The presented paper experimentally demonstrates the potential expansion of stereolithographic prototype utilization. Two methods for manufacturing plastic prototypes are proposed, enabling the subsequent substitution of the polymer material with either metal or ceramics. The first method involves additional actions by the prototype designer during the modeling stage. The second method necessitates alterations in the technological processes of model preparation and prototype manufacturing using a stereolithography apparatus. Material substitution occurs in two stages. Initially, cavities in the prototype are filled with powder material or a mixture of powder and water. Although titanium powder was chosen as the test material, the proposed technology permits the utilization of a broad spectrum of powder materials, encompassing both metallic and ceramic options. The subsequent stage involves heat treatment, where the polymer is eliminated, and the metal powder is sintered while retaining the original shape and dimensions of the prototype. Heat treatment of the acquired prototypes was conducted in both argon and atmospheric air environments. The utilization of different gas media might induce chemical transformations in the material filling the prototype. The experiments lead to the conclusion that the proposed approaches show promise and merit further development. Additionally, we contemplate amalgamating the two methods in the future to attain an optimized final outcome. The data we have gathered could significantly contribute to broadening the scope of stereolithography applications, given that this technology presently represents one of the most precise, widespread, and accessible additive manufacturing methods.

Abstract—The work is aimed at improvement of the mechanical properties of polymers produced using laser stereolithography technology by modifying the composition of a photocuring resin (PCR) with a highly dispersed filler. A composition based on vinyl ester resin was developed as the starting material, and aluminum hydroxide was chosen as the filler. The addition of the filler to the original PCR leads to a noticeable increase in the viscosity of the composition at 25°C. Specimens obtained both by laser stereolithography technology and by initiating polymerization by incoherent UV radiation were studied simultaneously for comparison. A thermomechanical analysis of the specimens was carried out and their studies were carried out using the differential scanning calorimetry method to determine the thermomechanical characteristics and the degree of conversion of double bonds for these specimens. It has been confirmed that post-curing of specimens is a necessary step in achieving their high mechanical properties. It has been shown that the use of aluminum hydroxide as a PCR filler improves the physicomechanical and thermomechanical properties of cured specimens.

This paper discusses the application of methods of non-destructive testing and flaw detection of plastic products manufactured by additive technologies. The modern development of additive technologies associated with the active transition from the manufacture of prototypes and test samples to the manufacture of functional products increases the requirements for improving the quality of manufacturing and conducting non-destructive diagnostics of finished products, including plastic materials. The overall productivity of the production process can be increased by increasing the yield due to a decrease in the number of defects, which is ensured by process control and the quality of finished products. The method of laser-ultrasound diagnostics allows monitoring and flaw detection of products made of different materials with good spatial resolution, which is not always possible, for example, by tomographic scanning. Thus, the main purpose of this work is to evaluate the possibility of using laser-ultrasonic methods to detect potential defects and to track the impact of the additive manufacturing process on the quality of plastic products.

Monitoring the evolution of the aerodynamic flow in potentially dangerous conditions is very important to ensure flight safety. Due to the impossibility of experimental study of critical flight conditions in real flights, methods of scaled modeling of flow processes have been developed and are widely used in aerodynamics and hydrodynamics. Aircraft icing is one of the most important processes that pose a threat to flight safety. The presented study is aimed at developing techniques for monitoring of process of aircraft icing and its influence on flow behaviour, that can be used in controlled conditions of aerodynamic/hydrodynamic tube. While available technical means for aerodynamic study does not include the wind tunnel for registration of flow simultaneously with icing process, the proposed framework includes as icing process 3D registration so further modelling this process in a hydrodynamic tube for flow monitoring. The proposed technique includes three phases, that allow to perform comprehensive monitoring of the whole process beginning with 3D registration of ice accretion development and completing with accurate 3D flow evolution monitoring corresponding to icing process.

The work is aimed to increase mechanical properties of polymers produced by laser stereolithography technology by modifying the composition of photocurable resin (PCR) by highly dispersed filler. A resin based on vinyl ester was developed as an initial one, and aluminum hydroxide was chosen as a filler for it. Adding the filler to the initial PCR leads to a marked increase in the viscosity of the composition at 25 °C. For comparison samples obtained both by laser stereolithography technology and at initiation of polymerization by incoherent UV radiation were simultaneously studied. Thermomechanical analysis of the samples was carried out and the samples were studied by differential scanning calorimetry to determine the thermomechanical characteristics and the degree of conversion of double bonds for these samples. It has been confirmed that the post-treatment of the samples is a necessary step in achieving their high mechanical properties. It is shown that the use of aluminum hydroxide as a FPC filler leads to an increase in the physical-mechanical and thermomechanical properties of cured samples.

Проблемы бесконтактной регистрации потоков в гидродинамической трубеНовиков Михаил Михайлович 1 , Ипполитов Евгений Викторович 1 , Камаев Сергей Валентинович 1 , Марков Михаил Александрович

Flow visualization is an important mean for studying flow processes in aerodynamics and hydrodynamics. It allows obtaining qualitative valuable information about flow behaviour, that is needed for understanding of aerodynamic performance of an aircraft, especially in critical conditions. With growing advances in 3D optical measuring techniques, accurate 3D registration and measurements of fast developing processes became possible. The paper addresses the problem of accurate metric 3D reconstruction of flow in hydrodynamic tunnel that is necessary for studying aerodynamic process in aircraft icing conditions. It presents the techniques developed for optical measurement system calibration and for accurate flow 3D registration, and the results of laboratory flow 3D reconstruction and visualization. Experimental evaluation of the developed techniques in laboratory hydrodynamic tunnel demonstrated high accuracy of 3D measurements and readiness for applying in aircraft icing study.

Hydrodynamic tunnel has proved to be an effective mean for studying aerodynamic processes using scaled models of real aircrafts. The specificity of study in a hydrodynamic tunnel requires to apply non-contact measuring techniques, such as photogrammetry, for retrieving information on geometrical characteristics of the flow. So reliable calibration of photogrammetric system is a key element for trustworthy analysis of flow behaviour. For 3D measurements in a hydrodynamic tunnel calibration technique must account for refraction effects at optical media interfaces. But often the design of a hydrodynamic tunnel does not allow to perform standard calibration procedure based on image acquisition of a special test field, placed in the working space of the measuring system. The presented study addresses this problem – developing the technique for accurate photogrammetric calibration, for the case of the working space being inaccessible for placing there a test field. The developed calibration technique estimates parameters of interior orientation of the photogrammetric system and parameters of multimedia optical environment by special preliminary procedure, that allows to obtain accurate 3D measurements during experiments in hydrodynamic tunnel. Experimental evaluation of the developed technique demonstrated high accuracy of photogrammetric 3D measurements.

The safety of an aircraft depends on the wing flow process, therefore, the study of air flow in various flight conditions is one of the most important parts of the design and operation of an aircraft. A hydrodynamic tube is one of the most effective means for studying the processes of aircraft flow in aerodynamics. It allows you to simulate special conditions and study flow characteristics that cannot be studied in real flight. Standard flow visualization methods, such as colored jets or fine particles, allow us to obtain qualitative data on the flow behavior. But it is more important to have quantitative flow characteristics that allow you to predict the development of the process and develop recommendations on flight safety measures. In this paper, the possibility of conducting non-contact three-dimensional measurements in hydrodynamic tubes by photogrammetric methods is considered. The article presents the development of a system of remote three-dimensional measurements based on images to obtain an accurate three-dimensional visualization of the flow used to quantify the parameters of the flow of aerodynamic elements in a hydrodynamic tube. The results of experimental studies on the calibration of a three-dimensional measurement system for the case of shooting an object through two boundaries of optical media are presented. The developed method of calibration of a photogrammetric system for three-dimensional measurements in an aqueous medium has demonstrated its applicability to the problem of spatial analysis of flow flows in a hydrodynamic tube.

Physical flow modelling is a powerful tool in aerodynamic researches, especially in analysis of complicated and dangerous conditions.It allows to study flow behaviour and to obtain reliable results via similitude concept, that is widely used in aerodynamics and hydrodynamics.Visualization of flow jets is one of the basic tools for analysis of flow behaviour under different flying conditions.Optical registration and 3D measurement techniques extend the capacities of visual flow study, providing both qualitative and quantitative data.The presented study addresses the problem of development of the vision-based technique for accurate flow 3D registration and 3D visualization.Algorithms allowing accurate 3D reconstructing of flow jets are presented, along with discussion of application for experimental flow 3D visualization.

This paper discusses the application of methods of non-destructive testing and flaw detection of plastic products manufactured by additive technologies. The modern development of additive technologies associated with the active transition from the manufacture of prototypes and test samples to the manufacture of functional products increases the requirements for improving the quality of manufacturing and conducting non-destructive diagnostics of finished products, including plastic materials. The overall productivity of the production process can be increased by increasing the yield due to a decrease in the number of defects, which is ensured by process control and the quality of finished products. The method of laser-ultrasound diagnostics allows monitoring and flaw detection of products made of different materials with good spatial resolution, which is not always possible, for example, by tomographic scanning. Thus, the main purpose of this work is to evaluate the possibility of using laser-ultrasonic methods to detect potential defects and to track the impact of the additive manufacturing process on the quality of plastic products.

Hydrodynamic tunnel is an effective mean for studying wing flow process in aerodynamics and hydrodynamics. It allows to study flow characteristics in controlled conditions and to model the conditions that could not be studied in real flight, such as aerodynamic characteristics at critical angles of attack, in icing conditions etc. Techniques for flow visualisation such as coloured jets or small particles allow to have a qualitative data about flow behaviour, being the valuable means for understanding flow behaviour. But it is more important to have quantitative characteristics of the flow allowing to predict the process evolution and to develop safety measures and recommendations. The presented study addresses to developing a system for optical 3D measurements in hydrodynamic tunnel basing on photogrammetric techniques. To provide accurate measurements in condition of two optical media interfaces (air-glass and air-liquid) the accurate model of image formation accounting refraction is developed. The developed photogrammetric system includes several high speed cameras (from 2 to 4 cameras) mounted in a fixed position relatively the working space and a structured light projector. Original technique is applied for the system calibration. Two metrics has been used as a measure of the accuracy of the calibration: the first one being based on the test field points measurements, and the second one using points-to points distance for the surfaces of a reference object. The key contributions of this paper are: (1) accurate model of image formation in case of several media interfaces (2) a technique for photogrammetric system calibration for 3D measurements in hydrodynamic tunnel (3) experimental evaluation of calibration accuracy for multi-media 3D measurements. The performed experimental evaluation of the developed photogrammetric system has proved high accuracy of system calibration and optical 3D measurements in multi-media optical environment. The developed technique for photogrammetric system calibration and 3D measurements demonstrated applicability for the task of 3D flow analysis in hydrodynamic tunnel.

Findings from Bronze Age burials of Shengavit settlement have become a source of multiple studies referred to anthropological, and especially odontological, research based on 3d imaging and image processing techniques. The currently presented case is an example of palaeopathological analysis of bone tissue resorption caused by complications of dental pathologies. Thus by analogy with diagnostic procedures in clinical dentistry, conventional x-ray based cone-beam tomographic scanning have been applied and have shown its effectiveness as a study method. Through CBCT imaging we managed to reveal a hidden pathological process in the body of the studied semi-mandible fragment, though initially another pathological area located on the same finding was planned to be studied. Application of micro-computed tomography has improved analytical, or diagnostic, part of the current palaepathological study. It has brought to finding unusual morphological features hypothetically causing bone resorption as a complication of dental pathological conditions. However our intention to obtain 3d reconstructions as evidence supporting the most likely version required several attempts to correct image processing in line with the increase of imaging resolution.

Abstract. Studies of teeth represent a significant part of palaeoanthropological research. Over the past two decades these studies have significantly developed with implementation of high resolution imaging based on x-ray scanning techniques. Highly informative reconstructions based on image processing have provided an opportunity to study morphological layers and structures of teeth which are usually hidden under the outer layer of dental enamel. Thus micro-computed tomography of the studied teeth has been performed in order to obtain reconstructions of enamel and dentin surfaces. The material is represented by well-preserved teeth of an adolescent from Upper Palaeolithic archaeological site of Sunghir world-renowned archaeological site in Vladimir Oblast in the Russian Federation. The characteristic feature of the studied teeth is in their unusual, presumably archaic, morphology, which has been previously studied and described through measurements by application of automated digital odontometry method; however the mentioned study referred to the enamel surface. And in the current study these algorithms are applied to measure the surface of dentin. As this is the first successful attempt of measuring dentin surface morphology, the process has to be improved for complete automation. Nevertheless even currently applied approaches allow to compare enamel and dentin morphology through measurements.

The article reports on the effect the building orientation of the part, produced by laser stereolithography technology, has on achieving its best functional characteristics. Based on the example of IPLIT-3 and IPLIT-4 resins, the study shows that in contrast to the literature data on other commercial photocurable resins (PCRs), there is no definite advantage of the vertical orientation of the test samples compared to their horizontal orientation for obtaining the best values of the manufactured part functional characteristics.

The paper deals with the formation of personalized digital models of facial skeletal fragments based on computed tomography data of the patient. Precise individual three-dimensional models, surgical templates, and implant molds obtained using computer modeling and laser stereolithography were used to prepare and perform reconstructive procedures in 191 pa-tients with complex cranio-orbital defects and deformities. During the research, a special technique (“virtual pencil”) was developed, which allows you to edit halftone images of intact and damaged thin walls of the orbit. This allowed us to avoid further data processing errors when converting DICOM files into a three-dimensional model and to obtain the real geometry and correct dimensions of the defects of the damaged area. Thus, it became possible to carry out preoperative planning, modeling of individual stages of surgical intervention, manufac-turing of individual implants for the reconstruction of the skull, orbit and adjacent parts of the facial skeleton. Our experience shows that computer-aided design systems and additive tech-nologies allow us to optimize surgical treatment and increase its accuracy and efficiency.

Many anthropological researches require identification and measurement of craniometric and cephalometric landmarks which provide valuable information about the shape of a head. This information is necessary for morphometric analysis, face approximation, craniafacial identification etc. Traditional techniques use special anthropological tools to perform required measurements, identification of landmarks usually being made by an expert-anthropologist. Modern techniques of optical 3D measurements such as photogrammetry, computer tomography, laser 3D scanning provide new possibilities for acquiring accurate 2D and 3D data of high resolution, thus creating new conditions for anthropological data analysis. Traditional anthropological manual point measurements can be substituted by analysis of accurate textured 3D models, which allow to retrieve more information about studied object and easily to share data for independent analysis. The paper presents the deep learning technique for anthropological landmarks identification and accurate 3D measurements. Photogrammetric methods and their practical implementation in the automatic system for accurate digital 3D reconstruction of anthropological objects are described.

The introduction of information technologies into the practice of healthcare significantly changes the methods of diagnosis and treatment, the forms of interaction of doctors with patients and colleagues, the organization of treatment and restoration of health. Modern digital medicine makes it possible to increase the availability, quality and efficiency of medical care.The development of modern three-dimensional modeling and the introduction of a new generation of spiral computed tomographs have significantly expanded the possibilities of using these information technologies in reconstructive surgery. The performed study deals with the problems of forming the personalized digital models of anatomical structures according to patient's tomographic data. The principles of tomographic image segmentation are considered. A review and comparison of the specialized software for obtaining of digital models with the use of tomographic data is given. The evaluation of the functionality, speed and quality of the models is presented. Practical recommendations on the use of the software for creating digital models for medical applications are given. The issues of certification of personalized models and medical products are discussed.

Purpose Nowadays, cheilorhinoseptoplasty is one of the most efficient methods of cleft lip primary surgical treatment eliminating both functional and esthetic issues. In this work, we have proposed, developed, and experimentally tested a new thermography-based algorithm for studying the efficiency and symmetry of nasal breathing prior to and after the surgery. Methods To investigate and analyze the external respiration function of an infant with unilateral cleft lip after surgical respiration symmetry restoration followed by anatomically shaped postoperative endonasal retainer installation, we have applied contactless thermal imaging in real time. Results The developed algorithm enables effective analysis of the respiratory function in infants before and after the surgery. Its combination with applied surgical technique experimentally demonstrated the potential of this approach for improving further the efficiency and symmetry of the airflows through the patient's nasal passages after the primary cheilorhinoseptoplasty. Conclusions The results of our study constitute a novel and promising avenue of investigation into the breathing function in infants and young children prior to and after their surgery for unilateral cleft lip. The adaptation of our technique to the conditions of a pediatric hospital will make it a safe and informative tool for noninvasive diagnosing the respiratory function in infants in the early postoperative period.

Aircraft icing is one of the main factors decreasing the flight safety. Qualitative and quantitative understanding of the icing process is crucially needed for developing anti-icing measures and safety recommendations. Changes in aerodynamic characteristics of aircraft caused by changes in shape of aircraft surfaces due to the ice accretion can lead to significant aerodynamic performance degradation. So the reliable and accurate information of how the shape of the ice accretion influences on aerodynamic characteristics is a key point for predicting the changes in aerodynamic performance. The study addresses to a problem of accurate shape measuring of ice accretion for further experimental study of iced-aircraft aerodynamic in a hydrodynamic tunnel. For this purpose the evaluation of various techniques of ice 3D measurements is performed that include as visible so thermal imaging of ice accretion. The results of evaluation serves for the decision of preferable technique to be used in experimental study. Also the framework is developed for creating physical models of iced aircraft based on result of real ice accretion shape measurement. It allows to produce stereolithography (SLA) copies of of an aircraft under icing condition for different levels of icing. These SLA-models of an aircraft under icing condition are then used for flow behaviour study in order to identify critical flying condition.