Search results for "Wind"

PCA analysis of wind direction climate in the baltic states

2021

Wind direction is one of the fundamental parameters of weather. In this study we investigate the wind direction climate 10 m above surface level in the Baltic States (Estonia, Latvia, Lithuania). The analysis of wind direction over larger regions is usually hindered by the fact that wind direction is a circular variable, which means that averaged values are meaningless. Here we show how Principal Component Analysis (PCA) can be applied to give a large scale overview of typical wind direction patterns in the region. Here we apply PCA to both observational and reanalysis data. The most significant wind direction patterns are detected in both synoptic scale and mesoscale, and we attempt to lin…

Analyzing the security of Windows 7 and Linux for cloud computing

2013

We review and analyze the major security features and concerns in deploying modern commodity operating systems such as Windows 7 and Linux 2.6.38 in a cloud computing environment. We identify the security weaknesses and open challenges of these two operating systems when deployed in the cloud environment. In particular, we examine and compare various operating system security features which are critical in providing a secure cloud. These security features include authentication, authorization and access control, physical memory protection, privacy and encryption of stored data, network access and firewalling capabilities, and virtual memory.

The Spirit Rover's Athena science investigation at Gusev Crater, Mars.

2004

The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former lake, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration. Any lacustrine sediments that may exist at this location within Gusev apparently have been buried by lavas that have undergone subsequent impact disruption.

A heuristic approach for optimal operation of grid connected source-battery-load systems

2016

In the paper an optimal management procedure for a system composed of a renewable energy source, storage batteries and a load, permanently connected to a distribution network, is presented. The issue follows two objectives: a) maximum economic benefit for the system, and b) minimum energy exchange with the network. The operation cost of storage facilities, as well as the technical and economic constraints on power exchanges between the system and the network and the technical constraints about charging and discharging cycles of the batteries are considered. The effectiveness of the management procedure is numerically tested and the results are presented.

On the modelling of an Acid/Base Flow Battery: An innovative electrical energy storage device based on pH and salinity gradients

2020

Abstract Electrical energy storage can enhance the efficiency in the use of fluctuating renewable sources, e.g. solar and wind energy. The Acid/Base Flow Battery is an innovative and sustainable process to store electrical energy in the form of pH and salinity gradients via electrodialytic reversible techniques. Two electromembrane processes are involved: Bipolar Membrane Electrodialysis during the charge phase and its opposite, Bipolar Membrane Reverse Electrodialysis, during the discharge phase. For the first time, the present work aims at predicting the performance of this energy storage device via the development of a dynamic mathematical model based on a multi-scale approach with distr…

Influence of variability and uncertainty of wind and waves on fatigue damage of a floating wind turbine drivetrain

2021

Abstract This study investigates the effect of variability and uncertainty of wind and wave conditions on the short-term fatigue damage of a 10-MW floating wind turbine drivetrain. Global dynamic responses of a semi-submersible wind turbine are calculated by aero-hydro-servo-elastic simulations in various environmental conditions. Then, rotor and generator loads, as well as nacelle motions from the global analysis are provided to a drivetrain model to investigate its dynamics. One-hour fatigue damage of the drivetrain bearings is calculated based on the bearing loads and speeds, and the effect of uncertainties related to wind and waves is assessed. The results indicate that the variations o…

Application of A Precision Apiculture System to Monitor Honey Daily Production †

2020

Precision beekeeping or precision apiculture is an apiary management strategy based on the monitoring of individual bee colonies to minimize resource consumption and maximize the productivity of bees. Bees play a fundamental role in ensuring pollination

Editorial: Timing the Brain: From Basic Sciences to Clinical Implications

2022

Rīks Bezjē līkņu konstruēšanai un modificēšanai

2019

Kvalifikācijas darbā ir aprakstīta sistēma interaktīvam grafisku objektu rīkam, kas paredzēta kubisku Bezjē līkņu konstruēšanai, modificēšanai un dzēšanai, izmantojot datorpeli, datora tastatūru vai teksta failus. Sistēma piedāvā ģenerēt četru dažādu veidu Bezjē līknes, tai skaitā interpolētas līknes un saliktas līknes ar C2 nepārtrauktību (B-splaini), papildus izmantojot trīs dažādu veidu parametrizācijas metodes. Iespējams arī izvadīt konstruēto Bezjē līkņu kontrolpunktus un/vai mezglu punktus, kā arī citus līkni raksturojošos lielumus. Līkņu vizuālai salīdzināšanai iespējams augšupielādēt fona attēlu un pietuvināt, attālināt grafiskos objektus. Sistēma implementēta C# programmēšanas valo…

Biological nitrogen removal from landfill leachate: a pilot-scale study

1999

A pilot-scale two-stage process including an anaerobic pretreatment (up-flow anaerobic sludge blanket, UASB) unit and a pre-denitrification activated sludge process was studied for treating leachates from a municipal landfill (waste aged 4 to 5 years, area 2.5 ha) and from a windrow composting area (1ha). A single-stage pilot process was used for nitrification studies. The leachate characteristics were as follows: COD 740 to 2400 mg 1-1 (chemical oxygen demand), BOD7 (biochemical oxygen demand) approximately 1000 mg 1 -1, Ntot 40 to 120 mg 1-1 and the temperature was between 2 and 21°C. The results show that 45 to 50% COD removal could be achieved in the UASB reactor even at temperatures b…