The study of the mechanical properties of frozen rock is a basic problem that humans have to face in artificial low-temperature rock engineering and cold region rock engineering. There are few literatures on the dynamic constitutive models of frozen rocks under low-temperature gradients at home and abroad. In this paper, the constitutive model of water-saturated marble under the coupling effects of uniaxial impact compressive load and low-temperature is studied by theoretical analysis and experimental verification. Based on the theory of mechanical element combination, a rock constitutive model considering strain rate effect, damage softening effect and low-temperature effect is established, and the model parameters are determined by fitting method. The dynamic stress-strain curve of water-saturated marble at -30 °Cis predicted. The predicted results are in good agreement with the experimental results and the concordance correlation coefficient is 0.984092. The relevant results of this paper can provide a theoretical reference for the excavation and protection of rock engineering under negative temperature., Junzhe Li, Guang Zhang, Mingze Liu, Shaohua Hu and Xinlong Zhou., and Obsahuje bibliografii
This paper studies the constrained robust adaptive stabilization problem for a class of lower triangular systems with unknown control direction. A robust adaptive feedback control law for the systems is proposed by incorporating the technique of Barrier Lyapunov Function with Nussbaum gain. Such a controlled system arises from the study of the constrained robust output regulation problem for a class of output feedback systems with the unknown control direction and a nonlinear exosystem. An application of the constrained robust adaptive stabilization design leads to the solution of the constrained robust output regulation problem in the sense that the output tracking error is constrained within the prescribed barrier limit while asymptotically approaching to zero and the closed loop signals are all bounded for all the time. A numerical example is provided to illustrate the performance of the proposed control.
Ductile shear zone recorded valuable data about the progressive deformation and geodynamic setting of the earth crust. Analysis of the strain ratio on the deformed quartz grains in the samples of the Zagros orogenic shear zone indicated generally most of the strain ellipsoids shape are prolate and developed under constructional strain regime. Principal axes of the strain ellipticity ratio varied in the range between 2.04 to 3.12, shear strain magnitude analysis indicated εs are between “0.6 to 1.3”. Strain ellipsoid shape also revealed the propagation of the shear zone could not be coeval with the continental collision because in the collision region expected the ellipsoid shape to be oblate. Flattening strain regime in the Zagros Orogeny contemporaneous with the collisional event (D1 phase) and widespread in the Sanandaj-Sirjan Metamorphic Zone. Constructional conditions and prolate strain ellipsoid could be related to the post-collisional deformation phase (D2 phase). In this event stretching and shearing localized in the ductile shear zone and transtension structures superimposed on the former transpression structures. The deformation followed by third phase and brittle event (D3 phase) and caused to the propagation of veins. These veins somewhere cut the foliation and in the other place are parallel to foliation plane.
In this paper, we introduce two transformations on a given copula to construct new and recover already-existent families. The method is based on the choice of pairs of order statistics of the marginal distributions. Properties of such transformations and their effects on the dependence and symmetry structure of a copula are studied.
We construct two pairs (\A[1]F,\A[2]F) and (\A[1]ψ,\A[2]ψ) of ordered parametric families of symmetric dependence functions. The families of the first pair are indexed by regular distribution functions F, and those of the second pair by elements ψ of a specific function family \bpsi. We also show that all solutions of the differential equation dydu=α(u)u(1−u)y for α in a certain function family \balphas are symmetric dependence functions.
\noindent The number of n-gaussoids is shown to be a double exponential function in n. The necessary bounds are achieved by studying construction methods for gaussoids that rely on prescribing 3-minors and encoding the resulting combinatorial constraints in a suitable transitive graph. Various special classes of gaussoids arise from restricting the allowed 3-minors.
In this paper, the ordinal sum construction methods of implications on bounded lattices are studied. Necessary and sufficient conditions of an ordinal sum for obtaining an implication are presented. New ordinal sum construction methods on bounded lattices which generate implications are discussed. Some basic properties of ordinal sum implications are studied.
In this paper, two construction methods have been proposed for uni-nullnorms on any bounded lattices. The difference between these two construction methods and the difference from the existing construction methods have been demonstrated and supported by an example. Moreover, the relationship between our construction methods and the existing construction methods for uninorms and nullnorms on bounded lattices are investigated. The charactertics of null-uninorms on bounded lattice L are given and a contruction method is presented.
A method is presented making it possible to construct $po$-groups with a strong theory of quasi-divisors of finite character and with some prescribed properties as subgroups of restricted Hahn groups $H(\Delta ,\mathbb{Z})$, where $\Delta $ are finitely atomic root systems. Some examples of these constructions are presented.
Gröbner bases for modules are used to calculate a generalized linear immersion for a plant whose solutions to its regulation equations are polynomials or pseudo-polynomials. After calculating the generalized linear immersion, we build the controller which gives the robust regulation.