Offshore wind power grid connection—The impact of shallow versus super-shallow charging on the cost-effectiveness of public support

Public support for electricity generation from renewable energy sources is commonly funded by non-voluntary transfers from electricity consumers to producers. Apparently, the cost-effective disposition of funds in terms of induced capacity deployment has to be regarded a key criterion for the success of renewable energy policy.     

Evolutionary events in a mathematical sciences research collaboration network

This study examines long-term trends and shifting behavior in the collaboration network of mathematics literature, using a subset of data from Mathematical Reviews spanning 1985–2009. Rather than modeling the network cumulatively, this study traces the evolution of the “here and now” using fixed-duration sliding windows. The analysis uses a suite of common network diagnostics, including the distributions of degrees, distances, and clustering, to track network structure. Several random models that call these diagnostics as parameters help tease them apart as factors from the values of others. Some behaviors are consistent over the entire interval, but most diagnostics indicate that the network’s structural evolution is dominated by occasional dramatic shifts in otherwise steady trends. These behaviors are not distributed evenly across the network; stark differences in evolution can be observed between two major subnetworks, loosely thought of as “pure” and “applied”, which approximately partition the aggregate. The paper characterizes two major events along the mathematics network trajectory and discusses possible explanatory factors.     

A Lateral Restraining Device for Large Telescope Mirrors

Abstract

Telescope mirrors—like every rigid body—have six degrees of freedom (DOFs) to move: translation along three axes of space and rotation around these three axes. Hydraulic support systems, which are designed to hold the mirror in the required best optical shape, have to couple all six DOFs between the mirror and its supporting cell structure. While three DOFs are covered by the axial support system and two DOFs by the lateral support system, the last degree of freedom often remains uncovered. A good example is the lateral support system for the 8 m primary mirror of ESO's Very Large Telescope, which did not couple movements along the horizontal axis between the mirror and its cell and therefore required a lateral restraining device. Based on this example, a general method is shown how to control all degrees of freedom at a given supporting force distribution without any unwanted additional forces. According to the theory of modal control, a hydraulic network is used to decouple the oil flow to the hydraulic actuators and thereby to control the components of the supporting forces independently. The theory may be applied for other hydraulic support systems, too.     

Genome-Wide Investigation of Multifocal and Unifocal Prostate Cancer—Are They Genetically Different?

Prostate cancer is widely observed to be biologically heterogeneous. Its heterogeneity is manifested histologically as multifocal prostate cancer, which is observed more frequently than unifocal prostate cancer. The clinical and prognostic significance of either focal cancer type is not fully established. To investigate prostate cancer heterogeneity, the genetic profiles of multifocal and unifocal prostate cancers were compared. Here, we report observations deduced from tumor-tumor comparison of copy number alteration data of both focal categories. Forty-one fresh frozen prostate cancer foci from 14 multifocal prostate cancers and eight unifocal prostate cancers were subjected to copy number variation analysis with the Affymetrix SNP 6.0 microarray tool. With the investigated cases, tumors obtained from a single prostate exhibited different genetic profiles of variable degrees. Further comparison identified no distinct genetic pattern or signatures specific to multifocal or unifocal prostate cancer. Our findings suggest that samples obtained from multiple sites of a single unifocal prostate cancer show as much genetic heterogeneity and variability as separate tumors obtained from a single multifocal prostate cancer.     

Improved microwave plasma cavity reactor for diamond synthesis at high-pressure and high power density

Microwave plasma assisted synthesis of diamond is experimentally investigated using high purity, 2–5% CH₄/H₂ input gas chemistries and operating at high pressures of 180–240 Torr. A microwave cavity plasma reactor (MCPR) was specifically modified to be experimentally adjustable and to enable operation with high input microwave plasma absorbed power densities within the high-pressure regime. The modified reactor produced intense microwave discharges with variable absorbed power densities of 150–475 W/cm³ and allowed the control of the discharge position, size, and shape thereby enabling process optimization. Uniform polycrystalline diamond films were synthesized on 2.54 cm diameter silicon substrates at substrate temperatures of 950–1150 °C. Thick, freestanding diamond films were synthesized and optical measurements indicated that high, optical-quality diamond films were produced. The deposition rates varied between 3 and 21 μm/h and increased as the operating pressure and the methane concentrations increased and were two to three times higher than deposition rates achieved with the MCPR operating with equivalent input methane concentrations and at lower pressures (≤ 140 Torr) and power densities.     

Influence of oxide scales on heat transfer in secondary cooling zones in the continuous casting process,part 2: determination of material properties of oxide scales on steel under spray-water cooling conditions

In order to model heat transfer from the slab to the cooling agent in the continuous casting process the thermophysical properties of the surface layer must be taken into account. For this purpose thermal conductivities and thermal diffusivities of wustite as well as of two carbon steels were measured. The oxide scale growth for six steels was measured as a function of time and at temperatures between 900 and 1200°C in air and in steam. Complex heterogeneous oxide scales were examined by optical and scanning electron microscopy, by SIMS, as well as by Mössbauer spectroscopy. Segregation of alloying elements in the metal-oxide contact zone was found. Cracks due to thermal stresses result in spalling of the scale. Therefore, a straightforward use of the data for process modelling can principally not be recommended without restrictions.     

Influence of Precursor Densification on Strength Retention of Zirconia-Coated Nextel™ 610 Fibers

Strength degradation of Nextel^™ 610 fibers by continuous liquid phase coating was investigated for four different zirconia precursors. The precursors differed regarding their chemical composition (with or without yttrium), phase composition (amorphous or crystalline), and decomposition behavior. Phase transformation and densification of the films were characterized and found to depend on the kind of precursor. Single fiber Weibull's strength was measured for calcination temperatures between 250° and 1150°C for all precursors. Each precursor had an individual degradation behavior. For an annealing temperature of 1150°C highly damaged (∼1600 MPa) and undamaged (>3300 MPa) fibers were obtained depending on the kind of precursor. Fiber degradation could be correlated to mechanical stresses. Stress concentration due to inhomogeneous film thickness distribution is proposed as the cause of fiber strength degradation. Full strength could be retained for porous coatings or coatings where stresses were reduced by phase transformation.     

Economic and CO2 mitigation impacts of promoting biomass heating systems: An input–output study for Vorarlberg, Austria

This paper reports on an empirical investigation about the economic and CO₂ mitigation impacts of bioenergy promotion in the Austrian federal province of Vorarlberg. We study domestic value-added, employment, and fiscal effects by means of a static input–output analysis. The bioenergy systems analysed comprise biomass district heating, pellet heating, and automated wood chip heating systems, as well as logwood stoves and boilers, ceramic stoves, and buffer storage systems. The results indicate that gross economic effects are significant, regarding both investment and operation of the systems, and that the negative economic effects caused by the displacement of conventional decentralised heating systems might be in the order of 20–40%. Finally, CO₂ mitigation effects are substantial, contributing already in 2004 around 35% of the 2010 CO₂ mitigation target of the Land Vorarlberg for all renewable energy sources.