Messeinrichtung für Wechselspannungen und Phasenverschiebungswinkel im Frequenzbereich 0,3Hz bis 50kHz Instrumentation for the Measurement of Alternating Voltage and Angle of Phase Difference in the Frequency Range 0.3Hz to 50kHz

2008 ◽  
Vol 75 (9) ◽  
Author(s):  
Uwe Bühn
Keyword(s):  
Phase Difference ◽  
Frequency Range ◽  
Alternating Voltage

scholarly journals Design of Compact BranchlineBalun

2020 ◽  
Author(s):  
Indhumathi J ◽  
Maheswari S
Keyword(s):  
Dielectric Constant ◽  
Phase Difference ◽  
Transmission Lines ◽  
Substrate Material ◽  
Size Reduction ◽  
Frequency Range ◽  
Branch Line ◽  
Reduction Techniques ◽  
Shape Structure ◽  
Phase Differences

This paper present the compact branch line balun to operate at the frequency range of 2.4GHz. The compact branchlinebalun is designed using the substrate material with the dielectric constant of FR4 material. The proposed balun is designed using different transmission lines. Thus the balun should achieves -3dB power division and 1800 phase differences between the outputs. The main objective of this design focuses on size reduction. To reduce the size, A balun is realized using the equivalent T-shape structure. After the reduction techniques the implemented size of the balun is 29.41x44.32 mm2 achieves 35% of size reduction. Thus the measured S11 are -23 dB and the S21,S31 remains -3dB and provide 1790 phase difference between the outputs at the frequency of 2.4GHz.

Phase dynamics in cerebral autoregulation

2005 ◽  
Vol 289 (5) ◽  
pp. H2272-H2279 ◽  
Author(s):  
Miroslaw Latka ◽  
Malgorzata Turalska ◽  
Marta Glaubic-Latka ◽  
Waldemar Kolodziej ◽  
Dariusz Latka ◽  
...  
Keyword(s):  
Uniform Distribution ◽  
Phase Difference ◽  
Wavelet Transforms ◽  
Low Frequency ◽  
Cerebral Hemodynamics ◽  
Healthy Individuals ◽  
Frequency Range ◽  
Phase Dynamics ◽  
Very Low Frequency ◽  
Arterial Blood

Complex continuous wavelet transforms are used to study the dynamics of instantaneous phase difference Δφ between the fluctuations of arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV) in a middle cerebral artery. For healthy individuals, this phase difference changes slowly over time and has an almost uniform distribution for the very low-frequency (0.02–0.07 Hz) part of the spectrum. We quantify phase dynamics with the help of the synchronization index γ = 〈sinΔφ〉2 + 〈cosΔφ〉2that may vary between 0 (uniform distribution of phase differences, so the time series are statistically independent of one another) and 1 (phase locking of ABP and CBFV, so the former drives the latter). For healthy individuals, the group-averaged index γ has two distinct peaks, one at 0.11 Hz [γ = 0.59 ± 0.09] and another at 0.33 Hz (γ = 0.55 ± 0.17). In the very low-frequency range (0.02–0.07 Hz), phase difference variability is an inherent property of an intact autoregulation system. Consequently, the average value of the synchronization parameter in this part of the spectrum is equal to 0.13 ± 0.03. The phase difference variability sheds new light on the nature of cerebral hemodynamics, which so far has been predominantly characterized with the help of the high-pass filter model. In this intrinsically stationary approach, based on the transfer function formalism, the efficient autoregulation is associated with the positive phase shift between oscillations of CBFV and ABP. However, the method is applicable only in the part of the spectrum (0.1–0.3 Hz) where the coherence of these signals is high. We point out that synchrony analysis through the use of wavelet transforms is more general and allows us to study nonstationary aspects of cerebral hemodynamics in the very low-frequency range where the physiological significance of autoregulation is most strongly pronounced.

scholarly journals Design of a Low Scattering Metasurface for Stealth Applications

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3031 ◽  
Author(s):  
Tayyab Ali Khan ◽  
Jianxing Li ◽  
Juan Chen ◽  
Muhammad Usman Raza ◽  
Anxue Zhang
Keyword(s):  
Cross Section ◽  
Phase Difference ◽  
Metallic Plate ◽  
Frequency Range ◽  
Magnetic Conductor ◽  
Relative Bandwidth ◽  
Good Accordance ◽  
Unit Cells ◽  
Effective Phase ◽  
Phase Reflection

The design of a metasurface with low radar cross section (RCS) property is presented in this paper. The low scattering of the metasurface is achieved by applying the artificial magnetic conductor (AMC) unit cells in three different configurations. Two different AMC unit cells with an effective phase difference of 180 ± 37° are first designed to analyze the out of phase reflection in a wideband frequency range from 5.9 to 12.2 GHz. Then, the unit cells are placed in a chessboard-like configuration, newly constructed rotated rectangular-shaped configuration, and optimized configuration to study and compare the RCS reduction performance. All designs of the metasurface with different configurations show obvious RCS reduction as compared with the metallic plate of the same size. However, the relative bandwidth of the optimized metasurface is larger than the chessboard-like configuration and rotated rectangular-shaped configuration. To certify the results of the simulations, the metasurface with the optimized configuration is fabricated further to measure the RCS reduction bandwidth. The measured results are in good accordance with the simulated results. Therefore, the proposed metasurface can be a good option for applications where low RCS is desirable.

Special Government Standard of unit alternating voltage within the 20?3�107-Hz frequency range

1976 ◽  
Vol 19 (3) ◽  
pp. 387-390 ◽  
Author(s):  
T. B. Rozhdestvenskaya ◽  
R. F. Aknaev ◽  
O. P. Galakhova
Keyword(s):  
Frequency Range ◽  
Government Standard ◽  
Special Government Standard ◽  
Alternating Voltage

Coupled Piezoelectric Phononic Crystal for Adaptive Broadband Wave Attenuation by Destructive Interference

2020 ◽  
Vol 87 (9) ◽  
Author(s):  
Jiawen Xu ◽  
Xin Zhang ◽  
Ruqiang Yan
Keyword(s):  
Phase Difference ◽  
Wave Attenuation ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Crystal Plate ◽  
Destructive Interference ◽  
Negative Capacitance ◽  
Frequency Range ◽  
Frequency Wave ◽  
Unit Cells

Abstract In this paper, we report a piezoelectric phononic crystal plate featuring broadband wave attenuation. In the piezoelectric phononic crystal system, the transmitted elastic wave is attenuated owing to destructive interference by taking advantages of phase difference. The proposed concept is applied to a piezoelectric phononic crystal plate synthesized by functional dual-lane units that yields phase difference. Whereas, the piezoelectric unit-cells are connected negative capacitance shunt circuits individually. Our analysis shows that the coupled phononic crystal has a strong broadband low-frequency wave attenuation capability. The bandwidth of 10 dB wave attenuation is broadened by 34 times in the vicinity of 5 kHz comparing to that of a local resonance metamaterial under the same mechanical configuration. Moreover, the frequency range of wave attenuation of the proposed system can be online adjusted through the modification of the external shunt circuits.

Wide-Band Planar Balun Based on Simplified Composite Right-Left-Handed Structure

2014 ◽  
Vol 488-489 ◽  
pp. 1043-1046
Author(s):  
Li Zhu ◽  
Xiang Jun Gao ◽  
Hui Yong Zeng ◽  
Guang Ming Wang
Keyword(s):  
Phase Difference ◽  
Frequency Band ◽  
Phase Shifter ◽  
Wide Band ◽  
Experimental Results ◽  
Power Divider ◽  
Operating Frequency ◽  
Frequency Range ◽  
Operating Frequency Band ◽  
Left Handed

Wide-band planar microstrip balun implemented with simplified composite right/left-handed (SCRLH) structure is presented in this letter. The proposed balun consists of a wide-band Wilkinson power divider and a broadband 180° phase shifter based on SCRLH structure. The new design was simulated and validated by the measurement. In the experimental results, within the frequency range from 3.1 to 8.3 GHz (91.2%), the measured return losses of the unbalanced and balanced ports are greater than 10 dB, and the balanced ports isolation is below 15 dB. The measured amplitude and phase difference between the two balanced ports are within ±0.6 dB and ±50, respectively, over the operating frequency band.

Density-based discrimination of protein and RNA in the ribosome

1992 ◽  
Vol 50 (1) ◽  
pp. 464-465
Author(s):  
Joachim Frank
Keyword(s):  
Transfer Function ◽  
Spatial Frequency ◽  
Three Dimensional ◽  
Wiener Filter ◽  
Dark Field Image ◽  
Dark Field ◽  
Frequency Range ◽  
Bright Field ◽  
Contrast Transfer Function ◽  
Pass Filter

Cryo-electron microscopy combined with single-particle reconstruction techniques has allowed us to form a three-dimensional image of the Escherichia coli ribosome.In the interior, we observe strong density variations which may be attributed to the difference in scattering density between ribosomal RNA (rRNA) and protein. This identification can only be tentative, and lacks quantitation at this stage, because of the nature of image formation by bright field phase contrast. Apart from limiting the resolution, the contrast transfer function acts as a high-pass filter which produces edge enhancement effects that can explain at least part of the observed variations. As a step toward a more quantitative analysis, it is necessary to correct the transfer function in the low-spatial-frequency range. Unfortunately, it is in that range where Fourier components unrelated to elastic bright-field imaging are found, and a Wiener-filter type restoration would lead to incorrect results. Depending upon the thickness of the ice layer, a varying contribution to the Fourier components in the low-spatial-frequency range originates from an “inelastic dark field” image. The only prospect to obtain quantitatively interpretable images (i.e., which would allow discrimination between rRNA and protein by application of a density threshold set to the average RNA scattering density may therefore lie in the use of energy-filtering microscopes.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

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