On the qualitative behaviors of solutions of third order nonlinear differential equations

We present some new results about oscillation and asymptotic behavior of solutions of third order nonlinear differential equations of the form

(r₂(t)(r₁(t)y^′)^′)^′+p(t)y^′+q(t)f(y(g(t)))=0.     

Interkulturalität und informatische Gestaltung – Eine interdisziplinäre Annäherung

Zusammenfassung   Dieser Beitrag behandelt - aus einer interdisziplin?ren Perspektive - die Bedeutung der Interkulturalit?t für die Gestaltung in und mit der Informatik im Zeitalter zunehmender Globalisierung. In diesem Zusammenhang wird, um die Rolle der Kultur in der Kommunikation zu verstehen, auf linguistisch-empirische Untersuchungen zur schriftlichen Kommunikation eingegangen und ihre Brauchbarkeit für die Gestaltung hinterfragt. Anschlie?end wird der Frage nach M?glichkeiten und Grenzen des interkulturellen Verstehens und Dialoges in der Philosophie nachgegangen, um daraus Rechtfertigungen für die interkulturelle Orientierung in der Informatik zu erarbeiten. Schlie?lich werden aktuelle informatische Entwicklungen in interkulturellen Kontexten diskutiert. Eingegangen in überarbeiteter Form am 30.04.1998     

Rheological Characterization of Nitrocellulose Gels

Various nitrocellulose, NC, based propellant formulations need to be processed using new and more environmentally friendly solvent combinations on the one hand and using continuous processing methodologies on the other hand. A detailed understanding of the significant changes that take place in the structure and hence the rheological behavior of NC based formulations during manufacture is required to minimize the use of organic solvents and to revert to safer and green solvents. Towards achieving these objectives, experimental methodologies were developed for the first time to enable the accurate characterization and thus fingerprinting of the rheological behavior of NC gels. In these methodologies linear viscoelastic measurements are employed. The concentration of the solvents existing in the gel sample during rheological characterization is concomitantly monitored to allow the documentation of the major source of error associated with the rapid loss of the typical solvents, which generally exhibit relatively high vapor pressures. These measurements have indicated that the source of the NC fibers and the treatment method alter the rheological behavior and can be tracked. The rheological properties of the NC gels can be linked to their manufacturability and such data can be used to pinpoint optimum geometries and processing conditions. The processability of the NC based formulations can also be tailored on the basis of rheological characterization, allowing the manufacturers greater latitude for reducing costs and environmental footprint during manufacture, as well as improving the quality of their NC based energetic formulations.     

Acetylation of Wood with Various Catalysts

Abstract

The purpose of this study was to compare two different acetylation mechanisms using acetic anhydride (AA) or vinyl acetate (VA) modification with using various catalysts. Acetylation of Scots pine wood flour with acetic anhydride could be significantly improved in the presence of potassium acetate, potassium carbonate, and sodium carbonate at 100°C. Sodium carbonate had low effect on VA acetylation, potassium acetate was found to be more effective, and potassium carbonate was better for vinyl acetate modification of wood flour. The two modification methods and the effect of different catalysts on AA or VA modification were characterized by infrared and NMR spectra and analyzed in detail. The acetylation of Scots pine flour with VA and AA showed almost the same WPG values for catalysts when based on long reaction times.     

Development of a multipurpose tile body: Phase and microstructural development

In this study, an attempt was made in order to develop a multipurpose tile body using a single formulation. In order to achieve this, several body recipes were prepared using mainly local raw materials with clearly defined physical and chemical properties at different sieve residues and single fast fired under industrial conditions in the first part of the study. In the second part, the most suitable formulations with the corresponding sieve residues were determined and further fired at different peak temperatures under laboratory conditions in order to establish their vitrification ranges and optimum firing temperatures. The tested peak firing temperatures were varied at 20 °C intervals from 1120 to 1200 °C for multipurpose wall tile body and from 1140 to 1220 °C for multipurpose floor tile body. The physical and thermal properties of the fired bodies such as water absorption, linear firing shrinkage, bulk density and linear thermal expansion coefficient were measured. The vitrification behaviour of the multipurpose bodies was also evaluated using a double-beam optical non-contact dilatometer. Furthermore, the fired bodies were subjected to colour measurements. Particular consideration was given to the phase and microstructural evolution of the developed tile bodies. X-ray diffraction (XRD) was used to analyse the phases formed before and after firing. Scanning electron microscopy (SEM) in combination with energy dispersive X-ray spectroscopy (EDS) was further employed in order to observe the microstructural and microchemical characteristics of the fired bodies with respect to peak firing temperature. The preliminary experimental results showed that it was possible to obtain a multipurpose body with the properties in accordance with ISO-EN 10545.     

Policy implications of trends in Turkey's meat sector with respect to 2023 vision

Turkey has become one of the leading emerging economies in the world being second after China as the highes ecoonomically growing country with 8.9% economic growth rate in 2010. Forecasting impacts of this development in coming 10 years might have very important policy implications for the meat sector in the framework of 2013 vision of Turkey. In this study, annual time series data which contain several key variables of meat sector in last 26 years (1987–2012) are used to forecast the variables of the coming twelve years (2013–2024) to drive policy implications by considering the impacts of high economic growths, crises and major policy changes. Forecasted future values of the variables for 2023 in the sector are assessed and compared with recent national and international values to drive policy implications. The results show that the economic growth results in the increase in per capita income and thus increased demand for meat seemed to foster the meat sector. Therefore, these macroeconomic indicators need to be better in addition to improvements at micro level for establishing competitive meat sector and thus reaching aimed consumption level of meat.     

Exploring the types and reasons of Internet-triggered academic dishonesty among Turkish undergraduate students: Development of Internet-Triggered Academic Dishonesty Scale (ITADS)

Internet contributes to the development of science and facilitates scientific demeanors while it also serves as a ground for academic misdemeanors. Recent studies indicate that Internet facilitates and spreads academic dishonesty. The purpose of the current study is to investigate the extent of involvement of Turkish university students in academic dishonesty practices facilitated through Internet (i.e. e-dishonesty) and to question the conditions which lead to e-dishonesty. Three hundred and forty nine education faculty students from the most populated state university in Turkey were administered two Likert-Scale questionnaires developed by the researchers. After the reliability and validity conditions were met, two exploratory factor analyses were conducted. The first one revealed the factors constituting common types of e-dishonesty among undergraduate students which were fraudulence, plagiarism, falsification, delinquency, and unauthorized help. The second factor analysis exhibited individual and contextual factors triggering e-dishonesty which were named as individual factors, institutional policies and peer pressure. Results of both analyses are discussed and suggestions for further research are provided.     

Separation and recovery of palladium(II) from base metal ions by melamine–formaldehyde–thiourea (MFT) chelating resin

Melamine–formaldehyde–thiourea (MFT) resin, a chelating resin, was synthesized by reaction with melamine, formaldehyde and thiourea in aqueous solution. This chelating resin was used in the separation and recovery of palladium(II) from copper(II) and zinc(II) base metal ions. Effect of initial acidity, adsorption capacities of the metal ions by batch method and adsorption, elution, separation factors and column adsorption capacity of the metal ions by column method were examined. The optimum initial acidity was determined as pH 4. Adsorption capacities of the MFT resin were found as 15.29 mg/g (0.144 mmol/g) for palladium(II), as 1.612 mg/g (0.025 mmol/g) for copper(II) and as 0.453 mg/g (0.007 mmol/g) for zinc(II). In addition the protonation capacity of the resin was found as 0.110 mmol H⁺/g. It was concluded that ionic interaction between protonated amines on the resin and chloro-palladate complex (PdCl₄^2?) was very effective as well as chelation. In the column studies, dynamic adsorption capacities were calculated as 1580 μg/g (14.85 μmol/g) for palladium(II), as 250 μg/g (3.93 μmol/g) for copper(II) and as 25 μg/g (0.38 μmol/g) for zinc(II). MFT resin showed higher affinity to palladium(II) ions according to copper(II) and zinc(II) ions. It was seen that palladium(II) can be separated from copper(II) and zinc(II) and concentrated by melamine–formaldehyde–thiourea chelating resin.