Search results for "DRY"
showing 10 items of 980 documents
Satvara izstrāde vienotai lietotāja ievades klienta un servera puses validācijai
2016
Lietotāja ievades validācija ir pašsaprotams process jebkurā nopietnā sistēmā. Slikti dati un izvairīšanās no to apstrādes var novest pie drošības riskiem, negaidītas sistēmas darbības vai sliktas pieredzes lietojot sistēmu. Parasti sistēmām servera puses un klienta puses validācijas tiek veidotas atsevišķi, taču uzdevumi bieži vien pārklājas. Kā bakalaura darba mērķis tika izvirzīts izpētīt klienta un servera puses validācijas risinājumus, atrast kopīgās raksturīpašības un izveidot sistēmu, kas ļauj vienuviet pārvaldīt izmaiņas, nodrošināt kļūdu ziņojumu tulkojumus, neatkārtot darbības, kas jau veiktas citā solī. Bakalaura darbā izvirzītā hipotēze – vienota satvara izstrāde klienta un serv…
Electron transport and the effect of current annealing in a two-point contacted hBN/graphene/hBN heterostructure device
2020
In this work, we fabricated a 2D van der Waals heterostructure device in an inert nitrogen atmosphere by means of a dry transfer technique in order to obtain a clean and largely impurity free stack of hexagonal boron nitride (hBN)-encapsulated few-layer graphene. The heterostructure was contacted from the top with gold leads on two sides, and the device’s properties including intrinsic charge carrier density, mobility, and contact resistance were studied as a function of temperature from 4 K to 270 K. We show that the contact resistance of the device mainly originates from the metal/graphene interface, which contributes a significant part to the total resistance. We demonstrate that current…
Properties of Nanosized Ferrite Powders and Sintered Materials Prepared by the Co-Precipitation Technology, Combined with the Spray-Drying Method
2016
Cobalt and nickel ferrites powders are synthesized by the co-precipitation technology, combined with the spray-drying method. The crystallite size, specific surface area (SSA), magnetic properties of synthesized products are investigated. All the synthesized ferrites are nanocrystalline single phase materials with crystallite size of 5-6 nm, the SSA of 80-85 m2/g and the calculated particle size of 13-15 nm. After spray-drying granules of the size up to 10 μm are obtained. After thermal treatment at 550 and 950 °C SSA decreases to 40-50 m2/g and 20-22 m2/g, respectively. The saturation magnetization at these temperatures increase from 17 to 40 emu/g for NiFe2O4 and from 51 to 77 emu/g for C…
Theoretical study on the decomposition mechanism of bisphenol A polycarbonate induced by the combined effect of humidity and UV irradiation.
2020
Polycarbonate (PC) is a good material for covering and protecting cultural heritage sites because of its durability, mechanical properties, and transparency. When bisphenol A polycarbonate is subjected to weathering conditions this polymer shows several degradation processes depending on the irradiation wavelength, humidity and temperature. In particular, the combined effects of humidity and UV irradiation speed up the PC molecular weight reduction. In this work, the decomposition mechanisms associated to the hydrolysis process are scrutinized and the effects of UV irradiation on the hydrolysis process are evaluated throughout the Density Functional Theory (DFT) approach. It was found that …
Seasonal Analysis of Surface Soil Moisture Dry-Downs in a Land-Atmosphere Hotspot as Seen by LSM and Satellite Products
2018
The soil drying process is a challenging framework to assess climatic, hydrologic and ecosystem processes. This work develops a seasonal analysis of temporal e-folding decay ( $\tau$ ) of surface soil moisture dry-downs using ORCHIDEE land surface model and SMOS observations over South Eastern South America (SESA). Results show that the soil drying process depends on both location and season, and that the modeled drying velocity is faster than the observed one, even when modeled data is sampled at the same frequency as the observations. Differences between observed and modeled data have been found both in the analysis of the regional overall $\tau$ and in the spatial patterns of $\tau$ esti…
Effects of climate change and land use intensification on regional biological soil crust cover and composition in southern Africa
2022
Biological soil crusts (biocrusts) form a regular and relevant feature in drylands, as they stabilize the soil, fix nutrients, and influence water cycling. However, biocrust forming organisms have been shown to be dramatically vulnerable to climate and land use change occurring in these regions. In this study, we used Normalized Difference Vegetation Index (NDVI) data of biocrust-dominated pixels (NDVIbiocrust) obtained from hyperspectral and LANDSAT-7 data to analyse biocrust development over time and to forecast future NDVIbiocrust development under different climate change and livestock density scenarios in southern Africa. We validated these results by analysing the occurrence and compo…
The response of flood-plain ecosystems to the Late Glacial and Early Holocene hydrological changes: A case study from a small Central European river …
2016
Abstract We use a range of environmental variables to explore the possible drivers influencing the biota, especially the composition of aquatic invertebrates, during the Younger Dryas (YD) and Early Holocene (EH) in different river valley sites: a well-developed meandering river and the confluence zone of headwater streams. Using pollen, macrofossil, cladoceran, and chironomid as well as geochemical and lithological data as proxies for environmental factors (i.e., water depth and temperature), we attempt to show that these different sites display similar hydroclimatic signals (especially floods). The geochemical records in the studied valley are correlated with environmental factors, such a…
El Niño variability off Peru during the last 20,000 years
2005
Here we present a high-resolution marine sediment record from the El Nino region off the coast of Peru spanning the last 20,000 years. Sea surface temperature, photosynthetic pigments, and a lithic proxy for El Nino flood events on the continent are used as paleo–El Nino–Southern Oscillation proxy data. The onset of stronger El Nino activity in Peru started around 17,000 calibrated years before the present, which is later than modeling experiments show but contemporaneous with the Heinrich event 1. Maximum El Nino activity occurred during the early and late Holocene, especially during the second and third millennium B.P. The recurrence period of very strong El Nino events is 60–80 years. El…
High-frequency climate fluctuations over the last deglaciation in the Alboran Sea, Western Mediterranean: Evidence from calcareous plankton assemblag…
2018
Abstract A high resolution study, with a centennial scale resolution, has been performed on the calcareous plankton assemblage (coccolithophores and planktonic foraminifera) at Ocean Drilling Program Site 976, Alboran Sea (Western Mediterranean), focusing on the interval between 20 and 9 ka, in order to reconstruct changes in surface and subsurface water dynamics and productivity. The biotic surface water proxies integrate the extremely detailed (multi-decadal scale) geochemical data set and the pollen record already available at the core, thus providing a complete paleoenvironmental/paleoceanographic reconstruction. The results highlight the sensitivity of the calcareous plankton in record…
The response of a shallow lake and its catchment to Late Glacial climate changes — A case study from eastern Poland
2015
In this study we investigate how climate fluctuation in the Late Glacial period influenced the development of a lake and its catchment located in the East European Plain. We analyzed the sediments of the lake for pollen, subfossil Cladocera, macrofossils and chemical composition. We aimed at disentangling: (1) the climate changes and their limno-ecological responses, (2) temperature dynamics with the use of Cladocera-based transfer function (MJT) and macrofossil-based reconstruction of mean minimum July temperature (MMJT), (3) timing of the response of different proxies to environmental changes. The results of multiproxy analyses explicitly suggest that the main driver for changes in aquati…