Characterization of a Novel Flat‐Panel Airlift Photobioreactor With an Internal Heat Exchanger

A novel flat‐panel airlift photobioreactor with an internal heat exchanger (FPA‐IHE) separating the riser and downcomer zones was characterized. The proposed FPA‐IHE has working volume of 2.2 L, height of 450 mm and light path of 50 mm. The overall heat transfer coefficients for the internal heat exchanger and the external surface of the reactor were 47.0 W m^–2K^–1 and 7.1 W m^–2K^–1, respectively. The mass transfer coefficient increased with an increase in the volumetric power input until a value of 0.01 s^–1. The mixture time decreased with the increase in the superficial gas velocity of the riser. The circulation time ranged from 5 to 6 s. The specific growth rates of Dunaliella tertiolecta and Chlorella minutissima were high, 0.77 d^–1 and 0.67 d^–1, respectively; thus, the FPA‐IHE photobioreactor is a promising environment for the development of highly productive processes using microalgae.     

Improving a practical DBR buffering approach using Workload Control

This paper deals with improving the lead-time performance of a small packaging manufacturer in the Netherlands that had already implemented several facets of Theory of Constraints (TOC) in 1997. Since then, delivery reliability and profits have increased and lead-times reduced substantially. In an attempt to achieve further lead-time improvements in 2001, the firm recently encountered some limitations of its partial TOC implementation. In this paper we focus on the modifications of its order acceptance and buffer management system that were necessary in order to obtain the desired lead-time reduction. We describe how Workload Control principles were introduced to improve the buffering approach and planning procedures the firm had been using since 1997. It shows that Workload Control provides effective tools that can be used in combination with the Drum-Buffer-Rope mechanism in order to balance the flow of work to the production floor.     

Die Technische Richtlinie zur vertrauenswürdigen elektronischen Langzeitspeicherung (TR-VELS)

In vielen Bereichen der ?ffentlichen Verwaltung, der Justiz und der Unternehmen besteht das Bestreben, Gesch?ftsprozesse umfassend zu digitalisieren und damit ausschlie?lich in elektronischer Form durchzuführen. Ziel der TR-VELS ist es, ein Rahmenwerk für die vertrauenswürdige elektronische Langzeitspeicherung zu definieren, um so die Authentizit?t, Integrit?t und Verkehrsf?higkeit gespeicherter Daten w?hrend der gesetzlichen Aufbewahrungsfristen sicherzustellen.     

Investigation of the reaction impurities associated with methylamphetamine synthesized using the Nagai method

The synthesis of methylamphetamine hydrochloride from l-ephedrine or d-pseudoephedrine hydrochloride via reduction with hydriodic acid and red phosphorus was investigated. Eighteen batches of methylamphetamine hydrochloride were synthesized in six replicate batches using three different reaction times. This allowed the investigation of the variation of impurities in the final product with reaction time. The results obtained have resolved previously conflicting impurity profile data reported in the literature for this synthesis route. The impurity profile was shown to change with reaction time, and all previously reported impurity components were identified but not in all batches. Additionally, 20 batches of methylamphetamine hydrochloride were synthesized from either from l-ephedrine or d-pseudoephedrine hydrochloride in reactions which were allowed to proceed for 24 h. The impurities present in the resulting batches were investigated, and route-specific impurities present in all batches were identified. Batch-to-batch fluctuations in the resultant chromatographic impurity profile, despite careful synthetic monitoring and control, were also noted.     

Electrical Noise in a TES as a Resistively Shunted Conducting Junction

We present results of the analysis of electrical noise in a transition edge sensor (TES) as a resistively shunted conducting junction (the RSJ model). We derive an expression for the spectral density of voltage fluctuations taking into account weak superconductivity of a TES. We analyse and discuss differences in voltage noise in a TES compared to the familiar situation for the Josephson junction. The spectral density of voltage noise in the RSJ model has a unique analytical structure and cannot be reduced to the expression for the nonlinear Johnson noise near equilibrium.     

BonnTools: Mathematical Innovation for Layout and Timing Closure of Systems on a Chip

The BonnTools provide innovative solutions for layout and timing closure that are used for many of the most complex integrated circuits. During 20 years of cooperation between the University of Bonn and IBM, new mathematical foundations and algorithms have been developed for the need of new technologies and leading-edge designs. In this paper we present the main ideas for placement, routing, timing optimization, and clock tree synthesis, which are the foundation of a continuing success story     

ESR as a fast technique to dissolve nitrogen-rich inclusions in titanium

 Nitrogen-rich inclusions can lead to a reduction in fatigue life of highly stressed titanium-alloy components (found in the compressor sections of power generation gas turbines, turbine sections of power generation steam turbines, wing sections of aircraft air frames, and compressor and fan sections of aircraft jet engines, for example). It is the ”crack starting” nature of the nitrogen-rich inclusions that is the problem, not the presence of nitrogen in the system, per se. This paper covers the theory and laboratory experiments used to evaluate ESR (electro-slag refining) as an alternative technique for rapid dissolution of nitrogen-rich inclusions in titanium and titanium alloys. Five variations of melt rate, slag temperature and inclusion type were evaluated. One variant showed complete dissolution of the inclusions. Several of the other variants showed partial dissolution of the inclusions. The kinetics were observed to occur at a rate 100 to 1000 times faster than the rate of dissolution of nitrogen-rich inclusions by immersion in liquid titanium. Received: 14 December 1998 / Reviewed and accepted: 17 December 1998     

Three-dimensional nanostructuring with femtosecond laser pulses

The development of simple laser-based technologies for the fabrication of complicated three-dimensional (3-D) microstructures with a structure size down to 100 nm is reported. These technologies are based on nonlinear multiphoton laser-matter interaction processes allowing to overcome the diffraction limit and to fabricate 3-D structures inside transparent materials. Examples on nanostructuring of metals, dielectrics, and polymers are presented.     

Distributed or centralised energy-from-waste policy? Implications of technology and scale at municipal level

Energy-from-waste (EfW) policies can provide an essential part of landfill diversion and climate change strategies. Many UK waste disposal authorities (WDAs) are currently deciding which energy-from-waste policies are most suitable for their respective municipal areas. Such decisions are challenging since the environmental, economic and social implications of any EfW policy must be fully considered, now that planning guidelines require a full Sustainability Assessment. More specifically, WDAs must identify suitable site locations for facilities, and the optimal scale and number of facilities. This paper reports the results from a study that has developed and appraised EfW policy options using Geographical Information Systems and Multi Criteria Analysis modelling. These methods were used to evaluate and compare the impacts of several EfW strategies in the UK administrative areas of Cornwall and Warwickshire. Different strategies have been defined by the size and number of the EfW facilities, as well as the technology chosen, which includes conventional incineration and advanced thermal treatment. The overall conclusion of this work is that distributed small-scale EfW facilities score most highly overall on the chosen decision criteria and that scale is more important than technology design in determining overall EfW policy impact.