824 research outputs found

    Good management improves productivity, but it may worsen environmental performance

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    The reduction of greenhouse gas (GHG) emissions is an increasingly important policy objective for many governments, both in developed and developing economies. This is reflected, among other things, in the emergence of energy efficiency as a high-priority topic on the policy agenda. In manufacturing – one of the key sectors from the point of view of GHG emissions and energy intensity – improvements in energy efficiency can come about from upgrading or closing existing plants or adding new production capacity that uses more modern technology. Moreover, recent research has found that management practices – such as those focused on how a firm handles a process-related problem, collection of production indicators, the timescale and difficulty of its targets and incentives – also play a significant role in reducing the energy intensity of firms

    Magnetic ionization-thermal instability

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    Linear analysis of the stability of diffuse clouds in the cold neutral medium with uniform magnetic field is performed. We consider that gas in equilibrium state is heated by cosmic rays, X-rays and electronic photoeffect on the surface of dust grains, and it is cooled by the collisional excitation of fine levels of the CII. Ionization by cosmic rays and radiative recombinations is taken into account. A dispersion equation is solved analytically in the limiting cases of small and large wave numbers, as well as numerically in the general case. In particular cases the dispersion equation describes thermal instability of Field (1965) and ionization-coupled acoustic instability of Flannery and Press (1979). We pay our attention to magnetosonic waves arising in presence of magnetic field, in thermally stable region, 35T9535 \leq T \leq 95 K and density n\lessapprox 10^3\,\mbox{cm}^{-3}. We have shown that these modes can be unstable in the isobarically stable medium. The instability mechanism is similar to the mechanism of ionization-coupled acoustic instability. We determine maximum growth rates and critical wavelengths of the instability of magnetosonic waves depending on gas temperature, magnetic field strength and the direction of wave vector with respect to the magnetic field lines. The minimum growth time of the unstable slow magnetosonic waves in diffuse clouds is of 4604-60 Myr, minimum and the most unstable wavelengths lie in ranges 0.050.50.05-0.5 and 0.550.5-5 pc, respectively. We discuss the application of considered instability to the formation of small-scale structures and the generation of MHD turbulence in the cold neutral medium.Comment: 11 pages, 9 figures, 2 tables, accepted for publication in MNRA

    The Long Run Effects of R&D Place-based Policies: Evidence from Russian Science Cities

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    We study the long run effects of a unique historical place-based policies targeting R&D: the creation of “Science Cities” in former Soviet Russia. The establishment of Science Cities and the criteria for selecting their location were largely guided by political and military-strategic considerations. We compare current demographic and economic characteristics of Science Cities to those of appropriately matched localities that were similar to them at the time of their establishment. We find that in the modern Russian economy, despite the massive cuts of governmental support to R&D that followed the dissolution of the USSR, Science Cities host more high-skilled workers and more developed R&D and ICT sectors; are the origin of more international patents; and generally appear to be more productive and economically developed. Within a spatial equilibrium framework, we interpret these findings as the result of the interaction between persistence and agglomeration forces. Furthermore, we rule out alternative explanations that have to do with the differential use of public resources, and we find limited support for a case of equilibrium reversion. Finally, by analyzing firm-level data we obtain evidence in favor of spillover effects with a wide spatial breadth

    Optimization of Discrete Parameters Using the Adaptive Gradient Method and Directed Evolution

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    The problem is considered of optimizing discrete parameters in the presence of constraints. We use the stochastic sigmoid with temperature and put forward the new adaptive gradient method CONGA. The search for an optimal solution is carried out by a population of individuals. Each of them varies according to gradients of the 'environment' and is characterized by two temperature parameters with different annealing schedules. Unadapted individuals die, and optimal ones interbreed, the result is directed evolutionary dynamics. The proposed method is illustrated using the well-known combinatorial problem for optimal packing of a backpack (0-1 KP).Comment: 19 pages, 12 figure

    Experimental and Numerical Investigation of Near-field Rotor Aeroacoustics

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    This work presents comparisons between experimental and numerical estimates of near-field rotor aeroacoustics in hover. The experiments took place at the Kazan National Research Technical University named after A. N. Tupolev (Kazan Aviation Institute). A set of rotor blades with NACA-0012 aerofoil sections was used to obtain the sound pressure distribution using a linear array of microphones. It is shown that CFD and experimental results are in good agreement suggesting that the obtained test data can be useful as a validation case for development of CFD tools

    Experimental and numerical study of rotor aeroacoustics

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    The work documents recent experiments at the Kazan National Research Technical University named after A.N. Tupolev (Kazan Aviation Institute), related to helicopter acoustics. The objective is to measure nar-field acoustics of rotors in hover and provide data suitable for computational fluid dynamics validation. The obtained set of data corresponds to a scaled rotor of known planform and the results are of high resolution. An advantage of the current dataset is that direct near-field acoustic data is made available and this allows for easy and direct comparisons with computational fluid dynamics predictions, without the need to use far-field aeroacoustic methods

    Paleo-Balkan and Slavic Contributions to the Genetic Pool of Moldavians

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    Moldova has a rich historical and cultural heritage, which may be reflected in the current genetic makeup of its population. To date, no comprehensive studies exist about the population genetic structure of modern Moldavians. To bridge this gap with respect to paternal lineages, we analyzed 37 binary and 17 multiallelic (STRs) polymorphisms on the non-recombining portion of the Y chromosome in 125 Moldavian males. In addition, 53 Ukrainians from eastern Moldova and 54 Romanians from the neighboring eastern Romania were typed using the same set of markers. In Moldavians, 19 Y chromosome haplogroups were identified, the most common being I-M423 (20.8%), R-M17* (17.6%), R-M458 (12.8%), E-v13 (8.8%), RM269* and R-M412* (both 7.2%). In Romanians, 14 haplogroups were found including I-M423 (40.7%), R-M17* (16.7%), RM405 (7.4%), E-v13 and R-M412* (both 5.6%). In Ukrainians, 13 haplogroups were identified including R-M17 (34.0%), I-M423 (20.8%), R-M269* (9.4%), N-M178, R-M458 and R-M73 (each 5.7%). Our results show that a significant majority of the Moldavian paternal gene pool belongs to eastern/central European and Balkan/eastern Mediterranean Y lineages. Phylogenetic and AMOVA analyses based on Y-STR loci also revealed that Moldavians are close to both eastern/central European and Balkan-Carpathian populations. The data correlate well with historical accounts and geographical location of the region and thus allow to hypothesize that extant Moldavian paternal genetic lineages arose from extensive recent admixture between genetically autochthonous populations of the Balkan-Carpathian zone and neighboring Slavic group
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