Coherency identification and equivalents for transient stability studies

This paper presents techniques for identifying coherent generators without conducting a transient stability study and for developing stability equivalents of a group of coherent generators. Identification is based on the property of equal acceleration for coherent machines and it requires only examination of the elements of the Jacobian matrix of the linearized power system model. After the coherent groups have been identified, the stability equivalents are developed on the basis of the power invariance condition at the tie buses and at the internal buses of the coherent generators. These stability equivalents are used in a transient stability study. The techniques are illustrated with a 12-machine system.These techniques greatly improve the efficiency of calculation of coherency based equivalents. They have potential applications in planning studies of large power systems.     

Experimental study and analysis of lubricants dispersed with nano Cu and TiO<Subscript>2</Subscript> in a four-stroke two wheeler

The present investigation summarizes detailed experimental studies with standard lubricants of commercial quality known as Racer-4 of Hindustan Petroleum Corporation (India) dispersed with different mass concentrations of nanoparticles of Cu and TiO₂. The test bench is fabricated with a four-stroke Hero-Honda motorbike hydraulically loaded at the rear wheel with proper instrumentation to record the fuel consumption, the load on the rear wheel, and the linear velocity. The whole range of data obtained on a stationery bike is subjected to regression analysis to arrive at various relationships between fuel consumption as a function of brake power, linear velocity, and percentage mass concentration of nanoparticles in the lubricant. The empirical relation correlates with the observed data with reasonable accuracy. Further, extension of the analysis by developing a mathematical model has revealed a definite improvement in brake thermal efficiency which ultimately affects the fuel economy by diminishing frictional power in the system with the introduction of nanoparticles into the lubricant. The performance of the engine seems to be better with nano Cu-Racer-4 combination than the one with nano TiO₂.     

Emission analysis of Botryococcus braunii algal biofuel using Ni-Doped ZnO nano additives for IC engines

Microalgae biodiesel has been considered ?as a clean renewable fuel for diesel marine engines. This is due to its optimistic characterizations such as ?rapid growth rate, high productivity, and its ability to convert CO₂ into fuel. In this study, the use of microalgae biodiesel, obtained from Botryococcus braunii, as an alternative fuel for diesel marine engines has been investigated. The diesel engine is verified experimentally using Ni-Doped ZnO nano additive blends with algae biodiesel and neat diesel fuel. The results showed that doped nano additive blends? produce less emission compared to B20.     

Novel directional patterns and a Generalized Supervised Dimension Reduction System (GSDRS) for facial emotion recognition

This paper presents two novel directional patterns, a Maximum Response-based Directional Texture Pattern (MRDTP) and a Maximum Response-based Directional Number Pattern (MRDNP), for recognizing the facial emotions in constrained as well as unconstrained situations. The intensity information obtained from the maximum of the edge responses, after applying eight Kirsch masks, is used for the calculation of facial features in MRDTP. In MRDNP, instead of intensity information, the direction number of the maximum response is used. After dividing MRDNP and MRDTP code images into grids, feature vectors are created from the concatenated histograms obtained from the grids. This paper also proposes an effective Generalized Supervised Dimension Reduction System (GSDRS) and uses Extreme Learning Machine with Radial Basis Function (ELM-RBF) classifier for rapid and efficient classification of emotions. Both the proposed patterns are more effective than the existing ones in removing random noise and providing good structural information using prominent edges which help to achieve high classification accuracy when tested with seven datasets.     

Hybrid graph-based networks for multiprocessing

This article summarizes various ways of constructing large interconnection networks by performing different graph operations on smaller networks. The resultant hybrid graphs are classified, their inherent static topological properties are outlined and their relative advantages for multiprocessing applications are illustrated with several well-known networks. One class of hybrid graphs defined as compound networks, popularly known by an alternative name as hierarchical networks, is observed to be suitable for multicomputers in the current VLSI/WSI environment, as their use reduces network complexity, enhances scalability, reliability and fault-tolerance and supports locality of reference. This revised version was published online in June 2006 with corrections to the Cover Date.     

Optimal transmission power with delay constraints in 2D and 3D MANETs

Given the mobile node (MN) density and transmission power, this paper estimates the per-hop advancement toward destination with a single transmission, assuming that MNs are uniformly distributed. Based on this esteem, we calculate required hop count between two given MNs. In homogeneous mobile ad hoc networks (MANETs) where all MNs utilize the same transmission power, the hop count between any two MNs is proportional to the distance between them. Given the distance between each pair of MNs, this paper suggests the optimal transmission range (OTR) of MNs, which is the minimum possible power to guarantee end-to-end delay constraints of requested connections in the entire network. Packet collision is also considered in computing the OTR. All problems are investigated in both a two-dimensional (2D) and a three-dimensional (3D) area. Simulation results substantiate the accuracy of proposed estimation methods. The errors of the per-hop advancement estimation are just 0.88% and 2.33% in a 2D and 3D areas.     

Cycloaddition of carbon dioxide to epichlorohydrin using ionic liquid as a catalyst

The cycloaddition of carbon dioxide to epichlorohydrin was performed without any solvent in the presence of ionic liquid as catalyst. 1-Alkyl-3-methyl imidazolium salts of different alkyl group (C₂, C₄, C₆, C₈) and anions (Cl⁻, BF₄⁻, Br⁻, PF₆⁻) were used for this reaction carried out in a batch autoclave reactor. The conversion of epichlorohydrin was affected by the structure of the imidazolium salt ionic liquid; the one with the cation of longer alkyl chain length and with more nucleophilic anion showed better reactivity. The conversion of epichlorohydrin increased as the temperature increased from 60°C to 140°C. It also increased with increasing carbon dioxide pressure probably due to the increase of the absorption of carbon dioxide into the mixture of epichlorohydrin and the ionic liquid. Zinc bromide was also tested for its use as a cocatalyst in this reaction. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

Load-balanced mesh router migration for wireless mesh networks

Load-balancing among domains in a wireless mesh network (WMN) is normally achieved by changing the Internet attachment of mesh routers (MRs) that carry the traffic from mobile stations (MSs). The greediness of load-balancing algorithms may force MRs to frequently change their Internet attachments, and thus degrade network performance due to inter-domain mobility of the associated MSs. In this paper, we discuss the negative impact on the performance of MSs’ mobility, due to inter-domain reassignment of MR. A MR migration scheme is proposed to achieve a tradeoff between load-balancing and inter-domain reassignment of MR. The proposed load-balancing scheme for WMNs includes: an initialization procedure to divide a WMN into domains, and a load adjustment procedure to rebalance the traffic load among the neighboring domains when required. We also provide a framework for handling inter-domain mobility in support of multi-hop communication using the Multi-hop cellular IP. Our simulation results show that the proposed protocol effectively controls MR’s change in connectivity as well as MS’s mobility.