Wide Range Of Distances Research Articles

Ab initioand analytical studies of the spin-orbit coupling in heteronuclear alkali-metal dimersAB(A, B= Li, Na, K, Rb) at long ranges

The spin-orbit (SO) coupling matrix elements between the excited states of the lightest heteronuclear alkali metal dimers AB(A, B = Li, Na, K, Rb) converging to the first three dissociation limits were evaluated by employing the quasirelativistic electronic wave functions in a wide range of interatomic distances, $R$. The inner-shell electrons of alkali atoms were described using nonempirical shape-consistent effective core potentials. To take the core-valence correlation effects into account, core polarization potentials for each atom were implemented. Dynamical correlation was introduced through the multireference configuration interaction method, which was applied to two valence electrons keeping all subvalence electrons frozen. The reliability of the derived SO functions is accessed through comparison, wherever possible, with their preceding theoretical and experimental counterparts. The ab initio SO matrix elements were approximated beyond the LeRoy radius using the formula: ${\ensuremath{\xi}}_{if}^{\text{SO}}(R)=\ensuremath{\alpha}+{\ensuremath{\beta}}_{if}^{[k]}/{R}^{k}$, where (1) $k=6$ and $\ensuremath{\alpha}={\ensuremath{\xi}}_{n^{2}\mathrm{P}}^{\text{SO}}$ is the SO splitting of the atom $\mathrm{A}(n^{2}\mathrm{P}$) for the states of the AB molecule converging to the same $\mathrm{A}({n}_{\mathrm{A}}^{2}\mathrm{P}$) + $\mathrm{B}({n}_{\mathrm{B}}^{2}\mathrm{S}$) dissociation limit, and (2) $k=3$ and $\ensuremath{\alpha}=0$ for the molecular $i$ and $f$ states converging to the $\mathrm{A}({n}_{\mathrm{A}}^{2}\mathrm{P})+\mathrm{B}({n}_{\mathrm{B}}^{2}\mathrm{S})$ and $\mathrm{A}({n}_{\mathrm{A}}^{2}\mathrm{S})+\mathrm{B}({n}_{\mathrm{B}}^{2}\mathrm{P}$) atomic thresholds, respectively. A theoretical justification of these formulas was derived from the multipole expansion of the molecular SO operator in terms of the inverse powers of the internuclear distance and of products of operators acting on the electronic coordinates of the atoms A and B.

Quantitative Schlieren Diagnostic Applied to a Nitrogen Thermal Plasma Jet

A quantitative interpretation of the schlieren technique applied to an atmospheric pressure, vortex-stabilized nitrogen thermal plasma jet generated in a direct-current nontransferred arc plasma torch (nitrogen gas flow rate of 25 NL/min, power level of 15 kW), discharging into ambient air is reported. A $Z$ -type, two-mirror schlieren system was used in the research. The technique allowed inferring the temporally averaged values of the temperatures and densities of different species present in the plasma jet in a wide range of radial and axial distances. Deviations from kinetic equilibrium in the calculation of the plasma refractive index were accounted for, but maintaining the assumption of the local chemistry equilibrium. The influence of several assumptions on the accuracy of the measurements was considered. The results have shown that for a distance of 3.5-mm downstream from the nozzle exit, the kinetic equilibrium is realized (being both electron and gas temperatures values around 11 000 K), but noticeable deviation from kinetic equilibrium appears toward the jet border. On the other hand, a marked deviation from the kinetic equilibrium was found in the whole far field of the plasma jet, where the electron temperature remains still quite high (about 10 000 K at 30-mm downstream of the nozzle exit), well decoupled from the gas temperature (about 7000 K at the same distance). The obtained results are in reasonable good agreement with those previously reported by some of the authors by using a double floating probe method in the same plasma torch.

On the Spraying Modality of Liquids by Pyroelectrohydrodynamics

We present for the first time an investigation on the spraying modality for the pyroelectrohydrodynamic (pyro-EHD) system. We show that the pyro-EHD spray (p-Spray) works well in the range from far field (d > 10 mm) to near field (d < 2 mm) without the need of external voltage and without the needs to change the experimental apparatus in that wide range of distances. Because the proposed method works without a counter electrode, no limitations are connected with the geometric shape of the substrate on which the spray coating is deposited. We report on several examples of the formation of disperse sprayed droplets, whose size can be varied between hundreds of micrometers and hundreds of nanometers, as well as on the production of sprayed pattern footpaths. The results reported here demonstrate the direct writing of spray patterns of nano/microdroplets with different materials in a very wide range, that is, from low- to high-viscous liquid solutions. Finally, as an example of application, we show the use of the p-Spray for the fabrication of silver-coated devices showing antimicrobial properties of the pattern produced by the p-Spray through a customizable and environmental friendly approach.

Heat Exchange in a Cylindrical Channel with Stabilized Laminar Fluid Flow

Based on the determination of the temperature perturbation front and additional boundary conditions, an approximate analytical solution is obtained for the stationary heat exchange problem when fluid flows in a cylindrical channel with a constant parabolic velocity profile (the Gretz–Nusselt problem), which allows us to investigate the temperature distribution in the fluid in a wide range of distances from the pipe inlet, including small and very small distances. Based on the data of numerical calculations of temperature change at a certain value of the spatial variable using the solution obtained by solving the inverse heat conduction problem, the Peclet number was found (in the case where it is unknown in the solution obtained), from which we can determine the velocity profile and the flow rate of the liquid. Graphs of the distribution of isotherms and the their velocities in space over time are plotted.

Hopping parameters for tunnel coupling in 2D materials

Using Bardeen’s approach and orbital wave functions obtained by the algorithm of Herman and Skillman, we calculated interatomic matrix elements for tunnel interaction between the atoms from the set of B, C, N, Si, P, S, Ti, V, Se, Mo, Te and W, which constitute many 2D materials. In a wide range of interatomic distances, these values are approximated by simple functions with a small set of parameters. The results are presented in reference tables. These results will be useful for describing different tunnel phenomena in low-dimensional materials using the tight-binding approach.

Hydrodynamic Performance Analysis of the Vertical Axis Twin-Rotor Tidal Current Turbine

The goal of this manuscript is to investigate the influence of relative distance between the twin rotors on the hydrodynamic performance of the vertical axis twin-rotor tidal current turbine. Computational fluid dynamics (CFD) simulations based on commercial software ANSYS-CFX have been performed to enhance the understanding of interactions between the twin-rotors. The interactions between the twin rotors are known to have increased the power output efficiency as a whole, and it is, therefore, of great significance to undertake deeper research. The simulation results are found to be consistent with similar research results in the literature in some aspects. The simulation results of stand-alone turbine and twin rotors are compared from three different aspects, including blade forces, power output efficiency and wake flow field. The results showed that the cyclic variations tendency of blade force coefficients of twin rotors is close to that of the stand-alone turbine. The average power output efficiency of the twin-rotors system is higher than that of the stand-alone turbine. The interactions between the turbines increase the power output of the twin turbine system as whole in a wide relative distance range. However, smaller relative distance between the twin rotors does not mean a bigger power output efficiency of such a system. The power out efficiency of such a system would decrease when the relative distance between the twin rotors exceeds the critical point. The power output of the twin rotors reaches the peak value when the ratio between the two main axis distance and diameter of the turbine is around 9/4. This research can provide a reference for the design and development of larger tidal power stations.

The 55 Cancri system reassessed

Orbiting a bright, nearby star the 55 Cnc system offers a rare opportunity to study a multiplanet system that has a wide range of planetary masses and orbital distances. Using two decades of photometry and spectroscopy data, we have measured the rotation of the host star and its solar-like magnetic cycle. Accounting for this cycle in our velocimetric analysis of the system allows us to revise the properties of the outermost giant planet and its four planetary companions. The innermost planet 55 Cnc e is an unusually close-in super-Earth, whose transits have allowed for detailed follow-up studies. Recent observations favor the presence of a substantial atmosphere yet its composition, and the nature of the planet, remain unknown. We combined our derived planet mass (Mp = 8.0 ± 0.3 MEarth) with refined measurement of its optical radius derived from HST/STIS observations (Rp = 1.88 ± 0.03 REarth over 530–750 nm) to revise the density of 55 Cnc e (ρ = 6.7 ± 0.4 g cm−3). Based on these revised properties we have characterized possible interiors of 55 Cnc e using a generalized Bayesian model. We confirm that the planet is likely surrounded by a heavyweight atmosphere, contributing a few percents of the planet radius. While we cannot exclude the presence of a water layer underneath the atmosphere, this scenario is unlikely given the observations of the planet across the entire spectrum and its strong irradiation. Follow-up observations of the system in photometry and in spectroscopy over different time-scales are needed to further investigate the nature and origin of this iconic super-Earth.

Thermal analysis of triple and quadruple windows using partitioning radiant energy veils™ with different physical and optical properties

One of the key performance parameters for any energy efficient window product is the center of glass U-value or thermal transmittance. This paper presents a new methodology to compute the thermal performance of fenestration systems incorporating partitioning radiant energy veils™ between two panes of a window. A conduction heat transfer model is used for glazing layers coupled with radiation and convection models at the layer boundary surfaces. Partitioning radiant energy veils™ are treated as individual layers with effective radiative properties. The effect of a wide range of optical properties, pane thicknesses, pane distances and different gas fill types on thermal transmittance of the window are considered. The novel use of partitioning radiant energy veils™, having application specific properties, between two panes of a window allows to customize the thermal performance of a triple or quadruple window. It is shown that using one or two internal partitioning layers, with appropriate pane/inter-layer distances and high spectrally reflective metallo-dielectric coated layers, results in highly enhanced U-Values.

Simulation Model of a 2-kW IPT Charger with Phase-Shift Control: Validation through the Tuning of the Coupling Factor

When applied to road vehicle electrification, inductive power transfer (IPT) technology has the potential to boost the transition from combustion engines to electric motors powered by a battery pack. This work focuses on the validation of a PSpice circuit model developed as a replica of a 2-kW IPT prototype with series-series compensation operating at 18.65 kHz. The laboratory prototype has the three stages commonly found in an IPT system: an inverter, controlled by the phase-shift technique, a coil coupling and a load. Simulations were run with the circuit model for three different distances between the two coils of the inductive coupling, all of which are of interest for practical chargers: 125, 150 and 175 mm. The validation approach was based on tuning the magnetic coupling factor for each distance and a set of ten load resistances, until the best match between the simulated and the experimental peak currents supplied by the inverter was found in each case. The coupling factors obtained from the simulation work are in good agreement with their experimental counterparts for the three distances, provided the duty cycle of the inverter output voltage is not too small. The circuit model developed is, therefore, able to reproduce the behavior of the laboratory prototype with sufficient accuracy over a wide range of distances between coils and loading conditions.

A Vision-Based Approach to UAV Detection and Tracking in Cooperative Applications.

This paper presents a visual-based approach that allows an Unmanned Aerial Vehicle (UAV) to detect and track a cooperative flying vehicle autonomously using a monocular camera. The algorithms are based on template matching and morphological filtering, thus being able to operate within a wide range of relative distances (i.e., from a few meters up to several tens of meters), while ensuring robustness against variations of illumination conditions, target scale and background. Furthermore, the image processing chain takes full advantage of navigation hints (i.e., relative positioning and own-ship attitude estimates) to improve the computational efficiency and optimize the trade-off between correct detections, false alarms and missed detections. Clearly, the required exchange of information is enabled by the cooperative nature of the formation through a reliable inter-vehicle data-link. Performance assessment is carried out by exploiting flight data collected during an ad hoc experimental campaign. The proposed approach is a key building block of cooperative architectures designed to improve UAV navigation performance either under nominal GNSS coverage or in GNSS-challenging environments.

Long Range Guided Wave Propagation Experimental Analysis in Overhead Power Line Cables under Different Axial Load Levels.

Over the past hundred years, overhead power line cables have been widely installed around the world. These cables are commonly exposed to adverse environmental conditions that can affect their structural integrity and over time, could lead to the complete failure of the structure. This research presents the use of guided waves for the inspection of the structural integrity of the overhead power line cables. The proposed system relies on permanently installing on power line cables a multiple transducers collar as well as a pulse receiver. The system is installed on the cable and performs automated regular inspections. One of the key features of this technique is its ability to inspect a long section of the cable from a single inspection point. To achieve this objective, the wave propagation features have been studied in a wide range of frequencies in 50m long cables, where different collar configurations were used. In addition, power line cables, when installed, are subjected to different axial loads depending on the type of cable and the distance between pylons. The effects of the axial load on the wave propagation have been studied. To assess the defect detection capabilities of the system over a wide range of distances without damaging the cable samples, a metallic clamp is used to introduce a cross-section change on the cables, simulating the effect of a fault on the cables (i.e. corrosion). The experimental results show the highly attenuative effect of the axial load on the wave propagation for most of the frequency spectrum. However, it was found that at low frequencies the system performance allowed the inspection of long distances. This was further proven with the experimental results for the clamp detection study.

The Gaia-ESO Survey: The N/O abundance ratio in the Milky Way

Context. The abundance ratio N/O is a useful tool to study the interplay of galactic processes, for example star formation efficiency, timescale of infall, and outflow loading factor. Aims. We aim to trace log(N/O) versus [Fe/H] in the Milky Way and to compare this ratio with a set of chemical evolution models to understand the role of infall, outflow, and star formation efficiency in the building up of the Galactic disc. Methods. We used the abundances from IDR2-3, IDR4, IDR5 data releases of the Gaia-ESO Survey both for Galactic field and open cluster stars. We determined membership and average composition of open clusters and we separated thin and thick disc field stars. We considered the effect of mixing in the abundance of N in giant stars. We computed a grid of chemical evolution models, suited to reproduce the main features of our Galaxy, exploring the effects of the star formation efficiency, infall timescale, and differential outflow. Results. With our samples, we map the metallicity range −0.6 ≤ [Fe/H] ≤ 0.3 with a corresponding −1.2 ≤ log(N/O) ≤ −0.2, where the secondary production of N dominates. Thanks to the wide range of Galactocentric distances covered by our samples, we can distinguish the behaviour of log(N/O) in different parts of the Galaxy. Conclusions. Our spatially resolved results allow us to distinguish differences in the evolution of N/O with Galactocentric radius. Comparing the data with our models, we can characterise the radial regions of our Galaxy. A shorter infall timescale is needed in the inner regions, while the outer regions need a longer infall timescale, coupled with a higher star formation efficiency. We compare our results with nebular abundances obtained in MaNGA galaxies, finding in our Galaxy a much wider range of log(N/O) than in integrated observations of external galaxies of similar stellar mass, but similar to the ranges found in studies of individual H II regions.

Planet Formation: An Optimized Population-synthesis Approach

Abstract The physics of planet formation is investigated using a population synthesis approach. We develop a simple model for planetary growth including pebble and gas accretion, as well as orbital migration in an evolving protoplanetary disk. The model is run for a population of 2000 stars with a range of disk masses, disk radii, and initial protoplanet orbits. The resulting planetary distribution is compared with the observed population of extrasolar planets, and the model parameters are improved iteratively using a particle swarm optimization scheme. The characteristics of the final planetary systems are mainly controlled by the pebble isolation mass, which is the mass of a planet that perturbs nearby gas enough to halt the inward flux of drifting pebbles and stop growth. The pebble isolation mass increases with orbital distance such that giant planet cores can only form in the outer disk. Giants migrate inward, populating a wide range of final orbital distances. The best model fits have large initial protoplanet masses, short pebble drift timescales, low disk viscosities, and short atmospheric cooling times, all of which promote rapid growth. The model successfully reproduces the observed frequency and distribution of giant planets and brown dwarfs. The fit for super-Earths is poorer for single-planet systems, but improves steadily when more protoplanets are included. Although the study was designed to match the extrasolar planet distribution, analogs of the solar system form in 1–2% of systems that contain at least four protoplanets.

Bottom-laid targets imaging and classification using a synthetic circular array

Detection and classification of bottom-laid targets in littoral area represents a serious problem for the navies of the world. It has been shown based on past acoustic research that the backscattered field carries a lot of information about the subject in terms of frequency and angular distribution if ensonified over a wide range of distance and can thus be used to different a mine from a stone or one type of mine from the other, referred to as acoustic color image. A circular array is more advantageous compared to a planar array as circular patterns maximize the aperture，and due to its high angular resolution, one can search and classify multiple targets at the same time. While it is difficult to deploy a large circular array since one does not know where is the target and the circular array needs to have a large diameter. Therefore, in this work, one will demonstrate effective bottom-laid targets imaging and classification using a synthetic circular array, which is created by a towed line array. We will study the concept of the proposed system and make simplified assumptions in order to obtain a crude estimate of the system performance.Detection and classification of bottom-laid targets in littoral area represents a serious problem for the navies of the world. It has been shown based on past acoustic research that the backscattered field carries a lot of information about the subject in terms of frequency and angular distribution if ensonified over a wide range of distance and can thus be used to different a mine from a stone or one type of mine from the other, referred to as acoustic color image. A circular array is more advantageous compared to a planar array as circular patterns maximize the aperture，and due to its high angular resolution, one can search and classify multiple targets at the same time. While it is difficult to deploy a large circular array since one does not know where is the target and the circular array needs to have a large diameter. Therefore, in this work, one will demonstrate effective bottom-laid targets imaging and classification using a synthetic circular array, which is created by a towed line array. We will...

Experimental observations and numerical modeling of lipid-shell microbubbles with stone targeting moieties for minimally-invasive treatment of urinary stones

Products incorporating stone-targeting microbubbles have recently entered human clinical trials as a new minimally-invasive approach to treat urinary stones. Lipid-shell, gas-core microbubbles can be introduced into the urinary tract through a catheter. Calcium-binding moieties incorporated into the lipid shell can facilitate binding to stones. The microbubbles can be excited by an extracorporeal source of low-intensity ultrasound. Alternatively, the microbubbles can be excited by an intraluminal source, such as a fiber-optic laser. With either excitation technique, stone-targeting microbubbles can significantly increase rates of erosion, pitting, and fragmentation of stones, as has recently been reported for in-vitro experiments with synthetic stones [Wiener et al., J. Urology, v.199, no.4S, e322 (2018)]. We report here on new experiments using high-speed photography to characterize microbubbles expansion of cracks within a stone and resultant breaking-off of stone fragments. Numerical modeling shows that the direction of microjets produced by collapsing stone-bound microbubbles depends strongly on bubble shape and stand-off distance. For a wide range of stand-off distances and bubble shapes, microbubble collapse is associated with pressure increases of some two orders of magnitude compared to the excitation source pressures. This in-vitro study provides key insights into the use of stone-targeting microbubbles in treatment of urinary stones.

Relating the H i gas structure of spiral discs to passing satellites

We extend the work of Chang & Chakrabarti (2011) to find simple scaling relations between the density response of the gas disk of a spiral galaxy and the pericenter distance and mass ratio of a perturbing satellite. From the analysis of results from a test particle code, we obtained a simple scaling relation for the density response due to a single satellite interacting with a galactic disk, over a wide range of satellite masses and pericenter distances. We have also explored the effects of multiple satellites on the galactic disk, focusing on cases that are commonly found in cosmological simulations. Here, we use orbits for the satellites that are drawn from cosmological simulations. For these cases, we compare our approximate scaling relations to the density response generated by satellites, and find that for two satellite interactions, our scaling relations approximately recover the response of the galactic disk. We have also examined the observed HI data in the outskirts of several spiral galaxies from the THINGS sample and compared the observed perturbations to that of cosmological simulations and our own scaling relations. While small perturbations can be excited by satellites drawn from cosmological simulations, we find that large perturbations (such as those that are seen in some THINGS galaxies like M51) are not recovered by satellites drawn from cosmological simulations that are similar to Milky Way galaxies.

Developments in the Biomechanics and Equipment of Olympic Cross-Country Skiers.

Here, our aim was to describe the major changes in cross-country (XC) skiing in recent decades, as well as potential future developments. XC skiing has been an Olympic event since the very first Winter Games in Chamonix, France, in 1924. Over the past decades, considerable developments in skiing techniques and improvements in equipment and track preparation have increased skiing speed. In contrast to the numerous investigations on the physiological determinants of successful performance, key biomechanical factors have been less explored. Today’s XC skier must master a wide range of speeds, terrains, and race distances and formats (e.g., distance races with individual start, mass-start or pursuit; knock-out and team-sprint; relays), continuously adapting by alternating between various sub-techniques. Moreover, several of the new events in which skiers compete head-to-head favor technical and tactical flexibility and encourage high-speed techniques (including more rapid development of propulsive force and higher peak forces), as well as appropriate training. Moreover, the trends toward more extensive use of double poling and skiing without grip wax in classical races have given rise to regulations in connection with Olympic distances that appear to have preserved utilization of the traditional classical sub-techniques. In conclusion, although both XC equipment and biomechanics have developed significantly in recent decades, there is clearly room for further improvement. In this context as well, for analyzing performance and optimizing training, sensor technology has a potentially important role to play.

Clock errors in land and ocean bottom seismograms: high-accuracy estimates from multiple-component noise cross-correlations

Many applications in seismology rely on the accurate absolute timing of seismograms. However, both seismological land stations and ocean bottom seismometers (OBSs) can be affected by clock errors, which cause the absolute timing of seismograms to deviate from a highly accurate reference time signal, usually provided by GPS satellites. Timing problems can occur in land stations when synchronization with a GPS signal is temporarily or permanently lost. This can give rise to complicated, time-dependent clock drifts relative to GPS time, due to varying environmental conditions. Seismometers at the ocean bottom cannot receive GPS satellite signals, but operate in more stable ambient conditions than land stations. The standard protocol is to synchronize an OBS with a GPS signal immediately before deployment and after recovery. The measured timing deviation, called 'skew', is assumed to have accumulated linearly over the deployment interval, an assumption that is plausible but usually not verifiable. In recent years, cross-correlations of ambient microseismic noise have been put to use for correcting timing errors, but have been limited to interstation distances of at most a few tens of kilometres without reducing the temporal resolution. We apply noise cross-correlations to the evaluation of clock errors in four broad-band land stations and 53 wideband and broad-band OBSs, which were installed on and around the island of La Reunion in the western Indian Ocean during the RHUM-RUM (Reunion Hotspot and Upper Mantle-Reunions Unterer Mantel) experiment. We correlate all three seismic components, plus a hydrophone channel in OBS stations. Daily cross-correlation functions are derived for intermediate distances (similar to 20 km) for land-to-land station pairs;stable, 10 d stacks are obtained for very large interstation distances up to > 300 km for land-to-OBS and OBS-to-OBS configurations. Averaging over multiple station pairs, and up to 16 component pairs per station, improves the accuracy of the method by a factor of four compared to the single-channel approaches of prior studies. The timing accuracy of our method is estimated to be similar to 20 ms standard deviation or one sample at a sampling rate of 50 Hz. In land stations, nonlinear clock drifts and clock jumps of up to 6 min are detected and successfully corrected. For 52 out of 53 OBSs, we successfully obtain drift functions over time, which validate the common assumption of linear clock drift. Skew values that were available for 29 of these OBSs are consistent with our independent estimates within their observational error bars. For 23 OBSs that lacked skew measurements, linear OBS clock drifts range between 0.2 and 8.8 ms d(-1). In addition to linear drift, three OBSs are affected by clock jumps of similar to 1 s, probably indicating a missing sample problem that would otherwise have gone undetected. Thus we demonstrate the routine feasibility of high-accuracy clock corrections in land and OBSs over a wide range of interstation distances.

AUTOMATION OF VEHICLE PLATE NUMBERS IDENTIFICATION ON ONE-ASPECT IMAGES

The subject matter of the article is the method of automating the identification of vehicle plate numbers based on the processing of one-aspect images obtained using video recording means. The goal is to provide automation of the process of identifying vehicle plate numbers within a wide range of changing the viewing angles and the levels of illumination. The task is formulation of the method of automated identification of vehicle plate numbers on one-aspect images, which are obtained by means of video fixation within wide limits of changing both the viewing angles and the levels of illumination. Analysis of the problems of methods and algorithms of automated detection and recognition of vehicle plate numbers has shown that it is most promising to use flexible algorithms that adapt to the changing conditions of observation of traffic control devices. One of the promising technologies for implementing such algorithms is the application of artificial neural networks. The solution of the problem of recognition of vehicle plate numbers can be represented as a complex of image processing and analysis of algorithms, which includes the initial preparation of the image, the discovery of the area of the vehicle plate on the image, the segmentation of symbols and the recognition of symbols. Conclusions: an algorithmically implemented method of identifying vehicle plate numbers, which makes possible searching the text areas under an arbitrary angle in different lighting conditions, is proposed. This method allows automating the process of identification of vehicle plate numbers within a wide range of distances to the car, as well as viewing the angles and levels of illumination. The purpose of further research is to improve the proposed method for its implementation, using modern software and hardware.

Interplanetary Type III Bursts and Electron Density Fluctuations in the Solar Wind

Abstract Type III bursts are generated by fast electron beams originated from magnetic reconnection sites of solar flares. As propagation of radio waves in the interplanetary medium is strongly affected by random electron density fluctuations, type III bursts provide us with a unique diagnostic tool for solar wind remote plasma measurements. Here, we performed a statistical survey of 152 simple and isolated type III bursts observed by the twin-spacecraft Solar TErrestrial RElations Observatory mission. We investigated their time–frequency profiles in order to retrieve decay times as a function of frequency. Next, we performed Monte Carlo simulations to study the role of scattering due to random electron density fluctuations on time–frequency profiles of radio emissions generated in the interplanetary medium. For simplification, we assumed the presence of isotropic electron density fluctuations described by a power law with the Kolmogorov spectral index. Decay times obtained from observations and simulations were compared. We found that the characteristic exponential decay profile of type III bursts can be explained by the scattering of the fundamental component between the source and the observer despite restrictive assumptions included in the Monte Carlo simulation algorithm. Our results suggest that relative electron density fluctuations in the solar wind are 0.06–0.07 over wide range of heliospheric distances.