Inside Pressure Research Articles

Design and Fabrication of Industrial Washing Machine for Heat Treated Metals

The clothes washer is generally utilized in the present day's general public for washing, drying of garments and furthermore for the warmth treatment procedure of metals and materials which has been created in the business these days. The vast majority of the crude materials utilized in the assembling procedure of the clothes washer have significant negative social and natural effects which incorporates mass scale extraction of metals, arrivals of harmful gases during creation and preparing, defilement of land and wellbeing perils causes in people and creatures. Subsequently it is imperative to relieve these impacts while accomplishing the social necessities. It is accepted that offering an assistance to supplant the residential clothes washer would be doable answer for this situation. Low carbon steel is having every single material property that are worthy for some applications which is required to have heat treatment process. Here we are thinking of completely mechanized mechanical utilization heat treated clothes washer for improve flexibility, durability, quality, hardness and rigidity and to remember interior pressure created in the materials.

Artificial Sensitive Skin for Robotics Based on Electrical Impedance Tomography

Electrical impedance tomography (EIT) is a noninvasive measurement technique that estimates the internal resistivity distribution based on the boundary voltage–current data measured from the surface of the conductor. If a thin stretchable soft material with a certain piezoresistive property is used as the electrical conductor, EIT has the ability to reconstruct the position where the resistivity changes due to the inside pressure contact, so that a large‐scale artificial sensitive skin is provided for robotics. First, the different conduction principles and material types of artificial sensitive skins are discussed, which is next followed by the different driving modes and image reconstruction techniques. Then, details on how EIT is used for robotic skin applications are described. Finally, the development trends and future potentials of EIT‐based robotic skins are expounded.

Hints on the origins of particle traps in protoplanetary disks given by the Mdust – M⋆ relation

Context. Demographic surveys of protoplanetary disks, carried out mainly with the Atacama Large Millimeter/submillimete Array, have provided access to a large range of disk dust masses (Mdust) around stars with different stellar types and in different star-forming regions. These surveys found a power-law relation between Mdust and M⋆ that steepens in time, but which is also flatter for transition disks (TDs). Aims. We aim to study the effect of dust evolution in the Mdust−M⋆ relation. In particular, we are interested in investigating the effect of particle traps on this relation. Methods. We performed dust evolution models, which included perturbations to the gas surface density with different amplitudes to investigate the effect of particle trapping on the Mdust−M⋆ relation. These perturbations were aimed at mimicking pressure bumps that originated from planets. We focused on the effect caused by different stellar and disk masses based on exoplanet statistics that demonstrate a dependence of planet mass on stellar mass and metallicity. Results. Models of dust evolution can reproduce the observed Mdust−M⋆ relation in different star-forming regions when strong pressure bumps are included and when the disk mass scales with stellar mass (case of Mdisk = 0.05 M⋆ in our models). This result arises from dust trapping and dust growth beyond centimeter-sized grains inside pressure bumps. However, the flatter relation of Mdust − M⋆ for TDs and disks with substructures cannot be reproduced by the models unless the formation of boulders is inhibited inside pressure bumps. Conclusions. In the context of pressure bumps originating from planets, our results agree with current exoplanet statistics on giant planet occurrence increasing with stellar mass, but we cannot draw a conclusion about the type of planets needed in the case of low-mass stars. This is attributed to the fact that for M⋆ < 1 M⊙, the observed Mdust obtained from models is very low due to the efficient growth of dust particles beyond centimeter-sizes inside pressure bumps.

Effect of Pressure on the Performance of Passive Two-Phase Closed Thermosyphon System Using R-134a

Two-phase closed thermosiphon system for cooling high heat flux electronic devices was constructed and tested on a lab scale. The performance of the thermosyphon system was investigated using R-134a as a working fluid. The effect of heat flux and the refrigerant pressure on the evaporator side heat transfer coefficient were investigated. It was found that the heat transfer coefficient increases by increasing the heat flux on the evaporator or by reducing the inside pressure. The effect of heat transfer mode of the condenser (natural or forced) also affected the overall heat transfer coefficient in the cycle. At the 200W heating load, the values of the heat transfer coefficients were 32 and 1.5 kW/m². ˚C, for natural and forced convection modes, respectively. The temperature difference between the evaporator and the refrigerant saturation pressure was found to be dependent on heat flux and the pressure inside the system. At 40 W heating load, the heat transfer coefficient was calculated to be 500, 3000 and 7300 W/oC.m2 at 0.152, .135 and 0.117 reduced pressure, respectively. It can be concluded that such a thermosyphon system can be used to cool high heat flux devices. This can be done using an environmentally friendly refrigerant and without any need for power to force the convection at the condenser.

Aural comfort prediction method for high-speed trains under complex tunnel environments

Aural comfort is negatively affected during a train’s passage through various tunnel environments. The objective of this study was to propose a prediction model for determining optimal operation parameter combinations to improve train occupants’ aural comfort. High-speed train model tests, combined with a mathematical transfer model, were used to obtain the interior pressure transients under varying speeds, tunnel lengths and seal indexes. Then, a middle ear finite element model was used to simulate the dynamic responses under the pressure transients, and three indicators were employed to assess the severity of aural sensations. Meanwhile, the aural discomfort were classified into four groups according to the duration. Based on the simulation results, the ordinal regression analysis method was used to reveal the effects of the considered factors on aural comfort. The results indicate that aural discomfort sensations begin when a train runs in the middle of a tunnel but are mitigated when it approaches the tunnel exit. Furthermore, aural discomfort is positively correlated with the train speed and the distance from the driver cabin of the head car but negatively correlated with the seal index and tunnel length. As a conclusion, a mathematical prediction model was established that incorporates factors including the train speed, seal index, tunnel length and car position. It can not only forecast aural sensations under certain operation parameters and tunnel environments but also be used for determining the optimal operation parameters to ensure the best aural sensations for high-speed-train occupants.

Shape stability and flow behaviour of a phase change material based slurry in coupled fluid-thermo-electrical fields for electronic device cooling

The suitable phase transition temperature range and low electrical conductivity make fatty acid-based Phase Change Material (PCM) slurries an attractive heat transfer fluid for cooling of High–Voltage Direct Current (HVDC) electronic devices. However, their shape instability induced by external electrical field may alter their effective thermophysical properties and hence the heat transfer performance. In this work, the shape stability and flow behavior of a fatty acid droplet under a coupled fluid-thermo-electric coupled field are numerically investigated. The effects of droplet size, fluid velocity and temperature, and electrical field on the shape and energy of the droplet are evaluated. The results show that the droplet size is the major influencing factor for the shape stability. Given other conditions, the deformation ratio and the internal pressure difference of a 1 μm droplet are respectively 8 times higher and 5 times larger than a 7 μm droplet. An increase in the slurry velocity only slightly increases the particle interior pressure; given other conditions, an increase in the velocity from 0.22 m/s to 1.1 m/s only leads to an internal pressure increase by 25.77%. The electrical stress across the surface tends to squeeze the droplet into a prolate shape, offsetting the shape deformation by the shear stress and hence stabilizing the PCM slurry. The presence of the electrical field slows down the energy evolution and reduces the pressure difference inside the droplet.

Validation of a coupled pressure-equalization-thermal-mechanical model to study double-skin facades

Although double skin façades are a well-known façade system, still few experimental data and numerical approaches exist in literature that couple their thermal behaviour and pressure equalisation with the structural response. The reason is that, differently from insulating glazing units, the extent of the problem is trivial when designing ventilated double skins. Indeed, the leakage of the double skin cavity is large enough to avoid any response of the internal cavity pressure to its temperature variations. However, during the last years Closed Cavity Façades, a new trend of double skins, have been applied in order to achieve high performances in terms of thermal and acoustic insulation and providing at the same time valuable benefit with regards to maintenance cost reduction. The CCF low levels of air permeability are responsible for a strong correlation of pressure and temperature of its cavity and the phenomenon needs an accurate model to support the design. Indeed, an optimal design of the outer and inner skin should consider the skin interactions and their coupling through the cavity, under the dynamic temperature and variable mass within the cavity itself. The mass variation is governed by two counteracting effects: on one side the dry and clean air that is pumped into the cavity in order to avoid the risk of condensation, on the other side the mass flows through the skin openings that connects cavity with external and internal environment. Moreover, the pressure is also affected by the interior and exterior air pressures that induce a deflection of the inner and outer skin. A numerical calculation procedure was developed, integrated with commercial codes commonly used in façade design, in order to provide a unique assessment tool for the coupled thermal-mechanical design of double skin facades. The tool has been validated by means of an extensive experimental campaign and the different relevant effects have been described.

Characterizing a System for Measuring Limb Tourniquet Pressures

Pressure is an important variable in emergency use limb tourniquet science. This study characterizes one system for measuring tourniquet-applied pressure.A neonatal blood pressure cuff bladder was inflated to target pressures over atmospheric. Unconstrained or constrained within 1-inch tubular polyester webbing, the neonatal cuff was placed in a 500mL Erlenmeyer flask. A 3-hole stopper provided connections to flask interior (chamber) and bladder pressure sensors and a 60mL syringe for altering chamber pressure: atmospheric to >1500mmHg absolute to atmospheric.Within a finite range of chamber pressures, the neonatal cuffbased system accurately indicates applied pressure (minimum and maximum 95% confidence interval linear regression slopes of 0.9871 to 0.9953 and y-intercepts of -0.1144 to 2.157). The visually defined linear response ranges for bladder inflation pressures were as follows for unconstrained/ constrained: 100 to 400mmHg unconstrained/450mmHg constrained for 10mmHg, 150 unconstrained/100 constrained to 450mmHg for 12mmHg, 150 to 500mmHg for 15mmHg, 150 to 500mmHg unconstrained/550mmHg constrained for 18mmHg, 150 to 550mmHg for 21mmHg. Below the linear response range, the inflated bladder system indicated higher pressures than chamber pressures. Above the linear response range, the system indicated progressively lower pressures than chamber pressures.Within the linear response range, the bladder pressure accurately indicates surface-applied pressure.

Life Prediction of Thin Wall Pipe for External Superficial Cracked Exposed to Interior Pressure

Life Prediction of Thin Wall Pipe for External Superficial Cracked Exposed to Interior Pressure

Account for high flow rate-low detrusor pressure voids in female: Contribution of VBN model

Nomograms using the VBN model of women micturition allowed evaluating detrusor contractility (k) and urethral obstruction (U) from pressure-flow (PFs) recordings. While the model worked for most of the patients, an intriguing result, negative U value was observed for patients with high flow-low detrusor pressure (Qp voids). To explain that condition, our hypothesis was a weak urethral resistance to dilatation or increased expansibility (URD). The area offered to the fluid at each point of the urethra (its dilatation) is a function of the time depending difference between inside and outside pressures. In the VBN model, this function is sigmoid-like, the same for all women. For Qp voids, Qrecorded was more higher than it would be with the recorded pressure (VBN analysis). So, modeling allowed computing abnormally increased urethral wall expansibility (URD) whose consequence would be an increased flow. Among 222 non-neurologic women referred for investigation of various lower urinary tract symptoms, 27 (mean age 66.3±11.4 y) had Qp void: Qmax=27±6mL/s; pdet.Qmax =7.5±4.7cm H2O. Mean URD value was .36±.67. Introduction of URD in a modeled analysis of urodynamic traces led to a good fitting between recorded and computed traces for the 27 Qp. Mathematical modeling of micturition allows proposing an explanation of the unexpected observations of Qp voids. They would be due to abnormal urethral wall elasticity. Despite major challenges measurement of this elasticity would be the next step. 3.

Field measurements of the interior and exterior aerodynamic pressure induced by a metro train passing through a tunnel

Aerodynamic effects (in particular the pressure variation) induced by the passage of a metro train in a tunnel intensify with the increase of train speed. When the interior pressure fluctuation of carriages exceeds limits, it may cause passengers’ ear discomfort and even could cause serious injury. In this paper, field measurements have been used to study the influences of tunnel portals, airshafts and train speeds on the interior and exterior pressure variation of the metro train. The influence of pressure changes on passengers’ ear comfort was also analysed in detail. The results show that the tunnel portal, the airshaft and the train speed are important factors that cause the fast pressure change inside and outside the metro train. When the airshaft is open, the interior and exterior aerodynamic pressure changes increase. The amplitudes of interior pressure variations of the metro train are dependent on running directions. From the entrance to the exit as defined, the amplitudes are approximately proportional to the train speed at a power exponent of 1.5–1.6, while changing the running direction those are approximately proportional to the train speed at a power exponent of 1.0–1.1. Additionally, when the metro train passes the tunnel interval with a clearance design diameter of 5.5 m at the speed of greater than 80 km/h and the tunnel interval includes a portal, it would pose a risk of passengers’ ear discomfort. Thus, the running direction of the metro train should be considered in evaluating passengers’ ear comfort.

THE SPRING VARIATION IN TWO DIMENSIONAL MODELING OF RED BLOOD CELL DEFORMABILITY BASED ON GRANULAR

The red blood cell membrane has a complex structure and high deformability. Simulation of that complex red blood cell membrane can simpler use granular-based modeling. Red blood cell is modeled consisting of 50 granular particles connected by springs. An i-particle is connected with two of its first nearest particles which are i+1-particle and i-1-particle and with two of its second nearest particles which are i+2-particle and i-2-particle. Each particle has a spring force and forces from internal hydrostatic pressure. Spring force is a product of the spring constant and change of spring length of two particles. Meanwhile, forces of internal hydrostatic pressure is a product of particle diameter and the difference in the outside and inside pressure of red blood cell membrane. In this research, there is variation in spring length and spring constant that can model deformability of three shapes of red blood cell; those are biconcave, ellipse, and circle. This variation in spring length and spring constant for every cell shape in this modeling can also use for other initial cell shapes, which shows that initial cell shapes deform into shape according to variation used.

An Investigation on the Possible Radioactive Contamination of Environment during a Steam-Line Break Accident in a VVER-1200 Nuclear Power Plant

In this work, the possibility of contamination of environment by radioactive elements due to a steam-line break accident has been investigated for a VVER-1200 type nuclear power plant. Personal Computer Transient Analyzer (PCTRAN) has been used to generate the response data of the plant safety systems numerically for an accidental condition like such. A break of 1000 cm2 in the A-loop of the steam line has been considered. A break of the size is considered a “Large Break”, which is believed to be responsible for multiple serious accidents in the past. Also, it has also been assumed that off-site AC power supply is unavailable. Simulations were run for time duration of 300 seconds since most of the safety features of the plant should respond within 50 seconds from the initiation of the accident. Results show that SCRAM is initiated within 22.5 seconds from the emergence of the break, which limited the peak core thermal power to around 105% of the nominal value. The peak temperatures of fuel elements and fuel cladding are recorded to be around 1850oC and 620oC respectively, which are both within the safety limits. The pressure inside reactor pressure vessel has not undergone any significant changes, showing no sign of failure. Again, the pressure inside the reactor containment building is kept within 2.5 bar by the safety systems, indicating that there is no possibility of containment failure due to over-pressure. Finally, the readings from radiation monitor show that there is no noticeable release of radioactive elements to the environment during the accident. Therefore, it may be concluded that the release of radioactive elements in the surrounding environment during a steam-line break accident is very unlikely provided that the plant safety systems are fully functional.

Revisiting the Classical Emulsion Polymerization: An Intriguing Occurrence of Monodispersed Bowl-Shaped Particles

An intriguing phenomenon is found that monodispersed bowl-shaped rather than spherical poly(styrene-co-butyl acrylate) [P(St-co-BA)] particles can be obtained by one pot traditional emulsion polymerization without using any template or redundant process and the cavity size is controllable. The facile implementation method is beneficial to large-scale fabrication of the bowl-shaped particles. Herein, the amphiphilic oligomeric radical with hydrophobic P(St-co-BA) chains and hydrophilic sulfate groups ([−OSO3]−) from water-soluble potassium persulfate could migrate to surface of primary latex particles to act as an emulsifier when amount of the additional emulsifier is so low, which causes an imbalance between inside and outside osmotic pressures of the latex particles to result in bowl-shaped particles for the kinetic stability. This advances the understanding of classical emulsion polymerization mechanism.

Comparative Numerical Simulation in a 2D Combustion Chamber, Based on the Finite Volume Method

Combustion chambers are used in energy systems mainly to increase heat transfer. In this paper, a modern design procedure of a combustion chamber of a boiler is presented, in order to improve temperature distribution over the combustion chamber borders, as well as the combustion dynamics such as interior pressure and combustion velocity. The design process is mainly based on changing the geometric aspects of the combustion chamber, more particularly the geometry of the bottom side. Thus, a simulation study using Fluent Software has been carried out on two main geometries, namely: a cylindrical combustion chamber with a flat bottom and another one with a convex bottom respectively. The simulation results have shown remarkable improvements in the combustion chamber in case of convex bottom behavior in terms of temperature distribution and heat transfer and therefore the good efficiency of the boiler

Liquid-Phase Electron Microscopy with Controllable Liquid Thickness

Liquid-phase electron microscopy (LPEM) is capable of imaging nanostructures and processes in a liquid environment. The spatial resolution achieved with LPEM critically depends on the thickness of the liquid layer surrounding the object of interest. An excessively thick liquid results in broadening of the electron beam and a high background signal that decreases the resolution and contrast of the object in an image. The liquid thickness in a standard liquid cell, consisting of two liquid enclosing membranes separated by spacers, is mainly defined by the deformation of the SiN membrane windows toward the vacuum side, and the effective thickness may differ from the spacer height. Here, we present a method involving a pressure controller setup to balance the pressure difference over the membrane windows, thus manipulating the shape profiles of the used silicon nitride membrane windows. Electron energy loss spectroscopy (EELS) measurements to determine the liquid thickness showed that it is possible to control the thickness precisely during an LPEM experiment by regulating the interior pressure of the liquid cell. We demonstrated atomic resolution on gold nanoparticles and the phase contrast using silica nanoparticles in liquid with controlled thickness.

Evaluation of numerical ablation model for charring composites

Charring composites are widely used in the thermal protection system (TPS) to consume the intense aerodynamic heating during vehicle reentry. The ablation and thermal responses for the charring composites can be studied by using a numerical ablation model, in which the surface ablation and volume ablation could be taken into account. The coupling interactions among temperature, gas motion and interior pressure producing the pyrolysis gas could make the computation more complicated. A multi-physics model is developed to simulate the thermal response coupled with volume ablation and surface ablation. After studying four typical ablation cases, the model is validated, and then the heat transfer mechanisms in ablation are investigated. It is found that the viscous dissipation energy by the motion of pyrolysis gas can be neglected in the simulation. Also, the flow of pyrolysis gas plays an important role in the temperature response, especially under high heat flux condition.

Investigating the effects of transient flow in concrete-lined pressure tunnels, and developing a new analytical formula for pressure wave velocity

One of the most common problems in concrete-lined pressure tunnels is the development of cracks in the concrete lining as a result of high internal transient pressure. Due to the rapid operations of hydraulic systems, transient flow establishes in the tunnel, and thereby, the unsteady water flow imposes high pressure on the lining. In this situation, an increase in the width and depth of cracks leads to leakage from the lining, and ultimately results in structural failure. Therefore, the effects of transient flow, as well as the pressure fluctuations inside pressure tunnels, must be considered in the design. In the present study, a two-dimensional concrete-lined pressure tunnel is modeled using Abaqus FEA (Finite Element Analysis) software, and steady-state and transient flow analyses are performed using the HAMMER software. The loads that result from the hydraulic analyses are used for the structural analysis of the lining. In this regard, first, the pressure wave velocity in the tunnel is calculated by a quasi-static method, using numerical modeling and a developed analytical formula. Then the effects of the grouted zone on the generated pressure waves are examined. Finally, the impact of the pressure wave on crack formation in the lining is studied, and the bearing capacity of the lining is evaluated. The stress analysis of the cracked elements in the concrete lining is conducted based on concrete damage plasticity behavior. It is observed that numerical modeling results indicate higher pressure wave velocity values than the analytical formula results, which can be attributed to the consideration of the rock load in the numerical model. Further, the operation schedule of the control gates influences the formation of cracks in the concrete lining. Considering non-linear behavior, the ultimate bearing capacity of the tunnel concrete lining is obtained, which can be used for the optimal design of the hydraulic systems.

Assessment methodology for pressure-related aural discomfort in high-speed trains using airtightness experiments and mathematical models

This study aimed at establishing an evaluation methodology for aural discomfort induced by the interior pressure changes in high-speed trains running in tunnels. Experiments in pressure cabin, which can reveal the relationship between aural discomfort and pressure change, were discussed. Furthermore, a human middle ear model was used to simulate the vibration. The experimental conditions were considered as pressure loads, which were exerted on the tympanic membrane. Furthermore, the aural discomfort was hierarchically divided into four levels: ideal, good, bad, and worse. Four indicators, such as the tympanic membrane displacement and stress and the stapes footplate displacement and velocity, were used to establish the discomfort criteria. Logistic regression analysis was used to investigate the incidences of each level as well as to obtain the thresholds between levels. The outcomes have a p-value of less than 0.05; hence, the response results of the indicators are statistically significant. Additionally, the thresholds of the indicators were obtained and used to differentiate the aural discomfort levels. The intervals of the four indicators are (0,T1), (T1,Tc), (Tc,T3), and (T3,>T3) for the discomfort levels of ideal, good, bad, and worse, respectively. Moreover, the onset mechanism of aural sensations was revealed using the four indicators. It can be implied that large tympanic membrane and stapes footplate displacements tend to elicit ear complaints, such as fullness, otalgia, and vertigo, whereas the large stapes footplate velocity affects the onset of tinnitus and hearing loss.

Seismic response analysis and damping method of spherical liquid storage tank

Earthquake is a natural disaster with outburst and ruinous in the world. The damage of spherical liquid storage tank due to earthquake can result in serious deaths and economic loss. In this thesis, the analysis of seismic response of spherical tank, which considering interior pressure, gravity, liquid sloshing and earthquake, is carried out. Seismic response analysis shows that the spherical tank rotates horizontally while rotating a small amount around the horizontal axis, mainly around the vertical axis. Time-history analysis of the tank under passive control is performed. The spherical tank model with dissipative bracing system installed has a very good damping effect by comparing the seismic responses of controlled and uncontrolled structures.