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Abstract Glaucoma, a blinding eye disease with optic neuropathy, is usually associated with elevated intraocular pressure (IOP). The currently available pharmacological and surgical treatments for glaucoma have significant limitations and side effects, which include systemic reactions to medications, patient non-compliance, eye infections, surgical device failure, and damage to the eye. Here, we present Sensor-Actuator-Modulator (SAM), an engineered double mutant version of the bacterial stretch-activated mechanosensitive channel of large conductance (MscL) that directly senses tension in the membrane lipid bilayer of cells and in response, transiently opens its large nonspecific pore to release cytoplasmic fluid. The heterologously expressed mechanosensitive SAM channel acts as a tension-activated pressure release valve in trabeculocytes. In the trabecular meshwork (TM), SAM is activated by membrane stretch caused by elevated IOP. We have identified several SAM variants that are activated at physiologically relevant pressures. Using this barogenetic technology, we have demonstrated that SAM is functional in cultured TM cells, and successfully transduced in vivo in TM cells by use of AAV2/8. Further, it is effective in enhancing aqueous humor outflow facility leading to lowering the IOP in a mouse model of ocular hypertension.

Glaucoma, a blinding eye disease with optic neuropathy, is usually associated with elevated intraocular pressure (IOP). The currently available pharmacological and surgical treatments for glaucoma have significant limitations and side effects, which include systemic reactions to medications, patient non-compliance, eye infections, surgical device failure, and damage to the eye. Here, we present Sensor-Actuator-Modulator (SAM), an engineered double mutant version of the bacterial stretch-activated mechanosensitive channel of large conductance (MscL) that directly senses tension in the membrane lipid bilayer of cells and in response, transiently opens its large nonspecific pore to release cytoplasmic fluid. The heterologously expressed mechanosensitive SAM channel acts as a tension-activated pressure release valve in trabeculocytes. In the trabecular meshwork (TM), SAM is activated by membrane stretch caused by elevated IOP. We have identified several SAM variants that are activated at physiologically relevant pressures. Using this barogenetic technology, we have demonstrated that SAM is functional in cultured TM cells, and successfully transduced in vivo in TM cells by use of AAV2/8. Further, it is effective in enhancing aqueous humor outflow facility leading to lowering the IOP in a mouse model of ocular hypertension. [ABSTRACT FROM AUTHOR]

The present paper provides a brief overview of the existing methods for energy separation and an analysis of the possibility of the practical application of the Hartmann–Sprenger effect to provide quasi-isothermal pressure reduction of natural gas at the facilities within a gas transmission system. The recommendations of external authors are analyzed. A variant of a quasi-isothermal pressure regulator is proposed, which assumes the mixing of flows after energy separation. Using a numerical simulation of gas dynamics, it is demonstrated that the position of the resonators can be determined on the basis of calculations of the structure of the underexpanded jet without taking into account the resonator and, accordingly, without the need for time-consuming calculations of the dynamics of the processes. Based on the results of simulating the gas dynamics of two nozzle–resonator pairs installed in a single flow housing, it is shown that, in order to optimize the regulator length, the width of the passage between the two nearest resonators should be greater than or equal to the sum of diameters of the critical sections of the nozzles. Numerical vibroacoustic analysis demonstrated that the most dangerous part of the resonator is the frequency of its natural oscillations. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cells from different organs in the body experience a range of mechanical and osmotic pressures that change in various diseases, including neurological, cardiovascular, ophthalmological, and renal diseases. Here, we demonstrate the use of an engineered Sensor-Actuator-Modulator (SAM) of microbial origin derived from a mechanosensitive channel of large conductance (MscL) for sensing external mechanical stress and modulating activities of mammalian cells. SAM is reliably expressed in the mammalian cell membrane and acts as a tension-activated pressure release valve. Further, the activities of heterologously expressed SAM in mammalian cells could be modulated by osmotic pressure. A comparison of the mechanosensitive activities of SAM-variants from different microbial origins shows differential inward current and dye uptake in response to mechanical stress exerted by hypo-osmotic shock. The use of SAM channels as mechanical stress-activated modulators in mammalian cells could provide new therapeutic approaches for treating disorders related to mechanical or osmotic pressure.

Currently, when creating the actuators of deep-sea vehicles and other technical facilities, there is a tendency to accommodate the elements of the hydraulic drive outside the durable housing. Such hydraulic systems are subject to the risk of depressurization, which leads to the ingress of working fluid (mineral oils or synthetic working fluids) into seawater and flooding of the hydraulic system's working fluid with seawater. The ingress of the working fluid into seawater leads to the violation of environmental safety, and if seawater enters the internal cavities of the hydraulic system, they may be damaged, which will require long and expensive repair in the future. One of the possible ways to eliminate the listed consequences of depressurization of outboard hydraulic systems is the creation of hydraulic equipment using seawater as a working fluid. The cheapest design of such a regulatory body is the use of shut-off valves with elastic tubular control elements. The research carried out confirmed the possibility of creating low-noise regulators with elastic control elements. These regulators have better vibroacoustic characteristics than spool-type throttles with similar functional characteristics. Preservation of the operating characteristics of regulators with elastic regulating elements when working with working fluids of different viscosities (PGV liquid, mineral oil, tap water) was confirmed. Survivability of a regulator with elastic control elements during long-term tests was confirmed. As a result of the work carried out, research and technological groundwork was obtained that allows creating a device with elastic regulating elements, having a flow differential characteristic that meets modern requirements, a vibroacoustic characteristic that meets advanced requirements and sufficient reliability when working on clean working fluids.

The present paper provides a brief overview of the existing methods for energy separation and an analysis of the possibility of the practical application of the Hartmann–Sprenger effect to provide quasi-isothermal pressure reduction of natural gas at the facilities within a gas transmission system. The recommendations of external authors are analyzed. A variant of a quasi-isothermal pressure regulator is proposed, which assumes the mixing of flows after energy separation. Using a numerical simulation of gas dynamics, it is demonstrated that the position of the resonators can be determined on the basis of calculations of the structure of the underexpanded jet without taking into account the resonator and, accordingly, without the need for time-consuming calculations of the dynamics of the processes. Based on the results of simulating the gas dynamics of two nozzle–resonator pairs installed in a single flow housing, it is shown that, in order to optimize the regulator length, the width of the passage between the two nearest resonators should be greater than or equal to the sum of diameters of the critical sections of the nozzles. Numerical vibroacoustic analysis demonstrated that the most dangerous part of the resonator is the frequency of its natural oscillations.

This study is focused on energy harvesting. The goal was to develop a new energy-harvesting system using a pressure regulator and establish an efficient energy flow model within it. The harvested electrical energy can be used as a power source for devices around the regulator, such as primary battery-powered gas meters, thereby enabling battery-free operation. Here, we focus on pressure regulators for LP and city gases, which are used by a vast number of consumers. We systematically modeled complicated energy-conversion processes using the transfer matrix method to maximize the recovered electrical energy. Under normal gas usage conditions, the gas flow is low, and the harvested energy is limited. However, it surpasses the energy supplied by the primary batteries. The results obtained under the actual operational conditions were compared with those calculated using a theoretical model. Within the system, a DC motor and an AC motor were used as generators, and the results were compared. When a DC motor was used as the generator under 0.05 MPa, 0.8 L/m, and maximum power-harvesting load conditions, the harvested power was 0.237 W, which is sufficient to drive the meters. Additionally, the error between the experimental and theoretical results ranged from 2.6% to 4.6%. When an AC motor was used as a generator, the harvested energy was 0.015 W and the error was −14.7%. Utilizing this theoretical model allows for the calculation of the optimal conditions for energy harvesting from various pressure regulators, thereby offering design guidelines for energy-harvesting systems.

Abstract The pneumatic vibration isolator (PVI) plays an increasingly important role in precision manufacturing. In this paper, aiming to detect the performance of the pressure regulator in the PVI system, a PVI testing system with a pressure regulator is designed and developed. Firstly, the structure of the pneumatic spring is presented and analyzed, and the nonlinear stiffness is obtained based on the ideal gas model and material mechanics. Then, according to the working principle and continuity equations of ideal airflow, a dynamic model of the PVI system with a pressure regulator is established. Through the simulation analysis, the vibration isolation performance is improved with the efficient and precise pressure regulator. The average values of both the vibration velocity and transmission rate decrease when the vibration is set to 4, 10, 20 and 40 Hz, respectively. The experiments demonstrate the reliability and effectiveness of the pressure regulator. This achievement will become an important basis for future research concerning precision manufacturing.

The article shows the areas of use of pneumatic protective and regulating devices in the enrichment of gas concentrates. Examples of technological schemes based on the application of pneumatic regulators are given. Reducers of the "after itself" type serve to reduce the pressure of gas supplied from highpressure receivers, a group of cylinders and receivers. The inclusion of such regulators allows you to reduce the inlet pressure to a level corresponding to the characteristics of the compressors or the technological modes of the units. Reducers "to itself" serve to stabilize the pressure in the devices-sources of gas concentrates. When selecting a Ne-He mixture from a number of different types of air separation units into the phase separator (dephlegmator), such regulators are able to ensure the coordinated operation of several units and eliminate the overflow of the mixture and violation of air separation. Reducers "to itself" can perform the functions of preventive protective valves along with typical safety valves. Unlike the latter, regulators "to itself" have greater sensitivity and are able to reduce the pressure in the installation smoothly, without disrupting the technological process. In this case, the regulators are adjusted to 0.2...0.3 MPa below the pressure of the main safety valve. Examples of circuits based on the use of pneumatic regulators in inert gas enrichment systems are given. The case of sampling the mixture directly from the source and feeding it uniformly into the column with increased (relative to the source) pressure is considered. This option involves matching the compressor flow rate with the column performance through the use of periodic compression and receivers. Calculation models allow predicting the change in pressure during the cycle. Depending on the performance of the unit, the minimum volume of the receiver is calculated, which ensures the continuity of the mixture supply to the column. The proposed schematic solutions allow for stable operation of units for the enrichment of inert gas concentrates. [ABSTRACT FROM AUTHOR]

Among the alternative fuels enabling the energy transition, hydrogen-based transportation is a sustainable and efficient choice. It finds application both in light-duty and heavy-duty mobility. However, hydrogen gas has unique qualities that must be taken into account when employed in such vehicles: high-pressure levels up to 900 bar, storage in composite tanks with a temperature limit of 85 °C, and a negative Joule–Thomson coefficient throughout a wide range of operational parameters. Moreover, to perform a refueling procedure that is closer to the driver's expectations, a fast process that requires pre-cooling the gas to −40 °C is necessary. The purpose of this work is to examine the major phenomena that occur during the hydrogen refueling process by analyzing the relevant theory and existing modeling methodologies. [ABSTRACT FROM AUTHOR]

Here, we describe the development of an organ-on-a-chip platform that enables ex vivo studies under active physio-mechanical stress by applying hydrodynamic and mechanical forces to vascular endothelial cells. Access to current platforms for such studies is hampered by the need for advanced fabrication techniques to create these platforms, and the need for extensive ancillary equipment for their operation. The platform design and fabrication approach reported here aims to improve accessibility of microfluidic technology for ex vivo mechanobiology studies to the broader biomedical research community. Dual-layer lithography was used to significantly reduce the technical expertise and equipment required to create porous, stretchable membranes that serve as the substrate for cells. A cost-effective, portable pressure regulator was created to apply physiologically relevant cyclic stretch (to resemble breathing) across pulmonary endothelial cells grown on the porous membrane. The use of cyclic olefin copolymer sheets helped reduce the total thickness of the microfluidic platform to about 3 mm, enabling fluorescence imaging 'on-chip'. Furthermore, the reversible bond between the cyclic olefin copolymer lid and the rest of the platform allows for exposure of the cells to aerosolized particulates. To validate the capacity to image cells in situ, we obtained subcellular actin images of bovine aortic endothelial cells and human pulmonary aortic endothelial cells 'on-chip'. Overall, we present an accessible microfluidic platform that exposes endothelial cells to physiologically relevant shear and/or cyclic stretch, and allows for post exposure 'on-chip' cell imaging. [ABSTRACT FROM AUTHOR]

The application of expansion turbines at natural gas pressure reduction stations (PRS) is considered in order to recover energy contained in the natural gas. This energy is irretrievably lost at the reduction stations which use the traditional pressure reducer. Expanders allow for the electricity production for PRS own needs and for resale. The paper presents an analysis of the possibility of using turboexpanders at PRS in Poland. Authors performed static simulations for the assumed data sets and dynamic simulations for annual data from selected representative natural gas reduction and measurement stations. Energy balances are presented for the discussed scenarios that compare the energy requirements of natural gas pressure reduction stations which use a classic pressure reducer or turboexpander (TE). Using static simulations, authors investigated whether the use of a turboexpander is economically justified for the case if it is used only to supply the reduction station with electricity. Dynamic analyses were carried out using real data. In addition, static analyses were performed for a natural gas reduction and measurement station using a PEM fuel cell for the production of electricity in a combined gas heating system. At higher inlet temperatures and pressures, the expansion process was more economical due to the lower heat power requirement and the greater amount of produced electricity. The PRS with the turboexpander compared to the PRS with the reducer required the supply of thermal energy which did not allow the PRS to lower operating costs for the assumed prices of heat and electricity. The reduction system with the PEM fuel cell in the combined heating system positively achieved lower operating costs of the PRS (without taking into account the investment costs). Total annual costs for PRS with a reducer was PLN 1,593,167.04, and for PRS with TE + PEM PLN 1,430,595.60—the difference was PLN 108,571.44 in favor of the arrangement with TE and PEM. The payback time should be investigated, although the use of such a system gives the impression of oversizing. An increase in the electricity purchase price and a decrease in the natural gas purchase price may contribute to the investment in the future. [ABSTRACT FROM AUTHOR]

The pneumatic vibration isolator (PVI) plays an increasingly important role in precision manufacturing. In this paper, aiming to detect the performance of the pressure regulator in the PVI system, a PVI testing system with a pressure regulator is designed and developed. Firstly, the structure of the pneumatic spring is presented and analyzed, and the nonlinear stiffness is obtained based on the ideal gas model and material mechanics. Then, according to the working principle and continuity equations of ideal airflow, a dynamic model of the PVI system with a pressure regulator is established. Through the simulation analysis, the vibration isolation performance is improved with the efficient and precise pressure regulator. The average values of both the vibration velocity and transmission rate decrease when the vibration is set to 4, 10, 20 and 40 Hz, respectively. The experiments demonstrate the reliability and effectiveness of the pressure regulator. This achievement will become an important basis for future research concerning precision manufacturing. [ABSTRACT FROM AUTHOR]

The impact of two parameters - the pressure regulator X1 at the nozzle and the speed of the machine X2 for the amount of water flow through the sprinkler (Y, mm) experiment were determined by 8 mm diameter nozzles. The experiment was carried out in the laboratory of “Design of Irrigation and Equipment” used by “Sprinkler’s uniformity distribution measuring equipment” at the School of Engineering and Technology of MULS. In order to determine the rain intensity of low pressure sprinkler nozzle, mathematical statistical methods was used and it was found that the maximum amount of water supplied by the sprinkler nozzle is 1.727 mm/min with a maximum pressure of 30 PSI and a minimum speed is 1 m / min with a minimum flow rate of 0.313 mm/min. At a pressure regulator value of 20 PSI, the speed was a maximum of 3 m/min.

The application of expansion turbines at natural gas pressure reduction stations (PRS) is considered in order to recover energy contained in the natural gas. This energy is irretrievably lost at the reduction stations which use the traditional pressure reducer. Expanders allow for the electricity production for PRS own needs and for resale. The paper presents an analysis of the possibility of using turboexpanders at PRS in Poland. Authors performed static simulations for the assumed data sets and dynamic simulations for annual data from selected representative natural gas reduction and measurement stations. Energy balances are presented for the discussed scenarios that compare the energy requirements of natural gas pressure reduction stations which use a classic pressure reducer or turboexpander (TE). Using static simulations, authors investigated whether the use of a turboexpander is economically justified for the case if it is used only to supply the reduction station with electricity. Dynamic analyses were carried out using real data. In addition, static analyses were performed for a natural gas reduction and measurement station using a PEM fuel cell for the production of electricity in a combined gas heating system. At higher inlet temperatures and pressures, the expansion process was more economical due to the lower heat power requirement and the greater amount of produced electricity. The PRS with the turboexpander compared to the PRS with the reducer required the supply of thermal energy which did not allow the PRS to lower operating costs for the assumed prices of heat and electricity. The reduction system with the PEM fuel cell in the combined heating system positively achieved lower operating costs of the PRS (without taking into account the investment costs). Total annual costs for PRS with a reducer was PLN 1,593,167.04, and for PRS with TE + PEM PLN 1,430,595.60—the difference was PLN 108,571.44 in favor of the arrangement with TE and PEM. The payback time should be investigated, although the use of such a system gives the impression of oversizing. An increase in the electricity purchase price and a decrease in the natural gas purchase price may contribute to the investment in the future.

The impact of two parameters - the pressure regulator X1 at the nozzle and the speed of the machine X2 for the amount of water flow through the sprinkler (Y, mm) experiment were determined by 8 mm diameter nozzles. The experiment was carried out in the laboratory of "Design of Irrigation and Equipment" used by "Sprinkler's uniformity distribution measuring equipment" at the School of Engineering and Technology of MULS. In order to determine the rain intensity of low pressure sprinkler nozzle, mathematical statistical methods was used and it was found that the maximum amount of water supplied by the sprinkler nozzle is 1.727 mm/min with a maximum pressure of 30 PSI and a minimum speed is 1 m / min with a minimum flow rate of 0.313 mm/min. At a pressure regulator value of 20 PSI, the speed was a maximum of 3 m/min. [ABSTRACT FROM AUTHOR]

High-pressure pumps for microfluidic systems typically require high power and have large sizes, which hinder portability of otherwise miniaturized HPLC systems. To solve this, a battery-powered, pneumatic system for pressure-driven chromatography is presented. The system utilizes the stored energy in pressurized gas without consuming any of the gas. As the chromatography liquid flows, the gas in the pressure container expands and its pressure reduces. To compensate for this, a solution is presented with an on-chip microfluidic pressure regulator. The chip contains a microfluidic restrictor where fluid is heated by Joule heating to decrease viscosity, and thus reduce the pressure drop over the restrictor. An 18 V battery driven system with 50 ml N 2 at 51 bar could provide a water flow rate of 55 μ l /min at 32 bar for 67 min with a mean power consumption of 0.2 W. With the regulating microfluidic chip, the pressure stability was 2 mbar, i.e., on pair with high-quality high-pressure syringe pumps. The required gas volume, and hence the total size, is scalable with the desired liquid volume, which makes it suitable for miniaturized systems. [Display omitted] • Battery-powered pump system only requiring 0.3 W. • On-chip pressure regulator compensates for decreasing gas pressure. • Piston separates gas and liquid avoiding any chemical interaction. • Gas does not get consumed and can be reused multiple times. [ABSTRACT FROM AUTHOR]

The expediency of replacement of throttling devices used for low-pressure gas (fuel, starting, etc.) treatment to meet self-needs of plants treating gas for transportation with expansion units was examined as a part of the PJSC Gazprom's energy saving policy of improving energy efficiency of subsidiary companies and organization based on application of innovative technologies and energy-generating equipment. The proposed fuel gas treatment technique will able production of additional amount of eco-friendly "green" energy and reduce thereby the operating cost and enhance energy efficiency of the whole plant. The paper presents a comparative analysis of isenthalpic and isentropic gas expansion by various devices. The proposed gas expansion models were constructed using specialized HYSYS (Aspen Tech) software package for modeling chemical engineering system and allow quantitative estimation of the energy of gas pressure drop. [ABSTRACT FROM AUTHOR]

A pressure regulator in a system of the base shroud failed during service. The pressure regulator is intended to regulate the inlet pressure of 275 to 50 kg/cm2 outlet pressure. The working medium is stated to be nitrogen gas. On disassembly of the system, a brown layer was observed on the seating surface of poppet of the main regulator. A brown layer was also observed on the spring pocket and on the spring end surface which was in contact with the poppet. Metallographic tests and hardness measurement were carried out on the components to reach to the cause of failure. The poppet of the pressure regulator failed to function in service due to rusting of its seating surface by crevice corrosion and partial closure of the holes. The crevices at contact surface between the poppet and the spring seems to have formed by settlement of a stagnant condensed moisture along the surface. Partial closure of the holes was due to the presence of condensed moisture as well as rust. Spring made of AISI 302 austenitic stainless steel did not corrode at all, while poppet made of AISI 420 martensitic stainless steel corroded heavily. [ABSTRACT FROM AUTHOR]

Cells from different organs in the body experience a range of mechanical and osmotic pressures that change in various diseases, including neurological, cardiovascular, ophthalmological, and renal diseases. Here, we demonstrate the use of an engineered Sensor-Actuator-Modulator (SAM) of microbial origin derived from a mechanosensitive channel of large conductance (MscL) for sensing external mechanical stress and modulating activities of mammalian cells. SAM is reliably expressed in the mammalian cell membrane and acts as a tension-activated pressure release valve. Further, the activities of heterologously expressed SAM in mammalian cells could be modulated by osmotic pressure. A comparison of the mechanosensitive activities of SAM-variants from different microbial origins shows differential inward current and dye uptake in response to mechanical stress exerted by hypo-osmotic shock. The use of SAM channels as mechanical stress-activated modulators in mammalian cells could provide new therapeutic approaches for treating disorders related to mechanical or osmotic pressure., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Long-distance gas transfer requires high pressure, which has to be reduced before the gas is conveyed to the customers. This pressure reduction takes place at natural gas pressure reduction stations, where gas pressure is decreased by using gas flow energy for overcoming local resistance, represented by a throttling valve. This pressure energy can be reused, but it is difficult to implement it at small pressure reduction stations, as the values of unsteadiness significantly increase when the gas approaches consumers, whereas gas flow rate and pressure decrease. This work suggests replacing throttling valves at small pressure reduction stations for expander-generator units, based on volumetric expanders. Two implementations are proposed. A mathematical model of gas-dynamic processes, which take place in expander-generator units, was developed using math equations. With its help, a comparison was made of the stability of the operation of two possible control schemes in non-stationary conditions, and the feasibility of using an expander-generator regulator as a primary one for a small natural gas pressure reduction station was confirmed.

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Oxygen production centers produce oxygen in high pressure that needs to be defused. A regulator is designed and analyzed in the current paper for medical use in oxygen production centers. This study aims to design a new oxygen pressure regulator and perform an analysis using Finite Element Modeling in order to evaluate its working principle. In the design procedure,the main elements and the operating principles of a pressure regulator are taking into account. The regulator is designed and simulations take place in order to assessthe proposed design. Stress analysis results are presented for the main body of the regulator, as well as, flow analysis to determine some important flow characteristics in the inlet and outlet of the regulator.

The primary objective of the present study was to identify the problems experienced by agricultural enterprises in Çumra town of Konya province in utilization of PTO shaft-driven field sprayers. Data were gathered through face-to-face questionnaires applied to 119 agricultural enterprises selected by stratified randomized sampling procedure from the town. Present findings revealed that 50.4% of sprayers had a tank capacity of 600 L, 89.9% of tanks were made of plastic material and 26.9% of the sprayers had an operational width of 10 m. Cracks or fractures were reported on boom by 31.9% and on both boom and chassis by 46.2%. About 24.4% indicated that they replaced the nozzles in case of a plug, 52.1% indicated regulator problems on rod, 26% indicated pump problems on pump lid and 91.6% indicated that they replaced at least one part. It was concluded based on present findings that farmers should be trained about utilization of sprayers to change their routines on sprayers. They should perform sprayer maintenance and repairs in accordance with user manual. [ABSTRACT FROM AUTHOR]

• The pressure wave propagation in pressurized thin-walled tubes were investigated. • Numerical models include modeling approach of fluid-structure interaction (FSI). • ALE models validated by experiments were used to examine impact wave propagation. • The results show a complex pressure wave propagation occurs in pressurized tubes. • The finding promotes the ALE should be used for a realistic modeling of the air. The pressurized thin-walled tubes are called as a member of adaptive energy absorbers of which energy absorbing performance can be controlled by variation of internal pressure. In this context, this study numerically investigates the axial impact performance of pressurized thin-walled circular tubes. For the realistic modeling of the compressed air, the ALE model was developed in LS-DYNA, which enabled an opportunity to investigate both pressure wave propagation in pressurized air and fluid-structure interaction effects between tube-wall and air. In addition, the models were run by taking into account both states, whether pressure regulator, which is an adjustable valve to control internal pressure value, was active. To validate the numerical models, the axial impact tests on Aluminum Aerosol cans were carried out using a light gas gun set-up. The results showed that at the onset of impact, a radial pressure wave, as well as an axial pressure one, simultaneously emerged. Whereas a radial pressure wave propagated towards the center from the tube-wall, the other one propagated along the centerline of the tube. Therefore, a complex pressure distribution and wave propagation occurred in the pressurized tubes. The pressure distribution obtained in the model with a pressure regulator revealed different behavior from the corresponding one obtained without pressure regulator. Also, the results showed that there is no distinct interaction between strain energy absorbed by tube-wall and pressure wave propagation although the total absorbed energy of pressurized tubes increases to some extent with the effects of wave propagation in the pressurized medium. [ABSTRACT FROM AUTHOR]

A mathematical model for reducing the pressure of natural gas in a direct acting pressure regulator is developed. It is shown that, if an outlet-inlet pressure ratio typical for practice is lower than a critical value, the pressure reduction process comes down to two stages: partial expansion of gas with throttling in the orifice plate of the pressure regulator and subsequent expansion in its body. The values of the gas temperature in the characteristic sections of the pressure regulator are determined. It is established that the temperature drops at the first stage of pressure reduction and rises as the flow in the pressure regulator body expands and decelerates. A method for minimizing the possibility of formation of gas hydrates in the pressure regulator is proposed. [ABSTRACT FROM AUTHOR]

Abstract Fuel cell vehicles offer significant sustainability benefits by eliminating tailpipe emissions, increasing powertrain efficiency, and utilizing hydrogen that can be supplied from various sources including renewables. A pressure regulator in the hydrogen storage system on a fuel cell vehicle is an important component to ensure that the hydrogen delivery to the fuel cell stack meets the pressure and temperature requirements. A validated model of the regulator can be used to support the product design and optimization of the operating strategy. In this work, a pressure regulator model has been developed to capture the hydrogen discharge behaviors from the compressed hydrogen tank to the fuel cell stack. The focus of the model is to develop the pressure and temperature relationship at the regulator outlet given the inlet conditions from the storage tank. Besides the ideal-gas based derivation for pressure response, the model has used a constant-enthalpy approach to capture the hydrogen temperature increase associated with the pressure drop due to the Joule–Thomson effect. The model was validated with various testing data including hysteresis and dynamic flow conditions, showing satisfactory agreement. The validated model was then used for parametric studies. The modeling results concluded that the regulator inlet temperature has the strongest influence on raising the outlet temperature, while the regulator inlet pressure is an important factor although secondary to the inlet temperature. The comprehensive regulator modeling developed in this work provides the foundation for assessing and optimizing a key dynamic component in the hydrogen storage system. Highlights • A pressure regulator model has been developed to capture the hydrogen discharge behaviors. • The hydrogen temperature increase due to Joule–Thomson effect has been captured. • The model was validated with various hysteresis and dynamic flow conditions. • The regulator inlet temperature has a significant influence on the outlet temperature. [ABSTRACT FROM AUTHOR]

Orbitofrontal foreign-body injuries comprise a major cause of all facial injuries referred to a neurosurgeon. The authors hereby present an unusual case of a pressure regulator of a domestic pressure cooker impacted into the orbit and extending through the orbital roof into the basifrontal cortex. The globe was intact externally with no obvious sign of such a large object impacted behind the globe. On imaging, the foreign body was found to have fractured the orbital roof with one end protruding into the basifrontal cortex. A transcranial approach was taken to remove the object with removal of the orbital rim and roof to reach the object. After successful retrieval of the metallic body, all displaced bone fragments were removed and the dural closure was done in a watertight manner. The vision could not be salvaged, most likely due to damage to the optic nerve. However, the globe was left intact and the ocular movements were normal. An important factor to consider in removal of such foreign bodies is that the bone fragments that get impacted should be meticulously removed and the dural tears should be sealed to prevent any intracranial infections and cerebrospinal fluid leaks. Removal of the orbital rim helps in adequate exposure of the retro-orbital space and the basifrontal dura. [ABSTRACT FROM AUTHOR]

During the natural gas pipeline transportation process, gas stream pressure is reduced at natural gas regulation stations (GRS). Natural gas pressure reduction is accompanied by energy dissipation which results in irreversible exergy losses in the gas stream. Energy loss depends on the thermodynamic parameters of the natural gas stream on inlet and outlet gas pressure regulation and metering stations. Recovered energy can be used for electricity generation when the pressure regulator is replaced with an expander to drive electric energy generation. To ensure the correct operation of the system, the natural gas stream should be heated, on inlet to expander. This temperature should be higher than the gas stream during choking in the pressure regulator. The purpose of this research was to investigate GRS operational parameters which influence the efficiency of the gas expansion process and to determine selection criteria for a cost-effective application of turboexpanders at selected GRS, instead of pressure regulators. The main novelty presented in this paper shows investigation on discounted payback period (DPP) equation which depends on the annual average natural gas flow rate through the analyzed GRS, average annual level of gas expansion, average annual natural gas purchase price, average annual produced electrical energy sale price and CAPEX.