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Journal articles on the topic 'Lumped and Distributed-Lumped modelling'

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Author: Grafiati

Published: 10 December 2022

Last updated: 29 January 2023

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1

Gaudreault, M., and M. G. Stubbs. "Lumped-element components for GaAs monolithic microwave integrated circuits." Canadian Journal of Physics 63, no. 6 (June 1, 1985): 736–39. http://dx.doi.org/10.1139/p85-117.

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Gallium-arsenide monolithic microwave integrated circuits (GaAs MMIC's) promise the microwave circuit designer significant size, weight, and reliability advantages. Distributed and lumped matching techniques have been utilized previously in MMIC design with the latter offering greater bandwidth and smaller size. In this paper, experimental results for lumped interdigitated capacitors on a gallium-arsenide substrate are presented. Computer modelling in the frequency range 2–18 GHz was used to derive a set of design curves for these capacitors. These curves cover aspect ratios of w/s = 1 and w/s = 2.5. Experimental results obtained by using these curves to design lumped-element monolithic filters show excellent agreement with theory.

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2

Athanasiou, Panagiotis, and Yaser Hadi. "Simulation of Oil Well Drilling System Using Distributed–Lumped Modelling Technique." Modelling 1, no. 2 (November 12, 2020): 175–97. http://dx.doi.org/10.3390/modelling1020011.

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The strengths and torque of well-boiling hydrocarbons are of utmost significance. Boiling a well is one of the most critical steps in the discovery and production of oil and gas. The well’s boiling process is expensive because the drilling depth can be as much as 7000 meters. Any delay (breakdown time) in boiling costs a lot of money for hydrocarbon firms. Various boiler parameters are continuously tracked and regulated to avoid drilling delays. This paper focuses on the vibrations occurring at the bottom hole assembly (BHA) stick-slip. Two modelling methods, the lumped parameter model and the combination of the distributed–lumped (D–L) parameter model, were used and compared to the actual measurement performance. The D–L model was found to be more precise, particularly for long strings. Using the simulations, the most comprehensive modelling methodology is introduced.

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3

Herath, Herath Mudiyanselage Viraj Vidura, Jayashree Chadalawada, and Vladan Babovic. "Hydrologically informed machine learning for rainfall–runoff modelling: towards distributed modelling." Hydrology and Earth System Sciences 25, no. 8 (August 11, 2021): 4373–401. http://dx.doi.org/10.5194/hess-25-4373-2021.

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Abstract. Despite showing great success of applications in many commercial fields, machine learning and data science models generally show limited success in many scientific fields, including hydrology (Karpatne et al., 2017). The approach is often criticized for its lack of interpretability and physical consistency. This has led to the emergence of new modelling paradigms, such as theory-guided data science (TGDS) and physics-informed machine learning. The motivation behind such approaches is to improve the physical meaningfulness of machine learning models by blending existing scientific knowledge with learning algorithms. Following the same principles in our prior work (Chadalawada et al., 2020), a new model induction framework was founded on genetic programming (GP), namely the Machine Learning Rainfall–Runoff Model Induction (ML-RR-MI) toolkit. ML-RR-MI is capable of developing fully fledged lumped conceptual rainfall–runoff models for a watershed of interest using the building blocks of two flexible rainfall–runoff modelling frameworks. In this study, we extend ML-RR-MI towards inducing semi-distributed rainfall–runoff models. The meaningfulness and reliability of hydrological inferences gained from lumped models may tend to deteriorate within large catchments where the spatial heterogeneity of forcing variables and watershed properties is significant. This was the motivation behind developing our machine learning approach for distributed rainfall–runoff modelling titled Machine Induction Knowledge Augmented – System Hydrologique Asiatique (MIKA-SHA). MIKA-SHA captures spatial variabilities and automatically induces rainfall–runoff models for the catchment of interest without any explicit user selections. Currently, MIKA-SHA learns models utilizing the model building components of two flexible modelling frameworks. However, the proposed framework can be coupled with any internally coherent collection of building blocks. MIKA-SHA's model induction capabilities have been tested on the Rappahannock River basin near Fredericksburg, Virginia, USA. MIKA-SHA builds and tests many model configurations using the model building components of the two flexible modelling frameworks and quantitatively identifies the optimal model for the watershed of concern. In this study, MIKA-SHA is utilized to identify two optimal models (one from each flexible modelling framework) to capture the runoff dynamics of the Rappahannock River basin. Both optimal models achieve high-efficiency values in hydrograph predictions (both at catchment and subcatchment outlets) and good visual matches with the observed runoff response of the catchment. Furthermore, the resulting model architectures are compatible with previously reported research findings and fieldwork insights of the watershed and are readily interpretable by hydrologists. MIKA-SHA-induced semi-distributed model performances were compared against existing lumped model performances for the same basin. MIKA-SHA-induced optimal models outperform the lumped models used in this study in terms of efficiency values while benefitting hydrologists with more meaningful hydrological inferences about the runoff dynamics of the Rappahannock River basin.

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4

Alkaragoolee, MYA, KM Ebrahimi, and R. Whalley. "A hybrid model for a drilling process for hydrocarbon well-boring operations." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 231, no. 4 (March 7, 2017): 726–38. http://dx.doi.org/10.1177/1464419317697854.

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In hydrocarbon well-drilling operations, self-excited, stick-slip vibration is considered as a source of drilling equipment failures, which also causes a reduction in the drilling penetration. This leads to delays and increase in the operational and equipment costs. A new approach using distributed-lumped (hybrid) modelling is considered as the first step in understanding the stick-slip phenomena in order to determine a solution to this problem. In this paper, a hybrid modelling scheme is the advocated modelling method proposed in contrast to the conventional lumped modelling. Three case studies are used to show that hybrid modelling is an accurate technique in the representation of stick-slip oscillations, particularly when the length of the drill string is high. The results show that the modelling technique adopted in this work can more accurately present the phenomena associated with stick-slip process.

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5

GRANT, MALCOLM A. "MATHEMATICAL MODELLING OF WAIRAKEI GEOTHERMAL FIELD." ANZIAM Journal 50, no. 3 (January 2009): 426–34. http://dx.doi.org/10.1017/s1446181109000212.

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AbstractMathematical modelling of Wairakei geothermal field is reviewed, both lumped-parameter and distributed-parameter models. In both cases it is found that reliable predictions require five to ten years of history for calibration. With such calibration distributed-parameter models are now used for field management. A prudent model of Wairakei, constructed without such historical data, would underestimate field capacity and provide only general projections of the type of changes in surface activity and subsidence.

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6

Savenije, H. H. G. "HESS Opinions "Topography driven conceptual modelling (FLEX-Topo)"." Hydrology and Earth System Sciences 14, no. 12 (December 23, 2010): 2681–92. http://dx.doi.org/10.5194/hess-14-2681-2010.

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Abstract. Heterogeneity and complexity of hydrological processes offer substantial challenges to the hydrological modeller. Some hydrologists try to tackle this problem by introducing more and more detail in their models, or by setting-up more and more complicated models starting from basic principles at the smallest possible level. As we know, this reductionist approach leads to ever higher levels of equifinality and predictive uncertainty. On the other hand, simple, lumped and parsimonious models may be too simple to be realistic or representative of the dominant hydrological processes. In this commentary, a new approach is proposed that tries to find the middle way between complex distributed and simple lumped modelling approaches. Here we try to find the right level of simplification while avoiding over-simplification. Paraphrasing Einstein, the maxim is: make a model as simple as possible, but not simpler than that. The approach presented is process based, but not physically based in the traditional sense. Instead, it is based on a conceptual representation of the dominant physical processes in certain key elements of the landscape. The essence of the approach is that the model structure is made dependent on a limited number of landscape classes in which the topography is the main driver, but which can include geological, geomorphological or land-use classification. These classes are then represented by lumped conceptual models that act in parallel. The advantage of this approach over a fully distributed conceptualisation is that it retains maximum simplicity while taking into account observable landscape characteristics.

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7

Whalley, Robert, and Alaa Abdul-Ameer. "Warship propulsion system control." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 10 (January 17, 2012): 2402–21. http://dx.doi.org/10.1177/0954406211434389.

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The modelling of a dual gas turbine, single-shaft transmission drive, for a naval propulsion system, is considered. Owing to the spatial dispersion of the arrangement, a distributed–lumped parameter approach to the dynamic analysis problem is necessary. This enables the relatively concentrated assemblies to be included as lumped, pointwise representations and the propulsion shaft to be incorporated as a dispersed inertia and stiffness element. A multivariable, least effort controller design strategy is employed to achieve the regulation required. The performance of the closed-loop system following reference input and load disturbances is evaluated and the drive shaft speed and twist angle response transients are computed.

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8

Moustakas, Sotirios, and Patrick Willems. "Testing the Efficiency of Parameter Disaggregation for Distributed Rainfall-Runoff Modelling." Water 13, no. 7 (April 1, 2021): 972. http://dx.doi.org/10.3390/w13070972.

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A variety of hydrological models is currently available. Many of those employ physically based formulations to account for the complexity and spatial heterogeneity of natural processes. In turn, they require a substantial amount of spatial data, which may not always be available at sufficient quality. Recently, a top-down approach for distributed rainfall-runoff modelling has been developed, which aims at combining accuracy and simplicity. Essentially, a distributed model with uniform model parameters (base model) is derived from a calibrated lumped conceptual model. Subsequently, selected parameters are disaggregated based on links with the available spatially variable catchment properties. The disaggregation concept is now adjusted to better account for non-linearities and extended to incorporate more model parameters (and, thus, larger catchment heterogeneity). The modelling approach is tested for a catchment including several flow gauging stations. The disaggregated model is shown to outperform the base model with respect to internal catchment dynamics, while performing similarly at the catchment outlet. Moreover, it manages to bridge on average 44% of the Nash–Sutcliffe efficiency difference between the base model and the lumped models calibrated for the internal gauging stations. Nevertheless, the aforementioned improvement is not necessarily sufficient for reliable model results.

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9

Bartlett, H., and R. Whalley. "Analogue solution to the modelling and simulation of distributed-lumped parameter systems." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 212, no. 2 (March 1, 1998): 99–114. http://dx.doi.org/10.1243/0959651981539334.

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This paper presents an analogue solution to the modelling and simulation of distributed-lumped parameter systems. The solution is simple and is computationally attractive when compared with equivalent analytical approaches. To illustrate versatility two worked examples, taken from widely employed industrial applications, are presented. In the first the air flow in a long road tunnel is investigated while the second application shows the dynamical performance of a wide-faced rotor for a paper manufacturing process. The generality of the method and the industrial relevance of the proposal are demonstrated thereby.

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10

Margolis, Donald L. "A survey of bond graph modelling for interacting lumped and distributed systems." Journal of the Franklin Institute 319, no. 1-2 (January 1985): 125–35. http://dx.doi.org/10.1016/0016-0032(85)90069-9.

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11

Mattioni, Andrea, Yongxin Wu, Hector Ramirez, Yann Le Gorrec, and Alessandro Macchelli. "Modelling and control of a class of lumped beam with distributed control." IFAC-PapersOnLine 51, no. 3 (2018): 217–22. http://dx.doi.org/10.1016/j.ifacol.2018.06.057.

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12

KRYSANOVA, V., A. BRONSTERT, and D. I. MÜLLER-WOHLFEIL. "Modelling river discharge for large drainage basins: from lumped to distributed approach." Hydrological Sciences Journal 44, no. 2 (April 1999): 313–31. http://dx.doi.org/10.1080/02626669909492224.

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13

Oh, M., and C. C. Pantelides. "A modelling and simulation language for combined lumped and distributed parameter systems." Computers & Chemical Engineering 20, no. 6-7 (June 1996): 611–33. http://dx.doi.org/10.1016/0098-1354(95)00196-4.

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14

Orlikowski, Cezary, and Rafał Hein. "Modelling of Geared Multi-Rotor System." Solid State Phenomena 198 (March 2013): 669–74. http://dx.doi.org/10.4028/www.scientific.net/ssp.198.669.

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In this paper the method of modelling a speed-varying geared rotor system is presented. The proposed approach enables us to obtain an accurate low-order lumped parameter representation of the investigated system. The final model consists of reduced modal models of an undamped beam/torsional shaft system as well as a spatially lumped model of other linear and nonlinear phenomena including gear mesh interaction.

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15

Matveenko, Valerii, Maksim Iurlov, Dmitrii Oshmarin, Nataliya Sevodina, and Nataliia Iurlova. "Modelling of vibrational processes in systems with piezoelements and external electric circuits on the basis of their electrical analogue." Journal of Intelligent Material Systems and Structures 29, no. 16 (June 11, 2018): 3254–65. http://dx.doi.org/10.1177/1045389x18781025.

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The dissipative properties of electromechanical systems based on structure with elements made of piezomaterial can be controlled by attaching external electric circuits to the piezoelements. One can change electric circuit parameters in such a way as to ensure the greatest possible energy dissipation on an external electric circuit and, thereby, the best damping of the system’s specified oscillation frequency. Since the external electric circuits are a collection of elements with lumped parameters attached to a system with distributed parameters, the solution for such a system of electro-viscoelasticity problems in the complete formulation by the finite element method leads to a large solving system of algebraic equations. The solution of this system requires considerable time and computational resources. There are known approaches in mechanics that make it possible to represent mechanical systems with distributed parameters in the form of discrete systems with lumped parameters, such as a spring–mass–damper. In this article, it is proposed to model electromechanical systems with external electric circuits based on their electrical analogue in the form of equivalent electric substitution circuits, which are discrete electrical systems with lumped parameters. These discrete systems are analogues of the initial electromechanical systems in terms of frequency characteristics and the electrical processes that take place in them. The equivalent substitution circuit is based on the Van Dyke model and allows one to obtain the required number of complex eigenfrequencies of the electromechanical system under consideration.

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16

Knudsen, J., A. Thomsen, and J. Chr Refsgaard. "WATBAL." Hydrology Research 17, no. 4-5 (August 1, 1986): 347–62. http://dx.doi.org/10.2166/nh.1986.0026.

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A semi-distributed, physically based hydrological modelling system, WATBAL, which accounts for the entire land phase of the hydrological cycle is described. As compared to the two alternative hydrological model types, i.e. the traditional lumped, conceptual rainfall runoff models (STANFORD model type) and the complex, fully distributed, physically based model (SHE model type) WATBAL represents an intermediate approach. In the model, primary attention is given to the hydrological processes at the root zone level through a distributed, physically based approach whereas the groundwater processes are simulated in less details by use of a lumped, conceptual approach. This approach allows WATBAL to utilize spatially distributed input data to account for the spatial and temporal variability of meteorological conditions, vegetation and soil properties. Thus WATBAL can e.g. utilize digital satellite information as input data. WATBAL has primarily been designed as a tool for predicting the runoff from ungauged catchments and for assessing the hydrological effects of land use changes. The capability of the model for simulating ungauged catchments is tested using results from a recent feasibility study for medium size dams in Zimbabwe.

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17

Savenije, H. H. G. "<i>HESS Opinions</i> "Topography driven conceptual modelling (FLEX-Topo)"." Hydrology and Earth System Sciences Discussions 7, no. 4 (July 15, 2010): 4635–56. http://dx.doi.org/10.5194/hessd-7-4635-2010.

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Abstract. Heterogeneity and complexity of hydrological processes offer substantial challenges to the hydrological modeller. Some hydrologists try to tackle this problem by introducing more and more detail in their models, or by setting-up more and more complicated models starting from basic principles at the smallest possible level. As we know, this reductionist approach leads to ever higher levels of equifinality and predictive uncertainty. On the other hand, simple, lumped and parsimonious models may be too simple to be realistic or representative of the dominant hydrological processes. In this commentary, a new model approach is proposed that tries to find the middle way between complex distributed and simple lumped modelling approaches. Here we try to find the right level of simplification while avoiding over-simplification. Paraphrasing Einstein, the maxim is: make a model as simple as possible, but not simpler than that. The approach presented is process based, but not physically based in the traditional sense. Instead, it is based on a conceptual representation of the dominant physical processes in certain key elements of the landscape. The essence of the approach is that the model structure is made dependent on a limited number of landscape classes in which the topography is the main driver, but which can include geological, geomorphological or land-use classification. These classes are then represented by lumped conceptual models that act in parallel. The advantage of this approach over a fully distributed conceptualisation is that it retains maximum simplicity while taking into account observable landscape characteristics.

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18

Bairamov, F. D., and M. Yu Safronov. "The stability of systems with distributed parameters and lumped forces." Journal of Applied Mathematics and Mechanics 66, no. 3 (January 2002): 341–45. http://dx.doi.org/10.1016/s0021-8928(02)00043-6.

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19

Wassar, Taoufik, Matthew A. Franchek, and José A. Gutierrez. "Reduced-order modelling of transient flow in transmission lines using distributed lumped parameters." International Journal of Fluid Power 18, no. 3 (September 2, 2017): 153–66. http://dx.doi.org/10.1080/14399776.2017.1380348.

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20

Heinrich, W. "Limits of FET modelling by lumped elements." Electronics Letters 22, no. 12 (1986): 630. http://dx.doi.org/10.1049/el:19860432.

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21

Kock, A. A. A., C. P. L. Veeger, L. F. P. Etman, B. Lemmen, and J. E. Rooda. "Lumped parameter modelling of the litho cell." Production Planning & Control 22, no. 1 (December 15, 2010): 41–49. http://dx.doi.org/10.1080/09537287.2010.490016.

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22

Tang, Hui, and Shan Zhong. "Lumped element modelling of synthetic jet actuators." Aerospace Science and Technology 13, no. 6 (September 2009): 331–39. http://dx.doi.org/10.1016/j.ast.2009.06.004.

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23

Sharma, Vimal Chandra, and Satish Kumar Regonda. "Multi-Spatial Resolution Rainfall-Runoff Modelling—A Case Study of Sabari River Basin, India." Water 13, no. 9 (April 28, 2021): 1224. http://dx.doi.org/10.3390/w13091224.

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One of the challenges in rainfall-runoff modeling is the identification of an appropriate model spatial resolution that allows streamflow estimation at customized locations of the river basin. In lumped modeling, spatial resolution is not an issue as spatial variability is not accounted for, whereas in distributed modeling grid or cell resolution can be related to spatial resolution but its application is limited because of its large data requirements. Streamflow estimation at the data-poor customized locations is not possible in lumped modeling, whereas it is challenging in distributed modeling. In this context, semi-distributed modeling offers a solution including model resolution and estimation of streamflow at customized locations of a river basins with less data requirements. In this study, the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) model is employed in semi-distribution mode on river basins of six different spatial resolutions. The model was calibrated and validated for fifteen and three selected flood events, respectively, of three types, i.e., single peak (SP), double peak (DP)- and multiple peaks (MP) at six different spatial resolution of the Sabari River Basin (SRB), a sub-basin of the Godavari basin, India. Calibrated parameters were analyzed to understand hydrologic parameter variability in the context of spatial resolution and flood event aspects. Streamflow hydrographs were developed, and various verification metrics and model scores were calculated for reference- and calibration- scenarios. During the calibration phase, the median of correlation coefficient and NSE for all 15 events of all six configurations was 0.90 and 0.69, respectively. The estimated streamflow hydrographs from six configurations suggest the model’s ability to simulate the processes efficiently. Parameters obtained from the calibration phase were used to generate an ensemble of streamflow at multiple locations including basin outlet as part of the validation. The estimated ensemble of streamflows appeared to be realistic, and both single-valued and ensemble verification metrics indicated the model’s good performance. The results suggested better performance of lumped modeling followed by the semi-distributed modeling with a finer spatial resolution. Thus, the study demonstrates a method that can be applied for real-time streamflow forecast at interior locations of a basin, which are not necessarily data rich.

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24

Zhehua, Du. "Improvement of Dynamic Modelling for Single-phase Heated Tubes." E3S Web of Conferences 248 (2021): 02012. http://dx.doi.org/10.1051/e3sconf/202124802012.

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To improve the currently available multi-segment lumped parameter models, a new dynamic mathematic model for single-phase heated tubes is established by employing dynamic equations instead of the traditional static equations for calculating the heat transfer across the control volume’s tube wall. Through separating the temporal and spatial terms of the partial differential equations, and combining both lumped and analytical methods, an analytical solution for the temperature distribution of the steam and water in the tubes is derived. Then, by integrating the elemental volume equations, dynamic equations for the heat release of the tube wall are achieved. The improved model, which can be explicitly solved, is more stable and has much wider applicability. After applying the improved model to an ultra-supercritical boiler superheater, the results show that the response characteristics for inlet temperature step change are significantly improved, and the results during the puredelay periods are in accordance with those of the distributed parameter models. Compared with traditional multi-segment models, the improved model can achieve higher precision even with less segments. Besides, the transport delay characteristics of water or steam within tubes can be analyzedmore accurately with the improved model.

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25

Farshidianfar, A., M. Ebrahimi, and H. Bartlett. "Hybrid modelling and simulation of the torsional vibration of vehicle driveline systems." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 215, no. 2 (February 1, 2001): 217–29. http://dx.doi.org/10.1243/0954407011525593.

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Vehicle drivelines are lightly damped non-linear systems possessing many degrees of freedom with dynamic interactions between the various subsystems. There are many sources of excitation such as torsional impact caused by the take-up of backlash in the power train system. Such sources of excitation exist in transmission backlash, in driveline splines and in pinion to ring gear contact in the differential. Abrupt application or release of the throttle in slowly moving traffic or rapid engagement of the clutch can be followed by noise and vibration responses referred to in the industry as ‘clonk’. This paper presents a method of modelling a vehicle driveline which can identify the phenomena known as ‘clonk’ and ‘shuffle’. This model is based on the assumption that vehicle drivelines can be considered as partially lumped and partially distributed, which for systems of this type is wholly appropriate. In doing this it is possible to derive an analytical solution to the governing equations, which has not been considered previously. The results from this model are compared with a totally lumped model of the vehicle driveline for comparison.

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26

Wallner, M., U. Haberlandt, and J. Dietrich. "Evaluation of different calibration strategies for large scale continuous hydrological modelling." Advances in Geosciences 31 (September 10, 2012): 67–74. http://dx.doi.org/10.5194/adgeo-31-67-2012.

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Abstract. For the analysis of climate impact on flood flows and flood frequency in macroscale river basins, hydrological models can be forced by several sets of hourly long-term climate time series. Considering the large number of model units, the small time step and the required recalibrations for different model forcing an efficient calibration strategy and optimisation algorithm are essential. This study investigates the impact of different calibration strategies and different optimisation algorithms on the performance and robustness of a semi-distributed model. The different calibration strategies were (a) Lumped, (b) 1-Factor, (c) Distributed and (d) Regionalisation. The latter uses catchment characteristics and estimates parameter values via transfer functions. These methods were applied in combination with three different optimisation algorithms: PEST, DDS, and SCE. In addition to the standard temporal evaluation of the calibration strategies, a spatial evaluation was applied. This was done by transferring the parameters from calibrated catchments to uncalibrated ones and validating the model performance of these uncalibrated catchments. The study was carried out for five sub-catchments of the Aller-Leine River Basin in Northern Germany. The best result for temporal evaluation was achieved by using the combination of the DDS optimisation with the Distributed strategy. The Regionalisation method obtained the weakest performance for temporal evaluation. However, for spatial evaluation the Regionalisation indicated more robust models, closely followed by the Lumped method. The 1-Factor and the Distributed strategy showed clear disadvantages regarding spatial parameter transferability. For the parameter estimation based on catchment descriptors as required for ungauged basins, the Regionalisation strategy seems to be a promising tool particularly in climate impact analysis and for hydrological modelling in general.

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27

Medici, C., S. Bernal, A. Butturini, F. Sabater, A. J. Wade, and F. Frances. "Modelling the inorganic nitrogen behaviour in a small Mediterranean forested catchment, Fuirosos (Catalonia)." Hydrology and Earth System Sciences Discussions 6, no. 5 (September 4, 2009): 5665–703. http://dx.doi.org/10.5194/hessd-6-5665-2009.

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Abstract. The aim of this work was to couple a nitrogen (N) sub-model to already existent hydrological lumped (LU4-N) and semi-distributed (LU4-R-N and SD4-R-N) conceptual models, to improve our understanding of the factors and processes controlling nitrogen cycling and losses in Mediterranean catchments. The N model adopted provides a simplified conceptualization of the soil nitrogen cycle considering mineralization, nitrification, immobilization, denitrification, plant uptake, and ammonium adsorption/desorption. It also includes nitrification and denitrification in the shallow perched aquifer. We included a soil moisture threshold for all the considered soil biological processes. The results suggested that all the nitrogen processes were highly influenced by the rain episodes and that soil microbial processes occurred in pulses stimulated by soil moisture increasing after rain. Our simulation highlighted the riparian zone as a possible source of nitrate, especially after the summer drought period, but it can also act as an important sink of nitrate due to denitrification, in particular during the wettest period of the year. The riparian zone was a key element to simulate the catchment nitrate behaviour. The lumped LU4-N model (which does not include the riparian zone) could not be validated, while both the semi-distributed LU4-R-N and SD4-R-N model (which include the riparian zone) gave satisfactory results for the calibration process and acceptable results for the temporal validation process.

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28

Medici, C., S. Bernal, A. Butturini, F. Sabater, M. Martin, A. J. Wade, and F. Frances. "Modelling the inorganic nitrogen behaviour in a small Mediterranean forested catchment, Fuirosos (Catalonia)." Hydrology and Earth System Sciences 14, no. 2 (February 8, 2010): 223–37. http://dx.doi.org/10.5194/hess-14-223-2010.

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Abstract. The aim of this work was to couple a nitrogen (N) sub-model to already existent hydrological lumped (LU4-N) and semi-distributed (LU4-R-N and SD4-R-N) conceptual models, to improve our understanding of the factors and processes controlling nitrogen cycling and losses in Mediterranean catchments. The N model adopted provides a simplified conceptualization of the soil nitrogen cycle considering mineralization, nitrification, immobilization, denitrification, plant uptake, and ammonium adsorption/desorption. It also includes nitrification and denitrification in the shallow perched aquifer. We included a soil moisture threshold for all the considered soil biological processes. The results suggested that all the nitrogen processes were highly influenced by the rain episodes and that soil microbial processes occurred in pulses stimulated by soil moisture increasing after rain. Our simulation highlighted the riparian zone as a possible source of nitrate, especially after the summer drought period, but it can also act as an important sink of nitrate due to denitrification, in particular during the wettest period of the year. The riparian zone was a key element to simulate the catchment nitrate behaviour. The lumped LU4-N model (which does not include the riparian zone) could not be validated, while both the semi-distributed LU4-R-N and SD4-R-N model (which include the riparian zone) gave satisfactory results for the calibration process and acceptable results for the temporal validation process.

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29

Aime, M. L., and C. Maffezzoni. "Modelling and simulation of combined lumped and distributed systems by an object-oriented approach." Mathematics and Computers in Simulation 53, no. 4-6 (October 2000): 345–51. http://dx.doi.org/10.1016/s0378-4754(00)00226-3.

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30

Watton, J. "Modelling of Electrohydraulic Systems with Transmission Lines using Modal Approximations." Proceedings of the Institution of Mechanical Engineers, Part B: Management and engineering manufacture 202, no. 3 (August 1988): 153–63. http://dx.doi.org/10.1243/pime_proc_1988_202_063_02.

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The method of modal approximation to the distributed friction transmission line functions via frequency-domain analysis is briefly discussed. A specific form is then derived which allows time-domain analysis to be easily pursued using a digital simulation package approach. The method is applied to a highly non-linear servo-valve controlled motor system and a good comparison between experiment and theory is shown. A comparison is also made with previous work using the method of characteristics, and natural frequency predictions are also compared with some common lumped parameter approximations.

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Arjona L., M. A., and D. C. MacDonald. "Lumped modelling of open-circuit turbogenerator operational parameters." IEEE Transactions on Energy Conversion 14, no. 3 (1999): 347–53. http://dx.doi.org/10.1109/60.790881.

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Fiddes, J., and S. Gruber. "TopoSUB: a tool for efficient large area numerical modelling in complex topography at sub-grid scales." Geoscientific Model Development 5, no. 5 (October 10, 2012): 1245–57. http://dx.doi.org/10.5194/gmd-5-1245-2012.

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Abstract. Mountain regions are highly sensitive to global climate change. However, large scale assessments of mountain environments remain problematic due to the high resolution required of model grids to capture strong lateral variability. To alleviate this, tools are required to bridge the scale gap between gridded climate datasets (climate models and re-analyses) and mountain topography. We address this problem with a sub-grid method. It relies on sampling the most important aspects of land surface heterogeneity through a lumped scheme, allowing for the application of numerical land surface models (LSMs) over large areas in mountain regions or other heterogeneous environments. This is achieved by including the effect of mountain topography on these processes at the sub-grid scale using a multidimensional informed sampling procedure together with a 1-D lumped model that can be driven by gridded climate datasets. This paper provides a description of this sub-grid scheme, TopoSUB, and assesses its performance against a distributed model. We demonstrate the ability of TopoSUB to approximate results simulated by a distributed numerical LSM at around 104 less computations. These significant gains in computing resources allow for: (1) numerical modelling of processes at fine grid resolutions over large areas; (2) efficient statistical descriptions of sub-grid behaviour; (3) a "sub-grid aware" aggregation of simulated variables to coarse grids; and (4) freeing of resources for computationally intensive tasks, e.g., the treatment of uncertainty in the modelling process.

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Fiddes, J., and S. Gruber. "TopoSUB: a tool for efficient large area numerical modelling in complex topography at sub-grid scales." Geoscientific Model Development Discussions 5, no. 2 (May 2, 2012): 1041–76. http://dx.doi.org/10.5194/gmdd-5-1041-2012.

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Abstract. Mountain regions are highly sensitive to global climate change. However, large scale assessments of mountain environments remain problematic due to the high resolution required of model grids to capture strong lateral variability. To alleviate this, tools are required to bridge the scale gap between gridded climate datasets (climate models and re-analyses) and unresolved (by coarse grids) sub-grid mountain topography. We address this problem with a sub-grid method. It relies on sampling the most important aspects of land surface heterogeneity through a lumped scheme, allowing for the application of numerical land surface models (LSM) over large areas in mountain regions. This is achieved by including the effect of mountain topography on these processes at the sub-grid scale using a multidimensional informed sampling procedure together with a 1-D lumped model that can be driven by gridded climate datasets. This paper provides a description of this sub-grid scheme, TopoSUB, as well as assessing its performance against a distributed model. We demonstrate the ability of TopoSUB to approximate results simulated by a distributed numerical LSM at around 104 less computations. These significant gains in computing resources allow for: (1) numerical modelling of processes at fine grid resolutions over large areas; (2) extremely efficient statistical descriptions of sub-grid behaviour; (3) a "sub-grid aware" aggregation of simulated variables to course grids; and (4) freeing of resources for treatment of uncertainty in the modelling process.

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Koopaee, Mohammad E., Rajesh P. Dhakal, and Gregory MacRae. "Analytical simulation of seismic collapse of RC frame buildings." Bulletin of the New Zealand Society for Earthquake Engineering 48, no. 3 (September 30, 2015): 157–69. http://dx.doi.org/10.5459/bnzsee.48.3.157-169.

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Application of a fibre-element nonlinear modelling technique for seismic collapse capacity assessment of RC frame buildings in comparison with conventional lumped plasticity models is investigated in this paper. Constitutive material models of concrete and steel for fibre elements are adopted to enable simulation of the loss in vertical load carrying capacity of structural columns. Inclusion of the nonlinear second order P−Δ effects accelerated by degrading behaviour of steel and concrete materials in the fibre model allows prediction of the sidesway mode of collapse. The model is compared with nonlinear lumped plasticity models in which stiffness and strength degradation is replicated through degrading parameters in structural components. Static cyclic analyses of an example cantilever column and a portal frame indicate that the variation of axial loads in columns may result in accelerated degradation and failure of structural components which is not taken into account by lumped plasticity models. Moreover, incremental dynamic analysis of a ten-storey RC frame shows that the lumped plasticity model may overestimate building collapse capacity when vertical failure of structural components occurs prior to sidesway instability.

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Drioli, Carlo, and Philipp Aichinger. "Modelling sagittal and vertical phase differences in a lumped and distributed elements vocal fold model." Biomedical Signal Processing and Control 64 (February 2021): 102309. http://dx.doi.org/10.1016/j.bspc.2020.102309.

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Johann, Gracielle, Edson Antonio da Silva, and Nehemias Curvelo Pereira. "Modelling and optimisation of grape seed drying: Equivalence between the lumped and distributed parameter models." Biosystems Engineering 176 (December 2018): 26–35. http://dx.doi.org/10.1016/j.biosystemseng.2018.10.004.

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Bartlett, H., and R. Whalley. "Power transmission system modelling." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 212, no. 6 (June 1, 1998): 497–505. http://dx.doi.org/10.1243/0954406981521394.

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This paper employs hybrid modelling techniques in the investigation of the dynamic performance of ‘long’ driveshafts, which include a clutch and load, for power transmission purposes. The power transmission system considered is suitable for a wide variety of applications in which the load is coupled directly to the clutch and hence to the ‘long’ driveshaft. Owing to the length of the shaft and relatively pointwise location of the clutch and load, a distributed—lumped (D—L) description of the arrangement is investigated. This enables the behaviour of the dispersed driveline shaft to be ‘adequately’ replicated along with the connecting elements. A discrete modelling approach is adopted and analysis and simulated response characteristics are presented, thereby validating the technique. Existing results on clutch judder are referred to and the interaction between judder and the driveshaft torsional oscillation is commented upon.

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Kunstmann, H., A. Heckl, and A. Rimmer. "Physically based distributed hydrological modelling of the Upper Jordan catchment and investigation of effective model equations." Advances in Geosciences 9 (September 26, 2006): 123–30. http://dx.doi.org/10.5194/adgeo-9-123-2006.

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Abstract. Sufficient freshwater availability in the water scarce environment of the Upper Jordan Catchment (UJC) is a central prerequisite for peaceful agricultural and industrial development. Hydrological modelling is required to understand terrestrial water balance and to provide scientifically sound estimates on water availability. This article aims at two related objectives: First the water balance of the UJC, a hydrogeologically complex catchment located at the borders of Israel, Syria and the Lebanon, is investigated. It is for the first time that a physically based model is set up for this region that accounts both for the entire terrestrial water balance and in particular for the groundwater-surface water interaction. It is shown that the model is able to describe observed river discharges satisfactorily. Secondly, it is investigated if observed and simulated runoff components can be explained by simple lumped approaches based on 1) linear filter theory and 2) neural networks and what the number of degrees of freedom for the runoff components is. It is exemplary shown for the Ayun subcatchment of the UJC that the simulated river discharge, the direct runoff component and the interflow runoff component as modelled by the physically based distributed hydrological model WaSiM can be described by simple effective equations with only 3 to 5 degrees of freedom. Application of simple lumped approaches to observed river discharge values showed much weaker performance.

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García-Sánchez, Francisco, Beatriz Romero, Denise Lugo-Muñoz, Pozo del, Belén Arredondo, Juin Liou, and Adelmo Ortiz-Conde. "Modelling solar cell S-shaped I-V characteristics with DC lumped-parameter equivalent circuits a review." Facta universitatis - series: Electronics and Energetics 30, no. 3 (2017): 327–50. http://dx.doi.org/10.2298/fuee1703327g.

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This article reviews and appraises the dc lumped-parameter equivalent circuit models that have been proposed so far for representing some types of solar cells that can exhibit under certain circumstances a detrimental S-shaped concave deformation within the energy-producing fourth quadrant of their illuminated I-V characteristics. We first present a very succinct recollection of lumped-parameter equivalent circuits that are commonly used to model conventional solar cells in general. We then chronologically present and discuss lumped-parameter equivalent sub-circuits that, combined with conventional solar cell equivalent circuits, are used to specifically represent the undesired S-shaped behaviour. The mathematically descriptive equations of each complete equivalent circuit are also examined, and closed form solutions for the terminal current and voltage as explicit functions of each other are presented and discussed whenever available. While comparing the most salient features and explaining the practical advantages and disadvantages of such equivalent circuit models, we offer some comments on possible directions for further improvement.

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Orsino, Renato Maia Matarazzo. "Recursive modular modelling methodology for lumped-parameter dynamic systems." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 473, no. 2204 (August 2017): 20160891. http://dx.doi.org/10.1098/rspa.2016.0891.

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This paper proposes a novel approach to the modelling of lumped-parameter dynamic systems, based on representing them by hierarchies of mathematical models of increasing complexity instead of a single (complex) model. Exploring the multilevel modularity that these systems typically exhibit, a general recursive modelling methodology is proposed, in order to conciliate the use of the already existing modelling techniques. The general algorithm is based on a fundamental theorem that states the conditions for computing projection operators recursively. Three procedures for these computations are discussed: orthonormalization, use of orthogonal complements and use of generalized inverses. The novel methodology is also applied for the development of a recursive algorithm based on the Udwadia–Kalaba equation, which proves to be identical to the one of a Kalman filter for estimating the state of a static process, given a sequence of noiseless measurements representing the constraints that must be satisfied by the system.

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Casoli, Paolo, Fabio Scolari, and Massimo Rundo. "Modelling and Validation of Cavitating Orifice Flow in Hydraulic Systems." Sustainability 13, no. 13 (June 28, 2021): 7239. http://dx.doi.org/10.3390/su13137239.

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Cavitation can occur at the inlet of hydraulic pumps or in hydraulic valves; this phenomenon should be always avoided because it can generate abnormal wear and noise in fluid power components. Numerical modeling of the cavitation is widely used in research, and it allows the regions where it occurs more to be predicted. For this reason, two different approaches to the study of gas and vapor cavitation were presented in this paper. In particular, a model was developed using the computational fluid dynamics (CFD) method with particular attention to the dynamic modeling of both gaseous and vapor cavitation. A further lumped parameter model was made, where the fluid density varies as the pressure decreases due to the release of air and the formation of vapor. Furthermore, the lumped parameter model highlights the need to also know the speed of sound in the vena contracta, since it is essential for the correct calculation of the mass flow during vaporization. A test bench for the study of cavitation with an orifice was set up; cavitation was induced by increasing the speed of the fluid on the restricted section thanks to a pump located downstream of the orifice. The experimental data were compared with those predicted by CFD and lumped parameter models.

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Velázquez, J. A., J. Schmid, S. Ricard, M. J. Muerth, B. Gauvin St-Denis, M. Minville, D. Chaumont, D. Caya, R. Ludwig, and R. Turcotte. "An ensemble approach to assess hydrological models' contribution to uncertainties in the analysis of climate change impact on water resources." Hydrology and Earth System Sciences Discussions 9, no. 6 (June 12, 2012): 7441–74. http://dx.doi.org/10.5194/hessd-9-7441-2012.

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Abstract. Over the recent years, several research efforts investigated the impact of climate change on water resources for different regions of the world. The projection of future river flows is affected by different sources of uncertainty in the hydro-climatic modelling chain. One of the aims of the QBic3 project (Québec-Bavarian International Collaboration on Climate Change) is to assess the contribution to uncertainty of hydrological models by using an ensemble of hydrological models presenting a diversity of structural complexity (i.e. lumped, semi distributed and distributed models). The study investigates two humid, mid-latitude catchments with natural flow conditions; one located in Southern Québec (Canada) and one in Southern Bavaria (Germany). Daily flow is simulated with four different hydrological models, forced by outputs from regional climate models driven by a given number of GCMs' members over a reference (1971–2000) and a future (2041–2070) periods. The results show that the choice of the hydrological model does strongly affect the climate change response of selected hydrological indicators, especially those related to low flows. Indicators related to high flows seem less sensitive on the choice of the hydrological model. Therefore, the computationally less demanding models (usually simple, lumped and conceptual) give a significant level of trust for high and overall mean flows.

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O'Loughlin, Fiachra, Michael Bruen, and Thorsten Wagener. "Parameter sensitivity of a watershed-scale flood forecasting model as a function of modelling time-step." Hydrology Research 44, no. 2 (July 10, 2012): 334–50. http://dx.doi.org/10.2166/nh.2012.157.

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Although ongoing technological advances have alleviated data restrictions and most of the computational barriers to distributed modelling, lumped, parsimonious, conceptual and rainfall-runoff models are still widely used for flood forecasting. However both optimum parameter values and the fluxes of water through individual model components change significantly with the time-step used. Thus, such models should be used with caution in applications such as hydrograph separation or water quality studies that require the fluxes through individual flow routes through the model or which try to relate parameters to physical features of the catchment. To demonstrate this time-scale limitation, a parameter sensitivity analysis was performed on the lumped conceptual Soil Moisture Accounting and Routing with Groundwater component (SMARG) model for a 182 km2 rural catchment in Ireland for a number of time-steps, flow regimes and evaluation metrics. A global sensitivity analysis method (Higher Dimensional Model Representation) showed that sensitivity indices vary greatly with time-step and evaluation metric. The sensitivity of parameters also varied for different flow regimes. Certain parameters' sensitivities remain fairly constant across both flow regimes and time-step, while others are very much regime or time-step dependent. Care should be taken in using internal information from conceptual models because of this strong dependence on time-step.

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Ivanovic, A., R. D. Neilson, and A. A. Rodger. "Lumped parameter modelling of single-tendon ground anchorage systems." Proceedings of the Institution of Civil Engineers - Geotechnical Engineering 149, no. 2 (April 2001): 103–13. http://dx.doi.org/10.1680/geng.2001.149.2.103.

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Treml, Paul, Gudrun Mikota, Bernhard Manhartsgruber, and Andreas Brandl. "Modelling of a hydraulic system coupled with lumped masses." Mathematical and Computer Modelling of Dynamical Systems 28, no. 1 (July 7, 2022): 142–96. http://dx.doi.org/10.1080/13873954.2022.2080718.

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RABIE, Calal. "ABOUT THE LUMPED PARAMETER APPROACH TO HYDRAULIC LINE MODELLING." International Conference on Applied Mechanics and Mechanical Engineering 1, no. 1 (May 1, 1986): 31–46. http://dx.doi.org/10.21608/amme.1986.51797.

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Mostofi, A. "The incorporation of damping in lumped-parameter modelling techniques." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 213, no. 1 (June 1999): 11–17. http://dx.doi.org/10.1243/1464419991544018.

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Marcelli, R., G. Bartolucci, G. Minucci, B. Margesin, F. Giacomozzi, and F. Vitulli. "Lumped element modelling of coplanar series RF MEMS switches." Electronics Letters 40, no. 20 (2004): 1272. http://dx.doi.org/10.1049/el:20046490.

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Hoover, J., and S. A. Meguid. "Analytical viscoelastic modelling of whiplash using lumped-parameter approach." International Journal of Mechanics and Materials in Design 11, no. 2 (March 17, 2015): 125–37. http://dx.doi.org/10.1007/s10999-015-9306-1.

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Underwood, C. P. "An improved lumped parameter method for building thermal modelling." Energy and Buildings 79 (August 2014): 191–201. http://dx.doi.org/10.1016/j.enbuild.2014.05.001.

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