Digital Camera Research Articles

High-normal serum bilirubin is a useful indicator to assess the risk of diabetic retinopathy in type 2 diabetes: A real-world study

BackgroundTo investigate the association of serum bilirubin within normal range, especially unconjugated bilirubin (UCB), with diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM). MethodsIn this cross-sectional, real-world study, 7617 T2DM patients were stratified into quartiles based on serum UCB levels. DR was determined by digital fundus photography and further classified into non-proliferative diabetic retinopathy (NPDR) and PDR. The associations of serum bilirubin levels and UCB quartiles with DR were investigated by logistic regression analysis. ResultsAfter controlling for age, sex, and diabetes duration, the DR prevalence was significantly decreased across the serum UCB quartiles (40.4 %, 33.4 %, 29.7 %, 26.6 % for each quartile, respectively, p < 0.001 for trend). The subjects with DR had lower serum total bilirubin (TB) and UCB, rather than conjugated bilirubin (CB), compared with those without DR (p = 0.003 for TB, p < 0.001 for UCB, and p = 0.528 for CB, respectively), while all three types of serum bilirubin in the subjects with PDR were obviously lower than those with NPDR (p = 0.006 for TB, and p < 0.001 for UCB and CB, respectively). After adjustment for confounding factors, logistic regression demonstrated negative associations of serum TB and UCB levels, rather than CB, with the presence of DR (OR: 0.844, 95%CI: 0.774–0.920, p < 0.001 for TB; OR: 0.828, 95%CI: 0.763–0.899, p < 0.001 for UCB; and OR: 0.984, 95%CI: 0.900–1.074, p = 0.713 for CB, respectively). Additionally, a fully-adjusted analysis revealed a negative correlation between UCB quartiles and DR (p < 0.001). ConclusionHigh-normal serum TB and UCB were closely associated with the decreased odds of DR, while all types of serum bilirubin were negatively correlated with the severity of DR in T2DM patients. Serum bilirubin may be used as a potential indicator to assess the risk and severity of DR in T2DM.

The IGCP 714 Project “3GEO – Geoclimbing & Geotrekking in Geoparks” – Selection of Geodiversity Sites Equipped for Climbing for Combining Outdoor and Multimedia Activities

The IGCP 714 project “3GEO – Geoclimbing & Geotrekking in Geoparks” is financed by the International Geoscience Programme (IGCP) and supported by the International Union of Geological Sciences (IUGS). In this paper, we report on the results of the first phase of the project focused on the criteria to be adopted to select geodiversity sites equipped for climbing or trekking. The selection of geoclimbing sites and geotrekking routes is aimed at combining multimedia tools and outdoor activities for Geosciences promotion and conservation in UNESCO Global Geoparks, aspiring geoparks or geoparks project, and also in protected areas featuring geoheritage sites. Indeed, both outdoor activities and multimedia tools favour the pursuing of many of the United Nations Sustainable Development Goals (e.g., 3, 4, 8, 11). An international consortium of geoscientists from 12 different countries selected, through the proposed procedure, 22 geoclimbing sites, and then they also detected 30 geotrekking routes mirroring Earth geodiversity. At some test sites (geoclimbing and geotrekking) multimedia tools and digital outcrop models have been developed through different methodological approaches (e.g., Structure from Motion and Multi-View Stereo photogrammetry), to open the way to the second part of the project still in progress. These sites and the relative virtual models are herein also shown. The final aim of the IGCP 714 project is indeed to create an open data repository (digital outcrop models, videos, virtual tours, photos, scientific information, and interpretations) to upload data of the selected sites to mirror Earth geodiversity for different users including tourists and school groups.

A digital volume pulse device-finger photo pulse plethysmography to trace the vascular integrity amongst the low back pain subjects with lumbar disc degenerative diseases diagnosed by MRI analysis.

Finger photo pulse plethysmography is a simple, inexpensive and non-invasive method for measurement of arterial stiffness. The objective is to assess the correlation of arterial stiffness in low back pain subjects with lumbar disc degeneration. Thirty-four back pain patients of both sexes in age group of 30-65 were included. Anthropometric measures like height, body weight, body mass index (BMI) were included. Stiffness index (SI) and reflection index (RI) were measured from the digital volume pulse waveform. There was a negative correlation between SI/RI and no correlation between SI and RI with BMI in both sexes. A significant correlation found between weight and BMI in both sexes. Arterial stiffness may not have any influence on disc degeneration. BMI showed some influence on disc degeneration and back pain.

Penciptaan Produk Eksklusif Melalui Aplikasi Material dan Tekstur Pada Karya Fotograf

This research is an effort to synthesize, explore and experiment to formulate photographic products of applied art by combining aspects of photographic art and aspects of painting. Concretely, through this research, digital photo printing will be carried out on paper and canvas media which in the next stage will be applied with painting materials and techniques to get an exclusive impression. The physical consumption of photography is now increasingly focused on meeting domestic and artistic needs. The results of observations show that the texture in the painting has its own visual strength, which is not found in photographic works. The main question of this research is how to select, digitally print photos on certain media, and apply materials and painting techniques to produce unique, exclusive, and characteristic photo works through the application of materials and painting techniques. The innovation resulting from this research is a working model to increase the value of photo prints in society by adding textural elements resulting from the touch of a hand. The creative method for creating works refers to Graham Wallas in The Art of Thoughts which consists of stages: preparation, incubation, illumination and verification. The product will be analyzed by using Otto Ocvirk’s theory in Art Fundamentals Theory and Practice. He discusses that texture gives the illusion of a touch effect so that the surface character looks real. It is found that applying resin to photos printed on paper has a positive impact and corresponds to the illusory effect to be achieved. Keywords: texture, photograph, exclusive product

Simulation and Experimental Investigation of the Effect of Pore Shape on Heat Transfer Behavior of Phase Change Materials in Porous Metal Structures.

With the gradual increase in energy demand in global industrialization, the energy crisis has become an urgent problem. Due to high heat storage density, small volume change, and nearly constant transition temperature, phase change materials (PCMs) provide a promising method to store thermal energy. In this work, we designed and fabricated three kinds of porous metal structures with hexagonal, rectangular, and circular pores and explored the phase change process of PCMs within them. A two-dimensional numerical model was established to investigate the heat transfer process of PCMs within different shapes of porous metal structures and analyze the influence of heat source location on the thermal performance of the thermal storage units. Visualization experiments were also carried out to reveal the melting process of PCMs within different porous metal structures by a digital camera. The results show that paraffin in a porous metal structure with hexagonal pores has the fastest melting rate, while that in a porous metal structure with circular pores has the slowest melting rate. Under the bottom heating mode, the melting time of the paraffin in porous metal structures with hexagonal pores is shortened by 18.6% compared to that in porous metal structures with circular pores. Under the left heating mode, the corresponding melting time is shortened by 16.7%. These findings in this work will offer an effective method to design and optimize the structure of porous metal and improve the thermal properties of PCMs.

Applying Spectroscopies, Imaging Analyses, and Other Non-Destructive Techniques to Olives and Extra Virgin Olive Oil: A Systematic Review of Current Knowledge and Future Applications

Given its huge economic, nutritional, and social value, extra virgin olive oil (EVOO) is an essential food. This flagship product of the countries bordering the Mediterranean basin is one of the most frauded products worldwide. Although traditional chemical analyses have demonstrated to be reliable tools for olive drupes and EVOO quality assessment, they present several drawbacks; the urgent need for fast and non-destructive techniques thus motivated this review. Given the lack of comprehensive reviews in the literature, our first aim was to summarize the current knowledge regarding applying spectroscopies, imaging analyses, and other non-destructive techniques to olives and EVOO. The second aim was to highlight the most innovative and futuristic applications and outline the future research prospects within this strategic production chain. With respect to olive drupes, the most interesting results were obtained using RGB imaging and NIR spectroscopy, particularly using portable NIR devices and specific digital cameras for in-field or in-mill monitoring. Nevertheless, it is important to highlight that RGB imaging and NIR spectroscopy need to be integrated with flesh hardness measurements, given the higher reliability of this parameter compared to olive skin color. Finally, with respect to EVOO, although several useful applications of visible imagining, UV–Visible, NIR, and Mid-Infrared spectroscopies have been found, the online monitoring of EVOO quality using NIR spectroscopy strikes us as being the most interesting technique for improving the EVOO production chain in the near future.

Conversion Factor Estimation of Stacked Eucalypt Timber Using Supervised Image Classification with Artificial Neural Networks

Stacked timber is quantified in-store units and then adjusted with a conversion factor for volume estimation in cubic meters, which is important for the wood trade in South America. However, measuring large quantities accurately can be challenging. Digital image processing and artificial intelligence advancements offer promising solutions, making research in this area increasingly attractive. This study aims to estimate conversion factors of stacked Eucalyptus grandis timber using supervised image classification with Artificial Neuronal Network (ANN). Measured data and photographs from an experiment involving thirty stacks of timber were used to achieve this. The conversion factor was determined using photographic methods that involved the applications of equidistant points and ANN and subsequently validated with values observed through the manual method. The ANN method produced more accurate conversion factor estimates than the equidistant points method. Approximately 97% of the ANN estimates were within the ±1% error class, even when using low-resolution digital photographs.

Effects of camera calibration on the accuracy of Unmanned Aerial Vehicle sensor products

Utilization of Unmanned Aerial Vehicles (UAV) mounted with non-metric consumer grade digital cameras is on the rise globally due to their affordability and ease of operation. For high-accuracy UAV products, there is a need for accurate camera parameters determined through camera calibration. Camera calibration can be performed before (pre-calibration) or during the bundle block adjustment (self-calibration). This study aims to analyze the effect of camera calibration parameters on the accuracy of UAV products namely Digital Elevation Model (DEM) and orthoimage. Camera calibration parameters are estimated using two approaches namely self-calibration which deploys 3D image information of the scene in a bundle adjustment and a 2D reference object-based approach known as Zhang’s technique which requires image information of a planar pattern. A DJI FC220 camera mounted on a DJI Mavic Pro UAV was used. Self-calibration was deployed in Agisoft Metashape software based on Brown’s method and Zhang’s technique was deployed in MATLAB and OpenCV. Based on internal measures of accuracy, OpenCV yields the least reprojection error of 0.14 followed by MATLAB (0.79) and self-calibration (1.21). Processing without calibration yields the highest reprojection error of 2.18. Based on external measures of accuracy, that is the geometric accuracy of UAV products, self-calibration yields the least RMSE of 8.2 and 1.4 cm, for the horizontal and vertical, respectively, followed by Zhang’s technique with 9.6 and 2.3 cm in MATLAB and 13.5 and 4.3 cm in OpenCV. Processing without calibration yields the highest vertical RMSE of 20.0 and 22.9 cm for the horizontal and vertical, respectively. Comparison of accuracy of UAV mapping products computed with and without calibration emphasizes the need for camera calibration to optimize accuracy of UAV products. This study recommends assessing other photogrammetric mapping software and camera calibration approaches and the effect of flying heights on calibration parameters and mapping accuracy.

Consumer willingness to pay (WTP) for beef based on color and price discounts

Discoloration of beef products leads retailers to offer discounts or discard beef products, as consumers tend to reject a brownish beef color. This practice contributes to retail food waste and inefficient resource allocation linked to beef production. The objective of this study was to investigate U.S. consumer preferences for beef color and price discounts. After an initial test for screen acuity regarding color perception using a condensed form the ishihara test, data on meat purchasing behavior as well as demographic information was collected for all participants. An additional part of the study undertook a hypothetical discrete choice experiment using digital photos of beef steaks with different meat color, price, and discount labels in retail packaging to examine consumer preferences, willingness to pay, and the effects of discount pricing. Results of a Mixed Logit Model based on choice data show that beef shoppers perceive, see, and prefer color nearly linearly across days of retail display. Consumers' willingness to pay was negative for 4, 7 and 9 days of retail display relative to day zero and decreased with an increase in discoloration. Results indicate that beef shoppers would have to be financially compensated for choosing a steak that was discolored after 9 days of retail display. However, male beef buyers exhibit weaker preferences for color and could be a target segment for promoting discolored beef products to reduce meat waste.

Reliability of the Test of Gross Motor Development Third Edition Among Children with Developmental Coordination Disorder

Aim The Test of Gross Motor Development Third Edition (TGMD-3) is used to assess the development of fundamental movement skills in children from 3 to 10 years old. This study aimed to evaluate the intra-rater, inter-rater, and test-retest reliability and to determine the minimal detectable change (MDC) value of the TGMD-3 in children with developmental coordination disorder (DCD). Methods The TGMD-3 was administered to 20 children with DCD. The child’s fundamental movement skills were recorded using a digital video camera. Reliability was assessed at two occasions by three raters using the generalizability theory. Results The TGMD-3 demonstrates good inter-rater reliability for the locomotor skills subscale, the ball skills subscale, and the total score (φ = 0.77 − 0.91), while the intra-rater reliability was even higher (φ = 0.94 − 0.97). Test-retest reliability was also shown to be good (φ = 0.79-0.93). The MDC95 was determined to be 10 points. Conclusion This study provides evidence that the TGMD-3 is a reliable test when used to evaluate fundamental movement skills in children with DCD and suggests that an increase of 10 points represents a significant change in the motor function of a child with DCD.

Properties of biochars derived from different straw at 500℃ pyrolytic temperature: Implications for their use to improving acidic soil water retention

Climate change cause extreme weather effects with temperature increases and drops in humidity, such as drought and heatwaves, which will lead to more evaporation in arid and semi-arid lands. The application of biochar made from crop straw without burning to farmland can effectively improve the water retention capacity of soil. A testing program has been carried out in a climate simulation laboratory to study the effects of different straw biochars on the cracking and evaporation of soils due to drying. Biochar from wheat straw (WS), corn straw (CS) and rice straw (RS) is produced at a pyrolysis temperature of 500℃. Thermogravimetric analysis and elemental analysis are carried out to obtain the properties of the biochar. Five percent of WS, CS and RS biochar by weight is added to acidic soil. Digital camera and digital image processing technology are used to analyze the crack morphology of the samples during evaporation. The results indicate that the RS biochar has the highest ash content (32.5 %), CS biochar has the highest content of volatile solid (25.36 %) and WS biochar has the highest content of fixed carbon (55.38 %). Biochar can effectively improve the water retention capacity of soil. The final water contents of the WS, CS and RS biochar soil samples are 132.3 %, 101.0 %, and 20.7 % respectively higher than that of the soil without biochar. Moreover, biochar can effectively reduce the degree of soil cracking. The addition of WS, CS and RS biochar can reduce soil cracking by 9.21 %, 16.57 %, and 7.46 %, respectively. WS contains more total cellulose than CS and RS, so WS biochar is the best choice to improve soil water retention ability. Therefore, biochar technology helps to optimize soil water retention while avoiding environmental pollution from straw burning.

Low-cost, high-volume imaging for entomological digitization.

Large-scale digitization of natural history collections requires automation of image acquisition and processing. Reflecting this fact, various approaches, some highly sophisticated, have been developed to support imaging of museum specimens. However, most of these systems are complex and expensive, restricting their deployment. Here we describe a simple, inexpensive technique for imaging arthropods larger than 5 mm. By mounting a digital SLR camera on a CNC (computer numerical control) motor-drive rig, we created a system that captures high-resolution z-axis stacked images (6960 × 4640 pixels) of 95 specimens in 30 minutes. This system can be assembled inexpensively ($1000 USD without a camera) and it is easy to set-up and maintain. By coupling low cost with high production capacity, it represents a solution for digitizing any natural history collection.

Airside Surveillance by Computer Vision in Low-Visibility and Low-Fidelity Environment

Low visibility at airports can significantly impact airside capacity, leading to ground delays and runway/taxiway incursions. Digital tower technology, enabled by live camera feeds, leverages computer vision to enhance airside surveillance and operational efficiency. However, technical challenges in digital camera systems can introduce low-fidelity transmission effects such as blurring, pixelation, or JPEG compression. Additionally, adverse weather conditions like rain and fog can further reduce visibility for tower controllers, whether from digital video or out-of-tower views. This paper proposes a computer vision framework and deep learning algorithms to detect and track aircraft in low-visibility (due to bad weather) and low-fidelity (due to technical issues) environments to enhance visibility using digital video input. The framework employs a convolutional neural network for aircraft detection and Kalman filters for tracking, especially in low-visibility conditions. Performance enhancements come from pre- and postprocessing algorithms like object filtering, corrupted image detection, and image enhancement. It proves effective on an airport video dataset from Houston Airport, enhancing visibility under adverse weather conditions.

Effects of artificial light on foraging behavior of the Pacific Kangaroo Rat (Dipodomys agilis)

Abstract Artificial light at night is increasingly recognized as a cause of habitat degradation, and as a conservation threat to wildlife species. We studied the behavioral response of Pacific kangaroo rats (Dipodomys agilis) to natural and artificial light in coastal sage scrub in southern California, United States. We used digital trail cameras to monitor visits to seed trays in shrub and open, intershrub microhabitats. Under natural-light conditions, kangaroo rats were more active on full- than new-moon nights, and concentrated foraging beneath shrubs. Surprisingly, kangaroo rats frequently interacted with other rodents in seed trays. Near to an artificial light source, kangaroo rats removed fewer seeds, had fewer foraging bouts, and spent less time in trays—especially in brightly lit open microhabitats—compared to distances farther from the light. Differences between the first and second nights of trials during both experiments suggested that kangaroo rats learned locations of resource-rich seed trays and modified their behavior accordingly. Our results are similar to recent studies showing that artificial light depresses foraging activity of rodents in the areas of highest illumination, and adds to evidence of the need to mitigate impacts of urban lighting in fragments of coastal sage scrub, especially along the urban–wildland interface.

Ophthalmic assessment of an intensive care ward patients in the first and last wave of the COVID-19. Do they have a difference?

BACKGROUND: The new coronavirus infection (COVID-19) gained the pandemic status in 2020, and despite the fact that since then the virus has become less pathogenic, its virulence has increased by 2023. Well-vascularized organs and tissues, including the retina, represent the target for coronavirus. The etiopathogenesis of COVID-associated retinopathy, first described in 2021, still remains poorly understood, and its forms and occurrence frequency during different periods of the infectious process vary greatly. AIM: To identify the main characteristics of the COVID-associated retinopathy in patients with moderate and severe COVID-19 course during the acute period of the disease. MATERIALS AND METHODS: The study, conducted in 2021 (group 1) and 2023 (group 2), included patients with confirmed COVID-19 of moderate to severe course during the first 7 days from the onset of symptoms. Group 1 included 46 people, mean age 65.5 years, and group 2 included 55 people, mean age 69.3 years. The ophthalmologic examination was carried out in the “red zone” and intensive care unit, and included examination of the anterior segment of the eye, indirect ophthalmoscopy, and fundus photography using a portable hand-held digital fundus camera (Smartscope M5, Optomed, Finland). Hypertension, diabetes mellitus, volume of lung damage, invasive mechanical ventilation, and anticoagulant therapy were considered as conditions affecting retinal microcirculation. RESULTS: The observation groups were homogeneous in terms of gender, age, and concomitant diseases. The incidence of ophthalmoscopic findings in group 1 was 17.3%, and in group 2 — 12.7%. Most often, during the first 7 days of the disease, signs of angiopathy were observed: dilatation of blood vessels, irregularity of their diameter and tortuosity. Among focal changes, there were multiple retinal hemorrhages (6.5% and 3.6%) and cotton wool spots (4.3% and 5.4%). In patients with fundus changes, diabetes mellitus was significantly less common (in group 1, 25% vs. 39%, p 0.001; in group 2, 28% vs. 44%, p 0.001), as well as arterial hypertension (in group 1, 55% vs. 66%, p = 0.003; in group 2 28% vs. 83%, p 0.001). In group 1, there was a higher proportion of patients treated in intensive care unit, as in group 2 (37% vs. 17%, p 0.001), but in group 2, patients with identified retinal changes were more likely to receive therapeutic doses of anticoagulants (33% vs. 12%, p 0.001). CONCLUSION: The main characteristics of COVID-associated retinopathy in patients with moderate to severe COVID-19 during the acute period of the disease are dilatation and pathological tortuosity of the retinal arteries and veins, intraretinal hemorrhages and cotton wool spots. The connection between COVID-associated retinopathy and concomitant to the infectious process cardiovascular conditions has not been established. Retinopathy associated with coronavirus infection, with absolute similarity of clinical manifestations, was significantly more common in 2021 than in 2023.

Four-Dimensional Digital Monitoring and Registering of Historical Architecture for the Preservation of Cultural Heritage

Preserving cultural heritage through monitoring, registering, and analyzing damage in historical architectural structures presents significant financial and logistical burdens. Developed approaches for monitoring and registering 4D (4-dimensional)-scanned range and raster images of damaged objects were investigated in a case study of historical Baron Palace in Egypt. In the methodology, we first prepared and observed the damaged historical models. The damaged historical models were scanned using a laser scanner at a predetermined date and time. Simultaneously, digital images of the models were captured (by a calibrated digital camera) and stored on a researcher’s tablet device. By observing and comparing the scanned models with the digital images, geometric defects and their extent are identified. Then, the observed data components were detected on the map. Then, damaged statue materials were investigated using system of energy dispersive (SEM; scanning electron microscope, Gemini Zeiss-Ultra 55) and XRF (X-ray fluorescence) spectroscopic analysis to identify the statue’s marble elements, and the results indicate that SEM-EDX and XRF analyses accurately identify major and minor compositions of the damaged statue. Then, the damaged models were registered in two stages. In the registration stages, the corresponding points were determined automatically by detecting the closest points in the clouds and ICP (iterative closest point) algorithm in RiSCAN. The point clouds (of the Palace and damaged statues) gave very detailed resolutions and more realistic images in RiSCAN, but it is a costly program. Finally, the accuracies of the registration tasks were assessed; the standard deviations are within acceptable limits and tend to increase irregularly as the number of polydata observations used in the registration calculations increase.

Vision-Based Online Molten Pool Image Acquisition and Assessment for Quality Monitoring in Gas–Metal Arc Welding

In gas–metal arc welding (GMAW), the welding quality is influenced by various factors, including the welding conditions and external environment. Achieving a high welding quality requires careful observation and control. Welding monitoring is crucial for validating a planned welding process and assessing its quality. This study introduces a vision system for the online acquisition of clear molten pool images. It uses a small camera equipped with a complementary metal-oxide-semiconductor sensor during GMAW, as well as a method for constructing this system. The proposed vision system does not require triggering using devices such as field-programmable gate arrays, facilitating lower costs and online quality monitoring under various welding conditions during mild-steel GMAW. Accurate measurement of radiation from the weld is essential for clear observation of the molten pool during welding, emphasizing the importance of selecting an optical system with appropriate lenses and filters. In addition, appropriate digital camera parameters must be set for monitoring. High-quality images were successfully captured using the proposed method, and the image quality was evaluated using the blind/referenceless image spatial quality evaluator algorithm.

The Effect of Resin Infiltration Technique on the Calculated Color Change of Demineralized Lesions of Different Severities.

To assess the color change of demineralized enamel lesions of different severities after resin infiltration using both clinical spectrophotometry and digital photography. Sixty sound human premolars were randomly divided into 3 groups according to the demineralization level. All the teeth were immersed in a demineralizing solution of a pH adjusted to 4.4 at 37°C. Three levels of demineralization were obtained (D1 shallow, D2 moderate, D3 deep) according to the demineralization time. The demineralized area was then infiltrated by low-viscosity resin (ICON, DMG, Germany). Two instrumental methods were utilized to assess the color difference, a clinical spectrophotometer and digital photography at three time points (sound, demineralized, and infiltrated enamel) to calculate the color difference between sound and demineralized enamel (ΔE1) and between sound and infiltrated enamel (ΔE2). Statistical analysis was performed by ANOVA, followed by Tukey's post hoc test. The correlation was analyzed using linear regression. Two-way ANOVA showed statistically significant differences for both levels of the study (p≤0.05). The color change (ΔE1) and (ΔE2) for different demineralization levels showed statistically significant differences between all groups. For both clinical spectrophotometry and digital photography, D3 showed the highest difference followed by D2 and then D1. As for (ΔE1) calculations, digital photography had a significantly higher difference than spectrophotometry for the D1 group (5.47±0.93 vs 2.78±0.58). As for (ΔE2) digital photography had a statistically significantly lower difference than spectrophotometry (5.55±1.05 vs 6.48±0.76) for the D3 group. Color correction after resin infiltration is affected by the demineralization level of enamel. Clinical spectrophotometry and digital photography can detect similarly the color change of demineralized enamel after resin infiltration in shallow and moderate demineralization. However, in deep demineralization clinical spectrophotometry tends to exaggerate the color change compared to digital photography.

Three-Dimensional Density And Flight Direction Measurement In The Ballistic Range

Simultaneous measurement of the three-dimensional density field around the Hayabusa-type re-entry capsule model and the angle of attack using the 3D-BOS (Background Oriented Schlieren) technique was carried out in the ballistic range at the Institute of Fluid Science (IFS), Tohoku University. A Hayabusa-type re-entry capsule model with a diameter of 25 mm was used for the test model, and the free-flight Mach number was 1.20. A total of 22 digital cameras were installed for the two set of 3D-BOS measurement system. Each of 11 digital cameras are synchronized and captures the flow field around the test model at two different moments. In this paper, the model position at the different moments were measured using two sets of 3D-BOS measuring systems based on image processing, and the model flight direction and angle of attack were measured. The results showed that the stagnation point predicted from the angle of attack and the maximum density point showed good agreement. Therefore, we conclude that the density distribution around the reentry capsule model obtained by the 3D-BOS technique can be directly compared with the CFD results.

Glimmer Synchronization Of Luciola Parvula Fireflies To External Stimulas

It is known that the Luciola parvula fireflies clearly emit the lights at regular time intervals and synchronization between multiple males are observed, but the details of synchronization have not yet been clarified. Presently, we took videos of the luminescence phenomenon of multiple male Luciola parvula fireflies and performed a correlation analysis on the details of the time change of the luminescence brightness of each male Luciola parvula fireflies. The 12 Luciola parvula fireflies are kept in glass wells so that each Luciola parvula fireflies can only moves in restricted areas and their luminescence is recorded by a digital movie camera at the video rate of 30 fps. According to the preliminary study, each glimmer lasts about 3 frames and thus the time series brightness is fitted by a parabolic function in order to give a precise timing of maximum brightness. First of all, time intervals between glimmers of each Luciola parvula fireflies are evaluated. Secondly, the glimmer correlation between different Luciola parvula fireflies are investigated. As a result, it was clarified that the light emission cycle of Luciola parvula fireflies is almost constant at 0.54 seconds, more than 70% of all light emissions are synchronized and the order of synchronization is almost fixed with very small delay. Consequently, it has been shown quantitatively that the glimmers of male Luciola parvula fireflies are well synchronized.