Method of Power Adaptation for Signals Emitted in a Wireless Network in Terms of Neuro-Fuzzy System

Wireless Personal Communications - Attenuation of the signal propagating between the emitting and receiving antennas in a wireless network requires adaptation of the power of the emitted signal for...     

Novel sub-100 nm surface chemical modification by optical near-field induced photocatalytic reaction

The surface modification is indispensable to facilitate new functional applications of micro/nanofluidics devices. Among many modification techniques developed so far, the photo-induced chemical modification is the most versatile method in terms of robustness, process simplicity, and feasibility of chemical functionality. In particular, the method is useful for closed spaces, such as post-bonded devices. However, the limitation by optical diffraction limit is still a challenging issue in scaling down the pattern sizes to nanoscale. Here, we demonstrated a novel surface modification on sub-100 nm scale utilizing the novel optical near-field (ONF) generated on nanostructures of photocatalyst (TiO₂). The minimum pattern size of 40 nm, which was much smaller than diffraction limit, was achieved using a visible light source (488 nm) and a conventional irradiation setup. The controllability of pattern size by light intensity, the feasibility of functionality, and the non-contact working mode have impacts on surface patterning of post-bonded micro/nanofluidics devices. It is also worthy to note that our results verified for the first time the ONF on nanostructures of non-metal materials and its ability to manipulate the chemical reaction on nanoscale.     

Effect of cation doping on lattice and grain boundary diffusion in superplastic yttria-stabilized tetragonal zirconia

Lattice diffusion coefficients D_l and grain boundary diffusion D_gb coefficients of hafnium were studied for 0.5 and 1 mol% cation-doped yttria-stabilized tetragonal zirconia at the temperature range from 1283 to 1510 °C. The diffusion profiles were determined by two experimental techniques: secondary ion mass spectroscopy and electron microprobe analysis. Additionally the first principle calculations of the electronic states of Zr⁴⁺, dopant cations and O^2? anions and elastic properties in 3Y-TZP were performed. Superplastic strain rate versus stress and inverse temperature was also measured. For 1 mol% doped samples the significant increase of the grain boundary diffusion and superplastic strain rate was observed. Correlations between the calculated ionic net charges and D_gb indicate that enhancement of D_gb was caused by the reduction of ionic bonding strength between metal cation and oxygen anion in zirconia. The new constitutive equation for superplastic flow of yttria-stabilized tetragonal zirconia ceramics was obtained.     

Singular and Hypersingular Integral Equations Techniques for Gyrotron Coaxial Resonators with a Corrugated Insert

For the first time rigorous theory is developed for eigen traveling TM modes in the resonator of the coaxial cavity gyrotron with a corrugated insert. This mathematical model can be applied for any corrugation parameters and wavelengths. Gyrotron simulation software is developed and allows to calculate mode eigenvalues, electromagnetic field components and Ohmic losses for eigen TE and TM modes. Results of the numerical investigations are presented for the ITER relevant 170 GHz coaxial cavity gyrotron developed in Forschungszentrum Karlsruhe, Germany.     

Sulphide-induced stress corrosion cracking and hydrogen absorption of copper in deoxygenated water at 90°C

Stress corrosion cracking (SCC) of oxygen-free phosphorous-alloyed copper was investigated in sulphide- and chloride-containing deoxygenated water at 90°C with sulphide concentrations of 0.001 and 0.00001 M. Several intergranular defects were found in the specimen exposed to the high sulphide environment. Similar defects were not found in the low sulphide environment, where only slight corrosion on grain boundaries and slip lines occurred. Hydrogen content measurements show an increase in hydrogen uptake of the plastically deformed specimens, which is dependent on the sulphide concentration and on plastic deformation of copper. However, the highest hydrogen content was measured in friction stir welds, welded in air without shielding gas, and tested in the high sulphide environment. The embedded oxide particles in the weld metal act as local hydrogen trapping sites and selectively react with the sulphide solution. A relatively thick air-formed oxide film covers the copper canisters when deposited, which transforms into a sulphide film in the repository conditions. Thus, some of the coupon specimens were pre-oxidised. The conversion of the pre-existing Cu₂O film into Cu₂S film occurs quickly and the transformation is almost 100% efficient. The structure and properties of the Cu₂S films, susceptibility of copper to sulphide-induced SCC and hydrogen uptake of copper in reducing, anoxic repository conditions are discussed.     

Hydrogen embrittlement of nodular cast iron

Ferritic nodular cast iron, intended for use as the material for inserts of canisters for long-term geological disposal of spent nuclear fuel, was studied for hydrogen sensitivity. In the canisters, the insert provides the mechanical strength against external loads. Hydrogen was charged from 0.1 N H₂SO₄ solution in free-corrosion tests and under controlled cathodic potential. Hydrogen uptake and trapping were then measured using thermal desorption spectroscopy. The hydrogen desorption rate after hydrogen charging manifests two distinct peaks. Plastic deformation during hydrogen charging increases the hydrogen uptake considerably. Hydrogen reduces the elongation to fracture and time to fracture in slow strain rate testing and constant load testing (CLT), respectively. Especially, the strain rate in CLT is dramatically increased. The appearance of hydrogen-induced cracking in the ferrite phase changes from ductile dimple fracture to brittle cleavage fracture due to hydrogen charging, which initiates from the interphases of the graphite nodules. The results are discussed in terms of the role of hydrogen and the graphite nodules in hydrogen embrittlement of ductile cast iron.     

Design and evaluation of C++ open multi-methods

Multiple dispatch-the selection of a function to be invoked based on the dynamic type of two or more arguments-is a solution to several classical problems in object-oriented programming. Open multi-methods generalize multiple dispatch towards open-class extensions, which improve separation of concerns and provisions for retroactive design. We present the rationale, design, implementation, performance, programming guidelines, and experiences of working with a language feature, called open multi-methods, for C++. Our open multi-methods support both repeated and virtual inheritance. Our call resolution rules generalize both virtual function dispatch and overload resolution semantics. After using all information from argument types, these rules can resolve further ambiguities by using covariant return types. Care was taken to integrate open multi-methods with existing C++ language features and rules. We describe a model implementation and compare its performance and space requirements to existing open multi-method extensions and work-around techniques for C++. Compared to these techniques, our approach is simpler to use, catches more user mistakes, and resolves more ambiguities through link-time analysis, is comparable in memory usage, and runs significantly faster. In particular, the runtime cost of calling an open multi-method is constant and less than the cost of a double dispatch (two virtual function calls). Finally, we provide a sketch of a design for open multi-methods in the presence of dynamic loading and linking of libraries.     

Novel sorbents of ethanol “salt confined to porous matrix” for adsorptive cooling

In this paper a new family of sorbents, specifically designed for ethanol sorption, is presented. The composites were synthesized by a dry impregnation of matrices with an aqueous solution of various salts. The ethanol sorption capacity of the composites, under conditions typical for adsorptive air conditioning cycle, has been measured by using an express method based on the Polanyi principle of temperature invariance. Results obtained show that the best novel composites have the ethanol sorption ability which is higher than that of known ethanol sorbents. The composite LiBr(30 wt.%)/SiO₂ appears to show the highest sorption capacity and an uptake variation Δw = 0.56 and 0.40 g/g for air conditioning and ice making cycles, respectively. They are much larger than those obtained for conventional adsorbents. The correspondent cooling coefficient of performance (COP) was estimated to be 0.66 and 0.61, which is comparable with the COP of the best water sorbents.