Aerothermodynamic effects of controlled heat release within the hypersonic shock layer around a large angle blunt cone

Clinical photography is a fundamental aspect of orthodontic treatment and has become critical to patient care, communication and documentation. Digital Single Lens Reflex (DSLR) cameras with a ring flash have been established as a gold standard for clinical photography for many years, however smartphones are increasingly being utilized by both patients and clinicians due to their convenience, cost effectiveness and good accessibility. This study compared the image quality, dimensional accuracy, ease of use and accuracy of shade representation of images produced by recent flagship smartphones versus DSLR cameras with a ring flash. A sample of four recent smartphones and three semi-professional DSLR cameras were compared taking a comprehensive set of orthodontic intra and extra oral clinical photographs. The following outcome measures were assessed for each device: Camera sensor size, image quality, ease of use, dimensional accuracy and colour shade representation. DSLR cameras with a ring flash were statistically significantly superior to smartphones for camera sensor size, image quality rating and dimensional accuracy. There was no significant difference between all devices for their ease-of-use rating or accuracy of colour shade representation. Based on the results of this study, the authors recommend the use of DSLR cameras with a ring flash as a gold standard for clinical photography due to reduced quality rating and image distortion produced by many smartphone cameras.

Generation and development of disturbances in a hypersonic viscous shock layer on a flat plate is studied both experimentally and numerically. The study is performed at the Mach number M∞ = 21 and the Reynolds number ReL = 1.44 × 105 and is aimed at elucidating the physical mechanisms that govern the receptivity and instability of the shock layer at extremely high hypersonic velocities. The experiments are conducted in a hypersonic nitrogen-driven wind tunnel. An electron-beam fluorescence technique, a Pitot probe and a piezoceramic transducer are used to measure the mean density and Mach number contours, as well as density and pressure fluctuations, their spectra and spatial distributions in the shock layer. Direct numerical simulations are performed by solving the Navier–Stokes equations with a high-order shock-capturing scheme in a computational domain including the leading and trailing edges of the plate, so that the bow shock wave and the wake behind the plate are also simulated. It is demonstrated that computational and experimental data characterizing the mean flow field, intensity of density fluctuations and their spatial distributions in the shock layer are in close agreement. It is found that excitation of the shock layer by external acoustic waves leads to generation of entropy–vortex disturbances with two maxima of density fluctuations: directly behind the shock wave and on the external edge of the boundary layer. At the same time, the pressure fluctuations decay inward into the shock layer, away from the shock, which agrees with the linear theory of interaction of shock waves with small perturbations. Thus, the entropy–vortex disturbances are shown to dominate in the hypersonic shock layer at very high Mach numbers, in contrast with the boundary layers at moderate hypersonic velocities where acoustic modes are most important. A parametric numerical study of wave processes in the shock layer induced by external acoustic waves is performed with variations of frequency, amplitude and angle of propagation of external disturbances. The amplitude of generated disturbances is observed to grow and decay periodically along the streamwise coordinate, and the characteristics of these variations depend on the frequency and direction of incident acoustic waves. The hypersonic shock layer excited by periodic blowing and suction near the leading edge is also investigated; in the experiments, this type of excitation is obtained by using an oblique-cut whistle. It is shown that blowing/suction generates disturbances resembling those generated by external acoustic waves, with similar spatial distributions and phase velocities. This result paves the way for active control of instability development in the shock layer by means of destructive interference of two types of disturbances. Numerical simulations are performed to show that instability waves can be significantly amplified or almost entirely suppressed, depending on the relative phase of blowing/suction and acoustic disturbances. Wind-tunnel experiments completely confirm this numerical prediction. Thus, the feasibility of delaying instability development in the hypersonic shock layer has been demonstrated for the first time.

Acquisition of chemiluminescent signals from immunoblots with a digital single-lens reflex camera

Introduction: Smartphone photography has come a long way in terms of technological advances in sensor quality, resolution, and lens sophistication, giving much improved image quality over the last few years. Smartphones being relatively compact and lighter than a Digital SLR camera hence the younger generation dentists prefer it over the conventional cameras. We did a survey to assess the perception of quality of images taken using smartphone and DSLR (Digital Single Lens Reflex) intra oral cameras. The aim of this study is to compare the quality of intraoral images taken using mobile phones with DSLR cameras. Materials and Methods: 20 intra oral images of subjects were taken using DSLR (Canon 700D) and 2 renowned smartphones (iPhone 7 plus and Oppo R7 plus). A questionnaire was prepared and sent through social sources to general dentists and specialists. The questions included in the survey are based on the knowledge, attitude and practice in the usefulness of mobile phones compared to DSLRs for taking intra oral images. Results: The primary outcome measure of this study was to assess the orthodontist’s perception towards the various image characteristics of intra oral photographs taken using digital SLR camera, iPhone 7 plus and Oppo R7 plus. Conclusion: So, from this study we can conclude that there were no statistically significant results found. In the coming years smartphone cameras can really give a tough challenge to bulky cumbersome DSLRs.

Comparison of image quality, color accuracy, and resolution in intraoral photography using digital single lens reflex camera and smartphone cameras: A pilot study

In the framework of the approximation of local similarity to the Navier-Stokes equations, an investigation is made of the axisymmetric flow of homogeneous gas in a hypersonic shock layer, this including the region of transition through the shock wave. Boundary conditions, which take into account blowing of gas, are specified on the surface of the body and in the undisturbed flow. A numerical solution to the problem is obtained in a wide range of variation of the Reynolds number and the blowing parameter. Expressions are found for the dependences on the blowing parameter usually employed in boundary layer theory of the coefficients of friction and heat transfer on the surface of the body, which are divided by their values obtained for blowing parameter equal to zero. It is shown that these dependences are universal and the same as the dependences obtained from the solution of the equations of a hypersonic viscous shock layer with modified Rankin-Hugoniot relations across the shock wave and from the solution of the boundary layer equations.

Abstract. The widespread usage of the mobile technologies and the improvement of the digital photo devices getting has led to more frequent cases of falsification of images including in the judicial practice. Consequently, the actual task for up-to-date digital image processing tools is the development of algorithms for determining the source and model of the DSLR (Digital Single Lens Reflex) camera and improve image formation algorithms. Most research in this area based on the mention that the extraction of unique sensor trace of DSLR camera could be possible on the certain stage of the imaging process into the camera. It is considered that the study focuses on the problem of determination of unique feature of DSLR cameras based on optical subsystem artifacts and sensor noises.

Recently, light field cameras have drawn much attraction for their innovative performance in photographic and scientific applications. However, narrow baselines and constrained spatial resolution of current light field cameras impose restrictions on their usability. Therefore, we design a hybrid imaging system containing a light field camera and a high-resolution digital single lens reflex camera, and these two kinds of cameras share the same optical path with a beam splitter so as to achieve the reconstruction of high-resolution light fields. The high-resolution 4D light fields are reconstructed with a phase-based perspective variation strategy. First, we apply complex steerable pyramid decomposition on the high-resolution image from the digital single lens reflex camera. Then, we perform phase-based perspective-shift processing with the disparity value, which is extracted from the upsampled light field depth map, to create high-resolution synthetic light field images. High-resolution digital refocused images and high-resolution depth maps can be generated in this way. Furthermore, controlling the magnitude of the perspective shift enables us to change the depth of field rendering in the digital refocused images. We show several experimental results to demonstrate the effectiveness of our approach.

Aim and objectives Accurate shade selection is critical for achieving optimal esthetic outcomes in restorative dentistry. Digital photography has emerged as an alternative to conventional visual shade matching; however, the accuracy of smartphone (SP) cameras compared with digital single-lens reflex (DSLR) cameras remains uncertain. This study aimed to compare Commission Internationale de l'Éclairage L*a*b* (CIELAB) color coordinates obtained from SP and DSLR images with manufacturer-provided values of the VITA 3D-Master shade guide (VITA Zahnfabrik, Bad Säckingen, Germany) and to evaluate the reliability of smartphone photography for shade selection. Methods An in vitro study was conducted using a commercial VITA 3D-Master shade guide. Images of 26 shade tabs were captured using an iPhone 13 smartphone (Apple Inc., Cupertino, CA, USA) and a Canon EOS 700D DSLR (Canon Inc., Tokyo, Japan). Two images per shade tab were obtained under standardized daylight conditions (4000-5000 K) at a fixed distance of 18 cm against a neutral gray background, yielding a total of 104 images. Image selection was standardized based on predefined criteria of focus and exposure consistency. CIELAB color values (L*, a*, b*) were extracted using digital image analysis software. Color differences (ΔE) between photographic values and manufacturer reference values were calculated using the CIEDE2000 formula. Statistical analysis was performed using the Wilcoxon signed-rank test, with significance set at P < 0.05. Results Statistically significant differences were observed between SP and DSLR images in deviations of L*, a*, and b* values (P < 0.05). DSLR images demonstrated greater color accuracy, achieving 75% agreement with manufacturer reference values, whereas SP images showed 55% agreement. Mean ΔE values were lower for DSLR images, indicating improved color fidelity. Conclusions Within the limitations of this in vitro study, DSLR photography demonstrated greater accuracy in shade selection compared to smartphone photography. Although smartphones may serve as an accessible adjunct, they currently exhibit lower color accuracy than DSLR systems for shade determination.

Thermal photogrammetric imaging: A new technique for monitoring dome eruptions

We present AstroWISP: a collection of image processing tools for source extraction, background determination, point-spread function/pixel-response function fitting, and aperture photometry. AstroWISP is particularly well suited for working with detectors featuring a Bayer mask (an array of microfilters applied to each detector pixel to allow color photography), such as consumer digital single-lens reflex (DSLR) cameras. Such detectors pose significant challenges for existing tools while offering a much cheaper alternative to specialized devices. As a result, consumer DSLR cameras with Bayer masks are often underutilized for precision photometry. AstroWISP addresses this limitation in an effort to democratize precision photometry and support broader community participation in research. We demonstrate that our tools produce high-precision photometry from such images, enabling the use of such devices for detecting exoplanet transits. We package our tools for all major operating systems to ensure accessibility for amateur astronomers.

In process of 3D image reconstruction, the local image breakage or mismatch are appeared when the objects have high reflection and uniform color properties, such as, windshield of car, reflective paint, etc. In this study, the above-mentioned conditions are overcame by introducing the different statement of software processing to examine the 3D model reconstruction of car. Four types processes, extract the color channel of image, produce the High Dynamic Range Image (HDRI), take the HDRI process directly and Digital Single-Lens Reflex camera (DSLR) image with polarizer are implemented to investigate the problem of image breakage. The results show that the image breakage cannot be conquered using the color channel image extracting. The HDRI producing and HDRI taking directly are solved this problem a little. Obviously, the DSLR image with polarizer shows the good feasibility for solving the phenomena of image breakage.

Detection of ninhydrin-glyphosate in groundwater via the colour chart-assisted digital camera method.

Using the iPhone as a device for a rapid quantitative analysis of trinitrotoluene in soil

Photography are an activity that can be done through a lot of other media, some uses DSLR (Digital Single Lens Reflex) camera, Mirrorless and even from their smartphones. Choosing a mirrorless camera by those who doesn’t have the knowledge of the specifications of a camera might be a problem by itself. The problem itself rose because there’re a lot of criterias that need to be considered in getting the right one and due to lack of information. That is why recommendation system based on website are developed which can help users choosing the right product using SMART (Simple Multi Attribute Rating Technique) method. SMART method are a method for taking decisions that are multi attribute used for supporting decisions which have other alternatives. In developing this website it uses 5 brands of camera that is Canon, Fujifilm, Nikon, Panasonic and Sony. The validity test based from UAT (User Acceptance Rate) of 35 respondents gives a result of 85.71% accuracy that agrees that the recommendation system is appropriate to what user wants and proves that the system gaves the recommendation based on what user wants and beneficial to be used.