Search results for "communication channel"

Online channel adoption in supermarket retailing

2021

Abstract Introducing a new online channel is a crucial decision for brick-and-mortar retailers that requires insight and forecasts into customers' adoption and subsequent behaviour. The aim of this study is to analyse the dynamics in the behavioural heterogeneity of (new) multichannel supermarket customers when the online channel is introduced. A Latent Class Analysis (LCA) was conducted on 1151 adopters of the new online channel of a supermarket retailer to segment customers. We employed an extended “Recency, Frequency and Monetary (RFM)” model that includes customers’ purchases prior to the introduction of the new channel. Results show that adopters of a new channel are not a homogenous g…

Markov Chain Analysis of CA and CF with Multiple Types of Users

2019

In the previous chapter, we studied in depth the impact of CA and CF on traffic flows in systems where there exists only one type of users with one type of flows. In this chapter, the influence of CA and CF is studied in a more complicated scenario, i.e., the one in which multiple users exist, and where users have different priorities in using channel resources. CRN is a typical example for such a system, and we study the CRNs where PUs and SUs have one type of flows for each.

A Single radio based channel datarate-aware parallel rendezvous MAC protocol for cognitive radio networks

2009

Channel hopping based parallel rendezvous multichannel MAC protocols have several advantages since they do not need a control channel, require only one transceiver, and produce higher system capacity. However, channel hopping sequences in existing parallel rendezvous MAC protocols have been designed as irrelevant to channel datarates, leading to under-utilization of channel resources in multi-rate multi-channel networks. Considering that datarates among channels may be different, we propose a dynamic parallel rendezvous multichannel MAC protocol for synchronized cognitive radio networks in which the secondary users adjust their own distinct hopping sequences according to the datarates of th…

Estimation of the Velocity of Multiple Moving Persons in Non-Stationary Indoor Environments from Received RF Signals

2019

This paper presents a new accurate iterative procedure to estimate the time-variant (TV) velocity, i.e., TV speed, TV vertical angle-of- motion (VAOM), and TV horizontal angle-of-motion (HAOM), of multiple moving objects/persons in three-dimensional (3D) non-stationary indoor propagation environments. The indoor space is assumed to be equipped with a distributed 3x3 multiple-input multiple-output (MIMO) system. The proposed procedure focuses on estimating the TV speed, TV VAOM, and TV HAOM by matching the spectrogram of the complex channel gain of a non- stationary indoor channel model to the spectrogram obtained from received radio frequency (RF) signals. Together with the velocity …

A New Iterative Estimation Procedure for the Localization of Passive Stationary Objects from Received RF Signals in Indoor Environments

2019

This paper deals with the localization of passive stationary objects from the received radio- frequency (RF) signals in 3-dimensional (3D) indoor environments. Each object located in the 3D indoor environment is modelled by a single point scatterer. The propagation space is equipped with a multiple-input multiple-output (MIMO) wireless communication system. The employed channel model is flexible and allows to have a line-of-sight (LOS) component as well as single- and double- bounce scattering components. Here, we present a new accurate iterative estimation technique for computing the optimal coordinates as well as the number of the main stationary objects (scatterers) in indoor areas. The …

Friction Factor for Gravel-Bed Channel with High Boulder Concentration

2000

This paper reports the results of an experimental investigation on flow resistance law for a gravel-bed channel having bed arrangements characterized by different values of the number of boulders. The dependence is studied of a parameter, proposed for describing the gravel-bed surfaces, on the boulder concentration and on the ratio between the median diameter of the coarser particles and the median diameter of the bed layer. Flume measurements carried out for the hydraulic condition of \Itransition\N and \Ilarge-scale\N roughness (1.5 ≤ \ih/\id\d5\d0 ≤ 6.9) show that the intercept of the semilogarithmic flow resistance law depends on the ratio and on boulder concentration. For concentration…

The influence of roughness geometry and shields parameter on flow resistance in gravel-bed channels

1997

The spatial variability of bed particles of a gravel-bed channel is analysed and treated experimentally in order to simulate the effects of the arrangement of coarse bed elements on the flow resistance law. For the studied bed patterns, characterized by the concentration Γ of coarser elements arranged on the bed layer, a particle arrangement parameter α is proposed. The α parameter is useful for estimating the intercept b0 of the semi-logarithmic flow resistance law deduced by flume measurements carried out for the hydraulic condition of large-scale and transition roughness. The differences between the experimental friction factor parameter values and the ones calculated by the proposed sem…

Photochemical and Chemical Two-Channel Control of Functional Nanogated Hybrid Architectures

2007

Anisotropic flow in striped superhydrophobic channels

2012

We report results of dissipative particle dynamics simulations and develop a semi-analytical theory of an anisotropic flow in a parallel-plate channel with two superhydrophobic striped walls. Our approach is valid for any local slip at the gas sectors and an arbitrary distance between the plates, ranging from a thick to a thin channel. It allows us to optimize area fractions, slip lengths, channel thickness and texture orientation to maximize a transverse flow. Our results may be useful for extracting effective slip tensors from global measurements, such as the permeability of a channel, in experiments or simulations, and may also find applications in passive microfluidic mixing.

Monte Carlo analysis of polymer translocation with deterministic and noisy electric fields

2012

AbstractPolymer translocation through the nanochannel is studied by means of a Monte Carlo approach, in the presence of a static or oscillating external electric voltage. The polymer is described as a chain molecule according to the two-dimensional “bond fluctuation model”. It moves through a piecewise linear channel, which mimics a nanopore in a biological membrane. The monomers of the chain interact with the walls of the channel, modelled as a reflecting barrier. We analyze the polymer dynamics, concentrating on the translocation time through the channel, when an external electric field is applied. By introducing a source of coloured noise, we analyze the effect of correlated random fluct…