Stability analysis and design of stabilization measures for Chenab railway bridge rock slopes

Bulletin of Engineering Geology and the Environment - This article presents the challenges encountered during the stability analysis and stabilization of two Himalayan rock slopes supporting the...     

Novel nonlinearity minimized time-to-digital converters with digital calibration technique

Analog Integrated Circuits and Signal Processing - This paper presents a low nonlinearity, four channel Gated Ring Oscillator (GRO) based Time-to-Digital Converters (TDC) in Xilinx 28 nm...     

Synthesis, characterization and optical properties of Mg(OH)2 micro-/nanostructure and its conversion to MgO

Magnesium hydroxide (Mg(OH)₂) micro- and nanostructures have been synthesized by a single step hydrothermal route. Surface morphology analysis reveals the formation of micro- and nanostructures with varying shape and size at different synthesis conditions. Structural investigations by X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirm that the synthesized material is Mg(OH)₂ with hexagonal crystal structure. An optical band gap of 5.7 eV is determined for Mg(OH)₂ nanodisks from the UV–vis absorption spectrum. A broad emission band with maximum intensity at around 400 nm is observed in the photoluminescence (PL) spectra of Mg(OH)₂ nanodisks at room temperature depicting the violet emission, which can be attributed to the ionized oxygen vacancies in the material. Furthermore, Mg(OH)₂ has been converted to MgO by calcination at 450 °C. Optical studies of the MgO nanodisks have shown an optical band gap of 3.43 eV and a broadband PL emission in the UV region. Mg(OH)₂ and MgO nanostructures with wide-band gap and short-wavelength luminescence emission can serve as a better luminescent material for photonic applications.     

Effect of reinforcement form on the bearing capacity of square footings on sand

This paper presents the results of laboratory model loading tests and numerical studies carried out on square footings supported on geosynthetic reinforced sand beds. The relative performance of different forms of geosynthetic reinforcement (i.e. geocell, planar layers and randomly distributed mesh elements) in foundation beds is compared; using same quantity of reinforcement in each test. A biaxial geogrid and a geonet are used for reinforcing the sand beds. Geonet is used in two forms of reinforcement, viz. planar layers and geocell, while the biaxial geogrid was used in three forms of reinforcement, viz. planar layers, geocell and randomly distributed mesh elements. Laboratory load tests on unreinforced and reinforced footings are simulated in a numerical model and the results are analyzed to understand the distribution of displacements and stresses below the footing better. Both the experimental and numerical studies demonstrated that the geocell is the most advantageous form of soil reinforcement technique of those investigated, provided there is no rupture of the material during loading. Geogrid used in the form of randomly distributed mesh elements is found to be inferior to the other two forms. Some significant observations on the difference in reinforcement mechanism for different forms of reinforcement are presented in this paper.     

Blends of unsaturated polyester and phenolic resins for application as fire-resistant matrices in fibre-reinforced composites. Part 1: identifying compatible, co-curable resin mixtures

An unsaturated polyester resin, cured with styrene of commercial origin, has been blended and cured with several commercial phenolic resoles with a view to obtain a homogeneous polymer blend having better fire resistance than unsaturated polyester alone. It is shown that blends of the unsaturated polyester with an allylically modified resole are not only physically compatible (miscible), but also chemically compatible in which they co-cure to an extent to give, probably, a co-continuous interpenetrating polymer network.     

Automated design algorithms for tactical wireless networks

To guide users who attempt to deploy wireless networks in military applications, there is an evolving need for developing systematic methodologies to analyze/predict the performance of mobile ad hoc networks (MANETs). In addition, the advance in cognitive networking research provides opportunities for exploiting unused spectrum to optimize throughput of MANETs. However, with the increasing number of parameters/constraints, there is even a more demanding need to develop automated methodologies to design/tune such networks.In this work, we study the concepts and challenges for automatic design/re-configuration of cognitive MANETs, in addition to proposing design automation algorithms. The paper is divided into two parts. In the first part, we describe the design objectives, imposed constraints, and involved parameters in MANET design. We discuss how cognitive techniques can be employed to exploit the unused spectrum in military architectures. We then discuss the challenges that face the design/re-configuration of a cognitive network and their implications at different network layers. We also describe possible implementation options for designing MANETs that employ cognitive features at all layers. In the second part of this work, we propose design automation algorithms for optimally setting parameters to achieve a desired objective and satisfy certain constraints. Despite providing the optimal configuration, the simple approach of testing all possible combinations of parameter settings has significant time complexity (the COMB approach). Thus, we propose a novel heuristic (Sequential Parameter Optimization or SEPO) for searching through the possible parameter settings and selecting the best design options. SEPO is efficient in terms of both convergence speed and parameter tuning. We also discuss the foundation for using supervised learning to speed up the design (search) process. By evaluating realistic design of military-like scenarios that require optimizing a diverse set of metrics, we show that SEPO generates comparable results to the optimal, straightforward (slow-converging) COMB approach that is based on exhaustive search.     

Hydrodynamic analysis of flow fields for redox flow battery applications

Electrolyte flow distribution is an important factor that contributes to the performance of the overall efficiency of a redox flow battery system. In the present paper, a comparative study of the hydrodynamics of the serpentine and interdigitated flow fields has been performed. Ex situ experiments were conducted using the two flow fields in conditions typical of flow battery applications. Limited in situ testing has also been conducted. These bring out the surprising result that the pressure drop in the interdigitated flow field is less than that in the serpentine for the same flow rate. Computational fluid dynamics studies show strong under-the-rib convection in the reaction zone exists in both flow fields but with a shorter residence time in case of the interdigitated. It is posited that this may explain the superior electrochemical performance of cells with interdigitated flow fields.     

Structural,spectroscopic and electrochemical study of V5+ substituted LiTi2(PO4)3 solid electrolyte for lithium-ion batteries

Vanadium substituted LiTi₂(PO₄)₃ (LTP) samples of composition of Li_{1? x} [Ti_{2? x} V _x ](PO₄)₃ (x = 0.0, 0.05, 0.10 and 0.15) have been prepared by solid-state reaction method. XRD data for these compositions indicated the formation of phase pure materials of rhombohedral structure with space group R \(\bar 3\) c (167). Microstructural studies by scanning electron microscope indicated particle size in the range of 0.5–1 μm. Electrochemical impedance studies showed that ionic conductivity is high for x = 0.10 composition. a.c. and d.c. conductivity results up to 573 K are in accordance with the Jonscher’s power law. Cyclic voltammetry study showed its electrochemical stability in the voltage range from 0.5 to 3.5 V.     

Effect of food grade organic acids on inoculated S. aureus, L. monocytogenes, E. coli and S. Typhimurium in sheep/goat meat stored at refrigeration temperature

Sheep/goat forequarters procured from freshly slaughtered animals were decontaminated with hot water and inoculated with Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salmonella typhimurium. The forequarters were individually spray washed with 2% lactic acid and 1.5% acetic + 1.5% propionic acid combination. Total viable count (TVC) of the treated meat samples was reduced by about 0.52 and 1.16 log units with marginal changes in colour and odour scores. Inoculated organisms were found to be highly sensitive to acid combination treatment as compared to lactic acid alone. Shelf-life of acid and acid combination treated samples was increased to 8 and 11 days as against 3 days in untreated samples. Carcass washing with acid alone or acid combination was found to be suitable for extension of shelf-life and improvement in the sensory and microbiological quality of meat.     

Resistance of Microencapsulated <Emphasis Type="Italic">Lactobacillus acidophilus</Emphasis> LA1 to Processing Treatments and Simulated Gut Conditions

This investigation reports the effect of microencapsulation using sodium alginate and starch on the tolerance of probiotic Lactobacillus acidophilus LA1 to selected processing conditions and simulated gastrointestinal environments. The organism survived better in the protected form at high temperatures (72, 85, and 90 °C) and at high salt concentrations (1%, 1.5%, and 2%). The free cells were completely destroyed at 90 °C whereas the microencapsulated cells reduced by 4.14 log cycles. The log cycle reduction was 5.67 and 2.30, respectively, in free and protected cells when incubated for 3 h with 2% (w/v) NaCl. Homogenization did not affect the viability of the cells but led to the disruption of the protective encapsulating material around the cells. Microencapsulation provided better protection at simulated conditions of gastric pH (1.0, 1.5, and 2.0) and at high bile salt concentrations (1.0%, 1.5%, and 2.0%). The free and protected cells registered 5.47 and 2.16 log cycle reduction, respectively, after 3-h incubation at 2% bile salt (w/v). The release of the microencapsulated organisms in simulated colonic pH required 2.5 h. These studies demonstrated that microencapsulation of probiotic L. acidophilus LA1 in sodium alginate is an effective technique of protection against extreme processing conditions and under simulated gastrointestinal environment.