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In geosynchronous synthetic aperture radar (GEO SAR), the azimuth FM rate drastically falls and comes close to the variation rate of the Doppler centroid, due to the higher altitude. The effect of the variation of the Doppler parameters becomes significant and affects the azimuth resolution results. A concise azimuth resolution expression is deduced from the azimuth ambiguity function which involves the azimuth variance property and third-order range equation. It is more accurate for GEO SAR than the conventional expression. Meanwhile, the phenomenon where the traditional frequency algorithm becomes invalid is found. However, the time domain algorithm is still applicable when the azimuth FM rate approaches zero. Finally, the simulation results of the point targets at five typical areas verify the analysis.

Abstract An azimuth electromagnetic propagation logging while drilling tool provides the electrical parameters around a well in the intelligent drilling guidance system. It is a key link in intelligent guidance technology. As the stratum directivity parameter, the azimuth signal is associated with the compensation measurement of the resistivity instrument, which guides the drilling. However, it must be calibrated to have physical significance. The traditional method uses a water tank for calibration. However, this method is affected by the edge effect, which greatly weakens the azimuth signal. The model is complex and difficult to recover, which seriously suppresses the calibration results and causes errors in the azimuth signal. To eliminate the edge effect and simplify the model to improve the signal quality, an instrument calibration method based on sea level as the reflection interface is proposed in this paper. The air–seawater structure can simplify the calculation model, eliminate the edge effect and improve the signal strength. According to 1D air–seawater model simulation and 3D water tank model calculation, the feasibility of the simplified model is analyzed. According to the azimuth signal characteristics of the simplified model, an azimuth signal correction process that is more suitable for azimuth electromagnetic propagation logging while drilling is proposed. The measured data show that the air–seawater model improves the signal-to-noise ratio of the azimuth signal, verifies the detection ability of the azimuth antenna and provides technical support for oil and gas development in complex reservoirs.

The satellite–ground bistatic configuration, which uses geosynchronous synthetic aperture radar (GEO SAR) for illumination and ground equipment for reception, can achieve wide coverage, high revisit, and continuous illumination of interest areas. Based on the analysis of the signal characteristics of GEO satellite–ground bistatic SAR (GEO SG-BiSAR), it is found that the bistatic echo signal has problems of azimuth spectrum aliasing and 2-D spatial variability. Therefore, to overcome those problems, a novel SAR imaging method for a GEO SG-BiSAR system with severe azimuth spectrum aliasing and 2-D spatial variability is proposed. Firstly, based on the geometric configuration of the GEO SG-BiSAR system, the time-domain and frequency-domain expressions of the signal are derived in detail. Secondly, in order to avoid the increasing cost caused by traditional multi-channel reception technology and the processing burden caused by inter-channel errors, the azimuth deramping is executed to solve the azimuth spectrum aliasing of the signal under the special geometric structure of GEO SG-BiSAR. Thirdly, based on the investigation of azimuth and range spatial variability characteristics of GEO SG-BiSAR in the Range Doppler (RD) domain, the azimuth spatial variability correction strategy is proposed. The signal corrected by the correction strategy has the same migration characteristics as monostatic radar. Therefore, the traditional chirp scaling function (CSF) is also modified to solve the range spatial variability of the signal. Finally, the two-dimensional spectrum of GEO SG-BiSAR with modified chirp scaling processing is derived, followed by the SPECAN operation to obtain the focused SAR image. Furthermore, the completed flowchart is also given to display the main composed parts for GEO SG-BiSAR imaging. Both azimuth spectrum aliasing and 2-D spatial variability are taken into account in the imaging method. The simulated data and the real data obtained by the Beidou navigation satellite are used to verify the effectiveness of the proposed method.

The Gulong Sag in the northern Songliao Basin, China, possesses abundant shale oil resources and represents a highly prospective area for shale oil exploration. However, the Qingshankou formation shale oil reservoir within this region exhibits characteristics such as thin longitudinal thickness, pronounced horizontal heterogeneity, limited frequency range, and significant anisotropy that pose difficulties in accurately predicting the “sweet spot” of shale oil within the target interval. The azimuthal anisotropy characteristics of the target layer in the Qingshankou formation are analyzed in this manuscript, utilizing wide-azimuth and small bin seismic data from the Y3 research area. Considering the limitations of existing methods for fitting elliptical velocities in azimuthal anisotropy correction, the influence of azimuthal anisotropy time difference on the non-in-phase superposition of seismic in-phase axis is eliminated by employing a non-rigid dynamic matching method, thereby enhancing the resolution and imaging accuracy of seismic data. The azimuth anisotropy correction effectively broadens the frequency range of the stack profile by 7 Hz, thereby enhancing the reliability of data for shale oil reservoir prediction in the study area.

Accurate characterization of the fault system is crucial for the exploration and development of fractured reservoirs. The fault characterization technique based on multi-azimuth and multi-attribute fusion is a hotspot. In this way, the fault structures of different scales can be identified and the characterization details of complex fault systems can be enriched by analyzing and fusing the fault-induced responses in multi-azimuth and multi-type seismic attributes. However, the current fusion methods are still in the stage of violent information stacking in utilizing fault information of multi-azimuth and multi-type seismic attributes, and the fault or fracture semantics in multi-type attributes are not fully considered and utilized. In this work, we propose a physic-guided multi-azimuth multi-type seismic attributes intelligent fusion method, which can mine fracture semantics from multi-azimuth seismic data and realize the effective fusion of fault-induced abnormal responses in multi-azimuth seismic coherence and curvature with the cooperation of the deep learning model and physical knowledge. The fused result can be used for multi-azimuth comprehensive characterization for multi-scale faults. The proposed method is successfully applied to an ultra-deep carbonate field survey. The results indicate the proposed method is superior to self-supervised-based, principal-component-analysis-based, and weighted-average-based fusion methods in fault characterization accuracy, and some medium-scale and microscale fault illusions in multi-azimuth seismic coherence and curvature can be removed in the fused result.

The significance of the solar energy is to intensify the effectiveness of the Solar Panel with the use of a primordial solar tracking system. Here we propounded a solar positioning system with the use of the global positioning system (GPS) , artificial neural network (ANN) and image processing (IP) . The azimuth angle of the sun is evaluated using GPS which provide latitude, date, longitude and time. The image processing used to find sun image through which centroid of sun is calculated and finally by comparing the centroid of sun with GPS quadrate to achieve optimum tracking point. Weather conditions and situation observed through AI decision making with the help of IP algorithms. The presented advance adaptation is analyzed and established via experimental effects which might be made available on the memory of the cloud carrier for systematization. The proposed system improve power gain by 59.21% and 10.32% compare to stable system (SS) and two-axis solar following system (TASF) respectively. The reduced tracking error of IoT based Two-axis solar following system (IoT-TASF) reduces their azimuth angle error by 0.20 degree.

Accurate information about marsquake locations is crucial for understanding the tectonic activity, subsurface structures, and dynamics of Mars. We designed a varying‐parameter scheme for polarization analysis to determine the back‐azimuths of marsquakes. For two Martian meteorite impact events with ground‐truth locations known from orbital images, our scheme yields back‐azimuths that are ∼5° and ∼14° closer to the true values than those reported previously, demonstrating our method's advantages in constraining back‐azimuths. We applied this method to determine the back‐azimuths of 44 Low Frequency marsquakes and 39 were reliably relocated. Nearly half of these marsquakes occur in Cerberus Fossae, while the rest are broadly distributed, including along the dichotomy boundary and within the northern lowlands and southern highlands. Although further studies are required to understand the mechanisms of these marsquakes, the widespread seismicity implies that present‐day Mars, especially the ancient southern highlands, is more tectonically active than previously thought. Plain Language Summary Identifying seismic activity on Mars is crucial for advancing our understanding of the planet's present‐day properties and tectonic processes. From February 2019 to December 2022, the InSight seismograph captured nearly one hundred Low Frequency marsquakes. As these marsquakes have similar ground vibration characteristics to tectonic earthquakes, they are important to understand tectonic‐related activities on Mars. However, there is only a single seismograph on Mars, and some of the data for Low Frequency marsquakes are noisy, making it challenging to precisely determine their locations. To improve the accuracy of marsquake locations, we devised a scheme using sliding time and frequency windows to effectively constrain the orientation of marsquakes relative to the seismograph. With this method, we successfully relocated 39 Low Frequency marsquakes. Our new findings indicate that a significant portion, approximately half, of these marsquakes are concentrated in the Cerberus Fossae region, while the remaining events are distributed across various tectonic units. Interestingly, we have also identified marsquakes within the ancient southern highlands, an area that has previously had limited reports of seismic activity. Although the origin of marsquakes may differ from region to region, the widespread distribution of marsquakes suggests that Mars is more tectonically active than previously thought. Key Points The varying‐parameter polarization analysis scheme can effectively improve the accuracy of back‐azimuth estimates for marsquakes Several additional Low Frequency marsquakes have been identified within the southern highlands of Mars The widespread Martian seismicity implies that Mars is more tectonically active than previously thought

The paper presents a multi-directional inclined compartmental basin solar desalination system with a unique design aimed at enhancing water purification through solar energy. The system consists of a central basin surrounded by four inclined compartmental basins, each equipped with a thick glass cover of 4 mm tilted at a 30° angle to facilitate condensation. Techniques such as one-step azimuth tracking are employed, where the entire setup is rotated 15° daily to optimize solar exposure, improving distillate productivity. The methodology includes the construction of basins with pyramid-like structures to concentrate solar energy, increase water temperature rapidly, and maintain it for prolonged periods. Experimental tests were conducted at different orientations (0°, 15°, 30°, 45°, 60°, 75°, and 90°), measuring yields across basins and analyzing the effects of solar radiation and temperature. This innovative system, leveraging azimuth tracking and optimized basin configurations, offers a supportable solution for potable water production in solar-rich areas. The study’s results show that the multi-directional solar desalination system achieved its highest yield of 20.305 liters/day at a 0° orientation, with Basin 1 (south-facing) producing 5.780 liters/day. Rotating the setup to different angles (e.g., 15°, 30°) yielded minor increases (up to 0.90%) in overall productivity due to optimized solar exposure. The findings confirm that one-step azimuth tracking enhances daily distillate production in solar-rich environments.

In this paper, a practical non-stationary three-dimensional (3-D) channel models for massive multiple-input multiple-output (MIMO) systems, considering beam patterns for different antenna elements, is proposed. The beam patterns using dipole antenna elements with different phase excitation toward the different direction of travels (DoTs) contributes various correlation weights for rays related towards/from the cluster, thus providing different elevation angle of arrivals (EAoAs) and elevation angle of departures (EAoDs) for each antenna element. These include the movements of the user that makes our channel to be a non-stationary model of clusters at the receiver (RX) on both the time and array axes. In addition, their impacts on 3-D massive MIMO channels are investigated via statistical properties including received spatial correlation. Additionally, the impact of elevation/azimuth angles of arrival on received spatial correlation is discussed. Furthermore, experimental validation of the proposed 3-D channel models on azimuth and elevation angles of the polarized antenna are specifically evaluated and compared through simulations. The proposed 3-D generic models are verified using relevant measurement data.

A multi-channel synthetic aperture radar (SAR) on board a spaceplane orbiting near the top of the atmosphere is proposed to acquire images of cruising ships. Low pulse repetition frequency (PRF) is required for high-resolution wide-swath (HRWS) imaging, leading to inevitable problems of azimuth spectrum aliasing (ASA) and azimuth Doppler ambiguity (ADA). In this work, we propose a phase matching technique to solve the ASA problem in restoring the azimuth spectrum. A multi-stage compressive-sensing (CS) technique is also proposed to solve both ADA and ASA problems. Five similar types of cruising ship are simulated to verify the efficacy of the proposed approach, at different levels of signal-to-noise ratio. Indices of geometry match, intensity match, and structural similarity are used to identify different ships from the acquired SAR images.