„Smart“, Vernetzung und Komplexität – Ein Plädoyer für einen kritischeren Umgang mit dem Thema Vernetzung

Our daily life is already based on a very high level of connectivity and interconnectedness with many benefits but also with a growing threat level from cyberspace. Our critical infrastructure will also become more and more involved in this process of interconnectedness. Especially with the topic of “smart” many things are likely to get more comfortable and easier. Smart homes are to be controlled remotely, smart meters should decrease our energy consumption and smart grids should enable the transformation of the power supply system to renewable and sustainable energy production. The pictures conjured up by these topics are very colourful. But seldom the responsible people are aware of the consequences of an increasing interconnectedness. The results are complex systems with a completely different behaviour from our current machines. They are not controllable in the same way we used to do with machines until now. On the other hand it could be a high risk to merge the known insecure ICT systems with our critical infrastructure, especially with our power supply system. Our whole life is heavily dependent on the reliability of the power supply system and there is only one European power network. We should not risk this essential system for survival by increasing interconnectedness inconsiderately and without an adequate knowledge of complex systems.     

High hydrogen production from glycerol or glucose by electrohydrogenesis using microbial electrolysis cells

The use of glycerol for hydrogen gas production was examined via electrohydrogenesis using microbial electrolysis cells (MECs). A hydrogen yield of 3.9 mol-H₂/mol was obtained using glycerol, which is higher than that possible by fermentation, at relatively high rates of 2.0 ± 0.4 m³/m³ d (E_ap = 0.9 V). Under the same conditions, hydrogen was produced from glucose at a yield of 7.2 mol-H₂/mol and a rate of 1.9 ± 0.3 m³/m³ d. Glycerol was completely removed within 6 h, with 56% of the electrons in intermediates (primarily 1,3-propanediol), with the balance converted to current, intracellular storage products or biomass. Glucose was removed within 5 h, but intermediates (mainly propionate) accounted for only 19% of the electrons. Hydrogen was also produced using the glycerol byproduct of biodiesel fuel production at a rate of 0.41 ± 0.1 m³/m³ d. These results demonstrate that electrohydrogenesis is an effective method for producing hydrogen from either pure glycerol or glycerol byproducts of biodiesel fuel production.     

Design of maximum thrust plug nozzles with variable inlet geometry

An optimization analysis is presented for axisymmetric plug nozzles with varible inlet geometry. The analysis is based on the governing gas dynamic relations for a rotational flow of a frozen or equilibrium gas mixture. The problem is formulated to maximize the axial thrust produced by the plug nozzle for a general isoperimetric constraint, such as constant nozzle length or constant nozzle surface area. The effects of base pressure and ambient pressure are included in the thrust expression to be maximized. The governing gas dynamic equations and the differential and integral constraints that the solution must satisfy are incorporated into the formulation by means of Lagrange multiples. The formalism of the calculus of variations is applied to the resulting functional to be maximized. The results of the optimization analysis are a set of partial differential equations for determining the Lagrange multipliers in the region of interest and a set of equations for determining the necessary boundary conditions for the solution. The complete set of equations for the gas dynamic properties and the Lagrange multipliers are system of first order, quasi-linear, non-homogeneous partial differential equations of the hyperbolic type, which can be treated by the method of charac- teristics. The characteristic and compatibility equations for the system are presented. A numerical solution procedure is presented to determine wether or not a given plug nozzle geometry is an optimal solution. An iteration technique is developed which systematically adjusts the plug nozzle geometry until the optimal solution is obtained. Selected parametric studies are presented. These studies illustrate the effect of the specific heat ratio, the design pressure ratio and the base pressure model on the thrust peformance and nozzle geometry of optimal, fixed length, plug nozzles.     

Economic growth and energy consumption in the UK, 1700–1975

This paper attempts to trace the development of energy consumption in the UK during the process of industrialization. First a quantitative overview of the relationship between energy consumption and economic growth for the period 1700–1975 is presented. An examination of the factors affecting relations between economic growth and energy consumption is then presented. This is divided into two main periods: pre-1800 and 1800–1975. The discussion of pre-1800 energy consumption is mainly concerned with coal use, while a more detailed account is given of developments in the later period.     

A Comparison of Replicate Field Samples Collected with the Bi-Air,Air-O-Cell,and Graesby-Andersen N6 Bioaerosol Samplers

The Bi-Air (BA) and Air-O-Cell (AOC) cassettes have been compared for the collection of Aspergillus/Penicillium (Asp/Pen) and Chaetomium spores based on replicate and/or duplicate samples collected under typical field conditions. Total culturable Asp and Pen concentrations were also compared for the BA and the N6 impactor based on duplicate field samples. When single Asp/Pen spores or small chains were dominant, the average BA:AOC concentration ratio was 2.1 (11,260 spores/m³ v 5,400 spores/m³) for six duplicate samples collected in a well-mixed room. This ratio was consistent with previous studies performed under controlled conditions. However, the average BA:AOC concentration ratio was 54 (765,00 spores/m³ v 36,800 spores/m³) for four replicate samples in which small Asp/Pen spores and clusters of Asp/Pen spores were dominant. The average BA:AOC concentration ratio for Chaetomium was typically 8.6, with a high of 100 for the four replicate samples in which Asp/Pen clusters were dominant. It was concluded that the performance of the BA and the AOC, except for a reasonably constant 2:1 ratio of concentrations, were similar for the detection of single Asp/Pen spores or small chains. However, the BA generally detected higher concentrations of Asp/Pen spores when clusters were dominant; and detected Chaetomium spores in more of the replicate field samples and at a higher average concentration.

The average concentrations of culturable Aspergillus and Penicillium were not statistically different for six duplicate N6 and BA samples collected in a well-mixed room. For nine duplicate field samples with N6 concentrations of total culturable fungi greater than 1,000 cfu/m³, the N6 and BA were moderately correlated (r = 0.76). It was concluded that the ability of the BA to collect culturable fungi was similar to that of the N6 for short-term samples.     

Overlap-Based Cell Tracker

In order to facilitate the extraction of quantitative data from live cell image sets, automated image analysis methods are needed. This paper presents an introduction to the general principle of an overlap cell tracking software developed by the National Institute of Standards and Technology (NIST). This cell tracker has the ability to track cells across a set of time lapse images acquired at high rates based on the amount of overlap between cellular regions in consecutive frames. It is designed to be highly flexible, requires little user parameterization, and has a fast execution time.     

Temperature Effects on a Non-Volatile Memory Device with Ferroelectric Capacitor

The temperature effects on a ferroelectric non-volatile memory latch were measured. The device is based on a design from Radiant Technologies Inc. utilizing a discrete ferroelectric capacitor. The effects measured include functionality, I-V characteristics and retention. The range of temperatures for which the device was tested is –107°F to +302°F. The results are compared with measurements made at room temperature for the device. Retention measurements of the device at elevated temperatures allow predictions of retention performance under normal operating conditions. Potential applications of this device in harsh environments which include aerospace, industrial and automotive are presented.     

Fano Resonance Through Quantum Dots in Tunable Aharonov-Bohm Rings

Stimulated by recent intriguing experiments with a quantum dot in an Aharonov-Bohm (AB) ring, we investigate novel resonant phenomena by studying the total transmission probability of nanoscale AB rings with an embedded scattering center in one arm and a magnetic flux passing through its center. In the AB ring with double coupled-quantum dots (QDs), we show that the overlapping of Fano resonances arises from the strong interaction between two quasi-bound levels in the coupled QDs, and that the zero of the Fano resonance is shifted to the complex plane. In addition, we also study the effects of an asymmetry in the arm by inserting an attractive potential well (dot) in one arm. The combined transmission resonance effects as functions of variables of the ring structure and the potential are presented. It is shown that an attractive potential in one of the arms in the AB ring generates an asymmetric Fano resonance in the transmission.