RFID Based Non-Preemptive Random Sleep Scheduling in WSN

In Wireless Sensor Network (WSN), because battery and energy supply are constraints, sleep scheduling is always needed to save energy while maintaining connectivity for packet delivery. Traditional schemes have to ensure high duty cycling to ensure enough percentage of active nodes and then derogate the energy efficiency. This paper proposes an RFID based non-preemptive random sleep scheduling scheme with stable low duty cycle. It employs delay tolerant network routing protocol to tackle the frequent disconnections. A low-power RFID based non-preemptive wakeup signal is used to confirm the availability of next-hop before sending packet. It eliminates energy consumption of repeated retransmission of the delayed packets. Moreover, the received wakeup signal is postponed to take effect until the sleep period is finished, and the waken node then responds to the sending node to start the packet delivery. The scheme can keep stable duty cycle and then ensure energy saving effect compared with other sleeping scheduling methods.     

Matrix pencil method for simultaneously estimating azimuth and elevation angles of arrival along with the frequency of the incoming signals

In this paper we describe a method for simultaneously estimating the direction of arrival (DOA) of the signal along with its unknown frequency. In a typical DOA estimation problem it is often assumed that all the signals are arriving at the antenna array at the same frequency which is assumed to be known. The antenna elements in the array are then placed half wavelength apart at the frequency of operation. However, in practice seldom all the signals arrive at the antenna array at a single pre-specified frequency, but at different frequencies. The question then is what to do when there are signals at multiple frequencies, which are unknown. This paper presents an extension of the matrix pencil method to simultaneously estimate the DOA along with the operating frequency of each of the signals. This novel approach involves approximating the voltages that are induced in a three-dimensional antenna array, by a sum of complex exponentials by jointly estimating the direction of arrival (both azimuth and elevation angles) along with the carrier frequencies of multiple far-field sources impinging on the array by using the three-dimensional matrix pencil method. The matrix pencil method is a direct data domain method for approximating a function by a sum of complex exponentials in the presence of noise. The variances of the estimates computed by the matrix pencil method are quite close to the Cramer–Rao bound. Finally, we illustrate how to carry out the broadband DOA estimation procedure using realistic antenna elements located in a conformal array. Some numerical examples are presented to illustrate the applicability of this methodology in the presence of noise. It is shown that the variance decreases as the SNR increases. The Cramer–Rao bound for the estimators are also provided to illustrate the accuracy and the computational efficiency of this new methodology.     

Navier-Stokes Solution by New Compact Scheme for Incompressible Flows

A new high spectral accuracy compact difference scheme is proposed here. This has been obtained by constrained optimization of error in spectral space for discretizing first derivative for problems with non-periodic boundary condition. This produces a scheme with the highest spectral accuracy among all known compact schemes, although this is formally only second-order accurate. Solution of Navier-Stokes equation for incompressible flows are reported here using this scheme to solve two fluid flow instability problems that are difficult to solve using explicit schemes. The first problem investigates the effect of wind-shear past bluff-body and the second problem involves predicting a vortex-induced instability.     

Topical Liposomal local Anesthetics: Design, Optimization and Evaluation of Formulations

To improve the rate of penetration into the skin, and to develop an effective topical anesthetic product, selected local anesthetic agents, benzocaine, lidocaine, dibucaine, etidocaine and tetracaine were encapsulated into liposomes using the solvent evaporation method. After the pilot experiments, tetracaine was selected for further development. Encapsulation efficiency was determined by centrifugation of liposomes and spectrophotometric analysis of liposome pellets and supernatants. Physical stability and organoleptic properties of the various liposomal tetracaine formulas were monitored visually and by microscopy for 1 year. Tetracaine was found to be suitable for the development of a liposomal drug delivery system with high encapsulation efficiency (60-90%) and physical stability. The results showed that encapsulation efficiency of tetracaine into liposomes can be increased by increasing drug concentration and pH, and including negatively charged stearic acid or unsaturated lipids in the formula. Stability of tetracaine increased with higher encapsulation efficiency, however the shelf life of the product was still short (2 months). In-process and finished product quality control parameters are suggested to facilitate the topical liposomal product development in general.     

Using incremental Web log mining to create adaptive web servers

Personalization of content returned from a Web site is an important problem in general and affects e-commerce and e-services in particular. Targeting appropriate information or products to the end user can significantly change (for the better) the user experience on a Web site. One possible approach to Web personalization is to mine typical user profiles from the vast amount of historical data stored in access logs. We present a system that mines the logs to obtain profiles and uses them to automatically generate a Web page containing URLs the user might be interested in. Profiles generated are only based on the prior traversal patterns of the user on the Web site and do not involve providing any declarative information or require the user to log in. Profiles are dynamic in nature. With time, a users traversal pattern changes. To reflect changes to the personalized page generated for the user, the profiles have to be regenerated, taking into account the existing profile. Instead of creating a new profile, we incrementally add and/or remove information from a user profile, aiming to save time as well as physical memory requirements.     

Knowledge based scheduling systems: a framework

Scheduling is a complex problem which occurs often in a manufacturing environment. There are many possible variations within the context of a scheduling problem, enough to overwhelm anyone but an expert. A production manager, faced with the task of job scheduling for a particular process, might well benefit from the advice of a scheduling expert. Even though the scheduling literature is full of optimizing rules for a variety of manufacturing environments few, if any, of these rules have been used in practice. The bewildering variety of theoretical results, the lack of a mechanism to match theoretical results to practical problems and the difficulty in establishing the practical efficacy of the theoretical results are among the reasons for this gap between scheduling theory and practice. This paper describes a scheduling expert system framework which addresses these problems and helps bridge this gap. The solution techniques available in SCHEDEX produce a specific schedule for the problem according to a procedure which has been mathematically proven to provide a satisfactory and often optimal solution, given the criteria for the problem. A simulation model also tests for the effectiveness of a selected technique with respect to the chosen performance measure(s).     

Detection of Branch Points by Modified FFT

This paper illustrates the existence of branch points in transients on lossy transmission lines and presents a technique of detecting branch points. By applying modified FFT to the transient signal and from the resulting amplitude and phase spectra, it is possible to detect and distinguish banch points from poles. Numerous examples are given to demonstrate the effectiveness of the modified FFT and the use of windowing in improving the detectability of a small branch point under the influence of a nearby strong pole.     

Enhancement of Poles in Spectral Analysis

This paper presents a new technique for detecting a small pole in the presence of a nearby strong pole. By simultaneously applying the chirp z-transform (CZT) and a recently developed window, the new technique is shown to be able to detect and resolve a small pole. The CZT is efficient since it employs the fast Fourier transform (FFT) to evaluate a convolution. But unlike the FFT which is limited to the evaluation of the spectrum on the jw-axis, the CZT can evaluate the z-transform on the whole complex plane. And with the use of the new window, which is designed to have a near-sidelobe level of any specified value, the CZT is shown to be able to resolve two closely spaced poles with a large difference in amplitudes. Unlike the Prony's method, the new technique does not require predetermining the system order. No matrix inversion or solution of polynomial roots is required. Further, the new technique is a linear operation. Thus even under noisy environments it yields accurate, stable results for extraction of poles from transient response data.     

Abrasion characteristics of coals

The silica content and ash level of the various fractions of an abrasive coal from the Talcher coalfield, Orissa state, India, are reported. Free silica, to which the abrasion of the coal is attributed, appears to be relatively evenly distributed among the size fractions, occurring at levels of 9.02–10.55 wt%.