Nonuniform sampling delta modulation for digital audio processing

I.lntroductionDigitalcodingofwavefOrrniswidelyusedinaudioengineeringbecauseoftheadvantageofdirectapproximatingthecodedsignaltotlleorigina1soundw...form[1'2].LinearDeltaModulation(LDM)isanimportantwaveformcodingtechniqueusingsing1ebitcodetorep-resentanalogsigna1swithwidespreadapplicationsinbothdigitalcommunicationsandsoundprocessing.However,inconventionalLDMsystems,thesamplingintervalisusuallyfixedwiththetransmissionrateeventhoughthesigna1characteristicsvaryl'].Thereforeifthestepsizeistoosm…     

Measurement of the total spectrum of electrons and positrons in the energy range of 300–1500 GeV in the PAMELA experiment with the aid of a sampling calorimeter and a neutron detector

A method based on the use of a sampling calorimeter was developed for measuring the total energy spectrum of electrons and positrons from high-energy cosmic rays in the PAMELA satellite-borne experiment. This made it possible to extend the range of energies accessible to measurements by the magnetic system of the PAMELA spectrometer. Themethod involves a procedure for selecting electrons on the basis of features of a secondary-particle shower in the calorimeter. The results obtained by measuring the total spectrum of cosmic-ray electrons and positrons in the energy range of 300–1500 GeV by the method in question are presented on the basis of data accumulated over a period spanning 2006 and 2013.

     

Monte Carlo sampling of energy-constrained quantum superpositions in high-dimensional Hilbert spaces

We derive scaling laws for the steady spectrum of wind excited waves, neglecting surface tension and taking air and water as inviscid, an approximation valid at large wind speed. Independently of the wind speed, there exists an unique (small) dimensionless parameter ϵ, the ratio of the mass densities of the two fluids (air and water). The smallness of ϵ allows to derive some important average properties of the wave system. The average square slope of the waves is, as observed, a small but not very small quantity, because it is of order |ln(ϵ ²)|^-1. This supports the often used assumption of small nonlinearity in the wave-wave interaction. We introduce an equation to be satisfied by the two-point correlation of the height fluctuations. Lastly we reconsider the formation of swell, that is the relationship between the randomness of waves and the observation of quasi monochromatic water waves.     

On coding of a quantum source of states with a finite frequency band: Quantum analogue of the Kotel’nikov theorem on sampling

An example of coding a source of quantum states with a finite frequency band W and finite exit power not exceeding ～(?W)W is given. The number of classical information bits that can be coded in the quantum states generated by such a source per unit time is C=W. Such a source is minimal in the sense that the filling factor for each of the orthogonal single-particle modes constituting N=WT-photon vector in time window 2T is equal to 1. This result can be treated as a quantum analogue of the Kotel’nikov theorem on sampling for classical signals     

Performance comparison between sampling methods using DOP as feedback signal for higher-order PMD compensator

We numerically analyzed the performance of the two polarization-mode dispersion(PMD)compensation methods of the single degree of polarization(DOP)sampling and DOP ellipsoid sampling methods.The numerical results show that the single DOP sampling method can generate the maximum DOP,and may result in a small overall differential group delay(DGD)or the principal state of polarization(PSP) launching.By the PSP launching,just the first-order PMD is compensated while second-order PMD not. When the DOP ellipsoid sampling method is used the performance is evidently better,because the effect of high-order PMD on PMD compensation is reduced.     

Design of a 1.2 GSPS single-channel real-time long-distance transmission sampling system for fast-transient signal

This article has introduced the origin and speciality of fast-transient signal, and told the meaning of researching on fast-transient signal. The main troubles of sampling on fast-transient signal is its `fast' and `transient', and the experiment's bad condition also troubles the transmission of information. To solve those troubles we put forward a technology called `digital Forward-sampling', and designs a sampling system for the fast-transient signal with this technology. The sampling rate of this system is 1.2 GSPS; it could get the whole pulse of fast-transient signal through the digital Forward-sampling technology; this system also could transmit the result to the analyzing equipment kilometers away immediately, before the data was destroyed by the electromagnetic and     

Multicanonical sampling of the space of states of ℋ(2, <Emphasis Type="Italic">n</Emphasis>)-vector models

Problems of temperature behavior of specific heat are solved by the entropy simulation method for Ising models on a simple square lattice and a square spin ice (SSI) lattice with nearest neighbor interaction, models of hexagonal lattices with short-range (SR) dipole interaction, as well as with long-range (LR) dipole interaction and free boundary conditions, and models of spin quasilattices with finite interaction radius. It is established that systems of a finite number of Ising spins with LR dipole interaction can have unusual thermodynamic properties characterized by several specific-heat peaks in the absence of an external magnetic field. For a parallel multicanonical sampling method, optimal schemes are found empirically for partitioning the space of states into energy bands for Ising and SSI models, methods of concatenation and renormalization of histograms are discussed, and a flatness criterion of histograms is proposed. It is established that there is no phase transition in a model with nearest neighbor interaction on a hexagonal lattice, while the temperature behavior of specific heat exhibits singularity in the same model, in case of LR interaction. A spin quasilattice is found that exhibits a nonzero value of residual entropy.     

Channel spacing halving and multi-channel apodisation of sampling fiber Bragg grating based on Moire effect

Channel spacing halving and multi-channel apodisation of sampling fiber Bragg grating (SFBG) based on Moire effect are demonstrated, which are realized by stretching and double exposure in fabrication of the SFBG. The experiment and theoretical analysis showed that the channel spacing could be halved when the period of Moire grating was four times of the period of sampling and the initial phase difference of two exposures was even times of m. The multi-channel apodisation could be realized when the period of Moire fringe was twice the length of SFBG and the initial phase difference of two exposures was odd times of m. A novel method to control the initial phase difference of two exposures is presented in this paper. Using this technique, we fabricated two SFBGs with channel spacing of 50 and 100 G by a same phase mask and an apodized SFBG with channel spacing of 100 G.     

Continuous analysis of δ¹⁸O and δD values of water by diffusion sampling cavity ring-down spectrometry: a novel sampling device for unattended field monitoring of precipitation, ground and surface waters

A novel sampling device suitable for continuous, unattended field monitoring of rapid isotopic changes in environmental waters is described. The device utilises diffusion through porous PTFE tubing to deliver water vapour continuously from a liquid water source for analysis of δ1?O and δD values by Cavity Ring-Down Spectrometry (CRDS). Separation of the analysed water vapour from non-volatile dissolved and particulate contaminants in the liquid sample minimises spectral interferences associated with CRDS analyses of many aqueous samples. Comparison of isotopic data for a range of water samples analysed by Diffusion Sampling-CRDS (DS-CRDS) and Isotope Ratio Mass Spectrometry (IRMS) shows significant linear correlations between the two methods allowing for accurate standardisation of DS-CRDS data. The internal precision for an integration period of 3 min (standard deviation (SD) = 0.1‰ and 0.3‰ for δ1?O and δD values, respectively) is similar to analysis of water by CRDS using an autosampler to inject and evaporate discrete water samples. The isotopic effects of variable air temperature, water vapour concentration, water pumping rate and dissolved organic content were found to be either negligible or correctable by analysis of water standards. The DS-CRDS system was used to analyse the O and H isotope composition in short-lived rain events. Other applications where finely time resolved water isotope data may be of benefit include recharge/discharge in groundwater/river systems and infiltration-related changes in cave drip water.     

Vernier frequency sampling: a new tuning approach in spectroscopy—application to multi-wavelength integrated path DIAL

We present novel frequency tuning methods for broadband mid-infrared spectroscopy that take advantage of the unique frequency sampling properties of our recently developed “nested dual-cavity doubly resonant optical parametric oscillator” (NesCOPO). These methods, referred to as Vernier frequency sampling, enable mode-hop tuning with an adjustable virtual-cavity intermode spacing. Both frequency resolution and span are widely adjustable and can be tailored to fulfill the requirements either for broadband spectroscopy (>50 cm^?1 spectral coverage) at low resolution or for high resolution (<0.01 cm^?1) narrow band spectroscopy. The technique is applied to short-range (10 to 30 m) atmospheric CO₂ measurements at 4.2 µm using integrated path differential absorption LIDAR.     

Can the CMB reveal the topology of the universe?

This article summarizes recent progress in the development of tools to study the topology of the universe with the cosmic microwave background. The different signatures of the topology and observational constraints are described. The ability of future experiments to reveal the topological structure of our universe is then discussed. To cite this article: J.P. Uzan, A. Riazuelo, C. R. Physique 4 (2003).     

Dark Energy： Relating the Evolutions of the Universe from the Past to the Future

Using the evolution history of the universe, one can make constraint on the parameter space of dynamic dark energy models. We discuss two different parameterized dark energy models. Our results further restrict the combined constraints obtained from supernova and the first-year Wilkinson-microwave-anisotropy-probe observations. From the allowed parameter space, it is found that our universe will experience an eternal acceleration. We also estimate the bound on the physically relevant regions both in the re-inflationary and inflationary phases.     

On the interpretation of the results of the experimental test of the Askar’yan effect

The effect of the environment on the results of measuring the radio radiation spectrum is considered in the experimental simulation of the cascade shower by a high-energy γ-ray beam in a dense medium. The calculation shows that the character of the measured energy spectrum depends on the location of the receiving antenna with respect to the shower axis.     

A robust and fast method of sampling and analysis of δ13C of dissolved inorganic carbon in ground waters

The stable carbon isotopic composition of dissolved inorganic carbon (δ¹³C_DIC) is traditionally determined using either direct precipitation or gas evolution methods in conjunction with offline gas preparation and measurement in a dual-inlet isotope ratio mass spectrometer. A gas evolution method based on continuous-flow technology is described here, which is easy to use and robust. Water samples (100–1500 μl depending on the carbonate alkalinity) are injected into He-filled autosampler vials in the field and analysed on an automated continuous-flow gas preparation system interfaced to an isotope ratio mass spectrometer. Sample analysis time including online preparation is 10 min and overall precision is 0.1 ‰. This method is thus fast and can easily be automated for handling large sample batches.     

Stochastic bounded consensus tracking of leader–follower multi-agent systems with measurement noises based on sampled-data with small sampling delay

This paper is concerned with the stochastic bounded consensus tracking problems of leader–follower multi-agent systems, where the control input of an agent can only use the information measured at the sampling instants from its neighborhood agents or a virtual leader with a time-varying reference state, the measurements are corrupted by random noises, and the signal sampling process induces a small sampling delay. The augmented matrix method, probability limit theory and algebra graph theory are employed to derive the necessary and sufficient conditions guaranteeing mean square bounded consensus tracking. It turns out that the convergence of the proposed protocol simultaneously depends on the constant feedback gains, the network topology, the sampling period and the sampling delay, and that the static consensus tracking error depends on not only the above-mentioned factors, but also the noise intensity, the number of agents and the upper bound of the changing rate of the virtual leader’s state. The obtained results cover no sampling delay as a special case. Simulations are provided to demonstrate the effectiveness of the theoretical results.     

Telecommunications—the state of the art

This article is a survey of the technological foundations of telecommunications, including both point-to-point electrical communication wing wires, cables and other guiding media. and radio wave broadcasting to many receivers via terrestrial transmitters or Earth-orbiting space satellites. The characteristics of analogue and digital telecommunication signals, the means available for their transmission and switching me described, together with the organization of local distribution, national and global networks. The various services that can be provided over such networks, including in addition to telephonic communication, audio and video conferencing, data and facsimile transmission and new vied-display data/information access services (Teletext) are outlined. Finally, the sociological implications of these technological and service developments me considered, for example in terms of their impact on urban and rural planning, where people live and work, and on energy economy by reducing the need to travel.     

Why is the Euclidean Line the Same as the Real Line?

This paper investigates whether the differential structure of space-time follows from accepted laws of physics, or is a mathematical invention. In view of the results of [7], it suffices to consider whether the assumed identity of the Euclidean line E—the line of the geometers of ancient Greece—and the real line R of modern analysis, follows from any known law of nature (i.e., one that can be falsified empirically). Since the totality of empirical data is finite, one is forced to conclude that the completeness of R cannot be falsified empirically—and therefore, according to Popper's criterion, the real line must be an invention, and not a discovery. It then becomes difficult to tell whether Newton's second law of motion (expressed as the differential equation is an invention or a discovery! Finally, some alternatives to the above analysis are briefly analysed.     

On the Structure of the B¨acklund Transformations for the Relativistic Lattices

Abstract

The B¨acklund transformations for the relativistic lattices of the Toda type and their discrete analogues can be obtained as the composition of two duality transformations. The condition of invariance under this composition allows to distinguish effectively the integrable cases. Iterations of the B¨acklund transformations can be described in the terms of nonrelativistic lattices of the Toda type. Several multifield generalizations are presented.     

Study on the optical system for the record of the pulsed acoustic field and the scattering of the cylindrical-like objects buried in underwater sand

11尬roductlon For the vlsuallzatlon and the studies of the physical properties of acoustic ield;the schlierentechnique was the most useful for the co尬Inuous waves[1,2].ReceNwars,the shadowgraphmode was appeared for the recording of＊theing acoustic pulse[3-p].Although the shadowgr地hmode Is used more frequently In experimental fluid dynamics[6],In the irst part of this paper;the response of＊these opticall扯enslty of＊the recorded acoustic pulse related to the acousticpressure gradlem Is st…