210 research outputs found

    How can America challenge China's political ambitions in an age of deglobalisation?

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    COVID-19 has accelerated the trend of deglobalisation and further entrenched China into the growing political and economic fort of Asia. This has made the US less effective at implementing policies aimed at curbing Beijing’s political ambitions and strength in the region. Washington must therefore make itself indispensable in Asia and employ strategies for bringing China into a global network that can collectively reign in the Asian giant’s growing influence

    Experimental Analysis of the Feasibility of Polydisperse Droplet Water Flow Using at Fire Extinguishing

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    With use of modern diagnostic methods the experimental researches of the process of the sprayed water evaporation at its movement through a flame of the fixed height was conducted. The change ranges of the main integrated evaporation characteristics of the sprayed water droplets (rates, sizes, concentration in a flow) are established. It is shown that at the extinguishing of fires the most expedient decision is the use of polydisperse droplet flows

    Waterbirds of Uvs-Nuur Depression

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    This report provides an overview of water birds (Non-Passeriformes) inhabiting the lakes of Uvs- Nuur Depression. The article includeds material obtained during field work in the Uvs-Nuur Depression during 1999-2006, unpublished observations of rare vagrant species of birds, and data from the literature. Altogether we and others recorded 81 bird species from ten families on the lakes within the basin. The list we provide does not include sparrows or birds from habitats closely associated with the basin. The following non-Passeriformes bird families were noted (with the number of species in parentheses): Gaviidae (1), Podicipedidae (2), Phalacrocoracidae (1), Ardeidae (5), Anatidae (27), Gruidae (6), Charadriidae (5), Recurvirostridae (2), Scolopacidae (21), and Laridae (11). We noted the following rare vagrant species: Ixobrychus minutus, Anser albifrons, Grus leucogeranus. The report also presents some quantitative data of bird observations

    Investigation of the Extinguishing Features for Liquid Fuels and Organic Flammable Liquids Atomized by a Water Flow

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    The processes of heat and mass transfer were investigated experimentally while moving and evaporating the atomized water flow in high-temperature combustion products of typical liquid fuels and organic flammable liquids: gasoline, kerosene, acetone, crude oil, industrial alcohol. We determined typical periods of liquid extinguishing by an atomized water flow of various dispersability. Data of the discharge of extinguishing medium corresponding to various parameters of atomization and duration of using the atomization devices was presented. It is shown that U[m]≈3.5 m/s is a minimal outflow velocity of droplets during moving while passing the distance of 1m in the high-temperature gas medium to stop the combustion of organic liquid

    Numerical investigations of two-dimensional photonic crystal optical properties, design and analysis of photonic crystal based structures

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    Two-dimensional (2D) photonic crystals (PhCs) operating in the near-infrared wavelengths are promising candidates for novel integrated optics applications. In this work the optical properties of the Bloch modes in 2D photonic crystals have been investigated theoretically using different numerical methods. The plane wave expansion (PWE) method have been formulated in a general form for arbitrary 2D photonic crystal and applied for detailed analysis of the properties of the Bloch modes. The k space based and the frequency based PWE methods have been derived and used, which allowed us to analyze both propagating and evanescent modes. The guided mode expansion method has been used to take into account three-dimensional distribution of the electromagnetic field in the planar photonic crystals and improve the accuracy of the analysis. A new method of calculation of the sensitivity of the photonic crystal optical properties to small variations of the photonic crystal parameters has been developed. This method is based on the perturbation theory and allows fast and accurate estimation of the optical properties corrections as a result of a change the parameters of the photonic crystal. The developed methods have been used for design and analysis of different photonic crystal based structures, such as cavities, waveguides, coupled-cavity waveguides and polarization beam splitter. The developed methods proved to be efficient and accurate tools for modelling two-dimensional photonic crystal properties and design of photonic crystal based devices

    The Difference between the Integral Characteristics of Two and Three Water Droplets Moving Sequentially through High-Temperature Combustion Products and Air

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    This paper focuses on the study of macroscopic regularities that describe how moving droplets influence on the evaporation of subsequent droplets in high-temperature gases (1100 K) and air at moderate temperatures (about 300 K). Experiments have been conducted by means of high-speed video recording and using specialized software. Investigations have been performed for two and three successive droplets with the initial radius of 1.5 mm. The effect of droplet braking, coagulation and acceleration has been defined. The typical difference between velocities, sizes and distances of successive droplets has been demonstrated

    Totalitarianism and geography: L.S. Berg and the defence of an academic discipline in the age of Stalin

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    In considering the complex relationship between science and politics, the article focuses upon the career of the eminent Russian scholar, Lev Semenovich Berg (1876–1950), one of the leading geographers of the Stalin period. Already before the Russian Revolution, Berg had developed a naturalistic notion of landscape geography which later appeared to contradict some aspects of Marxist–Leninist ideology. Based partly upon Berg's personal archive, the article discusses the effects of the 1917 revolution, the radical changes which Stalin's cultural revolution (from the late 1920s) brought upon Soviet science, and the attacks made upon Berg and his concept of landscape geography thereafter. The ways in which Berg managed to defend his notion of geography (sometimes in surprisingly bold ways) are considered. It is argued that geography's position under Stalin was different from that of certain other disciplines in that its ideological disputes may have been regarded as of little significance by the party leaders, certainly by comparison with its practical importance, thus providing a degree of ‘freedom’ for some geographers at least analogous to that which has been described by Weiner (1999. A little corner of freedom: Russian nature protection from Stalin to Gorbachev. Berkeley: University of California Press) for conservationists. It is concluded that Berg and others successfully upheld a concept of scientific integrity and limited autonomy even under Stalinism, and that, in an era of ‘Big Science’, no modernizing state could or can afford to emasculate these things entirely

    Semiconductor High-Energy Radiation Scintillation Detector

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    We propose a new scintillation-type detector in which high-energy radiation produces electron-hole pairs in a direct-gap semiconductor material that subsequently recombine producing infrared light to be registered by a photo-detector. The key issue is how to make the semiconductor essentially transparent to its own infrared light, so that photons generated deep inside the semiconductor could reach its surface without tangible attenuation. We discuss two ways to accomplish this, one based on doping the semiconductor with shallow impurities of one polarity type, preferably donors, the other by heterostructure bandgap engineering. The proposed semiconductor scintillator combines the best properties of currently existing radiation detectors and can be used for both simple radiation monitoring, like a Geiger counter, and for high-resolution spectrography of the high-energy radiation. The most important advantage of the proposed detector is its fast response time, about 1 ns, essentially limited only by the recombination time of minority carriers. Notably, the fast response comes without any degradation in brightness. When the scintillator is implemented in a qualified semiconductor material (such as InP or GaAs), the photo-detector and associated circuits can be epitaxially integrated on the scintillator slab and the structure can be stacked-up to achieve virtually any desired absorption capability
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