Offset Features Research Articles

Human Multi-Activities Classification Using mmWave Radar: Feature Fusion in Time-Domain and PCANet.

This study introduces an innovative approach by incorporating statistical offset features, range profiles, time-frequency analyses, and azimuth-range-time characteristics to effectively identify various human daily activities. Our technique utilizes nine feature vectors consisting of six statistical offset features and three principal component analysis network (PCANet) fusion attributes. These statistical offset features are derived from combined elevation and azimuth data, considering their spatial angle relationships. The fusion attributes are generated through concurrent 1D networks using CNN-BiLSTM. The process begins with the temporal fusion of 3D range-azimuth-time data, followed by PCANet integration. Subsequently, a conventional classification model is employed to categorize a range of actions. Our methodology was tested with 21,000 samples across fourteen categories of human daily activities, demonstrating the effectiveness of our proposed solution. The experimental outcomes highlight the superior robustness of our method, particularly when using the Margenau-Hill Spectrogram for time-frequency analysis. When employing a random forest classifier, our approach outperformed other classifiers in terms of classification efficacy, achieving an average sensitivity, precision, F1, specificity, and accuracy of 98.25%, 98.25%, 98.25%, 99.87%, and 99.75%, respectively.

Fault slip behavior and segmentation revealed by geomorphic offset clusters: An example from the middle Riganpei Co fault, central Tibet

High-resolution topographic datasets are useful for revealing offset features of fault geomorphology and are thus important for reconstructing the evolution history of faults. The Riganpei Co fault, located in the central Tibetan Plateau, is an important active fault on the northern boundary of the Bangong-Nujiang suture zone. In this study, WorldView-2 stereo images were used to generate high-resolution topographic data in a 1 km range on both flanks of the middle section of the Riganpei Co fault. We interpreted the tectonic geomorphology along the fault, classified it into distinct units, and measured the horizontal displacement of each unit. Within approximately 70 km along the fault, we obtained 396 displacement measurements ranging from 0 to 60 m. Given the evident uneven distribution of displacement, the fault was divided into four segments. In each fault segment, the reconstructed slip distributions revealed a tendency of larger displacements in the center and smaller displacements toward the ends. The cumulative offset probability distribution (COPD) of displacements displays 4–5 offset clusters in the range of 0–30 m for each segment, suggesting that at least four large earthquakes ruptured this fault. The binned COPD demonstrated that there are differences in the displacement accumulation modes among these fault segments, where the middle segment follows a characteristic slip accumulation mode. Reconstructed cumulative slip profiles revealed a complex pattern of strong earthquake activities along the Riganpei Co fault.

CEST and nuclear Overhauser enhancement imaging withdeep learning-extrapolated semisolid magnetization transfer reference: Scan-rescan reproducibility andreliability studies.

To develop a novel MR physics-driven, deep-learning, extrapolated semisolid magnetization transfer reference (DeepEMR) framework to provide fast, reliable magnetization transfer contrast (MTC) and CEST signal estimations, and to determine the reproducibility and reliability of the estimates from the DeepEMR. A neural network was designed to predict a direct water saturation and MTC-dominated signal at a certain CEST frequency offset using a few high-frequency offset features in the Z-spectrum. The accuracy, scan-rescan reproducibility, and reliability of MTC, CEST, and relayed nuclear Overhauser enhancement (rNOE) signals estimated from the DeepEMR were evaluated on numerical phantoms and in heathy volunteers at 3 T. In addition, we applied the DeepEMR method to brain tumor patients and compared tissue contrast with other CEST calculation metrics. The DeepEMR method demonstrated a high degree of accuracy in the estimation of reference MTC signals at ±3.5 ppm for APT and rNOE imaging, and computational efficiency (˜190-fold) compared with a conventional fitting approach. In addition, the DeepEMR method achieved high reproducibility and reliability (intraclass correlation coefficient = 0.97, intersubject coefficient of variation = 3.5%, and intrasubject coefficient of variation = 1.3%) of the estimation of MTC signals at ±3.5 ppm. In tumor patients, DeepEMR-based amide proton transfer images provided higher tumor contrast than a conventional MT ratio asymmetry image, particularly at higher B1 strengths (>1.5 μT), with a distinct delineation of the tumor core from normal tissue or peritumoral edema. The DeepEMR approach is feasible for measuring clean APT and rNOE effects in longitudinal and cross-sectional studies with low scan-rescan variability.

Evolution of slip partitioning in a major continental margin strike-slip fault system during a transition to oblique plate-margin tectonics: Insight into the evolution of the Garlock fault zone, California (USA)

Abstract The Walker Lane belt and Eastern California shear zone of California, USA, are active, plate boundary–related dextral systems with transtensional and transpressional deformation, respectively. They are separated by the sinistral Garlock fault, creating a complex system without an overall integrated formation and evolution model. We examine the deformation within the eastern segment of the Garlock fault zone over geologic timescales by determining the slip history of faults. We assess the progression of faulting and associated deformation along the WSW-striking Garlock fault zone and how it applies to the overall NNW-directed dextral system. Previous studies found that large synthetic fault strands take up 30% of the slip of the Garlock fault zone and have proposed multiple mechanisms to explore how to accommodate regional NNW-directed shear across the Garlock fault without cutting its trace. We analyze an unstudied section of faulting in one of the more complex areas of regional deformation via compiled and reinterpreted published geologic data for an analysis of total and incremental slip on the main faults of the eastern Garlock fault zone. We identify geologic offset features to interpret total slip, timing, and deformation evolution. We find that 30% of the total slip of the Garlock zone occurs on strands other than the Garlock fault sensu stricto, with the locus of main slip sidestepping during the evolution of accommodation of throughgoing, regional dextral shear. Our results support ideas of the creation and evolution of the regional dextral system via stress concentration on a sub-Garlock lithospheric anisotropy with a resulting lowering of the plastic yield stress. Our results also show an eastward increase in fault system complexity, which may imply an underappreciated seismic hazard of the eastern Garlock fault zone.

Real-Time Human Action Recognition Using Locally Aggregated Kinematic-Guided Skeletonlet and Supervised Hashing-by-Analysis Model.

3-D action recognition is referred to as the classification of action sequences which consist of 3-D skeleton joints. While many research works are devoted to 3-D action recognition, it mainly suffers from three problems: 1) highly complicated articulation; 2) a great amount of noise; and 3) low implementation efficiency. To tackle all these problems, we propose a real-time 3-D action-recognition framework by integrating the locally aggregated kinematic-guided skeletonlet (LAKS) with a supervised hashing-by-analysis (SHA) model. We first define the skeletonlet as a few combinations of joint offsets grouped in terms of the kinematic principle and then represent an action sequence using LAKS, which consists of a denoising phase and a locally aggregating phase. The denoising phase detects the noisy action data and adjusts it by replacing all the features within it with the features of the corresponding previous frame, while the locally aggregating phase sums the difference between an offset feature of the skeletonlet and its cluster center together over all the offset features of the sequence. Finally, the SHA model combines sparse representation with a hashing model, aiming at promoting the recognition accuracy while maintaining high efficiency. Experimental results on MSRAction3D, UTKinectAction3D, and Florence3DAction datasets demonstrate that the proposed method outperforms state-of-the-art methods in both recognition accuracy and implementation efficiency.

GeometryMotion-Net: A Strong Two-Stream Baseline for 3D Action Recognition

In this work, we propose a strong two-stream baseline method referred to as GeometryMotion-Net for 3D action recognition. For efficient 3D action recognition, we first represent each point cloud sequence as a limited number of randomly sampled frames with each frame consisting of a sparse set of points. After that, we propose a new two-stream framework for effective 3D action recognition. For the geometry stream, we propose a new module to produce a virtual overall geometry point cloud by first merging all 3D points from these selected frames, and then we exploit local neighborhood information of each point in the feature space. In the motion stream, for any two neighboring point cloud frames, we also propose a new module to generate one virtual forward motion point cloud and one virtual backward motion point cloud. Specifically, for each point in the current frame, we first produce a set of 3D offset features relative to the neighboring points in the reference frame ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i.e.</i> , the previous/subsequent frame) and then exploit local neighborhood information of this point in the offset feature space. Based on the newly generated virtual overall geometry point cloud and multiple virtual forward/backward motion point clouds, any existing point cloud analysis methods ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e.g.</i> , PointNet) can be readily adopted for extracting discriminant geometry and bidirectional motion features in the geometry and motion streams, respectively, which are further aggregated to make our two-stream network trainable in an end-to-end fashion. Comprehensive experiments on both large-scale datasets ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i.e.</i> NTU RGB+D 60 and NTU RGB+D 120) and small-scale datasets ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i.e.</i> , N-UCLA and UWA3DII) demonstrate the effectiveness and efficiency of our two-stream network for 3D action recognition.

STEPS: Slip Time Earthquake Path Simulations Applied to the San Andreas and Toe Jam Hill Faults to Redefine Geologic Slip Rate Uncertainty

AbstractGeologic slip rates are a time‐averaged measurement of fault displacement calculated over hundreds to million‐year time scales and are a primary input for probabilistic seismic hazard analyses, which forecast expected ground shaking in future earthquakes. Despite their utility for seismic hazard calculations, longer‐term geologic slip rates represent a time‐averaged measure of the tempo of strain release and do not measure variability across earthquake cycles. We have developed a numerical approach called STEPS (Slip Time Earthquake Path Simulations), which is built upon field‐based observations and explicitly incorporates realistic variations in displacement per event and variability in the recurrence interval between earthquakes. The STEPS approach, which simulates strain release through time, relies on representing earthquake cycles as stairsteps, rather than straight‐line paths, connecting per earthquake time‐displacement coordinates. We simulate earthquake histories based on these input constraints using two examples: the Carrizo section of the San Andreas fault and the Toe Jam Hill fault of the Seattle fault zone. We find that modeled slip rate distributions agree with slip rates reported for the sites of interest by the original investigators, while providing a slip rate distribution that reflects the variability of earthquake frequency and displacement. The STEPS approach provides an estimate of fault slip rate uncertainty based on a synthetic suite of plausible time‐displacement paths resulting from individual earthquakes, rather than measurement uncertainties associated with offset features. When considering this simulated earthquake behavior between measurements, the uncertainty associated with earthquake paths is greater than that calculated by the long‐term rate.

IQ-Data-Based WiFi Signal Classification Algorithm Using the Choi-Williams and Margenau-Hill-Spectrogram Features: A Case in Human Activity Recognition

This paper presents a novel approach that applies WiFi-based IQ data and time–frequency images to classify human activities automatically and accurately. The proposed strategy first uses the Choi–Williams distribution transform and the Margenau–Hill spectrogram transform to obtain the time–frequency images, followed by the offset and principal component analysis (PCA) feature extraction. The offset features were extracted from the IQ data and several spectra with maximum energy values in the time domain, and the PCA features were extracted via the whole images and several image slices on them with rich unit information. Finally, a traditional supervised learning classifier was used to label various activities. With twelve-thousand experimental samples from four categories of WiFi signals, the experimental data validated our proposed method. The results showed that our method was more robust to varying image slices or PCA numbers over the measured dataset. Our method with the random forest (RF) classifier surpassed the method with alternative classifiers on classification performance and finally obtained a 91.78% average sensitivity, 91.74% average precision, 91.73% average F1-score, 97.26% average specificity, and 95.89% average accuracy.

Rapid Postearthquake Field Reconnaissance, Paleoseismic Trenching, and GIS-Based Fault Slip Variability Measurements along the Mw 6.4 and Mw 7.1 Ridgecrest Earthquake Sequence, Southern California

ABSTRACTUnderstanding fault rupture deformation patterns, especially in complex fault zones, has fundamental implications on seismotectonic studies and hazard mitigation for the built environment. The 2019 Mw 6.4 and Mw 7.1 Ridgecrest earthquake ruptures offer an opportunity to quantify deformation patterns and surface displacements from a complex fault rupture. Our field reconnaissance, within 18 hr of the Mw 6.4 event, documented a complex and relatively broad fault deformation zone up to a few kilometers wide in the vicinity of a gas transmission pipeline intersected by the surface rupture south of Highway 178. The subsequent Mw 7.1 event resulted in similarly distributed surface fault deformation within a broad zone that crossed a second gas transmission pipeline located south of Highway 178. On 10 July, fault-normal pipeline assessment trenches were excavated at both locations and provided evidence for late Pleistocene fault rupture on both faults expressed as upward fault truncations and paleoliquefaction features. Subsequent imagery-based rupture-mapping facilitated identification and measurement of offset features that were not identified during field mapping. Fault displacement measurements document a gradual decrease in fault slip on rupture southwestward from the Mw 6.4 epicenter within the study area. However, displacement along the primary Mw 7.1 rupture decreased more drastically southeastward toward a structural complexity at a fault stepover expressed as a horsetail splay. Fault-normal slip distributions showed that majority of the surface deformation was accommodated along discrete fault strands within the primary fault zone across both ruptures. This work expands the catalog of high-fidelity coseismic rupture information used to better understand seismotectonic processes, while contributing to refinement of fault displacement models used in support of critical infrastructure design.

Geological correlation between northern Cyprus and southern Anatolia

The island of Cyprus constitutes a fragment of southern Anatolia separated from the mainland by left-oblique transtension in late Cenozoic time. However, a geological framework of offset features of south-central Anatolia, for comparison of Cyprus with a source region within and west of the southeastern Anatolian suture zone, has not yet been developed. In this paper, I enumerate, describe, and compare a full suite of potentially correlative spatial and temporal elements exposed in both regions. Northern Cyprus and south-central Anatolia have identical tectonostratigraphic units. At the base of both belts, crop out ophiolitic mélange – accretionary complex generated during the northward subduction of the Neo-Tethyan Oceanic lithosphere from the Late Cretaceous until the end of middle Eocene. The nappes of the Taurus carbonate platform were thrust above this internally chaotic unit during late Eocene. They began to move as a coherent nappe pile from that time onward. An asymmetrical flysch basin was formed in front of this southward-moving nappe pile during the early Miocene. The nappes were then thrust over the flysch basin fill and caused its tight folding. Cyprus separated from Anatolia in the Pleistocene–Holocene when transtensional oblique faults with dip-slip components caused the development of the Adana and Iskenderun basins and the separation of Cyprus from Anatolia.

Numerical investigation and triple-parameters correlations development on the dynamic characteristics of a turbulent offset jet

ABSTRACT The present numerical study aims to numerically investigate the dynamic and turbulent characteristics of a two-dimensional and turbulent offset jet. Three different parameters were investigated: The Reynolds numbers (Re) which was varied from 10000 to 30000, wall inclination angle (α) that was from −20° to +20° and finally the offset ratio (OR) which extends from 3.25–13. Ansys Fluent was numerical CFD solver used in this present investigation. The simultaneous effects of the OR, Re and α were investigated in details. The velocity and pressure contours showed that these three parameters do not contribute equally in the development of such a flow. Also, the turbulent characteristics, such as the turbulence intensities and energies depicted how each parameter influences, separately, the turbulent flow production. Furthermore, different of tripled parameters correlations were developed. These correlations may be of help to more understand certain offset jet flow features more accurately and to predict their exact values.

The Lavic Lake Fault: A Long-Term Cumulative Slip Analysis via Combined Field Work and Thermal Infrared Hyperspectral Airborne Remote Sensing

The 1999 Hector Mine earthquake ruptured to the surface in eastern California, with &gt;5 m peak right-lateral slip on the Lavic Lake fault. The cumulative offset and geologic slip rate of this fault are not well defined, which inhibits tectonic reconstructions and risk assessment of the Eastern California Shear Zone (ECSZ). With thermal infrared hyperspectral airborne imagery, field data, and auxiliary information from legacy geologic maps, we created lithologic maps of the area using supervised and unsupervised classifications of the remote sensing imagery. We optimized a data processing sequence for supervised classifications, resulting in lithologic maps over a test area with an overall accuracy of 71 ± 1% with respect to ground-truth geologic mapping. Using all of the data and maps, we identified offset bedrock features that yield piercing points along the main Lavic Lake fault and indicate a 1036 +27/−26 m net slip, with 1008 +14/−17 m horizontal and 241 +51/−47 m vertical components. For the contribution from distributed shear, modern off-fault deformation values from another study imply a larger horizontal slip component of 1276 +18/−22 m. Within the constraints, we estimate a geologic slip rate of &lt;4 mm/yr, which does not increase the sum geologic Mojave ECSZ rate to current geodetic values. Our result supports previous suggestions that transient tectonic activity in this area may be responsible for the discrepancy between long-term geologic and present-day geodetic rates.

RECONSTRUCTION OF THE SLIP DISTRIBUTION ALONG THE WEST HELANSHAN FAULT, NORTHERN CHINA BASED ON HIGH-RESOLUTION TOPOGRAPHY

Abstract. The increasing wealthy of high-resolution topography allows for remotely measuring and analysing offset features and their associated surface slip distributions at a very high resolution and along a significant length of a fault, hence providing important insights into many aspects of the fault behaviour. The West Helanshan Fault is a Holocene active fault located at the junction of the Tibetan Plateau, Alashan, and Ordos blocks. Despite its special tectonic location, it has rarely been studied before. In this study, a 2-m-resolution DEM of the West Helanshan Fault was built from the high-resolution (0.5 m) WorldView-3 stereo satellite imagery based on the photogrammetry method, and a total of 181 strike-slip offsets and 201 vertical displacements were acquired along different segments of the fault. By statistical analysis of the offset observations, we conclude that at least six large paleoearthquakes have ruptured the fault, producing a minimum rupture length of ∼50 km, and the paleoearthquakes have followed a characteristic slip pattern with a coseismic strike slip of ∼3 m and a vertical slip of ∼1 m, corresponding to a geologic moment magnitude of 7.1–7.5.

Surface Slip Distribution Along the West Helanshan Fault, Northern China, and Its Implications for Fault Behavior

AbstractHigh‐resolution topographic data sets have now become increasingly available, which allows for remotely measuring and analyzing offset features and their associated slip distributions at a very high resolution along a fault, hence providing important insights into the fault behavior. The West Helanshan Fault is a Holocene active right‐lateral strike‐slip fault located at the junction of the Tibetan Plateau, Alashan, and Ordos blocks. In this study, a 2‐m‐resolution DEM of the West Helanshan Fault was built from the WorldView‐3 stereo satellite images (0.5 m). Combined with the high‐resolution topography acquired from the Unmanned Aerial Vehicle (UAV) images based on the Structure from Motion (SfM) method, a total of 180 lateral offsets and 201 vertical displacements were acquired along ~50 km of the fault. By statistical analysis of the offset observations and constructing the cumulative slip profiles, we conclude that large paleoearthquakes have produced characteristic slip accumulation along the fault with a right‐lateral slip of ~3 m and a vertical slip of ~1 m, rupturing at least two segments of the fault simultaneously, which corresponds to a moment magnitude ofMw7.1 ~ 7.5. The cumulative slip profiles suggest that the fault has likely propagated northward over its lifetime, and the south segment may be the most mature section of the fault where larger coseismic slip of earthquake ruptures may occur. The ratio of lateral to vertical displacement has remained constant (~3:1) through multiple successive events, indicating that the fault has maintained the same kinematic style over the last few thousands of years.

A Bit-Line Voltage Sensing Circuit With Fused Offset Compensation and Cancellation Scheme

A systematic offset voltage occurs in sense amplifiers for SRAMs, mainly due to the mismatch between the threshold voltages of MOS transistors. This offset affects the reading operations of SRAMs in terms of accuracy, delay and power consumption. In this brief, a bit-line voltage sense amplifier is presented, which combines offset compensation and cancellation features. The circuit operations are carried out in four phases, in which two CMOS amplifiers are used as line buffers and they are pre-charged in the high voltage gain region in order to reduce the effects of the offset. The proposed sense amplifier has been designed and prototyped in 180-nm CMOS technology. It is capable to correct a voltage offset up to 100 mV and exhibits a minimum access time of 58 ps. These results overcome other solutions in applications where sub-threshold operations are not required and an aggressive voltage scaling is not convenient.

Structural Characteristics, Paleoseismology and Slip Rate of the Qoshadagh Fault, Northwest of Iran

Geometric and seismic parameters of the Qoshadagh Fault (QDF) were investigated to evaluate seismic hazard along this fault, which consists of three segments. The central E–W striking, dextral-reverse segment is the longest and terminates at both ends into NW–SE striking splay arrays. Both eastern and western splay arrays form locally transtensional bends. Paleoseismic data obtained from three excavated trenches across the fault combined with dated offset geomorphic features revealed that the central segment experienced at least 5 surface rupturing earthquakes during the past 2.5 ka, with maximum moment magnitude of Mw = 6.8 ± 0.2. The mean recurrence interval for the identified paleoearthquakes is 452 ± 143 years (±2σ) and the calculated amount of slip per event is ca. ≈0.85 m. These results imply that the QDF slips at an average rate of 1.9 ± 0.1 mm yr–1 for over the past 2.5 ka. The obtained values define the seismic behavior of the fault and are essential to remediate ensuing seismic risks.

Image offset density distribution model and recognition of hand knuckle

The accurate description of hand posture plays an important role in the man-machine interaction involved in coordinated assembly. Knuckle image extraction and recognition are of great significance to refine and enrich hand-pose information. These are based on nonparametric density kernel estimation observation sets corresponding to unilateral and bilateral excursion of the hand knuckle gray image. In this paper, sets of pixel positions belonging to the upper- and middle-density intervals are used as two types of image targets. Random clustering and random field multi-classification target modeling are used to learn and estimate the two target distributions of the image. The discriminant field classification learning method is used to fuse the two kinds of target models. A comprehensive representation of the image offset features is obtained. Finally, the knuckle image sample set is used to train the model, and the adaptive threshold is used to identify the hand knuckle image. The results show that the proposed method is feasible.

Multimillennial Incremental Slip Rate Variability of the Clarence Fault at the Tophouse Road Site, Marlborough Fault System, New Zealand

AbstractIncremental slip rates of the Clarence fault, a dextral fault in the Marlborough fault system of South Island, New Zealand, varied by a factor of 4–5 during Holocene–latest Pleistocene time, as revealed by geomorphic mapping and luminescence dating of faulted fluvial landforms at the Tophouse Road site. We used high‐resolution lidar microtopographic data and field surveys to map the fine‐scale geomorphology and precisely restore the offset features. We dated the offsets using a stratigraphically informed protocol for infrared stimulated luminescence dating. These data show that incremental slip rates varied from ~2.0 to 9.6 mm/year, averaged over multiple earthquakes and millennial timescales. Comparison to incremental slip rates of the nearby Awatere fault suggests that these faults may behave in coordinated (and anticorrelated) fashion. This study adds to a growing body of evidence suggesting that incremental slip rate variation spanning multiple earthquake cycles may be more common than previously recognized.

Forward Modeling Research of Gravity Data Offset in North China Region

Due to the complexity and overlap effects of gravity anomalies, the gravity high point always deviates from the real position of the target. Researching the offset characteristics is helpful to determine the right location of gravity anomalies. In this paper, a series of forward models were designed to calculate the offset features under different assumptions. Different density models were established based on the measured gravity data in north China Sunhu area and a variety of methods were tried to eliminate offset effects under different conditions. The results indicate that the gravity anomalies of different density bodies can be separated effectively and the real position of target can be correctly located by using the “layer stripping method”.

Surface Slip From the 2014 South Napa Earthquake Measured With Structure From Motion and 3‐D Virtual Reality

AbstractThe detailed features of an earthquake surface rupture may decay quickly in the landscape due to erosion or repair, such that primary displacements are seldom available for repeated study within the weeks following an earthquake. Here we describe a rapidly deployable field workflow using structure‐from‐motion (SfM) photogrammetry to produce three‐dimensional models of offset features and apply the technique to the 24 August 2014 Mw 6.0 South Napa earthquake surface rupture. We use repeated analyses of SfM point clouds using 3‐D interactive virtual reality tools to derive precise and reproducible fault‐slip measurements along the surface rupture and document the temporal evolution of afterslip at two sites along its trace. The SfM technique, combined with 3‐D virtual reality, enables archiving of primary field relationships and assessment of uncertainty in those data to a degree that was previously inaccessible.