Virtual Setup Research Articles

Integrating 3D facial scanning in a digital workflow to CAD/CAM design and fabricate complete dentures for immediate total mouth rehabilitation.

PURPOSETo integrate extra-oral facial scanning information with CAD/CAM complete dentures to immediately rehabilitate terminal dentition.MATERIALS AND METHODSTen patients with terminal dentition scheduled for total extraction and immediate denture placement were recruited for this study. The patients were submitted to a facial scanning procedure using the in-office PritiMirror scanner with bite registration records in-situ. Definitive stone cast models and bite records were subsequently submitted to a lab scanning procedure using the lab scanner (iSeries DWOS; Dental Wings). The scanned models were used to create a virtual teeth setup of a complete denture. Using the intra-oral bite records as a reference, the virtual setup was incorporated in the facial scan thereby facilitating a virtual clinical evaluation (teeth try-in) phase. After applying necessary adjustments, the virtual setup was submitted to a CAM procedure where a 5-axis industrial milling machine (M7 CNC; Darton AG General) was used to fabricate a full-milled PMMA immediate provisional prosthesis.RESULTSTotal extractions were performed, the dentures were immediately inserted, and subjective clinical fit was evaluated. The immediate provisional prostheses were inserted and clinical fit, occlusion/articulation, and esthetics were subjectively assessed; the results were deemed satisfactory. All provisional prostheses remained three months in function with no notable technical complications.CONCLUSIONTen patients with terminal dentition were treated using a complete digital approach to fabricate complete dentures using CAD/CAM technology. The proposed technique has the potential to accelerate the rehabilitation procedure starting from immediate denture to final implant-supported prosthesis leading to more predictable functional and aesthetics outcomes.

Влияние размера TCP-окна на распределение интервалов между пакетами трафика в программно-конфигурируемых сетях SDN

This work considers effect of TCP-window size on the numerical characteristics of time slots between packets. Here we researched first three initial time slot moments due to developed mathematical model utilizes them. Researches were performed on virtual experimental setup installed over physical servers by OpenNebula platform. We considered two cases including software-defined network supporting OpenFlow open protocol and conventional network without it. The first one is performed with POX controller and physical switch. Here we utilize software products tcpdump for traffic capture and Iperf for traffic generation. This work presents script providing traffic generation initiation process automation. Obtained results were imported to MS Excel. Then moment characteristics are evaluated by well-known mathematical statistics formulas.

Stiffness comparison of mushroom and straight SS and TMA lingual archwires.

BackgroundThe aim of this study is to investigate the relative stiffness of straight and mushroom lingual archwires of different diameters, cross sections and alloys, plotting their load/deflection graphs and using a modified three-point bending test.MethodsFujita’s mushroom archwires and straight lingual archwires of different diameters, cross sections and alloys were derived by a virtual set-up of an equal malocclusion and were cut at their straight distal portion. These distal portions were tested using a modified three-point bending test by an Instron 4467 dynamometer and the forces, were exerted at 1-mm deflection and were compared on each resulting load/deflection curve by means of ANOVA (p < 0.05).ResultsAll upper lingual mushroom wires exerted significantly lower forces than the straight wire. Lower mushroom archwires were stiffer than their upper counterparts, which were longer and featured inset bends. In the lower arch, similar levels of forces were recorded for the two types of wire. Load-deflection curves were higher for the straight wires, and stiffness increased proportionally with their diameter.ConclusionsThe stiffness of an archwire is a function of its diameter, length and the alloy it is made from. In lower lingual wires, there is little difference in stiffness between mushroom and straight wires, but in upper wires, the straight version is considerably stiffer. The greater bearing effect exhibited by the straight wire in the working and finishing phases makes it less susceptible to bowing effect and therefore preferable for sliding mechanics during en masse retraction, particularly in the upper arch.

Impact of (virtual) set-up errors on DVH dose results in IMRT plans for head-neck cancer

Introduction-purpose The aim of this study is to evaluate the impact of isocenter shift in three directions (lateral, longitudinal and vertical) on DVH results in IMRT plans for head and neck cancer treatment, in order to simulate possible set-up errors and its effects on treatment outcome. Materials and methods IMRT step and shoot plans for ten patients with head and neck cancer were created on the Oncentra TPS according to RTOG 0615 protocol. Three PTVs were outlined with prescribed dose of 54 Gy (PTV54), 59.4 Gy (PTV59.4) and 70 Gy (PTV70) in 33 fractions. Each treatment plan was recalculated for isocenter shift of ±3 mm in all directions. DVHs were regenerated for PTVs and critical structures for all shifted plans. Results Mean values of V51.3, V57 and V66.5 were calculated in standard plan for PTV54, PTV59.4 and PTV70 as 95.3 (SD = 1.3), 93.5 (SD = 0.9 and 95.3 (SD = 1.8) respectively. The maximum deviation n PTV70 coverage was found in the posterior direction 5% less than the standard plan value. Both PTV59.4 and PTV50 showed a decrease in coverage within a range of 4–8% either in the anterior or in the longitudinal direction. The mean D2 values calculated for spinal cord and brainstem for the standard plan were 42.0 Gy (SD = 2.1) and 42.6 Gy (SD = 2.1) respectively. The greatest deviation for shifted plans was found in the posterior direction 11% more than the standard (no shift) value. The average D50 for left and right parotids were 26.4 Gy (SD = 1.2) and 27 Gy (SD = 1.3) respectively. The greatest deviation was found reciprocally in the lateral direction 13% less than the standard plan value. Conclusion In this study, isocenter shift of ±3 mm reveals significant deviations of calculated DVH parameters. Such possible set-up errors could result in non-adequate PTV coverage and in dose values for critical structures outside of compliance criteria. These results indicate the importance of daily IGRT and subsequent patient setup correction for efficient IMRT treatment outcome.

Super Resolution from Hyperview Image Stack by Spatial Multiplexing

An image stack for a hyperview representation could contain millions of different perspective views with extreme image similarity. The recording of all views from a computational 3d model implicates a lateral displacement of the virtual camera. Because of the huge number of views, the offset in between two adjoining camera positions can be very minor. If such a virtual setup reproduces a real hyperview screen setup, the offset can be below the wavelength of the visible light. But even with such small changes, there is an intrinsic probability for a measurable difference in between two neighbour images. Such image dissimilarity can be proofed successfully also in very basic 3d scenes. By using a quantity of juxtapositional images from the hyperview image stack, the resolution of the rendered images can be considerably improved, which is commonly known as super resolution. The utilisation of super resolution images in hyperview could cut the necessity of full frame computing and will reduce the effective render time.

Investigation of the annular nozzle start in actual and virtual intermittent aerodynamic setups

The results of a numerical and experimental investigation of the starting of jet-engine annular nozzle blown with the air at room temperature and high-temperature combustion products of a stoichiometric acetylene-air mixture in an intermittent aerodynamic setup are presented. The regimes and the times of the attainment of quasi-steady stAte of the flow are studied in the virtual full-scale counterpart of the experimental setup. The special features of the starting stage and the quasi-steady flow are studied for entry channels of different shapes. The values of starting times, the pressures at different points of the flow duct, and the thrusts produced by the annular nozzle measured in the physical experiment and obtained in the virtual experimental setup are compared.

Children With Dystonia Can Learn a Novel Motor Skill: Strategies That are Tolerant to High Variability.

Children with dystonia are characterized by highly variable and seemingly uncontrolled movements. An important question for any rehabilitative effort is whether these children can learn and improve their performance. This study compared children with dystonia due to cerebral palsy, typically developing children, and healthy adults in their ability to acquire a novel sensorimotor skill. Using a virtual setup, subjects threw a virtual ball tethered to a post to hit a virtual target. Multiple combinations of release angle and velocity of the arm at ball release could achieve a target hit-the task was redundant and afforded solutions with different sensitivity to variability. Subjects performed 200 trials for two target locations that presented different types of redundancy. We hypothesized that children with dystonia develop strategies that are tolerant to their high variability. Estimating this variability highlighted the insufficiency of traditional outcome measures. Therefore, additional analyses of data distributions and of ball release timing were applied. Results showed that: 1) children with dystonia reduced their performance error despite their high variability; 2) this improvement was brought about by finding error-tolerant solutions; and 3) they generated arm trajectories that created time windows for ball release that were tolerant to timing variability. While reduced in magnitude, the performance improvements in children with dystonia paralleled those in healthy children and adults. These findings demonstrate that children with dystonia are able to adapt their behavior to their high variability, an important basis for any rehabilitative intervention.

Generation and stabilization of detonation in a plane elbowed channel

The problem of detonation initiation in a supersonic flow of a stoichiometric propane-air mixture in a plane elbowed channel of constant width is considered. In the bend zone the channel walls are made in the shape of circles of given radii, whose lengths are determined by the given angle of the channel turn. An investigation is performed within the framework of the single-stage combustion kinetics using a numerical method based on the Godunov scheme and included in an original program complex, or a “virtual experimental setup”, developed for performing multiparameter calculations and flow visualization. The critical conditions of detonation generation are determined as functions of the oncoming flow velocity, the channel turn angle and width, and the radii of curvature of the walls.

Digital templating for THA: a simple computer-assisted application for complex hip arthritis cases.

Total hip arthroplasty (THA) is the standard procedure for end-stage arthritis of the hip. Its technical success relies on preoperative planning of the surgical procedure and virtual setup of the operative performance. Digital hip templating is one methodology of preoperative planning for THA which requires a digital preoperative radiograph and a computer with special software. This is a prospective study involving 23 patients (25 hips) who were candidates for complex THA surgery (unilateral or bilateral). Digital templating is done by radiographic assessment using radiographic magnification correction, leg length discrepancy and correction measurements, acetabular component and femoral component templating as well as neck resection measurement. The overall accuracy for templating the stem implant's exact size is 81%. This percentage increased to 94% when considering sizing within 1 size. Digital templating has proven effective, reliable and essential technique for preoperative planning and accurate prediction of THA sizing and alignment.

Lack of depth constancy for grasping movements in both virtual and real environments.

Recent studies on visuomotor processes using virtual setups have suggested that actions are affected by similar biases as perceptual tasks. In particular, a strong lack of depth constancy is revealed, resembling biases in perceptual estimates of relative depth. With this study we aim to understand whether these findings are mostly caused by a lack of metric accuracy of the visuomotor system or by the limited cues provided by the use of virtual reality. We addressed this issue by comparing grasping movements towards a spherical object located at four distances (420, 450, 480, and 510 mm) performed in three conditions: 1) virtual, in which the target was a virtual object defined by binocular cues, 2) glow-in-the-dark, in which the object was painted with luminous paint but no other cue was provided, and 3) full-cue, in which the movement was performed with the lights on and all the environmental information was available. Results revealed a striking effect of object distance on grip aperture equally in all three conditions. Specifically, grip aperture gradually decreased with increase in object distance, proving a consistent lack of depth constancy. These findings clearly demonstrate that systematic biases in grasping actions are not induced by the use of virtual environments and that action and perception may involve the same visual information, which does not engage a metric reconstruction of the scene.

Virtual smile design systems: a current review.

In the age of digital dentistry, virtual treatment planning is becoming an increasingly important element of dental practice. Thanks to new technological advances in the computer- assisted design and computer-assisted manufacturing (CAD/CAM) of dental restorations, predictable interdisciplinary treatment using the backward planning approach appears useful and feasible. Today, a virtual smile design can be used as the basis for creating an esthetic virtual setup of the desired final result. The virtual setup, in turn, is used to plan further treatment steps in an interdisciplinary team approach, and communicate the results to the patient. The smile design concept and the esthetic analyses required for it are described in this article. We include not only a step-by-step description of the virtual smile design workflow, but also describe and compare the several available smile design options and systems. Subsequently, a brief discussion of the advantages and limitations of virtual smile design is followed by a section on different ways to integrate a two-dimensional (2D) smile design into the digital three-dimensional (3D) workflow. New technological developments are also described, such as the integration of smile designs in digital face scans, and 3D diagnostic follow-up using intraoral scanners.

A Virtual Environment for Simulation of Formation Flight

This paper presents the design of Unmanned Aerial Vehicles (UAVs) formation flight control laws and then the virtual Environment setup of a nice structure for close formation flight. The images of the target airplane projected on the video-camera plane of the follower airplane are captured and processed into vision information The simulation setup includes airplane dynamics, autopilots and formation keeping controller and module that creates virtual environment for the simulation of the vision software called Unity3D. The UKF is applied to the relative motion estimator due to the highly nonlinear characteristics of the problem.

Integrated three-dimensional digital assessment of accuracy of anterior tooth movement using clear aligners

ObjectiveTo assess the accuracy of anterior tooth movement using clear aligners in integrated three-dimensional digital models.MethodsCone-beam computed tomography was performed before and after treatment with clear aligners in 32 patients. Plaster casts were laser-scanned for virtual setup and aligner fabrication. Differences in predicted and achieved root and crown positions of anterior teeth were compared on superimposed maxillofacial digital images and virtual models and analyzed by Student's t-test.ResultsThe mean discrepancies in maxillary and mandibular crown positions were 0.376 ± 0.041 mm and 0.398 ± 0.037 mm, respectively. Maxillary and mandibular root positions differed by 2.062 ± 0.128 mm and 1.941 ± 0.154 mm, respectively.ConclusionsCrowns but not roots of anterior teeth can be moved to designated positions using clear aligners, because these appliances cause tooth movement by tilting motion.

Rhythmic manipulation of objects with complex dynamics: predictability over chaos.

The study of object manipulation has been largely confined to discrete tasks, where accuracy, mechanical effort, or smoothness were examined to explain subjects' preferred movements. This study investigated a rhythmic manipulation task, which involved continuous interaction with a nonlinear object that led to unpredictable object behavior. Using a simplified virtual version of the task of carrying a cup of coffee, we studied how this unpredictable object behavior affected the selected strategies. The experiment was conducted in a virtual set-up, where subjects moved a cup with a ball inside, modeled by cart-and-pendulum dynamics. Inverse dynamics calculations of the system showed that performing the task with different amplitudes and relative phases required different force profiles and rendered the object's dynamics with different degrees of predictability (quantified by Mutual Information between the applied force and the cup kinematics and its sensitivity). Subjects (n = 8) oscillated the virtual cup between two targets via a robotic manipulandum, paced by a metronome at 1 Hz for 50 trials, each lasting 45 s. They were free to choose their movement amplitude and relative phase between the ball and cup. Experimental results showed that subjects increased their movement amplitudes, which rendered the interactions with the object more predictable and with lower sensitivity to the execution variables. These solutions were associated with higher average exerted force and lower object smoothness, contradicting common expectations from studies on discrete object manipulation and unrestrained movements. Instead, the findings showed that humans selected strategies with higher predictability of interaction dynamics. This finding expressed that humans seek movement strategies where force and kinematics synchronize to repeatable patterns that may require less sensorimotor information processing.

Early problems identification in collaborative engineering with different product data modelling standards

Since activities during collaborative projects in global engineering teams depend greatly on efficient exchange of current and accurate data, establishing procedures for successful data exchange is needed for effective product design and realisation projects. The work found in this study benefits a collaborative engineering strategy for testing available software applications, and their neutral exchange file types, which will be used in a bigger project among stakeholders in the product design or manufacturing phase. A collaborative methodology for future larger scale projects that would be done with a team, who has access to different software, has been tested on a smaller example in this study using a cordless hand drill reverse engineering project. This research aimed to establish a model for the start-up and testing of a virtual collaborative tool set-up for a future engineering collaboration on product design and realisation projects. A real case study was considered in this project to simulate a real situation, not uncommon for modern design and manufacturing projects, especially while collaborators are from mid-sized companies and working for a larger supplier. The proposed approach is a possible solution to accelerate the identification of possible problems in data conversion as early as in the design phase.

Comparison of virtual and manual tooth setups with digital and plaster models in extraction cases

The aim of this study was to compare the virtual and manual tooth setups with digital and plaster models in extraction cases by measuring various occlusal parameters and applying the American Board of Orthodontics objective grading system. Linear intra-arch and interarch dimensions (arch width and length, perimeter, overjet, and overbite), angular variables (tip, torque, and rotation), and American Board of Orthodontics objective grading system scores obtained from a digital virtual setup model were compared with those from a plaster model setup. The digital virtual setup model resulted in smaller arch perimeters than did the plaster setup model by 2.20 mm in the maxillary arch (P<0.01) and 1.30 mm in the mandibular arch (P<0.05). The digital virtual setup also exhibited significantly lower values for overbite and overjet (P<0.01). The digital virtual setup had tendencies toward mesial angulation of the anterior teeth, labial inclination of the maxillary anterior teeth (P<0.05), and distal in-rotation of the mandibular teeth (P<0.05). The resulting American Board of Orthodontics objective grading system evaluation showed that larger deductions for overjet, occlusal contact, and total score (P<0.01) were required for the digital than for the manual setup model. Digital and manual setups lead to similar measurements for intra-arch and interarch occlusal variables. However, because of the possibility of collision on proximal and occlusal contact, delicate adjustments in proximal and occlusal contacts are required.

Current Orthodontic Treatment using CAD/CAM technology: from orthodontic diagnosis to indirect bonding procedure

Computerized 3D virtual dental models are currently available, and their use has started to improve treatment outcomes. The accuracy of digital models has been demonstrated by many studies and various intra-oral scanners are innovated for short scanning time and high precision. Recently, a digital model was combined with a high technology computer-driven system, which was developed for the application of a digital set-up and indirect bonding of lingual attachments. In this section, virtual treatment planning using a virtual set-up program is be introduced, and the clinical applications and accuracy of computer-generated indirect bonding are discussed.

Innovative virtual set-up to evaluate arch form effects

Innovative virtual set-up to evaluate arch form effects

Fatigue mitigation through the optimization of ergonomic positional parameters in massage therapy using virtual instrumentation

This paper reports a research in which a setup was developed to determine the optimal values of ergonomic positional parameters that would mitigate the development of fatigue while performing massage therapy. This setup was based on virtual instrumentation principles and consisted of a sphygmomanometer bulb, an air sac, a pressure sensor, a data acquisition card and a personal computer installed with the Laboratory Virtual Instrumentation Engineers Workbench software (LABView software). The air sac fitted in this setup is equalised with the muscles and other human body parts which a human therapist is required to press while performing massage therapy. After constructing the air sac fatigue monitoring virtual instrumentation setup, 25 participants who were not actually massage therapists were asked to press the air sac to mimic the behaviour of the massage therapists during the time of their works. After drawing necessary data by performing this activity and by entering the data in Minitab 16 software, regression models to specify optimal values of ergonomic positional parameters were developed. These regression models were practically validated by conducting experiments involving five other participants. The method of utilizing these regression models in determining the optimum values of positional parameters that would mitigate fatigue development while performing massage therapy is illustrated by presenting two cases. While concluding, it is suggested to involve actual massage therapists for testing the performance of the fatigue monitoring virtual instrumentation setup developed during the research reported in this paper.

Pymote: High Level Python Library for Event-Based Simulation and Evaluation of Distributed Algorithms

In recent years we have witnessed strong development and widespread use of powerful wirelessly connected platforms, thus the set of the related problems that need to be solved by distributed algorithms is growing rapidly. Some of them present large obstacles in harnessing the full potential of this new technology, so there is an imminent need for a fast and easy evaluation of new ideas and approaches. Simulation is a fundamental part of distributed algorithm design and evaluation process. In this paper, we present a library for event-based simulation and evaluation of distributed algorithms. This library provides a set of simple but powerful tools with a goal to ease virtual setup of a complex system such as a distributed network of communicating entities and to define, simulate, and analyze its behavior. In order to reduce a huge problem space inherent in such systems, our library is using a high level of abstraction. This is made possible by a strict and complete definition of the distributed computing environment. The library is implemented in Python whose simple and expressive syntax provides a possibility of minimal implementations and a mild learning curve. In addition to executing automated simulations or larger experiments, the library fully supports interactive mode along with a step-by-step execution, which can be a very powerful combination.