Sökning: "sparse data"

Visar resultat 1 - 5 av 291 avhandlingar innehållade orden sparse data.

  1. 1. Order in the random forest

    Författare :Isak Karlsson; Henrik Boström; Lars Asker; Pierre Geurts; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Machine learning; random forest; ensemble; time series; data series; sequential data; sparse data; high-dimensional data; Computer and Systems Sciences; data- och systemvetenskap;

    Sammanfattning : In many domains, repeated measurements are systematically collected to obtain the characteristics of objects or situations that evolve over time or other logical orderings. Although the classification of such data series shares many similarities with traditional multidimensional classification, inducing accurate machine learning models using traditional algorithms are typically infeasible since the order of the values must be considered. LÄS MER

  2. 2. Flood Hazard Assessment in Data-Scarce Basins : Use of alternative data and modelling techniques

    Författare :Diana Fuentes-Andino; Sven Halldin; Chong-Yu Xu; Keith Beven; Giuliano Di Baldassarre; Wouter Buytaert; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Central America; floods; data scarcity; data quality; uncertainty analysis; regionalisation; flood frequency analysis; GLUE; hydraulic modelling; rainfall-runoff modeling; TOPMODEL; LISFLOOD-FP; GRADEX; index-flood; Muskingum-Cunge-Todini flow routing; Mellanamerika; högflöde; datakvalitet; osäkerhetsanalys; regionalisering; frekvensanalys av högflöden; GLUE; hydraulisk modellering; nederbörds-avrinningsmodeller; TOPMODEL; LISFLOOD-FP; GRADEX; indexflöde; Muskingum-Cunge-Todini flödessvarstid; Central América; inundaciones; escasez de datos; calidad de los datos; análisis de incertidumbre; regionalización; análisis de frequencia de inundación; GLUE; modelación hidraulica; modelo de lluvia-escorrentía; TOPMODEL; LISFLOOD-FP; GRADEX; índice de inundación; Muskingum-Cunge-Todini rutina de propagación de flujo;

    Sammanfattning : Flooding is of great concern world-wide, causing damage to infrastructure, property and loss of life. Low-income countries, in particular, can be negatively affected by flood events due to their inherent vulnerabilities. Moreover, data to perform studies for flood risk management in low-income regions are often scarce or lacking sufficient quality. LÄS MER

  3. 3. Disinformative and Uncertain Data in Global Hydrology : Challenges for Modelling and Regionalisation

    Författare :Anna Kauffeldt; Sven Halldin; Allan Rodhe; Chong-Yu Xu; András Bárdossy; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Data uncertainty; Discharge; Disinformative data; Evaporation; Flow-duration curve; Global hydrology; Neural networks; Numerical weather prediction; Precipitation; Quality control; Regionalisation; Ungauged basins; Water balance; Avdunstning; avrinningsområden utan vattenföringsdata; dataosäkerhet; desinformativa data; global hydrologi; kvalitetskontroll; nederbörd; neurala nät; numerisk vädermodell; regionalisering; varaktighetskurva; vattenbalans; vattenföring; Hydrology; Hydrologi;

    Sammanfattning : Water is essential for human well-being and healthy ecosystems, but population growth and changes in climate and land-use are putting increased stress on water resources in many regions. To ensure water security, knowledge about the spatiotemporal distribution of these resources is of great importance. LÄS MER

  4. 4. Sparse Voxel DAGs

    Författare :Viktor Kämpe; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geometry; Shadows; Data structures; Tree; Visibility; Grid; Voxel; Directed acyclic graph; Computer graphics;

    Sammanfattning : This thesis investigates a memory-efficient representation of highly detailed geometry in 3D voxel grids. The memory consumption of a plain dense grid scales too fast as the resolution increases to be feasible at very high resolutions. LÄS MER

  5. 5. Studies in Applied Data Structures

    Författare :Kurt Swanson; Institutionen för datavetenskap; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Systems engineering; Sparse Matrix; Suffix Tree; Roundness; Range searching; Data- och systemvetenskap; computer technology;

    Sammanfattning : The design of efficient data structures is of primary importance in creation of theoretical algorithms as well their more tangible descendants, computer programs. In this dissertation we study computational aspects of data structures and their respective algorithms from a theoretical viewpoint, which are however of direct importance in the implementation of solutions for real-world problems. LÄS MER