On stochastic comparisons of finite mixtures for some semiparametric families of distributions

In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards.     

Sodium silicate as a coke inhibitor during naphtha pyrolysis

Rates of coke formation during steam pyrolysis of naphtha have been investigated in a jet-stirred reactor both for sodium silicate coated and uncoated Inconel 600 surfaces in the temperature range of 1078–1108 K. Coke formation rates were significantly reduced on sodium silicate coated plates due to the passivation of the metal surface. However, the coking rates gradually increased with successive decokings of the coated surface.     

Impact of communication time delays on combined LFC and AVR of a multi-area hybrid system with IPFC-RFBs coordinated control strategy

In this paper, the impact of communication time delays (CTDs) on combined load frequency control (LFC) and automatic voltage regulation (AVR) of a multi-area system with hybrid generation units is addressed. Investigation reveals that CTDs have significant effect on system performance. A classical PID controller is employed as a secondary regulator and its parametric gains are optimized with a differential evolution - artificial electric field algorithm (DE-AEFA). The superior performance of the presented algorithm is established by comparing with various optimization algorithms reported in the literature. The investigation is further extended to integration of redox flow batteries (RFBs) and interline power flow controller (IPFC) with tie-lines. Analysis reveals that IPFC and RFBs coordinated control enhances system dynamic performance. Finally, the robustness of the proposed control methodology is validated by sensitivity analysis during wide variations of system parameters and load.     

Evaluation of Concurrent Flaw Populations in Silicon Carbide in Terms of a Modified Weibull Distribution Function

Concurrent surface- and edge-flaw populations are often observed in strength testing of ceramics The overall strength distribution in such ceramic samples has been analyzed in terms of a modified Weibull distribution function. The junction provides an upper and lower strength limit and is characterized by two shape and location parameters. To evaluate the parameters of the distribution function, the type of flaw that causes failure need not be identified. The applicability of the function has been evaluated in terms of experimental results on SiC specimens. The analysis also shows that the relative values of shape parameters determine which flaw type dominates.     

An Architectural Framework for Accurate Characterization of Network Traffic

In networks carrying large volume of traffic, accurate traffic characterization is necessary for understanding the dynamics and patterns of network resource usage. Previous approaches to flow characterization are based on random sampling of the packets (e.g., Cisco's NetFlow) or inferring characteristics solely based on long lived flows (LLFs) or on lossy data structures (e.g., bloom filters, hash tables). However, none of these approaches takes into account the heavy-tailed nature of the Internet traffic and separates the estimation algorithm from the flow measurement architecture.In this paper, we propose an alternate approach to traffic characterization by closely linking the flow measurement architecture with the estimation algorithm. Our measurement framework stores complete information related to short lived flows (SLFs) while collecting partial information related to LLFs. For real-time separation of LLFs and SLFs, we propose a novel algorithm based on typical sequences from Information theory. The distribution (pdf) and sample space of the underlying traffic is estimated using the non-parametric Parzen window technique and likelihood function defined over the Coupon collector problem. We validate the accuracy and performance of our estimation technique using traffic traces from the internal LAN in our laboratory and from National Library for Applied Network Research (NLANR).     

Appearance Harmonization for Single Image Shadow Removal

Shadow removal is a challenging problem and previous approaches often produce de‐shadowed regions that are visually inconsistent with the rest of the image. We propose an automatic shadow region harmonization approach that makes the appearance of a de‐shadowed region (produced using any previous technique) compatible with the rest of the image. We use a shadow‐guided patch‐based image synthesis approach that reconstructs the shadow region using patches sampled from non‐shadowed regions. This result is then refined based on the reconstruction confidence to handle unique textures. Qualitative comparisons over a wide range of images, and a quantitative evaluation on a benchmark dataset show that our technique significantly improves upon the state‐of‐the‐art.     

Porous Titania Thin Films Grown by Anodic Oxidation for Hydrogen Sensors

Porous titanium dioxide (Titania) thin films were grown by anodic oxidation using high purity (99.7%) titanium foil in a dilute sulphuric acid (1 M) medium. The anodization process was carried out for 30 minutes with 20 mA/cm² and 50 mA/cm² current densities. The samples were characterized by XRD, SEM, and AFM techniques. It was found that the grown porous titania films were less sensitive to 500 ppm hydrogen in air ambient below 300°C; however, the sensitivity and response behavior of the film at 300°C are very much dependent on the growth conditions. Particularly, the films grown at current density 50 mA/cm² and 1 M acid concentration exhibited the lowest response time of 151 sec at 300°C.     

Dynamic Modeling and Simulation of Impact in Tether Net/Gripper systems

The objective of this paper is to study the dynamic modeling andsimulation of a tether-net/gripper system during an impact, while it isbeing deployed or retrieved by a winch on a satellite orbiting aroundearth. We stick to Tether-Net system but the analysis is applicable toTether-Gripper systems too. We assume that the net is deployed from thesatellite in orbit and the motion is restricted to the orbital plane.This net captures a second satellite and tows it. The motion of atether-net system can be broken down into the following phases: (i)Phase 1: Net is shot out from the satellite with the tether completelyslack, (ii) Phase 2: Net comes to a location where the tether is tautwhile the drum on the orbiter is locked, (iii) Phase 3: Drum is unlockedand the net moves with the tether, (iv) Phase 4: Net captures a body.The continua (tether) is modeled using mode functions and coordinates.The theory of impulse and momentum can be used to model Phases 1, 2, and4 of motion of the tether-net system. The dynamics of the motion of thesystem in phase 3 is characterized by differential and algebraicequations (DAEs). Matlab ODE solvers were used to solve these DAEs.     

QOS aware channel and power allocation scheme for D2D enabled cellular networks

Telecommunication Systems - Device-to-device (D2D) communication enabled cellular system is capable of enhancing the spectrum utilization and throughput performance of the system. However, D2D...