Interacting with team oriented plans in multi-robot systems

Team oriented plans have become a popular tool for operators to control teams of autonomous robots to pursue complex objectives in complex environments. Such plans allow an operator to specify high level directives and allow the team to autonomously determine how to implement such directives. However, the operators will often want to interrupt the activities of individual team members to deal with particular situations, such as a danger to a robot that the robot team cannot perceive. Previously, after such interrupts, the operator would usually need to restart the team plan to ensure its success. In this paper, we present an approach to encoding how interrupts can be smoothly handled within a team plan. Building on a team plan formalism that uses Colored Petri Nets, we describe a mechanism that allows a range of interrupts to be handled smoothly, allowing the team to efficiently continue with its task after the operator intervention. We validate the approach with an application of robotic watercraft and show improved overall efficiency. In particular, we consider a situation where several platforms should travel through a set of pre-specified locations, and we identify three specific cases that require the operator to interrupt the plan execution: (i) a boat must be pulled out; (ii) all boats should stop the plan and move to a pre-specified assembly position; (iii) a set of boats must synchronize to traverse a dangerous area one after the other. Our experiments show that the use of our interrupt mechanism decreases the time to complete the plan (up to 48 % reduction) and decreases the operator load (up to 80 % reduction in number of user actions). Moreover, we performed experiments with real robotic platforms to validate the applicability of our mechanism in the actual deployment of robotic watercraft.     

Synthesis of a novel carbon nanofiber structure for removal of lead

A new structure of carbon nanofibers was synthesized by chemical vapor deposition method. Kaolin was used as substrate and cyclohexanol and ferrocene as carbon source and catalyst, respectively. The morphology of the product was studied by scanning electron microscopy. Carbon nanofiber was modified with a mixture of nitric acid and sulfuric acid to enhance its adsorption capacity. The presence of functional groups on the treated adsorbent was assessed by FT-IR spectroscopy. The surface activity of the oxidized sample was estimated by Boehm’s titration. The pH_(PZC) of the samples was also measured. The adsorbent was then used for adsorption of Pb²⁺ at different experimental conditions. The optimized capacity of 211mg·g^?1 was obtained. Kinetic and thermodynamic of the reaction were studied. It was concluded that the adsorption process is spontaneous and endothermic. Equilibrium data were well fitted to the Langmuir model and the pseudo-second-order kinetic model described the adsorption process.     

Platinum-palladium nanoparticles-loaded on N-doped graphene oxide/polypyrrole framework as a high performance electrode in ethanol oxidation reaction

Existing catalysts for ethanol oxidation in direct ethanol fuel cells (DEFC) are faced to significant challenges due to their poor performance and CO like intermediates poisoning tolerance at anode surface. Hence researchers are looking for new electrocatalysts in the ethanol oxidation. In this study, polypyrrole/N-doped graphene oxide (PPy/NGO) nanocomposite was prepared using in-situ polymerization method. Next the platinum-palladium (PtPd) was electrochemically decorated on PPy/NGO nanocomposite surface. In order to ensure the correct preparation of nanocomposite, fourier transform infrared spectroscopy (FT-IR) analysis was carried out to peruse the chemical structure of the nanocomposite and also to investigate their morphology, field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were used. The morphology of nanocomposite shows that PPy has penetrated into the space between NGO plates. Disparate electrochemical techniques like cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA) were employed to evaluate the oxidation of ethanol. Results showed that PtPd/PPy/NGO exhibits improved electrocatalytic activity and stability for ethanol oxidation. Enhanced active surface area of the PtPd/PPy/NGO electrode (35.1 m² g^?1) contributes to increase in current density and decrease in over potential values in the ethanol oxidation as compared to PtPd electrocatalyst.     

Liquid–Liquid Equilibria in Biodiesel Production

During biodiesel production, the product is contaminated with impurities such as some non-reacted alcohol, glycerol, and catalyst. In order to comply with product requirements, these impurities must be removed, for example, by washing with water. Knowledge of the extent of water solubility in biodiesel is required to design the drying system and determine fuel quality. In the present work, the solubilities of water in biodiesels produced from sunflower and canola oils were measured within the temperature range of 24–60 °C. The solubility of water increased with increasing temperature and biodiesel unsaturation. The liquid–liquid equilibria of ternary systems of glycerol, methanol, and the above-mentioned biodiesels were investigated experimentally at 20, 30, and 40 °C. The binodal curves were determined by using the cloud point titration method and the tie lines were measured by evaporating the methanol. Both binary and ternary data were modeled using the UNIQUAC model. The model showed good agreement with the data. Othmer-Tobias correlations were applied and the corresponding constants were obtained. The results validated the consistency of the tie-line data obtained experimentally.     

COMPARATIVE STUDIES OF SOME HETEROCYCLIC COMPOUNDS AS CORROSION INHIBITORS OF COPPER IN PHOSPHORIC ACID MEDIA

Corrosion inhibition properties of some heterocyclic compounds (3-mercapto 1,2,4 triazole, benzotriazole, thiophene, and tetra hydro-thiophene) in Cu/H₃PO₄ medium were investigated theoretically and experimentally via cluster/polarized continuum and gravimetric approaches. Second-order Møller-Plesset perturbation and density functional theories were applied, and the electronic chemical potential, molecular softness, and extent of charge transfer were determined for inhibitor molecules at the metal/solution interface. Good correlations were observed for both theories between the calculated quantities and experimental data. To reveal the quality of metal-inhibitor interactions, comprehensive analyses were carried out on various active centers of the compounds. It was concluded that the interactions are mostly physical, and the molecules with less electron-inducing effect act more efficiently.     

Reference node selection in dynamic tree

The reference node (RN) is a central node that has minimum distance/hop count to all other nodes in the network. This central node can play several critical roles such as being the time reference in order to synchronise computer nodes. For synchronisation, the main goal is to minimise the sum of synchronisation errors. The time synchronisation error, known for each link between two nodes, accumulates for each hop along the path used for synchronisation between two nodes. In such a context, the best RN is defined as having the minimal sum of time synchronisation errors between itself and every other node. Thus, the first step for error minimisation is to select a minimum spanning tree (MST), formed by the links with minimum synchronisation error, as synchronisation path. The second step is to select an RN, which minimises the sum of synchronisation errors to all nodes in the MST, as time reference for synchronisation. In a dynamic network, where communication links appear and disappear, and synchronisation accuracy improves as more packets are exchanged, a static RN would entail suboptimal synchronisation accuracy. All existing models in this area are limited to static RNs because of the computing cost of updating the RN, yielding a suboptimal total synchronisation error over time and causing problems if the selected node is removed from the dynamic network. This paper presents a novel and efficient method for dynamic RN selection in dynamic networks. The approach proposed in this paper improves the performance of RN computation and update in live mode for dynamic networks. This new method concentrates on the altered path with respect to the RN, each time the MST is updated. This provides an efficient way to find and maintain a RN incrementally in an average time complexity of O(log n) per update, which n is the total number of nodes in the network. The proposed approach was tested with a huge dynamic network containing 60 000 simulated nodes, in a number of different situations. The proposed approach achieves excellent running time while minimising synchronisation error. Although this work is currently used for time synchronisation purposes, several dynamic network tools can benefit from an efficient incremental algorithm to calculate hop counts and select a central point for the network. Copyright © 2014 John Wiley & Sons, Ltd     

Synthesis of 2,4,6,8,10,12‐Hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane Using Melaminium‐tris(hydrogensulfate) by a Simple One‐Pot Nitration Procedure

A highly efficient protocol for the synthesis of 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20) in the presence of melaminium‐tris(hydrogen sulfate) as a solid acid is described.     

Estimation of Formation Enthalpies of Organic Pollutants from a New Structural Group Contribution Method

Chemical stability and reactivity of organic pollutants is dependent to their formation enthalpies. The main objective of this study is to provide simple straightforward strategy for prediction of the formation enthalpies of wide range organic pollutants only from their structural functional groups. Using such an extended dataset comprising 1694 organic chemicals from 77 diverse material classes benefits the generalizability and reliability of the study. The new suggested collection of 12 functional groups and a simple linear regression lead to promising statistics of R²=0.958, Q_Loo²=0.956, and δ_AEE=57 kJ·mol^-1 for the whole dataset. Moreover, unknown experimental formation enthalpies for 27 organic pollutants are estimated by the presented approach. The resultant model needs no technical software/calculations, and thus can be easily applied by a non-specialist user.     

Stochastic Design of Flood Control Systems; Uncertainty Propagation and Results Representation

Water Resources Management - The design and operation of flood control systems are always subjected to different uncertainties. In general, uncertainty occurs due to the inherent randomness of...