Journal articles: 'Propagation channel modelling'

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Har, Dongsoo, Ce Xu, and Howard H. Xia. "Propagation modelling for wireless local loop channel." International Journal of Communication Systems 13, no. 3 (2000): 231–41. http://dx.doi.org/10.1002/1099-1131(200005)13:3<231::aid-dac428>3.0.co;2-q.

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Yang, Yi Huai. "Channel Modelling for WBANs." Applied Mechanics and Materials 246-247 (December 2012): 346–50. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.346.

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Development of an appropriate propagation channel model is an important step to design wireless body area network (WBAN). Because the human body has different body shapes (male, female and child), different tissues with different permittivity and conductivity (even the same person at the different age), and limbs positions and postures are changing all the time, this made the in-body channel modelling extremely difficult, if not impossible. There are few publications on implant communication channel models compared to wearable WBAN. In this paper, we present a literature survey on radio channel modelling for WBAN, especially the IEEE 802.15.6 models. The performance of the model is studied by simulating probability density functions (PDF) and cumulative distribution functions (CDF). Finally, we briefly outline some aspects of our future research works.

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Yang, Yi Huai. "Visual Simulation of Mobile Channel Model." Applied Mechanics and Materials 246-247 (December 2012): 1209–13. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.1209.

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Simulink is the integrated environment of system modelling and simulation, which is being widespread used. This paper describes the MATLAB visual simulation of the propagation path loss model for telecommunication systems. We simulated the whole process of COST231-Walfisch-Ikegami model with high accuracy, built a visual simulation frame and the path loss curves are given. This method can be used in studying other propagation path loss models in propagation environments.

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Del Galdo, G., M. Haardt, and C. Schneider. "Geometry-based channel modelling of MIMO channels in comparison with channel sounder measurements." Advances in Radio Science 2 (May 27, 2005): 117–26. http://dx.doi.org/10.5194/ars-2-117-2004.

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Abstract. In this paper we propose a flexible geometrybased propagation model for wireless communications developed at Ilmenau University of Technology. The IlmProp comprises a geometrical representation of the environment surrounding the experiment and a precise representation of the transmitting and receiving antennas. The IlmProp is capable of simulating Multi-User MIMO scenarios and includes a complete collection of tools to analyze the synthetic channels. In order to assess the potentials as well as the limits of our channel simulator we reconstruct the scenario encountered in a recent measurement campaign at Ilmenau University of Technology leading to synthetic data sets similar to the ones actually measured. The measurements have been collected with the RUSK MIMO multi-dimensional channel sounder. From the comparisons of the two channel matrices it is possible to derive useful information to improve the model itself and to better understand the physical origins of small-scale fading. In particular the effects of the different parameters on the synthetic channel have been studied in order to assess the sensibility of the model. This analysis shows that the correct positioning of a small number of scatterers is enough to achieve frequency selectiveness as well as specific traits of the channel statistics. The size of the scattering clusters, the number of scatterers per cluster, and the Rician K-factor can be modified in order to tune the channel statistics at will. To obtain higher levels of time variance, moving scatterers or time dependent reflection coefficients must be introduced.

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Arndt, Daniel, Alexander Ihlow, Albert Heuberger, and Ernst Eberlein. "State Modelling of the Land Mobile Propagation Channel with Multiple Satellites." International Journal of Antennas and Propagation 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/625374.

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We evaluate a new approach for multisatellite state modelling: the Master-Slave approach. By this concept slave satellites are modelled according to an existing master, whereas the correlation between multiple slaves is omitted. Master-Slave is therefore a generic name for a state modelling concept, for which different realisations are possible. As a possible realisation we present the Conditional Assembling Method. For modelling of only two satellites (one master and one slave), the Conditional Assembling Method enables an accurate resimulation of the correlation coefficient between the satellites and the probabilities of single and combined states. Based on this condition, the performance of Master-Slave for three, four, and five satellites is evaluated in terms of state probability modelling. Therefore, the correlation coefficients and the all bad-state probabilities with Master-Slave are compared with the measurements for different elevation angles and azimuth angle separations of the multisatellite system. Master-Slave has a high modelling error in case of small azimuth separation between the slave satellites (except that one slave has a small azimuth separation to the master). Furthermore, a master satellite with a high elevation provides a lower probability error compared to a master with low elevation.

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Arias, Marvin R. "Analysis of Multipath Propagation based on Cluster Channel Modelling Approach." Polibits 42 (December 31, 2010): 77–82. http://dx.doi.org/10.17562/pb-42-9.

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Nguyen, Dung Van. "FINITE ELEMENT MODELLING FOR ELECTRIC FIELD DISTRIBUTION AROUND POSITIVE STREAMERS IN OIL." Vietnam Journal of Science and Technology 58, no. 1 (February 21, 2020): 56. http://dx.doi.org/10.15625/2525-2518/58/1/14448.

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Electric field distribution of positive streamers during propagation was determined with the finite element method by using COMSOL multiphysics. Modelling was performed at 210 kV and 270 kV. The geometrical shape of streamers was modelled with cylinder and sphere for the case of 210 kV while a growing cylinder was used for streamer propagation at 270 kV. In addition, a spherical model was used for determining the correlation between streamer branching and the electric field. It is obtained from the simulation results that the 2nd mode streamers has the electric field at channel tips of about 0.1 MV/cm while 8.3 MV/cm was received for the 4th mode streamers. The simulation results also reveal that the shielding effect resulting from streamer branching significantly reduces the electric field at the channel tips, and the shielding effect disappears with the angle a between channels is about 30o-60o depending on the size of streamer envelope. The hypothesis on correlation among velocity, streamer branching and electric field is suggested.

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Kyösti, Pekka, Tommi Jämsä, and Jukka-Pekka Nuutinen. "Channel Modelling for Multiprobe Over-the-Air MIMO Testing." International Journal of Antennas and Propagation 2012 (2012): 1–11. http://dx.doi.org/10.1155/2012/615954.

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This paper discusses over-the-air (OTA) test setup for multiple-input-multiple-output (MIMO) capable terminals with emphasis on channel modelling. The setup is composed of a fading emulator, an anechoic chamber, and multiple probes. Creation of a propagation environment inside an anechoic chamber requires unconventional radio channel modelling, namely, a specific mapping of the original models onto the probe antennas. We introduce two novel methods to generate fading emulator channel coefficients; the prefaded signals synthesis and the plane wave synthesis. To verify both methods we present a set of simulation results. We also show that the geometric description is a prerequisite for the original channel model.

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Lin, H. P., F. S. Tsai, and M. J. Tseng. "Satellite propagation channel modelling using photogrammetry and hidden Markov model approach." IEE Proceedings - Microwaves, Antennas and Propagation 148, no. 6 (2001): 375. http://dx.doi.org/10.1049/ip-map:20010728.

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Konstantinou, K., S. Kang, T. Brown, and C. Tzaras. "Measurement and modelling of the propagation channel between low-height terminals." IET Microwaves, Antennas & Propagation 5, no. 4 (2011): 412. http://dx.doi.org/10.1049/iet-map.2010.0197.

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Ervine, D. A., and J. Ellis. "Experimental and computational aspects of overbank floodplain flow." Transactions of the Royal Society of Edinburgh: Earth Sciences 78, no. 4 (1987): 315–25. http://dx.doi.org/10.1017/s0263593300011251.

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ABSTRACTThe propagation of a flood wave through a river system is influenced by a complex process of energy dissipation. This is especially the case when overbank flows are a feature of the flood movement, producing more defined lateral movement of flow and high rates of fluid shear at the main channel/floodplain interface. The present paper concentrates on the physical and numerical modelling of river flows during overbank flow. A general description of the flow behaviour is outlined, including an investigation into the nature of the shear interaction between channel and floodplain. The paper advances a method for determining energy losses for the case of meandering channels with overbank flow and a method of sub-dividing the floodway for stage-discharge prediction. A state-of-the-art study of numerical modelling of flood propagation is outlined, including selected case histories on how the overbank flow situation has been handled to date, as well as comment on the current means of representing energy dissipation relying on calibration of the numerical model against observed field data.

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Miramirkhani, Farshad, and Murat Uysal. "Channel modelling for indoor visible light communications." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2169 (March 2, 2020): 20190187. http://dx.doi.org/10.1098/rsta.2019.0187.

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Visible light communication (VLC) allows the dual use of light-emitting diodes (LEDs) for wireless communication purposes in addition to their primary purpose of illumination. As in any other communication system, realistic channel modelling is a key for VLC system design, analysis and testing. In this paper, we present a comprehensive survey of indoor VLC channel models. In order to set the background, we start with an overview of infrared (IR) channel modelling, which has received much attention in the past, and highlight the differences between visible and IR optical bands. In the light of these, we present a comparative discussion of existing VLC channel modelling studies and point out the relevant advantages and disadvantages. Then, we provide a detailed description of a site-specific channel modelling approach based on non-sequential ray tracing that precisely captures the optical propagation characteristics of a given indoor environment. We further present channel models for representative deployment scenarios developed through this approach that were adopted by the Institute of Electrical and Electronics Engineering (IEEE) as reference channel models. Finally, we consider mobile VLC scenarios and investigate the effect of receiver location and rotation for a mobile indoor user. This article is part of the theme issue ‘Optical wireless communication’.

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Korman, Can E., and Isaak D. Mayergoyz. "On hysteresis of ion channels." Mathematical Modelling of Natural Phenomena 15 (2020): 26. http://dx.doi.org/10.1051/mmnp/2019058.

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Ion channel proteins have many conformational (metastable) states and, for this reason, they exhibit hysteresis. This fact is responsible for the non-Markovian stochastic nature of single ion channel recordings. It is suggested in the paper that the stochastic single channel recordings can be modeled as the random outputs of rectangular hysteresis loops driven by stochastic processes. The latter problem can be mathematically treated as an exit problem for stochastic processes or by using the theory of stochastic processes on graphs. It is also demonstrated in the paper that the collective action of sodium and potassium channels responsible for the generation and propagation of action potentials exhibit hysteresis. This demonstration is accomplished by using the inverse problem approach to the nonlinear Hodgkin-Huxley diffusion equation.

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Kasmi, C., M. Hélier, M. Darces, and E. Prouff. "Design of Experiments for Factor Hierarchization in Complex Structure Modelling." Advanced Electromagnetics 2, no. 1 (July 24, 2013): 59. http://dx.doi.org/10.7716/aem.v2i1.136.

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Modelling the power-grid network is of fundamental interest to analyse the conducted propagation of unintentional and intentional electromagnetic interferences. The propagation is indeed highly influenced by the channel behaviour. In this paper, we investigate the effects of appliances and the position of cables in a low voltage network. First, the power-grid architecture is described. Then, the principle of Experimental Design is recalled. Next, the methodology is applied to power-grid modelling. Finally, we propose an analysis of the statistical moments of the experimental design results. Several outcomes are provided to describe the effects induced by parameter variability on the conducted propagation of spurious compromising emanations.

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BRUNEAUX, G., T. POINSOT, and J. H. FERZIGER. "Premixed flame–wall interaction in a turbulent channel flow: budget for the flame surface density evolution equation and modelling." Journal of Fluid Mechanics 349 (October 25, 1997): 191–219. http://dx.doi.org/10.1017/s0022112097006769.

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Turbulent premixed flame propagation in the vicinity of a wall is studied using a three-dimensional constant-density simulation of flames propagating in a channel. The influence of the walls is investigated in terms of the flamelet approach, where flamelet speed and flame surface density transport are used to describe the flame. The walls have constant temperature and lead to flamelet quenching for sufficiently small wall–flame distances. Starting from the exact evolution equation for the surface density of propagating interfaces (Trouvé & Poinsot 1994; Candel & Poinsot 1990; Pope 1988), a budget for the flame surface density equation is presented before, during, and after the interaction with the wall. Before the flame interacts with the wall, flame propagation is controlled by a balance between surface production and annihilation. During the interaction, high flame surface density gradients near the wall are responsible for the predominance of the transport terms. Closures of all terms of the flame surface density equation are proposed. These models are based on flamelet ideas and take into account wall effects. Enthalpy loss through the wall affects flamelet speed, flamelet annihilation and flame propagation. Decrease of turbulent scales near the wall affects turbulent diffusion and flame strain. This model is compared to DNS results using two types of tests: (i) a priori tests, where individual terms of the modelled flame surface density equation are compared to the terms of the exact interface density propagation equation, calculated with the DNS; (ii) a posteriori tests, where the final model is used to obtain total reaction rate, mean fuel mass fraction, heat flux at the wall and fuel mass fraction at the wall in the configuration used in the DNS. For both types of tests the model compares well with the DNS results.

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Cemal Benim, Ali, and Björn Pfeiffelmann. "Prediction of hydrogen flame propagation in a channel with exit contraction." E3S Web of Conferences 128 (2019): 01013. http://dx.doi.org/10.1051/e3sconf/201912801013.

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The propagation of a flame front in a homogeneous and initially quiescent hydrogen-air mixture in a channel with exit contraction is numerically analyzed by means of Computational Fluid Dynamics. For the given configuration, the compressibility effects are important, the average pressure increases in time due to the exit contraction, and pressure waves occur, which affect the flame propagation. Flowturbulence is modelled by the Realizable k-e model. In modelling combustion, turbulence-chemistry interactions are neglected. Predictions are compared with the measurements for evolution of the flame shape, propagation speed and pressure. It is observed that the flame propagation speed, and, thus, the rate of pressure increase are over-predicted by the present approach. Still, a fair qualitative agreementto measurements is observed.

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Campisano, A., E. Creaco, and C. Modica. "Experimental analysis of the Hydrass flushing gate and laboratory validation of flush propagation modelling." Water Science and Technology 54, no. 6-7 (September 1, 2006): 101–8. http://dx.doi.org/10.2166/wst.2006.608.

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Periodical cleansing operations prove necessary inside sewer systems in order to reduce hydraulic and environmental problems owing to the accumulation of deposits on the bottom of channels. For this objective, new effective hydraulic devices based on the scouring effects of flushing waves have been recently set up and adopted in many sewer systems. In this paper, the results of an experimental and numerical investigation on the hydraulic operation of the Hydrass flushing gate are reported. The experimental analysis has been carried out using a laboratory channel and a reduced scale model of the gate, in order to characterise the flushing waves generated by the device. The numerical analysis has been performed using a mathematical model specifically developed for the simulation of flushing waves inside sewer channels. The comparison of numerical results and experimental data has allowed evaluation of the applicability under unsteady flow conditions of the outflow relations determined for the Hydrass gate in a previous investigation under steady flow conditions.

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Akkaş, Mustafa Alper. "Nano-Sensor Modelling for Intra-Body Nano-Networks." Wireless Personal Communications 118, no. 4 (February 11, 2021): 3129–43. http://dx.doi.org/10.1007/s11277-021-08171-2.

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AbstractIn this work, the author has evaluated the propagation of electromagnetic waves inside the human tissue such as blood, skin and fat for single-path and multi-path layers according to nano sensor transmit power calculations. In particular, the propagation characteristics of the Intra-Body Nano-Network communication channel are calculated using a theoretical approach. The analysis in this paper provides an evaluation related to the path loss, bit error rate, signal to noise ratio and the channel capacity. The model is evaluated for each single-path effect and multi-path effect. The effects of human tissue for each blood, skin and fat for single-path effect and multi-path are included in the analysis. The model frequency range is chosen from 0.01 to 1.5 THz frequencies, which are ideal for designing nano sensors antennae and using THz range for communication. This paper will also guide other researchers who are working on the electromagnetic radiation performance of Intra-Body Nano-Network and Nano sensors designed at the THz range.

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Goulianos, A. A., T. Brown, and S. Stavrou. "Power delay profile modelling of the ultra wideband off-body propagation channel." IET Microwaves, Antennas & Propagation 4, no. 1 (2010): 62. http://dx.doi.org/10.1049/iet-map.2008.0356.

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GOMEZ, CHRISTOPHE. "LOSS OF RESOLUTION FOR THE TIME REVERSAL OF WAVES IN RANDOM UNDERWATER ACOUSTIC CHANNELS." Mathematical Models and Methods in Applied Sciences 23, no. 11 (July 23, 2013): 2065–110. http://dx.doi.org/10.1142/s0218202513500267.

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In this paper we analyze a time reversal experiment in a random underwater acoustic channel. In this kind of waveguide with a semi-infinite cross-section a propagating field can be decomposed over three kinds of modes: the propagating modes, the radiating modes and the evanescent modes. Using an asymptotic analysis based on a separation of scales technique we derive the asymptotic form of the the coupled mode power equation for the propagating modes. This approximation is used to compute the transverse profile of the refocused field and show that random inhomogeneities inside the waveguide deteriorate the spatial focusing. This result, in an underwater acoustic channel context, is a counterexample of the classical results about time reversal experiment in other configurations for which randomness in the propagation medium enhances the refocusing.

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Sirdeshpande, Nandakishor, and Vishwanath Udupi. "Characterization of path loss model for wireless communication channel modelling." Data Technologies and Applications 54, no. 3 (April 27, 2020): 343–64. http://dx.doi.org/10.1108/dta-03-2019-0052.

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PurposeWireless communication channel provides a wide area of applications in the field of communication, distributed sensor network and so on. The prominence of the wireless communication channel is because of its robust nature and the sustainability for the precise ranging and the localization. The precision and accuracy of the wireless communication channel largely depend on the localization. The development of the wireless communication channel with improved benefits needs the accurate channel model.Design/methodology/approachThis paper characterizes the tangential path loss model in the WINNER based wireless communication channel model. The measurements taken in the WINNER channel model are compared with the tangential path loss characterized WINNER Channel model.FindingsThe model operates well over the varying antenna orientations, measurement condition and the propagation condition. The proposed tangential path loss model is performing well over the various outdoor scenarios.Originality/valueThe proposed characterization shows change in the small-scale parameters (SSP), such as power, delay, angle of arrival and angle of departure as well as the large-scale parameters (LSP), such as RMS delay spread, shadowing, path loss and Ricean factor associated with the model.

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Lièbe, Christophe, Pierre Combeau, Alain Gaugue, Yannis Pousset, Lilian Aveneau, Rodolphe Vauzelle, and Jean-Marc Ogier. "Ultra-Wideband Indoor Channel Modelling Using Ray-Tracing Software for through-the-Wall Imaging Radar." International Journal of Antennas and Propagation 2010 (2010): 1–14. http://dx.doi.org/10.1155/2010/934602.

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This paper presents a new software for design of through-the-wall imaging radars. The first part describes the evolution of a ray tracing simulator, originally designed for propagation of narrowband signals, and then for ultra-wideband signals. This simulator allows to obtain temporal channel response to a wide-band emitter (3 GHz to 10 GHz). An experimental method is also described to identify the propagation paths. Simulation results are compared to propagation experiments under the same conditions. Different configurations are tested and then discussed. Finally, a configuration of through-the-wall imaging radar is proposed, with different antennas patterns and different targets. Simulated images will be helpful for understanding the experiment obtained images.

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Grajales, Juan Carlos Munoz. "EXISTENCE AND NUMERICAL APPROXIMATION OF SOLUTIONS OF AN IMPROVED INTERNAL WAVE MODEL." Mathematical Modelling and Analysis 19, no. 3 (June 1, 2014): 309–33. http://dx.doi.org/10.3846/13926292.2014.924039.

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In this paper we establish local existence of solutions for a new model to describe the propagation of an internal wave propagating at the interface of two immiscible fluids with constant densities, contained at rest in a long channel with a horizontal rigid top and bottom. We also introduce a spectral-type numerical scheme to approximate the solutions of the corresponding Cauchy problem and perform a complete error analysis of the semidiscrete scheme.

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Aminu, Muslim B. "Geophysical investigation of the Orle River fracture system in Igarra Township, southwestern Nigeria." Global Journal of Geological Sciences 19, no. 1 (July 13, 2021): 1–14. http://dx.doi.org/10.4314/gjgs.v19i1.1.

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The subsurface structure and propagation geometry of the fracture system controlling the Orle River Channel in the Igarra Township, Southwestern Nigeria, have been investigated via a multi-method geophysical survey. The goal was to delineate the nature, distribution, and spatial propagation geometry of the fracture system and evaluate its potential to serve as storage and distribution features for groundwater within adjoining areas. 2D electrical resistivity, total field magnetic, and co-planar loop conductivity measurements were collected along four traverses using an ABEM1000 Terrameter unit, a GEMS Magnetometer, and an EM34 Co-planar loop electromagnetic system. Traverses were established to run across and parallel to the river channel. The observed electrical resistivity field data were inverted for subsurface 2D resistivity structure using a commercially available 2.5D finite element modelling inversion software. Magnetic field intensity data and ground conductivity data were presented against station positions. Three subsurface layers were delineated at the survey site; (1) surficial humus-rich and wet top-soil, (2) a thin poorly developed weathering layer, and (3) the fresh bedrock which occurs as relatively shallow levels and often outcrops. The River channel is controlled by multiple fractures usually located at or near the contracts between contrasting rock types. Fracture dip is usually in the northerly direction but conjugates, dipping southwards also occur in the most northerly extremes of the imaged fracture system. Upstream the fracture path is wider and along with the imaged overburden, isjuxtaposed northwards of the channel axis suggesting a much broader river channel in the geologic past. Low aperture fractures imaged tangential to channel axis likely serve to funnel surface and groundwater from the channels to the surrounding areas. Where such low aperture fractures can be delineated, they offer the best chances of groundwater abstraction within adjoining areas, particularly during the dry season.

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Carruthers, J. B., P. Kannan, and S. M. Carroll. "Propagation modelling for indoor optical wireless communications using fast multi-receiver channel estimation." IEE Proceedings - Optoelectronics 150, no. 5 (October 1, 2003): 473–81. http://dx.doi.org/10.1049/ip-opt:20030527.

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Ghaddar, M., L. Talbi, and T. A. Denidni. "Human body modelling for prediction of effect of people on indoor propagation channel." Electronics Letters 40, no. 25 (2004): 1592. http://dx.doi.org/10.1049/el:20046730.

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Ahmad, Abrar, Adnan Ahmad Cheema, and Dewar Finlay. "A survey of radio propagation channel modelling for low altitude flying base stations." Computer Networks 171 (April 2020): 107122. http://dx.doi.org/10.1016/j.comnet.2020.107122.

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Obite, Felix, Jafri Din, Kamaludin Mohammad Yusof, and Basliza M. Noor. "Investigation of HAPs Propagation Channel for Wireless Access in a Tropical Region at Ka-Band." International Journal of Electrical and Computer Engineering (IJECE) 7, no. 3 (June 1, 2017): 1204. http://dx.doi.org/10.11591/ijece.v7i3.pp1204-1211.

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<p>In the last few years, High Altitude Platforms (HAPs) have attracted considerable effort due to their ability to exploit the advantages of satellite and terrestrial-based systems. Rain attenuation is the most dominant atmospheric impairment, especially at such frequency band. This paper addresses the modelling of rain attenuation and describes a propagation channel model for HAPs at Ka-band to provide efficient and robust wireless access for tropical regions. The attenuation due to rain is modeled based on three years measured data for Johor Bahru to estimate the actual effect of rain on signals at Ka band. The radio propagation channel is usually characterized as a random multipath channel. Specifically, a statistical derivation of probability distribution function for Rayleigh and Rician fading channels are presented. The model consists of multiple path scattering effects, time dispersion, and Doppler shifts acting on the HAPs communication link. Simulation results represent the fading signal level variations. Results show perfect agreement between simulation and theoretical, thereby conforming to the multipath structures. The information obtained will be useful to system engineers for HAPs link budget analysis in order to obtain the required fade margin for optimal system performance in tropical regions.</p>

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Tigerholm, J., M. E. Petersson, O. Obreja, A. Lampert, R. Carr, M. Schmelz, and E. Fransén. "Modelling activity-dependent changes of velocity in C-fibers." Scandinavian Journal of Pain 16, no. 1 (July 1, 2017): 186–87. http://dx.doi.org/10.1016/j.sjpain.2017.04.062.

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AbstractAimsWhen C-nociceptors are activated repeatedly using electrical stimulation at relatively low frequencies (0.125–2 Hz), their propagation velocity will decrease. This is referred to as activity-dependent slowing (ADS). The main reason why activity-dependent changes in velocity are of interest is that they can be recorded directly, using invasive methods (microneurography), in patients with chronic pain. Interestingly, in certain patients with neuropathic pain, reduced activity-dependent slowing of conduction has been observed, indicating that these axons have an increased excitability. Through a computational model, it is possible to link such velocity alterations with changes in active conductances, opening for an understanding the underlying excitability changes occurring in these patients.MethodsWe have developed a detailed multicompartment model of a C-nociceptor fiber. This model incorporates a wide range of voltage-gated ion channels (Nav1.7, Nav1.8, Nav1.9, Kdr, KA, KM, KNa and h) which were implemented across a detailed and realistic axon morphology.ResultsThe model predicts that the small diameter of the axon can accumulate intracellular sodium when it is repeatedly activated in a similar fashion as during single fiber microneurography. This increase of intracellular sodium concentration can shift the balance between ion channel currents, shift the membrane potential and membrane input resistance, and thereby generate activity-dependent changes of velocity, such as ADS as well as recovery cycle supernormality.ConclusionsOur results thus provide insight into how activity-dependent excitability changes can be generated in C-fibers. By identifying which ion channels are contributing to activity-dependent changes of velocity this could provide insight into ion channel alterations in neuropathic pain patients.

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Adnan, Farasatul, Valon Blakaj, Sendy Phang, Thomas M. Antonsen, Stephen C. Creagh, Gabriele Gradoni, and Gregor Tanner. "Wireless power distributions in multi-cavity systems at high frequencies." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477, no. 2245 (January 2021): 20200228. http://dx.doi.org/10.1098/rspa.2020.0228.

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The next generations of wireless networks will work in frequency bands ranging from sub-6 GHz up to 100 GHz. Radio signal propagation differs here in several critical aspects from the behaviour in the microwave frequencies currently used. With wavelengths in the millimetre range (mmWave), both penetration loss and free-space path loss increase, while specular reflection will dominate over diffraction as an important propagation channel. Thus, current channel model protocols used for the generation of mobile networks and based on statistical parameter distributions obtained from measurements become insufficient due to the lack of deterministic information about the surroundings of the base station and the receiver-devices. These challenges call for new modelling tools for channel modelling which work in the short-wavelength/high-frequency limit and incorporate site-specific details—both indoors and outdoors. Typical high-frequency tools used in this context—besides purely statistical approaches—are based on ray-tracing techniques. Ray-tracing can become challenging when multiple reflections dominate. In this context, mesh-based energy flow methods have become popular in recent years. In this study, we compare the two approaches both in terms of accuracy and efficiency and benchmark them against traditional power balance methods.

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Liu, Weiping, and C. S. James. "Estimation of discharge capacity in meandering compound channels using artificial neural networks." Canadian Journal of Civil Engineering 27, no. 2 (April 1, 2000): 297–308. http://dx.doi.org/10.1139/l99-056.

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Flow in compound (or two-stage) channels is very complex and different energy loss mechanisms operate under different geometric and flow conditions. Neither theoretical analyses nor current empirical approaches are sufficiently developed for practical calculation of conveyance for all conditions experienced in practice. An alternative approach, using artificial neural network modelling, has been successfully applied to predict conveyance under a wide range of conditions. The model proposed uses a feed-forward system with one hidden layer and an error back-propagation learning procedure. It predicts a dimensionless discharge using input describing the main channel and floodplain flow depths, vegetation density over the cross section, channel sinuosity, transverse floodplain slope, and floodplain bend tightness. The discharge is dimensionalized by multiplication with the composite discharge calculated assuming frictional resistance only. The model was trained using 45 data sets representing a range of main channel and floodplain characteristics and tested using 15 additional data sets. The discharge prediction error for all the data used in development and testing the model was -0.19% on average and exceeded 15% for one condition only.Key words: compound channels, channel conveyance, flow resistance, neural networks.

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Guet-McCreight, Alexandre, and Frances K. Skinner. "Computationally going where experiments cannot: a dynamical assessment of dendritic ion channel currents during in vivo-like states." F1000Research 9 (March 11, 2020): 180. http://dx.doi.org/10.12688/f1000research.22584.1.

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Background: Despite technological advances, how specific cell types are involved in brain function remains shrouded in mystery. Further, little is known about the contribution of different ion channel currents to cell excitability across different neuronal subtypes and their dendritic compartments in vivo. The picture that we do have is largely based on somatic recordings performed in vitro. Uncovering dendritic ion channel current contributions in neuron subtypes that represent a minority of the neuronal population is not currently a feasible task using purely experimental means. Methods: We employ two morphologically-detailed multi-compartment models of a specific type of inhibitory interneuron, the oriens lacunosum moleculare (OLM) cell. The OLM cell is a well-studied cell type in CA1 hippocampus that is important in gating sensory and contextual information. We create in vivo-like states for these cellular models by including levels of synaptic bombardment that would occur in vivo. Using visualization tools and analyses we assess the ion channel current contribution profile across the different somatic and dendritic compartments of the models. Results: We identify changes in dendritic excitability, ion channel current contributions and co-activation patterns between in vitro and in vivo-like states. Primarily, we find that the relative timing between ion channel currents are mostly invariant between states, but exhibit changes in magnitudes and decreased propagation across dendritic compartments. We also find enhanced dendritic hyperpolarization-activated cyclic nucleotide-gated channel (h-channel) activation during in vivo-like states, which suggests that dendritically located h-channels are functionally important in altering signal propagation in the behaving animal. Conclusions: Overall, we have demonstrated, using computational modelling, the dynamical changes that can occur to ion channel mechanisms governing neuronal spiking in vitro and in vivo. In particular, we have shown that the magnitudes of some ion channel current contributions are differentially altered during in vivo-like states relative to in vitro.

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Guet-McCreight, Alexandre, and Frances K. Skinner. "Computationally going where experiments cannot: a dynamical assessment of dendritic ion channel currents during in vivo-like states." F1000Research 9 (June 11, 2020): 180. http://dx.doi.org/10.12688/f1000research.22584.2.

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Background: Despite technological advances, how specific cell types are involved in brain function remains shrouded in mystery. Further, little is known about the contribution of different ion channel currents to cell excitability across different neuronal subtypes and their dendritic compartments in vivo. The picture that we do have is largely based on somatic recordings performed in vitro. Uncovering dendritic ion channel current contributions in neuron subtypes that represent a minority of the neuronal population is not currently a feasible task using purely experimental means. Methods: We employ two morphologically-detailed multi-compartment models of a specific type of inhibitory interneuron, the oriens lacunosum moleculare (OLM) cell. The OLM cell is a well-studied cell type in CA1 hippocampus that is important in gating sensory and contextual information. We create in vivo-like states for these cellular models by including levels of synaptic bombardment that would occur in vivo. Using visualization tools and analyses we assess the ion channel current contribution profile across the different somatic and dendritic compartments of the models. Results: We identify changes in dendritic excitability, ion channel current contributions and co-activation patterns between in vitro and in vivo-like states. Primarily, we find that the relative timing between ion channel currents are mostly invariant between states, but exhibit changes in magnitudes and decreased propagation across dendritic compartments. We also find enhanced dendritic hyperpolarization-activated cyclic nucleotide-gated channel (h-channel) activation during in vivo-like states, which suggests that dendritically located h-channels are functionally important in altering signal propagation in the behaving animal. Conclusions: Overall, we have demonstrated, using computational modelling, the dynamical changes that can occur to ion channel mechanisms governing neuronal spiking. Simultaneous access to dendritic compartments during simulated in vivo states shows that the magnitudes of some ion channel current contributions are differentially altered during in vivo-like states relative to in vitro.

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Deyirmenjian, V. B., and J. E. Sipe. "A cluster expansion approach to modelling single-channel bit string propagation in optical fibers." Optics Communications 159, no. 1-3 (January 1999): 49–52. http://dx.doi.org/10.1016/s0030-4018(98)00603-8.

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Castanet, Laurent. "Special issue on ‘Channel modelling and propagation impairment simulation activities within the SatNEx project’." International Journal of Satellite Communications and Networking 29, no. 1 (December 19, 2010): 1–6. http://dx.doi.org/10.1002/sat.949.

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Aka-Ngnui, T., and A. Beroual. "Modelling of multi-channel streamers propagation in liquid dielectrics using the computation electrical network." Journal of Physics D: Applied Physics 34, no. 5 (February 21, 2001): 794–805. http://dx.doi.org/10.1088/0022-3727/34/5/318.

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Naicker, K., and S. H. Mneney. "Propagation measurements and multipath channel modelling for line-of-sight links at 19.5 GHZ." SAIEE Africa Research Journal 97, no. 2 (June 2006): 162–71. http://dx.doi.org/10.23919/saiee.2006.9488006.

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Yuan, Pei-yin, Ping-yi Wang, and Yu Zhao. "Physical Modelling of Roll and Pitch Motions of Travelling or Stationary Ship in Large-Scale Landslide-Generated Waves." Advances in Civil Engineering 2020 (July 21, 2020): 1–11. http://dx.doi.org/10.1155/2020/8857604.

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Large-scale landslides often occur in river-type reservoirs, and landslide-generated waves affect navigation channels and the navigation of ships. Thus, such waves cause widespread regional disasters. This study establishes a mechanical model of landslide-generated waves via field investigations and data collection, reveals the mechanism and process of landslide-generated waves, and investigates the propagation characteristics of landslide-generated waves along a sloping wave. The feasibility of the model is verified via (i) regularity analysis, (ii) comparative analysis of the effect of landslide-generated waves of mountain river channel reservoirs on the movement characteristics of navigation vessels and stationary vessels, (iii) deviation from the equilibrium position, and (iv) an in-depth study of the influence of large-scale landslide-generated waves on ships in different navigation positions in a river channel. Countermeasures are proposed for a sailing ship to tackle a sudden landslide-generated wave; these measures can provide a theoretical basis for ships to sail safely through large-scale landslide-generated waves.

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Badejo, O. T., O. T. Jegede, H. O. Kayode, O. O. Durodola, and S. O. Akintoye. "Modelling and prediction of water current using artificial neural networks: A case study of the commodore channel." Nigerian Journal of Technology 39, no. 3 (September 16, 2020): 942–52. http://dx.doi.org/10.4314/njt.v39i3.37.

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Water current modelling and prediction techniques along coastal inlets have attracted growing concern in recent years. This is largely so because water current component continues to be a major contributor to movement of sediments, tracers and pollutants, and to a whole range of offshore applications in engineering, environmental observations, exploration and oceanography. However, most research works are lacking adequate methods for developing precise prediction models along the commodore channel in Lagos State. This research work presents water current prediction using Artificial Neural Networks (ANNs). The Back Propagation (BP) technique with feed forward architecture and optimized training algorithm known as Levenbergq-Marquardt was used to develop a Neural Network Water Current Prediction model-(NNWLM) in a MATLAB programming environment. It was passed through model sensitivity analysis and afterwards tested with data from the Commodore channel (Lagos Lagoon). The result revealed prediction accuracy ranging from 0.012 to 0.045 in terms of Mean Square Error (MSE) and 0.80 to 0.83 in terms of correlation coefficient (R-value). With this high performance, the Neural network developed in this work can be used as a veritable tool for water current prediction along the Commodore channel and in extension a wide variety of coastal engineering and development, covering sediment management program: dredging, sand bypassing, beach-contingency plans, and protection of beaches vulnerable to storm erosion and monitoring and prediction of long-term water current variations in coastal inlets. Keywords: Artificial Neural Network, Commodore Channel, Coastal Inlet, Water Current, Back Propagation.

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Lv, Zhengnan, and Zhenghao Xi. "Radio Frequency Link and User Selection Algorithm for 5G Mobile Communication System." Complexity 2021 (May 18, 2021): 1–10. http://dx.doi.org/10.1155/2021/1976499.

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Based on the millimetre-wave time-domain channel detector, this paper conducts channel measurement and modelling for different scenarios and antenna types in typical frequency bands and thus carries out a study on the propagation characteristics of millimetre-wave channels in typical frequency bands and scenarios for 5G. The time-varying characteristics and modelling methods of millimetre-wave clusters are studied, and the time-varying channel simulation strategy and linear regression fitting method are used to establish the time-varying generation and extinction model of clusters by combining the measured data of 26 GHz large-scale antenna channels. The algorithm is based on the correlation dictionary and achieves the efficient and optimal selection of large-scale antenna arrays in the millimetre-wave band. A low-complexity multiuser hybrid precoding design scheme is proposed based on the wideband millimetre-wave large-scale Multiple-Input Multiple-Output (MIMO) system. The scheme aims to maximize the system spectral efficiency and introduces the net spectral efficiency as a bridge to decouple the analogy precoding design from the digital precoding design, thus significantly reducing the computational complexity. In the analogy precoding stage, a Hungarian algorithm-based beam assignment method is proposed to avoid beam conflicts and maximize the net spectral efficiency of the system; in the digital precoding stage, the equivalent channel matrix of each subcarrier is diagonalized to eliminate multiuser interference. Finally, the effectiveness of the scheme is verified by simulation. In this paper, we focus on the radio frequency (RF) link and user selection algorithm of 5G mobile communication system. Through the study of these two aspects, the RF link of our communication system has high stability and reliability, and through the study of the algorithm used for selection, our results also have a strong practical value.

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García Sánchez, Manuel, Alejandro Santomé Valverde, and Isabel Expósito. "Radio Channel Scattering in a 28 GHz Small Cell at a Bus Stop: Characterization and Modelling." Electronics 9, no. 10 (September 23, 2020): 1556. http://dx.doi.org/10.3390/electronics9101556.

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The 28 GHz band is one of the available bands in Frequency Range 2 (FR2), above 6 GHz, for fifth generation (5G) communications. The propagation characteristics at this frequency band, together with the bandwidth requirements of 5G communications, make it suitable for ultra-dense smart cell networks. In this paper, we investigate the performance of a radio channel in the presence of moving, scattering sources for a small cell at 28 GHz, located at a bus stop. To do so, measurements of the channel complex impulse response with a sweep time delay cross-correlation sounder were made and then used to examine the distribution of multipath components. Besides analyzing the delay spread caused by the channel, we also evaluate the impact on the Doppler spectrum (DS) caused by the vehicles passing near the bus stop. We show that delay components are grouped in clusters exhibiting exponential decay power. We also show that the DS varies with time as vehicles pass by, so the channel cannot be considered stationary. We propose an empirical DS model, where the model parameter should change with time to describe the non-stationary nature of the radio channel. We have also found that the DS with maximum spread is similar for channel contributions in different delay clusters.

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Isabona, Joseph, and Divine O. Ojuh. "Application of Levenberg-Marguardt Algorithm for Prime Radio Propagation Wave Attenuation Modelling in Typical Urban, Suburban and Rural Terrains." International Journal of Intelligent Systems and Applications 13, no. 3 (June 8, 2021): 35–42. http://dx.doi.org/10.5815/ijisa.2021.03.04.

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The desire to achieve an adaptive prognostics regression learning processes of physical and empirical phenomenon is a complex task and open problem in radio frequency telecommunication engineering. One key method to solving such complex task or problems is by means of numerical based optimisation algorithms. The Levenberg–Marquardt algorithm (LMA) is an efficient nonlinear parametric machine learning based modelling algorithm with optimal, fast, and accurate convergence speed. This paper proposes and demonstrates the real-time application of the LMA in developing a log-distance like propagation loss model based on received radio strength measurements conducted over deployed long term evolution (LTE) eNodeBs antennas in three different propagation areas. The LTE eNodeB signal propagation areas were selected to reflect typical urban, suburban and rural terrains which represent urban, suburban and rural terrains. The heights of the three eNodeBs are 30, 28 and 32m respectively and each operate at 2.6GHz carrier frequency with 10MHz channel bandwidths. The resultant outcome of the proposed propagation loss modelling using LMA indicates a high approximation efficacy over the popular Gauss-Newton algorithm (GNA) modelling method, which has been used to benchmark the process. Precisely, the developed propagation loss model using LMA method attained lower maximum absolute error (MABE) of 7.73, 14.57and 10.53 for urban, suburban and rural terrains compared to the ones developed by GNA which yielded 15.19, 16.59 and 13.05 MABE values. The improved approximation performance of the LMA over the GNA can be ascribed to its capacity handle multiple free parameters and attain optimum solution irrespective of the selected values of initial guess parameters.

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Wu, Sheng, Zuyao Ni, Xiangming Meng, and Linling Kuang. "Block Expectation Propagation for Downlink Channel Estimation in Massive MIMO Systems." IEEE Communications Letters 20, no. 11 (November 2016): 2225–28. http://dx.doi.org/10.1109/lcomm.2016.2598810.

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Muñoz Grajales, Juan Carlos. "Propagation of Water Waves over Uneven Bottom under the Effect of Surface Tension." International Journal of Differential Equations 2015 (2015): 1–21. http://dx.doi.org/10.1155/2015/805625.

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We establish existence and uniqueness of solutions to the Cauchy problem associated with a new one-dimensional weakly-nonlinear, weakly-dispersive system which arises as an asymptotical approximation of the full potential theory equations for modelling propagation of small amplitude water waves on the surface of a shallow channel with variable depth, taking into account the effect of surface tension. Furthermore, numerical schemes of spectral type are introduced for approximating the evolution in time of solutions of this system and its travelling wave solutions, in both the periodic and nonperiodic case.

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Belloul, B., S. R. Saunders, M. A. N. Parks, and B. G. Evans. "Measurement and modelling of wideband propagation at L- and S-bands applicable to the LMS channel." IEE Proceedings - Microwaves, Antennas and Propagation 147, no. 2 (2000): 116. http://dx.doi.org/10.1049/ip-map:20000220.

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Haefner, Stephan, and Reiner Thomä. "High Resolution Estimation of AoA, AoD and TdoA from MIMO Channel Sounding Measurements with Virtual Antenna Arrays: Maximum-Likelihood vs. Unitary Tensor-ESPRIT." International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems 7, no. 2 (June 28, 2018): 27. http://dx.doi.org/10.11601/ijates.v7i2.254.

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Estimating the parameters of a geometric propagation model from MIMO channel sounding measurements will be considered, which requires the solution of an inverse problem. Thus, a model of the measured data is derived, which incorporates a model of the measurement system as well as the parameters of interest. Based on the data model a maximum-likelihood estimator will be derived to infer the model parameters. Because virtual antenna arrays are considerer, formed by step-wise rotating directive antennas at transmitter and receiver side, the MIMO measurements are conducted in the beam-space. Hence, the data model can be described by a multidimensional convolution of the measurement system and the propagation channel. Based on the convolutional modelling, the parameter estimation problem is transformed into a harmonic retrieval problem, which can be solved by an Unitary Tensor-ESPRIT algorithm. The maximum-likelihood and ESPRIT estimator are compared by Monte-Carlo simulations according to their root-mean-square estimation error.

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Formetta, G., R. Mantilla, S. Franceschi, A. Antonello, and R. Rigon. "The JGrass-NewAge system for forecasting and managing the hydrological budgets at the basin scale: the models of flow generation, propagation, and aggregation." Geoscientific Model Development Discussions 4, no. 2 (April 29, 2011): 943–69. http://dx.doi.org/10.5194/gmdd-4-943-2011.

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Abstract. This paper presents a discussion of the predictive capacity of the first implementation of the semi-distributed hydrological modeling system JGrass-NewAge. This model focuses on the hydrological balance of medium scale to large scale basins, and considers statistics of the processes at the hillslope scale. The whole modeling system consists of six main parts: (i) estimation of energy balance; (ii) estimation of evapotranspiration; (iii) snow modelling; (iv) estimation of runoff production; (v) aggregation and propagation of flows in channel, and (vi) description of intakes, out-takes, and reservoirs. This paper details the processes, of runoff production, and aggregation/propagation of flows on a river network. The system is based on a hillslope-link geometrical partition of the landscape, so the basic unit, where the budget is evaluated, consists of hillslopes that drain into a single associated link rather than cells or pixels. To this conceptual partition corresponds an implementation of informatics that uses vectorial features for channels, and raster data for hillslopes. Runoff production at each channel link is estimated through a combination of the Duffy (1996) model and a GIUH model for estimating residence times in hillslope. Routing in channels uses equations integrated for any channels' link, and produces discharges at any link end, for any link in the river network. The model has been tested against measured discharges according to some indexes of goodness of fit such as RMSE and Nash Sutcliffe. The characteristic ability to reproduce discharge in any point of the river network is used to infer some statistics, and notably, the scaling properties of the modeled discharge.

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Bertrand-Krajewski, J. L., A. Campisano, E. Creaco, and C. Modica. "Experimental analysis of the Hydrass flushing gate and field validation of flush propagation modelling." Water Science and Technology 51, no. 2 (January 1, 2005): 129–37. http://dx.doi.org/10.2166/wst.2005.0040.

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As well known, a periodical cleansing of sewers results necessary in order to avoid or reduce many unpleasant consequences due to the presence of sediments, such as the solid re-suspension during rain events and the reduction of the channel flow capacity. For this purpose, different systems based on flushing techniques have been adopted in sewers. In the present paper, the results of an analysis of the hydraulics of a flushing device, the Hydrass gate, is presented. In particular, an experimental investigation on a scale model under steady conditions was carried out in order to determine the behaviour of the device during the flushing phase. Outflow relations were derived for the different outflow conditions. A numerical model was finally set up for testing the relations under unsteady conditions, using for validation the experimental data of a previous measurement campaign carried out in a sewer reach of the city of Lyon, France.

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Sabri, N., Mohammed S. S, Sarah Fouad, Syed A. A, Fahad Taha AL-Dhief, and Auda Raheemah. "Investigation of Empirical Wave Propagation Models in Precision Agriculture." MATEC Web of Conferences 150 (2018): 06020. http://dx.doi.org/10.1051/matecconf/201815006020.

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Wireless Sensor Networks have highly proved its contribution in precision agriculture. Communication channel modelling investigation is a highly demanded to achieve a successful communication system where a good wave propagation model is crucially needed. Precision agriculture degrades the traveling waves in various forms in addition to the effects of the large-scale path losses models. This paper reviews the most known theoretical large-scale path losses models such as free space (FSPL) and Plane earth (PE) models as well as the vegetation models represented by Weissberger, ITU-R, FITU-R and COS235 models. Indeed, this work illustrates the effects of many factors on the total path losses such as separation distance between transceivers, antenna heights and the depth of vegetation that presence in the path propagation. In conclusion, the total path loss is computed based on large-scale path losses and the vegetation losses in protected vegetation environment.

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Santoso, Tri Budi, Endang Widjiati, Wirawan Wirawan, and Gamantyo Hendrantoro. "Underwater Acoustic Channel Characterization of Shallow Water Environment." EMITTER International Journal of Engineering Technology 6, no. 1 (July 10, 2018): 137–50. http://dx.doi.org/10.24003/emitter.v6i1.243.

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Understanding of channel propagation characteristics is a key to the optimal design of underwater acoustic communication. Generally, modelling of underwater acoustic channel is performed based on measurement result in certain site at certain times. Different sites might have different characteristics, each of which can generally be described by a model obtained by averaging measurement results at multiple points in the same environment. This paper describes a characterization of the underwater acoustic channel of tropical shallow water in a Mangrove estuary, which has sediment up to 60 cm at the bottom. Such a channel model is beneficial for the design of communication system in an autonomous underwater vehicle, for instance. The measurement result of delay spread parameter from three different points with the distance of 14 ~ 52 m, has various values. The root mean square (RMS) of delay spread ranges between 0.0621 ~ 0.264 ms, and the maximum delay spread varies with the value of 0.187 ~ 1.0 ms. The pdf fitting shows that Rayleigh distribution describes the fading variation more accurately than Nakagami and Ricean.

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Journal articles on the topic 'Propagation channel modelling'

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