On the Turnaround of Vacancy Stocks: The Stock Flow Model for the German Residential Rental Market

We apply the stock flow model for the German residential rental market using a data set that includes the overwhelming majority of nomenclature of territorial units for statistics (NUTS) 3 regions for the 2004-2007 period. Aside from proving conditional rental price convergence, we have detected a turnaround in vacancy stocks between the short and the long term. While East German counties and West German independent cities currently exhibit the highest and lowest vacancy rates, respectively, the opposite holds true at equilibrium. Leaning on theoretical suggestions, landlords in well-developed areas have incentives to hold onto vacancies in view of future rent increases. Our results support this idea, which demonstrates the significantly positive impact of household income and net birth rate on the natural vacancy rate.Rental Market; Adjustment Process; Natural Vacancy Rate; Regional Analysis; Germany

Ceria-Based Dual-Phase Membranes for High-Temperature Carbon Dioxide Separation: Effect of Iron Doping and Pore Generation with MgO Template

Dual-phase membranes for high-temperature carbon dioxide separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement these membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce0.8Sm0.2O2−δ (SDC) and Ce0.8Sm0.19Fe0.01O2−δ (FSDC) ceramic powders were used to form the skeleton in dual-phase membranes. The use of MgO as an environmentally friendly pore generator allows control over the membrane porosity and microstructure in order to compare the effect of the membrane’s ceramic phase. The ceramic powders and the resulting membranes were characterized using ICP-OES, HSM, gravimetric analysis, SEM/EDX, and XRD, and the carbon dioxide flux density was quantified using a high-temperature membrane permeation setup. The carbon dioxide permeability slightly increases with the addition of iron in the FSDC membranes compared to the SDC membranes mainly due to the reported scavenging effect of iron with the siliceous impurities, with an additional potential contribution of an increased crystallite size due to viscous flow sintering. The increased permeability of the FSDC system and the proper microstructure control by MgO can be further extended to optimize carbon dioxide permeability in this membrane system.DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berli

Horizontal and Vertical Firm Networks, Corporate Performance and Product Market Competition

This paper sheds new light on the assessment of firm networks via multiple directorships in terms of corporate firm performance. Using a large sample of European listed firms in the period from 2003 to 2011 and system GMM we find a significant compensation effect on corporate firm performance for the initial negative effect of horizontal multiple directorships by product market competition. In markets with effective competition, horizontal multiple directorships turn out to be an efficient mechanism to increase firm performance and thus assure competitive advantages. By contrast, linkages between up- and downstream firms have no significant influence on financial performance, irrespective of the level of competition intensity

Horizontal and Vertical Firm Networks, Corporate Performance and Product Market Competition

This paper sheds new light on the assessment of firm networks via multiple directorships in terms of corporate firm performance. Using a large sample of European listed firms in the period from 2003 to 2011 and system GMM we find a significant compensation effect on corporate firm performance for the initial negative effect of horizontal multiple directorships by product market competition. In markets with effective competition, horizontal multiple directorships turn out to be an efficient mechanism to increase firm performance and thus assure competitive advantages. By contrast, linkages between up- and downstream firms have no significant influence on financial performance, irrespective of the level of competition intensity

KIC InnoEnergy Project Neptune: development of a floating LiDAR buoy for wind, wave and current measurements

The KIC-InnoEnergy project “NEPTUNE” develops a floating Lidar buoy and a hindcast- and forecast model for wind- wave- and current measurements of offshore wind farms. In this paper just the lidar buoy is presented and discussed: Main challenges, the design ideas and the steps to develop, test and prototype this product, which – according to the KIC-InnoEnergy project idea – should be commercialized after the project end, foreseen for the end of 2014. KIC-InnoEnergy is funded from the European Institute of Technology, EIT.Peer ReviewedPostprint (published version

Statistical load estimation using a nacelle-based lidar system

The paper presents the results of statistical load analyses based on data measured at the 5MW AREVA Wind M5000 onshore prototype. Measurements with standard meteorological measurement devices are analysed and compared to measurements with a pulsed LIDAR system which is enhanced with a multi-purpose scanning device installed on the top of the nacelle of the turbine. Based on these measurements statistical summaries of relevant meteorological parameters have been used for normative procedures to calculate the mechanical loads which occur at the wind energy turbine. It could be verified that LIDAR systems can substitute standard measurement devices for a load estimation of wind energy turbines

The functional genome of CA1 and CA3 neurons under native conditions and in response to ischemia

<p>Abstract</p> <p>Background</p> <p>The different physiological repertoire of CA3 and CA1 neurons in the hippocampus, as well as their differing behaviour after noxious stimuli are ultimately based upon differences in the expressed genome. We have compared CA3 and CA1 gene expression in the uninjured brain, and after cerebral ischemia using laser microdissection (LMD), RNA amplification, and array hybridization.</p> <p>Results</p> <p>Profiling in CA1 vs. CA3 under normoxic conditions detected more than 1000 differentially expressed genes that belong to different, physiologically relevant gene ontology groups in both cell types. The comparison of each region under normoxic and ischemic conditions revealed more than 5000 ischemia-regulated genes for each individual cell type. Surprisingly, there was a high co-regulation in both regions. In the ischemic state, only about 100 genes were found to be differentially expressed in CA3 and CA1. The majority of these genes were also different in the native state. A minority of interesting genes (e.g. inhibinbetaA) displayed divergent expression preference under native and ischemic conditions with partially opposing directions of regulation in both cell types.</p> <p>Conclusion</p> <p>The differences found in two morphologically very similar cell types situated next to each other in the CNS are large providing a rational basis for physiological differences. Unexpectedly, the genomic response to ischemia is highly similar in these two neuron types, leading to a substantial attenuation of functional genomic differences in these two cell types. Also, the majority of changes that exist in the ischemic state are not generated de novo by the ischemic stimulus, but are preexistant from the genomic repertoire in the native situation. This unexpected influence of a strong noxious stimulus on cell-specific gene expression differences can be explained by the activation of a cell-type independent conserved gene-expression program. Our data generate both novel insights into the relation of the quiescent and stimulus-induced transcriptome in different cells, and provide a large dataset to the research community, both for mapping purposes, as well as for physiological and pathophysiological research.</p

Lidars and wind turbine control

Reducing mechanical loads caused by atmospheric turbulence and energy optimization in the presence of varying wind are the key issue for wind turbine control. In terms of control theory changes in the inflowing wind field as gusts, varying shears and directional changes represent unknown disturbances. However, conventional feedback controllers can compensate such excitations only with a delay since the disturbance has to be detected by its effects to the turbine. This usually results in undesired loads and energy losses of wind turbines. From the control theory point of view disturbance rejection can be improved by a feedforward control if the disturbance is known. Not fully covered by theory, but used in practice is the further advantage of knowing the disturbance in the future, e.g. in chassis suspension or in daily life when vision is used to circumnavigate obstacles with a bicycle. In a similar way wind field measurements with remote sensing technologies such as Light Detection and Ranging (LIDAR) might pave the way for predictive wind turbine control strategies aiming to increase energy yield and reduce excessive loads on turbine components. Remote sensing offers wind speed tracking at various points in space and time in advance of reaching the turbine and before hitting sensors at the blades or nacelle. This provides the control and safety system with sufficient reaction and processing time

Prospects of optimization of energy production by LIDAR assisted control of wind turbines

In the presented work two approaches to increase the energy production of wind turbines are studied assuming the usage of a wind speed measurement provided by a nacelle based LIDAR system: The first approach uses the knowledge of the incoming wind speed to assist variable speed control. The second approach uses the wind direction information measured by a LIDAR system for yaw control. From this first analysis only marginal benefit can be gained by the LIDAR assisted speed control, but an increase of energy production by a couple of percent can be expected by LIDAR assisted yaw control