Multichannel Version Research Articles

Wavelet Cross-Correlation Signal Processing for Two-Phase Flow Control System in Oil Well Production

An algorithm based on continuous measurement of multiphase flows of oil well production has been designed to improve the efficiency of the technical control of oil production processes in the field. Separation-free, non-contact measurement of multiphase flows of oil well products allows increasing the efficiency of managing oil production processes in the field. Monitoring the current density using radioisotope measuring transducers (RMTs) allows obtaining information about the structure of the flow in the form of the distribution of gas inclusions and the speed of movement of liquid and gas in a two-phase flow. Fluid velocity measurement is based on digital processing of RMT signals, applying a continuous or discrete undecimated wavelet transform to them, and assessing the cross-correlation of wavelet coefficients in individual subspaces of the wavelet decomposition. The cross-correlation coefficients of two RMT signals located at a base distance, calculated in the subspaces of the wavelet decomposition, characterize the speed of movement of gas bubbles of different sizes in a vertical pipe. The measurement assumes that the velocity of the liquid phase of the oil flow in a vertical pipe mainly corresponds to the velocity of small bubbles. This speed should be determined by the maximum cross-correlation of wavelet coefficients in the corresponding decomposition subspace. Computer modeling made it possible to evaluate the characteristics of the algorithm for controlling the speed of liquid movement in the gas–liquid flow of oil well products and determine the mass flow rate of the liquid and the relative value of the gas content. The implementation of the algorithm in a multi-channel version of the device allows monitoring an entire cluster of wells in the field.

Exact tests for offline changepoint detection in multichannel binary and count data with application to networks

We consider offline detection of a single changepoint in binary and count time-series. We compare exact tests based on the cumulative sum (CUSUM) and the likelihood ratio (LR) statistics, and a new proposal that combines exact two-sample conditional tests with multiplicity correction, against standard asymptotic tests based on the Brownian bridge approximation to the CUSUM statistic. We see empirically that the exact tests are much more powerful in situations where normal approximations driving asymptotic tests are not trustworthy: (i) small sample settings; (ii) sparse parametric settings; (iii) time-series with changepoint near the boundary. We also compare these exact tests against their bootstrap-based variants which do not have exact type I error control guarantees. Further, we consider a multichannel version of the problem, where channels can have different changepoints. Controlling the False Discovery Rate (FDR), we simultaneously detect changes in multiple channels. This ‘local’ approach is shown to be more advantageous than multivariate global testing approaches when the number of channels with changepoints is much smaller than the total number of channels. As a natural application, we consider network-valued time-series and use our approach with (a) edges as binary channels and (b) node-degrees or other local subgraph statistics as count channels. The local testing approach is seen to be much more informative than global network changepoint algorithms.

Theoretical Study of the Seven-Nucleon 6Li + p System Using the Algebraic Version of the Resonating Group Model

The seven-nucleon 6Li + p system is considered. The 6Li(p, α)3He transfer reaction being of interest to nuclear astrophysics is studied using a multichannel algebraic version of the resonating group model. The astrophysical S-factor of this reaction is calculated at low sub-barrier energies. The result is compared with available experimental data and other theoretical calculations.

A laser-based system for a fast and accurate measurement of gain and linearity of photomultipliers

This paper describes a method for the measurement of gain and linearity of photomultipliers (PMTs). Gain and linearity are two fundamental parameters to use properly a PMT in several physics experiments. In the developed system light is laser generated and adressed to the PMT through a set of optical fibers. The data acquisition system consists in a commercial 16 channel digitizer coupled to a custom front-end board. With the chosen digitizer the system is scalable to test up to 16 PMTs, with the aid of a light distribution system and a multi-channel version of the front-end board. Data analysis is performed by a custom acquisition software. A 1.5" Hamamatsu PMT is used to validate the system.

Microscopic multichannel investigation of the 6Li + n seven-nucleon nuclear system at low energies

The 6Li + n seven-nucleon nuclear system is studied at low energies within a microscopic approach based on the multichannel algebraic version of the resonating group model. The partial and total cross sections for the 6Li(n, t)4He reaction are calculated. The contributions of the various partial cross sections to the energy dependence of the total cross section are considered. The results of the calculations are found to be in a good agreement with experimental data.

A multichannel block-matching denoising algorithm for spectral photon-counting CT images.

We present a denoising algorithm designed for a whole-body prototype photon-counting computed tomography (PCCT) scanner with up to 4 energy thresholds and associated energy-binned images. Spectral PCCT images can exhibit low signal to noise ratios (SNRs) due to the limited photon counts in each simultaneously-acquired energy bin. To help address this, our denoising method exploits the correlation and exact alignment between energy bins, adapting the highly-effective block-matching 3D (BM3D) denoising algorithm for PCCT. The original single-channel BM3D algorithm operates patch-by-patch. For each small patch in the image, a patch grouping action collects similar patches from the rest of the image, which are then collaboratively filtered together. The resulting performance hinges on accurate patch grouping. Our improved multi-channel version, called BM3D_PCCT, incorporates two improvements. First, BM3D_PCCT uses a more accurate shared patch grouping based on the image reconstructed from photons detected in all 4 energy bins. Second, BM3D_PCCT performs a cross-channel decorrelation, adding a further dimension to the collaborative filtering process. These two improvements produce a more effective algorithm for PCCT denoising. Preliminary results compare BM3D_PCCT against BM3D_Naive, which denoises each energy bin independently. Experiments use a three-contrast PCCT image of a canine abdomen. Within five regions of interest, selected from paraspinal muscle, liver, and visceral fat, BM3D_PCCT reduces the noise standard deviation by 65.0%, compared to 40.4% for BM3D_Naive. Attenuation values of the contrast agents in calibration vials also cluster much tighter to their respective lines of best fit. Mean angular differences (in degrees) for the original, BM3D_Naive, and BM3D_PCCT images, respectively, were 15.61, 7.34, and 4.45 (iodine); 12.17, 7.17, and 4.39 (galodinium); and 12.86, 6.33, and 3.96 (bismuth). We outline a multi-channel denoising algorithm tailored for spectral PCCT images, demonstrating improved performance over an independent, yet state-of-the-art, single-channel approach.

Multi-decadal 40- to 60-year cycles of precipitation variability in Chile (South America) and their relationship to the AMO and PDO signals

High-frequency components of precipitation variability have been an important focus of study during the last few decades in Chile. Low-frequency variations, on the other hand, have received less attention, especially in association with multi-decadal cycles that can affect variability trends of precipitation in the long term. This study analyzes these low-frequency patterns of precipitation in Chile (>30years), and their relationship to global Sea Surface Temperatures (SSTs), with special focus on associations with the Pacific Decadal Oscillation (PDO) and the Atlantic Multi-decadal Oscillation (AMO) indices. Singular Spectrum Analysis (SSA) and its Multi-Channel version (MSSA) techniques were applied to a dataset containing long instrumental records of monthly precipitation aggregated yearly and seasonally. The relationships between the low-frequency variability of precipitation and the PDO are significant to the north of the country, whereas connections with the AMO are significant to the north and also to the south. This is also evident from the global spatial correlation analysis of low-frequency precipitation modes and SSTs, where the southernmost station shows a strong relationship with the Atlantic Ocean. We conclude that a significant multi-decadal precipitation cycle between 40 and 60years is evident at the rain gauges located in the subtropical and extratropical regions of Chile. This low-frequency variability seems to be largely linked to PDO and AMO modulation.

Microscopic Study of the 6Li(p, α)3He Reaction at Low Energies

The 6 Li(p, α)3 He reaction important for nuclear astrophysics is studied in the framework of a microscopic approach based on a multichannel algebraic version of the resonating group model. Astrophysical S -factor for the reaction is calculated at low energies. The obtained result is compared with experimental data and other theoretical calculations.

The grammatical potential of co-speech gesture

In recent years, consensus has been growing that certain co-speech gestures must be incorporated in grammatical theory. Contrary to traditional beliefs, gestural expression has been found to be systematic in various ways, to exhibit some degree of compositional structure and to be to a certain extent language-specific. Most current work on the gesture-grammar interface is, nonetheless, rather programmatic in character or lacks an appropriate theoretical framework. This paper shows that Functional Discourse Grammar (FDG) provides a promising model for understanding the grammar-gesture relationship in a more comprehensive and detailed way than has thus far been achieved. It first evaluates how a FDG perspective on language structure aligns with the ways gestures have been studied. Then it demonstrates that various types of co-speech manual gestures can be classified (perhaps even exhaustively) according to the pragmatic and semantic layers recognized in FDG. On the basis of this survey, a first sketch of a multi-channel (speech-gesture) version of FDG’s architecture is presented. Finally, some challenges are put forward that arise when taking the multimodal grammar enterprise seriously. Altogether, the content of this paper suggests that a multimodal perspective on grammar can be mutually beneficial for functionally oriented linguists and gesture researchers.

Distributed and Energy Efficient Scheduling for IEEE802.11s Wireless EDCA Networks

We consider scheduling over IEEE802.11s wireless mesh networks running the standard Hybrid Wireless Mesh Protocol (HWMP) which forms a tree rooted at the mesh gateway. We propose Time-Split, a very simple and distributed scheduling algorithm compatible with the conventional EDCA mode of access. Time-Split is equipped with a simple mechanism to remove off-path interference without knowledge of the interference graph. Furthermore, Time-Split limits time-line fragmentation by creating contiguous inactivity periods within a beacon interval that can be used for deep power saving. We compare the performance of Time-Split with a greedy scheduler which performs optimally over the tree formed by HWMP for traffic routed to/from the gateway. We show that Time-Split can achieve more than 90 % optimal throughput at a packet delivery ratio of almost 100 %. More importantly, we propose split-depth as a means to strike a balance between interference elimination and spectrum sharing. In addition, we introduce a multi-channel version of Time-Split improving connection acceptance ratio by about 15 % using a single radio interface. Furthermore, due to its contiguous deep sleep intervals, Time-Split can potentially provide up to 25 and 50 % energy savings compared to conventional EDCA with sleep capability and a greedy sleep scheduler, respectively.

Adiabatic potential-energy curves of long-range Rydberg molecules: Two-electronR-matrix approach

We introduce a computational method developed for study of long-range molecular Rydberg states of such systems that can be approximated by two electrons in a model potential of the atomic cores. Only diatomic molecules are considered. The method is based on a two-electron \rmath approach inside a sphere centered on one of the atoms. The wave function is then connected to a Coulomb region outside the sphere via multichannel version of the Coulomb Green's function. This approach is put into a test by its application to a study of Rydberg states of the hydrogen molecule for internuclear distances $R$ from 20 to 400 bohrs and energies corresponding to $n$ from 3 to 22. The results are compared with previous quantum chemical calculations (lower quantum numbers $n$) and computations based on contact potential models (higher quantum numbers $n$).

Elastic and inelastic vibrational cross sections for positron scattering by carbon monoxide

The vibrational cross sections of the CO molecule induced by positron impact is the focus of this work. The positron–molecule interaction is represented by the static potential plus a model potential designed to take into account the positron–target correlations. To calculate the vibrational cross sections, we applied the multichannel version of the continued fractions method in the close-coupling scheme. We present vibrational excitation cross sections and elastic ones, for the ground and excited vibrational states. The results are interpreted in terms of the vibrational coupling-scheme used in the scattering model.

Multichannel Extensions of Non-Negative Matrix Factorization With Complex-Valued Data

This paper presents new formulations and algorithms for multichannel extensions of non-negative matrix factorization (NMF). The formulations employ Hermitian positive semidefinite matrices to represent a multichannel version of non-negative elements. Multichannel Euclidean distance and multichannel Itakura-Saito (IS) divergence are defined based on appropriate statistical models utilizing multivariate complex Gaussian distributions. To minimize this distance/divergence, efficient optimization algorithms in the form of multiplicative updates are derived by using properly designed auxiliary functions. Two methods are proposed for clustering NMF bases according to the estimated spatial property. Convolutive blind source separation (BSS) is performed by the multichannel extensions of NMF with the clustering mechanism. Experimental results show that 1) the derived multiplicative update rules exhibited good convergence behavior, and 2) BSS tasks for several music sources with two microphones and three instrumental parts were evaluated successfully.

Adaptación española de la versión reducida multicanal del Perfil de Sensibilidad No Verbal (MiniPONS)

The Spanish version of the MiniPONS (Bänziger, Scherer, Hall y Rosenthal, 2011), the short version multichannel of the Profile of Nonverbal Sensitivity (PONS), is presented. This scale was designed to measure individual differences in the ability to recognize emotions, interpersonal attitudes, and communicative intentions in nonverbal channels. This short multichannel version is composed of 64 items nonverbal audio and/or visual scenes portrayed by a female in black and white color. The main aim of this study was to analyze the psychometric properties of MiniPONS using a large sample of university students (N = 1154) aged 18-60, this study also examined gender and age differences in nonverbal sensitivity. Normative data, reliability and validity were examined in three studies with 168, 254, and 1154 university students. The Spanish version of the MiniPONS has psychometric properties similar to those of the original version, the MiniPONS had moderate internal consistency and test-retest reliability, and shows reasonable convergent validity through significant correlations with other tests of non-verbal emotion recognition ability. Results revealed an advantage of women in all the conditions of stimulus presentation; women not only process more efficiently unisensory nonverbal information (face, body and voice) but may also be better at integrating emotional expressions. We conclude that the MiniPONS Spanish version is an adequate instrument to be used in measure of socio-nonverbal sensitivity. Limitations and potential applications for research are described. : E�F' p�Pr�span>have not been studied for current literature. The aim of this study was to analyse changes in cortical arousal, blood lactate, muscle strength, autonomic modulation and rate of perceived exertion in a simulated urban combat. We analyzed 20 soldiers before and after an urban combat simulation. The results showed how urban combat produced high sympathetic nervous system activation, increasing the muscle strength, heart rate and blood lactate concentration of the soldiers. Despite this effort, rate of perceived exertion were not consistent with the physiological response that soldiers presented, the rate of perceived exertion was lower than the physiological response evaluated. Furthermore, the information processing and cortical arousal decreased after the urban combat simulation. These results have showed the psycho-physiological response of soldiers in combat, helping to better understanding and enabling an improvement of current training methods of soldiers.

Ambient Vibration Recording for Single-Station, Array and Building Studies Made Simple: CityShark II

This article describes an improved data acquisition system from a previous system dedicated to one-sensor site studies, aimed at recording ambient vibrations (microtremors). A multi-channel and/or remote triggering system is proposed. The system was conceived by IRD-Leas, France, and used at ISTerre, France, for research activities. The size, weight of this high quality system and its autonomy (no need to be connected to a laptop) make it a real portable device. The system acquires data with 24-bit delta-sigma ADCs in the 10 - 1000 sps range at 10 - 20 bit resolution on up to 18 channels in the multi-channel version. The input stage dynamics is available at ±2.5 V or ±5 V. The dynamic range varies, for example, from 108 dB at 100 sps to 90 dB at 250 sps. Gain is selectable from 1 (0 dB) to 8192 (78 dB) by powers of two (6 dB). Its very low level of internal noise allows recording of very low tension signals without missing code. Continuous recording and GPS may also be implemented in the system. While primarily dedicated to ambient vibration recordings, this system can be connected to any type of device delivering an output tension in the ±5 V range.

Multichannel Detrended Fluctuation Analysis Reveals Synchronized Patterns of Spontaneous Spinal Activity in Anesthetized Cats

The analysis of the interaction and synchronization of relatively large ensembles of neurons is fundamental for the understanding of complex functions of the nervous system. It is known that the temporal synchronization of neural ensembles is involved in the generation of specific motor, sensory or cognitive processes. Also, the intersegmental coherence of spinal spontaneous activity may indicate the existence of synaptic neural pathways between different pairs of lumbar segments. In this study we present a multichannel version of the detrended fluctuation analysis method (mDFA) to analyze the correlation dynamics of spontaneous spinal activity (SSA) from time series analysis. This method together with the classical detrended fluctuation analysis (DFA) were used to find out whether the SSA recorded in one or several segments in the spinal cord of the anesthetized cat occurs either in a random or in an organized manner. Our results are consistent with a non-random organization of the sets of neurons involved in the generation of spontaneous cord dorsum potentials (CDPs) recorded either from one lumbar segment (DFA- mean = 1.040.09) or simultaneously from several lumbar segments (mDFA- mean = 1.010.06), where = 0.5 indicates randomness while 0.5 indicates long-term correlations. To test the sensitivity of the mDFA method we also examined the effects of small spinal lesions aimed to partially interrupt connectivity between neighboring lumbosacral segments. We found that the synchronization and correlation between the CDPs recorded from the L5 and L6 segments in both sides of the spinal cord were reduced when a lesion comprising the left dorsal quadrant was performed between the segments L5 and L6 (mDFA- = 0.992 as compared to initial conditions mDFA- = 1.186). The synchronization and correlation were reduced even further after a similar additional right spinal lesion (mDFA- = 0.924). In contrast to the classical methods, such as correlation and coherence quantification that define a relation between two sets of data, the mDFA method properly reveals the synchronization of multiple groups of neurons in several segments of the spinal cord. This method is envisaged as a useful tool to characterize the structure of higher order ensembles of cord dorsum spontaneous potentials after spinal cord or peripheral nerve lesions.

Introducing the MiniPONS: A Short Multichannel Version of the Profile of Nonverbal Sensitivity (PONS)

Despite extensive research activity on the recognition of emotional expression, there are only few validated tests of individual differences in this competence (generally considered as part of nonverbal sensitivity and emotional intelligence). This paper reports the development of a short, multichannel, version (MiniPONS) of the established Profile of Nonverbal Sensitivity (PONS) test. The full test has been extensively validated in many different cultures, showing substantial correlations with a large range of outcome variables. The short multichannel version (64 items) described here correlates very highly with the full version and shows reasonable construct validity through significant correlations with other tests of emotion recognition ability. Based on these results, the role of nonverbal sensitivity as part of a latent trait of emotional competence is discussed and the MiniPONS is suggested as a convenient method to perform a rapid screening of this central socioemotional competence.

A multichannel discharge UV source

A source with a spark discharge at the atmospheric gas pressure is described. A multichannel version of the spark discharge from a single generator with the use of an inductive current divider is realized. The number of the discharge channels and geometry of their disposition can vary over a wide range, depending on the problems being solved.

Vibrational cross sections for positron scattering by nitrogen molecules

We present a systematic study of low-energy positron collision with nitrogen molecules. Vibrational elastic and excitation cross sections are calculated using the multichannel version of the continued fractions method in the close-coupling scheme for the positron incident energy up to $20$ eV. The interaction potential is treated within the static-correlation-polarization approximation. The comparison of our calculated data with existing theoretical and experimental results is encouraging.

Testing of a Prototype Lost α-Particle Diagnostic Utilizing an Imaging Bolometer

A multi-channel version of the multi foil thermal detector (MFTD) prototype has been developed and tested at the FNL ion accelerator in Tohoku University, which uses an imaging bolometer as a thermal sensor and 2-dimensional set of the foils with the different thicknesses as an energy discriminator for alphas. A Phoenix IR camera from FLIR Systems had been used for monitoring the temperature profile variations under the ion beam irradiation. The results obtained showed that the tested foils are applicable for the MFTD design.