Borehole radar, due to its high resolution and extensive radial detection capability, has become an important geophysical tool for detecting complex subsurface fractures. The key to evaluating fracture detectability lies in accurate fracture modeling and numerical simulation. To overcome the limitations of conventional fracture modeling approaches, including geometric oversimplification, inadequate representation of aperture and fracture surface correlation, and incomplete characterization of roughness, we propose a multi-factor three-dimensional (3D) rough fracture modeling method. This method integrates two-dimensional (2D) image reconstruction with the Weierstrass-Mandelbrot (W-M) fractal function, which enables a comprehensive description of fracture geometry, surface roughness, aperture, and correlation between the surfaces of a fracture. Based on the developed models, full-wave electromagnetic simulations of borehole radar are conducted using the finite-difference time-domain (FDTD) method, and the effects of fracture attitudes on radar responses are systematically investigated. The simulation results indicate that variations in dip angle and dip direction significantly influence the characteristics of the borehole radar signals. Fracture surface roughness is also found to introduce perturbations in echo details. Furthermore, the radar migration imaging results are more conducive to the evaluation of fracture attitude, as systematic simulation analysis demonstrates a high morphological consistency between the radar migration imaging results and the geometric projection of the fracture onto the Borehole-Fracture Coupling Plane (BFCP). This is further confirmed by the centroid offset distance and the Intersection over Union (IoU). In addition, the “dip direction ambiguity” in omnidirectional borehole radar detection is revealed, where fractures symmetric about the BFCP generate highly similar radar responses, thereby increasing the difficulty of interpretation. The presented fracture modeling method and observed response patterns from fractures support the accurate detection of complex fractures using borehole radar.

With the increasing proportion of renewable energy integration in port areas, the trend of replacing conventional fossil energy load with electricity and hydrogen is becoming prominent, posing challenges to the safe operation of traditional port electrical systems. To address the above issues, firstly, we propose a novel architecture for a hybrid AC-DC electric-hydrogen coupling system, improving the scheduling flexibility. Then, we propose the energy management strategy considering multi-type hydrogen load dispatching based on the system, 100% local use of renewable energy is achieved. Lastly, we propose the equipment capacity configuration optimization method based on the strategy, considering various investment and operation costs of the port electric-hydrogen coupling system, which increases the annual income by 32.5% at an additional cost of only 6.3%, indicating great improvement in the economy while ensuing renewable energy consumption. The program is implemented on the MATLAB + YALMIP platform, and optimization models are solved using GUROBI. The simulation results validate the economic, low-carbon emissions and technical feasibility of the proposed system with its operation strategy and capacity configuration scheme.

Directional borehole radar (DBR) is a powerful tool for constructing the 3-D morphology of subsurface geological bodies. Direction of arrival (DOA) estimation is a key step in 3-D imaging. However, the existing DOA methods are constrained by factors such as DBR aperture, and can only identify one signal source within a time window. Consequently, when faced with multiple targets, DBR encounters challenges in effectively distinguishing them, especially when their echoes nearly overlap. In addition, the presence of interference waves makes echo overlap more likely to occur. So we propose a 3-D imaging method based on echo separation to solve this problem. This method first separates echoes of different targets through echo separation methods such as correlation method, deconvolution method, τ-ptransformation method, and moving window method. Subsequently, the azimuth is obtained through the multiple signal classification (MUSIC) algorithm, while the depth and radial distance are obtained through the inverse bi-static boundary scattering transform (IBBST), finally achieving the 3-D imaging of multiple geological targets. The effectiveness of the proposed method is demonstrated through synthetic data of both simple and complex fracture models, and its feasibility in practical applications is demonstrated through field data examination. This method improves the detection capability of DBR, opening up new possibilities for accurately mapping subsurface geological features.

As a major carbon emitter, how to create an effective path for low-carbon actions in the ports is extremely urgent. In view of the abundant renewable energy resources and hydrogen equipment in the ports, a multi-source output hydrogen storage coordination system in the ports is built to achieve the purpose of carbon reduction. From the perspective of multi-energy and low-carbon economic operation in the ports, an optimal operation method of multi-source output in the ports based on the optimal carbon emission flow(CEF) is proposed to take into account both carbon emission and economy. Based on the calculation method of the nodal carbon intensity of the power system, the calculation model of the carbon potential of the electric energy storage device and the electric hydrogen conversion device under the new power system is defined; Then, a multi-objective function with the lowest carbon emission and the maximum system economic benefit is established considering the influence of the charging and discharging depth and the number of cycles of the energy storage device; Finally, a non-dominated sorting genetic algorithm II (NSGA-II) is used to analyze a ports scenario integrated with new energy, electric energy storage equipment, and electric hydrogen conversion equipment. The results show that the proposed optimal operation method can effectively reduce the carbon emissions of the ports and improve the economy of the power system in the ports.

The emergence of directional borehole radar (DBR) has made it possible to obtain the 3-D morphology of fractures through a single borehole. The use of a uniform circular array (UCA) as the array receiving antenna is an important way to achieve directional detection; however, the direction of arrival (DOA) method and 3-D imaging method with DBR still have limitations in the imaging capability of rough fractures. We, therefore, propose a method of performing migration first and then DOA estimation next, combined with the moving window method (MWM), to achieve multitarget 3-D imaging, where the DOA estimation adopts the idea of applying the multiple signal classification (MUSIC) algorithm directly. We use the multigrid finite difference time domain (FDTD) method for numerical simulation to verify the effectiveness of the proposed 3-D imaging method. Subsequently, the response of DBR to rough fractures was studied, and the results showed that the roughness characteristics of fractures would significantly change the imaging results but also bring more fracture feature information; we can even detect the rough fracture under unfavorable dip angle. The research provides a theoretical basis for the detection of fractures under complex conditions and has practical application value in the future.

The 3-D airborne electromagnetic (AEM) inversions have been restricted by the modeling efficiency resulting from the complex geology in exploration areas and massive amount of data collected by AEM systems. In order to improve the modeling efficiency, we develop an algorithm that combines the hexahedral vector finite element (FE) with octree meshes, in which the boundary conditions are imposed via an algebraic constraint to ensure the continuity of the FE solution. This makes the division with hexahedral meshes more flexible for complex geology such as rugged topography or underground structures so that we can reduce the number of elements while maintaining the accuracy. After formulating the forward problem, we check the accuracy of our algorithm by taking a homogeneous half-space model and comparing the results of our octree method with the semianalytical solutions. Furthermore, we demonstrate the efficiency of our octree method by comparing with the traditional FE method using tetrahedral meshes. Finally, we subdivide a complex topography constructed using the 2-D Gaussian rough surface and calculate the EM responses with and without anomaly embedded. The results show that the EM responses are overwhelmed by the Earth topography. We carry out the topographic correction by taking a method based on the ratio of EM responses with and without anomaly. The experiments show that after topographic correction to AEM data, the response of anomaly becomes more distinguishable so that the anomaly can be clearly identified. Furthermore, we also calculate the EM response for a realistic model—the Ovoid Zone ore body located at Voisey’s Bay, Labrador, Canada, to verify the flexibility and practicality of our algorithm.

Borehole radar is a powerful tool for detecting subsurface fractures. Fracture modeling and numerical simulation are essential means to study fracture detectability. In this article, we first propose a method to construct a single fracture model, which combines the Baecher disk model and random rough surface and includes features, such as roughness, pinch-out, and irregularity. As the precise description of the fracture raises the requirement for accuracy of the simulation algorithm, the 3-D conformal finite-difference time-domain (CFDTD) method is used in this work. Numerical simulations of a sphere and rough fractures show that the CFDTD has higher calculation accuracy than conventional FDTD. Then, we analyzed how the fractures with different roughness affect the electromagnetic wave response. It is found that as the fracture surface becomes rougher, the wave scattered by it becomes stronger, more fracture contour-related information is obtained, and the fracture morphology is recovered better. Combined with accurate fracture modeling and high-precision numerical simulation, the electromagnetic response characteristics of different forms of fractures are obtained, which provides a basis for the accurate detection and interpretation of fractures in the future.