A coarse space for heterogeneous Helmholtz problems based on the Dirichlet-to-Neumann operator

The Helmholtz equation governing wave propagation and scattering phenomena is difficult to solve numerically. Its discretization with piecewise linear finite elements results in typically large linear systems of equations. The inherently parallel domain decomposition methods constitute hence a promising class of preconditioners. An essential element of these methods is a good coarse space. Here, the Helmholtz equation presents a particular challenge, as even slight deviations from the optimal choice can be devastating. In this paper, we present a coarse space that is based on local eigenproblems involving the Dirichlet-to-Neumann operator. Our construction is completely automatic, ensuring good convergence rates without the need for parameter tuning. Moreover, it naturally respects local variations in the wave number and is hence suited also for heterogeneous Helmholtz problems. The resulting method is parallel by design and its efficiency is demonstrated on 2D homogeneous and heterogeneous numerical examples

Volatile Profile and Physico-Chemical Analysis of Acacia Honey for Geographical Origin and Nutritional Value Determination

Honey composition and color depend greatly on the botanical and geographical origin. Water content, water activity and color of 50 declared acacia samples, collected from three different geographical zones of Romania, together with chromatographic determination of sugar spectrum were analyzed. A number of 79 volatile compounds from the classes of: Alcohols, aldehydes, esters, ketones, sulphur compounds, aliphatic hydrocarbons, nitrogen compounds, carboxylic acids, aromatic acids and ethers were identified by solid-phase micro-extraction and gas-chromatography mass spectrometry. The overall volatile profile and sugar spectrum of the investigated honey samples allow the differentiation of geographical origin for the acacia honey samples subjected to analysis. The statistical models of the chromatic determination, physicochemical parameters and volatile profile was optimal to characterize the honey samples and group them into three geographical origins, even they belong to the same botanical origin

Norway's Battery Electric Vehicles and Public Health- Findings From the Literature.

The transportation sector is among the highest contributors to the increase in greenhouse gas emissions in European nations, with private cars emerging as the primary source. Although reducing emissions presents a formidable challenge, the emergence of battery electric vehicles (BEVs) offers a promising and sustainable avenue toward achieving zero greenhouse gases within the transportation infrastructure. Since the 1990s, the Norwegian parliament has fervently supported this transition, leveraging public awareness campaigns and a range of financial incentives for its users nationwide. The widespread utilization of BEVs promises substantial health benefits, including ensuring cleaner air for all citizens regardless of their socioeconomic status and fostering improvements in public health outcomes. This transition potentially curtails hundreds of thousands of annual deaths attributed to climate change, enhances the quality of life, bolsters civilian productivity, and fuels economic and population growth. The adoption of BEVs offers a myriad of advantages, including reduced health risks and premature mortality, as well as a quieter environment with diminished noise pollution. Nonetheless, the integration of BEVs necessitates robust road infrastructure with considerable maintenance costs, alongside limitations on driving range for users. Concerns arise regarding potential particle emissions from BEV tire wear due to the increased weight of batteries compared to conventional vehicles. Rapid acceleration capabilities may accelerate tire degradation, contributing to higher particle emissions, of which only 10% to 20% remain suspended in the air, whereas the majority settles on road surfaces, posing a threat to nearby aquatic ecosystems when washed into water bodies and soils. While BEVs hold promise for valuable benefits, successful policy creation and implementation require a detailed awareness of their limitations and challenges to ensure a comprehensive approach to sustainable mobility and public health improvement. Therefore, more research on the limitations of BEVs can help inform improved tactics for maximizing their benefits while limiting potential disadvantages