Effects of quantization on detrended fluctuation analysis

Detrended fluctuation analysis(DFA) is a method foro estimating the long-range power-law correlation exponent in noisy signals.It has been used successfully in many different fields,especially in the research of physiological signals.As an inherent part of these studies,quantization of continuous signals is inevitable.In addition,coarse-graining,to transfer original signals into symbol series in symbolic dynamic analysis,can also be considered as a quantization-like operation.Therefore,it is worth considering whether the quantization of signal has any effect on the result of DFA and if so,how large the effect will be.In this paper we study how the quantized degrees for three types of noise series(anti-correlated,uncorrelated and long-range power-law correlated signals) affect the results of DFA and find that their effects are completely different.The conclusion has an essential value in choosing the resolution of data acquisition instrument and in the processing of coarse-graining of signals.     

Monitoring the formation of oil–water emulsions with a fast spatially resolved NMR spectroscopy method

In the present study, a fast chemical shift imaging(CSI) method has been used to dynamically monitor the formation of oil–water emulsions and the phase separation process of the emulsion phase from the excessive water or oil phase on the molecular level. With signals sampled from series of small voxels simultaneously within a few seconds, high-resolution one-dimensional(1D) ~1H nuclear magnetic resonance(NMR) spectra from different spatial positions for inhomogeneous emulsion systems induced by susceptibility differences among components can be obtained independently. On the basis of integrals from these ~1H NMR spectra, profiles obtained explicitly demonstrate the spatial and temporal variations of oil concentrations. Furthermore, the phase separation time and the length of the oil–water emulsion phase are determined. In addition, effects of oil types and proportions of the emulsifier on the emulsification states are also inspected. Experimental results indicate that 1D PHASICS(Partial Homogeneity Assisted Inhomogeneity Correction Spectroscopy) provides a helpful and promising alternative to research on dynamic processes or chemical reactions.     

Transportation of dynamic biochemical signals in non-reversing oscillatory flows in blood vessels

Biological processes and behaviors of endothelial cells on the inner surfaces of blood vessels are regulated by the stimulation from biochemical signals contained in the blood.In this paper,the transportation of dynamic biochemical signals in non-reversing oscillatory flows in blood vessels is analyzed by numerically solving a nonlinear governing equation for the time-dependent Taylor-Aris dispersion.Results show that the nonlinear frequency-amplitude modulation of the transportation of biochemical signals is more(less) significant when the frequency of an oscillatory flow is close to(higher than) that of an oscillatory signal.Under steady flow,the transfer function for the signal transmission system is obtained,showing that the system is a low-pass filter.Lower inner radius or higher center-line velocity of a blood vessel increases the cutoff frequency of the transportation system.These results suggest the possibility and condition for the ’remote’ transmission of low-frequency dynamic biochemical signals in pulsatile blood flows.     

Toward a fractal spectrum approach for neutron and gamma pulse shape discrimination

Accurately selecting neutron signals and discriminating 7 signals from a mixed radiation field is a key research issue in neutron detection.This paper proposes a fractal spectrum discrimination approach by means of different spectral characteristics of neutrons and 7 rays.Figure of merit and average discriminant error ratio are used together to evaluate the discrimination effccts.Different neutron and γ signals with various noise and pulse pile-up are simulated according to real data in the literature.The proposed approach is compared with the digital charge integration and pulse gradient methods.It is found that the fractal approach exhibits the best discrimination performance,followed by the digital charge integration method and the pulse gradient method,respectively.The fractal spectrum approach is not sensitive to high frequency noise;and pulse pile-up.This means that the proposed approach has superior performance for effective and efficient anti-noise and high discrimination in neutron detection.     

Droplet impact on regular micro-grooved surfaces

We have investigated experimentally the process of a droplet impact on a regular micro-grooved surface. The target surfaces are patterned such that micro-scale spokes radiate from the center, concentric circles, and parallel lines on the polishing copper plate, using Quasi-LIGA molding technology. The dynamic behavior of water droplets impacting on these structured surfaces is examined using a high-speed camera, including the drop impact processes, the maximum spreading diameters, and the lengths and numbers of fingers at different values of Weber number. Experimental results validate that the spreading processes are arrested on all target surfaces at low velocity. Also, the experimental results at higher impact velocity demonstrate that the spreading process is conducted on the surface parallel to the micro-grooves, but is arrested in the direction perpendicular to the micro-grooves. Besides, the lengths of fingers increase observably, even when they are ejected out as tiny droplets along the groove direction, at the same time the drop recoil velocity is reduced by micro-grooves which are parallel to the spreading direction, but not by micro-grooves which are vertical to the spreading direction.     

Derivative fluorimetry analysis of new cluster structures formed by ethanol and Water molecules

The ultraviolet （UV） light excited fluorescence spectra of ethanol-water mixture with different concentrations are investigated by derivative fluorimetry. It is found that there are 8 types of luminescent cluster molecules, formed by ethanol and water molecules in different ways, existing in the solution. The peak wavelengths of all these clusters＇ fluorescence spectra are measured and their contents are obtained by measuring the peak values in the second derivative fluorescence spectra. The spectra corresponding to the 8 types of clusters are obtained by Gaussian decomposition. It is found that two kinds of cluster molecules whose peak wavelengths are 330 and 345 nm have an optimal excitation wavelength located at （236 4- 3） nm. This research contributes to the study of ethanol-water cluster structures and their physical and chemical characteristics.     

Phase transition model of water flow irradiated by high-energy laser in a chamber

In the absorption chamber of a high-energy laser energy meter, water is directly used as an absorbing medium and the interaction of the high-power laser and the water flow can produce a variety of physical phenomena such as phase transitions. The unit difference method is adopted to deduce the phase transition model for water flow irradiated by a high-energy laser. In addition, the model is simulated and verified through experiments. Among them, the experimental verification uses the photographic method, shooting the distribution and the form of the air mass of water flow in different operating conditions, which are compared with the simulation results. The research shows that it is achievable to reduce the intensity of the phase transition by increasing the water flow, reducing the power intensity of the beam, shortening the distance the beam covers, reducing the initial water temperature or adopting a shorter wavelength laser. The study＇s results will provide the reference for the design of a water-direct-absorption-type high-energy laser energy meter as well as an analysis of the interaction processes of other similar high-power lasers and water flow.     

Book Review MODERN METHODS IN ANALYTICAL ACOUSTICS

This is a collection of lecture notes of five applied mathematicians and acousticians.The authors are all world-famous authorities in their fields,showing for senioracousticians in their lectures the applications and usefulness of various mathematicalmethods.It is not a book of mathematics,the emphesis is on its effectiveness to the ad-vanced study of dynamic mechanics problems as encountered in aeroacoustics andunderwater acoustics.And large number of references are cited for those who want to in-dulge further into the mathematical origins.     

Structure and dynamics of ordered water in a thick nanofilm on ionic surfaces

The structure and dynamics of water in a thick film on an ionic surface are studied by molecular dynamic simulations. We find that there is a dense monolayer of water molecules in the vicinity of the surface. Water molecules within this layer not only show an upright hydrogen-down orientation, but also an upright hydrogen-up orientation. Thus, water molecules in this layer can form hydrogen bonds with water molecules in the next layer. Therefore, the two-dimensional hydrogen bond network of the first layer is disrupted, mainly due to the O atoms in this layer, which are affected by the next layer and are unstable. Moreover, these water molecules exhibit delayed dynamic behavior with relatively long residence time compared with those bulk-like molecules in the other layers. Our study should be helpful to further understand the influence of water film thickness on the interfacial water at the solid-liquid interface.     

CONTRIBUTIONS TO ACOUSTICS IN CHINA

We have a long history of acoustical investigation in China.The earliest record of acousticaltheory was found in writings of the sixth century B.C.,and legend put it much earlier.Acousticalphenomena were observed and discussed through the history.During the first half of this century,however,acoustics,like other branches of sciences,was left far behind,owing to the feudal-reactionaryrule prevailed in China.Only after the national liberation in 1949,the research in acoustics,boththeoretical and experimental,revived.A relatively strong research force was gradually formed,andmore and more important contributions were made in support of the socialistic reconstruction in China.The growth of the acoustical community,its academic activities and main contributions are reviewedin this article.     

关于"太阳在银河系中所受引力与到银心距离r的关系"的讨论

讨论了银道面内的引力场强分布和太阳在银河系中所受引力与到银心距离r的关系，指出引力场强g并不是与r的平方成反比，这是由于银河系的大小和形状不能忽略造成的．强调了万有引力定律的适用条件．     

On the predictability of the positions of the convergence zones in the ocean

The disagreement between the experimental and calculated positions of the first convergence zone are known from many publications. The most probable cause for such a disagreement, namely, the incorrect specification of the input data for the calculations, is considered. The lack of simultaneity between the hydrological surveys of the region and the acoustic experiments is emphasized. The experimental data obtained by the author in five ocean regions are presented. These data characterize the diurnal variability of the distance from the source to the nearest boundary of the convergence zone. The relations proposed by different researchers for calculating the sound speed from the temperature, salinity, and hydrostatic pressure are analyzed. It is shown that these relations lead to a substantial difference in the estimated depth dependence of the hydrostatic gradient of the sound speed. The position of the first convergence zone is calculated for the propagation conditions determined by vertical temperature and salinity profiles with the subsequent recalculation of these profiles into sound speed profiles by using eight different formulas known from the literature. It is shown that different formulas lead to different values of the distance to the first zone; this difference is substantially greater than that between the calculations and experiment. The necessity of improving the recalculation relations in view of the experimental data on sound propagation in natural oceanic waveguides, including the data on the actual positions of the convergence zones, is emphasized.     

On the calculation of the bremsstrahlung in the region of the plasma frequency

On the basis of the classical theory of radiation produced in incomplete Coulomb interaction, a formula is derived for the coefficient of the bremsstrahlung of fully ionized plasma. In the region of rectilinear approximation a comparison is made with the results of the quantum formula derived from the Born approximation. Furthermore, the influence of dispersion upon the emission coefficient is taken into account; some relations for the region of dispersion are given.     

Dependence of the Intensity of the Spectral Lines and the Composition of the Sample and the Plasma Parameters of the Unipolar Arc

The investigation was made of the dependence of the intensity of Tl, Ga, Mo, Mg, Mn, Sn, Bi, Ni, Zn, Pt and Au spectral lines and the plasma parameters (temperature T, electron concentration n_e, degree of 6 ionnization α) from concentration of lithium additive.     

Extracting the wavefunction of the LSP at the LHC

We consider associated production of squarks and gluinos with the lightest supersymmetric particle (LSP), or states nearly degenerate in mass with it. Though sub-dominant to pair production of color SU(3)-charged superpartners, these processes are directly sensitive to the wavefunction composition of the lightest neutralinos. Exploiting event-shape variables - including some introduced here for the first time - we are able to identify the composition of the LSP by selecting events involving a single high-pT jet recoiling against missing transverse energy. We illustrate the proposed technique on a set of benchmark cases and propose methods for applying these results in more realistic experimental environments.     

On the Question of the Source of the Apokamp

Technical Physics - The object of this work is the apokamp—a new type of plasma jet, which is formed from a bright offshoot emerging at the bending point of a channel of a high-voltage...     

Set the controls for the heart of the Sun

In this paper we describe experiments conducted with high-power lasers that are attempting to replicate, for a very short time and in miniature, conditions found in the Sun. Experiments to date have reached conditions in the outer part of the Sun. To reach the Sun's centre requires compression of material to very much greater than solid density and heating to over ten million degrees. To achieve this, a new class of experiments and a new generation of high-power lasers are required.