Interlaced Scanning Research Articles

Dimethicone-assisted interlaced scanning compound cutting for regulating thermal damage in CFRP laser cutting by synergistic suppression of coupled heat effect

Carbon fiber reinforced polymer (CFRP) is prone to produce significant thermal damage such as heat-affected zone (HAZ) during laser cutting, which seriously affects the processing quality. In this paper, a new method of dimethicone-assisted interlaced scanning mode (DISM) compound cutting is proposed to regulate the surface damage of CFRP nanosecond UV laser hole cutting. Based on the simulation and experimental testing analysis, the coupling effect of heat conduction and heat accumulation during the laser cutting process, as well as the suppression mechanism of heat effects by compound cutting methods have been described. Compared to the default cutting method, DISM can effectively reduce the damage of CFRP laser hole cutting. The average matrix recession (MR) width of the hole entrance edge is reduced by 47.54% for DISM, while eliminating the heat-damaged matrix (HDM) zone, resulting in a comprehensive reduction of HAZ by 85.2%. The most obvious parameter combination for the reduction of MR width is 50 kHz, 1000 mm/s, and 0.06 mm, where the MR is reduced by 61.31% (37.61 μm→14.55 μm). Interlaced scanning mainly reduces MR width, while dimethicone-assisted processing exhibits suppression of HDM. The compound cutting method significantly reduces thermal damage and improves CFRP mechanical properties.

Reconfigurable Intelligent Surface Aided Position and Orientation Estimation Based on Joint Beamforming With Limited Feedback

The sparsity of millimeter wave (mmWave) channels in angular and temporal domains has been exploited for channel estimation, while the associated channel parameters can be utilized for localization. However, line-of-sight (LoS) blockage makes localization highly challenging, which may lead to big positioning inaccuracy. One promising solution is to employ reconfigurable intelligent surfaces (RIS) to generate virtual line-of-sight (VLoS) paths. Hence, it is essential to investigate the wireless positioning in RIS-aided mmWave systems. In this paper, an adaptive joint LoS and VLoS localization scheme is proposed, where the VLoS is constructed by a beamforming protocol operated between RIS and mobile station (MS). More specifically, to sense the location and orientation of a MS, a novel interlaced scanning beam sweeping algorithm is proposed to acquire the optimal beams. In this algorithm, LoS and VLoS paths are separately estimated and the optimal beams are selected according to the received signal strength so as to mitigate the LoS blockage problem. Then, based on the selected beams and received signal strength, angle of arrival (AoA), angle of departure (AoD), angle of reflection (AoR) and time of arrival (ToA) are estimated. Finally, with the aid of these estimated parameters, the location and orientation of the MS are estimated. We derive the Cramer-Rao lower bounds (CRLBs) for both location estimation and orientation estimation, and compare them with the corresponding results obtained from simulations. We compare the performance of our proposed scheme with that attained by three legacy schemes, when various aspects are considered. The performance results show the superiority of our proposed beam training algorithm, which is capable of achieving a localization error within 15 cm and an orientation error within 0.003 rads. Furthermore, the training overhead is 100 times less than that of the conventional exhaustive search algorithm, while obtaining a 13 dBm power gain when compared with the hierarchical codebook based search algorithm.

Measuring capillary flow dynamics using interlaced two-photon volumetric scanning

Two photon microscopy and optical coherence tomography (OCT) are two standard methods for measuring flow speeds of red blood cells in microvessels, particularly in animal models. However, traditional two photon microscopy lacks the depth of field to adequately capture the full volumetric complexity of the cerebral microvasculature and OCT lacks the specificity offered by fluorescent labeling. In addition, the traditional raster scanning technique utilized in both modalities requires a balance of image frame rate and field of view, which severely limits the study of RBC velocities in the microvascular network. Here, we overcome this by using a custom two photon system with an axicon based Bessel beam to obtain volumetric images of the microvascular network with fluorescent specificity. We combine this with a novel scan pattern that generates pairs of frames with short time delay sufficient for tracking red blood cell flow in capillaries. We track RBC flow speeds in 10 or more capillaries simultaneously at 1 Hz in a 237 µm × 237 µm × 120 µm volume and quantified both their spatial and temporal variability in speed. We also demonstrate the ability to track flow speed changes around stalls in capillary flow and measure to 300 µm in depth.

A Photogrammetric System for Tunnel Underbreak and Overbreak Detection

Overbreak and underbreak exerts negative impacts on the peripheral rocks mass around the excavation area, and also affects the construction cost and safety of the underground structures. Although a wide variety of monitoring and computing methods have been developed and applied to detect the tunnel overbreak and underbreak, these methods are constantly doubted for high cost of instruments. In this paper, a photogrammetric system with advantages of accuracy and efficiency is proposed for detection and prevention of tunnel overbreak and underbreak in construction. The proposed system employs an image matching method based on improved Hausdorff distance and image interlace scanning and region growing principles for higher efficient marker recognition, and uses the cubic parametric interpolation spline method to approximate the tunnel section profile. 3-dimensional reconstruction is also integrated in the system for better visualization and volume calculation of underbreak and overbreak. The reliability of the system is verified and successfully implemented in a practical tunnel excavation project, indicating its potential application scenarios in similar projects.

OldVSR: A model for the video super-resolution and restoration of old real-world TV series

With the recent advance in video super-resolution (VSR) techniques, there have been many requests for super-resolve real-world old analog TV series into high-definition digital content. As excellent classical TV series may receive little to no attention due to their poor video quality, restoring them would open new business opportunities for reusing old TV contents. A problem with restoring real-world old TV series is in the complex artifacts introduced by the old interlaced scanning and compression artifacts during the digitization of old analog videos. Though recent DNN-based VSR models perform nicely on clean videos, due to the artificial nature of interlacing and compression artifacts, they fail to restore old videos into a high-definition counterpart free from noticeable artifacts. In this work, we propose OldVSR for restoring old real-world TV series with artifacts of artificial nature. The proposed model implements a bidirectional recurrent structure with first and second-order propagation where each recurrent layer implements two main functions, i.e., Feature alignment (FA) and Pyramid feature aggregation (PFA). The outputs of the forward and backward layers are merged and upsampled to produce a High-Definition (HD) frame of the input standard-definition (SD) frame. We demonstrate through experiments that our proposed OldVSR can effectively remove artifacts of artificial nature from old videos and successfully restores old TV series.

UV laser high-quality drilling of CFRP plate with a new interlaced scanning mode

Based on the default sequential scanning mode (SSM) of the top-down multi-layer concentric circle filling scanning process, an interlaced scanning mode (ISM) is proposed to improve the surface quality of the carbon fibre reinforced polymers (CFRP) plate by a nanosecond UV laser drilling. The mechanism of the CFRP laser drilling has been described. Several experiments are conducted to explore and compare the surface quality under these two different scanning modes. Compared with SSM, the overall average HAZ width of ISMs is reduced by 25.85% by reducing the heat accumulation effect of adjacent trajectories. The best parameter combination for ISM reduces the HAZ width (39.81 µm to 17.91 µm) and taper (0.138 to 0.067) of hole by 55.01% and 51.48% respectively compared to the default SSM. The damage degree of the HAZ and its vicinity using ISM is less than that using SSM, and the micro surface defects are also less.

Multi-laser scan strategies for enhancing creep performance in LPBF

Laser Powder Bed Fusion (LPBF) enables complex structures to be manufactured, which is attractive to industries where augmented service performance can be achieved. However, the build time of LPBF can be slower than traditional manufacturing processes, especially for higher volumes of parts. Multi-laser machines have the potential to significantly reduce process time, but there is little understanding of how interlaced scan strategies impact upon mechanical properties. The results of this work show that multi-laser scan strategies have no adverse effects on the creep properties of LPBF alloy 718 at different build orientations, demonstrating the potential of using multi-laser strategies for faster build rates without compromising the mechanical properties. Indeed, it is shown that for samples built vertically (i.e. where the build direction is parallel to the loading direction), multi-laser samples outperformed their single-laser counterparts and had a similar creep life and secondary creep rate to wrought alloy (1% difference). The single and multi-laser samples built horizontally (i.e. with the build direction perpendicular to the loading direction) and at 45° from the loading direction performed similarly and all failed soon after the onset of tertiary creep. It was also found that the failure of components could not be attributed to the interlacing scan strategies used with multi-laser processing, but rather to the build orientation and its effect on the grain orientation with respect to the loading direction and the stress state of the sample. However, the scan strategy, number of lasers, fraction area of solidified layer, powder underneath the layer and the interlayer rotation meant that the layers themselves as well as the samples were heterogenous. Despite this, the creep life for any given sample was within 73 h (i.e.17%) of its repeats, giving confidence in the results. It is therefore possible, as a result of this work, to understand the effects of multi-laser scan strategies, particularly the laser-to-laser interfaces on LPBF microstructure. Multi-laser scan strategies are shown to have no detrimental effects on the creep performance, while cutting the build time by more than half.

Improved Acquisition and Reconstruction for Wavelength-Resolved Neutron Tomography.

Wavelength-resolved neutron tomography (WRNT) is an emerging technique for characterizing samples relevant to the materials sciences in 3D. WRNT studies can be carried out at beam lines in spallation neutron or reactor-based user facilities. Because of the limited availability of experimental time, potential imperfections in the neutron source, or constraints placed on the acquisition time by the type of sample, the data can be extremely noisy resulting in tomographic reconstructions with significant artifacts when standard reconstruction algorithms are used. Furthermore, making a full tomographic measurement even with a low signal-to-noise ratio can take several days, resulting in a long wait time before the user can receive feedback from the experiment when traditional acquisition protocols are used. In this paper, we propose an interlaced scanning technique and combine it with a model-based image reconstruction algorithm to produce high-quality WRNT reconstructions concurrent with the measurements being made. The interlaced scan is designed to acquire data so that successive measurements are more diverse in contrast to typical sequential scanning protocols. The model-based reconstruction algorithm combines a data-fidelity term with a regularization term to formulate the wavelength-resolved reconstruction as minimizing a high-dimensional cost-function. Using an experimental dataset of a magnetite sample acquired over a span of about two days, we demonstrate that our technique can produce high-quality reconstructions even during the experiment compared to traditional acquisition and reconstruction techniques. In summary, the combination of the proposed acquisition strategy with an advanced reconstruction algorithm provides a novel guideline for designing WRNT systems at user facilities.

Investigation of an interlaced laser beam scanning method for ultrashort pulse laser micromachining applications

Abstract This article investigates picosecond and sub-picosecond laser micromachining of Borofloat®33 glass and provides clear evidence that a simple modification of the laser beam scanning strategy can lead to significant improvement of machining efficiency and hence process throughput. Besides studying the impact of the fundamental laser machining parameters, such as laser fluence, pulse overlap, pulse repetition frequency (PRF), pulse duration and laser spot diameter, on the machined depth, surface roughness and material removal rate (MRR), it also compares the machining results for two different laser beam scanning strategies, called here sequential” method (SM) and “interlaced” method (IM). By changing the scanning strategy from SM to IM, the MRR can be significantly increased because IM allows high-quality machining of the glass at higher PRF values. The experimental results show that this simple, cost-free modification allows the MRR value to be increased by more than 4 times, i.e. from 0.12 mm3/s to 0.53 mm3/s. Moreover, by using a Phantom V2512 high-speed camera, the picosecond laser micromachining process using both SM and IM was filmed. The videos show that SM leads to the accumulation of glass particles within the laser-machined area, whereas in IM the glass material is removed layer by layer which leads to the generation of “cleaner” and deeper areas. The mechanisms associated with these machining improvements are discussed.

Multiple Step Interlaced Beam Scan to Minimize the Deviation of Radar Detection Performance

For detection of targets, a radar conventionally scans a specified search volume with a fixed beam lattice of a specified beam spacing. With the fixed beam lattice, the detection performance of the radar within a unit beam lattice changes depending on the line-of-sight angle to a target. In this paper, multiple step interlaced scan is proposed to minimize the deviation of the detection performance due to the change of the target line-of-sight angle. As a figure of merit for the detection performance, the cumulative probability of detection is analyzed for various values of the interlaced scan step with different beam overlap ratios, and the optimal values of the steps to minimize the deviation of the cumulative probability of detection are derived.

Restored interlaced volumetric imaging increases image quality and scanning speed during intravital imaging in living mice.

Dynamic intravital imaging is essential for revealing ongoing biological phenomena within living organisms and is influenced primarily by several factors: motion artifacts, optical properties and spatial resolution. Conventional imaging quality within a volume, however, is degraded by involuntary movements and trades off between the imaged volume, imaging speed and quality. To balance such trade-offs incurred by two-photon excitation microscopy during intravital imaging, we developed a unique combination of interlaced scanning and a simple image restoration algorithm based on biological signal sparsity and a graph Laplacian matrix. This method increases the scanning speed by a factor of four for a field size of 212 μm × 106 μm × 130 μm, and significantly improves the quality of four-dimensional dynamic volumetric data by preventing irregular artifacts due to the movement observed with conventional methods. Our data suggest this method is robust enough to be applied to multiple types of soft tissue.

Paper : Flicker-Free Method for Video Captured at 120-Hz Frame Frequency by Interlaced Scanning and Electrical Shutter

Paper : Flicker-Free Method for Video Captured at 120-Hz Frame Frequency by Interlaced Scanning and Electrical Shutter

Inner Focus Iterative Reconstruction Method with the Interlaced Phase Stepping Scanning for Grating-based Phase Contrast Tomography.

The potential clinical application of grating-based phase contrast computed tomography (GPCCT) requires moderate scanning time to reduce the radiation dose, which are not met by traditional GPCCT phase stepping (PS) method. Previous studies have proposed the interlaced scanning method to reduce the scanning time. However, due to the projection number demanded by the analysis reconstruction algorithm, the projection and scanning time cannot be further reduced. In this paper, we proposed an iterative algorithm based on the interlaced PS scanning for GPCCT, which was capable in reducing the motion artifacts during reconstruction as the same as the inner focus (IF) method we raised before. Furthermore, the iterative procedure is expected to introduce some machine learning method and allows a lower radiation dose while maintaining the image quality. Our proposed method mainly consists of three steps: 1) Interlaced data acquisition, 2) Phase retrieval, 3) Inner focus iterative reconstruction. Through changing the virtual rotation center and merging high resolution regions, images without severe boundary blurring can be reconstructed with fast scan speed. The experiment result indicates that our method can reconstruct GPCCT data with interlaced PS scanning.

Beam Training and Allocation for Multiuser Millimeter Wave Massive MIMO Systems

We investigate beam training and allocation for multiuser millimeter wave massive MIMO systems. An orthogonal pilot based beam training scheme is first developed to reduce the number of training times, where all users can simultaneously perform the beam training with the base station (BS). As the number of users increases, the same beam from the BS may point to different users, leading to beam conflict and multiuser interference. Therefore, a quality-of-service (QoS) constrained (QC) beam allocation scheme is proposed to maximize the equivalent channel gain of the QoS-satisfied users, under the premise that the number of the QoS-satisfied users without beam conflict is maximized. To reduce the overhead of beam training, two partial beam training schemes, an interlaced scanning (IS) and a selection probability (SP) based schemes, are proposed. The overhead of beam training for the IS-based scheme can be reduced by nearly half while the overhead for the SP-based scheme is flexible. Simulation results show that the QC-based beam allocation scheme can effectively mitigate the interference caused by the beam conflict and significantly improve the spectral efficiency while the IS-based and SP-based schemes significantly reduce the overhead of beam training at the cost of sacrificing spectral efficiency a little.

Interlaced Laser Beam Scanning: A Method Enabling an Increase in the Throughput of Ultrafast Laser Machining of Borosilicate Glass

We provide experimental evidence that the laser beam scanning strategy has a significant influence on material removal rate in the ultrafast laser machining of glass. A comparative study of two laser beam scanning methods, (i) bidirectional sequential scanning method (SM) and (ii) bidirectional interlaced scanning method (IM), is presented for micromachining 1.1-mm-thick borosilicate glass plates (Borofloat® 33). Material removal rate and surface roughness are measured for a range of pulse energies, overlaps, and repetition frequencies. With a pulse overlap of ≤90%, IM can provide double the ablation depth and double the removal rate in comparison to SM, whilst maintaining very similar surface roughness. In both cases, the root-mean-square (RMS) surface roughness (Sq) was in the range of 1 μm to 2.5 μm. For a 95% pulse overlap, the difference was more pronounced, with IM providing up to four times the ablation depth of SM; however, this is at the cost of a significant increase in surface roughness (Sq values >5 μm). The increased ablation depths and removal rates with IM are attributed to a layer-by-layer material removal process, providing more efficient ejection of glass particles and, hence, reduced shielding of the machined area. IM also has smaller local angles of incidence of the laser beam that potentially can lead to a better coupling efficiency of the laser beam with the material.

A Plant Image Compression Algorithm Based on Wireless Sensor Network

This paper designs and implements an image transmission algorithm applied to plant information collection based on the wireless sensor network. It can effectively reduce the volume of transmitted data, low-energy, high-availability image compression algorithm. This algorithm mainly has two aspects of improvement measures: the first is to reduce the number of pixels that transmit images, from interlaced scanning to interlaced neighbor scanning; the second is to use JPEG image compression algorithm [1], changing the value of the quantization table in the algorithm [2]. After image compression, the image data volume is greatly reduced; the transmission efficiency is improved; and the problem of excessive data volume during image transmission is effectively solved.

Detection of <i>Para</i>-Chloroaniline Resulting from the Interaction between Sodium Hypochlorite and Chlorhexidine Analyzed by Mass Spectrometry

5.1% of sodium hypochlorite (NaOCl) mixed with 2% of chlorhexidine (CHX) forms a brown precipitate that corresponds to para-chloroaniline (PCA), whether PCA is formed after the combination of NaOCl, CHX, and ethylenediaminetetraacetic acid (EDTA) by means of electron impact (high resolution and interlaced scanning) and ionization by fast atom bombardment (FAB), was analyzed. The brown precipitate, showed signals 127 and 153 Da, corresponding to p-chloroaniline and p-chlorophenyl isocyanate, respectively. These results were analyzed and compared with signals from the interlaced scanning program and confirmed with high resolution mass spectrometry analysis and compared with the NIST database. The mass spectra of this precipitated after different days confirmed the evolution of byproducts with the presence of a peak m/z = 127, due to the decrease of the fragment m/z = 153, which disappeared after 180 days. A blue and a white precipitate were observed by the addition of CHX (2%) with or without polyethylene glycol, respectively, EDTA (17%) and NaOCl (5.1%) precipitates contain chlorhexidine (m/z = 505), but no PCA was detected. We confirmed that PCA is not formed directly as a byproduct of CHX oxidation, but through the formation of the para-chlorophenyl isocyanate intermediate, which degrades slowly to PCA.

A rapid local backlight dimming method for interlaced scanning video

AbstractThis paper presents a rapid local backlight dimming method for interlaced video to improve the efficiency of displaying interlaced video. In the proposed method, we combine the line average deinterlacing algorithm with the local backlight dimming algorithm. In order to reduce the computational complexity and the backlight power consumption, three novel methods are proposed. The first is to add the sparse method to process the deinterlaced image. Second, the improved dynamic threshold method is used to calculate the dimming factor. And third, the odd field and even field of the same frame use the same backlight brightness to do backlight dimming. The simulation results show that the proposed method can reduce the computational complexity and power consumption, and the experiment results verify that the method can provide high display effect.

Paper] Flicker-Free Method for Video Captured at 120-Hz Frame Frequency by Interlaced Scanning and Electrical Shutter

We propose a flicker-free method for video captured at a 120-Hz frame frequency and a 100-Hz illumination intensity variation frequency by using interlaced scanning and an electrical shutter to broadcast video during the 2020 Olympic Games in Tokyo. We found from the results of image simulation that the human eye cannot identify the decrease in vertical resolution of images with interlaced scanning when they are displayed at a 120-Hz frame frequency. We found that flicker in video captured with the flicker-free method was suppressed to less than one-twentieth of the flicker with 120-Hz progressive scanning as a result of implementation. The sensitivity of the prototype camera head with the flicker-free method also became 1.2 times higher than that with 120-Hz progressive scanning. The 120-Hz flicker-free method could be adopted in a fieldprogrammable gate array of the prototype camera head that has already been developed with a 120-Hz frame frequency.

Standolone 3D Printer with Interlaced Scanning

Standolone 3D Printer with Interlaced Scanning