Primary and secondary tools’ life evaluation for soft ground TBMs

Bulletin of Engineering Geology and the Environment - Tool wear and tool life are very important issues for soft ground tunnel boring machines (TBMs) as they are directly related to the time and...     

Participatory Water-Food-Energy Nexus Approach for Evaluation and Design of Groundwater Governance

Water Resources Management - Improving the groundwater governance structure can help reduce groundwater decline and improve the state of an aquifer. This study develops an approach to modify...     

Interfacial lubricating effect in phase coarsening of polyethylene/polycaprolactone/polyethylene oxide tri-continuous polymer blends

This work aims at studying the mechanism involved in the phase coarsening of ternary tri-continuous polymer blends. To this aim, the phase coarsening behaviors of a co-continuous polyethylene (PE)/polyethylene oxide (PEO) blend, and a tri-continuous PE/polycaprolactone (PCL)/PEO blend during the quiescent annealing process are studied. Rheological characterization showed that the zero-shear viscosities of PE and PCL phases were similar but much less than the zero-shear viscosity of the PEO phase. The evolution of the microstructure of the blends during annealing was characterized using a characteristic length scale (λ). It was found that λ in both co- and tri-continuous blends increased linearly in the early stages of annealing but the phase coarsening rate decreased in both systems at longer annealing times. In general, the tri-continuous blend showed much faster phase coarsening rate. The effects of kinetic and thermodynamic parameters on the observed phase coarsening behaviors are discussed in detail. A new lubricating mechanism is proposed in which the deformation of the PCL layer between PE and PEO phases reduces the effect of high viscosity of the PEO phase and increases the phase coarsening rate in ternary blends. The obtained results provide a new insight into the role of the middle layer in tri-continuous polymer blends on controlling the phase morphology of these systems.     

Reduce energy consumption in sensors using a smartphone,smartwatch, and the use of SFLA algorithms (REC-SSS)

The Journal of Supercomputing - Wireless body area networks are a technology for remote medical care. Because of the limited energy of the sensors, one of the problems of long-distance medical care...     

Phosphonated graphene oxide with high electrocatalytic performance for vanadium redox flow battery

Development of more efficient electrodes is essential to improve the competitiveness of vanadium redox flow battery (VRFB) systems. Covalent functionalization of carbon structure in graphene oxide with phosphonic acid groups was carried out to enhance the electrode wettability. The phosphonated graphene oxide (P-GO) was characterized and found displaying an improved electrocatalytic performance towards electrooxidation/electroreduction of vanadium ion pairs. The defect in P-GO structure increased the negative charge density on the surface leading to higher vanadium ions tendency for electrooxidation/electroreduction reactions. The battery performance was evaluated using electrodes made of carbon felt hosted GO and P-GO in a single cell VRFB and 180 charge-discharge cycles were recorded. The VRFB with P-GO displayed an improved performance and stable coulombic, voltage and energy efficiency compared to VRFB with GO.     

Numerical modeling of discontinuous rock slopes utilizing the 3DDGM (three-dimensional discontinuity geometrical modeling) method

The geometry of discontinuities in a rock mass is one of the most important influences on the behavior and characteristics of that rock mass. The geometry of discontinuities largely determines the stability of the rock mass, as well as appropriate methods for reinforcing and stabilizing that mass. This study introduces the 3DDGM (three-dimensional discontinuity geometrical modeling) method, which is based on the 3DGM (three-dimensional geometrical modeling) algorithm that was developed using the Mathematica software package. The 3DDGM method provides essential input data for the stability analysis of a discontinuous rock mass using block stability assessment techniques or block modeling codes. The 3DDGM method developed in the present work was designed to model discontinuities in rock masses and to provide accurate values for discontinuity parameters (i.e., location, spacing, separation, system, orientation, etc.). This algorithm was developed to increase the accuracy of the discontinuity model based on the Heliot algorithm. The 3DDGM algorithm was tested by applying it to a real case, the sloping discontinuous rock mass at the phase 7 gas flare site in the South Pars Gas Complex in Assalouyeh, Iran, and the algorithm was successful in providing a three-dimensional model of the discontinuities in the rock mass at the site.     

A state-of-the-art review of automated extraction of rock mass discontinuity characteristics using three-dimensional surface models

In the last two decades, significant research has been conducted in the field of automated extraction of rock mass discontinuity characteristics from three-dimensional (3D) models. This provides several methodologies for acquiring discontinuity measurements from 3D models, such as point clouds generated using laser scanning or photogrammetry. However, even with numerous automated and semi-automated methods presented in the literature, there is not one single method that can automatically characterize discontinuities accurately in a minimum of time. In this paper, we critically review all the existing methods proposed in the literature for the extraction of discontinuity characteristics such as joint sets and orientations, persistence, joint spacing, roughness and block size using point clouds, digital elevation maps, or meshes. As a result of this review, we identify the strengths and drawbacks of each method used for extracting those characteristics. We found that the approaches based on voxels and region growing are superior in extracting joint planes from 3D point clouds. Normal tensor voting with trace growth algorithm is a robust method for measuring joint trace length from 3D meshes. Spacing is estimated by calculating the perpendicular distance between joint planes. Several independent roughness indices are presented to quantify roughness from 3D surface models, but there is a need to incorporate these indices into automated methodologies. There is a lack of efficient algorithms for direct computation of block size from 3D rock mass surface models.