Showing papers by "Romanian Academy published in 1993"
TL;DR: In this paper, the reciprocal distance (RD) matrix was defined, and three topological indices, namely RDSUM, RDSQ, and RDCHI, were defined.
Abstract: A new molecular graph matrix, the reciprocal distance (RD) matrix, is defined. Its nondiagonal elements are equal to the reciprocals of the topological distances between the corresponding vertices, while the diagonal elements are all equal to zero. Based on the RD matrix, a real-number local vertex invariant, RDS was proposed, and three topological indices, namely RDSUM, RDSQ, and RDCHI, were defined. Their degeneracy was investigated and proved to be lower than that of the topological index W based on the distance matrix. The correlational ability of the new molecular descriptors was tested against van der Waals molecular surfaces and boiling points of alkanes, showing a satisfactory monoparametric dependence.
258 citations
Journal Article•
TL;DR: It is demonstrated that lectin does not inhibit mycelial growth but irreversibly inhibits conidia germination and alters the germ tubes; and chitinases block mycelia growth as well as conidia Germination and lyse germ tubes.
Abstract: We have purified from potato tubers, the lectin STA devoid of chitinase activity and two chitinases devoid of lectin activity. Both enzymes are 16 kDa glycoproteins, and probably belong to a new family of plant chitinases. The respective antifungal properties of lectin and chitinases were studied by following their effects against early developmental stages of Fusarium oxysporum, a fungal potato pathogen. Here we demonstrate that: (1) lectin does not inhibit mycelial growth but irreversibly inhibits conidia germination and alters the germ tubes; and (2) chitinases block mycelial growth as well as conidia germination and lyse germ tubes.
65 citations
TL;DR: The authors used Clarke's generalised directional derivative to describe several types of invexity at a point of a nonlinear function, such as pseudo-and quasi-invexities.
Abstract: This paper uses Clarke’s generalised directional derivative to describe several types of invexity, pseudoinvexity and quasiinvexity at a point of a nonlinear function. Direct implications of the relations existing between the various types of invexity and generalised invexity are presented, as well as a block diagram of these implications. In particular, similar results in the class of quasiconvex functions are obtained.
27 citations
TL;DR: In this paper, the origin of the Danube delta is considered and its development is traced from the initial offshore bar, referring to the writings of the classical scholars and other sources.
Abstract: The Danube Delta is very large with diverse resources which have been intensively exploited during the modern period. It is now of great interest to conservationists with 280 species of birds (177 of which hatch in the delta). The origin of the delta is considered and its development is traced from the initial offshore bar, referring to the writings of the classical scholars and other sources. Modern developments involve the navigational work of the European Commission of the Danube (set up in 1856) and the more intensive exploitation of the reed beds, fisheries, agricultural lands and forests since 1950. Since the revolution of 1989 this programme has stopped and the delta (including the Razim-Sinoie lake complex) is now a Biosphere Reserve. The reserve is described and the principles for management are discussed.
26 citations
17 citations
TL;DR: In this article, it was proved that if X and Y are linear spaces and F : X → p(Y) is a set-valued map with convex graph such that F(x) ≠ O for allx ∈ X andF(x 0 ) is a singleton for somex 0, then F is single-valued and affine.
Abstract: It is proved that ifX andY are linear spaces andF :X →p(Y) is a set-valued map with convex graph such thatF(x) ≠ O for allx ∈X andF(x
0) is a singleton for somex
0, thenF is single-valued and affine. Applications to metric projections and to adjoints of set-valued maps are given.
15 citations
15 citations
12 citations
TL;DR: The results obtained from 1987-1991 at the two reservoirs where cyclic microbial recovery and microbial flooding recovery trials were carried out are discussed in this paper, where the possibilities of extending and improving these technologies at other reservoirs also are discussed.
Abstract: From 1975 to 1980, the first generation of MEOR field trials were carried out in Romania, based on microbial flooding recovery technology and using the level of technology of that time, with its pioneering deficiencies. The results were promising, but after 1980, it became apparent that many aspects of the MEOR technology we used should be improved, because a miracle is not possible with very simple MEOR technologies. This was the reason why, between 1980–1986, we prepared a “second generation” of MEOR field trials which took place between 1987–1991. Compared with the first generation of field trials, in this second generation we tried to improve the methods in the following ways: 1. enhancing the performance of the bacterial inoculum; 2. testing the inoculum for the production of substances involved in oil release; 3. with mathematical models, simulating the release of residual oil; 4. formulating a protocol for injecting the wells; 5. ensuring that adequate quantities of inoculum were used; and, 6. controlling nutrients and the time of their administration. In this paper we discuss the results obtained from 1987–1991 at the two reservoirs where cyclic microbial recovery and microbial flooding recovery trials were carried out. The possibilities of extending and improving these technologies at other reservoirs also are discussed.
12 citations
TL;DR: In this paper, the factors responsible for both maximum and minimum runoff are discussed and particular reference is made to the floods of 1970, and a review of demand gives particular attention to hydroelectricity and water transport.
Abstract: In relation to population Romania's water supplies are quite modest. They are provided by the rivers, which meet 89% of the present demand (48% from the Danube and 41% from the interior rivers), and by the underground sources which account for 11%. Mean specific runoff is 4.57 1/sec. km2 but there are significant variations through both space and time. The factors responsible for both maximum and minimum runoff are discussed and particular reference is made to the floods of 1970. Load and turbidity levels are also discussed. Underground water sources are described and a review of demand gives particular attention to hydroelectricity and water transport. Principles for future management of water supplies are summarised in conclusion.
11 citations
TL;DR: In this paper, the effect of PbO addition on the formation steps of the superconducting phases in the system Bi2O3−SrO−CaO−CuO was investigated.
Abstract: In order to clarify the effect of PbO addition on the formation steps of the superconducting phases in the system Bi2O3−SrO−CaO−CuO, a study of solid-state reactions under non-isothermal conditions, in the PbO−MO (M=Ca, Sr, Ca+Sr) system has been carried out.
TL;DR: In this article, the enthalpies of formation and atomization for the three compounds were derived and the experimental values of the atomization in the solid state were compared with those calculated using the Allen-Skinner bond energy scheme (for the liquid state).
TL;DR: In this article, the authors studied the question of integral points on affine open subsets of Abelian varieties over function fields of characteristic zero and obtained a boundedness result for the local height associated to a subvariety of an abelian variety defined over a discrete valuation field with residue characteristic zero.
Abstract: This paper studies the question of integral points on affine open subsets of Abelian varieties over function fields of characteristic zero. Siegel [Sie] has shown that an affine algebraic curve of genus at least one defined over a number field, has only finitely many integral points. Lang [L] has proven an analogous result for curves defined over a function field of characteristic zero, not defined over the constant field. For higher dimensions, in the classical case of number fields, Lang has conjectured and Faltings [F] proved that for A an abelian variety over the number field K, if V is an affine open subset of A and S is a finite set of places of K, then the set of S-integral points of V is finite. Faltings has also a quantitative (but non-effective) result. Parshin [P] also obtained a result for function fields of characterisic zero, under the hypothesis that the complement of V does not contain translates of abelian subvarieties of A. In this paper, we remove this hypothesis and also obtain a quantitative result. Our main theorem is a boundedness result for the local height associated to a subvariety of an abelian variety defined over a discrete valuation field with residue characteristic zero; it is a higher dimensional analogue of a result of Manin [M] about elliptic curves. Our method is quite different from those in [M] and [P]; it is based on a differential algebraic argument from [B] plus an argument involving formal groups. Acknowledgements. The first author wishes to express his gratitude to the Humboldt Foundation for support during 1992-93 and to the University of Essen, Germany, for hospitality.
TL;DR: In this article, the one-electron acceptor sites of some X and Y zeolites and of a silica-alumina catalyst have been investigated by adsorption of a series of electron donor compounds (anthracene (An), dibenzo-p-dioxin (Dx), phenoxathiin (Phx) and phenothiazine (Pht)) which have different ionization potentials but similar molecular diameters.
TL;DR: The transition from a centrally-planned to a free market economy is part of the transition from the state to the market economy as discussed by the authors, and industrial enterprises in all parts of Europe are developing new relationships with capital, labour and the state.
Abstract: Restructuring of industry in Romania today is part of the transition from a centrally-planned to a free market economy The paper deals with salient features of socialist industry and the trends which have occurred since 1989 in the context of greatly reduced state intervention Current trends are identified as a key to further evolution in the future and some international comparisons are attempted now that industrial enterprises in all parts of Europe are developing new relationships with capital, labour and the state
TL;DR: In this paper, the plant cover should be given the protection of national park or nature reserve status, and the present designations are substantial, though not yet adequate, and careful monitoring is needed to establish the extent or further provision.
Abstract: Romania is characterised by great floristic diversity and there are many distinctive aspects to the distribution of vegetation units. However, even the sparsely-populated mountainous country has been affected by anthropic activity, increasing in intensity through the expansion of agriculture during the nineteenth century and the recent emphasis on industrial development. It is therefore essential that the diverse plant cover should be given the protection of national park or nature reserve status. The present designations are substantial, though not yet adequate, and careful monitoring is needed to establish the extent or further provision.
TL;DR: In this article, the authors examine the physical and cultural landscapes of a small Carpathian district and show how a traditional economy, which maintained much of its integrity under communism, now looks with guarded optimism towards an uncertain future.
Abstract: The privatisation of Romanian agriculture will provide new opportunities for the peasantry and even in the mountains where collectivisation remained incomplete there will be the stimulus of a free market. This article examines the physical and cultural landscapes of a small Carpathian district and shows how a traditional economy, which maintained much of its integrity under communism, now looks with guarded optimism towards an uncertain future. Agriculture remains fundamental with ecological as well as economic dimensions (for the terrain is highly unstable) but the potential for small businesses and local services, neglected in the past, must also be realised.
TL;DR: In this paper, the Kobayashi pseudodistance is defined on each complex Banach manifold using contractive analytic functions from the unit disk into the Hubert space H. The main result of the paper asserts the fact the k-pseudo-distance is a true distance on the Shmuiyan parts of B 1.
Abstract: The Kobayashi pseudodistance can be defined on each complex Banach manifold. Using contractive analytic functions from the unit disk into B(H) we can define the Kobayashi pseudodistance on the closed unit ball B 1 of B(H), where B(H) is the algebra of all bounded linear operators on the Hubert space H. The main result of the paper asserts the fact the Kobayashi pseudodistance is a true distance on the Shmuiyan parts of B 1. Some connections between Pick condition for the two-nodes Nevanlinna-Pick interpolation problem and the Kobayashi distance are established.
TL;DR: This article examined the relations between the urban and industrial hierarchies at all levels with particular emphasis on the type of industry and the administrative functions, and examined the relationship between the industrial and urban hierarchies.
Abstract: Urban and industrial hierarchies can be constructed as synthetic indicators of urbanisation and industrialisation at a particular moment in time. The beginning of 1990 is a significant time to undertake this exercise because of the collapse of the communist system and the start of a transition to a market economy. Industrialisation, the key to economic advance in general and to urbanisation in particular, is studied over four decades to bring out the concentration in large units (considered appopriate for economic efficiency) and the locational emphasis on the county (judget) administrative centres identified in 1968 ad the new territorial base for central planning. These centres, with their surrounding villages, experienced a demographic explosion. The paper examines the relations between the urban and industrial hierarchies at all levels with particular emphasis on the type of industry and the administrative functions.
23 Aug 1993
TL;DR: It is shown that the classical bisimulation equivalence on process graphs coincides with the natural extension of the classical step-bystep flowchart equivalence to the nondeterministic case.
Abstract: In a flowchart scheme an atomic action is modelled as a vertex (box), while in a process graph an atomic action is modelled as an edge. We define translations between these two graphical representations. By using these translations, we show that the classical bisimulation equivalence on process graphs coincides with the natural extension of the classical step-bystep flowchart equivalence to the nondeterministic case. This result allows us to translate axiomatisation results from flowcharts to processes and viceversa.
25 Oct 1993
TL;DR: A self-organizing neural structure with neuron relocation features that extends the topological ordering concept and the DSOFS synthesis in a pattern recognition problem is showed.
Abstract: This paper presents a self-organizing neural structure with neuron relocation features. The neural net is used in the automatic synthesis of a dynamic self-organizing fuzzy system (DSOFS). The neural relocation learning provides a way to add, adapt and/or remove the fuzzy rules and the reference fuzzy sets of the DSOFS. The neural equivalent of modifying the DSOFS rules is adding and/or disposing the neurons while learning the input-output behaviour. This algorithm extends the topological ordering concept. A basin of attraction is supposed for every neuron (fuzzy rule) as a ground for the fuzzy reference sets construction. The DSOFS synthesis in a pattern recognition problem is showed.
01 Mar 1993
TL;DR: In this article, the defect structure of the Bi3FeMo2O12 surface determined by processes frequently encountered in heterogeneous catalysis (e.g. heating-cooling cycles, adsorption and/or reaction of reactive gases with solid surfaces) can be followed either by direct in situ measurement of the AC electrical conductance, or by comparing the electrical conductances data of successive experiments on the same sample, in standard reference conditions, after various in situ treatments.
Abstract: The dynamic evolution of the defect structure of the Bi3FeMo2O12 surface determined by processes frequently encountered in heterogeneous catalysis (e.g. heating-cooling cycles, adsorption and/or reaction of reactive gases with solid surfaces) can be followed either by direct in situ measurement of the AC electrical conductance, or by comparing the electrical conductance data of successive experiments on the same sample, in standard reference conditions, after various in situ treatments.
15 Apr 1993-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The HVEC-FN type tandem accelerator of the Institute of Atomic Physics in Bucharest was twice, in 1977 and 1986, severely damaged by strong earthquakes as mentioned in this paper, and it was replaced by a new tandem accelerator.
Abstract: The HVEC-FN type tandem accelerator of the Institute of Atomic Physics in Bucharest was twice, in 1977 and 1986, severely damaged by strong earthquakes
TL;DR: In this paper, the authors provide an outline of the programme, as a contribution to the wider electrification programme, and consider the impact of these developments in the Carpathians where there is much evidence of integrated rural planning to combine electricity generation with forestry and tourism.
Abstract: Hydropower developments are of major importance for the national economy and constitute one of the most impressive symbols of modernisation in the mountains of Romania. Development dates back to the turn of the century and comprehensive surveys were carried out during the 1930s; but construction on a sustained basis has occurred only during the postwar period, involving 118 water storages and some 5700 MW of installed power, a quarter of all installed electricpower in the country. The paper provides an outline of the programme, as a contribution to the wider electrification programme, and considers the impact of these developments in the Carpathians where there is much evidence of integrated rural planning to combine electricity generation with forestry and tourism. The prospects for further development in the context of a market economy are considered in the light of both economic and ecological issues.
TL;DR: In this paper, the effect of B addition on the formation of the high-Tc phase was examined using simultaneous differential thermal analysis (DTA) and thermogravimetric analysis (TGA), X-ray powder diffraction (XRD).
01 Jan 1993
TL;DR: In this paper, a Clifford algebra technique approach for proving boundary estimates for harmonic functions in nonsmooth domains is presented, in particular for studying the Dirichlet and Neumann problems for the Laplace operator on Lipschitz domains in a unified manner.
Abstract: A Clifford algebra technique approach for proving boundary estimates for harmonic functions in nonsmooth domains is presented. In particular these estimates are used for studying the Dirichlet and Neumann problems for the Laplace operator on Lipschitz domains in a unified manner.
TL;DR: In this article, a computer program which is able to simulate adsorption on fractal surfaces was developed, which is based on a DLA-algorithm and generated as Takagi surfaces.
Abstract: A computer program which is able to simulate adsorption on fractal surfaces was developed. The fractal surfaces are generated as Takagi surfaces. The computer program is based on a DLA-algorithm. Adsorption was simulated in different conditions: 1. equivalent active sites (homogeneous surfaces); 2. active sites with different adsorption probabilities; the probability associated with every active site is computed using a van der Waals potential. Our simulation allows us to explore the actual structure of the gas-solid interface and to study the sensitivity to energetic disorder. The fractal dimension of gas-solid interface vs. adsorption coverage curves are computed.