Multiple-channel System Research Articles

Tunneling time in coupled-channel systems

In present work, we present a couple-channel formalism for the description of tunneling time of a quantum particle through a composite compound with multiple energy levels or a complex structure that can be reduced to a quasi-one-dimensional multiple-channel system. Published by the American Physical Society 2024

Meta‐heuristic optimization techniques for scheduling in multiple‐input multiple‐output multiple‐access channel system

SummaryIn a highly dense multiple‐input multiple‐output (MIMO) communication system, proper resource allocation is exceedingly challenging. The simultaneous selection of antennas at the base‐station (BS) and scheduling of users in an uplink multiple access channel (MAC) system add up to the signal processing load in the MIMO wireless system. The method chosen for combining the user scheduling and antenna selection must have a very low computational complexity. However, the exhaustive search algorithm (ESA), which achieves the best sum‐rate capacity in a MIMO‐MAC system, has a very high level of complexity. In this paper, we use a metaheuristic‐based optimization algorithms to optimize the sum‐rate capacity in a MAC system with significantly less computational complexity. First, we use the beluga whale optimization (BWO) metaheuristic method to solve the optimization problem. The BWO is a swarm‐based algorithm that draws inspiration from beluga whale behavior. An improved BWO (iBWO) is also presented and is utilized for the same optimization challenge. The proposed iBWO scheme improves the search capability of the algorithm and thereby ensures better exploration and exploitation capabilities of the beluga whales. We compare the performance of these algorithms with a standard differential evolution (DE) algorithm. The simulation results demonstrate that the proposed iBWO is a very competitive meta‐heuristic algorithm for solving optimization problems. The proposed iBWO algorithm achieves near optimal throughput in a MIMO‐MAC system. Also, the computational complexity related to the suggested optimization technique in a MIMO‐MAC system is found to be very less compared with the complexity related to ESA.

A Method for Estimating the Hydrodynamic Values of Anastomosing Rivers: The Expression of Channel Morphological Parameters

An anastomosing river is a stable multiple-channel system separated by inter-channel wetlands, and there are serious difficulties in observing the hydrodynamics of such river patterns in situ. Therefore, there are few reports on the hydrodynamic data of such rivers, for example, the upper Columbia and Pearl Rivers. In order to obtain the hydrodynamic parameter values at flow cross-sections of anastomosing rivers, without having to observe hydraulic radius, this study proposes a method called the Expression of Channel Morphological Parameters (ECMP) for hydrodynamic estimation. The calculation formula of the ECMP method is based on the shape factor (width–depth ratio), scale factor (mean depth), and gradient factor of the channel cross-sections of anastomosing rivers below a given water level as independent variables. This method can be used to calculate the mean velocity, discharge, specific stream power, and gross stream power of the flow cross-section at different water levels, only requiring the measurements of channel morphological parameters such as the mean depth, width–depth ratio, and gradient at the channel cross-section below the corresponding water level. The applicability of the ECMP method was verified using measured hydrological data. The results showed that the ECMP method is a practical estimation method with higher accuracy that is convenient for calculating the hydrodynamic parameters of anastomosing rivers. It can also be used to reconstruct ancient anastomosing rivers using the channel morphological parameters revealed from the fill sediments in ancient channels.

Multi-sensor Optimal Linear Estimation With Unobservable Measurement Losses

For a multiple-channel system with sensor measurement losses, if the loss of sensor measurements can be observed by the estimator, the system is called a system with observable measurement losses; otherwise, it is called a system with unobservable measurement losses (a UML system). We first obtain the optimal linear estimator (OLE) for multiple-channel UML systems and then establish a necessary and sufficient condition for the stability and convergence of the OLE. We give a tight bound of the estimation performance loss caused by the unobservability of measurement losses. We show that the estimation performance is a monotonically increasing function of the measurement-loss rate and then analytically characterize the relation between the OLE-performance-loss rate and the measurement-loss rate. Finally, numerical examples are provided to show the effectiveness of the proposed OLE, when the measurement-loss status, that is, the private information of measurement losses, cannot be observed.

Three-Dimensional Acoustic Levitation of Particles in the Field of Phased Arrays of Ultrasonic Vibrators

A possibility of sustaining a stable 3D-levitation of a collection of particles in an acoustic field under the conditions of all-around irradiation by monochromatic ultrasonic waves in air is investigated. The levitation of particles is ensured by placing them into a field of standing waves of a particular configuration. The particles are controlled in the field in the horizontal plane by varying the phase relations of the radiating arrays. It is shown theoretically and experimentally that it is possible to apply a monochromatic field to sustain a stable levitation of particles in a volume. A multiple-channel system of control over the phased arrays of ultrasonic vibrators is shown, which is based on a 1-bit DA-converter for application in a facility of ultrasonic levitation in air.

The alteration of lateral circulation under the influence of human activities in a multiple channel system, Changjiang Estuary

Extensive coastal engineering activities including channel dredging and constructions of large infrastructure have greatly altered hydrodynamics in the Changjiang Estuary. While the changes in longitudinal circulation have been well-documented, limited studies have focused on the alteration in lateral circulation and its impact on estuarine circulation in the Changjiang Estuary. Lateral circulation in an estuary plays an important role in modulating estuarine circulation, sediment transport, and morphological change. Different from many of previous numerical studies, we utilize an unstructured-grid numerical model configured in a way to allow inundation over dikes and tidal flats. Numerical model experiments show significant changes in lateral circulation and stratification along the North Passage in response to the altered geometry and bathymetry due to the channel deepening and the dike construction. Both the channel deepening and the dike construction led to an enhanced stratification. Further analysis suggests that the along-channel, the lateral, and the vertical (including up- and downwelling and vertical mixing) effects are all important in modulating the intra-tidal stratification-destratification process. The channel deepening enhances both the lateral and the vertical effects around the high-water slack. The construction of dikes that completely blocks the lateral water exchange between the North Passage and surrounding tidal flats, changes the system from a multiple-channel system into a single-channel system. With dike construction, the estuarine circulation tends to have a horizontally sheared pattern with weaker friction and a stronger stratification.

Antimicrobial Susceptibility Test for the Determination of Resistant and Susceptible S. aureus and Enterococcus spp. Using a Multi-Channel Surface Plasmon Resonance Device.

The objective of this study was to investigate the development of a surface plasmon resonance (SPR) sensor platform equipped with multiple channels for the simultaneous determination of methicillin-resistant S. aureus (MRSA), methicillin-susceptible S. aureus (MSSA) and vancomycin-resistant Enterococcus (VRE), and vancomycin-susceptible Enterococcus (VSE). Drug resistance of S. aureus strains against cefoxitin and Enterococcus strains against vancomycin were investigated both using the minimum inhibitory concentration method (MIC) assay and the SPR system equipped with single and multiple channels. The MIC values of MRSA and MSSA ranged from 32 µg/mL to >128 µg/mL and from 1 µg/mL to 4 µg/mL, respectively. The MIC values of VRE and VSE were between 64 to >128 µg/mL and 2–4 µg/mL, respectively. With the multiple-channel system, the angle shifts of MRSA, MSSA, VRE and VSE were found to be −0.030° and −0.260°, −0.010° and −0.090° respectively. The antibiotic-resistant and susceptible strains were distinguished within 3 h for S. aureus strains and within 6 h for Enterococcus strains.

Multiple channel complexity: Conceptualization and measurement

Nowadays, to better serve their customers, many companies are using multiple channels with different levels of complexity. Although the literature agrees that it is a challenge to design and manage multiple channels for improved performance in today's circumstances, there are no empirically determined guidelines offered to achieve that goal. One contributing factor to this is the lack of a clear conceptualization of multiple channel complexity in the literature. With no such construct and measure, researchers are unable to conduct studies to understand variability in the complexity of multiple channels in practice and hence to draw normative conclusions for managers. In this work, drawing upon the vast organizational complexity literature, we provide a conceptual definition and a measure of multiple channel complexity. Our construct describes the structure of a multiple channel system with respect to three complexity dimensions: channel number; channel levels, and channel member variety. The data from 305 sales/marketing managers in the electronics industry support the validity of the construct as we observe that in highly uncertain environments having highly complex multiple channels in place improves company performance.

Experimental studies in a single-phase parallel channel natural circulation system: preliminary results

Abstract Natural circulation systems find extensive applications in industrial engineering systems. One of the applications is in nuclear reactor where the decay heat is removed by natural circulation of the fluid under off-normal conditions. The upcoming reactor designs make use of natural circulation in order to remove the heat from core under normal operating conditions also. These reactors employ multiple vertical fuel channels with provision of on-power refueling/defueling. Natural circulation systems are relatively simple, safe and reliable when compared to forced circulation systems. However, natural circulation systems are prone to encounter flow instabilities which are highly undesirable for various reasons. Presence of parallel channels under natural circulation makes the system more complicated. To examine the behavior of parallel channel system, studies were carried out for single-phase natural circulation flow in a multiple vertical channel system. The objective of the present work is to study the flow behavior of the parallel heated channel system under natural circulation for different operating conditions. Steady state and transient studies have been carried out in a parallel channel natural circulation system with three heated channels. The paper brings out the details of the system considered, different cases analyzed and preliminary results of studies carried out on a single-phase parallel channel system.

Stochastic Modeling and Simulation of Ion Transport through Channels

Ion channels are of major interest, and form an area of intensive research in the fields of biophysics and medicine since they control many vital physiological functions. The aim of this work is on the one hand to propose a fully stochastic and discrete model describing the main characteristics of a multiple channel system. The movement of the ions is coupled, as usual, with a Poisson equation for the electrical field; we have considered, in addition, the influence of exclusion forces. On the other hand, we have discussed the nondimensionalization of the stochastic system by using real physical parameters, all supported by numerical simulations. The specific features of both cases of micro- and nanochannels have been taken into consideration with particular attention to the latter case in order to show that it is necessary to consider a discrete and stochastic model for ions movement inside the channels.

Cross-layer distributed power control: a repeated game formulation to improve the sum energy efficiency

The main objective of this work is to improve the energy-efficiency (EE) of a multiple access channel (MAC) system, through power control, in a distributed manner. In contrast with many existing works on energy-efficient power control, which ignore the possible presence of a queue at the transmitter, we consider a new generalized cross-layer EE metric. This approach is relevant when the transmitters have a non-zero energy cost even when the radiated power is zero and takes into account the presence of a finite packet buffer and packet arrival at the transmitter. As the Nash equilibrium (NE) is an energy-inefficient solution, the present work aims at overcoming this deficit by improving the global energy-efficiency. Indeed, as the considered system has multiple agencies each with their own interest, the performance metric reflecting the individual interest of each decision maker is the global energy-efficiency defined then as the sum over individual energy-efficiencies. Repeated games (RG) are investigated through the study of two dynamic games (finite RG and discounted RG), whose equilibrium is defined when introducing a new operating point (OP), Pareto-dominating the NE and relying only on individual channel state information (CSI). Accordingly, closed-form expressions of the minimum number of stages of the game for finite RG (FRG) and the maximum discount factor of the discounted RG (DRG) were established. The cross-layer model in the RG formulation leads to achieving a shorter minimum number of stages in the FRG even for higher number of users. In addition, the social welfare (sum of utilities) in the DRG decreases slightly with the cross-layer model when the number of users increases while it is reduced considerably with the Goodman model. Finally, we show that in real systems with random packet arrivals, the cross-layer power control algorithm outperforms the Goodman algorithm.

IMPLEMENTATION OF MULTIPLE-CHANNEL CAPACITIVE ECG MEASUREMENT BASED ON CONDUCTIVE FABRIC

Capacitive electrocardiogram (cECG) measurement is an attractive approach for long-term health monitoring. However, there is little literature available for the implementation of multiple-channel cECG system in standard limb leads. The circuit diagram for such a system is also rarely available in literature. This paper presents a multiple-channel limb-lead cECG system that utilized conductive fabrics as the capacitive sensors. The design criteria and the corresponding circuit diagram are described in detail. The proposed system also incorporates the capacitive driven-body (CDB) circuit to reduce the common-mode power-line interference (PLI). The presented system is verified to be stable by theoretic analysis and long-term experiments. The signals acquired by the presented system are competitive with those by commercially available electrocardiogram (ECG) machines. The feasible size and distance to the subject for the sensor made by conductive fabric have also been evaluated by a series of tests. From the test results, the sensor is suggested to be of greater than 60 cm2 in area and not more than 3 mm in distance for cECG measurement.

Indoor Localization of Passive UHF RFID Tags Based on Phase-of-Arrival Evaluation

This paper introduces a two-dimensional localization system for passive UHF RFID transponders based on phase-of-arrival evaluation of the backscattered tag signal. A multiple-channel system, where alternately one path is configured as a transmitter and the remaining paths work as receivers, is used to permit the position estimation. To improve localization accuracy and reduce disturbances caused by multipath propagation, a frequency-stepped continuous-waveform approach is employed. To achieve proof of concept, a local position measurement system demonstrator comprising an RFID reader, passive EPC Gen 2 RFID tags, several transceivers, baseband hardware, and signal processing was used for measurements. The results show excellent localization accuracy, even in an indoor environment.

Optimal Spectrum Access for Users in Multi-Channel Cognitive Radio Networks

Cognitive Radio, a software defined rad io, is an emerging technology which uses opportunistic spectrum access (OSA) for the efficient utilizat ion of the spectrum. Its main aim is to utilize the unused portions of the spectrum by allo wing unlicensed users (secondary users) to transmit data in absence of primary users. In this paper the assignment of mu ltip le primary and secondary users in a mult iple channel system is addressed with the sole aim of optimizing the total throughput. We have considered an optimal spectrum access (OSA) algorith m for the allot ment of both the primary and secondary users in a mult iple channel system and compared the results with the well-known meta-heuristic techniques such as Simulated Annealing (SA) and Tabu Search (TS). The results reveal that OSA algorithm is mo re efficient as compared to SA and TS as far as throughput optimization is considered.

The Study and Achieving of High-precision Data-acquisition Based on ΔΣADC

ΔΣ ADC is used more and more widely, and it is favored for the important reason of high precision. In this paper, working principle and characteristics of ΔΣ modulator and digital filter have been analyzed, and then oversampling, noise shaping and digital filtering characteristics are discussed. Finally, a practical application is illustrated and its basic structure of acquisition circuit is given, the design ideas of single-ended-to-differential driver circuit and front RC filter circuit is highlighted, and the choosing of connection method of multiple channel system is argued. DOI: http://dx.doi.org/10.11591/telkomnika.v11i8.3048

Weighted sum-rate maximization for multi-user SIMO multiple access channels in cognitive radio networks

In this article, an efficient distributed and parallel algorithm is proposed to maximize the sum-rate and optimize the input distribution policy for the multi-user single input multiple output multiple access channel (MU-SIMO MAC) system with concurrent access within a cognitive radio (CR) network. The single input means that every user has a single antenna and multiple output means that base station(s) has multiple antennas. The main features are: (i) the power distribution for the users is updated by using variable scale factors which effectively and efficiently maximize the objective function at each iteration; (ii) distributed and parallel computation is employed to expedite convergence of the proposed distributed algorithm; and (iii) a novel water-filling with mixed constraints is investigated, and used as a fundamental block of the proposed algorithm. Due to sufficiently exploiting the structure of the proposed model, the proposed algorithm owns fast convergence. Numerical results verify that the proposed algorithm is effective and fast convergent. Using the proposed approach, for the simulated range, the required number of iterations for convergence is two and this number is not sensitive to the increase of the number of users. This feature is quite desirable for large scale systems with dense active users. In addition, it is also worth noting that the proposed algorithm is a monotonic feasible operator to the iteration. Thus, the stop criterion for computation could be easily set up.

Intelligent operating theater: Technical details for information broadcasting and incident detection system

This paper introduces an intelligent operating theater equipped with a magnetic resonance imaging (MRI) scanner and video recording and broadcasting system to enhance the quality of surgery. To reduce error, intraoperative incidents are detected and dealt with using semi-automatic computer algorithm. A multiple-channel video recording and broadcasting system was installed in an operating room and the surgical procedure was recorded. The supervising surgeon monitored the operation in real-time from outside the operating room. Information sharing via the intra-hospital network improved the work efficiency of staff. The amount of motion was estimated from recorded file size based on the principle of inter-frame video compression. A time period for which the file size significantly increased compared to those for neighboring time periods was chosen and the majority voting technique was applied to detect events using six channels of the video. A change in file size indicated a phase change of the surgical procedure. The proposed method is promising for future daily clinical procedure.

Choosing the right multiple channel system to minimize transaction costs

This paper proposes that firms can use a transaction cost approach to make multiple channel system design related decisions. The author differentiates between two types of multiple channel systems and hypothesizes that transaction asset specificity, behavioral uncertainty and environmental uncertainty lead manufacturers to adopt either a dual channel system or a multiple independent channel system. Furthermore, the author proposes that when all three transaction cost variables match with the type of multiple channel system used, firms can minimize their transaction costs and eventually increase their channel system performance in terms of contribution to firm profitability. The author tests the hypotheses with survey data collected from 229 firms. The results support that the fit between the type of multiple channel mix and the three transaction-cost theory variables results in lower transaction costs and higher contribution to profit. The author presents theoretical and managerial implications.

Modelling impact of dredging and dumping in ebb-flood channel systems

For a channel-shoal system in a funnel-shaped basin the impact of dredging and dumping is investigated using a complex process-based model. First, the residual flow and sediment transport circulations are analysed for the channel-shoal pattern, which has emerged after a long-term model simulation. Results are compared to the Western Scheldt estuary, which forms the inspiration for this study. Subsequently, different dredge and dump scenarios are modelled, according to a conceptual model, in which ebb-and flood-channels and enclosed shoals form morphodynamic units (cells) with their own sediment circulation. Model results show that dumping sediment in a channel further reduces the channel depth and induces erosion in the opposite channel, which enhances tilting of the cross-section of the cell and eventually can lead to the degeneration of a multiple channel system into a single channel. The impact of different dredging and dumping cases agrees with results from a stability analysis. This means that this type of model applied to a realistic geometry can potentially be used for better prediction of the impact of human interventions.

Adding direct or independent channels to multiple channel mix

PurposeThis paper aims to clarify the conditions under which firms can add direct or independent channels to their single channel system and switch to multiple channel systems. Using the transaction cost theory, variables, i.e. specific asset investments, internal uncertainty, and environmental uncertainty, this study seeks to examine how those variables affect firms' decision to adopt a specific multiple channel mix.Design/methodology/approachThe study was conducted within the context of a manufacturer and its multiple channel systems. Using a survey method, primary data were collected from 189 US manufacturers and 98 Taiwanese OEMs. The t‐test and regression analyses were used to test the hypotheses.FindingsThe results indicate that under high‐specific asset investments, high‐environmental uncertainty, and high‐internal uncertainty conditions firms add direct channels and adopt an independent‐direct multiple channel system. On the other hand, under low levels of those variables firms expand their channel system into multiple channels by adopting an independent‐independent multiple channel system.Research limitations/implicationsThe findings provide guidelines to managers regarding the composition of their multiple channel systems. As a limitation, this study uses only three transaction cost variables. Future studies should include other variables that may affect channel design decisions.Originality/valueWhile various studies have analyzed firms' decision to switch to multiple channels by adopting new channels, the nature of those added channels remains under‐researched. This study aims to fill that gap. Also, unlike some other similar studies that only depend on US data, this study tests the hypotheses with the data obtained not only from US manufacturers but also from Taiwanese OEMs