Magnetoresistance of UPt3

We have performed measurements of the temperature dependence of the magnetoresistance up to 9 T in bulk single crystals of UPt3 with the magnetic field along the b axis, the easy magnetization axis. We have confirmed previous results for transverse magnetoresistance with the current along the c axis, and report measurements of the longitudinal magnetoresistance with the current along the b axis. The presence of a linear term in both cases indicates broken orientational symmetry associated with magnetic order. With the current along the c axis the linear term appears near 5 K, increasing rapidly with decreasing temperature. For current along the b axis the linear contribution is negative.Comment: 6 pages, 3 figures, submitted to Quantum Fluids and Solids Conference (QFS 2006

Heterogeneity of adipose tissue in development and metabolic function.

Adipose tissue is a central metabolic organ. Unlike other organs, adipose tissue is compartmentalized into individual depots and distributed throughout the body. These different adipose depots show major functional differences and risk associations for developing metabolic syndrome. Recent advances in lineage tracing demonstrate that individual adipose depots are composed of adipocytes that are derived from distinct precursor populations, giving rise to different populations of energy-storing white adipocytes. Moreover, distinct lineages of energy-dissipating brown and beige adipocytes exist in discrete depots or within white adipose tissue depots. In this Review, we discuss developmental and functional heterogeneity, as well as sexual dimorphism, between and within individual adipose tissue depots. We highlight current data relating to the differences between subcutaneous and visceral white adipose tissue in the development of metabolic dysfunction, with special emphasis on adipose tissue expansion and remodeling of the extracellular matrix. Moreover, we provide a detailed overview of adipose tissue development as well as the consensus and controversies relating to adult adipocyte precursor populations

Techno-Economic Assessment of New Material Developments in Central Receiver Solar Power Plants

For the evaluation of functional material developments in the EU-project RAISELIFE, a tool chain of ray tracing, thermal FEM simulation and dynamic system simulation has been created. Multi-year simulations allow considering degradation of optical parameters. With this tool chain, the thermal energy output of a reference plant with one non-selective and one generic selective coating was simulated. The LCOE (Levelized Cost of Electricity) was calculated based on these results. The LCOE of the selective coating is 2.6 % lower, if the same costs are assumed. Furthermore, the ideal recoating interval for the reference system was identified. Finally, it was demonstrated that dynamic system simulation shows benefits to evaluate in-service performance of functional materials as dynamic behavior of solar thermal power plants can change quite significantly, if another coating is used

Solar tower cavity receiver aperture optimization based on transient optical and thermo-hydraulic modeling

A transient simulation methodology for cavity receivers for Solar Tower Central Receiver Systems with molten salt as heat transfer fluid is described. Absorbed solar radiation is modeled with ray tracing and a sky discretization approach to reduce computational effort. Solar radiation re-distribution in the cavity as well as thermal radiation exchange are modeled based on view factors, which are also calculated with ray tracing. An analytical approach is used to represent convective heat transfer in the cavity. Heat transfer fluid flow is simulated with a discrete tube model, where the boundary conditions at the outer tube surface mainly depend on inputs from the previously mentioned modeling aspects. A specific focus is put on the integration of optical and thermo-hydraulic models. Furthermore, aiming point and control strategies are described, which are used during the transient performance assessment. Eventually, the developed simulation methodology is used for the o ptimization of the aperture opening size of a PS10-like reference scenario with cavity receiver and heliostat field. The objective function is based on the cumulative gain of one representative day. Results include optimized aperture opening size, transient receiver characteristics and benefits of the implemented aiming point strategy compared to a single aiming point approach. Future work will include annual simulations, cost assessment and optimization of a larger range of receiver parameters

Efficient modeling of variable solar flux distribution on solar tower receivers by interpolation of few discrete representations

In order to assess the solar radiation on the complex geometry of Solar Tower receivers, usually detailed maps of the flux distribution are generated using optical simulations based on ray tracing techniques. Transient modeling including a large set of such simulations implies very high computational effort. A new methodology is presented which allows for transient assessment of the flux distribution based on a comparatively small set of optical simulations and subsequent interpolations. For this purpose, two different discretization grids are used: a set of uniformly distributed solar vector nodes on the sky hemisphere and a set of different heliostat field fractions being on focus. For the interpolation in the sky discretization, three different techniques are introduced and compared in terms of accuracy. Partly defocused heliostat fields as well as complex aiming strategies can be readily taken into account by the presented approach. The methodology is validated by means of two exemplary test setups (PS10 and Gemasolar). The accuracy of the different interpolation techniques depending on the refinement of the discretization grids is assessed with appropriate error measures. Depending on the temporal resolution of the transient application, the computational effort can be reduced by several orders of magnitude compared to a direct simulation of the flux distribution for every time step. In addition to the quantitative validation, the use of the developed methodology in conjunction with a thermo-hydraulic simulation is demonstrated by means of the PS10 setup

Hydration behavior and dynamics of water molecules in graphite oxide

In contrast to graphite intercalation compounds, graphite oxide GO is hydrophilic. However, the information about the mobility of the water molecules is still sparse. We show in this report that the degree of hydration and the kinetics of water uptake depend crucially on the preparation and aging conditions. The best sample we have ever got shows layer distances of 8, 9 and 11.5 at relative humidities of 45, 75 and 100 , respectively. With time of flight TOF neutron scattering V3 NEAT spectrometer diffusion processes for rotation and translation have been investigated in the temperature range 220 320 K with an energy resolution of 93 amp; 956;eV. Quasi elastic scattering was observed for all temperatures. Three types of motion can be sorted out. The first one is a translational motion of water molecules in pores between the GO particles for samples equilibrated at 100 relative humidity. Samples equilibrated at 45 and 75 relative humidity do not show this type of water. They exhibit two types of localized motions with different activation energies. We try to assign one type of these motions to confined water molecules encapsulated in the interlayer space between the functional groups attached to the carbon gri

Virtual process chain of sheet molding compound: Development, validation and perspectives

A virtual process chain for sheet molding compound (SMC) composites is established and validated by means of experimental investigations on a demonstrator structure. The flow in the compression molding step is simulated via a Coupled-Eulerian-Lagrangian approach using an anisotropic non-Newtonian fluid flow model. Evolution of the fiber orientation distribution (FOD) is described by Jeffery's equation. The predicted FOD is mapped to structural simulations employing a neutral data format. A mean-field anisotropic damage model is used to predict the damage evolution in the demonstrator. Simulated FOD at the end of the compression molding is validated by computer tomography. Structural simulations are validated by means of a cyclic four-point bending test on the demonstrator. The predicted results show increased accuracy with the experiments by transferring FOD data within the virtual process chain. Critical points of high damage concentrations leading to failure agree with the experimental observations