Security concepts for the dynamics of autonomous vehicle networks

The secure operation of autonomous vehicle networks in the presence of adversarial observation is examined, in the context of a canonical double-integrator-network (DIN) model. Specifically, we study the ability of a sentient adversary to estimate the full network’s state, from noisy local measurements of vehicle motions. Algebraic, spectral, and graphical characterizations are provided, which indicate the critical role of the inter-vehicle communication topology and control scheme in achieving security.     

Evolution of Surface Morphology in Laser-Dressed Alumina Grinding Wheel Material

An approach to laser dressing of alumina grinding wheels is proposed based on solidification microstructures associated with rapid cooling rates obtained in laser surface processing. Laser dressing of alumina grinding wheels forms surface microstructures characterized by multifaceted grains that are expected to facilitate the micro-scale material removal during precision machining. A detailed investigation of variation of grain size and melt depth with laser fluence is conducted. The results are correlated with calculated cooling rates derived from a thermal model. In addition, based on microscopic observations, the formation of surface grains by stacking of individual multifaceted grains formed during laser dressing is suggested.     

A simulation framework for measuring robustness of incentive mechanisms and its implementation in reputation systems

In game theoretical analysis of incentive mechanisms, all players are assumed to be rational. Since it is likely that mechanism participants in the real world may not be fully rational, such mechanisms may not work as effectively as in the idealized settings for which they were designed. Therefore, it is important to evaluate the robustness of incentive mechanisms against various types of agents with bounded rational behaviors. Such evaluations would provide us with the information needed to choose mechanisms with desired properties in real environments. In this article, we first propose a general robustness measure, inspired by research in evolutionary game theory, as the maximal percentage of invaders taking non-equilibrium strategies such that the agents sustain the desired equilibrium strategy. We then propose a simulation framework based on evolutionary dynamics to empirically evaluate the equilibrium robustness. The proposed simulation framework is validated by comparing the simulated results with the analytical predictions based on a modified simplex analysis approach. Finally, we implement the proposed simulation framework for evaluating the robustness of incentive mechanisms in reputation systems for electronic marketplaces. The results from the implementation show that the evaluated mechanisms have high robustness against a certain non-equilibrium strategy, but is vulnerable to another strategy, indicating the need for designing more robust incentive mechanisms for reputation management in e-marketplaces.     

Design and analysis of miniaturized all-optical binary to gray code converter using Y-shaped plasmonic waveguide for optical processors

In this paper, an all-optical miniaturized binary to gray code converter is designed and analyzed. The all-optical domain is now an alternative for electronic devices, where performance and speed are the key issues. Code converters are significantly used in digital data transmission in the areas of error detection and correction. Gray code is one of the cyclic codes, where the cyclic shift of each codeword is also a code word. An all-optical XOR gate, realized using a Y-shaped power combiner is used in this design to generate the desired gray code from the given binary code. The insertion loss and extinction ratio parameters are found to be 0.347 dB and 22.26 dB, respectively. The entire simulation is carried out using finite-difference time-domain method. The obtained practical results are verified mathematically using MATLAB.

     

Catastrophic Failure of a Steel Chimney in a Lime Plant

Failure analysis of a steel chimney used in a lime plant was carried out. The chimney broke from two different locations during a storm. During the site visit, it was observed that the chimney was dislodged from weld joints. The chimney was made up of hot rolled mild steel plates. Investigations were carried out on the failed chimney plate and welding between plates. The investigation consists of visual observation, chemical analysis, characterization of macro- and microstructures, measurement of hardness, tensile property tests and energy-dispersive spectroscopy (EDS). Calculation of wind load at the location of breakage was also carried out. EDS analysis revealed entrapment of slag inside weld. Overall analysis suggested that the failure took place due to selection of improper reconditioning technique as well as poor workmanship in welding.     

FSAP Protects against Histone-Mediated Increase in Endothelial Permeability In Vitro

Factor-VII-activating protease (FSAP) is involved in the regulation of hemostasis and inflammation. Extracellular histones play a role in inflammation and the conversion of latent pro-FSAP into active FSAP. FSAP has been shown to regulate endothelial permeability, but the mechanisms are not clear. Here, we have investigated the effects of FSAP on endothelial permeability in vitro. A mixture of histones from calf thymus stimulated permeability, and the wild-type (WT) serine protease domain (SPD) of FSAP blocked this effect. WT–SPD–FSAP did not influence permeability on its own, nor that stimulated by thrombin or vascular endothelial growth factor (VEGF)-A₁₆₅. Histones induced a large-scale rearrangement of the junction proteins VE-cadherin and zona occludens-1 from a clear junctional distribution to a diffuse pattern. The presence of WT–SPD–FSAP inhibited these changes. Permeability changes by histones were blocked by both TLR-2 and TLR4 blocking antibodies. Histones upregulated the expression of TLR-2, but not TLR-4, in HUVEC cells, and WT–SPD–FSAP abolished the upregulation of TLR-2 expression. An inactive variant, Marburg I (MI)–SPD–FSAP, did not have any of these effects. The inhibition of histone-mediated permeability may be an important function of FSAP with relevance to sepsis, trauma, and stroke and the need to be investigated further in in vivo experiments.     

Designing linear distributed algorithms with memory for fast convergence

Motivated by both distributed computation and decentralized control applications, we studied the distributed linear iterative algorithms with memory. Specifically, we showed that the system of linear equations G x = b can be solved through a distributed linear iteration for arbitrary invertible G using only a single memory element at each processor. Further, we demonstrated that the memoried distributed algorithm can be designed to achieve much faster convergence than a memoryless distributed algorithm. Two small simulation examples were included to illustrate the results. Copyright © 2011 John Wiley & Sons, Ltd.     

Pinch Roller Failure Analysis and Resulting Enhancement of Rebar Mechanical Properties

Reinforcing bars, popularly termed “rebars,” are used to impart tensile strength to concrete structures. Concrete has high resistance to weathering and fire and high compressive strength but almost no tensile strength, hence rebars are used to provide the latter to concrete. Property consistency along the length of rebars is an important prerequisite. When the finished product is subjected to thermomechanical treatment (TMT), proper control of rolling and water box parameters and efficient pinch rolling are needed to achieve acceptable properties. Variation of yield strength (YS) along TMT bars from the front to back end has been observed within the same heat treatment. In the presented investigation, it was observed that pinch rolling ineffectiveness is the main reason for the poor mechanical properties at the back end. The pinch roller was unable to support the back end of the TMT bars properly to maintain the speed and tension of the bars, resulting in nonuniform cooling of the back end through the water box and subsequent mechanical property failure. Due to the substandard material of the pinch roller, it was unable to hold the back end of the bar properly. Based on analysis of the roller it was concluded that it failed due to improper microstructure, resulting in inadequate hardness and toughness for the stringent operating conditions. AISI H13 is a better material to use in such high-service-temperature conditions. Moreover, proper heat treatment is needed to achieve adequate hardness and microstructure properties. After proper heat treatment of pinch rollers, their service life was increased twofold, minimizing the YS variation along the rebars.