The Azure Kinect is the successor of Kinect v1 and Kinect v2. In this paper we perform brief data analysis and comparison of all Kinect versions with focus on precision (repeatability) and various ...aspects of noise of these three sensors. Then we thoroughly evaluate the new Azure Kinect; namely its warm-up time, precision (and sources of its variability), accuracy (thoroughly, using a robotic arm), reflectivity (using 18 different materials), and the multipath and flying pixel phenomenon. Furthermore, we validate its performance in both indoor and outdoor environments, including direct and indirect sun conditions. We conclude with a discussion on its improvements in the context of the evolution of the Kinect sensor. It was shown that it is crucial to choose well designed experiments to measure accuracy, since the RGB and depth camera are not aligned. Our measurements confirm the officially stated values, namely standard deviation ≤17 mm, and distance error <11 mm in up to 3.5 meters distance from the sensor in all four supported modes. The device, however, has to be warmed up for at least 40-50 min to give stable results. Due to the time-of-flight technology, the Azure Kinect cannot be reliably used in direct sunlight. Therefore, it is convenient mostly for indoor applications.
Preventive maintenance is increasingly becoming an essential strategy in the bridge industry owing to its proactive advantage of maintaining the structural sustainability during its entire service ...life. Several in-use bridges lack an appropriate regular maintenance solution, leading to extra cost during the operation stage. This paper proposes a new generation of the bridge maintenance system by using a digital twin model concept for more reliable decision-making. A detailed solution is proposed in this work to enhance the bridge maintenance process using a parallel solution: a maintenance information management system based on a 3D information model in conjunction with a digital inspection system using image processing. Three-dimensional digital models are required to utilise information from the entire lifecycle of a project, including design and construction, operation, and maintenance, by continuously exchanging and updating data from each stakeholder. For the maintenance of prestressed concrete bridges, the twin models are defined and their uses are presented.
•Geometric features of two kinds of corroded HPS are compared by means of 3D scanning technology.•Comparisons of corrosion appearance, fracture characteristics, and mechanical behaviors are ...made.•Effects of different corroded cross sections and their spacing on the mechanical properties are evaluated.
An experimental study was conducted to compare the deterioration of mechanical properties of HPS specimens subjected to electrochemical corrosion and neutral salt spray accelerated corrosion. Twenty seven 460D steel specimens were designed and subjected to these two kinds of corrosion. The geometric features of the specimens were evaluated by using 3D scanning technology. Mechanical properties and corrosion damage were discussed after tensile tests. FEM was developed to investigate the effects of different corroded cross sections and their spacing on the degradation of mechanical properties. Experimental results show that specimens subjected to the electrochemical accelerated corrosion have more obvious non-uniformity. Shape of big pits in terms of the electrochemical accelerated corrosion can be regarded as a flat semi-ellipsoid, and part of a full semi-ellipsoid for salt spray accelerated corrosion, and cone for the small pits. Corrosion method has an effect on the ductility, strength, and failure behaviors. Compared with thickness loss, width loss has a greater impact on structural strength and stiffness.
Due to methodological advances in the archaeological sciences, an increasing number of archaeological specimens undergo destructive sampling. However, the preservation of cultural heritage is a ...primary concern. This leads to a dilemma between accessing sample material and obtaining sufficient information for a meaningful analytical outcome. Ideally, sampling a specimen would preserve the object for further macro, micro, and molecular analyses. For palaeoproteomics, a number of minimally invasive sampling approaches have been proposed, representing different benefits and limitations. There have been studies comparing a selection of these protocols, however, these have focused on specimens from a homogenous preservation environment using Zooarchaeology by Mass Spectrometry (ZooMS). Here we expand on earlier work by extending the comparison to specimens from two highly different preservation environments through both ZooMS and liquid-chromatography tandem mass spectrometry (LC-MS/MS). We compare five sampling approaches and seven extraction protocols in total, on 10 Bos sp. humeri from the Early Neolithic site of La Draga, Spain, utilising MALDI-ToF MS and LC-MS/MS to generate proteomic output, while assessing protocol invasiveness using microscopy and 3D imaging. Five humeri originate from Sector A, which is mostly related to dry, terrestrial preservation conditions, while the other five humeri stem from Sector B, which is characterised by its phreatic/aquatic preservation conditions. We show that there is a significant difference in protein recovery and taxonomic specificity between the sampling techniques applied, as well as between burial conditions. Additionally, various surface modifications were observed depending on the specific sampling technique applied. It is therefore essential to assess protein preservation for each sedimentological context within an archaeological site before performing extensive sampling, as protein preservation can be highly inter- and intra-site-specific.
•Preservation influences the proteomic outcome of different sampling methods.•Minimally invasive sampling extracts protein adequately if preservation is sufficient.•The HCl protocol produces the best proteomic results regardless of preservation state.•Minimally invasive sampling methods complicate use-wear analysis to various degrees.
•A two-stage CFD simulation method is proposed for droplets deposition in air-assisted spraying.•The influence of leaves deformation on droplet movement and deposition is considered.•3D point cloud ...scanning technique is used to assist in establishing plant geometric models.•The two-stage simulation method is a tool for optimizing air-assisted spraying parameters.
In air-assisted spraying, assisted airflow leads to flexible leaf deformation and affects distribution of droplet deposition in canopies. However, analyzing droplet deposition behavior during dynamic changes in canopies is challenging. To address this issue, a method was developed, called two-stage simulation, with one stage involving a fluid–structure interaction of assisted airflow with plant leaves and the other stage involving a discrete particle tracking simulation of droplet deposition within deformed plant canopies under the air–liquid interaction of assisted airflow and droplets. First, a representative three-dimensional (3D) plant model is developed through 3D point cloud scanning, agricultural planting parameters in the field, and plant growth characteristics. Subsequently, the deformed plant model is derived from the results of the fluid–structure interaction simulation. Finally, discrete particle tracking simulations of droplet deposition in canopies of deformed plants under air–liquid interaction are conducted. The accuracy of the simulation is verified by examining airflow distribution in the canopy and the deposition of droplet particles. The airflow verification results indicate accuracy, with a coefficient of determination of 0.8684 and a root mean squared error of 0.1463 for the linear fitted equation between the simulated and measured values. The normalized mean absolute error between the simulated and measured values is 17.2 %, indicating a favorable match between the two. The variance analysis results indicated that there is no significant difference (P > 0.05) between the simulated and measured values of droplet deposition density in the upper, middle, and lower layers. Utilizing the validated computational fluid dynamics (CFD) model, we analyze the deposition characteristics of droplets under varying airflow velocities and spray flow rates. The results highlight a direct correlation between the liquid distribution and generated airflow pattern with increased droplet deposition and drift risk observed under strong airflow and high spray flow rates. This study offers a novel approach to uncovering droplet deposition patterns through CFD simulation.
Over the past few years, we have been developing techniques for high-speed 3D shape measurement using digital fringe projection and phase-shifting techniques: various algorithms have been developed ...to improve the phase computation speed, parallel programming has been employed to further increase the processing speed, and advanced hardware technologies have been adopted to boost the speed of coordinate calculations and 3D geometry rendering. We have successfully achieved simultaneous 3D absolute shape acquisition, reconstruction, and display at a speed of 30
frames/s with 300
K points per frame. This paper presents the principles of the real-time 3D shape measurement techniques that we developed, summarizes the most recent progresses that have been made in this field, and discusses the challenges for advancing this technology further.
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The increasing prevalence of wound infections caused by antibiotic resistant bacteria is an urgent challenge facing modern medicine. To address this issue the expedient use of ...antimicrobial metals such as zinc, copper and silver were incorporated into an FDA-approved polymer (polycaprolactone – PCL) to produce filaments for 3D printing. These metals have broad-spectrum antimicrobial properties, and moreover, copper and zinc can enhance the wound healing process. 3D scanning was used to construct 3D models of a nose and ear to provide the opportunity to customize shape and size of a wound dressing to an individual patient. Hot melt extrusion was used to extrude pellets obtained by vacuum-drying of solutions of PCL and the different metals in order to manufacture metal-homogeneously-loaded filaments. Wound dressings with different shapes were produced with the filaments containing different concentrations of metals. Release of the metals from the dressings was determined by inductively coupled plasma atomic emission spectroscopy. All the different metal dressings show fast release (up to 24h) followed by slow release (up to 72h). The antibacterial efficacy of the wound dressings was tested using a thermal activity monitor system, revealing that silver and copper wound dressings had the most potent bactericidal properties. This study shows that 3D scanning and 3D printing, which are becoming simpler and more affordable, have the potential to offer solutions to produce personalised wound dressings.
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