Fast and accurate 4‐node quadrilateral

An accurate and variationally consistent 4‐node quadrilateral element is introduced where high coarse mesh accuracy and low mesh distortion sensitivity are characteristic qualities, even when incompressibility is approached for plane strain. One‐point quadrature integration procedure is adopted and a new improved stabilization technique is developed. Orthogonality conditions are utilized so that the patch test is satisfied for arbitrary quadrilaterals. Several numerical examples including a convergence rate study are presented which confirm the excellent performance of this element. Copyright © 2004 John Wiley & Sons, Ltd.     

On the off-design of a natural gas-fired combined cycle with CO2 capture

During the last 15 years cycles with CO₂ capture have been in focus, due to the growing concern over our climate. Often, a natural gas fired combined cycle with a chemical absorption plant for CO₂ capture from the flue gases have been used as a reference in comparisons between cycles. Neither the integration of the steam production for regeneration of amines in the combined cycle nor the off-design behaviour of such a plant has been extensively studied before.     

Heat of solidification in refractory metals studied by drop-tube experiments

A number of pure refractory metals have been investigated by drop-tube experiments. The cooling curves have been registered and theoretically analysed. A model for analysing the heat of fusion has been developed. It was found that the heat of fusion was approximately 50% of the tabulated value.     

Influence of melt temperature on Rapid solidification of Al-Y and Al-Si alloy system

Solidification behavior of Al-Y and Al-Si were investigated for different melt temperatures. Levitation casting technique was used to achieve a cooling rate of around ～2000K/s during the experiment. Light optical microscopy (LOM) and Scanning electron microscopy (SEM) were used to analyze the samples. An energy dispersive system (EDS) analysis of SEM was performed on the samples to identify the phases. Plate like structure of Al₈Y₃ primary phase was observed at low melt temperature with small percentage of peritectic transformation of Al₈Y₃ and liquid melt into Al₉Y₂. A pre-dentritic star like crystal of Al₃Y was observed in a fine eutectic matrix at very high melt temperature. Amount and number of primary Si crystals formed in a unit area during the solidification increases as the melt temperature increases. It is believed the melt temperature affects the solidification pattern by changing chemical short range order.     

On solidification of hypereutectic Al-Si alloys

Precipitation of primary silicon was studied in Al-Si hypereutectic alloys with 15, 18, and 25 wt. % silicon content. The alloys were solidified with different cooling rates from different super heat temperatures. The liquidus and eutectic temperature were evaluated from the cooling curves. The liquidus temperature was found to decrease with cooling rate. The evaluation of microstructure showed that the fraction of primary silicon decreased with increasing the cooling rate and super heat temperature. Furthermore, the morphology of the primary silicon changed as an effect of cooling rate and super heat temperature.     

XPS analysis of manganese in stainless steel passive films on 1.4432 and the lean duplex 1.4162

Passive films were compared on two stainless steels: the recent lean duplex EN 1.4162 and EN 1.4432 (316L). For alloys with significant amount of manganese and nickel, the Mn 2p_3/2 peak will overlap with the Ni-LMM. To resolve this overlap, Ni 2p_3/2 to Ni-LMM intensity ratios were recorded on 1.4432, compensated for overlayer thickness, and then used to fix the Ni-LMM intensities in the Mn 2p spectra on the duplex material. Manganese was found in oxidation states II and V/VI; its film content was not dependent on the bulk composition.     

Efficient parameterized string matching

In parameterized string matching the pattern P matches a substring t of the text T if there exist a bijective mapping from the symbols of P to the symbols of t. We give simple and practical algorithms for finding all such pattern occurrences in sublinear time on average. The algorithms work for a single and multiple patterns.     

A national meeting for medical students--new pedagogic approach. High tempo visits to different scientific fields]

The methionine analogue 2-amino-5-hexenoic acid (homoallylglycine, Hag) can be utilized by Escherichia coli in the initiation and elongation steps of protein biosynthesis. Use of an E. coli methionine auxotroph and Hag-supplemented medium resulted in replacement of ca. 85% of the methionine residues in mouse dihydrofolate reductase expressed under control of a bacteriophage T5 promoter. N-terminal sequencing indicated 92+/-5% occupancy of the initiator site by Hag. The vinyl function of Hag remains intact in the purified protein and suggests new chemistries for modification of natural and artificial proteins prepared in bacterial hosts.