Home – Home – Jornals – Contemporary Problems of Ecology 2012 number 2

A method of constructing optimal mask differentiating filters minimizing the level of the root-mean-square or systematic error of estimation of the anisotropic structure orientation observed in the presence of additive white noise is proposed. Results of a comparative analysis of the accuracy of gradient algorithms are presented. It is demonstrated that the use of optimal differentiating filters substantially increases the accuracy of the orientation estimation algorithm.

A class of wavelet filtration algorithms with two-parameter threshold functions is considered. An algorithm is proposed for solving the problem of choosing two threshold values, which allows estimating their optimal values with acceptable accuracy.

The use of the algorithm of real-time determination of local displacements of fragments (blocks) with due allowance for spatial and temporal coupling of motion is proposed for estimating the background component during detecting small-size dynamic objects (in the case of unknown motion of the observation system). The efficiency of this method is compared with that of the methods based on affine transformations of the image as a whole. It is demonstrated that this method is more efficient and ensures background suppression in the difference frame under the condition that it is presented by large zones deforming or displacing relative to each other.

For information generated by an unknown memoryless source, a compression method using nonequivalent symbols is proposed and its optimality is proved.

A possibility of using nonparametric algorithms of pattern recognition in the problem of comparing empirical and theoretical distribution functions of random variables is considered. Results of computational experiments are analyzed.

A method that ensures superresolution in terms of angular coordinates in surveillance systems with a flat antenna array during synthesis of radio-location and radio-thermal-location images of the Earth surface with the help of an airborne station in the real beam mode is proposed. This method is based on reconstruction of reflection and emission fields.

The problem of constructing linear regression models in the presence of errors in input and output data is considered. A statistical test for detecting measurement errors in input data is proposed that does not require a preliminary consistent estimation of the coefficients under the assumption of the presence of errors. The test is validated by Monte-Carlo statistical simulation.

A continuous ant colony algorithm is first proposed to identify fuzzy systems. It is used to construct five fuzzy systems to approximate nonlinear functions of one, two, and three variables. The effect of algorithm parameters on the approximation error is studied. A comparative analysis with other identification algorithms showed an advantage of the proposed algorithm.

Algorithms were developed for the tomographic reconstruction of structure from microscopic images using graphics processors of general application. The effect of noise and the choice of reconstruction filters for tomographic problems in materials science is investigated. It is shown that the use of ρ-filtration in reconstruction allows one to estimate the geometrical characteristics of threedimensional microstructures in amorphous metal alloys.

One possible variant of solving the problem of guidance of an autonomous unmanned underwater vehicle to a given target is considered. At large distances, navigation is based on measuring the time of propagation of acoustic signals. Short-range positioning is ensured by processing images taken by an optical camera. PID control is applied as an algorithm controlling the vehicle position and attitude in space. The proposed algorithm is implemented as a computer code and tested in a series of numerical experiments.

An optical method for measuring the geometric radius and velocity of slip of a wheel rolling on a rail is discussed.

This paper presents the results of experimental studies of staring infrared photodetector arrays (PDAs) designed for use in object recognition systems. A special bench was developed to determine the threshold sensitivity of PDAs to spot irradiation, i.e., the minimum excess of the signal power over the background with allowance for the measuring path and its performance. Estimations were made of the root-mean-square (RMS) noise of the PDA element which determines the detection threshold of the excess of the radiation power of an object over the background in the plane of the entrance pupil.

The use of a diffractive optical element (DOE) in the optical scheme of a laser illuminator of a shooting simulator exposing the target is studied. It is proposed to use the DOE in the optical projection system to form a laser beam with a special intensity profile. The use of the DOE with binary amplitude transmission allows simplification of the manufacture of this block with simultaneous improvement of its performance. The DOE is used as a diffraction attenuator of laser radiation with a period of 2.5 µm and a minimum bandwidth of about 0.8 µm. Results of an experimental study of the laser radiation distribution generated using the DOE and its comparison with distribution of radiation obtained in the usual way are presented.

A method for controlling the asymmetry sign of the spectral intensity of light reflected from a narrow-band filter by fitting the dielectric layer thickness adjacent to the thin metal layer is proposed.

The geometry of anisotropic light diffraction in ultrasound waves excited by a multi-element converter in an optically uniaxial negative crystal of lithium niobate is analyzed. An expression for the refractive index of a diffracted wave was found on the basis of a study of the optical indicatrices of the refractive indices of ordinary and extraordinary light waves in the crystal. A method for calculating the angular frequency characteristics of anisotropic acousto-optic Bragg cells with multi-element converters is proposed.

Two copper mirrors with different surface roughness are studied by means of spectroscopic ellipsometry. It is established that spectral dependences of optical conductivity are qualitatively similar, but shifted along the ordinate, and some of their peaks may be related to light absorption by the surface oxide layer.

Gallium arsenide ion-doped field-effect transistors with a Schottky barrier and various doping profiles are modeled. Dependences of static transistor characteristics on doping profile parameters are calculated and analyzed. The physical processes that determine the transistor characteristics with variation in doping profile parameters are studied.

Polymorphism of the main morphological characteristics used in species diagnostics was studied at the northern limits of Siberian spruce (Picea obovata Ledeb.) habitation. The analysis of population structure was performed. The results were compared with the characteristics of spruces from the central regions of the area. The data obtained permit making the conclusions about population structure and a pattern of Siberian spruce variation within the area.

Reconstruction of the dynаmics of the range of Artemisia genus was carried out with the help of palynoareological method on the basis of the data of 97 pollen diagrams from the territory of West Siberia and the Altay-Sayan mountainous region over the millennial time sections since the Late Glacial time till the present time. It was revealed that the maximal spread of the absinthe steppe communities (probably of the cryoarid pattern) occurred at the territory under examination 13-10 thousand years ago. After the time point of 9 thousand years ago, a fundamental change of the landscapes of West Siberia occurred, which resulted in the decomposition of previously continuous absinthe steppe cover into separate blocks. Since 8 thousand years ago, the absinthe steppe communities of modern appearance occupied the zone of modern steppe and forest-steppe of West Siberia and Northern Kazakhstan, while over the taiga zone the absinthe communities were spread occasionally under the extrazonal conditions and as the pioneering plant groupings on affected soil. Since the time point of 4 thousand years ago till the present time, the northern boundary of the steppe zone underwent pulsing shifts to the north and back, and also broadening and narrowing of isolated steppe islands took place. At present, we observe an increase in the role of absinthe plants in the tundra zone of West Siberia and in the Altay mountains.

Morphological and anatomic features of underground bodies of 12 species of Magnoliophyta plants growing in the tundra of the Yamal peninsula are revealed. The structural attributes of roots and rhizomes used for their identification and important for understanding of adaptation of species to extreme conditions are determined.

Tree plants in ten types of forest-tundra virgin spruce phytocenoses were studied for the purpose of revealing the factors that determine their vital state.

Comparative characterization of the response physiognomical reactions (classes of chloroses, necroses and crown scarcity) of woody plants in the industrial cities Ust-Kamenogorsk and Zyryanovsk is given. The regularities were revealed in the changes of the functional state of green plantations depending on the degree of greenery planting, species composition and structure of plantations, sanitary and hygienic care, the amount of poolutants entering the atmosphere, and city scale.

The concept of equivalence classes and factor-sets, known from ensemble theory, is introduced in application to the theory and practice of botanical investigations. The properties of taxonomic, typological and gradient factor-sets and their connection with the comparative floristic and phytoindicative analysis are considered. Upsized groups of regimes for 10 ecological factors of D. N. Tsyganov's phytoindicative scales are proposed. Computer realization of processing the data on plant cover with the help of factor-sets in the integrated botanical information information system IBIS is described.

Features of progressive successions in the landscapes with different levels of anthropogenic transformation (the southeast of Belarus) are considered. The comparative analysis of succession characteristics in weakly and strongly disturbed landscapes is performed. It is established that succession in strongly disturbed landscape differs by the slower speed of changes of the vegetation and essential delay at early stages (including initial stages). Strongly disturbed landscapes are characterized by the high degree of synanthropization and a significant level of invasion at all the stages of succession.

N,N,N′,N′-tetramethylethylenediamine is obtained by the reaction of ethylenediamine with formaldehyde and formic acid (the Eschweiler-Clarke reaction) and then alkylated with allyl chloride (or bromide) in a ratio of 1:1 or 1:2 to obtain N-allyl-N,N,N′,N′-tetramethylethylenediaminium and N,N′-diallyl-N,N,N′,N′-tetramethylethylenediaminium bromide respectively. [{C₂H₄N₂(H⁺)(CH₃)₄(C₃H₅)}Cu₄Cl₆] (1) and [{C₂H₄N₂(CH₃)₄(C₃H₅)₂}_0.5Cu₂Cl_1.67Br_1.33] (2) π-complexes are obtained from alcohol solutions containing an ethylenediamine derivative and copper(II) chloride by ac-electrochemical synthesis on copper wire electrodes. An XRD study of the complexes is carried out. The crystals are monoclinic; 1: P2₁/n space group, a = 9.0081(6) Å, b = 12.5608(7) Å, c = 16.8610(10) Å, β = 102.061(3)°, V = 1865.7(2) ų, Z = 4; 2: С2/с space group, a = 14.462(2) Å, b = 12.519(1) Å, c = 12.762(2) Å, β = 107.861(5)°, V = 2199.1(4) ų, Z = 8. The structure of 1 consists of infinite copper halide networks with four crystallographically independent copper atoms, one of which coordinates the double bond of the allyl group of the ligand. The [C₂H₄N₂(H)(CH₃)₄(C₃H₅)]²⁺ cations are attached above and below the plane of the network. The individual fragments are bonded via an extensive system of (N)H…Cl and (C)H…Cl hydrogen bonds. The structure of 2 contains a three-dimensional copper halide framework whose cavities contain the [C₂H₄N₂(CH₃)₄(C₃H₅)₂]²⁺ cations that are π-coordinated with copper(I) atoms. In both structures, the Cu(I) atom that coordinates the С=С bond has a trigonal-pyramidal coordination environment consisting of the double С=С bond of the corresponding ligand and three halogen atoms. The other Cu(I) atoms have a tetrahedral environment consisting solely of halogen atoms. The Cu-(C=C) distance is 1.958(1) Å (1) and 1.974(1) Å (2).

The crystal structures of compounds of the composition [Rh(H₂O)₆]₂(SO₄)₃·5H₂O (I) and [Rh(H₂O)₆]PO₄ (II) are determined. Crystallographic data for I: a = 7.272(9) Å, b = 27.047(1) Å, c = 12.464(9) Å, β = 97.038(10)°, P2₁ space group, Z = 4, d_x = 2.184 g/cm³; for II: a = 9.746(6) Å, b = 6.877(7) Å, c = 23.623(6) Å, β = 100.601(10)°, C2/c space group, Z = 8, d_x = 2.611 g/cm³. Compounds are analyzed by IR spectroscopy and powder XRD. Crystalline phase I is well soluble in water, whereas II is almost insoluble.

The structures of three novel octahedral rhenium cluster compounds [Re₆S₈(CN)₂(py)₄]·H₂O (1), [Re₆S₈(CN)₂(4-Mepy)₄] (2), [Re₆S₈(CN)₂(4-Mepy)₄]·4-Mepy (3) (py = pyridine, 4-Mepy = 4-methylpyridine) are determined by X-ray crystallography. Crystal data are: C2/m space group, a = 14.813(1) Å, b = 14.772(1) Å, с = 9.2122(6) Å, β = 119.085(2)°, V = 1761.7(2) ų, d_x = 3.318 g/cm³, R = 0.0585 (1); I4₁/amd space group, a = 16.0018(3) Å, c = 14.7186(5) Å, V = 3768.81(16) ų, d_x = 3.169 g/cm³, R = 0.0489 (2); P2₁/c space group, a = 9.0452(4) Å, b = 15.8065(7) Å, c = 15.2951(6) Å, β = 103.700(2)°, V = 2124.57(16) ų, d_x = 2.957 g/cm³, R = 0.0245 (3). Molecular cluster complexes interact via π-π stacking affording 3D frameworks in 1 and 2 and chains in 3.

The crystal structures of [CuL](NO₃)(ReO₄) and [CuL](ReO₄)₂ (L is 4,6,6-trimethyl-1,9-diamino-3,7-diazanon-3-en) are studied. The square coordination of the copper atom in [CuL](NO₃)(ReO₄) is completed to a distorted octahedron by two oxygen atoms: Cu…O 2.393 Å and Cu…O 2.685 Å, and that in [CuL](ReO₄)₂, by Cu…O 2.468 Å and 2.697 Å. The products of thermolysis of the salts in a hydrogen atmosphere at 800°C are mixtures of nanocrystalline metal powders with coherent scattering regions of ~45 nm.

The reaction products of 8-allylthioquinoline with mercury halides are studied by single crystal X-ray diffraction. It is shown that the products are organomercury derivatives of salts of 2,3-dihydro[1,4]-thiazino[2,3,4-ij]quinoliniuim

Two mercury(II) cyanide complexes of N-ethylthiourea (Ettu) and N-propylthiourea (Prtu) ligands, [Hg(Ettu)₂(CN)₂] (1) and [Hg(Prtu)₂(CN)₂] (2), were prepared and their crystal structures were determined by X-ray crystallography. In both structures, the mercury atom is coordinated to two sulfur atoms of thioureas and two cyanide carbon atoms in a pseudo-tetrahedral mode with the bond angles in the range of 90.52(11)-162.2(3)°. The structures are stabilized by N-H---S, N-H---N, and C-H---N intramolecular and intermolecular hydrogen bonds.

The structural study of two (C₃₀H₄₈O₂) pentacyclic triterpene (PCTT) isomers is presented. These terpenes, known as 30-hydroxy-lup-20(29)-en-3-one (1) and (11α)-11-hydroxy-lup-20(29)-en-3-one (2), were isolated from Maytenus imbricata Mart. Ex Reissek (Celastraceae). The molecular structure of 1 and 2 differs in the position of the hydroxyl group. Both compounds crystallize in non-centrosymmetric space groups with two molecules in the asymmetric unit. The crystal structure of 1 shows a triclinic P1 space group (a = 9.5518(1) Å, b = 9.7083(1) Å, c = 14.4696(2) Å, α = 93.832(1)°, β = 102.833(1)° and γ = 103.307(1)°), while compound 2 crystallizes in a monoclinic P2₁ one (a = 13.4439(16) Å, b = 14.4463(14) Å, c = 13.5224(9) Å and β = 99.703(8)°). The two molecules independent by symmetry of 1 differ slightly due to the presence of static disorder in oxygen atoms. In addition, the intermolecular geometries of 1 and 2 were analysed, and in each isomer the crystal packing is stabilized by O-H⋯O intermolecular hydrogen bonds and van der Waals forces.

Mass spectra of 5-substituted N(3)-acyl-4,6-diaryl-3,4-dihydropyrimidin-2(1H)-ones are studied. The features of the dissociative ionization of their molecular ions, which occurs with ketene elimination from the acyl group, are revealed. The subsequent fragmentation of fragment ions proceeds according to the rules established for pyrimidin-2(1H)-one derivatives.

Literature data on the apparent molar volumes φ of alanine in water and aqueous urea solutions at 298 K are analyzed. It is shown that the slope of the φ dependence on the alanine concentration is not dependent on the urea concentration. The standard partial volume of alanine increases linearly with the increase in the urea concentration (wt.%). The structural characteristics of hydrated complexes of alanine (hydration number, molar volume of water inside and outside the hydration sphere, and proper volume of alanine in solution) are given. The hydration number of alanine decreases by a factor of two in passing from water to a saturated (20m) urea solution. The effects of urea additions on the hydration numbers of alanine and glycine are compared.

A new 2D metal-organic coordination polymer [Cu(trtr)₂]_n (1) (Htrtr = 3-(1,2,4-triazolyl-4-yl)-1H-1,2,4-triazole) is synthesized through the hydrothermal reaction of Cu(ClO₄)₂ with Htrtr. The crystal structure of 1 is determined by a direct method from X-ray diffraction data (Rigaku Mercury CCD, MoK_α radiation). 1 crystallizes in the monoclinic C2/c space group with unit cell parameters: a = 14.158(2) Å, b = 9.8050(14) Å, c = 11.413(3) Å, β = 127.9870(10)°, v = 1248.7(4) ų, z = 4, D_cal = 1.775 g/cm³. 1 features a 2D grid based on the propagation of 28-membered rings, which is further fabricated into a 3D supramolecular framework via the hydrogen bond linkage. The fluorescence of 1 shows a blue emission at 441 nm with a 14 nm red-shift compared to that of free Htrtr, which can be assigned to LMCT.

The crystal structure of [Ni(en)₃](ReO₄)₂ (en is ethylenediamine) is studied: a = 8.3997(2)Å, b = 15.6167(5) Å, c = 14.2406(4) Å, β = 100.378(1)°, V = 1837.46(9) ų, P2₁/c space group, Z = 4, and d_x = 2.673 g/cm³. It is shown that packing of the complex cations can be considered as single-layer pseudohexagonal. Thermal decomposition of the salt in a hydrogen atmosphere at 550°C is used to obtain a mixture of nickel with a nanocrystalline Re_0.87Ni_0.13 solid solution (a = 2.733(2) Å, c = 4.400(3) Å, Р6₃/mmc space group; CSR size is ~14 nm).

It is found that M(AmH)₂(3,5-DNB)₄·8H₂O compounds (where M(II) = Co, Ni; AmH is piperidine PipH = (C₅H₁₀NH₂)⁺ or diethylamine DaH = (C₄H₁₀NH₂)⁺ cations; 3,5-DNB = (C₇H₃N₂O₆)^- is the dinitrobenzoic acid anion) are isotypic. The structure of the Ni(PipH)₂(3,5-DNB)₄·8H₂O single crystal is studied. The crystals have a monoclinic system, P2₁/n space group, Z = 2, a = 6.7694(3) Å, b = 16.0746(6) Å, c = 23.1250(9) Å, β = 97.794(1)°, V = 2493.1(2) ų, T = 153 K. The final value R(F) = 0.0407 was obtained for 8191 independent reflections with I > 2σ(I). The structural units of the compound studied are as follows: [Ni(OH₂)₆]²⁺ complex hexaaquacation, two (PipH)⁺ cations, four (3,5-DNB)^- anions, and two molecules of water of crystallization with the structural formula [Ni(OH₂)₆](PipH)₂(3,5-DNB)₄·2H₂O. Similar compounds of Ni(II) and Co(II) are isostructural.

The crystal and molecular structure of the complex of 2-(1-silatranylmethylthio)-4,5-benzo-1,3-thiazole with СоСl₂ and MeCN (I) is determined by single crystal X-ray diffraction. The geometry of the silatranylmethyl moiety in complex I is compared to the geometry of 1-(2′-benzthiazolylthiomethyl)silatrane. Molecular packing in the crystal is analyzed.

Crystal structures of two solvates (Bu₄N)₂[Mo₆Cl₈(O₃SC₆H₄CH₃)₆]·2CH₃CN (1) and (Bu₄N)₂[Mo₆Cl₈(O₃SC₆H₄CH₃)₆]·2CH₂Cl₂ (2) are determined. Both compounds contain cluster [Mo₆Cl₈(O₃SC₆H₄CH₃)₆]^2- anions. Molybdenum atoms are coordinated with monodentate carboxylate ligands (Mo-O 2.101(3)-2.110(3) Å in 1; 2.088(7)-2.109(2) Å in 2).

Single crystal X-ray diffraction is used to determine the crystal and molecular structure of 4-trifluoro-2-[2-(4-fluorophenyl)hydrazine-1-ylidene]-1-(thiophen-2-yl)butane-1,3-dione. Crystallographic data for C₁₄H₈F₄N₂O₂S are as follows: a = 8.2723(6) Å, b = 9.3009(7) Å, c = 9.9895(7) Å; α = 79.224(2)°, β = 75.851(2)°, γ = 72.337(2)°. Triclinic crystal system, P-1 space group, d_x = 1.622 g/cm³, V = 704.83(9) ų, μ = 0.286 mm^-1, crystal size 0.30×0.20×0.20 mm, R1 = 0.0891, wR2 = 0.1989.