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A simple analytical model was developed for evaluating the attenuation of flood wave peak discharge. The physically‐based model represents the flood wave along its trajectory, based on the diffusive model. Relative peak discharge decreases along the downstream distance according to a power function. The distance is scaled by the attenuation factor related to river hydrodynamics (flow rating, hydraulic diffusivity, celerity, and floodplain storage) and input hydrograph (initial peak discharge, hydrograph volume, and its relative curvature). It also informs the attenuation length, which is a practical indicator of the river distance in which discharge decreases by a given factor. Sensitivity analyses indicate that initial peak discharge, volume, floodplain storage, and slope are the governing factors of attenuation. Model's validity and accuracy were demonstrated by reproducing data from (a) numerical solutions of the Saint‐Venant equations covering a wide range of conditions, (b) 29 observations from 11 historical dam‐breaks, (c) 15 observations of natural floods in seven rivers and (d) a detailed hydrodynamic model. The model errors were generally lower than 10% and not larger than the typical uncertainty of flood observations. The accuracy is higher than simplified empirical models and analogous to a detailed hydrodynamic model that is representative of current practice. The proposed flood attenuation model can be easily applied using a few common parameters and a simple equation in a basic spreadsheet. It is suitable for practical applications such as first assessments of natural and dam‐break floods, engineering design, and analyses of large river networks supported by remote sensing data. Plain Language Summary Floods are the most common and damaging natural disaster. Predicting how flood waves weaken while traveling along rivers is key to clarifying the risks of natural and dam‐break floods, in engineering design, reservoir operation, and environmental analysis. We developed a simple and innovative physical model of flood wave attenuation. This model was accurate when tested against observations from historical dam‐break and natural floods and sophisticated computer simulations covering a wide range of river types and flow conditions. Flood waves weaken more when their peak is large, their volume is low, and in low‐slope rivers with large floodplains. This simple and meaningful equation can be easily applied for practical applications and help with massive mapping of floods over large regions. Key Points A simple physically‐based analytical model of flood wave peak attenuation is developed The model is validated using numerical solutions of the Saint‐Venant equations and observations of historical dam breaks and natural floods Flood wave attenuation is governed mostly by initial peak discharge, volume, floodplain storage, and river slope

Fractures provide pathways for preferential flow, whereas porous rock acts as storage that delays fluid propagation through matrix imbibition. These dual‐porosity mechanisms are investigated in laboratory experiments of partially saturated fracture infiltration. We analyze flow dynamics in terms of the fluid penetration depth in the fracture and delineate fracture‐ and matrix‐dominated flow regimes at different flow rates. We compare wetting front propagation in fracture and matrix and examine the interference of matrix‐wetting fronts with the lateral system boundary. The experimental data are interpreted using the analytical model of Nitao (1991), which accounts for the impact of fracture‐matrix interactions on fluid propagation in the fracture. We find that matrix imbibition affects the observed discontinuous, partially saturated fracture flow to behave, on average, like plug flow. Consequently, and within the range of applied flow rates above a critical threshold, the model’s plug flow assumption is not a relevant precondition for its applicability. Fluid propagation in the fracture exhibits three characteristic scaling regimes (FP1‐3) corresponding to the matrix imbibition state. Only two scaling regimes are established for flow rates below a critical threshold, hence required to recover bulk infiltration for the chosen geometry. Furthermore, wetting fronts switch from fracture‐to matrix‐dominated at moderate to high flow rates, indicating a flow‐rate‐dependent limitation of fracture‐dominated infiltration depth. While the scaling regimes agree with experiments for applied flow rates above the critical threshold, the model underestimates the initial penetration depth below. Here, we observe the direct onset of flow regime FP2 and the delayed transition into FP3. Key Points Laboratory experiments of infiltration dynamics in a vertical fracture between two sandstone blocks are compared to analytical solutions Complex fracture flow dynamics can be simplified as plug flow due to the strong effects of matrix imbibition during the wetting process Above critical inflow rates, only two of three conceptual flow periods are required to recover bulk infiltration in our experiments

This paper, presents a simplified analytical modeling approach to determine the structural behavior of historical buildings. Analytical modeling is a digital tool for determining the behavior of masonry buildings under the influence of dynamic and static loads. In the analytical modeling process, different types of elements are involved to represent buildings. Due to the complex geometrical features of historical buildings, it is significant to the preference for convenient elements. Mardin Great Mosque was discussed and analyzed for the selection of convenient element preferences. Three different mosque models were built and analyzed by using three different element types (frame, shell, solid).  In the findings of the paper, the values at the same points on the models were compared. When the first natural vibration period was examined, the first model is 0.76sec, the second model is 0.76sec, and the third model is 0.71sec. In addition, considering the base shear under dead load, 98.35% similarity was observed. As a consequence of the geometrical features of historical buildings, inappropriate definitions and inconvenient element preferences emerge the results questionable. Therefore, to be able to manage the analytical modeling process effectively requires accurate and appropriate definitions of the elements to be preferred.

Interior permanent magnet (IPM) machines with hairpin windings have attracted significant attention in EV applications owing to their low DC resistance and excellent thermal capabilities. In this paper, we present a comprehensive investigation of AC winding losses in IPM machines for traction applications, including analytical modeling, the influence of design parameters, and finite element (FE) verification. The proposed analytical model can predict the trends in AC winding losses for any number of bar conductors and slot/pole combinations. The results of the parametric study, obtained via the analytical model, are presented to examine the effects of key design parameters, such as conductor width and height, phase arrangement, and slot-per-pole-per-phase (SPP). To incorporate more practical issues into the analysis of IPM machines with hairpin windings, extensive FE simulations were conducted. The results indicated that the AC winding losses decrease with an increasing number of conductor layers and phases inside the slot.

In a channel confluence, different hydrodynamic characteristics can significantly affect the flow structure. As the main and tributary flow converges at the confluence, they are constrained by the recirculation zone, resulting in streamline contraction and an increase in flow velocity, thereby creating a zone of maximum velocity adjacent to the maximum width of the recirculation zone. The maximum flow velocity governs pollutant transport about a confluence and also influences bed erosion; thus, an accurate determination of the maximum flow velocity is crucial. In the present study, a statistical methodology was applied to validate the feasibility of substituting the maximum flow velocity at the widest section of the recirculation zone with the longitudinal maximum flow velocity. Two distinct models were formulated to address the transition between two mixing modes in the shear layer. In the wake mode, the two‐control volume approach was applied, using the lowest velocity within the shear layer as a boundary to partition the contracted flow into two control volumes. In the mixing‐layer mode, the contracted flow was treated as a single control volume. Those semi‐analytical models were validated using 3D numerical results and experimental data collected in laboratory‐scale confluence. The validation results demonstrate that both the proposed models could be applied to their respective shear layer modes to accurately predict the maximum longitudinal flow velocity.

The use of granular jamming is proposed for designing structures with tunable rigidity of their tools (with the ability of being flexible devices for shaping and deformation but rigid for shape-locking and force transmission). The granular jamming consists in modifying the apparent rigidity of a structure by controlling the vacuum in a membrane filled with granular material. When the difference of pressure is low, the grains are free to move with respect to each other and the structure is flexible. When the vacuum in the membrane is increased, the grains are blocked and the structure is more rigid. Different mechanical characterizations of the granular jamming have been performed (triaxial compression and tension and cantilever beam bending tests) for different glass bead sizes ranging between 100 μm and 1 mm (used as granular material) at different vacuum levels (between 0 kPa and 90 kPa). The grain size slightly influences the stiffness while the pressure difference is the main parameter to tune the stiffness of the structure. Based on these experiments, analytical models have been developed and validated. The tension characteristics can be directly deduced from the compression behavior and the bending modulus can be obtained by a combination of the tension and compression moduli. The proposed analytical models present the advantage of a simple formulation and are suitable for estimating the performance of other structures based on the granular jamming. The models can estimate and predict satisfactorily the results of granular jamming and can be used for designing mechanical structures based on this mechanism.

Hybrid floors infilled with polymeric materials between two steel plates were developed as a prefabricated floor system in the construction industry. However, the floor’s fire resistance performance has not been investigated. To evaluate this, fire tests suggested by the Korean Standards should be performed. As these tests are costly and time consuming, the number of variables were limited. However, many variables can be investigated in other ways such as furnace tests and finite element analysis (FEA) with less cost and time. In this study, furnace tests on heated surface areas smaller than 1 m2 were conducted to investigate the thermal behavior of the hybrid floor at elevated temperatures. To obtain the reliability of the proposed thermal behavior analytical (TBA) model, verifications were conducted by FEAs. Thermal contact conductance including interfacial thermal properties between two materials was adopted in the TBA model, and the values at elevated temperatures were suggested based on thermo-gravimetric analyses results and verified by FEA. Errors between the tests and TBA model indicated that the model was adequate in predicting the temperature distribution in small-scale hybrids. Furthermore, larger furnace tests and analysis results were compared to verify the TBA model’s application to different sized hybrid floors.

Xu, Y.; Zhang, W.; Chen, X.; Zheng, J.; Chen, X., and Wu, H., 2015. Comparison of analytical solutions for salt intrusion applied to the Modaomen Estuary. Salt intrusion in estuaries is an urgent environmental challenge across the world, because salinity influences water quality. The Modaomen Estuary is the main source of freshwater supply in the economically advanced Pearl River Delta, and it is experiencing a salt intrusion problem. Analytical models of salinity variation offer a simple and efficient approach to studying salt intrusion in estuaries. In this paper, two analytical models used worldwide to assess salinity variation in alluvial estuaries are applied to the Modaomen Estuary. The models are derived from salt convection-dispersion equations, with different assumptions for the dispersion coefficient. The performance of these two models was evaluated by comparing their results with field measurements; this revealed that both analytical models apply well to both the estimation of salinity distribution and the prediction of salt intrusion in the Modaomen Estuary. One model agrees more with the field measurements of salinity distribution along the estuary; the second better predicts salt intrusion length.

Printed antennas have played a key role in the quantum leap of portable electronics and communication technology due to their size, robustness and durability. Soft-computational optimization of printed antennas is an emerging trend in antenna design. These methods help in the rapid development of optimized antennas to meet the demands of fast-changing technologies. The geometrical parameters of an antenna are tuned iteratively using an optimization algorithm to best fit the desired performance of an antenna. The use of high-fidelity full-wave simulation is computationally expensive for such iterative evaluation. Low-fidelity surrogate models are viewed as a solution to this problem. This paper reviews some recent works where analytical antenna models are used as surrogate models for soft-computational optimization. Several traditional and modern methods for the analytical modeling of antennas are also reviewed. The analytical models are broadly classified into five categories—traditional analytical methods, antennas modeled as filters, analytical equivalent circuit models, cascade form of analytical equivalent circuit models and computer-aided design of equivalent circuit models. Traditional analytical methods and analytical equivalent circuit models provide higher insights into the working of the antennas. Modeling antennas as filters often result in higher accuracy but limited insights into how the antenna works. The hybrid approach may be viewed as a balance between the two. The computer-aided approach helps in enhancing the accuracy of equivalent circuit models. Examples from each category are reviewed, and they are evaluated based on their applicability in surrogate models.

At river confluences, the complex hydrodynamics result in significant alterations to flow structures, and the maximum velocity zone serves as one of the primary drivers of pollutant transport and riverbed erosion. This study investigates maximum longitudinal velocity formation in fully ice‐covered confluences, statistically validating the substitution of depth‐averaged maximum longitudinal velocity at the widest recirculation section for depth‐averaged maximum longitudinal velocity. In this study, a semi‐analytical model is developed to address transitional shear layer modes: (a) wake mode employing dual control volumes, and (b) mixing layer mode treating converging flow as a single control volume. The momentum equation incorporating secondary flow effects predicts maximum depth‐averaged velocities, verified against 3D simulations and experimental data with mean errors below 0.42%. Results confirm both models accurately predict velocities within their respective flow regimes, providing the first mechanistic framework for ice‐covered confluence hydrodynamics.