Failure analysis of oxygen hose of the lance equipment in LD shop of Tata steel

The hose of the oxygen lancing equipment in LD shop # 2 has failed at the weld–bellows interface by reverse bending fatigue. The bending stresses were resulted due to inclined fitting of the hose at the fixed flange end. No metallurgical abnormalities or weld defects or mechanical damages were responsible for the fatigue crack initiation. It is recommended that if inclined fitment of the hose is not a process requirement, the original design be restored to realize the expected life of the component. On the other hand, if inclined fitment cannot be avoided, additional support may be provided for the hose at the fixed flange end to avoid reverse bending at the weld–bellows interface. A detailed analysis of the failure is presented in this report.     

New mesoporous titanium–phosphorus mixed oxides having bifunctional catalytic activity

New mesoporous titanium–phosphorus mixed oxides templated by non-ionic triblock copolymer Pluronic F127 under evaporation induced self-assembly (EISA) method and using unconventional phosphorus source trimethylphosphite have been reported. Powder XRD, TEM and N₂ sorption studies are employed to characterize the mesophases. TPD-NH₃ experiments suggested an increase in surface acidity with the increase in the molar ratio of Ti/P in these mesoporous mixed oxides from 1 to 2. Interestingly these mesoporous materials showed excellent bifunctional catalytic activity in acid catalyzed Friedel–Crafts benzylation of bulky aromatics and partial oxidation of styrene to benzaldehyde with dilute H₂O₂ oxidant under mild liquid phase conditions.     

Validation of an improved dislocation density based flow stress model for Al-alloys

A microstructure and flow stress model for cell forming metals, 3IVM (3 Internal Variables Model), was developed [1], in which the work hardening and softening effects due to interaction of dislocation densities are taken into account. This model had been applied in through process modelling of sheet production. In the present paper, improvements of 3IVM are introduced. In the new model (3IVM+) the softening effect of recovery by cross slip and by additional dislocation reactions are considered in addition to that of climb. Moreover an improved kinetic equation of state is utilized. For validation, compression tests on a commercial Al-alloy were carried out and the flow curves were determined. The comparison between model predictions and experimental results shows that 3IVM+ can replicate the flow curves much better than the previous model, in particular at low temperatures and in wide temperature range. Since the concept of the model is unchanged, its applicability for through process modelling is not compromised.     

Hydrogen-Assisted Cracking in Boiler Steam Drums

A statutory inspection of a boiler steam drum that had seen 10 years of service revealed a few scattered cracks on the inner surface of the drum. The drum was used in the refinery and petrochemical industry. Remnant life assessment, including inspection of other drums, showed presence of several cracks in two out of seven boiler inspected. In situ microstructural analysis revealed a variation in the microstructure in the cracked regions compared to the microstructure in uncracked regions. Additionally, a wide variation in hardness was associated with the microstructural variation. Detailed study on a sample extracted from a cracked region demonstrated that the cracking occurred in a crescent zone similar in appearance to that of a heat affected zone (HAZ) generally associated with a spot weld or other sources of hot spots in the material. Subsequent examination of more samples confirmed that repair welding was carried out at several places on the inner surface of the drums before installation and commissioning and all the cracks were around the repair welds. The failure occurred by crack initiation in the HAZ of the repair welds and the cracks then propagated progressively across the inner surface of the drums. The failure mechanism was identified to be cold cracking and the failure analysis showed that all the factors required for cold cracking, namely, vulnerable microstructure, residual stresses and hydrogen atmosphere, during welding had been present in the drum material.     

Decoupling Capacitor Estimation and Allocation using Optimization Techniques for Power Supply Noise Reduction in System-on-Chip

Journal of Electronic Testing - This article examines the signal integrity problem arising due to resistive drop, inductive noise and electro- migration, causing voltage fluctuations known as...     

经济宽带通信用的理想光纤

宽带指的是大容量、高速率(一般双向的速率超过256 kb it/s),因特网或网络的连接是通过比普通铜电话线的带宽高得多的同轴电缆或光缆实现的。宽带信道可以同时传输语音、图像和数据。现在有许多不同的技术适用于宽带通信,如铜线可用于数字用户线(DSL)技术,光纤技术可用于光纤到户(FTTH),有线电视网络和无线技术可用于W iF i和W i-M ax。光纤技术可以为采用FTTH网络(即光纤到最后一英里)的用户提供宽带业务。在城域网和接入网中使用理想光纤(ITUTG.652D)的特点是,理想光纤可以提供宽带业务。究其原因是低水峰ITUTG.652D在1 383±3 nm具有低衰减和小偏振模色散(PMD),从而满足和超过宽带网络对理想光纤的性能要求。     

Xenon molecular laser in the vacuum ultraviolet

Vacuum ultraviolet emission from high-pressure Xe gas under excitation by a pulsed electron beam has been investigated. When cavity mirrors were provided, significant line narrowing and a thousandfold increase in spectral intensity occurred at 1730 ± 10 Å. This was accompanied by severe mirror burning and provides strong evidence that an associative molecular Xe laser has been achieved.     

Fragment docking to S100 proteins reveals a wide diversity of weak interaction sites

The S100 protein family is a highly conserved group of Ca(2+)-binding proteins that belong to the EF-hand type and are considered potential drug targets. In the present study we focused our attention on two members of the family: S100A13 and S100B; the former is involved in the nonclassical protein release of two proangiogenic polypeptides FGF-1 and IL-1alpha that are involved in inflammatory processes, whereas S100B is known to interact with the C-terminal domain of the intracellular tumor suppressor p53 and promote cancer development. We screened, using waterLOGSY NMR experiments, 430 molecules of a generic fragment library and we identified different hits for each protein. The subset of fragments interacting with S100B has very few members in common with the subset interacting with S100A13. From the (15)N-HSQC NMR spectra of the proteins in the presence of those hits the chemical shift differences Deltadelta(HN) were calculated, and the main regions of surface interaction were identified. A relatively large variety of interaction regions for various ligands were identified for the two proteins, including known or suggested protein-protein interaction sites.     

A study on the structural and mechanical properties of nanocrystalline CuS thin films grown by chemical bath deposition technique

We report a chemical route for the deposition of nanocrystalline thin films of CuS, using aqueous solutions of Cu(CH₃COO)₂, SC(NH₂)₂ and N(CH₂CH₂OH)₃ [triethanolamine, i.e. TEA] in proper concentrations and ratios. The films were structurally characterized using X-ray diffraction technique (XRD), field emission scanning electron microscopy (FESEM) and optical analysis [both photo luminescence (PL) and ultraviolet-visible (UV-vis)]. Optical studies showed a large blue shift in the band gap energy of the films due to quantum confinement effect exerted by the nanocrystals. From both XRD and FESEM analyses, formation of CuS nanocrystals with sizes within 10-15 nm was evident. A study on the mechanical properties was carried out using nanoindentation and nanoscratch techniques, which showed good mechanical stability and high adherence of the films with the bottom substrate. Such study on the mechanical properties of the CuS thin films is being reported here for the first time. Current-voltage (I-V) measurements were also carried out for the films, which showed p-type conductivity.     

On stability of NiTi wire during thermo-mechanical cycling

The use of NiTi wire as thermal actuator involves repeated thermal cycling through the transformation range under a constant or fluctuating load. The stability of the material under such conditions has been a concern for the past many years. Experimental results show that for a given alloy composition, the repetitive functional behaviour of NiTi wire is largely dependent on the processing schedule/parameters and the stress-strain regime of thermo-mechanical cycling (TMC). Among the various processing parameters, retained cold work in the material and the shape memory annealing temperature/time have significant influence. It has been shown in the present study that for a stable functional behaviour, the material needs to be tailored through judicious selection of these parameters. Study also shows that, after processing, the material requires an additional stabilization treatment for ensuring minimal variation in the repetitive functional response upon TMC.