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Wyniki wyszukiwania dla: DIRECTIONAL PULSE PROPAGATION
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Rapid simulation-driven design of miniaturised dual-band microwave couplers by means of adaptive response scaling
PublikacjaOne of the major challenges in the design of compact microwave structures is the necessity of simultaneous handling of several objectives and the fact that expensive electromagnetic (EM) analysis is required for their reliable evaluation. Design of multi-band circuits where performance requirements are to be satisfied for several frequencies at the same time is even more difficult. In this work, a computationally efficient design...
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Analytical Expression for the Time-Domain Green's Function of a Discrete Plane Wave Propagating in the 3-D FDTD Grid
PublikacjaIn this paper, a closed-form expression for the time-domain dyadic Green’s function of a discrete plane wave (DPW) propagating in a 3-D finite-difference time-domain (FDTD) grid is derived. In order to verify our findings, the time-domain implementation of the DPW-injection technique is developed with the use of the derived expression for 3-D total-field/scattered-field (TFSF) FDTD simulations. This implementation requires computations...
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Accurate Modeling of Antenna Structures by Means of Domain Confinement and Pyramidal Deep Neural Networks
PublikacjaThe importance of surrogate modeling techniques has been gradually increasing in the design of antenna structures over the recent years. Perhaps the most important reason is a high cost of full-wave electromagnetic (EM) analysis of antenna systems. Although imperative in ensuring evaluation reliability, it entails considerable computational expenses. These are especially pronounced when carrying out EM-driven design tasks such...
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Expedited Gradient-Based Design Closure of Antennas Using Variable-Resolution Simulations and Sparse Sensitivity Updates
PublikacjaNumerical optimization has been playing an increasingly important role in the design of contemporary antenna systems. Due to the shortage of design-ready theoretical models, optimization is mainly based on electromagnetic (EM) analysis, which tends to be costly. Numerous techniques have evolved to abate this cost, including surrogate-assisted frameworks for global optimization, or sparse sensitivity updates for speeding up local...
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Tolerance-Aware Multi-Objective Optimization of Antennas by Means of Feature-Based Regression Surrogates
PublikacjaAssessing the immunity of antenna design to fabrication tolerances is an important consideration, especially when the manufacturing process has not been predetermined. At the same time, the antenna parameter tuning should be oriented toward improving the performance figures pertinent to both electrical (e.g., input matching) and field properties (e.g., axial ratio bandwidth) as much as possible. Identification of available trade-offs...
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Robust Parameter Tuning of Antenna Structures by Means of Design Specification Adaptation
PublikacjaParameter tuning through numerical optimization has become instrumental in the design of high-performance antenna systems. Yet, practical optimization faces several major challenges, including high cost of massive evaluations of antenna characteristics, normally involving full-wave electromagnetic (EM) analysis, large numbers of adjustable variables, the shortage of reasonable initial solutions in the case of topologically complex...
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Accelerated Gradient-Based Optimization of Antenna Structures Using Multi-Fidelity Simulations and Convergence-Based Model Management Scheme
PublikacjaThe importance of numerical optimization has been steadily growing in the design of contemporary antenna structures. The primary reason is the increasing complexity of antenna topologies, [ a typically large number of adjustable parameters that have to be simultaneously tuned. Design closure is no longer possible using traditional methods, including theoretical models or supervised parameter sweeping. To ensure reliability, optimization...
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Expedited Acquisition of Database Designs for Reduced-Cost Performance-Driven Modeling and Rapid Dimension Scaling of Antenna Structures
PublikacjaFast replacement models have been playing an increasing role in high-frequency electronics, including the design of antenna structures. Their role is to improve computational efficiency of the procedures that normally entail large numbers of expensive full-wave electromagnetic (EM) simulations, e.g., parametric optimization or uncertainty quantification. Recently introduced performance-driven modeling methods, such as the nested...
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Reliable EM-driven size reduction of antenna structures by means of adaptive penalty factors
PublikacjaMiniaturization has become of paramount importance in the design of modern antenna systems. In particular, compact size is essential for emerging application areas such as internet of things, wearable and implantable devices, 5G technology, or medical imaging. On the other hand, reduction of physical dimensions generally has a detrimental effect on antenna performance. From the perspective of numerical optimization, miniaturization...
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Generalized Formulation of Response Features for Reliable Optimization of Antenna Input Characteristics
PublikacjaElectromagnetic (EM)-driven parameter adjustment has become imperative in the design of modern antennas. It is necessary because the initial designs rendered through topology evolution, parameter sweeping, or theoretical models, are often of poor quality and need to be improved to satisfy stringent performance requirements. Given multiple objectives, constraints, and a typically large number of geometry parameters, the design closure...
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Computationally Efficient Surrogate-Assisted Design of Pyramidal-Shaped 3D Reflectarray Antennas
PublikacjaReflectarrays (RAs) have been attracting considerable interest in the recent years due to their appealing features, in particular, a possibility of realizing pencil-beam radiation patterns, as in the phased arrays, but without the necessity of incorporating the feeding networks. These characteristics make them attractive solutions, among others, for satellite communications or mobile radar antennas. Notwithstanding, available microstrip...
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Rapid Variable-Resolution Parameter Tuning of Antenna Structures Using Frequency-Based Regularization and Sparse Sensitivity Updates
PublikacjaGeometry parameter tuning is an inherent part of antenna design process. While most often performed in a local sense, it still entails considerable computational expenses when carried out at the level of full-wave electromagnetic (EM) simulation models. Moreover, the optimization outcome may be impaired if good initial design is not available. This paper proposes a novel approach to fast and improved-reliability gradient-based...
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Tolerance Optimization of Antenna Structures by Means of Response Feature Surrogates
PublikacjaFabrication tolerances and other types of uncertainties, e.g., the lack of precise knowledge of material parameters, have detrimental effects on electrical and field performance of antenna systems. In the case of input characteristics these are particularly noticeable for narrow- and multi-band antennas where deviations of geometry parameters from their nominal values lead to frequency shifts of the operating frequency bands. Improving...
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Low-cost data-driven modelling of microwave components using domain confinement and PCA-based dimensionality reduction
PublikacjaFast data-driven surrogate models can be employed as replacements of computationally demanding full-wave electromagnetic simulations to facilitate the microwave design procedures. Unfortunately, practical application of surrogate modelling is often hindered by the curse of dimensionality and/or considerable nonlinearity of the component characteristics. This paper proposes a simple yet reliable approach to cost-efficient modelling...
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Bandwidth-size design trade-offs for compact spline-parameterised patch couplers by means of electromagnetic-driven multi-objective optimisation
PublikacjaBroad bandwidth and small size are the key performance figures for contemporary microwave couplers. These requirements are conflicting, i.e. improvement of one generally leads to degradation of the other assuming fixed topology of the circuit at hand. From a designer's perspective, the knowledge about available design trade-offs is indispensable as it permits for tailoring the circuit for particular applications as well as comparing...
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Constrained optimization for generating gain-bandwidth design trade-offs of wideband unidirectional antennas
PublikacjaBroadband unidirectional antennas realised in microstrip technology find applications in many wireless communication systems. One of their design challenges is the necessity of handling multiple performance figures which is difficult when using traditional design methods, largely based on parameter sweeping. This work presents a simple optimisation-based framework that permits generation of gain-bandwidth trade-off designs for...
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Fast surrogate-assisted frequency scaling of planar antennas with circular polarisation
PublikacjaIn this work, the problem of computationally efficient frequency scaling (re-design) of circular polarisation antennas is addressed using surrogate-assisted techniques. The task is challenging and requires the identification of the optimum geometry parameters to enable the operation of the re-designed structure at a selected (required) centre frequency. This involves handling several performance figures such as the antenna gain,...
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A Conformal Circularly Polarized Series-Fed Microstrip Antenna Array Design
PublikacjaA conformal circularly polarized series-fed microstrip array design for broadside radiation is presented. The array aperture under design is conformal to a cylindrical surface of a given radius. The approach we present primarily addresses focusing of the circularly polarized major lobe of the conformal array by proper dimensioning of the aperture spacings. The proposed analytical models yield the values of the element spacings...
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Variable-fidelity response feature surrogates for accelerated statistical analysis and yield estimation of compact microwave components
PublikacjaAccounting for manufacturing tolerances is an essential part of a reliable microwave design process. Yet, quantification of geometry and/or material parameter uncertainties is challenging at the level of full-wave electromagnetic (EM) simulation models. This is due to inherently high cost of EM analysis and massive simulations necessary to conduct the statistical analysis. Here, a low-cost and accurate yield estimation procedure...
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Reduced-cost electromagnetic-driven optimisation of antenna structures by means of trust-region gradient-search with sparse Jacobian updates
PublikacjaNumerical optimisation plays more and more important role in the antenna design. Because of lack of design-ready theoretical models, electromagnetic (EM)-simulation-driven adjustment of geometry parameters is a necessary step of the design process. At the same time, traditional parameter sweeping cannot handle complex topologies and large number of design variables. On the other hand, high computational cost of the conventional...
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Computationally-efficient design optimisation of antennas by accelerated gradient search with sensitivity and design change monitoring
PublikacjaElectromagnetic (EM) simulation tools are of primary importance in the design of contemporary antennas. The necessity of accurate performance evaluation of complex structures is a reason why the final tuning of antenna dimensions, aimed at improvement of electrical and field characteristics, needs to be based on EM analysis. Design automation is highly desirable and can be achieved by coupling EM solvers with numerical optimisation...
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Communication Model Order Reduction in Hybrid Methods Involving Generalized Impedance Matrix
PublikacjaA novel strategy for the efficient analysis of frequency-domain scattering electromagnetic problems in open and closed domains is presented. A fully automatic model-order reduction technique, called the enhanced reduced-basis method, is applied to increase the efficiency of the hybrid approach, which combines the finite-element and mode-matching methods. Numerical tests show that the proposed algorithm yields reliable and highly...
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Compact Dual-Polarized Corrugated Horn Antenna for Satellite Communications
PublikacjaIn this paper, a structure and design procedure of a novel compact dual-polarized corrugated horn antenna with high gain and a stable phase center for satellite communication is presented. The antenna incorporates an Ortho-Mode Transducer (OMT), a mode converter, and a corrugated structure. The compact OMT section is designed to be fed by standard WR-75 waveguides. The proposed compact design utilizes only ten corrugated slots...
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Frequency-Based Regularization for Improved Reliability Optimization of Antenna Structures
PublikacjaThe paper proposes a modified formulation of antenna parameter tuning problem. The main ingredient of the presented approach is a frequency-based regularization. It allows for smoothening the functional landscape of the assumed cost function, defined to encode the prescribed design specifications. The regularization is implemented as a special penalty term complementing the primary objective and enforcing the alignment of the antenna...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.10, b=0.14) and (C=6.40, b=0.45) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.80, b=0.25) and (C=6.40, b=0.45) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.10, b=0.14) and (C=7.30, b=0.49) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.40, b=0.26) and (C=2.10, b=0.14) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=5.50, b=0.37) and (C=6.40, b=0.45) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.80, b=0.25) and (C=3.30, b=0.40) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.80, b=0.25) and (C=2.00, b=0.11) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.00, b=0.11) and (C=6.20, b=0.38) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.00, b=0.11) and (C=7.30, b=0.49) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.40, b=0.26) and (C=2.80, b=0.25) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.40, b=0.26) and (C=2.00, b=0.11) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.80, b=0.25) and (C=5.70, b=0.32) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=5.50, b=0.37) and (C=6.20, b=0.38) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.80, b=0.25) and (C=2.10, b=0.14) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.00, b=0.11) and (C=5.70, b=0.32) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.10, b=0.14) and (C=5.70, b=0.32) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.00, b=0.11) and (C=2.10, b=0.14) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.10, b=0.14) and (C=6.20, b=0.38) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.00, b=0.11) and (C=3.30, b=0.40) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.00, b=0.11) and (C=6.40, b=0.45) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.40, b=0.26) and (C=3.30, b=0.40) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.00, b=0.11) and (C=5.50, b=0.37) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.40, b=0.26) and (C=5.70, b=0.32) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for two directional control valves arranged in parallel. Three test configurations were used: (1) being emptied tank -> the first DCV -> ambient atmosphere, (2) being...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.40, b=0.26) and (C=6.40, b=0.45) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=2.10, b=0.14) and (C=3.30, b=0.40) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...
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Determination of flow properties of a parallel connection of two pneumatic elements with (C=5.50, b=0.37) and (C=7.30, b=0.49) from changes in air pressure in a tank being emptied
Dane BadawczeThe aim of the study was to determine the flow properties of parallel connection of pneumatic components.The experiments were to measure the pressure changes in a being emptied tank for a directional control valve and a pressure relief valve arranged in parallel. Three test configurations were used: (1) being emptied tank -> DCV -> ambient atmosphere,...