Compass Measurements Research Articles

R-C-D-F machine learning method to measure for geological structures in 3D point cloud of rock tunnel face

This study introduces an innovative Roughness-CANUPO-Dip-Facet (R-C-D-F) methodology for the measurement of dip angle and direction in geological rock facets. The R-C-D-F method is distinguished by its comprehensive four-step approach, encompassing filtration through roughness analysis, CANUPO analysis, and dip angle filtration, followed by facet segmentation as the measurement step. To achieve precise and efficient results, the method specifically focuses on isolating joint embedment, achieved by systematically filtering out joint bands. This selective filtration process ensures that measurements are conducted exclusively on relevant joint embedment points. The novelty of this methodology lies in its capability to automatically eliminate joint bands while retaining the joint embedment points, facilitating precise measurements without manual intervention. Three site models were evaluated using the R-C-D-F method, alongside four different techniques for measuring dip angle and direction: plane fitting, normal vector conversion, facet segmentation, and compass measurements. The results demonstrated that all methods accurately calculated the dip angle, with an accuracy ranging from 97 % to 99.4 %. The facet segmentation method was selected as the optimal measurement tool due to its automatic nature and capacity to provide accurate results without manual intervention. Furthermore, the optimal local neighbour radius (LNR) for calculating normal vectors was determined, with findings indicating that a larger LNR value enhances accuracy but also increases computational time. A verification was conducted to estimate the dip angle used for filtering and discarding additional points representing joint rock bands, with the optimal value being 45, 30, and 45 degrees for the respective sites.The R-C-D-F method effectively detected and eliminated 100 % of joint band points while retaining 81 % of joint embedment points, and the facet segmentation method provided accurate dip angle and direction measurements for each joint embedment segment. These outcomes underscore the robustness and precision of the R-C-D-F method in geological engineering and rock stability studies.

A new method to automatically identify and characterize rock mass discontinuities using a smartphone: Experiences from a slope and a tunnel

Smartphones equipped with high-resolution lenses and advanced photo processing capabilities have evolved into versatile, multifunctional devices. This paper introduces a novel method for extracting and analyzing rock mass discontinuities using smartphones, encompassing smartphone photography, ground control point selection, point cloud reconstruction, and discontinuity set identification and analysis. The method was validated through a slope case study in Bayi District, Linzhi city, Tibet, China, under natural light and a tunnel case study in Northwest China under artificial light, and the results agreed well with traditional compass measurements. Notably, the method proved efficient, reducing the measurement time to 15 min compared to 1.5 h with a geological compass in Case 1. Significant insights were gained regarding the impact of photo quantity and shooting distance on point cloud accuracy, along with the influence of lighting in tunnel environments, thus offering valuable guidance for fieldwork. Moreover, the potential of this smartphone-based method was confirmed through comparative analysis with laser scanner data. In summary, rock mass measurements using smartphones are validated as simple, efficient, and practical approaches for geological studies.

Discontinuity Measurement for Slope Failure Analysis with Structure from Motion Method Using Drone on A Slope in Hargowilis, Kokap District, Kulon Progo Regency, D.I. Yogyakarta Province

Abstract The measurement of the discontinuity area is one of the important data to determine the slope failure kinematics. Discontinuity measurement can be done by geological compass measurements, but only limited to areas that can be reached and safe. Methods that can help measure the discontinuity plane is Structue from Motion techniques. This method uses raw data in the form of outcrop photos that are processed into point clouds to be processed into a 3-dimensional model. This model is used to measuring the position of the discontinuity plane digitally with a FACETS plug-in by CloudCompare software. FACETS plug-in performs a measurements automatically with the Kd-Nearest algorithm for two sides of of the outcrop. Side-1 has a dimension about 60 meter length and 25 meter height with slop face direction to the east an Side-2 has a dimensions about 25 meter length and 20 meter height, facing south. Side-1 kinematic analysis showing 8.97% of falilure mechanism are oblique. Meanwhile, wedge sliding are the most possible slope failure type happen ini Side-2 with 27,05% chance.

INFLUENCE OF ORIENTATION ERRORS ASSOCIATED WITH THE USE OF A MAGNETIC COMPASS ON THE ACCURACY OF DETERMINING THE POSITION OF THE PALEOMAGNETIC POLE AND THE AMPLITUDE OF PALEOSECULAR VARIATIONS

The use of a magnetic compass in paleomagnetic studies of highly magnetic rocks (for instance, basalts) can lead to large errors in the orientation of paleomagnetic samples. On the other hand, alternative methods of orientation are relatively time-consuming, and in the case of using a solar compass, they also require sunny weather – a condition that is rarely met, especially when sampling at high and subpolar latitudes. This often leads to the fact that researchers in their work rely on the results of magnetic compass measurements, while assuming that the resulting errors are of a random nature and, with sufficiently good statistics, are averaged. In this study, numerical modeling is performed, which allows us to verify this assumption and assess how much orientation errors associated with the use of a magnetic compass can affect the final results of paleomagnetic studies, such as determining the position of the paleomagnetic pole and the amplitude of ancient geomagnetic variations. As a result of the work performed , it is shown that: 1) the amplitudes of paleosecular variations and the positions of paleomagnetic poles are weakly sensitive to moderate and even relatively large errors in the orientation of paleomagnetic samples associated with the use of a magnetic compass; 2) very large errors in the orientation of samples lead to a significant increase in the within-site scatter of paleomagnetic directions, which makes it possible to detect and exclude the corresponding sites with a large (for instance >15°) value of the α95; 3) the influence of distortions associated with the use of a magnetic compass on the accuracy of determining the position of the paleomagnetic pole and the amplitude of ancient geomagnetic variations depends on latitude. At near-equatorial latitudes, this effect is maximal, at medium latitudes – minimal.

Transverse momentum weighted Sivers asymmetries in SIDIS and Drell-Yan processes at COMPASS

We investigate the transverse momentum weighted Sivers asymmetries in the processes with transversely polarized proton target, including the PhTzMpsin⁡(ϕh−ϕS) weighted asymmetry in charged hadron production in semi-inclusive deeply inelastic scattering (SIDIS) and the qTMpsin⁡(ϕS) weighted asymmetry in π−p Drell-Yan process. These asymmetries can be expressed as the product of the transverse-moments of the transverse momentum dependent (TMD) parton distribution functions (PDFs) and fragmentation functions (FFs). Using the parametrization for the Sivers function of the proton, the unpolarized PDFs of proton and pion, and the unpolarized FF of charged hadron, we present the numerical calculation for weighted Sivers asymmetries in SIDIS and Drell-Yan processes at the kinematics of COMPASS. We find that our prediction for the SIDIS process is in agreement with the recent COMPASS measurement. Recent new high-statistics data of Sivers asymmetry measured in SIDIS process and Drell-Yan process from COMPASS favored the sign change of Sivers function. High-precision experimental data of weighted asymmetries are still needed to test the sign change property of the Sivers function between SIDIS and Drell-Yan processes and to constrain the sea quark Sivers function.

Study of the origin and correction of compass measurement errors in Doppler current meters

Surface and subsurface currents are two of the Essential Climate Variables (ECVs) defined by the Global Climate Observing System (GCOS). In situ current measurements can be made by Eulerian methods with instruments on moorings fixed in space. These methods require the determination of two metrological quantities: the speed and the direction of the motion. Their measurement and calibration require the determination of reference velocities and the measure of the angular movement of seawater in relation to the measuring device, as well as of the measuring device in relation to a reference direction given by the magnetic North. This reference direction is determined by electronic compasses integrated into current meters and current profilers. Compasses are sensitive to their magnetic environment, and, therefore, to the objects and instruments that surround them. This publication describes experiments conducted with current meters and current profilers to measure the influence of different devices on the accuracy of their compass measurements. It gives some explanations about the origin of measurement errors and proposes solutions to correct or attenuate the defaults in direction measurements and the measured deviations. Correction formulas are given that can be applied to measured data. They allow the reduction of errors of several tens of degrees for data to be within the instrument’s specifications.

Manual compass measurement and trigonometric determination of proptosis.

To determine the accuracy of manual compass measurement and trigonometric determination of proptosis (MCMATDP). This agreement study included 120 eyes without eye diseases or injury of 60 patients who visited the ophthalmic clinic of Peking University Shenzhen Hospital from February 2020 to June 2020. The absolute values of proptosis were measured by MCMATDP and computed tomography (CT). The differences between the two methods were shown by Bland-Altman plot. The cohort comprised 25 males and 35 females (average age 38.3years). The absolute value of proptosis measured by CT was correlated with the MCMATDP. Further analysis showed that a 95% limit of agreement (LoA) was - 0.53 to 0.60mm in the right eye and - 0.46 to 0.55mm in the left eye between CT and MCMATDP. In addition, the 95% LoA was - 0.49 to 0.60mm in both eyes between the two methods. All points were < 5% in Bland-Altman plots. Compared to CT, MCMATDP is rather consistent in proptosis measurement. The new method is feasible in clinical practice when measuring proptosis. With the development of non-contact intelligent measurement software and the continuous improvement in measurement accuracy, a non-invasive, simple, and inexpensive measurement mode is true based on the theory of MCMATDP.

Robust Adaptive Heading Tracking Fusion for Polarization Compass With Uncertain Dynamics and External Disturbances

For the polarization compass (PC), maintaining high-precision and high-robustness autonomous measurement of the heading information under conditions where the atmospheric polarized light is being blocked or disturbed represents a challenging problem. In this paper, the E-vector orientation algorithm, which provides high orientation accuracy and real-time performance in sunny weather, and the symmetric axis orientation algorithm, which offers a strong anti-interference ability in occluded environments, are integrated to solve this problem. Furthermore, an improved state error model is established to increase the accuracy of the heading estimation. To track the system state rapidly and circumvent the uncertainties caused by measurement noise variance, an improved variational Bayesian strong tracking cubature Kalman filter (VBSTCKF) is proposed to estimate both the state and the time-varying measurement noise variance accurately. In addition, a multi-frequency data fusion algorithm based on residual compensation is proposed to overcome the inconsistent sampling operation frequency problems of the two orientation algorithms. The outstanding feature is that the proposed multi-frequency VBSTCKF (MF-VBSTCKF) can improve the orientation precision and robustness while also ensuring the high-frequency output performance. Finally, experimental results acquired in occluded environments verify the superiority of the proposed method.

Rapid tunnel scanning using a 360-degree camera and SfM photogrammetry

Photogrammetric scanning can be employed for the digitization of underground spaces, for example for remote mapping, visualization, or training purposes. However, such a technique requires capturing many photos, which can be laborious and time-consuming. Previous research has demonstrated that the acquisition time can be reduced by capturing the data with multiple lenses or devices at the same time. Therefore, this paper demonstrates a method for rapid scanning of hard rock tunnels using Structure-from-Motion (SfM) photogrammetry and a 360-degree camera. The test was performed in the Underground Research Laboratory of Aalto University (URLA). The tunnel is located in granitic rocks at a depth of 20 m below the Otaniemi campus in Espoo, Finland. A 10 m long and 3.5 m high tunnel section with exposed rock was selected for this study. Photos were captured using the 360-degree camera from 27 locations and 3D models were reconstructed using SfM photogrammetry. The accuracy, speed, and resolution of the 3D models were measured and compared with models scanned with a digital single-lens reflex (DSLR) camera. The results show that the data capture process with a 360-degree camera is 6x faster compared to a conventional camera. In addition, the orientation of discontinuities was measured remotely from the 3D model and the digitally obtained values matched the manual compass measurements. Even though the quality of the 360-degree camerabased 3D model was visually inferior compared to the DSLR model, the point cloud had sufficient accuracy and resolution for semi-automatic discontinuity measurements. The quality of the models can be improved by combining 360-degree and DSLR photos which result in a point cloud with 3x higher resolution and 2x higher accuracy. The results demonstrated that 360-degree cameras can be used for the rapid digitization of underground tunnels.

Directional wave measurements from navigational buoys

In-situ wave measurements are often required by marine industry standards and for verification of coastal wave forecasts. Obtaining wave measurements is costly and it would be advantageous to utilize existing platforms like navigational buoys designed for environmental monitoring. In this study, a wave sensor module (MOTUS Wave Sensor, Aanderaa Data Instruments) installed on a navigational buoy (Tideland) and a coastal buoy (EMM2.0) is validated against a dedicated wave measurement buoy (Waverider, Datawell). The validation is based upon four months of measurements off the west coast of Norway. The results show that the MOTUS sensor on-board navigational/coastal buoys provide accurate measurements of wave parameters compared to Waverider. Wave height biases were less than 0.04 m over the full wave spectra, and less than 5% for frequencies between 0.05 and 0.45 Hz (0.01 Hz bin width). Mean wave direction bias for the full spectra was 1.4 and 2.8 degrees, and less than 5 and 10 degrees in frequency bins between 0.05 and 0.45 Hz for the navigational and coastal buoy, respectively. External compass measurements were required for accurate directional measurements for the coastal buoy. The validated wave sensor provides in-situ directional wave measurements with measurement uncertainties well within recommended accuracy levels.

Detection of discontinuity pattern and orientation for tunnel faces by using 2D and 3D image analysis techniques

This study proposes a new measurement system based on Structure from Motion (SfM) photogrammetry to evaluate tunnel faces. The main goal is to determine the tunnel face discontinuity patterns and orientations for the tunnel face stability evaluation. A 3D point cloud model is generated from overlapping images of the tunnel face 3D polystyrene model through SfM photogrammetry. The discontinuity patterns and orientations are determined through facet extraction of the K-D tree plugin in CloudCompare. The same sets of overlapping images were analyzed in four different quality settings (low, medium, high, and ultra-high) with various sets of point cloud number that control the accuracy of the discontinuity's measurement. In this study, the high-quality setting shows the consistent measurement of the discontinuity patterns and orientations compared with the real 3D polystyrene tunnel face model. Validation of the pattern results from CloudCompare was carried out using JudGeo. Cluster analysis shows two sets of discontinuity with means of dip and dip direction of 82°/164° and 84°/307°, respectively. Both orientations were manually verified with a geological compass. The high-quality point cloud and manual compass measurement of the orientation highlight the similarity of the concentration for both discontinuity sets for the replica tunnel face. This tunnel face proposed method has the advantages of evaluating inaccessible areas and avoiding professional bias.

Rapid Photogrammetry with a 360-Degree Camera for Tunnel Mapping

Structure-from-Motion Multi-View Stereo (SfM-MVS) photogrammetry is a viable method to digitize underground spaces for inspection, documentation, or remote mapping. However, the conventional image acquisition process can be laborious and time-consuming. Previous studies confirmed that the acquisition time can be reduced when using a 360-degree camera to capture the images. This paper demonstrates a method for rapid photogrammetric reconstruction of tunnels using a 360-degree camera. The method is demonstrated in a field test executed in a tunnel section of the Underground Research Laboratory of Aalto University in Espoo, Finland. A 10 m-long tunnel section with exposed rock was photographed using the 360-degree camera from 27 locations and a 3D model was reconstructed using SfM-MVS photogrammetry. The resulting model was then compared with a reference laser scan and a more conventional digital single-lens reflex (DSLR) camera-based model. Image acquisition with a 360-degree camera was 3× faster than with a conventional DSLR camera and the workflow was easier and less prone to errors. The 360-degree camera-based model achieved a 0.0046 m distance accuracy error compared to the reference laser scan. In addition, the orientation of discontinuities was measured remotely from the 3D model and the digitally obtained values matched the manual compass measurements of the sub-vertical fracture sets, with an average error of 2–5°.

Accuracy assessment of smart devices for Geoscience field mapping

We present the measurement of fractures near the town of Beaufort West, South Africa. A field visit was conducted to examine the dip and azimuth of rock outcrops in and around the town. The locations of these various fractures were mapped and their orientation, which included the dip and strike of the rock surface, was measured using a geological compass (i.e., Brunton Truarc 15 Compass). The geological compass measurements were then compared to three mobile devices. These mobile devices, namely an iPad 2 and two smartphones (Samsung S8 and Huawei P10 Lite), all had the same application for standardization and the mobile device results were individually compared to the geological compass. The data stemming from the various mobile devices and the geological compass were then compared in terms of their variance. This statistical analysis was performed using the Correlated T-test method, as well as the Pearson Correlation Coefficient formula. To visually examine the main fracture orientations, the data obtained using the geological compass was plotted on a rose diagram. Results show that the relationship between the geological compass and the mobile device readings had little to no correlation, when using both the correlation and t-tests as combined determinants. This highlights the importance of ensuring measurement accuracy in the field as well as instrument calibration in situ.

Stochastic behaviours for retrieval of storage items using simulated robot swarms

Robot swarms have the potential to be used as an out-of-the-box solution for storage and retrieval that is low cost, scalable to the needs of the task, and would require minimal set up and training for the users. Swarms are adaptable, robust and scalable with a relatively low computational cost which makes them appropriate for this purpose. This project simulated a robot swarm with simple sensors and stochastic movement, collecting boxes from storage to deliver them to the user. We show in simulation that stochastic strategies based on random walk and probabilistic sampling of local boxes could give rise to competitive solutions to retrieve boxes and deliver them unordered, or following a predetermined order, within a storage scenario. The performance of the task is drastically improved using an additional simple bias rule which uses compass measurements and does not reduce the minimalism of the control. It is shown that swarm technology could provide an out-of-the-box system for storage and retrieval using only information local to each robot and with distributed control.

Single-spin asymmetry ATsin(2ϕ−ϕS) in π−p Drell-Yan process within TMD factorization

We study the single-spin asymmetry ATsin(2ϕ−ϕS) in the pion-induced Drell-Yan process within the transverse momentum dependent factorization (TMD factorization). The asymmetry can be expressed as the convolution of the Boer-Mulders function and the transversity function. We numerically estimate the asymmetry ATsin(2ϕ−ϕS) at the COMPASS kinematics with the model results for the pion meson distributions from the light-cone wave function approach and the available parametrization for the proton distributions. We also include the TMD evolution formalism both proton and pion parton distribution functions by using two different parametrizations on nonperturbative Sudakov form factor. We find that the asymmetry ATsin(2ϕ−ϕS) as functions of xp, xπ, xF and q⊥ is qualitatively consistent with the recent COMPASS measurement.

Kotzinian-Mulders effect in semi-inclusive DIS within TMD factorization * *Supported by the National Natural Science Foundation of China (12075043)

In this study, we investigate the Kotzinian-Mulders effect under semi-inclusive deep inelastic scattering (SIDIS) within the framework of transverse momentum dependent (TMD) factorization. The asymmetry is contributed by the convolution of the Kotzinian-Mulders function and the unpolarized fragmentation function . As a TMD distribution, the Kotzinian-Mulders function in the coordinate space in the perturbative region can be represented as the convolution of the C-coefficients and the corresponding collinear correlation function. The Wandzura-Wilczek approximation is used to obtain this correlation function. We perform a detailed phenomenological numerical analysis of the Kotzinian-Mulders effect in the SIDIS process within TMD factorization at the kinematics of the HERMES and COMPASS experiments. We observe that the obtained -, -, and -dependent Kotzinian-Mulders effects are basically consistent with the HERMES and COMPASS measurements. We also make predictions at EIC and EicC kinematics.

Boer\u2013Mulders function of the pion and pretzelosity distribution of the proton in the polarized pion-proton Drell\u2013Yan process at COMPASS

We present a phenomenological analysis of the q_{text {T}}-weighted transverse spin dependent azimuthal asymmetry recently measured by the COMPASS Collaboration in polarized pion-proton Drell–Yan process. In the kinematical regimes explored by experiments, we consider the leading-twist contributions from the Boer–Mulders distribution functions h_{1}^{perp }(x,k_{text {T}}^{2}) of both the pion and the proton, the transversity distribution h_{1}(x,k_{text {T}}^{2}) and the pretzelosity distribution h_{1text {T}}^{perp }(x,k_{text {T}}^{2}) of the proton, with the unpolarized transverse-momentum-dependent distribution function f_{1}(x,k_{text {T}}^{2}) of the proton being also involved in the calculation. By comparing the data reported by the COMPASS Collaboration with theoretical calculated results, we find that the COMPASS measurements represent the first experimental evidence of the Boer–Mulders effect in polarized Drell–Yan process. We also test the universality between proton and pion Boer–Mulders functions.

Scientists Mine 16th Century Ship Logs for Geophysical Research

Compass measurements held a key to unlocking the mystery of Earth’s magnetic field and its changes over time. A historian-turned-geoscientist found the measurements in an unlikely place—merchant ship logs.

Is cerebral perfusion maintained during full and partial resuscitative endovascular balloon occlusion of the aorta in hemorrhagic shock conditions?

Partial resuscitative endovascular balloon occlusion of the aorta (pREBOA) is a technology that occludes aortic flow and allows for controlled deflation and restoration of varying distal perfusion. Carotid flow rates (CFRs) during partial deflation are unknown. Our aim was to measure CFR with the different pREBOA balloon volumes and correlate those to the proximal mean arterial pressure (PMAP) and a handheld pressure monitoring device (COMPASS; Mirador Biomedical, Seattle, WA). Ten swine underwent a hemorrhagic injury model with carotid and iliac arterial pressures monitored via arterial lines. Carotid and aortic flow rates were monitored with Doppler flow probes. A COMPASS was placed to monitor proximal pressure. The pREBOA was inflated for 15 minutes then partially deflated for an aortic flow rate of 0.7 L/min for 45 minutes. It was then completely deflated. Proximal mean arterial pressures and CFR were measured, and correlation was evaluated. Correlation between CRF and COMPASS measurements was evaluated. Carotid flow rate increased 240% with full inflation. Carotid flow rate was maintained at 100% to 150% of baseline across a wide range of partial deflation. After full deflation, CFR transiently decreased to 45% to 95% of baseline. There was strong positive correlation (r > 0.85) between CFR and PMAP after full inflation, and positive correlation with partial inflation (r > 0.7). Carotid flow rate had strong correlation with the COMPASS with full REBOA (r > 0.85) and positive correlation with pREBOA (r > 0.65). Carotid flow rate is increased in a hemorrhagic model during full and partial inflation of the pREBOA and correlates well with PMAP. Carotid perfusion appears maintained across a wide range of pREBOA deflation and could be readily monitored with a handheld portable COMPASS device instead of a standard arterial line setup.

Supporting Transition from Out of Home Care to Adulthood: Linked Data Is Central to The Compass Social Impact Bond

The COMPASS program supports young people to successfully transition from Out of Home Care to adulthood. COMPASS is a social impact bond partnership between Victorian government, not-for-profit organisations and investors. COMPASS uses linked data in every phase from design, to implementation, to outcome measurement.&#x0D; IntroductionStudies demonstrates that young care leavers experience significantly poorer outcomes than their peers. COMPASS is a preventative program progressivelyproviding 200 care leavers with access to housing and individualised support. The Centre for Victorian Data Linkage (CVDL) developed the Victorian Linkage Map (VLM) in 2016, linking 20 plus health and human services datasets with births and deaths data. Linked data provides a critical evidence base for COMPASS.&#x0D; Objectives and ApproachThe presentation describes application of linked data for COMPASS design, implementation and measurement. Linked data cohort analysis of post-care service use of 6000 young people informed the program design. Linked data also provides the basis for a stratification tool to measure the complexity profile of referrals. Health, housing and justice payable outcomes are measured by comparing relative performance of participants with a matched control group using linked data.&#x0D; ResultsImplementation of COMPASS has highlighted the value of linked data in service design and measurement of payable outcomes. It has also highlighted the challenges of using linked data in a real-world environment, including the need for thorough documentation and testing of specifications, calculations and processes.&#x0D; Conclusion / ImplicationsThe use of linked data for COMPASS provides a model for evidence-based service design and tests the use of linked data for robust and sustainable outcome measurement. The lessons from COMPASS are applicable to other social impact bonds and service implementation and outcome measurement more broadly.