Sensor Support Systems for Asymmetric Threat Countermeasures

In the past, primary focus has been given to novel sensor elements for deployment against urban terrorists and in limited force engagements. The issue explored in this paper is the adequacy of electronic system support for these new sensing elements. For example, ad hoc distributed networks must lie dormant for long periods of time and ldquocome aliverdquo when threats are nearby. This presents a unique challenge in the storage, generation, and management of power. In this paper, we demonstrate designs of processor algorithms and telecommunication protocols that alleviate current power-system shortcomings for these stationary networks. These advances include: 1) low-power protocols for data fusion and fault tolerance and 2) system-level energy modeling and analysis. As a concrete example, we define a distributed sensor support system for line crossing recognition. We demonstrate that threat detection is a system-level problem. Single elements of the system chain individually have small impact on overall performance. Through the development of a preamplifier/amplifier chain for optimum signal-to-noise (S/N) ratio, we show the degree to which system-level architecture can improve reliable detection. Specifically, the use of sensor redundancy to improve performance is analyzed from a statistical basis.     

Robust stability under structured and unstructured perturbations

The problem of robust stability for linear time-invariant single-output control systems subject to both structured (parametric) and unstructured (H_∞) perturbations is studied. A generalization of the small gain theorem which yields necessary and sufficient conditions for robust stability of a linear time-invariant dynamic system under perturbations of mixed type is presented. The solution involves calculating the H_∞ -norm of a finite number of extremal plants. The problem of calculating the exact structured and unstructured stability margins is then constructively solved. A feedback control system containing a linear time-invariant plant which is subject to both structured and unstructured perturbations is considered. The case where the system to be controlled is interval is treated, and a nonconservative, easily verifiable necessary and sufficient condition for robust stability is given. The solution is based on the extremal of a finite number of line segments in the plant parameter property of a finite number of line segments in the plant parameter space along which the points closest to instability are encountered     

High-speed target tracking by fuzzy hostility-induced segmentation of optical flow field

A time efficient technique for real-time tracking of high-speed objects in a video sequence is presented in this article. The technique is primarily based on the segmentation of the optical flow field computed between the successive image frames of a video sequence, followed by the tracking of a detected point of interest (POI) within the segmented flow field. In the initial phase of the technique, the optical flow field between the first two successive image frames acquired from a video sequence, is computed. A fuzzy hostility index indicative of the degree of coherence of the moving objects in the image frames, is used to segment the optical flow field. This yields different coherent regions of interest (ROIs) in the segmented flow field. A POI is then detected in the different ROIs obtained. Tracking of the moving object is then carried out by computing the flow fields between predefined ROIs in the neighborhood of the detected POI in the subsequent image frames.Since the selected ROIs are smaller than the image frames, a fair amount of reduction in the time required for the computation of the optical flow field is achieved, thereby facilitating real-time operation. An application of the proposed technique is demonstrated on three video sequences of high-speed flying fighter aircrafts.     

Sidewall oxidation of polycrystalline-silicon gate

Evidence is presented demonstrating that sidewall oxidation, a processing step needed for device reliability, can lead to gate oxide thickening in short-channel devices. This increase in thickness is the result of encroachment of bird's beaks from the edges of the gate structure into the channel region. The encroachment can be reduced by increasing oxidation temperature and/or using a dry ambient. With a judicious choice of polysilicon sidewall oxidation conditions, minimum gate-to-drain overlap capacitance and adequate device reliability can be achieved     

The simultaneous addition of styrene maleic anhydride copolymer and multiwall carbon nanotubes during melt‐mixing on the morphology of binary blends of polyamide6 and acrylonitrile butadiene styrene copolymer

The effect of simultaneous addition of multiwall carbon nanotubes (MWNTs) and a reactive compatibilizer (styrene maleic anhydride copolymer, SMA) during melt‐mixing on the phase morphology of 80/20 (wt/wt) PA6/ABS blend has been investigated. Morphological analysis through scanning and transmission electron microscopic analysis revealed finer morphology of the blends in presence of SMA + MWNTs. Fourier transform infrared spectroscopic analysis indicated the formation of imide bonds during melt‐mixing. Non‐isothermal crystallization studies exhibited the presence of a majority faction of MWNTs in the PA6 phase of 80/20 (wt/wt) PA6/ABS blend in presence of SMA + MWNTs. Rheological analysis, dynamic mechanical thermal analysis, and thermogravimetric analysis have demonstrated the compatibilization action of simultaneous addition of a reactive compatibilizer (SMA copolymer) and MWNTs in PA6/ABS blends. An attempt has been made to investigate the role of simultaneous addition of SMA copolymer and MWNTs on the morphology of 80/20 (wt/wt) PA6/ABS blend through various characterization techniques. POLYM. ENG. SCI., 55:457–465, 2015. © 2014 Society of Plastics Engineers     

Failure Investigation of Spline-Shaft of an Under Slung Crane

Investigation of the causes of premature failure of a spline-shaft used in the hoist gear box assembly of an under slung crane has been presented. The investigation consisted of visual inspection, chemical analysis, characterization of microstructures by optical and scanning electron microscopes, energy dispersive spectroscopy (EDS), and hardness measurement. Visual observation of the fracture surface of the shaft revealed multiple cracks all of which initiated at the sharp corners of the spline. Fractography of the shaft showed striations confirming fatigue. The chemical composition of the shaft was found to be close to EN-24 grade of hardened and tempered steel which is specified as per IS 5517. Microstructural examination showed branched-out cracks and few of them were associated with oxide layer or scale which was confirmed by EDS analysis. Since the shaft was not exposed to high temperature in service, formation of scale along the crack suggested that it was pre-existing in the component. Base matrix of the shaft revealed bainitic microstructure. Hardness values were found to be lower than that obtained for EN-24 grade in hardened and tempered condition. Analyses of the results suggest that the component suffered from fatigue under reversed torsional loading, which initiated at pre-existing cracks in the component.     

Improvements to the SMO algorithm for SVM regression

This paper points out an important source of inefficiency in Smola and Scholkopf's (1998) sequential minimal optimization (SMO) algorithm for support vector machine regression that is caused by the use of a single threshold value. Using clues from the Karush-Kuhn-Tucker conditions for the dual problem, two threshold parameters are employed to derive modifications of SMO for regression. These modified algorithms perform significantly faster than the original SMO on the datasets tried.     

Design of optimum actively compensated networks

This paper describes an active compensation technique which is readily applicable to all active-RC networks, independently of the circuit topology. This procedure considers the network in its totality and derives general active compensation conditions for a generic active-RC network employing 2 or 3 operational amplifiers. Furthermore, the remaining degrees of freedom of the circuits are used to optimize the performance of the actively compensated circuits to further extend its operating frequency range. Simulation and experimental results are also reported.     

A differential staining technique for vertebrate histology.

A staining method is described for studying micro-anatomy of different vertebrate tissues in the light microscope. A staining sequence of celestin blue--erythrosin--orange G--fast green with mordanting in phosphomolybdic acid yields a satisfactory differentiation and fine colour contrast in various tissues. The efficacy of the method was tested on different avian and mammalian tissues.