Surface determination algorithm for accurate XCT bidirectional length measurements

Surface determination plays an important role in XCT bi-directional length measurement, however, its effect on the measurement results is often overlooked or hidden by other error sources. Most of the published research in dimensional field used the Canny algorithm or the surface determination module in VGStudio. Both of them require input from the operator that can also affect the accuracy of the measurements. Alternatively, the marker-controlled watershed (MCW) algorithm has been proven to avoid the latter issue, however, there is no systematic study that evaluated the surface determination algorithm's effect on the accuracy of bi-directional length measurements. In this study a two-sphere reference sample was measured using an XCT scanner and, with the aid of simulations, the effect of the three surface determination methods on bi-directional length measurements was comprehensively studied. The results show that in the presence of ‘streak’ artefacts, a beam hardening error, if the operator does not set parameters appropriately, Canny and VGStudio implementations lead to either loss of surface or large errors, whereas MCW avoids this issue demonstrating its process automation ability. Nevertheless, with voxel calibration, beam hardening correction and data manipulation, MCW and Canny algorithms enable accurate sphere radius measurements (bi-directional measurements), comparable to the accuracy of an industrial tactile coordinate measuring machine.Engineering and Physical Sciences Research Council (EPSRC): EP/K503241/

Food resources for Spoon-billed Sandpipers (<i>Calidris pygmaea</i>) in the mudflats of Leizhou Bay, southern China

Leizhou Bay in Guangdong Province is the most important wintering site in China for the critically endangered Spoon-billed Sandpipers (Calidris pygmaea). As food is usually a strong predictor of presence, in the winters of 2019-2022 we studied arthropod food resources and diet on the intertidal mudflats at the Tujiao and Hebei mudflats in Leizhou Bay. In December 2020, using a sampling device that encloses mobile epibenthic prey before the human sampler would disturb them in shallow pools, we visited 34 stations in their core foraging area at Tujiao. A total of 15 mobile benthic species were identified, including 13 arthropod and 2 fish species, with a total density of 106 animals/m2 (range= 0.2-48 animals/m2), with the lengths of the animals ranging from 1-19 mm. Two amphipod and one cumacean species contributed 85%. On the basis of photographs of foraging during low tide in 2019-2022, the visibly ingested prey items appeared to mainly consist of small shrimp, but also included crabs and fish. At 27 mm (compared with the 22 mm long bill of Spoon-billed Sandpipers) the average visibly ingested prey showed a strong size bias. Among the measured environmental covarying factors (sediment pH, salinity, TOC content, median particle size and distance from the seawall etc.) potentiually affecting the mobile epibenthic prey in shallow pools, only distance from the seawall was significantly and negatively correlated. Densities were higher within 1 km of the seawall (126 animals/m2) than further offshore (69 animals/m2). This may relate to the mangrove forests growing in abundance near the seawall providing released minerals, nutrients, bacterial production and diatoms for the benthic community in the adjacent mudflats. However, the potential negative impact of artificial mangrove expansion in Leizhou mudflats need to be carefully monitored and assessed to balance both mangrove and Spoon-billed Sandpipers conservation

Global acetylome profiling indicates EPA impedes but OA promotes prostate cancer motility through altered acetylation of PFN1 and FLNA.

Prostate cancer (PCa) is one of the leading causes of cancer morbidity and mortality in men. Metastasis is the main cause of PCa-associated death. Recent evidence indicated a significant reduction in PCa mortality associated with higher ω-3 polyunsaturated fatty acids (PUFAs) consumption. However, the underlying mechanisms remained elusive. In this study, we applied global acetylome profiling to study the effect of fatty acids treatment. Results indicated that oleic acid (OA, monounsaturated fatty acid, MUFA, 100 µM) elevates while EPA (eicosapentaenoic acid, 100 µM) reduces the acetyl-CoA level, which alters the global acetylome. After treatment, two crucial cell motility regulators, PFN1 and FLNA, were found with altered acetylation levels. OA increased the acetylation of PFN1 and FLNA, whereas EPA decreased PFN1 acetylation level. Furthermore, OA promotes while EPA inhibits PCa migration and invasion. Immunofluorescence assay indicated that EPA impedes the formation of lamellipodia or filopodia through reduced localization of PFN1 and FLNA to the leading edge of cells. Therefore, perturbed acetylome may be one critical step in fatty acid-affected cancer cell motility. This study provides some new insights into the response of ω-3 PUFAs treatment and a better understanding of cancer cell migration and invasion modulation

Block copolymer of trans-polyisoprene and urethane segment: Shape memory effects

ABSTRACT: Shape memory behaviors of trans-polyisoprene (TPI) segmented urethane copolymers were studied. Film specimens for cyclic loading tests were prepared from the polymer solution by casting, and tested at the loading temperature of 65°C. Results show that the recovery rates of the films depend on their TPI segment contents, while the fixity rate was measured to be close to 100% for each sample. The film containing 70% TPI segments was found to show a recovery rate of 85%. Two separated phases were clearly observed in the morphology of the films. The urethane segments were organized into spherical domains acting as physical cross-links during the shape memory process. The continuous phase formed by the crystalline TPI segments serves as the reversible phase responsible for fixation of the temporary shape. The tensile and dynamic thermal properties of those films were also studied

An automated surface determination approach for computed tomography

Surface determination is a critical image processing step in X-ray Computed Tomography that uses algorithms based on local thresholding methods, such as Canny and Steinbess, to detect the surface of metallic components with intricate designs and complex topographies. In most of the cases, these algorithms require trial-and-error tests to optimise the threshold operation, leading to unreliable and, at times, erroneous inspection results. This paper demonstrates the ability of marker-controlled watershed algorithm to automate the surface determination process and to maintain its robustness in the presence of beam hardening and complex topographies, outperforming the current commercial and non-commercial software implementations

The Design of Robotic Arm Adaptive Fuzzy Controller Based on Oscillator and Differentiator

State variables are acquired when tracking the trace of the robotic arm with adaptive fuzzy controller. Since some variables are difficult to or cannot be measured directly, we introduced the second order oscillator and the second order differentiator that converges in finite time to obtain the value of each state variable. In this paper, a model based on the dynamics analysis of robotic arm was build to design the second order oscillator and the second order differentiator that converges in finite time to obtain the value of each state variable. The designed adaptive fuzzy controller for robotic arm achieved high accuracy in trace tracking. Simulation results of two-link robotic arm show the adaptive fuzzy controller for robotic arm based on differentiators is adaptable, flexible. This controller is simple to design, easy to implement, and has a good value for the application of robotic arm system

The Design of Robotic Arm Adaptive Fuzzy Controller Based on Oscillator and Differentiator

State variables are acquired when tracking the trace of the robotic arm with adaptive fuzzy controller. Since some variables are difficult to or cannot be measured directly, we introduced the second order oscillator and the second order differentiator that converges in finite time to obtain the value of each state variable. In this paper, a model based on the dynamics analysis of robotic arm was build to design the second order oscillator and the second order differentiator that converges in finite time to obtain the value of each state variable. The designed adaptive fuzzy controller for robotic arm achieved high accuracy in trace tracking. Simulation results of two-link robotic arm show the adaptive fuzzy controller for robotic arm based on differentiators is adaptable, flexible. This controller is simple to design, easy to implement, and has a good value for the application of robotic arm system.</p

An AR Geo-Registration Algorithm for UAV TIR Video Streams Based on Dual-Antenna RTK-GPS

In emergency response and disaster rescue, unmanned aerial vehicles (UAVs) onboard thermal infrared (TIR) sensors are an essential means of acquiring ground information in the nighttime working environment. To enable field personnel to make better decisions based on TIR video streams returned from a UAV, the geographic information enhancement of TIR video streams is required. At present, it is difficult for low-cost UAVs to carry high-precision attitude sensors and thus obtain high-precision camera attitude information to meet the enhanced processing requirements of UAV TIR video streams. To this end, this paper proposes an improved Kalman filter algorithm to improve the geographic registration (geo-registration) accuracy by fusing the positioning and heading data from the dual-antenna real-time kinematic global positioning system (RTK-GPS) with onboard internal measurement unit (IMU) data. This method can yield high-precision position and attitude data in real time based on low-cost UAV hardware, based on which high-precision geo-registration results can be obtained. The computational complexity can be reduced compared with video stream feature tracking algorithms. Furthermore, the problem of unstable matching due to the low resolution and texture level of TIR video streams can be avoided. The experimental results prove that the proposed method can reduce the registration error by 66.15%, and significantly improve the geo-registration accuracy of UAV TIR video streams. Thus, it can strongly support the popularization and practicality of the application of augmented reality (AR) technology to low-cost UAV platforms

An AR Geo-Registration Algorithm for UAV TIR Video Streams Based on Dual-Antenna RTK-GPS

In emergency response and disaster rescue, unmanned aerial vehicles (UAVs) onboard thermal infrared (TIR) sensors are an essential means of acquiring ground information in the nighttime working environment. To enable field personnel to make better decisions based on TIR video streams returned from a UAV, the geographic information enhancement of TIR video streams is required. At present, it is difficult for low-cost UAVs to carry high-precision attitude sensors and thus obtain high-precision camera attitude information to meet the enhanced processing requirements of UAV TIR video streams. To this end, this paper proposes an improved Kalman filter algorithm to improve the geographic registration (geo-registration) accuracy by fusing the positioning and heading data from the dual-antenna real-time kinematic global positioning system (RTK-GPS) with onboard internal measurement unit (IMU) data. This method can yield high-precision position and attitude data in real time based on low-cost UAV hardware, based on which high-precision geo-registration results can be obtained. The computational complexity can be reduced compared with video stream feature tracking algorithms. Furthermore, the problem of unstable matching due to the low resolution and texture level of TIR video streams can be avoided. The experimental results prove that the proposed method can reduce the registration error by 66.15%, and significantly improve the geo-registration accuracy of UAV TIR video streams. Thus, it can strongly support the popularization and practicality of the application of augmented reality (AR) technology to low-cost UAV platforms