Hydraulic Model Study of Waller Creek Tunnel Project for the City of Austin, Texas

This report provides the results of a series of model tests designed to understand the fluid dynamics involved with the Waller Creek Tunnel.Waller Creek is centrally located within the City of Austin, Texas, and has one of the most densely developed watersheds in the locality. The main stem is approximately seven miles in length and generally flows from north to south. The total drainage area for Waller Creek is 5.74 square miles (3700 acres) and the watershed lies entirely within the jurisdictional boundaries of the City of Austin and Travis County as shown in Figure 1 and Figure 2. Flood impacts to development adjacent to the creek have been a concern since the area was developed in the 1950’s. Central Texas (including the City of Austin) is prone to flooding, especially in creeks with highly impervious watersheds. The Waller Creek Tunnel Project (WCTP) will reduce the threat of flood damages to existing infrastructure and development, along the Lower Reach of Waller Creek. In addition to flood control, the proposed design will improve water quality, create ecological benefits, mitigate erosion problems, and provide safety to individuals and businesses located in the downtown Austin Waller Creek area. At the request of Crespo Consulting Service Inc., Austin, Texas (Crespo), Alden Research Laboratory (Alden) conducted a hydraulic model study using Computational Fluid Dynamics (CFD) and physical model studies for the proposed WCTP for the City of Austin, Texas. The objective of the study included evaluation of the flow patterns approaching and in the various hydraulic structures. Additionally, the model study was used to: Establish a rating curve for the morning glory spillway, Evaluate the potential air entrainment in the tunnel and the need for any air bleed structures, Establish junction loss coefficients for the 4th Street and 8th Street lateral junctions, Determine the fluctuating pressures due to flow induced excitations at the tunnel portal to the recirculation pump intake when the valve is closed and, Obtain a rating curve for the outlet spillway/weir. Inlet CFD Model -A CFD model of the inlet at Waterloo Park was used to design and evaluate the approach channel geometry, training wall and bar screens. The intake structure is comprised of a morning glory type inlet and includes six bar screen type trash racks which remove a portion of any debris before entering the vertical drop shaft and the underground tunnel. A training wall was designed to improve flow distribution approaching the structure. Model results show that 80% of the bar screen area has a velocity of less than 4 ft/s. The maximum velocity at any location on the screens is less than 5.5 ft/s. To address concerns that debris may accumulate along the training wall, modifications were made to fill in the backside of the barbs (the barbs were developed as part of the design to improve flow distribution and conditions at the screens). With the modifications the model results show that two screens did not have 80% of the bar screen area velocities of less than 4 ft/s and one screen exceeded the 50 % flow variation from the target flow. The final alternative was evaluated in the physical model. Lateral Junction CFD Models - Lateral junctions at 4th Street and 8th Street were evaluated using CFD models. The models were used to simulate flow conditions where the lateral flow is relatively large and the main conduit flow is relatively small. This condition results in the largest impact of the lateral junctions on the main conduit flow. Model results showed that the lateral junctions are not predicted to cause significant flow separations in the main conduit and cavitation potential is small. Outlet CFD Model -A CFD model of the outlet structure was used to design the riser shaft from the tunnel to the surface, and a flip bucket at the toe of the spillway. Based on the CFD model results, Outlet connection 2 as shown in Figure 17 was selected. The final structure design, based on CFD results, shows uniform flow distribution over the spillway. The flip bucket at the toe of the dam decreased the water velocity near the bed of the discharge channel as compared to a no flip bucket condition. Water velocity near the end of the spillway with the 2.25 ft high flip bucket is not predicted to erode the spillway apron. Inlet/Tunnel/Lateral Junctions/Outlet Physical Model - A 1:33 scale model of the Inlet, Tunnel, Lateral Junctions and Outlet of the Waller Creek Tunnel Project was constructed at Alden. The design flow for the model to simulate the friction losses and the expected Hydraulic Gradient Line (HGL) along the tunnel corresponded to the 100 year flood flow. The rating curves for the inlet spillway and outlet weir and the closed conduit flow loss coefficients for tunnel junctions were obtained from the model by testing a range of flows, as they were not affected by the tunnel HGL. Upon initial model start up, air entrainment at the morning glory vertical shaft was observed. The measured average Volume Fraction of air (VFa) in the model was about 5% for 25 year flow and 4% for the 100 year flow. Maximum Volume Fraction of air (VFa) in the model for the 25 year and 100 year flows were 8% and 6%, respectively. The volume fractions obtained from the model data could be corrected for any scale effects on generation of air entrainment using correction factors available in the literature. Also, as the Volume Fraction of air, VFa, can be a function of pressure and temperature, corrections need to be applied taking into account the expected pressure (from HGL calculations) and temperature in the field. The morning glory rating curve (Figure 64) was established in the physical model using inlet flows for the 2, 5, 10, 25, 50, 100 and 500 peak tunnel/ peak intervening events. During the 500 year event the morning glory spillway was submerged and an air drawing free-surface vortex was observed however it should be noted that 1) the building operations deck, which could interfere with vortex formation, was not included in the model and 2) the emergency spillway was not modeled which would result in lower water levels for the 500 yr event. Data was also recorded for two additional flows to determine the point at which the inlet weir becomes drowned out (approximately at a flow of 9,950 cfs at EL 483.2 ft water level). For the 100 year peak inlet flow condition (8,247 cfs) the average HGL was increased in the inlet shaft to above the morning glory crest elevation (474.0 ft) to elevations 478.2 and 479.7 ft to determine any effect on the inlet rating curve. For these submerged conditions, no change in the head on the morning glory spillway was observed. Therefore, the inlet rating curve is hydraulically disconnected from the inlet shaft tailwater up to at least 479.9 ft. Testing was conducted to determine any fluctuating pressures due to flow induced excitations at the tunnel portal to the recirculation pump intake when the valve is closed using the 100 year peak tunnel/ peak intervening condition. A plot of the prototype pressure versus time fluctuation referenced to EL 427 ft is included in Figure 65. The predicted maximum, minimum and average pressures were 16.9, 15.5 and 13.4 psi, respectively. This range of fluctuating pressure was not of concern to the JV in terms of design criteria for the valve. Tests were conducted using the model to determine the Minor Losses and corresponding junction Loss Coefficients at the 8th Street and 4th Street lateral junctions and the tunnel (tees combining main flow in the tunnel with flow from side inlet weir branch). Results indicating the Loss Coefficients determined from the model for the 100 year flood for both Peak Tunnel-Peak Intervening and Lagging Tunnel-Peak Intervening are shown below: 100 yr Peak Tunnel-Peak Int. 100 yr Lagging Tunnel-Peak Int. Loss Coefficient 8th St. 4th St. 8th St. 4th St. Tunnel: K2-3 0.3 0.2 0.3 0.3 Branch: K1-3 -0.6 -0.7 -0.4 -0.4 The branch loss coefficients (K1-3) are negative due to transfer of energy from the through flow in the tunnel to the flow from the branch as the branch flow is only about 10% or so of the tunnel flow. The outlet spillway rating curve was also established in the physical model using inlet flows for the 2, 5, 10, 25, 50, 100 and 500 year peak tunnel/ peak intervening events. The outlet spillway rating curve is shown in Figure 70.Waller Creek Working Grou

AdaVis: Adaptive and Explainable Visualization Recommendation for Tabular Data

Automated visualization recommendation facilitates the rapid creation of effective visualizations, which is especially beneficial for users with limited time and limited knowledge of data visualization. There is an increasing trend in leveraging machine learning (ML) techniques to achieve an end-to-end visualization recommendation. However, existing ML-based approaches implicitly assume that there is only one appropriate visualization for a specific dataset, which is often not true for real applications. Also, they often work like a black box, and are difficult for users to understand the reasons for recommending specific visualizations. To fill the research gap, we propose AdaVis, an adaptive and explainable approach to recommend one or multiple appropriate visualizations for a tabular dataset. It leverages a box embedding-based knowledge graph to well model the possible one-to-many mapping relations among different entities (i.e., data features, dataset columns, datasets, and visualization choices). The embeddings of the entities and relations can be learned from dataset-visualization pairs. Also, AdaVis incorporates the attention mechanism into the inference framework. Attention can indicate the relative importance of data features for a dataset and provide fine-grained explainability. Our extensive evaluations through quantitative metric evaluations, case studies, and user interviews demonstrate the effectiveness of AdaVis

Predicting the response of three common subtropical tree species in China to climate change

IntroductionClimate is crucial factor influencing species distribution, and with global climate change, the potential geographic distribution of species will also alter. In this study, three subtropical tree species (Cunninghamia lanceolata, Pinus taiwanensis, and Quercus glauca) of great ecological values were selected as research objects.MethodsWe applied a maximum entropy (MaxEnt) to predict their potential distributions under different climate scenarios in both present and future conditions based on 37 environmental factors. Jackknife test was used in key factors affecting species distribution. In addition, we explored the key environmental variables that affect their distributions and revealed the evolutionary patterns and migration trends of these tree species under future climate.ResultsThe main findings are as follows: (1) Winter temperature, winter precipitation, and annual temperature range are identified as the key environmental variables affecting the potential geographic distribution of the three tree species; moreover, precipitation-related factors have a greater impact than temperature-related factors; (2) Currently suitable habitats for these three tree species are primarily located in subtropical China with decreasing suitability from south to north; (3) Under future climate conditions, the area of potentially suitable habitat for C. lanceolata continues to expand, while P. taiwanensis and Q. glauca tend to experience a reduction due to increasing greenhouse gas emissions over time; and (4) The centroid of suitable habitat for C. lanceolata shifts northward under future climate change, while the centroid of P. taiwanensis and Q. glauca move southward along with shrinking suitable habitat area.DiscussionOur predictions highlight a high risk of habitat loss of Q. glauca under climate change, recommending management and conservation references for these three commonly used afforestation species under current and future climate change scenarios in China

Modelacao tridimensional do escoamento em captacoes de agua

This research is motivated by the need to advance the state of the art in CFD modeling of water pump intake flows and reach a model that can be applied to intake problems of any geometry. A simple intake model was first selected for validation of the selected CFD model U"2 Rans, currently under development at the University of Iowa (USA). Qualitative and quantitative comparisons were made regarding free and sub surface vortices, with experimental data and previous numerical results. A second intake model with pump bell was chosen for further validation. Numerical results were compared with the experimental data, under "No Cross Flow" and "Cross Flow", and "Zero" and "Finite" pipe wall thickness. Finally, U"2 Rans was applied to a real world intake. Comparisons were made between the numerical results and experimental observations. A sensitivity analysis was performed on the influence of the inlet flow and pump bell shape. GRIDGEN, a leading grid generator package, was used throughout this research. The study was successful in a first attempt to simulate pump bell and pipe wall thickness, and to advance a CFD model to a real world water pump intake with practical geometry. The results further indicate the reliability of U"2 Rans as a cost effective tool for water pump intake designAvailable from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1249-074 Lisboa, Portugal / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga

AdaVis: Adaptive and explainable visualization recommendation for tabular data

Ministry of Education, Singapore under its Academic Research Funding Tier

Effect of Cold Stress on Growth, Physiological Characteristics, and Calvin-Cycle-Related Gene Expression of Grafted Watermelon Seedlings of Different Gourd Rootstocks

Recently, grafting has been used to improve abiotic stress resistance in crops. Here, using watermelon ‘Zaojia 8424’ (Citrullus lanatus) as scions, three different gourds (Lagenaria siceraria, 0526, 2505, and 1226) as rootstocks, and non-grafted plants as controls (different plants were abbreviated as 0526, 2505, 1226, and 8424), the effect of cold stress on various physiological and molecular parameters was investigated. The results demonstrate that the improved cold tolerance of gourd-grafted watermelon was associated with higher chlorophyll and proline content, and lower malondialdehyde (MDA) content, compared to 8424 under cold stress. Furthermore, grafted watermelons accumulated fewer reactive oxygen species (ROS), accompanied by enhanced antioxidant activity and a higher expression of enzymes related to the Calvin cycle. In conclusion, watermelons with 2505 and 0526 rootstocks were more resilient compared to 1226 and 8424. These results confirm that using tolerant rootstocks may be an efficient adaptation strategy for improving abiotic stress tolerance in watermelon

The Complete Chloroplast Genome of Carya cathayensis and Phylogenetic Analysis

Carya cathayensis, an important economic nut tree, is narrowly endemic to eastern China in the wild. The complete cp genome of C. cathayensis was sequenced with NGS using an Illumina HiSeq2500, analyzed, and compared to its closely related species. The cp genome is 160,825 bp in length with an overall GC content of 36.13%, presenting a quadripartite structure comprising a large single copy (LSC; 90,115 bp), a small single copy (SSC; 18,760 bp), and a pair of inverted repeats (IRs; 25,975 bp). The genome contains 129 genes, including 84 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. A total of 252 simple sequence repeats (SSRs) and 55 long repeats were identified. Gene selective pressure analysis showed that seven genes (rps15, rpoA, rpoB, petD, ccsA, atpI, and ycf1-2) were possibly under positive selection compared with the other Juglandaceae species. Phylogenetic relationships of 46 species inferred that Juglandaceae is monophyletic, and that C. cathayensis is sister to Carya kweichowensis and Carya illinoinensis. The genome comparison revealed that there is a wide variability of the junction sites, and there is higher divergence in the noncoding regions than in coding regions. These results suggest a great potential in phylogenetic research. The newly characterized cp genome of C. cathayensis provides valuable information for further studies of this economically important species

Multi-Channel Blind Restoration of Mixed Noise Images under Atmospheric Turbulence

The imaging quality of astronomical or space objects is significantly degraded by atmospheric turbulence, photon noise, image sensor noise, and other factors. A multi-channel alternating minimization (MCAM) method is proposed to restore degraded images, in which multiple blurred images at different times are selected, and the imaging object and the point spread function are reconstructed alternately. Results show that the restoration index can converge rapidly after two iterations of the MCAM method when six different images are adopted. According to the analysis of the structure similarity index, the stronger the influence of turbulence and mixed noise, the higher the degree of image improvement. The above results can provide a reference for blind restoration of images degraded by atmospheric turbulence and mixed noises

KG4Vis: A knowledge graph-based approach for visualization recommendation

Visualization recommendation or automatic visualization generation can significantly lower the barriers for general users to rapidly create effective data visualizations, especially for those users without a background in data visualizations. However, existing rule-based approaches require tedious manual specifications of visualization rules by visualization experts. Other machine learning-based approaches often work like black-box and are difficult to understand why a specific visualization is recommended, limiting the wider adoption of these approaches. This paper fills the gap by presenting KG4Vis, a knowledge graph (KG)-based approach for visualization recommendation. It does not require manual specifications of visualization rules and can also guarantee good explainability. Specifically, we propose a framework for building knowledge graphs, consisting of three types of entities (i.e., data features, data columns and visualization design choices) and the relations between them, to model the mapping rules between data and effective visualizations. A TransE-based embedding technique is employed to learn the embeddings of both entities and relations of the knowledge graph from existing dataset-visualization pairs. Such embeddings intrinsically model the desirable visualization rules. Then, given a new dataset, effective visualizations can be inferred from the knowledge graph with semantically meaningful rules. We conducted extensive evaluations to assess the proposed approach, including quantitative comparisons, case studies and expert interviews. The results demonstrate the effectiveness of our approach.Comment: 11 pages, 8 figures. IEEE Transactions on Visualization and Computer Graphics (Proceedings of IEEE VIS 2021