Proposal for a Unitary Anatomo-Clinical and Radiological Classification of Third Mobile Window Abnormalities

Introduction: An increased number of otic capsule dehiscence (OCD) variants relying on the third window pathomechanism have been reported lately. Therefore, a characterization of the anatomical structures involved and an accurate radiological description of the third window (TW) interface location have become essential for improving the diagnosis and appropriate therapeutic modalities. The purpose of this article is to propose a classification based on clinical, anatomical, and radiological data of third mobile window abnormalities (TMWA) and to discuss the alleged pathomechanism in lesser-known clinical variants.Materials and Methods: The imaging records of 259 patients who underwent, over the last 6 years, a high-resolution CT (HRCT) of the petrosal bone for conductive hearing loss were analyzed retrospectively. Patients with degenerative, traumatic, or chronic infectious petrosal bone pathology were excluded. As cases with a clinical presentation similar to those of a TW syndrome have recently been described in the literature but without these being confirmed radiologically, we thought it necessary to be integrated in a separated branch of this classification as “CT - TMWA.” The same goes for certain intralabyrinthine pathologies also recently reported in the literature, which mimic to some extent the symptoms of a TW pathology. Therefore, we suggest to call them intralabyrinthine TW-like abnormalities.Results: Temporal bone HRCT and, in some cases, 3T MRI of 97 patients presenting symptomatic or pauci-symptomatic, single or multiple, unilateral or bilateral OCD were used to develop this classification. According to the topography and anatomical structures involved at the site of the interface of the TW, a third-type classification of OCD is proposed.Conclusions: A classification reuniting all types of TMWA as the one proposed in this article would allow for a better systematization and understanding of this complex pathology and possibly paves the way for innovative therapeutic approaches. To encompass all clinical and radiological variants of TMWA reported in the literature so far, TMWAs have been conventionally divided into two major subgroups: Extralabyrinthine (or “true” OCD with three subtypes) and Intralabyrinthine (in which an additional mobile window-like mechanism is highly suspected) or TMWA-like subtype. Along these subgroups, clinical forms of OCD with multiple localization (multiple OCD) and those that, despite the fact that they have obvious characteristics of OCD have a negative CT scan (or CT – TMWA), were also included.

Low Reynolds Number Swimming Near Interfaces in Multi-Fluid Media

Microorganisms often swim within heterogeneous fluid media composed of multiple materials with very different properties. The swimming speed is greatly affected by the composition and rheology of the fluidic environment. In addition, biological locomotions are also strongly influenced by the presence of phase boundaries and free interfaces, across which physical properties of the fluid media may vary significantly. Using a two-fluid immersed boundary method, we investigate the classical Taylor’s swimming sheet problem near interfaces within multi-fluid media. The accuracy of the methodology is illustrated through comparisons with analytical solutions. Our simulation results indicate that the interface dynamics and phase separation in the multi-fluid mixture are closely coupled with the movement of the swimmer. Depending on the interface location, the frictional coefficient, and the multi-fluid composition, the swimmer can move faster or slower than that in a single phase fluid.

Modeling of Combustor-Turbine Vane Interaction Using Stress-Blended Eddy Simulation

Modeling the interaction between gas turbine engine modules is complex. The compact nature of modern engines makes it difficult to identify an optimal interface location between components, especially in the hot section. The combustor and high-pressure turbine (HPT) are usually modeled separately with a one-way boundary condition transfer to the turbine inlet. This approach is not ideal for capturing all the intricate flow details that travel between the combustor and the turbine and for tracking hot streak migration that determines turbine durability. Modeling combustor-turbine interaction requires a practical methodology that can be leveraged during the engine design process while ensuring accurate, fast, and robust CFD solutions. The objective of this paper is to assess the effectiveness of joint simulation versus co-simulation in modeling combustor and turbine interaction. Co-simulations are performed by exchanging information between the combustor and the turbine stator at the interface, wherein the combustor is solved using Stress-Blended Eddy Simulation (SBES) while the stator is solved using RANS. The joint combustor-stator simulations are solved using SBES. The benefits of using SBES versus LES are explored. The effect of the combustor-stator interaction on the flow field and hot streak migration is analyzed. The results suggest that the SBES model is more accurate than LES for heat transfer predictions because of the wall treatment and the joint simulation is computationally efficient and less prone to interpolation errors since both hot section components are modeled in a single domain.

Evaluation of Design Provisions for Horizontal Shear Strength in Composite Precast Concrete Beams with Different Interface Conditions

In a precast concrete (PC) composite beam, the horizontal interface between the PC beam and the cast-in-place (CIP) slab is located either on the compression side or on the tensile side of the cross-section. If the CIP slab is on the compression side, it becomes C-type interface, and if it is on the tensile side, it becomes T-type interface. Tensile cracks in the CIP slab may cause the horizontal shear strength of composite beams to decrease because of the reduced anchorage performance of shear reinforcements as well as the sliding on the interface. Such a tendency can be found from previous test results of specimens having T-type interface. In this study, the results of the push-off test and the beam flexure test were collected and analyzed to evaluate effects on the horizontal shear strength depending on the interface conditions, such as the interface location, surface roughness, concrete compressive strength, and clamping stress by shear connectors. The horizontal shear strength equations of ACI, PCI, AASHTO LRFD, and MC 2010 were evaluated with a database composed of 84 push-off tests and 95 beam tests from previous studies. According to the evaluation, evaluation results show that the design codes predict the horizontal shear strength conservatively for conditions other than the interface location. The horizontal shear strength deviated largely depending on the interface locations. The design codes conservatively estimate the horizontal shear strength for C-type interface, but the horizontal shear strength of T-type interface is overestimated. Based on current studies, it is recommended to use a friction coefficient of 0.7 as MC 2010 when calculating the horizontal shear strength of a composite beam with roughened T-type interface.

Anisotropic Multicomponent Topology Optimization for Additive Manufacturing With Build Orientation Design and Stress-Constrained Interfaces

This paper presents a multicomponent topology optimization method for designing structures assembled from additively manufactured components, considering anisotropic material behavior for each component due to its build orientation, distinct material behavior, and stress constraints at component interfaces (i.e., joints). Based upon the multicomponent topology optimization (MTO) framework, the simultaneous optimization of structural topology, its partitioning, and the build orientations of each component is achieved, which maximizes an assembly-level structural stiffness performance subject to maximum stress constraints at component interfaces. The build orientations of each component are modeled by its orientation tensor that avoids numerical instability experienced by the conventional angular representation. A new joint model is introduced at component interfaces, which enables the identification of the interface location, the specification of a distinct material tensor, and imposing maximum stress constraints during optimization. Both 2D and 3D numerical examples are presented to illustrate the effect of the build orientation anisotropy and the component interface behavior on the resulting multicomponent assemblies.

Numerical and Experimental Investigation of Phase Change Heat Transfer in the Presence of Rayleigh–Benard Convection

This research investigates the melting rate of a phase change material (PCM) in the presence of Rayleigh–Benard convection. A scaling analysis is conducted for the first time for such a problem, which is useful to identify the parameters affecting the phase change rate and to develop correlations for the solid–liquid interface location and the Nusselt number. The solid–liquid interface and flow patterns in the liquid region are analyzed for PCM in a rectangular enclosure heated from bottom. Numerical and experimental results both reveal that the number of Benard cells is proportional to the ratio of the length of the rectangular enclosure over the solid–liquid interface location (i.e.,, the liquified region aspect ratio). Their effect on the local heat flux is also analyzed as the local heat flux profile changes with the solid–liquid interface moving upward. The variations of average Nusselt number are obtained in terms of the Stefan number, Fourier number, and Rayleigh number. Eventually, the experimental and numerical data are used to develop correlations for the solid–liquid interface location and average Nusselt number for this type of melting problems.

Computational Fluid Dynamics Simulations of Nonlinear Sloshing in a Rotating Rectangular Tank Using the Level Set Method

In this paper, numerical simulations of nonlinear sloshing in rectangular tanks are presented. Model implementations in the open source software reef3d are tested, and the results are compared with experimental data from three different conditions. The interface location is compared for both linear and nonlinear sloshing. The nonlinear sloshing is simulated in both two-dimensional (2D) and three-dimensional (3D). Video images from the SPHERIC project are compared with simulations for the interface. A condition with lateral wave impacts in sloshing, with a frequency close to the natural frequency of the first mode, can be found in this case. The numerical model is solving the Reynolds-averaged Navier–Stokes (RANS) equations with the k–ω turbulence model. The level set method is used to capture the interface. Higher order discretization schemes are implemented to handle time-evolution and convective fluxes. A ghost cell method is used to account for solid boundaries and parallel computations. It is found that the limiting factor for the eddy-viscosity has significant influence in the nonlinear sloshing cases. As the sloshing becomes more violent, the increased strain at the gas–liquid interface overproduces turbulence energy with unrealistically high damping of the motion. Three-dimensional simulations show slightly better comparison than 2D. Due to nonlinearities and small damping, the time to reach steady-state may take several cycles. The last case shows promising results for the global motion. As expected, the breakup of the liquid surface makes it difficult to resolve each phase. But overall, the numerical model predicts the sloshing motion reasonably well.

Quasi 3D transdimensional Markov-chain Monte Carlo for seismic impedance inversion and uncertainty analysis

Accurate estimation of subsurface properties plays an important role in successful hydrocarbon exploration, and a variety of different types of inversion schemes are used to infer earth properties such as velocity or density by analyzing the surface seismic. The Markov-chain Monte Carlo (MCMC) stochastic approach is widely used to estimate subsurface properties. We have used a transdimensional form of MCMC, reversible jump MCMC (RJMCMC), to estimate seismic impedance, which allows the inference of the number of interfaces as well as the interface location and layer impedances. Estimating the uncertainty quantitatively is also very important when performing stochastic inversion. Therefore, the goal of this paper is to apply the transdimensional method to obtain a 3D seismic impedance model and to quantify uncertainty in impedance and interface locations. We also measured the speedup of the proposed algorithm by applying data and task parallelism. To demonstrate the performance and reliability of the proposed RJMCMC impedance inversion, we used seismic data from the E-segment of the Norne field in Norwegian Sea. The results of the quasi 3D transdimensional MCMC approach, which independently inverts data from each common-depth-point location, indicate high velocity contrasts near gas-oil contacts and high uncertainty in impedance near discontinuities. Also, the cross section of the impedance uncertainty volume helps to identify the location of a high-contrast boundary corresponding to the location of the possible gas reservoir. The proposed uncertainty measure can serve as an attribute to identify important reservoir features.