Engineering

Failure analysis of borehole liners in soft coal seam for gas drainage
In this paper, loads acting on the liner in inserting installation, drainage lifetime and recycling operation were analyzed. Texts on axial deformation, radial compressive deformation and shear deformation properties of the liner were carried out by the universal testing machine. The correlation between the test results and the different loads was discussed. The influences of sieve opening dens...


Development and comparison of spectral methods for passive acoustic anomaly detection in nuclear power plants
We have developed spectral signal processing methods for passive acoustic anomaly detection in nuclear power plants. Furthermore, we compared the developed and existing methods by applying them to stationary sounds recorded in a controlled environment. Our new methods show significant improvement, in particular concerning robustness against false alarms. The results also demonstrate that clear ...
Piezo-driven thermoacoustic refrigerators with dynamic magnifiers
Thermoacoustic refrigeration is an emerging cooling technology which does not rely for in its operation on the use of any moving parts or harmful refrigerants. This technology uses acoustic waves to pump heat across a temperature gradient. The temperature gradient forms across the ends of a porous body, called the stack, enclosed in a resonator. The vast majority of thermoacoustic refrigerators...


Identification of winter tires using vibration signals generated on the road surface
During the winter, traffic regulations state that automobile drivers must use winter tires on unsafe roads such as snowy expressways. The present report is concerned with the development of an automatic tire identification system that can discriminate winter tires from summer tires with high accuracy. The system detects the impact vibration signal that is specifically generated by winter tires ...
Temperature and frequency dependence of the visco-elasticity of a poro-elastic layer
Besides their structural complexity, the acoustic behavior of polymer-based poro-elastic layers is complicated also due to their frequency dependent elasticity. In this work, we address the frequency and temperature dependence of the elastic behavior in general, and the shear modulus in particular, of poro-visco-elastic materials. The analysis is based on the monitoring of mechanically excited ...


Objective assessment of the sound paths through earmuff components
This paper proposes an objective measurement methodology to assess the sound transmission paths through various earmuff components (cup, cushion, back-plate, foam insert, silicone flesh) and estimate the vibroacoustic couplings between them. The measurement methodology is applied to two different commercial earmuffs. For each Hearing Protection Device (HPD), the different sound paths are assess...
Highway-rail grade crossing safety challenges for shared operations of high-speed passenger and heavy freight rail in the U.S
This study presents an overview of the challenges of grade crossings to shared high-speed rail (HSR) passenger and heavy-axle-load (HAL) freight operations in the U. S., as well as an in-depth analysis of the relevant research to date, through an extensive literature review. from this study are expected to identify principal technical challenges related to grade crossings in developing HSR syst...

Simplified modeling of cracking in concrete: Application in tunnel linings
This paper presents a formulation for the analysis of the inelastic behavior of pipes, tunnels and rings. This new framework is based on lumped damage mechanics and emphasizes on the mathematical description of concrete cracking; the approach can be extended to other brittle materials as well. Lumped damage mechanics combines the concept of plastic hinge with the ideas and procedures of fractur...
Model predictive control for a class of systems with isolated nonlinearity
The paper is concerned with an overall convergent nonlinear model predictive control design for a kind of nonlinear mechatronic drive systems. The proposed nonlinear model predictive control results in the improvement of regulatory capacity for reference tracking and load disturbance rejection. The design of the nonlinear model predictive controller consists of two steps: the first step is to d...

The Flow Field and Free Surface Pattern of the Submerged Side Weir with Different Lengths
A side weir is set in the side of a channel and is used for water level control, diverting excess water, as in sewage systems. In this study, firstly, a numerical simulation for prediction-free surface turbulent flow over the sharp crest side weir was performed by commercial software using the volume of fluid scheme and Reynolds-stress model (RSM) turbulence model. Comparison between numerical ...
Blending of Poly(ethyl methacrylate) with Poly(2-hydroxy-3-phenoxypropyl methacrylate): Thermal and Optical Properties
The miscibility behavior of poly(ethyl methacrylate) [poly(EMA)] with poly(2-hydroxy-3-phenoxypropyl methacrylate) [poly(PPMA)] was studied by DSC technique. Thermogravimetric analysis was used to investigate the thermal degradation mechanism and activation energies for initial decomposition process under non-isothermal conditions by integral approximation methods. The reaction mechanism of dec...

Multiaxial deformation and strain-induced crystallization around a fatigue crack in natural rubber
The study of fatigue crack propagation in elastomers is an essential prerequisite to improve the service life of tire products. Natural rubber is a key compound in tires, because of its unique mechanical properties and more particularly its remarkable resistance to fatigue crack growth as compared to synthetic rubbers. To explain this resistance, the literature often mentions the phenomenon of ...
Characterizations of efficient and weakly efficient points in nonconvex vector optimization
In this paper, a class of nonconvex vector optimization problems with inequality constraints and a closed convex set constraint are considered. By means of Clarke derivatives and Clarke subdifferentials, a necessary and sufficient condition of weak efficiency and a sufficient criteria of efficiency are presented under suitable generalized convexity. A special case is discussed in finite dimensi...
Global optimization of general nonconvex problems with intermediate polynomial substructures
This work considers the global optimization of general nonconvex nonlinear and mixed-integer nonlinear programming problems with underlying polynomial substructures. We incorporate linear cutting planes inspired by reformulation-linearization techniques to produce tight subproblem formulations that exploit these underlying structures. These cutting plane strategies simultaneously convexify line...
The J and M integrals for a cylindrical cavity in a time-harmonic wave field
The invariant integrals are being widely used in the study of defects and fracture mechanics, mostly in elastostatics. However, the properties and the interpretation of these integrals in elastodynamics, especially in the case of time-harmonic excitation, remain unexplored. This contribution is focused on the derivation of the time average J integral for a cylindrical inhomogeneity and the M in...