1,895 research outputs found

    The general structure analysis of avalanche (mudflow) risk assessment

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    The basic structure of risk assessment is studied. The general form of the assessment formula consists of three components - temporal, spatial and anthropogenic ones. The role and contribution of these components are considered from standpoint of two approaches small- and large- scales ( in mapping sense too).The quantative evaluation of contributions is made on the example of avalanche (rnudflow) risk assessment for highroad in the Elbrus vicinity. We concluded the most important temporal component may vary from 10 -6 and less to approx.l according to used and observed data' and consideration scale. So this component becomes comparable with a spatial probability in order. So in the first case we have a background, smoothed assessment of small-scale analysis. In the second one we get a concrete or specific dated (predicted) risk for the real situation by large-scale consideration. In some cases the latter assessment may significantly exceed the former. So we suggest the corresponding term for this risk kind to include in general risk classification scheme

    Size and shape of graphene layers in commercial carbon blacks established by Debye refinement

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    PGB acknowledges financial support of EPSRC, including the SUPERGEN project.The size and the shape of graphene layers in commercial conductive carbon blacks, Super P® and Super S®, have been determined from powder X-ray diffraction data. Using a refinement procedure based on the fundamental diffraction equation of Debye, it is shown that the ordered regions within the layers of both materials are of elliptical shape, curved in a cylindrical fashion along the longer axis of the ellipse. The regions are greater in Super P®, ellipse axes: 5.4 and 2.2 nm, than in Super S®, 4.6 and 2.1 nm, and less curved, curvature radii: 12.7 and 11.7 nm respectively. There is no crystallographic registry between layers that are equidistantly stacked into concentric groups of 6 or 7, on average.PostprintPeer reviewe

    Ponomar Project Slavonic Computing Initiative Proposal to Encode Combining Glagolitic Letters in Unicode

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    Glagolitic, also known as “Glagolitsa”, is an alphabetic writing system used to record Church Slavonic and other Slavic languages. Originating in the 9 th century, it is the earliest known Slavonic alphabet. The creation of the alphabet is attributed to the younger of the teachers of the Slavs, St. Cyril

    Crystalline polymer electrolytes

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    In this chapter, we describe crystalline ion-conducting complexes formed by akali metal salts and poly(ethylene oxide). A variety of factors influencing the conductivity of such complexes are presented. Electrochemical testing of these materials in lithium and sodium rechargeable batteries demonstrate that crystalline polymer/salt complexes can be used as electrolytes in all-solid-state energy storage devices.Postprin

    Application of Hybrid Real-Time Power System Simulator for Designing and Researching of Relay Protection and Automation

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    Development, research and operation of smart grids (SG) with active-adaptive networks (AAS) are actual tasks for today. Planned integration of high-speed FACTS devices greatly complicates complex dynamic properties of power systems. As a result the operating conditions of equipment of power systems are significantly changing. Such situation creates the new actual problem of development and research of relay protection and automation (RPA) which will be able to adequately operate in the SGs and adapt to its regimes. Effectiveness of solution of the problem depends on using tools - different simulators of electric power systems. Analysis of the most famous and widely exploited simulators led to the conclusion about the impossibility of using them for solution of the mentioned problem. In Tomsk Polytechnic University developed the prototype of hybrid multiprocessor software and hardware system - Hybrid Real-Time Power System Simulator (HRTSim). Because of its unique features this simulator can be used for solution of mentioned tasks. This article introduces the concept of development and research of relay protection and automation with usage of HRTSim

    Dynamics of Multielement Agricultural Aggregates, Taking Into Account Nonholonomic Constraints and Spatial Motion

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    The paper studies a discrete system of multielement agricultural aggregate composed of a tractor, hopper and seeder. Mechanical model includes these elements, which are considered as rigid bodies and perform spatial motion subject to of the wheels considering elasticity. As the geometric constrains taking into account the flat surface of the earth and the hinges connecting the units. The aggregate is controlled by angle of the steering wheel or the angle between the tractor half-frames. A feature o f the model is the account of non-holonomic constraints caused by the rolling o f the wheels. This significantly reduces the number o f degrees o f freedom and also complicates the process of forming the equations o f motion. Differential equations are automatically generated by a special system of computer algebra KiDyM based on a general dynamics equation. The gravity force, the driving force and the resistance force applied to the elements o f the aggregate defined as force interactions. The studied linear motion, maneuvers with constant and harmonic law change o f control angle

    Software and Hardware Complex for Setting of Automatic Excitation Regulators of Turbogenerators

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    The motivation of the presented research is based on the needs for development of new methods and tools for research setting problem of automatic excitation regulators of turbogenerators. Simulation tools must meet the requirements of reproduction processes reliability in all elements of electric power system. The developed block diagram of the adequate mathematical model of automatic excitation regulator is presented. The simulation results of electric power system scheme confirm the adequacy of the reproduction processes of functioning of automatic excitation regulator and a generator

    Testing for nonlinearity in the choice of a freight transport service

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    Manufacturing firms buy transport services with the aim of minimizing their total logistics cost. There is a large amount of literature analyzing how shippers value the various characteristics of a transport service, mostly performed by collecting stated-preference data and estimating discrete choice models. Most of the empirical studies specify the deterministic part of the utility functions as linear in the observed attributes. This implicitly constrains the characteristics of the analyzed transport service to be perfect substitutes, and to have a constant substitutability ratio. Such an assumption is inconsistent with the standard microeconomic theory, typically assuming inputs’ decreasing marginal productivity, and may not be realistic. The paper tests the linearity assumption for freight rate, travel time, probability of having damaged and lost freight, frequency, flexibility, mode and punctuality on a sample of Italian small- and medium-sized manufacturing enterprises (SME). Our findings suggest that the linearity-in-the-attributes assumption should be rejected and that the marginal impact on the utility-of-profit of the attributes is not constant. More specifically travel time and freight rate produce decreasing marginal reductions of the utility-of-profit; while safety (percentage of not damaged or lost shipments) and punctuality (percentage of shipments on time) are responsible for increasing marginal contributions to the utility-of-profit. The substitutability ratios between (a) freight rate and loss and damage, (b) freight rate and travel time, (c) freight rate and punctuality, (d) travel time and damage and loss and (e) travel time and punctuality are estimated and found not constant. Finally, it is found that the willingness to pay for the qualitative attributes obtained with a linearly specified model tend to be overestimated
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