Modeling for control of a centrifugal compression system

Abstract onl

Practical issues in model-based surge control for centrifugal compressors

The performance and operating range of centrifugal compressors is limited by the occurrence of an aerodynamic instability called surge. This paper deals with the technological barriers for feedback stabilization of full-scale centrifugal compression systems. A dynamic model for a single stage compressor test rig is presented and a surge control strategy is discussed. Then the critical problems of model accuracy and sensor and actuator limitations are discussed. These problems are illustrated with simulation results and experimental data. We conclude by suggesting directions for further work in order to successfully implement active surge control in full-scale applications

Approximate realization with time delay

This paper describes the application of an approximate realization algorithm to dynamical systems with a time delay. First, a well-known algorithm is presented to obtain an approximate realization from an impulse response sequence. Then the limitation that a time delay imposes on the accuracy of this algorithm is discussed, and it is pointed out that time delays should be explicitly taken into account. Therefore, a time delay estimation method is proposed that utilizes the presented approximate realization algorithm. Simulation results show that the method is likely to provide an accurate estimate for the time delay in a dynamical syste

Stability parameter identification for a centrifugal compression system

This paper presents the application of a lumped parameter model to describe the dynamic behavior of a centrifugal compression system including surge. The response of the model is compared with experimental surge measurements from an industrial single stage compressor test rig. A parametric analysis of the model reveals the large influence of the stability parameter on the transient response. However, a good value for this parameter is not easily obtained fromsurge data. Therefore, an identification method is proposed to uniquely determine the stability parameter that is based on an approximate realization algorithm, making use of the fact that the step response of the system has the characteristics of a first order system. Simulation results show that this method canprovide an estimate for the stability parameter of a centrifugal compression system

A high-speed valve for surge control in a centrifugal compression system

This paper deals with the critical problem of actuator limitations for the successful implementation of active surge control. We specify the capacity, bandwidth and allowable time delay for a control valve that can be used to actively suppress surge in a specific full-scale centrifugal compression system. The actuator requirements are obtained from closed-loop simulations with a nonlinear simulation model of the compressor test rig. In order to meet the requirements, a new high-speed valve actuator had to be developed. We present the resulting actuator design and provide test results to illustrate that the control valve meets our design specifications

SALARECON connects the Atlantic salmon genome to growth and feed efficiency

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Barriers, facilitators, and other factors associated with health behaviors in childhood, adolescent, and young adult cancer survivors: A systematic review

\ua9 2024 The Author(s). Cancer Medicine published by John Wiley & Sons Ltd.Background: Healthy behaviors are paramount in preventing long-term adverse health outcomes in childhood, adolescent, and young adult (CAYA) cancer survivors. We systematically reviewed and synthesized existing literature on barriers, facilitators, and other factors associated with health behaviors in this population. Methods: MEDLINE and PsycInfo were searched for qualitative and quantitative studies including survivors aged 16–50 years at study, a cancer diagnosis ≤25 years and ≥2 years post diagnosis. Health behaviors included physical activity, smoking, diet, alcohol consumption, sun exposure, and a combination of these behaviors (defined as health behaviors in general). Results: Barriers, facilitators, and other factors reported in ≥2 two studies were considered relevant. Out of 4529 studies, 27 were included (n = 31,905 participants). Physical activity was the most frequently examined behavior (n = 12 studies), followed by smoking (n = 7), diet (n = 7), alcohol (n = 4), sun exposure (n = 4), and health behavior in general (n = 4). Relevant barriers to physical activity were fatigue, lack of motivation, time constraints, and current smoking. Relevant facilitators were perceived health benefits and motivation. Influence of the social environment and poor mental health were associated with more smoking, while increased energy was associated with less smoking. No relevant barriers and facilitators were identified for diet, alcohol consumption, and sun exposure. Barriers to healthy behavior in general were unmet information needs and time constraints whereas lifestyle advice, information, and discussions with a healthcare professional facilitated healthy behavior in general. Concerning other factors, women were more likely to be physically inactive, but less likely to drink alcohol and more likely to comply with sun protection recommendations than men. Higher education was associated with more physical activity, and lower education with more smoking. Conclusion: This knowledge can be used as a starting point to develop health behavior interventions, inform lifestyle coaches, and increase awareness among healthcare providers regarding which survivors are most at risk of unhealthy behaviors