Kraftstoffersparnis durch Hochleistungswerkstoffe

Fuel Saving by the Use of High‐Performance Materials Due to new European regulations efficiency of modern automobiles has to be increased. Two possible ways to achieve a reduction of fuel consumption are weight reduction by light metals like aluminium and use of coatings to reduce friction losses and enable new efficient working points. An example which combines both ways is the engine of a modern automobile. More and more light alloys like AlSi are used to reduce the engine weight. Furthermore, coatings are used to maximise the weight reduction and to increase the efficiency. Thus, thermal spraying is used to avoid wear on the aluminium bores and thin coatings on piston rings deposited by means of Physical Vapour Deposition (PVD) decrease the friction losses and allow low wear within this tribological contact.     

巴基斯坦的宝玉石新品种:山南矽卡岩(Sannan-Skarn)

在巴基斯坦西部发现了一种复杂的细粒宝玉石矿床。其产出的石材以其或浓或淡的绿色为特征,主要致色元素为铬。此类岩石的矿物组成在小的产出范围内亦有很大的变化,珠宝学家尚未完全了解其组成矿物(已知包括水钙铝榴石,透辉石,霓石,蓝透闪石,针纳钙石,绿泥石,钠沸石与方钠石等等)。以岩石学分类论,该类岩石为矽卡岩,一种经原岩交代变质作用后形成的岩石,通常为钙质硅酸岩。山南(Sannan)是产于此新矿床的矽卡岩的特定名称。     

The effect of texture on the pass/fail colour tolerances of injection‐molded plastics

The effect of surface texture on the pass/fail colour tolerance region was estimated using acrylonitrile–butadiene–styrene injection‐molded plaques in three different colours and with different surface textures. Variations in the measured colour coordinates due to differences in texture for three selected colours were observed using the specular component excluded mode (SCE) of the spectrophotometer. Such variations could not, however, be clearly distinguished in the specular component included mode. The colour tolerance regions were assessed through a combination of colour measurement and a psychometric study involving 35 observers. The limits of acceptance of colour differences varied substantially with the surface texture. In some cases, the observers accepted a larger colour difference for the textured than for the smooth surface, whereas in other cases, the reverse situation was noted. Thus, no general conclusion regarding the influence of texture on the tolerance region can be drawn, since the acceptable differences were colour‐ and/or surface texture‐dependent. In the case of textured surfaces, measurements made in the SCE mode of the spectrophotometer appear to be more meaningful for assessing perceived colour differences and tolerance regions. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 47–54, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20284     

Slender-Set Differential Cryptanalysis

This paper considers PRESENT-like ciphers with key-dependent S-boxes. We focus on the setting where the same selection of S-boxes is used in every round. One particular variant with 16 rounds, proposed in 2009, is broken in practice in a chosen plaintext/chosen ciphertext scenario. Extrapolating these results suggests that up to 28 rounds of such ciphers can be broken. Furthermore, we outline how our attack strategy can be applied to an extreme case where the S-boxes are chosen uniformly at random for each round, and where the bit permutation is key-dependent as well.     

Piezoelectric fields in one- and two-dimensional heterostructures fabricated on high-index surfaces

We present a theoretical study of the strain-induced piezoelectric fields which may occur in one- and two-dimensional III–V compound semiconductor heterostructures on high-index surfaces. The strain tensor components of the low-dimensional structures are calculated by minimization of the strain-energy density and by imposing appropriate constraints at the heterointerfaces. We obtain a tetragonal deformation for two-dimensional heterostructures grown on the high symmetry surfaces, while in the case of high-index surface orientations a monoclinic lattice deformation is obtained. For the one-dimensional heterostructures, which are fabricated from superlattices grown on thick substrate crystals and are laterally confined by air, a lower symmetry lattice deformation than a tetragonal one may also occur for the [001]-substrate orientation, as a result of the anisotropic elastic lattice relaxation. In zincblende heterostructures, these particular strain fields can generate high internal electric fields. In two-dimensional heterostructures, these piezoelectric fields appear for the [111] or for higher-index interface orientations. However, in one-dimensional heterostructures the strain fields can generate high piezoelectric fields even for the high-symmetry [001]-interface orientation.     

Importance of characterizing a reference filter test system

Standards governing the performance of air filters are there to enable comparisons to be made between different filter tests. However, measurement data from different filter test systems can vary widely, making comparisons difficult. Palas GmbH, Germany, has developed a modifed test system that it says meets the minimum requirements of a reference filter test system.