Design tool and its experimental validation for SOA-based photonic signal processing

This paper reports a unified, accurate and fast simulation tool, able to describe photonic SOA-based digital processing schemes. The model exploits cross gain modulation in SOAs in time resolved analysis in which each amplifier can be thought of as a point amplifier. Simulation and experimental comparisons of the steady state and dynamic amplified spontaneous emission noise behaviour of SOA are carried out. Details of multistage modelling useful for long nonlinear SOA has been described. Implementation of schemes such as combinatorial logic functions may require many cascading SOAs and contribution of ASE noise from each amplifier also been taken into account. A procedure of the extraction of parameters from the commercial SOA utilised in the experiment is laid down. Various sources of degradation have been identified and the method for evaluation of bit error rate for complex SOA based combinatorial network has been outlined. The tool is validated through the implementation of a photonic bit comparator. Important design guidelines are extracted by the proposed tool.     

Poly(vinylpyrrolidone) as a tool: aqueous dispersion of nanodiamonds by wrapping in the solid state

Among carbon‐based nanomaterials such as fullerenes, carbon nanotubes and nanodiamonds, the latter are good candidates as prospective materials in the future due to their potential physical, chemical and biological properties. Thus, nanodiamonds were wrapped with biocompatible polymers in the solid state. The dispersibility of the polymer‐wrapped nanodiamonds in water was investigated with respect to reaction time and mass ratio of the polymers during the wrapping process. The dispersibility of the materials was monitored using UV spectroscopy, and the size distribution of the polymer‐wrapped nanodiamonds was analyzed using high‐resolution transmission electron microscopy and dynamic light scattering measurements. In addition, molecular modeling calculations were performed. Finally, the best dispersion for the polymer‐wrapped nanodiamonds in water was found for a reaction time of 120 min. Copyright © 2012 Society of Chemical Industry     

Novel applications of solid and liquid formulations of nanoparticles against insect pests and pathogens

Nanoparticles are of special interest because of their markedly different physico-chemical properties than their bulk counterparts. This review covers the use of these novel agents to combat real life agricultural and medical issues important to Indian subcontinent. Nanoparticles of oxides like SiO₂ produced and characterized in our laboratory were tested against insect pests and pathogens. Nanosilica against insect pests shows nearly 100% mortality. Survivability of grasserie afflicted silkworm increased from 0% to 30% with hydrophobic nano-aluminosilicate. Treatment of multi-drug resistant tuberculosis with nanosilver and trypanosome infected mice with Dsethvasan showed significant protection. Sporulation and growth of fungi were inhibited by nanosulfur.     

Relationships between Properties of Some Jute Yarns and Fabrics

A series of jute hessian fabrics was woven in which the warp and weft components were varied systematically, and appropriate measurements, i.e., fabric mass per unit area, breaking load, extension at break, and bursting pressure, were made to explore the relationships with the fabric structure and the properties of constituent yarns. The breaking loads at the higher weft linear densitites were greater in relation to the breaking load of the single yarns than those at the lower linear densities. The extension at break of the fabric ranged between 4.45% and 4.78%. The bursting pressure of the fabric changed at the rate of 1.4 kN/m² for a change of 1 pick/cm.     

Supply chain efficiency: a simulation cum DEA approach

The management of risks within the supply chain and external to it has become highly critical component of supply chain management. Inventory management is a vital tool to mitigate these risks. Lead times and review periods are important parameters in inventory management. The organizations focus on these parameters to enhance the system-wide supply chain performance in terms of services to customers. This paper aims at analyzing the efficiency of total supply chain in context of average fill rate performance. We analyze the efficiency of a hypothetical supply chain network structure which is subjected to time delays due to lead time and inventory review period changes. To understand the optimal relative efficiency among different values of average fill rate performance obtained through simulation, we used Data Envelopment Analysis approach (DEA). Taguchi experimental design procedure is used as a vehicle for conducting the simulation experiments and analyzing its outcome. The proposed integration of simulation with DEA framework provides practical implications to the decision maker as well as connotes to the real world situation where different enterprises compete for the frontier supply chain efficiency.     

Sensitivity-tuned CO gas sensors with tailored Ga-doping in ZnO nanowires

Sensitivity-customization of zinc oxide (ZnO) nanowire (NW) gas sensors has been demonstrated by controlling Ga-doping, thereby tuning the resistance of the NWs. Both un-doped and 5 weight% Ga-doped ZnO (GZO) NWs are synthesized for the highly sensitive sensing within a narrow detection window and a less sensitive one within an expanded window, respectively. We have employed hot-walled pulsed laser deposition (HW-PLD) for the NW synthesis. With CO gas injection, the resistance reduction of NWs is detected and analyzed in a self-designed gas chamber that guarantees the precise control of gas flow and, gas concentration, as well as temperature. NW sensitivity is proportional to the sensing temperature and inversely proportional to the doping concentration resulting in widening the sensing window up to 230 times by the 5 wt.% Ga-doping.     

Shell-crossing singularities in Szekeres quasispherical models

We investigate the occurrence of shell-crossing singularities in Szekeres quasispherical dust models with or without a cosmological constant. We study the conditions for a shell-crossing singularity from both physical and geometric poinst of view, and they are in agreement.     

Integrating economic and hydrologic interdependence in reservoir management

The purpose of this study is to determine the optimal allocation of reservoir water among competing uses (hydroelectric power generation, lake recreation and urban and rural water supply). An optimization model using nonlinear programming is developed to optimally allocate reservoir water among these uses. It is not unusual to optimize the values for flood control, hydroelectric generation, and urban and rural water uses, and to determine recreation values as a residual. Furthermore, if recreation values are considered, it may be in the form of constraints that maintain reservoir water levels within a specified range. In contrast, this study develops a model in which the recreational benefits depend explicitly on lake water levels, while the flood control capacity of the reservoir is maintained through upper bounds on the lake level. A mass balance equation is used to determine the water levels and volumes in the lake for each month over a twelve‐month period. The General Algebraic Modeling System with MINOS is used to solve this model. The results indicate that the total economic benefits for Lake Tenkiller could be increased by directly including recreational values in the model, and maintaining lake water levels at near‐normal levels that maximize the number of summer visitations. The optimal allocation of Lake Tenkiller water among competing uses also satisfies the equimarginal principle. That is, the marginal value of water at the lake in each month is the same for the last unit of water used for hydroelectric, recreational, or urban and rural water uses. Use of this type of modelling framework would assist policymakers or reservoir managers in reallocation of reservoir water and in calibrating several policy scenarios.     

Effect of carbon black and nanoclay on mechanical and thermal properties of ABS–PANI/ABS–PPy blends

Acrylonitrile butadiene styrene (ABS)–polyaniline (PANI) and ABS–polypyrrole (PPy) blends exhibit poor mechanical and thermal properties due to their weak interfacial adhesion and inhomogeneous mixing. The properties have been improved by addition of carbon black (CB) and nanoclay (NC). Composites are prepared by mixing CB and NC with ABS–PANI and ABS–PPY blends. The morphology and crystalline characteristics are studied using field emission scanning electron spectroscopy (FESEM) and X‐ray diffraction, respectively. In addition, all the composites have been analyzed for their mechanical and thermal performance. The tensile strength of ABS–PANI has been increased by 7.18% and 65.83% with addition of CB and a combination of CB–NC, respectively. FESEM images are found supportive with these trends and show homogeneous dispersion of CB in the polymer matrix, assisted by NC. Dynamic mechanical analysis results also show slight improvement of glass transition temperature (T_g) with addition of fillers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42577.