Empowering End-users to Collaboratively Manage and Analyze Evolving Data Models

In order to empower end-users to make well-founded decisions based on domain-specific knowledge, companies use end-user oriented business intelligence (BI) software like spreadsheets. Moreover, many decisions require the collaboration of multiple and autonomous knowledge workers. However, prevalent BI software does not provide elevated collaboration features as known from traditional Web 2.0 technologies. There is also a lack of research on how to integrate collaboration features into BI systems, and which challenges arise as a consequence. In the paper at hand we address this issue by proposing the Spreadsheet 2.0 approach, which integrates Web 2.0 features with the spreadsheet paradigm as most-common representative of end-user-oriented business intelligence tools. Therefore, we derive requirements for a Web 2.0-based approach to collaborative BI, and present the conceptual design for a Spreadsheet 2.0 solution. Subsequently, we demonstrate a corresponding prototypical implementation, and elaborate on key findings and main challenges identified by its application and evaluation

Mixed Valence Europium Nitridosilicate Eu2SiN3

The mixed valence europium nitridosilicate Eu2SiN3 has been synthesized at 900°C in welded tantalum ampules starting from europium and silicon diimide Si(NH)2 in a lithium flux. The structure of the black material has been determined by single-crystal X-ray diffraction analysis (Cmca (no. 64), a=542.3(11) pm, b=1061.0(2) pm, c=1162.9(2) pm, Z=8, 767 independent reflections, 37 parameters, R1=0.017, wR2=0.032). Eu2SiN3 is a chain-type silicate comprising one-dimensional infinite nonbranched zweier chains of corner-sharing SiN4 tetrahedra running parallel [100] with a maximum stretching factor fs=1.0. The compound is isostructural with Ca2PN3 and Rb2TiO3, and it represents the first example of a nonbranched chain silicate in the class of nitridosilicates. There are two crystallographically distinct europium sites (at two different Wyckoff positions 8f) being occupied with Eu2+ and Eu3+, respectively. 151Eu Mössbauer spectroscopy of Eu2SiN3 differentiates unequivocally these two europium atoms and confirms their equiatomic multiplicity, showing static mixed valence with a constant ratio of the Eu2+ and Eu3+ signals over the whole temperature range. The Eu2+ site shows magnetic hyperfine field splitting at 4.2 K. Magnetic susceptibility measurements exhibit Curie-Weiss behavior above 24 K with an effective magnetic moment of 7.5 μB/f.u. and a small contribution of Eu3+, in accordance with Eu2+ and Eu3+ in equiatomic ratio. Ferromagnetic ordering at unusually high temperature is detected at TC=24 K. DFT calculations of Eu2SiN3 reveal a band gap of ∼0.2 eV, which is in agreement with the black color of the compound. Both DFT calculations and lattice energetic calculations (MAPLE) corroborate the assignment of two crystallographically independent Eu sites to Eu2+ and Eu3+

Fernwanderungen und innerstädtische Umzüge als Motoren der Reurbanisierung in Hamburg

Die vorliegende Analyse beschäftigt sich mit innerstädtischen Umzügen und überregionalen Zuwanderungen in Hamburg zwischen den Jahren 2006 und 2010. Ziel ist es, die Rolle, die unterschiedliche Teilgebiete der Stadt im stadtregionalen Reurbanisierungsprozess einnehmen, besser zu verstehen. Es wird herausgearbeitet, welche Stadtteile von innerstädtischen Zuzüglern und überregionalen Zuwanderern bevorzugt und welche seltener gewählt werden. Ausgehend von ähnlichen Zuzugs- und Zuwanderungsmustern wird eine Stadtteiltypisierung vorgenommen. Im Ergebnis kann gezeigt werden, dass sozioökonomisch benachteiligte Stadtteile mit verhältnismäßig hoher Einwohner- und Nahversorgungsdichte und niedrigem Mietniveau als "Auffangbecken" für Fernwanderer fungieren. Entgegen den Erwartungen sind aber die dichtesten und funktional am besten ausgestatteten Stadtteile ebenfalls besonders häufig Ziel von Fernwanderern, zugleich aber auch von innerstädtischen Zuzüglern. Diese Stadtteile nehmen trotz ihrer hohen Dichte besonders viel Bevölkerung auf und wachsen stark.This analysis is concerned with relocations within the urban area and supra-regional migrations to Hamburg between 2006 and 2010. The aim is to improve understanding of the role played by the various sub-areas of the city in the reurbanisation process. The urban districts that are most popular with people relocating within the city and those migrating from other regions are identified, as are those that are less often selected. Based on similar relocation and migration patterns, a typology of urban districts is developed. The results show that socio-economically disadvantaged urban districts with comparatively high densities of population and local retail and comparatively low rents act as collecting points for long-distance migrants. Contrary to expectations however, the most densely populated urban districts with the best facilities are often the objective of long-distance migrants too, and also of people relocating within the urban area. Despite their high population densities, these urban districts accommodate a particularly large population and have a high rate of growth

UTLS temperature validation of MPI-ESM decadal hindcast experiments with GPS radio occultations

Global Positioning System (GPS) radio occultation (RO) temperature data are used to validate MPI-ESM (Max Planck Institute – Earth System Model) decadal hindcast experiments in the upper troposphere and lower stratosphere (UTLS) region between 300 hPa and 10 hPa (8 km and 32 km) for the time period between 2002 and 2011. The GPSRO dataset is unique since it is very precise, calibration independent and covers the globe better than the usual radiosonde dataset. In addition it is vertically finer resolved than any of the existing satellite temperature measurements available for the UTLS and provides now a unique one decade long temperature validation dataset. The initialization of the MPI-ESM decadal hindcast runs mostly increases the skill of the atmospheric temperatures when compared to uninitialized climate projections with very high skill scores for lead-year one, and gradually decreases for the later lead-years. A comparison between two different initialization sets (b0, b1) of the low-resolution (LR) MPI-ESM shows increased skills in b1-LR in most parts of the UTLS in particular in the tropics. The medium resolution (MR) MPI-ESM initializations are characterized by reduced temperature biases in the uninitialized runs as compared to observations and a better capturing of the high latitude northern hemisphere interannual polar vortex variability as compared to the LR model version. Negative skills are found for the b1-MR hindcasts however in the regions around the mid-latitude tropospheric jets on both hemispheres and in the vicinity of the tropical tropopause in comparison to the b1-LR variant. It is interesting to highlight that none of the model experiments can reproduce the observed positive temperature trend in the tropical tropopause region since 2001 as seen by GPSRO data

Quantifying uncertainties of climate signals in chemistry climate models related to the 11-year solar cycle – Part 1: Annual mean response in heating rates, temperature, and ozone

Variations in the solar spectral irradiance (SSI) with the 11-year sunspot cycle have been shown to have a significant impact on temperatures and the mixing ratios of atmospheric constituents in the stratosphere and mesosphere. Uncertainties in modelling the effects of SSI variations arise from uncertainties in the empirical models reconstructing the prescribed SSI data set as well as from uncertainties in the chemistry–climate model (CCM) formulation. In this study CCM simulations with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model and the Community Earth System Model 1 (CESM1)–Whole Atmosphere Chemistry Climate Model (WACCM) have been performed to quantify the uncertainties of the solar responses in chemistry and dynamics that are due to the usage of five different SSI data sets or the two CCMs. We apply a two-way analysis of variance (ANOVA) to separate the influence of the SSI data sets and the CCMs on the variability of the solar response in shortwave heating rates, temperature, and ozone. The solar response is derived from climatological differences of time slice simulations prescribing SSI for the solar maximum in 1989 and near the solar minimum in 1994. The SSI values for the solar maximum of each SSI data set are created by adding the SSI differences between November 1994 and November 1989 to a common SSI reference spectrum for near-solar-minimum conditions based on ATLAS-3 (Atmospheric Laboratory of Applications and Science-3). The ANOVA identifies the SSI data set with the strongest influence on the variability of the solar response in shortwave heating rates in the upper mesosphere and in the upper stratosphere–lower mesosphere. The strongest influence on the variability of the solar response in ozone and temperature is identified in the upper stratosphere–lower mesosphere. However, in the region of the largest ozone mixing ratio, in the stratosphere from 50 to 10 hPa, the SSI data sets do not contribute much to the variability of the solar response when the Spectral And Total Irradiance REconstructions-T (SATIRE-T) SSI data set is omitted. The largest influence of the CCMs on variability of the solar responses can be identified in the upper mesosphere. The solar response in the lower stratosphere also depends on the CCM used, especially in the tropics and northern hemispheric subtropics and mid-latitudes, where the model dynamics modulate the solar responses. Apart from the upper mesosphere, there are also regions where the largest fraction of the variability of the solar response is explained by randomness, especially for the solar response in temperature

Occupant-oriented demand response with multi-zone thermal building control

In future energy systems with high shares of renewable energy sources, the electricity demand of buildings has to react to the fluctuating electricity generation in view of stability. As buildings consume one-third of global energy and almost half of this energy accounts for Heating, Ventilation, and Air Conditioning (HVAC) systems, HVAC are suitable for shifting their electricity consumption in time. To this end, intelligent control strategies are necessary as the conventional control of HVAC is not optimized for the actual demand of occupants and the current situation in the electricity grid. In this paper, we present the novel multi-zone controller Price Storage Control (PSC) that not only considers room-individual Occupants’ Thermal Satisfaction (OTS), but also the available energy storage, and energy prices. The main feature of PSC is that it does not need a building model or forecasts of future demands to derive the control actions for multiple rooms in a building. For comparison, we use an ideal, error-free Model Predictive Control (MPC), a heuristic control approach from the literature (PC), and a conventional hysteresis-based two-point control as upper and lower benchmarks. We evaluate the four controllers in a multi-zone environment for heating a building in winter and consider two different scenarios that differ in how much the permitted temperatures vary. In addition, we compare the impact of model parameters with high and low thermal capacitance. The results show that PSC strongly outperforms the conventional control approach and PC in both scenarios and for both parameters concerning the electricity costs and OTS. For high capacitance, it leads to 22 % costs reduction while the ideal MPC achieves cost reductions of more than 39 %. Considering that PSC does not need any building model or forecast, as opposed to MPC, the results support the suitability of our developed control strategy for controlling HVAC systems in future energy systems