Journal articles on the topic 'Space-time channel modelling'
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1
Babur, G., P. Aubry, and F. Le Chevalier. "Space-Time Radar Waveforms: Circulating Codes." Journal of Electrical and Computer Engineering 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/809691.
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This paper describes a concept of the circulating codes covering the whole class of the space-time codes. The circulating codes do not narrow the radiated pattern of the antenna array, thus providing a wide angular coverage, possibly tunable. In turn, the beam-forming on transmit is achievable by means of the signal processing in one (or each) receiver channel. The modelling results demonstrate the efficiency of the circulating codes based on their multidimensional ambiguity functions.
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Kharchenko, Volodymir, Bo Wang, Andrii Grekhov, and Anna Leschenko. "MODELLING THE SATELLITE COMMUNICATION LINKS WITH ORTHOGONAL FREQUENCY-DIVISION MULTIPLEXING." TRANSPORT 31, no. 1 (January 28, 2015): 22–28. http://dx.doi.org/10.3846/16484142.2014.1003599.
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Global technologies of data transmission in real time are developing constantly. Therefore, modelling of messages transmission through satellite constellations is an actual problem. In this paper the original model of a communication channel ‘Vehicle-to-Satellite-to-Ground Station’ based on principles of the IEEE 802.11a standard is designed using MatLab Sіmulіnk software. The model allows simulating data transmission with data rate from 6 to 54 Mbit/s using adaptive modulation. Two types of channels were analysed for uplink/downlink modulation – a free space path losses with phase/frequency offset and Additive White Gaussian Noise (AWGN) link. On the base of this model, channel integrity was investigated and dependences of a Signal-Noise Ratio (SNR) on free space path losses, antennas diameters, number of OFDM symbols and satellite transponder noise temperature were received.
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Larsson, E. G. "Unitary nonuniform space-time constellations for the broadcast channel." IEEE Communications Letters 7, no. 1 (January 2003): 21–23. http://dx.doi.org/10.1109/lcomm.2002.807432.
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Maa, C. S., Y. C. Wang, and J. T. Chen. "Low-Complexity Channel-Adapted Space-Time Coding Scheme for Frequency-Selective Wireless MIMO Channels." IEEE Communications Letters 8, no. 2 (February 2004): 93–95. http://dx.doi.org/10.1109/lcomm.2004.823420.
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Birkinshaw, S. J. "Technical Note: Automatic river network generation for a physically-based river catchment model." Hydrology and Earth System Sciences Discussions 7, no. 3 (May 31, 2010): 3237–48. http://dx.doi.org/10.5194/hessd-7-3237-2010.
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Abstract. SHETRAN is a physically-based distributed modelling system that gives detailed simulations in time and space of water flow and sediment and solute transport in river catchments. Standard algorithms for the automatic generation of river channel networks from digital elevation data are impossible to apply in SHETRAN and other similar models because the river channels are assumed to run along the edges of grid cells. In this work a new algorithm for the automatic generation of a river channel network in SHETRAN is described and its use in an example catchment demonstrated.
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Birkinshaw, S. J. "Technical Note: Automatic river network generation for a physically-based river catchment model." Hydrology and Earth System Sciences 14, no. 9 (September 17, 2010): 1767–71. http://dx.doi.org/10.5194/hess-14-1767-2010.
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Abstract. SHETRAN is a physically-based distributed modelling system that gives detailed simulations in time and space of water flow and sediment and solute transport in river catchments. Standard algorithms for the automatic generation of river channel networks from digital elevation data are impossible to apply in SHETRAN and other similar models because the river channels are assumed to run along the edges of grid cells. In this work a new algorithm for the automatic generation of a river channel network in SHETRAN is described and its use in an example catchment demonstrated.
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Ball, Frank G., Robin K. Milne, and Geoffrey F. Yeo. "Marked Continuous-Time Markov Chain Modelling of Burst Behaviour for Single Ion Channels." Journal of Applied Mathematics and Decision Sciences 2007 (October 29, 2007): 1–14. http://dx.doi.org/10.1155/2007/48138.
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Patch clamp recordings from ion channels often show bursting behaviour, that is, periods of repetitive activity, which are noticeably separated from each other by periods of inactivity. A number of authors have obtained results for important properties of theoretical and empirical bursts when channel gating is modelled by a continuous-time Markov chain with a finite-state space. We show how the use of marked continuous-time Markov chains can simplify the derivation of (i) the distributions of several burst properties, including the total open time, the total charge transfer, and the number of openings in a burst, and (ii) the form of these distributions when the underlying gating process is time reversible and in equilibrium.
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Tian, Xiaowen, Ming Li, Guangyu Ti, and Wenfei Liu. "Fast Detection of Orthogonal Space-Time Block Codes With Unknown Channel." IEEE Communications Letters 20, no. 9 (September 2016): 1896–99. http://dx.doi.org/10.1109/lcomm.2016.2591548.
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Ying, Tengda, Wenjiang Feng, and Guoling Liu. "Space-Time Interference Alignment: DoF of Two-User MIMO X Channel With Alternating CSIT." IEEE Communications Letters 21, no. 5 (May 2017): 1167–70. http://dx.doi.org/10.1109/lcomm.2017.2654340.
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Chalise, Batu, and L. Vandendorpe. "Outage probability analysis of a MIMO relay channel with orthogonal space-time block codes." IEEE Communications Letters 12, no. 4 (April 2008): 280–82. http://dx.doi.org/10.1109/lcomm.2008.072142.
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Ball, Frank. "Aggregated Markov processes with negative exponential time interval omission." Advances in Applied Probability 22, no. 4 (December 1990): 802–30. http://dx.doi.org/10.2307/1427563.
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We consider a time reversible, continuous time Markov chain on a finite state space. The state space is partitioned into two sets, termed open and closed, and it is only possible to observe whether the process is in an open or a closed state. Further, short sojourns in either the open or closed states fail to be detected. We consider the situation when the length of minimal detectable sojourns follows a negative exponential distribution with mean μ–1. We show that the probability density function of observed open sojourns takes the form , where n is the size of the state space. We present a thorough asymptotic analysis of fO(t) as μ tends to infinity. We discuss the relevance of our results to the modelling of single channel records. We illustrate the theory with a numerical example.
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Ball, Frank. "Aggregated Markov processes with negative exponential time interval omission." Advances in Applied Probability 22, no. 04 (December 1990): 802–30. http://dx.doi.org/10.1017/s0001867800023144.
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We consider a time reversible, continuous time Markov chain on a finite state space. The state space is partitioned into two sets, termed open and closed, and it is only possible to observe whether the process is in an open or a closed state. Further, short sojourns in either the open or closed states fail to be detected. We consider the situation when the length of minimal detectable sojourns follows a negative exponential distribution with mean μ–1. We show that the probability density function of observed open sojourns takes the form , where n is the size of the state space. We present a thorough asymptotic analysis of f O(t) as μ tends to infinity. We discuss the relevance of our results to the modelling of single channel records. We illustrate the theory with a numerical example.
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Schneider, Wilhelm. "Solitary waves in turbulent open-channel flow." Journal of Fluid Mechanics 726 (May 30, 2013): 137–59. http://dx.doi.org/10.1017/jfm.2013.175.
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AbstractTwo-dimensional turbulent free-surface flow is considered. The ensemble-averaged flow quantities may depend on time. The slope of the plane bottom of the channel is assumed to be small. The roughness of the bottom is allowed to vary with the space coordinate, leading to small variations in the bottom friction coefficient. An asymptotic analysis, which is free of turbulence modelling, is performed for large Reynolds numbers and Froude numbers close to the critical value 1. As a result, an extended Korteweg–deVries (KdV) equation for the surface elevation is obtained. Other flow quantities, such as pressure, flow velocity components, and bottom shear stress, are expressed in terms of the surface elevation. The steady-state version of the extended KdV equation has eigensolutions that describe stationary solitary waves. Time-dependent solutions of the extended KdV equation provide a means for discriminating between stable and unstable stationary solitary waves. Solutions of initial value problems show that there are transient solutions that approach asymptotically the stable stationary solitary wave, whereas other transient solutions decay asymptotically with increasing time.
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Guegueniat, P., J. C. Salomon, M. Wartel, L. Cabioch, and A. Fraizier. "Transfer Pathways and Transit Time of Dissolved Matter in the Eastern English Channel Indicated by Space-Time Radiotracers Measurement and Hydrodynamic Modelling." Estuarine, Coastal and Shelf Science 36, no. 5 (May 1993): 477–94. http://dx.doi.org/10.1006/ecss.1993.1029.
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Changjiang Xu and T. Le-Ngoc. "CM-based channel estimators for space-time block-coded M-PSK and M-QAM systems." IEEE Communications Letters 7, no. 7 (July 2003): 311–13. http://dx.doi.org/10.1109/lcomm.2003.814717.
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Ya Rudyak, V., and E. V. Lezhnev. "Direct stochastic molecular modelling of transport processes in gases." Journal of Physics: Conference Series 2056, no. 1 (October 1, 2021): 012003. http://dx.doi.org/10.1088/1742-6596/2056/1/012003.
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Abstract The stochastic molecular modeling method (SMM) of transport processes in rarefied gases developed by the authors is systematically discussed in this paper. It is shown that, it is possible to simulate the transport coefficients of rarefied gas with high accuracy, using a relatively small number of molecules. The data of modeling the thermal conductivity coefficient are presented for the first time. The second part of the paper is devoted to the generalization of the SMM method for modeling transport processes in confined conditions. To describe the dynamics of molecules in this case, the splitting of their evolution by processes is used: first, the movement of molecules in the configuration space is simulated, and then their dynamics in the velocity space is imitated. Anisotropy of viscosity and thermal conductivity in nanochannels has been established. The interaction of gas molecules with walls is described by specular or specular-diffuse reflection laws. Gas viscosity can be either greater than in the bulk or less, depending on the law of gas interaction with the channel walls.
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Lei, Xianfu, and Pingzhi Fan. "Comment on "Outage Probability Analysis of a MIMO Relay Channel with Orthogonal Space-Time Block Codes"." IEEE Communications Letters 12, no. 10 (October 2008): 720–21. http://dx.doi.org/10.1109/lcomm.2008.080694.
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Hu, Shaowen, and Edward Semones. "Calibration of the GOES 6–16 high-energy proton detectors based on modelling of ground level enhancement energy spectra." Journal of Space Weather and Space Climate 12 (2022): 5. http://dx.doi.org/10.1051/swsc/2022003.
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For several decades, the Geostationary Operational Environmental Satellites (GOES) series have provided both real-time and historical data for radiation exposure estimation and solar proton radiation environment modelling. Recently, several groups conducted calibration studies that significantly reduced the uncertainties on the response of GOES proton detectors, thus improving the reliability of the spectral observations of solar energetic particle events. In this work, the long-established Band function fitting set for past ground level enhancements (GLEs) and their recent revision are used as references to estimate the best matching energies of proton channels of GOES 6–16, with emphasis on comparing with previous calibration studies on the high energetic proton measurements. The calculated energies for different missions in the same series (GOES 8, 10, 11) show overall consistency but with small variations, and differences among missions of different series are noticeable for measurements crossing the past three solar cycles, though the results are sensitive to the method used to subtract background fluxes. The discrepancy and agreement with previous calibration efforts are demonstrated with other independent analyses. It is verified that the integral channel P11 of GOES 6–16 can be reliably used as a differential proton channel with an effective energy of about 1 GeV. Therefore, the multi-decade in situ measurements of the GOES series can be utilized with more extensive energy coverage to improve space radiation environment models.
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Jiang, Yanji, Youli Qiu, Xueli Shen, Chuan Sun, and Haitao Liu. "SuperFormer: Enhanced Multi-Speaker Speech Separation Network Combining Channel and Spatial Adaptability." Applied Sciences 12, no. 15 (July 29, 2022): 7650. http://dx.doi.org/10.3390/app12157650.
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Speech separation is a hot topic in multi-speaker speech recognition. The long-term autocorrelation of speech signal sequences is an essential task for speech separation. The keys are effective intra-autocorrelation learning for the speaker’s speech, modelling the local (intra-blocks) and global (intra- and inter- blocks) dependence features of the speech sequence, with the real-time separation of as few parameters as possible. In this paper, the local and global dependence features of speech sequence information are extracted by utilizing different transformer structures. A forward adaptive module of channel and space autocorrelation is proposed to give the separated model good channel adaptability (channel adaptive modeling) and space adaptability (space adaptive modeling). In addition, at the back end of the separation model, a speaker enhancement module is considered to further enhance or suppress the speech of different speakers by taking advantage of the mutual suppression characteristics of each source signal. Experiments show that the scale-invariant signal-to-noise ratio improvement (SI-SNRi) of the proposed separation network on the public corpus WSJ0-2mix achieves better separation performance compared with the baseline models. The proposed method can provide a solution for speech separation and speech recognition in multi-speaker scenarios.
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Watt, S. D., and A. J. Roberts. "The construction of zonal models of dispersion in channels via matched centre manifolds." Journal of the Australian Mathematical Society. Series B. Applied Mathematics 38, no. 1 (July 1996): 101–25. http://dx.doi.org/10.1017/s0334270000000497.
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AbstractTaylor's model of dispersion simply describes the long-term spread of material along a pipe, channel or river. However, often we need multi-mode models to resolve finer details in space and time. Here we construct zonal models of dispersion via the new principle of matching their long-term evolution with that of the original problem. Using centre manifold techniques this is done straightforwardly and systematically. Furthermore, this approach provides correct initial and boundary conditions for the zonal models. We expect the proposed principle of matched centre manifold evolution to be useful in a wide range of modelling problems.
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Mallik, M. S. I., M. A. Hoque, and M. A. Uddin. "Comparative Study of Standard Smagorinsky Model and Dynamic Smagorinsky Model in Large Eddy Simulation of Turbulent Channel Flow." Journal of Scientific Research 12, no. 1 (January 1, 2020): 39–53. http://dx.doi.org/10.3329/jsr.v12i1.41924.
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This paper presents results of comparative study of large eddy simulation (LES) that is applied to a plane turbulent channel flow. The LES is performed by using a finite difference method of second order accuracy in space and a low-storage explicit Runge-Kutta method with third order accuracy in time. In the LES for subgrid-scale (SGS) modelling, Standard Smagorinsky Model (SSM) and Dynamic Smagorinsky Model (DSM) are used. Essential turbulence statistics from the two LES approaches are calculated and compared with those from direct numerical simulation (DNS) data. Comparing the results throughout the calculation domain, it has been found out that SSM performs better than DSM in the turbulent channel flow simulation. Flow structures in the computed flow field by the SSM and DSM are also discussed and compared through the contour plots and iso-surfaces.
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Kasprak, Alan, James Brasington, Konrad Hafen, Richard D. Williams, and Joseph M. Wheaton. "Modelling braided river morphodynamics using a particle travel length framework." Earth Surface Dynamics 7, no. 1 (March 14, 2019): 247–74. http://dx.doi.org/10.5194/esurf-7-247-2019.
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Abstract. Numerical models that predict channel evolution are an essential tool for investigating processes that occur over timescales which render field observation intractable. The current generation of morphodynamic models, however, either oversimplify the relevant physical processes or, in the case of more physically complete codes based on computational fluid dynamics (CFD), have computational overheads that severely restrict the space–time scope of their application. Here we present a new, open-source, hybrid approach that seeks to reconcile these modelling philosophies. This framework combines steady-state, two-dimensional CFD hydraulics with a rule-based sediment transport algorithm to predict particle mobility and transport paths which are used to route sediment and evolve the bed topography. Data from two contrasting natural braided rivers (Rees, New Zealand, and Feshie, United Kingdom) were used for model verification, incorporating reach-scale quantitative morphological change budgets and volumetric assessment of different braiding mechanisms. The model was able to simulate 8 of the 10 empirically observed braiding mechanisms from the parameterized bed erosion, sediment transport, and deposition. Representation of bank erosion and bar edge trimming necessitated the inclusion of a lateral channel migration algorithm. Comparisons between simulations based on steady effective discharge versus event hydrographs discretized into a series of model runs were found to only marginally increase the predicted volumetric change, with greater deposition offsetting erosion. A decadal-scale simulation indicates that accurate prediction of event-scale scour depth and subsequent deposition present a methodological challenge because the predicted pattern of deposition may never “catch up” to erosion if a simple path-length distribution is employed, thus resulting in channel over-scouring. It may thus be necessary to augment path-length distributions to preferentially deposit material in certain geomorphic units. We anticipate that the model presented here will be used as a modular framework to explore the effect of different process representations, and as a learning tool designed to reveal the relative importance of geomorphic transport processes in rivers at multiple timescales.
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Fortunati, Alessandro, and Stephen Wiggins. "Transient Invariant and Quasi-Invariant Structures in an Example of an Aperiodically Time Dependent Fluid Flow." International Journal of Bifurcation and Chaos 28, no. 05 (May 2018): 1830015. http://dx.doi.org/10.1142/s021812741830015x.
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Starting from the concept of invariant KAM tori for nearly-integrable Hamiltonian systems with periodic or quasi-periodic nonautonomous perturbation, the paper analyzes the “analogue” of this class of invariant objects when the dependence on time is aperiodic. The investigation is carried out in a model motivated by the problem of a traveling wave in a channel over a smooth, quasi- and asymptotically flat (from which the “transient” feature) bathymetry, representing a case in which the described structures play the role of barriers to fluid transport in phase space. The paper provides computational evidence for the existence of transient structures also for “large” values of the perturbation size, as a complement to the rigorous results already proven by the first author for real-analytic bathymetry functions.
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Dichev, Dimitar, Hristofor Koev, and Petr Louda. "A MEASURING SYSTEM WITH AN ADDITIONAL CHANNEL FOR ELIMINATING THE DYNAMIC ERROR." Journal of Theoretical and Applied Mechanics 44, no. 1 (March 1, 2014): 3–20. http://dx.doi.org/10.2478/jtam-2014-0001.
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Abstract The present article views a measuring system for determining the parameters of vessels. The system has high measurement accuracy when operating in both static and dynamic mode. It is designed on a gyro-free principle for plotting a vertical. High accuracy of measurement is achieved by using a simplified design of the mechanical module as well by minimizing the instrumental error. A new solution for improving the measurement accuracy in dynamic mode is offered. The approach presented is based on a method where the dynamic error is eliminated in real time, unlike the existing measurement methods and tools where stabilization of the vertical in the inertial space is used. The results obtained from the theoretical experiments, which have been performed on the basis of the developed mathematical model, demonstrate the effectiveness of the suggested measurement approach.
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DOKHANE, A., D. HENNIG, R. CHAWLA, and RIZWAN-UDDIN. "SEMI-ANALYTICAL BIFURCATION ANALYSIS OF TWO-PHASE FLOW IN A HEATED CHANNEL." International Journal of Bifurcation and Chaos 15, no. 08 (August 2005): 2395–409. http://dx.doi.org/10.1142/s0218127405013381.
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Using a drift flux representation for the two-phase flow, a new reduced order model has been developed to simulate density-wave oscillations (DWOs) in a heated channel. This model is then used to perform stability and semi-analytical bifurcation analysis, using the bifurcation code BIFDD, in which the stability boundary (SB) and the nature of Hopf bifurcation are determined in a suitable two-dimensional parameter space. A comparative study is carried out to investigate the effects of the parameters in the drift flux model (DFM) — the radially void distribution parameter C0 and the drift velocity Vgj — on the SB as well as on the nature of Hopf bifurcation. It is the first time that a systematic analysis has been carried out to investigate the effects of DFM parameters on the nature of Hopf bifurcation in a heated-channel two-phase flow. The results obtained show that both sub- and super-critical Hopf bifurcations are encountered. In addition, it has been found that, while the SB is sensitive to both C0 and Vgj, the nature of Hopf bifurcation for lower values of N sub is more sensitive to Vgj than to C0. Numerical integration of the set of ODEs is carried out to confirm the predictions of the semi-analytical bifurcation analysis.
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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: models of flow generation and propagation/routing." Geoscientific Model Development 4, no. 4 (November 4, 2011): 943–55. http://dx.doi.org/10.5194/gmd-4-943-2011.
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Abstract. This paper presents a discussion of the predictive capacity of the implementation of the semi-distributed hydrological modeling system JGrass-NewAge. This model focuses on the hydrological budgets of medium scale to large scale basins as the product of the processes at the hillslope scale with the interplay of the river network. The part of the modeling system presented here deals with the: (i) estimation of the space-time structure of precipitation, (ii) estimation of runoff production; (iii) aggregation and propagation of flows in channel; (v) estimation of evapotranspiration; (vi) automatic calibration of the discharge with the method of particle swarming. The system is based on a hillslope-link geometrical partition of the landscape, combining raster and vectorial treatment of hillslope data with vector based tracking of flow in channels. Measured precipitation are spatially interpolated with the use of kriging. Runoff production at each channel link is estimated through a peculiar application of the Hymod model. Routing in channels uses an integrated flow equation and produces discharges at any link end, for any link in the river network. Evapotranspiration is estimated with an implementation of the Priestley-Taylor equation. The model system assembly is calibrated using the particle swarming algorithm. A two year simulation of hourly discharge of the Little Washita (OK, USA) basin is presented and discussed with the support of some classical indices of goodness of fit, and analysis of the residuals. A novelty with respect to traditional hydrological modeling is that each of the elements above, including the preprocessing and the analysis tools, is implemented as a software component, built upon Object Modelling System v3 and jgrasstools prescriptions, that can be cleanly switched in and out at run-time, rather than at compiling time. The possibility of creating different modeling products by the connection of modules with or without the calibration tool, as for instance the case of the present modeling chain, reduces redundancy in programming, promotes collaborative work, enhances the productivity of researchers, and facilitates the search for the optimal modeling solution.
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PANDEY, S. K., and DHARMENDRA TRIPATHI. "PERISTALTIC TRANSPORT OF A CASSON FLUID IN A FINITE CHANNEL: APPLICATION TO FLOWS OF CONCENTRATED FLUIDS IN OESOPHAGUS." International Journal of Biomathematics 03, no. 04 (December 2010): 453–72. http://dx.doi.org/10.1142/s1793524510001100.
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This model is targeted to study the swallowing of peristaltically driven food stuff such as jelly, tomato puree, soup, concentrated fruit juices and honey in the aboral direction confined to an oesophagus by modeling it as finite channel. Considering such highly concentrated fluids as Casson fluid in the fully stretched activated state, the dependence of pressure on space and time has been investigated for time averaged flow rate. Pressure distribution has been studied along the oesophageal length for an integral and also a non-integral number of waves at different time instants. Local wall shear stress and the role of yield stress have also been the areas of investigation. Mechanical efficiency of oesophageal pump during the Casson food transportation has been obtained. Reflux limit of perstaltically driven flow of Casson food bolus has also been discussed. The effect of Casson food bolus vis-à-vis Newtonian food bolus has been compared analytically, numerically and computationally from investigation point of view. It is observed that the pressure distribution is even and uneven respectively for the case of integral and non-integral number of waves. It is also concluded that it is not as easy to swallow Casson fluids (such as concentrated jelly, honey, soup, juice, etc.) as Newtonian fluids (such as water). As plug flow region widens, the pressure difference increases, indicating thereby that the averaged flow rate will be less for a Casson fluid. Physically, the oesophagus works more to swallow fluids with high concentration. It is also inferred that such fluids are more prone to reflux.
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Gilson, James G. "Classical fluid aspects of nonlinear Schrödinger equations and solitons." Journal of Applied Mathematics and Simulation 1, no. 2 (January 1, 1987): 99–114. http://dx.doi.org/10.1155/s1048953388000085.
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The author extends his alternative theory for Schrödinger quantum mechanics by introducing the idea of energy reference strata over configuration space. It is then shown that the view from various such strata defines, the content of the system of interest and enables a variety of different descriptions of events in the same space time region. Thus according to the point of view or energy stratum chosen so the type of Schrödinger equation, linear or otherwise, appropriate to describe the system is determined. A nonlinear information channel between two dimensional fluid action in hyperspace into two dimensional energy hyperspace is shown to exist generally as a background to nonlinear Schrödinger structures. In addition it is shown how soliton solutions of the one dimensional Schrödinger equation are related to two dimensional vortex fields in hyperspace.
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Arnaud, Fanny, Lalandy Sehen Chanu, Jules Grillot, Jérémie Riquier, Hervé Piégay, Dad Roux-Michollet, Georges Carrel, and Jean-Michel Olivier. "Historical cartographic and topo-bathymetric database on the French Rhône River (17th–20th century)." Earth System Science Data 13, no. 5 (May 10, 2021): 1939–55. http://dx.doi.org/10.5194/essd-13-1939-2021.
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Abstract. Space and time analyses of channel changes, especially within large rivers subject to high levels of human impact, are critical to address multiple questions about rivers in the Anthropocene era. The reconstruction of long-term (> 150 year) evolutionary trajectories permits an understanding of how natural and anthropogenic factors impact hydromorphological and ecological processes in rivers, helps with the design of sustainable management and restoration options, and may also help in the assessment of future changes. However, the reconstruction of channel changes can be challenging: historical data are often scattered across many archives, and the quantity and accuracy of information generally decreases as one goes back in time. This data article provides a historical database of 350 cartographic and topo-bathymetric resources on the French Rhône River (530 km in length) compiled from the 17th to mid-20th century, with a temporal focus prior to extensive river training (1860s). The data were collected in 14 national, regional, and departmental archive services. A table describes the properties of each archived data item and its associated iconographic files. Some of the historical maps are available in a georeferenced format. A GIS layer enables one-click identification of all archive data available for a given reach of the French Rhône River. This database provides substantial new material for deeper analyses of channel changes over a longer time period and at a finer time step compared with previously available data. The database has several potential applications in geomorphology, retrospective hydraulic modelling, historical ecology, and river restoration, as well as permitting comparisons with other multi-impacted rivers worldwide. The dataset is available at https://doi.org/10.1594/PANGAEA.922437 (Arnaud et al., 2020a). Iconographic extracts of the 350 archived items are available at http://photo.driihm.fr/index.php/category/52 (last access: 2 May 2021).
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Kilsby, C. G., J. Ewen, W. T. Sloan, A. Burton, C. S. Fallows, and P. E. O'Connell. "The UP modelling system for large scale hydrology: simulation of the Arkansas-Red River basin." Hydrology and Earth System Sciences 3, no. 1 (March 31, 1999): 137–49. http://dx.doi.org/10.5194/hess-3-137-1999.
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Abstract. The UP (Upscaled Physically-based) hydrological modelling system to the Arkansas-Red River basin (USA) is designed for macro-scale simulations of land surface processes, and aims for a physical basis and, avoids the use of discharge records in the direct calibration of parameters. This is achieved in a two stage process: in the first stage parametrizations are derived from detailed modelling of selected representative small and then used in a second stage in which a simple distributed model is used to simulate the dynamic behaviour of the whole basin. The first stage of the process is described in a companion paper (Ewen et al., this issue), and the second stage of this process is described here. The model operated at an hourly time-step on 17-km grid squares for a two year simulation period, and represents all the important hydrological processes including regional aquifer recharge, groundwater discharge, infiltration- and saturation-excess runoff, evapotranspiration, snowmelt, overland and channel flow. Outputs from the model are discussed, and include river discharge at gauging stations and space-time fields of evaporation and soil moisture. Whilst the model efficiency assessed by comparison of simulated and observed discharge records is not as good as could be achieved with a model calibrated against discharge, there are considerable advantages in retaining a physical basis in applications to ungauged river basins and assessments of impacts of land use or climate change.
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Rees, John G. "Sea-level, topographical and sediment supply controls on Holocene sediment composition in the Humber Estuary, UK." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1841 (February 22, 2006): 993–1008. http://dx.doi.org/10.1098/rsta.2006.1750.
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To increase our understanding of the relative control of antecedent topography, sediment supply and sea-level change on grain size and organic content in the Humber Estuary, the composition of its Holocene fill over space and time has been evaluated. A model based-upon bed-by-bed description of over 3500 boreholes was sub-horizontally ‘sliced’ to analyse the composition of sediments in different parts of the estuary across the entire fill, as well as solely within estuary marginal sequences. Results demonstrate that different physiographic parts of the estuary are characterized by distinctive vertical sediment profiles that reflect the relative control of antecedent topography as well as sea-level upon them. The results raise questions about the processes controlling sand and gravel abundance in marginal sequences, where the estuary is physiographically most constrained. This semi-quantitative evaluation, the first of its kind on an estuarine fill, provides a technique for interpreting the relative importance of controls on an estuarine system, but highlights the need for improved modelling of estuarine channel form and dynamics over centurial to millennial time-scales.
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Pochwat, Kamil. "Assessment of Rainwater Retention Efficiency in Urban Drainage Systems—Model Studies." Resources 11, no. 2 (January 27, 2022): 14. http://dx.doi.org/10.3390/resources11020014.
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Around the world, there is growing interest in the use of rainwater retention, and in particular channel retention, as part of urban drainage systems. This is made possible by means of intentional damming of rainwater in the existing sewer collectors in order to maximise the use of gravitational spaces in the channels. This approach is particularly favourable for drainage types related to high levels of urban development, where construction of a building is difficult due to the low amount of space available. This article explains the results of a study concerning the efficiency assessment of three retention devices characterised by different hydraulic systems, one of which uses channel retention in its operation. The analysis conducted within the simulation study has demonstrated that the use of standard single-chamber reservoirs is the least efficient solution. A comparison of the functions of different hydraulic systems of retention reservoirs under equal conditions has shown that the necessary retention capacity of a single-chamber reservoir is many times greater in comparison to highly efficient solutions and it may constitute up to 582% of the reservoir’s capacity and works in conjunction with the channel retention system. At the same time, it has been demonstrated that the application of channel retention is not the most efficient solution for all hydraulic conditions for a drainage system or for all hydrological conditions. In addition, the article proposes a set of retention efficiency indices that may be used in the future assessment of individual rainwater storage solutions. Estimation of the necessary capacity of the retention facilities operating in specific hydraulic conditions was made on the basis of model tests—hydrodynamic modelling with the use of SWMM 5.0 software. The course of the research was planned using the theory of experiment planning (DOE) with the use of Statistica software, whereas efficiency indices were developed with the use of artificial neural networks (ANNs). The study results include practical and cognitive aspects. These may constitute guidelines for the designers and potential investors, as well as a tool with the aim of promoting the most efficient rainwater retention solutions in urban drainage systems.
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Veith, Irina, Arianna Mencattini, Valentin Picant, Marco Serra, Marine Leclerc, Maria Colomba Comes, Fathia Mami-Chouaib, et al. "Apoptosis mapping in space and time of 3D tumor ecosystems reveals transmissibility of cytotoxic cancer death." PLOS Computational Biology 17, no. 3 (March 30, 2021): e1008870. http://dx.doi.org/10.1371/journal.pcbi.1008870.
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The emerging tumor-on-chip (ToC) approaches allow to address biomedical questions out of reach with classical cell culture techniques: in biomimetic 3D hydrogels they partially reconstitute ex vivo the complexity of the tumor microenvironment and the cellular dynamics involving multiple cell types (cancer cells, immune cells, fibroblasts, etc.). However, a clear bottleneck is the extraction and interpretation of the rich biological information contained, sometime hidden, in the cell co-culture videos. In this work, we develop and apply novel video analysis algorithms to automatically measure the cytotoxic effects on human cancer cells (lung and breast) induced either by doxorubicin chemotherapy drug or by autologous tumor-infiltrating cytotoxic T lymphocytes (CTL). A live fluorescent dye (red) is used to selectively pre-stain the cancer cells before co-cultures and a live fluorescent reporter for caspase activity (green) is used to monitor apoptotic cell death. The here described open-source computational method, named STAMP (spatiotemporal apoptosis mapper), extracts the temporal kinetics and the spatial maps of cancer death, by localizing and tracking cancer cells in the red channel, and by counting the red to green transition signals, over 2–3 days. The robustness and versatility of the method is demonstrated by its application to different cell models and co-culture combinations. Noteworthy, this approach reveals the strong contribution of primary cancer-associated fibroblasts (CAFs) to breast cancer chemo-resistance, proving to be a powerful strategy to investigate intercellular cross-talks and drug resistance mechanisms. Moreover, we defined a new parameter, the ‘potential of death induction’, which is computed in time and in space to quantify the impact of dying cells on neighbor cells. We found that, contrary to natural death, cancer death induced by chemotherapy or by CTL is transmissible, in that it promotes the death of nearby cancer cells, suggesting the release of diffusible factors which amplify the initial cytotoxic stimulus.
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Uzdenova, Aminat. "2D Mathematical Modelling of Overlimiting Transfer Enhanced by Electroconvection in Flow-Through Electrodialysis Membrane Cells in Galvanodynamic Mode." Membranes 9, no. 3 (March 11, 2019): 39. http://dx.doi.org/10.3390/membranes9030039.
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Flow-through electrodialysis membrane cells are widely used in water purification and the processing of agricultural products (milk, wine, etc.). In the research and operating practice of such systems, a significant place is occupied by a galvanodynamic (or galvanostatic) mode. 2D mathematical modelling of ion transfer in the galvanodynamic mode requires solving the problem of setting the average current density equal to a certain value, while the current density distribution in the system is uneven. This article develops a 2D mathematical model of the overlimiting transfer enhanced by electroconvection in a flow-through electrodialysis cell in the galvanodynamic mode. The model is based on the system of Navier–Stokes, Nernst–Planck, Poisson equations and equations for the electric current stream function. To set the electric mode we use a boundary condition, relating the electric field strength and current density. This approach allows us to describe the formation of the extended space charge region and development of electroconvection at overlimiting currents. For the first time, chronopotentiograms and current–voltage characteristics of the membrane systems are calculated for the galvanodynamic mode taking into account the forced flow and development of electroconvection. The behaviors of the calculated chronopotentiograms and current–voltage characteristic coincide qualitatively with experimental data. The effects of the electrolyte concentration, forced flow velocity and channel size on the mass transfer at overlimiting currents are estimated.
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Bianchi, Valeria, Troy Smith, and Joan Esterle. "Stratigraphic forward model of Springbok Sandstone sedimentation controlled by dynamic topography." APPEA Journal 56, no. 2 (2016): 600. http://dx.doi.org/10.1071/aj15106.
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After a long history of conventional gas exploration, the eastern Surat Basin in Queensland has developed as an active regional exploration target for coal seam gas, hosting large gas reserves. Interest in understanding basin fill mechanisms for petroliferous basins has grown in response to their economic significance. The Surat Basin is characterised by sedimentary successions with geometric complexity due to difficulty in correlation of coal splitting, interburden facies, and overburden channel belts. The uncertainty increases away from well control, in particular towards the centre where the basin is sparsely drilled. The forward modelling in LECODE (landscape evolution climate ocean and dynamic earth) is an innovative geomorphic and stratigraphic forward modelling code capable of simulating surface evolution and clastic sedimentary processes in 3D through geological time. This numerical tool can be used to test geological scenarios and predict the associated grain size distribution and sediment dispersal as a high-resolution synthetic stratigraphic record. This work focuses on a stratigraphic forward model developed for the Springbok Formation (Late Jurassic) within the Surat Basin. The simulated stratigraphy matches with models proposed by companies, highlighting a depocenter trending northwest–southeast. The formation is divided in two units: lower Springbok, defined by a fining-upward sequence and characterised by high-accommodation space and overfilling processes; and upper Springbok, described as an overall fining-upward sequence, with locally coarsening-upward wedge (conformable with the Weald Sandstone). The 3D basin simulation forecasts high heterogeneity of depositional geometries and stratal termination in depocentral and marginal areas.
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ZHAO, WEI, ZHIBIN MAO, and XINYA TAO. "APPLICATION OF FRACTAL DIMENSION OF FRACTIONAL BROWNIAN MOTION TO SUPPLY CHAIN FINANCING AND OPERATIONAL COMPREHENSIVE DECISION-MAKING." Fractals 28, no. 08 (July 10, 2020): 2040019. http://dx.doi.org/10.1142/s0218348x20400198.
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For a long time, the mismatch between material flow and capital flow in the supply chain operation management practice is very prominent, which has led to the inefficiency of supply chain operation and hindered the exertion of supply chain’s advantages. In the field of supply chain management theory research, the information completeness in capital market has long been a hypothetical premise, which has led to the separation of corporate financing and operational decision-making research. In addition to production, inventory, procurement, pricing and other strategies in supply chain operations, payment options and credit incentives are also important decisions for both parties, especially for products with long production and sales cycles; different payment methods directly affect corporate capital flows and the enterprise’s long-term development. On the basis of summarizing and analyzing previous works, this paper analyzed the research status and significance of supply chain financing and operational comprehensive decision-making, expounded the development background, current situation, and future challenges of the fractal dimension of fractional Brownian motion; elaborated the principles and methods of the scaling properties of fractional Brownian motion and the phase space reconstruction of time series, established a financial management analysis model based on the fractal dimension of fractional Brownian motion, performed the analysis of the agglomeration degree, time series and multi-fractal characteristics of supply chain financing, explored the coupling relationship between the comprehensive operational decision-making and Brownian motion’s scaling properties. The final empirical analysis showed that when own funds are sufficient, the production should be carried out with the goal of maximizing profits, and full consideration should be given customer channel stickiness, relative costs of offline and online channel products, and product profitability; the proposed analysis model can achieve the optimal order quantity in supply chain, and reach risk and benefit sharing among financial institutions, retailers, and suppliers by setting the financing interest rate, wholesale price, repurchase price and other parameters, thereby improving supply chain performance. This study results of this paper provided a reference for further researches on the application of fractal dimension of the fractional Brownian motion to the supply chain financing and operational comprehensive decision-making.
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Kirsal, Yonal, Vishnu Vardhan Paranthaman, and Glenford Mapp. "Exploring Analytical Models for Proactive Resource Management in Highly Mobile Environments." International Journal of Computers Communications & Control 13, no. 5 (September 29, 2018): 837–52. http://dx.doi.org/10.15837/ijccc.2018.5.3349.
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In order to provide ubiquitous communication, seamless connectivity is now required in all environments including highly mobile networks. By using vertical handover techniques it is possible to provide uninterrupted communication as connections are dynamically switched between wireless networks as users move around. However, in a highly mobile environment, traditional reactive approaches to handover are inadequate. Therefore, proactive handover techniques, in which mobile nodes attempt to determine the best time and place to handover to local networks, are actively being investigated in the context of next-generation mobile networks. Using this approach, it is possible to enhance channel allocation and resource management by using probabilistic mechanisms; because, it is possible to explicitly detect contention for resources. This paper presents a proactive approach for resource allocation in highly mobile networks and analyzed the user contention for common resources such as radio channels in highly mobile wireless networks. The proposed approach uses an analytical modelling approach to model the contention and results are obtained showing enhanced system performance. Based on these results an operational space has been explored and are shown to be useful for emerging future networks such as 5G by allowing base stations to calculate the probability of contention based on the demand for network resources. This study indicates that the proactive model enhances handover and resource allocation for highly mobile networks. This paper analyzed the effects of and alpha and beta, in effect, how these parameters affect the proactive resource allocation requests in the contention queue has been modelled for any given scenario from the conference paper "Exploring analytical models to maintain quality-of-service for resource management using a proactive approach in highly mobile environments".
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Oleynik, Marina A., and Alexandr S. Gorbatovsky. "MULTIMODALITY OF A PRECEDENT TEXT IN THE RESEARCH OF THE CULTURAL SPACE OF A LITERARY TEXT." German Philology at the St Petersburg State University 12 (2022): 19–31. http://dx.doi.org/10.21638/spbu33.2022.101.
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The article aims to describe the phenomenon of “precedence” in its multimodal specificity, which is realized in the process of recreating cultural space in a literary text. The authors rely on the achievements of modern linguocultural studies of the relationship between language and culture, which focus on the consideration of paradigmatic and syntagmatic relations of linguistic units, modelling the cultural space in the texts. At the same time, the possibility of realization by language units of their semiotic nature is taken into account, the peculiarities of its manifestation are determined by this or that context in the structure of precedent texts. The novelty of the research lies in the application of the theory of multimodality to the study of the precedent text as an element of cultural space in a literary text. One of the main questions is which units of a precedent text create prerequisites for its multimodality and how these units are interconnected with each other. Taking into account the denotative meaning of lexical units that verbalize the “channel” of information transmission and the recipient’s perception of this information, we can identify in the empirical material explicit and implicit ways of implementing the multimodality of precedent texts. The results of the analysis of the key lexemes of precedent texts served as the basis for characterizing multimodality, they are descriptive and were obtained with the help of comparative method, as well as the method of semantic, contextual and linguocultural analysis. The article suggests the multimodality of the precedent text not only contributes to the transmission of additional culturally significant information, due to which the cultural space in the literary text is modelled, but also allows the literary text itself to reveal its multimodal character. The material for the study is the novels “Der Weltensammler” by I.Trojanow, “1913: Der Sommer des Jahrhunderts” by F.Illias, and “Tyll” by D.Kehlmann, whose plots are set against the background of culturally significant historical events.
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Pankratov, Evgeny L., and Elena A. Bulaeva. "An analytical approach for analysis and optimization of formation of field-effect heterotransistors." Multidiscipline Modeling in Materials and Structures 12, no. 4 (November 14, 2016): 578–604. http://dx.doi.org/10.1108/mmms-09-2015-0057.
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Purpose The purpose of this paper is to analyze and optimize the formation of field-effect heterotransistors using analytical approach. The approach makes it possible to analyze mass and heat transport in a multilayer structure without cross-linking of solutions on interfaces between layers of the multilayer structure. The optimization makes it possible to decrease dimensions of the heterotransistors and to increase speed of transport of charge carriers during functioning of the transistors. Design/methodology/approach The authors introduce an analytical approach for analysis of mass and heat transport, which makes it possible to take into account at one time varying in space and time parameters of the transports (diffusion coefficient, heat conduction coefficient, etc.) and nonlinearity of processes. The approach enables analysis of mass and heat transport in a multilayer structure without cross-linking of solutions on interfaces between layers of the multilayer structure and optimises the technological process. The optimization means it is possible to decrease dimensions of field-effect heterotransistors. Findings In this paper the authors introduce an approach to manufacture a field-effect heterotransistor with inhomogeneous doping of channel. Some recommendations to optimize technological process to manufacture more compact distribution of concentration of dopant have been formulated. Originality/value The results are original and the paper provides an approach to the manufacture of a field-effect heterotransistor.
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Viel, Vincent, Monique Fort, Candide Lissak, Kevin Graff, Benoît Carlier, Gilles Arnaud-Fassetta, Etienne Cossart, and Malika Madelin. "Debris-flow functioning and their contribution to sedimentary budgets: the Peynin subcatchment of the Guil River (Upper Queyras, Southern French Alps)." Landform Analysis 36 (December 30, 2018): 71–84. http://dx.doi.org/10.12657/landfana.036.007.
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The Peynin catchment (15 km2) is prone to catastrophic floods (June 1957 – Recurrence Interval R.I.>100 yr), June 2000 (R.I.-30 yr) with serious damages to infrastructure and buildings located at the outlet. In this paper, PIT tags tracers and Vensim modelling software are used to better assess the sediment delivery unsteadiness, and more specifically to evaluate the respective role of geomorphological processes on sediment supply during flood event. For the last 20 years, our results highlight a significant variability in sediment delivery from a tributary to another one. According to our studies, we suppose that two torrential tributaries of the Peynin river, the Peyronnelle and Three Arbres subcatchments (<2 km2, representing <15% of the Peynin catchment area) are responsible of 80% of the sediments observed at the outlet of the catchment. Several processes take a part of these sediment transfers, but the efficiency of the sediment cascade in this catchment can be explained by a strong connectivity between sediment erosion area and the main channel of the catchment. Debris and torrential flows triggered during high intensity meteorological event are actually effectively coupled in space and time and guarantee an important sediment supply able to reload the downstream part of the sediment cascade. Recent climate trends, marked by extremes, suggest consequently more damaging events to come, in a context of increasing vulnerable assets
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Drago, A. F., R. Sorgente, and A. Ribotti. "A high resolution hydrodynamic 3-D model simulation of the malta shelf area." Annales Geophysicae 21, no. 1 (January 31, 2003): 323–44. http://dx.doi.org/10.5194/angeo-21-323-2003.
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Abstract. The seasonal variability of the water masses and transport in the Malta Channel and proximity of the Maltese Islands have been simulated by a high resolution (1.6 km horizontal grid on average, 15 vertical sigma layers) eddy resolving primitive equation shelf model (ROSARIO-I). The numerical simulation was run with climatological forcing and includes thermohaline dynamics with a turbulence scheme for the vertical mixing coefficients on the basis of the Princeton Ocean Model (POM). The model has been coupled by one-way nesting along three lateral boundaries (east, south and west) to an intermediate coarser resolution model (5 km) implemented over the Sicilian Channel area. The fields at the open boundaries and the atmospheric forcing at the air-sea interface were applied on a repeating "perpetual" year climatological cycle. The ability of the model to reproduce a realistic circulation of the Sicilian-Maltese shelf area has been demonstrated. The skill of the nesting procedure was tested by model-modelc omparisons showing that the major features of the coarse model flow field can be reproduced by the fine model with additional eddy space scale components. The numerical results included upwelling, mainly in summer and early autumn, along the southern coasts of Sicily and Malta; a strong eastward shelf surface flow along shore to Sicily, forming part of the Atlantic Ionian Stream, with a presence throughout the year and with significant seasonal modulation, and a westward winter intensified flow of LIW centered at a depth of around 280 m under the shelf break to the south of Malta. The seasonal variability in the thermohaline structure of the domain and the associated large-scale flow structures can be related to the current knowledge on the observed hydrography of the area. The level of mesoscale resolution achieved by the model allowed the spatial and temporal evolution of the changing flow patterns, triggered by internal dynamics, to be followed in detail. This modelling effort has initiated the treatment of the open boundary conditions problem in view of the future implementation of shelf-scale real-time ocean forecasting through the sequential nesting of a hierarchy of successively embedded model domains for the downscaling of the hydrodynamics from the coarse grid Ocean General Circulation Model of the whole Mediterranean Sea to finer grids in coastal areas. Key words. Oceanography: general (continental shelf processes; numerical modelling) Oceanography: physical (general circulation)
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Wang, Huiqing, Sen Zhao, Jing Zhao, and Zhipeng Feng. "A model for predicting drug-disease associations based on dense convolutional attention network." Mathematical Biosciences and Engineering 18, no. 6 (2021): 7419–39. http://dx.doi.org/10.3934/mbe.2021367.
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<abstract> <p>The development of new drugs is a time-consuming and labor-intensive process. Therefore, researchers use computational methods to explore other therapeutic effects of existing drugs, and drug-disease association prediction is an important branch of it. The existing drug-disease association prediction method ignored the prior knowledge contained in the drug-disease association data, which provided a strong basis for the research. Moreover, the previous methods only paid attention to the high-level features in the network when extracting features, and directly fused or connected them in series, resulting in the loss of information. Therefore, we propose a novel deep learning model for drug-disease association prediction, called DCNN. The model introduces the Gaussian interaction profile kernel similarity for drugs and diseases, and combines them with the structural similarity of drugs and the semantic similarity of diseases to construct the feature space jointly. Then dense convolutional neural network (DenseCNN) is used to capture the feature information of drugs and diseases, and introduces a convolutional block attention module (CBAM) to weight features from the channel and space levels to achieve adaptive optimization of features. The ten-fold cross-validation results of the model DCNN and the experimental results of the case study show that it is superior to the existing drug-disease association predictors and effectively predicts the drug-disease associations.</p> </abstract>
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Lockwood, M., B. S. Lanchester, H. U. Frey, K. Throp, S. K. Morley, S. E. Milan, and M. Lester. "IMF control of cusp proton emission intensity and dayside convection: implications for component and anti-parallel reconnection." Annales Geophysicae 21, no. 4 (April 30, 2003): 955–82. http://dx.doi.org/10.5194/angeo-21-955-2003.
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Abstract. We study a brightening of the Lyman-a emission in the cusp which occurred in response to a short-lived south-ward turning of the interplanetary magnetic field (IMF) during a period of strongly enhanced solar wind plasma concentration. The cusp proton emission is detected using the SI-12 channel of the FUV imager on the IMAGE spacecraft. Analysis of the IMF observations recorded by the ACE and Wind spacecraft reveals that the assumption of a constant propagation lag from the upstream spacecraft to the Earth is not adequate for these high time-resolution studies. The variations of the southward IMF component observed by ACE and Wind allow for the calculation of the ACE-to-Earth lag as a function of time. Application of the derived propagation delays reveals that the intensity of the cusp emission varied systematically with the IMF clock angle, the relationship being particularly striking when the intensity is normalised to allow for the variation in the upstream solar wind proton concentration. The latitude of the cusp migrated equatorward while the lagged IMF pointed southward, confirming the lag calculation and indicating ongoing magnetopause reconnection. Dayside convection, as monitored by the SuperDARN network of radars, responded rapidly to the IMF changes but lagged behind the cusp proton emission response: this is shown to be as predicted by the model of flow excitation by Cowley and Lockwood (1992). We use the numerical cusp ion precipitation model of Lockwood and Davis (1996), along with modelled Lyman-a emission efficiency and the SI-12 instrument response, to investigate the effect of the sheath field clock angle on the acceleration of ions on crossing the dayside magnetopause. This modelling reveals that the emission commences on each reconnected field line 2–2.5 min after it is opened and peaks 3–5 min after it is opened. We discuss how comparison of the Lyman-a intensities with oxygen emissions observed simultaneously by the SI-13 channel of the FUV instrument offers an opportunity to test whether or not the clock angle dependence is consistent with the "component" or the "anti-parallel" reconnection hypothesis.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; solar wind-magnetosphere interactions) – Space plasma physics (magnetic reconnection)
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Zajic, Alenka G., and Gordon L. Stuber. "Space-Time Correlated Mobile-to-Mobile Channels: Modelling and Simulation." IEEE Transactions on Vehicular Technology 57, no. 2 (March 2008): 715–26. http://dx.doi.org/10.1109/tvt.2007.905591.
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Bachmann, Aisha, Remco F. J. van der Burg, Jérémy Fensch, Gabriel Brammer, and Adam Muzzin. "Low surface brightness galaxies in z > 1 galaxy clusters: HST approaching the progenitors of local ultra diffuse galaxies." Astronomy & Astrophysics 646 (February 2021): L12. http://dx.doi.org/10.1051/0004-6361/202040097.
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Ultra diffuse galaxies (UDGs) are a type of large low surface brightness (LSB) galaxies with particularly large effective radii (reff > 1.5 kpc) that are now routinely studied in the Local (z < 0.1) Universe. While they are found to be abundant in clusters, groups, and in the field, their formation mechanisms remain elusive and comprise an active topic of debate. New insights may be found by studying their counterparts at higher redshifts (z > 1.0), even though cosmological surface brightness dimming makes them particularly difficult to detect and study in this channel. In this work, we use the deepest Hubble Space Telescope (HST) imaging stacks of z > 1 clusters, namely, SPT-CL J2106−5844 and MOO J1014+0038. These two clusters, at z = 1.13 and z = 1.23, respectively, were monitored as part of the HST See-Change programme. In making a comparison with the Hubble Extreme Deep Field as the reference field, we find statistical over-densities of large LSB galaxies in both clusters. Based on stellar-population modelling and assuming no size evolution, we find that the faintest sources we can detect are about as bright as expected for the progenitors of the brightest local UDGs. We find that the LSBs we detect in SPT-CL J2106−5844 and MOO J1014−5844 already have old stellar populations that place them on the red sequence. In correcting for incompleteness and based on an extrapolation of local scaling relations, we estimate that distant UDGs are relatively under-abundant, as compared to local UDGs, by a factor ∼3. A plausible explanation for the implied increase over time would be the significant growth of these galaxies over the last ∼8 Gyr, as also suggested by hydrodynamical simulations.
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Jitvanichphaibool, K., M. Saquib, and N. Al-Dhahir. "Space-Time Trellis-Coded Transmissions With Parallel Sequences Over Time-Varying Channels." IEEE Communications Letters 8, no. 9 (September 2004): 558–60. http://dx.doi.org/10.1109/lcomm.2004.833792.
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Song, L. y., and Alister Burr. "Successive interference cancelation for space-time block codes over time-selective channels." IEEE Communications Letters 10, no. 12 (December 2006): 837–39. http://dx.doi.org/10.1109/lcomm.2006.060993.
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Nezampour, Ali, and Robert Schober. "Asymptotic analysis of space-time codes in generalized fading channels." IEEE Communications Letters 13, no. 8 (August 2009): 561–63. http://dx.doi.org/10.1109/lcomm.2009.090935.
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Hongbin Li. "Differential space-time-frequency modulation over frequency-selective fading channels." IEEE Communications Letters 7, no. 8 (August 2003): 349–51. http://dx.doi.org/10.1109/lcomm.2003.814711.
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Díaz-Avalos, Carlos, David L. Peterson, Ernesto Alvarado, Sue A. Ferguson, and Julian E. Besag. "Spacetime modelling of lightning-caused ignitions in the Blue Mountains, Oregon." Canadian Journal of Forest Research 31, no. 9 (September 1, 2001): 1579–93. http://dx.doi.org/10.1139/x01-089.
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Generalized linear mixed models (GLMM) were used to study the effect of vegetation cover, elevation, slope, and precipitation on the probability of ignition in the Blue Mountains, Oregon, and to estimate the probability of ignition occurrence at different locations in space and in time. Data on starting location of lightning-caused ignitions in the Blue Mountains between April 1986 and September 1993 constituted the base for the analysis. The study area was divided into a pixeltime array. For each pixeltime location we associated a value of 1 if at least one ignition occurred and 0 otherwise. Covariate information for each pixel was obtained using a geographic information system. The GLMMs were fitted in a Bayesian framework. Higher ignition probabilities were associated with the following cover types: subalpine herbaceous, alpine tundra, lodgepole pine (Pinus contorta Dougl. ex Loud.), whitebark pine (Pinus albicaulis Engelm.), Engelmann spruce (Picea engelmannii Parry ex Engelm.), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), and grand fir (Abies grandis (Dougl.) Lindl.). Within each vegetation type, higher ignition probabilities occurred at lower elevations. Additionally, ignition probabilities are lower in the northern and southern extremes of the Blue Mountains. The GLMM procedure used here is suitable for analysing ignition occurrence in other forested regions where probabilities of ignition are highly variable because of a spatially complex biophysical environment.