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Experimental study on steady state heating performance of a multi-type heat pump system for finding the optimum control variable

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JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY 2011年第6期25卷 1415-1422页

作者： Choi, Jong Won Lee, Il Hwan Kim, Min Soo Seoul Natl Univ Div WCU Multiscale Mech Design Sch Mech & Aerosp Engn Seoul 151744 South Korea Korea Inst Sci & Technol Evaluat & Planning Natl R&D Coordinat & Evaluat Ctr Seoul 137130 South Korea

This paper describes the steady state heating performance of a multi-type heat pump system. The operation range of such systems has extended to cover various situations, and there is a requirement for systems that provide sufficient performance in those situations. Thus, many researchers have made efforts to design a controller or develop control logic that ensures optimal operation. In a multi-type heat pump, effective control of individual indoor units is necessary for satisfying heating or cooling demands. In such systems, a successfully designed controller must consider cross-coupling effects among indoor units during alteration of control variables such as expansion valve opening and compressor speed. Thus, we investigated cross-coupling effects among indoor units under various working conditions to help determine an optimum and effective control variable. The heating performance and the relationship among the operating variables of the multi-type heat pump system with R410A indicated that the temperature of the indoor units' secondary fluid was a suitable control variable.

关键词： control variable Electronic expansion valve Expansion valve openings Multi-type heat pump system R410A

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Bottom topography as a control variable in an ocean model

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JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY 2003年第11期20卷 1685-1696页

作者： Losch, M Wunsch, C MIT Dept Earth Atmospher & Planetary Sci Cambridge MA USA

The possibility of using topography in a state estimation context as a control parameter is explored in a linear barotropic shallow water model. Along with its adjoint, the model is used to systematically assess the influence of the depth field on the modeled circulation in a steady state. Sensitivity of the flow field to the topography is greater in a partially blocked zonal channel than in a subtropical gyre. Hypothetical surface elevations are used to represent the types of data actually available. In neither case can all the details of the topography be recovered, showing that the relationship between topography and elevation does not have a unique inverse, and that many details of the topography are irrelevant to the particular physics under consideration.

关键词： oceans flow field DEPTH OF FIELD control variable control parameter ocean models Bottom topography

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CMOS exponential-control variable gain amplifiers

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IEE PROCEEDINGS-CIRCUITS DEVICES AND SYSTEMS 2004年第2期151卷 83-86页

作者： Liu, W Liu, SI Wei, SK Natl Taiwan Univ Dept Elect Engn Taipei 10617 Taiwan Natl Taiwan Univ Grad Inst Elect Engn Taipei 10617 Taiwan Tung Nan Inst Technol Dept Elect Engn Taipei 2202 Taiwan

New CMOS exponential-control variable-gain amplifiers (VGAs) are presented. The control signal can be either current-mode or voltage-mode. Since no multiplier is needed in the proposed circuits, the proposed VGAs can be very compact. For the case of supply voltages V-D=\V-SS\ = 1.5 V, the power dissipation is only 0.48 mW. The gain control range of the proposed VGA can be 30 dB. The proposed circuits have been fabricated in a 0.5 mum n-well CMOS process. Experimental results are given to confirm the feasibility of the proposed VGAs, which are expected to be useful in analogue signal processing applications.

关键词： control range Electric circuits control variable Gain control Amplifiers CMOS process Power dissipation n-well ANALOG SIGNALS VGA Multiplying circuits

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Reliability Evaluation of Power System integrated. With Wind Farms Based on control variable Sampling

Reliability Evaluation of Power System integrated. With Wind...

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Chinese Automation Congress (CAC)

作者： Qiu, Xuanyu Guo, Yiguo Lan, Feng Xi, Lei State Grid Econ Res Inst Shandong Elect Power Co Jinan Shandong Peoples R China China Three Gorges Univ Coll Elect Engn & New Energy Yichang Peoples R China

ISBN: (纸本)9781538635247

Monte-Carlo sampling method in reliability evaluation has defects of great sampling number and low efficiency. This paper proposed control variable method in power system integrated with wind power unit, considering its feather of small unit capacity and large unit number. The proposed method is carried out on the IEEE RTS79 test system, compares with the conventional Monte-Carlo method and the average and scattered sampling method, the factors affect sampling efficiency are analyzed. The simulation results show that the proposed method can greatly reduce the sampling times and improve sampling efficiency, besides, demonstrates the correctness and effectiveness of the proposed method.

关键词： control variable wind power reliability index sampling times LOEE

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Problems with the control variable Approach in Achieving Unbiased Estimates in Nonlinear Models in the Presence of Many Instruments

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JOURNAL OF QUANTITATIVE ECONOMICS 2021年第SUPPL 1期19卷 39-58页

作者： Hahn, Jinyong Hausman, Jerry UCLA Econ BOX 9514778283 Bunche Hall Los Angeles CA 90095 USA MIT Econ 77 Massachusetts AveBldg E52-300 Cambridge MA 02139 USA

We present a pseudo-panel model and argue that the control variable approach is subject to the many instrument problem, since it uses the predicted value of the endogenous variable. We show how the bias can be analyti... 详细信息

关键词： control variable Many instruments Nonlinear models

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The Illusion of Statistical control: control variable Practice in Management Research

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ORGANIZATIONAL RESEARCH METHODS 2012年第3期15卷 413-435页

作者： Carlson, Kevin D. Wu, Jinpei Virginia Tech Dept Management Pamplin Coll Business Blacksburg VA 24061 USA Minnesota State Univ Moorhead Sch Business Moorhead MN USA

The authors extend previous recommendations for improved control variable (CV) practice in management research by mapping the objectives for using statistical control to recommendations for research practice. Including CVs in research designs to permit statistical control of "nuisance" variance is a common research practice that is subject to well-documented and potentially serious problems. Yet because CVs are frequently weakly related to focal variables, they rarely influence the interpretation of results. As a result, current practice offers an illusion of statistical control when in fact little control actually occurs. The authors extend the growing literature on CV practice by examining the ambiguity of researchers' stated purposes for using statistical control that makes it difficult to determine whether common CV practice accomplishes any of these intents effectively. Guidelines for improving research practice are offered, including adopting a conservative stance toward the inclusion of CVs in the analysis of quasiexperimental and correlational designs guided by the principle "When in doubt, leave them out.".

关键词： control variable multiple regression statistical control

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Methods to Deal with control variable Path Constraints in Dynamic Optimization Problems

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Acta Automatica Sinica 2013年第4期39卷 440-449页

作者： Yun-Qing HU Xing-Gao LIU

Many researchers have reported their methods to handle state variable path constraints in dynamic optimization problems. However, very few of them mentioned the techniques to handle control variable path constraints specifically. This paper firstly introduces two methods to deal with control variable path constraints, then presents a novel smoothed quadratic penalty function method that can solve dynamic optimization problems with both control and state variable path constraints at the same time. The control variable parameterization strategy is used to solve the resulting problems. Two separate cases are considered where testing of case1 demonstrates the characteristics of the three methods, while testing of Case 2 indicates the effectiveness and the superiority of the proposed smoothed penalty function method.

关键词： Dynamic optimization path constraint control variable control variable parameterization

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MODELING AND control OF variable-SPEED WIND-TURBINE DRIVE-SYSTEM DYNAMICS

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IEEE control SYSTEMS MAGAZINE 1995年第4期15卷 28-38页

作者： NOVAK, P EKELUND, T JOVIK, I SCHMIDTBAUER, B UNIV BORAS DEPT TECHNOLBORASSWEDEN

When designing control for variable-speed wind turbines, one YY deals with highly resonant, non-linear dynamic systems subject to random excitation, i.e., wind turbulence. This requires good knowledge of the dynamics to be controlled, particularly when combined with the increasingly common ''soft'' concept of lightweight, flexible constructional components;it creates cost advantages compared to more material-consuming rigid constructions, but also results in low frequency structural eigenfrequencies, some of which may appear in the bandwidth of closed-loop operation. For this article, system-identification experiments have been performed on an existing 400 kW, variable-speed, horizontal-axis wind turbine using various identification schemes. The identification results have then provided numerical values of the parameters in a physical model of the drive system. The acquired model has been used for design and evaluation of a number of linear and non-linear control schemes for wind-turbine speed regulation.

关键词： variable speed Modeling Wind Energy Conversion Systems numerical value closed loop operation physical models Standing Orders System dynamics control variable drive train dynamics random excitation wind speed

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An Aerodynamic Torque Observer for the Robust control of variable-Speed Wind Turbines

An Aerodynamic Torque Observer for the Robust Control of Var...

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IEEE Annual Conference on Decision and control

作者： M. L. Corradini G. Ippoliti G. Orlando Scuola di Scienze e Tecnologie Universita di Camerino via Madonna delle Carceri Dipartimento di Ingegneria dell'Informazione Universita Politecnica delle Marche via Brecce Bianche

ISBN: (纸本)9781467320658

This paper focuses on a robust power generation control strategy for a variable speed wind energy conversion system based on a permanent magnet synchronous generator. The proposed control strategy combines a robust observer of the aerodynamic torque with a Sliding Mode (SM) based field oriented control strategy. The robust vanishing of the observation error and the tracking error is proved. Reported numerical simulations show that the proposed SM approach is effective in terms of optimal power extraction and it is robust with respect to uncertainties affecting the system.

关键词： stability derivatives variable speed wind turbine control variable Wind Energy Conversion Systems Robust control power extraction power generation control control strategy variable speed Samarium

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Learning hidden relationship between environment and control variables for direct control of automated greenhouse using Transformer-based model

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COMPUTERS AND ELECTRONICS IN AGRICULTURE 2025年 235卷

作者： Lee, Junseo Im, Seongil Jeong, Jae-Seung Lee, Taek Sung Park, Soo Hyun Shin, Changhwan Ju, Hyunsu Kim, Hyung-Jun Korea Inst Sci & Technol Postsilicon Semicond Inst Seoul 02792 South Korea Korea Univ Dept Elect & Comp Engn Seoul 02841 South Korea Yonsei Univ Dept Chem & Biomol Engn Seoul 03722 South Korea Sahmyook Univ Dept Artificial Intelligence Convergence Seoul 01795 South Korea Korea Inst Sci & Technol Smart Farm Res Ctr Kangnung 25451 South Korea

Climate change poses a significant threat to agricultural sustainability and food security. Automated greenhouse systems, which provide stable and controlled environments for crop cultivation, have emerged as a promising solution. However, traditional rule-based greenhouse control algorithms struggle to determine optimal control variables due to the complex relationships between environmental variables. In response, we propose a Transformer-based model, Trans-Farmer, which predicts the control variables by considering the complex interactions among environmental variables. Trans-Farmer leverages the attention mechanism to learn the intricate relationships among the environmental variables. The encoder-decoder structure enables the translation of the environmental variables into the corresponding control variables, analogous to language translation. Experimental results demonstrate that Trans-Farmer outperforms baseline models across all the evaluation metrics, achieving superior accuracy and predictive performance. The attention maps of the encoder visualize how Trans-Farmer comprehends the complex interactions among the environmental variables. Additionally, the compact size of Trans-Farmer is suitable for application in general greenhouses with constrained microcontroller units. This approach contributes to the development of automated greenhouse management systems and emphasizes the potential of artificial intelligence applications in agriculture.

关键词： Automated Greenhouse Deep Learning Transformer control variable Language Translation

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