scholarly journals Brass instruments as a cascade of two-port networks: Transfer functions, chain parameters, and power efficiency in theory and practice

2021 ◽  
Vol 149 (4) ◽  
pp. 2698-2710
Author(s):  
Wilfried Kausel ◽  
Alexander Mayer ◽  
James W. Beauchamp
Keyword(s):  
Power Efficiency ◽  
Transfer Functions ◽  
Theory And Practice ◽  
Brass Instruments

POWER SHELL ELEMENTS: DYNAMIC MATHEMATICAL MODELS, POWER SYSTEMS (OVERVIEW)

2021 ◽  
pp. 31-39
Author(s):  
Pavel P. Chernus ◽  
A. K. Arbiev ◽  
Petr P. Chernus ◽  
P. A. Loshitskiy ◽  
V. T. Sharovatov
Keyword(s):  
Power Systems ◽  
Mathematical Models ◽  
Gas Flow ◽  
Transfer Functions ◽  
Theory And Practice ◽  
Design Stage ◽  
Shell Elements ◽  
Advantages And Disadvantages ◽  
Working Medium ◽  
Compressed Gas

This article is a review devoted to the theory and practice of the application of power shell elements (PSE) in pneumatic drives (PD). She makes acquaint the reader with the main provisions of the theory of PD, performed on the PSE. The review briefly presents materials on the development of dynamic mathematical models (DMM) of power units (PU) of shell PDs (SPD), based on the use of static characteristics of SPD, an assessment of the advantages and disadvantages of PU based on traditional pneumatic cylinders (PC) and PSE is given. The main attention in the review is paid to the solution of the problem of creating PU on PSE with the required quality indicators at the design stage, when it is necessary to take into account the properties of compressed gas. For this, an original methodology for the development of nonlinear DMMs for various typical variants of the midrange is proposed, the basis of which is a number of provisions of the theory of gas dynamics. Without invoking this theory, it is impossible to ta into account the properties of compressed gas (compressibility of the working medium, dependence on temperature and gas flow rate in the shell, the nature of the gas expansion processes), and, therefore, to reliably describe the state of unsteady gas processes inside the shell and develop a DMM of the PU, to a sufficient taking into account the mentioned properties. Since the topic of this review is intended mainly for engineers who develop SPD (theoreticians and practitioners), the review also contains materials on the linearization of the found nonlinear DMMs. As a result of linearization, nonlinear DMMs are transformed into transfer functions for displacement of the output coordinate and effort. The correctness of the linearization carried out is confirmed by the results of experiments. The review briefly discusses several options for pneumatic supply systems for SPD. Here, of particular interest for a specialist is the material on imparting invariance properties to SPDs to air intake from the atmosphere nd discharge of exhaust air into the atmosphere, which significantly expands the scope of SPDs and reduce their cost.

scholarly journals Investigation and Study of Mode Splitting in Near Field Inductive Communication Systems

2013 ◽  
Vol 59 (2) ◽  
pp. 185-194 ◽  
Author(s):  
Hoa Doan Thanh ◽  
Johnson I. Agbinya
Keyword(s):  
Communication Systems ◽  
Power Efficiency ◽  
Transfer Functions ◽  
Near Field ◽  
Coupling Coefficients ◽  
Mode Splitting ◽  
Natural Response ◽  
Investigation And Study ◽  
Degree Of Coupling ◽  
Inductive Communication

Abstract Frequency splitting is a near field inductive communication phenomenon where the resonant frequency divides into many separate frequencies or to different modes. In this paper, we show that this phenomenon depends on the coupling coefficients or the natural response of the circuit by using the circuit theory to derive these splitting frequencies. Also, the rules for the general matrix that is used to solve for splitting frequencies are also demonstrated clearly. Mode splitting is observed for peer-to-peer, three coils and four coil systems due to the existence of the nearest and second neighbour interactions. In particular, two, three and four modes have been analysed for two, three, and four coil systems respectively. However, the number of modes for these systems can be changed according to the degree of coupling. The differences in the resultant splitting frequencies with and without the second neighbour interaction are shown in the simulation results. Furthermore, we assess the system performances regarding to power efficiency through the inductive transfer functions. Besides, either coupling coefficients at resonance or the simplified transfer functions in some specific scenarios can be obtained by having an insight into these transfer functions. Finally, we recognise and propose that splitting frequency phenomenon can be deployed to transmit signals at many frequencies concurrently.

POWER SHELL ELEMENTS: DYNAMIC MATHEMATICAL MODELS, POWER SYSTEMS (OVERVIEW) Continuation

2021 ◽  
pp. 36-43
Author(s):  
Pavel P. Chernus ◽  
A. K. Arbiev ◽  
Petr P. Chernus ◽  
P. A. Loshitskiy ◽  
V. T. Sharovatov
Keyword(s):  
Power Systems ◽  
Mathematical Models ◽  
Gas Flow ◽  
Transfer Functions ◽  
Theory And Practice ◽  
Design Stage ◽  
Shell Elements ◽  
Advantages And Disadvantages ◽  
Working Medium ◽  
Compressed Gas

This article is a review devoted to the theory and practice of the application of power shell elements (PSE) in pneumatic drives (PD). She makes acquaint the reader with the main provisions of the theory of PD, performed on the PSE. The review briefly presents materials on the development of dynamic mathematical models (DMM) of power units (PU) of shell PDs (SPD), based on the use of static characteristics of SPD, an assessment of the advantages and disadvantages of PU based on traditional pneumatic cylinders (PC) and PSE is given. The main attention in the review is paid to the solution of the problem of creating PU on PSE with the required quality indicators at the design stage, when it is necessary to take into account the properties of compressed gas. For this, an original methodology for the development of nonlinear DMMs for various typical variants of the midrange is proposed, the basis of which is a number of provisions of the theory of gas dynamics. Without invoking this theory, it is impossible to take into account the properties of compressed gas (compressibility of the working medium, dependence on temperature and gas flow rate in the shell, the nature of the gas expansion processes), and, therefore, to reliably describe the state of unsteady gas processes inside the shell and develop a DMM of the PU, to a sufficient taking into account the mentioned properties. Since the topic of this review is intended mainly for engineers who develop SPD (theoreticians and practitioners), the review also contains materials on the linearization of the found nonlinear DMMs. As a result of linearization, nonlinear DMMs are transformed into transfer functions for displacement of the output coordinate and effort. The correctness of the linearization carried out is confirmed by the results of experiments. The review briefly discusses several options for pneumatic supply systems for SPD. Here, of particular interest for a specialist is the material on imparting invariance properties to SPDs to air intake from the atmosphere and discharge of exhaust air into the atmosphere, which significantly expands the scope of SPDs and reduce their cost.

Impact of time misalignment and input signal statistics in dynamically load-modulated amplifiers

2015 ◽  
Vol 7 (3-4) ◽  
pp. 327-337 ◽  
Author(s):  
Konstantinos Mimis ◽  
Gavin Tomas Watkins
Keyword(s):  
Output Power ◽  
Input Signal ◽  
Power Efficiency ◽  
High Efficiency ◽  
Supply Voltage ◽  
Amplitude Distribution ◽  
Network Control ◽  
Theory And Practice ◽  
Average Output ◽  
The Impact

The effect of time misalignment between the radiofrequency (RF) input and tunable matching network control signal in dynamically load-modulated power amplifiers (Pas) is investigated in theory and practice. Moreover, the impact of different input signal statistics is considered. A simple amplifier model is used for the study, based on which the impact on output power, efficiency, and linearity is explored with various generic multi-tone signals. Furthermore, to experimentally verify the results, a 10 W dynamically load-modulated RF PA is measured. As expected, proper synchronization of the signals is crucial, especially as channel bandwidth increases. Additionally, it is shown that the input signal characteristics, such as the amplitude distribution, are important. Moreover, the prototype RF PA is measured with a 1.4 MHz long-term evolution (LTE) signal delivering an average output power of 33.9 dBm with 46% efficiency. Finally, high efficiency and linearity is maintained over output power by scaling the drain supply voltage.

A simple way for producing holographic filters suitable for image improvement

1978 ◽  
Vol 36 (1) ◽  
pp. 226-227
Author(s):  
K.-H. Herrmann ◽  
E. Reuber ◽  
P. Schiske
Keyword(s):  
Transfer Functions ◽  
Diffraction Order ◽  
Lateral Position ◽  
Simple Method ◽  
Spatial Frequencies ◽  
Resolution Electron ◽  
Wiener Filters ◽  
Image Improvement ◽  
Optical Reconstruction ◽  
Set Up

Aposteriori deblurring of high resolution electron micrographs of weak phase objects can be performed by holographic filters [1,2] which are arranged in the Fourier domain of a light-optical reconstruction set-up. According to the diffraction efficiency and the lateral position of the grating structure, the filters permit adjustment of the amplitudes and phases of the spatial frequencies in the image which is obtained in the first diffraction order.In the case of bright field imaging with axial illumination, the Contrast Transfer Functions (CTF) are oscillating, but real. For different imageforming conditions and several signal-to-noise ratios an extensive set of Wiener-filters should be available. A simple method of producing such filters by only photographic and mechanical means will be described here.A transparent master grating with 6.25 lines/mm and 160 mm diameter was produced by a high precision computer plotter. It is photographed through a rotating mask, plotted by a standard plotter.

Analytic integration of contrast transfer functions

1988 ◽  
Vol 46 ◽  
pp. 822-823
Author(s):  
Peter Rez
Keyword(s):  
Wave Function ◽  
Transfer Function ◽  
Transfer Functions ◽  
Spherical Aberration ◽  
Continuous Distribution ◽  
Objective Lens ◽  
Direction Parallel ◽  
Scattering Angle ◽  
Analytic Integration ◽  
Image Position

In high resolution microscopy the image amplitude is given by the convolution of the specimen exit surface wave function and the microscope objective lens transfer function. This is usually done by multiplying the wave function and the transfer function in reciprocal space and integrating over the effective aperture. For very thin specimens the scattering can be represented by a weak phase object and the amplitude observed in the image plane is1where fe (Θ) is the electron scattering factor, r is a postition variable, Θ a scattering angle and x(Θ) the lens transfer function. x(Θ) is given by2where Cs is the objective lens spherical aberration coefficient, the wavelength, and f the defocus.We shall consider one dimensional scattering that might arise from a cross sectional specimen containing disordered planes of a heavy element stacked in a regular sequence among planes of lighter elements. In a direction parallel to the disordered planes there will be a continuous distribution of scattering angle.

Electron Holography Improving Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 208-209
Author(s):  
Hannes Lichte
Keyword(s):  
Electron Microscopy ◽  
Transfer Functions ◽  
Imaging System ◽  
Spherical Aberration ◽  
Image Plane ◽  
Chromatic Aberration ◽  
Object Wave ◽  
Objective Lens ◽  
Electron Holography ◽  
Wave Aberration

Generally, the electron object wave o(r) is modulated both in amplitude and phase. In the image plane of an ideal imaging system we would expect to find an image wave b(r) that is modulated in exactly the same way, i. e. b(r) =o(r). If, however, there are aberrations, the image wave instead reads as b(r) =o(r) * FT(WTF) i. e. the convolution of the object wave with the Fourier transform of the wave transfer function WTF . Taking into account chromatic aberration, illumination divergence and the wave aberration of the objective lens, one finds WTF(R) = Echrom(R)Ediv(R).exp(iX(R)) . The envelope functions Echrom(R) and Ediv(R) damp the image wave, whereas the effect of the wave aberration X(R) is to disorder amplitude and phase according to real and imaginary part of exp(iX(R)) , as is schematically sketched in fig. 1.Since in ordinary electron microscopy only the amplitude of the image wave can be recorded by the intensity of the image, the wave aberration has to be chosen such that the object component of interest (phase or amplitude) is directed into the image amplitude. Using an aberration free objective lens, for X=0 one sees the object amplitude, for X= π/2 (“Zernike phase contrast”) the object phase. For a real objective lens, however, the wave aberration is given by X(R) = 2π (.25 Csλ3R4 + 0.5ΔzλR2), Cs meaning the coefficient of spherical aberration and Δz defocusing. Consequently, the transfer functions sin X(R) and cos(X(R)) strongly depend on R such that amplitude and phase of the image wave represent only fragments of the object which, fortunately, supplement each other. However, recording only the amplitude gives rise to the fundamental problems, restricting resolution and interpretability of ordinary electron images:

The Effect of Nonlinear Amplitude Growth on the Speech Perception Benefits Provided by a Single-Sided Vocoder

2019 ◽  
Vol 62 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Jessica M. Wess ◽  
Joshua G. W. Bernstein
Keyword(s):  
Transfer Functions ◽  
Spatial Configuration ◽  
Free Field ◽  
Spatial Separation ◽  
Compression And Expansion ◽  
Interaural Difference ◽  
Interaural Differences ◽  
Single Sided Deafness ◽  
Perceptual Separation ◽  
Loudness Growth

PurposeFor listeners with single-sided deafness, a cochlear implant (CI) can improve speech understanding by giving the listener access to the ear with the better target-to-masker ratio (TMR; head shadow) or by providing interaural difference cues to facilitate the perceptual separation of concurrent talkers (squelch). CI simulations presented to listeners with normal hearing examined how these benefits could be affected by interaural differences in loudness growth in a speech-on-speech masking task.MethodExperiment 1 examined a target–masker spatial configuration where the vocoded ear had a poorer TMR than the nonvocoded ear. Experiment 2 examined the reverse configuration. Generic head-related transfer functions simulated free-field listening. Compression or expansion was applied independently to each vocoder channel (power-law exponents: 0.25, 0.5, 1, 1.5, or 2).ResultsCompression reduced the benefit provided by the vocoder ear in both experiments. There was some evidence that expansion increased squelch in Experiment 1 but reduced the benefit in Experiment 2 where the vocoder ear provided a combination of head-shadow and squelch benefits.ConclusionsThe effects of compression and expansion are interpreted in terms of envelope distortion and changes in the vocoded-ear TMR (for head shadow) or changes in perceived target–masker spatial separation (for squelch). The compression parameter is a candidate for clinical optimization to improve single-sided deafness CI outcomes.

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