The Effects of Surface Waviness and Length on Electrokinetic Transport in Wavy Capillary

An electrokinetic model for a wavy capillary has been developed. Poisson‐Nernst‐Planck and Navier‐Stokes equations constitute the model that governs fluid and ionic fluxes and electric potential distribution inside the capillary. In the present paper, a finite wavy cylindrical capillary with a large reservoir at both capillary ends is analyzed using finite element method. The model is used primarily to examine the influence of capillary surface waviness on the electrokinetic transport behaviours. Different frequencies and amplitudes of the wavy surface are considered to investigate the influence of surface waviness on electrokinetic transport. Fluctuations in potential and ionic concentration distribution increase with the increase in either amplitude or frequency of the capillary surface waviness. However, for higher frequencies the fluctuation diminishes for all surface waviness amplitudes. It is observed that for any irregularity in the capillary surface results in higher salt rejection. Salt rejection is found to be dependent on capillary axial length as well as flow velocity. A critical Peclet number, beyond which salt rejection attains a constant steady value, dictates maximum salt rejection.     

Analysis of Film Condensation Along a Vertical Flat Plate Under Sinusoidal G-Jitter

Transient phenomenon of laminar film condensation along a vertical flat plate under sinusoidal g-jitter has been analyzed, based on the same assumptions of Nusselt’s analysis of film condensation where the heat transfer within the liquid film is by pure conduction. The momentum equation retains the transient term. The perturbed acceleration due to gravity has been assumed to be a sinusoidal function of time and frequency of oscillation for the simplicity. The resultant equation has been solved analytically and the velocity profiles and mass flow rate under such g-jitter has been simulated. It has been observed that at the different heights the velocity response with time is purely sinusoidal with different amplitude. Last but not the least; boundary layer thickness is also oscillating with time, hence heat transfer coefficient. However, the entire analysis is an extension of Nusselt’s analysis of film condensation which includes transient response.     

Optimal placement and routing strategies for resilient two‐tiered sensor networks

In hierarchical sensor networks using relay nodes, sensor nodes are arranged in clusters and higher powered relay nodes can be used as cluster heads. The lifetime of such a network is determined primarily by the lifetime of the relay nodes. In this paper, we propose two new integer linear programs (ILPs) formulations for optimal data gathering, which maximize the lifetime of the upper tier relay node network. Unlike most previous approaches considered in the literature, our formulations can generate optimal solutions under the non‐flow‐splitting model. Experimental results demonstrate that our approach can significantly extend network lifetime, compared to traditional routing schemes, for the non‐flow‐splitting model. The lifetime can be further enhanced by periodic updates of the routing strategy based on the residual energy at each relay node. The proposed rescheduling scheme can be used to handle single or multiple relay node failures. We have also presented a very simple and straightforward algorithm for the placement of relay nodes. The placement algorithm guarantees that all the sensor nodes can communicate with at least one relay node and that the relay node network is at least 2‐connected. This means that failure of a single relay node will not disconnect the network, and data may be routed around the failed node. The worst case performance of the placement algorithm is bounded by a constant with respect to any optimum placement algorithm. Copyright © 2008 John Wiley & Sons, Ltd.     

A review of machining monitoring systems based on artificial intelligence process models

Many machining monitoring systems based on artificial intelligence (AI) process models have been successfully developed in the past for optimising, predicting or controlling machining processes. In general, these monitoring systems present important differences among them, and there are no clear guidelines for their implementation. In order to present a generic view of machining monitoring systems and facilitate their implementation, this paper reviews six key issues involved in the development of intelligent machining systems: (1) the different sensor systems applied to monitor machining processes, (2) the most effective signal processing techniques, (3) the most frequent sensory features applied in modelling machining processes, (4) the sensory feature selection and extraction methods for using relevant sensory information, (5) the design of experiments required to model a machining operation with the minimum amount of experimental data and (6) the main characteristics of several artificial intelligence techniques to facilitate their application/selection.     

Dynamical effects of missed switching in current-mode controlled DC-DC converters

Past investigations on nonlinear phenomena in DC-DC converters assume ideal switching and ignore the practical issue of switching ripples, for which the sampled data models yield piecewise smooth but continuous maps. In this brief, we show that the unavoidable nonidealities in the switching result in discontinuity in the map, which drastically changes the bifurcation structures. We demonstrate these effects experimentally, and develop simple one-dimensional models that account for switching delay and transients, and can predict the bifurcations in such systems with reasonable accuracy. Using the recent developments in bifurcation theory, we derive the limiting conditions for a reliable period-1 operation when these effects are considered.     

A new definition of shape similarity

Two reference points of a region are defined which do not depend on the position, size and orientation of the region. Reference points are used to get borders on the basis of which the shape distance and shape similarity are defined.     

A bio inspired and trust based approach for clustering in WSN

Wireless sensor network (WSN) is a special kind of ad-hoc network consists of battery powered low cost sensor nodes with limited computation and communication capabilities deployed densely in a target area. Clustering in WSN plays an important role because of its inherent energy saving capability and suitability for highly scalable network. This paper is an extended version of our previous work (Sahoo et al. 2013a). Although the clustering strategy presented in this paper is same as our previous work but here a light weight dynamic TRUST model along with honey bee mating algorithm is presented, which will only prevent malicious node to be a cluster head. The choice of light weight TRUST model makes our clustering method more secure and energy efficient, which are most pivotal issues for resource constrained sensor network. We have also introduced a priority scheme among the trust metrics which is more realistic. Furthermore, the use of honey bee mating algorithm finds most appropriate node as cluster head. Simulation results are also presented here to compare the performance of our algorithm with low energy adaptive clustering hierarchy and advertisement time-out driven bee mating approach to maintain fair energy level in sensor networks.     

Analytical Modeling of Triple-Metal Hetero-Dielectric DG SON TFET

In this paper, a 2-D analytical model of triple-metal hetero-dielectric DG TFET is presented by combining the concepts of triple material gate engineering and hetero-dielectric engineering. Three metals with different work functions are used as both front- and back gate electrodes to modulate the barrier at source/channel and channel/drain interface. In addition to this, front gate dielectric consists of high-K HfO₂ at source end and low-K SiO₂ at drain side, whereas back gate dielectric is replaced by air to further improve the ON current of the device. Surface potential and electric field of the proposed device are formulated solving 2-D Poisson’s equation and Young’s approximation. Based on this electric field expression, tunneling current is obtained by using Kane’s model. Several device parameters are varied to examine the behavior of the proposed device. The analytical model is validated with TCAD simulation results for proving the accuracy of our proposed model.     

Analytical models for a new turnover-based hybrid storage policy in unit-load warehouses

This paper considers a low-level unit-load warehouse employing single-deep storage lanes and a single-command manual storage and retrieval policy. Analytical travel distance models are developed for class-based and full turnover storage policies under across-aisle, within-aisle and a newly proposed hybrid product placement schemes. Our computational studies show that the analytical models developed in this paper are very accurate as compared to simulation results and a comparative study with a real-world warehouse case. Hybrid storage policies proposed in this paper outperform all other traditional storage policies. The paper also presents insights and simple design rules to warehouse practitioners.