Evaluating hydrology preservation of simplified terrain representations

We present an error metric based on the potential energy of water flow to evaluate the quality of lossy terrain simplification algorithms. Typically, terrain compression algorithms seek to minimize RMS (root mean square) and maximum error. These metrics fail to capture whether a reconstructed terrain preserves the drainage network. A quantitative measurement of how accurately a drainage network captures the hydrology is important for determining the effectiveness of a terrain simplification technique. Having a measurement for testing and comparing different models has the potential to be widely used in numerous applications (flood prevention, erosion measurement, pollutant propagation, etc). In this paper, we transfer the drainage network computed on reconstructed geometry onto the original uncompressed terrain and use our error metric to measure the level of error created by the simplification. We also present a novel terrain simplification algorithm based on the compression of hydrology features. This method and other terrain compression schemes are then compared using our new metric

Role of arginase 2 in systemic metabolic activity and adipose tissue fatty acid metabolism in diet-induced obese mice

Visceral adipose tissue (VAT) inflammation and metabolic dysregulation are key components of obesity-induced metabolic disease. Upregulated arginase, a ureahydrolase enzyme with two isoforms (A1-cytosolic and A2-mitochondrial), is implicated in pathologies associated with obesity and diabetes. This study examined A2 involvement in obesity-associated metabolic and vascular disorders. WT and globally deleted A2(−/−) or A1(+/−) mice were fed either a high fat/high sucrose (HFHS) diet or normal diet (ND) for 16 weeks. Increases in body and VAT weight of HFHS-fed WT mice were abrogated in A2−/−, but not A1+/−, mice. Additionally, A2−/− HFHS-fed mice exhibited higher energy expenditure, lower blood glucose, and insulin levels compared to WT HFHS mice. VAT and adipocytes from WT HFHS fed mice showed greater A2 expression and adipocyte size and reduced expression of PGC-1α, PPAR-γ, and adiponectin. A2 deletion blunted these effects, increased levels of active AMPK-α, and upregulated genes involved in fatty acid metabolism. A2 deletion prevented HFHS-induced VAT collagen deposition and inflammation, which are involved in adipocyte metabolic dysfunction. Endothelium-dependent vasorelaxation, impaired by HFHS diet, was significantly preserved in A2−/− mice, but more prominently maintained in A1+/− mice. In summary, A2 is critically involved in HFHS-induced VAT inflammation and metabolic dysfunction

COMPUTER SIMULATION OF OVERTOPPING OF LEVEES

There have been many cases of earth embankment failures, for example, Hurricane Katrina in 2005, where breaching occurred and devastated the surrounding population. Levee failures are preventable by a better understanding of the ways in which these embankments are designed and fail. The objective of this research is to protect levees against future failures. This paper studies various overtopping quantities and durations to represent the same level of levee erosion hazard. This study is based on experimental results of steady flows on the land side of a levee. The effect of water flow has been investigated and a comparison has been done between rills formations and erosion time for various water flows. Results showed that the pictures of digital simulations and real photographs which have been taken during tests in the laboratory are in a good concordance. Ha habido muchos casos de fallos de terraplén, por ejemplo, el huracán Katrina en 2005, en el cual se produjo una ruptura, devastando la población de los alrededores. Las fallas de diques se pueden prevenir, y es un objetivo de esta investigación alcanzar una mejor comprensión de las maneras en que estos diques se diseñan y fallan, a fin de poder protegerlos contra futuros fallos. Este documento desarrolla y recomienda equivalencias preliminares de combinaciones acumulativas de varias cantidades de desbordamiento y las duraciones asociadas que representan el mismo nivel de riesgo de erosión del dique. Las metodologías se basan en los resultados experimentales de flujos constantes en el lado seco de un dique. El efecto del flujo de agua se ha estudiado específicamente en esta investigación, y se ha hecho una comparación entre las formaciones de surcos y el tiempo de erosión para distintos flujos de agua

Validation of Erosion Modeling: Physical and Numerical

The overall intent of this research is to develop numerical models of erosion of levees, dams and embankments, validated by physical models. The physical models are performed at 1-g and at high g\u27s using a geotechnical centrifuge. The erosion is modeled in detail, from beginning to end, that is from the time the levee is overtopped until the levee is breached. Typical quantities measured as a function of time are the depth, width and volume of rills, number of junction points, are the rills straight or meandering, sediment transport quantities, and finally breach. This data can be obtained from the numerical modeling, but is difficult to obtain from the physical modeling. Video images indicate the physical modeling agrees quite well with the numerical modeling. A comparison has also been done between observed breaching width and the FEMA new formula for both 1-g and centrifuge tests

Simulating Levee Erosion with Physical Modeling Validation

This paper studies rill and gully initiation and propagation on levees, dams, and general earth embankments. It specifically studies where these erosion features occur, and how long a particular embankment can sustain overtopping before breaching and catastrophic failure. This contrasts to previous levee erosion analysis, which has primarily concerned the final effects of erosion, such as soil loss, depth of scour and breach width. This paper describes the construction of scaled-down physical models of levees composed of different homogeneous sands, as well as sand-clay mixtures, and their laboratory testing. A 3-D laser range scanner captured the surface features of the physical model, before and after erosion. The resulting data is utilized in developing digital simulations of the rill erosion process. Those simulations combine 3-D Navier-Stokes fluid simulations and a segmented height field data structure to produce an accurate portrayal of the erosive processes, which will be validated by physical modeling

Measuring terrain distances through extracted channel networks

This paper initiates a forensic analysis of the causes of levee failures by analyzing and extracting information from a sequence of elevation data. This is a crucial step in bettering the design and construction of levees and dams. (Fully diagnosing failures usually requires knowledge beyond the geometry of the levee, such as weather conditions and material properties). We use results from computer simulations of levee overtopping for training data. The simulations use smoothed particle hydrodynamics coupled with a well-known erodibility model. Using the sequential nature of our data, we extract important channel networks that form as the soil is scoured away. We present a series of metrics to measure the distance between channel networks to assist in determining the critical threshold value used to extract important channels from the flow network. Methods for determining this ideal threshold have gone mainly unexplored, and so we present a comparison of various threshold values and how closely they identify matching channel networks on sequential terrains. These threshold values allow us to identify important properties of the terrain that form its fingerprint, a way of characterizing the geometry of the terrain. Our method for fingerprinting terrain is an important step toward the diagnosis of levee failure from digital elevation data

Quantitative analysis of simulated erosion for different soils

Levee overtopping can lead to failure and cause catastrophic damage, as was the case during Hurricane Katrina. We present a computer simulation of erosion to study the development of the rills and gullies that form along an earthen embankment during overtopping. We have coupled 3D Smoothed Particle Hydrodynamics with an erodibility model to produce our simulation. Through comparison between simulations and between simulation and analogous laboratory experiments, we provide quantitative and qualitative results, evaluating the accuracy of our simulation

Should Attendance Be Required in Lecture Classrooms in Dental Education? Two Viewpoints

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153624/1/jddj0022033720168012tb06236x.pd

Stream Types

We propose a rich foundational theory of typed data streams and stream transformers, motivated by two high-level goals. First, the type of a stream should be able to express complex sequential patterns of events over time. And second, it should describe the internal parallel structure of the stream, to support deterministic stream processing on parallel and distributed systems. To these ends, we introduce stream types, with operators capturing sequential composition, parallel composition, and iteration, plus a core calculus λST of transformers over typed streams that naturally supports a number of common streaming idioms, including punctuation, windowing, and parallel partitioning, as first-class constructions. λST exploits a Curry-Howard-like correspondence with an ordered variant of the Logic of Bunched Implication to program with streams compositionally and uses Brzozowski-style derivatives to enable an incremental, prefix-based operational semantics. To illustrate the programming style supported by the rich types of λST, we present a number of examples written in Delta, a prototype high-level language design based on λST