Die Erhöhung der Grundfrequenz und der Beullast von Kreisplatten durch geeignete plastische Verformung

Zusammenfassung Eine M?glichkeit, ohne Mehraufwand an Material oder Verwendung teurerer Werkstoffe das dynamische Verhalten oder die Tragf?higkeit von Bauteilen zu verbessern, wird am Beispiel der Grundfrequenz- und Beullaststeigerung von Kreisplatten durch das Einpr?gen von geeigneten Eigenspannungszust?nden dargelegt. Die Ergebnisse einer Optimierung solcher Eigenspannungsfelder werden dargestellt, und die M?glichkeit der Erzeugung geeigneter Eigenspannungszust?nde wird an Hand eines Experiments nachgewiesen.     

Experimental activation energies for evolution of oxygen and chlorine on oxide electrodes

The chlorine and oxygen overpotential in dependence on the current density i (A cm^?2) and on the temperature in the range of 15–75°C was measured at γ-MnO₂ and β-PbO₂ electrodes in concentrated water solutions of sodium chloride and perchlorate. From the measured values the experimental activation energy in dependence on overpotential was calculated and, for the temperature of 25°C, the constants of Tafel's equation (a,b) (α, i_o respectively) were evaluated.     

Composition of Chemical Attractants Affects Trap Catches of the Australian Sheep Blowfly, Lucilia cuprina, and Other Blowflies

Numbers of Lucilia cuprina (Australian sheep blowfly), Chrysomya spp., and Calliphora spp. blowflies caught on sticky traps baited with various synthetic attractants or a standard liver/sodium sulfide attractant in western Queensland were recorded. Numbers of each genus collected were influenced by the composition of the chemical attractants. Attractant mixtures based on 2-mercaptoethanol, indole, butanoic/pentanoic acid, and a sodium sulfide solution gave 5- to 20-fold higher L. cuprina catches than the liver standard. These blends attracted similar numbers of Chrysomya spp. (0.85-2.7x) and fewer Calliphora spp. (0.02-0.2x) compared to the liver standard. These synthetic attractants were more effective and selective for L. cuprina than the standard liver/sodium sulfide attractant, and they can be packaged in controlled-release dispensers to generate constant, prolonged release of the attractant.     

Aquatic hypoxia is a teratogen and affects fish embryonic development

Hypoxia occurs over large areas in aquatic systems worldwide, and there is growing concern that hypoxia may affect aquatic animals, leading to population decline and changes in community by elimination of sensitive species. For the first time, we report that sublethal levels of hypoxia can significantly increase (+77.4%) malformation in fish embryonic development. Disruption of apoptotic pattern was clearly evident at 24 h post-fertilization, which may be a major cause of malformation. Furthermore, embryonic development was delayed, and balance of sex hormones (testosterone and estradiol) was disturbed during embryonic stages, implicating that subsequent sexual development may also be affected. Overall, our results imply that hypoxia may have a teratogenic effect on fish and delay fish embryonic development, which may subsequently impair species fitness leading to natural population decline.     

Perceived ward climate and treatment outcome.

3 ward climate scales were derived from 2 independent studies linking treatment environments as perceived by patients and staff to treatment outcome as assessed by ward dropout, release, and community tenure rates. Patients and staff from 7 large and 8 small Veterans Administration hospital wards completed the Ward Atmosphere Scales. Patients and staff agreed in perceiving wards with high dropout rates as low in involvement, support, order and organization, and program clarity, whereas wards with high release rates were perceived as strongly emphasizing practical orientation, but as relatively "unexpressive." Wards that kept patients out of the hospital longest were seen as emphasizing autonomy and independence, practical orientation, order and organization, and the open expression of feelings, particularly angry feelings. It is concluded that some relatively consistent findings are emerging from studies in this area. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Techniques for fast and sensitive measurements of two-dimensional birefringence distributions

We propose image processing algorithms for measuring two-dimensional distributions of linear birefringence using a pair of variable retarders. Several algorithms that use between two and five recorded frames allow us to optimize measurements for speed, sensitivity, and accuracy. We show images of asters, which consist of radial arrays of microtubule polymers recorded with a polarized light microscope equipped with a universal compensator. Our experimental results confirm our theoretical expectations. The lowest noise level of 0.036 nm was obtained when we used the five-frame technique and four-frame algorithm without extinction setting. The two-frame technique allows us to increase the speed of measurement with acceptable image quality.     

Correction of ozone influence on TOA radiance

An accurate atmospheric correction (AC) of Earth remote-sensing data in the spectral region 450–800 nm has to account for the ozone gas absorption influence. Usual operational AC codes employ a fixed ozone concentration corresponding to a climatologic average for a certain region and season, e.g. the mid-latitude summer atmosphere of the Moderate Resolution Atmospheric Transmission (MODTRAN) code. The reasons for a fixed ozone column are that ozone does not vary rapidly on a spatial and temporal scale, and additionally, the look-up table (LUT) size for AC is already big. This means that another degree of freedom for the ozone parameter would dramatically increase the size of the LUT database and the time required for LUT interpolation. In order to account for this effect, we use already existing LUTs that were calculated for a certain ozone reference level, e.g. an ozone column of g = 330 Dobson Units (DU) for MODTRAN’s mid-latitude summer atmosphere. Then the deviation of the top-of-atmosphere (TOA) radiance ΔL(g) from the reference level L(g = 330) is calculated as a function of solar and view geometries. The calculation is performed for a set of 36 wavelengths in the ozone-sensitive spectrum (450–800 nm) and five ozone columns. The last step computes the linear regression coefficients for each wavelength and geometry. The results are stored in a small table (11 kB). It is shown that the ozone influence is accurately accounted for by multiplying the modelled radiance L(g = 330) with a factor depending on g and wavelength yielding TOA radiance relative errors smaller than 0.5% for a wide range of ozone concentrations between 180 and 500 DU. Selected examples of a sensitivity study of the ozone effect on the retrieval of water constituents demonstrate the need to account for ozone in the AC step.     

Spectral and radiometric requirements for the airborne thermal imaging spectrometer ARES

ARES (Airborne Reflective/Emissive Spectrometer) is an airborne imaging spectrometer for remote sensing of land surfaces covering the wavelength regions 0.45–2.45?µm and 8–13?µm with 160 channels. The instrument is being built by Integrated Spectronics, financed by DLR and GFZ, and will be available to the scientific community from 2005 on.

This contribution presents the design of the thermal spectrometer covering the 8–13?µm region with 32 channels of 150?nm bandwidth while a separate paper treats the instrument specifications in the solar reflective region. The spectro‐radiometric design is based on scientific requirements derived from application scenarios comprising vegetation, soils of different compositions, and mineral exploration. The corresponding emissivity spectra are input for a simulation model that calculates at‐sensor radiance spectra, resamples them with the channel‐specific response functions, adds different amounts of sensor noise to the signal, and performs a retrieval to get the corresponding noisy surface emissivity spectra. The results of the simulation study indicate that a spectral wavelength accuracy of 3?nm and a sensor noise equivalent temperature of 0.05–0.1?K are required for an accurate retrieval of emissivity spectra.