Throat Region Research Articles

Solar plant with short diffuser concept: Further improvement of numerical model by included influence of guide vane topology on shape and stability of gravitational vortex

An alternative renewable energy concept, i.e. the concept of a solar power plant with short diffuser (SPD), was numerically investigated by more advanced computational fluid dynamics (CFD) model. Developed model is characterized by a more sophisticated and streamlined guide vane topology. The main novelty of this work is conducted optimization of the guide vane topology, for a specific novel application related to the alternative renewable energy concept (SPD). Optimization involved determining the required guide vane topology using minimal number of geometry influencing parameters. The objective was to result in vortex genesis and stabilization with respect to the desired circumferential velocity and to minimize the required pressure potential that is necessary for stable operation of the SDP plant. Provided numerical investigation was necessary, and for sure a step forward towards consideration of the experimental plant (which will assume introduction of the turbines). It needs to be taken into account that we deal with complex flow structure that requires gradual numerical investigation, in order to be able to get detail insight in the various influences and processes that can strongly affect SPD operating parameters. The guide vane topology was altered to develop an SPD capable of establishing and maintaining a stable gravitational vortex in pressure ranges which resemble atmospheric vortex phenomena (feasible for development of a compact system, and with maximal velocities in chimney throat regions ranging below 20 m s−1). The study outlines nine cases, each representing the altered guide vane design, where the best case is determined and compared with the available experimental data from other research groups. The comparison indicates that the numerical model, although quite simple, is accurate and robust in predicting the distribution of local velocity and pressure profiles and fit for implementation on wind turbines in order to determine the influence of the installed turbines on the vortex shape and stability in a future study. An important finding is that the swirl ratio can be manipulated by altering the guide vane shape, and it is independent of the Reynolds number (which will be important during the design phase since it can be used as a control strategy for vortex genesis and as a prevention of unintentional genesis regarding additional multiple vortices). The gained numerical results revealed specific operating conditions that will ensure a safer environment around the SPD and that will enable a carbon free electricity production.

USA300 Staphylococcus aureus persists on multiple body sites following an infection

BackgroundUSA300 methicillin-resistant Staphylococcus aureus (MRSA) is a community- and hospital-acquired pathogen that frequently causes infections but also can survive on the human body asymptomatically as a part of the normal microbiota. We devised a comparative genomic strategy to track colonizing USA300 at different body sites after an initial infection. We sampled ST8 S. aureus from subjects at the site of a first known MRSA infection. Within 60 days of this infection and again 12 months later, each subject was tested for asymptomatic colonization in the nose, throat and perirectal region. 93 S. aureus strains underwent whole genome shotgun sequencing.ResultsAmong 28 subjects at the initial sampling time, we isolated S. aureus from the nose, throat and perirectal sites from 15, 11 and 15 of them, respectively. Twelve months later we isolated S. aureus from 9 subjects, with 6, 3 and 3 strains from the nose, throat and perirectal area, respectively. Genome sequencing revealed that 23 patients (ages 0–66 years) carried USA300 intra-subject lineages (ISLs), defined as having an index infection isolate and closely related colonizing strains. Pairwise distance between strains in different ISLs was 48 to 162 single nucleotide polymorphisms (SNPs) across the core regions of the chromosome, whereas within the same ISL it was 0 to 26 SNPs. Strains in ISLs from the same subject differed in plasmid and prophage content, and contained deletions that removed the mecA-containing SCCmec and ACME regions. Five strains contained frameshift mutations in agr toxin-regulating genes. Persistence of an ISL was not associated with clinical or demographic subject characteristics. We inferred that colonization with the ISL occurred about 18 weeks before the first assessment of asymptomatic colonization.ConclusionsClonal lineages of USA300 may continue to colonize people at one or more anatomic sites up to a year after an initial infection and experience loss of the SCCmec, loss and gain of other mobile genetic elements, and mutations in the agr operon.

Calculation of the Resonant Frequencies of the Throat Part of the Helmholtz Resonator

The calculation of the resonant frequencies of the Helmholtz resonator neck for the purpose of further evaluating the relationship between the resonant frequencies, obtained experimentally with the resonant frequencies of one of the main elements of the resonator to create broadband acoustic systems or metamaterials is presented. Recently, the issues concerning Helmholtz's resonators are of increasing interest in the scientific world. They are actively used to solve various problems in acoustics and find more and more applications - from use as mufflers, for use in the composition of metamaterials. As a simplification, it is assumed that the Helmholtz resonator has only one resonant frequency. In practice, the presence of a number of additional resonances was discovered. In this paper, it is proposed to approach the question of finding additional resonant frequencies on the other hand and consider the cavity as a system consisting of two more simple elements, to go by solving two more simple problems and to bring the results together, to reconcile them. The aim of the work is to calculate the resonant frequencies of the Helmholtz resonator neck. The throat parameters are chosen equal to the throat parameters of one of the resonators investigated in experiment. Using the MathCad software environment, the necessary calculations to obtain the values of resonant frequencies in the range from 0 to 4200 Hz were made. The 9 resonant frequencies in the range from 99 to 4060 Hz was obtained experimentally. As a result of the calculation, numerical values are obtained for the first sixty four resonant frequencies. Some of these resonances will not have a significant effect on the resonances of the system, due to the smallness of their amplitudes of oscillations. This may explain the difference in the number of resonances obtained as a result of the calculation and experimentally (the smaller the amplitude of the oscillations, the more difficult to fix the resonance experimentally). At a frequency of 3978 Hz, resonance was observed inside the flask experimentally; in the throat region, resonance was absent. At the frequencies 3037Hz, 3568Hz and 4060Hz, the resonance in the neck was poorly expressed. It can be concluded that the resonant frequencies of the throat, exceeding the value of 3000 Hz, will not have a significant effect on the resonance values of the entire resonator, i.e. for these values of frequency, resonance in the throat part was not observed experimentally. Taking into account the amplitudes of oscillations inside the neck will help reduce the number of frequencies that are interesting for further calculations and select among them the frequencies that will have the greatest influence on the value of the resonance frequencies of the entire resonator, that is, they will have the greatest amplitudes of fluctuations within the neck. Therefore, the purpose of further research is to calculate the amplitudes of oscillations that correspond to the received resonance frequencies. Ref. 12, fig. 3, tabl. 3.

Trimethoprim-sulfamethoxazole and antineutrophil cytoplasmic antibodies-associated vasculitis.

In antineutrophil cytoplasmic antibodies-associated vasculitis (AAV), the treatment of choice is either Rituximab or cyclophosphamide in combination with steroids. In less extended forms of AAV, however, less toxic regimens are being used.In the current review, we will focus on the role of one of these less toxic regimens, that is trimethoprim-sulfamethoxazole monotherapy as induction treatment or as maintenance therapy in AAV. A substantial portion of patients with active granulomatosis with polyangiitis (GPA) limited to the upper airways can be initially controlled with trimethoprim-sulfamethoxazole (2 × 960 mg/day) monotherapy. In patients with initially a complete response, long-term control of the disease seems possible. In addition, trimethoprim-sulfamethoxazole (2 × 960 mg/day) maintenance therapy is an option for patients with GPA that have been proven to be frequent relapsers. The mechanism by which trimethoprim-sulfamethoxazole works in GPA is at present unknown. Suppression of Staphylococcus aureus carriage and/or anti-inflammatory mechanisms has been postulated. Trimethoprim-sulfamethoxazole may be considered as a safe initial treatment in GPA patients with disease localized to the ear, nose, and throat region. Furthermore, trimethoprim-sulfamethoxazole in a dose of 2 × 960 mg/day may be used to prevent relapses in GPA.

Pattern of presentation of ear, nose, throat, head and neck injury in a developing country

Objective : Ear, nose, throat, head and neck injuries are a common otorhinolaryngology disorder worldwide. This study aimed at determining the prevalence, sociodemographic features, aetiology, clinical presentation management and outcome of injuries to the ear, nose, throat, head and neck region. Methods : This was a prospective study of patients with otorhinolaryngolology, head and neck injuries that presented at our tertiary health institution. Consented patients were studied between October 2015 and September 2017. Analysis of obtained data was done with SPSS version 16.0. Results : The prevalence of ear, nose, throat, head and neck injury was 9.4%. There were 63.5% males 36.5% females with male to female ratio of 1.5:1. Foreign bodies' impaction was the commonest cause of injury in 32.3% followed by road traffic accidents in 19.8%. Commonest anatomical region were ear and nose in 49.7% and 28.5% respectively. Common clinical features among the patients were pain in 46.5%, bleeding in 37.8% and foreign bodies' impaction in 32.3%. Presentations for otorhinolaryngology care among the patients were common in 95.1% acute injury than 4.9% chronic injury (≥13 weeks). Commonest associated complications of the injuries were otitis media in 18.8% others were 14.9% otitis externa, 9.4% perforated tympanic membrane and 6.3% epistaxis. Pre-hospital treatment in the patients was 67.4%. Major treatment offered to the patients was conservative/medical therapy in 28.8%. Conclusion : Ear, nose, throat, head and neck injuries are common in the otorhinolaryngology practice. Commonest causes are self inflicting foreign bodies' impaction and road traffic accident. Pre-hospital treatment among the patients was very high. Keywords : Ear, Nose, Otorhinolaryngology, Head, Neck, Injuries, Trauma, Developing country

Modelling of swallowing organs and its validation using Swallow Vision®, a numerical swallowing simulator

Swallowing process occurring within the mouth and throat regions is so quick and complex that the three-dimensional (3D) motion of each organ involved in the process has not yet been visualised even by the state-of-the-art medical imaging technology. To overcome this issue, a realistic organ model has been developed based on the actual medical images and validated using swallowing simulation (by Swallow Vision®). A three-dimensional organ model coupled with a bolus flow model has been developed using a mesh-free moving particle simulation (MPS) method. Two organ models have been developed based on the computed tomography (CT) and video-fluorography (VF) images of a healthy male volunteer and a male patient with mild dysphagia, and validated by simulation. The results showed that these two models well-visualised each organ and the bolus flow, which were consistent with the actual images. The realistic organ model is deemed to be useful for acquiring a deeper understanding of the biomechanics of swallowing. Further work, especially on the segmentation and registration of medical images, will enable to develop various organ models from medical images, which may help in performing swallowing simulations in the clinical practice.

Direct Evidence for Throat Aurora Being the Ionospheric Signature of Magnetopause Transient and Reflecting Localized Magnetopause Indentations

AbstractMagnetopause transients, observing as brief entries into the magnetosheath by satellites, are commonly observed in the vicinity of the magnetopause and have been explained by several possible mechanisms. However, satellite observations alone are insufficient to determine the dynamics and context of transients. Throat auroras are characterized as north‐south aligned discrete auroral forms extending from the equatorward edge of the discrete auroral oval that are only observed near dayside convection throat region and have been suggested as the ionospheric signature of localized magnetopause indentations. Using coordinated observations from the Magnetospheric Multiscale Mission (MMS) and ground‐based all‐sky imagers, we show apparent one‐to‐one correspondences between transients observed by MMS near the subsolar magnetopause and throat auroras observed on the ground. The correspondence is valid not only for typical throat aurora with larger spatial scale but also for these with tiny scales. We even notice that the transient durations observed by satellite are approximately proportional to the width (east‐west extension) of the throat aurora. These results provide direct evidence that throat auroras are ground signatures for the magnetopause transients. With the aid of auroral observations, we suggest that these transients reflect localized magnetopause indentations but are not produced by motion of the entire magnetopause. We also found that most transients observed here are associated with earthward flow enhancements, which indicates that high‐speed jets in the magnetosheath could be a driver for producing these transients.

Haemodynamic study of Flow in concentric and eccentric stenosed carotid Artery

Study of flow through arteries is gaining importance in the recent times due to onset of several cardio-vascular diseases like atherosclerosis (block in artery), aneurysms (bulging of artery), hypertension etc. The application of CFD will be useful in demonstrating the underlying mechanism of flow past the diseased arteries. In the present study, initially an approximate eccentric and concentric 50% stenosed carotid model is generated in ANSYS 12.0 based on patient data obtained from ultrasound Doppler scan. Later the percentage of stenosis is increased to 60%, 70%, 80% and 90% in both the cases. A transient analysis has been performed for several pulse cycles in ANSYS FLOTRAN for various percentage cases. The results obtained from ECN and CCN cases are compared to observe the changes in flow behavior in the downstream of stenosis as compared with normal case. The formation of vortices and flow separation zone in downstream in eccentric case is higher than in concentric case. Comparison of results concludes that, with the increase in severity of stenosis, the flow changes abruptly causing an increase in velocity and WSS at throat region. The simulation results obtained agree well with clinically observed data and available literature.

Haemodynamic study of Flow in concentric and eccentric stenosed carotid Artery

Study of flow through arteries is gaining importance in the recent times due to onset of several cardio-vascular diseases like atherosclerosis (block in artery), aneurysms (bulging of artery), hypertension etc. The application of CFD will be useful in demonstrating the underlying mechanism of flow past the diseased arteries. In the present study, initially an approximate eccentric and concentric 50% stenosed carotid model is generated in ANSYS 12.0 based on patient data obtained from ultrasound Doppler scan. Later the percentage of stenosis is increased to 60%, 70%, 80% and 90% in both the cases. A transient analysis has been performed for several pulse cycles in ANSYS FLOTRAN for various percentage cases. The results obtained from ECN and CCN cases are compared to observe the changes in flow behavior in the downstream of stenosis as compared with normal case. The formation of vortices and flow separation zone in downstream in eccentric case is higher than in concentric case. Comparison of results concludes that, with the increase in severity of stenosis, the flow changes abruptly causing an increase in velocity and WSS at throat region. The simulation results obtained agree well with clinically observed data and available literature.

Coupled in silico platform: Computational fluid dynamics (CFD) and physiologically-based pharmacokinetic (PBPK) modelling

One of the critical components of the respiratory drug delivery is the manner in which the inhaled aerosol is deposited in respiratory tract compartments. Depending on formulation properties, device characteristics and breathing pattern, only a certain fraction of the dose will reach the target site in the lungs, while the rest of the drug will deposit in the inhalation device or in the mouth–throat region. The aim of this study was to link the Computational fluid dynamics (CFD) with physiologically-based pharmacokinetic (PBPK) modelling in order to predict aerolisolization of different dry powder formulations, and estimate concomitant in vivo deposition and absorption of amiloride hydrochloride. Drug physicochemical properties were experimentally determined and used as inputs for the CFD simulations of particle flow in the generated 3D geometric model of Aerolizer® dry powder inhaler (DPI). CFD simulations were used to simulate air flow through Aerolizer® inhaler and Discrete Phase Method (DPM) was used to simulate aerosol particles deposition within the fluid domain. The simulated values for the percent emitted dose were comparable to the values obtained using Andersen cascade impactor (ACI). However, CFD predictions indicated that aerosolized DPI have smaller particle size and narrower size distribution than assumed based on ACI measurements. Comparison with the literature in vivo data revealed that the constructed drug-specific PBPK model was able to capture amiloride absorption pattern following oral and inhalation administration. The PBPK simulation results, based on the CFD generated particle distribution data as input, illustrated the influence of formulation properties on the expected drug plasma concentration profiles. The model also predicted the influence of potential changes in physiological parameters on the extent of inhaled amiloride absorption. Overall, this study demonstrated the potential of the combined CFD-PBPK approach to model inhaled drug bioperformance, and suggested that CFD generated results might serve as input for the prediction of drug deposition pattern in vivo.

Evaluation of lesion flow coefficient for the detection of coronary artery disease in patient groups from two academic medical centers.

In this study, lesion flow coefficient (LFC: ratio of % area stenosis [%AS] to the square root of the ratio of the pressure drop across the stenosis to the dynamic pressure in the throat region), that combines both the anatomical (%AS) and functional measurements (pressure and flow), was assessed for application in a clinical setting. Pressure, flow, and anatomical values were obtained from patients in 251 vessels from two different centers. Fractional flow reserve (FFR), Coronary flow reserve (CFR), hyperemic stenosis resistance index (HSR) and hyperemic microvascular index (HMR) were calculated. Anatomical data was corrected for the presence of guidewire and the LFC values were calculated. LFC was correlated with FFR, CFR, HSR, HMR, individually and in combination with %AS. The p<0.05 was used for statistical significance. LFC correlated significantly when the FFR (pressure-based), CFR (flow-based), and anatomical measure %AS were combined (r=0.64; p<0.05). Similarly, LFC correlated significantly when HSR, HMR, and %AS were combined (r=0.72; p<0.05). LFC was able to significantly (p<0.05) distinguish between the two concordant and the two discordant groups of FFR and CFR, corresponding to the clinically used cut-off values (FFR=0.80 and CFR=2.0). The LFC could also significantly (p<0.05) distinguish between the normal and abnormal microvasculature conditions in the presence of non-significant epicardial stenosis, while the comparison was borderline significant (p=0.09) in the presence of significant stenosis. LFC, a parameter that combines both the anatomical and functional end-points, has the potential for application in a clinical setting for CAD evaluation.

Numerical Simulation of Chemical Erosion in Vega Solid-Rocket-Motor Nozzles

The erosion of rocket-nozzle ablative thermal protection materials during the solid-rocket-motor burning time needs to be accounted for to get reliable performance predictions, especially for long-duration firings and/or small nozzles (that is, upper stages). This work numerically investigates the erosion behavior as a function of chamber conditions for the nozzles of the Vega launch vehicle solid rocket motors: Zefiro 9, Zefiro 23, and P80. This study has been performed using a Reynolds-averaged Navier–Stokes equation solver with specific application to ablative nozzles. The throat region of the nozzle, and specifically the carbon/carbon nozzle insert, has received special attention because its evolution has a significant impact on the motor performance. The analysis of the throat insert has been performed for the three full-scale nozzles by comparing the predictions to measured data from static firing tests. A sensitivity analysis to the most important model parameters that can influence the throat erosion prediction has been performed to highlight modeling capabilities and limits, as well as numerical uncertainties. Finally, a characterization in terms of nozzle throat ablation mass flux dependency upon the motor chamber pressure has been derived for the three nozzles via a power fitting of the numerical data performed at discrete chamber pressure levels.

Automatic segmentation and automatic seed point selection of nasopharyngeal carcinoma from microscopy images using region growing based approach

ContextNasopharyngeal carcinoma (NPC) is a type of cancer in the head and neck, and this cancer presents in the throat region between the pharynx and nasal cavity. NPC is frequently detected in Southeast Asia, particularly in the southern part of China, Malaysia, Singapore, Hong Kong, Taiwan, Vietnam, and Thailand. ProblemThe diagnostic procedure of NPC entirely depends on the Physicians experience and involves multiple subjective decisions. Subjective decision-making can result in inter and intra observer variations. Inter-observer variation is the total difference obtained from the results of two and above observers when scrutinizing similar materials. Variation amongst the observers is the total difference an observer experience when spotting the same material many times. Tradition diagnostic of NPC has many limitations such as the time consuming for doctors to identify and recognize the tumor area slice by slice and reduce radiologists’ workloads. In addition, another challenge lies in the appearance of doctors used the observation of human eyes (human errors) in NPC cases can be missed detailed information. ApproachA novel approach to automatic segmentation plus initial seed generated without human intervention of nasopharyngeal carcinoma using region growing based technique from microscopy images is presented in this study by take advantage of geometric features to detection of NPC images. In order to get accurate region of NPC image, the proposed results utilize wavelet transform for image enhancement by reduce the noise by remove the high ratio sub-bands and predestine a developed NPC image. Segmentation steps including many phases. Firstly, the thresholding is mean value used to binarise the image and secondly, filtering or remove unwanted objects in the images. FindingThe findings outcome from this study have shown that: (1) a new adaptive threshold is used as a post-processing to at long last detect the NPC; (2) identified and established an evaluation criterion for automatic segmentation of NPC cases; (3) highlight the methods, based on region growing based technique and active contour operation, for selecting the best region; (4) assessed the performance of the proposed results by comparing the manual measurements and automatic NPC segmentation. The NPC segmentation rate in the technique used is about 83.89%. Comparably, this amount expanded to 92.04% once a line presumption (NPC approximation) was utilized in one of the stage in the technique here.

Attributes of oscillatory physiological blood flow through 3-D geometry of single stenosed artery

The present study investigates the significant changes of flow behavior for 65 and 85 percentages severities of stenosis by area. The blood is assumed to be incompressible, homogeneous and Newtonian, while artery is assumed to be a rigid wall. The transient analysis is performed using ANSYS-14.5. Oscillatory physiological and parabolic velocity profile has been imposed for inlet boundary condition. The investigation has a Reynolds number range of 96 to 800. Pressure based solver and finite volume method are used for calculations. The flow pattern, wall shear stress (WSS), pressure, velocity, streamline contours, cross sectional and Centre-line velocity distribution are observed at early-systole, peak-systole and diastole for better understanding of arterial disease. Wall Shear Stress distribution shows that as severity increases, shearing of flow also increases for all cases. Thus maximum stress is exerted in throat region at peak systole. Pressure distribution also demonstrates that at all cases 85% stenotic artery creates more force than 65% stenotic artery at their pre-stenotic region. Interestingly, a recirculation region is visible at the post stenotic region in 85% stenotic artery for all cases and recirculation region increases with increasing minimum velocity at the inlet flow. From streamline contours it can be interpreted that 85% stenosis can create vortex at any time phase. So 85% stenosis is very harmful for its high probability of creating vortex.

RISR‐N observations of the IMF By influence on reverse convection during extreme northward IMF

AbstractPrevious studies have demonstrated that the high‐latitude ionospheric convection is strongly influenced by the interplanetary magnetic field (IMF) direction. However, the temporal details of how the convection transitions from one state to another are still not understood completely. In this study, we analyze an interval on 12 September 2014 which provided a rare opportunity to examine dynamic variations in the dayside convection throat as the IMF transitioned from strong By+ to strong Bz+. Between 18:00 and 20:00 UT the northward face of the Resolute Bay Incoherent Scatter Radar (RISR‐N) rotated through the noon sector and directly measured strengthening reverse convection flows in the dayside throat region that peaked at ∼2800 m/s. Near‐simultaneous measurements from DMSP satellites confirm the magnitude of the reverse convection and its proximity to the cusp. Time series comparison of the RISR‐N north‐south flows with the IMF Bz component shows a remarkably high correlation, suggestive of strong linear coupling, with no sign of velocity saturation. Likewise, the east‐west flow variations were highly correlated with the changes in IMF By. However, time‐lagged correlation analysis reveals that the IMF By influence acted on a time scale 10 min shorter than that of the Bz component. As a consequence, the manner in which the convection transitioned from the strong By+ condition to the strong Bz+ condition is inconsistent with either the antiparallel or component reconnection models. Instead, we suggest that these particular observations are consistent with two separate reconnection sites on the magnetopause driven independently by the IMF By and Bz components.

CRT-200.29 Evaluation Of Lesion Flow Coefficient For The Detection Of Coronary Artery Disease In Patient Groups From Two Academic Medical Centers

In this study, lesion flow coefficient (LFC: ratio of % area stenosis [%AS] to the square root of the ratio of the pressure drop across the stenosis to the dynamic pressure in the throat region), that combines both the anatomical (%AS) and functional measurements (pressure and flow), was assessed

喉頭・鼻腔に病変を有した成人T細胞白血病例

Adult T-cell leukemia lymphoma (ATLL) is a T cell tumor that was first described in Japan by Takatsuki in 1975. ATLL is induced by human T-lymphotropic virus type 1 (HTLV-1) infection and is associated with a poor prognosis. Carriers who have been vertically infected with the virus through breastmilk may develop ATLL during adulthood, with a reported lifetime incidence of about 5%. The pathological abnormalities associated with ATLL include skin rash, splenohepatomegaly, lymph node swelling, and so on. Such cases are often diagnosed in the Departments of Internal Medicine and Dermatology. Although such lesions are rarely found in the ear, nose and throat region, we experienced a case of ATLL with lesions in the larynx and nasal cavity. A 45-year-old woman complained of odynophagia and hoarseness. On physical examination, granulomas and crust formations were observed in the anterior commissure and the nose. To obtain a definite diagnosis, we biopsied the lesions during laryngeal surgery. The pathological findings suggested an ATLL. The provirus was identified in a blood sample, and the diagnosis was confirmed. Because ATLL is associated with a poor prognosis, an early diagnosis is desirable.

Automatic pharynx and larynx cancer segmentation framework (PLCSF) on contrast enhanced MR images

A novel and effective pharynx and larynx cancer segmentation framework (PLCSF) is presented for automatic base of tongue and larynx cancer segmentation from gadolinium-enhanced T1-weighted magnetic resonance images (MRI). The aim of the proposed PLCSF is to assist clinicians in radiotherapy treatment planning. The initial processing of MRI data in PLCSF includes cropping of region of interest; reduction of artefacts and detection of the throat region for the location prior. Further, modified fuzzy c-means clustering is developed to robustly separate candidate cancer pixels from other tissue types. In addition, region-based level set method is evolved to ensure spatial smoothness for the final segmentation boundary after noise removal using non-linear and morphological filtering. Validation study of PLCSF on 102 axial MRI slices demonstrate mean dice similarity coefficient of 0.79 and mean modified Hausdorff distance of 2.2 mm when compared with manual segmentations. Comparison of PLCSF with other algorithms validates the robustness of the PLCSF. Inter- and intra-variability calculations from manual segmentations suggest that PLCSF can help to reduce the human subjectivity.

Anomalous Behavior of a Solid Rocket Motor Nozzle Insert During Static Firing Test

This paper presents the study and development of a firing test used to evaluate the behavior of a solid rocket motor. The motivation for the development of a subscale solid rocket motor with end burning propellant grain geometry arose from the need to evaluate the nozzle inserts of graphite for the possible replacement with the carbon fiber-reinforced carbon composite. These subscale solid rocket motors, simulating full scale motor operating time, but with mass flow far below, aim to determine the ablative characteristics of composite materials as a function of operating time. The objective was to correlate the mass flow between subscale solid rocket motors and full scale using insert data materials such as graphite and carbon fiber-reinforced carbon composites, which have ablative characteristics determined in subscale solid rocket motors used at the Instituto de Aeronautica e Espaco. The critical section to evaluate the test device is rocket nozzle throat region. Analysis of the materials of the subsonic and supersonic nozzle insert parts was performed after the burning tests. It was found the formation of a thin layer of material deposited after the test. The deposited coating layer was analyzed by electron dispersive x-ray analysis and scanning electron microscopy. The results analyzed by these methods showed that there were aluminum and carbon in the coating. Finally, the material was analyzed by x-ray diffraction, and the results showed the presence of aluminum oxide. It was also noticed that, because of the unexpected coating deposition forming material in exit conical and throat of the insert that the effect of ablation was not observed.

Numerical simulations for swirlmeter on flow fields and metrological performance

Measurements of flow rates of fluids are important in industrial applications. Swirlmeters (vortex precession meters) are widely used in the natural gas industry because of their advantage in having a large measurement range and strong output signal. In this study, using air as a working medium, computational fluid dynamics (CFD) simulations of a swirlmeter were conducted using the Reynolds-averaged Navier–Stokes (RANS) and renormalization group (RNG) k–ε turbulence models. The internal flow characteristics and the influence of the tube structure (geometric parameter of flow passage) on metrological performance were studied, with a particular focus on the meter factor. Calibration experiments were performed to validate the CFD predictions; the results show good agreement with those from simulations. From the streamline distributions, a clear vortex precession is found in the throat region. At the end of throat, the pressure fluctuation reached a maximum accompanied by the largest shift in the vortex core from the centreline. There exists a large reverse flow zone in the vortex core region in the convergent section. To mitigate the influence of reverse flow on vortex precession, a suitable length of throat is required. For a larger convergent angle, the fluid undergoes higher acceleration leading to an increase in velocity that produces more intensive pressure fluctuations. The minor diameter of the throat also produces a higher velocity and larger meter factor. Compared with both divergent angle and throat length, the convergent angle and throat diameter play a more important role in determining precession frequency.