Design of High Sensitive Temperature Sensor Based on Two-Dimensional Photonic Crystal

In this effort, a two-dimensional photonic crystal ring resonator (2DPCRR) is simulated. This device is developed for temperature detection in harsh enviro     

Mobility management support and performance analysis for wireless MPLS networks

Multi‐Protocol Label Switching (MPLS) is deployed in the Internet backbone to support service differentiation and traffic engineering. In recent years, there has been interest in extending the MPLS capability to wireless access networks for mobility management support. In this paper, we present analysis of Micro Mobile MPLS, a new micro‐mobility management scheme which integrates the Mobile IP and MPLS protocols by using two‐level hierarchy architecture. Our proposal supports two protocol variants. First, the fast handoff process, which anticipates the LSP procedure set‐up with neighboring locations where a mobile node (MN) may move to, is provided to reduce service disruption. Second, a new mechanism based on the forwarding chain concept is proposed to track efficiently the host mobility within a domain. This concept can significantly reduce registration update costs and provide low handoff latency. Analytical models are developed and simulations are conducted to justify the benefits of our proposed mechanisms. Copyright © 2006 John Wiley & Sons, Ltd.     

Cost optimal, parallel reliability systems with fixed repair sanction

Optimisation methods under varied criteria for different parameters in stochastic reliability systems are being increasingly developed and have been reported in recent literature. The large interest evinced in this fascinating area is primarily due to its applicational value and operational role in the decision making process. Recently a parallel system has been considered and the optimal number of units discussed, as well as optimal replacement times for the system based on acquisition and replacement costs.In this paper we consider an improved version of the model formulation, by bringing in additionally the maintenance and per unit repair time costs, and develop a procedure to obtain the optimal number of components in the system with the condition that the system is allowed to undergo a prefixed maximum number of repairs, after which the system is to be replaced.The applicational use of the results is illustrated through numerical work, specialising to some known laws governing the system parameters and corresponding to different fixed number of repair sanctions.     

Selectivity of partial hydrogenation reactions performed in a pore-through-flow catalytic membrane reactor

The selectivity of partial hydrogenation reactions of unsaturated substrates was studied in a membrane reactor operating at 323 K and 40 bar hydrogen pressure. The reactor system was constructed as a loop of a saturation vessel and a membrane module in which the reaction mixture was resaturated with hydrogen up to 100 times. In a porous membrane made from cross-linked polyacrylic acid palladium nanoparticles were incorporated as catalysts. A well-defined residence time within the membrane was achieved due to a defined pore structure of the membrane and a convective mass flow of the reaction mixture through the membrane. The selectivity for the partially hydrogenated products was investigated as a function of the pore size of the PAA membrane and was compared to commercially available catalysts. Compared to experiments with supported catalysts (Pd/C and Pd/Al₂O₃) in a slurry and a fixed bed reactor the selectivity for the desired products could be increased by 3% (1-octyne) up to 40% (geraniol).     

Towards a Dual-Tip STM Application in Mesoscopic Electron Transport

A new design for a dual-tip scanning tunneling microscope (STM) is presented. The design is a variation on the mechanically controllable break-junction with two electron beam-induced deposition nano-tips. The new design enables one to scan surfaces simultaneously with two probes having a nano-gap separation. By collecting the lateral current flowing between the tips, the transconductance map can then be compared with the STM images for local characterizations of the electron transport. Since the lateral beam carries the property of the density of states of the surface at momentum space, the dispersion of the electronic structure should give an orientation and position dependence of the local transconductance current. In addition, the reduced terminal separation, on the order of the characteristic mesoscopic length scales, is likely to be sensitive to a variety of typically observed interactions and interference effects.     

Hydrogels based on graft copolymers of collagen synthesis

Graft copolymerization of 2-hydroxyethyl methacrylate in combination with hydrophobic monomers onto soluble collagen was employed in the synthesis of hydrogels. The hydrogels were formed by simultaneous graft copolymerization and crosslinking. In order to study the effect of various crosslinking agents on the water retention character of the hydrogels, three different crosslinking agents, namely, N,N′-methylene bis acrylamide, 1,4-butanediol dimethacrylate, and hexamethylene urethanediacrylate were used. Hexamethylene urethanediacrylate crosslinked systems require a minimum amount of crosslinking agent to attain maximum water content in comparison to the other systems.     

UV-shielding by a polyurethane/f-Oil fly ash-CeO2 protective coating

A waste material called oil fly ash (OFA) was acid-functionalized, yielding f-OFA-COOH, which was then reacted with cerium oxide (CeO₂) to make CeO₂-functionalized OFA, or f-OFA-CeO₂. Pristine OFA and f-OFA-CeO₂ were used to make waterborne polyurethane (WBPU) dispersions, referred to as WBPU/OFA and WBPU/f-OFA-CeO₂, respectively, with defined OFA and f-OFA-CeO₂ content. All the dispersions were applied to mild steel as organic coatings to evaluate their protective properties, such as their hydrophobicity, adhesive strength and UV-shielding resistance. These protective properties varied based on the OFA and f-OFA-CeO₂ content. The highest water contact angle, minimum water swelling and maximum adhesive strength were found using WBPU/f-OFA-CeO₂-20 coating (using 2.00 wt% f-OFA-CeO₂), which also showed the maximum ultraviolet (UV) absorption via UV–vis spectroscopy analysis. This UV shielding result also matched field test results, as that coating was found to exhibit the lowest UV degradation near a marine atmosphere, as shown by X-ray photoelectron spectroscopy (XPS) analysis. The least affected hydrophobicity was also recorded for the sample with the WBPU/f-OFA-CeO₂-20 coating.     

A robust estimation approach for uncertain systems with perturbed measurements

This paper deals with state estimation problem for uncertain continuous‐time systems. A numerical treatment is proposed for designing interval observers that ensures guaranteed upper and lower bounds on the estimated states. In order to take into account possible perturbations on the system and its outputs, a new type of interval observers is introduced. Such interval observers consist of two coupled general Luenberger‐type observers that involve dilatation functions. In addition, we provide an optimality criterion in order to find optimal interval observers that lead to tight interval error estimation. The proposed existence and optimality conditions are expressed in terms of linear programming. Also, some illustrative examples are given. Copyright © 2015 John Wiley & Sons, Ltd.     

Preference-based content replacement using recency-latency tradeoff

This work introduces and establishes a new model for cache management, where clients suggest preferences regarding their expectations for the time they are willing to wait, and the level of obsolescence they are willing to tolerate. The cache uses these preferences to decide upon entrance and exit of objects to and from its storage, and select the best copy of requested object among all available copies (fresh, cached, remote). We introduce three replacement policies, each evicts objects based on ongoing scores, considering users’ preferences combined with other objects’ properties such as size, obsolescence rate and popularity. Each replacement algorithm follows a different strategy: (a) an optimal solution that use dynamic programming approach to find the best objects to be kept (b) another optimal solution that use branch and bound approach to find the worst objects to be thrown out (c) an algorithm that use heuristic approach to efficiently select the objects to be evicted. Using these replacement algorithms the cache is able to keep the objects that are best suited for users preferences and dump the other objects. We compare our proposed algorithms to the Least-Recently-Used algorithm, and provide evidence to the advantages of our algorithms providing better service to cache’s users with less burden on network resources and reduced workloads on origin servers.