Development of Structured Light 3D-Scanner with High Spatial Resolution and its Applications for Additive Manufacturing Quality Assurance

Digital three-dimensional (3D) scanning is a cutting-edge metrology method that can digitally reconstruct surface topography with high precision and accuracy. Such metrology can help traditional manufacturing processes evolve into a smart manufacturing paradigm, which can ensure product quality by automated sensing and control. However, due to limitations with the spatial resolution, scanning speed, and size of the focusing area, commercially available systems cannot be directly used for in-process monitoring in smart manufacturing. For example, a metal 3D printer requires a scanner with second-level sensing, micron-level spatial resolution, and a centimeter-scale scanning region. Among the 3D scanning technologies, structured light 3D scanning can meet the scanning speed criteria but not the spatial resolution and scanning region criteria. This work addresses these challenges by reducing the field of view of a structured light scanner system while increasing the image sensor pixel resolution. Improvements to spatial resolution and accuracy are achieved by establishing hardware selection criteria, integrating the proper hardware, designing a scale-appropriate calibration target, and developing noise reduction procedures during calibration. An additively manufactured Ti-6Al-4V part was used to validate the effectiveness of the proposed 3D scanner. The scanning result shows that both melt pool geometry and overall shape can be clearly captured. In the end, the scanning accuracies of the proposed scanner and a professional-grade commercial scanner are validated with a nanometer-level accuracy white light interferometer using high-density point cloud data. Compared to the commercial scanner, the proposed scanner improves the spatial resolution from 48 µm to 5 µm and the accuracy from 108.5 µm to 0.5 µm.

A method for measuring angular bearing errors in the “antenna - radome” system in the phased-array beam scanning region

The paper introduces a method for measuring angular bearing errors in an antenna-radome system in a two-dimensional angular region of scanning of electronically steerable antenna, i.e. phased array antenna, active phased array antenna. The measurements were based on an antenna measuring collimator system - “compact testing ground”. The mathematical expressions used in processing the obtained data are given. To make a matrix of angular bearing errors, measurements are carried out at different angles of the heel of the antenna - radome system when the phased array antenna beam is deflected in oblique planes. To perfect the method at the initial stage, we used a quick-release model of the radome, which has the ability to introduce angular bearing errors

Extra radiation dose of lungs in male examinees during cardiac computed tomography

The use of multi-detector row computed tomography in cardiac examinations is increasing globally. Several hospitals are yet to establish a practical method for evaluating the extra scattering dose in the lungs (Dlung) of male examinees with different body-weights undergoing cardiac computed tomography. To measure the dose in each slice of a lung (Dlung,i), thermoluminescent dosimeters are inserted into Rando and tissue-equivalent phantoms made of polymethylmethacrylate and derived from ICRU 48 with masses from 10 to 90 kg. Dlung was evaluated by weighing the scanned volume of each slice. A practical method for determining Dlung involves 64-slice computed tomography scans using a Philips Brilliance computed tomography at 120 kV and 200 mAs, with a thickness of 1.0 mm. Dlung,i increased with distance from the scanning region. This experiment yielded Dlung values from 12.1 ? 2.1 mSv (90 kg) to 23.0 ? 3.8 mSv (10 kg). Finally, a simple equation can be used to derive the relationship between Dlung and the body-weights of a male examinee. Experimental results are compared with others in the literature.

Selection of stable equivalent wavebands for near-infrared spectroscopic analysis of total nitrogen in soil

The selection of stable wavebands for the near-infrared (NIR) spectroscopic analysis of total nitrogen (TN) in soil was accomplished by using an improved moving window partial least squares (MWPLS) method. A new modeling approach was performed based on randomness, similarity and stability, which produced an objective, stable and practical model. Based on the MWPLS method, a search was in the overall scanning region from 400 to 2498 nm, and the optimal waveband was identified to be 1424 to 2282 nm. A model space that includes 41 wavebands that are equivalent to the optimal waveband was then proposed. The public range of the 41 equivalent optimal wavebands was 1590 to 1870 nm, which contained sufficient TN information. The wavebands of 1424 to 2282 nm, 1590 to 1870 nm, and the long-NIR region 1100 to 2498 nm all achieved satisfactory validation effects. However, the public waveband of 1590 to 1870 nm had only a minimum number of wavelengths, which significantly reduced the method complexity. Various equivalent wavebands serve as guidelines for designing spectroscopic instruments. These wavebands could address the restrictions of position and the number of wavelengths in instrument design.

Tracking of urban aerosols using combined LIDAR-based remote sensing and ground-based measurements

A measuring campaign was performed over the neighboring towns of Nova Gorica in Slovenia and Gorizia in Italy on 24 and 25 May 2010, to investigate the concentration and distribution of urban aerosols. Tracking of two-dimensional spatial and temporal aerosol distributions was performed using scanning elastic LIDAR, operating at 1064 nm. In addition, PM10 concentrations of particles, NOx concentrations and meteorological data were continuously monitored within the LIDAR scanning region. Based on the data we collected, we investigated the flow dynamics and the aerosol concentrations within the lower troposphere and found an evidence for daily aerosol cycles. We observed a number of cases with spatially localized increased LIDAR returns, which are associated with the presence of point sources of particulate matter. Daily aerosol concentration cycles were also clearly visible with a peak in aerosol concentration during the morning rush hours and daily plateau at around 17:00 Central European Time. We also found that horizontal atmospheric extinction at the height of 200 m, averaged in limited region with a radius of 300 m directly above the ground-based measuring site, was linearly correlated to the PM10 concentration with a correlation coefficient of 0.84. When considering the average of the horizontal atmospheric extinction over the entire scanning region, a strong dependence on traffic conditions (concentration of NOx) in the vicinity of the ground-based measuring site was observed.

Tracking of urban aerosols using combined lidar-based remote sensing and ground-based measurements

A measuring campaign was performed over the neighboring towns of Nova Gorica in Slovenia and Gorizia in Italy on 24 and 25 May 2010, to investigate the concentration and distribution of urban aerosols. Tracking of two-dimensional spatial and temporal aerosol distributions was performed using scanning elastic lidar operating at 1064 nm. In addition, PM10 concentrations of particles, NOx and meteorological data were continuously monitored within the lidar scanning region. Based on the collected data, we investigated the flow dynamics and the aerosol concentrations within the lower troposphere and an evidence for daily aerosol cycles. We observed a number of cases with spatially localized increased lidar returns, which were found to be due to the presence of point sources of particulate matter. Daily aerosol concentration cycles were also clearly visible with a peak in aerosol concentration during the morning rush hours and daily maximum at around 17:00 Central European Time. We also found that the averaged horizontal atmospheric extinction within the scanning region 200 m above the ground is correlated to the PM10 concentration at the ground level with a correlation coefficient of 0.64, which may be due to relatively quiet meteorological conditions and basin-like terrain configuration.

The Numerical Simulation on the Temperature Field of Laser Cladding

This article uses the finite element software ABAQUS in the process of laser cladding to form the numerical simulation, which establishes numerical simulation model of the temperature field of laser cladding forming the heat transfer. The results show that the laser scanning position of the cladding layer depth direction of a high temperature gradient. Simulation of temperature changes of a known point the temperature change in laser scanning region is drastic. The experimental results show that the numerical simulation model of the temperature field is reasonable. Therefore, the numerical simulation model can be used to analyze the influence of the laser cladding parameters on the temperature field and simulate remelting depth under any scanning speed.

X-ray and CT presentation of advanced gastric carcinomas of different locations

We presented the X-ray and CT findings characteristic for gastric cancers of different localizations (localized in different parts of the stomach). Particularly, esophagogastric junction (EGJ) carcinomas and antral carcinomas are singled out, as two localizations of gastric cancer that we usually meet in everyday clinical and radiological practice, and which have completely different radiological presentation. Advanced carcinomas of esophago-gastric junction, whose incidence is on the rise, usually affect the distal segment of the esophagus, cardia, and proximal part of the stomach, in different proportions. Siewert's, and the Japanese classification of these tumors are listed. Due to the involvement of the distal esophagus, scanning region, besides the abdomen, should be expanded to the chest. Advanced cancer of the antral part of the stomach is presented by the X-ray as a fungating, infiltrative, or combined form, often capturing the entire wall circumference. Possible infiltration of the left liver, the body and neck of the pancreas, colon and anterior abdominal wall should be estimated by CT.