Influence of Cohesion on Bed Load Transport of Bimodal Sediments

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Erosion characteristics of cohesive sediment mixtures

River morphodynamics and sediment transportMechanics of sediment transpor

CRUSH4SQL: Collective Retrieval Using Schema Hallucination For Text2SQL

Existing Text-to-SQL generators require the entire schema to be encoded with the user text. This is expensive or impractical for large databases with tens of thousands of columns. Standard dense retrieval techniques are inadequate for schema subsetting of a large structured database, where the correct semantics of retrieval demands that we rank sets of schema elements rather than individual elements. In response, we propose a two-stage process for effective coverage during retrieval. First, we instruct an LLM to hallucinate a minimal DB schema deemed adequate to answer the query. We use the hallucinated schema to retrieve a subset of the actual schema, by composing the results from multiple dense retrievals. Remarkably, hallucination \unicode{x2013} generally considered a nuisance \unicode{x2013} turns out to be actually useful as a bridging mechanism. Since no existing benchmarks exist for schema subsetting on large databases, we introduce three benchmarks. Two semi-synthetic datasets are derived from the union of schemas in two well-known datasets, SPIDER and BIRD, resulting in 4502 and 798 schema elements respectively. A real-life benchmark called SocialDB is sourced from an actual large data warehouse comprising 17844 schema elements. We show that our method1 leads to significantly higher recall than SOTA retrieval-based augmentation methods.Comment: To appear at EMNLP 2023 (Main

Targeted Subset Selection for Limited-data ASR Accent Adaptation

We study the task of adapting an existing ASR model to a non-native accent while being constrained by a transcription budget on the duration of utterances selected from a large unlabeled corpus. We propose a subset selection approach using the recently proposed submodular mutual information functions, in which we identify a diverse set of utterances that match the target accent. This is specified through a few target utterances and achieved by modelling the relationship between the target and the selected subsets using these functions. The model adapts to the accent through fine-tuning with utterances selected and transcribed from the unlabeled corpus. We also use an accent classifier to learn accent-aware feature representations. Our method is also able to exploit samples from other accents to perform out-of-domain selections for low-resource accents which are not available in these corpora. We show that the targeted subset selection approach improves significantly upon random sampling - by around 5% to 10% (absolute) in most cases, and is around 10x more label-efficient. We also compare with an oracle method where we specifically pick from the target accent and our method is comparable to the oracle in its selections and WER performance.Comment: Under review (INTERSPEECH 2022

Evolution of Drainage in Response to Brittle - Ductile Dynamics and Surface Processes in Kachchh Rift Basin, Western India

The eastern part of Kachchh Rift basin was reactivated after 2001 Bhuj earthquake of Mw 7.7 and continuous seismicity has been recorded since then. The northern part of Wagad upland also experienced moderate earthquakes Mw ≥ 5.7 in February 2006 and March 2007. These moderate to major Intraplate earthquakes provide a unique opportunity to study the effects and linkage between brittle-ductile dynamics, surface processes and drainage evolution. We presented a geomorphological analysis of the Wagad highland providing new constraints on the evolution of river network. The shallow to deeper nature of fault and their response to development of hydrological networks has been analyzed using seismic tomography. Based on surface drainage offset and seismic structures several E-W oriented faults controlling fluvial dynamics are identified. From seismic structures and drainage offset it is clear that the fluvial dynamics is controlled by shallower to deeper faults. The estimated attributes are well supported with seismic structures and focal mechanisms solutions. Based on fluvial offset and seismic structure analysis a new tectonic model has been proposed for WH. The tectonic model shows that the faults WH are well connected at deeper level and generated negative flower structures and significantly controlling surface fluvial dynamics

Scour prediction in non-uniform soils: undrained shear strength and erodibility

Scour development in non-uniform soils is still an area of great uncertainty and remains a challenge for designing structurally efficient and effective foundations in the marine environment. Scour risk in cohesive soils is made more uncertain by effects such as weathering and time-scale to scour. For large volume installation of foundations such as those related to offshore wind farm developments there is a limit to the amount of detailed geotechnical information that can be collected as part of the project. Therefore, reliance in data such as undrained shear strength, derived from cone penetration tests, supplemented with borehole data collected at a limited number of sites across the wind farm and laboratory analysis of soil samples becomes the principal source of geotechnical information. Hence, the question arises as to whether the undrained shear strength be used as a proxy for the erodibility of a soil as proposed in the approach of Annandale (1995). This paper will present evidence from both field and laboratory measurements of undrained shear strength and scour potential to test the hypothesis of undrained shear strength as a proxy for scour

Submerged flexible vegetation impact on open channel flow velocity distribution: An analytical modelling study on drag and friction

YesIn this paper, an analytical model that represents the streamwise velocity distribution for open channel flow with submerged flexible vegetation is studied. In the present vegetated flow modelling, the whole flow field has been separated into two layers vertically: a vegetated layer and a non-vegetated free-water layer. Within the vegetated layer, an analysis of the mechanisms affecting water flow through flexible vegetation has been conducted. In the non-vegetated layer, a modified log-law equation that represents the velocity profile varying with vegetation height has been investigated. Based on the studied analytical model, a sensitivity analysis has been conducted to assess the influences of the drag and friction coefficients on the flow velocity. The investigated ranges of drag and friction coefficients have also been compared to published values. The findings suggest that the drag and friction coefficient values are non-constant at different depths and vegetation densities, unlike the constant values commonly suggested in literature. This phenomenon is particularly clear for flows with flexible vegetation, which is characterised by large deflection