64 research outputs found

    Current distribution and group velocities for electronic states on αT3\alpha-\mathcal{T}_3 lattice ribbons in a magnetic field

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    We study the group velocities of electronic states and distributions of currents in αT3\alpha-\mathcal{T}_3 lattice ribbons under a uniform perpendicular magnetic field. Using the effective low-energy model we analyze all possible simple configurations of lattice termination with zigzag and armchair boundaries. We show that the edge current depends on the type of zigzag termination, and can be zero or finite near the edge. Also similar dependence is observed in the case of armchair termination and is related to the size of the ribbon. The nonzero current flowing along the edge can be used a signature of formation of propagating edge states. Also we show the qualitative difference in the distribution of the edge current between the case of α=1\alpha=1 (dice model) and other values of model parameter α1\alpha\neq 1 for armchair-terminated ribbons.Comment: 11 pages, 6 figure

    ENTERPRISE MANAGEMENT IN THE CONTEXT OF EXPANDING THE SCOPE OF BLOCKCHAIN TECHNOLOGY

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    The method of creating an automated enterprise management system is considered. The method is based on the ideas of the imitation approach and fuzzy mathematics. Real-time enterprise planning is the goal. The method is relevant in the context of setting up the market for goods and services with the expansion of e-commerce. The model of the formation of the plan of the enterprise for the execution of the orders received is considered.

    SCHEDULING REAL-TIME GRAPH-BASED WORKLOADS

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    Developments in the semiconductor industry in the previous decades have made possible computing platforms with very large computing capacities that, in turn, have stimulated the rapid progress of computationally intensive computer vision (CV) algorithms with highly parallelizable structure (often represented as graphs). Applications using such algorithms are the foundation for the transformation of semi-autonomous systems (e.g., advanced driver-assist systems) to future fully-autonomous systems (e.g., self-driving cars). Enabling mass-produced safety-critical systems with full autonomy requires real-time execution guarantees as a part of system certification.Since multiple CV applications may need to share the same hardware platform due to size, weight, power, and cost constraints, system component isolation is necessary to avoid explosive interference growth that breaks all execution guarantees. Existing software certification processes achieve component isolation through time partitioning, which can be broken by accelerator usage, which is essential for high-efficacy CV algorithms.The goal of this dissertation is to make a first step towards providing real-time guarantees for safety-critical systems by analyzing the scheduling of highly parallel accelerator-using workloads isolated in system components. The specific contributions are threefold.First, a general method for graph-based workloads’ response-time-bound reduction through graph structure modifications is introduced, leading to significant response-time-bound reductions. Second, a generalized real-time task model is introduced that enables real-time response-time bounds for a wider range of graph-based workloads. A proposed response-time analysis for the introduced model accounts for potential accelerator usage within tasks. Third, a scheduling approach for graph-based workloads in a single system component is proposed that ensures the temporal isolation of system components. A response-time analysis for workloads with accelerator usage is presented alongside a non-mandatory schedulability-improvement step. This approach can help to enable component-wise certification in the considered systems.Doctor of Philosoph

    GEDF Tardiness: Open Problems Involving Uniform Multiprocessors and Affinity Masks Resolved

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    Prior work has shown that the global earliest-deadline-first (GEDF) scheduler is soft real-time (SRT)-optimal for sporadic task systems in a variety of contexts, meaning that bounded deadline tardiness can be guaranteed under it for any task system that does not cause platform overutilization. However, one particularly compelling context has remained elusive: multiprocessor platforms in which tasks have affinity masks that determine the processors where they may execute. Actual GEDF implementations, such as the SCHED_DEADLINE class in Linux, have dealt with this unresolved question by foregoing SRT guarantees once affinity masks are set. This unresolved question, as it pertains to SCHED_DEADLINE, was included by Peter Zijlstra in a list of important open problems affecting Linux in his keynote talk at ECRTS 2017. In this paper, this question is resolved along with another open problem that at first blush seems unrelated but actually is. Specifically, both problems are closed by establishing two results. First, a proof strategy used previously to establish GEDF tardiness bounds that are exponential in size on heterogeneous uniform multiprocessors is generalized to show that polynomial bounds exist on a wider class of platforms. Second, both uniform multiprocessors and identical multiprocessors with affinities are shown to be within this class. These results yield the first polynomial GEDF tardiness bounds for the uniform case and the first such bounds of any kind for the identical-with-affinities case

    Study of the laws of oxidation of biodiesel

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    The paper discusses in detail the first stage of the catalytic oxidation of fatty acid methyl esters with atmospheric oxygen. According to the data obtained as a result of processing the kinetic data, it was concluded that the reactivity of the components of biodiesel. It is established that polyunsaturated and monounsaturated compounds have different reactivity. The kinetic pattern of consumption of unsaturated components of biodiesel was set up and kinetic constants were calculated, which are equal to: oxidation of C18/1 k1 = 0.106 ± 0.008 h-1, and oxidation of C18/2 k2 = 0.269 ± 0.005 h-1, respectively

    Investigation of vibratory drilling model with adaptive control. Part 2: mixed control of peak-to-peak vibration displacement and cutting continuity index

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    Chip segmentation is important condition for deep drilling efficiency improving. Chip segmentation could be ensured by sustaining stable axial self-excited vibrations of a drill. Vibrations are excited by regenerative effect when cutting edges move along the surface formed by previous passes. The conditions required for reliable chip segmentation could be created by using of a special vibratory head with an elastic element, providing tool additional axial flexibility. To maintain stable vibro-process with amplitude sufficient for chip segmentation, it’s suggested to use the vibratory head with a special actuator for adaptive feedback control proportional to a tool vibration velocity. Two algorithms of the feedback gain adaptation are proposed in the present paper: the adaptation by peak-to-peak displacement and the mixed adaptation by peak-to-peak displacement with cutting continuity index. The investigation of effectiveness of the proposed algorithms applicable to the model, described in [9], is also presented

    Genetic Improvement of Bread Wheat for Stem Rust Resistance in the Central Federal Region of Russia: Results and Prospects

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    Advanced breeding lines of spring and winter wheat with several effective resistance genes to stem rust, including its aggressive race Ug99, were developed for the first time for the non-Chernozem zone of Russia. Modern wheat varieties cultivated in this region have high productivity and grain quality. However, they are susceptible to fungal diseases and therefore are cultivated using frequent fungicides treatments. The introgression wheat lines with multiple alien translocations (“Arsenal” collection) have been developed in the Moscow Scientific Research Institute of Agriculture “Nemchinovka” by using gamma irradiation of pollen of wild wheat relatives (Aegilops speltoides, Ae. triuncialis, Triticum kiharae, Secale cereale). Initial material with several effective Sr resistance genes for wheat breeding was developed using donors from the “Arsenal” and the VIR collections. The created initial material can compete with modern varieties, as it has resistance to leaf rust and powdery mildew, high productivity and numerous other advantages. On this basis, a new direction in breeding of spring and winter wheat is developed for this region, that is, creation of wheat cultivars with resistance to fungal diseases. This allows to reduce the fungicide load during cultivation with the goal of producing ecologically clean grain for healthy diet

    Modeling of defects in electronic navigation devices operating in extreme conditions

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    An investigation of the corrosive and mechanical destruction of microelectronic objects such as multipurpose sensors and navigating devices used in the airspace industry in extreme conditions such as variable temperature, pressure and environmental composition is described. The appearance and growth of micro cracks and other defects in metallic parts and conductors of micro devices due to external actions are investigated. The structural features of defect‐testing devices improved on the basis of magnetic modulation sensitive iron elements are analyzed. Mathematical modeling for the most characteristic types of defects is performed and the forecast growth of defects within 6 % accuracy is achieved. Santrauka Atlikti mikroelektronikos objektų, eksploatuojamų ekstremaliomis sąlygomis bei esant kintamoms temperatūroms, slėgiui, darbinės aplinkos sudėčiai, irimo tyrimai, tarp jų – mikroįtrūkimų ir kitų defektų atsiradimo bei augimo mikroprietaisų metalinėse dalyse ir laidininkuose. Pagerinti prietaisų, gaminamų fero-moduliacinių elementų pagrindu ir skirtų mikroprietaisų defektų kontrolei, konstruktyviniai sprendimai. Sudarytas matematinis modelis, leidžiantis analizuoti būdingiausių rūšių defektus ir iki 6 % tikslumu prognozuoti defektų plitimą. First Published Online: 14 Oct 2010 Reikšminiai žodžiai: defektų detektavimas, mikroįtrūkimas, matematinis įtrūkimų modeliavimas

    Regulation of the interaction between PIPKIγ and talin by proline-directed protein kinases

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    The interaction of talin with phosphatidylinositol(4) phosphate 5 kinase type Iγ (PIPKIγ) regulates PI(4,5)P2 synthesis at synapses and at focal adhesions. Here, we show that phosphorylation of serine 650 (S650) within the talin-binding sequence of human PIPKIγ blocks this interaction. At synapses, S650 is phosphorylated by p35/Cdk5 and mitogen-activated protein kinase at rest, and dephosphorylated by calcineurin upon stimulation. S650 is also a substrate for cyclin B1/Cdk1 and its phosphorylation in mitosis correlates with focal adhesion disassembly. Phosphorylation by Src of the tyrosine adjacent to S650 (Y649 in human PIPKIγ) was shown to enhance PIPKIγ targeting to focal adhesions (Ling, K., R.L. Doughman, V.V. Iyer, A.J. Firestone, S.F. Bairstow, D.F. Mosher, M.D. Schaller, and R.A. Anderson. 2003. J. Cell Biol. 163:1339–1349). We find that Y649 phosphorylation does not stimulate directly PIPKIγ binding to talin, but may do so indirectly by inhibiting S650 phosphorylation. Conversely, S650 phosphorylation inhibits Y649 phosphorylation by Src. The opposite effects of the phosphorylation of Y649 and S650 likely play a critical role in regulating synaptic function as well as the balance between cell adhesion and cell motility

    Dynamic fracture in carbon-fibre composites: Effect of steel and ice projectiles

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    In this study the resultant ballistic dynamic response observed in a 2x2 twill weave T300 carbon fibre/epoxy composite flat-plate specimen is examined, using a combination of non-invasive analysis techniques. The study investigates deformation, damage and fracture following the impacts with both solid (steel) and fragmenting (ice) projectiles travelling with velocities of 70-90 m/s and 300-500 m/s, respectively. Digital image correlation was employed to obtain displacement data for the rear surfaces of the specimens in each experiment, and used to assess the effect of impact velocity and projectile material on the specimen’s response. 3D X-ray computed tomography was used to image and visualize the resultant internal cloud of damage and fracture, initiated by dynamic loading in each specimen. It was shown that solid projectiles led to greater localized deformation and, in some cases, penetration, whereas fragmenting projectiles destroyed on impact resulted in more distributed loading leading to major front-surface damage depending on the depth on indentation before fragmentation
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