Self-developed Image Processing Research Articles

Precise digital bacteria enumeration and antibiotic susceptibility testing via a portable vibrating capillary-based droplet platform

Antibiotic resistance can lead to multidrug-resistant superbugs and threaten global health, putting forward a high demand for accurate and fast antibiotic susceptibility testing (AST). Conventional AST methods are labor-intensive and time-consuming, far from meeting the requirement for rapid clinical decision-making. Here, we develop a portable vibrating capillary-based droplet platform for precise digital bacteria enumeration and rapid AST. Multi-volume droplets encapsulating bacteria with or without antibiotics are generated on demand, and the elevated fluorescence from resazurin reduction is measured, which corresponds to the growing bacteria. Automated data analysis is achieved by a self-developed image processing program. Multi-volume droplet digital counting allows precise bacteria enumeration over a wide dynamic range spanning more than 4 orders of magnitude. Droplet digital AST of ampicillin against E. coli demonstrates that it is feasible for accurately assessing the minimum inhibitory concentration and investigating the inoculum effect, with the assay time reduced to 5 h. In sum, this method is easy to operate, cost-effective, with high accuracy and short time-to-result, which is highly promising for rapid and precise assessment of antimicrobial susceptibility in resource-limited settings.

Species Monitoring Using Unmanned Aerial Vehicle to Reveal the Ecological Role of Plateau Pika in Maintaining Vegetation Diversity on the Northeastern Qinghai-Tibetan Plateau

Plateau pika (Ochotona curzoniae, hereafter pika) is considered to exert a profound impact on vegetation species diversity of alpine grasslands. Great efforts have been made at mound or quadrat scales; nevertheless, there is still controversy about the effect of pika. It is vital to monitor vegetation species composition in natural heterogeneous ecosystems at a large scale to accurately evaluate the real role of pika. In this study, we performed field survey at 55 alpine grassland sites across the Shule River Basin using combined methods of aerial photographing using an unmanned aerial vehicle (UAV) and traditional ground measurement. Based on our UAV operation system, Fragmentation Monitoring and Analysis with aerial Photography (FragMAP), aerial images were acquired. Plot-scale vegetation species were visually identified, and total pika burrow exits were automatically retrieved using the self-developed image processing software. We found that there were significant linear relationships between the vegetation species diversity indexes obtained by these two methods. Additionally, the total number of identified species by the UAV method was 71, which was higher than the Quadrat method recognition, with the quantity of 63. Our results indicate that the UAV was suitable for long-term repeated monitoring vegetation species composition of multiple alpine grasslands at plot scale. With the merits of UAV, it confirmed that pika’s disturbance belonged to the medium level, with the density ranging from 30.17 to 65.53 ha−1. Under this density level, pika had a positive effect on vegetation species diversity, particularly for the species richness of sedge and forb. These findings conclude that the UAV was an efficient and economic tool for species monitoring to reveal the role of pika in the alpine grasslands.

Effect of orifice inlet roundness on internal flow and external spray characteristics in enlarged nozzle with single-passage

This study aims to analyze the cavitating flow inside the nozzle and the spray characteristics near the nozzle tip according to the needle positions and orifice inlet roundness through experimental analysis. To simulate the needle movement during fuel injection by the injector, six needle positions were used. The upper and lower positions of the needle were assumed to be the positions where the needle was fully opened and just before being fully closed. The length-to-width ratio of the nozzle was 2.0, and the nozzle was made in two dimensions for convenience of visualization. The inside of the nozzle was visualized by the shadow graphic visualization technique, and the image was acquired using a high-speed camera. The cavitating flow inside the nozzle and the spray characteristics near the nozzle tip were analyzed using the self-developed image processing code. The experimental results show that cavitating flow characteristics such as cavitation length and cavitation width and external flow characteristics such as spray angle were influenced by the shape of the orifice inlet and needle positions. In addition, when the cavitating flow became the hydraulic flip, the phenomenon in which the spray angle was bent like a bow was examined. This phenomenon occurred frequently as the volume fraction of hydraulic flip at the tip of the nozzle became larger than a certain level. In addition, when the cavitating flow became the hydraulic flip, the phenomenon in which the spray angle was bent like a bow was examined. In addition, we discussed the negative effects that occurring when the same phenomenon in an actual injector.

Laser asymmetric ablation method to improve corneal shape.

This study aims to assess whether central-symmetric corneal thickness reduces off-centered corneal shift caused by intraocular pressure (IOP). In this retrospective study, 122 healthy eyes of 62 presbyopic patients, mostly myopic, were divided into two groups. Two distinct asymmetric corneal ablations were applied in peripheral presbyopia correction to produce central-symmetric corneal thickness, which reduces the off-centered corneal shift by utilizing intraocular pressure. The first method used a 90° angled combination in group 1 and the second method used a 45° angled combination in group 2. Target refraction was spherical equivalent of - 1D. Self-developed image processing algorithm analyzed the change in thickness and the posterior cone, and obtained two factors: central symmetry (f) and visual axis deviation (d), from each eye's pre and postoperative maps of Orbscan II. UDVA and UNVA were also analyzed. In both groups, mean SE was about - 1D and there was no significant difference in UDVA. UNVA was better in group 2 than group 1. Only in group 2, corneal thickness and posterior cone became central-symmetric and the posterior corneal apex point relocated towards the visual axis. The p values were 0.03, 0.04, and 0.03, respectively. This is the first study to control corneal shape by utilizing the interaction between intraocular pressure and corneal thickness. Only group 2 was applied with asymmetric corneal ablation created by the 45° angled combination of semi-cylindrical ablation patterns, and intraocular pressure contributed significantly to reduce the off-centered corneal shift and reshaped the posterior corneal cone to the center.

Linking the Effect of Aggregate Interaction to the Compaction Theory for Asphalt Mixtures Using Image Processing

This study presents a modified compaction concept of asphalt mixtures based on aggregate frictional behavior using self-developed image processing for measuring the aggregate orientation. The compaction energy index was introduced to evaluate the aggregate orientation on different compaction temperatures. For the better rearrangement of aggregates, there was an optimum temperature at which a preferred orientation exists, providing lower compaction efforts. An excessively high temperature reduced the asphalt contents for lubrication and caused additional aggregate friction to require higher compaction efforts. This phenomenon can be found in the changes of the volume of the effective asphalt binder (Veac) and the absorbed asphalt binder (Pba). The mixture produced higher Veac, at which an optimum compaction temperature required lower compaction energy. Despite being higher than the optimum temperature for the PG62-28 mixture, the Veac decreased by 0.4%. An increase of 0.35% in the Pba was inferred to flow into the aggregates. Clearly, a reduction of lubricant in the mixture caused a higher frictional interaction between aggregates. Changes in the Veac and the Pba can eliminate the viscosity effect for the rearrangement of aggregates. Based on the aggregate orientation and change in mixture volumetrics, the aggregate interaction effect was introduced to the Mohr–Coulomb compaction theory to explain the additional friction.

영상처리기법을 이용한 실시간 변위 측정 및 붕괴감지 시스템

The collapse of concrete forms or structures often occur at places with many risks like construction sites. One of the most important factors to assess stability of structure can be the velocity ratio of horizontal direction respect to the vertical direction. In this study, the accuracy of measurement was verified through the steel beam test with the real-time displacement measurement system using the self-developed image processing, and the satisfactory results with the error of 0.1mm were reached when comparing test results using a LVDT. Additionally, through the small-scale model test and the field experiment, the change of displacement with the collapse of structures was measured and the results showed that the horizontal displacement at the time of the collapse increased sharply compared to the vertical displacement. Thus, after measuring the displacement, the collapse can be predicted using the ratio of the vertical to the horizontal direction for the velocity or acceleration.

Evaluation of the performance correlated defects of metamorphic InGaAs photodetector structures through plane-view EBIC

To evaluate the performance correlated imperfection or defect features of metamorphic InGaAs photodetector structures, a scanning electron microscopy scheme including both plane-view electron beam induced current (EBIC) and secondary electron (SE) images have been used. The abilities, merits and limitations as well as some case-dependent properties of EBIC have been discussed in detail. The devices of similar structures grown on InP or GaAs substrates with quite different lattice mismatch show discriminated defect distribution patterns, prompting their distinct origins, which have been confirmed by cross-sectional transmission electron microscopy observation. Using self-developed image processing software the EBIC features of the samples are statistically analyzed, which validated the qualitative correlation between the EBIC data and device dark current. Fusing of EBIC and SE images has also been attempted to enhance the defect visibility. Results indicate that EBIC is feasible to investigate the effects of defects on the device performance not only in research work, but also for product quality monitor purposes.

An automated growth measurement system for leafy vegetables

In plant science, the fundamental information for research and related applications is derived from the measurement of plant features. It is especially useful for applications in plant growth modelling and climate control in greenhouses or plant factories. Standard, direct measurement methods are generally simple and reliable, but they are time consuming and laborious. In contrast, vision-based methods are non-destructive and an efficient way to describe external plant features and plant growth. In this study, a stereo-vision system, using two off-the-shelf cameras with parallel optical axes, integrated a self-developed image processing algorithm to monitor the growth of Boston lettuce in a plant factory. The system was mounted on a sliding rail to extend the field of vision of planting beds. Images were continuously recorded to determine the plants' features and construct panoramic images. The image processing algorithms, that calculated geometric features such as the projected leaf area, plant height, volume and diameters were developed and incorporated into the automated measurement system. Subsequently, plant growth curves were determined from calculations of the plant features data. This automated vision-based system showed promising results when put into practice.

CT Investigation of Fracture Mechanism of Soil-Rock Mixtures

Soil-Rock Mixture (SRM) is a unique type of geological material characterized by inhomogeneous composition and complicated structures. This paper investigated the fracture mechanisms that govern the strength and deformation of SRM subjected to uniaxial compression loads by means of computed tomography (CT) techniques. The self-designed loading devices and self-developed image processing program were applied to identify and quantify the fractures inside SRM during compressions. The results show that the internal fracture behavior of SRM greatly depends on the rock ratios of SRM.

Study on three dimensional reconstruction and simulation surgery of spleen

To study the three-dimensional (3D) reconstruction and the visualization simulation surgery of spleen based on the scanning data of 64-slice helical computed tomograph (CT). The original data of 64-slice helical CT of spleen was collected, and then the CT image sequences were segmented and automatically extracted using auto-adapted region growth algorithm, and were conducted with the segmented images by adopt self-developed image processing software for 3D reconstruction. Finally, the 3D models were imported into FreeForm Modeling System for modifying and smooth. And the visualization simulation surgery was performed before splenectomy. It was fast and effective to utilize auto-adapted region growth algorithm to conduct spleen image program segmentation; the reconstructed models were seen clearly and could reappear the structure of the spleen and the important surrounding organs. The effect of the splenectomy simulation surgery was similar to the practical surgery. The research on 3D models of spleen and visualization simulation surgery of splenectomy could lead to clinical benefits. It maybe improve the surgical effect and decrease the surgical risk and reduce the complication demonstrating visualized operation before surgery.

Automatic finite element mesh generation for maxillary second premolar

Developing three dimensional finite element mesh models for irregular geometric objects requires a large amount of manual efforts, hence limiting the three dimensional approach for dental structure analyses. An automatic procedure which can be used to generate a three dimensional finite element mesh for the maxillary second premolar was developed in this study. Firstly, a embedded second premolar was sliced and scanned parallel to the occlusal surface. A self-developed image processing system was employed to detect the boundaries of different materials within each section. An automatic mesh generation program was used on these boundaries to create tetrahedral elements based on moving nodes of uniform cube approach. Six mesh models of the second premolar with different element sizes using linear and quadratic elements were analyzed. Strain energy and von Mises stresses were reviewed for convergence in the crown regions.

Transient thermal stress intensity factors of edge-cracked semi-infinite plates

In this paper, the digital caustic technique was used to determine the transient thermal stress intensity factors (SIFs) of edge-cracked semi-infinite plates subjected to a sudden temperature change on the plate edge. Effects of different crack lengths and orientations on SIFs were studied. By using the self-developed image processing software on a locally supported digital caustic system, caustic patterns were analyzed and SIFs were then obtained. The correlation expressions between the variations of transient thermal SIFs with the time, temperature difference and geometrical parameters of the cracks were obtained by a regression procedure.