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1.
In order to extend the rail life and improve the firing accuracy,the electromagnetic launcher' s rail can be modeled as a beam on elastic foundation with simply supported beam with moving load.Euler be... 相似文献
2.
A fundamental property of solid materials is their stress state. Stress state of a solid or thin film material has profound effects on its thermodynamic stability and physical and chemical properties. The classical mechanical stress(δM) originates from lattice strain(m), following Hooke's law: δM=Cδ, where C is elastic constant matrix. Recently, a new concept of quantum electronic stress(δ QE) is introduced to elucidate the extrinsic electronic effects on the stress state of solids and thin films, which follows a quantum analog of classical Hooke's law: QE=δ(δn), where δis the deformation potential of electronic states and n is the variation of electron density. Here, we present mathematical derivation of both the classical and quantum Hooke's law from density functional theory. We further discuss the physical origin of quantum electronic stress, arising purely from electronic excitation and perturbation in the absence of lattice strain(ε=0), and its relation to the degeneracy pressure of electrons in solid and their interaction with the lattice. 相似文献
3.
张俊芝 《武汉理工大学学报(材料科学英文版)》2010,(1)
According to the existing concrete core samples obtained in site, chloride concentration and porosity of existing normal hydraulic concrete were measured, and chloride diffusivity in existing hydraulic concrete was studied. By Fick’s second law, the chloride diffusion coefficients in the steady diffusion area were calculated. The chloride diffusion of different mix proportion concrete was tested, and chloride diffusion coefficients and porosities of freshly concrete were measured, moreover, the relationship... 相似文献
4.
Whendesignedandoperatedeffectively ,FMScanbeofassistancetomanufacturersaccordingtodefinedproduc tionandprocessplans ,whichspecifytheactivitiesandresourcesaswellassequencerelatedconditions ,suchasprecedencerelationsandsynchronization .Alternativere sourcesandroutingforsomeofthejobsinFMSmaybespecifiedpreviously .Thisresultsinanincreasingflexibil ityinjobscheduling .Someresourceallocationsmayleadtodeadlocksituations ,inparticularwhentheresourcesinsystemarelimited .Deadlockproblemscancauseunnec… 相似文献
5.
FromEinstein’s supposition aboutcrystal lattice vi-bration, which states that the vibration frequency of ev-ery crystal lattice is the same, the balance of heat ener-gy in the crystal can be written out using the theory ofstatistical thermodynamics, so that the molar heat capac-ity under normal temperatures can be easily calculated.For many kinds of metals, the theoretical value of themolar heat capacity is close to the experimental value.In other kinds of metals, though, especially metals of… 相似文献
6.
In order to predict blended coal’s property accurately, a new kind of hybrid prediction model based on principal component analysis (PCA) and support vector machine (SVM) was established. PCA was used to transform the high-dimensional and correlative influencing factors data to low-dimensional principal component subspace. Well-trained SVM was used to extract influencing factors as input to predict blended coal’s property. Then experiments were made by using the real data, and the results were compared with weighted averaging method (WAM) and BP neural network. The results show that PCA-SVM has higher prediction accuracy in the condition of few data, thus the hybrid model is of great use in the domain of power coal blending. 相似文献
7.
The synthesis of Friedel’s salt(FS: 3Ca O·A12O3·Ca Cl2·10H2O) by the reaction of calcium chloride with sodium aluminate was investigated. Factors affecting the preparation of Friedel’s salt, such as reaction temperature, initial concentration, titration speed, aging time and molar Ca/Al ratio were studied in detail. XRD, SEM images and particle size distribution show that the reaction temperature, aging time and molar Ca/Al ratio have significant effect on the composition, crystal morphology, and average particle size of the obtained samples. In addition, the initial Ca Cl2 concentration and Na Al O2 titration speed do not significantly influence the morphology and particle size distribution of Friedel’s salt. With the optimization of the operating conditions, the crystals can grow up to a average size of about 28 um, showing flat hexagonal(or pseudohexagonal) crystal morphology. Moreover, two potential mechanisms of Friedel’s salt formation including adsorption mechanism and anion-exchange mechanism were discussed. In the adsorption mechanism, Friedel’s salt forms due to the adsorption of the bulk Cl- ions present in the solution into the interlayers of the principal layers, [Ca2Al(OH-)6·2H2O]+, in order to balance the charge. In the anion-exchange mechanism, the free-chloride ions bind with the AFm(a family of hydrated compounds found in cement) hydrates to form Friedel’s salt by anion-exchange with the ions present in the interlayers of the principal layer, [Ca2Al(OH-)6· 2H2O]+-OH-. 相似文献