Microstructure alterations in the base material, heat affected zone and weld metal of a 440-VVER-reactor pressure vessel caused by high fluence irradiation during long term operation; material: 15 Ch2MFA ≈0.15 C–2.5 Cr–0.7 Mo–0.3 V

Within the scope of the EC research project Tacis ’91 (‘RPV-Embrittlement’), trepans were taken from the highly irradiated circumferential RPV-weld of the Novovoronesh power plant unit-2 of the type VVER-440/230. The cumulated fast fluence level in this position reaches up to 6.5×10¹⁹/cm² (E>0.5 MeV). In a joint research work, the mechanical properties, the chemical composition, and the microstructure of the base material, the heat affected zone (HAZ), and the weld metal have been investigated in order to study the influence of irradiation, and of post irradiation heat treatment (475°C, 560°C) on the properties. The examination of the microstructure performed by analytical transmission electron microscopy (200 kV) shows the existence of dislocation loops (‘black dots’), irradiation induced precipitates, and segregation of copper in the carbides. These changes in microstructure, which are due to service affection (neutron irradiation, temperature) have occurred more pronounced in the weld metal and the HAZ than in the base material.     

Locating experts and carving out the state of the art: A systematic review on Industry 4.0 and energy system analysis

As Germany's manufacturing industry highly depends on international competitiveness, German companies must rapidly assimilate to current processes of digitization and so‐called Industry 4.0. These processes will also affect the German energy system. Understanding and predicting the implications of these changes is one of the core elements of energy system analysis. To address this issue, herein, we present a structured and systematic review of literature within the intersection of industrial digitalization in the sense of Industry 4.0 and scientific energy system analysis. The goals of this study are (1) to reveal the locations and institutions of relevant experts and (2) to carve out the current state of the art with regard to technologies that enable (digitized) industries to interact with the energy system in order to contribute to a smart energy system. Our approach is based on a systematic and reproducible keyword search using the scientific literature database Scopus. Both a quantitative evaluation and a qualitative evaluation of the relevant literature are conducted. The quantitative results are presented using GIS‐based visualizations. This facilitates us to identify the European Union as main contributor on a global level and the United Kingdom as the most prolifically publishing country within the European Union. Focusing on Germany, we find North Rhine‐Westphalia to be the most scientifically active area and Aachen/Dortmund to be the cities where most publications originate. In the qualitative, content‐based part of this review, we show that in particular sector coupling and the integration of distributed energy prosumers can lead to a working smart energy system. We demonstrate that industrial digitalization processes in the sense of Industry 4.0 can serve as enabling factor in this respect. Further, we provide extensive summaries regarding both the technological and economic potentials and challenges of different technologies in future smart energy systems. Taking all of the results into account, we outline a framework to connect the highly discussed topics of digitalized industries and smart energy systems to corresponding experts.     

Nonlinear finite-element analysis of the role of dynamic changes inblood perfusion and optical properties in laser coagulation of tissue

A nonlinear finite-element program was developed to simulate the dynamic evolution of coagulation in tissue considering temperature and damage dependence of both the optical properties and blood perfusion rate. These dynamic parameters were derived based on the Arrhenius rate process formulation of thermal damage and kinetics of vasodilation. Using this nonlinear model, we found that the region of increased blood flow that formed at the periphery of the coagulation region significantly reduces the heat penetration. Moreover, increased scattering in the near-surface region prevents light penetration into the deeper region. Therefore, if the dynamic parameters are ignored, a relatively significant overestimation of the temperature rise occurs in a deeper area resulting in an overestimation in predicted depth of coagulation. Mathematical modeling techniques that simulate laser coagulation may not provide reliable information unless they take into account these dynamic parameters     

Testing a Typology of Homelessness Across Welfare Regimes: Shelter Use in Denmark and the USA

This article compares patterns of homeless shelter use in Denmark and the USA. Combining data from homeless shelters in Denmark with population registers, we find that the prevalence of shelter use is substantially lower in Denmark than in the USA. A cluster analysis of shelter stays identifies three types of users similar to findings from US research: the transitionally, episodically and chronically homeless. However, the transitionally homeless in Denmark have a higher tendency of suffering from mental illness and substance abuse than the transitionally homeless in the USA. The results support Stephens and Fitzpatrick' hypothesis that countries with more extensive welfare systems and lower levels of poverty have lower levels of homelessness, mainly amongst those with complex support needs, whereas in countries with less extensive welfare systems homelessness affects broader groups and is more widely associated with poverty and housing affordability problems.     

Evaluation of different approaches to quantify strong organic acidity and acid-base buffering of organic-rich surface waters in Sweden

The role of organic acids in buffering pH in surface waters has been studied using a small brownwater stream (26mg L(-1) TOC) draining a forested catchment in Northern Sweden. Under the conditions of elevated pressure of CO2 stream field pH was changed between 3.5 and 6.1 during the acidification and alkalinization experiment. Acid-base characteristics of the natural organic matter were also determined using a high precision potentiometric method for a concentrated sample from the same stream. We compared the predictions from the Windermere Humic Aqueous Model (WHAM Model V), a model derived from the potentiometric titration (diprotic/monoprotic acid model) and a previously derived triprotic acid model which only uses alkalinity and TOC as input variables. The predicted buffering characteristics of all three models are very similar in the pH range 4.5-7 which suggests that during routine analysis alkalinity and TOC are sufficient to give a good estimate of organic acid anion charge contribution in a large range of surface waters. A slightly adjusted version of WHAM V successfully describes the organic charge contribution in a large number of sampled surface water lakes, which were previously used to calibrate the triprotic model.