NEW SEMICONDUCTOR MATERIALS AND HETEROSTRUCTURES
FOR TUNABLE IR LASERS
Davarashvili O.I., Enukashvili M.I., Kekelidze N.P., Kochoradze G.I., Metskhvarishvili M.R., Emekly N. and Yarat A.
Iv. Javakhishvili Tbilisi State University
Marmara University, Istanbul, Turkey
The investigation of heterostructures in the system of the IV-VI semiconductors carried out by the authors has shown that a significant factor increasing the threshold current in the lasers based on isolattice- parameter structures is diffusion of the components through a heterojunction that causes formation of a mismatched layer in the active region. Corresponding elastic strains can reach the limiting values, i.e. the relaxation. As a result, the centers of nonradiative recombination are formed. In order to achieve pulsed and continuous wave mode operation of tunable IR lasers at the temperature of coding modules (~250 K) and room temperature, new semiconductor materials PbCaSrSeTe and Pb1-ySnxSe1-yTey (0£ õ£ 0.16, 0£ ó£ 0.9) doped with Ca, Sr, Sb and heterostructures on their basis are proposed. These structures are distinguished by a high heterobarrier, a specific profile of distribution of fast-diffusive components along the heterojunction and broadening of the range of elastic deformation of the laser active region.
Keywords: IR lasers, multicomponent solid solutions, lattice constant, mismatch of layers, threshold current, diffusion, elastic properties.
A new investigation of Hallen's integral equation with the usage of the method of generalized δ-like functions is presented. This equation was transformed into the second-kind Fredholm equation with a symmetric kernel. Its eigenfunctions and eigenvalues were determined. As a result, the solution to the Hallen's equation in a closed form was found basing on Hilbert-Schmidt theory. It was established that, only in the resonance case h=nλ( h- the dipole length, λ- the wavelength, n= 1,2,3…), the surface (axial) current distribution of the dipole is of a sine character. A precise value of the mentioned current amplitude was determined. In non-resonance cases (h?nλ), the axial current distribution significantly differs from the sine one.
Keywords: antenna, symmetric dipole, Hallen's integral equation.
It is shown that the performed technological, physical-mechanical and radiation tests clearly indicate the prospects of using Neutron Absorbing Elements (NAE) based on B-10 and some rare-earth compounds in designing the highly effective Control and Safety System (CSS) rods for fast neutron nuclear-power reactors. Particular attention was paid to the development of new and upgrading items of existing computation models and real technologies for designing and preparing the optimizing NAE items characterized by all physical and strength properties for obtaining desirable operational parameters of CSS rods on their base.
Keywords: fast reactor, control and safety rod, absorbing element.
The necessity in developing of models and technologies for molecular mixture preparation has arisen in the connection with an increasing needs of fine-dispersion waterfueling emulsions used as fuel for engines of internal combustion, gas turbines and plant boiler. The presented work deals with mixing processes and novel equipment based on the developed analytical approaches and modern device design which permits to obtain steady mixtures based on the substances of different chemical nature. The described model and technology based on precise turbulization and mixing processes provide high quality of the prepared emulsion. The mixer machine, the main part of which includes a cylindrical body with a central pipe and two opposite vertical pipes, and a turbulencer of the internal pipe,allows to fulfilling this task. This construction performs the preparation of molecular mixtures - high quality emulsions containing the liquids with different properties.
Keywords: molecular mixture, preparation, turbulence, liquid.
The effect of preliminary deformation - high-temperature thermo-mechanical treatment (HTMT) - on the mechanism of phase transformations at ductile iron austempering is investigated. The effects of deformation and thermal conditions on the character of ductile iron structure transformation were evaluated by metallographic analyses, TEM, X-ray and mechanical testing. The deformed state of cast iron was obtained by stamping or extrusion of the samples at 900-950° C with different degrees of deformation. It was established that sequential deformation and austempering of ductile cast irons are efficient for controlling their structure characteristics and, consequently, their properties. The investigated low-silicon ductile irons are a new class of materials, which can sequentially be exposed to hot plastic deformation and isothermal hardening.
Keywords: ductile iron (ADI), austempering, deformation, bainite, phase transformation.
The paper is related to the methods of determining the Earth crust structures by processing the earthquake epicenters distribution. As it is known, errors in determination of the epicenters are inevitable. As a result, the earthquakes distribution pattern is inaccurate. Unlike the calculation methods proposed earlier by other authors, instead of "moving" hypocenters, here was made an attempt to calculate a general pattern basing on the epicenter determination error ellipsoid. As a result, a "probabilistic density" pattern has been obtained. The basic aim of the work was to develop the algorithm for calculation and mapping. It should be noted that the work was carried out in ArcView environment, which allows 3D mapping and calculating.
Keywords: earthquake, epicenter distribution, probabilistic density, calculation.
A general analytical expression for calculation of the energetic spectrum of a linear code with mBIC insertions for any value of m have been derived. The obtained expressions allow one to calculate continuous and discrete components of the energetic spectrum for all possible values of the probability of occurrence of P(1) and P(0) in the initial linear code.
Keywords: fiber-optics transmission system, energetic spectrum, code with insertions, matrix.
The expressons for calculation of continuous and discrete spectra of linear block alphabetic code 3B4B have been derived. These expressinions allow one to calculate the energetic specrum for all values of the probability of occurence of P(1) and P(0) on the initial linear code.
Keywords: fiber-optics transmission system, energetic spectrum, linear block code, matrix.
The task of finding unknown dependence parameters between the two measured values is considered. In order to extend the field of solving the problem, cubical periodical interpolated spline functions are used. The use of these functions considerably simplifies the computation process.
Keywords: unknown parameters, spline functions, functional dependence, parameters definition.
The properties of second-order symmetric central composition designs, related to the precision of evaluation of regression equation factors, have been investigated. Among the criteria considered, there is D-, A-, E-optimality, orthogonality, dispersion of parameter estimations, etc. For each criterion, the optimum value of the "star" branch, that provides the best properties of the design from the standpoint of this or that criterion, was determined.
The character of changes in the design properties with adding 1-7 points in the design center is described.
Keywords: experiment designing, symmetric composition designs.
A generalized calculation eauation for the magnetic field energy of two inductively coupled circuits with consideration of the Lenz law of electromagnetic inertia is suggested.
Keywords: magnetic field, energy, inductively coupled circuits, coil, aiding connection, connection in opposition.
Basing on the improved magnetic sensor of direct controlling the suspended vessel movement, a positional system for controlling the electric drive of jig-back aerial tramways with intermediate supports has been developed. The system provides movement of the electric drive according the optimal tachogram and displacement of suspended vessels according to the optimal speed diagram en route. The developed positional system is characterized by high precision of controlling the suspended vessel and ensures an increase in the dynamic indexes of the electric drive of jig-back aerial tramways with intermediate supports under maximum capacity conditions.
Keywords: electric drive, jig-back aerial tramway, digital-analog system, control.
A new approach to designing the tea leaves collecting system based on the methods of cybernetics is suggested. There were preferred the solutions based on statistical characteristics of a tea bush such as the sprout height, the number of leaves on the sprout, the relation between the length of the portion from the sprout top to the cutting place and the sprout height etc. The task of optimal collection was stated. According to it, the levels of location of a selecting roller and a cutting tool at the specified minimum portion of a delicate fraction and permissible losses were determined. To solve the problem, software Matlab 5.x was used. Possible solutions and areas of these solutions are shown.
Keywords: tea leaves collection, mathematical model, statistical characteristics, optimization problem, solution area.
For determination of optimal conditions of operation of the robotic system for selective collection of tea leaves, a simulation programme Polygon was composed. The programme allows one to carry out various operations in laboratory under the conditions similar to those in field. The programme is based on the database of sprout images and statistical characteristics of the raw material layer of a tea bush. The programme constructs a probability-statistical model of the sequence of sprouts passing through the system of technical vision, which does not actually differ from a real pattern, and allows one to determine optimal conditions of the tea-collecting system.
Keywords: tea leaves collection, simulation programme, optimal conditions.
The state of the art of metrological provision of the ion activity measurement is considered. It is noted that rigorous metrological determination of pH is limited by temperature of 100° C though, in the field of pH standardization, good results have been achieved. Measurement of other ions is less provided with metrological tools. There are considered some possibilities of metrological provision: calibration graphs, analytical relations, table forms, procedures related to the measurement of separate ion activity etc.
Keywords: ion activity, metrological provision, state of art.
The results of investigation of nemato-chiral thermoindicator films are presented. The films were obtained on the base of a nemato-chiral mixture (84% p-buthoxy-benzilidene-p'-n-buthylaniline with 16% tigogenin caprate). The produced films are characterized by high photochemical stability as distinguished from the films consisting of the mixture of cholesterol esters.
Keywords: nemato-chiral polymer film, photochemical stability, dyeing intensity.
The interchange diffuse process in a segment cylinder is examined. The process model was constructed by a difference scheme. It is shown that inhomogenous gradient layer formation is caused by a delay effect.
Keywords: isorefraction, inhomogeneous gradient layer, difference scheme, delay effect.
Cometathesis reactions of cycloolefins with a -olefins were studied. On the basis of the olefin metathesis reaction, new technologically effective methods of synthesis of a sex feromone of Archips podana and a plant growth stimulator - triacontanol were developed. It is shown that, choosing cycloolefins and a -alkens of the desired length, it is possible to obtain alcohols of a certain length with both odd and even numbers of carbon atoms.
Keywords: feromone, triacontanol, metathesis, olefins.
Lactose transformation under the lead hydroxide effect in nitrogen atmosphere was studied. Lead salt of 4-0-[b -D-galactopyranozyl]-a -D-glucosaccharinic acid was obtained. Then the derivative acids were produced. The mechanism of lactose restructuring and the pattern of active complex formation was established. Electronic density at atoms and bonds in the active complex was determined by quantum chemistry methods. The results justified the established mechanism.
Keywords: isomerization, disaccharides, lactose, restructuring mechanism, active complex, lead hydroxide, electronic density.
Lobesia botrana is the main pest of vine and table grapes in Georgia. The basic component of this pheromone is Z,E-7,9-dodecadien-1-yl-acetate. A polar solvent - dimethylsulfoxide was used instead of liquid ammonia in the scheme of synthesis at the step of combination. A new preparative form of this pheromone – a pill dispenser which has more prolonging properties than rubber ones, was developed on the basis of natural aluminosilicate – clinoptilolite.
Keywords: pheromone, pest, preparative forms, pill dispensers, prolonging properties.
Some geometrical, electronic and thermodynamic characteristics of Fisher's bases and their analogues were studied by semiempirical quantum-chemical method MINDO/3. It was established that the factors which increase the basicity of the compounds of that type shift spirochromene equilibrium towards the coloured form. Accordingly, the electron-acceptor groups which decrease the basicity of these compounds enhance the stability of the coloured form of spirochromene.
Keywords: Fisher's bases, analogues, electronic structure, properties.
There have been investigated glasses of the Na2O-MnO-SiO2 system, which are the basis of the majority of multicomponent glasses and glass materials produced from manganese-containing wastes of mining and processing industries. There was studied the phase composition of crystallization products, the density, refraction index and thermal expansion of the glasses of two series, containing 60 and 50 mol % SiO2. The effect of the composition on the properties of the mentioned glasses allows us to represent the manganese they contain in the forms of Mn2+ and Mn4+ , which have different functions and predetermine the possibility of differential structure formation.
Keywords: manganese-containing glasses, properties, structure.
The electroconductivity in glasses of the system CdO-CuO-B2O3 have been studied. It is shown that, at interchanges of Cu into Cd and MnO into CuO there is observed an effect silmilar to the mixed alkali and polyanionic effects of electrocounductivity, that is related to the change in the donor type and/or electron acceptors.
Keywords: electroconductivity, glasses, system CdO-CuO-B2O3 , interchange.
The results of investigation on the possibility of application of the sludge of electrolytic manganese dioxide production as microfertilizer are presented. X-ray phase and petrographic analyses and petrochemical calculation showed that, in the sludge, there are present watercontaining calcium and manganese sulfates, vad-type compounds MnO2× MnO× nH2O, feldspars and quartz. The obtained data justify the possibility of application of the investigated sludge as manganese-containing microfertilizer.
Keywords: manganese dioxide, sludge, microfertilizer, application.
A principle of functions distribution among leg joints of a six-legged robot designed by the compositional concept is presented. The principle consists in the following: for efficient control of this or that pacing parameter, there should be determined the joint for which a maximum absolute value of the partial derivative of this pacing parameter is achieved along the given joint axis. The value intervals of the joint axes, within which the maximum absolute values of partial derivatives are maintained are detrmined.
Keywords: six-legged robot, joints, pacing, functions.
The principles of designing the on-line system of digital aerophotography are considered. The problems of designing the complex of optical devices for aerophotography of the Earth surface including an independent optical coordinator and an optical device for digital aerophotography using photoreceivers based on the instruments with a charged bond have been investigated.
Keywords: digital aerophotography, on-line system, designing.
The problems of investigation of digital methods of processing the radiolocation signals and images and of development of the digital computerized complex for this purpose are considered. The results of experimental studies are presented.
Keywords: radiolocation, signals, images, digital processing.
Types of expert systems and their classification according to the goals and target problems of water supply are presented. There is considered a structural model of the expert system for detection of water pollution at the outlet of the water supply system. The series of logic elements, the database and the logic reasoning for making decisions etc. used in the described expert system are explained.
Keywords: water supply system, water pollution control, expert system.
A model of the flow distribution process in water supply engineering networks is described. The model is based on the principle of self-regulation of flows in accordance with the established process of water supply. Graphical interpretation of the described model is presented. The experimental results of examination of the local water supply network in the city of Tbilisi have shown good agreement with the calculated data.
Keywords: water supply network, flow distribution, simulation, model.
A system of measures and actions (general tasks) for ensuring the ecological safety of potable water sources is suggested. The structural-functional scheme of this system is presented. On its base, it is possible to fulfil scientific, methodological, standardization and legal measures for determination of the ecological safety regime and keeping it at the desired level.
Keywords: ecological safety, potable water source, system of safety measures.
The models for determination of safety indexes of the sanitary-epidemic state of potable water sources have been developed. These models are recommended for application by municipal sanitation services for rapid analysis of potable water and determination of the pollution level of the potable water sources.
Keywords: potable water, safety indexes, sanitary-epidemic state, model.
A new construction of a wasteway head with additional capabilities is suggested. The principal design of the bank wasteway head and the mechanism of its operation are described. This wasteway construction was finally adopted when designing Khudafedin Waterworks on the River Araks (Azerbaijan) and the waterworks on the River Olga (Russia).
Keywords: waterworks, bank wasteway, head, construction.
The study offers the methods of determination of snare -interceptors in case of damage explosion of the main pipeline. The methods are based on application of a spline function and are suitable for both designed and operating pipelines.
Keywords: oil pipeline, damage, snare-interceptors, methodology.
An attempt of the qualitative analysis of the main oil pipeline influence on the environment is described. The concepts of local and integral risk-factors are introduced and the method of their quantitative estimation is suggested.
Keywords: oil pipeline, ecology, risk-factor, estimation.
Meat productivity of different rabbit breeds, their crosses and hybrids with wild individuals has been studied in increasing dynamics. The generality for all the groups has been revealed, namely that the meat productivity increases with age. The crosses and hybrids are superior to purebred species in basic indexes of the meat productivity.
Keywords: rabbits, meat productivity, breed crossing, hybridization.
Inheritance of hair colour by progeny at crossing and hybridization in rabbits has been studied. When estimating the combination of different gametes, Pennet's method was used. When crossing Gray Giant and European rabbits, the progeny had protective colouration (Aguti colour) by a genotype. The first crossing and three-way crossing hybrids had the same colour. When crossing Georgian meat and fur-producing rabbits with Soviet Shinshila, the progeny had an iron grey colour.
Keywords: rabbits, crossing, hybridization, hair colour, genotype.
The photoelectric converter of the electromagnetic energetic-informational flow, which performs a complex function of an energetic-informational converter in the process of photosynthesis, is considered. That allows a plant to accumulate energy and structural information in organic structures as in a combined accumulator of energy and memory. This phenomenon can be observed by the rhythms of biopotentials in darkness, as a result of remembering the previous rhythms of light irritation. According to this fact, the energy and information play a vitally important role both in the evolution of flora and of every living being on the Earth. Here, it is suggested to supplement the existing classification of natural energy photoconverters by the third type - a combined energetic - informational converter.
Keywords: natural photoconverters, energy, information, evolution, classification.
Here are presented the laws of the following transitions in the knowledge of natural systems:
Keywords: correlation, program control, management, Galaxy, Solar System, Sun, Earth Biosphere.
The problems of ensuring the economical security of Georgia are considered. One of the basic guarantees of this is the struggle against corruption. The state of art is described, historical parallels are drawn. The threats to the country's economical security from the corruption are analyzed. Effective measures for struggling against corruption are suggested. General principles of the Bill on Establishment of the Special Anticorruption Service presented by the author earlier are stated.
Keywords: economical security, state, struggle against corruption.
An ancient method of gold extraction in Colkhida, the region of Georgia, is described. This method was reflected in the ancient myths about the Golden Fleece and Argonauts. Fast flow and waving through narrow canyons of gold-carrying mountain rivers of Colkhida prevented them from forming gold deposits in their upper flow. Therefore, the Colkhs extracted gold directly from the rivers using a sheep's fleece. Due to roughness of its hairs, wool has high capability of trapping gold particles. That fact provided for application of the wool at modern gold extraction plants, but in the form of a soft coating, made of rough cloth or felt, in sluice boxes.
Keywords: gold extraction, ancient method, historical aspect.
On the basis of scientific literature and archival materials of the middle of the XIX century, the facts of application of P.R. Bagrationi's galvanic cell were discovered. It was established that the cell had been used for various purposes for about 40 years. It was employed in military explosion devices, for power supply of the first electromagnetic telegraph St. Petersburg - Tsarskoe Selo (Tsar's Village), for galvanic works at M. Leichtenberg's Plant, and in various public and private laboratories.
Keywords: galvanic cell, Bagrationi, application, historical aspect.
An optical-fiber light commutator based on chalcogenide glass fiber is described. The commutator contains an optical-fiber head attached to the plane of light sources. The device can be used to produce light effects.
Keywords: optical fiber, chalcogenide glass, light commutator.
In the context of quantum chemistry (the AM1 method) and algebraic chemistry (the quasi-ANB-matrices method), theoretical study of the processes of transformation of succinic acid into fumaric acid and of fumaric acid into malic acid was carried out.
Keywords: succinic acid, fumaric acid, malic acid, AM1 method, quasi-ANB-matrices method.
There were prepared insecticide-repellent compositions containing natural components: eugenol, isoeugenol, citronellol, geraniol, limonene, turpentine, eucalyptus oil, etc. The compositions also contain such synthesized substances as methyl cyclopentanone, dimethyl phthalate, dibutyl phthalate, dimethyl phthalate amide and neopynamine. The preparations were produced in the form of a smoke cord and tablets with natural aluminosilicates, and of minced garlic with aluminosilicate fillings. The tablets were applied to undriable glue spread on a tree.
Keywords: insecticide-repellent compositions, natural components, aminosilicates, methyl cyclopentanone, dibutyl phthalate, amide, neopynamine.
Efficient preparative forms from synthesized carbamates and other biologically active substances were produced on the basis of mineral resources (zeolites, clays) of Georgia. It was established that the efficiency of hydrophilic powder is higher as compared with powder and microgranulated forms.
Keywords: insecticide, preparative forms, biologically active substances.
Here is offered a high-octane composition for automobile petrol. The composition was prepared on the basis of xylidines (a fraction of rocket propellant TG-02 Samin) and dried technical alcohols of the C2-C6 composition.
Keywords: high-octane composition, petrol, xylidines, dried alcohols, roket propellant.
Phytohormones in wine materials of some Georgian wines were studied by thin-layer chromatography. As a result, the following phytohormones were identified: cytocrylic, indole-acetic, hiberellic, abscisic acids and cytokinin. The investigation results showed that the phytohormone content in various wines differs a lot both quantitatively and qualitatively.
Keywords: Georgian wines, phytohormones, identification, chromatography.
The history of discovering the mineral "Bagrationite" is described. P.R. Bagrationi, a prominent chemist, expressed a deep interest in mineralogy and gathered a rather impressive collection of minerals. One of the samples which he had found in a mine in the Urals appeared to be a new mineral specimen, that was proved by mineralogical investigation. The mineral was called "Bagrationite" in honour of the discoverer.
Keywords: mineral, Bagrationite, discovery, history.