Hermite matrix in Lagrange basis for scaling static output feedback polynomial matrix inequalities

Using Hermite's formulation of polynomial stability conditions, static output feedback (SOF) controller design can be formulated as a polynomial matrix inequality (PMI), a (generally nonconvex) nonlinear semidefinite programming problem that can be solved (locally) with PENNON, an implementation of a penalty and augmented Lagrangian method. Typically, Hermite SOF PMI problems are badly scaled and experiments reveal that this has a negative impact on the overall performance of the solver. In this note we recall the algebraic interpretation of Hermite's quadratic form as a particular Bézoutian and we use results on polynomial interpolation to express the Hermite PMI in a Lagrange polynomial basis, as an alternative to the conventional power basis. Numerical experiments on benchmark problem instances show the improvement brought by the approach, in terms of problem scaling, number of iterations and convergence behaviour of PENNON.     

Synthesis and characterization of poly(N-(2-(thiophen-3-yl)methylcarbonyloxyethyl)maleimide) and its spectroelectrochemical properties

A new monomer; N-(2-(thiophen-3-yl)methylcarbonyloxyethyl) maleimide (NMT) was synthesized. The chemical structure of the monomer was characterized by Nuclear Magnetic Resonance (¹H-NMR) and Fourier Transform Infrared (FTIR) Spectroscopy. Electrochemical polymerization of NMT was performed in acetonitrile (AN)/borontrifloride ethylether (BFEE) solvent mixture (1:1, v/v) where tetrabutylammonium tetrafluoroborate (TBAFB) was utilized as the supporting electrolyte. The resulting conducting polymer was characterized by Fourier Transform Infrared (FTIR) Spectroscopy, thermal analyses and Scanning Electron Microscopy (SEM). Electrical conductivity was measured by the four-probe technique. The spectroelectrochemical behavior and switching ability of P(NMT) film were investigated by UV–Vis spectrophotometry. P(NMT) revealed color changes between yellow and blue in the reduced and oxidized states respectively.     

Distributed multilevel optimization for complex structures

Optimization problems concerning complex structures with many design variables may entail an unacceptable computational cost. This problem can be reduced considerably with a multilevel approach: A structure consisting of several components is optimized as a whole (global) as well as on the component level. In this paper, an optimization method is discussed with applications in the assessment of the impact of new design considerations in the development of a structure. A strategy based on fully stressed design is applied for optimization problems in linear statics. A global model is used to calculate the interactions (e.g., loads) for each of the components. These components are then optimized using the prescribed interactions, followed by a new global calculation to update the interactions. Mixed discrete and continuous design variables as well as different design configurations are possible. An application of this strategy is presented in the form of the full optimization of a vertical tail plane center box of a generic large passenger aircraft. In linear dynamics, the parametrization of the component interactions is problematic due to the frequency dependence. Hence, a modified method is presented in which the speed of component mode synthesis is used to avoid this parametrization. This method is applied to a simple test case that originates from noise control.     

Preparation and characterization of Cr- and Fe-pillared bentonites by using CrCl3, FeCl3, Cr(acac)3 and Fe(acac)3 as precursors

Four pillared bentonites (Cr-PILB, Cr(acac)₃-PILB, Fe-PILB and Fe(acac)₃-PILB were prepared and characterized by X-ray diffraction (XRD), nitrogen sorption measurements and thermogravimetric (TG) analysis. The surface acidities of the samples and their structures were also investigated in the gas phase adsorption data of pyridine by the aid of FT-IR spectroscopic techniques. The XRD data and FT-IR spectra of the samples reflected mainly the structure of bentonite. The nitrogen adsorption–desorption isotherms of the samples were Type II shaped and showed in general mesoporous structures with pore openings of 4 nm. Two steps mass losses were observed in the TGA thermograms of B, Cr-PILB and Fe-PILB, while three steps mass losses were detected in the case of Cr(acac)₃-PILB and Fe(acac)₃-PILB. IR study by the adsorption of pyridine on the samples showed both Lewis and Brönsted acid sites on their surfaces.     

Orthonormal Basis Functions for Continuous-Time Systems and Lp Convergence

In this paper, model sets for linear-time-invariant continuous-time systems that are spanned by fixed pole orthonormal bases are investigated. These bases generalize the well-known Laguerre and two-parameter Kautz cases. It is shown that the obtained model sets are everywhere dense in the Hardy space H ₁(Π) under the same condition as previously derived by the authors for the denseness in the (Π is the open right half plane) Hardy spaces H _p(Π), 1<p<∞. As a further extension, the paper shows how orthonormal model sets, that are everywhere dense in H _p(Π), 1≤p<∞, and which have a prescribed asymptotic order, may be constructed. Finally, it is established that the Fourier series formed by orthonormal basis functions converge in all spaces H _p(Π) and (D is the open unit disk) H _p(D), 1<p<∞. The results in this paper have application in system identification, model reduction, and control system synthesis. Date received: June 16, 1998. Date revised February 4, 1999.     

A novel indicator system for catalytic spectrophotometric determination and speciation of inorganic selenium species （Se（Ⅳ）, Se（Ⅵ）） at trace levels in natural lake and river water samples

A novel catalytic kinetic method is proposed for the determination of Se(IV), Se(VI), and total inorganic selenium in water based on the catalytic effect of Se(IV) on the reduction of Celestine blue by sodium sulfide at pH 7.0 phosphate buffer. The fixed-time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the two calibration graphs are linear with a good correlation coefficient in the range 2–20 and 20–200 μg·L⁻¹ of Se(IV) for the fixed-time method at 30°C. The experimental and theoretical detection limits of the developed kinetic method were found to be 0.21 and 2.50 μg·L⁻¹ for the fixed-time method (3 min). All of the variables that affect the sensitivity at 645 nm were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se(IV) determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the strongly cation exchange resin such as Amberlite IR120 plus as long as chelating agents of thiourea and thiosulphate. The proposed kinetic method was validated statistically and through recovery studies in natural water samples. The relative standard deviations (RSDs) for ten replicate measurements of 2, 10, and 20 μg·L⁻¹ of Se(IV) change between 0.35% and 5.58%, while the RSDs for ten replicate measurements of 3, 6, and 12 μg·L⁻¹ of Se(VI) change between 0.49% and 1.61%. Analyses of a certified standard reference material (NIST SRM 1643e) for selenium using the fixed-time method showed that the proposed kinetic method has good accuracy. The Se(IV), Se(VI), and total inorganic selenium in lake and river water samples have been successfully determined by this method after selective reduction of Se(VI) to Se(IV).     

Effects of porosity and related interstitial phase morphology difference on the grindability of clinkers

The effects of regional clinker porosity and interstitial phase morphology differences on grindability of clinkers have been investigated within the scope of this study. Porosity and phase characteristics of two clinkers from different furnaces which are using the same raw materials were determined by the application of image processing techniques on SEM images of polished surfaces. Comparison of interstitial phase compositions of two clinkers showed that, clinkers with similar phase compositions may have different grindability due to the porosity and phase morphology differences. Porous clinkers usually exhibit a dendritic interstitial phase morphology with an improved grindability. Increasing porosity also leads to greater incidence of the dendritic morphology in porous regions and lower incidence of alkali in the aluminate in dendritic regions.     

Evaluation of sponging and antipyretic medication to reduce body temperature in febrile children

A case of large fronto-temporo-parietal epidural hematoma associated with ipsilateral retrobulbar hematoma is reported. A 24-year-old man soon after a head injury due to a traffic accident became comatose with anisocoria and hemiplegia and developed exophthalmos, conjuctival chemosis, downward and lateral displacement of the eyeball. CT scan of the brain and the orbit showed the large epidural clot communicating with an ipsilateral retrobulbar hematoma through a sphenoid bone fracture. The patient underwent emergency surgery. Postoperatively, he improved and was discharged in good conditions. On follow-up one month later he was symptoms free. The available literature is reviewed: our case seems to be the fifth reported.