A networked mobile sensor test-bed for collaborative multi-target tracking applications

This paper presents the design, architecture, implementation, and experimental results from a networked mobile sensor test-bed developed for collaborative sensor tracking applications. The test-bed comprises a fleet of networked mobile sensors, an indoor localization system, a control, debugging and management infrastructure, and a tiered wireless ad hoc network for seamless integration of the above three components and the existing wireless infrastructure. First, the software and hardware architectural details of a swarm capable autonomous vehicle (SCAV) system for our collaborative applications are presented. Second, the details of an indoor self-localization and Kalman filter based navigation system design for the SCAV platform are presented. Third, as an example multi-sensor application, a collaborative multi-target tracking problem and a heuristics-based networked solution are formulated. Finally, the performance of the collaborative tracking framework is evaluated on the laboratory test-bed for characterizing the impacts of localization and navigation errors on the distributed tracking performance. The experimental study also characterizes the tradeoff between the tracking performance and the consumed wireless bandwidth. The experimental results demonstrate a number of counterintuitive results due to various errors in sensor localization and navigation.     

A multiple criteria buy versus lease analysis for governmentcontracts

In this paper, the authors describe their experiences with a real world case study that involved a buy versus lease decision for a government agency. The study was divided into two major parts: (1) the financial implications of buy versus lease; and (2) a multicriteria decision making (MCDM) model that explored the impact of both the tangible and intangible factors in a buy versus lease decision. The selected MCDM approach was the analytic hierarchy process (AHP). The study concluded that the lease option can be beneficial to both parties if the subjective criteria are considered     

Design and Implementation of Optical Signal Reinstatement Technique for High DPSK RZ Transceiver Scheme

Wireless Personal Communications - Optical signal reinstatement (OSR) is a common technique used in high-speed communication systems. OSR can be achieved using various techniques such as;...     

A data compression technique for scattered fields from complextargets

A data compression technique to efficiently compress the scattered fields from complex targets is presented. Since at high frequencies the scattered fields from complex radar targets exhibit a highly localized behavior, the data compression technique is based on extracting and then sampling the responses associated with individual scattering mechanisms. The compression technique preserves the angle as well as the frequency variation of individual scattering mechanisms and, thus, leads to small reconstruction error. The proposed technique, however, is a lossy process in the sense that a tradeoff exists between the compression ratio and the data reconstruction error. The smaller the data reconstruction error, the smaller the compression ratio. The effectiveness of the technique is demonstrated by compressing measured scattered fields of a complex target     

Constitutive and Aging Behavior of Sn3.0Ag0.5Cu Solder Alloy

We describe double-lap shear experiments on Sn3.0Ag0.5Cu solder alloy, from which fits to Anand's viscoplastic constitutive model, power-law creep model, and to time-hardening primary-secondary creep model are derived. Results of monotonic tests for strain rates ranging from 4.02E-6 to 2.40E-3 s^-1, and creep response at stress levels ranging from 19.5 to 45.6 MPa are reported. Both types of tests were conducted at temperatures of 25degC, 75degC , and 125degC. Following an earlier study where Anand model and time hardening creep parameters for Sn3.8Ag0.7Cu and Sn1.0Ag0.5Cu solder alloys were reported, here we report power law model parameters so as to enable a comparison between all three alloys. Primary creep in Sn3.0Ag0.5Cu solder alloy is shown to be significant and are considered in addition to secondary creep and monotonic behavior. Aging influence on behavior is also shown to be significant. On the basis of experimental data, the following four aspects are discussed: 1) difference between testing on bulk versus joint specimen; 2) consistency between the creep and monotonic behaviors; 3) comparison against behaviors of Sn1.0Ag0.5Cu and Sn3.8Ag0.7Cu alloys as well as aganist Sn40Pb, 62Sn36Pb2Ag and 96.5Sn3.5Ag alloys; and 4) comparison of Sn3.0Ag0.5Cu and Sn3.8Ag0.7Cu relative to their aging response.     

Scanning of sector and cosecant beams generated by a circular aperture

A method of scanning a one-dimensional shaped pattern generated by a circular aperture is presented. It is shown that the desired beam shape can be retained in the desired scan plane by superposing on the nonlinear phase distribution applied along and parallel to the meridian plane, a linear phase progression along the perpendicular direction. Analysis carried out using the stationary phase method of evaluating the integral reveals that the gradient of the linear phase progression is a function of position along the meridian plane of the aperture. Expressions for the phase functions are derived. Computed results on the phase distribution and the radiation pattern are presented.     

Effect of jammer power on the performance of adaptive arrays

The effect of jammer power on the performance of adaptive arrays is studied. It is shown that the output signal-to-interference-plus-noise ratio (SINR) of an adaptive array is a function of jammer power. In the presence of a wide-band jammer, the output SINR of the array decreases with an increase in jammer power and eventually goes to zero. Unlike continuous wave (CW) jammers, a wide-band jammer does not go through power inversion. Instead, as the jammer power is increased, the interference-to-noise ratio (INR) at the array output shows oscillations. For large jammer power, the output INR increases with an increase in jammer power.     

Stochastic analysis of a two-unit parallel system with partial and catastrophic failures and preventive maintenance

This paper studies a two-unit parallel system with each unit having two types of failure and two modes of operation—normal or partial failure mode. A unit fails either due to change in operating characteristics or due to catastrophe. The system goes for preventive maintenance randomly (in time). Failure rates are constant while repair and (preventive) maintenance rates are general. Using the theory of regenerative and Markov-renewal processes several important measures of reliability are obtained.     

Optimal allocation of cost to detectors in a two-unit series system

A two-unit series system, in which each unit is equipped with a separate detector to detect failure, is considered. The probability that a detector operates successfully at the time of need (i.e. when system fails) is a function of cost spent on the detector. The problem is that of allocation of total resources (cost) to the two detectors such that the overall expected profit is maximized. The optimization problem has been formulated. Two examples are included to show the uses of results.