Journal articles on the topic 'Channel model'
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1
Abdelsalam, Hisham M., and Ahmed O. El-Tagy. "A Simulation Model for Managing Marketing Multi-Channel Conflict." International Journal of System Dynamics Applications 1, no. 4 (October 2012): 59–76. http://dx.doi.org/10.4018/ijsda.2012100103.
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In today’s global competition, companies are obliged to go to market using multiple channels of strategy for various reasons. However, channel conflict is inevitable in multi-channel structures causing sharp decreases in the demand of one or more channels. A system dynamic model was developed to simulate the complex multiple channel structure and factors that affect the demand and channel conflict; aiming to simulate the situation of the supplier decision maker who takes fast decisions in one of the various variables that he controls to achieve maximum profits and minimum channel conflict. The model was validated using real data of a major consumer electronics supplier in Egypt that has traditional distributors and Hypermarkets as two different channels. Various policies of inventory allocations in each channel and different promotion rates were tested in order to achieve the objective of maximizing supplier profit and minimizing channel conflict.
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Shamohamadi, Behnam, and Ali Mehboudi. "Analyzing Parameters Influencing Scour Bed in Confluence Channels Using Flow3D Numerical Model." Civil Engineering Journal 2, no. 10 (October 30, 2016): 529–37. http://dx.doi.org/10.28991/cej-2016-00000055.
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Channels junction is a phenomenon which is used in most of irrigating and drainage networks and in hydraulic engineering in general. In two channels junction, main and secondary channels encounter with each other and move to the channel downstream. Scour holes and sedimentation zones are created in channels bed. 3D simulation of scour hole created in these channels is influenced by various factors. The ratio of main channel width to secondary channel width is one of the most important influencing factors. This parameter is the main focus of the present research. In the present study, a model calibrated with laboratory results has been simulated. The numerical model results have revealed that decreasing the ratio of main channel width to secondary channel width causes the secondary channel flow encounters to the front wall of the secondary channel. Also, it leads to creating scour near the front wall and the main hole is drawn towards the wall. Furthermore, in the present research, topographical changes of the bed with running time of the numerical model for the middle channel axis has been extracted and presented.
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Pi, Zhenyang, and Weiguo Fang. "The Implication of Channel Discrepancy in a Dual-Channel Supply Chain." Complexity 2021 (January 30, 2021): 1–13. http://dx.doi.org/10.1155/2021/8506454.
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This paper studies the implication of channel discrepancy between the retail and direct channels in a dual-channel supply chain consisting of one common retailer and two manufacturers in which the manufacturers may have different market powers. Each manufacturer provides a substitutable product and opens an online channel to customers directly. We develop an analytical model to derive the optimal pricing strategies by using game theory and the backward induction method, and we examine related properties under three market power structures while considering channel discrepancy, including the Nash equilibrium, the Manufacturers leader Stackelberg, and the M1 leader Stackelberg models (denoted as the N, MS, and M1S models, respectively). Numerical simulations are examined to reveal and verify the effect of channel discrepancy on optimal prices, demands, and profits. We find that a higher level of channel discrepancy induces higher prices, demands, and profits for each member in both channels, while this kind of stimulating impact for the leader manufacturer who obtains a higher level of channel discrepancy will be more significant than it is for the other members in the three models. In addition, the profit of the supply chain in the N model is always higher than it is in the MS model, while it may be higher or lower than it is in the M1S model depending on the level of channel discrepancy.
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Ahmed, Sadia, and Huseyin Arslan. "Analysis of Underwater Acoustic Communication Channels." Marine Technology Society Journal 47, no. 3 (May 1, 2013): 99–117. http://dx.doi.org/10.4031/mtsj.47.3.7.
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AbstractThe underwater acoustic communication (UAC) channel presents many difficulties such as high frequency, space, and time selectivity, frequency-dependent noise, and significant range and band limitation on transmission. Traditional UAC channel models that model such channels primarily include environmental models based on experimental data; models that are developed using mathematical equations such as wave equations, modal methods, and parabolic equations; and using statistical distributions. These methods/models are often limited in their coverage and accurate representations of every possible UAC channel environment. It is also physically impractical and cost ineffective to try to measure/estimate each channel to determine its model. In this paper, the authors will present the analysis of UAC channels according to the UAC channel environments classified and presented in a prior work by the authors, in which cognitive intelligence is used in the selection of the appropriate channel representations according to each sensed environment. To the best knowledge of the authors, this type of analysis and representation of UAC channels with respect to each UAC environment has not been addressed in the literature to date and therefore presents a significant contribution.
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Jarosch, A. H., and M. T. Gudmundsson. "A numerical model for meltwater channel evolution in glaciers." Cryosphere 6, no. 2 (April 16, 2012): 493–503. http://dx.doi.org/10.5194/tc-6-493-2012.
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Abstract. Meltwater channels form an integral part of the hydrological system of a glacier. Better understanding of how meltwater channels develop and evolve is required to fully comprehend supraglacial and englacial meltwater drainage. Incision of supraglacial stream channels and subsequent roof closure by ice deformation has been proposed in recent literature as a possible englacial conduit formation process. Field evidence for supraglacial stream incision has been found in Svalbard and Nepal. In Iceland, where volcanic activity provides meltwater with temperatures above 0 °C, rapid enlargement of supraglacial channels has been observed. Supraglacial channels provide meltwater through englacial passages to the subglacial hydrological systems of big ice sheets, which in turn affects ice sheet motion and their contribution to eustatic sea level change. By coupling, for the first time, a numerical ice dynamic model to a hydraulic model which includes heat transfer, we investigate the evolution of meltwater channels and their incision behaviour. We present results for different, constant meltwater fluxes, different channel slopes, different meltwater temperatures, different melt rate distributions in the channel as well as temporal variations in meltwater flux. The key parameters governing incision rate and depth are channel slope, meltwater temperature loss to the ice and meltwater flux. Channel width and geometry are controlled by melt rate distribution along the channel wall. Calculated Nusselt numbers suggest that turbulent mixing is the main heat transfer mechanism in the meltwater channels studied.
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Heider, Inaam Abbas. "Improvement of Fading Channel Modeling Performance for Wireless Channel." International Journal of Electrical and Computer Engineering (IJECE) 8, no. 3 (June 1, 2018): 1451. http://dx.doi.org/10.11591/ijece.v8i3.pp1451-1459.
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Fading channel modeling is generally defined as the variation of the attenuation of a signal with various variables. Time, geographical position, and radio frequency which is included. Fading is often modeled as a random process. Thus, a fading channel is a communication channel that experiences fading. In this paper, the proposed system presents a new design and simulate a wireless channel using Rayleigh channels. Rayleigh channels using two approaches (flat and frequency-selective fading channels) in order to calculate some path space loss efforts and analysis the performance of different wireless fading channel modeling. The results show that the bite error rate (BER) performance is dramatically improved in the value of signal to noise ratio (SNR) is equal to 45dB. Finally, the experimental results show that the proposed method enhances the performance of fading channel modeling by reducing the error of BER when the SNR is reduced also. Moreover, the more accurate model is Rayleigh model which can be considered for developing fading channel model.
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Soundararajan, Rajasoundaran, Prince Mary Stanislaus, Senthil Ganesh Ramasamy, Dharmesh Dhabliya, Vivek Deshpande, Sountharrajan Sehar, and Durga Prasad Bavirisetti. "Multi-Channel Assessment Policies for Energy-Efficient Data Transmission in Wireless Underground Sensor Networks." Energies 16, no. 5 (February 27, 2023): 2285. http://dx.doi.org/10.3390/en16052285.
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Wireless Underground Sensor Networks (WUGSNs) transmit data collected from underground objects such as water substances, oil substances, soil contents, and others. In addition, the underground sensor nodes transmit the data to the surface nodes regarding underground irregularities, earthquake, landslides, military border surveillance, and other issues. The channel difficulties of WUGSNs create uncertain communication barriers. Recent research works have proposed different types of channel assessment techniques and security approaches. Moreover, the existing techniques are inadequate to learn the real-time channel attributes in order to build reactive data transmission models. The proposed system implements Deep Learning-based Multi-Channel Learning and Protection Model (DMCAP) using the optimal set of channel attribute classification techniques. The proposed model uses Multi-Channel Ensemble Model, Ensemble Multi-Layer Perceptron (EMLP) Classifiers, Nonlinear Channel Regression models and Nonlinear Entropy Analysis Model, and Ensemble Nonlinear Support Vector Machine (ENLSVM) for evaluating the channel conditions. Additionally, Variable Generative Adversarial Network (VGAN) engine makes the intrusion detection routines under distributed environment. According to the proposed principles, WUGSN channels are classified based on the characteristics such as underground acoustic channels, underground to surface channels and surface to ground station channels. On the classified channel behaviors, EMLP and ENLSVM are operated to extract the Signal to Noise Interference Ratio (SNIR) and channel entropy distortions of multiple channels. Furthermore, the nonlinear regression model was trained for understanding and predicting the link (channel behaviors). The proposed DMCAP has extreme difficulty finding the differences of impacts due to channel issues and malicious attacks. In this regard, the VGAN-Intrusion Detection System (VGAN-IDS) model was configured in the sensor nodes to monitor the channel instabilities against malicious nodes. Thus, the proposed system deeply analyzes multi-channel attribute qualities to improve throughput in uncertain WUGSN. The testbed was created for classified channel parameters (acoustic and air) with uncertain network parameters; the uncertainties of testbed are considered as link failures, noise distortions, interference, node failures, and number of retransmissions. Consequently, the experimental results show that DMCAP attains 10% to 15% of better performance than existing systems through better throughput, minimum retransmission rate, minimum delay, and minimum energy consumption rate. The existing techniques such as Support Vector Machine (SVM) and Random Forest (RF)-based Classification (SMC), Optimal Energy-Efficient Transmission (OETN), and channel-aware multi-path routing principles using Reinforcement Learning model (CRLR) are identified as suitable for the proposed experiments.
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Ullah, Ghanim, Don-On Daniel Mak, and John E. Pearson. "A data-driven model of a modal gated ion channel: The inositol 1,4,5-trisphosphate receptor in insect Sf9 cells." Journal of General Physiology 140, no. 2 (July 30, 2012): 159–73. http://dx.doi.org/10.1085/jgp.201110753.
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The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) channel is crucial for the generation and modulation of intracellular Ca2+ signals in animal cells. To gain insight into the complicated ligand regulation of this ubiquitous channel, we constructed a simple quantitative continuous-time Markov-chain model from the data. Our model accounts for most experimentally observed gating behaviors of single native IP3R channels from insect Sf9 cells. Ligand (Ca2+ and IP3) dependencies of channel activity established six main ligand-bound channel complexes, where a complex consists of one or more states with the same ligand stoichiometry and open or closed conformation. Channel gating in three distinct modes added one complex and indicated that three complexes gate in multiple modes. This also restricted the connectivity between channel complexes. Finally, latencies of channel responses to abrupt ligand concentration changes defined a model with specific network topology between 9 closed and 3 open states. The model with 28 parameters can closely reproduce the equilibrium gating statistics for all three gating modes over a broad range of ligand concentrations. It also captures the major features of channel response latency distributions. The model can generate falsifiable predictions of IP3R channel gating behaviors and provide insights to both guide future experiment development and improve IP3R channel gating analysis. Maximum likelihood estimates of the model parameters and of the parameters in the De Young–Keizer model yield strong statistical evidence in favor of our model. Our method is simple and easily applicable to the dynamics of other ion channels and molecules.
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P. T. Nimbalkar, P. T. Nimbalkar, D. K. Mokashi D. K. Mokashi, and S. V. Kanitkar S. V. Kanitkar. "Channel Routing Model For Flood Zone Mapping." Indian Journal of Applied Research 1, no. 2 (October 1, 2011): 48–49. http://dx.doi.org/10.15373/2249555x/nov2011/15.
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Gutierrez del Arroyo, Jose A., Brett J. Borghetti, and Michael A. Temple. "Considerations for Radio Frequency Fingerprinting across Multiple Frequency Channels." Sensors 22, no. 6 (March 9, 2022): 2111. http://dx.doi.org/10.3390/s22062111.
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Radio Frequency Fingerprinting (RFF) is often proposed as an authentication mechanism for wireless device security, but application of existing techniques in multi-channel scenarios is limited because prior models were created and evaluated using bursts from a single frequency channel without considering the effects of multi-channel operation. Our research evaluated the multi-channel performance of four single-channel models with increasing complexity, to include a simple discriminant analysis model and three neural networks. Performance characterization using the multi-class Matthews Correlation Coefficient (MCC) revealed that using frequency channels other than those used to train the models can lead to a deterioration in performance from MCC > 0.9 (excellent) down to MCC < 0.05 (random guess), indicating that single-channel models may not maintain performance across all channels used by the transmitter in realistic operation. We proposed a training data selection technique to create multi-channel models which outperform single-channel models, improving the cross-channel average MCC from 0.657 to 0.957 and achieving frequency channel-agnostic performance. When evaluated in the presence of noise, multi-channel discriminant analysis models showed reduced performance, but multi-channel neural networks maintained or surpassed single-channel neural network model performance, indicating additional robustness of multi-channel neural networks in the presence of noise.
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Jarosch, A. H., and M. T. Gudmundsson. "A numerical model for meltwater channel evolution in glaciers." Cryosphere Discussions 5, no. 5 (October 11, 2011): 2605–28. http://dx.doi.org/10.5194/tcd-5-2605-2011.
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Abstract. Meltwater channels form an integral part of the hydrological system of a glacier. Better understanding of how meltwater channels develop and evolve is required to fully comprehend supraglacial and englacial meltwater drainage. Incision of supraglacial stream channels and subsequent roof closure by ice deformation has been proposed in recent literature as a possible englacial conduit formation process. Field evidence for supraglacial stream incision has been found in Svalbard and Nepal. In Iceland, where volcanic activity provides meltwater with temperatures above 0 °C, rapid enlargement of supraglacial channels has been observed. By coupling, for the first time, a numerical ice dynamic model to a hydraulic model which includes heat transfer, we investigate the evolution of meltwater channels and their incision behaviour. We present results for different, constant meltwater fluxes, different channel slopes, different meltwater temperatures as well as temporal variations in meltwater flux. The key parameters governing incision rate and depth are the channel slope and the meltwater temperature loss to the ice. Meltwater flux controls channel width and to a lesser degree incision behaviour. Calculated Nusselt numbers suggest that turbulent forced convection is the main heat transfer mechanism in the studied meltwater channels.
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Koshak, William J., Richard J. Solakiewicz, and Harold S. Peterson. "A Return Stroke NOx Production Model." Journal of the Atmospheric Sciences 72, no. 2 (February 1, 2015): 943–54. http://dx.doi.org/10.1175/jas-d-14-0121.1.
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Abstract A model is introduced for estimating the nitrogen oxides (NOx = NO + NO2) production from a lightning return stroke channel. A realistic modified transmission line model return stroke current is assumed to propagate vertically upward along a stepped leader channel of 0.1-cm radius. With additional assumptions about the initial radial expansion rate of the channel, the full nonlinear differential equation for the return stroke channel radius r(z, t) is solved numerically using Mathematica V9.0.1.0. Channel conductivity and channel air density are adjustable constants, and the model employs typical atmospheric profiles of temperature, pressure, and density. The channel pressure is modeled by a dynamic pressure expression. Channel temperature is extracted from the pressure by a minimization technique that involves a generalized gas law appropriate for high temperatures where dissociation and ionization are important. The altitude and time variations of the channel energy density are also obtained. Three model runs, each with different input parameters, are completed. Channel radii at sea level range from about 1.7 to 6.0 cm depending on the model inputs and are in good agreement with other investigators. The NOx production from each 1-m segment of the channel is computed using conservation of energy and equilibrium freeze-out-temperature chemistry. Because the NOx per meter of channel is computed as a function of altitude, extensions of the results to tortuous and branched channels are possible and lead to preliminary estimates of total return stroke NOx. These estimates are found to be smaller than the return stroke NOx values obtained from the NASA Lightning Nitrogen Oxides Model (LNOM).
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Larsson, Richard, Mathias Milz, Peter Rayer, Roger Saunders, William Bell, Anna Booton, Stefan A. Buehler, Patrick Eriksson, and Viju O. John. "Modeling the Zeeman effect in high-altitude SSMIS channels for numerical weather prediction profiles: comparing a fast model and a line-by-line model." Atmospheric Measurement Techniques 9, no. 2 (March 3, 2016): 841–57. http://dx.doi.org/10.5194/amt-9-841-2016.
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Abstract. We present a comparison of a reference and a fast radiative transfer model using numerical weather prediction profiles for the Zeeman-affected high-altitude Special Sensor Microwave Imager/Sounder channels 19–22. We find that the models agree well for channels 21 and 22 compared to the channels' system noise temperatures (1.9 and 1.3 K, respectively) and the expected profile errors at the affected altitudes (estimated to be around 5 K). For channel 22 there is a 0.5 K average difference between the models, with a standard deviation of 0.24 K for the full set of atmospheric profiles. Concerning the same channel, there is 1.2 K on average between the fast model and the sensor measurement, with 1.4 K standard deviation. For channel 21 there is a 0.9 K average difference between the models, with a standard deviation of 0.56 K. Regarding the same channel, there is 1.3 K on average between the fast model and the sensor measurement, with 2.4 K standard deviation. We consider the relatively small model differences as a validation of the fast Zeeman effect scheme for these channels. Both channels 19 and 20 have smaller average differences between the models (at below 0.2 K) and smaller standard deviations (at below 0.4 K) when both models use a two-dimensional magnetic field profile. However, when the reference model is switched to using a full three-dimensional magnetic field profile, the standard deviation to the fast model is increased to almost 2 K due to viewing geometry dependencies, causing up to ±7 K differences near the equator. The average differences between the two models remain small despite changing magnetic field configurations. We are unable to compare channels 19 and 20 to sensor measurements due to limited altitude range of the numerical weather prediction profiles. We recommended that numerical weather prediction software using the fast model takes the available fast Zeeman scheme into account for data assimilation of the affected sensor channels to better constrain the upper atmospheric temperatures.
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Larsson, R., M. Milz, P. Rayer, R. Saunders, W. Bell, A. Booton, S. A. Buehler, P. Eriksson, and V. John. "Modeling the Zeeman effect in high altitude SSMIS channels for numerical weather prediction profiles: comparing a fast model and a line-by-line model." Atmospheric Measurement Techniques Discussions 8, no. 10 (October 2, 2015): 10179–211. http://dx.doi.org/10.5194/amtd-8-10179-2015.
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Abstract. We present a comparison of a reference and a fast radiative transfer model using numerical weather prediction profiles for the Zeeman-affected high altitude Special Sensor Microwave Imager/Sounder channels 19–22. We find that the models agree well for channels 21 and 22 compared to the channels' system noise temperatures (1.9 and 1.3 K, respectively) and the expected profile errors at the affected altitudes (estimated to be around 5 K). For channel 22 there is a 0.5 K average difference between the models, with a standard deviation of 0.24 K for the full set of atmospheric profiles. Same channel, there is 1.2 K in average between the fast model and the sensor measurement, with 1.4 K standard deviation. For channel 21 there is a 0.9 K average difference between the models, with a standard deviation of 0.56 K. Same channel, there is 1.3 K in average between the fast model and the sensor measurement, with 2.4 K standard deviation. We consider the relatively small model differences as a validation of the fast Zeeman effect scheme for these channels. Both channels 19 and 20 have smaller average differences between the models (at below 0.2 K) and smaller standard deviations (at below 0.4 K) when both models use a two-dimensional magnetic field profile. However, when the reference model is switched to using a full three-dimensional magnetic field profile, the standard deviation to the fast model is increased to almost 2 K due to viewing geometry dependencies causing up to ± 7 K differences near the equator. The average differences between the two models remain small despite changing magnetic field configurations. We are unable to compare channels 19 and 20 to sensor measurements due to limited altitude range of the numerical weather prediction profiles. We recommended that numerical weather prediction software using the fast model takes the available fast Zeeman scheme into account for data assimilation of the affected sensor channels to better constrain the upper atmospheric temperatures.
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Geetanjali Sharma, Geetanjali Sharma. "Analysis of Multiple Queue Model in Cellular Networks with Sub Rating of Channels." journal of King Abdulaziz University Engineering Sciences 23, no. 1 (January 1, 2012): 85–128. http://dx.doi.org/10.4197/eng.23-1.5.
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In cellular Networks we generally consider a single queue for each cell, some authors proposed a model with a dedicated queue for each transceiver in the cell. We have extended the idea of dedicated queue for each transceiver in the cell with sub-rating channels to improve the Quality of Service (QOS) of the system. In this paper we have compared three models, in model-I we used guard channels to give priority to handoff attempts and a buffer for finite size is provided to give priority to handoff data attempts, further in model-II we have taken sub-rating channel scheme (SCS). In subrating scheme a full rate channel is temporarily divided into two half rate channels in the blocked cell; one half rate channel serve the originating call and another serves handoff call. We proposed a dedicated queue for each transceiver in the cell with sub-rating in model-III. The Fixed Channel Assignment Scheme is considered for all models. The probabilities of handoff failure, blocking probability of new calls, forced termination of handoff calls, probability of noncompleted calls for all models are calculated for varying assumed of values arrival rate of new data calls, arrival rate of new voice calls, buffer size of channels and service rates. We compared and analyzed the numerical results to validate the proposed models.
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Bicknell, Brendan A., and Geoffrey J. Goodhill. "Emergence of ion channel modal gating from independent subunit kinetics." Proceedings of the National Academy of Sciences 113, no. 36 (August 22, 2016): E5288—E5297. http://dx.doi.org/10.1073/pnas.1604090113.
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Many ion channels exhibit a slow stochastic switching between distinct modes of gating activity. This feature of channel behavior has pronounced implications for the dynamics of ionic currents and the signaling pathways that they regulate. A canonical example is the inositol 1,4,5-trisphosphate receptor (IP3R) channel, whose regulation of intracellular Ca2+ concentration is essential for numerous cellular processes. However, the underlying biophysical mechanisms that give rise to modal gating in this and most other channels remain unknown. Although ion channels are composed of protein subunits, previous mathematical models of modal gating are coarse grained at the level of whole-channel states, limiting further dialogue between theory and experiment. Here we propose an origin for modal gating, by modeling the kinetics of ligand binding and conformational change in the IP3R at the subunit level. We find good agreement with experimental data over a wide range of ligand concentrations, accounting for equilibrium channel properties, transient responses to changing ligand conditions, and modal gating statistics. We show how this can be understood within a simple analytical framework and confirm our results with stochastic simulations. The model assumes that channel subunits are independent, demonstrating that cooperative binding or concerted conformational changes are not required for modal gating. Moreover, the model embodies a generally applicable principle: If a timescale separation exists in the kinetics of individual subunits, then modal gating can arise as an emergent property of channel behavior.
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Kong, Yanfen, Caiyue Zhou, Chuanyong Zhang, Lin Sun, and Chongbo Zhou. "Multi-Color Channels Based Group Sparse Model for Image Restoration." Algorithms 15, no. 6 (May 24, 2022): 176. http://dx.doi.org/10.3390/a15060176.
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The group sparse representation (GSR) model combines local sparsity and nonlocal similarity in image processing, and achieves excellent results. However, the traditional GSR model and all subsequent improved GSR models convert the RGB space of the image to YCbCr space, and only extract the Y (luminance) channel of YCbCr space to change the color image to a gray image for processing. As a result, the image processing process cannot be loyal to each color channel, so the repair effect is not ideal. A new group sparse representation model based on multi-color channels is proposed in this paper. The model processes R, G and B color channels simultaneously when processing color images rather than processing a single color channel and then combining the results of different channels. The proposed multi-color-channels-based GSR model is compared with state-of-the-art methods. The experimental contrast results show that the proposed model is an effective method and can obtain good results in terms of objective quantitative metrics and subjective visual effects.
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Imoize, Agbotiname Lucky, Augustus Ehiremen Ibhaze, Aderemi A. Atayero, and K. V. N. Kavitha. "Standard Propagation Channel Models for MIMO Communication Systems." Wireless Communications and Mobile Computing 2021 (February 15, 2021): 1–36. http://dx.doi.org/10.1155/2021/8838792.
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The field of wireless communication networks has witnessed a dramatic change over the last decade due to sophisticated technologies deployed to satisfy various demands peculiar to different data-intensive wireless applications. Consequently, this has led to the aggressive use of the available propagation channels to fulfill the minimum quality of service (QoS) requirement. A major barometer used to gauge the performance of a wireless communication system is the spectral efficiency (SE) of its communication channels. A key technology used to improve SE substantially is the multiple input multiple output (MIMO) technique. This article presents a detailed survey of MIMO channel models in wireless communication systems. First, we present the general MIMO channel model and identified three major MIMO channel models, viz., the physical, analytical, and standardized models. The physical models describe the MIMO channel using physical parameters. The analytical models show the statistical features of the MIMO channel with respect to the measured data. The standardized models provide a unified framework for modern radio propagation architecture, advanced signal processing, and cutting-edge multiple access techniques. Additionally, we examined the strengths and limitations of the existing channel models and discussed model design, development, parameterization, implementation, and validation. Finally, we present the recent 3GPP-based 3D channel model, the transitioning from 2D to 3D channel modeling, discuss open issues, and highlight vital lessons learned for future research exploration in MIMO communication systems.
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Jiang, Ting, Maozhong Song, Xiaorong Zhu, and Xu Liu. "Channel Estimation for Broadband Millimeter Wave MIMO Systems Based on High-Order PARALIND Model." Wireless Communications and Mobile Computing 2021 (November 23, 2021): 1–12. http://dx.doi.org/10.1155/2021/6408442.
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Channel state information (CSI) is important to improve the performance of wireless transmission. However, the problems of high propagation path loss, multipath, and frequency selective fading make it difficult to obtain the CSI in broadband millimeter-wave (mmWave) system. Based on the inherent multidimensional structure of mmWave multipath channels and the correlation between channel dimensions, mmWave multiple input multiple output (MIMO) channels are modelled as high-order parallel profiles with linear dependence (PARALIND) model in this paper, and a new PARALIND-based channel estimation algorithm is proposed for broadband mmWave system. Due to the structural property of PARALIND model, the proposed algorithm firstly separates the multipath channels of different scatterers by PARALIND decomposition and then estimates the channel parameters from the factor matrices decomposed from the model based on their structures. Meanwhile, the performance of mmWave channel estimation is analysed theoretically. A necessary condition for channel parameter estimation is given based on the uniqueness principle of PARALIND model. Simulation results show that the proposed algorithm performs better than traditional compressive sensing-based channel estimation algorithms.
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Kang, Jun, Anthony K. Asare, Thomas Brashear-Alejandro, Elad Granot, and Ping Li. "Interorganizational drivers of channel performance: a meta-analytic structural model." Journal of Business & Industrial Marketing 33, no. 2 (March 5, 2018): 183–95. http://dx.doi.org/10.1108/jbim-09-2016-0218.
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Purpose This meta-analysis aims to explore the true effect sizes of major channel performance drivers from different theoretical perspectives and how these true effects are organized in a theoretically integrated structural analysis to predict performance. Design/methodology/approach First, it offers a quantitative summary on the drivers of channel performance through pairwise correlation analysis. Second, it tests an integrative framework of various performance drivers based on the relational view by using structural equation modeling. Last, it examines the potential moderation on the effects of performance drivers. Findings The synthesized effects of various channel performance drivers confirm the effectiveness of underlying theoretical perspectives of channel performance. The relational view is effective to identify immediate interorganizational drivers of channel performance. The contexts and methods of performance assessment have an impact on the appraisal of performance drivers. Research limitations/implications The performance drivers included in this meta-analysis are constrained to variables that exist in empirical channels literature and have sufficient primary data for analysis. Moderation tests are constrained by the report of research contexts and methods in original studies. Future research should broaden the theoretical perspectives on channel performance. Practical implications First, leveraging key routines and processes embedded in marketing channel relationships is critical to improve channel performance. Second, more targeted effort to manage channels in different markets may improve the efficiency of channel performance enhancement. Last, a comprehensive performance assessment process is necessary to avoid biased estimation of performance drivers. Originality/value This meta-analysis provides a systematic review of factors influencing marketing channel performance by synthesizing and correcting the effect sizes of performance drivers from different theoretical perspectives. It further develops and tests an integrative model of four immediate interorganizational drivers of channel performance.
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Shelley, Christopher, Xiaowei Niu, Yanyan Geng, and Karl L. Magleby. "Coupling and cooperativity in voltage activation of a limited-state BK channel gating in saturating Ca2+." Journal of General Physiology 135, no. 5 (April 26, 2010): 461–80. http://dx.doi.org/10.1085/jgp.200910331.
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Voltage-dependent gating mechanisms of large conductance Ca2+ and voltage-activated (BK) channels were investigated using two-dimensional maximum likelihood analysis of single-channel open and closed intervals. To obtain sufficient data at negative as well as positive voltages, single-channel currents were recorded at saturating Ca2+ from BK channels mutated to remove the RCK1 Ca2+ and Mg2+ sensors. The saturating Ca2+ acting on the Ca2+ bowl sensors of the resulting BKB channels increased channel activity while driving the gating into a reduced number of states, simplifying the model. Five highly constrained idealized gating mechanisms based on extensions of the Monod-Wyman-Changeux model for allosteric proteins were examined. A 10-state model without coupling between the voltage sensors and the opening/closing transitions partially described the voltage dependence of Po but not the single-channel kinetics. With allowed coupling, the model gave improved descriptions of Po and approximated the single-channel kinetics; each activated voltage sensor increased the opening rate approximately an additional 23-fold while having little effect on the closing rate. Allowing cooperativity among voltage sensors further improved the description of the data: each activated voltage sensor increased the activation rate of the remaining voltage sensors approximately fourfold, with little effect on the deactivation rate. The coupling factor was decreased in models with cooperativity from ∼23 to ∼18. Whether the apparent cooperativity among voltage sensors arises from imposing highly idealized models or from actual cooperativity will require additional studies to resolve. For both cooperative and noncooperative models, allowing transitions to five additional brief (flicker) closed states further improved the description of the data. These observations show that the voltage-dependent single-channel kinetics of BKB channels can be approximated by highly idealized allosteric models in which voltage sensor movement increases Po mainly through an increase in channel opening rates, with limited effects on closing rates.
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Weng, Jialai, Xiaoming Tu, Zhihua Lai, Sana Salous, and Jie Zhang. "Indoor Massive MIMO Channel Modelling Using Ray-Launching Simulation." International Journal of Antennas and Propagation 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/279380.
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Massive multi-input multioutput (MIMO) is a promising technique for the next generation of wireless communication networks. In this paper, we focus on using the ray-launching based channel simulation to model massive MIMO channels. We propose one deterministic model and one statistical model for indoor massive MIMO channels, both based on ray-launching simulation. We further propose a simplified version for each model to improve computational efficiency. We simulate the models in indoor wireless network deployment environments and compare the simulation results with measurements. Analysis and comparison show that these ray-launching based simulation models are efficient and accurate for massive MIMO channel modelling, especially with application to indoor network planning and optimisation.
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Prasad, G. Shyam Chandra, and K. Adi Narayana Reddy. "Sentiment Analysis Using Multi-Channel CNN-LSTM Model." Journal of Advanced Research in Dynamical and Control Systems 11, no. 12-SPECIAL ISSUE (December 31, 2019): 489–94. http://dx.doi.org/10.5373/jardcs/v11sp12/20193243.
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Gao, Yu, Xintong Han, Xun Wang, Weilin Huang, and Matthew Scott. "Channel Interaction Networks for Fine-Grained Image Categorization." Proceedings of the AAAI Conference on Artificial Intelligence 34, no. 07 (April 3, 2020): 10818–25. http://dx.doi.org/10.1609/aaai.v34i07.6712.
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Fine-grained image categorization is challenging due to the subtle inter-class differences. We posit that exploiting the rich relationships between channels can help capture such differences since different channels correspond to different semantics. In this paper, we propose a channel interaction network (CIN), which models the channel-wise interplay both within an image and across images. For a single image, a self-channel interaction (SCI) module is proposed to explore channel-wise correlation within the image. This allows the model to learn the complementary features from the correlated channels, yielding stronger fine-grained features. Furthermore, given an image pair, we introduce a contrastive channel interaction (CCI) module to model the cross-sample channel interaction with a metric learning framework, allowing the CIN to distinguish the subtle visual differences between images. Our model can be trained efficiently in an end-to-end fashion without the need of multi-stage training and testing. Finally, comprehensive experiments are conducted on three publicly available benchmarks, where the proposed method consistently outperforms the state-of-the-art approaches, such as DFL-CNN(Wang, Morariu, and Davis 2018) and NTS(Yang et al. 2018).
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Gerber, Richard E., David R. Sharpe, Hazen A. J. Russell, Steve Holysh, and Esmaeil Khazaei. "Conceptual hydrogeological model of the Yonge Street Aquifer, south-central Ontario: a glaciofluvial channel–fan setting." Canadian Journal of Earth Sciences 55, no. 7 (July 2018): 730–67. http://dx.doi.org/10.1139/cjes-2017-0172.
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The Yonge Street Aquifer (YSA) in the Greater Toronto Area of south-central Ontario is a prolific municipal supply aquifer. It has been considered to be channelized sand and gravel linked to a bedrock valley. Despite considerable work, the fundamental conceptual model for the YSA is not well developed and documented. Based on high-quality data, a revised conceptual model of the aquifer is presented. Seismic profiles define the geometry of the regional stratigraphy with four distinct units: bedrock, Lower sediments, Newmarket Till, and Oak Ridges Moraine (ORM) sediment. Seismic data reveal two generations of roughly north–south channels: older sub-Newmarket Till channels within Lower sediments (termed Thorncliffe channel) and ORM-related channels (termed ORM channel) that incise both Newmarket Till and Lower sediments. The YSA is interpreted to occur within a Thorncliffe channel, with possible vertical connection to younger ORM channels and lateral connection to inter-channel Lower sediments. Thorncliffe channel deposits consist of fining-upward transitions from coarse gravel, to sand, to rhythmically bedded mud interpreted to be deposited within a channel – esker – subaqueous fan complex. Upper Thorncliffe channel mud facies and overlying Newmarket Till provide a capping aquitard. The YSA conceptual model benefits from a strong understanding of facies changes in the Thorncliffe Formation. The deposits with highest permeability occur within up to 80 m thick gravel and sand sequences at the base of the Thorncliffe channel, with transmissivity ranging from 1500 to 4500 m2/day. Groundwater level response to municipal pumping confirms connection along the channel with muted hydraulic response laterally. Thorncliffe channels are interpreted to be up to 20 km long and approximately 2 km wide.
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Wu, Dapeng, and R. Negi. "Effective capacity channel model for frequency-selective fading channels." Wireless Networks 13, no. 3 (July 3, 2006): 299–310. http://dx.doi.org/10.1007/s11276-006-7526-x.
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Simon, Andrew. "A model of channel response in disturbed alluvial channels." Earth Surface Processes and Landforms 14, no. 1 (February 1989): 11–26. http://dx.doi.org/10.1002/esp.3290140103.
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Vikulov, A. "Effective Channel Planning of IEEE 802.11 Networks as a Plane Tessellation Problem. Part 1. Adjacent Channel Interference Model." Proceedings of Telecommunication Universities 8, no. 2 (June 30, 2022): 29–36. http://dx.doi.org/10.31854/1813-324x-2022-8-2-29-36.
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IEEE 802.11 wireless networks design process is impossible without a correct choice of a channel plan, i.e. a set of channels of a given type. This is especially important because channel planning of a distributed network heavily depends on the network designer’s and administrator’s decisions. Additionally, the central frequencies of the channels provided by the standard do not mean that the channels are non-overlapping. However, considering the coverage of a flat area as a plane tessellation by coverage areas of access points, for a particular regular structure geometry, it is necessary to choose the best channel planning solution among the possible ones. To do this, it is required to consider practically applicable channel planning cases, which use different numbers of channels, as a plane tessellation problem, also taking into account the overlapping of their spectral masks. This paper considers channel planning of IEEE 802.11 networks as a plane tessellation with regular structures and proposes a model that takes into account the effects of adjacent-channel interference, provides evaluation criteria, and thus is applicable to select the best channel configuration for the corresponding regular structure.
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Yue, Bicheng. "Research on Multichannel Supply Chain Pricing Under Different Dominance." Proceedings of Business and Economic Studies 4, no. 5 (October 28, 2021): 59–64. http://dx.doi.org/10.26689/pbes.v4i5.2638.
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In a multichannel supply chain comprising of dual-channel retailers with both physical and online channels as well as single-channel e-tailers with online channels, a multichannel demand model for e-commerce is constructed based on customer channel preferences, and a Stackerberg game model with price competition dominated by dual-channel retailers and single-channel e-tailers as well as a Bertrand game model with equal rights are established to analyze the impact of different channel rights structures on the price, demand, and profit of the two retailers. The results show that the single-channel e-tailer under the dual-channel retailer-dominated game has the highest profit, and the dual-channel retailer under the single-channel e-tailer-dominated game has the highest profit; thus, both retailers should accept the other’s dominant channel rights for profit maximization.
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Cao, Zhan Mao, and Jian Chao Tang. "Routing Methods and Scheduling Patterns in MIMO WMN Virtual Model." Applied Mechanics and Materials 519-520 (February 2014): 216–21. http://dx.doi.org/10.4028/www.scientific.net/amm.519-520.216.
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Multi-input multi-output wireless mesh networks (MIMO WMNs) act as backbone broadband networks for ubiquitous access. Topology model is a crucial factor in interference avoidance, simplifying channel allocation, and discussing optimal scheduling and routing. Cartesian product of graphs (CPG) is introduced for MIMO WMN as a virtual topology. By putting orthogonal channels into different channel layer meshes, some conclusions are explored on channel allocation, routing and scheduling. A path coherent realization is composed of combinatorial edges over multiple channels for all hops. Some important property propositions in CPG are also given, such as path hops with node address and path number counting. Practical mesh node addressing scheme and path number counting theorems are useful virtual topology properties.
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Aldawsari, Layla S., and Tom Altman. "Naming in Multichannel with Beeps in the Strong Model." Applied Sciences 10, no. 20 (October 14, 2020): 7164. http://dx.doi.org/10.3390/app10207164.
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In this paper, a system of anonymous processes is considered that communicates with beeps through multiple channels in a synchronous communication model. In beeping channels, processes are limited to hearing either a beep or a silence from the channel with no collision detection. A strong model is assumed in which a process can beep on any single channel and listen on any specific channel during a single round. The goal is to develop distributed naming algorithms for two models where the number of processes is either known or unknown. A Las Vegas algorithm was developed for naming anonymous processes when the number of processes is known. This algorithm has an optimal time complexity of O(nlogn) rounds and uses O(nlogn) random bits, where n is the number of processes for the largest group. For the model with an unknown number of processes, a Monte Carlo algorithm was developed, which has an optimal running time of O(nlogn) rounds and a probability of success that is at least 1−12Ω(logn). The algorithms solve the naming problem in new models where processes communicate through multiple channels.
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Liro, Maciej. "CONCEPTUAL MODEL FOR ASSESSING THE CHANNEL CHANGES UPSTREAM FROM DAM RESERVOIR." Quaestiones Geographicae 33, no. 1 (March 1, 2014): 61–74. http://dx.doi.org/10.2478/quageo-2014-0007.
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Abstract Most of geomorphological studies related to the impact of dam reservoirs are focused on its effect on the river channels downstream of dams. However, little is known about the evolution of river channels upstream of dams (in backwater areas). In this paper I propose a conceptual model of alluvial channel changes in the backwater. It assumes that three conditions of a channel that may occur in the pre-dam period. These are sediment supply deficit, balance and surplus compared to the river transport capacity. These conditions can be strengthened, stable or weakened. In the post-dam period these conditions is modified by the influence of the dam reservoir, which may affect the trajectory of channel changes, as well as its response and adjustment time in the backwater. The adjustment of channel parameters, in spite of the reservoir operation mode, also depends on the local river, reach characteristics and the magnitude and frequency of floods. Therefore, the use of an appropriate reference reach is inherent in this model. The model suggests that some adverse changes to backwater channels degraded by the regulation can be hampered. The model is based on Lane’s balance concept. It may be useful for explaining and predicting channel changes upstream of reservoirs and forming hypotheses in other studies.
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Heydari, Jafar, Amin Aslani, and Ali Sabbaghnia. "A collaborative scenario-based decision model for a disrupted dual-channel supply chain." Benchmarking: An International Journal 27, no. 3 (December 31, 2019): 933–57. http://dx.doi.org/10.1108/bij-06-2019-0281.
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Purpose Distribution systems usually utilize both traditional retailing channels in conjunction with e-channels. The purpose of this paper is to investigate a dual-channel supply chain, comprising a traditional retailing channel and an e-channel under disruption. By benchmarking against the centralized decision structure, the authors intend to propose a collaboration model to achieve channel coordination as well as more reliable decisions. Design/methodology/approach Four different channel disruption scenarios, with customers’ reaction toward disruptions, are examined, and then, optimal pricing decisions for both centralized and decentralized decision-making structures are extracted. Next, a collaboration mechanism based on the dominancy power of channel members is developed to entice all channel members to participate in channel coordination. By benchmarking the proposed collaboration model against both the decentralized/centralized structures a win–win solution is guaranteed for all channel members. In addition, the proposed model ensures more reliable decisions than the centralized structure, as it guarantees less fluctuated income levels. Findings This study shows, as the disruption probability grows, the channel profit decreases while the channel-retailing price increases. Furthermore, the exact alignment of the centralized decision-making approach and the proposed collaboration model is not achievable due to the problem infeasibility. Numerical experiments and sensitivity analyses benchmark the performance of the proposed collaboration mechanism against the centralized structure for the full alignment with centralized decision-making approach. Originality/value This study contributes to the channel conflict literature as jointly considers pricing decisions, disruptions and coordination. Further, consumers’ reaction toward disruption is analyzed through a transshipment agreement.
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Mohamed Hadi Habaebi, Ahmad Shahmi Mod Rofi, Md Rafiqul Islam, and Ahmed Basahel. "ANN-based LoRaWAN Channel Propagation Model." International Journal of Interactive Mobile Technologies (iJIM) 16, no. 11 (June 7, 2022): 91–106. http://dx.doi.org/10.3991/ijim.v16i11.30095.
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LoRaWAN wireless communication channels are often impacted by noise and interference over long-range causing loss of a received signal. One of the main drawbacks of using existing propagation models is less accurate as these models in designing the communication link are tailored to simplify the estimation. In this paper, an artificial intelligent real time path loss model is proposed. It is capable of processing complex variables over a short period of time. Providing it with enough data, the model is able to learn channel behavior and predict the path loss accurately. Results of the model are benchmarked against classical statistical curve fitting models where RMSE values are also compared and indicating that the artificial intelligent model has better accurate prediction.
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Teng, Michelle H., and Theodore Y. Wu. "Nonlinear water waves in channels of arbitrary shape." Journal of Fluid Mechanics 242 (September 1992): 211–33. http://dx.doi.org/10.1017/s0022112092002349.
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The generalized channel Boussinesq (gcB) two-equation model and the forced channel Korteweg–de Vries (cKdV) one-equation model previously derived by the authors are further analysed and discussed in the present study. The gcB model describes the propagation and generation of weakly nonlinear, weakly dispersive and weakly forced long water waves in channels of arbitrary shape that may vary both in space and time, and the cKdV model is applicable to unidirectional motions of such waves, which may be sustained under forcing at resonance of the system. These two models are long-wave approximations of a hierarchy set of section-mean conservation equations of mass, momentum and energy, which are exact for inviscid fluids. Results of these models are demonstrated with four specific channel shapes, namely variable rectangular, triangular, parabolic and semicircular sections, in which case solutions are obtained in closed form. In particular, for uniform channels of equal mean water depth, different cross-sectional shapes have a leading-order effect only on the variations of a k-factor of the coefficient of the term bearing the dispersive effects in the model equations. For this case, the uniform-channel analogy theorem enunciated here shows that long waves of equal (mean) height in different uniform channels of equal mean depth but distinct k-shape factors will propagate with equal velocity and with their effective wavelengths appearing k times of that in the rectangular channel, for which k = 1. It also shows that the further channel shape departs from the rectangular, the greater the value of k. Based on this observation, the solitary and cnoidal waves in a k-shaped channel are compared with experiments on wave profiles and wave velocities. Finally, some three-dimensional features of these solitary waves are presented for a triangular channel.
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Zhou, Chuiri. "Pricing Model for Dual Sales Channel with Promotion Effect Consideration." Mathematical Problems in Engineering 2016 (2016): 1–20. http://dx.doi.org/10.1155/2016/1804031.
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We focus on the pricing strategy of a dual sales channel member when his/her online retailer faces an upcoming overloaded express delivery service due to the sales peak of online shopping, especially referring to the occurring affairs in China. We characterize the pricing problem of the dual selling channel system as a two-period game. When the price discount is only provided by the online seller, we find that the prices of the traditional channel and the online channel in the two periods are higher while the overloaded degree of express delivery is lower and the overloaded delivery services can decrease the profits of both channels. When the price discounts are provided by both traditional and online sellers, we find that the derived Nash price equilibrium of both channels includes five possible combinations of prices. Both traditional and online sellers will choose their price strategies, respectively, according to their cost advantages which are affected by the overloaded degree of express delivery.
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Zhong, Changchun, Changhun Oh, and Liang Jiang. "Information transmission with continuous variable quantum erasure channels." Quantum 7 (March 6, 2023): 939. http://dx.doi.org/10.22331/q-2023-03-06-939.
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Quantum capacity, as the key figure of merit for a given quantum channel, upper bounds the channel's ability in transmitting quantum information. Identifying different types of channels, evaluating the corresponding quantum capacity, and finding the capacity-approaching coding scheme are the major tasks in quantum communication theory. Quantum channel in discrete variables has been discussed enormously based on various error models, while error model in the continuous variable channel has been less studied due to the infinite dimensional problem. In this paper, we investigate a general continuous variable quantum erasure channel. By defining an effective subspace of the continuous variable system, we find a continuous variable random coding model. We then derive the quantum capacity of the continuous variable erasure channel in the framework of decoupling theory. The discussion in this paper fills the gap of a quantum erasure channel in continuous variable setting and sheds light on the understanding of other types of continuous variable quantum channels.
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Dolasinski, Mary Jo, Chris Roberts, and Tianshu Zheng. "Measuring Hotel Channel Mix: A DEA-BSC Model." Journal of Hospitality & Tourism Research 43, no. 2 (September 3, 2018): 188–209. http://dx.doi.org/10.1177/1096348018789741.
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The hotel industry has experienced changes brought on by growth, customer expectations, and the proliferation in the use of e-commerce and online distribution channels. Future hotel success depends on how effectively hotel revenue managers are able to manage different booking channels to maximize hotel revenue. A Data Envelopment Analysis–Balanced Scorecard (DEA-BSC) model to measure efficiency of distribution channel mix using BSC results is presented. DEA-BSC was used because DEA-BSC incorporates multiple metrics simultaneously while traditional business models typically focus on one performance measure such as profit. Inputs for the model include the five distribution channels of C-Res/Voice, GDS, Brand.com , OTAs, and property/relationship sales. Output is the consolidated BSC average. The model was tested and results presented, demonstrating support for the usefulness of the model.
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Chen, Xin, Yong Fang, Weidong Xiang, and Liang Zhou. "Research on Spatial Channel Model for Vehicle-to-Vehicle Communication Channel in Roadside Scattering Environment." International Journal of Antennas and Propagation 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/3098198.
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In this paper, an extension of spatial channel model (SCM) for vehicle-to-vehicle (V2V) communication channel in roadside scattering environment is investigated for the first time theoretically and by simulations. Subsequently, to efficiently describe the roadside scattering environment and reflect the nonstationary properties of V2V channels, the proposed SCM V2V model divides the scattering objects into three categories of clusters according to the location of effective scatterers by introducing critical distance. We derive general expressions for the most important statistical properties of V2V channels, such as channel impulse response, power spectral density, angular power density, autocorrelation function, and Doppler spread of the proposed model. The impact of vehicle speed, traffic density, and angle of departure, angle of arrival, and other statistical performances on the V2V channel model is thoroughly discussed. Numerical simulation results are presented to validate the accuracy and effectiveness of the proposed model.
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Werner, Matthias E., Andrea L. Meredith, Richard W. Aldrich, and Mark T. Nelson. "Hypercontractility and impaired sildenafil relaxations in the BKCa channel deletion model of erectile dysfunction." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 295, no. 1 (July 2008): R181—R188. http://dx.doi.org/10.1152/ajpregu.00173.2008.
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Erectile dysfunction (ED) can be elicited by a variety of pathogenic factors, particularly impaired formation of and responsiveness to nitric oxide (NO) and the downstream effectors soluble guanylate cyclase (sGC) and cGMP-dependent protein kinase I (PKGI). One important target of PKGI in smooth muscle is the large-conductance, Ca2+-activated potassium (BKCa) channel. In our previous report ( 42 ), we demonstrated that deletion of the BKCa channel in mice induced force oscillations and led to reduced nerve-evoked relaxations and ED. In the current study, we used this ED model to explore the role of the BKCa channel in the NO/sGC/PKGI pathway. Electrical field stimulation (EFS)-induced contractions of corpus cavernosum smooth muscle strips were significantly enhanced in the absence of BKCa channel function. In strips precontracted with phenylephrine, EFS-induced relaxations were converted to contractions by inhibition of sGC, and this was further enhanced by loss of BK channel function. Sildenafil-induced relaxations were decreased to a similar extent by inhibition of sGC or BKCa channels. At concentrations >1 μM, sildenafil caused relaxations independent of inhibition of sGC or BKCa channels. Sildenafil did not affect the enhanced force oscillations that were induced by the loss of BKCa channel function. Yet, these oscillations could be completely eliminated by blocking L-type voltage-dependent Ca2+ channels (VDCCs). These results suggest that therapeutically relevant concentrations of sildenafil act through cGMP and BKCa channels, and loss of BKCa channel function leads to hypercontractility, which depends on VDCCs and cannot be modified by the cGMP pathway.
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Lozanović Šajić, Jasmina, Sonja Langthaler, and Christian Baumgartner. "Creating a Novel Mathematical Model of the Kv10.1 Ion Channel and Controlling Channel Activity with Nanoelectromechanical Systems." Applied Sciences 12, no. 8 (April 11, 2022): 3836. http://dx.doi.org/10.3390/app12083836.
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The use of nanoelectromechanical systems or nanorobots offers a new concept for sensing and controlling subcellular structures, such as ion channels. We present here a novel method for mathematical modeling of ion channels based on control system theory and system identification. We investigated the use of nanoelectromechanical devices to control the activity of ion channels, particularly the activity of the voltage-gated ion channel Kv10.1, an important channel in cancer development and progression. A mathematical model of the dynamic behavior of the selected ion channel Kv10.1 in the Laplace (s) domain was developed, which is given in the representation of a transfer function. In addition, we addressed the possibilities of controlling ion channel activity by nanoelectromechanical devices and nanorobots and finally presented a control algorithm for the Kv10.1 as a control object. A use case demonstrates the potential of a Kv10.1 controlled nanorobot for cancer treatment at a single-cell level.
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De Schutter, E., and J. M. Bower. "An active membrane model of the cerebellar Purkinje cell. I. Simulation of current clamps in slice." Journal of Neurophysiology 71, no. 1 (January 1, 1994): 375–400. http://dx.doi.org/10.1152/jn.1994.71.1.375.
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1. A detailed compartmental model of a cerebellar Purkinje cell with active dendritic membrane was constructed. The model was based on anatomic reconstructions of single Purkinje cells and included 10 different types of voltage-dependent channels described by Hodgkin-Huxley equations, derived from Purkinje cell-specific voltage-clamp data where available. These channels included a fast and persistent Na+ channel, three voltage-dependent K+ channels, T-type and P-type Ca2+ channels, and two types of Ca(2+)-activated K+ channels. 2. The ionic channels were distributed differentially over three zones of the model, with Na+ channels in the soma, fast K+ channels in the soma and main dendrite, and Ca2+ channels and Ca(2+)-activated K+ channels in the entire dendrite. Channel densities in the model were varied until it could reproduce Purkinje cell responses to current injections in the soma or dendrite, as observed in slice recordings. 3. As in real Purkinje cells, the model generated two types of spiking behavior. In response to small current injections the model fired exclusively fast somatic spikes. These somatic spikes were caused by Na+ channels and repolarized by the delayed rectifier. When higher-amplitude current injections were given, sodium spiking increased in frequency until the model generated large dendritic Ca2+ spikes. Analysis of membrane currents underlying this behavior showed that these Ca2+ spikes were caused by the P-type Ca2+ channel and repolarized by the BK-type Ca(2+)-activated K+ channel. As in pharmacological blocking experiments, removal of Na+ channels abolished the fast spikes and removal of Ca2+ channels removed Ca2+ spiking. 4. In addition to spiking behavior, the model also produced slow plateau potentials in both the dendrite and soma. These longer-duration potentials occurred in response to both short and prolonged current steps. Analysis of the model demonstrated that the plateau potentials in the soma were caused by the window current component of the fast Na+ current, which was much larger than the current through the persistent Na+ channels. Plateau potentials in the dendrite were carried by the same P-type Ca2+ channel that was also responsible for Ca2+ spike generation. The P channel could participate in both model functions because of the low-threshold K2-type Ca(2+)-activated K+ channel, which dynamically changed the threshold for dendritic spike generation through a negative feedback loop with the activation kinetics of the P-type Ca2+ channel. 5. These model responses were robust to changes in the densities of all of the ionic channels.(ABSTRACT TRUNCATED AT 400 WORDS)
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Li, Dongfei, Ning Dai, Hongtao Wang, and Fujun Zhang. "Mathematical Modeling Study of Pressure Loss in the Flow Channels of Additive Manufacturing Aviation Hydraulic Valves." Energies 16, no. 4 (February 10, 2023): 1788. http://dx.doi.org/10.3390/en16041788.
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The application of additive manufacturing in the field of aviation hydraulics greatly improves the design freedom of hydraulic valve internal flow channels. Pressure loss in hydraulic valve internal flow channels is a primary factor that designers need to consider, and the rapid prediction of pressure loss is very helpful for flow channel design. At present, most studies only focus on how much the pressure loss in an additive manufacturing (AM) hydraulic channel is reduced compared with an original hydraulic channel, and a mathematical model of pressure loss in an AM curved channel is still lacking. In this paper, the pressure loss in a curved flow channel was firstly studied, and the main parameters affecting the pressure loss were determined using the dimensionless analysis method. Using computational fluid dynamics simulation, the relationships between the flow channel diameter, the flow channel length, the flow channel curvature radius, the fluid velocity and pressure loss were studied. According to the multiple regression analysis method, the mathematical model of pressure loss in aviation hydraulic channels was developed, and the model was solved based on the orthogonal experimental results. The pressure loss in the flow channel samples fabricated using selective laser melting was tested, and the results showed that the average error between the test results and the mathematical model calculation results was 7.72%. This model can be used to quickly predict the pressure loss in curved flow channels in the aviation hydraulic field.
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Miller, C. "A Chloride Channel Model?" Science 274, no. 5288 (November 1, 1996): 738–0. http://dx.doi.org/10.1126/science.274.5288.738.
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MARINOV, B. "Ion channel redox model." Journal of Molecular and Cellular Cardiology 23 (February 1991): 53–60. http://dx.doi.org/10.1016/0022-2828(91)90024-g.
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SATO, CHIKARA, and GEN MATSUMOTO. "A Sodium Channel Model." Annals of the New York Academy of Sciences 707, no. 1 Molecular Bas (December 1993): 338–41. http://dx.doi.org/10.1111/j.1749-6632.1993.tb38064.x.
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Kabir, M. H., and K. S. Kwak. "Molecular nanonetwork channel model." Electronics Letters 49, no. 20 (September 2013): 1285–87. http://dx.doi.org/10.1049/el.2013.1948.
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Chen-Izu, Ye, Alonso P. Moreno, and Robert A. Spangler. "Opposing gates model for voltage gating of gap junction channels." American Journal of Physiology-Cell Physiology 281, no. 5 (November 1, 2001): C1604—C1613. http://dx.doi.org/10.1152/ajpcell.2001.281.5.c1604.
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Gap junctions are intercellular channels that link the cytoplasm of neighboring cells. Because a gap junction channel is composed of two connexons docking head-to-head with each other, the channel voltage-gating profile is symmetrical for homotypic channels made of two identical connexons (hemichannels) and asymmetric for the heterotypic channels made of two different connexons (i.e., different connexin composition). In this study we have developed a gating model that allows quantitative characterization of the voltage gating of homotypic and heterotypic channels. This model differs from the present model in use by integrating, rather than separating, the contributions of the voltage gates of the two member connexons. The gating profile can now be fitted over the entire voltage range, eliminating the previous need for data splicing and fusion of two hemichannel descriptions, which is problematic when dealing with heterotypic channels. This model also provides a practical formula to render quantitative several previously qualitative concepts, including a similarity principle for matching a voltage gate to its host connexon, assignment of gating polarity to a connexon, and the effect of docking interactions between two member connexons in an intact gap junction channel.
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Kohli, Amit Kumar, Amrita Rai, and Meher Krishna Patel. "Variable Forgetting Factor LS Algorithm for Polynomial Channel Model." ISRN Signal Processing 2011 (December 30, 2011): 1–4. http://dx.doi.org/10.5402/2011/915259.
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Variable forgetting factor (VFF) least squares (LS) algorithm for polynomial channel paradigm is presented for improved tracking performance under nonstationary environment. The main focus is on updating VFF when each time-varying fading channel is considered to be a first-order Markov process. In addition to efficient tracking under frequency-selective fading channels, the incorporation of proposed numeric variable forgetting factor (NVFF) in LS algorithm reduces the computational complexity.
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Gao, Tianhan, and Wei Lu. "Electrolyte Channel Design By Physical Model and Machine Learning." ECS Meeting Abstracts MA2022-02, no. 5 (October 9, 2022): 562. http://dx.doi.org/10.1149/ma2022-025562mtgabs.
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Thick electrode is highly effective to increase the specific energy of a battery cell, but the associated increase in transport distance causes a major barrier for fast charging. We introduce a bio-inspired electrolyte channel design into thick electrodes to improve the cell performance, especially under fast charging conditions. The effects of channel length, width, tapering degree and active material width on the electrochemical performance and mechanical integrity are investigated. Machine learning by deep neural network (DNN) is developed to relate the geometrical parameters of channels to the overall cell performance. Integrating machine learning with the Markov chain Monte Carlo gradient descent optimization, we demonstrate that the complicated multivariable channel geometry optimization problem can be efficiently solved. The results show that within a certain range of geometrical parameters, the specific energy, specific capacity and specific power can be greatly improved. At the same time, the maximum first principal stress which is in the cathode region next to the separator can be significantly reduced, giving better mechanical integrity. Comparing to conventional designed cells without electrolyte channels, we show a 79% increase in specific energy using channel design optimization. This study provides a design strategy and optimization method to achieve significantly improved battery performance