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The dual five-axis machining machine is state-of-the-art equipment designed for producing thin-walled aerospace parts like skins and panels. It comprises two five-axis machine tools with mirrored synchronous motions: one bi-rotary machine for milling and the other machine for follow-up support. The high absolute accuracy of the five-axis machine tools themselves and the high synchronous motion accuracy between the two machines are both crucial to ensure machining accuracy. This paper proposes an efficient method to measure and identify geometric and dynamic errors of dual five-axis machine tools. Using the R-test combined with three measurement trajectories to measure the absolute motion error of two five-axis machine tools and the synchronous motion error between the two machines. The designed trajectories include the main rotary axis linkage conditions and can fully reflect the primary motion forms of the dual five-axis machine tool. The main position-independent geometric errors and rotational axis linkage dynamic errors are identified by converting quasi-static and dynamic measurement data from three different trajectories into a unified reference coordinate system. The entire process requires only one instrument installation, effectively avoiding time-consuming repetitive installations and calibration processes while reducing the impact of installation errors on results. The effectiveness of the proposed method for measuring and identifying the geometric and dynamic errors is analyzed combined with Monte Carlo simulation. Experiments were carried out on a dual five-axis mirror milling system (MMS) with a 5000 mm X-stroke. Both simulations and experiments confirmed that the proposed method is efficient in quickly identifying key error sources of the MMS. [Display omitted] • An efficient method to measure and identify geometric and dynamic errors during synchronous motion of the MMS is proposed. • A geometric and dynamic error model is introduced for identifying key errors using error sensitivity theory. • A 3-step measurement strategy that enables rapid separation of linkage errors of the MMS is introduced. • Both simulation and experiment show the proposed method could obtain key error sources of the MMS with high efficiency. [ABSTRACT FROM AUTHOR]

Trajectory similarity measurement is a basic and vital task in trajectory data mining, which has attracted extensive research in the past decades. Recent works focused on the sequence and hierarchy property of trajectories to construct similarity measurements. However, these methods ignore the user information on the visiting locations, such as semantic and time distribution. In light of this, a novel trajectory similarity measurement based on Node‐Sequence Hierarchical Digraph (NSHD) framework is proposed in this article. We first propose a Time‐Weighted Stay Point Detection (TWSPD) method to extract real visiting locations of users more accurately. Then, the nodes of digraph are obtained by clustering users' stay points and the edges of digraph are sequence information that users move between these nodes. An Advanced Earth Mover's Distance (AEMD) is proposed to measure the node similarity between users, considering visiting time distribution and semantic information simultaneously. Both node and sequence similarities are used to calculate the similarity score to obtain the final trajectory similarity measurement. Experiments on Geolife and T‐Drive datasets show that our proposed method offers competitive performance with mean reciprocal rank values reaching 96.01 and 81.26%, which outperforms related trajectory similarity measurements by more than 10 and 15%. [ABSTRACT FROM AUTHOR]

The four-axis variable trajectory equal-thickness screen (FAVTETS) achieves equal-thickness screening by appropriate excitation force generated by four eccentric rotors in synchronized motion. The forced synchronization exciter is characterized by an unsatisfactory synchronization effect due to the wear of transmission parts. Hence, in this paper, the four-axis controlled synchronization of FAVTETS is investigated, and an intelligent control system is proposed. Firstly, research is conducted on the variable trajectory characteristics of FAVTETS. Next, the sliding mode, fuzzy, and PID controllers are designed and compared to obtain an ideal control effect. Moreover, the influence of torsional stiffness of flexible coupling on control accuracy is considered. The results show that the sliding mode controller has a good control effect. Based on the aforementioned, the simulation model of a four-axis controlled synchronization structure is established via MATLAB/Simulink. Finally, Labview is employed to design the four-axis controlled synchronization software system. Then, the physical experiment is carried out. The four-axis controlled synchronization and vibration trajectory measurement results verify the effectiveness and robustness of the intelligent control system. [ABSTRACT FROM AUTHOR]

Background: Growth studies rely on longitudinal measurements, typically represented as trajectories. However, anthropometry is prone to errors that can generate outliers. While various methods are available for detecting outlier measurements, a gold standard has yet to be identified, and there is no established method for outlying trajectories. Thus, outlier types and their effects on growth pattern detection still need to be investigated. This work aimed to assess the performance of six methods at detecting different types of outliers, propose two novel methods for outlier trajectory detection and evaluate how outliers affect growth pattern detection. Methods: We included 393 healthy infants from The Applied Research Group for Kids (TARGet Kids!) cohort and 1651 children with severe malnutrition from the co-trimoxazole prophylaxis clinical trial. We injected outliers of three types and six intensities and applied four outlier detection methods for measurements (model-based and World Health Organization cut-offs-based) and two for trajectories. We also assessed growth pattern detection before and after outlier injection using time series clustering and latent class mixed models. Error type, intensity, and population affected method performance. Results: Model-based outlier detection methods performed best for measurements with precision between 5.72-99.89%, especially for low and moderate error intensities. The clustering-based outlier trajectory method had high precision of 14.93-99.12%. Combining methods improved the detection rate to 21.82% in outlier measurements. Finally, when comparing growth groups with and without outliers, the outliers were shown to alter group membership by 57.9 -79.04%. Conclusions: World Health Organization cut-off-based techniques were shown to perform well in few very particular cases (extreme errors of high intensity), while model-based techniques performed well, especially for moderate errors of low intensity. Clustering-based outlier trajectory detection performed exceptionally well across all types and intensities of errors, indicating a potential strategic change in how outliers in growth data are viewed. Finally, the importance of detecting outliers was shown, given its impact on children growth studies, as demonstrated by comparing results of growth group detection. [ABSTRACT FROM AUTHOR]

The article firstly reviews the current level of research on the dynamics of tower cranes. The publications covering research on the dynamics of crane systems and issues related to sway and trajectory of a load on a flexible suspension are considered. Taking into account the actual characteristics of the drive in dynamic models of tower cranes remains an urgent issue and is the aim of this study To achieve this goal, a multi-mass dynamic model of a tower crane with a slewing tower was obtained, where the drive of the slewing mechanism is taken into account as a separate mass. This approach is the main scientific novelty of this article and enables determination of the forces in elastic connections and other dynamic and kinematic characteristics of the movement depending on changes in the control parameter of the slewing mechanism motor. At the same time, it is possible to take into account the change in torque through the equation of mechanical characteristics, which allows to additionally take into account the influence of internal processes in the drive. When writing the system of equations describing this system, the Lagrange equations of the second kind were used. The resulting mathematical model takes into account the inertial (moments of inertia, reduced masses), elastic and damping characteristics of the structure. The complex movement of the load in both planes is considered. A numerical calculation is performed based on the parameters of a real crane. The change in the drive control parameter during the working cycle is modelled according to different laws. [ABSTRACT FROM AUTHOR]

Measuring trajectory angles of bullet defects at a crime scene is an important part of crime scene investigation as these angles can be used for shooting incident reconstructions. The Washington State Patrol Crime Scene Response Team (WSP CSRT) had a desire to report and use measured trajectory angles. To report quantitative measurements, a statement of uncertainty for the measurement must also be reported due to an accreditation requirement through the ANSI National Accreditation Board (ANAB), through which the WSP CSRT is accredited. This evaluation examined the measurement uncertainty of the 3D laser scanning method that the WSP CSRT utilizes for measuring the vertical and azimuth angles from trajectory rods fitted to bullet defects. Three studies were performed which examined the variation of vertical and azimuth angle measurements from trajectory rods on flat surfaces, the variation of azimuth angle measurements from a trajectory rod on a curved surface, and a traceability study with known vertical and azimuth angle measurements. Seven common substrates were selected as target materials and were shot with 9 mm Luger and 0.45 Auto caliber bullets. A vehicle with one bullet defect was utilized for the curved surface study. The WSP's current fleet of Trimble X7 3D laser scanners, the WSP Criminal Investigation Division (CID) Detectives who operate these scanners, and the Forensic Scientists responsible for trajectory rod placement and angle measurements were utilized. An overall measurement uncertainty of +/− 2.6 degrees at an approximate 95% confidence interval was determined for all trajectory angles measured from trajectory rods. [ABSTRACT FROM AUTHOR]

In this paper, we review some of the extant literature on the study of interstellar objects (ISOs). With the forthcoming Vera C. Rubin Telescope and Legacy Survey of Space and Time (LSST), we find that 0. 3 8 − 8 4 'Oumuamua-like interstellar objects are expected to be detected in the next 10 years, with 95% confidence. The feasibility of a rendezvous trajectory has been demonstrated in previous work. In this paper, we investigate the requirements for a rendezvous mission with the primary objective of producing a resolved image of an interstellar object. We outline the rendezvous distances necessary as a function of resolution elements and object size. We expand upon current population synthesis models to account for the size dependency on the detection rates for reachable interstellar objects. We assess the trade-off between object diameter and occurrence rate, and conclude that objects with the size range between a third of the size and the size of 'Oumuamua will be optimal targets for an imaging rendezvous. We also discuss expectations for surface properties and spectral features of interstellar objects, as well as the benefits of various spacecraft storage locations. [ABSTRACT FROM AUTHOR]

Introduction: The newly introduced Cellular Oxygen METabolism (COMET®) monitor enables the measurement of mitochondrial oxygen tension (mitoPO2) using the protoporphyrin IX triplet state lifetime technique (PpIX-TSLT). This study aims to investigate the feasibility and applicability of the COMET® measurements in the operating theatre and study the behavior of the new parameter mitoPO2 during stable operating conditions. Methods: In this observational study mitochondrial oxygenation was measured in 20 patients during neurosurgical procedures using the COMET® device. Tissue oxygenation and local blood flow were measured by the Oxygen to See (O2C). Primary outcomes included mitoPO2, skin temperature, mean arterial blood pressure, local blood flow and tissue oxygenation. Results: All patients remained hemodynamically stable during surgery. Mean baseline mitoPO2 was 60 ± 19 mmHg (mean ± SD) and mean mitoPO2 remained between 40–60 mmHg during surgery, but tended to decrease over time in line with increasing skin temperature. Conclusion: This study presents the feasibility of mitochondrial oxygenation measurements as measured by the COMET® monitor in the operating theatre and shows the parameter mitoPO2 to behave in a stable and predictable way in the absence of notable hemodynamic alterations. The results provide a solid base for further research into the added value of mitochondrial oxygenation measurements in the perioperative trajectory. [ABSTRACT FROM AUTHOR]

Methodological and technical possibilities of monitoring temperature fields along a 1000-km track in the Sea of Japan using acoustic thermometry are presented. The proposed tomographic method for monitoring the dynamics and structure of waters is based on emission and reception of complex phase-shift keyed signals on a diagnosed path with determination of the propagation time along various ray trajectories with further measurement of the speed of sound and temperature. The physical prerequisites for practical use of thermometric studies at large distances are based on the acoustic "mudslide" effect: the phenomenon of the transition of acoustic energy from the bottom shelf area to an underwater sound signal of the deep ocean. A high-precision system of acoustic thermometry on the basis of tomographic schemes with mobile and stationary hydroacoustic emitters and receiving systems is proposed and tested with the example of the Sea of Japan. [ABSTRACT FROM AUTHOR]

The shield of the SMA-2 utilizes a quadrilateral mechanism with a corner cylinder generating a lemniscate. The synthesis of the quadrilateral mechanism, its geometric and kinematic analysis in correlation with the geometry and kinematics of the entire support, raises challenging analytical issues. For this reason, in the present work, we have theoretically and practically analyzed the geometry and kinematics of the mechanism, demonstrating the utility of using computer software for modeling and simulation in addressing these problems. [ABSTRACT FROM AUTHOR]

In order to improve the accuracy of well trajectory calculation in measurement while drilling, a segmented well trajectory calculation method based on magnetic inertia measurement is proposed in this study. When the drill bit is stopped, the tool face angle model recognition method is used to identify the borehole trajectory model of the test section, and the sub-measurement points of the test section under the constraints of the model are generated according to the depth change in the real-time measurement data. Then, the magnetic inertia measurement data is used to correct the measured points, and the corrected points are identified by piecewise trajectory model. Finally, the corresponding models are calculated by piecewise model. The experimental results show that the absolute error of the coordinate increment is reduced from 0.840 m of the single model algorithm to 0.146 m after adopting the new method, which shows that compared with the single model of the well trajectory calculation method, the error of the segmented well trajectory calculation method is smaller and the wellbore trajectory calculation method can improve the accuracy of the borehole trajectory calculation. [ABSTRACT FROM AUTHOR]

Seed dispersal by wind is one of the most important dispersal mechanisms in plants. The key seed trait affecting seed dispersal by wind is the effective terminal velocity (hereafter "terminal velocity", Vt), the maximum falling speed of a seed in still air. Accurate estimates of Vt are crucial for predicting intra‐ and interspecific variation in seed dispersal ability. However, existing methods produce biased estimates of Vt for slow‐ or fast‐falling seeds, fragile seeds, and seeds with complex falling trajectories. We present a new video‐based method that estimates the falling trajectory and Vt of wind‐dispersed seeds. The design involves a mirror that enables a camera to simultaneously record a falling seed from two perspectives. Automated image analysis then determines three‐dimensional seed trajectories at high temporal resolution. To these trajectories, we fit a physical model of free fall with air resistance to estimate Vt. We validated this method by comparing the estimated Vt of spheres of different diameters and materials to theoretical expectations and by comparing the estimated Vt of seeds to measurements in a vertical wind tunnel. Vt estimates closely match theoretical expectations for spheres and vertical wind tunnel measurements for seeds. However, our Vt estimates for fast‐falling seeds are markedly higher than those in an existing trait database. This discrepancy seems to arise because previous estimates inadequately accounted for seed acceleration. The presented method yields accurate, efficient, and affordable estimates of the three‐dimensional falling trajectory and terminal velocity for a wide range of seed types. The method should thus advance the understanding and prediction of wind‐driven seed dispersal. [ABSTRACT FROM AUTHOR]

The geometrical error of rotation axis is a fundamental error source for five-axis machine tool (FAMT). Therefore, enhancing the accuracy of rotation axis is one of the important means to enhance the machining accuracy of FAMT. This paper developed a novel approach for geometric error identification of rotation axis. Firstly, a single axis rotation identification model using double ball bar is established based on Homogeneous Transformation Matrix (HTM) theory. Secondly, the five measurement trajectories are developed to determine the geometric errors of the C-axis. In addition, the fourth-order truncated Fourier series is used to fit the discrete measurement data under the premise of considering the installation error of the double ball bar instrument. Finally, simulation and experiments indicate that the proposed method is effective and feasible. The SSE values of the fitting model are above 90.39. In the compensation experiment based on identification method, the average machining accuracy of workpiece has been improved by 28.6% compared with RTCP. [ABSTRACT FROM AUTHOR]

Since the Argo program began, 568 floats returned almost 31,000 profiles, at high‐southern latitudes, with no measured position. These data are either disseminated with positions linearly interpolated between known positions, or with no geographic positions. Here, we present a simple method for estimating unknown Argo float trajectories. We try to identify trajectories that approximately follow contours along three different properties: potential vorticity (f/H), sea‐level, and density at 1,000 m. No single property‐constraint can be used to estimate trajectories for all position‐gaps. Each constraint fails for 9%–18% of gaps, where no continuous contour between the end‐points exists. But all constraints fail for the same position‐gap, for fewer than 1% of cases. For a given position‐gap, when a trajectory is identified using two or three different constraints, we select the shortest trajectory to be used to "fill the gap". This selection process could be performed better by an Expert Operator, inspecting each estimated trajectory, and selecting the trajectory that is most consistent with a priori knowledge of the circulation in the vicinity of the position‐gap. Nonetheless, using the objective metric for selection, we find that 41.2% of position‐gaps use the f/H‐constraint, 32.1% use density, and 25.8% use sea‐level. We assess the estimated trajectories for consistency, by comparing bottom depths beneath trajectories to the deepest measurements in each profile. We find inconsistencies for 11.6% of position‐gaps using our method, compared to 28.0% using linearly‐interpolated trajectories. Adoption of the estimated trajectories for measurements under ice may yield benefits to many applications. Plain Language Summary: Argo floats measure ocean properties between the surface and 2,000 m depth, providing an estimate of their position using satellite fixes when they're at the surface. When a float samples under ice, it cannot measure its position. When that happens, the float continues to sample, collecting profiles over time, and later sends data if and when it finally surfaces. While under ice, the geographic positions of the float's observations are unknown, making it hard for scientists and marine users to exploit the data. Here, we present a method for estimating the float's position, while under ice, by assuming that the float's path followed contours of some climatological ocean properties. The method won't always be accurate, because floats mostly move with ocean properties that change with time. But sometimes, we expect the new estimates will be accurate enough to make the data more useful. Key Points: Almost 31,000 Argo profiles have sampled under ice at high‐southern latitudes, and are disseminated without measured positionsWe present a method to estimate missing trajectories, constrained by multiple different oceanic propertiesNo single property works for all cases. But using multiple constraints, realistic trajectories are estimated for almost all position‐gaps [ABSTRACT FROM AUTHOR]

The task of detecting elements of group flight test objects is considered. The relevance of the research is related to the growing need for metrological support of external trajectory measurements when testing advanced multi-agent systems, which comprise aircrafts as elements. Existing algorithms for detecting objects used in modern optoelectronic stations (systems) are analyzed. According to the conducted analysis, the failure of these algorithms to meet the requirements imposed on testing group objects is largely due to the complexity of selecting objects against the atmospheric background. In order to ensure efficient detection of group objects, it is proposed to use additional highly-informative features that reflect the physical nature of test objects, such as the shape of the spectrum of light reflected from various materials. Such features can be identified in the process of preliminary hyperspectral analysis of test objects with a subsequent reduction in the data dimensionality. In order to eliminate errors arising during the rotation and partial overlapping of test objects, it is proposed to use neural network methods – in particular, the neural network detector YOLO v2. An approach to organizing data for training this detector is proposed along with an architecture that provides high accuracy and speed of information processing. These detector properties were confirmed experimentally on the basis of images exported from a model of external trajectory measurements. A procedure for implementing neural network detection of group test objects is proposed. The obtained results can be used when developing hardware and software for optoelectronic tracking systems. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of multiple agents circumnavigating group targets within finite time. Unlike most existing works in which agents can circumnavigate with a regular-shaped trajectory in the mission area, the problem of agents with an irregular-shaped trajectory in the area with obstacles is addressed in the paper. The agents can only obtain the bearing information of the targets. First, a scheme for establishing the group targets as an extended convex hull is presented. And the boundary of the extended convex hull is taken as the scheduled irregular-shaped trajectory. Then, a finite-time estimator is presented to localise the positions of the targets and their geometric centre. Afterward, a finite-time control protocol is proposed to drive agents along the irregular-shaped trajectory within finite time. Subsequently, an obstacle avoidance method is provided for agents to avoid obstacles on the path to the expected trajectory. Finally, simulation results validate the effectiveness of the theoretical results in this paper. [ABSTRACT FROM AUTHOR]

The semantic enrichment of mobility data with several information sources has led to a new type of movement data, the so‐called multiple aspect trajectories. Comparing multiple aspect trajectories is crucial for several analysis tasks such as querying, clustering, similarity, and classification. Multiple aspect trajectory similarity measurement is more complex and computationally expensive, because of the large number and heterogeneous aspects of space, time, and semantics that require a different treatment. Only a few works in the literature focus on optimizing all these dimensions in a single solution, and, to the best of our knowledge, none of them proposes a fast point‐to‐point comparison. In this article we propose the Multiple Aspect Trajectory Index, an index data structure for optimizing the point‐to‐point comparison of multiple aspect trajectories, considering its three basic dimensions of space, time, and semantics. Quantitative and qualitative evaluations show a processing time reduction of up to 98.1%. [ABSTRACT FROM AUTHOR]

The purpose of this article is to show the validity of the simulation result for particle charge and trajectory in an electrostatic precipitator (ESP) with multiple wire electrodes, and the effect of the number of wire electrodes on the relationship between collection efficiency and discharge power. The ESP in this article has wires-and-plates configuration. The potential, the electric field intensity, the negative ion density, the ionic gas flow, the charge of the particles and the charged particle trajectory in the ESP were calculated. In the experiment, the charged particle trajectory was measured by a particle image velocimetry (PIV). In addition, the analysis and the experimental collection efficiencies as a function of input power in the ESPs with a single wire electrode and three wire electrodes were compared, and the effect of the number of wire electrodes on the power consumption was investigated. As a result, the x and y components of the particle velocity measured using the PIV almost agreed with the simulated result. The validity of the simulation result for charged particle trajectory, which was calculated by fitting the analyzed corona current to the experimental value, in an ESP with multiple wire electrodes was demonstrated. Also, both analysis and experimental collection efficiencies by the ESP with three wire electrodes were greater than those with the single wire electrode at the same input power. An analysis revealed that this was because the residence time of the particles in the ESP with three wire electrodes was longer than that with the single wire electrode. [ABSTRACT FROM AUTHOR]

Background Hyperkalaemia is a common condition in patients with comorbidities such as chronic kidney disease (CKD) or congestive heart failure (HF). Moreover, severe hyperkalaemia is a potentially life-threatening condition that is associated with a higher risk of adverse clinical events such as ventricular arrhythmias and sudden cardiac death. Currently, data regarding the prognostic implications of chronic hyperkalaemia are available; however, information about the long-term clinical consequences after an episode of severe hyperkalaemia remains scarce. The objective of this study was to evaluate the association between the trajectory of potassium measurements in patients with acute hyperkalaemia and long-term all-cause mortality. Methods This is a retrospective observational study that included patients with acute severe hyperkalaemia [potassium (K) >6 mEq/L] without haemolysis in the emergency room of Dr Peset University Hospital in Valencia, Spain searching the lab database from January 2016 to March 2017. The multivariable-adjusted association of serum potassium with mortality was assessed by using comprehensive state-of-the-art regression methods that can accommodate time-dependent exposure modelling. Results We found 172 episodes of acute hyperkalaemia in 160 patients in the emergency room. The mean ± standard deviation age of the sample was 77 ± 12 years and 60.5% were males. The most frequent comorbidities were CKD (71.2%), HF (35%) and diabetes mellitus (56.9%). Only 11.9% of the patients were on chronic dialysis. A quarter of the patients did not have previous CKD, making hyperkalaemia an unpredictable life-threatening complication. During the acute episode, mean potassium and estimated glomerular filtration rate (eGFR) were 6.6 ± 0.6 (range 6.1–9.2) mEq/L and 23 ± 16 (range 2–84) mL/min/1.73 m2, respectively. After a median (interquartile range) follow-up of 17.3 (2.2–23.7) months, 68 patients died (42.5%). Recurrences of hyperkalaemia (K >5.5 mEq/L) were detected in 39.5% of the patients who were monitored during follow-up. We found that previous potassium levels during an acute severe hyperkalaemia episode were not predictors of mortality. Conversely, the post-discharge longitudinal trajectories of potassium were able to predict all-cause mortality (overall P = 0.0015). The effect of transitioning from hyperkalaemia to normokalaemia (K >5.5 mEq/L to K ≤5.5 mEq/L) after the acute episode was significant, and inversely associated with the risk of mortality. Conclusions Potassium levels prior to a severe hyperkalaemic event do not predict mortality. Conversely, following an episode of acute severe hyperkalaemia, serial kinetics of potassium trajectories predict the risk of death. Further evidence is needed to confirm these findings and clarify the optimal long-term management of these patients. [ABSTRACT FROM AUTHOR]

• Innovative efficiency: Introducing a novel absolute phase extraction algorithm requiring only three grayscale images for high-speed 3D reconstruction. • Robust performance: Demonstrating resilience to environmental factors such as noise, reflectivity variations, and shadows commonly encountered in practical measurement scenarios. • Adaptive error correction: Proposing an error correction technique that adaptively self-corrects non-linear errors in the phase obtained through the algorithm, ensuring enhanced accuracy. • Cost-effective solution: Eliminating the need for additional pattern-assisted phase unwrapping or expensive equipment, providing a cost-effective 3D measurement solution. • Dynamic scene advantage: Outperforming in dynamic scenes, achieving high-quality reconstruction with minimal projected fringes and reduced computational requirements. The structured light three-dimensional (3D) measurement technology based on optical metrics has gained increasing applications, and there is a growing demand for capturing transient trajectory changes in dynamic scenes. Conventional temporal phase unwrapping (TPU) approaches often require multi-frequency fringe patterns for application. However, the inevitable conflict arises between the number of projected fringe patterns and the measurement speed. This paper proposes a highly accurate and robust 3D measurement method using only 3-step phase-shifting fringe patterns. To precisely reconstruct the 3D shape using the fewest fringe patterns, it is essential to extract as much information as possible from the available patterns. Therefore, we calculate the wrapped phase distribution using 3-step phase-shifting fringe patterns to ensure accuracy. Simultaneously, the trapezoidal phase-shifting method is employed to calculate the intensity ratio distribution. Through the proposed region-based indexing method, the intensity ratio map is transformed into an unwrapped phase map. Additionally, a novel self-correction method is introduced to correct the non-linear errors in the unwrapped phase map, which is then utilized for the calculation of the fringe order required for phase unwrapping. This high-speed measurement method utilizes only 3-step phase-shifting fringe patterns while retaining the advantages of TPU, meeting the requirements of high-speed and full-field measurements. Experimental results on both static and dynamic scenes validate the effectiveness and versatility of the proposed method, demonstrating its flexibility and simplicity in application. In our 3D measurement system, the method achieves 3D reconstruction of the dynamic object's trajectory at a measurement speed of 107 frames per second. [ABSTRACT FROM AUTHOR]

Recent experiments and simulation studies showed that protein/DNA folding barriers inferred from folding rates or from potentials of mean force are often much higher than the barriers estimated from the distributions of transition path times. Here a toy model is used to explain a possible origin of this effect: It is shown that when the transition in question involves an entropic barrier, the one-dimensional Langevin model commonly used to interpret experimental data, while adequately predicting the transition rate, fails to describe the properties of the subset of the trajectories that form the transition path ensemble; the latter may still be describable in terms of a one-dimensional model, but with a different potential, just as observed experimentally. [ABSTRACT FROM AUTHOR]

Measurement trajectory error, geometric error of the measurement trajectory, and systematic error attributable to the velocity of sound are the main sources of the errors that affect the positioning accuracy of seafloor geodetic stations. Here, we propose a systematic error difference constraint model designed to control the influence of systematic errors in seafloor geodetic station positioning. An error equation is constructed using system error parameters and the position parameters of the seafloor geodetic station to be estimated. On the basis of the subtle positional change characteristics of an adjacent epoch, the constraint condition of the adjacent epoch difference is added. Finally, for the case of a single seafloor transponder, analysis of the results of a simulation and an actual experiment confirm that the proposed model with a systematic error difference constraint can effectively control the influence of systematic errors on seafloor positioning and overcome the ill-posed model issue, thereby enabling positioning results that are more accurate. • A systemic error difference constraint model is constructed using the constraint condition that the systemic errors of the front and back epochs are approximately equal, effectively resisting the influence of adjacent epochs' observation systemic errors on the positioning results of seafloor reference points. [ABSTRACT FROM AUTHOR]

The first point of contact between a spherical blood drop and a surface is related to the angle between the trajectory of the blood drop and the surface being struck. This angle is often referred to as the impact angle which can be estimated by knowing the width and length of the resultant elliptical bloodstain. Most software programs dedicated to area of origin analysis indicate the location of the backtracked bloodstain trajectory to be at the geometric centre or at the tip of the bloodstain ellipse. However, it is unknown how the first point of contact and the blood drop trajectory (here defined as the locus of the centre of mass of the drop as it travels) are related empirically. Thus, this study aims to look at how the initial point of contact and the trajectory at the impact of a blood drop relates to the formed bloodstain ellipse. Two volumes of blood (0.013 ml and 0.071 ml) were dropped from a height of 10 cm and 40 cm onto an inclined surface at 0°, 15°, 30°, 45°, 60°, and 75°. The transition from a spherical blood drop to an elliptically shaped bloodstain was recorded using a high-speed camera for all tests. A total of 72 ellipses were analyzed to determine the location of the first point of contact and trajectory point of the blood drop and how they relate to the formed elliptical bloodstain. A relationship was found between the first point of contact and the bloodstain trajectory which was dependent on the impact angle. However, there were clear deviations from theoretical assumptions due to blood drop oscillations, the effects of gravity, and the natural fluid characteristics of blood. The results of this study may assist bloodstain pattern analysts and software developers by more accurately applying the location of the blood drop trajectory based on empirical data. • The first point of contact follows a similar trend to the sine value. • The trajectory point moves along the half-length of the bloodstain. • The trajectory point and first point of contact are mainly at different locations. • The trajectory point is not always at the centre or tip of the ellipse. • The first point of contact is not always at the centre of tip of the ellipse. [ABSTRACT FROM AUTHOR]

Following the recent advent of Process Analytical Technologies, dataset production has undergone significant leverage. In this new abundance of data, isolating meaningful, informative content is critical for process dynamic modeling. This paper proposes a data-driven algorithm based on low-rank matrix approximation, the so-called successive projection algorithm, to retrieve a minimal set of macroscopic reactions, the corresponding stoichiometry, and a consistent kinetic model structure from the measurements of the trajectories of the species concentrations during cultures in a bioreactor. The proposed method is successfully validated in simulation, considering a case study related to monoclonal antibody (MAb) production with hybridoma cell cultures. • A data-driven tool for macroscopic modeling of bioprocesses is proposed. • The approach is based on a successive projection algorithm. • The algorithm retrieves the number of macroscopic reactions and computes stoichiometry. • The data-driven method infers a consistent kinetic structure for bioprocess modeling. [ABSTRACT FROM AUTHOR]

We analyze the dynamics of N-qubit systems in the measurement space under the action of symmetric Hamiltonians. We show that the evolution of the discrete distribution function, representing the global properties of multipartite states, becomes quasicontinuous in the macroscopic limit N ≫ 1. The shorttime dynamics can be approximately described as a propagation along "classical" trajectories in the measurement space. [ABSTRACT FROM AUTHOR]

Cryogenic deuterium–tritium ice target implosions on OMEGA with new small-spot (SG5-650) distributed phase plates (DPPs) achieved an (11 ± 4) % increase in energy coupling compared to implosions with larger-spot SG5-850 DPPs by decreasing the ratio of the laser spot diameter to the target diameter from 0.93 to 0.75. The SG5-650 DPPs provide a focus spot size of 674 μm, which is defined as the diameter that encircles 95% of the measured beam energy compared to 834 μm for the SG5-850, which are the standard DPPs in cryogenic target implosions on OMEGA. The hydrodynamic efficiency, defined as the ratio of the kinetic energy in the imploding shell to the laser energy, increased from 4.5% to 5.0% based on radiation-hydrodynamic calculations benchmarked to shell trajectory and bang-time measurements. The higher coupling came with a trade-off of an increased hot-electron production as well as increased hydrodynamic instabilities seeded by a larger mode-10 amplitude from the beam port geometry, both of which may have reduced the fusion neutron production and areal density. [ABSTRACT FROM AUTHOR]

The paper explores the application of the Swiss Cheese Theory (‘linear accident causation model’) to a local conservation project as a study case: i.e. the construction of a supplementary feeding station to support a local Black Kite Milvus migrans breeding population in a nature reserve of central Italy. In this regard, the project brings light to the conditioning factors (and related ‘slices’) that may be more critical when planning a conservation project. This experience provided valuable lessons in regards to conservation: (i) the authorization process (and related bureaucracy) represented the most challenging obstacle for the promoters and slowed down the project; (ii) the authorization process was easier and faster for a research project that anyway implied providing food to Black Kites; (iii) highly motivated volunteers and expert researchers made the difference; (iv) the use of the ‘effectiveness trajectories’ in conservation projects may highlight critical points, suggesting changes in strategy and facilitating the adaptive improvement of the project. [ABSTRACT FROM AUTHOR]

We sought to evaluate the feasibility and efficacy of spinous process screws in subaxial cervical fixation. A retrospective study was conducted on 7 patients receiving posterior cervical instrumentation for subaxial fracture dislocation or atlantoaxial dislocation from 2014 to 2015. In addition, a biomechanical test was performed on 7 fresh-frozen cadaveric spine samples (from the occiput to C7) from healthy human subjects with no history of spinal trauma. And lastly, the potential trajectories of cervical spinous process screws of 100 adults were measured through axial computed tomography in order to establish the general rule for applicability of this technique. Rigid fixation and solid fusion were achieved in all 7 patients included in the study. Biomechanical test results revealed no significant difference between bilateral lateral mass screw fixation and the hybrid lateral mass and spinous process screw fixation constructs. Measurement of the potential trajectory suggested that spinous process screw fixation was a viable technique in the subaxial cervical spine in the general population. The spinous process screw fixation technique in the subaxial cervical spine is a viable and effective salvage option for patients in whom conventional posterior fixations were not sufficient and salvage, supplementary techniques were required. [ABSTRACT FROM AUTHOR]

Repeated data are increasingly collected in studies to investigate the trajectory of change in measurements over time. Determining a link between one repeated measurement with another that is considered as the biomarker for disease progression, may provide a new target for drug development. When a third variable is associated with one of the two measurements, partial correlation after eliminating the effect of that variable is able to provide reliable estimate for association as compared to the existing raw correlation for repeated data. We propose using linear regression models to compute residuals by modeling a relationship between each measurement and a third variable. The computed residuals are then used in a linear mixed model (implemented by SAS Proc Mixed) to compute partial correlation for repeated data. Alternatively, the partial correlation may be computed as the average of partial correlations at each visit. We provide two real examples to illustrate the application of the proposed partial correlation and conduct extensive numerical studies to evaluate the proposed partial correlation coefficients. [ABSTRACT FROM AUTHOR]

Eye-movement recognition is a new type of biometric recognition technology. Without considering the characteristics of the stimuli, the existing eye-movement recognition technology is based on eye-movement trajectory similarity measurements and uses more eye-movement features. Related studies on reading psychology have shown that when reading text, human eye-movements are different between individuals yet stable for a given individual. This paper proposes a type of technology for aiding biometric recognition based on reading eye-movement. By introducing a deep-learning framework, a computational model for reading eye-movement recognition (REMR) was constructed. The model takes the text, fixation, and text-based linguistic feature sequences as inputs and identifies a human subject by measuring the similarity distance between the predicted fixation sequence and the actual one (to be identified). The experimental results show that the fixation sequence similarity recognition algorithm obtained an equal error rate of 19.4% on the test set, and the model obtained an 86.5% Rank-1 recognition rate on the test set. [ABSTRACT FROM AUTHOR]

In this article, a Shack–Hartmann wavefront sensor is combined with a mechatronic positioning system to overcome the limited dynamic range of the Shack–Hartmann sensor (SHS) by repositioning and reorienting the SHS. Feedback loops to ensure a tangential orientation of the wavefront sensor in every measurement position and a measurement strategy that compensates for tip and tilt between wavefront and sensor are described and implemented. A framework that estimates the admissible measurement trajectories by relating the positioning errors caused by misalignments of the stages to the parameters of the wavefront sensor is developed. It is demonstrated that the setup is capable of directly measuring a highly divergent optical wavefront by combining wavefront data and positioning data acquired along the wavefront generated by a microscope objective with numerical aperture (NA) of 0.45. [ABSTRACT FROM AUTHOR]

The reflection of a converging cylindrical shock over a double curved wedge was investigated experimentally and numerically. The double curved wedge was specially designed to ensure that the wedge angle only changes at the corner during the cylindrical shock reflection. Seven different reflection processes existing in the planar case were reproduced in the converging case. The sudden variation of the wedge angle alters the strength of the disturbance propagating along the converging shock. Depending upon the type of the flow-induced pressure waves, which dominate the type of the wave behind the reflection over the second wedge, the propagation of the disturbance is either promoted or restrained. Comparison of the lengths of the disturbed shock front between the single wedge reflection and the double wedge reflection indicates that the history of the reflection over the first wedge would affect the reflection over the second wedge. Provided that the Mach reflection over the second wedge is fully developed, it approaches the Mach reflection of an identical shock over a single wedge with the same wedge angle as the second wedge. Relative to the planar case, the convex curved surface in the converging case promotes the disturbance propagation and increases the trajectory angle of the triple point. [ABSTRACT FROM AUTHOR]

Simultaneous localization and mapping (SLAM) refers to a process that permits a mobile robot to build up a map of the environment and, at the same time, to use it to compute its location. One of its most important components is its ability to associate the most recently perceived visual measurement to the one derived from previsited locations, a technique widely known as loop closure detection. In this article, we evolve our previous approach, dubbed as 'DOSeqSLAM' by presenting a low complexity loop closure detection pipeline wherein the traversed trajectory (map) is represented by sequence‐based locations (submaps). Each of these groups of images, referred to as place, is generated online through a point tracking repeatability check employed on the perceived visual sensory information. When querying the database, the proper candidate place is selected and, through an image‐to‐image search, the appropriate location is chosen. The method is subjected to an extensive evaluation on seven publicly available datasets, revealing a substantial improvement in computational complexity and performance over its predecessors, while performing favourably against other state‐of‐the art solutions. The system's effectiveness is owed to the reduced number of places, which, compared to the original approach, is at least one order of magnitude less. [ABSTRACT FROM AUTHOR]

Maritime traffic prediction is a crucial task for increasing the efficiency of port operations and safety, especially in congested regions. A huge amount of automatic identification system (AIS) data is constantly transmitting from vessels to receivers that contain information about vessels' movements and characteristics. These historical AIS data can be utilized in movement analyses of vessels. This paper proposes a novel point-based model for location and traffic prediction using vessels' trajectories adapted from AIS measures. The location prediction procedure is setup based on similarity analysis of historical AIS data. The model is applied to a real dataset of hundreds of vessels' trajectories in the Strait of Georgia, USA. The correlation results of 0.9976, 0.9887, and 0.9794 for the next 10, 20, and 30 minutes, respectively, imply sufficient correspondence between predicted and actual coordinates. The traffic prediction procedure considers the probability of the appearance of new vessels inside an area of interest (AoI) at different time intervals. The Sorenson similarity index (SSI) is used to measure the accuracy of the traffic prediction model. The SSIs for time intervals of 10, 20, and 30 minutes are 70%, 66%, and 59%, respectively, which show the robustness of the model to predict hot spots inside the AoI. [ABSTRACT FROM AUTHOR]

The use of surrogate markers to examine the effectiveness of a treatment has the potential to decrease study length and identify effective treatments more quickly. Most available methods to investigate the usefulness of a surrogate marker involve restrictive parametric assumptions and tend to focus on settings where the surrogate is measured at a single point in time. However, in many clinical settings, the potential surrogate marker is often measured repeatedly over time, and thus, the surrogate marker information is a trajectory of measurements. In addition, it is often difficult in practice to correctly specify the relationship between a treatment, primary outcome, and surrogate marker trajectory. In this paper, we propose a model‐free definition for the proportion of the treatment effect on the primary outcome that is explained by the treatment effect on the longitudinal surrogate markers. We propose three novel flexible methods to estimate this proportion, develop the asymptotic properties of our estimators, and investigate the robustness of the estimators under multiple settings via a simulation study. We apply our proposed procedures to an AIDS clinical trial dataset to examine a trajectory of CD4 counts as a potential surrogate. [ABSTRACT FROM AUTHOR]

Trajectory similarity measurement is a vital and widely used step in many applications, including recommendation systems. In the discipline of similarity measurement, research has mostly been focused on raw trajectories, consisting of location and time‐stamp information. Due to the explosion in the use of the internet and location‐based social networks, raw trajectories can be easily enriched with semantic information. Nevertheless, few attempts have been made to apply semantic and location information during similarity measurement. In light of this, we present a new similarity measure called the enhanced maximal travel match (EMTM) in this article. The proposed EMTM improves on conventional maximal travel match (MTM) methods by simultaneously considering the location and place category as the most basic semantic information. EMTM first generates a new place category‐location hierarchical framework (CLHF) for each trajectory. Subsequently, it identifies MTMs at each layer of hierarchy to explore the similarity between each pair of CLHFs. Finally, the proposed method calculates similarity scores based on the identified MTMs. In experiments on a Foursquare data set, EMTM outperformed the conventional MTM methods by more than 50% in terms of mean average precision. Additionally, EMTM was the most accurate technique among four state‐of‐the‐art methods. [ABSTRACT FROM AUTHOR]

Movement datasets are often complex and require sophisticated processing and analysis. A thorough understanding of the dataset is needed to choose the right methods and to interpret their results. Misunderstandings and violations of assumptions about dataset characteristics can lead to flawed analysis results and wrong conclusions. To address this challenge, we propose a novel protocol for the systematic exploration of movement datasets. The individual protocol steps address the different types of movement data problems. The exploration tools recommended at each step are specifically tailored to identifying potential problems and avoiding common pitfalls when working with global navigation satellite system (GNSS) tracking data, commonly referred to as GPS tracks. However, the general steps should be transferable to continuous movement datasets with different characteristics, such as video trajectories. Furthermore, we provide an open-source implementation of our protocol in the form of a Jupyter notebook accompanying this paper. [ABSTRACT FROM AUTHOR]

Coal will still be China's basic energy for quite a long time. With the increase of mining depth, gas content and pressure also increase. The problems of gas emission and overrun affect the safety and efficient production of coal resource to a certain extent. In this work, the field test of gas drainage borehole peeping and trajectory measurement in coal seam of Changling coal mine are carried out. These coal seams include C5b coal seam, upper adjacent C5a coal seam, C6a coal seams, C6c in lower adjacent strata, and C5b coal seam in high-level borehole. The view of gas drainage borehole peeping and trajectory measurement in the working seam, upper adjacent layer, lower adjacent layer, and high position are obtained. It is found that the hole collapses at the position of about 20 m in both adjacent strata and high-level boreholes, and there are a lot of cracks in the high-level boreholes before 12 m. The deviation distance of high-level borehole is large, and the actual vertical deviation of upper adjacent layer is small. Finally, the strategies to prevent the deviation of drilling construction are put forward. It includes four aspects: ensuring the reliability of drilling equipment, reasonably controlling the drilling length, standardizing the drilling, and reasonably selecting the drilling process parameters. [ABSTRACT FROM AUTHOR]

The current state of the research activities of the Main Astronomical Observatory of the National Academy of Sciences of Ukraine (MAO NASU) on the use of GNSS technology is presented. Today, MAO operates a permanent GNSS network consisting of five stations (two stations are temporarily inactive). All stations are included in EPN and the EPOS network, GLSV, KHAR, and UZHL stations are also integrated to the IGS network. MAO Operational Centre also provides automatic data transfer from 12 stations installed by other Ukrainian organizations included in the international networks. Data from approximately 300 Ukrainian permanent GNSS stations are stored in the MAO Local Data Centre. The MAO Local Analysis Centre uses Bernese GNSS Software for different types of data processing of GNSS observations. Rapid processing is performed on a daily basis for monitoring the stability of the permanent stations from some Ukrainian RTK networks. All available observations data from the Ukrainian stations for the period from December 7, 1997, to January 28, 2017, were processed according EPN standards during the MAO's second reprocessing campaign and regular processing. As a result, the coordinates in the IGb08 reference frame and tropospheric zenith delays for 233 permanent stations (202 of them are the Ukrainian stations), as well as the velocities for the 128 stations that have observation period more than 3 years, were estimated. The creation and development of local GNSS networks, as well as the long-term filling of databases with high-precision coordinate solutions and estimates of the displacement velocities of GNSS stations, made possible to conduct geodynamic studies at the local level. The strain ellipses and rotation were found based on estimated coordinates and velocities of the GNSS stations. In 2016–2019, Kharkiv National University of Radio Electronics, in cooperation with MAO NASU, performed a number of studies on high-precision GNSS positioning and navigation. New implementations of modern methods and algorithms for the PPP positioning were created and experimentally tested. The errors of the daily floating PPP solutions were 5...8 mm (with a probability of P ≈ 95%) for static mode and 5...8 cm (P ≈ 68%) for kinematic mode. The decimeter/centimeter error of determining the coordinates of current satellites with low Earth orbits (LEO) in the implementation of kinematic floating and fixed PPP solutions was proven. The development of a high-accuracy multiposition phase system of trajectory measurements for field tests of high dynamic aircrafts (HDA) were proposed. The estimated values of the root-mean-square error (RMSE) in determining the HDA motion variables were in the range from 0.05 to 0.40 m for coordinates and from 0.5 to 1.6 cm/s for the velocity vector components. [ABSTRACT FROM AUTHOR]

In a joint analysis of longitudinal quality of life (QoL) scores and relapse‐free survival (RFS) times from a clinical trial on early breast cancer conducted by the Canadian Cancer Trials Group, we observed a complicated trajectory of QoL scores and existence of long‐term survivors. Motivated by this observation, we proposed in this paper a flexible joint model for the longitudinal measurements and survival times. A partly linear mixed effect model is used to capture the complicated but smooth trajectory of longitudinal measurements and approximated by B‐splines and a semiparametric mixture cure model with the B‐spline baseline hazard to model survival times with a cure fraction. These two models are linked by shared random effects to explore the dependence between longitudinal measurements and survival times. A semiparametric inference procedure with an EM algorithm is proposed to estimate the parameters in the joint model. The performance of proposed procedures are evaluated by simulation studies and through the application to the analysis of data from the clinical trial which motivated this research. [ABSTRACT FROM AUTHOR]

Many different formalisms exist for computing the phase of a matter-wave interferometer. However, it can be challenging to develop physical intuition about what a particular interferometer is actually measuring or about whether a given classical measurement provides equivalent information. Here, we investigate the physical content of the interferometer phase through a series of thought experiments. In low-order potentials, a matter-wave interferometer with a single internal state provides the same information as a sum of position measurements of a classical test object. In high-order potentials, the interferometer phase becomes decoupled from the motion of the interferometer arms, and the phase contains information that cannot be obtained by any set of position measurements on the interferometer trajectory. This phase shift in a high-order potential fundamentally distinguishes matter-wave interferometers from classical measuring devices. [ABSTRACT FROM AUTHOR]

Rockfall propagation models are routinely used for the quantitative assessment of rockfall hazard. Their capacities and limitations remain difficult to assess due to the limited amount of exhaustive experimental data at the slope scale. This article presents experiments of block propagation performed in a quarry located in Authume (France). This study site was chosen for its complexity, related with the presence of topographical discontinuities and of configurations promoting block rolling. A total of more than one hundred blocks were released on two propagation paths. The propagation of the blocks was assessed by measuring the block stopping points as well as their kinematics at specific locations of the paths, called evaluation screens. Significant variability of the stopping points and of the block kinematics at the evaluation screens was observed, and preferential transit and deposit zones were highlighted. The analysis of the results showed predominant effect of topography, in particular that related to topographical discontinuities. Significant influence of local and small scale parameters (e.g., block orientation, local topography) was also highlighted. These conclusions are of particular interest for researchers or practitioners who would like to assess the relevance of propagation modeling tools considering this complex study site. In this configuration, the quality of block propagation simulations should notably rely on the accuracy of digital terrain models, and on the integration of local conditions effects using physically based approaches. [ABSTRACT FROM AUTHOR]

The increasing volume of ship traffic has resulted in new challenges for the supervision of maritime safety administration. The conventional manual monitoring approach for maritime traffic is inefficient and lacks specifics, particularly for supervising ships with abnormal trajectories. To address this issue, this study proposes utilizing the minimum description length criterion to extract features from ship trajectory data provided by the automatic identification system (AIS). This approach simplifies the compression of ship trajectories. Additionally, the dynamic time warping trajectory similarity measurement algorithm is employed to optimize the density-based spatial clustering of applications with noise algorithm. This optimization enables the clustering of ship trajectories and the acquisition of normalized ship motion trajectories. Furthermore, a ship trajectory prediction method based on a transformer model is proposed, and the normalized motion trajectory is used as the training set for model training. The trained ship trajectory prediction model is subsequently utilized to predict the target ship trajectory. The AIS ship trajectory data in the vicinity of Yantai Port were used for experimental verification. The results demonstrate the effectiveness of the proposed approach in identifying abnormal ship trajectories. • A minimum description length criterion is proposed to simplifies the compression of AIS trajectory. • The dynamic time warping trajectory similarity measurement method is used to optimize the density-based spatial clustering. • The trained ship trajectory prediction method based on transformer model is utilized to predict the target ship trajectory. [ABSTRACT FROM AUTHOR]

• A 3D trajectory measurement method for pipelines based on inertial navigation. • A high-reliability measurement algorithm based on multiple sensors. • An algorithm based on the fusion of time forward and time reverse Kalman filter. • A time-saving method that only needs one trip from inlet to outlet of pipeline. • A high-precision algorithm that can correct sensor errors. The three-dimensional (3D) trajectory measurement of underground pipelines is the basis for establishing an underground pipeline network system. Mastering the trajectory of underground pipelines can reduce damage to old pipelines during construction. Traditional pipeline measurement methods have limitations in terms of depth and environment, leading to the inability to obtain accurate information on the pipeline trajectory. In this study, a forward and reverse Kalman filtering fusion measurement algorithm based on MEMS-IMU, MEMS magnetometer, and the odometer was proposed. First, a 16-dimensional Kalman filtering model was established according to the motion mode and working environment of the pipeline measurement instruments; Secondly, based on the 16-dimensional Kalman filtering model, the data of multi-sensors were fused according to the forward and reverse time order respectively. Thus, two kinds of 3D trajectories of the pipeline were obtained. One is the time order, the other one is the reverse time order. Thirdly, in order to get the optimal measurement results of the 3D trajectory of the pipeline, the forward and reverse measurement results were fused according to the covariance matrix of the forward and reverse Kalman filter. Finally, a ground simulation experiment and an underground pipelines experiment with a MEMS sensor (PA-IMU488B) were performed to verify the feasibility of the method. In the ground simulation experiment, the maximum relative error in the plane is 0.14%, and the maximum relative error in the vertical is 0.28%. In the experiment of underground drainage pipelines, the maximum relative error in the plane is 0.22%, and the maximum relative error in the vertical is 0.12%. This method proposed by this study uses one set of data twice which can make the measurement results more accurate. Above all, the sensors used in this method are all cheap and low precision. Moreover, the measuring equipment only needs to travel through the pipe from the entrance to the exit and doesn't need to go back from the exit to the entrance. Therefore, the method proposed by this study is a high-precision, low-cost, and low-time-consuming method for 3D trajectory measurement of underground pipelines. [ABSTRACT FROM AUTHOR]

Cyclist trajectory prediction is an essential task in autonomous driving and surveillance systems. This task is challenging due to that the bicycles go much faster than the pedestrians and a minor prediction error could lead to a severe deviation in the actual path. Existing cyclist trajectory prediction models usually employ the social pooling mechanism to depict the mutual interactions between targets. They ignore that the pooling operation is leaky in information. Moreover, they prefer to use the recurrent architecture to capture the time‐varying features, which is not efficient in computation and parameter learning. To address these issues, a spatial‐temporal multi‐graph module which employs the topology of graphs to represent social interactions and design multi‐kernel functions to depict the social attributes from various aspects is proposed. Instead of the recurrent architecture, a temporal convolution to forecast the future paths is introduced. Experimental results on real‐world datasets demonstrate its superior performance against state‐of‐the‐art baselines. It reduces 9% prediction error when compared to recurrent neural network based models and is more effective in crowded scenarios. [ABSTRACT FROM AUTHOR]

Solenoids are frequently used for focusing low-energy beams. In this paper, we show how they can serve as multipurpose diagnostics tools to measure various beam parameters, including energy, emittance, the second moments of the transverse distribution, and the beam position and angle with respect to the solenoid's axis. The energy measurement is based on rotation of the plane of the transverse motion, as opposed to generating dispersion with a dipole. Measurement of the beam trajectory with respect to the solenoid axis is done by analyzing the beam orbit downstream of the solenoid while varying its current. The second moments are calculated by analyzing the beam image on a profile monitor while accounting for the beam rotation caused by the solenoid. We describe in detail the corresponding procedures and the experimental results of these measurements. [ABSTRACT FROM AUTHOR]

In this paper we investigate the energy integral which is obtained in the problem of the motion of a material point in a central field within thе frame of the general theory of relativity. Applied are the method of the small parameter in a combination with the balance method. Derived is a compact formula, describing the trajectory of the motion. This formula gives a correct quantitative description of the basic relativistic effects. We prove the shortening of the major axis of the orbit in comparison with the case where we do not take into account relativistic effects. This result can be useful for analysing the structure of planet systems around massive stars. [ABSTRACT FROM AUTHOR]

In addition to and parallel to the SERVUS project, the requirements for a new, agile, urban cargo bicycle with electric drive are identified through a targeted, scientific application potential analysis in the project "E-Cargo Bike - Accompanying Research" described here. These findings are then implemented in the SERVUS project in an agile development and production process. Several prototypes are built in the process. The new e-cargo bicycles should be able to be used both privately and commercially. They will be presented to users for the first time at events (IAA 2021) and rated by them. In addition, the longer-term allocation of the bikes to selected users enables a cross-comparison with existing e-cargo bicycle models. Finally, the substitution potential of journeys in motorized individual transport is estimated and projected using the example of Munich. A key for gathering further information on the abilities of specific electric cargo bike types is tracking experiments with various sensor setups of which the first attempts are presented in this research. Additionally, and by enabling a certain spatial accuracy of gathered GNSS data, we are able to match selected maneuvers of these vehicle types to selected types of the Munich transportation infrastructure. Besides trajectory shapes of maneuvers, we are able to incorporate travel time and delay variations depending on investigation areas and times of the day at selected urban locations for every inspected maneuver (at for examples differing intersection geometries with and without traffic light signals). Another aspect is the presence of bicycle infrastructure and its relation to the option of using mixed traffic modes. [ABSTRACT FROM AUTHOR]

SiC metal–oxide–semiconductor field-effect transistor (MOSFET) has a fast switching speed and high slew rate. However, its ultrashort switching time approximates the rise time and propagation delay of the measurement instruments, which results in an inaccurate assessment of the switching loss and challenges the thermal design of the power converter. In this article, aiming to reveal the principles of accurate measurement for the switching behavior of SiC MOSFET, insightful models are proposed for baseline probes and transient trajectories to characterize the measurement error of the switching losses. By using the Gaussian function, the mathematical models for the rise time, bandwidth, and propagation delay of the measurement instruments are achieved, which is also confirmed by the surveyed specifications of commercial probes. Concerning the accurate measurement, the turn-on and turn-off losses of the SiC MOSFET influenced by the rise time and propagation delay of probes are comprehensively modeled and characterized. With respect to different current probes, voltage probes, and gate driver resistances, extensive experiments are demonstrated to confirm the validity of the proposed models. The experimental findings are in line with the conducted predictions of the proposed models. It is found that, due to the very fast switching transients of the SiC MOSFET, the limited bandwidth and inevitable propagation delay of measurement instrument may result in a prominent error of the switching loss and impede the widespread implementation of the SiC MOSFET. [ABSTRACT FROM AUTHOR]