The CIELO Seismic Experiment

The Crust and lithosphere Investigation of the Easternmost expression of the Laramide Orogeny was a two-year deployment of 24 broadband, compact posthole seismometers in a linear array across the eastern half of the Wyoming craton. The experiment was designed to image the crust and upper mantle of the region to better understand the evolution of the cratonic lithosphere. In this article, we describe the motivation and objectives of the experiment; summarize the station design and installation; provide a detailed accounting of data completeness and quality, including issues related to sensor orientation and ambient noise; and show examples of collected waveform data from a local earthquake, a local mine blast, and a teleseismic event. We observe a range of seasonal variations in the long-period noise on the horizontal components (15–20 dB) at some stations that likely reflect the range of soil types across the experiment. In addition, coal mining in the Powder River basin creates high levels of short-period noise at some stations. Preliminary results from Ps receiver function analysis, shear-wave splitting analysis, and averaged P-wave delay times are also included in this report, as is a brief description of education and outreach activities completed during the experiment.

Determining the impact of sensor orientation on moisture content measurements in eastern white pine

As buildings become more airtight and insulated, the movement and accumulation of moisture within building envelopes become paramount in determining its resiliency. Current methods for quantifying the moisture content (MC) of wood species involve the measurement of electrical resistance between two installed electrodes and the use of existing empirical correlations to evaluate the MC. However, these correlations do not adequately consider the impact of sensor orientation within wall assemblies. The objective of this paper is to determine the impact of MC readings within a wood sample due to sensor orientation. A total of 126 eastern white pine samples were tested with electrodes placed along the grain of the wood (longitudinal), across the grain of the wood (tangential), and in a diamond pattern, using six different fasteners as electrodes. The samples were placed in a controlled environmental chamber until steady state was achieved at approximately 18% MC. Electrical resistances of the samples were measured in both directions at temperatures ranging from -10°C to 40°C. It was found that the tangential-to-longitudinal resistance ratio is 1.1-1.35 depending on the electrode type.

Validation of 3-Space Wireless Inertial Measurement Units Using an Industrial Robot

Inertial Measurement Units (IMUs) are beneficial for motion tracking as, in contrast to most optical motion capture systems, IMU systems do not require a dedicated lab. However, IMUs are affected by electromagnetic noise and may exhibit drift over time; it is therefore common practice to compare their performance to another system of high accuracy before use. The 3-Space IMUs have only been validated in two previous studies with limited testing protocols. This study utilized an IRB 2600 industrial robot to evaluate the performance of the IMUs for the three sensor fusion methods provided in the 3-Space software. Testing consisted of programmed motion sequences including 360° rotations and linear translations of 800 mm in opposite directions for each axis at three different velocities, as well as static trials. The magnetometer was disabled to assess the accuracy of the IMUs in an environment containing electromagnetic noise. The Root-Mean-Square Error (RMSE) of the sensor orientation ranged between 0.2° and 12.5° across trials; average drift was 0.4°. The performance of the three filters was determined to be comparable. This study demonstrates that the 3-Space sensors may be utilized in an environment containing metal or electromagnetic noise with a RMSE below 10° in most cases.

Proof of Concept Novel Configurable Chipless RFID Strain Sensor

This paper contains two main areas of research: First, this work outlines a novel, highly sensitive strain sensor design that should support various levels of deformation, depending on the substrate type used. Physical implementations in this work have focused on proving its large deformation capabilities, and simulations have been used to assess its more general electromagnetic response. The other part of this paper focusses on exploring other effects that will impact the sensing of strain of resolutions below 10 με, which is a capability achieved by other aerospace-grade strain sensor technologies. These effects are limited to mechanical swelling and sensor orientation in the azimuth and elevation planes, as these appear to be unexplored and highly relevant issues to the topic of chipless RFID-based strain sensing. From this exploration, it is apparent that the effects of mechanical swelling and sensor orientation (amongst others) will need to be addressed in any real-life implementation of the sensor, requiring a strain resolution below 10 με.

ANALYSIS AND BIAS IMPROVEMENT OF HEIGHT MODELS BASED ON SATELLITE IMAGES

Height models are a fundamental part of the geo-information required for various applications. The determination of height models by aerial photogrammetry, LiDAR or space images is time-consuming and expensive. For height models with large area coverage, UAVs are not economic. The freely available height models ASTER GDEM-3, SRTM, AW3D30 and TDM90 can meet various requirements.With the exception of ASTER-GDEM-3, which cannot compete with the other, the digital surface models SRTM, AW3D30 and TDM90 are analyzed in detail for accuracy and morphology in 4 test sites using LiDAR reference DTMs. The accuracy figures root mean square error, standard deviation, NMAD and LE90 are compared as well as the accuracy dependence on the terrain inclination. The analysis uses a layer for the open areas, excluding forest and settlement areas. Remaining elements that do not belong to a DTM are filtered. Particular attention is paid to systematic errors. The InSAR height models SRTM and TDM90 have some accuracy and morphological restrictions in mountain and settlement areas. Even so, the direct sensor orientation of TDM90 is better than for the other. Optimal results in terms of accuracy and morphology were achieved with AW3D30 corrected by TDM90 for the local absolute height level. This correction reduces the bias and also the tilt of the height models compared to the reference LiDAR DTM.

Orientation-Invariant Spatio-Temporal Gait Analysis Using Foot-Worn Inertial Sensors

Inertial sensors can potentially assist clinical decision making in gait-related disorders. Methods for objective spatio-temporal gait analysis usually assume the careful alignment of the sensors on the body, so that sensor data can be evaluated using the body coordinate system. Some studies infer sensor orientation by exploring the cyclic characteristics of walking. In addition to being unrealistic to assume that the sensor can be aligned perfectly with the body, the robustness of gait analysis with respect to differences in sensor orientation has not yet been investigated—potentially hindering use in clinical settings. To address this gap in the literature, we introduce an orientation-invariant gait analysis approach and propose a method to quantitatively assess robustness to changes in sensor orientation. We validate our results in a group of young adults, using an optical motion capture system as reference. Overall, good agreement between systems is achieved considering an extensive set of gait metrics. Gait speed is evaluated with a relative error of −3.1±9.2 cm/s, but precision improves when turning strides are excluded from the analysis, resulting in a relative error of −3.4±6.9 cm/s. We demonstrate the invariance of our approach by simulating rotations of the sensor on the foot.

An Innovative Deployment Technique to Optimize Logging Conveyance and Improve Data Quality

Wireline logging in a complex well profile, such as extended reach drilling (ERD) wells, presents many challenges for conveyance and data quality. Traditional pipe conveyed logging (PCL) or coiled tubing (CT) are prohibitive in terms of rig time, operational complexity and cost. Alternatively, tractor conveyance is limited by the available force in long laterals. Tools and accessories create higher friction and might jeopardize tool position in the horizontal section. Consequently, both data quality and reaching total depth are compromised. This paper details an innovative deployment technique using oriented wheels to address these challenges.The new centralizing system, comprised of bespoke wheeled carriages, takes a holistic approach to tool conveyance, reducing drag while ensuring optimum sensor orientation. Tool position is achieved through management of tool center of gravity, relative to the wheel axes. The idea of "centralizing by decentralizing" uses the wheeled carriages instead of bow spring centralizers. An eccentered counterweight is included to ensure the proper orientation of the logging sensors.In addition to improving data quality with proper centralization, the wheels minimize friction and the required force to push the toolstring when combined with a tractor. This enables the toolstring to safely and efficiently reach the well bottom and avoid multiple attempts and associated downhole failures. In the planning phase, calibrated software simulation parameters for this technique help to predict free-fall depth and required tractoring force.The wheeled carriages were deployed in an ERD well for cement evaluation across a 9-5/8" casing and could reach a world record of 85° by gravity. The reduced friction and optimized tool position resulted in higher tractor force margins; and so a net gain in the overall tractoring distance. Also, the low drag and surface tension enabled a sufficient pull capacity with a minimum drive combination. For data acquisition, this deployment enabled a minimum eccentricity, resulting in better cement evaluation data quality and reduced uncertainty related to interpretation. In addition to these benefits, a tangible and direct savings of rig time has improved safety, operational efficiency and well delivery KPIs. Oriented wheels with tractors were deployed in other challenging environments and showed consistent and reliable results.This innovative technique can be deployed in both open-hole and cased-hole with fitted design depending on the borehole size, well profile and complexity of the toolstring configuration.

Evaluation of seismic sensor orientations in the full moment tensor inversion results

<p>Three-component seismograms recorded by seismic sensors are momentous data to study the source mechanism of earthquakes. Correct orientation of sensors relative to the true north is important for the waveform inversion techniques. Yet, the non-precise orientation of horizontal components of seismic sensors has been reported in many seismic networks worldwide. In this study, we evaluated the effect of sensor misorientations (deviations from the true north) on time-domain moment tensor inversion, relying on the recent sensor orientation studies on broadband seismic networks in Iran and Turkey. We selected several well-recorded countrywide local and regional moderate magnitude earthquakes, which are associated with the tectonic events, in the time period of 2012-2019. We calculated the moment tensor inversion of those events before and after applying the orientation correction using a Bayesian bootstrap-based probabilistic method. This leads to reaching the uncertainties and trade-offs of parameters and helps to stabilize the inversion. Our analysis shows that in the presence of misoriented sensors, an approximate solution is achievable. However, this includes the remarkable uncertainties in inverted parameters and makes the reliable determination of the moment tensor’s elements challenging. We also found an additional significant non-double couple component while using the misoriented radial and transverse components. Results show that the misfit and uncertainties decrease significantly when sensor orientation correction applied. We suggest that the evaluation of metadata should be part of data processing in seismic networks and data centers, to report more reliable moment tensor solutions.</p>