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Due to the fact that, excessive stresses induced by drastic moisture and temperature gradients make the engineering structures susceptible to failure. But only thermal effect has been considered so far to study the frequency analysis of FGM nanobeams, wherein most of the cases some rule of mixture were used to grade the mechanical properties along certain directions. It has been observed from the literature that the interfacial stresses arise which is the main cause of failure of composite structures is reduced up to an extent if the mechanical constants are varying under sigmoid law formulation. Hence, this paper reported the frequency behavior of functionally graded nanobeam under hygrothermal effect, where the mechanical constants are assumed to vary smoothly along the thickness direction using power law or sigmoid law distribution. The MUMPS Eigen solver which is exists in COMSOL Multiphysics® (version 5.2) software is employed to obtain the Eigenfrequencies and corresponding mode shapes. Hence, this study can be helpful directly or indirectly in development of highly efficient hygrothermal Nano sensors based on functionally graded materials for health monitoring purpose.

The transient heat transfer process is studied in rarefied gas argon (Ar) confined between two stationary concentric cylinders. The inner cylinder (filament) is subjected to a periodically heating-cooling cycle. The energy transfer is modeled with continuous model based on Navier-Stokes-Fourier equations of motion and energy transfer and with a statistical Direct Simulation Monte Carlo model. Numerically is analyzed the operation of the Micro Mechanical-Electro System (MEMS) pulsating Pirani gauge at the real-time frequencies. The actual read pressure (pressure difference) variation is studied. The results can be used to analyze the pulsating Pirani gauge sensitivity, i.e., the time to reach sustained oscillations as well as to adjust the pressure reading to the actual value.

Extreme rainfall may cause problems to the social, environmental and ecology. In this paper, we focused on regional frequency analysis of extremes rainfall based on 3-hourly rainfall records by TRMM 3B42 and raingauge data between 1998-2012 at 30 stations of Peninsular Malaysia, Malaysia. Based on the L-Moments method, we developed the regional extreme rainfall frequency analysis in measuring discordancy, regional homogeneity and the goodness-of-fit test to determine the best regional parent distribution. The Wards method is presented to identify the homogenous regions in Peninsular Malaysia and produce 4 acceptably homogeneous regions that had been tested by the L-Moments method. The results show that the L-Moments method is good in term of performance, simplicity and robustness.

Prior knowledge in pervasive computing recently garnered a lot of attention due to its high demand in various application domains. Human activity recognition (HAR) considered as the applications that are widely explored by the expertise that provides valuable information to the human. Accelerometer sensor-based approach is utilized as devices to undergo the research in HAR since their small in size and this sensor already build-in in the various type of smartphones. However, the existence of high inter-class similarities among the class tends to degrade the recognition performance. Hence, this work presents the method for activity recognition using our proposed features from combinational of spectral analysis with statistical descriptors that able to tackle the issue of differentiating stationary and locomotion activities. The noise signal is filtered using Fourier Transform before it will be extracted using two different groups of features, spectral frequency analysis, and statistical descriptors. Extrac...

An approach for the analysis of the frequency content of structural vibrations from high-speed video recordings is proposed. The techniques and tools proposed rely on an Eulerian approach, that is, using the time history of pixels independently to analyse structural motion, as opposed to Lagrangian approaches, where the motion of the structure is tracked in time. The starting point is an existing Eulerian motion magnification method, which consists in decomposing the video frames into a set of spatial scales through a so-called Laplacian pyramid [1]. Each scale — or level — can be amplified independently to reconstruct a magnified motion of the observed structure. The approach proposed here provides two analysis tools or pre-amplification steps. The first tool provides a representation of the global frequency content of a video per pyramid level. This may be further enhanced by applying an angular filter in the spatial frequency domain to each frame of the video before the Laplacian pyramid decomposition, which allows for the identification of the frequency content of the structural vibrations in a particular direction of space. This proposed tool complements the existing Eulerian magnification method by amplifying selectively the levels containing relevant motion information with respect to their frequency content. This magnifies the displacement while limiting the noise contribution. The second tool is a holographic representation of the frequency content of a vibrating structure, yielding a map of the predominant frequency components across the structure. In contrast to the global frequency content representation of the video, this tool provides a local analysis of the periodic gray scale intensity changes of the frame in order to identify the vibrating parts of the structure and their main frequencies. Validation cases are provided and the advantages and limits of the approaches are discussed. The first validation case consists of the frequency content retrieval of the tip of a shaker, excited at selected fixed frequencies. The goal of this setup is to retrieve the frequencies at which the tip is excited. The second validation case consists of two thin metal beams connected to a randomly excited bar. It is shown that the holographic representation visually highlights the predominant frequency content of each pixel and locates the global frequencies of the motion, thus retrieving the natural frequencies for each beam.

In this paper the existence of the corner frequency value for the seismic moment distribution is investigated, analysing worldwide data. Pareto based distributions, usually considered as the most suitable to this type of data, are fitted to the most recent data, available in a global earthquake catalog. Despite the undeniable finite nature of the seismic moment data, we conclude that no corner frequency can be established considering the available data set.

Depth sizing of intergranular attack (IGA) with conventional eddy-current analysis is difficult, and typically gives results of poor accuracy. This paper presents a sizing technique using multi-frequency analysis for bobbin probe and X-Probe eddy-current data, along with a case study of outer-surface IGA in 0.510" (12.95 mm) diameter, 0.044" (1.12 mm) wall Alloy 600 tubing. A mathematical framework for the expected eddy-current phase and amplitude response is provided. Using this formulation, eddy-current amplitude and phase responses at four inspection frequencies are calculated, and compared to the corresponding measured responses. IGA flaw geometry is approximated through the optimization of flaw parameters via a least-squares minimization of the residual from the comparison.

The surface shape and the absolute optical thickness of a fused-silica glass parallel plate were measured by wavelength tuning interferometry. An excess fractions method combined with the Fourier based frequency analysis removed a systematic error. The interference orders of the optical thickness fringes were finally estimated, which resulted in an accuracy of a few nanometers for the optical thickness measurement.

It has been suggested that the detection of a wealth of very low amplitude modes in Delta Sct stars was only a matter of signal--to--noise ratio. Access to this treasure, impossible from the ground, is one of the scientific aims of the space mission CoRoT, developed and operated by CNES. This work presents the results obtained on HD 50844: the 140,016 datapoints allowed us to reach the level of 10^{-5} mag in the amplitude spectra. The frequency analysis of the CoRoT timeseries revealed hundreds of terms in the frequency range 0--30 d^{-1}. The initial guess that Delta Sct stars have a very rich frequency content is confirmed. The spectroscopic mode identification gives theoretical support since very high--degree modes (up to ell=14) are identified. We also prove that cancellation effects are not sufficient in removing the flux variations associated to these modes at the noise level of the CoRoT measurements. The ground--based observations indicate that HD 50844 is an evolved star that is slightly underabundant in heavy elements, located on the Terminal Age Main Sequence. The predominant term (f_1=6.92 d^{-1}) has been identified as the fundamental radial mode combining ground-based photometric and spectroscopic data. This work is based on observations made with ESO telescopes under the Large Programme LP 178.D-0361., Comment: Proceedings of the International Conference "Stellar Pulsation: Challenges for Theory and Observation", AIP, Vol.1170, p. 435

This research work presents a study of beans seed tissue (Phaseolous vulgaris, L.) optical interactions with laser aiming to contribute to the development of biospeckle techniques applied to the recognition of bean seed tissue vitality when contaminated with fungi, by differentiating the generated frequency spectra. Biospeckle is an interference optic phenomenon occurring when a laser beam reaches a surface exhibiting some dynamic process, due to biological activities or purely physical changes. The technique involves image processing to distinguish each different active material contribution present in the seed, by means of the procedure known as “Moment of Inertia” and frequency analysis. Frequency analysis was carried by Fourier Transform preceded by module of convolution. A great challenge in this area is to identify the elements contribution to increase biospeckle activity, such as water, microorganisms, among others. This research work is recognized to provide an important step aiming to characteriz...

In this paper, laser ultrasonic signals generated in ablative regime are measured in a number of metal samples (2024 Al, 6061 Al, 7075 Al, mild steel, and copper) with a broadband laser interferometer. The frequency spectra are analyzed and compared for different thicknesses (50.8 mm, 25.4 mm, 12.7 mm, and 6.4 mm), and for different power densities. Hanning windowing is applied before frequency analysis is performed. The experimental data match the theoretical predictions very well. The results show that the frequency spectrum extends from 0 to 15 MHz, while the center frequency occurs near 2 MHz. The detailed distribution of the spectrum is dependent on the material, thickness, and laser power density.

A time-localized frequency (TLF) analysis is employed for the guided wave mode identification and improved guided wave applications. For the analysis of time-localized frequency contents of digitized ultrasonic signals, TLF analysis consists of splitting the time domain signal into overlapping segments, weighting each with the hanning window, and forming the columns of discrete Fourier transforms. The result is presented by a frequency versus time domain diagram showing frequency variation along the signal arrival time. For the demonstration of the utility of TLF analysis, an experimental group velocity dispersion pattern obtained by TLF analysis is compared with the dispersion diagram obtained by theory of elasticity. Sample piping is carbon steel piping that is used for the transportation of natural gas underground. Guided wave propagation characteristic on the piping is considered with TLF analysis and wave structure concepts. TLF analysis is used for the detection of simulated corrosion defects and the assessment of weld joint using ultrasonic guided waves. TLF analysis has revealed that the difficulty of mode identification in multi-mode propagation could be overcome. Group velocity dispersion pattern obtained by TLF analysis agrees well with theoretical results.

The problem of predicting long-term particle loss in 4D betatronic motion is considered. A phenomenological scenario is derived through numerical tools based on tracking and frequency analysis. A three-parameter formula to interpolate the dynamic aperture versus the number of turns is proposed. The agreement with tracking data is excellent, and the extrapolation for very high number of turns agrees with the onset of chaos evaluated through the Lyapunov method.

Measurements performed on the SuperACO storage ring showed that, during the decay of the beam, the inherent synchrotron oscillation remains dipolar but the frequency of this oscillation depends on the remaining current in the storage ring. Three distinct regions of current were characterized. In the region of high current (100–200 mA), the frequency was constant and was three times the synchrotron frequency. At an intermediate current (70–100 mA), another constant frequency was present, two times the synchrotron frequency. In the third region (30–60 mA), at low current, the frequency was proportional to the square root of the current, and was higher than the two frequencies above. The synchrotron band in the frequency spectrum contained several lines which confirmed the presence of at least one passive cavity and maybe of a second one at two well separated frequencies. They induce self‐consistent micro structures in the bunch.

The following is a summary of a poster presentation at the Workshop. A full discussion of the matters touched on here will appear elsewhere.

We use 4 and 16 channel data from the BATSE Large Area Detectors to compare the continuum spectral characteristics of the short‐duration bursts with those of short spikes within long‐duration bursts. We compare frequency distributions of the resulting best‐fit model parameters for the short bursts and for the short spikes within the long bursts. These distributions are different for the two types of events. The best‐fit model parameters are used to calculate the peak energy Emax of the νFν spectrum for each type of event. The resulting distributions of Emax are consistent within a cosmological scenario if the redshift of the short spikes within long‐duration bursts is larger than the redshift of the short bursts.

The emission of neutrons from a titanium‐deuterium gas system has been detected by us in experiments performed in the Spring of 1989. One of the most striking features was the structure in bursts (duration of about 100 μs) of the neutron emission. Using a detection system proposed by H. Menlove, suitable to analyze the structure in bursts of the emission, a preliminary set of measurements has been performed with satisfactory results. A better tailored detector is now in use, and measurements in a low neutron background are being started. The first data about background and calibration measurements for this experiment will be reported.

The program, SUPERFISH, obtains the frequencies and fields for azimuthally symmetric TM or TE modes in azimuthally symmetric cavities. The r−z plane is covered by a triangular mesh and the resulting difference equations for the field component Hφ(TM) or Eφ(TE) at the vertices of the mesh solved by direct matrix inversion. In the present paper, we describe a number of recent modifications of SUPERFISH. (AIP)