Doppler effect in the ripple tank: further experiments with a moving source

We conducted a timing analysis of PSR J0922+0638 (B0919+06) using data from the Nanshan 26 m radio telescope and the MeerKAT telescope, spanning from 2001 January to 2023 March. During this 22 yr period, we discovered a previously unreported small glitch (glitch 1) before the well-known large glitch (glitch 2), occurring at MJD ∼ 53325(3), with a frequency jump amplitude of Δν/ν ∼ 0.79(6) × 10−9. We also identified 10 slow glitch events, half of which were newly detected. These slow glitches occurred quasi-periodically, with an average interval of approximately 553(21) days, fractional frequency changes ranging from Δν/ν ∼ 1.13(1) × 10−9 to 4.08(5)×10−9, and a maximum fractional change in the first derivative of the frequency of Δ ν ̇ / ν ̇ ∼ − 4.6 × 1 0 − 3 . Additionally, our timing noise analysis reveals a change in the spectral index for noise power before and after glitch 2, with values of −6.0 and −5.3, respectively, likely due to this large glitch. Throughout the entire observation period, the first derivative of the spin frequency ( ν ̇ ) showed a periodic structure. The possible modulation period was estimated to be 537(24) days before the 700 days data gap at MJD 56716 and 600(58) days afterward. We discuss the periodic oscillations in pulsar rotation as a possible manifestation of spin-down noise and quasi-periodic slow glitches.

Ultrasound anomaly at T c in YBa 2Cu 3O y

Dielectric resonator oscillators operating at 1.5 and 2.0 GHz, based on a two-port resonator design incorporated into a basic feedback oscillator configuration were evaluated and show state-of-the-art, close-to-carrier phase noise performance. Typically, at 1 KHz carrier offset frequency the single sideband phase noise levels were -130 dBc/Hz and -120 dBc/Hz for the 1.5 GHz and 2.0 GHz oscillators, respectively. Vibration sensitivity was also investigated and the resonators show fractional frequency changes per g in the range of 10/sup -7/ to 10/sup -9/ for the 1.5 GHz and 2.0 GHz designs, respectively.

The aim of this study was to determine the effect of the COVID-19 pandemic on changes in eating habits is a quantitative study with a cross-sectional design conducted in Bogor with 110 respondents. Changes in eating habits observed include changes in eating frequency, meal portions, frequency of fruit consumption, frequency of vegetable consumption, frequency of snack consumption, frequency of consumption of fast food/frozen food, and consumption of supplements. Respondents were more women (83,6%), adult age group (89,1%), higher education (79,1%), work (61,8%), income > IDR 4,000,000 (75,5%). The results of the univariate analysis related to changes in eating habits consist of: changes in eating frequency (69,1%), changes in food portions (56,4%), changes in fruit consumption frequency (61,8% more often), changes in vegetable consumption frequency (63,6% more often), changes in the frequency of snack consumption (more often 74,5%), changes in the frequency of consumption of fast food/frozen food (more often 70%) and consumption of supplements (90,9%). The results of the bivariate analysis are showed that changes in eating frequency were significantly related to income; changes in meal portions were significantly related to education and expenditure; changes in the frequency of vegetable consumption are significantly related to income; changes in snack consumption frequency were significantly related to age, gender, occupation; changes in the frequency of consumption of fast food are significantly related to gender and consumption of supplements was significantly related to age. Suggestions for the research are needed to consistently educate about good and correct food habits so that more people understand and apply them to increase immunity and data collection will be better with direct interviews and fill out the FFQ of the food consumed.

The frequency change in internal gravity waves upon scattering from a rough topography is investigated analytically. For this, sets of appropriate and tractable governing equations for various parameter regimes are derived using the method of multiple scales under the assumption that the amplitude of the bottom topography is small. A solution is shown for a simple case in which an incident internal wave is approximately linear and monochromatic. The solution has the following features: the intrinsic frequencies of the scattered waves are given as the sum and difference of the incident-wave frequency and the Doppler shift (or lee-wave frequency). This Doppler shift causes the change in the frequency. Hence, the assumption of frequency conservation is not valid if the Doppler shift is significant, that is, when the horizontal scale of the bottom roughness (or the length scale in the plane of the slope) is on the order of or much less than that of the incident-wave flow excursion. This condition can be satisfied in a realistic parameter range. The occurrence of such a frequency change has the following implications: first, it affects the estimate of the boundary mixing induced by the scattering because the energy redistribution in the vertical wavenumber space on scattering differs from that estimated using the assumption of frequency conservation. This effect happens because for a given horizontal wavenumber, the change in the frequency alters the vertical wavenumber of the scattered waves through the dispersion relation. Furthermore, if the incident waves are not monochromatic, even the leading-order scattered waves cannot be obtained by the superposition of the solutions for all the Fourier components of the incident waves because of the difference in the Doppler shift. Second, the effects of the background flow associated with the incident and primary reflected waves are significant when the frequency change occurs such that the background flow can create a critical level and/or advect scattered waves. The former causes mixing and background-flow acceleration, and the latter is favorable for the amplification of the scattered waves through superposition. Third, the resulting energy redistribution in frequency space could modify the spectrum shape of the oceanic internal waves, which is considered to affect both interior and boundary mixing.

To determine the relative status of the damaged floors of a building after an earthquake using building modal characteristics, instrumentation of the building is not required throughout its lifetime. In this paper, comparison of neural networks accuracy trained with fractional frequency change and mode shape change obtained from combination of three, four and five damage levels of different storeys of the building is evaluated. The network trained with combination of three damage levels of four and eight storey building is incapable of giving acceptable results. However, for four-storey building, network trained with four damage levels predicted good results and networks trained with five damage levels predicted excellent results. For eight-storied building, network trained with four damage levels gave acceptable results for storey level damage. The accuracy of damage severity, decrease with the increased number of building storey.

The Doppler effect in NMR spectroscopy

The ocean is transparent to sound and nearly opaque to electromagnetic radiation. Remote sensing of processes in the ocean interior therefore depends in large measure on acoustic techniques. Measurements of travel times, Doppler shifts, and intensity fluctuations of probe signals transmitted through the ocean or backscattered from it yield information on ocean temperature and current fields, surface and internal waves, and fauna and other particulates that scatter acoustic signals. The study of acoustic sound generated by natural processes yields information on wind, rain, surface waves, ice, whales and other fauna, and undersea earthquakes and volcanic eruptions. Currently active and exciting research areas include: (i) the study of ocean surface processes using scattered and ambient sound, (ii) acoustic global ocean monitoring of ocean temperature, (iii) Arctic acoustics, including the study of ice dynamics using ambient sound, (iv) acoustic measurement of ocean structure at a variety of scales, and (v) biological acoustics.

In this study we describe laser Doppler measurements on scattering liquids flowing through a highly scattering static medium to determine the scattering coefficient and the anisotropy factor of the liquids. Monte Carlo simulations of light propagation in the static and moving media were used to calculate the Doppler spectra. We show that the scattering coefficient of liquids can be derived from the integration of the Doppler spectrum provided that the absorption coefficient of the liquid is much smaller than the scattering coefficient. The anisotropy factor was deduced by applying an iterative nonlinear regression method to fit the measured Doppler spectra. The experimental setup was tested by comparing laser Doppler measurements on polystyrene spheres with Monte Carlo simulations. Finally, the scattering properties of dilute Intralipid20% and those of blood were determined at λ = 820 nm.

Hospital surveillance for infection control purposes is a well-accepted method of following nosocomial infections in U.S. hospitals. However, hospital surveillance is being increasingly performed for nosocomial events in noninfectious areas, such as quality assurance and other areas of outcomes research. For the continued development of hospital surveillance in all these areas, dramatic growth in the amount of information collected will occur. To accommodate this growth and to validate new approaches in these areas, large amounts of data collection will be necessary. Collection of these data will be quite difficult without the creation of clinical hospital data bases in which large amounts of information are collected as a routine part of patient care, not as an elaborate addition to patient care. Automated hospital information systems, such as the HELP system, can facilitate the conduct of ongoing hospital surveillance not only in infection control but also in a broad range of areas, such as quality improvement outcomes research and cost-containment areas.

The velocity potentials of a point source moving at a constant velocity in the upper layer of a two-layer fluid are obtained in a form amenable to numerical integration. Each fluid layer is of finite depth, and the density difference between the two layers is not necessarily small. The far-field asymptotic behavior of the surface waves and internal waves are also derived using the method of stationary phase. They show that the wave system at the free surface or at the interface each contains contributions from two different modes: a surface-wave mode and an internal-wave mode. When the density difference between the two layers is small or the depth of the upper layer is large, the surface-wave mode mainly affects the surface waves while the internal-wave mode mainly affects the internal waves. However, for large density difference, both modes contribute to the surface wave or internal wave system. For each mode, both divergent and transverse waves are present if the total depth Froude number is less than a certain critical Froude number which is mode-dependent. For depth Froude number greater than the critical Froude number, only divergent waves exist for that mode. This classification is similar to that of a uniform fluid of finite depth, where the critical Froude number is simply unity. The surface waves and internal waves are also calculated using the full expressions of the source potentials. They further confirm and illustrate the features observed in the asymptotic analysis.

Bridge vibration frequency is a measure of the overall state and structural damage will inevitably lead to changes in frequency. Based on this approach, we realized the bridge health monitoring system, introduced the bridge health monitoring system design approach, the data collection process and data analysis. Test proved that the vibration frequency of the bridge on the health status of the bridge. By the system design process and experimental results, from the experimental point of view, we can assess the overall state of the bridge model. Through this test, we can carry out health monitoring of bridge large-scale structures. It is important to bridge health monitoring.

Years ago, just by thinking about it, we discovered the rate of a unit clock in a gravitational field, and, after that, because of the slower clock rate in a gravitational field, that the energy that an energy wave sphere loses becomes its energy of motion. We calculated the radius of a proton energy wave sphere contained in an electron energy wave sphere. We extend the concept of energy wave spheres to imaginary energy wave spheres to explain the change in frequency of the wave in an energy wave sphere. We show that a black hole is an imaginary energy wave sphere with radius alpha and wave velocity ic, which gives the nature of the kernel with radius alpha of a mass M. We show that the radial component of the velocity of a light ray, perpendicular to a radius in a gravitational field, has the velocity of an imaginary energy wave sphere inside the photon. We did not come here to offer a false theory, but, rather, a look through the veil of gravitation. We are the looking glass. A light ray with constant velocity -c moving toward the imaginary kernel of a mass M along a radius has a real energy wave sphere with wave velocity 0 always. In the face of imaginary energy wave spheres along its path, the wave velocity of the energy wave sphere never becomes imaginary assuming any energy lost by the wave goes into the velocity of the energy wave sphere. Taking this non-imaginary wave velocity clue amounts to assuming it holds for all real energy wave spheres and, as a consequence, that the absolute velocity of a real energy wave sphere cannot exceed c. Knowing that the source of this velocity is the energy wave sphere itself, we should have already concluded this anyway. As for a real kernel for the mass M for some radius less than alpha, no real energy wave sphere has an imaginary energy wave sphere to hold it together for such a radius. The only conceivable place to match the wave velocity of the real kernel of a mass M, where the wave velocity of the kernel is c and the velocity of the energy wave sphere, not its wave velocity, is -c, is at the radius alpha, thus extending the notion of a black hole to include this real energy wave sphere.

One procedure widely used to detect the velocity of a moving object is by using the Doppler effect. This is the perceived change in frequency of a wave caused by the relative motion between the emitter and the detector, or between the detector and a reflecting target. The relative movement, in turn, generates a time-varying phase which translates into the detected frequency shift. The classical longitudinal Doppler effect is sensitive only to the velocity of the target along the line-of-sight between the emitter and the detector (longitudinal velocity), since any transverse velocity generates no frequency shift. This makes the transverse velocity undetectable in the classical scheme. Although there exists a relativistic transverse Doppler effect, it gives values that are too small for the typical velocities involved in most laser remote sensing applications. Here we experimentally demonstrate a novel way to detect transverse velocities. The key concept is the use of structured light beams. These beams are unique in the sense that their phases can be engineered such that each point in its transverse plane has an associated phase value. When a particle moves across the beam, the reflected light will carry information about the particle's movement through the variation of the phase of the light that reaches the detector, producing a frequency shift associated with the movement of the particle in the transverse plane.

Ice formation on an aircraft can cause serious safety problems, and hence, there is a real need for ice detection and monitoring on aircrafts. It is well known that acoustic wave devices offer a simple and inexpensive technique for a number of sensing applications. In this paper, we present a wireless ice detection and monitoring system using a surface acoustic wave (SAW) device utilizing shear horizontal (SH) waves as the sensing mechanism. The SAW device is designed and fabricated on a quartz substrate. Silicon dioxide is then deposited to serve as a guiding layer for SH waves. The acoustic wave concentrated in the guiding layer is highly sensitive to surface perturbations. The experimental setup used to measure the effect of ice formation is by an oscillator setup. The SAW device is designed to oscillate at a particular frequency and any fractional change in wave velocity due to surface perturbations leads to a change in oscillation frequency. It is observed that phase transformation from water to ice causes a shift in oscillator frequency of 2 MHz. The ice sensor can be operated wirelessly by connecting the SAW sensor to a stand-alone oscillator and the oscillator can communicate with a remote monitoring system using a microstrip antenna.