Showing papers by "Wrocław University of Technology published in 1999"
TL;DR: In this paper, the transesterification of rapeseed oil by methyl alcohol can be catalysed effectively by basic alkaline-earth metal compounds: calcium oxide, calcium methoxide and barium hydroxide.
528 citations
224 citations
TL;DR: In this article, the cooperative charge transfer among constructive molecules in organic crystals of tetrathiafulvalene-chloranil, i.e., the bidirectional transition between the neutral and ionic phases, can certainly be induced by irradiation of a laser pulse with an 80-fs width.
Abstract: We demonstrate that the cooperative charge transfer among constructive molecules in organic crystals of tetrathiafulvalene-chloranil, i.e., the bidirectional transition between the neutral and ionic phases, can certainly be induced by irradiation of a laser pulse with an 80-fs width. We also report the dynamics of the photoinduced neutral−ionic phase transition by means of the time-resolved spectroscopic technique. Studies using various excitation intensities have shown that the photoconverted fraction (Φ) depends nonlinearly on the excitation intensity. In addition, it has been found that the growth dynamics of the macroscopic domain of the metastable phase strongly depends on the excitation intensity as well. The role of the cooperative charge-transfer interaction in the driving process of this unusual photoeffect is discussed from both the experimental and the theoretical viewpoints.
183 citations
TL;DR: The robotization of the transport process by an elastic manipulator of an elephant trunk type is proposed and the design of an experimental stand and some results of statical and dynamical analysis are presented.
Abstract: This paper presents some problems dealing with the transportation of bulk and liquid materials. The robotization of the transport process by an elastic manipulator of an elephant trunk type is proposed. The design of an experimental stand and some results of statical and dynamical analysis are presented. In conclusion, some proposals describing the possibilities of utilising elastic manipulators for transport purposes are given.
171 citations
TL;DR: In this paper, polysulfone membranes were modified with plasma of CO2 to obtain highly hydrophilic surfaces of acidic character, and it was shown that prolonged treatment caused severe surface degradation, increase of pore size and widening of their distribution.
150 citations
TL;DR: In this paper, a new method of recycling aluminium and aluminium-alloy chips coming from the machining of semi-finished products, which are very difficult to recycle by conventional methods, is presented.
137 citations
TL;DR: In this paper, a fault locating algorithm for series compensated lines is presented, which is developed as a one-end fundamental frequency based technique and offsets both the series compensation effect and the reactance effect resulting from the remote end in-feed.
Abstract: Summary form only given as follows. This paper presents a new, accurate and robust fault locating algorithm for series compensated lines. The algorithm is developed as a one-end fundamental frequency based technique and offsets both the series compensation effect and the reactance effect resulting from the remote end in-feed. The method uses phase coordinates (abc) instead of symmetrical components [012]. The basic algorithm is presented for a line compensated by one three-phase bank of series capacitors. The presented fault locating method has been extensively tested using the EMTP model of a 400 kV 300 km transmission line. The enclosed results demonstrate very high accuracy and robustness of the algorithm.
136 citations
TL;DR: In this paper, it has been determined that the stainless steel/Al2O3 coating system may be substituted by an electrical model comprising three constant phase elements, and the aluminium oxide coating heated at temperature of 500°C remains stable within the period of 1000 hours exposition in Ringer's solution.
133 citations
TL;DR: An approximation algorithm is proposed which has been designed using a non-trivial generalisation of the block elimination properties known for the classic flow shop problem which is able to achieve excellent results for problems up to 200 jobs and 20 machines.
120 citations
01 Dec 1999
TL;DR: In this article, the harmonic vibrational frequencies and infrared intensities of p-nitrophenol as well as geometries of ortho-and para-nipponol, were calculated with density functional theory (DFT), using BLYP functional and 6-31G(d,p) basis set.
Abstract: The harmonic vibrational frequencies and infrared intensities of p-nitrophenol as well as geometries of ortho- and para-nitrophenol, are calculated with density functional theory (DFT), using BLYP functional and 6-31G(d,p) basis set. The calculated (unscaled) spectra are in very good agreement with the gas phase and solid IR spectra of p-nitrophenol. A detailed interpretation of the infrared spectra of p-nitrophenol is reported on the basis of the calculated potential energy distribution (PED). Several reassignments have been made.
103 citations
TL;DR: In this article, a survey of stochastic Markov games with general state spaces is presented. But the authors focus on nonzero-sum games and provide a detailed survey of selected recent results.
Abstract: This chapter discusses stochastic games. We focus on nonzero-sum games and provide a detailed survey of selected recent results. In Section 1, we consider stochastic Markov games. A correlation of strategies of the players, involving “public signals,” is described, and a correlated equilibrium theorem proved recently by Nowak and Raghavan for discounted stochastic games with general state space is presented. We also resport an extension of this result to a class of undiscounted stochastic games, satisfying some uniform ergodicity condition. Stopping games are related to stochastic Markov games. In Section 2, we describe a version of Dynkin’s game related to observation of a Markov process with random assignment mechanism of states to the players. Some recent constributions of the second author in this area are reported. The chapter also provides a brief overview of the theory of nonzero-sum stochastic games and stopping games.
TL;DR: Laccase isolated from Trametes versicolor was immobilized in polyacrylamide gel and used for the conversion of 4-methyl-3-hydroxyanthranilic acid to 2-amino-4,6-dimethyl-3
24 May 1999
TL;DR: In this paper, the singular value decomposition (SVD) was used for the estimation of harmonics in signals, in the presence of high noise, and the proposed approach results in a linear least squares method.
Abstract: The paper examines the singular value decomposition (SVD) for estimation of harmonics in signals, in the presence of high noise. The proposed approach results in a linear least squares method. The methods developed for locating the frequencies as closely spaced sinusoidal signals are appropriate tools for the investigation of power system signals containing harmonics and interharmonics differing significantly in their multiplicity. The SVD approach is a numerical algorithm to calculate the linear least squares solution. The methods can also be applied for frequency estimation of heavy distorted periodical signals. To investigate the methods several experiments have been performed using simulated signals and the waveforms of a frequency converter current. For comparison, similar experiments have been repeated using the FFT with the same number of samples and sampling period. The comparison has proved superiority of the SVD for signals buried in the noise. However, the SVD computation is much more complex than FFT, and requires more extensive mathematical manipulations.
TL;DR: Streptomycete StC had a surprising ability to degrade N-phosphonomethylglycine (glyphosate) in a phosphate-independent manner via C–P bond cleavage accompanied by sarcosine formation.
Abstract: Wild-type Streptomyces sp. strains, able to utilise both naturally occurring and synthetic organophosphonates, were isolated. High levels of inorganic phosphate were necessary for their growth in complete medium as well as in medium, supplemented with phosphonates as the sole carbon or nitrogen source. Isolate StA expressed detectable enzymatic activity against 2-aminoethylphosphonate in vivo. Streptomycete StC had a surprising ability to degrade N-phosphonomethylglycine (glyphosate) in a phosphate-independent manner via C-P bond cleavage accompanied by sarcosine formation.
TL;DR: In this paper, the authors present spatial and seasonal radon concentration changes in the air of two caves in Poland on the basis of measurements during 1995-1997, based on research on radon occurrence in caves carried out for over 20 years.
TL;DR: In this paper, the phase transition between low and high reactivities of catalytic oxidation of CO by oxygen on a platinum (111) single-crystal surface in a gas-flow reactor follows the Langmuir-Hinshelwood reaction mechanism.
Abstract: The catalytic oxidation of CO by oxygen on a platinum (111) single-crystal surface in a gas-flow reactor follows the Langmuir–Hinshelwood reaction mechanism. It exhibits two macroscopic stable steady states (low reactivity: CO-covered surface; high reactivity: O-covered surface), as determined by mass spectrometry. Unlike other Pt and Pd surface orientations no temporal and spatiotemporal oscillations are formed. Accordingly, CO+O/Pt(111) can be considered as one of the least complicated heterogeneous reaction systems. We measured both the macroscopic and mesoscopic reaction behavior by mass spectrometry and photoelectron emission microscopy (PEEM), respectively, and explored especially the region of the phase transition between low and high reactivity. We followed the rate-dependent width of an observed hysteresis in the reactivity and the kinetics of nucleation and growth of individual oxygen and CO islands using the PEEM technique. We were able to adjust conditions of the external control parameters which totally inhibited the motion of the reaction/diffusion front. By systematic variation of these conditions we could pinpoint a whole region of external control parameters in which the reaction/diffusion front does not move. Parallel model calculations suggest that the front is actually pinned by surface defects. In summary, our experiments and simulation reveal the existence of an “experimental” bistable region inside the “computed” bistable region of the reactivity diagram (S-shaped curve) leading to a novel dollar ($)-shaped curve.
TL;DR: The results indicate that the zeta potential and surface charge data alone cannot be used to delineate the electrochemical properties of a given water/moiety interface because similar electrical properties do not necessary mean a similar structure of the interfacial region.
TL;DR: In this article, a facile and selective method for the title transformation is described, where two-phase oxidation of bis-sulfides with hydrogen peroxide catalyzed by vanadium complex of chiral Schiff base leads to the corresponding chiral mono- and bis-Sulfoxides.
Abstract: A facile and selective method for the title transformation is described. The two-phase oxidation of bis-sulfides with hydrogen peroxide catalyzed by vanadium complex of chiral Schiff base leads to the corresponding chiral mono- and bis-sulfoxides. In the case of 1,2-bis(arylthio)ethanes the respective optically active bis-sulfoxides are formed in up to over 95% e.e.
TL;DR: In this paper, the results of semi-empirical quantum-chemical calculations of the first and second-order hyperpolarizabilities (β and γ, respectively) for molecules in the gas phase and in chloroform and aqueous solvents are presented.
TL;DR: In this article, the properties of multilayer two and three-strip asymmetric coupled lines are described using their coupled-mode parameters and experimental results for two 3-dB couplers on ceramic-filled polytetrafluoroethylene and polyimide laminates are presented together with various layered structures of bilevel and trilevel coupled lines.
Abstract: In this paper, the properties of multilayer two- and three-strip asymmetric coupled lines are described using their coupled-mode parameters. Examples of quasi-ideal, microstrip, and coplanar directional couplers designed in monolithic and hybrid microwave integrated-circuit technology, consisting of various layered structures of bilevel and trilevel coupled lines, are presented together with experimental results for two 3-dB couplers on ceramic-filled polytetrafluoroethylene and polyimide laminates.
TL;DR: In this article, the concept of two sensor systems capable of measurements and analysis of butanol/xylene and butanol-toluene mixtures is presented. Butanol and aromatic compounds are classified among the most commonly used there.
Abstract: Organic solvents represent significant class of air pollutants. Mixtures of butanol and aromatic compounds are classified among the most commonly used there. The concept of two sensor systems capable of measurements and analysis of butanol/xylene and butanol/toluene mixtures is presented. Sensor array consists of four commercial, tin oxide based, semiconductor type gas sensors (TGS 800 series). For the sensors characterisation manually operated gas installation is constructed. Feedforward neural networks are developed for appropriate analysis of sensors responses. Both systems provide measurements of several single compounds concentrations with inaccuracy not exceeding 15% of range. Humidity influence on system responses is rejected. Possibility of portable realisation make the systems potential replacement of traditional gas analysing devices, especially in off-laboratory applications.
TL;DR: The statistical analysis of an ionic current signal recorded from a single channel of a biological membrane provides evidence for the non-Markovian character of the channel kinetics of the investigated data.
Abstract: The statistical analysis of an ionic current signal recorded from a single channel of a biological membrane is presented. We find the main characteristics of the ionic current probability density, the closed- and open-state distributions, and the autocorrelation function of the current recordings by using procedures based on the kernel and tail estimators, the bootstrap methodology; and the Zipf plots. The results provide evidence for the non-Markovian character of the channel kinetics of the investigated data.
TL;DR: In this paper, the authors investigated the influence of concentration of tetraethoxysilane, pH of hydrolysis and pH of gelation on the bulk density, specific surface area and porosity of silica aerogels.
Abstract: The synthesis of silica aerogels had been carried out by hydrolysis of tetraethoxysilane (TEOS) as an aerogel precursor in ethanol solution, followed by gelation of the sols obtained and drying under supercritical conditions The influence of concentration of TEOS, pH of hydrolysis and pH of gelation on the bulk density, specific surface area and porosity of silica aerogels were investigated
TL;DR: A series of new 5H-indolo[2,3-b]quinoline derivatives bearing methoxy and methyl groups at C-2 and C-9 was synthesized and evaluated for their antimicrobial and cytotoxic activity.
TL;DR: In this article, a series of microstrip dual-feed aperture-coupled patch antennas were designed for the four categories of substrates and the sensitivity of their electrical performance due to temperature variations was fully investigated.
Abstract: In the common approach to the design of microstrip antennas, the designers rely on data provided in the manufacturers' specifications, even though such specifications are confined to standard environmental conditions. In practice, the electrical parameters of the substrates may deviate from the manufacturers' data, thus making the antenna designer adopt a deficient design strategy. In the study reported, microstrip substrates were exposed to large temperature variations and their temperature dependent properties were measured in a specialized laboratory for dielectric materials. The results include plots of the dielectric constant and dissipation factor for wide temperature ranges equivalent to those in airborne applications. On the basis of this experimental data, the substrates were divided into four categories according to their dielectric constant value and its temperature dependence. Using both manufacturers' data and the measured values, a series of microstrip dual-feed aperture-coupled patch antennas were designed for the four categories of substrates and the sensitivity of their electrical performance due to temperature variations was fully investigated.
TL;DR: The work function and surface energy for relaxed thin Al(110) slabs using local density-functional theory, first-principles pseudopotentials and a plane-wave basis set were calculated in this paper.
TL;DR: In this article, the Al, Si and Ti targets were sputtered in a reactive atmosphere of argon and oxygen and argon&nitrogen, and the pulsed magnetron power supply generated a series of one polarity 160 kHz puises grouped with 25 kHz, the amplitude of negative current pulses was constant and equal to 8.
TL;DR: In this paper, low density polyethylene- or polypropylene-starch blends containing 40-50% of glycerol plasticized starch were subjected to four months long soil test, and then they were etched with 10% aqueous natrium hydroxide solution during 5 days at room temperature.
TL;DR: In this article, a series of dialkyl and monoalkyl phosphates, phosphites and phosphinates based on (−)-menthol and (−)-nopol were synthesized and used as carriers for transport of aromatic amino acids through supported liquid membranes.
TL;DR: Under such assumptions and some regularity conditions on the primitive data, it is proved the existence of optimal stationary strategies for the players in the expected average payoff stochastic games.
Abstract: In this paper we study zero-sum stochastic games with Borel state spaces. We make some stochastic stability assumptions on the transition structure of the game which imply the so-called w-uniform geometric ergodicity of Markov chains induced by stationary strategies of the players. Under such assumptions and some regularity conditions on the primitive data, we prove the existence of optimal stationary strategies for the players in the expected average payoff stochastic games. We also provide a first result on overtaking optimality in zero-sum stochastic games.