Byzantine Vector Consensus in Complete Graphs

Consider a network of n processes each of which has a d-dimensional vector of reals as its input. Each process can communicate directly with all the processes in the system; thus the communication network is a complete graph. All the communication channels are reliable and FIFO (first-in-first-out). The problem of Byzantine vector consensus (BVC) requires agreement on a d-dimensional vector that is in the convex hull of the d-dimensional input vectors at the non-faulty processes. We obtain the following results for Byzantine vector consensus in complete graphs while tolerating up to f Byzantine failures: * We prove that in a synchronous system, n >= max(3f+1, (d+1)f+1) is necessary and sufficient for achieving Byzantine vector consensus. * In an asynchronous system, it is known that exact consensus is impossible in presence of faulty processes. For an asynchronous system, we prove that n >= (d+2)f+1 is necessary and sufficient to achieve approximate Byzantine vector consensus. Our sufficiency proofs are constructive. We show sufficiency by providing explicit algorithms that solve exact BVC in synchronous systems, and approximate BVC in asynchronous systems. We also obtain tight bounds on the number of processes for achieving BVC using algorithms that are restricted to a simpler communication pattern

Surgical consideration in posterior C1-2 instrumentation in case of vertebral artery anomaly

Anatomical variations in the course of the vertebral artery have been previously described in the literature. Generally, these predictable patterns of variations commonly observed in lower cervical vertebral artery anatomy and less commonly described for upper cervical vertebral artery anatomy. Due to presence of these variations, treatment options for upper cervical spine pathology may be influenced and sometimes prevent commonly performed stabilization procedures.  Herein author presented a case of vertebral artery anatomic variation at the craniovertebral junction and management option for such variations

Spectrum Sensing Using CSMA Technique

Cognitive Radio is an emerging frontier to tackle the ever increasing demand of spectral needs. The most important function of CR is to search for spectrum holes or white spaces in the spectrum. Many techniques has been introduced and researched to increase the efficiency and accuracy of Spectrum Sensing. With the introduction of more complex methods cost of the whole process also increases. The following paper suggests a new idea of involving CSMA technique for spectrum sensing. This paper will give an insight on working of CR and CSMA technique. Later it will put forward the criterion for spectrum sensing and how CSMA can be used for investigate the presence of primary user in the spectrum vicinity

A comparative study of collagen-based dressing versus conventional dressing in chronic ulcers

Background: Collagen is a fibrous structure, proline-rich protein, comprised of three α-chains, plays an important role in each stage of wound healing, attracts fibroblasts and keratinocytes which in turn encourages debridement, angiogenesis and re-epithelializationMethods: This is a prospective cohort study. After obtaining ethical clearance from Institute’s ethical committee, all the patients fulfilling inclusion criteria were enrolled and written consent was obtained from all the patients. Detailed history was enquired and recorded on a predesigned proforma. The ulcer healing, analysed as- Time required for appearance of healthy granulation tissue, 50% reduction in ulcer size, complete healing time, requirement of skin grafting, time required in return to daily activities.Results: A significant decrease in time required for 50 % reduction in wound size with a mean difference of 18.5 in collagen group patients when compared to 37.5 and 33.0 in Normal saline group patients and Povidone iodine group patients. Chi square test was applied to assess the difference in proportions between groups t test was applied to compare the mean between the groups. P<0.05 was considered as statically significant.Conclusions: Healing with collagen particles is early, compared to the conventional dressings with lesser requirement of skin grafting, number of dressings, shorter hospital stay. Dressing changed every 3-4 days. Healing occurs by formation of early granulation tissue and wound contraction

Pasting Characteristics of Stored Wheat in Hermetic Bags and Conventional Methods

This study was performed in India to observe the effect of type of structure on pasting characteristics of stored wheat. Wheat of WH-711 variety was stored in hermetic bag and two conventional grain storage structures viz. steel bin and gunny bag piles which are usually employed in India. Pasting characteristics of wheat flour were measured in the Rapid Visco-Analyzer (RVA). The results revealed the significant influence of type of structure on pasting properties of stored wheat. Highest values of peak, trough, setback and final viscosity were observed in steel bins storage and minimum were in the gunny bag storage. Peak, trough, and final viscosity were found to be increased with the advancement of storage time in all structures. Setback and breakdown viscosity decreased with time. Breakdown and maximum setback viscosity were found minimum in hermetic bag storage, gave equal final viscosity as steel bins. Gelatinization temperature and peak time of all structures were same and remained constant. A small increase in the value of pasting temperature was observed in all the structures but maximum increase (about 1.5˚C) was recorded in gunny bags and minimum (0.8˚C) in hermetic storage than initial values

High-Fidelity Hydrostructural Design Optimization of Lifting Surfaces

Recent advances in high-performance computing and the efficiency of numerical solvers have made it possible to use sequential high-fidelity hydrodynamic and structural simulations to carry out design and optimization of marine lifting surfaces such as hydrofoils and propulsors. However, the design optimization of flexible hydrofoils and propellers requires coupled hydrodynamic and structural analysis to achieve a truly optimal, physically realizable, and structurally sound design. To address this need, the thesis presents an efficient high-fidelity hydrostructural design optimization with large numbers of design variables, multiple design points, as well as design constraints to avoid cavitation, avoid excessive stresses, and satisfy manufacturing tolerances. The hydrostructural solver couples a 3-D nearly incompressible Reynolds-averaged Navier–Stokes solver with a 3-D structural finite-element solver. The hydrostructural solver is validated by comparing the hydrodynamic load coefficients and tip bending deformations of a cantilevered aluminum hydrofoil with a NACA 0009 cross section and a trapezoidal planform. A coupled adjoint approach for efficient computation of the performance and constraint function derivatives with respect to 210 shape design variables is used. Using this state-of-the-art hydrostructural design optimization tool, a multipoint optimization yields improved performance over the entire range of expected operating conditions with significantly increased cavitation inception speed. The hydrostructural optimal result is compared to an equivalent hydrodynamic-only optimization, and results show that only the hydrostructural optimized design satisfies the stress constraint up to the highest expected loading condition, highlighting the need for coupled hydrostructural optimization. The proposed approach enables multipoint optimization of the hydrostructural performance for hydrofoils and marine propulsors, and it constitutes a powerful new tool for improving existing designs, and exploring new concepts. The thesis also presents the first experimental validation of a numerically optimized hydrofoil designed using the developed hydrostructural optimization tool. Good agreement is observed between the predictions and measurements, where both showed that the optimized hydrofoil yielded an overall increase in the lift-to-drag ratio of 29% and significantly delayed cavitation inception compared to the NACA 0009 baseline. In keeping up with the recent advances in material and manufacturing technology, the possibility of using composite material for marine propulsors is investigated. Combined experimental and numerical studies are presented to understand the benefits and challenges of using composite material for the maritime applications. The composite hydrofoils are manufactured by Defence Science and Technology Group (DSTG), Australia and are tested in the cavitation tunnel at Australian Maritime College (AMC), Australia. Results are presented for three composite hydrofoils with different orientations of the structural carbon layers, resulting in a different material-based bend-twist coupling. The results show that the material-based bend-twist coupling has a significant impact on the load-dependent deformation response, stall boundary, modal characteristics, susceptibility to static divergence, and cavity dynamics. This thesis helps in advancing the understanding of the impact of load-dependent bend-twist coupling on the performance of adaptive composite hydrofoils. We also took the first step towards developing a high-fidelity hydrostructural design optimization tool for composite hydrofoils by extending our structural solver to simulate the performance of anisotropic composite hydrofoils. The high-fidelity hydrostructural solver combined with the improved understanding of the material-based bend-twist coupling has the potential to play an important role in the analysis, design, and optimization of the next generation adaptive composite marine propulsors.PHDNaval Architecture & Marine EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/138569/1/gargn_1.pd