Bottom Of Cavity Research Articles

Cavity length downstream of a sudden fall-expansion aerator in chute

Abstract Cavity length has been proven to have a significant effect on the air entrainment of an aerator in flood discharge engineering; however, the estimation of both the bottom and lateral cavity lengths downstream of a sudden fall-expansion aerator remain unclear. This research conducts a series of experiments involving various approach-flow conditions and geometric parameters of an aerator. An improved solution of the cavity length for the bottom and lateral cavities is established. The proposed equation was validated through the data of experiments and predecessor formulas, and exhibited a higher precision than other methods. Both the transverse turbulence and the axial dynamic pressure are found to be related to the formation of a lateral cavity. The present method involving the lateral cavity length was developed based on dimensional analysis and experimental test. The geometric morphology of a lateral cavity exhibits a parabolic shape, which is similar to that of the bottom cavity.

Mixed Convection in a Cavity Saturated with Wavy Layer Porous Medium: Entropy Generation

In this paper, the effects of the wavy nanofluid/porous interface on the mixed convection and entropy generations of Cu–water nanofluid in a horizontally partitioned non-Darcy porous double lid-driven cavity are investigated. The bottom cavity wall is heated, and the top wall is cooled. Both of the left and right walls are adiabatic. The upper and the lower parts of the square cavity are filled with the nanofluid. The wavy middle part of the cavity is filled with the non-Darcy porous medium. The effects of the fundamental parameters were studied, including Reynolds number, Richardson parameter (), and Darcy parameter () as well as nanofluid/porous interface parameters including the porous media height (), nanofluid heights, the amplitude of wavy interface (), and the number of interface undulations (). It is found that the decrease of the Darcy parameter brings a big resistance force for the fluid flow, an increase in the heat transfer by conduction, and a significant decrease in the irreversibility due to the heat transfer. And the effects of the nanoparticle concentrations depend on the convection mode. The average Bejan number is close to unity at forced convection mode.

软弱基座型高边坡危岩演化及应力场分析

危岩崩塌具有爆发突然、难以预测、危害性大等特点，准确合理推断危岩崩塌演化发展过程及趋势成为预防和治理危岩崩塌的关键性问题。以黄泥堡高边坡危岩为依托，结合现场工程地质调绘，通过分析高边坡危岩体的结构特征，得出近水平层状软弱基座型危岩体悬臂–拉裂式破坏模式；运用地质学基础理论，分析阐述高边坡危岩体崩塌的形成及演化发展过程的四个阶段；在此基础上，推导出评价危岩崩塌稳定性的表达式；采用数值模拟方法对依托工程实例进行应力场模拟分析，研究地应力场的演化特征。结果表明，岩腔底部产生应力集中现象，并且随着岩腔的发展加深而越来越明显。为高边坡危岩稳定性评价以及治理措施提供指导和借鉴。 Perilous rock and collapse is provided with characteristics of sudden outbreak, unpredictable, harmful and so on, accurately and reasonably infer the process and trend of the evolution of pe-rilous rock and collapse is the key issues for the prevention and treatment of rock collapse. In this paper, based on the high rock slope of Huang Nibao, combined with the site engineering geological mapping, the structural features of dangerous rock mass in high slope is analyzed, and the cantilever-rupture failure mode of the near horizontal layered perilous rock in soft foundation is obtained. Based on the basic theory of geology, the four stages of the formation and evolution of the perilous rock and collapse are analyzed and explained. On the basis of this, the expression of the stability for the perilous rock and collapse is derived. Based on the engineering example, the numerical simulation method is used to analyze the stress field, and study the evolution characteristics of the stress field. The results show that, the stress concentration occurs at the bottom of the rock cavity and becomes more and more obvious as the rock cavity deepens. It provides guidance and reference for the stability evaluation and treatment measures of perilous rock in high slope.

Investigation of Flow Behavior of Joule-Heating Flow in a 2-D Model of a Reprocessing Glass Melter Cavity

Flow behavior was observed in a simplified model cavity of a multiphase High Level Liquid Waste (HLLW) reprocessing glass melter. Electrodes were set to generate Joule-heating flow in the cavity. A chaotic flow occurred because the lower part of the cavity was heated while the top surface of the cavity was cooled. Downflow and upflow occurred alternately in cavities. The shape of the cavity was a sloping bottom cavity, which was similar in shape to the real glass melter. To know the flow behavior in the cavity, 1-D flow behavior and 2-D flow behavior were measured in an experiment and simulated by an original CFD code. In the sloping bottom cavity, chaotic flow occurred in the upper part of the cavity. In the case of the sloping bottom cavity which had the same set of electrodes as the glass melter, the effect of the downflow near the electrodes decreased. The same phenomena could be predicted in the melter. The experimental results were also used to validate the CFD code, which will be helpful for developing a multiphase Joule-heating flow predicting.

Question of the Etiology of Malignant Neoplasms

Purpose. To determine the severity of potentiometric parameters in patients with malignant neoplasms of the oral mucosa and the presence of metal inclusions in the form of non-removable dentures made of dissimilar metals and their alloys. Methods. We examined of potentiometric parameters in 39 patients with metallic inclusions in the oral cavity, in which malignant tumors of the mucous membrane of the oral cavity (tongue, palate, mucous membrane of the alveolar process and the bottom of the oral cavity) were detected. All subjects were between the ages of 40 and 68 years. Results. High potentiometric indicators were revealed in patients with non-removable metal dentures, which are made of dissimilar metals and their alloys. The presence of defects in the lining of dentures, as well as metal parts of a non-removable structure or metal protective coating ("bald zones") increase the potentiometric parameters and increase the risk of malignant neoplasms of the mucous membranes. Conclusions. The presence of metal inclusions in the oral cavity in the form of permanent dentures can be one of the reasons for the development of malignant neoplasms of the mucous membranes. A significant increase (more than 3 times higher than the normal values) of potentiometric parameters in patients with malignant tumors of the mucous membranes with metallic inclusions in the oral cavity is observed not only between the metals of immovable dentures, but also between the metal denture and the mucosa of the alveolar process of the jaw, between different parts of the mucous membranes of the alveolar process.

Effect of the background gas pressure on the effectiveness of laser-induced material removal from deep cavities in irradiated targets

Two-dimensional expansion of a plume, induced by short-pulse laser irradiation of a bottom of a cylindrical cavity in a copper target, into argon background gas at pressure ranging from 0 to 1 bar is studied numerically based on a hybrid computational model that includes a heat conduction equation for the irradiated target and a kinetic model of the gas mixture flow. It is found that an increasing pressure of non-reactive background gas can induce an order-of-magnitude increase in the effectiveness of removal of the laser ablation products from the cavity as compared to ablation under vacuum conditions. The effectiveness of the material removal, measured as the ratio of the mass of the ablated products leaving the cavity to the evaporated mass, is determined by the interplay between the confinement and focusing effects of the background gas, which decelerate the plume expansion and concentrate the ablation products far from the cavity wall, correspondingly. At small background gas pressure, the plume expansion is dominated by the focusing effect, which enhances the efficiency of the material removal. At large pressure, the confinement effect dominates and suppresses the material removal. As a result, there is an optimum background gas pressure that maximizes the efficiency of the material removal from the cavity. This optimum background gas pressure depends on the characteristic pressure in the plume and strongly increases with an increase in the absorbed intensity of laser radiation.

Collapse-driven formation of depressions on comet 67P/Churyumov–Gerasimenko

The extremely diverse surface of comet 67P/Churyumov–Gerasimenko contains a large number of depressions or craters of very different scales. Among the most prominent are two large roughly circular depressions, each with radii of several hundred meters. In this work a model for the formation of the depressions is proposed. It is based on the theory of the deformation of a thin circular elastic plate under its own weight. The plate covers a circular cavity with a given radius. The resilience of the plate diminishes over time as a result of its thinning which is itself a consequence of sublimation. When the stress limit is achieved, a gravitational collapse occurs: the plate cracks and the remnants fall into the cavity bottom. A formula that links the radius of the plate corresponding to collapse with the plate thickness has been derived. The formula was discussed for the large intervals of the values of parameters that characterize surface layers of cometary nuclei. It was found that the surface above large cavities collapses sooner than one of a similar thickness that covers a smaller cavity. So, if the collapse mechanism theory works, that larger depressions are therefore older than smaller ones.

АНОМАЛАД П’ЄРА-РОБЕНА В КЛІНІЧНІЙ ПРАКТИЦІ ПЕДІАТРА

Уроджена вада щелепно-лицевої ділянки з вираженим недорозвитком нижньої щелепи як наслідок зменшення ротової порожнини і западання язика перешкоджає змиканню піднебінних пластинок з формуванням щілини м’якого піднебіння, що часто поєднується з множинними іншими аномаліями. В основі даного синдрому лежить аномалія росту і розвитку зародка, що характеризується порушенням розвитку початкового зародкового стану (внаслідок вади першої зябрової дуги). Язик розміщений сильно назад, досягаючи синусів носа, між глотково-піднебінними дужками, які орієнтовані сильно вниз. Розвиток цих аномалій зумовлений деякими інфекціями матері під час вагітності або нейрогенетичними порушеннями, наявністю механічної компресії всередині матки, а також вони можуть виникати внаслідок сімейної спадковості (на їх користь вказують вади обличчя в деяких членів однієї чи іншої родини). Основні діагностичні критерії: мікрогнатія (мала, коротка нижня щелепа) та (або) ретрогнатія (запала нижня щелепа). У хворого характерний профіль, подібний на пташиний рот, «пташине обличчя», рот до кінця не закривається, тому його називають «ротом акули»; глосоптоз (недорозвиток та западання язика) – невелика і втягнута нижня щелепа не може тримати язика в нормальному положенні, так що він впадає назад у гіпофаринкс, здавлюючи надгортанник, який відіграє роль клапана та перешкоджає проникненню повітря, одночасно порушується і ковтання. Іноді відмічається макроглосія, язик прирощений до м’яких тканин дна ротової порожнини; щілина м’якого піднебіння або «стрілчате піднебіння» (одно- чи двобічне незрощення). Усі ці аномалії спричиняють респіраторний дистрес-синдром, порушення дихання, неспокій, диспное з брадипное, постійний ціаноз, які особливо виражені при положенні дитини на спині, асфіксію при годуванні дитини, утруднення чи неможливість ковтання, блювання, з часом – атрепсію і порушення окостеніння. Ізольовані випадки аномаладу П’єра Робена завжди спорадичні. Аномалад є складовою частиною синдрому множинних уроджених вад розвитку, успадкування визначається залежно від типу успадкування основного синдрому. Актуальними при даному синдромі є виключення всіх несприятливих факторів у допологовий період розвитку дитини, пренатальна діагностика, проведення медико-генетичного консультування з метою попередження народження дитини зі спадковим захворюванням.

Improved Oxygen Reduction Reaction Performance of Co Confined in Ordered N-Doped Porous Carbon Derived from ZIF-67@PILs

Diffusion and activation of reaction species are two critical factors of oxygen reduction reaction (ORR). Diffusion property is essentially dominated by transmission of reaction species in the channel of catalysts. Herein, we report a facile method to prepare ordered-carbon coated Co nanoparticle (Co@O-NPC). Specifically, we mixed ZIF-67 MOF microcrystal into an ionic liquid monomer which resulted in ZIF-67@PILs composites. Subsequently, Co@O-NPC was obtained by the high-temperature pyrolysis of ZIF-67@PILs. Electrochemical measurements show that it possesses superior ORR property compared to commercial Pt/C. A combination of molecular dynamics (MD) calculations and contrast experimental results reveals that the ordered porous carbon structure can improve the diffusivity of reaction species more effectively than disordered carbon, thereby enhancing ORR property. Moreover, DFT calculation results demonstrate that the catalytically active sites are located on the cavity bottom of Co@O-NPC and uncover the sy...

Natural convective heat transfer through two entrapped triangular cavities filled with a nanofluid: Buongiorno's mathematical model

Free convection of water based nanofluid inside two entrapped triangular cavities under the effects of Brownian diffusion and thermophoresis is numerically studied. The bottom and upper walls of the cavities are kept at high constant temperature while the rest walls are kept at low constant temperature. Dimensionless governing equations formulated using stream function, vorticity, temperature and nanoparticles volume fraction have been solved by finite difference method of the second order accuracy. The effects of the Rayleigh number, Lewis number and buoyancy-ratio parameter on fluid flow, heat and mass transfer have been analyzed. It has been found that, taking into account the used temperature boundary conditions, the bottom triangular cavity is more sensitive to changes of the Rayleigh number and buoyancy-ratio parameter, while the upper cavity is not so sensitive to changes of these parameters. In addition, an increase in the Rayleigh number and buoyancy-ratio parameter reflects non-uniform distributions of nanoparticles inside cavities.

Research on dual-polarized circular waveguide antenna fed by L-shaped probes

This paper researched a kind of dual-polarized and cylindrical waveguide antenna fed by two L-shaped probes at the antenna bottom. The designed antenna was composed of two orthogonal L-shaped coaxial probes and a cylindrical waveguide cavity. The two orthogonal field structures were excited and the dual-polarized radiation mode was formed. The feeding cables of two polarization ports went through the bottom of the cylindrical cavity and were connected with the microwave adaptors. The bottom feeding structure was suitable to constitute a planar antenna array. The electromagnetic simulation and optimization design of the proposed antenna were carried out by using the full wave electromagnetic simulation technique, and the simulation results showed that the isolation between two polarization ports were more than 20dB within the frequency range of 4.8–5.4GHz. At the center frequency, the cross-polarization levels of radiation pattern were lower than −21dB at the boresights and the beam width of radiation patterns at E-plane and H-plane were more than 70° for two polarization ports. The designed antenna in this paper was fabricated and measured. The measurement results indicated that the designed antenna achieved anticipated radiation performances and design effectiveness of the dual-polarized antenna in this paper was proved. The dual-polarized and cylindrical waveguide antenna is suitable for some application fields such as dual-polarized array radar. The research results in this paper can provide a technical basis for the practical engineering application.

Characteristics of aeration in the flow downstream of a radial gate with a sudden fall-expansion aerator in a discharge tunnel

Abstract The mechanisms of cavitation damage in flood releasing tunnels remain unclear. In this study a series of physical experiments and numerical calculations were conducted to investigate the flow pattern, pressure distribution and cavitation downstream of a sudden fall-expansion aerator in a discharge tunnel. When the radial gate was partly open, the bottom cavity length reduced drastically, the lateral cavity disappeared, and the flow cavitation index near the sidewalls was less than 0.2. The pressure on the floor and sidewalls can be divided into four regimes: the cavity regime, the impact regime, the reflective regime and the stable regime. The time-average pressure is subject to a unimodal distribution when the gate is fully open, whereas a bimodal distribution is presented when the gate is partly open. The negative pressure regime presented an elliptic shape. Cavitation erosion occurred easily on lateral expansion sidewalls in the tunnel with the radial gate partly open.

A robust higher order compact scheme for solving general second order partial differential equation with derivative source terms on nonuniform curvilinear meshes

A fourth order compact finite difference scheme is proposed for solving general second order steady partial differential equation (PDE) in two-dimension (2D) on geometries having nonuniform curvilinear grids. In this work, the main efforts are focused not only on nonorthogonal curvilinear grids but also on the presence of mixed derivative term and nonhomogeneous derivative source terms in the governing equation. This is in turn suitable for solving fluid flow and heat transfer problems governed by Navier–Stokes(N–S) equations on geometries having nonuniform and nonorthogonal curvilinear grids. The newly proposed scheme has been applied to solve general second order partial differential equation having analytical solution and some pertinent fluid flow problems, namely, viscous flows in a lid driven cavity such as trapezoidal cavity using nonorthogonal grid, square cavity using distorted grid, complicated enclosures using curvilinear grid, and mixed convection flow in a bottom wavy wall cavity. It is seen to efficiently capture steady-state solutions of the N–S equations with Dirichlet as well as Neumann boundary conditions. Detailed comparison data produced by the proposed scheme for all the test cases are provided and compared with existing analytical as well as established numerical results available in the literature. Excellent comparison is obtained in all the cases.

THE CLINICAL AND LABORATORY TESTS OF THE EFFECTIVENESS OF KRIOCYSTEKTOMY OF ODONTOGENOUS CYSTS, OVERGROWN THE BOTTOM OF THE MAXILLARY SINUS

For the purpose of an increase in the effectiveness in the treatment of odontogenous cysts in the region of upper jaw and preventive maintenance of different complications we have proposed the procedure of kriocystektomy. The clinical laboratory testing of the effectiveness of its use with the application of roentgenography, densitometry, laser thermometry of gum into the region of the arrangement of cysts, the results of investigating of S-reactive protein (mg/ml), factor of the necrosis of tumor (FNO-α, pg/ml), it is lactoferrini, a quantity of factor of an increase in the fibroblasts -β - of oFRF-β (ng/ml) they showed the normalization of all indices on 30 day after operation in all 33 inspected patients with the odontogenous cysts, which germinate the bottom of the upper maxillary cavity and nasal cavity. Obtained data are the highly informative proof of simplicity, rationality and safety of the developed regime of kriocystektomy during the reatment of odontogenous cysts.

The thermal neutron facility HOTNES: theoretical design

HOTNES (HOmogeneous Thermal NEutron Source) is a thermal neutron irradiation facility with extended and very uniform irradiation area. A 241Am-B radionuclide neutron source with nominal strenght 3.5×106 s−1 is located on bottom of a large cylindrical cavity (30cm diameter, 70cm in height) delimited by polyethylene walls. The upper part of this volume (30cm diameter, 40cm in height) is used to irradiate samples. A polyethylene cylinder, acting as shadowing object, prevents fast neutrons to directly reach the irradiation volume. Indeed neutrons can only reach the irradiation volume after multiple scattering with the cavity walls. The facility was designed trough extensive calculations with MCNPX. Irradiation planes are disks with 30cm diameter, centred on the cavity axis, and parallel to the cavity bottom. The value of thermal fluence in a given irradiation plane is as uniform as 1–2%. The value of thermal fluence rate simply depends on the height from the cavity bottom. Values of thermal fluence rate in the range 700–1000cm−2s−1 are available, depending on the irradiation plane chosen. The fraction of thermal neutrons is in the order of 90%, also depending on the irradiation plane. The angular distribution of thermal neutrons is roughly isotropic. Taking advantage of the HOTNES design, even large devices can be uniformly irradiated.This work presents HOTNES's design and describes the neutron field in the irradiation volume in terms of spatial, energy and direction distributions.

Comparison of digital panoramic radiography versus cone beam computerized tomography for measuring alveolar bone

BackgroundCone beam computerized tomography (CBCT) has been widely used in dental implanting. However, the local hospitals usually don’t have access to CBCT due to the cost and medical investment, especially in West of China. The doctors in local hospitals have to make reasonable dental planting using orthopantomography (OPG) to reduce risks. Therefore, it is clinically meaningful to determine the magnification rate of OPG to obtain correct diagnosis. This study investigated the magnification rate of OPG in measuring different maxillofacial loci compared with CBCT.MethodsEighty-six patients demanding dental implanting were scanned by CBCT and OPG. The vertical distance between the alveolar ridge crest of the maxillary first molar and the sinus bottom of the upper jaw, the distance between the alveolar ridge crest of the mandibular first molars and the top of nerviduct in the mandibular alveolar, and the distance between the alveolar ridge crest of the maxillary central incisors and the bottoms of the nasal cavities were measured. The horizontal distance in those loci were also measured. The distances derived from CBCT were used as reference. The distances between the two methods were compared using paired t-test. The magnification rates at these positions were calculated. The relationship between the data acquired from the two methods was analyzed Pearson correlation.ResultsThe correlation coefficients (R) between the paired samples obtained from OPG and CBCT were highly related (P < 0.05) with R values varying from 0.840 and 0.959 in vertical distances and R values varying from 0.703 and 0.904 in horizontal distances. Compared with data obtained from CBCT, the mean vertical magnification rates were 11.38% and 12.95% vertically and 8.55% and 9.43% horizontally for the first molars in the right and left maxilla respectively; 7.26% and 6.35% vertically and 5.33% and 4.96% horizontally for the first molars in the right and left mandible respectively; and 5.55% and 4.84% vertically and 6.53% and 7.47% horizontally for the central incisors in the upper right and left jaws respectively.ConclusionThe magnification rates of OPG at these teeth are different. The distances measured by OPG were highly correlated with that measured by CBCT.

Numerical study of the droplet impact onto liquid film on the rough solid surface via lattice Boltzmann method

The process of the droplet impact onto the liquid film on the rough solid surface, as one of the basic multiphase problems, is very important in many fields of science and engineering. On the other hand, the problem is also very complicated since there are many parameters that may influence the process of the droplet impact on the rough solid surface with a liquid film. Up to now, there are still little research on this problem, and to gain a better understanding on the physical mechanics of the droplet impact onto the film on the rough solid surface, it is desirable to conduct a detailed study. To clearly understand the physical phenomena appearing in the process of droplet impact on the liquid film, a parametric study on this problem is also carried out based on a recently developed lattice Boltzmann method in which a MRT lattice Boltzmann model is used to solve the Navier-Stokes equations, and the other is adopted to solve the Cahn-Hilliard equation that is used to depict the interface between different phases. In this paper, the effects of the relative thickness of film ( h ), the relative width of cavity ( d *) and the relative depth of cavity ( L *) on the dynamic behavior of interface are investigated in detail, and the velocity and pressure fields are also presented. In order to reduce the influence of lattice, we fix the lattice to be 600×120 for gas, which is fine enough to give accurate results. In addition, in our simulations, We =500, Re =480, viscosity ratio and density ratio are set to be 2:1. The numerical results first show that, the phenomena of crown and entrainment can be observed obviously during the process of droplet impact onto the liquid film on the rough interface when We and Re are large. The radius of spray ( r ), which is formed by the droplet impact onto liquid film, is related to time through the relation r / 2 R ≈ α U t / 2 R when h is small, which is coincident with the result of droplet impact onto the liquid film on smooth surface, and additionally the coefficient α would decrease with the increase of h . However, this relation seems not accurate for the case with a large h , and simultaneously, the splashing phenomenon has not been observed. Secondly, the relative width of cavity d * plays an important role on the phenomena of splashing. When d *=1, there will be two small droplets through the splashing phenomenon (left half part), then with this parameter increase, the number of small droplet and the point where the splashing occur will also change, and there also are much difference in relation of spray radius and time. Actually, if d * is small, the coefficient α would first decrease and then increase with the increase of d *, while if d *>8, the cavity width would only have a little influence on the behavior of spray. Finally, it is also found that the pressure change near the cavity bottom is small at different L *, that is to say, the relative depth of cavity L * seems to has no apparent effect on the formation of spray, but it brings a great influence on the splashing of spray and the movement of the droplet which is produced in the process of splashing.

Control of Tip Leakage in a High-Pressure Turbine Cascade Using Tip Blowing

Blowing from the tip of a turbine blade was studied experimentally to determine if total pressure loss could be reduced. Experiments were done with a linear cascade in a low-speed wind tunnel. Total pressure drop through the blade row and secondary velocity fields in the passage between two blades were measured. Cases were documented with various blowing hole configurations on flat and squealer tipped blades. Blowing normal to the tip was not helpful and in some cases increased losses. Blowing from the bottom of a squealer cavity provided little benefit. With a flat tip, blowing from holes located near and inclined toward the pressure side generally reduced total pressure drop by reducing the effect of the tip leakage vortex. Holes near the axial location of maximum loading were most helpful, while holes closer to the leading and trailing edges were not as effective. Higher jet velocity resulted in larger total pressure drop reduction. With a tip gap of 1.5% of axial chord, jets with a velocity 1.5 times the cascade inlet velocity had a significant effect. A total pressure drop reduction of the order 20% was possible using a jet mass flow of about 0.4% of the main flow. Jets were most effective with smaller tip gaps, as they were more able to counter the leakage flow.

Study of Starting Problem of Axisymmetric Divergent Dual Throat Nozzle

Compared to the conventional axisymmetric dual throat nozzle, the axisymmetric divergent dual throat nozzle (ADDTN) can offer larger thrust vector angles. However, the starting problem maybe exists in the ADDTN and results in a huge thrust loss. In this paper, the ADDTN starting problem has been studied by steady and unsteady numerical simulations. The effects of nozzle geometric parameters on internal nozzle performance have been discussed in detail, including cavity divergence angle, cavity convergence angle, cavity length, expansion ratio, rounding radius at the nozzle throat, and rounding radius at the cavity bottom. And, the shock oscillation phenomenon is found inside the recessed cavity in some high-expansion ratio configurations. In addition, a bypass is proposed in this study to solve the ADDTN starting problem. The main numerical simulation results show that the expansion ratio is the most sensitive parameter affecting the starting characteristic of ADDTN, followed by the cavity divergence angle and the cavity length. And, among these parameters, the parameters of cavity convergence angle and rounding radius at the cavity bottom contribute the least to the starting problem. Besides, the ADDTN configurations of large rounding radius at the nozzle throat tend to start.

Sintopy of the distal end of the nasolacrimal duct detected by means of the vector analysis of the CT-identified anatomical features of the nasal cavity

The objective of the present work was to study syntopy of the distal end of the nasolacrimal duct based on the results of the vector analysis of the CT-identified anatomical features of the nasal cavity and the paranasal sinuses in 102 patients (204 nasolacrimal channels). The main criterion for inclusion in the study was the absence of traumatic injuries and inflammatory changes in the nasal cavity and the paranasal sinuses. X-ray studies of the distal end of the nasolacrimal duct (NLD), turbinate crest (crista conchalis), the edge of the nasal aperture, and the floor of the nasal cavity were carried out. The vector and angle measurements were made with respect to the bottom of the nasal cavity in the perpendicular and parallel planes. The study has demonstrated that the distal end of the nasolacrimal duct was located 3.49 mm above the level of crista conchalis of the maxillary bone 19.77 mm and 22.04 mm apart from the edge of the aperture of the nose in the individuals younger than 20 years and in the older subjects respectively. Syntopy of the distal end of NLD relative to the bottom of the nasal cavity did not depend on the sex and age of the patients and was localized at a depth of 13.93 mm from the edge of the aperture of the bone and 11.86 mm above the bottom of the nose.