Initial tests of a new comupational linearization method

Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006. http://hdl.handle.net/1860/732The 2D shallow water equations (SWE) have been widely used in hydraulic science and engineering. Numerical discretization based on midpoint rule (e.g. leapfrog method) is desirable for 2nd order temporal accuracy. However, the explicit 3-level Leapfrog approach must be applied with appropriate strategies to decouple the known instability mode (Peyret and Taylor, 1983). In this paper, we propose a “Time-Centered, Split-Implicit” (TCSI) method based on a 2-level midpoint rule. This new method computationally linearizes the advection term such that individual solution steps are implicit and linear, but their combination is discretely equivalent to nonlinear midpoint rule discretization. To verify the capability of the new method, the 2D SWE are used to develop and test the TCSI approach. Test cases of simulating a standing wave in a closed basin are performed to examine a variety of model characteristics

Determination of selected physical and mechanical properties of Chinese jujube fruit and seed

Some of physical characteristics and mechanical properties of two widely commercialized varieties of Chinese jujube (Zizyphus jujube cv. junzao and Zizyphus jujube cv. huizao) were studied at 62.2% and 35.4% w.b. for fruits and seeds of junzao and 70.3% and 25.2% w.b. for fruits and seeds of huizao. The results showed that fruits and seeds of junzao were larger in all the dimensions and heavier than that of huizao while the fruits of junzao were smaller in true density, bulk density and porosity than that of huizao. The aspect ratio and sphericity of both cultivars fruits were spherical and more likely to roll than slide. And all the physical parameters measured and calculated of both cultivars fruits and seeds were significant different to each other. The rupture force of junzao was higher than that of huizao at both orientations under compression. Greater rupture force and higher hardness were found at the horizontal orientation of both cultivars

Two-path network with feedback connections for pan-sharpening in remote sensing

High-resolution multi-spectral images are desired for applications in remote sensing. However, multi-spectral images can only be provided in low resolutions by optical remote sensing satellites. The technique of pan-sharpening wants to generate high-resolution multi-spectral (MS) images based on a panchromatic (PAN) image and the low-resolution counterpart. The conventional deep learning based pan-sharpening methods process the panchromatic and the low-resolution image in a feedforward manner where shallow layers fail to access useful information from deep layers. To make full use of the powerful deep features that have strong representation ability, we propose a two-path network with feedback connections, through which the deep features can be rerouted for refining the shallow features in a feedback manner. Specifically, we leverage the structure of a recurrent neural network to pass the feedback information. Besides, a power feature extraction block with multiple projection pairs is designed to handle the feedback information and to produce power deep features. Extensive experimental results show the effectiveness of our proposed method

The global/local (limited to some regions) effect of cesarean delivery on the risk of pediatric allergic rhinitis: a systematic review and meta-analysis

BackgroundAllergic rhinitis is a chronic and refractory disease that can be affected by a variety of factors. Studies have shown an association between cesarean section and the risk of pediatric allergic rhinitis.MethodsThe PubMed, Springer, Embase, Cochrane Library, and Web of Science databases were searched to retrieve all studies published from January 2000 to November 2022, focusing on the relationship between cesarean section and the risk of pediatric allergic rhinitis. A meta-analysis was conducted to find a correlation between cesarean section and the risk of pediatric allergic rhinitis. A subgroup analysis was performed, considering the region and family history of allergy, after adjusting for confounding factors. Pooled odds ratios (ORs) were calculated, publication bias was assessed using a funnel plot, and heterogeneity between study-specific relative risks was taken into account.ResultsThe results showed that cesarean section was significantly associated with an increased risk of pediatric allergic rhinitis (OR: 1.27, 95% CI: 1.20–1.35). Subgroup analysis stratified by region indicated that cesarean section increased the risk of pediatric allergic rhinitis, with the highest increase in South America (OR: 1.67, 95% CI: 1.10–2.52) and the lowest in Europe (OR: 1.13, 95% CI: 1.02–1.25). The results of the subgroup analysis stratified by family history of allergy indicate that family history of allergy was not associated with the risk of pediatric allergic rhinitis.ConclusionAn association exists between cesarean section as the mode of delivery and the increased risk of pediatric allergic rhinitis, and cesarean section is a risk factor for allergic rhinitis

A time-centered split for implicit discretization of unsteady advection problems

textEnvironmental flows (e.g. river and atmospheric flows) governed by the shallow water equations (SWE) are usually dominated by the advective mechanism over multiple time-scales. The combination of time dependency and nonlinear advection creates difficulties in the numerical solution of the SWE. A fully-implicit scheme is desirable because a relatively large time step may be used in a simulation. However, nonlinearity in a fully implicit method results in a system of nonlinear equations to be solved at each time step. To address this difficulty, a new method for implicit solution of unsteady nonlinear advection equations is developed in this research. This Time-Centered Split (TCS) method uses a nested application of the midpoint rule to computationally decouple advection terms in a temporally second-order accurate time-marching discretization. The method requires solution of only two sets of linear equations without an outer iteration, and is theoretically applicable to quadratically-nonlinear coupled equations for any number of variables. To explore its characteristics, the TCS algorithm is first applied to onedimensional problems and compared to the conventional nonlinear solution methods. The temporal accuracy and practical stability of the method is confirmed using these 1D examples. It is shown that TCS can computationally linearize unsteady nonlinear advection problems without either 1) outer iteration or 2) calculation of the Jacobian. A family of the TCS method is created in one general form by introducing weighting factors to different terms. We prove both analytically and by examples that the value of the weighting factors does not affect the order of accuracy of the scheme. In addition, the TCS method can not only computationally linearize but also decouple an equation system of coupled variables using special combinations of weighting factors. Hence, the TCS method provides flexibilities and efficiency in applications.Civil, Architectural, and Environmental Engineerin

A time-centered split for implicit discretization of unsteady advection problems

Center for Research in Water Resource