scholarly journals Research on viscoelastic fluid unsteady flow model based on torque loss correction

2021 ◽  
Vol 93 ◽  
pp. 106927
Author(s):  
Bingfan Li ◽  
Gang Liu ◽  
Shiyuan Liu ◽  
Lei Chen
Keyword(s):  
Unsteady Flow ◽  
Viscoelastic Fluid ◽  
Flow Model ◽  
Model Based ◽  
Torque Loss

Kalman Filter and Model-Free Adaptive Control Theory Applied to the Unsteady Flow State Estimation of Product Pipelines

2020 ◽  
Author(s):  
Lei He ◽  
Kai Wen ◽  
Jing Gong
Keyword(s):  
Unsteady Flow ◽  
Linear Model ◽  
Flow Model ◽  
Transient Flow ◽  
Linear Method ◽  
Model Parameters ◽  
Flow State ◽  
Transient Pressure ◽  
Linear Flow ◽  
Model Based

Abstract The accurate online estimation of unsteady flow state provides important operation information for product pipelines real-time scheduling. In practice, affected by the parameter drift and observation noises, traditional estimation methods based on the first principle can hardly provide accurate results within acceptable time. The nonlinear and fast transient characteristics of pipeline flow make it difficult to realize on-line adaptive modification of model parameters. In order to meet the requirements of computational efficiency and accuracy simultaneously, this paper proposes a methodology with two-level adaptive adjustment to realize the digital twin of pipeline nonlinear transient flow process by using simplified linear flow model. In terms of improving computing efficiency, the linear flow model based on frequency response and difference transforming is established to process the on-line state estimation of transient flow. To reduce the deviation between the actual observed value and the linear model estimation, we first introduce mode-free adaptive control method as linear compensation of the reduced order unsteady flow model. The compact form dynamic linearization method has been adopted to design the virtual input of the linear flow model. To further improve the adaptability of the linear model, the model parameters are online adjusted by using the recursive least squares with forgetting factor method. The uncertainty of the model and the interference of observation noise is eliminated by adopting Kalman filter to the state space model based on modified linear model. The effectiveness of the proposed methodology is evaluated by applying to the digital twin process of a product pipeline transient pressure in a multistation pipeline. The results show that the proposed method can make transient pressure estimation of second-order linear model agree well with the value of nonlinear flow model even under unforeseen conditions and noise interference. The performance of the proposed method is better than model-based linear method, data-driven linear method and nonlinear method.

New Method Based on Model-Free Adaptive Control Theory and Kalman Filter for Multi-Product Unsteady Flow State Estimation

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Lei He ◽  
Jing Gong ◽  
Kai Wen ◽  
Changchun Wu ◽  
Yuan Min
Keyword(s):  
Adaptive Control ◽  
Unsteady Flow ◽  
State Estimation ◽  
Flow Model ◽  
Transient Flow ◽  
Pipeline System ◽  
Flow State ◽  
Flow Estimation ◽  
Model Based ◽  
Model Free

Abstract In this paper, a new methodology is proposed to realize real-time unsteady flow estimation for a multi-product pipeline system. Integrating transient flow model, adaptive control theory, and adaptive filter, this method is developed to solve the contradiction between the efficiency and accuracy in traditional model-based methods. In terms of improving computational efficiency, the linear flow model based on frequency response and difference transforming is established to replace the traditional nonlinear flow model for transient flow state estimation. To reduce the deviation between actual observations and linear model estimates, we first introduce a model-free adaptive control method as linear compensation of the reduced order unsteady flow state model. To overcome the interference of observation noise, the Kalman filter method is applied to the modified state space model to obtain the one-step-ahead transient flow estimation. The proposed method is applied to the transient flow state estimation of a multi-product pipeline system and compared with the model-based method and two data-driven methods. The proposed method can reduce the deviation of transient flow estimation between the reduced order linear model and the traditional nonlinear model to less than 0.5% under unforeseen conditions and shows strong robustness to noise interference and parameter drift.

Traffic flow model based on real data

2021 ◽  
Author(s):  
Teodora A. Mecheva ◽  
Nikolay R. Kakanakov
Keyword(s):  
Traffic Flow ◽  
Flow Model ◽  
Real Data ◽  
Traffic Flow Model ◽  
Model Based

Values, Constraints, and Maneuvers

2021 ◽  
pp. 170-191
Author(s):  
Tehila Kalagy
Keyword(s):  
Higher Education ◽  
Case Studies ◽  
Flow Model ◽  
Traditional Values ◽  
Academic Institutions ◽  
Female Model ◽  
Model Based ◽  
Education Academic ◽  
The Individual ◽  
High Degree

For about a decade, ultra-Orthodox and Bedouin women have been applying to higher education academic institutions in Israel in order to study despite bans from their conservative communities. Academic studies instill learning and culture, create an encounter with knowledge for the individual and thus carry a high degree of threat to the rigid conservative enclave. This article examines how conservative societies cope with the wheels of change as the process of higher education for women expands. The case studies in this article are 60 educated women from Jewish ultra-Orthodox society and from Negev Bedouin groups in Israel. As shown by the findings, a theoretical flow model based on three parameters emerges: value-constraint-maneuver. In summary, it appears that this model reflects the development of a new conservative female model that combines traditional values with contemporary indicators.

Sign in / Sign up

Export Citation Format

Share Document