Study of a BGO calorimeter using electron and hadron beams from 1 to 50 GeV

A calorimeter of 25 bismuth germanate (BGO) crystals equipped with silicon photodiode readout has been tested at the CERN SPS in the energy range 1–50 GeV. The response for electrons has been shown to be linear in this energy range and the rms resolution obtained ( ) is approximately 1%, for E > 4 GeV. The electron/pion separation was found to be better than 1:500 in the energy range 1–20 GeV. Data on lateral and longitudinal shower development were compared with the results of a Monte Carlo simulation using the SLAC-EGS program and found to be in good agreement.     

Characterization of Ceramic Foam Filters Used for Liquid Metal Filtration

In the current study, the morphology including tortuosity, and the permeability of 50-mm thick commercially available 30, 40, 50, and 80 pores per inch (PPI) alumina ceramic foam filters (CFFs) have been investigated. Measurements have been taken of cell (pore), window, and strut sizes, porosity, tortuosity, and liquid permeability. Water velocities from ~0.015 to 0.77 m/s have been used to derive both first-order (Darcy) and second-order (Non-Darcy) terms for being used with the Forchheimer equation. Measurements were made using 49-mm “straight through” and 101-mm diameter “expanding flow field” designs. Results from the two designs are compared with calculations made using COMSOL 4.2a^® 2D axial symmetric finite element modeling (FEM), as a function of velocity and filter PPI. Permeability results are correlated using directly measurable parameters and compared with the previously published results. Development of improved wall sealing (49 mm) and elimination of wall effects (101 mm) have led to a high level of agreement between experimental, analytic, and FEM methods (±0 to 7 pct on predicted pressure drop) for both types of experiments. Tortuosity has been determined by two inductive methods, one using cold-solidified samples at 60 kHz and the other using liquid metal at 50 Hz, giving comparable results.     

Removal of nitrogen in different wetland filter materials: use of stable nitrogen isotopes to determine factors controlling denitrification and DNRA.

Laboratory incubations with varying O2 and NO3 concentrations were performed with a range of filter materials used in constructed wetlands (CWs). The study included material sampled from functioning CWs as well as raw materials subjected to laboratory pre-incubation. 15N-tracer techniques were used to assess the rates of denitrification versus dissimilatory nitrate reduction to ammonium (DNRA), and the relative role of nitrification versus denitrification in producing N2O. The N2O/(N2 + N2O) product ratio was assessed for the different materials. Sand, shell sand, and peat sustained high rates of denitrification. Raw light-weight aggregates (LWA) had a very low rate, while in LWA sampled from a functioning CW, the rate was similar to the one found in the other materials. The N2O/(N2 + N2O) ratio was very low for sand, shell sand and LWA from functioning CWs, but very high for raw LWA. The ratio was intermediate but variable for peat. The N2O produced by nitrification accounted for a significant percentage of the N2O accumulated during the incubation, but was dependent on the initial oxygen concentration. DNRA was significant only for shell sand taken from a functioning CW, suggesting that the establishment of active DNRA is a slower process than the establishment of a denitrifying flora.     

Saw-based chirp fourier transform and its application to analogue on-board signal processing

This paper reports on the work done at ELAB-RUNIT on surface acoustic wave (SAW) on-board signal processing. The main processing is done by the analogue chirp Fourier transformer (CFT) and its inverse (ICFT). In a CFT, the input signal is transformed from an FDMA format to a TDM format and at the same time filtered by a filter bank. By multiplying and convolving the signal with chirp waveforms, the CFT is implemented by one bandpass cover filter and one chirp filter. The paper demonstrates that SAW reflector array compressors (RAC) built by ELAB-RUNIT have suitable chirp responses and adequate precision for digital satellite communication. Two applications are described. An on-board multicarrier demodulator (MCD) for 9·6 kb/s QPSK carriers and a processor for filtering, routeing and beam steering (FROBE) for flexible transparent repeaters. For MCDs the use of SAW CFTs leads to a power consumption for demultiplexing and A/D conversion of 15 mW per carrier with room for improvements. For transparent paylods, the FROBE leads to more flexibility and narrower guardbands than can be obtained by other analogue processors.     

Biaxial strength and slow crack growth in porous alumina with silica sintering aid

Biaxial strength, fracture toughness and subcritical crack growth are reported for coarse grained porous alumina ceramics. The materials were prepared with a varying amount of a silica sintering aid, which resulted in the formation of a glassy secondary phase at the grain boundaries. Crystalline mullite was additionally found in the material with the highest silica content. The biaxial strength, measured by Ball-on-Ring and Ball-on-3-Balls, was highest for the material without mullite at the grain boundaries, and the biaxial strength decreased with increasing porosity. The fracture toughness of the materials was in the range of 1.7–1.9 MPa m^0.5. Measurements of subcritical crack growth by a modified lifetime method in air and aqueous environments demonstrated a higher crack growth rate in water and acid relative to in air. The effect of porosity and grain boundary phase were discussed in relation to subcritical crack growth and fracture mode in the coarse grained alumina ceramics.     

Computerized analysis of isometric tension studies provides important additional information about vasomotor activity

Concentration-response curves of isometric tension studies on isolated blood vessels are obtained traditionally. Although parameters such as Imax, EC50 and pA2 may be readily calculated, this method does not provide information on the temporal profile of the responses or the actual nature of the reaction curves. Computerized data acquisition systems can be used to obtain average data that represent a new source of otherwise inaccessible information, since early and late responses may be observed separately in detail.     

A Fuzzy Rule‐based Model for the Assessment of Macrobenthic Habitats under Hydropeaking Impact

Hydropeaking presents one of the large impacts on river ecology and is gaining importance because of an increasinlgy volatile energy market with high portions of new renewable energies dependent on local climate conditions. This study presents the application of a fuzzy logic model for the investigation of macrobenthic habitats under hydropeaking conditions in the Norwegian river Surna. Preference data of the three taxa Baetis rhodani, Hydroptila spp. and Allogamus auricollis with distinctively different habitat requirements related to near‐bottom flow forces (high/low forces, and narrow range) are used. These data are transferred into the multivariate fuzzy rule‐based physical habitat model Computer Aided Simulation of Instream flow and Riparia in order to integrate water depth and river bed substrate as additional parameters. Permanently available habitats (persistent habitats) are assessed for different scenarios of hydropeaking operation. It is found that the amount of persistently high‐quality habitat is closely related to the size and range of fluctuations in hydraulic conditions occuring during hydropeaking events. Effects are much more distinct for species with a narrow range of hydraulic preference. The integration of water depth in the simulations has a noticable impact on the amount and quality of predicted habitats. Substrate conditions in the investigation site are homogeneous and, in the specific case considered, do not have a significant impact. The study suggests persistent habitats as a suitable indicator of hydropeaking impact on organisms with low mobility. The persistent habitat approach takes into account that organisms with a low mobility and a distinct range of tolerance related to hydraulic stress tend to settle in areas with permanently stable conditions. Multivariate aspects are accounted through the fuzzy rule‐based approach and do clearly affect habitat predictions. Habitat requirements of species particularly sensitive to hydropeaking are proposed for the investigation and application in the future. Copyright © 2016 John Wiley & Sons, Ltd.     

A failure to communicate: next generation communication requirements, technologies, and architecture for the electric power grid

The power grid engineering community is beginning to recognize a need to fundamentally transform the capabilities of the communication infrastructure that supports power grid operations. Better communications are key to providing improvements in security, efficiency, and reliability. This paper reviews current data communication practices for the grid and describes a new approach to data communications that will help realize the vision of a more resilient and efficient "smart" grid.