Cavity Diameter Research Articles

Reconstruction of Water Entry Cavity by OECT through combining Field Transformation and Group-based Sparse Representation

Abstract Due to the fact that a water entry cavity directly affects the hydrodynamic characteristics of underwater vehicles, its monitoring is crucial for controlling the motion stability of the vehicles. However, there is limited research on the visualization and measurement of cavities during vehicle motion. Based on Open-Electrical Capacitance Tomography (OECT), this article presents an image reconstruction method to measure the water entry cavity by combining field transformation and group-based sparse representation (FT-GSR). To address the openness of the cavity measurement domain, a field transformation method is proposed that unifies open- and closed-domain image reconstruction while reducing the dimensionality of the unknowns to be resolved and the computational complexity of the forward problem. To achieve high-resolution reconstruction, a group-based sparse representation method is proposed that utilizes global sparsity and neighborhood self-similarity in the reconstructed image, which shows good performance in simulation. Finally, water entry experiments were conducted to validate the performacne of the proposed method. Images captured by a high-speed camera were used as references to assess the accuracy of the calculated equivalent cavity diameter. The experimental results indicate that the proposed method can outperform typical reconstruction methods while maintaining computational cost. Based on the aforementioned performance, the proposed method is anticipated to be integrated into system-on-chip technology to enable real-time, high-precision monitoring of the water entry cavity.

Body size mediates the role of insect seed predators as ecosystem engineers for arthropod communities

Abstract Arthropods that interact with host plants can function as allogenic ecosystem engineers by modifying plant structures, thereby influencing the availability of resources for other organisms. This study examined the role of insect seed predators as ecosystem engineers within arthropod communities and assessed how body size affects this facilitation process. We hypothesised that fruits with more and larger cavities would be more colonised, since they would increase the probability of colonisation and allow a wider range of sizes of arthropod species to access the fruits, respectively. We collected tamarind (Tamarindus indica, Fabaceae) fruits infested by different seed predators. Following the emergence of these organisms, we categorised 200 fruits into five categories (40 per category) based on the number and size of entrance/emergence cavities: absent (fruits without cavities), small (one small cavity), medium (one medium cavity), large (one large cavity), and multiple (two or more cavities). The fruits were then taken back to the field for 2 and 4 months at the beginning of rainy season to allow colonisation by secondary arthropods. We recorded 5237 secondary colonisers from 50 morphospecies and 12 different orders. Ants were the most abundant group (4356 individuals) and utilised the fruits mainly as nesting sites (17 nests). Overall, tamarind fruits in the absent category had a lower species richness and abundance of arthropods compared to fruits with cavities present. Additionally, fruits with large cavities (medium and large categories) supported greater species richness and abundance than those in the small and absent categories. Finally, multiple cavities in fruits facilitate more arthropod species to colonise them compared with those with just one cavity. Our findings underscore the critical role of seed predators as ecosystem engineers, significantly shaping the structure of plant‐dwelling arthropod communities. We conclude that the cavity diameter and number of cavities in fruits are key factors influencing this facilitation process.

Unveiling the glass‐forming ability of MOF: A high‐throughout simulation and data mining

AbstractThe correlation between the glass‐forming ability (GFA) of Metal–Organic Frameworks (MOFs) and their structural characteristics remains poorly understood. To address this gap, we analyze over 20,000 MOFs from the MOF database, comparing geometric and electronic order parameters between zeolitic imidazolate frameworks (ZIFs) and other MOFs. Our findings reveal a set of order parameters that effectively capture the thermal stability, and GFA of MOFs, acting as structural genes to predict glass formation. Through molecular dynamics simulations on representative ZIFs structures, we validate the reliability of these order parameters, particularly the total bond‐order density (TBOD) and the largest cavity diameter (LCD), for screening potential melt‐quenched MOFs. Furthermore, we predict that external pressure and electric fields can control the TBOD of MOFs, expanding our understanding of their thermal stability. This work identifies structural genes associated with the melt stability of MOFs, and contributes valuable insights into the prediction and understanding of MOFs glass‐forming ability.

PET-CT outcomes from a randomised controlled trial of rosuvastatin as an adjunct to standard tuberculosis treatment

Adjunctive rosuvastatin for rifampicin-susceptible pulmonary tuberculosis (rs-PTB) shows no effect on microbiological or radiological outcomes in a phase IIb randomised, controlled trial (NCT04504851). We explore the impact of adjunctive rosuvastatin on 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) imaging in a sub-study of 24 participants. Changes in standardised uptake value (SUVmax, SUVmean), Total Metabolic Volume, (TMV), Total Lesion Glycolysis (TLG), cavity diameter and volume, between week 0 and week 8 post-randomisation, are evaluated. Here we show no evidence of difference in the reduction in TLG [median 65.8% for the rosuvastatin group (Q1, Q3 38.6, 94.5) vs 64.3% for standard tuberculosis treatment group (Q1, Q3 −20.0, 81.7), P = 0.32], reduction in cavity volume on CT [median 3.2 cm3 (IQR 11.1, 0.5) for rosuvastatin, 2.2 cm3 (IQR 4.6, 0.7) for control (p = 0.72)], or any other PET-CT parameter measured. We show that the first 8-weeks of standard tuberculosis treatment results in a reduction in the volumetric indices (TLG and TMV), but had little change in SUVmax or SUVmean. Change in TLG and TMV holds promise as biomarkers of tuberculosis treatment response: future PET-CT studies should evaluate their role in predicting relapse-free cure, and the overall role of 18F-FDG-PET-CT as a tool for early-phase tuberculosis clinical trials.

Numeric ring-reconstructions based on massifs favor a non-oblique south pole-Aitken-forming impact event

The size and shape of ring structures around the South Pole-Aitken basin (SPA) have been subject of several studies over the past decades. Most investigations considered long wavelength signatures such as the topographic outline of the extant basin floor or orbital observations of elemental abundances, all of which are oval or crescent-shaped and therefore implied an elliptic SPA formed by an oblique impact. Here we present a novel dataset of 286 circum-SPA massifs taller than 1000 m prominence, 201 of which we interpret as likely ring remnants based on morphology and location. Using a gradient-based optimization algorithm, we performed three numeric fits of these massifs, each consisting of an outer and an inner ellipse. While one fit included all 201 likely ring remnants, the two other fits included only massifs taller than 2160 m prominence or such that show a negative Bouguer anomaly (like the Outer Rook Ring around Orientale basin). A set of massifs that are part of non-ambiguous, relatively intact SPA-ring segments were given the same weight as all other massifs in every fit. The sizes of our three fits are relatively similar (variances ≤ 3.7%) with semimajor and semiminor axes of the outer ellipses ranging from 1099.4 km to 1126.9 km and 1060.0 km to 1099.4, respectively, and those for the inner ellipses from 946.2 km to 947.4 km and 910.2 to 941.3 km, respectively. As the two more exclusive fits discard massifs that are part of the relatively intact ring segments, we tentatively favor our more inclusive fit using all 201 likely ring remnants, which also has the lowest loss per datapoint value. All our fits have ellipticities ≤ 1.06 resulting in a near-circular SPA, which should have required an impact at a non-oblique angle of well over 44°. Compared to previously assumed lower impact angles around 30° to 45°, 2D and 3D models by previous studies suggest that such a non-oblique SPA-forming impact would increase the volume of generated impact melt, excavation depth, and diameter of the transient cavity, albeit only moderately by up to 20%. The energy injected by the SPA-forming event might be smaller in a non-oblique case because the size of the basin is determined only by the vertical component of the impactor trajectory, allowing for a lower impact energy to explain the diameter of SPA. Most decisively, though, a non-oblique scenario would imply a more symmetric distribution of ejecta, predicting an up to 10 km thick blanket at the South Pole, where oblique scenarios estimated only very small amounts of SPA ejecta. This is in agreement with increased olivine abundances in the regolith at the Chandrayaan 3 landing site and would imply SPA ejecta, including materials from the lower crust and upper mantle, to be relatively widespread in the Artemis Exploration Zone.

The value of volume measurement in CT in the follow-up of Stanford B aortic dissection after TEVAR

BackgroundTo investigate the value of dual-source CT combined with volumetric measurement in the follow-up of Stanford Type B aortic dissection (TBAD) intrathoracic aortic repair (TEVAR).Methods40 TBAD patients in our hospital were treated with TEVAR and followed up at 3, 6 and 12 months after surgery. Dual-source CT and volumetric measurements were used to calculate the diameters and areas of the true and false lumen and the total lumen of the left subclavian artery at a distance of 2 cm (P1), the middle part of the descending aorta (P2), the opening of the abdominal trunk (P3) and the anterior bifurcation of the abdominal aorta (P4) before and after surgery. The maximum diameter, maximum area, volume and modified aortic remodeling index (MARI) of the true and false lumen of the distal abdominal aortic dissection were measured to evaluate the postoperative vascular remodeling.ResultsThe true cavity diameter of P1 and P2 increased gradually, the false cavity diameter decreased gradually (P < 0.05), and the total and true cavity diameter of P3 and P4 increased (P < 0.05). After operation, the true cavity area of P1 and P2 gradually increased, and the false cavity area decreased (P < 0.05). The total area of P3, P4, and true cavity increased gradually after operation (P < 0.05). There were statistically significant differences in true and false lumen volume and MARI before and after surgery (P < 0.05).ConclusionCompared with diameter measurement and area measurement, volume measurement can more accurately reflect the remodeling of the true and false lumen of the uncoated aortic dissection.Clinical trial numberNot applicable.

Optical performance enhancement of solar flux distribution uniformity of solar parabolic dish cavity system

The design of the cavity receiver plays a crucial role in the conversion from solar to thermal energy that is absorbed in the cavity receiver to the heat transfer fluid. Nonuniform heat flux at the surface of cavities generates structural failure due to thermal unbalance. This research focuses on the optimization of cavity design based on position, aperture diameter, and eccentricities of elliptical-shaped cavity to enhance the uniformity of solar flux distribution on the cavity walls. The optical analysis is performed using Monte Carlo ray tracing using COMSOL Multiphysics on conical, cylindrical, rectangular, spherical, and elliptical shapes to determine the solar heat flux distribution. The validation of the computational model is performed through published experimental and analytical data. The flux distribution is more dispersed in spherical and elliptical-shaped cavities when positioned above the focal plane. The flux distribution uniformity increases when the cavities are positioned at a higher distance from the focal plane whereas the larger aperture opening eases the absorption of radiation flux on the surface. Partial obstruction of incoming rays starts to occur when positioning the cavity at a higher distance as well as in smaller aperture openings. The optimum configuration of the elliptical cavity is with 30% eccentricity, 100 mm above the focal plane, and 250 mm opening, providing a solar flux distribution uniformity factor of 0.585.

Utilizing metal-organic framework porosity for efficient antibiotic separation and sustained release

Metal-organic frameworks (MOFs) have emerged as a revolutionary class of nanoporous materials due to their highly tunable porosity and functionality. With the vast number of MOFs being discovered, traditional experimental techniques to identify the best candidates for various applications, including water treatment and drug delivery become time-consuming and expensive. This is where computational screening offers a powerful solution. We present a computational screening strategy using Monte Carlo (MC) simulation to identify the promising MOFs among over 14,000 MOFs for efficient absorption, membrane separation, and sustained delivery of antibiotics (e.g., azithromycin, AZ). The MC simulation was used to calculate the loading capacity and isosteric heat of the AZ absorption. These absorption properties were correlated with several structural characteristics of the MOF, including the largest cavity diameter, pore limiting diameter, accessible volume, helium void fraction, etc. Critical evaluation of the correlation results identified the best MOFs for AZ absorption, separation, and delivery. The results recommended a total of 578 MOFs, with 126 identified as suitable for use as AZ adsorbents or drug carriers, and 452 for use as membranes to separate AZ from water. Furthermore, the adsorption mechanism of the top MOF was analyzed using molecular dynamics simulation and non-covalent interactions. The solvation-free energy of AZ was evaluated in various solvents to identify the most effective solvent for extracting AZ from MOFs, thereby facilitating the regeneration of the MOF.

Numerical Simulation on the Influence of the Distribution Characteristics of Cracks and Solution Cavities on the Wellbore Stability in Carbonate Formation

The development of cracks and solution cavities in carbonate reservoirs can notably reduce the rock’s mechanical properties, leading to a severe wellbore collapse problem during drilling operations. To clarify the influence of the characteristics of cracks and solution cavities on the wellbore stability in the Dengying Formation carbonate reservoir in the Gaoshiti–Moxi area of Sichuan, the mechanical properties of carbonate rock were analyzed. Then, the influences of the attitude and width of cracks, the size and quantity of solution cavities, and their connectivity on wellbore stability were studied using FLAC3D 6.00 numerical simulation software. Our results show the following: (1) The cracks and solution cavities in the Dengying Formation carbonate rock cause significant differences in the rock’s mechanical properties. (2) The equivalent drilling fluid density of collapse pressure (ρc) considering the effects of cracks and solution cavities is 6.4% higher than without these effects, which is in good accordance with engineering practice. Additionally, cracks play a more significant role than solution cavities in affecting the wellbore stability. (3) When the orientation of a crack is closer to the direction of maximum horizontal stress, and the dip angle and width of the crack increase, the stress and deformation at the intersection of the crack and wellbore gradually increase, and correspondingly, ρc also increases. (4) The stress and displacement of various points around the solution cavities gradually increase with the increases in diameter and quantity of solution cavities, and ρc also increases. (5) Compared with the situation where cracks and solution cavities are not interconnected, the stress disturbance area around the wellbore is larger, and ρc is greater when cracks and solution cavities are interconnected.

Effectiveness of Intercostal Stretch on Chest Expansion and Peak Expiratory Flow Rate

Introduction: The intercostal muscles play a role in moving the ribs upward and outward. This action leads to an increase in the antero-posterior diameter of the thoracic cavity. In respiratory physiotherapy, manual stretching techniques are widely used to improve lung function Objective: To determine the effect of Intercostal stretch on chest expansion and peak expiratory flow rate. Methods: A total of 100 subjects were recruited according to inclusion criteria i.e.age group 60-70 years, both genders and written informed consent was taken. Assessment and evaluation of participants was done. Chest expansion was measured and then after 2 minutes rest peak expiratory flow rate was taken using peak flow meter before the intervention. The stretch was applied in sync with the patient’s exhalation and held while they continued breathing normally. As the stretch was sustained, there was a gradual increase in inspiratory movements in the area being stretched. Each subject received intercostal stretching for 20 days, with 5 repetitions per session and a 20-second hold on both the right and left sides. After the 20-day period, chest expansion and peak expiratory flow measurements were recorded. Results: By applying Paired t-test for Pre-test and Post-test values of chest expansion and peal expiratory flow rate p-value obtained was &lt; 0.01, which was statistically significant. This suggests that Intercostal stretch is effective in improving chest expansion and peak expiratory flow rate. Conclusion: The study concludes that there was significant improvement in chest expansion and peak expiratory flow rate among the healthy older adults who underwent intercostal stretch.

High-performance metal-organic frameworks for efficient adsorption, controlled release, and membrane separation of organophosphate pesticides

Metal-organic frameworks (MOFs) are considered good choices for the absorption, separation, and release of various substances. The rapid increase in the number of MOFs being produced makes it impractical to conduct experimental research to identify the most promising candidates in these areas. Therefore, computational screening has emerged as a robust approach. We employed this approach to identify the most efficient MOFs for the removal, separation, and controlled release of organophosphorus pesticides, including diazinon, chlorpyrifos, and chlorpyrifos-methyl. From a database of approximately 14,000 MOFs, 584 MOFs with the largest cavity diameters were used in the screening process to evaluate promising candidates for each pesticide. Monte Carlo simulations were used to estimate the pesticide uptake capacities and isosteric heats of the selected MOFs. The structural properties of MOFs were correlated with their adsorption capacities and isosteric heats. Computational screening identified 325, 330, and 450 MOFs as potential absorbents and carriers for diazinon, chlorpyrifos-methyl, and chlorpyrifos, respectively. Additionally, it proposed 235, 254, and 135 MOFs as membranes for the effective separation of these organophosphorus pesticides. The reactivity of the pesticides was explored using quantum mechanics calculations. Molecular dynamics simulations of the top three MOFs with high uptake capacities for each pesticide were performed and analyzed to understand the interactions between the MOF, pesticide, and water molecules. The solvation-free energies of the pesticides were calculated for various solvents to identify the most effective solvent for desorbing pesticides from the MOFs, thereby enabling MOF regeneration.

Impact of design variations of a micro-perforated panel on psychoacoustic metrics of transmitted sound

Recent work reveals that sound travelling through metamaterials can lead to changes in sound perception [L. De Ryck et al., Proceedings of ISMA and USD, pp. 1147–1162 (2018)]. As a starting point unravelling the impact of intricate vibro-acoustic design on perception, this study investigates the relationship between the intrinsic physical properties of micro-perforated panels (MPP) and several psychoacoustic metrics (loudness, sharpness, prominence ratio, and speech intelligibility index) in sound transmission conditions. A Sobol global sensitivity analysis is performed to quantify the impact of variations in MPP design parameters—panel thickness, perforation rate, hole diameter, and air cavity depth between panels—on these sound quality metrics [I. M. Sobol, MATCOM 55, 271–280 (2001)]. The analysis is conducted using both broadband and narrowband noise stimuli. The data trends suggest that the psychoacoustic effects of MPP acoustic treatments exhibit a non-trivial dependence on specific parameters of the panel setup. This also provides a framework towards innovative material design, where desired psychoacoustic metrics can help guide the manufacturing of metamaterials in order to meet specific sound quality targets. [The European Commission is gratefully acknowledged for its support of the Marie Sklodowska Curie program through the Horizon Europe DN METAVISION project (GA 101072415).]

Development of diesel combustion with low cooling loss and high dispersion spray using two-dimensional optical measurements

In this study, a novel, high-efficiency, and clean combustion concept utilizing low cooling loss and high dispersion spray is proposed. The research aims to validate the objectives of this concept through spatiotemporal analysis of phenomena when key variables such as combustion chamber shape, spray parameters, and swirl are modified. This new combustion approach focuses on achieving low heat loss by using smaller nozzle diameters, multi-hole nozzles, and reduced swirl compared to conventional combustion. The combustion chamber is designed with an increased cavity diameter and an expanded taper diameter to enhance upward spray dispersion, thereby reducing fuel spray penetration into the cavity and decreasing cooling loss. This configuration reduces the fuel spray penetration in cavity, achieving a reduction in cooling heat loss. Furthermore, to increase the volume in the lower part of the combustion chamber, a corner-bottom shape is employed. Additionally, by causing spray impingement through the corner bottom shape, the strategy aimed to prevent the return of the mail injections to the central part of the combustion chamber. These parameters were evaluated using two-dimensional optical measurements, which calculated thermal flux, temperature, velocity, and KL value distributions. The impact of cavity diameter on internal cooling loss is significant, and preventing flame stagnation from a smoke perspective is crucial. An increase in taper diameter reduces squish velocity, achieving heat losses reduction, while necessitating spray dispersion into the squish area. The influence of swirl ratio on heat losses is more pronounced in the squish and taper areas than inside the cavity, necessitating consideration of flame temperature reduction within the cavity when reducing swirl ratios. The implementation of double after injection influences low heat losses and avoids flame stagnation, enabling soot reduction. The corner bottom shape combustion chamber proved effective in reducing heat losses and particulate matter (PM) at medium and high loads.

Исследование изменения геометрии внутренней полости передающих устройств для гидроструйных технологий с целью улучшения их теплового состояния

The paper is devoted to the study of the influence on changes in their thermal balance during operation by improving the cooling conditions of sections of the drill shaft with contact surfaces of changes in geometric characteristics, such as diameter and length, of the internal cavity for supplying working fluid in high-pressure hydro-puller device for hydro-jet technologies. The axisymmetric simulation not on a full-size transmit-ting device was carried out, but on one-eighth part in order to reduce the time of both creating the model itself and the amount of calculations. A model created in the computing environment «Ansys» with a computational grid for calculating equivalent stresses is shown. The stress distributions calculated by the finite element method for various combinations of the geometry of the transfer device revealed the corresponding boundaries for the rational change in the diameter and length of the internal cavity, allowing to ensure its operability of the structural unit in combination with maximum cooling of the most thermally loaded sections of the shaft. Dimensionless geometric parameters (reduced diameter and reduced length of the internal cavity) are introduced for a general description of the geometry of transmitting devices for hydro-jet technologies. Graphs of the dependences of voltage values on the given values were obtained.

Determination and Analysis of Endogenous Hormones and Cell Wall Composition between the Straight and Twisted Trunk Types of Pinus yunnanensis Franch

Pinus yunnanensis Franch., one of the pioneer species of wild mountain afforestation in southwest China, plays an essential role in the economy, society and environment of Yunnan Province. Nonetheless, P. yunnanensis’ trunk twisting and bending phenomenon has become more common, which significantly restricts its use and economic benefits. In order to clarify the compositional differences between the straight and twisted trunk types of P. yunnanensis and to investigate the reasons for the formation of twisted stems, the present study was carried out to dissect the macroscopic and microscopic structure of the straight and twisted trunk types of P. yunnanensis, to determine the content of cell wall components (lignin, cellulose, hemicellulose), determine the content of endogenous hormones, and the expression validation of phytohormone-related differential genes (GA2OX, COI1, COI2) and cell wall-related genes (XTH16, TCH4). The results showed that the annual rings of twisted trunk types were unevenly distributed, eccentric growth, insignificant decomposition of early and late wood, rounding and widening of the tracheid cells, thickening of the cell wall, and reduction of the cavity diameter; the lignin and hemicellulose contents of twisted trunk types were higher; in twisted trunk types, the contents of gibberellin (GA) and jasmonic acid (JA) increased, and the content of auxin (IAA) was reduced; the GA2OX were significantly down-regulated in twisted trunk types, and the expressions of the genes associated with the cell wall, COI1, COI2, TCH4 and XTH16, were significantly up-regulated. In conclusion, the present study found that the uneven distribution of endogenous hormones may be an important factor leading to the formation of twisted trunk type of P. yunnanensis, which adds new discoveries to reveal the mechanism of the genesis of different trunk types in plants, and provides a theoretical basis for the genetic improvement of forest trees.

The utility of MOF-based materials in direct air capture (DAC) application to ppm-level CO2

Metal-organic frameworks (MOFs) are well-suited materials for CO2 removal and have robust capture capacity and selectivity. Although the adsorption of CO2 in MOFs has been studied, the implementation of ppm-level CO2 uptake in MOFs and the effects of the pore size and charge have not been fully explored. We performed grand canonical Monte Carlo (GCMC) simulations combined with the Density Functional Theory plus U (DFT + U) charge method to investigate MOF screening for ppm-level CO2 uptake and its application in a direct air capture (DAC) system. Three types of MOFs containing eight members were studied: i.e., ZIF-68, 69, 70; UiO-66, 67, 68; CAU-10; and MIL-125. The pore landscape characterization, electrostatic field-induced enhancement, and preferential binding sites of these MOFs were examined for CO2 capture. MOFs with pore limited diameters (PLD) 1.5 times the size of CO2 molecules and with large cavity diameters (LCD) smaller than 10 Å exhibit robust confinement capacity. Polar functional groups and metal ions dominate the electrostatic contributions and subsequently enhance the surface adhesion of CO2 molecules. For a given framework, favorable CO2 binding occurs in the following order: small pores/cages > polar functional group/metal ions > larger pores/cages. ZIF-69 which comprises smaller pores (7.5 Å) and robust polar functional groups (–Cl) collectively enhances CO2 capture; thus, ZIF-69 outperforms other MOFs; the performance of ZIF-69 is followed by that of CAU-10 which has an optimal pore size of 6 Å. These findings are of fundamental and practical importance for the application of MOFs in DAC technologies for CO2 removal.

Self-excited oscillation characteristics and mechanisms of supercritical CO2 flowing in a Helmholtz oscillator for enhancing heat transfer

The drastic variations in thermal properties of supercritical CO2 near its pseudo-critical point induce the formation of complex boundary layer structures within pipelines, rendering it susceptible to heat transfer deterioration under the influence of buoyancy forces. The Helmholtz self-excited cavity can generate self-excited pulsating jets, enhancing the intermixing between fluids inside the heat exchanger tubes, disrupting the thermal boundary layer, and suppressing heat transfer deterioration. In this study, the characteristics and mechanisms of self-excited oscillations of supercritical CO2 flowing vertically upward in the Helmholtz self-excited cavity were investigated using the large eddy simulation (LES) method. A detailed analysis of cavitation and vortex evolution within the cavity was conducted, along with an exploration of the influence of inlet pressure and structural parameters on the frequency characteristics of pulsations. The results indicate a close relationship between cavitation and vortex interactions and the pulsation frequency. An increase in inlet pressure leads to a significant cavitation phenomenon near the jet shear layer and an increase in vortex frequency. Dimensionless cavity length (Lc/d1) enlargement results in an increase in outlet pulsation frequency but a decrease in pulsation amplitude. The critical dimensionless ratio of cavity diameter (Dc/d1) plays a crucial role in maintaining the desired pulsation frequency and amplitude. Within the working range outlined in this paper, practical insights for system design and operation are provided by the optimal parameters of Lc/d1 = 3 and Dc/d1 = 10.

The Research on Self-Excited Oscillating Jet Cleaning Technology

Abstract Self-oscillating nozzles have gained wide popularity due to their ability to generate powerful impact forces, long-range projection, and concentrated, stable jets in applications such as water-jet drilling and rust removal. However, the nozzle’s efficient operation relies heavily on specific structural designs and operational parameters, which necessitates further indepth research. By studying the characteristics of self-excited oscillating pulse cavitation jet within the nozzle cavity structure. Analyzing the evolution characteristics of internal flow field. Solving optimization problems in a targeted manner. The purpose of this study is to reveal the resonance principle behind the self-excited oscillation of nozzle. It also explores the regularities of the effects that the cavity diameter has on jet performance, ultimately seeking to find the optimal configuration of nozzle structure and operating conditions.

214. THORACIC CAVITY/ CAGE RATIO IS PREDICTOR FOR SURGICAL DIFFICULTY OF MINIMALLY INVASIVE ESOPHAGECTOMY

Abstract Background Esophagectomy for esophageal cancer is highly invasive surgery. Minimally invasive esophagectomy (MIE) was introduced as a less invasive surgery, and conventional MIE (C-MIE) is being increasingly performed worldwide. Recently, robot-assisted MIE (RAMIE) was developed with the aim of further minimization of invasiveness, and is expected to spread in the future. When performing MIE, we sometimes experienced difficult cases. In this study, we aimed to clarify the factors related to surgical difficulty of MIE. Methods We evaluated 362 patients who underwent MIE (285 C-MIEs and 77 RAMIEs) for esophageal squamous cell carcinoma between April 2010 and February 2023. We used computed tomography to evaluate the occipitofrontal diameter of thoracic cavity and cage at brachiocephalic vein (BV), tracheal bifurcation (TB) and inferior right pulmonary vein (IRPV) levels, respectively. We calculated the thoracic cavity/cage ratio (TRRC) at each level. The cut-off values of TCCR at each level for thoracic procedure time were calculated using the receiver operating characteristic. Furthermore, total score consisted of four degrees (0,1,2,3) by the TCCR at three levels was calculated. We assessed clinicopathological and anatomical factors and determined the independent factors influencing the thoracic procedural time as parameter of difficulty in MIE. Results We divided the patients into C-MIE group and RAMIE group. Patients in each group were divided into two cohorts according to median thoracic procedure time (C-MIE: 307 and RAMIE: 409 minutes, respectively). In the C-MIE group, univariate analysis demonstrated that sex, body mass index (BMI), and the TCCR at BV, TB and IRPV levels were correlated with thoracic procedure time. The total TRRC score was also correlated with thoracic procedure time in univariate analysis. Next, multivariate analysis was done using sex, BMI, and the total TCCR score. Multivariate analyses demonstrated that BMI (p = 0.0005) and the total score (p = 0.0069) were independent factors for thoracic procedure time. In the RAMIE group, univariate analysis demonstrated that BMI and the TCCR at BV and TB levels were correlated with thoracic procedure time. Multivariate analyses demonstrated that the TCCR at TB level (p = 0.0187) was only independent factor for thoracic procedure time. Conclusions The TCCR and the total score based on it could be useful in assessing surgical difficulty of both C-MIE and RAMIE. C-MIE was affected by the diameter at all levels of the thoracic cavity due to restricted mobilities of thoracoscopic instruments. On the other hand, RAMIE’s articulated forceps prevent it from being affected by entire thoracic cavity. Consequently, only the TCCR at TB level, which is one of the most less flexible field, affects the difficulty in RAMIE.

The investigation of double wall cooling configuration with spherical cavity

Double wall cooling is an efficient cooling method for turbine blade. Commonly used double wall cooling configurations contains a cubic cavity between two walls. Chaos flow flied in the cavity impedes heat transfer. In this research, a new spherical cavity was proposed, traditional cubic cavity was replaced by several spherical cavities, film hole located on the top of spherical cavity, and impact hole located at the button of spherical cavity. Adjacent spherical cavities were connected by channel. Different spherical cavities were established and numerical simulation was used to check their performance. The influence of blowing ratio, channel, film hole diameter, spherical cavity diameter was analyzed. The performance of cavities was also compared with common double wall cooling configurations. According to the result, when blowing ratio was 0.3, spherical cavity increased cooling effectiveness by 45.6% maximumly compared to common configurations. As for coolant consumption, spherical cavity needs less coolant than common configurations to achieve the same cooling effectiveness. What's more, film hole located at −45° position was benefit for cooling, and cooling effectiveness would increase further when spherical cavity diameter was enlarged.