Narrow Results

An acoustic wave signal measured on the gas pipe due to impact force is transfer to the far distance through the medium inside of duct. This signal is very complex since it includes the acoustic wave and solid wave. Acoustic wave is affected by the cavity mode inside of duct. The analysis of this acoustic wave gives information about the impact force. For the analysis of this signal, the correlation technique has been used for a long time. This method has a limitation for the application since the waves have dispersive and cavity mode characteristics for the flexible wave. In this paper, we present the time-frequency method for the identification of impact force and the location of impact on the gas pipe. The results give the useful information for the impact force and are applied to the analysis of leakage location of the gas pipe.

We experimentally demonstrate radar remote imaging using a radio technique based on ultra-wideband chaotic signals over fiber links. The radar system includes three parts, i.e. a central station, some optical fiber links and a base station. At the central station, an ultra-wideband chaotic signal is generated from an improved Colpitts oscillator and then is up-converted as a probe signal. The probe signal is then converted to be in optical domain by the external modulation technique on laser diode for transmitting over a fiber link to a remote base station. At the base station, the probe signal is converted to be in electrical domain and then launched by a microwave antenna. After being received by another antenna, the echo signal from a target is converted to be in optical domain and then transmitted over a fiber link back to the central station. By optical-to-electrical conversion and down conversion, the echo chaotic signal is recovered. Utilizing the correlation method and back projection algorithm, an image of the target in the two-dimensional space can be realized at the central station. Our experiments successfully performed remote imaging for both planar and spherical reflectors with a distance over 10 km. The down-range resolution of 6-cm and 8-cm cross-range resolution were obtained, respectively. We will show that the power spectrum of the probe signal is adjustable in the spectral mask according to the Federal Communications Commission standards, therefore can avoid interference to the existing narrowband radio signals.

Direct method for detecting intranuclear clusters of nuclear matter-clusters and determining their effective numbers was developed. The idea of the method is based on the functional coincidence of kinematics for light nuclei in the free state and clusters of the same mass within the nuclear volume. The reliability of the method is additionally confirmed by two experimental methods. The experiments were carried out at the Kazakhstan U-150M accelerator on a beam of $\alpha$-particles with energy of 29MeV. The first method consists in measuring the half-width of the elastic scattering peak from the angle and a comparison between the differential cross-sections of elastically scattered $\alpha$ particles on free light nuclei and the differential cross-sections obtained by the authors on intranuclear multicluster. Using the second method, the correlation method, an experiment was performed to record the scattered $\alpha$ particle on the ⁹Be nucleus-matrix and the recoil nucleus identical to it ($\alpha$ particle). Thus, the kinematics of the ${}^4\mathrm{\text{He}}(\alpha ,\alpha )$⁴He reaction, where ⁴He is an intranuclear $\alpha$ cluster, indicates the presence of an intranuclear alpha cluster, which is further confirmed by the authors, an experimental measurement of intranuclear multicluster.

Identification of individuals who are at risk for sudden cardiac death (SCD) remains a formidable challenge. T-wave alternans (TWA) evaluation is emerging as an important tool for risk stratification in patients with heart diseases. Several methods have been developed in recent years to detect and quantify TWA. One such method is known as the correlation method (CM). This method performs well for different levels of TWA and phase shifts in the time domain, but it is sensitive to noise and requires higher quality of electrocardiogram (ECG) signal for test. In this paper, we propose a modified correlation method (MCM) to ensure a robust and accuracy detection of TWA. Compared with CM, MCM add a stage of T-wave curve fitting before media T-wave template, and the TWA magnitude is obtained by meaning the maximum absolute difference between even and odd T-wave. Our assessment study demonstrates the improved performance of the proposed algorithm.