The MFS for numerical boundary identification in two-dimensional harmonic problems

In this study, we briefly review the applications of the method of fundamental solutions to inverse problems over the last decade. Subsequently, we consider the inverse geometric problem of identifying an unknown part of the boundary of a domain in which the Laplace equation is satisfied. Additional Cauchy data are provided on the known part of the boundary. The method of fundamental solutions is employed in conjunction with regularization in order to obtain a stable solution. Numerical results are presented and discussed.     

Aromatic diazenes containing azulen-1-yl moieties Part 2: The synthesis,characterization, electronic spectra and basicity of novel,bis aromatic diazenes containing two azulen-1-yl moieties

Bis aromatic diazenes which possess either two identical or two different azulene-1-yl groups substituted at either 1,3 or 1,4-positions in the bridging phenylene moiety were synthesized in good yield via diazotization of the 3- or 4-azulen-1-ylazo-phenylamines followed by coupling with azulene in a buffered medium. The electronic spectra of the synthesized compounds were analyzed by comparison with those of previously published compounds. The isosbestic points obtained by protonation of the compounds enabled their pK_a values to be determined.     

Micro-structured nuclear fuel and novel nuclear reactor concepts for advanced power production

Many applications (e.g. terrestrial and space electric power production, naval, underwater and railroad propulsion and auxiliary power for isolated regions) require a compact-high-power electricity source. The development of such a reactor structure necessitates a deeper understanding of fission energy transport and materials behavior in radiation dominated structures. One solution to reduce the greenhouse-gas emissions and delay the catastrophic events' occurrences may be the development of massive nuclear power. The actual basic conceptions in nuclear reactors are at the base of the bottleneck in enhancements. The current nuclear reactors look like high security prisons applied to fission products. The micro-bead heterogeneous fuel mesh gives the fission products the possibility to acquire stable conditions outside the hot zones without spilling, in exchange for advantages – possibility of enhancing the nuclear technology for power production. There is a possibility to accommodate the materials and structures with the phenomenon of interest, the high temperature fission products free fuel with near perfect burning. This feature is important to the future of nuclear power development in order to avoid the nuclear fuel peak, and high price increase due to the immobilization of the fuel in the waste fuel nuclear reactor pools.     

Fourier transform infrared-attenuated total reflection nitrate determination of soil pastes using principal component regression, partial least squares, and cross-correlation

This paper investigates the use of Fourier transform infrared (FTIR) attenuated total reflectance (ATR) spectroscopy as a fast and simple way for direct determination of nitrate concentration in soil pastes, which would assist precision fertilizer placement and reduce nitrate pollution. Eight types of soils are investigated, with nitrate concentrations ranging from 0 to 1000 ppm-N. The spectral region around the nitrate band (1300-1550 cm(-1)) is analyzed by (1) principal component regression (PCR), (2) partial least squares (PLS), and (3) cross-correlation with reference libraries that include spectra of pure ions and/or soils. The main obstacle to accurate nitrate measurement appears to be an interfering band present in calcareous soils. This band, which may be due to carbonate, is located around 1450 cm(-1) and overlaps with the nitrate band centered around 1370 cm(-1). For non-calcareous soils, and in particular for light sandy agricultural soils, PLS and cross-correlation with a reference library containing only spectra of ions in water give similar results (about 8 ppm-N on dry soil basis), while PCR leads to slightly poorer results. When calcareous soils are included in the analysis, the prediction errors are about twice as large. In this case, the best results are obtained using PLS, followed by PCR, while cross-correlation with reference libraries leads to poorer results.     

Magnetoelastic modeling of circular cylindrical shells immersed in a magnetic field: Part II: Implications of finite dimensional effects on the free vibrations

In the context of free vibration analysis of axi-symmetric perfectly electro-conductive circular cylindrical shells, four simplified magnetoelastic load models are investigated. Concerning the model of circular cylindrical shells, a linear theory based on Love-Kirchhoff hypothesis is adopted. Due to the high complexities involving singularity of integral equations, infinite integral domains and excessive time needed to evaluate some kernels, special treatments are designed toward achieving highly efficient and highly accurate numerical computation. The influence of applied magnetic field, thickness ratio and dimensionless radius on free vibrations of circular cylindrical shells are further investigated and pertinent conclusions are outlined.     

Vibration and stability control of robotic manipulator systems consisting of a thin‐walled beam and a spinning tip rotor

Vibration and stability feedback control of a robotic manipulator modeled as a cantilevered thin‐walled beam carrying a spinning rotor at its tip is investigated. The control is achieved via incorporation of adaptive capabilities that are provided by a system of piezoactuators, bonded or embedded into the host structure. Based on converse piezoelectric effect, the piezoactuators produce a localized strain field in response to an applied voltage, and as a result, an adaptive change of vibrational and stability response characteristics is obtained. A feedback control law relating the piezoelectrically induced bending moments at the beam tip with the appropriately selected kinematical response quantities is used, and the beneficial effects of this control methodology upon the closed‐loop eigenvibration characteristics and stability boundaries are highlighted. The cantilevered structure modeled as a thin‐walled beam, and built from a composite material, encompasses non‐classical features, such as anisotropy, transverse shear, and secondary warping, and in this context, a special ply‐angle configuration inducing a structural coupling between flapping‐lagging and transverse shear is implemented. It is also shown that the directionality property of the material of the host structure used in conjunction with piezoelectric strain actuation capability, yields a dramatic enhancement of both the vibrational and stability behavior of the considered structural system. © 2002 Wiley Periodicals, Inc.     

A comprehensive analysis of the state of stress of elastic anisotropic flat plates using refined theories

Summary This paper establishes, on a quantitative basis, the correlation between two apparently different higher-order theories of anisotropic plates. In addition it provides a strong mathematical tool allowing one to determine, in an exact and unified manner, the state of stress of orthotropic shear deformable rectangular plates exhibiting a variety of edge conditions.With 7 Figure     

Synthesis of libraries of 16beta-aminopropyl estradiol derivatives for targeting two key steroidogenic enzymes

Two libraries, each consisting of 48 16beta-aminopropyl estradiol derivatives, phenols and sulfamates, respectively, were synthesized by solid-phase parallel chemistry through a seven-step reaction sequence. Following the attachment of a C18-steroid sulfamate precursor on a trityl chloride resin, diversity elements were first introduced on the 16beta-aminopropyl chain of the steroid by acylation reactions with eight Fmoc-amino acids. After deprotection, the free amine function of the resulting compounds was reacted with six carboxylic acids for the introduction of a second diversity level. The two variants employed for the cleavage of compounds from the solid support, acidic and nucleophilic, allowed the corresponding libraries of sulfamate and phenol derivatives in yields of 8-50 % and 13-58 % to be obtained with an average HPLC purity of 94 % and 91 %, respectively. Potent steroid sulfatase inhibitors and interesting SAR results were generated from the screening of the sulfamate library. Furthermore, moderate inhibitors of type 1 17beta-HSD resulted from the partial screening of phenol library. Thus, these two categories of compounds were synthesized to rapidly identify potential inhibitors of steroid biosynthesis for the hormonal therapy of estrogen-dependent diseases, and also to demonstrate the versatility and efficiency of the recently developed sulfamate linker.     

Enhanced Bio-Electrochemical Reduction of Carbon Dioxide by Using Neutral Red as a Redox Mediator

Microbial electrosynthetic cells containing Methylobacterium extorquens were studied for the reduction of CO₂ to formate by direct electron injection and redox mediator-assisted approaches, with CO₂ as the sole carbon source. The formation of a biofilm on a carbon felt (CF) electrode was achieved while applying a constant potential of −0.75 V versus Ag/AgCl under CO₂-saturated conditions. During the biofilm growth period, continuous H₂ evolution was observed. The long-term performance for CO₂ reduction of the biofilm with and without neutral red as a redox mediator was studied by an applied potential of −0.75 V versus Ag/AgCl. The neutral red was introduced into the systems in two different ways: homogeneous (dissolved in solution) and heterogeneous (electropolymerized onto the working electrode). The heterogeneous approach was investigated in the microbial system, for the first time, where the CF working electrode was coated with poly(neutral red) by the oxidative electropolymerization thereof. The formation of poly(neutral red) was characterized by spectroscopic techniques. During long-term electrolysis up to 17 weeks, the formation of formate was observed continuously with an average Faradaic efficiency of 4 %. With the contribution of neutral red, higher formate accumulation was observed. Moreover, the microbial electrosynthetic cell was characterized by means of electrochemical impedance spectroscopy to obtain more information on the CO₂ reduction mechanism.     

Base oils of high aromatic,long branched aliphatic pyromellitic esters

The present paper deals with the synthesis of some tetraesters with a mixed structure of pyromellitic dianhydride, and with their characterisation as potential base oils. These esters are made on the basis of a long branched aliphatic alcohol, such as isotridecanol, and an alcohol with aromatic content, such as 2‐phenoxy‐ethanol. The variation of the principal properties as a function of both the length of the aliphatic chain introduced by the aliphatic alcohol, and the aromatic content introduced by the aryl‐alkyl alcohol has been assessed and the potential for viable products with a wide range of viscosity values has been examined. The enhanced aryl content is shown to induce superior thermal behaviour. These products present good test results and, thereby, demonstrate their versatility.