A Modular Superconducting Generator for Offshore Wind Turbines

In this study, a new claw-pole type transverse flux superconducting generator topology is presented. The machine has a stationary superconducting field winding, which eliminates electrical brushes and cryocouplers. The machine is specifically designed for low-speed high torque applications such as large offshore wind turbines. The proposed machine is robust and has a modular structure. A 30 kW, 100 rpm prototype is planned to be manufactured to prove the concept. MgB2, YBCO, and BSSCO wires are compared in terms of wire length, operating temperature, and critical temperature. The magnetic flux penetrating into superconducting wire has been simulated using 3D FEA software. Moreover, mechanical loads are estimated and the deflections in the structure are analysed.     

Depth Dependence of Nanoindentation Pile-Up Patterns in Copper Single Crystals

A study of the dependence of nanoindentation pile-up patterns on the indentation load and crystallographic orientation is presented. Three different orientations—(001), (011), and (111)—of single crystal copper were investigated. Experiments were conducted on a CSM ultra-nanoindentation tester using a Berkovich tip. The topographic images were obtained using an atomic force microscope. The evolution of pile-up patterns with different applied loads was observed. The results show that for applied loads equal to 0.45 mN and smaller the pile-up patterns do not depend on the crystallographic orientation of the indented surface; instead, they depend on the tip’s geometry. On the other hand, in the case of indentation loads bigger than 2 mN, pile-up patterns on the surfaces of (001)-, (011)-, and (111)-oriented single crystals have fourfold, twofold, and sixfold (or threefold) symmetry, respectively. An intermediate state was also reported. Furthermore, a detailed analysis of residual impressions with maximal applied loads equal to 2 mN and bigger reveals that both pile-up and sink-in patterns are present.     

A thermodynamic criterion for selection of working fluid for subcritical and supercritical domestic micro CHP

A thermodynamic criterion for selection of a fluid both for subcritical and supercritical organic Rankine cycle has been proposed. Theoretical performances of few fluids have been comparatively assessed for use in low-temperature domestic organic Rankine cycle micro systems. Of the 20 fluids investigated, ethanol, R123 and R141b appear as the most suitable for small scale domestic CHP applications.     

Frequency division multiplexed microwave and baseband digitaloptical fiber link for phased array antennas

A frequency-division multiplexed optical fiber link is described in which microwave (1-8 GHz) and baseband digital (1-10 Mb/s) signals are combined electrically and transmitted through a direct-modulation microwave optical link. The microwave signal does not affect bit error rate (BER) performance of the Manchester-coded baseband digital data link. The baseband digital signal affects microwave signal quality by generating second-order intermodulation noise. The intermodulation noise power density is found to be proportional to both the microwave input power and the digital input power, enabling the system to be modeled as a mixer (AM modulator). The conversion loss for the digital signal is approximately 68 dB for a 1-GHz microwave signal and is highly dependent on the microwave frequency, reaching a minimum value of 41 dB at 4.5 GHz corresponding to the laser diode relaxation oscillation frequency. It is shown that Manchester coding on the digital link places the intermodulation noise peak away from microwave signal, preventing degradation of close-carrier phase noise (<1 kHz offset). A direct trade-off between intermodulation noise and digital link margin is developed to project system performance     

Maximum principle for optimal control of two-directionally continuous linear repetitive processes

In the paper, maximum principle for a two-directionally continuous variant of a linear autonomous repetitive process with cost functional depending on a fixed “end-function” is obtained. Maximum condition has a pointwise form, a conjugate system has a Fornasini-Marchesini form. The result is derived from the extremum principle for smooth-convex problems, due to Ioffe and Tikhomirov.     

The Impact of PAHs Contamination on the Physicochemical Properties and Microbiological Activity of Industrial Soils

The aim of this article is the study of the potential relationships between PAHs contamination, physicochemical parameters, and microbial activity in industrial soils. The research was based on two series of measurements. The first was conducted in June 2013 and the second in November 2013. Samples used in study were collected from the area of fuel handling and a loading station, located in the Silesia region of Poland. All collected samples were characterized by the following analytical procedures: PAHs content analysis, the basic physical and chemical parameters determinations (pH, CEC, humic acids content, TC, TN, TP) and microbial activity analysis. The obtained results were also subjected to statistical analysis, based on the Pearson's correlation coefficient calculations.

Results collected during described above procedure show that: the PAHs content was highly positively correlated with C and N contents (p < 0.001) and moderately correlated with humic acids and P contents (p < 0.01). This phenomenon confirms the thesis that the increase of soil organic matter content promotes accumulation of hydrophobic organic compounds such as PAHs. Microbiological analysis shows that bacteria from the mesophilic group are most resistant to PAHs contamination. This information indicates that the organisms belonging to this group should be considered as potentially useful in the soil bioremediation processes.     

The Impact of Zeta Potential and Physicochemical Properties of TiO2‐Based Nanocomposites on Their Biological Activity

The aim of this research was to observe the relationship between zeta potential, morphology, surface area, porosity, chemical composition, and ecotoxicity of nanocomposite powders such as Au/TiO₂, Ag₂O/TiO₂, PdO/TiO₂, Ag/TiO₂/SiO₂, Ag/N(C)TiO₂, and SiO₂/TiO₂ from which Ag₂O/TiO₂, Ag/N(C)/TiO_2, and Ag/TiO₂/SiO₂ were exhibiting good antimicrobial properties. It was observed, that nanomaterials characterized by similar morphology and zeta potential revealed the similar toxic behavior. The samples of higher agglomeration and higher zeta potential, especially Ag/TiO₂/SiO₂ xerogel and TiO₂/SiO₂ aerogel were generally less ecotoxic to water organisms and plants. They were also not genotoxic in concentrations up to 500 and 250 mg/L, respectively.     

Bang–bang principle for linear and non-linear Goursat–Darboux problems

In this paper, the bang-bang principle for a control system described by a system of non-linear (in control) non-autonomous partial differential equations of hyperbolic type (the so-called Goursat-Darboux problem) is proved. As a particular case the bang-bang principle for a linear system is obtained. The method used for the proof is based on some properties of the Aumann integral.