Synthesis and characterization of iron oxide nanoparticles by solvothermal method

In the present work iron oxide nanoparticles have been synthesized by alkaline solvo thermal method using anhydrous ferric chloride, sodium hydroxide, polyethylene glycol and cetyl trimethyl ammonium bromide and characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray Spectroscopy (EDX) and Thermal Gravimetric Analysis (TGA). XRD indicated that the product is a mixture of different phases of iron oxide viz. gamma-Fe₂O₃ (maghemite, tetragonal), Fe₂O₃ (maghemite, cubic), Fe₃O₄ (magnetite, cubic) and ?-Fe₂O₃(epsilon iron oxide). FESEM studies indicated that size of the particles is observed in the range of about 19.8 nm to 48 nm. EDX spectral analysis reveals the presence of carbon, oxygen, iron in the synthesized nanoparticles. The FTIR spectra indicated absorption bands due to O-H stretching, C-O bending, N-H stretching and bending, C-H stretching and Fe-O stretching vibrations. TGA curve represented weight loss of around 3.0446 % in the sample at temperature of about 180°C due to the elimination of the water molecules absorbed by the nanoparticles from the atmosphere.     

Dynamic response of full-scale sandwich composite structures subject to air-blast loading

Glass-fibre reinforced polymer (GFRP) sandwich structures (1.6 m × 1.3 m) were subject to 30 kg charges of C4 explosive at stand-off distances 8–14 m. Experiments provide detailed data for sandwich panel response, which are often used in civil and military structures, where air-blast loading represents a serious threat. High-speed photography, with digital image correlation (DIC), was employed to monitor the deformation of these structures during the blasts. Failure mechanisms were revealed in the DIC data, confirmed in post-test sectioning. The experimental data provides for the development of analytical and computational models. Moreover, it underlines the importance of support boundary conditions with regards to blast mitigation. These findings were analysed further in finite element simulations, where boundary stiffness was, as expected, shown to strongly influence the panel deformation. In-depth parametric studies are ongoing to establish the hierarchy of the various factors that influence the blast response of sandwich composite structures.     

Removal of soy protein-bound phospholipids by a combination of sonication, β-cyclodextrin,and phospholipase A2 treatments

One of the contributing factors to generation of off-flavours in soy protein isolate (SPI) during storage is autoxidation of residual amounts of phospholipids present in SPI. Thus, removal of phospholipids from SPI is a likely first step to improve its flavour stability and enhanced utilisation of SPI in food products. We describe a β-cyclodextrin-based (βCD) process to remove protein-bound phospholipids and free fatty acids in SPI. Treating SPI solution (8%) with 10 mM βCD alone at pH 8.0 decreased the phospholipid content of SPI by about 36%. A greater than 99% removal of phospholipids and free fatty acids was achieved by using a combination of treatments involving sonication of the SPI solution for 5 min at 50 °C followed by treatment with phospholipase A₂ and βCD. SPI prepared by this method was white in colour. The results presented here offer a process for removing residual off-flavour causing phospholipids from soy protein.     

Growth of undoped and Te doped InSb crystals by vertical directional solidification technique

We have successfully grown high mobility undoped and Te doped InSb crystals of size 10–12 mm dia. and 60 mm length under inert argon atmosphere in closed quartz ampoules, by vertical directional solidification (VDS) technique. The crystals showed predominantly (220) orientation along the growth axis. The surface defects, such as voids were reduced drastically by selecting proper lowering rate, rotational speed and cone angle of the ampoule. The high mobility and quality crystals were obtained with the ampoule conical angle less than 20°, lowering rate 5mm/h, and rotational speed 10 rpm.     

Continuous accountability for acceptable building performance

Complexities in building technology when not fully understood, have resulted in a less than favorable aggregate impact on the building's environment. A surprisingly high portion of U.S. non-industrial buildings do not provide satisfactory task environments. Developments in computer technology have infused new thought processes in the way we plan, design, build and operate our buildings. This paper proposes a social and technical use of Knowledge-based-systems (KBS) for continuous accountability to assure healthy buildings. Diagnostics, as an emerging discipline in building design and operation, is also discussed. A proposed framework for such accountability and the resulting ‘chain of custody’, that draws on the medical paradigm and associated diagnostic procedures is presented. It is suggested that KBS also be used for the development and interpretation of criteria for evaluating building performance from initial conception through design, construction and operation. Thus, KBS is expected to aid in the analysis of ‘virtual’ and ‘actual’ buildings that may be ‘sick’ or ‘healthy’. It is proposed that for a building to provide satisfactory performance over its life-time, the ‘life-cycle’ concept must be modified in terms of the roles, responsibilities, and configuration of the building team, and in terms of its costing procedures.     

Electrochemical etching of highT c superconducting materials

HighT _c superconductor materials of yttrium barium copper oxide (YBCO) have been etched by a new electrochemical technique. In this technique, acids like hydrochloric, nitric and phosphoric have been used as an electrolyte and etching has been achieved with acid dilutions as high as 1:200 with water. It is observed that rapid and controlled etching is possible by this technique.     

Availability analysis of steam and power generation systems in the thermal power plant

The paper discusses the availability analysis of a steam generation system consisting of three subsystems A, B and D and a power generation system consisting of four subsystems E, F, G and H arranged in series, with three states viz., good, reduced and failed. Taking constant failure and repair rates for each working unit, the mathematical formulation is done using the Birth-Death process. Expressions for steady state availability and the MTBF (mean time between failure) are derived. The graphs are given, depicting the effect of failure and repair rates on the system availability. The results are supplied to the plant personnel, to plan the policies for failure free running of the systems for a long duration.     

Numerical and experimental analysis of large passivation opening for solder joint reliability improvement of micro SMD packages

In this paper, using a recently developed solder fatigue model for wafer level-chip scale package (WL-CSP), we investigated the improvement on solder joint reliability for a 8-bump micro SMD package by enlarging the passivation layer opening at the solder–die interface. The motivation to enlarge the passivation opening is to reduce the severity of the stress concentration caused by the original design, and also to increase the contact area between the solder bump and aluminum bump pad. It was confirmed in the thermal shock test that with the new design, package fatigue life improved by more than 70%. To numerically predict this improvement represents a unique challenge to the modeling. This is because in order to capture the slightest geometrical difference on the order of a few microns between the two designs, the multiple-layer solder-die interface needs to be modeled using extremely fine mesh, while the overall dimensions of the package and the test board are on the order of millimeters. To bridge this tremendous gap in geometry, a single finite element model that incorporates all necessary geometrical details is deemed computationally prohibitive and impractical. In this paper, we applied a global–local modeling scheme that was also suggested by others [1, 2 and 3]. The global model contains the complete package with much simplified solder–die interface whereas the local model includes only one solder joint, but with detailed solder–die interface. Unlike most global–local models proposed by others, we included time-independent plasticity and temperature-dependent materials in the global model. This greatly improved model correlation accuracy with only moderate increase in run time. Energy-based solder fatigue model was used to correlate the inelastic strain energy with the package fatigue life. In an earlier study [4], we have found that Darveaux’s equations tended to be conservative when applied to the micro SMD, and hence new correlations based on curve-fitting the test data were derived. In this paper, we used the newly derived equation and achieved less than 20% error in N₅₀ life for both designs, which is on par with Darveaux’s equations when used for BGAs. The analysis also revealed two factors that may account for the life improvement. First, a slight decrease in inelastic energy dissipation after enlarging the passivation opening. Second, the shift of the crack initiation location which leads to longer crack growth length for the new design. The second factor was also independently confirmed by the failure analysis.     

Data base design methodology for structural analysis and design optimization

A methodology to design data bases for finite element analysis and structural design optimization is described. The methodology considers three views of data organization-conceptual, internal, and external. Tabular and matrix forms of data are included. The relational data model is used in the data base design. Entity, relation, and attributes are considered to form a conceptual view of data. First, second, and third normal forms of data are suggested to design an internal model. Several aspects such as processing, iterative needs, multiple views of data, efficiency of storage and access time, and transitive data are considered in the methodology.