Occurrence Statistics Research Articles

New symmetric key cipher capable of digraph to single letter conversion utilizing binary system

In this paper, a new Playfair cipher built on bits level symmetric key cryptographic was proposed for the purpose of converting pairs of letters (digraphs) into single letters. The proposed algorithm is capable to overcome many of the shortcoming and vulnerabilities that exist in the current classical version of Playfair algorithm. The Playfair cipher is exceedingly complex than a classical substitution cipher, but still simple to hack using automated tactics. It is famous as a digraph cipher because two letters are exchanged by other two letters. This destroys any solo letter occurrence statistics, but the digraph statistics still unaffected (frequencies of two letters). Unluckily letter pairs have a flatter distribution than the one letter frequencies, so this intricacy matters for solving the code using pen and paper procedures. The suggested encryption process is conducted as follows; letters are first arranged in a spiral manner in Polybius square, afterwards, each pair will be replaced utilizing before-after technique if we are arranging pairs horizontally and down-up technique (vertically). The former process produces pairs of Plaintext that will be converted to binary bit stream then will be divided over blocks with stable sizes. Bits of these blocks are taken from pairs then fit them into square matrix of suitable order to put the concept of row-wise and revers row-wise matrix. Bits of this matrix are split into 2x2 square matrixes. The sub-matrixes are formed 8 bits. Here the XNOR operation is taken into consideration for bitwise operation to generate the keys for decryption and produce the cipher-text.

Consideration of anthropogenic factors in boreal forest fire regime changes during rapid socio-economic development: case study of forestry districts with increasing burnt area in the Sakha Republic, Russia

This paper presents an original approach to characterizing historical fire regimes for regions with limited fire data. Fire variables were derived from satellite datasets and regional fire occurrence statistics. They defined the integral elements of a fire regime such as historical trends, spatiotemporal evolution, fire seasonality and causes. Temporal evolution was investigated based on a regime shift detection method developed by Rodionov while changes in the fire regime were analyzed for statistical significance using the Mann–Kendall trend test and Sen’s slope estimator. A descriptive analysis was performed to assess fire seasonality, causes, and together formed the basis for this methodology. We validated the proposed approach by assessing historical fire activity in the Sakha Republic (Yakutia), which is one of the most fire-prone regions of Russia. The assessment was conducted with data from the period of 1996–2018. We detected increases in historical fire activity as well as thresholds of change in the fire regime. Changes during the analysis period included lengthening of fire season, increased burned area extent, and extension of peak fire period. Overall, significant changes in the fire regime were detected in the regions strongly affected by warming and increasing anthropogenic alteration.

Multi magnetic states in Co/Cu multilayered cylindrical nanowires studied by combination of off-axis electron holography imaging and micromagnetic simulations

We report on a wide variety of magnetic states in Co/Cu multilayered nanocylinders grown by electrodeposition with different thicknesses of both elements. The remnant magnetic states in individual Co layers have quantitatively been determined at the nanoscale by micromagnetic reconstruction of the magnetic phase shift image obtained by electron holography. We demonstrate that the magnetization in the Co layers can present either uniform or vortex states. Also, different magnetic configurations can be observed within the same nanocylinder. In the case of vortices, the direction of the core can rotate almost at 90° from the nanocylinder axis for layers with an aspect ratio close to 1. We show that the occurrence of each magnetic configuration depends on the aspect ratio of the layers, the direction of magnetocrystalline anisotropy, and, in some cases, the interlayer dipolar coupling. Such a wide variety of magnetic states is observed due to lower values of the Co magnetic constants (magnetization, exchange, anisotropy) with respect to bulk, typical of the electrodeposition process in a single bath, and to the local geometrical variation of the layers. We also calculated the phase diagram of the remnant magnetic states in a single layer for various amplitudes and orientations of the magnetocrystalline anisotropy and different directions of the saturation field. In particular cases, these phase diagrams, in addition to statistics of occurrence of each kind of magnetic configurations in the multilayer and the application of a saturation field in different directions, allow for recovering information on the preferential orientation of the crystalline anisotropy.

Prospects of genomic resources available at the global databases for the flora of United Arab Emirates.

This article emphasizes available genomic resources at the global databases National Center for Biotechnology Information (NCBI) GenBank, Gramene and Phytozome for the selected 378 plant taxa of the United Arab Emirates (UAE). Germplasm of these species was collected and banked at the Sharjah Seed Bank and Herbarium (SSBH) along with their related information on habit, habitat and occurrence. The occurrence statistics exhibits almost 19.84% species under rare-to-very rare category, the GenBank search statistics for this category indicates 17.72% species as studied and 2.11% as not studied. Overall, from the global search statistics for 378 plant species, it seems that about 40 (10.58%) species remained unstudied. Most of the unstudied species were herbaceous plants belonging to the mountainous habitat. Moreover, full genomes were recorded for 7 species at NCBI GenBank, 2 species at Phytozome and 1 species at Gramene database. The local search statistics (for UAE) exhibits about 10.58% of the flora that still remained unstudied and only 11 (2.90%) of the recorded species were having genomic information at NCBI GenBank. It is necessary to prioritize studies on such species that could provide valuable insight on their genetic composition in order to understand their adaptation to the natural environment. At present, the SSBH is cataloguing UAE's flora using core barcode and assisted markers that could provide a robust DNA barcode library for native plants of UAE. Our study appeals researchers to recognize and prioritize the species that need attention to enrich their genomic resources at the global databases by supporting nucleotide libraries with their conspecifics. At present, genomic resources for UAE plant taxa are limited, but with the advent of low-cost sequencing technologies these resources would flourish in the near future. Nevertheless, the information generated through genomic studies could be utilized for conservation and management of threatened and endangered plant species, Crop Wild Relatives and medicinal plants. We hope this article will promote interest in conducting additional studies in genomics of desert plants by encouraging researchers to participate in this emerging field.

Mahonian STAT on rearrangement class of words

In 2000, Babson and Steingrímsson generalized the notion of permutation patterns to the so-called vincular patterns, and they showed that many Mahonian statistics can be expressed as sums of vincular pattern occurrence statistics. STAT is one of such Mahonian statistics discovered by them. In 2016, Kitaev and the third author introduced a words analogue of STAT and proved a joint equidistribution result involving two sextuple statistics on the whole set of words with fixed length and alphabet. Moreover, their computer experiments hinted at a finer involution on R(w), the rearrangement class of a given word w. We construct such an involution in this paper, which yields a comparable joint equidistribution between two sextuple statistics over R(w). Our involution builds on Burstein’s involution and Foata–Schützenberger’s involution that utilizes the celebrated RSK algorithm.

A novel high-performance holistic descriptor for face retrieval

Texture extraction-based classification has become the facto methodology applied in face recognition. Haralick feature extraction from gray-level co-occurrence matrix (GLCM) is one of the basic holistic studies that has inspired many face recognition algorithms. This paper presents a theoretically simple, yet efficient, holistic approach that utilizes the spatial relationships of the same pixel patterns occurring at different positions in an image rather than their occurrence statistics as applied in GLCM-based counterparts. The matrix holding the statistical values for the total displacement of the pixel patterns is called the gray-level total displacement matrix (GLTDM). Three approaches are proposed for feature extraction. In the first approach, classical Haralick features extraction is conducted. The second approach (D_GLTDM) utilizes the GLTDM directly as the feature vector rather than extra feature extraction process. In the last approach, principle component analysis (PCA) is used as the feature extraction method. Comprehensive simulations are conducted on images retrieved from the popular face databases, namely face94, ORL, JAFFE and Yale. The performance of the proposed method is compared with that of GLCM, local binary pattern and PCA used in the leading studies. The simulation results and their comparative analysis show that D_GLTDM exhibits promising results and outperforms the other leading methods in terms of classification accuracy.

Comparison of scenario‐neutral approaches for estimation of climate change impacts on flood characteristics

AbstractScenario‐neutral assessments of climate change impact on floods analyse the sensitivity of a catchment to a range of changes in selected meteorological variables such as temperature and precipitation. The key challenges of the approach are the choice of the meteorological variables and statistics thereof and how to generate time series representing altered climatologies of the selected variables. Different methods have been proposed to achieve this, and it remains unclear if and to which extent they result in comparable flood change projections. Here, we compare projections of annual maximum floods (AMFs) derived from three different scenario‐neutral methods for a prealpine study catchment. The methods chosen use different types of meteorological data, namely, observations, regional climate model output, and weather generator data. The different time series account for projected changes in the seasonality of temperature and precipitation, in the occurrence statistics of precipitation, and of daily precipitation extremes. Resulting change in mean AMF peak magnitudes and volumes differs in sign between the methods (range of −6% to +7% for flood peak magnitudes and −11% to +14% for flood volumes). Moreover, variability of projected peak magnitudes and flood volumes depends on method with one approach leading to a generally larger spread. The differences between the methods vary depending on whether peak magnitudes or flood volumes are considered and different relationships between peak magnitude and volume change result. These findings can be linked to differing flood regime changes among the three approaches. The study highlights that considering selected aspects of climate change only when performing scenario‐neutral studies may lead to differing representations of flood generating processes by the approaches and thus different quantifications of flood change. As each method comes with its own strengths and weaknesses, it is recommended to combine several scenario‐neutral approaches to obtain more robust results.

Внутренние волны на Кавказском и Крымском шельфах Черного моря (по летне-осенним наблюдениям 2011–2016 гг.)

The results of observations of internal waves on the Crimean and Caucasian shelves of the Black Sea conducted between 2011 and 2016 are analyzed and generalized. The measurements were carried out on moored stations equipped with chains of autonomous temperature sensors, as well as by vertical profiling of the water column with the miniSVP probe and the acoustic Doppler current profiler (ADCP). The observed internal waves are compared for three types of shelf: the shallow (Gelendzhik shelf), the shallow (offshore South Coast) and the sharp descent of depths (the Abkhazian shelf). Long-term observations of the field of internal waves on the Black Sea shelf confirm the almost constant presence of internal quasi-inertial oscillations of the thermocline, short-period internal waves with periods from one to tens of minutes are often recorded. On the Black Sea shelf, internal waves of the lower mode predominate, but waves of the second mode also occur. On the shelf with a sharp descent of depths, there are internal waves of maximum heights. Examples of recorded inertial and short-period internal waves are presented. The frequency spectra of internal waves are presented, as well as the statistics of occurrence and the estimation of the intermittency of inertial and short-period internal waves for the three shelf regions.

Global pentapeptide statistics are far away from expected distributions

The relationships between polypeptide composition, sequence, structure and function have been puzzling biologists ever since first protein sequences were determined. Here, we study the statistics of occurrence of all possible pentapeptide sequences in known proteins. To compensate for the non-uniform distribution of individual amino acid residues in protein sequences, we investigate separately all possible permutations of every given amino acid composition. For the majority of permutation groups we find that pentapeptide occurrences deviate strongly from the expected binomial distributions, and that the observed distributions are also characterized by high numbers of outlier sequences. An analysis of identified outliers shows they often contain known motifs and rare amino acids, suggesting that they represent important functional elements. We further compare the pentapeptide composition of regions known to correspond to protein domains with that of non-domain regions. We find that a substantial number of pentapeptides is clearly strongly favored in protein domains. Finally, we show that over-represented pentapeptides are significantly related to known functional motifs and to predicted ancient structural peptides.

WIND TURBINE MAINTENANCE. A REVIEW

Climatic change has taxed humanity in terms of the use of renewable energy in most countries around the world. In this context, installed wind power has recently increased at an almost exponential rate. Although there is still a large potential market that could be covered, minimizing costs has become a critical factor for a wind project to be financially justified and competitive. The present work is a bibliographical review of the primary strategies and methodologies used to reduce the cost of these activities while producing the maximum electricity from wind turbines. This review includes tabulated information on the types of faults, occurrence statistics, and associated costs and equipment suppliers for monitoring, detection, diagnosis and fault prediction and although most of it refers to onshore wind turbines, offshore wind turbines are also included in several parts. Research shows that in order to guarantee the reliability and economic feasibility of wind farms, the most used methodologies is CMS, which include vibration analysis, acoustic emission, ultrasonic testing techniques, thermography, oil analysis, structural health monitoring, optical fiber monitoring, strain measurement, radiographic inspection, power signal analysis. Currently, in addition to technical personnel, turbine operation and maintenance include, sensors, software, trucks, cranes, boats, helicopters, drones and smartphone applications. Keywords: wind turbines, maintenance strategies, cost, types of faults, condition monitoring system

A minimum in the latitude variation of spread-F at March equinox

This short paper presents the statistics of spread-F occurrence at four low-mid latitude locations (17.0° N, 21.2° N, 26.5° N and 36.5° N mag. lat.) in Japan longitude sector (~ 135° E) in March to April 2002, 2003 and 2006 (high, medium and low solar activity). The location of a spread-F minimum predicted by theoretical models is identified for the first time. The spread-F minimum occurs at the poleward side of the equatorial ionisation anomaly crest and shifts equatorward from ~ 25° N mag. lat. at high solar activity to below 17° N at low solar activity. The corresponding spread-F maximum occurring on the poleward side of the minimum also shifts equatorward from ~ 35° N (or beyond) at medium solar activity to 20°–25° N at low solar activity. The spread-F occurrence increases with decreasing solar activity at all locations especially at higher latitudes (> ~ 25° N) where there is almost no occurrence at high solar activity.

Simulating the exoplanet yield of a space-based mid-infrared interferometer based on Kepler statistics

Aims. We predict the exoplanet yield of a space-based mid-infrared nulling interferometer using Monte Carlo simulations. We quantify the number and properties of detectable exoplanets and identify those target stars that have the highest or most complete detection rate. We investigate how changes in the underlying technical assumptions and uncertainties in the underlying planet population impact the scientific return. Methods. We simulated 2000 exoplanetary systems, based on planet occurrence statistics from Kepler with randomly orientated orbits and uniformly distributed albedos around each of 326 nearby (d< 20 pc) stars. Assuming thermal equilibrium and blackbody emission, together with the limiting spatial resolution and sensitivity of our simulated instrument in the three specific bands 5.6, 10.0, and 15.0 μm, we quantified the number of detectable exoplanets as a function of their radii and equilibrium temperatures. Results. Approximately [see formula in PDF] exoplanets, with radii 0.5 REarth ≤ Rp ≤ 6 REarth, were detected in at least one band and half were detected in all three bands during ~0.52 years of mission time assuming throughputs 3.5 times worse than those for the James Webb Space Telescope and ~40% overheads. Accounting for stellar leakage and (unknown) exozodiacal light, the discovery phase of the mission very likely requires 2−3 years in total. The uncertainties in planet yield are dominated by uncertainties in the underlying planet population, but the distribution of the Bond albedos also has a significant impact. Roughly 50% of the detected planets orbit M stars, which also have the highest planet yield per star; the other 50% orbit FGK stars, which show a higher completeness in the detectability. Roughly 85 planets could be habitable (0.5 REarth ≤ Rp ≤ 1.75 REarth and 200 K ≤ Teq ≤ 450 K) and are prime targets for spectroscopic observations in a second mission phase. Comparing these results to those of a large optical/near-infrared telescope, we find that a mid-infrared interferometer would detect more planets and the number of planets depends less strongly on the wavelength. Conclusions. An optimized space-based nulling interferometer operating in the mid-infrared would deliver an unprecedented dataset for the characterization of (small) nearby exoplanets including dozens of potentially habitable worlds.

Frequency-Domain Proof of the Existence of Atomic-Scale SERS Hot-Spots.

The existence of sub-nanometer plasmonic hot-spots and their relevance in spectroscopy and microscopy applications remain elusive despite a few recent theoretical and experimental evidence supporting this possibility. In this Letter, we present new spectroscopic evidence suggesting that Angstrom-sized hot-spots exist on the surfaces of plasmon-excited nanostructures. Surface-enhanced Raman scattering (SERS) spectra of 4,4'-biphenyl dithiols placed in metallic junctions show simultaneously blinking Stokes and anti-Stokes spectra, some of which exhibit only one prominent vibrational peak. The activated vibrational modes were found to vary widely between junction sites. Such site-specific, single-peak spectra could be successfully modeled using single-molecule SERS induced by a hot-spot with a diameter no larger than 3.5 Å, located at the specific molecular sites. Furthermore, the model, which assumes the stochastic creation of hot-spots on locally flat metallic surfaces, consistently reproduces the intensity distributions and occurrence statistics of the blinking SERS peaks, further confirming that the sources of the hot-spots are located on the metallic surfaces. This result not only provides compelling evidence for the existence of Angstrom-sized hot-spots but also opens up the new possibilities for the vibrational and electronic control of single-molecule photochemistry and real-space visualization of molecular vibration modes.

Evolution of statistically inhomogeneous degenerate water wave quartets.

A discretized equation for the evolution of random surface wave fields on deep water is derived from Zakharov's equation, allowing for a general treatment of the stability and long-time behaviour of broad-banded sea states. It is investigated for the simple case of degenerate four-wave interaction, and the instability of statistically homogeneous states to small inhomogeneous disturbances is demonstrated. Furthermore, the long-time evolution is studied for several cases and shown to lead to a complex spatio-temporal energy distribution. The possible impact of this evolution on the statistics of freak wave occurrence is explored.This article is part of the theme issue 'Nonlinear water waves'.

Occurrence statistics of Spread F at Ilorin

This study is the first of its kind aimed at the statistical study of the occurrence of Equatorial Spread-F (ESF) using ionosonde data obtained with the aid of Digisonde (DPS-4) during the year 2010 at Ilorin (Geo. Lat. 8.470N, Long. 4.680E, and Dip. Lat. 7.8670S): an equatorial station in the African sector. The study revealed that the ionosphere over Ilorin exhibit three types of equatorial spread-F i.e. frequency spread F (FSF), range spread F (RSF) and mixed frequency (MSF). ESF is observed to be a post-sunset and nighttime phenomenon; occurring within the hours of 2000LT and 0700LT with the range of hmF2 being between 230 and 405 km. ESF grows during the post-sunset periods and decays towards the sunrise hour. ESF is observed to be monthly/seasonal dependent. Occurrence of ESF is observed to be predominant during the equinox months. The results further show that RSF type is the most prevalent at this station.

Evaluation of multiple stochastic rainfall generators in diverse climatic regions

Long term synthetic precipitation data are useful for water resources planning and management. Commonly stochastic weather generator (SWG) models are useful to produce synthetic time series of unlimited length of weather data based on the statistical characteristics of observed weather at a given location. However, it is difficult to find a single model which works best for all weather (climate) patterns. The objective of this study is to evaluate five different SWG models namely CLIGEN, ClimGen, LARS-WG, RainSim and WeatherMan to generate precipitation at three diverse climatic regions: a Mediterranean climate of western USA, temperate climate of eastern Australia and tropical monsoon region in northern Vietnam. The performance of SWG models to generate precipitation characteristics (i.e., precipitation occurrence; wet and dry spell; and precipitation intensity on wet days) varies between three selected climatic regimes. It was observed that the second order Markov chain (ClimGen and WeatherMan) performed well for all three selected regions in generating precipitation occurrence statistics. All models are able to simulate the ratio of wet/dry spell lengths with respect to observed precipitation. The RainSim performed well in reproducing wet/dry spell lengths in comparison to other models for wetter regions in Australia and Vietnam. ClimGen and WeatherMan are the two best models in simulating precipitation in the western USA, followed by CLIGEN and LARS. Similarly, ClimGen and WMAN are the two best models for synthetic precipitation generation for eastern Australian and northern Vietnam stations, but CLIGEN performs poorly over these regions. All SWG model performed differently with respect to climatic regimes, therefore careful validation is required depending on the weather pattern as well as its application in different water resources sectors. Although our findings are preliminary in nature, however, in order to generalize the performance of SWG’s in a given climate type, it is recommended that more number of stations needs to be evaluated in future studies.

Data-adaptive harmonic spectra and multilayer Stuart-Landau models.

Harmonic decompositions of multivariate time series are considered for which we adopt an integral operator approach with periodic semigroup kernels. Spectral decomposition theorems are derived that cover the important cases of two-time statistics drawn from a mixing invariant measure. The corresponding eigenvalues can be grouped per Fourier frequency and are actually given, at each frequency, as the singular values of a cross-spectral matrix depending on the data. These eigenvalues obey, furthermore, a variational principle that allows us to define naturally a multidimensional power spectrum. The eigenmodes, as far as they are concerned, exhibit a data-adaptive character manifested in their phase which allows us in turn to define a multidimensional phase spectrum. The resulting data-adaptive harmonic (DAH) modes allow for reducing the data-driven modeling effort to elemental models stacked per frequency, only coupled at different frequencies by the same noise realization. In particular, the DAH decomposition extracts time-dependent coefficients stacked by Fourier frequency which can be efficiently modeled-provided the decay of temporal correlations is sufficiently well-resolved-within a class of multilayer stochastic models (MSMs) tailored here on stochastic Stuart-Landau oscillators. Applications to the Lorenz 96 model and to a stochastic heat equation driven by a space-time white noise are considered. In both cases, the DAH decomposition allows for an extraction of spatio-temporal modes revealing key features of the dynamics in the embedded phase space. The multilayer Stuart-Landau models (MSLMs) are shown to successfully model the typical patterns of the corresponding time-evolving fields, as well as their statistics of occurrence.

The Most Frequent Complications after Cranio-cerebral Injuries in Children Hospitalized at the Department of Paediatric Surgery

Introduction. Head injuries among children are the most frequent cause of hospitalization. Posttraumatic cranio-cerebral damage in children can lead to the occurrence of partial physical and mental disorders and in some cases prevent proper functioning of the organism.Aim. The goal of this research was to study the frequency of complication occurrence among children after cranio-cerebral traumas as well as to determine the character they most often take on.Material and Methods. The study was conducted at Paediatric Surgery Outpatient Clinic at the St. Luke District Hospital in Tarnów. It included 150 children hospitalized at the Department of Paediatric Surgery within the period from July to October 2015 due to sustained cranio-cerebral injuries ranging from minor and moderate to severe.Results. The most frequent causes of sustained injuries were sport-related ones as well as those resulting from a fall from height. Among the vast majority of the children with an injury (95%) an early posttraumatic complication occurred in the form of concussion. The most often demonstrated early side symptoms of sustained injury included: emesis (80%), poor well-being and headache (69%) as well as drowsiness and changes in behavior (53%). The most frequent late complication was posttraumatic cerebrasthenia characterized by headache, memory disorders and problems with concentration. In the study group of children with an injury, poor well-being and headache were experienced by approximately 50% of the patients one week following the hospital discharge and by approximately 20% one month after the discharge.Conclusions. The demonstrated early and late side symptoms observed among children with an injury, when properly treated and controlled, with time tend to decrease and thus contribute to comforting statistics of occurrence of a small number of serious complications following minor and moderate to severe cranio-cerebral injuries. (JNNN 2017;6(3):107–113)

Passive in-vehicle driver breath alcohol detection using advanced sensor signal acquisition and fusion

ABSTRACTObjective: The research objective of the present investigation is to demonstrate the present status of passive in-vehicle driver breath alcohol detection and highlight the necessary conditions for large-scale implementation of such a system. Completely passive detection has remained a challenge mainly because of the requirements on signal resolution combined with the constraints of vehicle integration. The work is part of the Driver Alcohol Detection System for Safety (DADSS) program aiming at massive deployment of alcohol sensing systems that could potentially save thousands of American lives annually.Method: The work reported here builds on earlier investigations, in which it has been shown that detection of alcohol vapor in the proximity of a human subject may be traced to that subject by means of simultaneous recording of carbon dioxide (CO2) at the same location. Sensors based on infrared spectroscopy were developed to detect and quantify low concentrations of alcohol and CO2. In the present investigation, alcohol and CO2 were recorded at various locations in a vehicle cabin while human subjects were performing normal in-step procedures and driving preparations. A video camera directed to the driver position was recording images of the driver's upper body parts, including the face, and the images were analyzed with respect to features of significance to the breathing behavior and breath detection, such as mouth opening and head direction.Results: Improvement of the sensor system with respect to signal resolution including algorithm and software development, and fusion of the sensor and camera signals was successfully implemented and tested before starting the human study. In addition, experimental tests and simulations were performed with the purpose of connecting human subject data with repeatable experimental conditions. The results include occurrence statistics of detected breaths by signal peaks of CO2 and alcohol. From the statistical data, the accuracy of breath alcohol estimation and timing related to initial driver routines (door opening, taking a seat, door closure, buckling up, etc.) can be estimated.The investigation confirmed the feasibility of passive driver breath alcohol detection using our present system. Trade-offs between timing and sensor signal resolution requirements will become critical. Further improvement of sensor resolution and system ruggedness is required before the results can be industrialized.Conclusions: It is concluded that a further important step toward completely passive detection of driver breath alcohol has been taken. If required, the sniffer function with alcohol detection capability can be combined with a subsequent highly accurate breath test to confirm the driver's legal status using the same sensor device. The study is relevant to crash avoidance, in particular driver monitoring systems and driver–vehicle interface design.

Detection of vortex coherent structures in superfluid turbulence

Filamentary regions of high vorticity irregularly form and disappear in the turbulent flows of classical fluids. We report an experimental comparative study of these so-called “coherent structures” in a classical vs. quantum fluid, using liquid helium with a superfluid fraction varied from 0% up to 83%. The low-pressure core of the vorticity filaments is detected by pressure probes located on the sidewall of a 78-cm-diameter von Kármán cell driven up to record turbulent intensity . The statistics of occurrence, magnitude and relative distribution of the filaments in a classical fluid are found indistinguishable from their superfluid counterpart, namely the bundles of quantized vortex lines. This suggests that the internal structure of vortex filaments, as well as their dissipative properties have a negligible impact on their macroscopic dynamics, such as lifetime and intermittent properties.