In double sandbar systems, the alongshore variability in the inner bar often resembles that of the outer bar, suggesting that the outer bar acts as a morphological template for the inner bar. Earlier observations have...
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In double sandbar systems, the alongshore variability in the inner bar often resembles that of the outer bar, suggesting that the outer bar acts as a morphological template for the inner bar. Earlier observations have indicated that this resemblance, also termed coupling, may take several forms. Here we apply a nonlinear 2DH morphodynamic model with time-invariant forcing to show that the angle of wave incidence () is crucial for the alongshore-variable morphodynamic evolution of the inner bar, for a given crescentic outer bar. In contrast to previous modeling efforts of double-barred systems, which mostly used highly idealized boundary conditions, we force our model with realistic hydrodynamics and bathymetrical data derived from video observations at the double-barred Gold Coast, Australia. The results show that for small angles of wave incidence (<10 degrees) over a crescentic outer-bar, cell-circulation patterns govern the flow at the inner bar, giving rise to rip channels that incise the inner bar at the locations of the landward perturbations in the outer bar (horns). On the other hand, for obliquely incident waves (=10 degrees-20 degrees) over a crescentic outer bar, the circulatory nature of the flow disappears and gives way to a meandering alongshore current. The offshore-directed sections of this meandering alongshore current erode the inner-bar downdrift of the outer-bar horns, leading to landward perturbations of the inner bar that are coupled to the outer-bar horns;an observed coupling type that had not been reproduced as yet. Oblique wave incidence thus proves to be crucial to the development of this type of sandbar coupling, as previously hypothesized from sandbar-coupling observations at the Gold Coast. Additional simulations including tidal water level variations and bar depth variations demonstrate the robustness of our findings.
In our former work [Catal. Today 174 （2011） 127], 12 heterogeneous catalysts were screened for CO oxidation, and Au-ZnO/Al2O3 was chosen and optimized in terms of weight loadings of Au and ZnO. The present study fol...
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In our former work [Catal. Today 174 （2011） 127], 12 heterogeneous catalysts were screened for CO oxidation, and Au-ZnO/Al2O3 was chosen and optimized in terms of weight loadings of Au and ZnO. The present study follows on to consider the impact of process parameters （catalyst preparation and reaction conditions）, in conjunction with catalyst composition （weight loadings of Au and ZnO, and the total weight of the catalyst）, as the optimization of the process parameters simultaneously optimized the catalyst composition. The optimization target is the reactivity of this important reaction. These factors were first optimized using response surface methodology （RSM） with 25 experiments, to obtain the optimum： 100 mg of 1.0%Au-4.1%ZnO/Al2O3 catalyst with 220℃ calcination and 100℃ reduction. After optimization, the main effects and interactions of these five factors were studied using statistical sensitivity analysis （SA）. Certain observations from SA were verified by reaction mechanism, reactivity test and/or characterization techniques, while others need further investigation.
The purpose of this paper is to find the way how to distribute the number of escalators which are up and down among the escalator group according to the curve of crowd. Under the circumstances where there are both...
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The purpose of this paper is to find the way how to distribute the number of escalators which are up and down among the escalator group according to the curve of crowd. Under the circumstances where there are both upstream and downstream of the crowd, the passenger transport model is established based on the sampled data and the problem of the number distribution of the escalators is solved in the sense of zero-sum game. The simulation results demonstrate the rationality and effectiveness of the proposed method.
The purpose of this lecture is to display recent results concerning the relation between discrete, continuous, and data-based population models. The lecture is organized as follows: ( 1) we begin by motivating why dis...
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The purpose of this lecture is to display recent results concerning the relation between discrete, continuous, and data-based population models. The lecture is organized as follows: ( 1) we begin by motivating why discrete models are used, under what circumstances, and for what purposes. ( 2) It is not obvious how discrete models should be derived and we show how discrete models are derived in our case. ( 3) We continue by discussing the relation between continuous and discrete models and their dynamical analogies. ( 4) We end up by discussing possible problems that appear as models fitted to data are used for making conclusions regarding its long-term behavior. (C) 2009 Elsevier Ltd. All rights reserved.
The spatiotemporal temperature distribution in the imperfectly mixed airspace around plants has a considerable effect on the physiological plant processes. In a fully instrumented climate chamber, eight identification...
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The spatiotemporal temperature distribution in the imperfectly mixed airspace around plants has a considerable effect on the physiological plant processes. In a fully instrumented climate chamber, eight identification experiments were carried out to model the spatiodynamic temperature response around plants to variations in the supply air temperature and the sensible heat, produced by the lamps (directly related to the light intensity), as control inputs. From the experimental data, a minimally parameterized, linear, discrete-time transfer function matrix (TFM) model was identified, capturing the dominant model behavior of the dynamic process. based on statistical considerations, a first-order TFM model came out as the best model structure. The first-order model provided a good compromise between goodness of fit (minimum Rt(i)(2) of 0.91) and parametric efficiency (standard error), characterized the airflow behavior very well, and formed an adequate basis for model-based process control.
PID controllers have been widely employed for industrial processes. Although most process systems have nonlinear properties, the effective PID parameters tuning method for nonlinear systems have not been established y...
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PID controllers have been widely employed for industrial processes. Although most process systems have nonlinear properties, the effective PID parameters tuning method for nonlinear systems have not been established yet. Therefore, in this paper, a new tuning method of PID parameters is proposed for nonlinear systems using the idea of a data-based modeling method. According to the proposed method, PID parameters can be adequately tuned by input/output data of the controlled object stored recursively in the data-base. Finally, this method is experimentally evaluated on a temperature control system.
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