Comprehensive studies on polyethylenimine filled polypropylene and its potential application in carbon dioxide sequestration

Polypropylene (PP) was blended with branched polyethylenimine (PEI) with the aim to prepare blends having CO₂ adsorption property. The CO₂ adsorption properties will be conferred due to the presence of variety of amine functionality in PEI. PEI contains primary, secondary as well as tertiary amine groups. Before testing CO₂ adsorption, PP–PEI blends were characterized using variety of techniques, for example, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, scanning electron microscopy, and polarized light optical microscopy. In this work, we have studied in detail both compatibilized as well as noncompatibilized blends of PP and PEI. The compatibilization was achieved via addition of maleic anhydride grafted PP. Finally, all the compatibilized as well as noncompatibilized blends were studied for CO₂ adsorption. The compatibilized blends showed better thermal, mechanical as well as CO₂ adsorption properties as compared to the noncompatibilized blends. POLYM. ENG. SCI., 59:2092–2102, 2019. © 2019 Society of Plastics Engineers     

R-reliable intervals and confidences for the lifetime of a parallel system

In this discussion, R-reliable intervals for the life-time of a parallel system, based on order statistics, are obtained. The failure distributions for the individual components are assumed to have densities of the form 1/θ_Xif(x_iθ_Xi) where X_i, for i = 1, 2, …, n, are the failure times for the components in the parallel system and θ_Xis are the scale parameters for the failure times X_i. A relationship between the confidence of the R-reliable interval for the total lifetime of the parallel system and the confidences of the R-reliable intervals for the lifetimes of the individual components is investigated. A bound for the confidence of the R-reliable interval for the total lifetime of the system is obtained. Examples for n=3 are presented.     

Dynamic Routing and Wavelength Assignment Using Cost Based Heuristics in WDM Optical Networks

Dynamic routing and wavelength assignment problem in optical networks is a two-step problem that is influenced by the choice of a successful optimal path selection and wavelength assignment. Proper selection techniques reduce the number of wavelengths required in the network and thereby improves traffic grooming. Heuristic algorithms and integer linear programming models help in selection of route and wavelength separately. Hence, the computation time is large which makes the system slow. A cost function is computed which uses independent parameters in the network for the selection of route and wavelength for a call. The heuristic reduces computation time by combining the search of route and wavelength to be assigned. In addition, the network performance is analyzed with and without alternate routing along with proposed heuristics. The selection of proper route and wavelength finding technique is very essential since it improves the grooming factor of the network thereby allowing more traffic support by the network. Our objective is to investigate and propose a cost based heuristics for dynamic traffic routing and wavelength Assignment in WDM optical networks. For this we plan to develop cost functions and heuristics to compute the route and wavelength assignment strategy. Here, our objective is to reduce the computation time for selection of route and wavelength assignment strategy by weighted cost function. The function has to include network parameters for its processing. Our work provides an overview about DRWA by applying cost based heuristics in WDM networks. This paper explains the proposed cost function and its applications in line with selection of independent parameters. The details of other functions like cost function formulation, hop-based route assignment, available wavelength based route assignment, mathematical analysis of proposed cost function are also explained. Results and discussions based on the findings are presented.

     

Improved Connection Establishment of Dynamic Traffic with Queue in WDM Optical Networks

Wireless Personal Communications - Proper route selection between source and destination $$(s-d)$$ connection leads to efficient resource utilization which leads to the availability of resources...     

A flexible bathtub hazard model for non-repairable systems with uncensored data

This research effort has developed a mathematical model for bathtub shaped hazards (failure rates) for operating systems with uncensored data. The model will be used to predict the reliability of systems with such hazards. Early in the life-time of a system, there may be a relatively large number of failures due to initial weaknesses or defects in materials and manufacturing processes. This period is called the “infant mortality” period. During the middle period of an operating system fewer failures occur and are caused when the environmental stresses exceed the design strength of the system. It is difficult to predict the environmental stress amplitudes or the system strengths as deterministic functions of time, thus the middle-life failures are often called “random failures.” As the system ages, it deterioates and more failures occur. This region of failure is called the “wearout” period. Graphing these failure rates simultaneously will result in a bathtub shaped curve. The model developed for this bathtub pattern of failure takes into account all three failure regions simultaneously. The model has been validated for accuracy by using Halley's mortality table and is used to predict the reliability with both least squares and maximum likelihood estimators.     

Contemporary Approaches to Paced Visual Inspection

An approach to the study of inspection task design has been investigated. Twenty female inspectors did a simulated paced visual inspection task for 90 minutes each. The experimental variables were display size, product pacing, and fault information as a measure of defect probability. They were tested in a 15 point design with 3 replications of the center point. The criterion of performance was the fraction of total products correctly identified as being defect free. From the experimental data quantitative estimates of performance increments or decrements associated with changes in inspection task variables were determined. The implications of observations and their importance in the design of an inspection task have been discussed.     

Synthesis and characterization of AA7050 - TiO2 reinforced aluminium matrix composite

Journal of Mechanical Science and Technology - The extensive applications of aluminium alloy in the automotive and aerospace industries promote the current research activity. The present research...     

Study on degradation reactions in polyethylene terephthalate containing 5‐sulpho isophthalyl moieties

Kinetics of thermal degradation occurring on polyester containing cationic dyeable comonomer units viz. 5‐sulphoisophthalate moieties are studied by measurement of changes in intrinsic viscosity and carboxyl values on the polymer after subjecting the polymer chips to temperatures in the range 275–285°C for different residence times ranging from 5 to 60 min and comparing with the homopolymer. The activation energy values for degradation are estimated from the kinetic data. Mechanical properties of the textured yarns produced from the partially oriented yarns (POY) spun under different residence times are measured. Yarn produced with higher residence time has poor mechanical properties. The SEM images of the POY show presence of particles at the surface of the yarn due to polymer degradation. The size of the particles as seen on the surface increase with increase of retention time. Addition of thermal stabilizer helps in controlling the thermal degradation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Dominating the maximum likelihood estimator in predicting reliability

The reliability of a series system with n independent components are estimated. The failure distributions of these components are assumed to be Weibull with parameters α_i's and β_i's. It is assumed that the shape parameters β_i's are known. This reduces the reliability of the system to be a function of α = (α₁, ..., α_n), ξ(α), say. The MLE of ξ(α) is derived and an estimator which dominates the MLE in terms of risk, under squared error loss, is also derived. The predicted reliability using these two estimators are computed and compared.     

Properties of a multivariate survival distribution generated by aWeibull and inverse-Gaussian mixture

The authors consider the influence of the work environment on a system of nonrenewable components. The failure times for the components are Weibull distributed and the work environment has an inverse Gaussian distribution. A multivariate Weibull and inverse Gaussian mixture distribution is derived. Several pertinent properties for this multivariate distribution are discussed that shed some light on the nature of the distribution. The authors account for the operating environment and its changing nature by averaging over a parameter corresponding to the environment. The distribution is applied to find the mean number of components working at some mission time and the reliability for k-out-of-n components