Central Orifice Research Articles

Gastric dysplasia arising from a submucosal heterotopic gastric gland.

A submucosal heterotopic gastric gland (SHGG) is characterized by benign ectopic gastric tissue within the submucosa. Neoplasms arising from SHGGs are rare, and their definitive diagnosis via endoscopic biopsy is often challenging. We report the case of a 74-year-old man undergoing screening esophagogastroduodenoscopy, which revealed a subepithelial lesion with a central orifice in the upper body of the stomach. Endoscopic submucosal dissection (ESD) was performed because the endoscopic biopsy revealed a suspected pyloric gland adenoma. Pathological examination of the resected specimen confirmed SHGG with focal dysplasia. The patient recovered uneventfully and remained free of recurrence over a 5-year follow-up period. This case highlights the utility of ESD in both the treatment and accurate pathological diagnosis of neoplasms arising from SHGGs.

Clinical analysis of atlanto-occipital decompression in the management of chiari malformation with multi-segmental syringomyelia.

Chiari malformation type I with syringomyelia (CM-I-S) is a very common disease in neurosurgery. There are also various surgical methods. But it is controversial. There are few reports about children, especially the treatment of multi-segmental beaded syringomyelia. The purpose of this study was to explore the clinical effects of atlanto-occipital decompression (AOD) in the management of Chiari malformation type I (CM-I) with multi-segmental beaded syringomyelia (MSBS) in pediatric patients. This retrospective study were pediatric patients with CM-I combined with MSBS who were treated in our hospital from January 2015 to December 2023. The patients who received the AOD treatment were screened according to inclusion and exclusion criteria. Outcomes were assessed by comparison of pre- and postoperative clinical, Chicago Chiari Outcome Scale (CCOS), the diameter and volume of the syringomyelia, morphological parameters of posterior cranial fossa (cervical spinal cord angle of medulla oblongata, CSC-MO) and complications in the enrolled children. This study ultimately included 21 eligible pediatric patients with CM-I and MSBS. All the patients successfully completed the operation, which consists of atlanto-occipital decompression, partial resection of the posterior arch of the atlas, electrocoagulation of the cerebellar tonsil, pseudomembrane resection of the central canal orifice (latch) of the spinal cord, and artificial dura mater expansion repair. No death, no relapses, no serious neurological dysfunction and other complications. At the last follow-up, the clinical symptoms of all patients basically disappeared. The results of magnetic resonance imaging (MRI) showed that the average preoperative cerebellar tonsillar hernia was 12.4 ± 4.6 mm, and the postoperative were all above the foramen magnum. The average preoperative syringomyelia volume was 11.7 ± 3.7 cm2, and the syringomyelia disappeared or significantly shrunk after operation, with the volume unable to be accurately measured. The median preoperative CSC-MO was 132.5°, and the median postoperative CSC-MO was 150°, with a significant difference. The median preoperative pain and non-pain score of CCOS was 4 and 3 respectively. The symptoms disappeared after operation, and the score was 4. Only 5 children had cerebrospinal fluid leakage. The AOD is safe and effective in CM-I with MSBS in pediatric patients. Pseudomembrane resection of the central canal orifice (latch) of the spinal cord is crucial for the treatment of syringomyelia.

Abstract 18651: Case Report: Transcatheter Edge-to-Edge Repair in a 59-Year-Old Patient With Mitral Regurgitation and Challenging Anatomy

Re-intervention for patients with mitral valve disease is a growing challenge. We present a 59-year-old male with a history of a congenitally bicuspid aortic valve. He had valve and root replacement for aortic regurgitation in his 30s and two subsequent sternotomies for prosthesis failure and endocarditis. After admission with acute pulmonary edema, there was persistent NYHA class II-III dyspnea. Echo showed severe (grade IV) mitral regurgitation due to the dehiscence of a 32mm mitral annuloplasty ring. The coaptation point of the leaflets was posterior to the posterior aspect of the ring. No regurgitation was observed through the ring’s central orifice, but the tissue was seen on its posterior aspect, suggesting torn posterior leaflet or healed vegetation. The left ventricle was mildly dilated, and the LVEF was 53%. The right ventricle was moderately dilated with severe functional tricuspid regurgitation with a normally functioning aortic valve prosthesis. After extensive discussion, due to his multiple previous surgeries and challenging anatomy, the patient was deemed unsuitable for surgical treatment. There is some limited registry data to support TEER as a safe and feasible alternative to surgery in this cohort. He underwent successful implantation of two clip devices in the A2/P2 and A2/P2b positions via a trans-septal approach under a general anesthetic. Femoral venous access was used. Some useful learning points relate to the challenges posed by the unusual anatomy in terms of imaging and trajectory. No MVARC complications. Postoperatively the LVEF was 55% with a mean transvalvular gradient of 5mmHg and only mild (grade I) transvalvular MR. At three months the patient reported an improvement of overall functional status. This successful case of “clip-in-ring” TEER illustrates one of the expanding indications for existing trans-catheter valvular therapies as well as the potential for creative application of TEER in helping patients with high surgical risk.

In-situ charge reduction of electrospray plumes by unipolar corona ions

Obtaining uniformly-sized microparticles by electrospray drying poses challenges due to the high electric charge of the droplets, which often leads to Coulombic fissions, short lifetimes, and charge buildup on the collection. In this study, we have conducted numerical simulations to investigate the use of unipolar ions for achieving extensive droplet discharging in electrosprays, aiming to prevent Coulombic fissions and attain high efficiency in extracting the electrically discharged aerosol. Our mathematical model incorporates Lagrangian tracking of the droplets, their evaporation till forming a solid residue, Coulomb fission, Eulerian descriptions of ion and progeny droplet transports, and droplet discharge kinetics through ion capture. We have identified an effective system configuration comprising coaxially a capillary electrode supporting the Taylor cone, a nearby ring electrode, and an Earth-grounded plate with a central orifice emitting ions. The electrode potentials are selected to sustain the Taylor cone. Air flows coaxially with the electrospray, passing through the ring hole, and exiting the system through a circular slit in the plate. We have simulated two electrospray systems with identical droplet size distributions but different volatilities of the solvents (acetone and methanol). In these systems, the ion cloud rapidly expands from the plate orifice, driven by strong electrical self-repulsion, subsequently flooding the entire spray while traveling towards the ring. The droplets are electrostatically repelled from the ring and are encouraged by the airflow to pass through the ring hole. Most of the droplets are discharged downstream of the ring, before they undergo their first Coulomb fission. Importantly, when the ring is thin and short, it attracts the majority of excess ions. The remaining ions pass through the ring towards the Taylor cone, but are intercepted by the spray, thus preserving the cone stability. Consequently, our simulations demonstrate that the configuration with axial symmetry comprising a ring and an orifice plate between the spraying and corona tips is a robust strategy to obtain stable and efficient in-situ discharging and extraction of electrospray plumes.

Pengaruh Variasi Tebal Orifice dan Bilangan Reynolds (Re) terhadap Penurunan Tekanan (Pressure Drop) pada Entrance Region

Orifice is a device that is placed in a pipe flow to inhibit the flow of fluid and cause a pressure drop. The measurement of the flow rate (flow rate) is obtained from the difference in pressure due to the pressure drop. In this study, it analyzed the influence of differences in plate orifice thickness variations used ranging from 2 mm to 4 mm thick with variations in increments every 0.5 mm with an orifice center hole diameter of 1.5 cm. Orifice placement is placed in an area whose speed profile is still changing or called the entrance region with a pipe diameter used 2.54 cm (1 Inch) diameter in the pipe. Then along the entrance area are paired 12 piezometer points along 75 cm with a position of laying 6 piezometer points before the orifice valve and 6 piezometer points after the orifice valve and in this experiment set the Re value to 3 Variations of Re, namely Re 1: 9784.5; Re2: 14647.5; Re 3: 19510.45 and this experiment was carried out at a temperature of 27 °C. In this study, the results were obtained for the highest irrecoverable pressure drop value located in the flow discharge with Re 19510.45 and at the thickness of the plate orifice 4 mm with an irrecoverable pressure drop value of 3033.01 Pa and while for the lowest irrecoverable pressure drop value, it was located in the flow discharge with a value of Re 9784.5 at an orifice plate thickness of 2 mm with an irrecoverable pressure drop value of 548.26 Pa. The highest discharge of coefficient (Cd) value lies in the flow discharge with a value of Re 14647.5 at the plate orifice thickness of 3.5 with a Cd value of 0.718 and while for the lowest discharge of coefficient (Cd) value lies in the flow discharge with Re 14647.5 with an orifice plate thickness of 2 mm with a Cd value of 0.609.

EVO/EVO+ Visian Implantable Collamer Lenses for the correction of myopia and myopia with astigmatism

ABSTRACT Introduction Intraocular lens implantation in phakic eyes for the correction of refractive error is currently a widespread procedure. The EVO and EVO+ Visian Implantable Collamer Lenses (ICL) are two of the most prevalent lenses implanted. They incorporate a central orifice to avoid the need for iridotomy. The main difference between both ICL is the higher optical diameter zone provided by the EVO+, allowing a better quality of vision at night. This review aims to provide an overview of the current ICL models available for correcting myopia and myopic astigmatism. Areas Covered During the last decade, more than 100 scientific papers analyzing the performance of EVO and EVO+ lenses have been published. This review describes the objective visual performance achieved with the implantation of central hole ICL lenses and the subjective perception of the patients implanted with these lenses. In addition, the safety and the potential complications associated with undergoing an EVO and EVO+ ICL implantation have been addressed. Expert Opinion Refractive surgeons and candidates to undergo ICL implantation should be aware of the excellent safety and visual outcomes provided by the implantation of central hole ICL lenses. However, future research could address minor issues currently not resolved.

Flow and heat transfer characteristics of single and multiple synthetic jets impingement cooling

In this paper, the comparison between synthetic jet actuator with single axisymmetric orifice and multiple axisymmetric orifices is presented. The aim of this paper is to compare the flow and heat transfer characteristics of single and multiple synthetic jet impingements cooling. The multiple orifice configurations had a central orifice and a satellite orifices placed in the pitch circle. The synthetic jet actuator had central orifice with 0, 3, 4, 5 and 6 orifices placed in the diameters of the relative pitch circle p/d = 2.5, 3 and 4. A total of 13 various geometric configurations were tested experimentally. In the multiple orifice configurations, the total cross-section area was approximately equal to the cross-section area of the single orifice configuration. The input power delivered to the synthetic jet actuator was maintained constant and equal to 3.00 W. The synthetic jet actuator energetic efficiency, Reynolds number, equivalent Reynolds number, radial and axial distributions of pressure coefficient, and heat transfer characteristic were presented. The synthetic jet issuing from multiple orifice plate merged at some axial distance, creating a single axisymmetric jet. The merging jet axial distances were determined for all investigated configurations. In the present paper, the integral quantities averaged over all orifices cross section area, or over impingement plate much larger than total orifices area, were analyzed for the purpose of objective comparison. From all various investigated parameters obtained from five different and independent experimental methods, the following conclusion may be made: if the total orifice cross section area in the case of single and multiple orifice synthetic jet is similar and real power deliver to the SJA is maintained at the same level the resulting equivalent Reynolds number and equivalent dimensionless stroke length achieved similar values and the impinging jet equivalent Nusselt number also achieved comparable values and distributions.

Computational Parametric Study and Live Firing Validation of Base-Bleed Exit Configuration

Base bleed, along with boattailing, is widely confirmed to be an efficient technique for drag reduction of projectiles. It is believed that the flow pattern at the projectile base, hence the level of drag reduction, is dependent on the base-bleed exit configuration design. It was also shown that bleeding from annular slots overperformed that from a single central orifice. However, central orifices are required for practical issues and may not be completely eliminated. The effect of simultaneous bleeding from the central orifice and annular slots was not adequately explored before. In addition, the impact of annular slot design on level of drag reduction was not thoroughly clarified in the available open literature. The objective of the present study was to systematically address these two gaps. Following parameterization of the bleed exit configuration, a set of three-dimensional computational simulations are conducted to find the design that yields the maximum drag reduction. A set of live firing experiments are conducted to assess the validity of simulation results. Based on parametric study results, the impact of bleed exit configuration on base flow pattern, base pressure, and total drag coefficient is explained. The optimized bleed configuration was found to yield a further drag reduction up to 5% compared to the baseline configuration, including a single central orifice.

Pneumatic hammer characteristics of the aerostatic thrust bearing with central orifice and pressure-equalizing groove

Pneumatic hammer characteristics of the aerostatic thrust bearing with central orifice and pressure-equalizing groove

Broadband ventilated meta-barrier based on the synergy of mode superposition and consecutive Fano resonances.

Sound insulation under ventilation conditions is an important issue in acoustic fields that has significant applications in various practical scenarios. The emergence of acoustic metasurfaces breaks the limitation of manipulating large-scale waves at subwavelength scales and enables a better ventilating capability, while there is still a problem that the bandwidth of previous studies is usually smaller than half an octave. Here, we design and experimentally implement a ventilated meta-barrier with subwavelength thickness capable of realizing broadband sound insulation while maintaining efficient ventilation. The underlying mechanism is the synergy of the consecutive Fano resonances and superposition of equal-strength monopolar mode of the gradient helical structure and dipolar mode of the central orifice, leading to an efficient blocking of approximately 90% of sound waves coming from various directions in the range from 1145 to 1815 Hz while preserving high-efficiency ventilation. The experiments are conducted to verify the effectiveness of the resulting device, which is in good agreement with the simulated results and theoretical predictions. Our design with functionality and flexibility opens up possibilities for the design of broadband ventilated acoustic devices and may find important application prospects in diverse fields such as noise control and architectural acoustics.

Enhancement of flushed sediment in pressure flushing using inclined plates upstream of orifice

Abstract Pressure flushing is a common technique to restore the storage capacity of reservoirs. However, the low quantity of flushed sediment remains a drawback of pressure flushing. Experimentally, the present study used inclined plates upstream of the bottom outlet to increase the flushed sediment in pressure flushing. The variables included the plate width (B), the angel between the vertical line at the outlet center and the normal vector of the inclined plate (α), radial distance of the inclined plates from the orifice center (R), and outlet discharge (Q). The results showed that the flushed sediment significantly enhanced; the quantity of flushed sediment for B = 6.3 cm, α = 60°, R = 8.5 cm, and a Q = 8.34 L/s was 19 times as large as that in the reference test (i.e., without plates). Furthermore, the length, width, and depth of the scour cone in the presence of inclined plates were 3, 2.3, and 3.3 times as high as those in the absence of the inclined plates. Also, equations were developed to predict the volume and dimensions of the scour cone in the presence of inclined plates based on the experimental data. Finally, the importance of the variables was determined using a sensitivity analysis method. Between all considered parameters in this study, the plate distance from the outlet was found to have the highest effect and the plate inclination the lowest effect (three times) in increasing the flushed sediment through the orifice.

An experimental study on the damping characteristics and tuning of the liquid column vibration absorber

This paper deals with an experimental investigation of the damping characteristics of the liquid column dynamic vibration absorber. The laboratory test rig of a single degree of freedom system integrated with a liquid column dynamic vibration absorber was designed and manufactured to study the efficiency of this type of dynamic absorbers. The system response has been measured and recorded by using a (DXL-345) accelerometer and data acquisition system. The effects of mass ratio, length ratio, and the opening ratio of the central orifice on the vibration reduction of the main structure in free vibration mode were evaluated. The results showed that the tuned liquid column vibration absorber has a good ability to reduce or eliminate unwanted vibration by the suitable selection of the combination of its design parameters. The maximum damping of the main system was achieved at the mass, length and orifice opening ratios equal to 7.7 %, 87% and 74% respectively.

Turbulence characteristics in a weir-orifice-slot combined fishway with an identical layout

A combined fishway containing notched weir, central orifice and vertical slot with an identical layout was designed, and its turbulence characteristics were experimentally studied. An acoustic Doppler velocimetry (ADV) was used to measure three-dimensional velocity. Flow regime, average velocity, turbulence intensity, Reynolds stress, power frequency-spectrum, correlation function, turbulence scale were analysed. The experimental results showed the combined fishway was of remarkable three-dimensional flow structures. Longitudinal velocity exhibited obvious extreme value region on the horizontal plane. Extreme values of longitudinal turbulence intensity were concentrated mainly on the mixing region between weir flow and orifice jet, as well as the vertical slot wall jet region, extreme value region of transverse turbulence intensity occurred on the central plane of orifice jet, and extreme values of vertical turbulence intensity were scattered. Reynolds stress extreme value occurred mainly in the convergent zone of multiple jets. Dominant frequency of power frequency-spectrum was highest for notched weir and lowest for vertical slot. Longitudinal velocity fluctuation exhibited a correlation with time, which was characterised by dominant frequency. Turbulence scales showed eddy structures were related to flow zones.

Live Firing and 3D Numerical Investigation of Base Bleed Exit Configuration Impact on Projectile Drag

Base bleed, in which gases are discharged at the base of projectile, is confirmed to be an effective drag reduction technique. Itis believed that the design of base exit can impact the pattern of gas bleeding and, hence, the level of drag reduction. The present study is aimed to address this dependence that was not clarified in previous studies by examining the reduction in drag acting on a projectile with two different base bleed exit configurations. The first configuration includes a central circular orifice while the other is modified to include a smaller central circular orifice and four annular slots with equivalent total area. Numerical simulations on 3‑D computational domain have been conducted to estimate drag and to explore the base flowfield for each configuration. The computational results at different Mach numbers have been compared with the mean drag based on range shooting for projectiles with both base configurations. In addition, different simulations have been performed to predict the real pattern of bleeding through the modified configuration based on the comparison with firing data at different Mach numbers.

Numerical validation of hydrodinamic cavitation generation using perforated plates

This research shows the analysis of three case studies using perforated plates with a central orifice to generate hydrodynamic cavitation with diameters of 2 mm, 3 mm, and 4 mm. Experimental model was fabricated and instrumented to validate numerical models of the perforated plates and their corresponding pressure drop. Test points were established in the experimental setup to measure variables such as pressure drop compared between upstream pressured (distance of one diameter before plate), and downstream pressure (distance of ½ diameter after the plate), according to the ISO 5167 standard. The numerical model was developed using commercial computational fluid dynamics (CFD) software applying the standard k-epsilon turbulence model, the mixture model, and the Rayleigh-Plesset equation. Results demonstrated that numerical model of the pressure drop produced hydrodynamic cavitation downstream the perforated plates; such phenomenon was validated with experimental data by less than 5% error values.

Spray Combustion of Rocket-Grade-Kerosene-Based Nanofluids with Oxygen

The spray and spray combustion characteristics of rocket-grade kerosene (Isrosene) loaded with graphene nanoplatelets and aluminum nanoparticles are investigated in this study. A shear coaxial injector with recess was employed to generate the nanofluid spray flowing through the center orifice and 99.98% oxygen through the annular gap. The mass flow rate was maintained at for both the fuel and oxidizer streams, and the flame was nonconfined. Effect of nanoparticles on droplet size of the sprays, flame liftoff height, flame temperature, and CO emissions were measured. Droplet size measurement was conducted using a laser-based nonintrusive technique (MALVERN particle sizer). It was observed that for the same mass flow rates of the fuel and oxygen, the droplet size of the spray increased by 50% due to the addition of nanoparticles. The direct videography method was used to visualize the flame shape and size, and it was observed that the flame liftoff height decreased by 50 and 10% due to the addition of graphene and aluminum nanoparticles, respectively. The presence of nanoparticles enhanced the reaction rate, which was concluded based on the measurement of flame temperature and CO concentrations.

Acoustics and Heat Transfer Characteristics of Piezoelectric Driven Central Orifice Synthetic Jet Actuators

ABSTRACT Growth in computational capacity combined with a decrease in the size of digital devices has led to increasing demand for more active and efficient cooling of electronics. In this study, an experimental investigation into two different sizes of central orifice Synthetic Jet Actuators (SJAs) is conducted to evaluate their heat transfer as well as noise generation characteristics. Two SJAs (40 mm and 20 mm) are examined, covering a distinct span of frequencies ranging from low to medium (<5500 Hz) in regards to the effect of SJA size over performance. The SJAs’ disk deflection, structural frequency, and jet exit velocity were measured to fully characterize the jet performance. The maximum Nusselt number for the largest SJA was 3 times more than the smallest SJA, where the evaluation of stroke length suggests no effective synthetic jet formation for the smallest SJA. The noise from the SJAs was measured in an anechoic chamber using three microphones, Fast Fourier Transform (FFT) of the sound pressure levels provide contributions to different tones in the resulting noise. 1/3 Octave Constant Percentage Bandwidth (CPB) analysis was performed to identify the frequency bands making the largest contribution to the noise. The largest SJA showed the highest heat transfer at acceptable noise levels during the operation below resonance frequency.

Influence of Injection Pressure on the Thermohydrodynamic Behavior of Tilting Pad Journal Bearings—Model and Experiment

In rotating machines, tilting pad journal bearings (TPJBs) are widely used because of their enhanced design stability in comparison with alternative bearing configurations. In the present research, a thermohydrodynamic (THD) lubrication model for a tilting pad bearing with injection is developed. Within the THD lubrication model, the lubricant is also fed into each pad through a central injection orifice. The effects on the lubricant oil film pressures and temperatures and subsequent influences on the system dynamic behavior were investigated. Another important factor considered within the THD model is associated with the flexibility of the pivot of each pad and its impact on the behavior of the bearing when subjected to direct lubricant injection. The numerical model results are compared with the measurements of the rotor equilibrium position within the bearing and the pad temperatures obtained from the test rig designed specifically for the TPJB geometry with and without central pad injection. Pad temperatures are measured before the injection orifice position and after it. Agreement between experimental and model-predicted results provides confidence in the model’s ability to evaluate the dynamic behavior of the bearing and its effect on the complete system through the stiffness and damping coefficients.

Broadband ventilated metamaterial silencer for high reflection based on Fano-like interference

Conventional sound shielding structures is difficult to meet the requirements of low-to-middle frequency broadband sound insulation and free ventilation. In this paper, we propose a ventilated metamaterial silencer based on Fano-like interference, which can achieve the sound transmission loss (STL) of more than 10 dB in the range of 516–970 Hz with subwavelength thickness (0.11 [Formula: see text]) while remains an opening area ratio of 23%. The designed silencer is composed of a large central orifice and four surrounding coiling channels, making the sound waves passing through the two areas generate Fano-like asymmetric transmission spectrum and form efficient reflection to insulate sound coming from various directions. The parametric studies are also carried out to investigate the tunable acoustic performance. Experiment measurement matches well with the simulation results. In the future, the proposed silencer may have potential applications in practical environments requiring broadband sound insulation and free air flows.

Efficient degradation and mineralization of methylene blue via continuous-flow electrohydraulic plasma discharge

A continuous-flow electrohydraulic plasma discharge (EHPD) process characteristic of establishing a stable discharge through the conducting channel of in the center orifice of a dielectric plate was developed and investigated to degrade methylene blue (MB) in water. The effect of three operating parameters, i.e., liquid flow rate (37−94 ml/min), air flow rate (1−4 L/min), and initial dye concentration (10−100 mg/L), on the MB degradation efficiency was evaluated. The results indicated that a complete degradation of MB was achieved within 10 min of treatment for all MB concentrations tested. The optimum liquid and air flow rates were 68 mL/min and 3 L/min, respectively, for the process to remove MB in a circular flow operation. The energy efficiency for different operating parameters was in the range of between 0.16 g/kWh and 0.81 g/kWh at 50% conversion. Reaction kinetics and the possible MB degradation pathway was analyzed and proposed. Hydroxyl radicals were found to be the dominant reactive species responsible for the MB degradation. Mineralization of MB was demonstrated by a 92.5% COD removal within10 min treatment for an initial MB concentration of 100 mg/L. The overall results indicated that the novel, continuous-flow EHPD reactor is a robust and highly effective process for degradation and mineralization of MB, a potential technology that can overcome the limitations of advanced oxidation processes for wastewater treatment.