Virtual Three-dimensional Images Research Articles

Dipole source-based virtual three-dimensional imaging for propeller noise

The increasing attention to aerodynamic noise radiation from propellers has driven the interest in noise source identification and promoted the development of urban aerial vehicles over the last decades. Conventional acoustic imaging algorithms primarily assume monopole-type sources, but modern aeroacoustic theories have recognized that the dipole-type loading noise is dominant for propellers. To obtain physically consistent noise source distributions, we propose a moving dipole source-based beamforming method. The method is developed in the time-frequency domain to recover the time history of three-dimensional mapping for source strength and directivity, different to other techniques. The capability of the proposed method to identify noise sources is assessed by considering a two-bladed propeller benchmark. Instead of directly conducting experiments, we use results from high-fidelity numerical simulations, validated by measurements, to perform a noise source analysis. In this way, it is easier to verify the obtained source locations and directions. The results show that the noise sources are located on the trailing edge around the tip of the propeller, and the directivity varies with frequency. The proposed method exhibits competitive advantages in correctly tracing sources over conventional monopole-based methods. The proposed method can recover the three-dimensional noise sources for a high-speed rotating propeller. The consistency between the flow field and acoustic imaging results confirms the accuracy of the proposed method and suggests its potential in industrial applications.

The Size of the Visual Feedback-Providing Object Affects the Vertical Posture Maintenance in Humans

Of all information that permits a person to elaborate an idea about the spatial position of their body, visual signals about the structures and sizes of visible objects in the surrounding play an important role. A study was made to find out how a change in the size of an object in the field of vision affects the stability of standing in healthy people. Subjects stood in stereo glasses and a mask that limited the field of vision in a darkened room in front of a screen (silver screen, 2 × 1.5 m), and a three-dimensional image of a dark gray sphere was projected on the screen. The subjects saw only the virtual three-dimensional image of the sphere in these conditions. Four sphere sizes with diameters of 8.75, 17.5, 35, and 70 cm were used. Spheres with these sizes covered visual fields of 4.5, 9, 18, and 36 degrees, respectively. The sphere was motionless in control conditions, while displacements of the sphere in the anteroposterior and lateral directions were in phase or out of phase with oscillations of the body’s center of gravity (CoG) in test conditions. The amplitude of sphere oscillations was twice as high as the amplitude of CoG oscillations. The subjects performed 36 tests of 40 s each; the instruction was to calmly stay on a stabilographic platform and to look at the sphere. The tests were grouped into four blocks, each including three control tests with the immobile sphere and six tests with the sphere moving in phase or out of phase with CoG oscillations. The interval between tests was 1 min. The sphere had the same size in all tests of a block. After each block, the subject rested in a sitting position for 4–5 min. Blocks with different sphere sizes were performed in a random order. The amplitude-frequency characteristics of two elementary variables were calculated from the trajectories that the center of pressure (CoP) of the feet showed in the anteroposterior and lateral directions. The variables were the trajectory of the CoG projection on the support (CoG variable) and the difference between the CoP and CoG trajectories. Sphere displacements destabilized the vertical posture in the test conditions. Destabilization increased with the increasing sphere size. Quality of standing worsened because of the changes in both amplitude and frequency characteristics of the CoG and CoP–CoG variables. An increase in sphere size exerted an opposite effect in control tests; i.e., body oscillations decreased. Changes in the stability of the vertical posture with increasing size of the sphere were presumably associated with the peculiarities of using visual information that comes from the central and peripheral fields of view.

Usefulness of virtual three-dimensional image analysis in inguinal hernia as an educational tool.

The pre-operative three-dimensional (3D) imaging technique has resulted in a better surgical outcome for patients and has been used as an education and diagnostic tool. However, there are no reports concerning the usefulness of the 3D imaging technique in laparoscopic transabdominal pre-peritoneal repair (TAPP) so the aim of this study was to investigate the usefulness of the 3D imaging technique in laparoscopic TAPP as an educational tool for medical students. Six (6) patients who underwent laparoscopic TAPP for inguinal hernia were enrolled in this study. 3D reconstruction was performed from pre-operative computed tomography (CT) and the usefulness of pre-operative 3D simulation compared with intra-operative laparoscopic imaging was validated. Moreover, thirty (30) medical students at the university completed a multiple-choice questionnaire (MCQ) to determine the level of their satisfaction and understanding of anatomy resulting from the study. The local anatomy of the patients was identified as the same during the operation as the pre-operative 3D simulation. The results of the MCQ showed that most of the medical students were extremely (23%) or very (67%) satisfied with the effect of pre-operative 3D simulation on the quality of the surgery. Moreover, most students could understand the surgery anatomy by the 3D simulation extremely well (40%) or very well (47%) and agreed on the usefulness of this procedure for learning anatomy. Pre-operative 3D simulation increases the understanding of detailed anatomy and virtual three-dimensional image analysis in laparoscopic TAPP is useful as an educational tool for medical students.

Utility of virtual three-dimensional image analysis for laparoscopic gastrectomy conducted by trainee surgeons.

Purpose The aim of this study was to investigate the utility the three-dimensional (3D) imaging for laparoscopic gastrectomy performed by trainee surgeons. Methods 3D-reconstruction was performed using multi-detector computed tomography (MDCT) and SYNAPSE VINCENT software. Trainee surgeons made 3D-imaging and checked the anatomical structure. Thirty-three patients who underwent laparoscopic gastrectomy (LG) for gastric cancer were examined. Trainees performed 19 LG, while specialists performed 14 LG. The vascular pattern and the surgical outcomes were evaluated. Result 3D imaging depicted the correct positional relationship between the gastric vasculatures and the organs. Regarding vascular pattern detected by 3D imaging, the origins of the infrapyloric artery were the right gastroepiploic artery in 12 cases (36%), the gastroduodenal artery in eight cases (24%), the bifurcation of the right gastroepiploic artery and gastroduodenal artery in seven cases (21%), and not detected in one case (3%). The types of confluence of the infrapyloric vein were the right gastroepiploic vein in 16 cases (48%), the anterior superior pancreatoduodenal vein in 10 cases (30%), and not detected in seven cases (21%). Surgical outcomes were not different between trainee group using intraoperative 3D image with the specialist in instruction group without the intraoperative 3D image. Conclusions Preoperative 3D imaging might contribute to successful and safe LG by trainee surgeons. J. Med. Invest. 66 : 280-284, August, 2019.

Optical see-through holographic near-eye-display with eyebox steering and depth of field control.

We propose an optical see-through holographic near-eye-display that can control the depth of field of individual virtual three-dimensional image and replicate the eyebox with dynamic steering. For optical see-through capability and eyebox duplication, a holographic optical element is used as an optical combiner where it functions as multiplexed tilted concave mirrors forming multiple copies of the eyebox. For depth of field control and eyebox steering, computer generated holograms of three-dimensional objects are synthesized with different ranges of angular spectrum. In optical experiment, it has been confirmed that the proposed system can present always-focused images with large depth of field and three-dimensional images at different distances with shallow depth of field at the same time without any time-multiplexing.

Additive Manufacturing for Surgical Planning of Mandibular Fracture.

Currently, imaging techniques such as Computed Tomography with three-dimensional reconstruction (3D) and Magnetic Resonances are being routinely used in pre-surgical planning in all fields of medicine. Nowadays, virtual three-dimensional images, commonly displayed on two-dimensional surfaces, such as the computer screen, can be used to produce rapidly prototyped models, with excellent dimensional accuracy and fine reproduction of anatomical structures, providing professionals with the ability to use the biomodel in planning and simulating medical and dental procedures (oral and maxillofacial surgery, making individualized facial implants and prostheses, measurements and previous adaptations of prefabricated fixation plates), thus contributing to considerable reductions in surgical time and consequently the duration of anesthesia, minimizing infection risks and reducing hospital costs. In this report, we describe a case of surgical planning and treatment of bilateral atrophic mandibular fracture, in which, for surgical planning, authors used Rapid Prototyping as an adjunct tool, considering the advantages already outlined.

Research and Implementation of Three-Dimensional Power Lines Selection System Based on Aerial Images

Based on the application of aerial images processing technology and 3D visualization technology, this paper used a series of procedures including aerial images procession, DEM generation, three-dimensional tower modeling and images recombination, and adopted VB + VRML to generate virtual three-dimensional images animation of the study area according to certain scale and flight routes, this three-dimensional power lines selection system provides the designers the most direct information to grasp the route of the transmission lines from the macro perspective.

음성녹음 기반의 실감형 어학시스템 콘텐츠 개발

기존의 어학시스템 콘텐츠의 문제점은 수업에 대한 집중력 저하와 실제 학습여부를 판단할 수 없었고, 수업 진행자의 평가로 많은 결정이 되었다. 이로 인해 음성녹음 기반에 유비쿼터스 기술과 가상현실 기술을 조합하여 강의실에 프로젝터를 설치하고 각 강의실의 RFID 리더기 부착과 학생의 RFID 태그 부착된 학생증을 통해 영어 등급에 해당하는 콘텐츠를 학습한다. 3차원 영상 콘텐츠로 가상 현실상의 외국인과의 질의응답을 음성녹음 기술을 이용하여 발음과 억양을 동시에 체크 하여 레벨 패스 또는 레벨 실패를 판가름 한다. 이렇게 구성된 시스템은 학생 교육 데이터를 중앙 서버에 DB로 저장후 피드백 과정을 통해 정보를 제공하게 된다. 본 연구로 어학 콘텐츠에서 공통적으로 가질 수 있는 문제점들을 분석하고 문제점에 대하여 음성 녹음기술을 적용하여 기존의 어학콘텐츠에서 해결하지 못했던 문제점을 해결하였고 레벨위주의 수업이 가능하였다. 또한, 흥미위주의 적극적인 수업참여가 되도록 기여하였다. Learning a lesson about poor concentration and problems of the existing content, the system of language which could not be determined, Many teachers' assessment decision was made. As a result, voice recording based on the combination of ubiquitous technology and virtual reality technology, and install the projector in a classroom Through the learning content corresponding grade English student ID card attached RFID reader in each classroom, and students of RFID tags attached. In reality of the virtual three-dimensional image content foreigners and question-and-answer using the voice recording technology at the same time check the pronunciation and intonation level passes or level failure judged. Student education data to a central server system is configured to do so after saving to the DB through a feedback process, which provides information. Analysis of the issues that can have a common language content in the present study and Problem for voice recording technology to solve the problem and did not solve the existing language in the content level based classes.

Design and Implementation of a Self-Directed Stereochemistry Lesson Using Embedded Virtual Three-Dimensional Images in a Portable Document Format

A novel stereochemistry lesson was prepared that incorporated both handheld molecular models and embedded virtual three-dimensional (3D) images. The images are fully interactive and eye-catching for the students; methods for preparing 3D molecular images in Adobe Acrobat are included. The lesson was designed and implemented to showcase the 3D virtual images and determine whether the use of virtual 3D images should be permanently included with the stereochemistry lesson. A group of students completed the lesson and provided positive feedback on the incorporation of the embedded virtual 3D images.

Digital pathology: exploring its applications in diagnostic surgical pathology practice

There has been a recent upsurge in worldwide attention on digital pathology, which has transformed from static snapshots from camera-equipped microscopes to its modern form that encompasses scanning of whole glass slides with evaluation of histological images on a computer screen, along with management of its accompanying information. Although it has been widely accepted in education and research, its implementation in diagnostic surgical pathology practice is not without challenges in workflow integration, technological infrastructure, pathologist acclimatisation, global standardisation for clinical practice, and cost issues, among others. Nonetheless, early adopters have harnessed its benefits in specific niches, like frozen section services and remote second opinion consultations. Its tremendous potential is worthy of further validation to compare with conventional glass slide evaluation, even while it is already paving the way for advancement into virtual three-dimensional imaging technology, with a glimpse into a possible future digital diagnostic pathology practice.

Successful Duct-to-duct Biliary Reconstruction after Right Hemihepatectomy. Operative Planning Using Virtual 3D Reconstructed Images

Accurate knowledge of partial anatomy is essential in hepatic surgery but is difficult to acquire. We describe the potential impact of a new technique for constructing three-dimensional virtual images of the portal vein, hepatic artery, and bile ducts and present a representative case. An 80-year-old man was suspected of having papillary cholangiocarcinoma arising in S8 of the liver and extending to the hepatic hilum intraluminaly. Right hemihepatectomy with bile duct resection was planned. However, it was uncertain whether duct-to-duct biliary reconstruction would be possible based on the appearance of the confluence of the right and left hepatic ducts on cholangiogram and conventional computed tomograph. Virtual three-dimensional images of the liver were constructed and revealed vascular and biliary anatomy. They showed that the upper margin of bile duct excision would be 19 mm from the umbilical point of the left portal vein, and that the site of the left branch of the caudate lobe bile duct could be preserved. Based on this information, we performed a sphincter-preserving biliary operation safely without complications. Planning complex biliary surgery may be improved by the use of virtual three-dimensional images of the liver. This approach is especially useful in candidates for postoperative regional chemotherapy.

Do-it-yourself holography

If an object is illuminated by a coherent, monochromatic light source such as a laser, it is possible to record an interference pattern produced by light scattered from the object on a photographic film placed close to the object. No camera is necessary, and if the developed plate (hologram) is viewed in the laser beam, a virtual three-dimensional image of the object is seen through it.The article describes a simple experimental arrangement for obtaining a hologram provided a laser is available, the lower power type used for lecture-room demonstrations being suitable.Results are shown together with an elementary treatment of the wave superposition and photographic processes.