Smooth Anatomical Models From 3D Imaging

The primary objective of this numerical study is to provide a finite element (FE) analysis approach for segmental structures. The study was conducted using a hollow circular segmental structure model capable of adequately imitating real structural behavior and deals with the effect of varying number of segments on structural performance. In order to verify the FE procedure conducted by DIANA software, comparisons are made with the acquired numerical results and the results taken from previous experimental studies for 1 reinforced concrete (RC) beam, 2 post-tensioned (PT) beam, and 3 segmental post-tensioned beams (SPT). For the considered cases, 1D line, 2D shell, and 3D solid FE models are made, and it is found out that the 3D solid model with interface elements yields the most plausible results. Further, the FE model was constructed to accurately predict segment joint behavior concerning the relationship between the number of segments, concrete compressive strength, and the width of the openings at the segment joints up to collapse. In this study, a hollow circular segmental structure model is utilized to mimic real structural behavior, presenting a novel perspective on internal force transfer mechanisms within segmental structures. Moreover, the FE model is tailored to accurately predict segment joint behavior, elucidating the intricate relationship between the number of segments, concrete compressive strength, and the width of openings at segment joints up to collapse. In addition to presenting a robust numerical analysis framework, this study contributes novel insights into the complex interplay between segmental geometry, material properties, and structural behavior, thus advancing the state-of-the-art in segmental structural design. Thus, a modular construction methodology is proposed for segmental beam type structures ensuring safety, efficiency, and flexibility in challenging load conditions.

Reverse innovative design — an integrated product design methodology

In this paper intelligent technology of 3D complicated surface scanning measurement which is associated with typical problems for the cutting tool groove measurement is discussed and some special algorithm are introduced. The 3-D scanning system can be used not only to input the parameters of solid model for tool CAD/CAM system and as a constitutions of the measurement geometry modelling system which is useful to the design and copy of tool groove but also to measure machining error of mould of the cutting tool. The experimental results show that the measuring precision of the system is up to the design requirements.

Effective mass of robot is considered of great significance in enhancing the safety of human-robot collaboration. In this paper, the effective mass of the robot is investigated using different joint configurations. This investigation is executed in two steps. In the first step, the position of each joint of the robot is changing alone, whereas the positions of the other joints of the robot are fixed and then the effective mass is determined. In the second step, the positions of all joints of the robot are changing together, and the effective mass of the robot is determined. From this process, the relation between the effective mass of the robot and the joint configurations can be presented. This analysis is implemented in MATLAB and using two collaborative robots; the first one is UR10e robot which is a 6-DOF robot and the second one is KUKA LBR iiwa 7 R800 robot which is a 7-DOF robot. The results from this simulation prove that the change in any joint position of the robot except the first and the last joint affect the effective mass of the robot. In addition, the change in all joints’ positions of the robot affect the effective mass. Effective mass can thus be considered as one of the criteria in optimizing the robot kinematics and configuration.

High powered computing hardware, software, and sophisticated computer-based sensing and control has migrated from the factory and entered the cloud and the home. We have become comfortable with computers, software applications, and computer-driven machines as they now exist in our homes in many forms ranging from smart phones to remote controlled toys. We now have access to low cost 3D printers in the studio, or down the street, and access to larger commercial machines over the Internet. It is useful to understand what the building blocks of these machines are and how they fit together to best choose AM metal printing capability. In this chapter, we discuss the range and capabilities of 3D solid model software, 3D scanners, and computer-aided design (CAD) that support AM. In addition, we introduce and discuss computer-aided engineering (CAE), computer-aided manufacturing (CAM), computer numerical control (CNC), and motion systems. Most importantly, we focus on the aspects of these technologies as applied to AM metals. You will be introduced to the STL or Stereolithography file format, originally developed for rapid prototyping of polymer materials and plastics, offering a simple solution to computer-defined surface geometry. The evolving need for interoperability and cross platform independence is discussed as well as the development of the 3MF file format.

Test and simulation of corroded high strength steel wires: From scanned morphology feature to mechanical degradation

Tree risk assessment requires mechanical response studies, but simplification of the shape, material, or boundary conditions is necessary when dealing with such complex structures. To observe overall tree response, sub-structuring to several levels of detail can be used, enabled by recent developments in numerical methods and three-dimensional laser scanning (3D scan). This study aimed to determine an appropriate level of geometry and loading simplification allowed for high-order branches at the crown border, which is useful for the mechanical analysis of structured tree models. Four higher-order branches were pruned and experimentally tested by single-point loading. Beam and solid finite-element models (FEMs) were created based on measured geometric parameters and detailed 3D scans, respectively. The FEMs were used to analyze seven loading scenarios with force applied at (a) the center of gravity, (b) the top of side branches, (c) key discrete points, and (d) uniformly to the whole volume (to each finite element). Force was distributed by ratios weighted according to the mass, area, and diameter of side branches; or according to the mass of each finite element. The results showed no significant difference between the beam model and 3D scan-based model. The scenarios with finite elements’ mass-based force distribution deviated significantly from those of the other scenarios. The most simplified single-point loading caused a deviation in the deflection curve. The deviation of single-point loading in the case of the bending moment was related to force distribution ratios given by the branches architecture. Therefore, such loading simplification is not considered always appropriate. Consistency between the bending moment and branch deflection provided a representative mechanical response, recommended for further modeling of trees by sub-structuring.

To determine the maximum loads acting in the rear air suspension of a truck at the early stages of design there was used computer modeling based on solving equations of dynamics of solids and implemented in the Recurdyn software. The components of the developed virtual test bench, including hinges, power connections, drive axles, a wheel-hub assembly with a wheel and a support platform, are considered in detail. The test bench is controlled using a mathematical model created in the environment for calculating the dynamics of rigid bodies and associated with a solid suspension model by standard software tools of the application. The test bench is controlled using a mathematical model created in the environment for calculating the dynamics of rigid bodies and associated with a solid suspension model by standard software tools of the application. The use of such a test bench makes it possible to determine the loads in the hinges and power connections of the suspension, to determine the mutual positions of the links for each load mode, to increase the accuracy of the calculation of loads in comparison with the flat kinematic and force calculation. The mathematical model of the virtual test bench allows to carry out numerous parametric studies of the suspension without the involvement of expensive full-scale prototypes. This makes it possible at the early stages of design to determine all hazardous modes, select rational parameters of the elements, and reduce design costs. The paper shows the results of modeling the operation of a virtual test bench with an air suspension in the most typical loading modes, identifying the most dangerous modes. The efficiency and adequacy of the mathematical model of the suspension was proved. Examples of determining the force in all the joints of the structure, the choice of maximum loads for design calculations when designing the air suspension of vehicle were shown.

Prosthetic devices remain unaffordable to many patients in resource-constrained environments. The design process of personalized prosthetic devices is sophisticated and requires specialized equipment and trained professionals who may have limited availability. The situation is further exacerbated by the fact that the resources are frequently situated away from underserved communities, compounding the issue of accessibility. Lowering the barriers to accessing required equipment and minimizing the involvement of trained professionals in designing and manufacturing prosthetic devices can potentially minimize the required visits to the prosthetists and lower the associated costs. Traditional prosthetic and orthotic device creation methods can take up to several months. There are attempts to leverage advanced technologies to enhance the design process, but they require special equipment such as 3D scanners and MRI equipment in addition to the active involvement of specialists. This work proposes a computer vision method for creating a virtual model of the affected human limb. We also propose an automated approach for generating the socket from the virtual model and scaling other parts of the prosthetic device. The prosthetic device designed through the proposed process is realized via a 3D printer. We present a case study demonstrating the feasibility of our approach, using a mobile phone and open-source software to reconstruct a virtual representation of an upper limb and customize a prosthetic hand with minimal input from a specialist.

As 3D digital photographic and scanning devices produce higher resolution images, acquired geometric data sets grow more complex in terms of the modeled objects’ size, geometry, and topology. As a consequence, point-sampled geometry is becoming ubiquitous in graphics and geometric information processing, and poses new challenges which have not been fully resolved by the state-of-art graphical techniques. In this paper, we address the challenges by proposing a meshless computational framework for dynamic modeling and simulation of solids and thin-shells represented as point samples. Our meshless framework can directly compute the elastic deformation and fracture propagation for any scanned point geometry, without the need of converting them to polygonal meshes or higher order spline representations. We address the necessary computational techniques, such as Moving Least Squares, Hierarchical Discretization, and Modal Warping, to effectively and efficiently compute the physical simulation in real-time. This meshless computational framework aims to bridge the gap between the point-sampled geometry with physics-based modeling and simulation governed by partial differential equations.

The analysis, measuring, and recording of anatomical structures by means of dissection and other destructive techniques introduces inaccuracies due to the risk of damaging the original organization of a body's tissues. More so than other tissues, thin connective tissues are especially susceptible to breakage and distortions. MRI is the method of choice for visualizing and identifying connective tissue structures in 3D without the need for contrast staining, which dehydrates and shrinks soft tissues. The visualization of MRI data, however, comes with their own challenges because optimizing image resolution as well as contrast resolution in a particular data set generally results in non‐cubic voxels. Optimizing image resolution requires minimizing pixel size in the viewing plane, whereas optimizing contrast resolution among pixels in the viewing plane requires maximizing the number of hydrogen atoms and, hence, the voxel volume for a more accurate statistical summation of relaxing hydrogen atoms. The latter would create a non‐cubic voxel with a greater depth than the side length of the pixel in the viewing plane. Non‐cubic voxels, however, present a special challenge for building realistic 3D models based on MRI data, in particular for complexly configured thin connective tissue structures that are thinner than a voxel and, therefore, may not be discriminated from the surrounding tissue along their entire course. Recursive segmentation is a technique that allows the reconstruction of such structures in their entirety by using more than one MRI scan of the same specimen in the same position. While most segmentation can usually be done from 3D MRI scans, some portions of the structure may not have enough contrast resolution to be identified because of the almost cubic voxels. For such a portion, its segmentation from a 2D MRI scan with greater contrast resolution in the viewing plane, although lower image resolution in the planes perpendicular to the viewing plane, can serve as a scaffold for guiding the segmentation of the portion that is invisible in the 3D MRI scan. This technique allows the reconstruction of a realistic (“realitätsgetreues”) 3D model of the entire structure. The recursive technique requires skill and anatomical knowledge of the structures to be segmented by the operator and, therefore, needed to be tested as to its efficacy, reliability, and reproducibility even when used by different operators, some of whom may be less familiar with the anatomy of the structures and the segmentation software. By having a novice operator who is unfamiliar with the anatomy of lampreys execute the segmentation of myosepta with and without the help of the recursive technique, we were able to demonstrate that recursive segmentation using both 2D and 3D MRI data sets is essential to creating accurate and realistic 3D models of thin connective tissue structures. Realistic 3D models of myosepta of lampreys and other piscine vertebrates are necessary prerequisites for an elucidation of the biomechanics underlying undulatory swimming behavior.Support or Funding InformationLSU FoundationThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Repeated brain MRI scans are performed in many clinical scenarios, such as follow up of patients with tumors and therapy response assessment. In this paper, the authors show an approach to utilize former scans of the patient for the acceleration of repeated MRI scans. The proposed approach utilizes the possible similarity of the repeated scans in longitudinal MRI studies. Since similarity is not guaranteed, sampling and reconstruction are adjusted during acquisition to match the actual similarity between the scans. The baseline MR scan is utilized both in the sampling stage, via adaptive sampling, and in the reconstruction stage, with weighted reconstruction. In adaptive sampling, k-space sampling locations are optimized during acquisition. Weighted reconstruction uses the locations of the nonzero coefficients in the sparse domains as a prior in the recovery process. The approach was tested on 2D and 3D MRI scans of patients with brain tumors. The longitudinal adaptive compressed sensing MRI (LACS-MRI) scheme provides reconstruction quality which outperforms other CS-based approaches for rapid MRI. Examples are shown on patients with brain tumors and demonstrate improved spatial resolution. Compared with data sampled at the Nyquist rate, LACS-MRI exhibits signal-to-error ratio (SER) of 24.8 dB with undersampling factor of 16.6 in 3D MRI. The authors presented an adaptive method for image reconstruction utilizing similarity of scans in longitudinal MRI studies, where possible. The proposed approach can significantly reduce scanning time in many applications that consist of disease follow-up and monitoring of longitudinal changes in brain MRI.

The Center for Simulating Dynamic Response of Materials at the California Institute of Technology is constructing a virtual shock physics facility for studying the response of various target materials to very strong shocks. The Virtual Test Facility (VTF) is an end-to-end, fully three-dimensional simulation of the detonation of high explosives (HE), shock wave propagation, solid material response to pressure loading, and compressible turbulence. The VTF largely consists of a parallel fluid solver and a parallel solid mechanics package that are coupled together by the exchange of boundary data. The Eulerian fluid code and Lagrangian solid mechanics model interact via a novel approach based on level sets. The two main computational packages are integrated through the use of Pyre, a problem solving environment written in the Python scripting language. Pyre allows application developers to interchange various computational models and solver packages without recompiling code, and it provides standardized access to several data visualization engines and data input mechanisms. In this paper, we outline the main components of the VTF, discuss their integration via Pyre, and describe some recent accomplishments in large-scale simulation using the VTF.

IntroductionTraumatic osteoarthritis of the ankle joint caused after malleolar fractures of the ankle and tibial plafond fractures are frequently observed in comparatively young and highly active patients. Since the ankle movement in these patients is in general, comparatively favorable, orthopedists may sometimes have difficulty in deciding on a treatment policy. In our department, when treating traumatic osteoarthritis patients having a movable range within their ankle joints, we proactively applied distal tibial oblique osteotomy (DTOO) developed by Dr. Teramoto in 1994 or intra-articular osteotomy developed based on DTOO concepts such as distal tibial intra-articular osteotomy (DTIO) and distal fibular oblique osteotomy (DFOO).The objectives of the current study are to radiologically assess the ankle joint after intra-articular osteotomy for traumatic ankle osteoarthritis and evaluate the change in configuration of the ankle joint. This study summarizes the clinical results of intra-articular osteotomy obtained through the above-mentioned study. Patients and methodsThe subjects of this study were 20 patients diagnosed with traumatic osteoarthritis who were surgically treated for a total of 20 ankles. All patients underwent treatment with intra-articular osteotomy and were evaluated retrospectively for the following parameters: surgical procedure, fixation devices, clinical results based on the Japanese Society for Surgery of the Foot ankle/hindfoot scale (hereafter, JSSF scale) and post-operative adverse events. They were also assessed radiologically with pre- and post-operative anterior-posterior (AP) and lateral weight-bearing ankle radiographs. ResultsThe 20 patients consisted of 12 males and 8 females. The median age at surgery was 49 years old (range 14 - 87 years old) and the average follow-up period was 42 months (range 19 to 121 months). DTOO was applied to 10 cases, DFOO to 2 cases, DTOO and DFOO to 2 cases, medial-distal tibial intra-articular osteotomy (M-DTIO) and DFOO to 1 case, lateral-distal tibial intra-articular osteotomy (L-DTIO) and DFOO to 3 cases, M-DTIO followed by DTOO and DFOO to 1 case, and DTOO followed by low tibial osteotomy (LTO) to 1 case. Fixation devices utilized included circular external fixator for 15 cases, locking compression plate (LCP) to 3 cases, LCP and Kirschner-wire (K-wire) to 1 case, and screw and K-wire to 1 case. Radiological assessment revealed significant changes in the following parameters after surgery: tibial ankle surface angle (TAS, P= 0.0203), tibiotalar surface angle (TTS, P= 0.0021), medial malleolar angle (MMA, P= 0.0217), empirical axis (EA, P= 0.0019), fibular angle (FA, P= 0.0002), talar tilt angle (TTA, P= 0.0374), and tibial lateral surface angle (TLS, P= 0.0279). The JSSF scale also improved significantly after surgery (pre-operative JSSF scale: 51.1±11.0, post-operative JSSF scale: 89.2±8.2), p=0.0001. ConclusionIntra-articular osteotomy may change the radiological configuration of the ankle in a weight-bearing state. The present study showed very good short-term clinical results. Intra-articular osteotomy can prove a viable surgical option applicable for treatment of patients with traumatic ankle osteoarthritis having a reasonable range of motion within their ankle joints.

We describe a framework for training-oriented simulation of temporal bone surgery. Bone dissection is simulated visually and haptically, using a hybrid data representation that allows smooth surfaces to be maintained for graphic rendering while volumetric data is used for haptic feedback. Novel sources of feedback are incorporated into the simulation platform, including synthetic drill sounds based on experimental data and simulated monitoring of virtual nerve bundles. Realistic behavior is modeled for a variety of surgical drill burrs, rendering the environment suitable for training low-level drilling skills. The system allows two users to independently observe and manipulate a common model, and allows one user to experience the forces generated by the other’s contact with the bone surface. This permits an instructor to remotely observe a trainee and provide real-time feedback and demonstration.KeywordsHaptic FeedbackVolumetric DataHaptic RenderingDiamond BurrBone RemovalThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.