Battery powered high efficiency drive systems in practical applications

Since about 30 years three-phase variable speed drives are the standard industrial solution when high reliability, high ingress protection of machine and especially high efficiency are required. Generally, these drives are powered from the grid due to their high power capability. Through Lithium-Ion rechargable batteries, electric variable speed drives for commercial vehicles as cars and trucks become feasible. These Lithium-Ion batteries are no more a completely constant voltage source but vary the voltage mainly dependent on state of charge by about plus and minus 15%. Power electronics for the drive have to cope with this and are strongly influenced by the type of motor, too. Power insertion comes from the grid by special chargers or in case of big mining trucks, by catenaries. Commercial battery powered drives are common between some kW up to 100 kW but are extended up to 800 kW in a heavy truck implementation study

Detection of cochlear hearing loss applying wavelet packets and support vector machines

The aim of this paper is to evaluate the application of the wavelet packet transform (WP) and support vector machines (SVM) to transient evoked otoacoustic emissions (TEOAE) in order to achieve a detection of frequency-specific hearing loss. We introduce a system to determine detection rates between groups of persons with normal hearing, high frequency hearing loss, and pantonal hearing loss. The validity and use of our approach is verified on a different patient group

Ultraviolet variability of quasars: dependence on the accretion rate

We compiled a catalogue of about 4000 SDSS quasars including individual estimators V for the variability strength, virial black hole masses M, and mass accretion rates dM/dt from the Davis-Laor scaling relation. We confirm significant anti-correlations between V and dM/dt, the Eddington ratio, and the bolometric luminosity L, respectively. A weak, statistically not significant positive trend is indicated for the dependence of V on M. As a side product, we find a strong correlation of the radiative efficiency with M and show that this trend is most likely produced by selection effects in combination with the mass errors and the use of the scaling relation for dM/dt. The anti-correlations found for V cannot be explained in such a way. The strongest anti-correlation is found with dM/dt. However, it is difficult to decide which of the quantities (L, Eddington ratio, dM/dt) is intrinsically correlated with V and which of the observed correlations are produced by the relations between these quantities. A V-dM/dt anti-correlation is qualitatively expected for the strongly inhomogeneous accretion disks. We argue that several observed variability properties are not adequately explained by the simple multi-temperature black-body model of a standard disk and suggest to check whether the strongly inhomogeneous disk model is capable of reproducing these observations better.Comment: 16 pages, 10 figures; accepted for publication in Astronomy and Astrophysics; the full catalogue is only available in electronic form at CD

Fabrication of a glycerol from CO2 reaction system, supplement

The fabrication, installation, and testing of a glycerol hydrogenation and a CO2 hydrogenation - CH4 partial oxidation units are reported. The glycerol system proved to be operational while the CO2 system was installed but not bought on operational steam

Biological effects of prolonged exposure of animals to unusual gaseous environments Semiannual report, 1 Sep. 1969 - 28 Feb. 1970

Lung weights of rats exposed to hyperoxic gas mixtures with He or no inert gas diluents substituting N

Accuracy of a mechanical single electron shuttle

Motivated by recent experiments, we calculate both the average current and the current fluctuations for a metallic island which oscillates between two symmetric electrodes. Electrons can only tunnel on or off the island when it is close to one of the electrodes. Using a Master equation we investigate the accuracy of such an electron shuttle both analytically and numerically. It is shown that optimum operation is reached when the contact time is much larger than the RC-time.Comment: RevTeX, 8 pages, 5 figure

HIV risk: is it possible to dissuade people from having unsafe sex?

The cumulative number of human immunodeficiency virus (HIV) infections worldwide has reached 60 million in little over 30 years. HIV continues to spread despite a detailed understanding of the manner in which it spreads and measures which can prevent spread. Some governments have been highly successful in containing the spread of HIV through blood products and from mother to child and among injecting drug users. Lack of political will, lack of resources or challenges to widely accepted scientific evidence have held back similar interventions in other countries. It has proved much more difficult to reduce the sexual transmission of HIV in both high and low income countries. A wide range of strategies has been identified but it remains unclear which strategies deserve priority and what methods of promoting them have the greatest effect.There is ample evidence that awareness of HIV and changes in sexual behaviour have occurred widely but the penetration of information remains poor in some vulnerable groups especially adolescents and women in poorer countries. Further obstacles face those who have information about the risk.The subordinate position of women and a desire for large families are important obstacles to condom negotiation and use. Urbanization, poverty, conflict and declining public services all exacerbate unsafe sexual behaviour.We argue that so-called ‘structural’ interventions directed at these wider contexts of unsafe behaviour merit greater attention. Such approaches have the added benefit of being less susceptible to ‘risk compensation’ which has the potential to undermine strategies directed at reducing the transmission efficiency of HIV