On the thermodynamically consistent fractional wave equation for viscoelastic solids

Since the well-known methods for the computation of harmonically induced LAMB waves in elastic plates cannot be applied directly to viscoelastic material, an enhanced material model is developed. It is based on fractional time derivatives and incorporates a fractional KELVIN?CVOIGT model. A proof of the thermodynamic consistency of this model is given. On the basis of the developed material model, the fractional wave equation is derived which allows for the calculation of LAMB waves in viscoelastic solids.     

Formulas and Numbers of Isomers for Benzenoid Hydrocarbons

The benzenoid chemical formulas, C _n H _s are treated. Extremal benzenoids and some of their subclasses are defined, and some general mathematical formulations are reviewed, especially those of relevance to the constant-isomer series. Substantial extensions of the existing data on the numbers of benzenoid C _n H _s isomers are reported.     

Evaluation of power ultrasound for disinfection of both Legionella pneumophila and its environmental host Acanthamoeba castellanii

The objectives of this study were to (1) examine the effect of power ultrasound on the viability of both Legionella pneumophila and Acanthamoeba castellanii trophozoites and cysts, (2) investigate if intracellular Legionella replication in trophozoites positively affects bacterial resistance to ultrasound and (3) study if Legionella renders viable but non-culturable (VBNC) due to ultrasound treatments. Using laboratory scale experiments, microorganisms were exposed for various time periods to power ultrasound at a frequency of 36 kHz and an ultrasound power setting of 50 and 100%. Due to a fast destruction, trophozoite hosts were not able to protect intracellular Legionella from eradication by ultrasound, in contrast to cysts. No significant effects of ultrasound on cyst viability could be detected and power settings of 100% for 30 min only made intracellular Legionella concentrations decrease with 1.3 log units. Due to intracellular replication of Legionella in trophozoites, ultrasound no longer affected bacterial viability. Concerning the VBNC state, ultrasound treatments using a power setting of 50% partly induced Legionella (±7%) to transform into VBNC bacteria, in contrast to power settings of 100%. Promising results obtained in this study indicate the possible application of power ultrasound in the control of both Legionella and Acanthamoeba concentrations in anthropogenic water systems.     

Erfolgreiches De-Mail Pilotprojekt: Teilnehmer ziehen Bilanz

So einfach wie E-Mail, so rechtsverbindlich wie Papierpost: Mehrere hundert Bürgerinnen und Bürger der Stadt Friedrichshafen haben im Rahmen des De-Mail Pilotprojekts die Chance genutzt und ihr bestehendes Mail-Postfach um das Angebot für die rechtsverbindliche elektronische Kommunikation erweitert. Der sechsmonatige Testbetrieb hat gezeigt: Das System funktioniert, es l?uft stabil und besteht in Sachen Benutzerfreundlichkeit den Realit?tscheck. Insofern f?llt das Fazit der beteiligten E-Mail-Provider — GMX, WEB.DE und der Privatkundensparte der Deutschen Telekom — positiv aus: Das Pilotprojekt war ein voller Erfolg. Jetzt stehen alle in den Startl?chern für den zertifizierten Regelbetrieb.     

Heat distribution and the future competitiveness of district heating

The competitiveness of present and future district heating systems can be at risk when residential and service sector heat demands are expected to decrease in the future. In this study, the future competitiveness of district heating has been examined by an in depth analysis of the distribution capital cost at various city characteristics, city sizes, and heat demands. Hereby, this study explores an important market condition often neglected or badly recognised in traditional comparisons between centralised and decentralised heat supply.     

An improved method for determining the continuous cooling transformation diagram of C‐Mn steels

Dilatometry is often used to study the decomposition of austenite in steels, but the analysis of dilatometric data is often limited to the determination of transformation temperatures. The well‐known lever rule is not applicable when more than one phase transformation occurs. A model accounting for the carbon partitioning effects was developed to extract the phase transformation kinetics of a C‐Mn steel cooled using a wide range of cooling rates. The model is shown to be suitable to analyze the phase transformations in C‐Mn steels and it can be used to obtain a detailed CCT diagram for those steels.     

From primary standard to mobile measurements — Overview of the Spectral Irradiance Calibration Equipment at PTB

The Spectral Irradiance Calibration Equipment (SPICE) at PTB incorporates several radiometric installations. They can be flexibly combined for a large variety of measurement requirements. The instrumentation consists of high-temperature blackbodies as primary radiometric standards, high-quality spectroradiometer systems and a variety of auxiliary measurement equipment. Besides the realization and dissemination of spectral irradiance to various international customers, SPICE enables PTB to investigate new developments in the field of source-based spectroradiometry. Several successfully finished international intercomparisons and cooperations validate the quality and flexibility of SPICE.