Partial Cavity Research Articles

Intraoperative radiation therapy for early-stage breast cancer.

Intraoperative radiotherapy (IORT) offers more convenience compared to external beam radiotherapy (EBRT) following breast-conserving surgery for early-stage breast cancer. This study describes the implementation of IORT at a metropolitan academic cancer center. Demographics, tumor characteristics, margin status, adjunct EBRT, and cosmetic results were retrospectively analyzed in patients undergoing BCS with IORT. IORT consists of 20 gray delivered to the partial mastectomy cavity. From 2015 to 2020, 171 patients (65.5% African American) were included. Histologically, 104 (60.8%) patients had invasive ductal carcinoma (IDC), while 67 (39%) patients had DCIS only. Seventeen (15.9%) patients with IDC and 12 (8.6%) patients with DCIS had positive margins. There were 15 ipsilateral breast recurrences (8.8%) and three patients (20%) developed systemic disease. Twenty-five patients (14.6%) underwent adjuvant EBRT. The local recurrence-free survival at 60 months from date of IORT was 89.4% (95% CI 82.7%-93.6%). For overall survival (OS), 168 (98.2%) patients were alive at a median follow-up of 51.4 months, and three total deaths were recorded. IORT is a highly desirable and convenient alternative to EBRT for early-stage breast cancer especially for patients with poor compliance. IORT has an acceptable ipsilateral recurrence while not precluding adjunct EBRT based upon the final pathologic report.

Mixed convection heat transfer in a partial porous layered split lid-driven wavy wall cavity with Cu–H2O nanofluid

This numerical study investigates mixed convection heat transfer in a two-dimensional irregularly-shaped enclosure with a nanofluid-saturated porous medium. The enclosure has wavy vertical walls, a centered triangular block, and a lid split into two regions moving in opposite directions. Transport equations are solved using the finite element method under varied Darcy (10−5 to 10−1), Reynolds (50 to 200), Richardson (0.1 to 10), amplitude (0 to 0.2), and nanoparticle volume fraction (0 to 0.1) numbers. Results demonstrate the combined effects of forced convection from lid motion and natural convection from temperature differences significantly enhance heat transfer. The wavy walls induce secondary flows and periodic disruption of thermal boundary layers. Increasing Darcy number enables deeper penetration into the porous block. Copper nanoparticles incrementally improve conductive heat transfer. Richardson number effects are more prominent at higher Reynolds numbers as buoyancy forces influence vertical convection. This study provides novel insights into synergistically utilizing wavy geometries, nanofluids, porous media, and active pumping for optimizing heat transfer in irregular enclosures for electronics cooling and thermal management.

Large eddy simulation of the cavity shedding characteristics of ventilated cavitation around the underwater vehicle

Ventilated cavitation is utilized for reducing drag and improving the headway of underwater vehicles. The ventilated cavitating flow around the axisymmetric body is simulated using the Large Eddy Simulation (LES) method in this study. Three cavity morphologies with different ventilation rates (Cq) are observed: Foamy Cavity (FC), Continuous Transparent and Foamy Cavity (CTFC) and Super Cavity (SC). The cavity shedding characteristic of the three different cavity morphologies is revealed. For partial cavity, the periodic cavity shedding is dominated by the local high pressure, re-entrant jet and vortex. The distributions of the turbulent kinetic energy and the pulsation enstrophy exhibit different migration mechanisms during the cavity shedding. The energy characteristic is reflected by three terms of the entropy generation. And the entropy production rate by direct dissipation occupies a dominant position, accounting for about 80% of the total entropy production, while the entropy production rate by viscous dissipation only accounts for 4%. For super cavity, gas leakage is dominated by a re-entrant jet induced by the intense adverse pressure gradient. And the results also demonstrated the velocity and vorticity pulsations around the test body wrapped in a super cavity are not intense.

Trampolines and insulation and data, Oh My!

This presentation will discuss sound and vibration data gathered for two separate and unrelated acoustical consultations. The first is a consultation for an adventure park facility (trampolines, arcade games, ball pits, etc.) planned on the upper level of an existing mall; acoustical concerns included vibration from jumping on trampolines and noise from amplified music to adjacent tenant spaces. The second is a comprehensive set of sound level reduction measurements in accordance with ASTM E336 / ASTM E2235, as well as ASTC calculations in accordance with ASTM E413; these results facilitated an investigation of the effect of complete versus partial cavity insulation within partitions.

Generation of spatiotemporal dark pulse or polarization domain wall solitons in a partial multimode mode-locked fiber laser

In this paper, we have experimentally investigated different operational states of a partial multimode Er-doped spatiotemporal mode-locked (STML) fiber laser. The STML is enabled by nonlinear multimode interference (NL-MMI) effect from the partial multimode cavity structure. It is found that by adjusting the multimode polarization controller (PC) and the pump power, the STML dark pulses, bright pulses, as well as the polarization domain wall solitons can all be obtained, alternatively. The fused-tapered multimode coupler is responsible for the dark pulses generation via the enhanced modal cross-phase coupling. It is believed that the present findings can offer an important insight into the spatiotemporal dynamics of the STML solitons.

Experimental investigation of the dynamic evolution of cavity during the free water-exit of a high-pressure venting vehicle

The underwater vehicle is subjected to complex hydrodynamic loads during water-exit process, which seriously affect the structural strength and water-exit stability of the vehicle. This paper investigates the effect of high-pressure venting conditions on the dynamic evolution characteristics of the cavity during the completely free water-exit of a vehicle based on self-designed experiments. Some novel phenomena are found in the experiment, and the hypothesis of constant acceleration is established to explain the formation mechanism. The results reveal that the reentrant jet is the main factor influencing the pattern of cavity development and causes great differences between the partial and supercavity states. The balance between the initial cavity volume increase and the gas leakage rate results in the fact that increasing the launch Froude number in the partial cavity state does not cause significant changes in the cavity size. There is a stable interval between 0.0038 and 0.03 for the effect of gas entrainment coefficient on the development of the cavity. The influence of the launch Froude number on the cavity morphology varies within different gas entrainment coefficient ranges. Besides, six patterns of cavity closure are found for free water-exit conditions. The coupling closure pattern of reentrant jet and interaction vortex tube is the most stable during the water-exit process. The stable development intervals of cavity closure pattern and cavity morphology are roughly the same. The present study aims to provide a reference for the active venting flow control of the vehicle during water-exit.

Analysis of confined cavity evolution and related pressure created by hydrodynamic ram

The impact of high-velocity projectiles on fluid-filled containers can induce the hydrodynamic ram (HRAM) effect, leading to the creation of a cavity within the fluid. The evolution of this cavity is subject to the constraints imposed by the container. This study aims to investigate the decay of projectile velocity and the development of confined HRAM cavities using a combined approach involving experimental and analytical methods. In contrast to existing research, this study accounts for the varying projectile velocities during different HRAM phases. Furthermore, enhancements have been introduced to the established cavity model, encompassing refinements in pressure differentials both inside and outside the cavity, alongside adjustments to the radial extent of liquid disturbance. The effectiveness of these refinements has been substantiated through experimental evidence. The findings illuminate two prominent constraint effects exerted by the container on the dynamics of HRAM cavities. Primarily, it accentuates the disparity in HRAM cavity pressures between the interior and exterior environments, and this pressure differential follows an exponential decay with distance. Secondly, it profoundly influences the flow of liquid near the wall, resulting in a considerably slower contraction of the cavity near the wall compared to its expansion phase. The evolution of the HRAM cavity is observed to manifest across three distinct stages: the unconfined cavity expansion stage, the partial cavity confinement stage, and the full cavity confinement stage.

Phase change mechanism of periodic cavitation evolution in turbulent cavitation boundary layer

The instantaneous flow features of a partial cavity were investigated using a mass transfer cavitation model and large eddy simulations around a three-dimensional symmetric hydrofoil at Reynolds number Re=1×106, cavitation number σ = 0.43, and attack angle α = 0°. The phase change mechanism of periodic cavitation evolution, that is, energy conservation and transformation between turbulent fluctuation kinetic energy and water-vapor volume fraction ∝vapor, was identified in the turbulent cavitation boundary layer. The streamwise velocity Vx and pulsation Vx′,Vx′Vx′ play the dominant role in the cavitation evolution, whereas the spanwise and normal magnitudes and their pulsations are all less than 1–2 orders of magnitude. Because of the flow stratification phenomenon, the boundary layer is divided into the inner (below y+=40), transition (within a range of y+=50–80), and outer zones (beyond y+=90) in the normal y+ direction. Along all chordwise points, cavitation initiates entirely within the inner zone of y+=12–30, where Vx′Vx′ is strongest at the water saturation pressure. In the inner zone of y+=5–8 and the outer zone, cavitation initiation is delayed with a low ∝vapor. The expression between the instantaneous ∝vapor and Vx′Vx′ was improved by adding a correction term (γ*Sc) to validate the rationality of the phase change mechanism.

Unsteady Cloud Cavitation on a 2D Hydrofoil: Quasi-Periodic Loads and Phase-Averaged Flow Characteristics

We perform large-eddy simulations to study a cavitating flow over a two-dimensional hydrofoil section—a scaled-down profile (1:13.26) of guide vanes of a Francis turbine—using the Schnerr–Sauer cavitation model with an adaptive mesh refinement in intensive phase transition flow areas. In the test case, the guide vane is tilted at an angle of attack of 9° to the direction of the flow, in which the Reynolds number, based on the hydrofoil chord length, equals 1.32×106, thus providing a strong adverse pressure gradient along the surface. The calculated time-averaged turbulence characteristics are compared with those measured by particle image velocimetry to verify that the flow is correctly reproduced in numerical simulations using the procedure of conditional averaging proposed and tested in our previous investigation. A re-entrant jet is identified as the primary source of vapor cloud shedding, and a spectral analysis of the cavitating flow over the profile midsection is conducted. Two characteristic frequencies corresponding to the cases, when an attached cavity detaches completely (as a whole) and two partially from the hydrofoil, are found in the flow. The study reveals that the natural frequency of partial cavity shedding is three times higher than that of full detachments. The examined regime exhibits an oscillatory system with two oscillation zones related to cavitation surge instability and unsteady cloud cavitation resulting from the re-entrant jet. Conditional averaging correlates cavitation structures with pressure distributions, forces, and torque on the guide vane. This modeling approach captures the fine details of quasi-periodic cavitation dynamics, providing insights into unsteady sheet/cloud cavitation and offering a method for developing control strategies.

InN TFET with extended gate for high sensitivity label‐free biosensor

AbstractAn extended gate tunneling field effect transistor (EG‐TFET) with narrow bandgap material InN as a label‐free dielectric modulated biosensor is proposed and investigated. An optimum structure of the proposed InN TFET is given by comparing on‐state and ambipolar current. The on‐state current is improved by increasing the length of source overlap, for the rate of forward tunneling increases. Further, the ambipolar current is suppressed by increasing the length of drain offset, for the rate of backward tunneling decreases. A cavity under the gate electrode is formed for sensing biomolecules by dielectric modulation. The performance of EG‐TFET biosensor corresponding to varied dielectric constants of biomolecule is analyzed. In addition, the impacts of charge density and partial filled cavity on the drain current sensitivity are investigated. The electric field, surface potential and energy band profiles are used to explain the working principle of the EG‐TFET biosensor. The simulations reveal that the drain current sensitivity is 3.72 × 107 when neutral biomolecule with κ = 12 is immobilized in the cavity. A linearity fit verification is given, and the results of current sensitivity reveal a good linearity of the EG‐TFET biosensor with fitness coefficient γ2 > 0.99.

Assessing tunnel basement structure damage under train excitation: Impacts of surrounding rock deterioration

On the ground of preliminary study of the Taihangshan Mountain Tunnel, it was observed that under the water-rich conditions, the long rolling of heavy-haul trains will deteriorate the surrounding rock, thereby causing damage to the bottom structure. Combined with data from long-term field monitoring and discrete element analysis, after clarifying the law of bedrock deterioration, the fuyingzi tunnel of Zhangtang railway in China is taken as the research object of fatigue damage. Ansys Workbench simulation software was used to further compare and analyze the influence of three characteristic deterioration stages of the surrounding rock on the basement structure damage. Based on the results, when the surrounding rock is intact, the basement structure gradually damages and expands from top to bottom, and the structural minimum fatigue life is approximately 76 years. When the surrounding rock is a partial cavity, the damage of the bottom structure intensifies and develops toward the surrounding rock deterioration position. The minimum fatigue life of the structure is 67 years, which decreases by 11.8%. When the surrounding rock is a cavity and connected, the damage of the bottom structure develops downward to a certain extent, which causes the structural damage at the deterioration position of the surrounding rock to develop in the opposite direction, i.e., from bottom to top. The structural minimum fatigue life is 42 years, which is reduced by 44.7% in the better situation.

Wave effects on the hydroelastic response of a surface-piercing hydrofoil. Part 2. Cavitating and ventilating flows

The objective of this paper is to understand the effects of waves and vaporous cavitation upon the hydrodynamic and hydroelastic responses of a flexible surface-piercing hydrofoil, adding to the subcavitating results presented in Part 1. In general, the presence of a sufficiently large vaporous cavitation bubble facilitated the formation of a ventilated cavity, substantially reducing the angle of attack or speed required to induce fully ventilated flow, relative to subcavitating conditions. A new co-analysis procedure was used to isolate synchronous hydrodynamic modes and structural operating deflection shapes. Significant dynamic load amplification occurred when the resonant frequencies of the first twisting and second bending modes coalesced in both fully wetted and partially cavitating flows. The presence of waves did not diminish the effect of frequency coalescence, but did encourage intermittent lock-in with both leading edge cavity shedding and trailing edge vortex shedding at certain speeds. Partial cavity shedding typically had a negligible impact on the power spectral densities of structural motions because of incoherent cavity shedding. However, lock-in between the cavity shedding frequency and modal coalescence frequency led to shifting of the primary frequency peak, as well as amplified harmonics and interactions between the cavity shedding frequency and vortex shedding frequency. The transition from partially cavitating to fully ventilated flow caused sudden and large drops in the mean hydrodynamic loads and deformations, as well as substantial reductions in the intensity of the fluctuations.

Natural Convection Instabilities Using the Lattice Boltzmann Method: Cavity Aspect Ratio Effect

In this paper, the natural convection instability flows in a partial heating cavity filled with air and cooled by the top wall are numerically investigated using the lattice Boltzmann method; and the cavity is partially heated and contains a heat source from below that is presented as an electronic component. To track the cavity aspect ratio effect on the heat transfer over time, first, a series of numerical simulations is completed by varying the aspect ratio of the cavity from to . The results show that the change in aspect ratio has a noticeable impact on the heat transfer behavior, specifically on the temperature distribution in the cavity, and the numerical results obtained indicate two different temperature distribution regimes: a stable steady regime, and a stable oscillatory regime. In the second step, a numerical simulation is done to study the natural convection instability into the cavity for the aspect ratio configuration of . The results show that the cavity structure has an important effect on the heat transfer in the cavity. The lattice Boltzmann method choice as a numerical simulation approach is due to its considerable result in fluid flow simulation and also to its simplicity of implementation, and it has become a suitable alternative method for solving fluid dynamics and thermal problems, as well as challenged traditional methods in many sectors by its simplicity of implementation.

Partial cavity shedding on a hydrofoil resulting from re-entrant flow and bubbly shock waves

Partial cavity flows forming on a NACA0015 hydrofoil are visualized using high-speed cinematography and time-resolved X-ray densitometry. These observations reveal the underlying flow features that lead to the cloud cavity shedding. Previous studies have reported that both near-surface liquid re-entrant flow and bubbly shock waves can serve as the mechanisms causing cavity pinch-off and cloud shedding. We identify both mechanisms in the current study. The cavity shedding frequency was also examined and related to the underlying flow dynamics. The probability of re-entrant flow or bubbly shock-induced shedding processes are quantified, and the likelihood of each mechanism is shown to be a function of both the cavitation number and the Mach number of the bubbly mixture within the separated region of the cavity. When the Mach number of the two-phase mixture in the cavity exceeds unity, shock waves become the dominant mechanism that lead to large-scale cavity shedding and cloud cavitation.

Experimental and Simulation Study for the Dissociation Behavior of Gas Hydrates─Part II: sII Mixed Gas Hydrates

This study is an extension of our research on the dissociation behavior of sI CH4 hydrates (Part I). In this study, investigations of the dissociation of binary and multicomponent structure II hydrates were carried out. A novel approach involving in situ and ex situ Raman spectroscopic measurements together with molecular dynamics simulations were applied for a systematic assessment of the hydrate dissociation and gas release behavior due to the destabilization of hydrate cavities. The hydrate decomposition was induced by thermal stimulation to mimic the warming of oceans and atmosphere brought by climate changes. The interactions between the released gas, aqueous phase, and hydrates were described. The results demonstrated that in the vicinity of the hydrate surface, the liquid phase was oversaturated with the gas molecules and some unstable partial hydrate cavities were also formed. Consequently, the release of gas was temporarily stopped or very slow. Throughout the process, the hydrate underwent decomposition–reformation–continuing decomposition until the crystal disappeared. A faster breakdown of small cavities (512) was recorded, leading to an increase in the large-to-small cavity ratio during dissociation. Moreover, the results indicated a faster release of CH4 molecules compared to C3H8 over the dissociation process of the sII CH4–C3H8 hydrate. This could be due to the higher diffusivity of CH4 molecules from the hydrate surface to the gas phase as well as its lower potential to stabilize the cavities compared to C3H8. The release of CH4 molecules was also faster compared to CO2 and C2H6 molecules in the sII mixed hydrate, leading to changes in the hydrate composition throughout the process.

Natural convection of NEPCM in a partial porous H-shaped cavity: ISPH simulation

PurposeThis paper aims to investigate the conformable fractal approaches of unsteady natural convection in a partial layer porous H-shaped cavity suspended by nano-encapsulated phase change material (NEPCM) by the incompressible smoothed particle hydrodynamics method.Design/methodology/approachThe partial hot sources with variable height L_Hot are in the H-cavity’s sides and center. The performed numerical simulations are obtained at the variations of the following parameters: source of hot length L_Hot = (0.4–1.6), conformable fractal parameterα(0.97–1), fusion temperatureθf(0.05–0.9), thermal radiation parameterRd(0–7), Rayleigh numberRa(103–106), Darcy parameterDa(10−2to 10−5) and Hartmann numberHa(0–80).FindingsThe main outcomes showed the implication of hot source length L_Hot, Rayleigh number and fusion temperature in controlling the contours of a heat capacity within H-shaped cavity. The presence of a porous layer in the right zone of H-shaped cavity prevents the nanofluid flow within this area at lower Darcy parameter. An increment in the thermal radiation parameter declines the heat transfer and changes the heat capacity contours within H-shaped cavity. The velocity field is strongly enhanced by an augmentation on Rayleigh number. Increasing the Hartmann number shrinks the velocity field within H-shaped cavity.Originality/valueThe novelty of this work is solving the conformable fractal approaches of unsteady natural convection in a partial layer porous H-shaped cavity suspended by NEPCM.

Influence of Base Rock Deterioration on Tunnel Bottom Structure Damage under Train Excitation

In the ground of the preliminary study of the Taihangshan Mountain Tunnel, it was observed that under water-rich conditions, the long rolling of heavy-haul trains would deteriorate the surrounding rock, thereby causing damage to the bottom structure. Combined with data from long-term field monitoring and discrete element analysis, after clarifying the law of bedrock deterioration, the Fuyingzi Tunnel of Zhangtang Railway in China is taken as the research object of fatigue damage. ANSYS Workbench simulation software was used to compare further and analyze the influence of three characteristic deterioration stages of the surrounding rock on the basement structure damage. Based on the results, when the surrounding rock is intact, the basement structure gradually damages and expands from top to bottom, and the structural minimum fatigue life is approximately 76 years. When the surrounding rock is a partial cavity, the damage to the bottom structure intensifies and develops toward the surrounding rock’s deterioration position. The minimum fatigue life of the structure is 67 years, which decreases by 11.8%. When the surrounding rock is a cavity and connected, the damage of the bottom structure develops downward to a certain extent, which causes the structural damage at the deterioration position of the surrounding rock to develop in the opposite direction, i.e., from bottom to top. The structural minimum fatigue life is 42 years, which is reduced by 44.7% in the better situation.

Experimental study on ventilated cavity flow at the tail of underwater vehicle under low surface tension

In model experiments, the Weber number determined by the surface tension usually has a significant effect on the ventilated cavity flow characteristics. This paper describes experiments in which the surface tension of water is reduced by adding surfactant, allowing thes flow characteristics of the ventilated cavity at the tail of an underwater vehicle under low surface tension to be analyzed. The effects of the Froude number, Weber number and cavitation number on the development of the ventilated tail cavity are explored. There are three stable closure modes of the ventilated cavity under low surface tension, namely, a complete foam cavity, partial foam cavity, and giant spindle cavity. The results show that a larger Froude number produces a smaller ventilated cavity, which mainly exhibits the complete foam cavity closure mode. A smaller cavitation number creates a larger ventilated cavity, which is mainly represented by the giant spindle cavity closure mode. The critical cavitation number under this closure mode is 2.19. At higher ventilation pressures, the entrainment ability at the end of the ventilated cavity is stronger, and bubbles are less likely to fall off.

Numerical investigation on the inhibition mechanisms of unsteady cavitating flow around stepped hydrofoils

In this work, the influence of obstacles on the control of unsteady cavitating flows is investigated numerically within the framework of homogeneous flow. The predicted Strouhal number of the cavity shedding around the smooth hydrofoil is close to the experimental value, indicating the accuracy of the numerical simulation. Four installation sites are examined, including 10%, 20%, 30%, and 40% of the chord length from the leading edge. The instantaneous and time-averaged hydrodynamics in conjunction with the unsteady cavity behaviors are discussed in detail. The results indicate that all cases display similar flow patterns within one shedding cycle, including the development of the attached sheet cavity, sheet/cloud transformation, and cloud cavity collapse. The hydraulic lift is governed by the partial cavity oscillation but could be significantly modified by the trailing wake vortices, especially after installing the obstacle. The recommended optimal position of the obstacle is X/L=0.4, and the corresponding pressure fluctuations and lift-to-drag ratio achieve the best performance. However, the mean vapor volume is significantly reduced when the obstacle is located at X/L=0.3, indicating the minimum risk of cavitation erosion. Installing the obstacle at different locations along the suction surface will provide different effects on oscillation based on the analyses of the Lagrangian coherent structures. The corresponding primary frequency varies in a narrow range between 106.67 Hz ∼ 121.33 Hz. Proper orthogonal decomposition (POD) analyses of the vapor fraction reveal the contribution of flow morphology to the partial cavity oscillation. Installing the obstacle could significantly limit the size of each pattern, especially for X/L=0.4.

Towards selecting the optimized external wall solution in Iran: Comparison between life cycle assessment (LCA), cost benefits, and thermal performance

External walls, as the main components of a building's envelope, directly affect the building's thermal and environmental performance due to their high carbon emissions, life cycle costs, and user comfort. As the buildings are responsible for one-third of global GHG emissions, choosing the most effective solutions for external walls is crucial to combat the environmental crisis. This paper aims to identify and assess conventional external walls in Iran. A multi-criteria scoring system is established to evaluate them regarding carbon emissions, cost benefits, and thermal performance (R-value). A selection criteria is defined, and a total of 45 external walls are identified and categorized into three wall types: solid, filled cavity, and partial cavity walls. Assessing environmental impact involves conducting a cradle-to-handover simplified life cycle assessment. Cost assessment is performed using construction costs, and thermal performance assessment is conducted based on thermal conductivity coefficient and thickness. Based on the results, the highest scores belong to partial cavity walls. Partial cavity walls perform better than simple and filled cavity walls, although the simple wall is Iran's most widely used wall solution. The manufacturing stage represents the more significant contribution to environmental impact in all cases, followed by transportation and construction. The environmental analysis indicates that the structural layer (53.7%), followed by external finishing (14%), and transportation (12.1%) are the three highest contributors, respectively. The results also stress the importance of transport protocols in the carbon emissions reduction of external walls by indicating the structural layer as a carbon hotspot.