Chamber Height Research Articles

Static Performance Characteristics Of Vortex Rate Sensor

The vortex rate sensor is a fluidic gyroscope with no moving parts and can be used in very difficult conditions like radiation, high temperature and noise with minimum cost of manufacturing and maintenance. A vortex rate sensor made of wood has been designed and manufactured to study theoretically and experimentally its static performance .A rig has been built to carry out the study, the test carried out with three different air flow rates (100, 150, and 200 l/min).The results show that the relation between the differential pressure taken from the sensor pickoff points and the angular velocity of the sensor was linear.The present work involved theoretical and experimental study of vortex rate sensor static characteristics .Vortex rate sensor has been designed and manufactured with dimensions :- Radius of vortex chamber= 140 mm, Radius of sink tube rs= 4.5 mm, the pickoff hole diameter = 2mm, Height of vortex chamber b= 19 mm, Height of pickoff pipe h= 25 mm.

An active mixing enhancement technique in supersonic ejectors using pulsed streamwise injections

The current study numerically investigates an active mixing enhancement technique for a supersonic ejector with a constant area mixing chamber operating under the critical regime. Streamwise control jet injections are alternatively pulsed at the top and bottom sides of the mixing chamber entrance. The induced oscillation of the primary jet enhances the bulk mixing between the primary and secondary streams. The secondary stream penetrates the primary core flow much upstream with the control strategy compared to the no-injection case, improving the onset of mixing by 65.36%. A higher spread of the primary jet along the mixing chamber height is observed with the control strategy indicating an enhanced mixing between the two streams. Dynamic mode decomposition analysis of the fluctuations of the velocity magnitude revealed that the dominant dynamic structures are determined by the pulsation frequency and a dominant flapping mode can be observed. The frequency spectrum of the primary jet oscillation revealed that the dominant frequency of oscillation is dictated by the pulsation frequency of the injection. With an increase in the control jet pulsation frequency, the amplitude of primary jet oscillation reduces near the entrance region of the mixing chamber, whereas the amplitude of oscillation far downstream reaches nearly the same value for all the cases. The power spectral analysis of the unsteady pressure fluctuations along the mixing chamber wall revealed that the wall pressure oscillations are contributed by the control jet pulsation frequency as well as the shock wave reflections produced by the supersonic jet–jet interaction within the mixing chamber.

Estimated Age Calculation with Tooth Coronal Index (TCI) Method Using Orthopanthomography in Malang City Population

Age estimation is an important aspect in forensics because it plays a role in determining individual identity. In cases of forensic identification of bodies that are difficult to identify visually or in poor condition, radiography is the choice of non-invasive method that can be used for age estimation, one of which is panoramic radiography. The Tooth Coronal Index (TCI) method is one method that can be used to identify a person's biological age through panoramic radiography. The purpose of this study was to compare the chronological age with the biological age obtained from the measurement of the TCI method on the mandibular premolars using panoramic radiography in the Malang City population. TCI measurement was done by measuring the height of the pulp chamber (Coronal Height) and the height of the crown of the tooth (Coronal Pulp Cavity Height) vertically from the Cemento Enamel Junction (CEJ) on the mandibular premolars. Then the value is entered in the regression equation that has been determined to obtain an estimate of biological age. Then, the results of the estimated biological age are compared with their chronological age. At last, the difference between biological and chronological age is calculated to determine the approximate age. The mean difference between chronological age and biological age was ± 1.32 years and there is no significant difference between the biological age and the chronological age (p value 0.11). TCI method on the mandibular premolars using panoramic radiography can be used to estimate age in Malang City Population.

Optimization and numerical study of the effect of using nanodiamond and nickel nanoparticles in solar desalination using two-phase mixture method and VOF

The finite element approach is used in this research to simulate a single-slope desalination (DLN) system in 2D. Hybrid composite of nanodiamond and nickel nanoparticles are added into the chamber of the DLN system, and the two-phase mixture model is used for simulation. This transient study is conducted in a 12 h time interval from 8 am to 8 pm, and the heat transfer coefficient (HTCT), humidity in the DLN system, mean temperature (TMN) of the system, and vapor circulation contours in the system are examined by altering the glass angle (GAL), wall height (WHT), and ambient temperature (TAMB) for the DLN system. Finally, artificial intelligence is used to determine the DLN system's TMN for different variables. Results of this study show that between the 8th and 9th h of the system operation, the DLN system's TMN and HTCT reach their maximum values. Increasing the GAL and chamber height decrease the HTCT. The maximum HTCT occurs for the TAMB of 10 °C, and this coefficient decreases by increasing the TAMB. Also, the maximum humidity inside the system is related to the TAMB of 10 °C, and increasing the TAMB decreases the humidity level extremely.

Design and evaluation of a hybrid solar dryer for postharvesting processing of parchment coffee

Due to the extended drying time open-sun and solar drying of coffee procedures undergo, the development of microorganisms, mycotoxins and molds threaten the product. Alternatives such as mechanical dryers are available, nevertheless, their running costs and setups are usually expensive and unaffordable for small-scale coffee growers. Therefore, this research aimed to design, build and evaluate a hybrid solar dryer which mixes solar and mechanical drying principles. It uses a traditional solar tunnel-type dryer as a base featuring a biomass burner which uses coffee trunks left from the yearly crop renovation as biofuel. A heat exchanger heats the drying air, afterwards blown into a plenum chamber that homogenizes the air's static pressure before crossing the coffee bed, ensuring an even moisture removal. Also, the hybrid unit includes a photovoltaic system to obtain a fully self-sufficient drying unit. The newly developed dryer was tested under three different configurations: Solar and mechanical day and night (C1), solar during the day and mechanical during the night (C2) and fully solar with non-mechanical aid (C3). The results displayed a notable drying time reduction in the three evaluated configurations: C1 reduced the drying time by 70.47%, C2 by 45.75% and C3 by 21.5%. Also, the predictive model for different plenum chamber heights was obtained through computational fluid dynamics simulations, where the ideal height was 0.25 m. A biomass consumption of 1.9 kg h−1 was registered. Also improved temperature and relative humidity profiles were achieved. Its design easily adapts to the existing tunnel and parabolic-type solar dryers.

Prediction of atomization characteristics of pressure swirl nozzle with different structures

The structure of the pressure swirl nozzle is an important factor affecting its spray performance. This work aims to study pressure swirl nozzles with different structures by experiment and simulation. In the experiment, 10 nozzles with different structures are designed to comprehensively cover various geometric factors. In terms of simulation, steady-state simulation with less computational complexity is used to study the flow inside the nozzle. The results show that the diameter of the inlet and outlet, the direction of the inlet, the diameter of the swirl chamber, and the height of the swirl chamber all affect the atomization performance, and the diameter of the inlet and outlet has a greater impact. It is found that under the same flow rate and pressure, the geometric differences do have a significant impact on the atomization characteristics, such as spray angle and SMD (Sauter mean diameter). Specific nozzle structures can be customized according to the actual needs. Data analysis shows that the spray angle is related to the swirl number, and the SMD is related to turbulent kinetic energy. Through data fitting, the equations for predicting the spray angle and the SMD are obtained. The error range of the fitting equation for the prediction of spray angle and SMD is within 15% and 10% respectively. The prediction is expected to be used in engineering to estimate the spray performance at the beginning of a real project.

Effects of welding chamber height on properties of porthole die extrudates made of 0.5 wt.% GNPs/Al composite

In this study, porthole die extrusion was first performed on a 0.5 wt% GNP-nanoplatelet-reinforced aluminium matrix composite by using welding chambers having heights of 10, 15, and 20 mm. The effects of the welding chamber height on the microstructure and mechanical properties of the composite in the welding zone were studied. The observation results show that there are no macroscopic defects in the interface of the extrudate by the die with different welding chamber heights. The welding degree and ductility of the longitudinal weld of the extrudate increase with the increase of the height of the welding chamber. When the welding chamber height was 20 mm, the comprehensive mechanical properties of the composite along the extrusion direction and the vertical direction were the best. This was mainly because a higher hydrostatic pressure and shear force in the welding chamber with the height of 20 mm increased the recrystallisation degree of the composite, resulting in smaller sizes and an even distribution of the GNP and alumina nanoparticles inside the grain, which played positive role in hindering the dislocation slip. Further, the interface strength between GNP and the matrix was also enhanced characterized by the light and sharp tearing edge in the tensile fractography. The presence of GNP hindered the closure of micro-holes in the weld, and an increase in the welding chamber height effectively reduced the size of micro-holes, thereby improving the welding quality. So larger welding chamber height should be recommended without sacrificing stability and life of the die.

Flow uniformity analysis and optimization of a 60-cell external manifold solid oxide cell stack with bottom-accesses

In order to enhance the integration of the SOFC stack module and facilitate the assembly of the external manifold stack, a bottom-access structure stack was developed. Computational fluid dynamics (CFD) techniques were employed to investigate the gas distribution of the stack. Multiple parameters, such as geometrical parameters, manifold structures, and buffer chambers were optimized to improve flow distribution uniformity. The results indicated that the introduction of guide plates and distributors in the manifold helped to prevent vortex generation, which led to an increase in the mass flow rate of cells near the inlet. The uniformity of flow distribution can be greatly improved by increasing the buffer chamber height, but when the buffer chamber height is excessive, it has the opposite effect. The depth of the manifold only has a limited impact on the flow distribution. Ultimately, the optimal structure was found to be the manifold with guide plates and buffer chambers, which reduced flow non-uniformity from 8.4% to 1.4%. These findings provide reliable guidance for the improvement of flow distribution in the bottom-access stack.

Three-dimensional morphometric analysis of maxillary and mandibular molars and bilateral correlation in North Indian population

The aim of this study was to evaluate and compare the anatomical landmarks of maxillary and mandibular molar pulp chambers and evaluate bilateral symmetry between contralateral molars using CBCT.CBCT scans of 200 molars from 157 patients were selected for the study. A total of nine measurements - A (Distance from the cusp tip to the roof of the pulp chamber) B (Distance from the cusp tip to the floor of the pulp chamber) C (Distance from the cusp tip to the furcation) D (Distance from the floor of the pulp chamber to the furcation) E (Distance from the roof of the pulp chamber to the furcation) F (Height of pulp chamber) A1(Distance from the central fossa to the roof of the pulp chamber) B1 (Distance from central fossa till the floor of pulp chamber) C1 (Distance from central fossa to furcation) were done. Statistical analysis was done using the ANOVA and Post hoc tests and statistical significance was set at p<0.05. Significant differences in maxillary and mandibular molars were noted in the measurements of- D, E, B and C1. Bilateral symmetry was also observed between the pairs of maxillary and mandibular molars.Maxillary first and second molars do not differ much from each other. However, mandibular first and second molars differed in various anatomic parameters from each other. Contralateral molars (maxillary and mandibular) pulp cavities, in general, exhibit matching symmetry in terms of their morphological and anatomical landmarks.

Die Design and Finite Element Analysis of Welding Seams during Aluminum Alloy Tube Extrusion

Hollow tubes are generally manufactured using porthole die extrusion. A finite element software QForm is used to analyze the material flow of aluminum alloy A6061 tubes inside a specially designed porthole die during tube extrusion. High welding pressure and shorter transverse seam length are required for a sound product. Various extrusion conditions and die geometries and dimensions affect the bonding strength of the products. In this paper, the effects of die geometries on the welding pressure are discussed using the Taguchi method. The simulation results show that a higher welding pressure is obtained with a larger porthole radius, a larger welding chamber height, and a larger bearing length, while a larger bridge width increases the welding pressure slightly. For transverse seam lengths, a shorter transverse seam length can be obtained with a smaller porthole radius and a smaller welding chamber height, and a shorter bridge width and bearing length decrease the transverse seam length slightly. The transverse seam region and flow patterns are observed. Tube expanding tests were also conducted. From the expanding test results, it is known that the fracture position did not occur at the welding line and the bonding strength could reach up to 160 MPa.

Optimization of Key Hydraulic Structure Parameters of a New Type of Water–Pesticide Integrated Sprinkler Based on Response Surface Experiment

To meet the requirements of trellis grape crop root irrigation, spraying pesticides on branches and leaves, an integrated sprinkler was designed, which relies on the flow pressure to change the irrigation water and spray pesticide working modes. The structural parameters that affect the hydraulic performance were selected based on the working principle of the sprinkler. The key parameters for the irrigation mode included diversion hole inclination angle, refractive cone angle, refractive cone length, and cone hole distance. The key parameters for the spray pesticide mode included diversion chute width, the number of diversion chutes, the diversion chute inclination angle, the rotary acceleration chamber height, and the nozzle outlet cylindrical section length. The central composite design response surface tests of the water–pesticide integrated sprinkler were carried out; the analysis of variance and regression analysis were selected; the main influence rules and interactions of key structural parameters on irrigation performance and pesticide spraying performance of sprinkler irrigation system were obtained. The optimal parameters of the water–pesticide integrated sprinkler were: the diversion hole inclination angle is 20.8°, the refractive cone angle is 123.7°, the refractive cone length is 8.8 mm, the cone hole distance is 3.6 mm, the diversion chute width is 2.5 mm, the number of diversion chutes is 2, the diversion chute inclination angle is 10°, the rotary acceleration chamber height is 1.3 mm, and the nozzle outlet cylindrical section length is 0.7 mm. The irrigation hydraulic performance of the wetted radius is 3.4 m, the average irrigation application rate is 0.65 mm/h, and the uniformity coefficient is 88%. The spraying pesticide performance of the droplet volume mid-diameter is 200.2 μm, the droplet spectrum width is 2.2, and the droplet coverage is 9.4%.

Effect of humidity level and aspect ratio on convective heat transfer coefficient and water productivity of a solar still: Experimental and theoretical analysis

This article proposes a new correlation to estimate the convective heat transfer coefficient inside the evaporation chamber (enclosed space over the basin) of a single slope solar still with a low humidity level. The Rayleigh number, aspect ratio (width to the average height of chamber) and the relative humidity of the chamber are the main variables in proposed correlation. Existing models use only Rayleigh number to characterise the convection and neglect the effect of vapour pressure. Therefore, they fail to accurately predict the convection in higher water temperatures or in unsaturated humidity levels. In this work, the natural convection Nusselt number is generated based on a theoretical approach and the constant values in the correlation are calculated using the multiple linear regression analysis on experimental data obtained in this work. The transient thermal model of solar still using the new correlation predicts daily water yield within 7.6% of experiments under different humidity levels and aspect ratios. Higher performance is obtained in larger aspect ratio and lower humidity inside solar still. The modified solar still with a relative humidity of 62% generated 3.49 kg m−2 d−1 of water during summer in Melbourne, demonstrating an 18% increase in water yield.

Numerical study of the mechanisms of the longitudinal pulsed detonation in two-dimensional rotating detonation combustors

A numerical study of the longitudinal pulsed detonation (LPD) is conducted in the present paper. The occurrence mechanism of the LPD, called shock wave amplification by coherent energy release, is verified preliminarily in this study. To be specific, upstream propagating shock waves, which originate from the outlet, induce a specific gradient of reactant distribution, and then detonation waves are ignited and evolve along the gradient in close succession. It is worth noting that the occurrence of LPD does not mean that the LPD will necessarily be sustained. The low injection pressure ratio PR (i.e., the ratio of inlet pressure to outlet pressure) = 1.3 is found to be conducive to the sustenance of the LPD instability in the baseline model. A lower PR (PR ≤ 1.2) or a slightly higher PR (1.4 ≤ PR ≤ 1.8) shall lead to an unstable detonation or quenching of detonations, while a much higher PR (PR > 1.8) contributes to the formation of stable canonical rotating detonation waves. In addition, the combustion regimes of five combustors of different heights at different PR are explored. As the combustion chamber height increases, the PR of the sustainable LPD is nearly linearly increasing, and its operating frequency decreases gradually. The calculation formula between the sustainable LPD propagating frequency and the natural acoustic resonance frequency of the combustor is employed and discussed, but in consideration of its imperfection, further investigation is required.

Application Of Tooth Coronal Index (TCI) Benindra Method In Estimating Biological Age at Sultan Agung Dental Hospital Semarang

Background: Estimation of age through teeth is one way to identify living and dead individuals. Age estimates can clarify statements of death, legal and civil matters. One way to identify victims is using periapical radiographs. The use of periapical radiographs in age estimation requires certain method, one of which is the TCI (Tooth Coronal Index) Benindra method modified from Drusini's TCI method. Tooth age assessment using Benindra TCI method based on pulp chamber height measurements.Purpose: to clarify the application of TCI Benindra method in estimating biological age in Semarang population. Material and Method: This research was using total sampling method with a number of 23 periapical radiographs with 7 male and 16 female. The estimated age of the Benindra TCI method was done at the age of 9-21 years and using a mandibular premolar. Tooth age assessment was based on measurements of pulp chamber height using the TCI formula, the results of TCI measurements were entered into the prediction age formula to determine the biological age. Result: the average difference between biological age estimated used the Benindra method and chronological age reached 0,46 years in the 9-21 years age group. There were 7 data that underestimated, 6 data over estimation, and 10 data on estimation.Conclusion: The application of the Benindra TCI method shows good results in estimating the biological age of the Semarang population, because the difference between the estimated age and the chronological age produced by this method is quite small.

Morphology of the optic nerve head and factors affecting it in the Northern Finland birth cohort.

To assess topographic characteristics of the optic nerve head (ONH) and retinal nerve fibre layer (RNFL) and study the effect of ocular and physiological factors on them in a middle-aged population. A 1552-person randomised sample from Northern Finland population aged 45-49 was examined. Laser scanning tomography and optical coherency tomography were performed to obtain measurements for ONH and RNFL morphology. Measurements of the RNFL included global thickness and the six zones used in automated structure-function analysis (S-F analysis). Influence of central corneal thickness (CCT), refractive correction, intraocular pressure (IOP), anterior chamber angle, gender, blood pressure, height, weight and body mass index (BMI) on tomographic data was analysed. The optic disc area had a strong correlation with all other parameters of ONH morphology (R=0.261 to 0.706) as did spherical equivalent (R=-0.280 to 0.280). The correlations between ONH and RNFL measurements were weaker (R=0.057 to 0.180). Gender, CCT, anterior chamber angle, blood pressure, height and BMI had statistically significant, yet feeble, correlations with a number of ONH parameters. Other than spherical equivalent, the studied anatomical and physiological attributes had little predictive value on the ONH morphology. The optic disc area itself had a significant effect on other measurements of ONH tomography and should be taken into consideration when the thresholds for normal ONH morphology are calculated.

Scaling of Turbulence and Microphysics in a Convection–Cloud Chamber of Varying Height

AbstractThe convection–cloud chamber enables measurement of aerosol and cloud microphysics, as well as their interactions, within a turbulent environment under steady‐state conditions. Increasing the size of a convection–cloud chamber, while holding the imposed temperature difference constant, leads to increased Rayleigh, Reynolds and Nusselt numbers. Large–eddy simulation coupled with a bin microphysics model allows the influence of increased velocity, time, and spatial scales on cloud microphysical properties to be explored. Simulations of a convection–cloud chamber, with fixed aspect ratio and increasing heights of H = 1, 2, 4, and (for dry conditions only) 8 m are performed. The key findings are: Velocity fluctuations scale as H1/3, consistent with the Deardorff expression for convective velocity, and implying that the turbulence correlation time scales as H2/3. Temperature and other scalar fluctuations scale as H−3/7. Droplet size distributions from chambers of different sizes can be matched by adjusting the total aerosol injection rate as the horizontal cross‐sectional area (i.e., as H2 for constant aspect ratio). Injection of aerosols at a point versus distributed throughout the volume makes no difference for polluted conditions, but can lead to cloud droplet size distribution broadening in clean conditions. Cloud droplet growth by collision and coalescence leads to a broader right tail of the distribution compared to condensation growth alone, and this tail increases in magnitude and extent monotonically as the increase of chamber height. These results also have implications for scaling within turbulent, cloudy mixed‐layers in the atmosphere, such as fog layers.

Hydrodynamics of Energy-Efficient Axial-Flow Cyclones for Environmentally Safe Cleaning of Gas and Dust Emissions

We investigated the operation of an axial-flow cyclone as the most promising dust-cleaning equipment based on energy consumption. Numerical solutions were obtained for the gas-solids suspension flow equations in axial flow cyclones with different separation chambers’ geometry using FlowVision software. The chamber’s geometrical features determined the nature of the gas-solids suspension flow, directly affecting the dusty gases’ purification degree. The circulating gas flows and the turbulent “trace” after the swirl generator were found to negatively influence the cyclone efficiency and the hydraulic resistance values. A high chamber height also negatively affected the gas purification since the bulk of dust particles were removed from the gas-solids flow at the initial section. The initial section’s length coincided with the gas-solids suspension’s jet flow zone due to the flow coming off the swirl vanes’ edges. Due to turbulent mixing, the particles’ secondary entrainment and return to the gas flow began to manifest outside this zone. Based on this analysis, it is possible to develop recommendations for choosing the chamber’s geometric parameters, minimizing the influence of the indicated factors. On the basis of this research, it will be possible to ensure cyclones’ high efficiency with significantly lower hydraulic resistance when designing axial-flow cyclones relative to other types of cyclone.

ИССЛЕДОВАНИЕ СПОСОБОВ СНИЖЕНИЯ ВЫДЕЛЕНИЙ ОКСИДОВ АЗОТА ПРИ СЖИГАНИИ ТОПЛИВА В ТРУБЧАТЫХ ПЕЧАХ

A mathematical model of fuel combustion in tubular furnaces was developed. The model allows to calculate the concentration of nitrogen oxides in the exhaust gases for different configurations of the furnace and burners, different volume flow rates and methods of air supply to the furnace. In order to confirm the adequacy of the developed mathematical model, a numerical experiment was conducted for the existing basic furnace design with fuel combustion technology according to the current regulations. A slight (2.3%) discrepancy between the calculated and experimental values of the concentration of nitrogen oxides at the outlet of the operating furnace indicates the adequacy of the developed mathematical model. Subsequent numerical experiments to study various fuel combustion schemes for the purpose of decreasing NOx emission showed that the use of two-stage combustion in burners located in the same plane is ineffective. The use of this method allows to reduce the NOx yield by no more than 10%. The method of two-stage combustion by the height of the combustion chamber is more effective. The supply of a mixture of gases with an excess air coefficient of 0.8 to the burners and the supply of the remaining air higher along the cross section of the furnace allow reducing the total output of nitrogen oxides by 2,5 times.

Influence of geometric parameters on the performance of ejector used in aeroengine air system

By using an ejector to draw low-pressure, low-temperature air into the aeroengine's air system, it is possible to significantly enhance the cooling effect of the hot component of the engine. It is very necessary to clarify the sensitivity of ejector performance to different geometric parameters, especially the receiving chamber height, mixing chamber diameter, and diffuser diameter, which are of great significance to improve ejector performance and save limited aeroengine space. Therefore, this paper investigated the effects of these three geometric parameters on the ejector's performance by numerical simulation. The results show that increasing the mixing chamber diameter can significantly improve ejector performance. When the compression ratio is 1.17 and the mixing chamber diameter is increased from 3 mm to 9 mm, the entrainment ratio and the total pressure recovery coefficient are increased by 23.1 % and 7 %, respectively. Especially when the compression ratio is 1, simultaneously increasing the size of the receiving chamber, mixing chamber, and diffuser can greatly improve the ejector's performance. When the diameter of the mixing chamber is increased from 6 mm to 27 mm, the entrainment ratio and the total pressure recovery coefficient are increased by 211 % and 39 %, respectively. The change in ejector structure will influence its flow field and then affect the mixing process. When the size of the ejector is too small, the strong background shock wave suppresses the mixing of the primary flow and the secondary flow, which then causes an increase in the total pressure loss. When the size of the ejector is too large, the eddy current loss leads to ejector performance reduction.

Structural Attacks and Defenses for Flow-Based Microfluidic Biochips.

Flow-based microfluidic biochips (FMBs) have seen rapid commercialization and deployment in recent years for point-of-care and clinical diagnostics. However, the outsourcing of FMB design and manufacturing makes them susceptible to susceptible to malicious physical level and intellectual property (IP)-theft attacks. This work demonstrates the first structure-based (SB) attack on representative commercial FMBs. The SB attacks maliciously decrease the heights of the FMB reaction chambers to produce false-negative results. We validate this attack experimentally using fluorescence microscopy, which showed a high correlation ( R2 = 0.987) between chamber height and related fluorescence intensity of the DNA amplified by polymerase chain reaction. To detect SB attacks, we adopt two existing deep learning-based anomaly detection algorithms with ∼96% validation accuracy in recognizing such deliberately introduced microstructural anomalies. To safeguard FMBs against intellectual property (IP)-theft, we propose a novel device-level watermarking scheme for FMBs using intensity-height correlation. The countermeasures can be used to proactively safeguard FMBs against SB and IP-theft attacks in the era of global pandemics and personalized medicine.