This study deals with a method to simulate transient responses of tapered fluid lines with rigid pipe walls. The fundamental equation employed in this analysis is a transfer matrix based on a fluid line model in which...
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This study deals with a method to simulate transient responses of tapered fluid lines with rigid pipe walls. The fundamental equation employed in this analysis is a transfer matrix based on a fluid line model in which the frequency-dependent effects of viscosity are considered. For the convenience of simulation, we employed a method for modeling irrational transfer matrix elements of the line by modal approximation. The resulting models were estimated as highly accurate by comparing them with the corresponding exact: solutions in frequency domain. By applying these approximation models to a block diagram representation, simulated results of transient responses were calculated. The simulated results of pressure and flow rate responses were compared with the corresponding analytical solutions. As a consequence, the validity and applicability of the proposed method were well confirmed.
Nickel-iron (Ni-Fe), nickel-cadmium (Ni-Cd), nickel-hydrogen (Ni-H-2), nickel-metal hydride (Ni-MH) and nickel-zinc (Ni-Zn) batteries employ nickel oxide electrodes as the positive plates, and are hence, categorised a...
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Nickel-iron (Ni-Fe), nickel-cadmium (Ni-Cd), nickel-hydrogen (Ni-H-2), nickel-metal hydride (Ni-MH) and nickel-zinc (Ni-Zn) batteries employ nickel oxide electrodes as the positive plates, and are hence, categorised as nickel-based batteries. This article highlights the operating principles and advances made in these battery systems during the recent years. In particular. significant improvements have been made in the Ni-MH batteries which are slowly capturing the market occupied by the ubiquitous Ni-Cd batteries. (C) 2001 Elsevier Science B.V. All rights reserved.
In this paper, the small-signal performance of different vector controllers for grid-connected voltage-source converters is investigated. Losses in the line filter, as well as nonlinearities due to blanking time and n...
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In this paper, the small-signal performance of different vector controllers for grid-connected voltage-source converters is investigated. Losses in the line filter, as well as nonlinearities due to blanking time and nonideal valves, are usually not modeled in the evaluation of the performance of control principles, A method to compensate for nonlinearities due to blanking time and nonideal valves is implemented, Furthermore, the influence of the compensation principle on the performance of traditional deadbeat controllers is shown in measured frequency responses. The compensation method reduces the cross-coupling gain and improves the direct-coupling gain, To show the influence of nonlinearities, measured frequency responses are compared with responses obtained from analytical models. At high frequencies, the frequency-dependent losses in the line filter should be taken into account to predict the dynamic performance correctly.
The ability of feedforward neural networks to approximate the dynamic behavior of linear and non-linear sensors was investigated. The networks were trained with data from simulated and real systems to compute the time...
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The ability of feedforward neural networks to approximate the dynamic behavior of linear and non-linear sensors was investigated. The networks were trained with data from simulated and real systems to compute the time varying sensor input from the measurable sensor output. Characteristic curves describing the static and dynamic network properties were calculated. The network performance was tested and visualized in time and frequency domain (bode diagram). It is shown that feedforward neural networks are an appropriate tool to approximate the dynamic behavior of non-linear gas sensors. (C) 1998 Elsevier Science S.A. All rights reserved.
Photocurrent iph and photopotential Vph vs. time t curves of thin γ-Fe2O3 films (<10 nm) deposited on Pt by MO-CVD technique were measured under intermittent illumination of white Xe arc light at various electrode...
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Photocurrent iph and photopotential Vph vs. time t curves of thin γ-Fe2O3 films (<10 nm) deposited on Pt by MO-CVD technique were measured under intermittent illumination of white Xe arc light at various electrode potentials in neutral Na2SO4 solutions. bode diagrams of the same film-solution systems were also measured over a wide frequency range in darkness and under continuous illumination. A fast photocurrent transient was observed in the iph vs. t curve immediately after the illumination; the photocurrent increased to a maximum value iph,t within 10 ms, and then decreased down to a stationary value iph,s. The iph,t, which was observed above 0.3 V, showed the maximum of ca. 1.5 A·m−2 at 1.0 V. The increase in iph,s occurred when the potential exceeded 0.8 V. Time-dependent changes in the transient photocurrent were very similar to those in the differentiated photopotential, showing that the intermittent illumination causes capacitance charging and discharging of the film. The bode diagrams showed the existence of surface-state with a large relaxation time (2 ms-1 s) at the film-solution interface and the increase in the capacitance of the surface-state with increasing potential and with illumination. From these results, it was thought that both the transient photocurrent and the photopotential arise from the displacement of charges in the space-charge layer of the film, which is attributed to the trapping and accumulation of photo-generated holes in the surface-state.
The human arm is a system of coupled mechanical oscillators. Its lowest resonance frequency coincides with the frequency of Parkinsonian tremor. In patients with Parkinson’s disease the pulse pattern of the nervous s...
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The human arm is a system of coupled mechanical oscillators. Its lowest resonance frequency coincides with the frequency of Parkinsonian tremor. In patients with Parkinson’s disease the pulse pattern of the nervous signal stimulating the muscles is pathologically shifted from 10 Hz in normals to lower frequencies and coincides then with the lowest and most dominant resonance frequency of the arm. The properties of the active muscular contraction add to the resonance effect of the passive arm mechanics. Both effects make the arm very sensitive to stimulations of about 5 Hz, thus leading to the high tremor amplitudes which characterize Parkinson’s disease.
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