Grounding systems are fundamental components of protection systems for electrical systems and equipment, with a top priority assigned to their economic design. The ground resistance of ground-enhancement-material (GEM)-encased vertical and horizontal rods buried in a uniform soil is calculated based on the current sphere simulation technique (CSST). A relationship between ground resistance and the associated cost of rod installation is formulated to form an objective function for optimizing the ground resistance. For a vertical rod of 1.44 m in length and 16 mm in diameter, encased by GEM shell with diameter of 0.2 m and length of 1.5 m, the calculated ground resistance is 102% of that obtained by COMSOL. For a horizontal rod with the same dimensions, buried at a depth of 0.6 m, the optimal ground resistance is 108.6% of that of the vertical rod. However, the cost for the horizontal rod is almost 70% of that of the vertical rod at the optimal solution.

This paper is aimed at proposing a method for the first-time to calculate the resistance-to-ground of a GEM- encased vertical-rod buried in a homogeneous high resistivity soil. The calculation method is based on the current sphere simulation technique along with the concept of images. The current discharged from the rod into the surrounding GEM is simulated by current spheres, whose diameter is the same as that of the rod. The current through the interface separating the GEM from soil is simulated by two sets of equal number of current spheres. Satisfaction of Dirichlet boundary condition at boundary points on the rod surface and normal current-density continuity along with potential equality boundary conditions at boundary points on the interface formulates a set of equations, whose solution determines the currents of simulation-spheres. The sum of sphere-currents simulating the rod is the current discharged from rod for evaluating ground resistance. The calculated ground resistance after nine weeks for a rod encased in GEM of resistivity 3.39 Ω.m and soil with resistivity 1678 Ω.m records a 47.86% reduction compared to the resistance without GEM. On the other hand, the COMSOL and the experiment predict 44.61% and 49.75% reduction in the ground resistance, respectively

This paper presents the design, implementation, and experimental validation of an Internet-of-Things (IoT)-based Structural Health Monitoring (SHM) system for suspension bridges using synchronized vibration measurements. The proposed framework integrates distributed MEMS-based sensing nodes, GPS-assisted time synchronization, low-power wireless communication, and cloud-based modal analysis to support continuous monitoring of structural conditions. The main contribution of this work is the end-to-end integration of synchronized low-power IoT sensing, multi-tier wireless communication, and cloud-based vibration analysis within a unified SHM framework, together with experimental validation on a laboratory-scale suspension bridge. In the proposed system, each leaf node incorporates a high-accuracy digital accelerometer, ESP-NOW communication, and a duty-cycled sleep mode to reduce power …