Zur Theorie der Trennfestigkeit metallischer Werkstoffe

Begriff der Trennfestigkeit. Aufstellung von Festigkeitsbedingungen für homogene isotrope Stoffe. Darstellung der Festigkeitsgrenzen im Hencky-Schaubild. Vieldeutigkeit der Mehrachsigkeitsziffern. Eindeutige Kennzeichnung der Form eines Spannungszustandes. Ermittlung der Hauptspannungen für reine Zugspannungszustände. Plastizitätsgrenze und kritischer Räumlichkeitsgrad. Zahlenbeispiel für den Baustahl St 42-3. Anwendung auf Kerbspannungen.     

Selection by color and form in vision.

Whether attention to a local part of a visual display can prevent access to semantic information in form matching tasks with objects was studied. A first picture containing a line segment (the reference) was followed by 2 lateral objects also containing a line segment (a target and a distractor). Participants matched the line segments according to either their orientation or color. Effects of semantic information were assessed by manipulating the semantic relations among the pictures surrounding the reference, target, and distractor. Semantic information affected performance in the orientation matching task, but not in the color matching task. Results suggest the existence of separate selection mechanisms in vision. Selection of local colors for response purposes can be based on inhibition of the form pathway (eliminating semantic effects on matching). Selection within the form pathway can involve a bias toward global shape (the picture). Once attention is allocated to global shape, associated semantic representations are activated and semantic effects on matching emerge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention to orientation, size, luminance, and color: Attentional failure within the form domain.

Whether Ss can attend to physical dimensions of objects without access to semantic information about them was examined. Ss decided which of 2 laterally presented pictures, a target and a distractor, had the same orientation (Exp 1), size (Exp 2), luminance (Exp 3), or color (Exp 4) as a reference picture. In each experiment, the matching stimuli were either physically identical, semantically related, or semantically unrelated. The reference stimulus and the distractor were either semantically related or unrelated. When matching was based on orientation or on size, performance was facilitated when the matching stimuli were semantically related, and it was disrupted when the distractor was semantically related to the reference stimulus. Semantic effects were eliminated when matching was based on luminance or color. The results are discussed in terms of physiological data, form and surface information, and global and local processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Secondary-emission amplification at microwave frequencies

Two types of photomultipliers exhibiting flat base-band response to ∼4 Gc/s are described. One photomultiplier employs crossed electric and magnetic fields, the other is purely electrostatic. At present both devices consist of eight Cu-Be secondary emission stages and an internally situated, opaque-backed S-1 photocathode. Current gain exceeds 10⁵, and the transit time dispersion is less than7 times 10^{-11}s. Frequency response measurements have used heterodyning between the modes of the Zeeman-split Doppler profiles of a 6328 Å He-Ne laser, and also shot noise in the current from a steadily illuminated photocathode as sources of microwave modulated currents. Transient response measurements have been made using sub-nanosecond light pulses from phase-locked He-Ne and argon ion lasers, the results being consistent with the measured frequency response. A calculation of the frequency response to be expected fromnidentical stages of secondary emission when only the secondary electron emission velocities contribute to electron transit time differences, as is true of the geometries used in the experiments, gives results in agreement with experiment, assuming a value of 3 eV for the most probable secondary electron emission energy from BeO. This value is consistent with direct observations by others.     

Reduction of reflection losses of PV-modules by structured surfaces

Structuring the transparent cover of solar cell modules reduces reflection losses, particularly at large angles of incidence. Relevant aspects are good transmission efficiency independent of wavelength and a low sensitivity to pollution. The macroscopic, linearly grooved structure proposed in this article shows good performance only in combination with a textured cell because large angles are likely to occur inside the structured cover. A classification is made with the concept of annual averaged transmission efficiency for the climatic zone of Freiburg. Calculations and measurements for different combinations of smooth and structured covers and solar cells are presented. From the calculated 97.8% entering the structured glass cover, a measured 93.2% can be coupled into a pyramidal textured monocrystalline solar cell. This is an absolute improvement of 17% compared to a smooth, incoated solar cell with a smooth glass cover. Outdoor measurements showed that a textured solar cell with a structured cover has between 5 and 10% higher values of short-circuit current than a textured cell with a smooth cover.     

Visual detection of blemishes in potatoes using minimalist boosted classifiers

This paper introduces novel methods for detecting blemishes in potatoes using machine vision. After segmentation of the potato from the background, a pixel-wise classifier is trained to detect blemishes using features extracted from the image. A very large set of candidate features, based on statistical information relating to the colour and texture of the region surrounding a given pixel, is first extracted. Then an adaptive boosting algorithm (AdaBoost) is used to automatically select the best features for discriminating between blemishes and non-blemishes. With this approach, different features can be selected for different potato varieties, while also handling the natural variation in fresh produce due to different seasons, lighting conditions, etc. The results show that the method is able to build “minimalist” classifiers that optimise detection performance at low computational cost. In experiments, blemish detectors were trained for both white and red potato varieties, achieving 89.6% and 89.5% accuracy, respectively.     

Effect of long term ingestion of gum arabic on the adipose tissues of female mice

Abdominal obesity is the most prevalent manifestation of metabolic syndrome. The anti-obese effects of dietary fiber is generally accepted, but specifically the anti-obese properties of the dietary fiber, gum arabic (GA) has not been well studied. In this investigation, we offered GA to the female 90 days old mice in the form of drink (1% w/v) for 180 days. Such GA in drinking water reduced age-dependent fat deposition in the visceral adipose tissue and improved the gastrocnemius muscle reduction. This inhibition of fat deposition effect is due to the β3-adrenergic stimulation of adipocytes in which TNFα down-regulation is probably involved. Modification of large intestinal microflora, as evidenced by a modification of cecal short-chain fatty acid profile and of 16S rDNA profile, may contribute to such reduction in TNFα expression in the adipose tissues.