The Ancient Greek Potter’s Wheel: Experimental Archaeology and Web Applications for Velocity Analysis

The potter’s wheel is central to the understanding of ancient technology, knowledge transfer, and social complexity. With scant evidence of potter’s wheels from antiquity, experimental projects with replica potter’s wheels can help researchers address larger questions on ceramic production. One such set of experiments, performed using the Ancient Greek wheel replica in Tucson modelled on Athenian and Corinthian iconographic evidence, provided useful insight into the qualitative experience of ancient potters. In past experiments, the quantitative analysis of the throwing sessions included data on wheel velocity which had been collected collected over large intervals, comprising entire stages of the throwing process. While this method provides an overview of rotational speed, a continuous velocity graph provides a clearer picture collected data on wheel velocity. To address this, we developed a web application (WheelVis; brandonneth.github.io/wheelvis) to aid in the velocity analysis of experimental potter’s wheels. Users provide a recording of the throwing session and while advancing through the recording, they mark points where the wheel has completed rotations. Using the time intervals between these points, the tool reconstructs a graph of the velocity of the wheel throughout the throwing session. This innovative application provides fast, fine-grained velocity information, and helps archaeologists answer questions about the physical properties of their experimental replicas or wheels used in traditional workshops. Future development of the application will include contextual partitions to allow users to split the throw into different stages, enabling further analysis into the throwing process. Moreover, intelligent error detection would notify users when a mark is likely to be made in error and allow them to correct their mistake.

Determination of dynamical ages of open clusters through the A+ parameter – I

The sedimentation level of blue straggler stars (BSS) has been shown to be a great tool to investigate the dynamical states of globular clusters (GCs). The area enclosed between the cumulative radial distributions of BSS and a reference population up to the half-mass radius of the clusters, $A^+_{\mathrm{rh}}$, is known to be a measure of the sedimentation of BSS in GCs. In this work, we calculate $A^+_{\mathrm{rh}}$ for 11 open clusters (OCs) using a combined list of main-sequence turn-off stars, sub-giant branch stars, and red-giant branch stars as reference population. The BSS, the reference populations, and the cluster members are identified using the proper motions and parallaxes from the Gaia DR2 data. In a subset of clusters, the BSS are confirmed cluster members on the basis of radial velocity information available in the literature. Using the Pearson and Spearman rank correlation coefficients, we find weak correlations between the estimated values of $A^+_{\mathrm{rh}}$ and other markers of dynamical ages of the clusters, i.e. the number of central relaxations a cluster has experienced since its formation, and the structural parameters of the clusters. Based on statistical tests, we find that these correlations are similar to the corresponding correlations among the less evolved GCs, albeit within large errors.

Confirming Reservoir Geometry and Exploration Opportunity through 5D Interpolation PSDM in The Sub-ophiolite Zone, Banggai Sula Basin, Central Sulawesi

In 2020, Pertamina EP made another gas discovery in Banggai-Sula Basin. However, the prediction missed the top of formation by several hundred meters and therefore increased the uncertainty in the actual amount of the discovered gas resources. The previous geological model was based on 3D Pre-Stack Depth Migrated seismic data from 2018. With only one well as data control, plus complex structure and the proximity to the Batui thrust, the velocity has not been modeled correctly. To reduce the uncertainty, a reprocessed seismic data is required to help building an updated geological model. The newly drilled well, WOL-002, provides new velocity information for PSDM reprocessing. It is however located below an ophiolite layer when signals are very weak. To improve the signal to noise ratio, a powerful yet time-consuming 5D Interpolation is employed. This step significantly improves image quality especially below the thrust. Since this project is tightly time constrained, a careful parameterization has been done for improving processing efficiency. As a result, the imaging can be finished ahead of schedule. Reflector’s depth is confirmed using not only velocity data from well W-20 but also from the neighboring field. New interpretation based on the 2020 reprocessing suggests a larger structure in the subsurface compared to the previous model. This newly processed 3D seismic is also used for identifying new prospect closer toward the thrust zones.

State estimation of tire-road friction and suspension system coupling dynamic in braking process and change detection of road adhesive ability

During vehicle braking, when vehicles move on the road with unknown road roughness elevation and unknown tire/road friction coefficient, fewer sensors shall be used for vehicle braking closed-loop control and braking distance prediction to obtain the dynamic states of the vehicle suspension and tire systems. In this paper, a vehicle dynamic model is established in Carsim software. Modify lump LuGre friction model and road roughness elevation model of four tires are proposed based on matlab. When vehicles brake on the road with time-varying split-μ, a braking control algorithm established in this paper. The road roughness elevation and the braking force of each tire are supplied to the vehicle dynamic model in Carsim. A state estimate algorithm of suspension system is proposed. The scheme for minimum sensor of this estimator is determined. A state estimate algorithm of the tire/road friction using only tire angular velocity information is proposed. When vehicles brake on the road with different levels of roughness, the influence of the number of installation groups of the sensors, the tire vertical stiffness deviations, and the measurement noise on the estimation error of the estimator is analyzed. When the vehicle is driving on the road with unknown adhesive ability, based on the estimator of tire/road friction using only tire angular velocity information, the tire/road friction internal state, the changes of road adhesive ability, and the vehicle velocity are estimated well.

A novel streak velocimetry technique based on 2D fits of decaying phosphor particle images

A new 2D velocimetry technique based on streaks formed by individual phosphor particles, which are moving during their luminescence decay following pulsed excitation is proposed in this study. Tin-doped phosphor particles (Sr,Mg)3(PO4)2:Sn2+ are dispersed into flows and excited by a pulsed UV light sheet. During the phosphor decay time (~27 µs), the emission streaks due to particle motion are recorded. A 2D fitting is then applied on each particle streak against the analytical expression of intensity distribution, to obtain the velocity information for each particle. Unlike Particle Tracking Velocimetry (PTV) this technique does not rely on any particle image searching procedure.

Consensus in networks of uncertain robot manipulators without using neighbors’ velocity information

In this paper, new distributed adaptive methods are proposed for solving both leaderless and leader–follower consensus problems in networks of uncertain robot manipulators, by estimating only the gravitational torque forces. Comparing with the existing adaptive methods, which require the estimation of the whole dynamics, presented methods reduce the excitation levels required for efficient parameter search, the convergence time, and the complexity of the regressor. Additionally, proposed schemes eliminate the need for velocity information exchange between the agents. Global asymptotic synchronization is shown by introducing new Lyapunov functions. Simulation results are provided for a network of 10 4-DOF robot manipulators.

Reliable Communications for Vehicular Networks

Vehicular communications, referring to information exchange among vehicles, and infrastructures. It has attracted a lot of attentions recently due to its great potential to support intelligent transportation, various safety applications, and on-road infotainment. The aim of technologies such as Vehicle-to-Vehicl (V2V) and Vehicle to-Every-thibg (V2X) Vehicle-to very-thing is to include models of connectivity that can be used in various application contexts by vehicles. However, the routing reliability of these ever-changing networks needs to be paid special attention. The link reliability is defined as the probability that a direct communication link between two vehicles will stay continuously available over a specified period. Furthermore, the link reliability value is accurately calculated using the location, direction and velocity information of vehicles along the road.

Visuomotor control of intermittent circular tracking movements with visually guided orbits in 3D VR environment

The analysis of visually guided tracking movements is important to the understanding of imitation exercises and movements carried out using the human visuomotor control system. In this study, we analyzed the characteristics of visuomotor control in the intermittent performance of circular tracking movements by applying a system that can differentiate between the conditions of invisible and visible orbits and visible and invisible target phases implemented in a 3D VR space. By applying visuomotor control based on velocity control, our study participants were able to track objects with visible orbits with a precision of approximately 1.25 times greater than they could track objects with invisible orbits. We confirmed that position information is an important parameter related to intermittent motion at low speeds (below 0.5 Hz) and that tracked target velocity information could be obtained more precisely than position information at speeds above 0.5 Hz. Our results revealed that the feedforward (FF) control corresponding to velocity was delayed under the visible-orbit condition at speeds over 0.5 Hz, suggesting that, in carrying out imitation exercises and movements, the use of visually presented 3D guides can interfere with exercise learning and, therefore, that the effects of their use should be carefully considered.

Deep velocimetry: Extracting full velocity distributions from projected images of flowing media

Particle image velocimetry (PIV) is a powerful image correlation method for measuring bulk velocity fields of flowing media. It typically uses optical images, representing quasi-two-dimensional experimental slices, to measure a single velocity value at each in-plane position. However, projection-based imaging methods, such as x-ray radiography or shadowgraph imaging, encode additional out-of-plane information that regular PIV is unable to capture. Here, we introduce a new image analysis method, named deep velocimetry, that goes beyond established PIV methods and is capable of extracting full velocity distributions from projected images. The method involves solving a deconvolution inverse problem to recover the distribution at each in-plane position, and is validated using artificial data as well as controlled laboratory x-ray experiments. The additional velocity information delivered by deep velocimetry could provide new insight into a range of fluid and granular flows where out-of-plane variation is significant. Graphic abstract