Layout optimization of large-scale oil–gas gathering system based on combined optimization strategy

Intl J Robust & Nonlinear

et al. 2020

In this article, the nonfragile H ∞ filtering problem is investigated for a class of discrete multirate time-delayed systems over sensor networks. The probabilistic packet dropout occurs during the information transmissions among the sensor nodes in the sensor network characterized by the Gilbert-Elliott model. In order to take the multirate sampling into account, the state updating period of the system and the sampling period of the sensors are allowed to be different. The variation of the filter gain is considered to reflect the physical errors with the filter implementation. The aim of this article is to design a set of nonfragile filters such that, in the presence of multirate sampling, time-delays, and packet dropouts, the filtering error dynamics is exponentially mean-square stable and also satisfies the H ∞ performance requirement. By using the Lyapunov-Krasovskii functional approach, a sufficient condition is derived, which ensures the exponential mean-square stability and the H ∞ performance requirement of the filtering error dynamics. Then, the filter gains are characterized in terms of the solution to a set of matrix inequalities. Finally, a simulation example is provided to demonstrate the effectiveness of the proposed filtering scheme. K E Y W O R D SGilbert-Elliott model, multirate sampling, nonfragile H ∞ filtering, packet dropouts, sensor networks, time-delays

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Nonfragile H_∞ filtering for discrete multirate time‐delayed systems over sensor networks characterized by Gilbert‐Elliott models

Intl J Robust & Nonlinear

et al. 2020

“…In this paper, we consider the WTOD protocol to save communication energy and prevent the data from collisions. As shown in Figure 1, for the underlying systems, only one sensor node is selected to transmit its measurement information to the central filter at each time step, where the specific selection strategy is realized by the updating rule in (5).…”

Section: Problem Formulationmentioning

confidence: 99%

H_∞ finite‐horizon filtering for complex networks with state saturations: The weighted try‐once‐discard protocol

Intl J Robust & Nonlinear

et al. 2019

Summary This paper addresses the finite‐horizon H∞ filtering problem for a kind of discrete state‐saturated time‐varying complex networks subjected to the weighted try‐once‐discard (WTOD) protocol. Under the WTOD protocol, only the measurement signal from one sensor node is allowed to be transmitted to the filter at each time point, where such a node is selected based on a certain quadratic selection principle. The main purpose of this paper is to design an H∞ filter that guarantees the disturbance attenuation level on a given finite time‐horizon for the underlying complex network subject to both state saturations and WTOD protocols. By using the convex hull approach, sufficient conditions are first obtained to ensure the existence for the desired filter to achieve the H∞ performance specification by means of a few recursive matrix inequalities. Then, based on the obtained results, the filter parameters are designed, which cope effectively with both state saturations and communication protocols. Finally, a numerical simulation is employed to demonstrate the validity of the developed filter algorithm.

“…Petroleum plays a vital role in industrial production [1,2]. Many of its advantages are incomparable with other fuels and alternatives cannot be developed in a short time [3,4].…”

Section: Introductionmentioning

confidence: 99%

Role of Shearing Dispersion and Stripping in Wax Deposition in Crude Oil Pipelines

Zhao

et al. 2019

Energies

Self Cite

Wax deposition during crude oil transmission can cause a series of negative effects and lead to problems associated with pipeline safety. A considerable number of previous works have investigated the wax deposition mechanism, inhibition technology, and remediation methods. However, studies on the shearing mechanism of wax deposition have focused largely on the characterization of this phenomena. The role of the shearing mechanism on wax deposition has not been completely clarified. This mechanism can be divided into the shearing dispersion effect caused by radial migration of wax particles and the shearing stripping effect caused by hydrodynamic scouring. From the perspective of energy analysis, a novel wax deposition model was proposed that considered the flow parameters of waxy crude oil in pipelines instead of its rheological parameters. Considering the two effects of shearing dispersion and shearing stripping coexist, with either one of them being the dominant mechanism, a shearing dispersion flux model and a shearing stripping model were established. Furthermore, a quantitative method to distinguish between the roles of shearing dispersion and shearing stripping in wax deposition was developed. The results indicated that the shearing mechanism can contribute an average of approximately 10% and a maximum of nearly 30% to the wax deposition process. With an increase in the oil flow rate, the effect of the shearing mechanism on wax deposition is enhanced, and its contribution was demonstrated to be negative; shear stripping was observed to be the dominant mechanism. A critical flow rate was observed when the dominant effect changes. When the oil flow rate is lower than the critical flow rate, the shearing dispersion effect is the dominant effect; its contribution rate increases with an increase in the oil flow temperature. When the oil flow rate is higher than the critical flow rate, the shearing stripping effect is the dominant effect; its contribution rate increases with an increase in the oil flow temperature. This understanding can be used to design operational parameters of the actual crude oil pipelines and address the potential flow assurance problems. The results of this study are of great significance for understanding the wax deposition theory of crude oil and accelerating the development of petroleum industry pipelines.