Geologic hazards (geohazards) are naturally occurring or human-activity-induced geologic conditions capable of causing damage or loss of property and/or life. geohazards, such as landslides, surface subsidence, and earthquakes, can seriously affect and threaten life, property, or public safety. geohazards prevention is the application of geologic engineering principles and existing and emerging technologies to reduce, minimize, or prevent the effects of various geologic hazards. Monitoring and early warning are the most common strategies for geohazards prevention. With the development of the Internet of Things (IoT), an emerging new idea is to apply IoT technology to enhance the accuracy and efficiency of monitoring and early warning systems for geohazards prevention. This article aims to present a comprehensive survey of relevant research and technological developments of the IoT applied in geohazards prevention. It first surveys the applications of the IoT in the monitoring and early warning of seven types of common geohazards, including landslides, debris flow, rockfall, surface subsidence, surface collapse, surface cracks, and earthquakes, then investigates the key technologies in geohazards prevention when utilizing the IoT, and finally summarizes the challenges in IoT-based monitoring and early warning systems for geohazards prevention. Moreover, this article also highlights the future directions for employing the IoT for geohazards prevention.

A Survey of Internet of Things (IoT) for Geohazard Prevention: Applications, Technologies, and Challenges

In this article, we consider a problem of the surface elastic wave propagation within the framework of the isotropic Cosserat continuum. The medium deformation in this model is described not only by the displacement vector but also by a kinematically independent rotation vector. We discuss the general solution of equations of motion. This solution describes the following wave types: longitudinal and transverse bulk waves, Rayleigh wave, surface transverse wave in a half-space as well as Lamb wave and transverse wave in a thin layer. Within the framework of Cosserat continuum, both the Rayleigh and surface transverse waves in a half-space are dispersive. The transverse wave in a thin layer and the surface transverse wave in a half-space do not have any analogies in the classical elasticity theory.

Waves in Linear Elastic Media with Microrotations, Part 2: Isotropic Reduced Cosserat Model

Waves in Linear Elastic Media with Microrotations, Part 2: Isotropic Reduced Cosserat ModelShort Note

Active damping of laminated cylindrical shells conveying fluid using 1–3 piezoelectric composites

The beam-mode stability of periodic functionally-graded-material shells conveying fluid

We consider a finite element algorithm intended to study the dynamic behavior of an elastic cylindrical shell filled with an immovable or flowing fluid. To describe the fluid, we use the perturbed velocity potential whose equations with the corresponding boundary conditions are solved by the Bubnov-Galerkin method. To describe the shell, we use the variation principle, which includes the linearized Bernoulli equation for calculating the hydrodynamic pressure acting on the shell on the side of the fluid. Solving the problem is reduced to calculating and analyzing the eigenvalues of the coupled system of equations obtained as a result of combining the equations for the perturbed velocity potential and the shell displacements. We consider several test problems in which, along with the comparison of the computational results with the earlier published experimental, analytic, and numerical data, we also study the dynamic behavior of the “shell-fluid” system for various boundary conditions for the perturbed velocity potential.

Numerical study of the influence of boundary conditions on the dynamic behavior of a cylindrical shell conveying a fluid

We present numerical results for dynamical stability of loaded coaxial shells of revolution interacting with the internal fluid flow. The motion of the incompressible fluid is described in the framework of the theory of frictionless potential flow, whereas the static load acting on the shells is caused by the steady forces of viscous drag arising in the viscous turbulent flow in a closed channel. For shells with different boundary conditions, we study how the stability boundary is affected by the value of the gap between the shells for different versions of the outer shell rigidity and fluid flow. We show that, as in the case of unloaded coaxial shells, there is a significant deviation from the previous numerical and analytical results.

Stability analysis of loaded coaxial cylindrical shells with internal fluid flow

Experimental results of strain field measurement in polymer composite specimens by Bragg grating fiber optic strain sensors embedded in the material are considered. A rectangular plate and a rectangular plate with “butterfly” shaped cuts are used as specimens. The results of uniaxial strain experiments with rectangular plates show that fiber optic strain sensors can be used to measure the strains, and these results can be used to calculate the calibration coefficients for fiber optic strain sensors. A gradient strain field is attained in a plate with cuts, and the possibility of measuring this field by fiber optic strain sensors is the main goal of this paper. The results of measurements of gradient strain fields in the plate with cuts are compared with the results obtained by using the three-dimensional digital optic system Vix-3D and with the results of numerical computations based on finite element methods. It is shown that the difference between the strain values obtained by these three methods does not exceed 5%.

Measurement of inhomogeneous strain fields by fiber optic sensors embedded in a polymer composite material

A mixed finite-element algorithm is proposed to study the dynamic behavior of loaded shells of revolution containing a stationary or moving compressible fluid. The behavior of the fluid is described by potential theory, whose equations are reduced to integral form using the Galerkin method. The dynamics of the shell is analyzed with the use of the variational principle of possible displacements, which includes the linearized Bernoulli equation for calculating the hydrodynamic pressure exerted on the shell by the fluid. The solution of the problem reduces to the calculation and analysis of the eigenvalues of the coupled system of equations. As an example, the effect of hydrostatic pressure on the dynamic behavior of shells of revolution containing a moving fluid is studied under various boundary conditions.

V. P. Matveenko

Papers

Numerical study of the influence of boundary conditions on the dynamic behavior of a cylindrical shell conveying a fluid

Stability analysis of loaded coaxial cylindrical shells with internal fluid flow

Measurement of inhomogeneous strain fields by fiber optic sensors embedded in a polymer composite material

Numerical modelling of the stability of loaded shells of revolution containing fluid flows

Investigation of Stress Behavior in the Vicinity of Singular Points of Elastic Bodies Made of Functionally Graded Materials