Large-scale Measurements Research Articles

Direct assessment of the influence of pose repeatability on the accuracy of dimensional measurements for Computed Tomography systems with high degrees of freedom

Abstract Industrial X-ray Computed Tomography (CT) systems with high geometric flexibility are increasingly utilized for large-scale measurement objects or challenging measurement tasks. To maintain high accuracy when deviating from the established circular scan trajectory, trajectory calibration methods using multi-sphere reference objects with known marker positions are commonly employed. These multi-sphere objects can either be scanned together with the measurement object (online trajectory calibration) or in a separate scan (offline trajectory calibration). While offline calibration increases machine time, it generally results in higher scan quality. However, a sufficient pose repeatability is necessary to ensure comparable or even superior accuracy to online calibration. In this contribution, we present a straightforward procedure to compare both types of trajectory calibration in a way that the differences of the results can directly be traced back to the influence of the pose repeatability. The multi-sphere reference object is not only used for trajectory calibration, but simultaneously as a measurement object for repeated measurements. The methodology is tested on both a twin robotic CT system and a conventional CT system that is additionally equipped with a hexapod manipulator for adaptive object tilting. Results showed, independent from the type of trajectory calibration, systematic measurement errors in the order of 10-5 to 10-4 of measured sphere distances and sphericity values below 50 μm. For sphere distances, random errors were increased by a factor of 5 due to the offline trajectory calibration, but were still low (< 1 μm) in comparison to systematic errors and the spread of different measurement features. Overall, both investigated systems demonstrated sufficient positioning repeatability for offline trajectory calibration. The method is in general also applicable to any other types of manipulator systems used for CT devices. It provides a workflow for the decision which type of trajectory calibration is preferable for a given CT system.

Comparison of Airborne Magnetic and Ground Magnetic for Identification of Sub-surface Condition Study Case Sand Caldera of Bromo-Tengger Volcanic Complex : Preliminary Study

Abstract The Bromo-Tengger Volcano Complex is a popular geotourism destination characterized by volcanic activity also unique geological and geomorphology settings. However, limited geophysical investigations have been conducted in this area, particularly using magnetic methods, to understand the subsurface conditions. Thus, this study aims to compare geophysical methods which are airborne and ground magnetic survey methods to identify the sub-surface conditions of Bromo-Tengger Volcano Complex. Airborne magnetic measurements were conducted using a Geotron Proton Precision Magnetometer G5 as the base and a Sensys Magdrone R3 with a DJI M600 drone as the rover with 5 ms of spacing, providing rapid coverage of large areas and minimizing interference. Ground magnetic measurements were taken using only a Geotron Proton Precision Magnetometer G5 for base and rover with 200 meters of spacing. Ground magnetic measurements serve as a comparison to assess resolution and potential data loss caused by factors such as flight altitude and data sampling rate. Combining both magnetic survey measurements enables a comprehensive understanding of the magnetic properties of the surveyed area. The airborne magnetic survey produced 2,097,134 data points in just two days, while the ground magnetic survey produced only 174 points in ten days. Although the airborne magnetic survey is less detailed, it can effectively interpret the subsurface conditions. On the other hand, the ground magnetic survey provides high-resolution results but is affected by local noise and temporal changes. Both surveys identified high anomalies in the southern and northeastern regions, which were interpreted as basalt lava flows. Medium anomalies are believed to be early pyroclastic fall deposits, while low anomalies indicate subsurface volcanic activity. Overall, the results of the airborne magnetic survey correlate well with the ground magnetic survey, making it a viable and time-saving alternative to large-scale magnetic measurements.

Testing [formula omitted]-attractor quintessential inflation against CMB and low-redshift data

Due to universality and attractor properties, α-attractor quintessential inflation establishes direct relations between inflationary observables such as the scalar tilt ns and the tensor-to-scalar ratio r, and late-time dark energy equation of state parameters w0 and wa. In this work, we examine three different physically motivated regimes, considering complete freedom in the parameter α, models inspired by supergravity where α takes on values up to α=7/3, and Starobinsky inflation (α=1). We investigate the consistency and constraints imposed by Cosmic Microwave Background measurements from the Planck satellite, B-mode polarization data from the BICEP/Keck collaboration, and low-redshift observations. Additionally, we consider small-scale CMB measurements released by the Atacama Cosmology Telescope, which give results approaching the Harrison-Zel’dovich spectrum (ns≈1). Here α-attractors lead to an improved fit over ΛCDM. For the large-scale CMB measurements, α≳2 models can provide equally good fits as ΛCDM.

Saving Private WAN: Using Internet Paths to Offload WAN Traffic in Conferencing Services

Large-scale video conferencing services incur significant network cost while serving surging global demands. Our work systematically explores the opportunity to offload a fraction of this traffic to the Internet, a cheaper routing option offered already by cloud providers, from WAN without drop in application performance. First, with a large-scale latency measurement study with 3.5 million data points per day spanning 241K source cities and 21 data centers across the globe, we demonstrate that Internet paths perform comparable to or better than the private WAN for parts of the world (e.g., Europe and North America). Next, we present Titan, a live (12+ months) production system that carefully moves a fraction of the conferencing traffic to the Internet using the above observation. Finally, we propose Titan-Next - a research prototype that jointly assigns the conferencing server and routing option (Internet or WAN) for individual calls. With 5 weeks of production data, we show Titan-Next reduces the sum of peak bandwidth on WAN links that defines the operational network cost by up to 61% compared to state-of-the-art baselines.

Sickle cell disease in India: the journey and hope for the future.

India, the most populous nation in the world, also has a high frequency of the sickle hemoglobin (HbS) allele globally. The Arab Indian HbS haplotype in India is characterized by a relatively high percentage of fetal Hb, with widely varying frequencies of α-thalassemia. Hence, sickle cell disease (SCD) in India was perceived to be mild. Advances in the past decade in screening and SCD management have revealed that the severity of SCD in India is comparable to many other parts of the world. Clinical features in India include vaso-occlusive crisis, acute chest syndrome, avascular necrosis, renal involvement, stroke, etc, at a relatively young age. Once a fatal disease of childhood, the majority of patients born with SCD are expected to survive into adulthood, largely because of improvements in comprehensive care programs including newborn screening, penicillin prophylaxis, transcranial Doppler, and hydroxyurea therapy. Several centers are performing hematopoietic stem cell transplants successfully for SCD. To address the urgent need to control and manage SCD in India's population, the Government of India launched the National Sickle Cell Anaemia Elimination Mission, with significant funding for large-scale measures to screen, treat, counsel, educate, and develop technologies and novel therapies and gene therapies.

Measuring DNS-over-HTTPS Downgrades: Prevalence, Techniques, and Bypass Strategies

DNS-over-HTTPS (DoH) is a privacy-enhancing protocol that encrypts plaintext query data in DNS resolution. However, DoH often faces accessibility challenges due to phenomena known as DoH downgrades, where DoH queries are reverted to plaintext DNS queries. Unlike downgrades in other security protocols, which are undoubtedly malicious, the act of downgrading DoH queries can be both desirable and undesirable depending on the context; e.g., enterprise networks are officially advised to avoid or downgrade DoH for security reasons. Recent research has drawn attention to the deeper examination of the phenomena of DoH downgrades, focusing on the prevalence, techniques, and potential bypass strategies. However, existing studies on DoH downgrades have several limitations, notably that they severely overestimate the severity of DoH downgrades across the globe as they lack any distinction between desirable and undesirable downgrades of DoH. In this work, we conduct a large-scale measurement study to provide a more accurate depiction of the DoH downgrade landscape. By minimizing the influence of desirable downgrades of DoH in our measurement probes, we show a skewed long-tail distribution of DoH downgrades across the globe. Our stateful probing techniques also reveal hidden DoH filtering mechanisms that were previously undetected. Furthermore, we design near perfect bypass strategies against existing DoH downgrades. Our study expands our limited understanding of DoH downgrades, offering a more accurate, fine-grained, and comprehensive view of the phenomena.

Precision compensation method for large-scale measurements based on full-space refractive index field reconstruction with vibratory mirror background oriented schlieren (VMBOS)

With the development of the large-scale equipment manufacturing industry, such as aircraft component assembly, wind turbine rotor blade measurement and large ship assembly the demand for optical measurement accuracy in large-dimensional spaces within industrial environments has become increasingly stringent. However, due to the presence of internal interference sources, light will no longer propagate in a straight line, thereby introducing measurement errors that cannot be ignored. To compensate for the measurement error, the refractive index field distribution within the large-dimensional measurement space must be reconstructed. Therefore, this paper proposed a vibratory mirror background oriented schlieren (VMBOS) based on vibratory scanning. This method scans the measurement space through the rotation of vibratory mirror to obtain light deflection angles at different directions. Subsequently, the refractive index field of the large-dimensional space is reconstructed by using the tomographic reconstruction algorithm. Then the optical path of the light in the optical measurement can be corrected through the Hamiltonian ray tracing algorithm, thereby achieving compensation for the measurement error. Finally, the VMBOS method has been verified through both simulation and experimental methods. The experimental results demonstrated that the method proposed in this paper can be applied to optical path correction and error compensation in large scale spaces.

Hesitant fuzzy linguistic preference consistency-driven consensus model with large-scale group interaction measure for venture capital investment selection

Recently, consensus-based large-scale group decision making (LSGDM) has been widely interactive with the study of social network, clustering and trust-based concepts. This study develops a novel hesitant fuzzy linguistic preference consistency-driven consensus model with interaction measure for large-scale group decision makers (DMs) in social networks. Firstly, directed social network is constructed by measuring the similarity between incomplete hesitant fuzzy linguistic preference relation (HFLPR) matrices. Community detection method is further conducted to categorize DMs into several communities. Secondly, driven by exploring the consistency of HFLPR matrices and interactive trusts between DMs, a novel optimization model is established to estimate the missing elements. Thirdly, the 2-order additive fuzzy measures of different coalitions between divided communities for capturing their fully or partially interactions are derived by a consistency-based optimization model. Accordingly, the attitudinal Choquet integral operator is employed to aggregate preferences into the collective one. Fourthly, a consensus improving mechanism is devised to achieve the unanimous agreement of DMs characterized by the bounded confidence. Personalized and specific adjustment scales obtained by investigating interval consistency of HFLPRs are provided in support of DMs’ modifications. Finally, an illustrative case on syndicated venture capital investment selection is conducted and related simulation analyses are performed to elucidate the feasibility and validity of the proposed methods. The comparisons with other approaches reveal the superiority and improvement of our proposal.

High spatial resolution φ-OFDR based on frequency-shift averaging and rotating vector summation

The coherent fading noise hinders the spatial resolution enhancements of phase optical frequency domain reflectometry (φ-OFDR). To mitigate the coherent fading noise, this study introduces frequency-shift averaging and rotating vector summation for strain measurements. The original Rayleigh backscattering signal was first divided into numerous sub-segments in frequency domain by using the frequency-shift averaging, and each sub-signal segment was transferred into vector signal with both intensity and phase information by using the rotating vector summation. Furthermore, a spatial position correction algorithm is incorporated to counteract the degradation of phase coherent, facilitating large-scale strain measurements. After optimizing the sub-frequency range and overlap ratio of the sub-signal in the frequency domain, we experimentally demonstrated that this method achieves strain measurement with a broad strain range of 2000 με, a high spatial resolution of 0.54 mm, and a high precision of 0.87%.

Future projections for mammalian whole-brain simulations based on technological trends in related fields

Large-scale brain simulation allows us to understand the interaction of vast numbers of neurons having nonlinear dynamics to help understand the information processing mechanisms in the brain. The scale of brain simulations continues to rise as computer performance improves exponentially. However, a simulation of the human whole brain has not yet been achieved as of 2024 due to insufficient computational performance and brain measurement data. This paper examines technological trends in supercomputers, cell type classification, connectomics, and large-scale activity measurements relevant to whole-brain simulation. Based on these trends, we attempt to predict the feasible timeframe for mammalian whole-brain simulation. Our estimates suggest that mouse whole-brain simulation at the cellular level could be realized around 2034, marmoset around 2044, and human likely later than 2044.

A Photometric Redshift Catalogue of Galaxies from the DESI Legacy Imaging Surveys DR10

The large-scale measurement of galaxy redshifts holds significant importance for cosmological research, as well as for understanding the formation and evolution of galaxies. This study utilizes a known sample obtained by cross-correlating the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys DR10 galaxy catalog with various galaxy catalogs from different spectroscopic surveys. The methods Easy and Accurate Photometric Redshifts from Yale (EAZY) and CatBoost are employed to estimate redshifts. In the case of EAZY, the known sample is used solely for testing, while CatBoost utilizes it for both training and testing purposes. The known sample is categorized into different subsamples based on various classification methods. Several CatBoost regression models are trained and optimized using these subsamples. By comparing the performance of different methods and models, it is observed that the two-step and two-part models outperform the one-step model, with further enhancements achieved through the combination of the two-step and two-part models. Based on the findings from all experiments, we propose a photometric redshift estimation workflow designed to facilitate the photometric redshift measurement of all galaxies within the DESI Legacy Imaging Surveys DR10. Consequently, a photometric redshift catalog has been released, comprising a total of 1,533,107,988 galaxies. Among these, 312,960,837 galaxies have reliable redshift estimates, determined using the CatBoost algorithm, with magnitude limits set at g > 24.0, r > 23.4, and z > 22.5. For galaxies with g, r, and z magnitudes exceeding these thresholds, the photometric redshifts estimated by EAZY can be employed as a reference.

Study on the Interface Reinforcement Effect of Bamboo Grid in Filled Loess Embankment in a High and Steep Gully

A bamboo grid is a new type of reinforcement material, which can replace traditional geogrids in the reinforcement of embankments. In this study, the reinforcement effect of the bamboo grid that is only set at the interface between the filled and undisturbed soils of the filled loess embankment in a high and steep gully was investigated. The influence of reinforcement position and grid spacing on the reinforcement effect was studied by carrying out a large-scale direct shear test, numerical simulation, and field measurement. The results indicated that the bamboo grid could enhance the shear strength of the reinforcement interface. The interface shear strength first improved and then decreased with the decrease in grid spacing. The differential settlement was significantly reduced after the reinforcement of the bamboo grid at the interface. Compared with other reinforcement positions, setting the bamboo grid in the upper part of the embankment was the most efficient and economical. When the grid spacing became dense, the reinforcement effect was improved as the differential settlement decreased. However, the improvement in the reinforcement effect by decreasing the grid spacing was limited, which meant there was an optimal grid spacing.

Visualization of Aerial Droplet Distribution for Unmanned Aerial Spray Systems Based on Laser Imaging

Unmanned aerial spray systems (UASSs) are a commonly used spraying method for plant protection operations. However, their spraying parameters have complex effects on droplet distribution. The large-scale 3D droplet density distribution measurement method is insufficient, especially since the downwash wind is easily affected by the environment. Therefore, there is a need to develop a technique that can quickly visualize 3D droplet distribution. In this study, a laser imaging method was proposed to quickly scan moving droplets in the air, and a test method that can visualize 3D droplet distribution was constructed by using the traveling mode of the machine perpendicular to the scanning plane. The 3D droplet distribution of targeted and conventional UAVs was tested, and the methods for signal processing, noise reduction, and point cloud rebuilding for laser imaging were developed. Compared with the simulation results, laser imaging showed the pattern of droplet distribution from the two UAV structures well. The results showed that the laser imaging based method for detecting 3D droplet distribution is feasible, fast, and environmentally friendly.

Measuring Street Quality: A Human-Centered Exploration Based on Multi-Sourced Data and Classical Urban Design Theories

Advancements in analytical tools have facilitated numerous studies on perceived street quality. However, most have focused on limited aspects of street quality, failing to capture a comprehensive perception. This study introduces a quantitative approach to holistically measure street quality by integrating three key dimensions: visual perception, network accessibility, and functional diversity. Using Beijing and Shanghai as case studies, we employed artificial neural networks to analyze street view images and quantify the visual characteristics of streets. Additionally, street network accessibility was assessed through spatial design network analysis, and functional diversity was evaluated using the entropy of points of interest (POIs) data. The evaluation results were combined using the analytic hierarchy process. The reliability and accuracy of this method were validated through further testing. Our approach offers a human-centered, large-scale measurement framework, providing valuable insights for urban street renewal and design.

RETRACTED: Theoretical development and validation of asphalt concrete density measurement using non-contact interdigital coplanar capacitive sensor

Asphalt concrete (AC) density serves as a critical criterion for quality control and quality assurance in asphalt pavement construction. Current non-destructive testing (NDT) approaches have shown potential for AC density measurement, but they present disadvantages such as inefficiency and unstable accuracy. This paper developed a novel NDT approach for AC density measurement based on non-contact interdigital coplanar capacitive sensor (ICCS). The feasibility of this approach was evaluated through both numerical and experimental validations. Firstly, the theoretical model of non-contact ICCS for AC density measurement was established based on conformal mapping technique, partial capacitance technique, and dielectric mixing model. Secondly, numerical simulations were performed to validate the developed theoretical model under two scenarios. Thirdly, laboratory experiments were conducted to measure capacitance data and predict density for three common types of ACs. Finally, the error of non-contact ICCS was discussed and compared with that of other NDT instruments. The results indicated that the developed theoretical model could establish the relationship between AC density and capacitance value, which provided the basis for AC density measurement using non-contact ICCS. It was also observed that the capacitance data obtained by the proposed model closely matched those computed by numerical simulations. The maximum errors between theoretical and numerical data were 4.10% and 1.08% for two cases respectively, which proved the feasibility of the theoretical model. Furthermore, experimental results indicated that the capacitance value of AC specimens increased by about 1 pF as the rolling time increases due to a decrease in the volume of air in AC, which reaffirms the validity of AC density measurement using non-contact ICCS. Additionally, the non-contact ICCS demonstrated excellent accuracy with a maximum error of 6.69%, which is comparable to the current mainstream NDT approaches. And it has the advantages of lower cost, simpler data processing and higher efficiency. The findings of this paper offer a new and reliable method and tool for non-destructive and large-scale AC density measurement.

Hippocampal recording with a soft microelectrode array in a cranial window imaging scheme: a validation study

The hippocampus has a crucial role in the formation, consolidation and recall of memories as well as in navigation related processes. These functions are in the focus of neuroscience and different disciplines have contributed to this research field for decades. Two-photon imaging in awake animals is a valuable new aspect for these observations, especially when it is supported by electrophysiology. In this study, we applied high speed two-photon hippocampal imaging through a chronically implanted, soft, transparent microelectrode (STM) device incorporated into a cranial window chamber in awake mice. We monitored the impedance of the recording sites over the course of the experiments to observe long-term changes in recording quality. The large-scale ipsilateral local field potential (LFP) recordings from the dorsal hippocampus provided reliable sharp wave-ripples (SPW-Rs), multi-unit activity (MUA) and single-unit activity (SUA) for up to two months. Calcium imaging of GCaMP6f. labeled cells from the CA1 pyramidal layer under the transparent device was possible even after six months in thy1-GCaMP6f. transgenic mice. We investigated the immune response with GFAP staining after the end of the long-term experiments. Based on our results, this dedicated transparent electrode device proved to be suitable for simultaneous two-photon imaging and large-scale electrophysiological measurements in chronic experiments in mice.

Rapid acquisition of battery impedance across multiple scenarios using DRT analysis

Quick and accurate electrochemical impedance spectroscopy (EIS) measurement has always been challenging. This paper proposes a reliable and fast measurement method, which, based on battery characteristics, utilizes a distribution of relaxation times (DRT) extraction algorithm to construct a characteristic spectrum and map it to a binary sequence. The proposed method for constructing characteristic sequences is applicable to battery measurements in multiple scenarioes. The paper additionally introduces a hybrid reconstruction filtering (HRF) method that amalgamates the DRT reconstruction technique and non-parametric estimation techniques. The filtering method does not require preset parameters, resulting in high accuracy and applicability. Simultaneously, combining the characteristic sequence with HRF ultimately obtains a smooth and complete EIS curve under varying states of charges (SOCs), temperatures, and capacities. The proposed testing framework obtains impedance from 0.1 Hz to 2000 Hz <13.2 s. The overall measurement error for batteries with different internal resistances does not exceed 2 %. This work provides a reliable characteristic optimization sequence for large-scale battery impedance measurements, offering a method that is both simple and highly versatile.

Large-Scale Measurements and Optimizations on Latency in Edge Clouds

Large-Scale Measurements and Optimizations on Latency in Edge Clouds

Development of a high-precision long trace profiler utilizing shear measurements.

Compensating for the pitch error in the scanning movement is a fundamental issue when conducting large-scale surface shape measurements with deflectometric profilers. This paper presents a new long trace profiler employing a shearing measurement technique. In this setup, the optical head and the mirror under test are mounted on two independent parallel movable air-bearing carriages to enable shearing and scanning movements separately. The distance between the optical head and the tested mirror remains fixed, effectively minimizing the influence of system errors resulting from imperfections in optical devices. Simulation studies show that the double shear measurement method with a low-spatial-frequency filtering process can effectively mitigate high-frequency angular measurement errors introduced by the instability of the air-bearing stage. Experimental tests conducted on flat mirrors demonstrated a precision of less than 50 nrad rms, thereby confirming the robustness of the system.

Development and in situ application of actively heated fiber Bragg grating cable for soil water content measurement

The actively heated fiber-optic (AHFO) technology has emerged as a frontier and hotspot in soil water content measurement, offering advantages such as easy installation, large-scale distributed measurement capability, and resistance to electromagnetic interference. However, current AHFO water content sensors fail to simultaneously achieve high precision, applicability for deep soil, and automated real-time monitoring, thereby limiting their development and application. Therefore, this study introduces a novel actively heated fiber Bragg grating (AH-FBG) cable. Laboratory tests were conducted to assess the heating uniformity of the AH-FBG cable and to establish the temperature characteristic value (Tt) – soil water content (θ) calibration formula for water content measurement. Subsequently, AH-FBG cables were deployed for in situ soil water content monitoring in a test pit on the Loess Plateau. Through two-year monitoring data verified the accuracy of the AH-FBG cable and elucidated the spatiotemporal distribution of in situ loess water content. Laboratory results demonstrated superior heating uniformity of AH-FBG cable, with a Tt standard deviation of approximately 0.3 °C. In the field, the AH-FBG cable exhibited excellent performance in soil water content measurement, achieving a high accuracy of 0.023 cm3/cm3. Further analysis revealed that the θ fluctuation predominantly occurred within a 10 m depth from the soil surface, with an overall upward trend over the two-year monitoring period; the response of shallow θ to precipitation was significant but exhibited increasing hysteresis with depth; frequent precipitation significantly enhanced water infiltration depth. This study provides technical guidance for high-precision, quasi-distributed, automated and real-time water content measurement of deep soil.