230 research outputs found
Exact shock measures and steady-state selection in a driven diffusive system with two conserved densities
We study driven 1d lattice gas models with two types of particles and nearest
neighbor hopping. We find the most general case when there is a shock solution
with a product measure which has a density-profile of a step function for both
densities. The position of the shock performs a biased random walk. We
calculate the microscopic hopping rates of the shock. We also construct the
hydrodynamic limit of the model and solve the resulting hyperbolic system of
conservation laws. In case of open boundaries the selected steady state is
given in terms of the boundary densities.Comment: 12 pages, 4 figure
Bethe ansatz and current distribution for the TASEP with particle-dependent hopping rates
Using the Bethe ansatz we obtain in a determinant form the exact solution of
the master equation for the conditional probabilities of the totally asymmetric
exclusion process with particle-dependent hopping rates on Z. From this we
derive a determinant expression for the time-integrated current for a
step-function initial state.Comment: 14 page
Logarithmic current fluctuations in non-equilibrium quantum spin chains
We study zero-temperature quantum spin chains which are characterized by a
non-vanishing current. For the XX model starting from the initial state |... +
+ + - - - ...> we derive an exact expression for the variance of the total spin
current. We show that asymptotically the variance exhibits an anomalously slow
logarithmic growth; we also extract the sub-leading constant term. We then
argue that the logarithmic growth remains valid for the XXZ model in the
critical region.Comment: 9 pages, 4 figures, minor alteration
Broken ergodicity in driven one-dimensional particle systems with short-range interaction
We present a one-dimensional nonequilibrium model for a driven
di�usive system which has local interactions and slow nonconservative reaction
kinetics. Monte-Carlo simulations suggest that in the thermodynamic limit
the steady state exhibits a phase with broken ergodicity. We propose a hydrodynamic
equation for the coarse-grained density (under Eulerian scaling),
augmented by a prescription how to treat shock and boundary discontinuities,
respectively. This conjecture can be readily generalized to other weakly nonconservative
driven di�usive systems and is supported by a heuristic identi�cation
of the main dynamical mode that governs the microscopic dynamics, viz. the
random motion of a shock in an self-organized e�ective potential. This picture
leads to the exact phase diagram of the system and suggests a novel and
mathematically tractable mechanism for \freezing by heating"
Stable and unstable nasal stems in Khalkha Mongolian
Declension of nasal stem nouns differs from that of standard consonant and vowel stems. The four nasal stem types discussed in the paper are not strict categories, a wide range of nouns show variance in the use of suffixes characteristic of one or another stem type, and also several examples of semantic split can be observed. Data obtained from the internet using a search engine show the distribution of the alternating forms, the tendencies of certain changes of stem types and also prove the spreading of unstable n-stems and velar nasal stems. The most complex phenomenon among Khalkha nasal stem types is the unstable n which is not simply a lexically encoded empty morpheme or a phonological feature in the declension paradigm of a particular noun class, but it has certain grammatical functions as well
Analysis of changes in resources and outputs of companies and partnerships in Hungarian agriculture
The aim of the study was to examine the achievement of Hungarian agricultural companies and partnerships, particularly agricultural co-operatives based on the aggregated database of National Tax and Customs Administration (NAV)1. From the methodological aspect, descriptive statistical methods and time series analysis were used. One of the most important conclusions is that the socio-economic weight of the agricultural co-operatives was strongly decreased in the period after the EU accession. The other important statement is that apart from the general examination of economic actors on aggregated level the comparative analysis of the single organizations forms would be needed. In the case of co-operatives, separated examination of the former type producer co-operatives and the so-called new type ones (e.g. marketing co-operatives etc.) would be necessary
Gazdaságszerkezet alakulása az EU-ban, különös tekintettel Magyarországra
Magyarország az EU-27 tagországai közül a kedvezőnek mondható ökológiai adottságú országok körébe sorolható. Az ország teljes területének mintegy 60%-a (5,3 millió hektár) áll mezőgazdasági művelés alatt, az EU-ban ennél csak Dániában és Nagy-Britanniában magasabb a mezőgazdasági terület aránya. Az EU-27 tagállamok összes mezőgazdasági területéből mindössze 3%-kal részesedik Magyarország, ennek ellenére egyes termékek előállításában jelentős a szerepe. Az EU-27 tagországok gazdaságait vizsgálva kiderül, hogy a gazdaságok 80%-a 10 hektárnál kisebb mezőgazdasági területen, 14%-uk 10–50 hektár közötti, illetve 3%-uk 50–100 hektár közötti mezőgazdasági területen gazdálkodik. A 100 hektár feletti mérettel rendelkező üzemek aránya csupán 3%, ugyanakkor a mezőgazdasági terület 50%-át művelik. A magyar gazdaságszerkezet egyedinek mondható az EU-ban (bár fontos megjegyezni, hogy Lengyelországban és Romániában is elaprózódott a birtokszerkezet). A gazdaságok 87%-a 5 hektárnál kisebb területen gazdálkodik, míg az 50 hektár feletti gazdaságok aránya csekély. Magyarországon elaprózódott a birtokstruktúra, amihez hozzájárul, hogy a gazdaságok számbavételénél a gazdasági küszöb mértéke igen alacsony. Ennek köszönhetően a gazdaság fogalma jelentősen eltér az üzemgazdaságban használt definícióktól. A Központi Statisztikai Hivatal (KSH) a gazdaság fogalmába a vidéki háztartásokat is beleérti, így az agrárpolitika által megcélzott mezőgazdasági üzemek (árutermelő gazdaságok) összemosódnak a számokban.---------------In the European Union (EU), Hungary is ranked among the countries with favourable ecological conditions. The utilised agricultural area (UAA) represents 60% (5.3 million hectares) of the country’s total area. In the EU only Denmark and Great Britain have a higher proportion of UAA. Hungary has only a 3% share in the total UAA of the EU, nevertheless Hungary plays an important role in the production of some crops. According to the analysis of agricultural holdings in the EU 80% of the farms farm less than 10 hectares, 14% farm 10 to 50 hectares, and 3% farm 50 to 100 hectares of land. Just 3% of the holdings farm over 100 hectares but these represent 50% of the total utilised agricultural area in the EU. The Hungarian farm structure seems to be unique in the EU (although Poland and Romania also have a fragmented farm structure). In Hungary 87% of the holdings farm less than 5 hectares, while only a tiny proportion of holdings farm over 50 hectares land. In Hungary a very low ceiling has been set for the minimum farm size contributing to the fragmented land structure. As a result, the definition of farms differs significantly from the definition used in farm business management analysis. As rural households are also included in the farm survey of the Hungarian Central Statistical Office the number of agricultural holdings differs significantly from that of commercial farms
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