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1
Perdigones, Francisco, Antonio Luque, and José M. Quero. "Novel Structure for a Pneumatically Controlled Flow Regulator With Positive Gain." Journal of Microelectromechanical Systems 19, no. 5 (October 2010): 1070–78. http://dx.doi.org/10.1109/jmems.2010.2067430.
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Satoh, Daisuke, Shuji Tanaka, and Masayoshi Esashi. "Electrostatically Controlled, Pneumatically Actuated Microvalve with Low Pressure Loss." IEEJ Transactions on Electrical and Electronic Engineering 3, no. 3 (2008): 305–12. http://dx.doi.org/10.1002/tee.20271.
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Trumper, D. L., and J. H. Lang. "An Electronically Controlled Pressure Regulator." Journal of Dynamic Systems, Measurement, and Control 111, no. 1 (March 1, 1989): 75–82. http://dx.doi.org/10.1115/1.3153021.
Повний текст джерелаАнотація:
This paper describes the analysis, design, implementation, and evaluation of an electronically controlled fluid back-pressure regulator system. The control scheme is unique in that it is purely electronic, and employs a nested pair of feedback loops. This approach overcomes several problems associated with purely mechanical regulation, such as friction in the control valve. Further, since the control is electronic, compensation functions are easily implemented via operational amplifier circuits. The pressure control system is derived with classical control techniques through linearization of the measured valve characteristics. The solutions to nonlinear problems encountered in the implementation are discussed. The design achieves good performance and stability over the entire pressure and flow operating regime.
4
Robert, R., P. Micheau, O. Avoine, B. Beaudry, A. Beaulieu, and H. Walti. "A Regulator for Pressure-Controlled Total-Liquid Ventilation." IEEE Transactions on Biomedical Engineering 57, no. 9 (September 2010): 2267–76. http://dx.doi.org/10.1109/tbme.2009.2031096.
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Barth,, Eric J., Jianlong Zhang, and, and Michael Goldfarb. "Control Design for Relative Stability in a PWM-Controlled Pneumatic System." Journal of Dynamic Systems, Measurement, and Control 125, no. 3 (September 1, 2003): 504–8. http://dx.doi.org/10.1115/1.1591810.
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This paper presents a control design methodology that provides a prescribed degree of stability robustness for plants characterized by discontinuous (i.e., switching) dynamics. The proposed control methodology transforms a discontinuous switching model into a linear continuous equivalent model, so that loop-shaping methods may be utilized to provide a prescribed degree of stability robustness. The approach is specifically targeted at pneumatically actuated servo systems that are controlled by solenoid valves and do not incorporate pressure sensors. Experimental demonstration of the approach validates model equivalence and demonstrates good tracking performance.
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Aishan, Yusufu, Yaxiaer Yalikun, and Yo Tanaka. "Pneumatically Actuated Thin Glass Microlens for On-Chip Multi-Magnification Observations." Actuators 9, no. 3 (August 23, 2020): 73. http://dx.doi.org/10.3390/act9030073.
Повний текст джерелаАнотація:
This paper presents a self-contained micro-optical system that is magnification-controlled by adjusting the positions of the microlens in the device via pneumatic air pressure. Unlike conventional dynamic microlenses made from a liquid or polydimethylsiloxane (PDMS) that change their shapes via external actuation, this system combines a fixed-curvature glass microlens, an inflatable PDMS layer, and the external pneumatic air pressure supply as an actuator. This device showed several advantages, including stable inflation, firm structure, and light weight; it achieved a larger displacement using the glass microlens structure than has been reported before. This fixed-curvature microlens was made from 120 µm-thick flat thin glass slides, and the system magnification was manipulated by the deflection of a 100 µm-thick PDMS layer to alter the distance from the microlens to the microfluidic channel. The system magnification power was proportional to the air pressure applied to the device, and with a 2.5 mbar air pressure supply, a 2.2X magnification was achieved. This optical system is ideal for combining with high resolving power microscopy for various short working distance observation tasks, and it is especially beneficial for various chip-based analyses.
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Hassan, Waseem, Hwangil Kim, Aishwari Talhan, and Seokhee Jeon. "A Pneumatically-Actuated Mouse for Delivering Multimodal Haptic Feedback." Applied Sciences 10, no. 16 (August 13, 2020): 5611. http://dx.doi.org/10.3390/app10165611.
Повний текст джерелаАнотація:
Most of the information a user obtains through a computer is visual and/or auditory. Providing synchronized haptic information in addition to visual and/or auditory information can significantly enhance user experience and perception of virtual objects. In this paper, we propose a pneumatically-controlled haptic mouse that can replace a conventional computer mouse and deliver multimodal haptic feedback using a single end-effector. The haptic mouse can deliver distinct haptic feedback, i.e., static pressure, high frequency vibrations, and impact response. It has a dual-layered silicone housing with two air chambers. The outer layer is stretchable, and when pumped with air, changes in size and delivers feedback directly to the hand. The inner layer is non-stretchable, and is used to hold the form of the haptic mouse. Various experiments were conducted to quantify the characteristics of haptic mouse. The haptic mouse can generate a static pressure of up to 0.6 Gs, vibrations up to 250 Hz, and provides a max actuation delay of 23 ms. Based on those characteristics, haptic geometry and texture rendering algorithms were developed. These algorithms were used to render virtual shapes and textures and were evaluated using a psychophysical experiment. The results show that participants were able to successfully identify the geometries and textures in most cases.
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Hashem, Mohammad Shadman, Joolekha Bibi Joolee, Waseem Hassan, and Seokhee Jeon. "Soft Pneumatic Fingertip Actuator Incorporating a Dual Air Chamber to Generate Multi-Mode Simultaneous Tactile Feedback." Applied Sciences 12, no. 1 (December 24, 2021): 175. http://dx.doi.org/10.3390/app12010175.
Повний текст джерелаАнотація:
A complete set of diverse haptic feedbacks is essential for a highly realistic and immersive virtual environment. In this sense, a multi-mode haptic interface that simultaneously generates multiple kinds of haptic signals is highly desirable. In this paper, we propose a new silicone-made pneumatically controlled fingertip actuator to render pressure and vibrotactile feedback concurrently to offer a realistic and effective haptic sensation. A new silicone-based stacked dual-layer air chamber was designed. The volume of the chambers is controlled by pneumatic valves with compressed air tanks. The top/upper air chamber renders vibration feedback, whereas the bottom/lower air chamber renders pressure feedback. The proposed silicone-made fingertip actuator is designed so that it can be easily worn at the fingertips. To demonstrate the potential of the system, a virtual environment for rendering three different types of haptic textures was implemented. Extensive performance evaluation and user studies were carried out to demonstrate the proposed actuator’s effectiveness compared to an actuator with single vibrotactile feedback.
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Xu, De Fu, Ping Dong, Jun Fan, and Shu Jun Guo. "The Dynamics Calculations and Research of Electronically Controlled Water Distribution Device." Key Engineering Materials 522 (August 2012): 342–46. http://dx.doi.org/10.4028/www.scientific.net/kem.522.342.
Повний текст джерелаАнотація:
There are four fluid flows in the water regulator of injection wells the first the second the third and the forth backwash flow.The four fluid flows are used to injection and backwash petroleum wells.Based on the reliability of the water regulator under the high-pressured high speed fluid's function.By using fluent software for the numerical analysis and fluid dynamics,get the velocity and pressure field contours and the cloud chart,under the high pressure and high velocity effect. Meanwhile analysis the results.It is provide a theoretical basis for the optimization of the structure of water distribution device.
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Dindorf, Ryszard, and Piotr Wos. "Analysis of the Possibilities of Using a Driver’s Brain Activity to Pneumatically Actuate a Secondary Foot Brake Pedal." Actuators 9, no. 3 (July 1, 2020): 49. http://dx.doi.org/10.3390/act9030049.
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The study deals with the use of the driver’s brain activity for wireless remote control of the pneumatic actuator exerting pressure on the secondary foot brake pedal. The conducted experimental tests confirm that bioelectrical signals (BES) induced by muscle tension within the head can be used for wireless remote control of a pneumatic actuator to exert a pressure force on a foot brake pedal for disabled drivers during car emergency braking. It has been shown that the BES artefacts generated by muscular tension inside the head (e.g., movement of the face and eyelids, clenching of jaws, and pressing the tongue on the palate) are the easiest to control of the pneumatic systems. The proposed car braking assistance system controlled by the driver’s brain activity can improve the driving safety of disabled people, e.g., by reducing the reaction time of pneumatically assisted emergency braking.
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Busek, Mathias, Stefan Grünzner, Tobias Steege, Udo Klotzbach, and Frank Sonntag. "Hypoxia-on-a-chip." Current Directions in Biomedical Engineering 2, no. 1 (September 1, 2016): 71–75. http://dx.doi.org/10.1515/cdbme-2016-0019.
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AbstractIn this work a microfluidic cell cultivation device for perfused hypoxia assays as well as a suitable controlling unit are presented. The device features active components like pumps for fluid actuation and valves for fluid direction as well as an oxygenator element to ensure a sufficient oxygen transfer. It consists of several individually structured layers which can be tailored specifically to the intended purpose. Because of its clearness, its mechanical strength and chemical resistance as well as its well-known biocompatibility polycarbonate was chosen to form the fluidic layers by thermal diffusion bonding. Several oxygen sensing spots are integrated into the device and monitored with fluorescence lifetime detection. Furthermore an oxygen regulator module is implemented into the controlling unit which is able to mix different process gases to achieve a controlled oxygenation. First experiments show that oxygenation/deoxygenation of the system is completed within several minutes when pure nitrogen or air is applied to the oxygenator. Lastly the oxygen input by the pneumatically driven micro pump was quantified by measuring the oxygen content before and after the oxygenator.
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Wang, Xiaolin, Duc T. T. Phan, Da Zhao, Steven C. George, Christopher C. W. Hughes, and Abraham P. Lee. "An on-chip microfluidic pressure regulator that facilitates reproducible loading of cells and hydrogels into microphysiological system platforms." Lab on a Chip 16, no. 5 (2016): 868–76. http://dx.doi.org/10.1039/c5lc01563d.
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Lin, S. J., and A. Akers. "Optimal Control Theory Applied to Pressure-Controlled Axial Piston Pump Design." Journal of Dynamic Systems, Measurement, and Control 112, no. 3 (September 1, 1990): 475–81. http://dx.doi.org/10.1115/1.2896167.
Повний текст джерелаАнотація:
This work presents a study of the applicability of optimal control theory to the design of a pressure regulator by use of an axial piston pump with a two-stage electrohydraulic servovalve. The control valve has been modeled and an optimal control law has been formulated. The time response curves due to a step input in flow rate to the pump have been obtained for the open loop and the for the optimal control system. An examination of the results has shown that the performance, in terms of pressure peaks and frequency during recovery to the flow disturbance, is significantly improved over that obtained when a single-stage valve is used.
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Petre, Ioana Mădălina, Tudor Deaconescu, and Andrea Deaconescu. "Concerning on a Lower Limb Joint Affections Rehabilitation Equipment Command." Applied Mechanics and Materials 772 (July 2015): 580–84. http://dx.doi.org/10.4028/www.scientific.net/amm.772.580.
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The aim of the article is to analyze the command of a rehabilitation equipment. The presented rehabilitation equipment allows lower limb joints movements, in order to recover their functionality. The rehabilitation movements are known as continuous passive motion, term used in kinetotherapy.The command used is composed by of a pneumatic muscle supplied with air from a pressure proportional regulator and controlled by a reference module. The reference module, by means of rotary potentiometers, can generate up to six different values of reference voltage which are transmitted as signals to the proportional controller. If no appeal to any of these benchmarks, the transmitted signal to the pressure regulator is a voltage that can be modified by an external potentiometer. The results of experiments shows that proportional pressure regulator allows easy modification of the pressure slope, with better results on rehabilitation movements.
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Day, M. J., R. J. Randall, C. P. Ratcliffe, and E. Rider. "Reducing the Vibrations Caused by a Marine Diesel Generator Set." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 207, no. 6 (November 1993): 375–81. http://dx.doi.org/10.1243/pime_proc_1993_207_144_02.
Повний текст джерелаАнотація:
This paper details work undertaken to investigate the use of pneumatically controlled vibration absorbers to reduce the vibrations caused by a G&M/Perkins six-cylinder diesel generator (DG) set. The DG set had a mass of approximately 1 tonne and reductions in vibration levels near the engine mounts of about 10 dB were achieved using four absorbers with a total active mass of 18 kg. The absorbers incorporated air springs which have the advantage of a variable stiffness depending on the contained air pressure within the springs. The ability to continuously tune to a target frequency was offset by the non-linear stiffness of the air springs, which makes control of the absorbers more complicated. For the work reported in this paper, the absorbers were manually tuned to the desired operating frequencies. Sensitivity trials for absorbers detuned from the optimum frequency are also reported.
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Batsios, N., M. Annapragada, and Sunil Kumar Agrawal. "Quadri-directional Air Thrusters for Free-floating Robot Applications." Journal of Mechanical Design 117, no. 4 (December 1, 1995): 651–53. http://dx.doi.org/10.1115/1.2826736.
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This paper describes the operational theory and design of a quadri-directional air thruster ( “quad” ) for propulsion of the free-floating robot of Ohio University. In this design, the air is drawn from a central air tank and routed to four nozzles of a quad thruster via a pressure regulator, a distribution manifold, four solenoid valves, and a quad manifold. The pressure regulator is controlled by a d.c. servomotor and the solenoid valves are turned on/off using the digital output ports of the computer. The performance characteristics of this quad thruster were determined experimentally. The experimental measurement of the thrust as a function of the regulated pressure shows a good match with the data predicted by the supporting theory.
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Cammarota, Gianmaria, Federico Longhini, Raffaella Perucca, Chiara Ronco, Davide Colombo, Antonio Messina, Rosanna Vaschetto, and Paolo Navalesi. "New Setting of Neurally Adjusted Ventilatory Assist during Noninvasive Ventilation through a Helmet." Anesthesiology 125, no. 6 (December 1, 2016): 1181–89. http://dx.doi.org/10.1097/aln.0000000000001354.
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Abstract Background Compared to pneumatically controlled pressure support (PSP), neurally adjusted ventilatory assist (NAVA) was proved to improve patient–ventilator interactions, while not affecting comfort, diaphragm electrical activity (EAdi), and arterial blood gases (ABGs). This study compares neurally controlled pressure support (PSN) with PSP and NAVA, delivered through two different helmets, in hypoxemic patients receiving noninvasive ventilation for prevention of extubation failure. Methods Fifteen patients underwent three (PSP, NAVA, and PSN) 30-min trials in random order with both helmets. Positive end-expiratory pressure was always set at 10 cm H2O. In PSP, the inspiratory support was set at 10 cm H2O above positive end-expiratory pressure. NAVA was adjusted to match peak EAdi (EAdipeak) during PSP. In PSN, the NAVA level was set at maximum matching the pressure delivered during PSP by limiting the upper pressure. The authors assessed patient comfort, EAdipeak, rates of pressurization (i.e., airway pressure-time product [PTP] of the first 300 and 500 ms after the initiation of patient effort, indexed to the ideal pressure–time products), and measured ABGs. Results PSN significantly increased comfort to (median [25 to 75% interquartile range]) 8 [7 to 8] and 9 [8 to 9] with standard and new helmets, respectively, as opposed to both PSP (5 [5 to 6] and 7 [6 to 7]) and NAVA (6 [5 to 7] and 7 [6 to 8]; P < 0.01 for all comparisons). Regardless of the interface, PSN also decreased EAdipeak (P < 0.01), while increasing PTP of the first 300 ms from the onset of patient effort, indexed to the ideal PTP (P < 0.01) and PTP of the first 500 ms from the onset of patient effort, indexed to the ideal PTP (P < 0.001). ABGs were not different among trials. Conclusions When delivering noninvasive ventilation by helmet, compared to PSP and NAVA, PSN improves comfort and patient–ventilator interactions, while not ABGs. (Anesthesiology 2016; 125:1181-9)
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Naik, Kuldip, Mehran Mehrandezh, and John Barden. "Design, Development and Control of a Hopping Machine – an Exercise in Biomechatronics." Applied Bionics and Biomechanics 7, no. 1 (2010): 83–94. http://dx.doi.org/10.1155/2010/746921.
Повний текст джерелаАнотація:
Hopping is a complicated dynamic behaviour in the animal kingdom. Development of a hopping machine that can mimic the biomechanics of jumping in Homo sapiens is envisioned. In this context, the design, development and control of a cost-effective, pneumatically actuated, one-legged hopping machine were initiated at the University ofRegina in 2005. The pneumatic actuator has a simple design that employs an off-the-shelf on/off control valve which regulates the air pressure supplied to the hopper's body using a pulse width modulated (PWM) signal. The objective is to maintain a constant jumping height in the hopper after going through a finite number of hopping cycles. The mechanistic model of the system was investigated in full detail. This model facilitates: (1) the design of the actuating system, and (2) the synthesis and verification of different control strategies in a simulation environment prior to implementation in the real world. The movement of the hopper is supported by a vertical slide; therefore, the hopper can only jump in place. However, the proposed control strategy and the propulsion unit can be further utilised for stable hopping in a 3-D environment. A model-free Neuro-PD controller was then designed, trained and implemented on a real system. Simulation and experimentation showed promising results. This system can be used as an educational tool for teaching real-time control of hybrid and non-linear systems. It can be also used as a biomechatronics test bed to simulate the effect of different timings in firing action potentials in jump-causing leg muscles on achieving a desired jumping height in the animal kingdom.
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Janerka, Krzysztof, Jan Jezierski, Marcin Stawarz, and Jan Szajnar. "Method for Resistivity Measurement of Grainy Carbon and Graphite Materials." Materials 12, no. 4 (February 21, 2019): 648. http://dx.doi.org/10.3390/ma12040648.
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The article presents the issue of electrical resistivity measurement of carbon materials. The device that was developed by the authors is described and is the subject of a Polish patent. The innovative approach of the setup is based on the possibility of measuring the resistivity of grainy (powdered, dusty) materials without having to conduct their preliminary pressing. The material that is to be analyzed is placed inside the chamber made of electrically non-conducting material. The sample is then compacted with pneumatically driven pistons and the compaction force can be controlled by the air pressure. The device as proposed by the authors works at a pressure of 900 kPa, which is equal to the compaction force of 1.2 kN. Resistivity is calculated on the basis of the voltage drop recorded on the sample length. The research covers the analysis of the influence of carbon material grade and compaction force on the resistivity value. It was stated that the resistivity of the graphite materials that were analyzed here changed within the range of 43–172 µm: petroleum coke—360–780 µm; the anthracite—1900–3900 µm. The experimental method presented here can be used whenever carbon materials are present in the form of grains.
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Chen, K., and G. A. Karim. "Evaluation of the instantaneous unsteady heat transfer in a rapid compression-expansion machine." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 212, no. 5 (August 1, 1998): 351–62. http://dx.doi.org/10.1243/0957650981536925.
Повний текст джерелаАнотація:
Investigation is made of the instantaneous unsteady heat transfer within a pneumatically driven rapid compression-expansion machine that offers simple, well-controlled and known boundary conditions. Values of the instantaneous apparent overall heat flux from the cylinder gas to the wall surfaces were calculated using a thermodynamic analysis of the experimentally measured pressure and volume temporal development. Corresponding heat flux values were also estimated through the application of a three-dimensional computational fluid dynamics code, KIVA3. Correlation of the derived data using the mean piston speed and cylinder bore diameter as the characteristic parameters for the Reynolds and the Nusselt numbers resulted in Nu = 0.010 × Re1.188 for all compression ratios (8.4–24.3). Correlation of the derived data when using the instantaneous height between the piston top and the cylinder head, the maximum gas velocity and the kinetic mean gas velocity obtained when using the KIVA3 code as the characteristic parameters for the Reynolds and the Nusselt numbers was found to produce values of the Nusselt number that were almost independent of the corresponding calculated values of the Reynolds number during the major part of the compression and expansion strokes. A power relationship between the cylinder pressure and gas temperature and the apparent heat transfer coefficient was demonstrated.
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Liu, Shaohu, and Zhichao Zhu. "Application of Composite Deflecting Model in Horizontal Well Drilling." Mathematical Problems in Engineering 2020 (March 9, 2020): 1–10. http://dx.doi.org/10.1155/2020/4672738.
Повний текст джерелаАнотація:
Based on current issues of difficulties in controlling horizontal well trajectory and high cost in drilling deflecting, a compound deflecting BHA (bottom hole assembly) with diameter-adjustable stabilizer (DAS) and bending-adjustable housing (BAH) is presented. According to the DAS operational principles and the stress condition in operation, the computational formula of wedge’s axial moving displacement and piston’s radial telescopic displacement of the DAS driven by drilling fluid pressure is presented. This formula is verified by lab experimental simulation. Three-points-circle method is utilized to calculate geometrical build up rate of compound deflecting BHA, and the result is verified by field data. The method is utilized to make design and calculate for compound BHA. The research can be used as a reference for compound deflecting drilling in horizontal wells. The flow rate and pressure difference have a very serious impact on the flow regulator erosion, so the flow rate and pressure difference should be controlled when the DAS works, and it is suggested that the flow regulator should maintain and replace frequently when in service.
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Sârbu, F., A. Deaconescu, and T. Deaconescu. "Adjustable compliance soft gripper system." International Journal of Advanced Robotic Systems 16, no. 4 (July 2019): 172988141986658. http://dx.doi.org/10.1177/1729881419866580.
Повний текст джерелаАнотація:
This article proposes a novel, innovative, soft gripper system developed for the manipulation of objects of unknown or unspecified shape and consistence. This could be achieved by the utilization of a linear pneumatic muscle benefitting from an inherently compliant behaviour. A gripper system of this type does not require the presence of sensors or complex controllers, as it is the mechanical system itself that provides the required adaptive behaviour. The compliance of the system is ensured by the variations of the air pressure fed to the pneumatic muscle, monitored and controlled in a closed loop by means of proportional pressure regulator.
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Nouaille, Sébastien, Lucie Rault, Sophie Jeanson, Pascal Loubière, Yves Le Loir, and Sergine Even. "Contribution of Lactococcus lactis Reducing Properties to the Downregulation of a Major Virulence Regulator in Staphylococcus aureus, theagrSystem." Applied and Environmental Microbiology 80, no. 22 (September 5, 2014): 7028–35. http://dx.doi.org/10.1128/aem.02287-14.
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ABSTRACTStaphylococcus aureusis a major cause of food poisoning outbreaks associated with dairy products, because of the ingestion of preformed enterotoxins. The biocontrol ofS. aureususing lactic acid bacteria (LAB) offers a promising opportunity to fight this pathogen while respecting the product ecosystem. We had previously established the ability ofLactococcus lactis, a lactic acid bacterium widely used in the dairy industry, to downregulate a major staphylococcal virulence regulator, the accessory gene regulator (agr) system, and, as a consequence,agr-controlled enterotoxins. In the present paper, we have shown that the oxygen-independent reducing properties ofL. lactiscontribute toagrdownregulation. Neutralizing lactococcal reduction by adding potassium ferricyanide or maintaining the oxygen pressure constant at 50% releasedagrdownregulation in the presence ofL. lactis. This downregulation still occurred in anS. aureus srrAmutant, indicating that the staphylococcal respiratory response regulator SrrAB was not the only component in the signaling pathway. Therefore, this study clearly demonstrates the ability ofL. lactisreducing properties to interfere with the expression ofS. aureusvirulence, thus highlighting this general property of LAB as a lever to control the virulence expression of this major pathogen in a food context and beyond.
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Paszota, Zygmunt. "Graphical presentation of the power of energy losses and power developed in the elements of hydrostatic drive and control system: Part I Rotational hydraulic motor speed series throttling control systems." Polish Maritime Research 15, no. 3 (October 1, 2008): 28–37. http://dx.doi.org/10.2478/v10012-007-0080-3.
Повний текст джерелаАнотація:
Graphical presentation of the power of energy losses and power developed in the elements of hydrostatic drive and control system: Part I Rotational hydraulic motor speed series throttling control systems Paper proposes and justifies a diagram of the direction of increase of power stream from the shaft or piston rod of a hydraulic motor to the pump shaft, power increasing as an effect of the imposed power of energy losses in the hydrostatic drive and control system elements. Graphical interpretation of the power of energy losses in the hydrostatic drive and control system elements and also of the power developed by those elements is presented. An individual system with the rotational hydraulic motor speed series throttling control fed by a constant capacity pump cooperating with an overflow valve in a constant pressure system p = cte ≈ pn is analyzed and also an individual system with the rotational hydraulic motor speed series throttling control fed by a constant capacity pump cooperating with an overflow valve controlled in a variable pressure system: p = var, an individual system with the rotational hydraulic motor speed series throttling control fed by a variable capacity pump cooperating with a pressure regulator in a constant pressure system p = cte ≈ pn and an individual system with the rotational hydraulic motor speed series throttling control fed by a variable capacity pump cooperating with the Load Sensing regulator in a variable pressure p = var system.
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Akers, A., and S. J. Lin. "Optimal Control Theory Applied to a Pump With Single-Stage Electrohydraulic Servovalve." Journal of Dynamic Systems, Measurement, and Control 110, no. 2 (June 1, 1988): 120–25. http://dx.doi.org/10.1115/1.3152661.
Повний текст джерелаАнотація:
Optimal control theory is applied to the design of a pressure regulator for an axial piston pump and single-stage electrohydraulic valve combination. The control valve has been modeled and an optimal control law has been formulated. The time response curves due to a step input inflow rate and in current input to the servovalve have been obtained for the open loop and for the optimal control system. Comparison of the results has been made with previous work in which the supply valve to the swashplate actuators was not modeled. It is shown that controlled system modeling of the servovalve significantly improves system performance in terms of response frequency and pressure peaks.
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Danieli, Guido A. "Analytical Description of Meshing of Constant Pressure Angle Teeth Profiles on a Variable Radius Gear and its Applications." Journal of Mechanical Design 122, no. 1 (January 1, 2000): 123–29. http://dx.doi.org/10.1115/1.533551.
Повний текст джерелаАнотація:
This paper presents a method for determining the profile of the gear teeth on a variable radius wheel characterized by a constant pressure angle. The method can generate special gears using numerically controlled milling machines. As will be shown, the method, applied to a constant radius gear, generates an involute profile. The method is based on the integration of a differential equation describing the mesh between gears of variable radius, where the mesh point position is computed during rotation starting from the point, freely selected, where the tooth crosses the pitch line. The individual point is subsequently rotated in the opposite direction by an angle equal to the angle of rotation from the initial pitch line point, thereby generating the tooth profile. The method, applied to a wheel of variable radius, defined analytically or numerically, can compute teeth profiles on pairs of pitch lines of any shape. In particular, the motion of a slotted rotating link mechanism has been reproduced, but for the sign. Teeth profiles of other variable radius wheels have also been obtained. The results are more than satisfactory and are presented below. A numerically controlled milling machine has been programmed to actually build the antirotating slotted link equivalent gear. The present method, however, has much broader application, such as assigning the speed law to consequentially determine the gear form, as can be done with cams. Furthermore, a special planetary gear train makes it also possible to obtain reciprocating motion driven solely by gears. This has been built and its picture and scheme are presented in the paper. However, due to the low efficiency of the said mechanism, the best way to utilize this new technology seems to be to couple a crank and a rod to the pair of variable radius gears, as has been done at Hanover University. Some possible applications are presented. The special feature of these gears is the programmability of the shape of the pitch lines during the design phase, and thus of the velocity and acceleration profiles. In this way velocity profiles that could formerly only be obtained electro-pneumatically can be produced from purely mechanical components, with the added advantage of being able to control the level of inertia forces during the design phase. [S1050-0472(00)01601-9]
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Maeda, MD, PhD, Hiroyuki, Hideaki Iwase, PhD, Akio Kanda, MD, PhD, Itaru Morohashi, MD, PhD, Kazuo Kaneko, MD, PhD, Mutsuhiro Maeda, Yuki Kakinuma, Yusuke Takei, Shota Amemiya, and Kazuyuki Mitsui, PhD. "A study of the blood flow restriction pressure of a tourniquet system to facilitate development of a system that can prevent musculoskeletal complications." American Journal of Disaster Medicine 12, no. 3 (July 1, 2017): 139–45. http://dx.doi.org/10.5055/ajdm.2017.0267.
Повний текст джерелаАнотація:
Background: After an emergency or disaster, subsequent trauma can cause severe bleeding and this can often prove fatal, so promptly stopping that bleeding is crucial to preventing avoidable trauma deaths. A tourniquet is often used to restrict blood flow to an extremity. In operation and hospital, the tourniquet systems currently in use are pneumatically actuated by an air compressor, so they must have a steady power supply. These devices have several drawbacks: they vibrate and are noisy since they are pneumatically actuated and they are far from portable since they are large and heavy.Introduction: Presumably, the drawbacks of pneumatic tourniquets could be overcome by developing a small, lightweight, vibration-free, quiet, and battery- powered tourniquet system. The current study built a small, vibration-free electrohydrodynamic (EHD) pump and then used that pump to restrict blood flow to the leg of rats in an experiment. This study explored the optimal conditions for effective restriction of blood flow by assessing biochemical and musculoskeletal complications following the restriction of blood flow, and this study also examined whether or not an EHD pump could be used to actuate a tourniquet system.Methods: A tourniquet cuff (width 12 mm × length 150 mm, material: polyolefin) was placed on the thigh of Wistar rats and pressure was applied for 2 hours by a device that uses EHD phenomena to generate pressure (an EHD pump). Animals were divided into four groups based on how much compressive pressure was applied with a tourniquet: 40 kPa (300 mm Hg, n = 13), 30 kPa (225 mm Hg, n = 12), 20 kPa (150 mm Hg, n = 15), or 0 kPa (controls, n = 25). Tissue oxygen saturation (regional oxygen saturation, denoted here as rSO2) was measured to assess the restriction of blood flow. To assess behavior once blood flow resumed, animal activity was monitored for third day and the amount of movement was counted with digital counters. Body weight was measured before and after the behavioral experiment, and changes in body weight were determined. Blood was sampled after a behavioral experiment and biochemically assessed and creatine kinase (CK) levels were measured.Results: Tissue oxygen saturation decreased significantly in each group. When a tourniquet was applied at a pressure of 30 kPa or more, tissue oxygen saturation decreased significantly. The amount of movement (the count) over third day decreased more when a tourniquet was applied at a higher pressure. The control group resumed the same amount of movement per day second after blood flow resumed. Animals to which a tourniquet was applied at a pressure of 20 or 30 kPa resumed the same amount of movement third day after blood flow resumed. In contrast, animals to which a tourniquet was applied at a pressure of 40 kPa did not resume the same amount of movement third day after blood flow resumed. After the behavioral experiment, animals to which a tourniquet was applied at a pressure of 40 kPa had a significantly lower body weight in comparison to the control group. After the behavioral experiment, animals to which a tourniquet was applied at a pressure of 40 kPa had significantly elevated CK levels in comparison to the control group.Discussion and Conclusion: A relationship between blood flow restriction pressure and tissue oxygen saturation was noted. rSO2 measurement can be used to assess the restriction of blood flow during surgery. On the basis of the decrease in rSO2, blood flow was effectively restricted at a pressure of 30 kPa or more. When, however, blood flow was restricted at a pressure of 40 kPa, weight loss and decreased movement were noted and CK levels increased after the behavioral experiment. Thus, complications had presumably developed due to damage to muscle tissue. These findings indicate that blood flow was effectively restricted in this experiment and they also indicate the existence of an optimal blood flow restriction pressure that does not cause musculoskeletal complications. The pressure in question was around 30 kPa. The tourniquet system that was developed here is actuated with an EHD pump that is still in the trial stages. That said, its pressure can readily be controlled and this pump could be used in a tourniquet system since it is quiet, vibration-free, and small. The pressure of this pump can be finely adjusted to prevent musculoskeletal complications.
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Nakazawa, T., M. Shiono, T. Inoue, Y. Orime, S. Shindo, and Y. Sezai. "Preliminary Experimental Study about the Feasibility of Combining Pulsatile Cardiopulmonary Support System and a Membrane Oxygenator." International Journal of Artificial Organs 19, no. 10 (October 1996): 597–604. http://dx.doi.org/10.1177/039139889601901007.
Повний текст джерелаАнотація:
A cardiopulmonary support (CPS) device that incorporated a pneumatic ventricular assist device (VAD) and a membrane oxygenator was developed for the support of patients with profound heart and/or respiratory failure. This device has an advantage of being both a pulsatile assist device and membrane oxygenator. A “triple flow” regulator was included in this system to control the blood flow through the oxygenator. The purpose of this study was to clarify the efficacy of this system in supporting an animal model with combined cardiac and respiratory failure. In vitro tests showed 3.7 L/min of pump flow under 1.6 L/min of oxygen supply to the oxygenator even though there was a 50% clamp of a “triple flow” regulator with sufficient pulsatility. In 14 acute canine experiments, cardiogenic shock and acute respiratory failure were introduced by coronary ligation and mechanical hypoventilation simultaneously. The pump flow was maintaned at 1.95 - 0.6 L/min (average 1.2 L/min) and the driving pressure of the pump was controlled between 200 and 300 mmHg positive pressure and -20 to -50 mmHg negative pressure. The driving rate was fixed at 100 bpm and systolic/diastolic ratio was controlled between 35-50%. The canines were divided into control group (n=4) and pumped group (drained from the right atrium n=7, drained from the left atrium n=3). By using CPS system, flow and aortic pressure recovered to the initial baseline level. Without this support, the canine model could not maintain systemic circulation. In the group drained from right atrium, central venous pressure decreased with the device from 13.9 ± 2.4 to 5.6 ± 1.4 cm H2O (p<0.01), returned to the initial level without this device (p<0.01). In the group drained from left atrium, pulmonary capillary wedge pressure decreased from 37.9 ± 4.6 to 20.8 ± 5.7 mmHg (p<0.01), and returned to the initial level without the device, arterial oxygen tension levels increased (p<0.01), and also arterial oxygen saturation levels recovered (p<0.01). The results suggest that the current model of the pulsatile CPS has a potential to support the animal model with combined cardiac and respiratory failure.
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Oh, Sung Hoon. "Development of Pneumatic Press Stroke Control through the Application of a Horizontal Cylinder." Applied Mechanics and Materials 433-435 (October 2013): 2117–20. http://dx.doi.org/10.4028/www.scientific.net/amm.433-435.2117.
Повний текст джерелаАнотація:
Developed the pneumatic press machine with a controllable precision stroke through this study. Conventional pneumatic presses cylinder installed in the vertical direction to deliver the power, but in contrast to conventional approaches, it is applied a horizontal cylinder by installing a pressure sloping portion, so that the cylinder power delivers to the vertical direction. This reduces the height of the press, transmitting the power of the cylinder controlling the straight length of the piston by moving regulator so the stroke of the press can be precisely controlled. In addition, in the press manufacturing by changing a driving cycle for the safety of workers and the working environment is improved.
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Klett, Christoph P. R., and Joey P. Granger. "Physiological elevation in plasma angiotensinogen increases blood pressure." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 281, no. 5 (November 1, 2001): R1437—R1441. http://dx.doi.org/10.1152/ajpregu.2001.281.5.r1437.
Повний текст джерелаАнотація:
Hepatic angiotensinogen secretion is controlled by a complex pattern of physiological or pathophysiological mediators. Because plasma concentrations of angiotensinogen are close to the Michaelis-Menten constant, it was hypothesized that changes in circulating angiotensinogen affect the formation rate of ANG I and ANG II and, therefore, blood pressure. To further test this hypothesis, we injected purified rat angiotensinogen intravenously in Sprague-Dawley rats via the femoral vein and measured mean arterial blood pressure after arterial catheterization. In controls, mean arterial pressure was 131 ± 2 mmHg before and after the injection of vehicle (sterile saline). The injection of 0.8, 1.2, and 2.9 mg/kg angiotensinogen caused a dose-dependent increase in mean arterial blood pressure of 8 ± 0.4, 19.3 ± 2.1, and 32 ± 2.4 mmHg, respectively. In contrast, the injection of a purified rabbit anti-rat angiotensinogen antibody (1.4 mg/kg) resulted in a significant decrease in mean arterial pressure (−33 ± 3.2 mmHg). Plasma angiotensinogen increased to 769 ± 32, 953 ± 42, and 1,289 ± 79 pmol/ml, respectively, after substrate and decreased by 361 ± 28 pmol/ml after antibody administration. Alterations in plasma angiotensinogen correlated well with changes in plasma renin activity. In summary, variations in circulating angiotensinogen can result in changes in blood pressure. In contrast to renin, which is known as a tonic regulator for the generation of ANG I, angiotensinogen may be a factor rather important for long-term control of the basal activity of the renin-angiotensin system.
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Valentine, BJ, GM Gurr, and WG Thwaite. "Efficacy of the insect growth regulators tebufenozide and fenoxycarb for lepidopteran pest control in apples, and their compatibility with biological control for integrated pest management." Australian Journal of Experimental Agriculture 36, no. 4 (1996): 501. http://dx.doi.org/10.1071/ea9960501.
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The insect growth regulators tebufenozide and fenoxycarb were compared with the industry standard organophosphate, azinphos-methyl, in a replicated field trial. In both the 1992-93 and 1993-94 seasons, the 2 insect growth regulators maintained damage levels to harvested and windfall apples below 1% for both codling moth (Cydia pornonella L.) and lightbrown apple moth (Epiphyas postvittana Walker). This was despite considerable pest pressure as indicated by pheromone trap catches of both species. In the first season of the trial, E. postvittana was controlled more effectively (P<0.05) by tebufenozide than by fenoxycarb. In both seasons, populations of two-spotted mite, Tetranychus urticae Koch, and European red mite, Panonychus ulmi Koch, were higher in plots under azinphos-methyl treatment than in either insect growth regulator treatment. Neither insect growth regulator appeared to suppress populations of the phytoseiids Typhlodromus pyri Scheuten and Typhlodromus occidentalis Nesbitt. Limb jarring in the second season showed statistically significant (P<0.05) differences in populations of other predators which may have contributed to the biological control of phytophagous mites in the insect growth regulator treatments. Numbers of spiders, Stethorus spp., and apple dimpling bug (Carnpylomma liebknechti Girault) nymphs were all lower in the azinphos-methyl treatment. Results are discussed in relation to reducing dependence on conventional pesticides by use of more target-specific compounds which may be more compatible with biological control.
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Chrastina, Adrian, Veronique T. Baron, Parisa Abedinpour, Gaelle Rondeau, John Welsh, and Per Borgström. "Plumbagin-Loaded Nanoemulsion Drug Delivery Formulation and Evaluation of Antiproliferative Effect on Prostate Cancer Cells." BioMed Research International 2018 (November 11, 2018): 1–7. http://dx.doi.org/10.1155/2018/9035452.
Повний текст джерелаАнотація:
Background. Plumbagin, a medicinal plant-derived 5-hydroxy-2-methyl-1,4-naphthoquinone, is an emerging drug with a variety of pharmacological effects, including potent anticancer activity. We have previously shown that plumbagin improves the efficacy of androgen deprivation therapy (ADT) in prostate cancer and it is now being evaluated in phase I clinical trial. However, the development of formulation of plumbagin as a compound with sparing solubility in water is challenging. Methods. We have formulated plumbagin-loaded nanoemulsion using pneumatically controlled high pressure homogenization of oleic acid dispersions with polyoxyethylene (20) sorbitan monooleate as surfactant. Nanoemulsion formulations were characterized for particle size distribution by dynamic light scattering (DLS). The kinetics of in vitro drug release was determined by equilibrium dialysis. Anticancer activity toward prostate cancer cells PTEN-P2 was assessed by MTS (Owen’s reagent) assay. Results. Particle size distribution of nanoemulsions is tunable and depends on the surfactant concentration. Nanoemulsion formulations of plumbagin with 1-3.5% (w/w) of surfactant showed robust stability of size distribution over time. Plumbagin-loaded nanoemulsion with average hydrodynamic diameter of 135 nm showed exponential release of plumbagin with a half-life of 6.1 h in simulated gastric fluid, 7.0 h in simulated intestinal fluid, and displayed enhanced antiproliferative effect toward prostate cancer cells PTEN-P2 compared to free plumbagin. Conclusion. High drug-loading capacity, retention of nanoparticle size, kinetics of release under simulated physiological conditions, and increased antiproliferative activity indicate that oleic-acid based nanoemulsion formulation is a suitable delivery system of plumbagin.
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Zhang, Lian Zhong, and Jing Min Li. "The Research of Composite Solar and Wind Energy Materials Generator." Advanced Materials Research 531 (June 2012): 584–88. http://dx.doi.org/10.4028/www.scientific.net/amr.531.584.
Повний текст джерелаАнотація:
Composite generator of solar and wind energy materials the generators， energy-saving environmental protection as a precondition to full use of green renewable energy, making wind power in weak wind conditions and strong winds can maintain normal operation of wind turbines how wind instability Under normal operation, but at higher wind speeds, the blades are not damaged? We start from the pressure-controlled device, the mechanical components and microelectronic technology combine to complete the slurry from the regulator controlled by changing the role of plasma from the body, strengthen the control of wind turbines, wind generators can adapt to changes in wind speed. In the initial wind speed easy to start; in the design of wind speed and wind speed between the initial access to higher wind energy utilization coefficient; In addition, the weak and the solar wind is sufficient,solar power can also get the power to add the function to ensure that the entire power system running smoothly, to achieve full power generation purposes.
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Derr, Jeffrey F. "Broadleaf Weed Control with Sulfonylurea Herbicides in Cool-Season Turfgrass." Weed Technology 26, no. 3 (September 2012): 582–86. http://dx.doi.org/10.1614/wt-d-11-00166.1.
Повний текст джерелаАнотація:
Broadleaf weeds are common and troublesome pests in cool-season turfgrass species such as tall fescue, Kentucky bluegrass, perennial ryegrass, and creeping bentgrass. Broadleaf weeds are primarily managed in these grasses through POST applications of growth regulator herbicides in the phenoxy, benzoic acid, and pyridine chemical classes. There are disadvantages to use of these chemicals, including nontarget plant damage and limited residual control. Certain annual broadleaf weeds can be controlled through application of isoxaben or a PRE crabgrass herbicide, but these herbicides do not control emerged broadleaf weeds. There are advantages to use of sulfonylurea herbicides, including PRE and POST control of annual and perennial weeds, a different mode of action, and these herbicides have low vapor pressure, reducing the potential for offsite movement. There are disadvantages to the use of sulfonylurea herbicides, including limited spectrum of broadleaf weed species controlled and limited tolerance in cool-season turfgrass species. The primary sulfonylurea herbicides used in cool-season turfgrass are chlorsulfuron, halosulfuron, metsulfuron, and sulfosulfuron. There have been specialized uses for primisulfuron and tribenuron-methyl.
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Hoshide, Reid, Robert C. Rennert, Carlos E. Sanchez, Joel R. Martin, Vincent J. Cheung, Gayle Gyles, and Michael L. Levy. "Rate-controlled intraventricular endoscopic irrigation via bipolar foot pedal activation: technical note." Journal of Neurosurgery: Pediatrics 25, no. 4 (April 2020): 434–38. http://dx.doi.org/10.3171/2019.11.peds19471.
Повний текст джерелаАнотація:
Irrigation during intraventricular endoscopic surgery is critical for visualization, with normal intracranial pressure maintained by balancing fluid ingress and egress. Although irrigation is typically achieved through manual manipulation of inexact stopcocks, the authors have developed a rate-controlled, foot pedal–activated system for precise intraventricular irrigation by using a standard irrigating bipolar electrocautery machine.This study is a retrospective review of patients who underwent endoscopic intraventricular surgery between January 1, 2018, and September 25, 2019, in which this irrigation system was used. Important components of this system include a bipolar module irrigation regulator that is set to a desired rate, a secure connection of the bipolar irrigation tubing to the endoscope, and one or more open egress ports on the endoscope for passive fluid drainage. Nineteen consecutive patients were identified on review (average age ± SD, 4.3 ± 4.1 years). Procedures performed included third ventriculostomies (n = 10); arachnoid/choroid cyst fenestrations/resections (n = 3); biopsy/tumor resection (n = 1); and combined procedures (n = 5). Foot pedal–controlled irrigation provided visualization of all intraventricular structures. A single operator was able to control the endoscope, endoscopic instruments, and irrigation, with assistance as indicated for more complex maneuvers. There were no perioperative complications. Because this setup is easily constructed from a standard irrigating bipolar machine, delivers precise irrigation flow rates, and facilitates a single-surgeon bimanual technique, these data support the utility of foot-controlled irrigation for endoscopic intraventricular surgery.
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Bhat, Ajaz A., H. Mang, Rajkumar S., T. M. Kotresh, and U. K. Singh. "On-Board Oxygen Generation Using High Performance Molecular Sieve." Defence Life Science Journal 2, no. 4 (November 10, 2017): 380. http://dx.doi.org/10.14429/dlsj.2.12274.
Повний текст джерелаАнотація:
<p class="p1">The majority of high performance combat aircrafts presently being operated by Indian air Force are fitted with conventional oxygen systems in which a replenishable store of oxygen is carried, most often as liquid oxygen and the flow of gas to each crew member is controlled by an individual pressure demand regulator in which the oxygen is diluted with cabin air to provide breathing gas.Moreover, in-flight refueling capability of present generation fighter aircraft has made it possible to fly for long durations (6 to 8 hours). In such case, the oxygen source becomes one of the limiting factors. In order to meet this requirement, a large supply of Gaseous Oxygen (GASOX) or Liquid Oxygen (LOX) have proven to be a costly affair and the Onboard Oxygen Generating System (OBOGS) has become a very convenient and attractive proposal. The OBOGS employs molecular sieves to adsorb nitrogen from engine bleed air using pressure swing adsorption (PSA) technique, wherein two molecular sieve beds are continuously cycled between steps of pressurization (adsorption) and depressurization (desorption) to generate oxygen enriched breathing gas for aircrew. This paper describes the design of OBOGS using high performance Lithium based Low Silica X-type (Li-LSX) molecular sieves and its performance characteristics. It consists of two Zeolite beds filled with Li-LSX material which adsorbs nitrogen fromengine bleed air tapped from Environmental Control System pipe line. The two beds are cycled by a 5/2 way solenoid valve. The input air is supplied to the solenoid valve through a coalescent filter to reduce moisture from it and a pressure regulator is fitted at the upstream of solenoid valve to regulate the system pressure. The experimental setup for evaluation of OBOGS is also discussed. The OBOGS, presented in this paper, meets all the performance requirements as specified in MIL-C-85521 (AS).<span class="Apple-converted-space"> </span></p>
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Rattanongphisat, Waraporn. "Efficiency of Vortex Tube Enclosure Cooling." Applied Mechanics and Materials 666 (October 2014): 154–58. http://dx.doi.org/10.4028/www.scientific.net/amm.666.154.
Повний текст джерелаАнотація:
A vortex tube offers an alternative cooling with advantages of simplicity and compact. Using a natural refrigerant, a vortex tube enclosure cooling is environmentally benign. In this paper, the performance of a vortex tube enclosure cooling, VTEC, is investigated experimentally. The VTEC system comprises of the vortex tube cooling, an enclosure with a volume space of 0.045 m3, an air compressor, a compressed air storage tank and a compressed air line. The VTEC system is tested for its efficiency and cooling potential in the laboratory. An operating condition is controlled by a pressure regulator for an inlet air pressure of 3 bars, for energy saving, and a cold flow rate is adjusted by a needle valve near the hot exit of a vortex tube for the cold fraction between 0 and 1. Accordingly, the analysis of experimental data shows the maximum isentropic efficiency of the vortex tube enclosure cooling is 0.37 at the cold mass fraction of 0.45. Air temperature in the enclosure is about 13°C in average.
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Zivanovic, Jasmina, and Milos R. Filipovic. "Hydrogen sulfide: stench from the past as a mediator of the future." Biochemist 38, no. 5 (October 1, 2016): 12–17. http://dx.doi.org/10.1042/bio03805012.
Повний текст джерелаАнотація:
The past decade has witnessed the discovery of hydrogen sulfide (H2S) as a new signalling molecule. Its ability to act as a neurotransmitter, regulator of blood pressure, immunomodulator or anti-apoptotic agent, together with its great pharmacological potential, is now well established. Notwithstanding the growing body of evidence showing the biological roles of H2S, the gap between these roles and the actual mechanism(s) behind these processes is getting larger. We propose a way that protein cysteine residues can be modified to form protein persulfides (P-SSH) and explain how this process is controlled in a physiologically relevant fashion. This article provides an overview of H2S signalling in the human body with particular emphasis on the latest discoveries regarding the mechanisms of protein persulfidation and depersulfidation, as well as about the biological reactivity of persulfides and their role in health and disease.
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Grigorova, N. P., P. V. Monastyrev, E. G. Pakhomova, and N. E. Semicheva. "Aerodynamics and Heat Transfer of Swirling Natural Gas Flow in a Vortex Heat Exchanger of the Heating System of a Gas Control Point." Proceedings of the Southwest State University 24, no. 3 (December 6, 2020): 99–110. http://dx.doi.org/10.21869/2223-1560-2020-24-3-99-110.
Повний текст джерелаАнотація:
Purpose of research. To obtain a two-parameter model characterizing the aerodynamic and heat exchange processes occurring in a vortex heat exchanger, giving a better agreement between the calculated and experimental values of the heat transfer coefficient taking into account the curvature of the swirling gas flow in a vortex heat exchanger, in which a controlled gas pressure drop is used as a source of thermal energy. This technical solution will make it possible to abandon the installation of autonomous sources of thermal energy, which will reduce the cost of gas as a fuel in the heating system of the industrial premises of the gas distribution point (GDP), as well as provide more comfortable working conditions for the hydraulic fracturing pressure regulator. Methods. Comprehensive analysis of thermal and hydraulic characteristics in a vortex heat exchanger is based on well-known theoretical positions and equations of motion of a swirling gas flow and heat exchange laws. Results. It is obtained a dependence that characterizes the intensification of heat transfer based on the influence of the axial and rotational speed, as well as the path of motion of the swirling gas flow. This dependence is obtained on the basis of a comprehensive analysis of the aerodynamic and heat exchange characteristics of a vortex heat exchanger, in which a controlled gas pressure drop is used as a source of thermal energy. Conclusion. The obtained two-parameter model gives the best agreement of the calculated values of the heat transfer coefficient with the values obtained experimentally, which were used in the thermal engineering calculation of the design parameters of the vortex heat exchanger.
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Powell, Heather M., Molly E. Baumann, and John Kevin Bailey. "656 Inter- and Intra-user Reliability of Skin Graft Thickness as a Function of Instrument." Journal of Burn Care & Research 41, Supplement_1 (March 2020): S173—S174. http://dx.doi.org/10.1093/jbcr/iraa024.274.
Повний текст джерелаАнотація:
Abstract Introduction The most popular powered dermatomes (both electric and pneumatic) have a linear blade which oscillates at high speeds. Though the thickness of skin graft being elevated can be controlled by the depth-adjustment dial on the side of the instrument, factors, such as applied pressure, angle between the instrument and the surface, and curvature of the harvest site, can cause deviations from the target depth. As a result, the same depth setting can result in significantly different thicknesses of excised tissue among operators. A newer, powered dermatome has been developed which pneumatically rotates a circular blade at a fixed angle to the surface of the skin and does not require additional downward pressure. The goal of this study was to assess inter- and intra-user uniformity of graft thickness using conventional and newly designed dermatomes and assess the accuracy of the excised thickness. Methods Split thickness skin grafts were collected from the dorsum of Yorkshire pigs using a conventional dermatome and a newly designed test dermatome. Three different users collected three 2-inch wide by 4-inch long strips of skin using both instruments. Skin thickness at the center and edges of each strip were measured using a digital micrometer. Additionally, grafts were laser scanned to create a map of thickness for the entire piece of tissue. Reliability of the harvest was assessed using inter- and intra-class correlation coefficient. Results Both instruments were set to collect grafts 0.012” thick. Grafts harvested using the conventional dermatome ranged from 0.020–0.038” thick while grafts harvested with the test instrument ranged from 0.008–0.016” thick. On average, the conventional dermatome harvested grafts that were 2.16-fold thicker than the instrument setting while the test instrument collected grafts 0.91-fold the target thickness. Intra-user reliability was similar between instruments with greater reliability observed when users has substantial prior experience. Additionally, inter-user reliability was significantly increased with the test instrument. Conclusions Many factors control the uniformity and overall thickness of a skin graft including applied pressure and angle of attack, and how much tension is applied to the elevated graft. Using a conventional dermatome, variability in thickness was observed with greater average measured thickness versus depth setting. Grafts harvested using the newly designed instrument were on average closer to the desired thickness and more reproducible among users. Applicability of Research to Practice New instruments for skin harvesting may enhance uniformity of skin grafts.
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Bech, J. N., C. B. Nielsen, and E. B. Pedersen. "Effects of systemic NO synthesis inhibition on RPF, GFR, UNa, and vasoactive hormones in healthy humans." American Journal of Physiology-Renal Physiology 270, no. 5 (May 1, 1996): F845—F851. http://dx.doi.org/10.1152/ajprenal.1996.270.5.f845.
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Animal studies have implicated an important role of nitric oxide (NO) in the regulation of blood pressure, renal hemodynamics, and renal excretion of sodium. NG-monomethyl-L-arginine (L-NMMA) is a specific, competitive inhibitor of NO synthesis interfering with NO synthase. The purpose of the present study was to investigate the effect of L-NMMA on renal plasma flow (RPF), glomerular filtration rate (GFR), urinary sodium excretion (UNa), fractional sodium excretion (FENa), fractional lithium excretion (FELi), mean arterial blood pressure (MAP), and heart rate (HR) in healthy humans. In a randomized placebo-controlled study, 23 healthy subjects were randomized to receive either bolus injection of L-NMMA (3 mg/kg in 10 ml saline, n = 12 subjects) or placebo (10 ml saline, n = 11). GFR and RPF were measured using the renal clearances of 51Cr-labeled EDTA and 125I-labeled hippuran by the constant infusion technique. L-NMMA treatment induced 60 min after injection a 14.6% decrease in RPF, a 5.8% decrease in GFR, a 9.8% increase in filtration fraction, a 34.7% decrease in UNa a 28.6% decrease in FENa, and a 12.1% decrease in FELi. These changes were still evident 120 min after injection. None of the effect parameters were changed after placebo, except FENa, which increased 9.9% 60 min after injection. Ten minutes after L-NMMA injection, MAP increased significantly (80 vs. 88 mmHg), and HR decreased (58 vs. 47 beats/min). The changes in HR and MAP normalized within 30 min. L-NMMA significantly reduced the plasma level of cGMP 60 min (3.0 vs. 3.7 pmol/l) and 120 min after injection (2.5 vs. 3.7 pmol/l). It is concluded that, in healthy humans, NO is a regulator of renal hemodynamics as a tonic vasodilator and a regulator of sodium excretion, due at least in part to a proximal tubular effect.
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Wolzt, Michael, Leopold Schmetterer, Guido Dorner, Georg Zelger, Jesusa Entlicher, Stylianos Kapiotis, and Hans-Georg Eichler. "Hemodynamic Effects of Parathyroid Hormone-Related Peptide-(1–34) in Humans1." Journal of Clinical Endocrinology & Metabolism 82, no. 8 (August 1, 1997): 2548–51. http://dx.doi.org/10.1210/jcem.82.8.4120.
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It has been suggested that PTH-related peptide-(1–34) (PTHrP) is a regulator or modulator of regional or systemic cardiovascular function with varying vasodilating actions in different species. We have studied the cardiovascular pharmacodynamic profile of PTHrP in healthy humans. In a double blind, placebo-controlled, cross-over study design, eight healthy subjects were assigned to stepwise increased iv doses of PTHrP. In addition, a dose-response curve to PTHrP was constructed in a dorsal hand vein in eight subjects. PTHrP dose-dependently increased pulse rate and renal plasma flow by more than 50% (P < 0.0001 for both parameters, by ANOVA), but only a small venodilating response was seen in hand vein experiments, and no effect was noted on mean arterial blood pressure or cardiac inotropic performance. Although it is unlikely that PTHrP regulates systemic hemodynamics, its chronotropic effect and its potent action on renal plasma flow may represent the primary cardiovascular physiological targets of action.
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Zhang, Liqin, Yang Wu, Boyuan Li, Bangji Zhang, and Nong Zhang. "A novel manoeuvre stability controller based on vehicle state prediction and intellectual braking torque distribution." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 1 (May 3, 2019): 136–51. http://dx.doi.org/10.1177/0954407019845717.
Повний текст джерелаАнотація:
This paper proposes an innovative hierarchical direct yaw moment control strategy consisting of upper, middle and lower controllers. In the upper layer, a linear quadratic regulator metric based on current side-slip angle and predicted yaw rate is established to generate the controlled yaw moment. The middle layer determines the actuating tyre forces and allocates the required longitudinal forces for each tyre according to the current tyre–road contact condition. Furthermore, the desired longitudinal slip ratios for each tyre are calculated in the middle layer. Finally, a suitable brake pressure is achieved by the sliding mode controller in the lower layer. The simulation results of sine with dwell and double lane change verify the effectiveness of the proposed method. Compared with a traditional direct yaw moment control strategy that preferentially brakes the priority wheel, the proposed novel strategy is able to keep the longitudinal force of the tyre working in a linear region and has better robustness response when the tyre–road contact condition encounters sudden change.
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Lu, Dang, Yao Ma, Hengfeng Yin, Zhihui Deng, and Jiande Qi. "Development and Validation of Electronic Stability Control System Algorithm Based on Tire Force Observation." Applied Sciences 10, no. 23 (December 7, 2020): 8741. http://dx.doi.org/10.3390/app10238741.
Повний текст джерелаАнотація:
In view of the higher and higher assembly rate of the electronic stability control system (ESC in short), the control accuracy still needs to be improved. In order to make up for the insufficient accuracy of the tire model in the nonlinear area of the tire, in this paper, an algorithm for the electronic stability control system based on the control of tire force feedforward used in conjunction with tire force sensors is proposed. The algorithm takes into consideration the lateral stability of the tire under extreme conditions affected by the braking force. We use linear optimal control to determine the optimal yaw moment, and obtain the brake wheel cylinder pressure through an algorithm combining feedforward compensation based on measured tire force and feedback correction. The controller structure is divided into two layers, the upper layer is controlled by a linear quadratic regulator (LQR in short) and the lower layer is controlled by PID (Proportional-integral-derivative) and feedforward. After that, verification of the controller’s algorithms using software cosimulation and hardware-in-the-loop (HIL in short) testing in the double lane change (DLC in short) and sine with dwell (SWD in short) conditions. From the test results it can be concluded that the controller based on tire force observation has partially control advantages.
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Boltz, Agnes, Doreen Schmidl, René M. Werkmeister, Michael Lasta, Semira Kaya, Stefan Palkovits, Reinhard Told, Sophie Frantal, Gerhard Garhöfer, and Leopold Schmetterer. "Role of endothelin-A receptors in optic nerve head red cell flux regulation during isometric exercise in healthy humans." American Journal of Physiology-Heart and Circulatory Physiology 304, no. 1 (January 1, 2013): H170—H174. http://dx.doi.org/10.1152/ajpheart.00408.2012.
Повний текст джерелаАнотація:
Endothelin-1 (ET-1) is an important regulator of vascular tone in the eye. It appears to play a role in ocular disease because of its strong vasoconstrictor action, its role in intraocular pressure homeostasis, and its neurotoxic potential. We have previously shown that ET-1 is involved in choroidal red cell flux (RCF) regulation during isometric exercise in healthy humans. In the present study we hypothesized that ET-1 also plays a role in optic nerve head (ONH) RCF regulation during isometric exercise. To test this hypothesis, we performed a randomized, double-masked, placebo-controlled, two-way crossover study in 15 healthy volunteers. Subjects were randomized to receive intravenous infusions of the specific endothelin type A receptor antagonist BQ-123 and placebo on two different study days. During these infusion periods, subjects performed squatting for 6 min to increase ocular perfusion pressure (OPP). ONH RCF was assessed with laser-Doppler flowmetry, and OPP was calculated from mean arterial pressure and intraocular pressure. BQ-123 did not change OPP or ONH RCF at baseline. The relative increase in OPP during isometric exercise was comparable between both groups (between 84 and 88%, P = 0.76 between groups; P < 0.001 vs. baseline). Isometric exercise increased ONH RCF during placebo and BQ-123, but the increase was more pronounced when the endothelin type-A receptor antagonist was administered (placebo, 27.3 ± 5.4%; and BQ-123, 39.2 ± 4.4%; P = 0.007 between groups). The present data indicate that ET-1 regulates red cell flux in the ONH beyond the autoregulatory range.
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Robertson, Andrew D., Heather Edgell, and Richard L. Hughson. "Assessing cerebrovascular autoregulation from critical closing pressure and resistance area product during upright posture in aging and hypertension." American Journal of Physiology-Heart and Circulatory Physiology 307, no. 2 (July 15, 2014): H124—H133. http://dx.doi.org/10.1152/ajpheart.00086.2014.
Повний текст джерелаАнотація:
Static cerebral autoregulation (sCA) is believed to be resistant to aging and hypertensive pathology. However, methods to characterize autoregulation commonly rely on beat-by-beat mean hemodynamic measures and do not consider within-beat pulse wave characteristics that are impacted by arterial stiffening. We examined the role of critical closing pressure (CrCP) and resistance area product (RAP), two measures derived from the pulse wave, across supine lying, sitting, and standing postures in young adults, normotensive older adults, and older adults with controlled and uncontrolled hypertension ( N = 80). Traditional measures of sCA, using both intracranial and extracranial methods, indicated similar efficiency across all groups, but within-beat measures suggested different mechanisms of regulation. At rest, RAP was increased in hypertension compared with young adults ( P < 0.001), but CrCP was similar. In contrast, the drop in CrCP was the primary regulator of change in cerebrovascular resistance upon adopting an upright posture. Both CrCP and RAP demonstrated group-by-posture interaction effects ( P < 0.05), with older hypertensive adults exhibiting a rise in RAP that was absent in other groups. The posture-related swings in CrCP and RAP were related to changes in both the pulsatile and mean components of arterial pressure, independent of age, cardiac output, and carbon dioxide. Group-by-posture differences in pulse pressure were mediated in part by an attenuated heart rate response in older hypertensive adults ( P = 0.002). Examination of pulsatile measures in young, elderly, and hypertensive adults identified unique differences in how cerebral blood flow is regulated in upright posture.
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Klett, Christoph P. R., and Joey P. Granger. "Physiological Amounts of Angiotensinogen Increase Blood Pressure in Sprague Dawley Rats After I.V. Administration." Hypertension 36, suppl_1 (October 2000): 694. http://dx.doi.org/10.1161/hyp.36.suppl_1.694-d.
Повний текст джерелаАнотація:
P9 The synthesis and secretion of hepatic angiotensinogen is controlled by a complex pattern of physiologic and pathophysiologic mediators including glucocorticoids, estrogens, thyroid hormones, cytokines, glucagon,insulin, and prostaglandins. Since plasma concentrations of angiotensinogen are close to the Michaelis Menten constant, it was hypothesized that changes in angiotensinogen plasma concentrations have an influence on the formation rate of angiotensin I and angiotensin II and, therefore, on blood pressure. To further test this hypothesis we injected purified rat angiotensinogen i.v. in Sprague Dawley rats via the femoral vein. Mean arterial blood pressure was measured after arterial cathederization. Control animals had a mean arterial pressure of 131 ± 2 mm Hg before and after the injection of vehicle (saline). The injection of 0.8, 1,2, and 2.9 mg/kg angiotensinogen caused a dose dependend increase in mean arterial blood pressure of 8 ± 0.4, 19.3 ± 2.1, and 32 ± 2.4 mm Hg, respectively. In contrast, the injection of a purified rabbit anti-rat-angiotensinogen antibody 1.4 mg/kg resulted in a significant decrease in blood pressure (-52 ± 3.2 mmHg). In an attempt to analyze how fast and efficient angiotensinogen production can sense regulatory input and convert into adaptation of secretion rate we determined the transit time (time needed for translation and post-translational modifications) for angiotensinogen in a pulse chase experiment employing 35 [S]-methionine as label in freshly isolated hepatocytes. During the chase periode, after quantitative immunoprecipitation, we determined the transit time for angiotensinogen with 2.5 h which is consistent with the constitutive type of angiotensinogen secretion and the time lag found for plasma concentrations to respond to regulatory mediators. In summary we conclude that variations in angiotensinogen plasma concentrations can result in changes in blood pressure. In contrast to renin known as a tonic regulator for the generation of angiotensin I, angiotensinogen seems to be a factor rather important for long-term control of the basal activity of the renin angiotensin system.
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Буряченко, Анна Григорьевна, та Иван Константинович Лопащенко. "МЕТРОЛОГIЧНЕ ЗАБЕЗПЕЧЕННЯ ВИПРОБУВАНЬ ЕЛЕКТРОННИХ РЕГУЛЯТОРIВ ГТД – СТЕНД-IМIТАТОР ДВИГУННИХ ДАТЧИКIВ". Aerospace technic and technology, № 7 (10 листопада 2018): 101–6. http://dx.doi.org/10.32620/aktt.2018.7.15.
Повний текст джерелаАнотація:
Testing of electronic control systems (further “regulators”) FADEC for gas turbine engines in the manufacturer laboratory conditions is described. The main attention is devoted to the control of the metrological characteristics of the regulator measuring channels. The results of constructively separated sensor imitators application, what interacts with the controller, including DBSCT and vibration sensor, are presented in this article. It is shown the expediency and results of the stand application, which united all the imitators necessary for testing of serial production. Data on verifying imitators and ensuring accuracy coefficients is given. In the framework of testing the electronic regulators of gas turbine engines, JSC Element experts developed, manufactured and certified all the necessary specialized stands that provide both a full-fledged inspection in the test-laboratory of monitoring and functions checking and additionally checking of the metrological characteristics of the regulators measuring channels. For reduced testing time in the serial production of the RDTs-450M regulator, in addition to the previously used structurally isolated sensors imitators, a stand was designed and manufactured combining all the imitators necessary for measuring channels testing. This new imitator provided usability and reduced testing time. The simulators used for test procedure. These simulators provide output signals of real sensors. These signals check by standardized measuring equipment. Systematic verification use certified stands, which create a normalized influence on the input signal of measuring (pressure, vibration acceleration, shaft rotation angle are also available). Further improvement of the test equipment will consist in automating of procedures for checking the metrological characteristics of the regulators channels by creating of programmatically controlled simulators. The replacement of individual simulators with a specialized stand markedly increased the productivity of work on the calibration and verification of the regulators measuring channels.
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Nguyen Dinh Cat, Aurélie, Antoine Ouvrard-Pascaud, François Tronche, Maud Clemessy, Daniel Gonzalez-Nunez, Nicolette Farman, and Frederic Jaisser. "Conditional Transgenic Mice for Studying the Role of the Glucocorticoid Receptor in the Renal Collecting Duct." Endocrinology 150, no. 5 (December 23, 2008): 2202–10. http://dx.doi.org/10.1210/en.2008-1531.
Повний текст джерелаАнотація:
The mineralocorticoid receptor (MR) is a major regulator of renal sodium reabsorption and body fluid homeostasis. However, little is known about glucocorticoid receptor (GR)-dependent renal effects. Glucocorticoids may activate both receptors, so it is difficult to distinguish between MR- and GR-mediated effects in vivo. To overcome this complexity, we used a transgenic mouse model allowing conditional GR overexpression (doxycycline inducible TetON system, Hoxb7 promoter) in the renal collecting duct (CD) to identify GR-regulated genes involved in sodium transport in the CD. In microdissected cortical CD, induction of GR expression led (after 2 d of doxycycline) to increased α-epithelial sodium channel and glucocorticoid-induced leucine zipper and decreased abundance of with-no-lysine kinase 4 transcripts, without modification of Na,K-ATPase, serum- and glucocorticoid-kinase-1, or MR expression. No changes occurred in the upstream distal and connecting tubules [distal convoluted tubule (DCT), connecting tubule (CNT)]. Sodium excretion was unaltered, but the urinary aldosterone concentration was reduced, suggesting compensation of transitory extracellular volume expansion that subsequently disappeared. At steady state, i.e. after 15 d of doxycycline administration, transcript abundance remained altered in the CD, whereas mirror changes appeared in the DCT and CNT. Plasma aldosterone or glucocorticoids and blood pressure were all unaffected. These experiments show that: 1) GR, in addition to MR, controls epithelial sodium channel- and glucocorticoid-induced leucine zipper expression in vivo in the CD; 2) with-no-lysine kinase 4 is negatively controlled by GR; and 3) the DCT and CNT compensate for these alterations to maintain normal sodium reabsorption and blood pressure. These results suggest that enhanced GR expression may contribute to enhanced sodium retention in some pathological situations.
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Denisov, Viatcheslav A., and Aleksey A. Solomashkin. "Ensuring Reliable Operation of Machine Parts with a New System of Variable Tolerances." Engineering Technologies and Systems 30, no. 1 (March 31, 2020): 76–91. http://dx.doi.org/10.15507/2658-4123.030.202001.076-091.
Повний текст джерелаАнотація:
Introduction. The article describes an algorithm for determining the system of tolerances for ensuring reliable operation of parts on the section. The block diagram of the program for determining the variable tolerances is demonstrated. There determined blocks of initial information − broken and smooth curves of the controlled parameter, histogram and graph of resource distribution and definition of active area of control, and blocks of building graphs of “marginal fan curves of wear” and systems of admissions for objects of study of two types: for universal fuel pump (UTN-5) and four-section small-sized fuel pump with mechanical regulator. Two ways of determining the system of tolerances are suggested. Variant 1 is a graphical way through constructing “limit fan curves of wear” and determining tolerances by the value of ordinates in the control points. Variant 2 is an analytical way. There is created a formula to replace the graphical method for determining system tolerances. Materials and Methods. Two models of high-pressure pump were selected as objects of the study. Nominal and limit values of parameters were known for the pumps. Schedules for checking and equation of wear curves are determined. Dependencies describing the pump plunger pair wear curves are determined. A histogram and graph for determining pump life cycles are drawn. The active area of control is determined with a given failure probability coefficient. Results. As a result of the study the values for the tolerances system of two types of high pressure fuel pumps are obtained. Reliability values for one pump type are determined. Graphic and analytical algorithms for determining the system of tolerances by the formula are developed. Discussion and Conclusion. The study approves the possibility of using the variable tolerance as a basis for determining the system of tolerances and reliability indicators of the diagnostic object.