Discrete-time integral terminal sliding mode-based speed tracking control for a robotic fish

Nonlinear Dynamics - This paper proposed a discrete-time integral terminal sliding mode (DITSM)-based forward speed tracking control for a robotic fish (RF). Due to the difficulty of quantification...     

Initiating electropolymerization on graphene sheets in graphite oxide structure

Because of its special chemical composition, graphite oxide has peculiar influences on electrochemical processes. The existence of various functional groups significantly affects electropolymerization processes and the formation of conductive polymers. Electrochemical synthesis of polyaniline (as a prototype of conductive polymers) on a paste‐based substrate of graphite oxide was investigated. In this case, the electropolymerization is significantly different from conventional cases, and the polymer is generated just during the first potential cycle. This can be attributed to the fact that graphite oxide can assist the monomer oxidation. Alternatively, electropolymerization was successfully performed inside the graphite oxide layers via electrochemical treatment of aniline‐intercalated graphite oxide in the supporting electrolyte. Although these phenomena are related to the chemical composition of graphite oxide, the graphite prepared by the reduction of graphite oxide also displayed some advantages for the electropolymerization (over natural graphite). There is an emphasis on the morphological investigations throughout this study, because novel morphologies were observed in the system under investigation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2204–2213, 2010     

The effect of particle size on the characteristics of FeCo nanoparticles

Some size-dependent characteristics of FeCo nanoparticles are investigated in this paper. The nanoparticles are fabricated using a coprecipitation route and their sizes are controlled by changing the reaction time. Transverse electron microscopy (TEM) images show that the nanoparticles are all spherical with an average size of 2–6 nm. The average size obtained from X-ray diffraction (XRD) measurements is in the range 1–3 nm. Magnetic measurements reveal that the nanoparticles are ordered ferromagnetically and have a high coercivity of about 500 Oe. In our measurements, the coercivity was decreased with decreasing particle size, indicating that the nanoparticles were in a single-domain region. Production of FeCo nanoparticles with high coercivity and fine dimension is highly promising for future recording media technology.     

A scoring mechanism for the rank aggregation of network robustness

To date, a number of metrics have been proposed to quantify inherent robustness of network topology against failures. However, each single metric usually only offers a limited view of network vulnerability to different types of random failures and targeted attacks. When applied to certain network configurations, different metrics rank network topology robustness in different orders which is rather inconsistent, and no single metric fully characterizes network robustness against different modes of failure. To overcome such inconsistency, this work proposes a multi-metric approach as the basis of evaluating aggregate ranking of network topology robustness. This is based on simultaneous utilization of a minimal set of distinct robustness metrics that are standardized so to give way to a direct comparison of vulnerability across networks with different sizes and configurations, hence leading to an initial scoring of inherent topology robustness. Subsequently, based on the inputs of initial scoring a rank aggregation method is employed to allocate an overall ranking of robustness to each network topology. A discussion is presented in support of the presented multi-metric approach and its applications to more realistically assess and rank network topology robustness.     

A method for solving a fuzzy linear programming

In this paper a fuzzy linear programming problem is presented. Then using the concept of comparison of fuzzy numbers, by the aid of the Mellin transform, we introduce a method for solving this problem.     

2,6-Dicarboxypyridinium Chlorochromate. An Efficient and Selective Reagent for the Mild Deprotection of Acetals, Thioacetals, and 1,1-Diacetates to Carbonyl Compounds

Summary. 2,6-Dicarboxypyridinium chlorochromate (2,6-DCPCC) was found to be an efficient reagent for the conversion of acetals, thioacetals, and 1,1-diacetates to their corresponding carbonyl compounds under neutral and anhydrous conditions in good to excellent yields. Selective deprotection of acetals or 1,1-diacetates in the presence of thioacetals at room temperature is also observed with this reagent.     

Geometry of ‘standoffs’ in lattice models of the spatial Prisoner’s Dilemma and Snowdrift games

The Prisoner’s Dilemma and Snowdrift games are the main theoretical constructs used to study the evolutionary dynamics of cooperation. In large, well-mixed populations, mean-field models predict a stable equilibrium abundance of all defectors in the Prisoner’s Dilemma and a stable mixed-equilibrium of cooperators and defectors in the Snowdrift game. In the spatial extensions of these games, which can greatly modify the fates of populations (including allowing cooperators to persist in the Prisoner’s Dilemma, for example), lattice models are typically used to represent space, individuals play only with their nearest neighbours, and strategy replacement is a function of the differences in payoffs between neighbours. Interestingly, certain values of the cost–benefit ratio of cooperation, coupled with particular spatial configurations of cooperators and defectors, can lead to ‘global standoffs’, a situation in which all cooperator–defector neighbours have identical payoffs, leading to the development of static spatial patterns. We start by investigating the conditions that can lead to ‘local standoffs’ (i.e., in which isolated pairs of neighbouring cooperators and defectors cannot overtake one another), and then use exhaustive searches of small square lattices (4×4$4\times 4$ and 6×6$6\times 6$) of degree k=3,k=4$k=3,k=4$, and k=6$k=6$, to show that two main types of global standoff patterns–‘periodic’ and ‘aperiodic’–are possible by tiling local standoffs across entire spatially structured populations. Of these two types, we argue that only aperiodic global standoffs are likely to be potentially attracting, i.e., capable of emerging spontaneously from non-standoff conditions. Finally, we use stochastic simulation models with comparatively large lattices (100×100$100\times 100$) to show that global standoffs in the Prisoner’s Dilemma and Snowdrift games do indeed only (but not always) emerge under the conditions predicted by the small-lattice analysis.     

A magnetically recoverable copper–salen complex as a nano-catalytic system for amine protection via acetylation using thioacetic acid

Research on Chemical Intermediates - A novel copper(II)–salen complex was immobilized on the surface of magnetite nanoparticles using chitosan as a linker. This system exhibits superior...     

Selecting most efficient information system projects in presence of user subjective opinions: a DEA approach

Information System (IS) project selection is a critical decision making task that can significantly impact operational excellence and competitive advantage of modern enterprises and also can involve them in a long-term commitment. This decision making is complicated due to availability of numerous IS projects, their increasing complexities, importance of timely decisions in a dynamic environment, as well as existence of multiple qualitative and quantitative criteria. This paper proposes a Data Envelopment Analysis approach to find most efficient IS projects while considering subjective opinions and intuitive senses of decision makers. The proposed approach is validated by a real world case study involving 41 IS projects at a large financial institution as well as 18 artificial projects which are defined by the decision makers.     

New exact solutions of some nonlinear evolution equations of pseudoparabolic type

This paper aims to conduct an analytical study into some nonlinear models of pseudoparabolic type, including the Oskolkov, Oskolkov–Benjamin–Bona–Mahony–Burgers, and Benjamin–Bona–Mahony–Peregrine–Burgers equations. A number of new exact solutions for these pseudoparabolic type equations have been derived based on the modified Kudryashov method that its calculations are performed in a symbolic computation system known as Maple.