A comparison of leaf-spring with aircushion trailer suspensions in the transport environment

Packaging engineers need to be able to accurately determine the forces present in the shipping environment in order to protect packaged goods. The purpose of this study was to determine the vertical vibration levels measured in three separate truck-trailer suspension systems; conventional leaf-spring, conventional air-ride and damaged air-ride. The main conclusion reached in this study is that the air-ride suspension when maintained gives lower power density (PD) levels on all road surfaces studied. A damaged air-ride suspension and leaf-spring suspension are very similar in response frequencies, although the damaged air-ride produces higher vibration levels at lower frequencies.     

Three-dimensional fracture simulation with a single-domain,direct boundary element formulation

An efficient hypersingular boundary integral equation method for three-dimensional fracture mechanics was presented in a previous paper. The details of the numerical implementation of this method are further discussed herein. In particular, an algorithm for achieving the required differentiability of the crack surface displacement function is discussed. To illustrate the utility of the method, computational results for several strongly interacting multiple-crack geometries are presented. The calculated stress intensity factors are in excellent agreement with those obtained by an approximate analytical method due to Kachanov and Laures.     

β-Si3N4Whiskers Embedded in Oxynitride Glasses: Interfacial Microstructure

Interfacial microstructures in βP-Si₃N₄( w )-Si-Al-Y-O-N-glass systems were investigated by systematically varying the nitrogen content and the Al:Y ratio of the glass matrix. High-resolution and analytical transmission electron microscopy (HREM and AEM) studies revealed that the interfacial microstructure is a function of the glass composition. No interfacial phases were formed in glasses with low Al:Y ratios and in glasses with high Al:Y ratios and low nitrogen content, whereas epitaxial growth of an interfacial layer (100–200 μm thick) on the βP-Si₃N₄( w ) occurred in a glass matrix with high Al:Y ratio and high nitrogen content. The interfacial layer was identified to be a β'-SiAION phase. Interfaces containing the SiAION layer exhibited high debonding energy compared to Si₃N₄( w )–glass interfaces. HREM studies indicated that the lattice-mismatch strain in the SiAION layer was relieved by dislocation formation at the SiAION–Si₃N₄( w ) interface. The difference in interfacial debonding energy was, hence, attributed to the local atomic structure and bonding between the glass-β-Si₃N₄ and the glass–β'-SiAION phases. This observation was clear evidence of the strong influence of glass chemistry on the interfacial debonding behavior by altering the interfacial microstructure.     

HER-2/c-erbB2 is phosphorylated by calmodulin-dependent protein kinase II on a single site in the cytoplasmic tail at threonine-1172

Calmodulin-dependent protein kinase II (Cam kinase II) is known to desensitise epidermal growth factor receptor (HER-1) tyrosine kinase activity by a process involving phosphorylation at serines 1046/47 in the cytoplasmic tail. We have developed an experimental system to investigate phosphorylation of the related HER-2/c-erbB2 proto-oncogene utilising purified Cam kinase II and recombinant glutathione-S-transferase (GST) fusion proteins. The cDNA for rat Cam kinase II-alpha was transfected into human embryonic kidney (HEK) 293 fibroblasts and the expressed protein purified to homogeneity by calmodulin-agarose affinity chromatography. A GST fusion protein comprising residues 1126-1255 of HER-2 was phosphorylated by purified Cam kinase II, in contrast to a GST protein comprising residues 1005-1125. Phosphoamino-acid analysis and site-directed mutagenesis indicated that HER-2 was phosphorylated on a single site at threonine-1172 which resides within a consensus Cam kinase II phosphorylation site (RAKT). HER-2 (threonine-1172-alanine), in the form of a ligand-inducible chimaera HER-1/2, was co-transfected into HEK-293 fibroblasts with a constitutively active form of Cam kinase II, followed by in vivo labelling of these cells with 32 P-orthophosphate. Immunoprecipitation of ligand-activated receptors followed by two-dimensional phosphopeptide mapping indicated that threonine-1172 in HER-2 is a newly identified in vivo site which can be hyper-phosphorylated by constitutively active Cam kinase II. In addition, when over-expressed in HEK-293 fibroblasts, HER-1/2 (threonine-1172-alanine) showed a defect in desensitisation and underwent a more sustained EGF-induced receptor autophosphorylation compared to wild-type HER-1/2.     

Some results on generalized residual entropy

Shannon’s entropy plays an important role in the context of information theory. Since this entropy is not applicable to a system which has survived for some units of time, the concept of residual entropy has been developed in the literature. Here we generalize the residual entropy by choosing a convex function ? with ?(1) = 0. In this paper, some orderings and aging properties have been defined in terms of the generalized residual entropy function and their properties have been studied. Quite a few results available in the literature have been generalized and some distributions (viz. uniform, exponential, Pareto, power series, finite range) have been characterized through the generalized residual entropy.     

Putting it all together – Formal verification of the VAMP

In the verified architecture microprocessor (VAMP) project we have designed, functionally verified, and synthesized a processor with full DLX instruction set, delayed branch, Tomasulo scheduler, maskable nested precise interrupts, pipelined fully IEEE compatible dual precision floating point unit with variable latency, and separate instruction and data caches. The verification has been carried out in the theorem proving system PVS. The processor has been implemented on a Xilinx FPGA. A shorter version of this article with the title “Instantiating uninterpreted functional units and memory system: functional verification of the VAMP” appeared in [8]. The work reported here was done while all the authors were with Saarland University.