Geometry of the minimum zone flatness functional: planar and spatial case

The zone straightness and flatness functional is constructed from the definition of the measure. The geometry of the straightness functional is illustrated in the plane, and in three dimensions, a novel means to visually represent flatness is described using the zone separation body. The zone separation body is a new construction that is uniquely associated with every measurement dataset and can be used to represent the flatness functional visually.     

Evaluating the Vulnerability of Network Traffic Using Joint Security and Routing Analysis

Joint analysis of security and routing protocols in wireless networks reveals vulnerabilities of secure network traffic that remain undetected when security and routing protocols are analyzed independently. We formulate a class of continuous metrics to evaluate the vulnerability of network traffic as a function of security and routing protocols used in wireless networks. We develop two complementary vulnerability definitions using set theoretic and circuit theoretic interpretations of the security of network traffic, allowing a network analyst or an adversary to determine weaknesses in the secure network. We formalize node capture attacks using the vulnerability metric as a nonlinear integer programming minimization problem and propose the GNAVE algorithm, a Greedy Node capture Approximation using Vulnerability Evaluation. We discuss the availability of security parameters to the adversary and show that unknown parameters can be estimated using probabilistic analysis. We demonstrate vulnerability evaluation using the proposed metrics and node capture attacks using the GNAVE algorithm through detailed examples and simulation.     

Mueller-matrix Ellipsometry on Electroformed Rough Surfaces

Abstract

Automated Mueller-matrix ellipsometry was used to investigate the optical properties of electroformed standard rough surfaces as a function of r.m.s. surface roughness heights and angle of incidence. The r.m.s. roughness of the specimens examined varied from 50 to 12 500 nm. Six different surface finishes and 22 different specimens were examined and Mueller matrices were obtained at angles of incidence that varied from 30 to 80°. Measurements were conducted at a wavelength of 633 nm with the use of a division-of-amplitude photopolarimeter capable of simultaneously measuring all four Stokes parameters of arbitrarily polarized light. Values of ψ and Δ, the ellipsometric parameters, were derived from the measured Mueller matrices. The results demonstrate firstly the monotonic variations in the derived values of Δ with surface roughness for fixed angles of incidence, which include a ‘resonance’ effect for specimens with r.m.s. roughness heights close to the wavelength of light, secondly a systematic variation of ψ with the angle of incidence for different specimen roughness values and a reversal in these trends beyond the pseudo-Brewster angle, thirdly a monotonic variation in Δ values with the angle of incidence for different roughness values, fourthly relatively large variations in ψ values for roughness values close to the wavelength of light and fifthly relatively little change in ψ and Δ values for roughness values that greatly exceeded the wavelength of light.     

A competition-motivated capstone design course: the result of afifteen-year evolution

In this paper, a design course organization is presented, which is the result of 15 years of experience with a two-semester senior design course sequence in the Department of Electrical and Computer Engineering at the University of Detroit Mercy. An organization has been determined, which for the authors, balances team experience, individual assessment, design complexity, realism, writing content, and faculty workload. The current course structure is based on the integration of a capstone program with the Intelligent Ground Vehicle Competition (IGVC) sponsored by the Association For Unmanned Vehicle Systems International (AUVSI). The competition rules require that the students design and build an autonomous land vehicle which can navigate while sensing lane lines, avoiding obstacles, and traveling over ramps and sand traps. There are two main competition events: the vehicle performance competition where the autonomous robotic vehicles compete to finish the course in the shortest time or by traveling the farthest in the allotted time, and the vehicle design competition that evaluates the documentation, design process, and presentation of each team. The authors have found that this type of competition matches both the spirit and the practical needs of their capstone design course     

Design of a single-switch-per-phase converter for switchedreluctance motor drives

The main considerations in the design of a single-switch-per-phase converter for a switched reluctance motor (SRM) drive are described, with particular attention given to the choice of converter topology, the type of switching devices, the normalized rating of the power devices, and input filter design. The converter uses MOSFET switches. Experimental verification is included with a 6/4 pole personal-computer-controlled prototype SRM drive     

PHYSIOLOGICAL AND MORPHOLOGICAL CHANGES IN IMMOBILIZED L. PLANTARUM NCIM 2084 CELLS DURING REPEATED BATCH FERMENTATION FOR PRODUCTION OF LACTIC ACID

L. Plantarum NCIM 2084 cells are homofermentative, essentially producing lactic acid as the main end product of glucose fermentation. Prolonged use through repeated batch fermentation with the cells of L. plantarum immobilized on chitosan treated polypropylene matrix showed a shift in the metabolic pathway from the homofermentative to heterofermentative, accompanied by morphological changes in immobilized cells from the normal rod shape to the coccoid shape. These changes appear to be related to a shift in the bacterial cell metabolism, resulting in a decrease in lactic acid yields.     

Thermal stability and elevated temperature mechanical properties of electroslag remelted Fe-16wt.%Al-(0.14–0.5)wt.%C intermetallic alloys

Addition of carbon in the range of 0,14–0.5 wt.% to the Fe₃Al-based intermetallic Fe-16wt.%Al (Fe-28at.%Al) alloy results in the formation of a thermally stable dispersion of Fe,AIC carbide phase. The volume fraction of these precipitates increases with increase in carbon content. Processing of these alloys through a combination of air induction melting and electroslag remelting leads to enhanced elevated temperature mechanical properties compared to those reported for the low (< 0.01 wt.%) carbon alloys with similar Al contents. Enhancement of up to 30% in elevated temperature yield strength was observed at the test temperatures (600, 700 and 800°C) used. The improvement in mechanical properties may be attributed to the presence of strengthening Fe₃AlC phase as well as the interstitial carbon present in the alloy matrix. The addition of carbon also leads to improved room temperature mechanical properties in contrast with other alloying additions (such as Mo, Ti and Si) used for enhancing elevated temperature properties of Fe₃Al-based intermetallic alloys. It is suggested that carbon may be an important alloying addition to these alloys.     

Edge passivation and related electrical stability in silicon powerdevices

Factors governing long-term stability of silicon power devices are discussed with particular reference to a major failure mechanism observed in a thyristor device. The device failure was due to electrical instability during an electrical and thermal stability storage test, wherein it was observed that the reverse blocking voltage deteriorated under applied bias at the rated maximum junction temperature. The major cause of this failure was identified as lack of exhaust during the edge passivation and curing process due to which excessive chemical deposits are retained in the bevel region of the silicon element. This contributes to surface leakage current and, hence, a rapid degradation of the off-state characteristics. An orthogonal array experiment was employed to optimize the process factors and levels. The manufacturing process was then modified by incorporating an effective exhaust system in the passivant curing oven. This resulted in marked improvements in the electrical stability and manufacturing yield of this device     

Silver nanorods induced oxidative stress and chromosomal aberrations in the Allium cepa model

The production of different size and shape silver nanoparticles (AgNPs) has increased considerably in recent years due to several commercial and biological applications. Here, rod‐shaped AgNPs (SNRs) were prepared using the microwave‐assisted method and characterised by ultraviolet–visible spectroscopy, and transmission electron microscopy analysis. The present study aims to investigate the cyto–genotoxic effect of various concentrations (5, 10, and 15 µM) of SNRs using Allium cepa model. As a result, concentration‐dependent cyto–genotoxic effect of SNRs was observed through a decrease in the mitotic index, and an increase in the chromosomal aberrations such as chromosome break, disturbed metaphase, and anaphase bridge. To check the impact of Ag⁺ ions, 15 µM silver nitrate (AgNO₃) was prepared and tested in all the assays. Furthermore, cell viability and different reactive oxygen species assays were performed to test the cytotoxicity evaluation of SNRs. The authors found that in all the tested assays, SNRs at high concentrations (15 µM) and AgNO₃ (15 µM) were observed to cause maximal damage to the roots. Therefore, the current study implies that the cytotoxicity and genotoxicity of SNRs were dependent on the concentration of SNRs.Inspec keywords: ultraviolet spectra, biomedical materials, silver, cellular biophysics, nanorods, toxicology, visible spectra, nanoparticles, nanofabrication, transmission electron microscopy, nanomedicine, aberrations, microwave materials processingOther keywords: biological applications, rod‐shaped AgNPs, microwave‐assisted method, ultraviolet‐visible spectroscopy, transmission electron microscopy, chromosomal aberrations, chromosome break, silver nitrate, reactive oxygen species assays, cytotoxicity, genotoxicity, silver nanorods, oxidative stress, shape silver nanoparticles, concentration‐dependent cyto‐genotoxic effect, Allium cepa model, mitotic index, disturbed metaphase, anaphase bridge, cell viability, cytotoxicity evaluation, Ag