Ray-casting and block model conversion using a spatial index

A spatial index is a data structure designed to facilitate spatial search, exemplified by the point-in-polyhedron inclusion problem. The 3D extensible cell (EXCELL) index is presented together with algorithms for spatial search and for converting a complex polyhedron (boundary representation) into an octree-like block model. We illustrate the techniques by an application to geometric mine modelling and demonstrate the efficiency of the approach by practical experiments.     

Room temperature photo-activation of methane on TiO2 supported molybdena

Methane is activated at room temperature and atmospheric pressure on TiO₂, supported molybdena catalyst excited by band gap illumination. With pure TiO₂, complete oxidation to CO₂ is observed in the presence of oxygen. The deposition of 4% molybdena has a pronounced effect on methane activation, partial oxidation to CO becoming a competing pathway. CO is the major oxidation product if TiO₂ loaded with both MoO₃ and H₄SiW₁₂O₄₀ is used as a catalyst. MoO₃ used alone or in conjunction -with A1₂O₃ or SiO₂ as carriers exhibits poor activity in the photoactivation of methane.     

Boreal freshwater fish diet modifies the plasma lipids and prostanoids and membrane fatty acids in man

The effect of fish diet on 43 healthy male students was studied. They ate a fish-containing meal for 15 weeks on an average of 3.7 times per week. Twenty-one of them voluntarily restricted their lipid intake while the rest ate normally. Controls continued their usual eating habits (19 students). The meals consisted of Finnish freshwater fish (87%) (vendace, pike, perch and rainbow trout) and brackish water fish (13%) (Baltic herring) that provided about 1 g of ω-3 polyunsaturated fatty acids per day (0.25 g eicosapentaenoic acid and 0.55 g docosahexaenoic acid). During the diet, ω-3 fatty acids increased in erythrocyte ghosts and platelets at the expense of ω-6 fatty acids. The concentration of serum cholesterol diminished in those fish consumers who lowered their lipid intake. Apolipo-protein A₁ and B were lowered in both fish-consuming groups. Triglyceride levels also showed a tendency to decrease. The formation of thromboxane B₂ during incubation of whole blood decreased in both fish-consuming groups. The decrease of plasma 6-keto-PGF_1α was not statistically significant, if compared with the controls. The results obtained indicate that a moderate intake of fish-containing meals has some beneficial effects on the plasma lipid and prostanoid metabolism, when coronary heart disease risk factors are considered.     

Oligomerization of phenyl glycidyl ether in the presence of ZnCl2

Summary In the presence of ZnCl₂ phenyl glycidyl ether reacts to different products owing to the ring-opening reaction of the oxirane and the cleavage of the ether bond. Using HPLC and offline mass spectrometry most of the reaction products could be identified.A reaction scheme and the supposed reaction mechanism were described involving the formation of chlorine — containing oligomers and low molecular weight by — products resulting from the cleavage of the ether bond of the monomer. Conclusions were drawn for original polyfunctional epoxy resin systems.     

Effect of Flux Materials on the Reaction of Y2O3and SiO2

The solid-state reaction between yttrium oxide and amorphous silicon oxide with a molar ratio 1:1 has been studied. The effect of several flux materials on conversion at different temperatures (900° to 1300°C) has been investigated. Lithium compounds and especially fluoride gave the highest conversions. Fluorides of cations other than lithium were also powerful fluxes. The purity of the oxyorthosilicate formed was studied by different methods.     

Radar‐based structural health monitoring of wind turbine blades: The case of damage localization

This short communication reports on a radar approach for structural health monitoring of wind turbine blades. Therefore, a bistatic frequency‐modulated continuous wave (FMCW) radar in the frequency range from 33.4 to 36.0 GHz has been developed and tested experimentally using a laboratory wind turbine demonstrator. A differential damage localization framework is presented here that exploits signal differences between measurements from the intact and the damaged structure for 3D imaging of the defect. We have achieved the localization of a 30‐mm cut in a glass fiber composite structure as well as the localization of a water pack at the backside of the specimen with a localization error of several centimeters.     

Flexible power generation scenarios for biogas plants operated in Germany: impacts on economic viability and GHG emissions

Biogas plants enable power to be generated in a flexible way so that variable, renewable energy sources can be integrated into the energy system. In Germany, the Renewable Energy Sources Act promotes flexible power generation in biogas plants. Two existing biogas plants in flexible operation were analyzed with respect to economic viability and greenhouse gas (GHG) emissions to assess the feasibility of flexible operation. To do this, a biogas technology simulation model was developed to reproduce the technical design of both biogas plants and to link this design with twelve flexibilization scenarios. The evaluation of the economic viability is based on a discounting method of investment appraisal. For assessing the level of GHG emissions, the life cycle assessment method has been applied. The results show that the profitability of flexibilization is contingent upon premium payments promoting flexibility and direct sales resulting from a higher electrical efficiency of new or additionally installed combined heat and power units. Overall, with respect to profitability, the results of the flexible power generation scenarios are dependent upon the properties of the technical plant, such as its power generation and gas storage capacities. Relative GHG emissions from flexible biogas plants show significantly lower values than for referenced fossil gas–steam power stations. Among the various scenarios, the results reveal that the level of GHG emissions especially depends on the number of operating hours of the additional combined heat and power unit(s). The results of the analyzed biogas plants showed no direct correlation between GHG emissions and the economic benefits. Overall, a flexible power generation of biogas plants may improve the economic viability as well as result in lower GHG emissions in comparison with a conventional base load operation. © 2016 The Authors. International Journal of Energy Research published by John Wiley & Sons Ltd.     

Design of adaptive and nonadaptive quantizers using subjective criteria

Several properties of visual masking have been investigated with a view to their application to adaptive quantization in DPCM-coding. Quantization characteristics for adaptive and nonadaptive quantizers have been designed using subjective criteria. Special stress has been laid on fixing the changeover levels of an adaptive quantizer. A comparison test involving various quantizing strategies demonstrated the efficiency of the developed techniques. Especially with regard to adaptive quantization with 11 levels (3.5 bits) per picture element, which is suitable for the transmission of broad-band TV-signals with 34 Mbits/s, an improvement on comparable methods could be demonstrated.     

Anthocyanins and betalains as light-harvesting pigments for dye-sensitized solar cells

We present the photoelectrochemical properties of dye-sensitized solar cells using natural pigments containing betalains and anthocyanins as sensitizers. The dyes extracted from grape, mulberry, blackberry, red Sicilian orange, Sicilian prickly pear, eggplant and radicchio have shown a monochromatic incident photon to current efficiency (IPCE) ranging from 40% to 69%. Short circuit photocurrent densities (J_sc) up to 8.8 mA/cm², and open circuit voltage (V_oc) ranging from 316 to 419 mV, were obtained from these natural dyes under 100 mW/cm² (AM 1.5) simulated sunlight. The best solar conversion efficiency of 2.06% was achieved with Sicilian prickly pear fruits extract. The influence of pH and co-absorbers on natural sensitizers, were investigated and discussed.     

Solid-state high-resolution 29Si NMR spectroscopy of synthetic 14 Å, 11 Å and 9 Å tobermorites

A new method for the investigation of the structure of silicates - solid-state high-resolution ²⁹Si NMR spectroscopy - was used for the investigation of 14 Å, 11 Å and 9 Å tobermorites prepared under different conditions. It is possible to determine selectively the individual SiO₄ structural units in tobermorites (end groups, chain middle groups, branching sites, etc.) and to draw conclusions about the type and structure of the silicate anions in the lattice. Synthetic 14 Å tobermorite consists predominantly of single chains, the 11 Å and 9 Å tobermorites contain, depending on the method of preparation, double chains and/or single chains.