Sample records for pllumajandusteaduste alal uurimuste
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Allaste, Airi-Alina, 1967-
2004-01-01
Rahvusvaheliste uurimuste ESPAD käigus koguti andmeid uimastite tarvitamisega seotud käitumise kohta koolinoorte hulgas; Joon.: uimastite tarvitamine soo ja õppekeele järgi, tubakaga katsetajad ja regulaarsed suitsetajad, kanepisuitsetajad
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Ülle Voog sai alalõualiigese uuringuteks Eesti suurima stipendiumi / Kadri Bank
Bank, Kadri
2007-01-01
Tartu Ülikooli arstiteaduskonna dotsent Ülle Voog pälvis Ernst Jaaksoni mälestusfondi 200 000-kroonise stipendiumi. Ülle Voog jätkab stipendiumi toel alalõualiigeste haiguste uurimist Karolinska Instituudis Rootsis
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Lundell, Katie A; Zhang, Xinxing; Boldyrev, Alexander I; Bowen, Kit H
2017-12-22
The Al=Al double bond is elusive in chemistry. Herein we report the results obtained via combined photoelectron spectroscopy and ab initio studies of the LiAl 2 H 4 - cluster that confirm the formation of a conventional Al=Al double bond. Comprehensive searches for the most stable structures of the LiAl 2 H 4 - cluster have shown that the global minimum isomer I possesses a geometric structure which resembles that of Si 2 H 4 , demonstrating a successful example of the transmutation of Al atoms into Si atoms by electron donation. Theoretical simulations of the photoelectron spectrum discovered the coexistence of two isomers in the ion beam, including the one with the Al=Al double bond. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Coupled growth of Al-Al2Cu eutectics in Al-Cu-Ag alloys
International Nuclear Information System (INIS)
Hecht, U; Witusiewicz, V; Drevermann, A
2012-01-01
Coupled eutectic growth of Al and Al 2 Cu was investigated in univariant Al-Cu-Ag alloys during solidification with planar and cellular morphology. Experiments reveal the dynamic selection of small spacings, below the minimum undercooling spacing and show that distinct morphological features pertain to nearly isotropic or anisotropic Al-Al 2 Cu interfaces.
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Piezo-tunnel effect in Al/Al2O3/Al junctions elaborated by atomic layer deposition
Rafael, R.; Puyoo, E.; Malhaire, C.
2017-11-01
In this work, the electrical transport in Al/Al2O3/Al junctions under mechanical stress is investigated in the perspective to use them as strain sensors. The metal/insulator/metal junctions are elaborated with a low temperature process (≤200 °C) fully compatible with CMOS back-end-of-line. The conduction mechanism in the structure is found to be Fowler-Nordheim tunneling, and efforts are made to extract the relevant physical parameters. Gauge factors up to -32.5 were found in the fabricated devices under tensile stress. Finally, theoretical mechanical considerations give strong evidence that strain sensitivity in Al/Al2O3/Al structures originates not only from geometrical deformations but also from the variation of interface barrier height and/or effective electronic mass in the tunneling oxide layer.
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Production and study of mixed Al-Al2O3 thin films for passive electronic circuits
International Nuclear Information System (INIS)
Pruniaux, B.
1966-09-01
A new vacuum deposition process, named reactive evaporation, is used to realize passive thin film circuits. Using aluminium, oxidized at various steps in its vapor phase, we obtain: - Al-Al 2 O 3 cermet resistors (R □ = 10000 Ω □ , CTR 2 O 3 capacitors (C □ = 60000 pf/cm 2 , tg δ [fr
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Compactibility of Al/Al2O3 Isotropic Composite with Variation of Holding Time Sintering.
Directory of Open Access Journals (Sweden)
Eddy S Siradj
2008-11-01
Full Text Available The requirement of component with structural ability, light weight and also strength is increasing base on Metal Matrix Composites (MMCs by aluminum as matrix (AMCs. A structural ability is connected to composites compactibility which is depend on quality of interfacial bounding. Powder metallurgy is one of method to produce composite with powder mixing, compacting and sintering. Volume fractions reinforced and sintering time can influence composites compactibility. Volume fractions reinforced variable can produce different reinforcement effect. Beside that, on sintering enables the formation of new phase during sintering time. In this research, Al/Al2O3 isotropic composites are made with aluminum as matrix and alumina (Al2O3 as reinforced. Volume fraction reinforced used 10%. 20%. 30% and 40%. Sintering temperature and compaction pressure are each 600oC and 15 kN. The tests that applied are compression and metallographic test. The result that obtained is optimum compactibility of Al/Al2O3 composite reached at holding time 2 hour. During sintering, new phase can occur that is aluminum oxides (alumina, with unstable properties. The best volume fraction reinforced and holding time sintering are 40% and 2 hours.
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Synthesis of new metal-matrix Al-Al2O3-graphene composite materials
Elshina, L. A.; Muradymov, R. V.; Kvashnichev, A. G.; Vichuzhanin, D. I.; Molchanova, N. G.; Pankratov, A. A.
2017-08-01
The mechanism of formation of ceramic microparticles (alumina) and graphene in a molten aluminum matrix is studied as a function of the morphology and type of precursor particles, the temperature, and the gas atmosphere. The influence of the composition of an aluminum composite material (as a function of the concentration and size of reinforcing particles) on its mechanical and corrosion properties, melting temperature, and thermal conductivity is investigated. Hybrid metallic Al-Al2O3-graphene composite materials with up to 10 wt % alumina microparticles and 0.2 wt % graphene films, which are uniformly distributed over the metal volume and are fully wetted with aluminum, are synthesized during the chemical interaction of a salt solution containing yttria and boron carbide with molten aluminum in air. Simultaneous introduction of alumina and graphene into an aluminum matrix makes it possible to produce hybrid metallic composite materials having a unique combination of the following properties: their thermal conductivity is higher than that of aluminum, their hardness and strength are increased by two times, their relative elongation during tension is increased threefold, and their corrosion resistance is higher than that of initial aluminum by a factor of 2.5-4. We are the first to synthesize an in situ hybrid Al-Al2O3-graphene composite material having a unique combination of some characteristics. This material can be recommended as a promising material for a wide circle of electrical applications, including ultrathin wires, and as a structural material for the aerospace industry, the car industry, and the shipbuilding industry.
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Irradiation effects of 6 MeV electron on electrical properties of Al/Al2O3/n-Si MOS capacitors
International Nuclear Information System (INIS)
Laha, P.; Banerjee, I.; Bajaj, A.; Chakraborty, P.; Barhai, P.K.; Dahiwale, S.S.; Das, A.K.; Bhoraskar, V.N.; Kim, D.; Mahapatra, S.K.
2012-01-01
The influence of 6 MeV electron irradiation on the electrical properties of Al/Al 2 O 3 /n-Si metal–oxide–semiconductor (MOS) capacitors has been investigated. Using rf magnetron sputtering deposition technique, Al/Al 2 O 3 /n-Si MOS capacitors were fabricated and such twelve capacitors were divided into four groups. The first group of MOS capacitors was not irradiated with 6 MeV electrons and treated as virgin. The second group, third group and fourth group of MOS capacitors were irradiated with 6 MeV electrons at 10 kGy, 20 kGy, and 30 kGy doses, respectively, keeping the dose rate ∼1 kGy/min. The variations in crystallinity of the virgin and irradiated MOS capacitors have been compared from GIXRD (Grazing Incidence X-ray Diffraction) spectra. Thickness and in-depth elemental distributions of individual layers were performed using Secondary Ion Mass Spectrometry (SIMS). The device parameters like flat band voltage (V FB ) and interface trap density (D it ) of virgin and irradiated MOS capacitors have been calculated from C vs V and G/ω vs V curve, respectively. The electrical properties of the capacitors were investigated from the tan δ vs V graph. The device parameters were estimated using C–V and G/ω–V measurements. Poole–Frenkel coefficient (β PF ) of the MOS capacitors was determined from leakage current (I)–voltage (V) measurement. The leakage current mechanism was proposed from the β PF value. - Highlights: ► The electron irradiation effects make variation in the device parameters. ► The device parameters changes due to percentage of defects and charge trapping. ► Leakage current of Al/Al 2 O 3 /n-Si changes due to interface dangling bonds. ► The leakage current mechanism of MOS structures is due to Poole-Frenkel effect.
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International Nuclear Information System (INIS)
Watanabe, Y.; Fukui, Y.
1997-01-01
Al-Al 3 Ti functionally graded materials (FGMs) were manufactured by the centrifugal method with a commercial ingot of Al-5 mass% Ti master alloy. The alloy was melted at a liquid/solid coexisting temperature, at which Al 3 Ti remains as a solid, and then it was cast into a thick-walled ring. It was found that the Al-Al 3 Ti functionally graded material can be successfully fabricated by the centrifugal method. It was also found that the volume fraction of the Al 3 Ti can be increased by repetition of the centrifugal method. Since the shape of Al 3 Ti particles in a commercial alloy ingot is that of a platelet, the Al 3 Ti particles are arranged with their platelet planes nearly perpendicular to the radial direction. The orientation effects become stronger when the G number becomes larger. Although the final centrifugal casting was conducted under a very large centrifugal force for the specimen cast three times, the orientation effects were weaker than those in the specimen cast one time. From these observations, it is concluded that the origin of orientation of Al 3 Ti platelets can be attributed to the angular velocity gradient of the melt along the radial direction produced by the difference in the viscosity. (orig.)
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Studies on SiC(p) reinforced Al-Al sub 3 Ni eutectic matrix composites
International Nuclear Information System (INIS)
Masrom, A.K.; Foo, L.C.; Ismail, A.B.
1996-01-01
An investigation on processing of Al-5.69wt% Ni eutectic with SiC particulate composites is reported. The intermetallic composites are prepared by elemental powder metallurgy route and sintered at two different temperatures, i.e., 600 degree C and 620 degree C. Results show that the metal matrix was Al-Al sub 3 Ni eutectic. The phase analysis by XRD identified the presence of Al sub 3 Ni and Al as dominant phases together with silicon and Al sub 4 C sub 3 phase as minor phases. The Al sub 4 C sub 3 and Si phases are formed during sintering due to SiC-Al interface reaction. SEM micrographs also reveal the formation of microvoid surrounding the SiC particle
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Capacitance-voltage characterization of Al/Al2O3/PVA-PbSe MIS diode
Gawri, Isha; Sharma, Mamta; Jindal, Silky; Singh, Harpreet; Tripathi, S. K.
2018-05-01
The present paper reports the capacitance-voltage characterization of Al/Al2O3/PVA-PbSe MIS diode using chemical bath deposition method. Here anodic alumina layer prepared using electrolytic deposition method on Al substrate is used as insulating material. Using the capacitance-voltage variation at a fixed frequency, the different parameters such as Depletion layer width, Barrier height, Built-in voltage and Carrier concentration has been calculated at room temperature as well as at temperature range from 123 K to 323 K. With the increase in temperature the barrier height and depletion layer width follow a decreasing trend. Therefore, the capacitance-voltage characterization at different temperatures characterization provides strong evidence that the properties of MIS diode are primarily affected by diode parameters.
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International Nuclear Information System (INIS)
Laha, P.; Banerjee, I.; Barhai, P.K.; Das, A.K.; Bhoraskar, V.N.; Mahapatra, S.K.
2012-01-01
Highlights: ► The electron irradiation effects make variation in the device parameters. ► The device parameters changes due to percentage of defects and charge trapping. ► Leakage current of Al/Al 2 O 3 /TiO 2 /n-Si changes due to interface dangling bonds. ► The leakage current mechanism of MOS structures is due to Poole–Frenkel effect. - Abstract: The effects of 6 MeV electron irradiation on the electrical properties and device parameter characteristics of Al/Al 2 O 3 /TiO 2 /n-Si metal–oxide–semiconductor capacitors have been studied. Twelve Al/Al 2 O 3 /TiO 2 /n-Si MOS capacitors were fabricated using r.f. magnetron sputtering and divided into four groups. The first group was not irradiated and treated as virgin. The rest were irradiated with 6 MeV electrons at doses 10, 20, and 30 kGy, maintaining the dose rate at ∼1 kGy/min. Variations in crystallinity of the virgin and irradiated capacitors were studied using grazing incident X-ray diffraction. The thickness and in-depth elemental distributions of individual layers were determined using secondary ion mass apectrometry. Capacitance–voltage, conductance–voltage and leakage current–voltage characteristics of the virgin and irradiated samples were studied. The device parameters (flat band voltage, surface charge density and interface trap density of the virgin and irradiated structures) were determined. The electrical properties of the capacitors were investigated and the Poole–Frenkel coefficient of the capacitors was determined from leakage current measurements. The leakage current mechanism has been explained.
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Koberidze, M.; Puska, M. J.; Nieminen, R. M.
2018-05-01
We present a computational study of the adhesive and structural properties of the Al/Al 2O3 interfaces as building blocks of the metal-insulator-metal (MIM) tunnel devices, where electron transport is accomplished via tunneling mechanism through the sandwiched insulating barrier. The main goal of this paper is to understand, on the atomic scale, the role of the geometrical details in the formation of the tunnel barrier profiles. Initially, we concentrate on the adhesive properties of the interfaces. To provide reliable results, we carefully assess the accuracy of the traditional methods used to examine Al/Al 2O3 systems. These are the most widely employed exchange-correlation functionals—local-density approximation and two different generalized gradient approximations; the universal binding-energy relation for predicting equilibrium interfacial distances and adhesion energies; and the ideal work of separation as a measure of junction stability. In addition, we show that the established interpretation of the computed ideal work of separation might be misleading in predicting the optimal interface structures. Finally, we perform a detailed analysis of the atomic and interplanar relaxations in each junction, and identify their contributions to the tunnel barrier parameters. Our results imply that the structural irregularities on the surface of the Al film have a significant contribution to lowering the tunnel barrier height, while atomic relaxations at the interface and interplanar relaxations in Al2O3 may considerably change the width of the barrier and, thus, distort its uniformity. Both the effects may critically influence the performance of the MIM tunnel devices.
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Energy Technology Data Exchange (ETDEWEB)
Sazgar, A. [Center of Excellence in Design, Robotics and Automation, Department of Mechanical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Movahhedy, M.R., E-mail: movahhed@sharif.edu [Center of Excellence in Design, Robotics and Automation, Department of Mechanical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Mahnama, M. [School of Mechanical Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Sohrabpour, S. [Center of Excellence in Design, Robotics and Automation, Department of Mechanical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of)
2017-01-02
The interfacial behavior of composites is often simulated using a cohesive zone model (CZM). In this approach, a traction-separation (T-S) relation between the matrix and reinforcement particles, which is often obtained from experimental results, is employed. However, since the determination of this relation from experimental results is difficult, the molecular dynamics (MD) simulation may be used as a virtual environment to obtain this relation. In this study, MD simulations under the normal and shear loadings are used to obtain the interface behavior of Al/Al2O3 composite material and to derive the T-S relation. For better agreement with Al/Al2O3 interfacial behavior, the exponential form of the T-S relation suggested by Needleman [1] is modified to account for thermal effects. The MD results are employed to develop a parameterized cohesive zone model which is implemented in a finite element model of the matrix-particle interactions. Stress-strain curves obtained from simulations under different loading conditions and volume fractions show a close correlation with experimental results. Finally, by studying the effects of strain rate and volume fraction of particles in Al(6061-T6)/Al2O3 composite, an equivalent homogeneous model is introduced which can predict the overall behavior of the composite.
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Mechanical properties and deformation behavior of Al/Al7075, two-phase material
International Nuclear Information System (INIS)
Sherafat, Z.; Paydar, M.H.; Ebrahimi, R.; Sohrabi, S.
2010-01-01
In the present study, mechanical properties and deformation behavior of Al/Al7075, two-phase material were investigated. The two-phase materials were fabricated by mixing commercially pure Al powder with Al7075 chips and consolidating the mixture through hot extrusion process at 500 o C. Mechanical properties and deformation behavior of the fabricated samples were evaluated using tensile and compression tests. A scanning electron microscope was used to study the fracture surface of the samples including different amount of Al powder, after they were fractured in tensile test. The results of the tensile and compression tests showed that with decreasing the amount of Al powder, the strength increases and ductility decreases. Calculation of work hardening exponent (n) indicated that deformation behavior does not follow a regular trend. In a way that the n value was approved to be variable and a strong function of strain and Al powder wt% of the sample. The results of the fractography studies indicate that the type of fracture happened changes from completely ductile to nearly brittle by decreasing the wt% of Al powder from 90% to 40%.
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International Nuclear Information System (INIS)
Prabhu, B.; Suryanarayana, C.; An, L.; Vaidyanathan, R.
2006-01-01
Al-Al 2 O 3 metal matrix composite (MMC) powders with volume fractions of 20, 30, and 50% Al 2 O 3 were synthesized by high-energy milling of the blended component powders. The particle sizes of Al 2 O 3 studied were 50 nm, 150 nm, and 5 μm. A uniform distribution of the Al 2 O 3 reinforcement in the Al matrix was successfully obtained after milling the powders for a period of 20 h at a ball-to-powder ratio of 10:1 in a SPEX mill. The uniform distribution of Al 2 O 3 in the Al matrix was confirmed by characterizing these nanocomposite powders by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray mapping, and X-ray diffraction (XRD) techniques
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Sobczak, N.; Ksiazek, M.; Radziwill, W.; Asthana, R.; Mikulowski, B.
2004-03-01
A fresh approach has been advanced to examine in the Al/Al2O3 system the effects of temperature, alloying of Al with Ti or Sn, and Ti and Sn coatings on the substrate, on contact angles measured using a sessile-drop test, and on interface strength measured using a modified push-off test that allows shearing of solidified droplets with less than 90 deg contact angle. In the modified test, the solidified sessile-drop samples are bisected perpendicular to the drop/Al2O3 interface at the midplane of the contact circle to obtain samples that permit bond strength measurement by stress application to the flat surface of the bisected couple. The test results show that interface strength is strongly influenced by the wetting properties; low contact angles correspond to high interface strength, which also exhibits a strong temperature dependence. An increase in the wettability test temperature led to an increase in the interface strength in the low-temperature range where contact angles were large and wettability was poor. The room-temperature shear tests conducted on thermally cycled sessile-drop test specimens revealed the effect of chemically formed interfacial oxides; a weakening of the thermally cycled Al/Al2O3 interface was caused under the following conditions: (1) slow contact heating and short contact times in the wettability test, and (2) fast contact heating and longer contact times. The addition of 6 wt pct Ti or 7 wt pct Sn to Al only marginally influenced the contact angle and interfacial shear strength. However, Al2O3 substrates having thin (<1 µm) Ti coatings yielded relatively low contact angles and high bond strength, which appears to be related to the dissolution of the coating in Al and formation of a favorable interface structure.
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Microstructure evaluation of Al-Al2O3 composite produced by mechanical alloying method
International Nuclear Information System (INIS)
Zebarjad, S.M.; Sajjadi, S.A.
2006-01-01
Mechanical alloying process using ball-milling techniques, has received much attention as a powerful tool for fabrication of several advanced materials, including amorphous, quasicrystals, nanocrystalline and composite materials, etc. This research is focused on production of Al-Al 2 O 3 composite materials by mechanical alloying method and on investigation of its microstructure. For this purpose a horizontal ball mill was designed and manufactured. Aluminum and alumina powders, with specified size and weight percent, were added to the mill. The mixed powders were milled at different times. The milled powders were pressed and sintered under argon gas control. Microstructure of produced composite was investigated by scanning electron microscope. The results show that increasing milling time causes to make fine alumina powders as well as uniform distribution within aluminum, also in steady-state stage increasing milling time has not significant effect on their size distribution within aluminum. The results of atomic analysis of initial and milled powders at different times show that at the beginning of milling, the powders will tend to absorb iron and gradually their susceptibility decrease until steady-state condition is prevailed. The result of infrared spectroscopy does not show any evidence of compounds except alumina
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International Nuclear Information System (INIS)
Belov, N.A.; Khvan, A.V.
2007-01-01
The phase diagram of the Al-Cu-Ce system in the quasibinary section area of Al-Al 8 CeCu 4 has been investigated by metallographic, thermal, micro-X-ray spectral and X-ray structural analyses. The parameters of the eutectic reaction L→(Al)+CeCu 4 Al 8 : T=610 Deg C were found out; the composition was 14% Cu and 7% Ce. This eutectics is of a disperse structure and the ternary compound contained is capable of fragmentation and spheroidizing in the heating process (starting from 540 Deg C). It was demonstrated that the area of optimal (Al)+CeCu 4 Al 8 eutectics-based alloy compositions was within the narrow limits. That is related to the fact that at a comparatively little variation of the Cu:Ce=2 ratio solidus sharply decreases and, as a result, the crystallization interval considerably extends [ru
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Riigi teaduspreemiad akadeemikutele
2000-01-01
Teaduspreemiad: tehnikateaduste alal Raimund-Johannes Ubarile; humanitaarteaduste alal Arvo Krikmannile; H. Küütsile kollektiivi koosseisus põllumajandusteaduste alal; täppisteaduste alal Ülo Lumistele; keemia ja molekulaarbioloogia alal Agu Laisk
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Kolmteist valitud uurimust / Paul Alvre
Alvre, Paul
1997-01-01
Arvustus: Itkonen, Terho. Aloja ja aiheita : valikoima kolmen kymmenluvun tutkielmia 1959-1979 = Themen und Bereiche : ausgewählte Aufsätze 1959-1979 = Fields and topics : selected studies 1959-1979. Helsinki : Suomalais-ugrilainen seura, 1993. (Suomalais-ugrilaisen seuran toimituksia ; 216 )
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TÜ nõukogu nimetas neli uut professorit ja emeriitdotsendi
2012-01-01
TÜ nõukogu valis 2011.a. detsembri istugil professoriteks Helle Karro (sünnitusabi ja günekoloogia alal), Jaak Vilo (bioinformaatika alal), Varmo Vene (programmeerimiskeelte semantika alal), Marlon Dumas (tarkvaratehnika alal) ja emeriitdotsendiks majandusõppejõud Kersti Meiesaar
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The importance of investor relations in the overall welfare of an organisation / Kati Aru
Aru, Kati
2001-01-01
Üks oluline valdkond organisatsiooni suhtekorralduses on investorisuhted, mis peaks olema strateegilise planeerimise osaks. Tutvustatakse Tallinna Börsil osalevate ettevõtete seas läbi viidud uurimust
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Koolieelne kasvatus jätkuvalt aktuaalne / Aino Saar, Lehte Tuuling, Gaili Suursaar
Saar, Aino, 1952-
1997-01-01
Münchenis toimunud EECERA (European Early Childhood Education Research Association) konverents. EECERA - rahvusvaheline organisatsioon, mis on pühendunud koolieelse kasvatusega seotud uurimuste soodustamisele ja uurimistulemuste levitamisele
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Kuus TÜ teadlast sai riigi teaduspreemia
2013-01-01
Eest Vabariigi aastapäeval pälvisid preemia täppisteaduste alal prof. Mikhail Brik, keemia ja molekulaarbioloogia alal prof. Jaanus Remme, arstiteaduse vallas prof-d Jaan Eha ning Mihkel Zilmer, geo- ja bioteaduste alal vanemteadur Peeter Hõrak, humanitaarteaduste alal vanemteadur Andres Tvauri
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1998-01-01
30.01.98. omistati Anne Uusenile, Maia Muldmale ja Monika Pulleritsule pedagoogikamagistri kraad, 12.02.98. Kaire Tõugule ja Tõnu Martmale magister scientsarum geoökoloogia alal, 6.03.98. Tõnu Laasile magister scientsarum füüsika alal, 20.03.98. Joe Noormetsale magister artium sporditeaduste alal, 25.03.98. Ülle Soosalule magister artium infoteaduste alal, 1.04.98. Ene Kullile ja Lea Kivipõllule magister artium sotsiaaltöö alal
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Center, Reform parties access government / Aleksei Gunter
Gunter, Aleksei, 1979-
2004-01-01
Keskerakonna ja Reformierakonna valitsuse ametisseastumise aastapäeva konverentsil esinesid kõnedega Edgar Savisaar ja Siim Kallas. Politoloog Rein Toomla tutvustas parlamendierakondade põhjal tehtud uurimust erakondade sobivusest koalitsiooni
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Святого Канута подменили / Владимир Лесмент
Лесмент, Владимир, 1931-
2004-01-01
Katoliiklikust pühakust Knud Lavard'ist (kanoniseeriti 1169), keda kujutab autori uurimuste kohaselt Tallinna Kanuti gildi hoone (arhitektid N. P. Jegorjev ja F. Kordes) fassaadi kaunistav Püha Kanuti skulptuur
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Jones, Rebecca
2009-01-01
Arhitektuurist, mis on dialoogis teiste kunsti- ja eluvormidega. Artikkel on sissejuhatuseks suuremale uurimustööle etendusliku arhitektuuri kontseptsioonist. Autorite vaateid on mõjutanud soome arhitekt Marco Casagrande ja ameerika lavastaja Robert Wilson
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Reasons for internal migration in Estonia 1989-2000 / Mare Ainsaar
Ainsaar, Mare
2004-01-01
Autor tutvustab oma uurimust "Reasons for move: a study on trends and reasons of internal migration with particular interest in Estonia 1989-2000" (Turku University, 2004) Eesti elanikkonna migratsioonist ja selle põhjustest. Skeemid
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Mälu ja liikumine kui ruumipraktikad = Memory and motion as spatial practices / Morten Lund
Lund, Morten, 1972-
2015-01-01
Artiklis on käsitletud nelja uurimust ruumist, mis illustreerivad võimalusi, kuidas sisearhitektuur võib kaasata mälu ja liikumise kui ruumilised praktikad läbi ruumilise kunsti ning 1:1 eksperimentide
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Marju Lauristin : Naidite drug druga! / Marju Lauristin ; interv. Jevgenija Garanzha
Lauristin, Marju, 1940-
2007-01-01
Intervjuu sotsioloogiga pronkssõduriga seotud Venemaa propagandasõja, rahvussuhete, integratsiooni ja dialoogi võimalikkuse teemadel, rahvastikuministri tellimusel valminud uurimustööst, mis käsitleb eestlaste ja venelaste suhteid peale aprillisündmusi
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Kalmus, Veronika, 1973-
2003-01-01
Autor kirjeldab Eesti ja Vene rahvusest õpilaste hulgas läbi viidud uurimust, mille eesmärgiks oli selgitada välja nende suhtumist kultuuridevahelise integratsiooni võimalikkusesse Eestis ning seda mõjutavad tegurid
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Dr. Heinz von zur Mühlen - teenekas Tallinna ajaloo uurija / Peep Pillak ; foto: Peep Pillak
Pillak, Peep
2003-01-01
ülevaade üheks paremaks Eesti ja Liivimaa, eriti aga Tallinna keskaja asjatundjaks peetava baltisakslasest ajaloolase eluteest ja teaduslikest uurimustöödest, mille eest pälvis 11. sept. 2002 Tallinna teenetemärgi
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Tulemuslikkuse hindamine : efektiivsuse analüüs Käru raamatukogu näitel / Ilme Säde
Säde, Ilme
2011-01-01
Ülevaade Ilme Säde uurimustööst "Raamatukogutöö efektiivsuse analüüs lugejate ja töötajate hinnangute ning kvantitatiivsete tulemusnäitajate abil Käru rahvaraamatukogus aastatel 2005-2010"
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Materjal ja atmosfäär = Material and atmosphere / Klaske Havik, Gus Tielens
Havik, Klaske, 1975-
2015-01-01
OASE numbriks ning intervjuuks Juhani Pallasmaa ja Peter Zumthoriga valmistudes uurisid autorid ka omaenda mälu ja valisid oma arhiividest atmosfäärilisi paiku. Illustreerivaid fotosid saadavad väljaandes "Stepping Stones" ilmunud uurimuste originaaltekstid.
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Näripea, Eva, 1980-
2011-01-01
Võtab vaatluse alla Nõukogude Eesti filmikunsti esimese perioodi, mil domineerisid nn külalislavastajad. Uuritakse, kuidas ruumipresentatsioonid resoneerusid ideoloogiliste võngetega ühiskonnas. Kasutatud on John Urry "turistliku pilgu" mõistet ja K.Clarki uurimust sakraliseeritud sotsrealistlikust ruumist
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Cytogenetic abnormalities in acute leukaemia of ambiguous lineage: an overview.
Manola, Kalliopi N
2013-10-01
Acute leukaemia of ambiguous lineage (ALAL) is a rare complex entity with heterogeneous clinical, immunophenotypic, cytogenetic and molecular genetic features and adverse outcome. According to World Health Organization 2008 classification, ALAL encompasses those leukaemias that show no clear evidence of differentiation along a single lineage. The rarity of ALAL and the lack of uniform diagnostic criteria have made it difficult to establish its cytogenetic features, although cytogenetic analysis reveals clonal chromosomal abnormalities in 59-91% of patients. This article focuses on the significance of cytogenetic analysis in ALAL supporting the importance of cytogenetic analysis in the pathogenesis, diagnosis, prognosis, follow up and treatment selection of ALAL. It reviews in detail the types of chromosomal aberrations, their molecular background, their correlation with immunophenotype and age distribution and their prognostic relevance. It also summarizes some novel chromosome aberrations that have been observed only once. Furthermore, it highlights the ongoing and future research on ALAL in the field of cytogenetics. © 2013 John Wiley & Sons Ltd.
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Konkurss "Riigiasutuste koostööprojekt 2003" / Viire Rannasoo
Rannasoo, Viire
2004-01-01
Konkursi raames anti välja kolm auhinda: tulemusliku koostöö eest eurolõimumise alal projektile "Eesti tollitariifistiku loomine", uuendusliku ja parima algatuse alal projektile "Digitaalne terviselugu", inimsõbraliku ja kliendikeskse lahenduse alal projektile "Eesti elanikele pensionide, toetuste ja hüvitiste väljamaksmise korraldamise kaasajastamine"
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Лицейские перекрестки Европы / Алла Беленкова
Беленкова, Алла
2009-01-01
Juba üle kümne aasta juhatab autor Tallinna Vene Lütseumi muuseumi "A. S. Puškin. XX sajand". Tema uurimuste põhiteemaks on Tsarskoje Selo Lütseumis õppinud baltisakslaste ning nende järglaste kohta andmete väljaselgitamine
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25. juulil toimuvad kodukoha suurmehe Jakob Hurda 170. sünniaastapäeva pidustused
Vill, Sirje
2009-01-01
Jakob Hurda 170. sünniaastapäeva tähistatakse traditsioonilise kultuuriretkega Jakob Hurdaga seotud paikadesse, autasustatakse õpilaste uurimustööde võitjaid ja teemaüritusel "Jakob Hurt 170" Põlva Kultuuri- ja Huvikeskuses antakse üle laureaatidele Hurda-nimelised kultuuriauhinnad
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International Nuclear Information System (INIS)
Robles Hernández, F.C.; Calderon, H.A.
2012-01-01
Highlights: ► Fullerene mix (C 60 + C 70 + soot) is effective to manufacture nanostructured Al/Al 4 C 3 . ► Carbon in the fullerene mix is more reactive with Al that that present in graphite. ► A complete transformation of carbon into Al 4 C 3 is observed in the Al/fullerene. ► Milling and sintering conditions preserve the nanostructured nature of the composites. ► Hardness improvement: 375% Al/graphite and 582% for Al/fullerene composites. - Abstract: Nanostructured Al matrix composites with reinforcements of graphite or fullerene (C 60 + C 70 + soot) have been produced by mechanical milling and spark plasma sintering (SPS). X-ray diffraction and transmission electron microscopy show that C 60 + C 70 withstand longer mechanical milling/alloying times than graphite. Fullerene is a good control agent during mechanical alloying resulting in a denser Al/fullerene composite when compared to the Al/graphite one. A refinement mechanism that takes place during mechanical alloying of fullerene and graphite is experimentally found and correspondingly discussed. Such a mechanism plays a major role in the amorphization of graphite. The larger surface area of the fullerene mix after milling promotes a better interaction with Al and hence allows its complete transformation into Al 4 C 3 during the SPS process. The sintered products show an increase in hardness for the Al/fullerene composite of 6 times and only 4 times for the Al/graphite composite. The SPS technique shows to be an excellent method to transform the fullerene into Al 4 C 3 while preserving its nanostructured nature.
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Paabo, Triin
2012-01-01
Hugo Treffneri Gümnaasiumi õpilase uurimustöö, mille eesmärgiks on välja selgitada, millised ensüümi RlmH aminohapped on määrava tähtsusega märklaudnukleotiidi äratundmisel ning metülatsioonireaktsiooni katalüüsil
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Kemler, Ellen; Thijs, Karin M; Badenbroek, Ilse; van de Port, Ingrid G L; Hoes, Arno W; Backx, Frank J G
2016-12-01
Acute lateral ankle ligamentous sprains (ALALS) are common injuries. This injury does not always have a favourable long-term outcome. Studies reporting the prognosis of ALALS after functional treatment are scarce. To determine the prognosis of functionally treated ALALS, in terms of recurrent ALALS and residual symptoms. Retrospective cohort study. Patients were recruited from 20 family practices, nine physical therapy practices, the emergency departments of a regional hospital and a university hospital. Adult patients with an ALALS caused by an inversion trauma were invited to participate in this study 2.5-5 years after their initial injury. Functional treatment of the initial ALALS. Acute lateral ankle ligamentous sprain recurrences and residual symptoms. A total of 44 patients were included, with an average follow-up period after the initial ankle sprain of 204 weeks (range 150-274 weeks). Eight patients (18.1%) had reinjured their ankle. Explicit pain around the ankle joint at physical examination was experienced by 45.5%. Clinical symptoms of anterior ankle impingement were present in 25% (all athletes), with radiologically confirmed tibiotalar osteophyte bone formation in 82% of them. A large proportion of patients with ALALS experience recurrences and persistent symptoms after their initial ankle injury. The high percentage of patients with anterior ankle impingement syndromes illustrates the need for early assessment of this impairment in patients with persistent complaints. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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Directory of Open Access Journals (Sweden)
J. Lakshmipathy
2014-06-01
Full Text Available The wear behaviour comparison of Al/SiC and Al/Al2O3 composites prepared by stir casting technique is investigated to find out the effects of weight percentage of SiC/Al2O3, load and the number of strokes on a reciprocating wear testing machine. The MMC pins are prepared with different weight percentage of SiC and Al2O3 (10, 15 and 20 %. The tests are carried out with different load conditions (25, 50 and 75 N and different number of strokes (420,780 and 1605 strokes. Wear surfaces of tested samples are examined in Scanning Electron Microscope (SEM. Hardness test and impact test are also carried out on the MMC samples. The experimental results shows that hardness of composites increases with increase in SiC and Al2O3 particle and the impact strength decreases with increase in SiC and Al2O3 content. The volume loss of MMC specimens are less than that of the matrix alloy. The temperature rise near the contact surface of the MMC specimens increases with increase in wt% of SiC and Al2O3, load and number of strokes. The coefficient of friction decreases with increase in the number of strokes. The WVAS (Wireless Vibration Acquisition System interfaced with MAT Lab software is used to record the amplitudes during the test.
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Sõdu jääb maailmas iga aastaga järjest vähemaks / Krister Paris
Paris, Krister, 1977-
2005-01-01
Kanada päritolu politoloog Andrew Mack esitles ÜRO peakorteris oma uurimust, mille kohaselt on nii sõdades kui ka konfliktide tõttu hukkunute arv järjekindlalt vähenenud ning sõjaliste konfliktide hulk alates 1992. aastast vähenenud 40%. Kaart: Sõdade arv on oluliselt vähenenud. Lisa: ÜRO tegevusel siiski ka tulemus
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Intermetallic Growth and Interfacial Properties of the Grain Refiners in Al Alloys
Li, Chunmei; Cheng, Nanpu; Chen, Zhiqian; Xie, Zhongjing; Hui, Liangliang
2018-01-01
Al3TM(TM = Ti, Zr, Hf, Sc) particles acting as effective grain refiners for Al alloys have been receiving extensive attention these days. In order to judge their nucleation behaviors, first-principles calculations are used to investigate their intermetallic and interfacial properties. Based on energy analysis, Al3Zr and Al3Sc are more suitable for use as grain refiners than the other two intermetallic compounds. Interfacial properties show that Al/Al3TM(TM = Ti, Zr, Hf, Sc) interfaces in I-ter interfacial mode exhibit better interface wetting effects due to larger Griffith rupture work and a smaller interface energy. Among these, Al/Al3Sc achieves the lowest interfacial energy, which shows that Sc atoms should get priority for occupying interfacial sites. Additionally, Sc-doped Al/Al3(Zr, Sc) interfacial properties show that Sc can effectively improve the Al/Al3(Zr, Sc) binding strength with the Al matrix. By combining the characteristics of interfaces with the properties of intermetallics, the core-shell structure with Al3Zr-core or Al3Zr(Sc1-1)-core encircled with an Sc-rich shell forms. PMID:29677155
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International Nuclear Information System (INIS)
Mao, Z.; Chen, W.; Seidman, D.N.; Wolverton, C.
2011-01-01
First-principles density functional calculations are used to study the nucleation and stability of L1 2 -ordered precipitates in Al-Sc-Li alloys. For dilute Al alloys, there are three possible ordered L1 2 precipitates: Al 3 Sc, Al 3 Li and an Al 3 Sc/Al 3 Li core/shell structure. To calculate the nucleation behavior, information about bulk thermodynamics (both static total energies and vibrational free energies), interfacial energetics and coherency strain is required. The study finds the following: (1) the coherency strain energies for forming coherent interfaces between Al/Al 3 Sc, Al/Al 3 Li and Al 3 Sc/Al 3 Li are relatively small, owing to the small atomic size mismatches in these systems; (2) the sublattice site preferences of Sc and Li are calculated, and it is demonstrated that Sc and Li share the same sublattice sites in both Al 3 Sc(L1 2 ) and Al 3 Li(L1 2 ), in agreement with recent experimental results; (3) the calculated solubilities of Sc and Li in α-Al alloys are in good agreement with experimental values and, for Sc, agree well with prior first-principles results; (4) the interfacial energies for Al/Al 3 Sc, Al/Al 3 Li and Al 3 Sc/Al 3 Li for (1 0 0), (1 1 0) and (1 1 1) interfaces are calculated: the values of the Al/Al 3 Sc interfacial energies are significantly larger than those of the Al/Al 3 Li and Al 3 Sc/Al 3 Li interfaces; (5) combining the bulk and interfacial energies yields the nucleation barriers and critical radii for Al 3 Sc and Al 3 Li precipitates; and (6) the energetic stability of the Al 3 Sc/Al 3 Li core/shell structure is compared with individual Al 3 Sc and Al 3 Li nuclei, and the range of precipitate sizes for which the core/shell structure is energetically favored is determined quantitatively.
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Kas pausid kannavad emotsiooni?
Directory of Open Access Journals (Sweden)
Kairi Tamuri
2010-05-01
Full Text Available Pausidele on emotsionaalse kõne uurimustes suhteliselt vähe tähelepanu pööratud. Ilmselt seetõttu, et pausid ei ole esmased emotsiooni kandvad akustilised tunnused. Siiski on teada, et pausidel on emotsioonide eristamisel oma roll. Artiklis antakse vastus kahele küsimusele: kas eestikeelse etteloetud emotsionaalse teksti pausid sõltuvad oluliselt teksti emotsioonist ning kas teksti emotsioon on ära tuntav ainult pausierinevuste põhjal.DOI: http://dx.doi.org/10.5128/ERYa6.18
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Maróti, P; Hanson, D K; Baciou, L; Schiffer, M; Sebban, P
1994-01-01
Light-induced charge separation in the photosynthetic reaction center results in delivery of two electrons and two protons to the terminal quinone acceptor QB. In this paper, we have used flash-induced absorbance spectroscopy to study three strains that share identical amino acid sequences in the QB binding site, all of which lack the protonatable amino acids Glu-L212 and Asp-L213. These strains are the photosynthetically incompetent site-specific mutant Glu-L212/Asp-L213-->Ala-L212/Ala-L213 ...
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Experimental Characterization of Aluminum-Based Hybrid Composites Obtained Through Powder Metallurgy
Marcu, D. F.; Buzatu, M.; Ghica, V. G.; Petrescu, M. I.; Popescu, G.; Niculescu, F.; Iacob, G.
2018-06-01
The paper presents some experimental results concerning fabrication through powder metallurgy (P/M) of aluminum-based hybrid composites - Al/Al2O3/Gr. In order to understand the mechanisms that occur during the P/M processes of obtaining Al/Al2O3/Gr composite, we correlated the physical characteristics with their micro-structural characteristics. The characterization was performed using analysis techniques specific for P/M process, SEM-EDS and XRD analyses. Micro-structural characterization of the composites has revealed fairly uniform distribution this resulting in good properties of the final composite material.
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Mapping energetics of atom probe evaporation events through first principles calculations.
Peralta, Joaquín; Broderick, Scott R; Rajan, Krishna
2013-09-01
The purpose of this work is to use atomistic modeling to determine accurate inputs into the atom probe tomography (APT) reconstruction process. One of these inputs is evaporation field; however, a challenge occurs because single ions and dimers have different evaporation fields. We have calculated the evaporation field of Al and Sc ions and Al-Al and Al-Sc dimers from an L1₂-Al₃Sc surface using ab initio calculations and with a high electric field applied to the surface. The evaporation field is defined as the electric field at which the energy barrier size is calculated as zero, corresponding to the minimum field that atoms from the surface can break their bonds and evaporate from the surface. The evaporation field of the surface atoms are ranked from least to greatest as: Al-Al dimer, Al ion, Sc ion, and Al-Sc dimer. The first principles results were compared with experimental data in the form of an ion evaporation map, which maps multi-ion evaporations. From the ion evaporation map of L1₂-Al₃Sc, we extract relative evaporation fields and identify that an Al-Al dimer has a lower evaporation field than an Al-Sc dimer. Additionally, comparatively an Al-Al surface dimer is more likely to evaporate as a dimer, while an Al-Sc surface dimer is more likely to evaporate as single ions. These conclusions from the experiment agree with the ab initio calculations, validating the use of this approach for modeling APT energetics. Copyright © 2013 Elsevier B.V. All rights reserved.
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Processing, microstructure evolution and properties of nanoscale aluminum alloys
Han, Jixiong
In this project, phase transformations and precipitation behavior in age-hardenable nanoscale materials systems, using Al-Cu alloys as model materials, were first studied. The Al-Cu nanoparticles were synthesized by a Plasma Ablation process and found to contain a 2˜5 nm thick adherent aluminum oxide scale, which prevented further oxidation. On aging of the particles, a precipitation sequence consisting of, nearly pure Cu precipitates to the metastable theta' to equilibrium theta was observed, with all three forming along the oxide-particle interface. The structure of theta' and its interface with the Al matrix has been characterized in detail. Ultrafine Al-Cu nanoparticles (5˜25 nm) were also synthesized by inert gas condensation (IGC) and their aging behavior was studied. These particles were found to be quite stable against precipitation. Secondly, pure Al nanoparticles were prepared by the Exploding Wire process and their sintering and consolidation behavior were studied. It was found that nanopowders of Al could be processed to bulk structures with high hardness and density. Sintering temperature was found to have a dominant effect on density, hardness and microstructure. Sintering at temperatures >600°C led to breakup of the oxide scale, leading to an interesting nanocomposite composed of 100˜200 nm Al oxide dispersed in a bimodal nanometer-micrometer size Al matrix grains. Although there was some grain growth, the randomly dispersed oxide fragments were quite effective in pinning the Al grain boundaries, preventing excessive grain growth and retaining high hardness. Cold rolling and hot rolling were effective methods for attaining full densification and high hardness. Thirdly, the microstructure evolution and mechanical behavior of Al-Al 2O3 nanocomposites were studied. The composites can retain high strength at elevated temperature and thermal soaking has practically no detrimental effect on strength. Although the ductility of the composite remains
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Üks doktor ja kaks magistrit / Halliki Uibu
Uibu, Halliki
2001-01-01
18. juunil 2001 toimus TPÜ kultuuriajaloo kaitsmisnõukogus Lauri Lindströmi doktoritöö "Album Academicum Universitatis Tartuensis 1918-1944. Rahvus, sugu, sünni- ja keskhariduse omandamise koht üliõpilaskonna kujunemist ja kõrghariduse omandamist mõjutavate teguritena" kaitsmine. Lauri Lindströmile omistati teaduskraad doctor philosophiae (PhD) kultuuriajaloo alal. TPÜ kultuuriajaloo magistrikraadi kaitsmisnõukogus kaitsesid 18. juunil 2001 Igor Tõnurist magistritööd "Pillid ja pillimäng eesti külaelus" ja Tatjana Tšervova magistritööd "Vene kogukonna ühiskondlikust ja kultuurielust Tallinnas 1880-1905". Igor Tõnuristile ja Tatjana Tšervovale omistati teaduskraad magister artium kultuuriajaloo alal hindega cum laude
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Art history in nineteenth-century Estonia? / Rene Mäe
Jõekalda, Kristjan, 1971-
2015-01-01
Kunstiajaloodistsipliini teke Baltikumis, Tartu Ülikooli kunstiajaloo-alane tegevus. Kunstiajaloo esimesed viljelejad Eesti alal: Gotthard von Hansen, Friedrich Amelung, Reinhold Guleke ja Wilhelm Neumann
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Korruptsioon: ehitusala loomus / Kaarel Tarand
Tarand, Kaarel, 1966-
2005-01-01
Korruptsioonist ehituses ja poliitikas. Transparency International avaldas aruande korruptsioonist ehituse ja riigihangete alal. Diagrammid, tabel: Korruptsioon ja erakonnad; Ehitussektori põhinäitajad; Korruptsiooni baromeeter
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Steve Jürvetson muudab maailma / Jaanika Heinsoo
Heinsoo, Jaanika
2004-01-01
Ameerikas elavast eestlasest riskiinvestorist, tema tegevusest infotehnoloogia alal, Eesti rollist infotehnoloogia maailmas, lähituleviku arengutest, iidolitest. Vt. samas intervjuud Steve Jürvetsoniga. Lisa: Steve Jürvetson
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Pae, Taavi, 1976-
2015-01-01
Esimeset valdade reformist Eesti alal. Valdade reformi takerdumisest iseseisvas Eestis. 1939. aastal jõustunud omavalitsuste reformi tagamaadest. Teise valdade liitmise reformi käigust. Peamistest probleemidest vallapiiride muutmisel.
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Grosvenor, Gerald
2006-01-01
Briti kaitsejõudude ülema asetäitja reservide alal räägib Suurbritannia Territoriaalarmeest, Kaitseliidu-sarnaste vabatahtlike organisatsioonide kasutamisest välismissioonidel, ajateenistusest ja olukorrast Iraagis
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Põllumajanduse algus Eesti alal / Aivar Kriiska
Kriiska, Aivar, 1965-
2007-01-01
Varajase maaviljeluse uurimise allikatest. Esimesed terviljakasvatuse märgid korreleeruvad kammkeraamika kultuuridega. Põllumajandusest hilisneoliitikumis ja varajasel pronksiajal. Viljelev majandus tõi nöörkeraamika perioodil kaasa küla lagunemise väiksemateks asustusüksusteks - taludeks. Kiviaja lõpul toimus põllumajandusliku asustuse laienemine, kusjuures see hõlmas ka kõrgustike alasid
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1997-01-01
Teaduspreemia autorite kollektiivile arstiteaduse alal töö "Vähktõbi Eestis 1968-1992: haigestumus, levimus, elulemus ja suremus" eest - Mati Rahu (kollektiivi juht), Tiiu Aarelaid, Kaja Gornoi, Heldi Thomson
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Alberto Cambrosio intervjuu David Tomas'ga / David Tomas ; intervjueerinud Alberto Cambrosio
Tomas, David
2010-01-01
Kanada antropoloogia professor ja kunstnik oma tegevusest kunsti ja teaduse vahelisel alal, uurides pildistamisprotsessi antropoloogiliste teooriatega visuaalsete mudelite näol ja kummutades lääne vaatamisharjumustega seotud dogmasid
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Lõbusa eeskavaga Oktoberfest Lakewoodis / Priit Parming ; fotod: Liisa-Mai Karuks
Parming, Priit
2012-01-01
22. septembril kogunes paarisajaliikmeline eestlaste, lätlaste ja leedulaste pere Lakewoodi Eesti Ühingu maa-alale, nautima ilusat ilma ja hubast meeleolu ühingu poolt korraldatud Balti kallakuga Oktoberfestil
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Nobeli preemia majanduse valitsemisstruktuuride uurijatele / Alari Purju
Purju, Alari, 1953-
2009-01-01
Rootsi Kuninglik Teaduste Akadeemia otsustas 2009. aasta Rootsi Keskpanga Nobeli mälestusauhinna majandusteaduse alal anda USA majandusteadlastele Elinor Ostromile Indiana ülikoolist ja Oliver E. Williamsonile Berkley California ülikoolist
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Kerge, Krista, 1952-
2006-01-01
Eesti-Soome koostööst keele alal. 31. keeleteaduse päevad toimusid 2004. a. Tallinna Ülikoolis, kogumik "Finest linguistics" sisaldab valiku artikliteks vormunud ettekannetest, mis sel konverentsil peeti
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Liisa Kruusmäe juhuslikult pealt kuuldud hetked / Kaarel Kressa
Kressa, Kaarel, 1983-
2011-01-01
Liisa Kruusmäe näitus "Overheard Stories / Pealtkuuldud lood" Tallinnas Draakoni galeriis. 2010. a. Eesti Kunstiakadeemia maaliosakonna lõpetanud Liisa Kruusmägi omandab EKA-s joonistamise alal magistrikraadi
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Linnateatri suveetenduse lavastab prantslane / Tiiu Talvist
Talvist, Tiiu
2002-01-01
Kuressaare Linnateatri suvelavastus "Arlekiini elu ja surm" on kokku pandud commedia dell' arte originaalstsenaariumide põhjal ja seda hakkab lavastama P. Pezin, kes on asjatundja commedia dell' arte ja maskiteatri alal
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Sugar continues to vex Estonia, Latvia
2005-01-01
Põllumajandusminister Ester Tuiksoo saatis Euroopa Komisjoni volinikule põllumajanduse alal kirja, milles palus kodumajapidamistes tarvitatava suhkru mahaarvamist koguvarudest. Läti meedia teatas, et Euroopa Komisjon võib anda rohkem aega suhkruvarudest vabanemiseks
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Viru Vesi sai ISO sertifikaadid / Külli Kriis
Kriis, Külli, 1961-
2005-01-01
Ilmunud ka: Severnoje Poberezhje 23. märts lk. 4. AS Viru Vesi sai Eestis teise vee-ettevõttena veevarustuse, kanalisatsiooni ning reoveepuhastuse teenuse pakkumise alal keskkonna- ja kvaliteedijuhtimissüsteemi sertifikaadid
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Raamatukogu esisele kerkib kevadel Marie Underi kuju / Andres Eilart
Eilart, Andres
2009-01-01
Skulptor Mati Karminil ja arhitekt Tiit Trummalil valmib valgest marmorist mälestusmärk Marie Underile. Kuju püstitatakse 2010. a. kevadel Eesti Rahvusraamatukogu ette. Alale on kavandatud ka veekaskaadid
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Natshata razdatsha Nobelevskih premii
2002-01-01
Tänavuse Nobeli meditsiini- ja füsioloogiapreemia said Briti teadlased Sudney Brenner ja H. Robert Horvitz ning ameeriklane John E. Sulston elutähtsate avastuste eest organite arengu geneetilise regulatsiooni alal
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Venemaa saatis välja reportaazhi teinud Läti ajakirjanikud / Kaivo Kopli
Kopli, Kaivo
2005-01-01
Pihkva oblastis pidasid miilitsad kinni Läti televisiooni ajakirjanikud, kes olid kogumas materjali Abrene piirkonnas - alal, mis Läti põhiseaduse järgi kuulub Lätile, kuid on praegu Venemaa koosseisus
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Majandus soosib PPP projekte / Neil Tindal
Tindal, Neil
2009-01-01
Neil Tindal, kes on Suurbritannia nõustaja infrastruktuuri projektide ja avalike riigihangete alal, vastab küsimustele, mis puudutavad finantskriisi mõju Euroopa kiirrongide PPP projektide realiseerimisele ning riikliku investeerimise suurenemist PPP projektidesse
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Talumehed nõuavad Natura aladel ümbermõõtmisi / Silja Lättemäe
Lättemäe, Silja, 1952-
2006-01-01
Eestis tänavu esmakordselt makstavat Natura toetust saab ebasoodsamates piirkondades looduskaitse nõuete täitmise eest. Toetust saab vaid sellise põllu eest, mis asub tervikuna Natura 2000 võrgustiku alal
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Tartu ülikool tahab ehitada linna serva Veerikusse teaduslinnaku / Mirko Ojakivi
Ojakivi, Mirko
2007-01-01
Tartus Maarjamõisa ja Viljandi maantee ringtee vahelisele ligi 20 ha maa-alale plaanitakse ehitada mitu õppe- ja teadushoonet, ühiselamu, konverentsikeskus, hostel, lasteaed, vabaaja- ja spordikeskus. Keemiahoone ehitamist alustatakse veel sel aastal
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"Kevadtormile" jõudsid poolakad
2014-01-01
"Kevadtormile" saabusid Poola ründelennukid SU-22 ja nende sõjaväeüksus transpordilennuki CASA 295 pardal. Kolm Poola ründelennukit hakkavad "Kevadtormi" ajal tegema lahingulende õppuste alale Lõuna-Eestis
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Kuusk, Priit, 1938-
2001-01-01
Brüsseli rahvusvahelisest noorte interpreetide konkursist. Firenze maifestivalist "Maggio Musicale Fiorentino", Manchesteri tshellofestivalist, Brightoni festivalist. J.G. von Herderi preemia muusika alal pälvis M.Kopelent. Lühidalt E.Picht-Axenfeld'ist
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Globaalse soojenemise gospel / Margit Tõnson
Tõnson, Margit, 1978-
2008-01-01
Dokumentaalfilm USA poliitiku Al Gore'i võitlusest keskkonnasäästlikkuse alal "Ebamugav tõde" ("An Inconvenient Truth") : režissöör Davis Guggenheim : Ameerika Ühendriigid 2006, ETV ekraanil 29. aprillil
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Haak, Arvi
2005-01-01
Huntaugu mäel paiknenud lühiajalistest väikestest asustusüksustest. Viljandi ordulinnuse eeslinnuse hoovialal 14. saj. keskel toimunud muudatustest, kaevamistest esimese eeslinnuse alal, varisenud konvendihoone müüridest, leiumaterjali kirjeldus
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ELSA - tõenäoliselt parim juuratudengite ühendus maailmas / Margit Käpp
Käpp, Margit
2008-01-01
1981. aastal asutatud Euroopa juuratudengite ühendusest The European Law Students' Association (ELSA). Artikli kirjutamisele aitasid kaasa Pille Talpsepp (ELSA Estonia president aastal 2008/2009) ja Heiki Eesmaa (ELSA Estonia asepresident seminaride ja konverentside alal)
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Poliitikud tõrjuvad väiteid, et Euroopa Liit tahab Eestist kakskeelset riiki teha / Kristjan Roos
Roos, Kristjan, 1978-
2005-01-01
USA geopoliitilise alalüüsi keskuse Axis Information and Analysis Euroopas tegutseva analüütiku Simon Araloffi sõnul tahab EL Eestist kakskeelset riiki teha. Eesti poliitikud selle väitega ei nõustu
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Mazza, Pierpaolo
2009-01-01
GE Energy Ida-Euroopa müügijuhi sõnul soovib firma olla Eestis esindatud taastuva energeetika ja ennekõike tuuleenergia alal. Esimesed generaatorid saaks Eestisse paigutada 2010. a. lõpuks või 2011. a. alguseks
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Eesti Põlevkivi aitab kotkastele GPS-saatjad selga / Külli Kriis
Kriis, Külli, 1961-
2006-01-01
Vt. ka Severnoje Poberezhje 2. aug. Kotkaklubi eestvõttel ning Eesti Põlevkivi ja riigimetsa majandamise keskuse toetusel püstitatakse Narva karjääri taastatud alale kolm kotka pesapuud ning varustatakse kaks konnakotkast GPS-saatjatega
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Archaeological Investigations on the Sites of the Glassworks of Central Estonia / Andres Tvauri
Tvauri, Andres, 1970-
2013-01-01
18. sajandil oli peamiseks klaasitootmise piirkonnaks Eesti alal Viljandimaa põhja- ja Põhja-Tartumaa lääneosa, kus aastatel 1760-1780 tegutses seitse klaasikoda: Utsali, Laashoone, Altnurga, Haava, Tõrna, Laasme, Hoone. Klaasikodade asupaikadest leitud materjalist
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Modernne kastmaja Nõmmel / Ene Läkk
Läkk, Ene, 1957-
1999-01-01
Projekteerija: arhitektuuribüroo Mark & Tamm. Konstruktiivne osa: inseneribüroo Randväli Karema. Arhitektid Ülar Mark, Kalle Komissarov. Kahekorruseline maja Vabaduse pst. ääres on mahutatud puude vahele kitsale alale. Kommenteerib Ü. Mark.
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2013-01-01
Eelviikingiaja lõppu dateeritud matuselaevast. Sõdalased olid maetud väikesele alale ja varustatud rohkete panustega. Väliuuringud Salme muististekompleksil on lõppenud. Käimasolevate uuringute keskseks ülesandeks on muistise võimalikult täpne dateerimine
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Haak, Arvi, 1978-
2006-01-01
Linnamüüri väljapuhastamisest Viljandi raekoja taga. Järelvalvetöödega Tartu tänaval selgus, et keskaegne kiht uuritaval alal puudus (või polnud tekkinud), kultuurkiht sisaldas 18. ja 19. saj. leide
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Maruste, Madli
2007-01-01
8. XI 2006 Raadimõisa hotellis toimunud rahvusvahelisest workshop'ist, mille eesmärgiks oli anda spetsialistide poolsed juhtnöörid Raadi lennuvälja ümbritseval maa-alal linnastruktuuri väljaarendamiseks. Heiki Kalbergi kommentaar
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Sihtasutus Eesti Rahvuskultuuri Fond...
2002-01-01
15. oktoobrini võetakse vastu 2003. a. stipendiumide ja kultuuriprojektide finantseerimise taotlusi. Esimest korda jagatakse stipendiume Peep Keskküla (toetatakse Eesti kunstielu arengut), Renate Jõesaare (stipendium eesti rahvusest isikule, kes on tegev kujutava kunsti alal) jt. fondidest
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2015-01-01
2008-2014. aastatel aset leidnud kaevamiste käigus on avastatud umbes 1000 km2 suuruselt alalt üle 40 uue kinnismuistisedateeringuga 5100-2000 eKr. Savinõude sarnasus uuritud alal osutab Narva-Lauga piirkonna ühtsele keraamikatraditsioonile
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Eesti sugemetega jaapani aed / Ene Läkk
Läkk, Ene, 1957-
1999-01-01
Ülle Grishakovi kujundatud aed Kose-Lükatil Pirita jõe käärus endise prügimäe kohal. Kahe hektari suurusel alal on esindatud jaapani aed, dekoratiiv-tarbeaed, inglise stiilis vanaema aed. 7 illustratsiooni.
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Volta kvartal valmib viie aasta pärast
2007-01-01
Tallinnasse Tööstuse tänavale AS-i Volta endise tootmishoone alale plaabnitav Volta kvartal valmib 2012. aastal. Ettevõtte juhatuse esimehe Aivar Reiviku sõnul kulub detailplaneeringu koostamiseks kaks ning ehituseks viis aastat. Arendaja: OÜ Koger Kinnisvara
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Kvartal Volta budet gotov tsherez pjat let
2007-01-01
Tallinnasse Tööstuse tänavale AS-i Volta endise tootmishoone alale plaabnitav Volta kvartal valmib 2012. aastal. Ettevõtte juhatuse esimehe Aivar Reiviku sõnul kulub detailplaneeringu koostamiseks kaks ning ehituseks viis aastat. Arendaja: OÜ Koger Kinnisvara
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Tänavused riikliku teaduspreemia laureaadid TÜ-s
2009-01-01
EV riikliku teaduspreemia laureaadid täppisteaduste (A. Šerman), keemia ja molekulaarbioloogia (Ü. Langel, M. Pooga, M. Hansen, U. Soomets, K. Kilk), arstiteaduse (P. Peterson), geo- ja bioteaduste (M. Pärtel), sotsiaalteaduste (T. Paas), humanitaarteaduste alal (A. Tering)
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Danikov, Maksim
2006-01-01
Ilmunud ka: Severnoje Poberezhje Ilmunud ka: Severnoje Poberezhje : Subbota 10. juuni lk. 5. Kiviõli aselinnapea kommunaalmajanduse alal oma tööst, linna arengust ja tulevikust. Arvamust avaldavad Kiviõli linnapea Voldemar Trumm ja OÜ Formet Grupp juht Pavel Suslov
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Sajand Waldhofi tselluloosivabriku hävimisest / Heino Kasesalu
Kasesalu, Heino, 1932-
2015-01-01
Waldhofi tselluloosivabrik Pärnus oli 20. saj. algul tollase Vene impeeriumi suurim ja moodsaim omataoline ettevõte. Esimese maailmasõja alal, 1915. aasta 20. augustil, lasti vabrik sakslaste dessandi kartuses Pärnu komandant polkovnik Pavel Rodzjanko käsul õhku
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Preliminary investigations of the southeastern section of the settlement site of Lehmja / Ain Lavi
Lavi, Ain, 1951-
2007-01-01
Seoses Tallinn-Tartu maantee rekonstrueerimisega toimusid 1985.-1986. aastal Lehmja asula lõunapoolsel alal mahukad päästekaevamised. Selgus, et tegemist on I aastatuhandest pärit asulakohaga, milliseid teatakse Eestis vähe. 2006. aasta kaevamismetoodikast ja uurimistulemustest
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No more autodidacts? / Janis Vanags
Vanags, Jānis, 1958-
2005-01-01
Läti CV-Online'i kommunikatsiooni ja turunduse juhi arvates peavad marketingi, ärijuhtimise ning kommunikatsiooni alale tööle pürgijad kindlasti omama vastavat akadeemilist väljaõpet. Teiseks määravaks faktoriks kandidaatidele on kliendikesksus
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Hansapank liisib Venemaal vaguneid / Lauri Linnamäe
Linnamäe, Lauri
2003-01-01
Ilmunud ka: Delovõje Vedomosti 3. september lk. 5. Hansa Capitalile ja EBRD-le kuuluv Hansa Leasing Russia on Venemaal raudteevagunite finantseerimise alal turuliider. Liisinguteenust Venemaal kavandab ka Eesti Ühispank. Diagramm: Venemaa osa kasvas Hansapanga jaoks hüppeliselt
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USA asekaitseminister seisab Eesti eest
2010-01-01
Eestis visiidil viibiv USA asekaitseminister poliitika alal Michele Flournoy ütles, et pooldab koostöökohtade otsimist Moskvaga, kuid on kindlal seisukohal, et Venemaa ei tohi end siin piirkonnas kehtestada. Flournoy tunnustas Eesti panust Afganistani ning samuti liitlassuhetesse laiemalt
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Reshenii net, no za vodu pridjotsja priplatshivat / Vladimir Polezhajev
Polezhajev, Vladimir
2007-01-01
Eesti ei suuda tähtajaks täita EL-i nõudeid reoveemajanduse korraldamise alal. Harjumaa ja Järvamaa omavalitsusliitude juhtide hinnangul ei suuda kohalikud omavalitsused seda probleemi üksi lahendada, vaja oleks riigi toetust. Rahandusministeeriumi nõuniku Kristi Jõesaare seisukoht
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Kus tondid Tallinnas pidu peavad?
2008-01-01
Lagunevatest hoonetest Tallinnas - end. Kalinini nimeline tehas, Eesti Meremuuseumi alal asuv hoone, Volta tehase hooned Tööstuse tänaval, Keraamikatehase hooned Maleva 2, Patarei vangla, Tina tänava juugendvilla (projekteerijad Karl Burman ja Artur Perna), puitelamu Kadriorus Poska 6
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Bit keskus. (Uuendusliku Tehnoloogia Keskus) Inca, Mallorca, Hispaania / Alberto Campo Baeza
Campo Baeza, Alberto
1998-01-01
High-tech büroo kolmnurksel krundil industriaalpargis. Krundi sisemuses suletud alal "salaaed" apelsinipuudega. Seintel ronivad aromaatse lõhnaga taimed: jasmiinid, vistaaria, viinapuud. Konkurss 1995, ehitus 1997-1998. Arhitekt Alberto Campo Baeza (koos: L. Ignacio Aguirre Lopez, Anton Garcia Abril, Antonio Perez Villegas)
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Argument ÜRO vastu / Joshua Muravchik
Muravchik, Joshua
2004-01-01
ÜRO rollist Somaalias, Rwandas ja Bosnias, Iisraeli eristaatusest. ÜRO silmakirjalikkusest inimõiguste alal, terrorismi legaliseerimisest, Kofi Annani juhtimisstiilist. Maailmas on pärast 1945. aastat valitsenud suhteline rahu mitte tänu ÜRO-le, vaid peamiselt USA tegevusele, leiab autor
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Anderson, Ants, 1933-
2007-01-01
tähistab sünnipäeva 22. jaanuaril, tema elukäigust, Eesti Arstide Seltsi Rootsis esimees ja liige, Eesti Üliõpilaste Seltsi liige. Oma kliinilise ja teadusliku karjääri tegi röntgendiagnostika ja kiiritusravi alal
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Li{sub 12}Cu{sub 12.60}Al{sub 14.37}. A new ternary derivative of the binary Laves phases
Energy Technology Data Exchange (ETDEWEB)
Pavlyuk, Volodymyr [Ivan Franko Lviv National Univ. (Ukraine). Dept. of Inorganic Chemistry; Jan Dlugosz Univ., Czestochowa (Poland). Inst. of Chemistry, Environment Protection and Biotechnology; Dmytriv, Grygoriy; Tarasiuk, Ivan [Ivan Franko Lviv National Univ. (Ukraine). Dept. of Inorganic Chemistry; Chumak, Ihor [IFW Dresden (Germany); Ehrenberg, Helmut [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inorganic Chemistry
2011-12-15
New ternary dodecalithium dodecacopper tetradecaaluminium, Li{sub 12}Cu{sub 12.60}Al{sub 14.37} (trigonal, R anti 3m, hR39), crystallizes as a new structure type and belongs to the structural family that derives from binary Laves phases. The Li atoms are enclosed in 15- and 16-vertex and the Al3 atom in 14-vertex pseudo-Frank-Kasper polyhedra. The polyhedra around the statistical mixtures of (Cu,Al)1 and (Al,Cu)2 are distorted icosahedra. The electronic structure was calculated by the TB- LMTO-ASA (tight-binding linear muffin-tin orbital atomic spheres approximation) method. The electron localization function, which indicates bond formation, is mostly located at the Al atoms. Thus, Al-Al bonding is much stronger than Li-Al or Cu-Al bonding. This indicates that, besides metallic bonding which is dominant in this compound, weak covalent Al-Al interactions also exist. (orig.)
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International Nuclear Information System (INIS)
Fuxiao, Yu; Fang, Liu; Dazhi, Zhao; Toth, Laszlo S
2014-01-01
Al-Fe alloys are attractive for applications at temperatures beyond those normally associated with the conventional aluminum alloys. Under proper solidification condition, a full eutectic microstructure can be generated in Al-Fe alloys at Fe concentration well in excess of the eutectic composition of 1.8 wt.% Fe. The microstructure in this case is characterized by the metastable regular eutectic Al-Al 6 Fe fibers of nano-scale in diameter, instead of the equilibrium eutectic Al-Al 3 Fe phase. In this study, the microstructure and mechanical properties of the Al-3Fe alloy with metastable Al 6 Fe particles deformed by equal channel angular extrusion were investigated. Severe plastic deformation results in a microstructure consisting of submicron equiaxed Al grains with a uniform distribution of submicron Al 6 Fe particles on the grain boundaries. The room temperature tensile properties of the alloy with this microstructure will be presented
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Tõeliselt julge projekt = A brave project, indeed / Tarja Nurmi
Nurmi, Tarja
2013-01-01
Aidu püramiidid. Arhitekt: Kadarik Tüür Arhitektid (KTA). Autorid: Ott Kadarik, Mihkel Tüür. Projekt: 2011-2013. Vastavalt projektile on alale ette nähtud restoranid, veinikeldrid, ujumiskohad jm. Peapüramiid (130 m kõrge) lubab harrastada mägironimist
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Eesti võimalused Soome lahe kasvukolmnurgas / Aare-Maldus Uustalu
Uustalu, Aare-Maldus, 1935-
2005-01-01
Euroopa Komisjoni ekspert logistika, transpordi ja regionaalökonoomika alal, TTÜ Tallinna Kolledzhi dotsent 2002. aasta alguses käivitatud Soome lahe kasvukolmnurga projektist, Eesti majanduse arenguperspektiivist projekti raames ning Eesti riigiametnike ükskõiksusest projekti suhtes. Via Baltica lisakoridoride projekti Via Islands ideest
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Eesti põllumajanduse töötervishoiu ja tööohutuse profiil / Marina Kempinen, Kari Kurppa
Kempinen, Marina
2005-01-01
Eesti põllumajanduse töötervishoiu ja -ohutuse sektoraalne profiil koostati põllumajanduse töötervishoiu võrgustiku raames ühe osana Eesti-Soome koostööprojektist töötervishoiuteenuste alal (2003-2004). Tabel: SWOT-analüüsi tulemused
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Lübecki filmipäevad 1999 ja Thomas Manni ekraniseering 1923 / Lauri Kärk
Kärk, Lauri, 1954-
1999-01-01
4.-7. novembrini Lübeckis toimunud Põhjamaade filmipäevade 41. Nordische Filmtage huvitavamatest filmidest, nagu Thomas Manni "Buddenbrookide" ekraniseering 1923. aastast (režissöör Gerhard Lamprecht) ja Rasmus Gerlachi dokumentaal "Operaator Kaufman" Dziga Vertovist ja tema kahest, samuti kino alal tegutsenud vennast
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Saddam Husseinile määrati surmanuhtlus poomise läbi / Heiki Suurkask
Suurkask, Heiki, 1972-
2006-01-01
Peale Iraagi endise presidendi Saddam Husseini mõisteti süüdi ka tema poolvend, luureteenistuse juht Barzan al-Tikriti ja revolutsioonikohtu endine juht Awad Hamad al-Bandar. Alustatud on kohtuasi Kurdistani alal sooritatud keemiarelvarünnakute ja Kurdistani veresauna asjus. Lisa: Toetajad lubavad kättemaksu
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Baltimaade kunstiajaloo isa : Wilhelm Neumann 150 / Jevgeni Kaljundi
Kaljundi, Jevgeni, 1931-2011
1999-01-01
Wilhelm Neumann ئ iseõppija. Riias: ilmunud uurimused, töö oma projekti järgi ehitatud Läti kunstimuuseumi direktorina. Neumanni vaid Eesti kunstipärandit käsitlevad uurimused. Neumann ئ muinsuskaitsetegevuse algataja Baltimaadel, tema töid muinsuskaitse alal Eestis. W. Neumann arhitektina
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Hiina põlevkivikeemikud uurisid VKG tootmist / Peeter Lilleväli
Lilleväli, Peeter
2004-01-01
Ilmunud ka: Severnoje Poberezhje, 26. aug. 2004, lk. 1. Fushun Mining Group Co. Ltd juht Yin Liangi sõnul on nende firma tegelenud põlevkivist õli tootmisega üle 40 aasta, kuid kuna Eesti kogemus on sellel alal kaks korda pikem, huvituvad nad siin kasutatavast tehnoloogiast
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Männikusse kasvatatud Rannametsa / Risto Kozer
Kozer, Risto
2009-01-01
Rannametsa elamukompleks (2 kortermaja, 4 ridaelamut, 3 eramut) Vääna-Jõesuus endise pioneerilaagri "Energia" alal. Arhitektid: Jüri Okas, Marika Lõoke, AB J. Okas & M. Lõoke. Ehitaja: AS YIT Ehitus. Projekt: 2005, valmis: 2007. Kompleks on valatud betoonist, mille juures on kasutatud puitlaudiseid ja alumiiniumviimistlust
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Kristi Salve kaitses doktoriväitekirja / Mall Hiiemäe
Hiiemäe, Mall, 1937-
2000-01-01
Kristi Salve kaitses 20. dets.̀1999 Tartu Ülikooli kirjanduse ja rahvaluule osakonnanõukogu ees väitekirja : Läänemeresoomlaste traditsiooniline vaimne kultuur : pärimusliikide vahelised seosed ja etnilised suhted / Kristi Salve. Tartu, 1999. 287 lk. Talle omistati doktorikraad folkloristika alal hinnanguga summa cum laude
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2007-01-01
Vestlusringis on maavalitsuse haridus- ja kultuuriosakonna peaspetsialist Anita Punamäe, Parksepa lasteaia juhataja Anu Sarap, Päkapiku lasteaia juhataja asetäitja õppekasvatustöö alal Ester Peterson, Sõlekese lasteaia õpetaja Sire Kala, lapsevanem ja lasteaia Punamütsike hoolekogu liige Consuelo Laanemäe-Räim
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Jagatud rõõm on alati kõige suurem! : [muljeid koertevõistluselt] / Aivo Oblikas
Oblikas, Aivo, 1970-
2009-01-01
23. - 24. mail 2009. a. toimusid Saksamaal Apoldas IDC (International Dobermann Club) MM-võistlused IPO-s. IPO on koeraspordiala, mis koosneb koera ja koerajuhi koostööst 3 alal: jälg, kuulekus ja kaitse. Eestit esindasid Aivo Oblikas ja tema koer Deli, kes saavutasid 10. koha
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Художники Кюгельгены. Ч. I-II / Марат Гайнуллин, Александра Мурре
Гайнуллин, Марат, 1933-
2010-01-01
Saksa kunstnikest, Venemaal, sh. Eesti alal elanud ja töötanud kaksikvendadest Karl Ferdinand ja Gerhard Franz Kügelgenist ning nende kunstnikest järglastest Wilhelm von Kügelgenist (Gerhard Franzi poeg), Konstantin von Kügelgenist (Karl Ferdinandi poeg) ning viimase tütrest Sally von Kügelgenist
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Tööjõu probleem pole laologistika valdkonnas enam nii terav / Roger Allas
Allas, Roger
2008-01-01
Ilmunud ka: Delovõje Vedomosti 12. märts lk. 25. Konverentsil Laoseis 2008 nenditi, et tööjõu olukorra paranemist on soosinud vaikne seis kinnisvaraturul ja majanduse stabiliseerumine, mistõttu on tekkinud turule hulganisti töökäsi, kes varem tegutsesid ehituse alal
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Rozhdestvo kruglõi god / Jevgenia Gorski
Gorski, Jevgenija
2008-01-01
Pirital Eesti Näituste messikeskuses paralleelselt toimuvatel sisustus- ja mööblimessil "Interjöör 2008" ning aiandusmessil "Aiandus & haljastus 2008" nähtust. Messi Interjöör Eesti Alal näidati Eestis toodetud mööblit. Aiandusmessil toimus konkurss parimale aiaväravale
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Koovit, Kaja, 1968-
2011-01-01
Austrias asuva Linzi ülikooli uuringu kohaselt moodustab varimajandus Eesti majandusest kolmandiku. SSE Riga ehk Stockholmi majanduskooli Riias Balti varimajanduse uuringu põhjal võib varimajanduse osakaal Eestis olla 19,4 protsenti. Varimajanduse alal maailma juhtivaks eksperdiks peetava Friedrich Schneideri uuringust. Marje Josingu ja Juhan Partsi hinnanguid. Tabel: Varimajandus
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Afganistan vajab liitlasvägede abi veel aastaid / Holger Roonemaa
Roonemaa, Holger
2007-01-01
Kuigi liitlasväed tegutsevad Afganistanis juba märksa laiemal alal kui aastaid tagasi, on koalitsioonivägede kohalolek veel aastaid riigile vajalik. Taliban jätkab aktiivset vastupanu ning on alustanud ka infosõda. Kaart. Lisa: Võitlus südamete ja mõistuse pärast; Oopiumitoodang suureneb
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Mällo, Sven
2008-01-01
Maailma ühe suurema geneerilisi ravimeid tootva firma Sandoz D. D. Eesti, Läti ja Leedu filiaali juht räägib oma haridusteest, tööst arstina, karjäärist ravimite müügi alal, perekonnast, hobidest. Kommenteerib kursusekaaslane, Eesti Kohtuekspertiisi instituudi direktor Üllar Lanno
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Volta alale kerkib uhke elurajoon / Ann-Marii Nergi
Nergi, Ann-Marii
2011-01-01
Põhja-Tallinnas asuva Volta kvartali detailplaneeringu eskiis on linnavalitsuses kooskõlastatud. Volta kvartali ideekonkursi võitis Soome arhitektibüroo AW². Detailplaneeringu koostaja, ConArte AB juhatuse liikme Tiina Vilbergi ja AS-i Volta tegevdirektori Aivar Reiviku kommentaarid
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Aktuaalsetest tendentsidest elektroakustilise muusika alal Eestis / Gerhard Lock
Lock, Gerhard, 1978-
2007-01-01
Elektroakustilise muusika lähiajaloost, elektroakustilist muusikat viljelevatest Eesti heliloojatest. Age Hirv, Raun Juurikas, Liis Jürgens, Andrus Kallastu, Tatjana Kozlova, Ülo Krigul, Margo Kõlar, Märt-Matis Lill, Gerhard Lock, Hans-Gunter Lock, Malle Maltis, Jüri Reinvere, Mart Siimer, Mirjam Tally, Toomas Trass, Lauri-Dag Tüür oma muusikast
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Vedru, Gurly, 1970-
2009-01-01
Kaevamistest Harjumaal Saha külas ja Raplamaal Kalbu külas. Sahas uuriti keskaegset kivist kabeliaeda. Kalbu külas toimusid päästekaevamised Räägu-Uueotsa talu alal paikneval kalmel. Leitud müntide põhjal võib oletada, et Kalbu kalmesse maeti 17. sajandil ning 18. saj. algul
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2006-01-01
2006. a. novembris ilmuvast Albert Jacksoni ja David Day "Puutöömeistri käsiraamatust". Albert Jackson ja David Day omandasid magistrikraadi mööblidisaini alal Londoni Kuninglikus Kunstikolledzhis. Raamatut on aidanud eesti lugejateni tuua Uku Velbri, kes 1991. a. lõpetas Tallinna Tehnikaülikoolis puidutöötlemise eriala
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Eesti fond rahastab Vene infotehnoloogiat / Andres Reimer
Reimer, Andres
2006-01-01
Martinson Trigon Venture Partners (MTVP) loob uue tarkvarainvesteeringute fondi, mis viib endise NSVL-i alale kuni 780 miljonit krooni, fond võtab sihiks kümmekond uut ettevõtet. MTVP esimese fondi investeeringutest. Fondide juhi Andres Susi selgitusi. Lisa: Martinson Trigon Venture Partners osalusega firmad; Vt. samas: Moskvas pole raha ja geeniused kohtunud
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Birgy Lorenz julgustab nutiseadmeid hariduse heaks tööle rakendama / Ada Maltseva
Maltseva, Ada, 1970-
2016-01-01
Vestlusest algatuse "Nutitund igasse kooli!" eestvedaja, Tallinna Pelgulinna gümnaasiumi IT-arendusjuhi ja õpetaja Birgy Lorenziga nutitunni projektist. Ta on Eesti informaatikaõpetajate seltsi juhatuse liige, Tallinna ülikooli lektor nuti- ja digiturbe alal ning ka sealse digiturbe labori projektijuht. Netiturvalisust uurib ta oma doktoritöös "Teismelise internetikasutaja turvastrateegiad"
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Directory of Open Access Journals (Sweden)
Ghorban Asgari
2013-08-01
Full Text Available Electrocoagulation (EC and Electrocoagulation/flotation (ECF processes are simple and efficient in water and wastewater treatment. In recent years, many investigations have focused on the use of these processes for treating of polluted water. The purpose of this study was to investigate the efficiency of EC and ECF processes in removal of high turbidity water using different electrodes in different circumstances. In present study an electrocoagulation and electrocoagulation/ flotation reactor in a lab scale to an approximate volume of 6 liters which is equipped with four Al-AL and Fe-Fe electrodes (200 * 20 * 2 mm was used for removing of high turbidity water. The effects of operating parameters such as type of electrodes, initial water turbidity, applied voltage (10 to 30 v, initial pH of the solution (3 to 12 and reaction times (5 to 30 minutes were evaluated. The batch experimental results showed that initial turbidity water, initial pH of the solution, different applied voltages up to %88 turbidity as initial turbidity of 1200 NTU have been removed when using Al-Al and Fe-Fe electrodes and reaction times highly effective on the turbidity removal efficiency in these processes. In ECF process, 84% in optimum condition. However, in EC process the maximum removal was found up to 68% of initial turbidity when using Al-Al and Fe-Fe electrodes in same operation. Based on the result obtained in this study, the type of electrodes in EC and ECF processes significantly affect the removal rate of high turbid water. Also, it was found that much higher turbidity removal could be achieved by ECF process than that by EC process in the same condition.
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Corrosion behavior of aluminum-alumina composites in aerated 3.5 percent chloride solution
Acevedo Hurtado, Paul Omar
Aluminum based metal matrix composites are finding many applications in engineering. Of these Al-Al2O3 composites appear to have promise in a number of defense applications because of their mechanical properties. However, their corrosion behavior remains suspect, especially in marine environments. While efforts are being made to improve the corrosion resistance of Al-Al2O3 composites, the mechanism of corrosion is not well known. In this study, the corrosion behavior of powder metallurgy processed Al-Cu alloy reinforced with 10, 15, 20 and 25 vol. % Al2O3 particles (XT 1129, XT 2009, XT 2048, XT 2031) was evaluated in aerated 3.5% NaCl solution using microstructural and electrochemical measurements. AA1100-O and AA2024T4 monolithic alloys were also studied for comparison purposes. The composites and unreinforced alloys were subjected to potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) testing. Addition of 25 vol. % Al2O 3 to the base alloys was found to increase its corrosion resistance considerably. Microstructural studies revealed the presence of intermetallic Al2Cu particles in these composites that appeared to play an important role in the observations. Pitting potential for these composites was near corrosion potential values, and repassivation potential was below the corresponding corrosion potential, indicating that these materials begin to corrode spontaneously as soon as they come in contact with the 3.5 % NaCl solution. EIS measurements indicate the occurrence of adsorption/diffusion phenomena at the interface of the composites which ultimately initiate localized or pitting corrosion. Polarization resistance values were extracted from the EIS data for all the materials tested. Electrically equivalent circuits are proposed to describe and substantiate the corrosive processes occurring in these Al-Al2O 3 composite materials.
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Laigu, Tõnu, 1956-
2011-01-01
27.-28.10. 2009 toimus Eesti Arhitektuurikeskuse linnafoorumite projekti avaüritus alal, kus saavad kokku Tallinna kesklinn, vanalinn, bastionivöönd ning lähim mereäär. Foorumi ülesandeks oli aidata kaasa kesklinna avardamisele mere suunas. Kujunenud olukorrast. Käsitletavat ala mõjutavad arengud. Foorumil väljapakutud linnalahendused
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Vaiklate ühine käejoon / Piret Veigel-Sepman
Veigel-Sepman, Piret
1999-01-01
Eesti sisearhitektidest Tüüne-Kristin ja Urmo Vaiklast. 1992. a. lõid Vaikla Stuudio, mis tegutseb interjööridisaini ja graafilise disaini alal. Viimasest suurest tööst: Raivo Puusepa projekteeritud Al Mare tervise- ja vaba aja keskuses asuva tervisespordiklubi Status Clubi sisekujundusest. Kujunduse läbiv idee on laev. 4 illustratsiooni
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Moazzami-Gudarzi, Mohsen; Adam, Pavel; Smith, Alexander M; Trefalt, Gregor; Szilágyi, István; Maroni, Plinio; Borkovec, Michal
2018-04-04
Direct force measurements involving amidine latex (AL) and sulfate latex (SL) particles in aqueous solutions containing multivalent ferrocyanide anions are presented. These measurements feature three different pairs of particles, namely SL-SL, AL-SL, and AL-AL. The force profiles are quantitatively interpreted in terms of the theory by Derjaguin, Landau, Verwey, and Overbeek (DLVO) that is combined with a short-ranged exponential attraction. In monovalent salt solutions, the AL particles are positively charged, while the SL particles are negatively charged. In solutions containing ferrocyanide, the charge of the AL particles is reversed as the concentration is increased. The longer-ranged component of all force profiles is fully compatible with DLVO theory, provided effects of charge regulation are included. At shorter distances, an additional exponential attraction must be introduced, whereby the respective decay length is about 2 nm for the AL-AL pair, and below 1 nm for the SL-SL pair. This non-DLVO force is intermediate for the asymmetric AL-SL pair. These additional forces are probably related to charge fluctuations, patch-charged interactions, or hydrophobic forces.
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Tiwary, C. S.; Chakraborty, S.; Mahapatra, D. R.; Chattopadhyay, K.
2014-05-01
This paper attempts to gain an understanding of the effect of lamellar length scale on the mechanical properties of two-phase metal-intermetallic eutectic structure. We first develop a molecular dynamics model for the in-situ grown eutectic interface followed by a model of deformation of Al-Al2Cu lamellar eutectic. Leveraging the insights obtained from the simulation on the behaviour of dislocations at different length scales of the eutectic, we present and explain the experimental results on Al-Al2Cu eutectic with various different lamellar spacing. The physics behind the mechanism is further quantified with help of atomic level energy model for different length scale as well as different strain. An atomic level energy partitioning of the lamellae and the interface regions reveals that the energy of the lamellae core are accumulated more due to dislocations irrespective of the length-scale. Whereas the energy of the interface is accumulated more due to dislocations when the length-scale is smaller, but the trend is reversed when the length-scale is large beyond a critical size of about 80 nm.
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2003-01-01
Vestlus noorte graafikutega nende õpingutest, tööst graafilise disain alal, disainist, disainist Tartus - Peeter Paasmäe (1963), Andres Rõhu (1965), Mari Ainsoo (1975), Martin Lazarev ehk Lazer (1977), Martin Rästa ehk Mammut (1980), Lauri Järvlepp ehk Mõmmar (1980) ja rühmitus D'Art: Risto Kalmre (1982), Pent Talvet (1983), Timo Toots (1982)
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Müüdid ja tegelikkus / Stanley Davis Phillips
Phillips, Stanley Davis
2007-01-01
USA suursaadik Eestis väidab, et kliimamuutustega seonduv on üks enim valesti mõistetud USA poliitika valdkond. Suursaadik kummutab müüdid, nagu teeks Euroopa rohkem kui USA, et vähendada oma tegevuse mõju kliimale, ning nagu ei teeks USA teiste riikidega koostööd kliimamuutuste alal. Lisa: Saksamaa ettepanek
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Haak, Arvi
2007-01-01
Kaevamistest ordulinnuses, uuringutest III eeslinnusel (Esimesel Kirsimäel) peavärava piirkonnas, järelevalvetöödest linnusest lääne poole jääval alal, uuringutest Tartu tänav 28A ja 30 kruntidel. Keraamikaleidude põhjal tekkis asustus Tartu tänav 30 piirkonnas 14. sajandi teisel poolel või veelgi varem
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Tammis, Toomas, 1969-
2010-01-01
Üle-Euroopalisest arhitektuurivõistlusest Europan. Noorte avalikel arhitektuurivõistlustel osalemise võimalustest Eesti, Eesti riigihangete süsteemist arhitektuuri ja linnaplaneerimise vallas. Võistlusest Europan 10 Tallinnas. Linnahalli ja Kultuurikatla vahelisele alale tuli kavandada Kalamaja kalaturg ning ala siduda ümbritseva linnastruktuuriga. Max Cohen De Lara ja David Mulderi (Holland) võidutööst "Green Cement"
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Pärnus avati monument süütusele
1999-01-01
Andrus Joonase Pootsi paepäevade raames valminud monument süütusele avati Academia Non Grata teise aastapäeva puhul Lepa kaubamaja ja karja tänava vahelisel alal; autori arvates on hingeline süütus kunstnikule väga tähtis ja Academia Non Grata ainus õppeasutus, kus õpilased seda hoida saavad.
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2014-01-01
Saku gümnaasiumis arutleti õpilaste korraldatud foorumil Eesti hariduse oleviku ja tuleviku üle. Intervjuu külalisesinejatega, kelleks tänavu olid haridus- ja teadusministeeriumi üldharidusosakonna peaekspert Kersti Kivirüüt, Epp Adler MTÜ-st HeadEst, Saku abivallavanem haridus-, kultuuri- ja sotsiaalhoolekande alal Andi Einaste ning Harju maavalitsuse haridus- ja sotsiaalosakonna juhataja Maris Liiders
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DEFF Research Database (Denmark)
Bizzarro, Martin; Haack, H.; Baker, J.A.
2005-01-01
. Initial Al/Al values range from (1.26 ± 0.37) × 10 to (5.12 ± 0.81) × 10 at the time of magmatism on the EPB and MPB, and are among the highest Al abundances reported for igneous meteorites. These results indicate that widespread silicate melting and differentiation of rocky bodies occurred within 3...
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2015-01-01
Arheoloogilisi kaevamisi teostati umbes 750 m2 alal. Leiti 104 matust. Täiskasvanute matuste hulgas oli ebaproprtsionaalselt palju mehi. Kõige tõenäolisemalt võib tegemist olla sõjameeste kalmistuga. Järelvalvetöödel tuvastati ja dokumenteeriti Narva linna varauusaegsed kaitserajatised ning suudeti ka kindlaks määrata 19. sajandil rajatud Peetri värava asukoht ning ehitusviis
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Robert J. Aumann - matemaatikust Nobeli preemia laureaat / Peeter Puusemp
Puusemp, Peeter, 1947-
2006-01-01
2005. a. Nobeli preemia majanduse alal silmapaistva panuse eest mänguteooria ülesannete lahendamisse saanud Robert J. Aumannist ja D. Saari loetelu matemaatikutest - Nobeli preemia laureaatidest: John Nash'ist, Herbert Hauptman'ist, John Pople'ist, Bertrand Arthur William Russell'ist, Kenneth Joseph Arrow'ist, Gerard Debreu'ist, Leonid Vitaljevitš Kantorovitš'ist, Reinhard Selten'ist, Jan Tinbergen'ist
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2003-01-01
9.01.2002 kaitsesid Tallinna Pedagoogikaülikooli kultuuriteaduskonna doktorinõukogu ees väitekirja Aivar Jürgenson ja David Vseviov, kellele anti filosoofiadoktori kraad kultuuriajaloo alal. A. Jürgensoni väitekiri oli teemal "Siberi eestlaste territoriaalsus ja identiteet", D.Vseviovi väitekirja teema oli "Kirde-Eesti urbaanse anomaalia kujunemine ning struktuur pärast Teist maailmasõda"
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Photon-assisted Tunneling In Double-barrier Superconducting Tunnel-junctions
Dierichs, M. M. T. M.; Dieleman, P.; Wezelman, J. J.; Honingh, C. E.; Klapwijk, T. M.
1994-01-01
Double-barrier Nb/Al2O3/Al/Al2O3/Nb tunnel junctions are used as mixing elements in a 345 GHz waveguide mixer. Noise temperatures (double side band) down to 720 K at 3.0 K are obtained without the need to apply a magnetic field to suppress the Josephson current. It is shown that the composite
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Merirahu elamurajoon Tallinnas = Merirahu Residential Community in Tallinn / Triin Ojari
Ojari, Triin, 1974-
2008-01-01
Projekteerija: Rein Murula Arhitektuuribüroo OÜ. Autorid: Rein Murula, Marti Kahu, Karl Koosa. Konstruktor: Pikoprojekt OÜ. Projekt: 2005-2006, valmis: I etapp 2006, II etapp 2007. Rein Murula korterelamute ehitamisest algselt ühepereelamute ehitamiseks mõeldud alale, majatüüpidest, lodzhadest, korteritest. I ja II majatüübi I-IV korruse plaan, 4 värv. välisvaadet
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Effect of Sintering Temperature on the Properties of Aluminium-Aluminium Oxide Composite Materials
Directory of Open Access Journals (Sweden)
Dewan Muhammad Nuruzzaman
2016-12-01
Full Text Available In this study, aluminium-aluminium oxide (Al-Al2O3 metal matrix composites of different weight percentage reinforcements of aluminium oxide were processed at different sintering temperatures. In order to prepare these composite specimens, conventional powder metallurgy (PM method was used. Three types specimens of different compositions such as 95%Al+5%Al2O3, 90%Al+10%Al2O3 and 85%Al+15%Al2O3 were prepared under 20 Ton compaction load. Then, all the specimens were sintered in a furnace at two different temperatures 550oC and 580oC. In each sintering process, two different heating cycles were used. After the sintering process, it was observed that undistorted flat specimens were successfully prepared for all the compositions. The effects of sintering temperature and weight fraction of aluminium oxide particulates on the density, hardness and microstructure of Al-Al2O3 composites were observed. It was found that density and hardness of the composite specimens were significantly influenced by sintering temperature and percentage aluminium oxide reinforcement. Furthermore, optical microscopy revealed that almost uniform distribution of aluminium oxide reinforcement within the aluminium matrix was achieved.
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Chen, Cunguang; Wang, Wenwen; Guo, Zhimeng; Sun, Chunbao; Volinsky, Alex A.; Paley, Vladislav
2018-03-01
Microstructure evolution and variations in mechanical properties of Al-Al2O3 nanocomposite produced by powder metallurgy were investigated and compared with commercially pure aluminum (Al-1050) after furnace annealing. Fine gas-atomized Al powder compacts were first sintered in flowing nitrogen, subsequently consolidated into wires by rotary swaging and eventually annealed at 300 and 500 °C for 24 h each. Scanning and transmission electron microscopy with energy-dispersive spectroscopy was utilized to document the microstructure evolution. Rotary swaging was proven to lead to a marked decrease in grain size. After heavy swaging to true deformation degree of φ = 6 and annealing at 500 °C, obvious recrystallization was observed at Al-1050's existing grain boundaries and the crystals began to grow perpendicular to the flow direction. In the Al-Al2O3 nanocomposite, fabricated from d 50 = 6 μm Al powder, recrystallization partially occurred, while grains were still extremely fine. Due to the dual role of fine-grained Al2O3 dispersion strengthening, the nanocomposite showed improved mechanical performance in terms of tensile strength, approximately twice higher than Al-1050 after annealing at 500 °C.
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Siva Sankara Raju, R.; Panigrahi, M. K.; Ganguly, R. I.; Srinivasa Rao, G.
2017-08-01
The present investigation develops a next-generation hybrid Al metal matrix composite using coconut shell ash (CSA) and graphite (Gr) reinforcement. Stir-casting is adapted to prepare an Al-1100-based composite. Three other composites of Al-Al2O3, Al-Al2O3-Gr, and Al-CSA are prepared that contain equivalent volume fractions of Al2O3, CSA, and Gr. These assist in comparisons among the three composites and the developed hybrid Al-CSA-Gr composite. The study reveals that the addition of 3 pct Gr improves the specific strength, toughness, and tribological properties. The Al-CSA composite shows better mechanical properties, such as tensile strength and hardness, than the other three composites. Gr addition helps the hybrid Al-CSA-Gr composite to attain better tribological properties with a slightly lower specific strength. Scanning electron microscopy studies of the worn material surfaces corroborate the findings of the abrasion testing. Elemental analyses by energy-dispersive X-ray spectroscopy of the debris from the counter-face of the tribo surface confirm the presence of Al, O, Si, Fe, Mn, and C.
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International Nuclear Information System (INIS)
Asta, M.; Foiles, S.M.; Quong, A.A.
1998-01-01
The configurational thermodynamic properties of fcc-based Al-Sc alloys and coherent Al/Al 3 Sc interphase-boundary interfaces have been calculated from first principles. The computational approach used in this study combines the results of pseudopotential total-energy calculations with a cluster-expansion description of the alloy energetics. Bulk and interface configurational-thermodynamic properties are computed using a low-temperature-expansion technique. Calculated values of the {100} and {111} Al/Al 3 Sc interfacial energies at zero temperature are, respectively, 192 and 226mJ/m 2 . The temperature dependence of the calculated interfacial free energies is found to be very weak for {100} and more appreciable for {111} orientations; the primary effect of configurational disordering at finite temperature is to reduce the degree of crystallographic anisotropy associated with calculated interfacial free energies. The first-principles-computed solid-solubility limits for Sc in bulk fcc Al are found to be underestimated significantly in comparison with experimental measurements. It is argued that this discrepancy can be largely attributed to nonconfigurational contributions to the entropy which have been neglected in the present thermodynamic calculations. copyright 1998 The American Physical Society
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Investigation of lime production sites in the historic Kursi parish / Andres Tvauri, Tanel Saimre
Tvauri, Andres, 1970-
2007-01-01
Lubi võeti Eesti alal ehitusmaterjaline kasutusele 13. sajandil seoses Saksa-Taani vallutusega. Välitööde tulemusena leiti kaks hästi säilinud lubjaahju koos paemurdudega. Üks nendest, Kaave jõe läänekaldal asuv ahi, osutus väga hästi säilinud kompleksiks. Senistel andmetel näib, et uuritud ahi pärineb 13.-18. sajandist.
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Pair potentials for alumina from ab initio results on the Al2O3 molecule
International Nuclear Information System (INIS)
Akdeniz, Z.; Cicek, Z.; Tosi, M.P.
2000-08-01
We use results from an ab initio investigation by Chang et al. on energetically low-lying stationary points of the Al 2 O 3 molecule to determine interionic potentials for the Al-O, O-O and Al-Al pairs. Our results are discussed in the perspective of previous studies of the condensed phases of alumina, with special regard to the structure of its molten state. (author)
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Buddolog Otton Ottonovitsh Rozenberg i Estonia / Mart Läänemets
Läänemets, Mart
2006-01-01
Vana-Liivimaal sündinud ülemaailmse tuntusega orientalist Otto Rosenberg arendas edasi Vassili Vassiljevi ideed "graafilisest alfabeedist" - hieroglüüfide järjestatusest nende graafiliste elementide järgi, temast sai Peterburi ülikooli esimene doktor jaapani keele ja kirjanduse alal, ta suri Tallinnas 26. novembril 1919 ja maeti Kopli kalmistule. Lisatud dokumendid, mis tõestavad tema surma 1919. aasta sügisel Tallinnas
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Jah, proua president / Aune Past
Past, Aune, 1954-
2006-01-01
SL Õhtuleht valis välja seitse daami, kes võiksid kandideerida ja saada Eesti Vabariigi presidendiks: Marju Lauristin, Siiri Oviir, Ingrid Rüütel, Ene Ergma, Mari-Ann Kelam, Vilja Savisaar ja Maimu Berg. Avalikkussuhete ja teabekorralduse lektor Aune Past toob välja nende positiivsed küljed ning annab nõu, mis alal võiks iga daam end täiustada
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Archaeological investigations in the inner courtyard of the puppet theatre 'Nuku' / Eero Heinloo
Heinloo, Eero
2014-01-01
Leidude põhjal võib rääkida puithoonestusest 13. sajandist, mis 14. sajandi lõpus asendati kivihoonestusega. Aktiivsem elutegevus on antud alale iseloomulik alates 14. sajandi keskpaigast. Keskaegse hoone kohale rajati 17. sajandi alguses uus kivihoone. 19. sajandi alguses krundil asunud kivihooned lammutati ja nende asemele rajati uued kivihooned. Leidudest moodustavad enamiku importkeraamika katkendid. Muust leiuainesest võib esile tõsta puitleide
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Ultrasonic spot welding of Al/Mg/Al tri-layered clad sheets
International Nuclear Information System (INIS)
Macwan, A.; Patel, V.K.; Jiang, X.Q.; Li, C.; Bhole, S.D.; Chen, D.L.
2014-01-01
Highlights: • The optimal welding condition is achieved at 100 J and 0.1 s. • Failure load first increases and then decreases with increasing welding energy. • The highest failure load after welding is close to that of the clad sheets. • At low energy levels failure occurs in the mode of interfacial failure. • At high energy levels failure takes place at the edge of nugget region. - Abstract: Solid-state ultrasonic spot welding (USW) was used to join Al/Mg/Al tri-layered clad sheets, aiming at exploring weldability and identifying failure mode in relation to the welding energy. It was observed that the application of a low welding energy of 100 J was able to achieve the optimal welding condition during USW at a very short welding time of 0.1 s for the tri-layered clad sheets. The optimal lap shear failure load obtained was equivalent to that of the as-received Al/Mg/Al tri-layered clad sheets. With increasing welding energy, the lap shear failure load initially increased and then decreased after reaching a maximum value. At a welding energy of 25 J, failure occurred in the mode of interfacial failure along the center Al/Al weld interface due to insufficient bonding. At a welding energy of 50 J, 75 J and 100 J, failure was also characterized by the interfacial failure mode, but it occurred along the Al/Mg clad interface rather than the center Al/Al weld interface, suggesting stronger bonding of the Al/Al weld interface than that of the Al/Mg clad interface. The overall weld strength of the Al/Mg/Al tri-layered clad sheets was thus governed by the Al/Mg clad interface strength. At a welding energy of 125 J and 150 J, thinning of weld nugget and extensive deformation at the edge of welding tip caused failure at the edge of nugget region, leading to a lower lap shear failure load
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Korporatiivspaa koolitab tallinlastest tallinklasi / Urmas Oja
Oja, Urmas, 1981-2012
2007-01-01
Tallink Spa & Conference Hotel Tallinnas Sadama 11a. Arhitektid: Indrek Tiigi, Ülar Mark, AB Urban Mark. Sisearhitektid: Andro Kööp, Tairo Pärnamets, SAB Torpedo Interior. Ehituse peatöövõtja: AS Merko Ehitus. Hotellitubade seintel on Heiki-Erich Merila fotod, spaa-alal Hannes Starkopfi kujud. Ehituse kestus: veebruar 2006-märts 2007. A. Kööbi ja I. Tiigi kommentaar. Välisvaade, 5 sisevaadet
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Tvauri, Andres, 1970-
2014-01-01
Kogu Munga tänava alal oli jälgitav punase liiva kihistus. Varasemate uuringute põhjal on teada, et see sillutis pärineb keskajast. Sillutise alune kiht sisaldas leide, mida võib dateerida 13. sajandi keskpaigast 14. sajandi keskpaigani. Sillutise pealne kiht sisaldas rohkesti leide 16. sajandi teisest poolest. Sepa tänava lääneküljel avastati keskaegse kivihoone müürid.
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2017-07-25
Fluid resuscitation Prompt fluid resuscitation is the first-line therapy to restore the lost intra- vascular volume. As blood products are often...Increased cell survival, and decreased apoptosis and necrosis TBI animal model Dekker et al., 2014b Spinal cord injury animal model Abdanipour et al...AL. were mapped to, among others, pathways related to cell death, apopto- sis, and necrosis (Dekker, 2014b). These findings support our hypothe- sis
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Environmental changes during Frasnian-Famennian transition in south China: A multiproxy approach
Xu, Bing; Gu, Zhaoyan; Han, Jingtai; Wang, Chengyuan
2008-12-01
This study presents high-resolution multiproxy analyses on two Late Devonian sequences for characterizing the environmental changes during the Frasnian-Famennian (F-F) transition in south China. Carbon isotope signatures of the carbonate and organic matter consistently show two positive excursions in the late rhenana zone and around the F-F boundary, implying two increased organic carbon burial events. These observations are consistent with the records from other continents, providing further support for the documented perturbations of the global carbon cycle. Redox indices, mainly of the Cu/Al and U/Al ratios, and hydrothermal-volcanic proxies, Al/(Al + Fe) and Zr/Al, indicate reducing conditions and increased hydrothermal-volcanic activities during these carbon isotope excursions. High-resolution investigations revealed that the reducing conditions predate the onset of the carbon isotope excursions, suggesting that the two positive carbon isotope shifts are likely caused by the expansion of anoxic conditions. The low Al/(Al + Fe) ratio around the F-F boundary leads the U/Al and Cu/Al anomalies in timing, implying that this anoxic event might have resulted from a long-term cumulative effect of intense hydrothermal-volcanic activities. In the late rhenana zone, enhanced hydrothermal activity also seems responsible for the reducing conditions.
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Effect of length scale on mechanical properties of Al-Cu eutectic alloy
Tiwary, C. S.; Roy Mahapatra, D.; Chattopadhyay, K.
2012-10-01
This paper attempts a quantitative understanding of the effect of length scale on two phase eutectic structure. We first develop a model that considers both the elastic and plastic properties of the interface. Using Al-Al2Cu lamellar eutectic as model system, the parameters of the model were experimentally determined using indentation technique. The model is further validated using the results of bulk compression testing of the eutectics having different length scales.
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Raadiomängud Eestis Teise maailmasõja ajal ja järel. 1.-7. osa / Jaak Pihlau
Pihlau, Jaak, 1937-2014
2010-01-01
Luureoperatsioonidest Teise maailmasõja ajal. Eesti territooriumiga seotud Abwehr'i luuregruppidest ja Eesti alal Teise maailmasõja ajal tegutsenud luurekoolidest. Raadiomängudest (Blind, Sever, Javka jm.). Eestlastest Saksa Soome luureüksustes. Lennuoperatsioone alustamine USA poolt Leetu 1950. aastal. USA ja Briti luurejuhtide kohtumisest Münchenis. Eesti agentide saabumisest Lätti. Briti-Eesti luureagentide saabumisest Eestisse 1952. aastal. Eesti NSV Riikliku Julgeoleku Ministeeriumi poolt alustatud raadiomängust "Universitet", hilisema nimega "Berkut". USA luureoperatsioonidest Leetu ja Eestisse
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Keskpolügooni umbsõlme lahendamisel viimane vaatus / Hannes Krause
Krause, Hannes
2006-01-01
Kaitseministeerium ja Kuusalu vald saavutasid kohtus võidu kolme maaomaniku üle, kellel on maatükk keskpolügooni alal. Kaitseministeerium peab veel läbirääkimisi 36 perekonnaga, kellele tehakse pakkumised nende maatükkide kasutusõiguse saamiseks. Vt. samas: Rein Sikk. Polügoon võttis naiselt kaks korda kodu ära. Hannes Krause. Keskpolügooni teeninduskeskuse ehitus käib juba kaks nädalat. Kaart. Kommenteerib Lauri Almann
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From Estonian Exile to Executive Office / Susan Frith
Frith, Susan
2008-01-01
Eesti Vabariigi Presidendi Toomas Hendrik Ilvese elukäigust, haridusteest, poliitilistest vaadetest. T. H. Ilves lõpetas Pennsylvania ülikooli psühholoogia alal magistrikraadiga 1978. a. Artiklis on kasutatud telefoniintervjuud presidendiga. T. H. Ilvese kohta avaldavad arvamust ülikoolikaaslane Brian Wandell ja Eesti Rahvuskomitee Ühendriikides endine president Juhan Simonson. Ülevaade artiklist ilmunud ka: Vaba Eesti Sõna, 24. jaan. 2008, lk. 7, 10: Vaga, Airi. Eesti president Toomas H. Ilves Pennsylvania ülikooli ajakirjas
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Tarkvaraarenduses süveneb ajude nappus / Tõnu Roolaht
Roolaht, Tõnu, 1972-
2008-01-01
Mobiillahenduste ja tarkvaratööstus on Eestis kiiresti arenenud, tegevus on killustunud paljude väikeste ettevõtete ning üksiküritajate vahel. Suuremate ettevõtete jaoks on tõsine komistuskivi kvalifitseeritud spetsialistide vähesus Eestis ning tööjõu globaalse mobiilsuse piirangud. Tuntumad ettevõtted tarkvaraarenduse vallas on Skype, Playtech, Webmedia ja Helmes ning mobiillahenduste alal Mobi Solutions ning Regio. Vt. samas: Mobiil- ja tarkvaraarenduses tegutseb paar tuhat ettevõtet
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Phase equilibria of Al3(Ti,V,Zr) intermetallic system
International Nuclear Information System (INIS)
Park, S.I.; Han, S.Z.; Choi, S.K.; Lee, H.M.
1996-01-01
Trialuminides such as DO 22 -structured Al 3 Ti are promising candidates as potential materials for elevated temperature applications because of their attractive high temperature strength and excellent oxidation resistance along with their low density. However, in the tetragonal structure, slip systems are restricted due to low symmetry and the primary deformation mode is twinning. And, therefore, monolithic trialuminide compounds have been very impractical to be used as structural materials. When transition elements such as Ti, V and Zr which constitute trialuminides are alloyed in aluminum, they have low solubilities and low diffusion coefficients in the Al matrix. If precipitated as trialuminide intermetallics, they maintain a small lattice mismatch with the Al matrix, which reduces the interfacial energy between matrix and precipitates. As a result, these precipitates would have a large coarsening resistance in the matrix. As most of the previous works have been concentrated on the microstructural stability and mechanical properties, thermochemical properties will be treated in this work. In this study, phase equilibria and diagrams of Al 3 (Ti,V,Zr) systems will be experimentally determined and then thermodynamically analyzed with a hope to extend to the Al-Al 3 (Ti,V,Zr) composite system. This approach will then be used as a guide for alloy design of Al-Al 3 (Ti,V,Zr) composite system
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Room Temperature Elastic Moduli and Vickers Hardness of Hot-Pressed LLZO Cubic Garnet
2012-01-01
4140-steel [29] as well as composites such as Al/Al2O3 [30] and Ni– YSZ cermets [27]. The RUS apparatus used in this study consists of a computer...Microstructure and lattice parameter of LLZO specimens In this study , the LLZO microstructure was observed on a (i) fracture surface of LLZO-01 (Fig. 1a) and... study are consistent with the trend (Eq. 2) of a power law decrease in mechanical properties with increasing lattice parameter observed for other garnet
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Archaeological investigations in Tartu and Vorbuse settlement site / Andres Tvauri, Rivo Bernotas
Tvauri, Andres, 1970-
2007-01-01
Uuringutest Küütri tänav 1 hoone fuajees, Püha Jüri kalmistul. Järelevalvest Poe tänaval, kus peaaegu kaevise alal oli jälgitav 15. või 16. sajandi esimesel poolel pandud munakivisillutis. Toomemäe poolses osas tuli nähtavale männipalkidest sillutis 13.-14. sajandist. Kahes kohas dokumenteeriti keskaegset linnamüüri. Järelevalvest Jakobi ja Laia tänava ristmikul ning Lossi tänav 21-/23 krundil. Kaevamistest Vorbuse asulakohal
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Kinetic energy distributions of sputtered neutral aluminum clusters: Al--Al6
International Nuclear Information System (INIS)
Coon, S.R.; Calaway, W.F.; Pellin, M.J.; Curlee, G.A.; White, J.M.
1992-01-01
Neutral aluminum clusters sputtered from polycrystalline aluminum were analyzed by laser postionization time-of-flight (TOF) mass spectrometry. The kinetic energy distributions of Al through Al 6 were measured by a neutrals time-of-flight technique. The interpretation of laser postionization TOF data to extract velocity and energy distributions is presented. The aluminum cluster distributions are qualitatively similar to previous copper cluster distribution measurements from our laboratory. In contrast to the steep high energy tails predicted by the single- or multiple- collision models, the measured cluster distributions have high energy power law dependences in the range of E -3 to E -4.5 . Correlated collision models may explain the substantial abundance of energetic clusters that are observed in these experiments. Possible influences of cluster fragmentation on the distributions are discussed
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Thermal Analysis of a Power Conditioning Unit for a Howitzer
2009-08-01
contact resistance Interface ( mA2 -K / W) AL-PCB 0.000389 AL-AL (thermal grease) 0.000083 AL-power chips 0.003891 AL-power chips (thermal grease...1120 W/ mA2 . Figure 3 shows the view of the box that the source of the solar radiation sees. The inside of the box is cluttered with cables, wiring, and...temperature (130°F) and a conservative convective heat transfer coefficient (5 W/ mA2 ) to all of the outer surfaces. These outer surfaces would
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Directory of Open Access Journals (Sweden)
J. Cumin
2018-01-01
Full Text Available This paper presents the results of Finite Element Method numerical simulation performed onEN-AW5754(AlMg3, EN AW-5019 (AlMg5 plates subjected to mechanical clinching. The goal was to observe differences between aluminum plates in the same tool; and to determine the possibility of using the constructed tool for the clinching of Al-Al material combinations. This tool construction is to be produced and tested in laboratory conditions, to elaborate prospective results, and reach additional conclusions.
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Ishimaru, Satoko; Arai, Shoji; Tamura, Akihiro
2017-11-01
, especially during the subduction of young and hot oceanic lithosphere. Footnote: Mg#, Mg/(Mg + Fe total) atomic ratio; Cr#, Cr/(Cr + Al) atomic ratio; YAl, Al/(Al + Cr + Fe3 +) atomic ratio; YCr, Al/(Al + Cr + Fe3 +) atomic ratio; YFe, Al/(Al + Cr + Fe3 +) atomic ratio. RSD: relative standard deviation. Ref. values: Reference values of JEOL_Kfs from a JEOL database.
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Plasmonic enhancement of UV emission from ZnO thin films induced by Al nano-concave arrays
International Nuclear Information System (INIS)
Norek, Małgorzata; Łuka, Grzegorz; Włodarski, Maksymilian
2016-01-01
Highlights: • Al nano-concave arrays with different interpore distance (D c ) were prepared. • PL of ZnO thin films deposited directly on the Al nano-concaves were studied. • The effect of 10 nm Al 2 O 3 spacer on PL emission from ZnO thin films was analyzed. • Plasmonic enhancement of the PL emission was dependent on the D c and the spacer. • The highest 9-fold enhancement was obtained for the Al/ZnO sample with D c ∼333 nm. - Abstract: Surface plasmons (SPs) supported by Al nano-concave arrays with increasing interpore distance (D c ) were used to enhance the ultraviolet light emission from ZnO thin films. Two sets of samples were prepared: in the first set the thin ZnO films were deposited directly on Al nanoconcaves (the Al/ZnO samples) and in the second set a 10 nm − Al 2 O 3 spacer was placed between the textured Al and the ZnO films (the Al/Al 2 O 3 -ALD/ZnO samples). In the Al/ZnO samples the enhancement was limited by a nonradiative energy dissipation due to the Ohmic loss in the Al metal. However, for the ZnO layer deposited directly on Al nanopits synthesized at 150 V (D c = 333 ± 18 nm), the largest 9-fold enhancement was obtained by achieving the best energy fit between the near band-edge (NBE) emission from ZnO and the λ (0,1) SPP resonance mode. In the Al/Al 2 O 3 -ALD/ZnO samples the amplification of the UV emission was smaller than in the Al/ZnO samples due to a big energy mismatch between the NBE emission and the λ (0,1) plasmonic mode. The results obtained in this work indicate that better tuning of the NBE − λ (0,1) SPP resonance mode coupling is possible through a proper modification of geometrical parameters in the Al/Al 2 O 3 -ALD/ZnO system such as Al nano-concave spacing and the thickness of the corresponding layer. This approach will reduce the negative influence of the non-radiative plasmonic modes and most likely will lead to further enhancement of the SP-modulated UV emission from ZnO thin films.
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High velocity properties of the dynamic frictional force between ductile metals
International Nuclear Information System (INIS)
Hammerberg, James Edward; Hollan, Brad L.; Germann, Timothy C.; Ravelo, Ramon J.
2010-01-01
The high velocity properties of the tangential frictional force between ductile metal interfaces seen in large-scale NonEquilibrium Molecular Dynamics (NEMD) simulations are characterized by interesting scaling behavior. In many cases a power law decrease in the frictional force with increasing velocity is observed at high velocities. We discuss the velocity dependence of the high velocity branch of the tangential force in terms of structural transformation and ultimate transition, at the highest velocities, to confined fluid behavior characterized by a critical strain rate. The particular case of an Al/Al interface is discussed.
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Hemispherical Shell Nanostructures from Metal-Stripped Embossed Alumina on Aluminum Templates
DEFF Research Database (Denmark)
Nielsen, Peter; Albrektsen, Ole; Simonsen, Adam Cohen
2011-01-01
aluminum/ alumina (Al/Al2O3) templates as a novel and versatile nanofabrication procedure, and we demonstrate explicitly how to exploit the technique for developing large-area hexagonally close-packed hemispherical shell nanostructures by stripping noble metal layers from embossed templates fabricated from...... anodized Al. Utilizing for this process the linear relationship between anodization voltage and the resulting interpore distance in the formed oxide, it is possible to tune the radius of curvature of the resulting hemispherical shells continuously, which in turn results in tunable optical properties...
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Kas Eesti avastamine algab Põhja-Eestist? : Põhja-Eesti V turismikonverents
2010-01-01
17. novembril Jõhvi Kontserdimajas toimunud Põhja-Eesti V turismikonverentsist “Kas Eesti avastamine algab Põhja- Eestist?", mille avas Ida-Virumaa maavalitsuse Arengu- ja planeeringuosakonna juhataja Urmas Majaääs. Ülevaade SA Ida-Virumaa Ettevõtluskeskuse turismikoordinaatori Sigrid Karoni, Estonian Airi asepresidendi kommertsalal Rauno Parrase, EASi koordinaatori turismiuuringute alal Piret Kallase, kommunikatsioonikonsultandi Raul Rebase, SA Põhja-Eesti Turism projektijuhi Erika Pääbuse ja nõukogu liikme Moonika Sooneste, CityBike OÜ tegevjuhi Toomas Lelovi, Narva-Jõesuu linnapea Andres Noormägi, Loodusturismi arendaja ja koolitaja Rein Kuresoo ettekannetest
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Cold pressure welding - the mechanisms governing bonding
DEFF Research Database (Denmark)
Bay, Niels
1979-01-01
Investigations of the bonding surface in scanning electron microscope after fracture confirm the mechanisms of bond formation in cold pressure welding to be: fracture of work-hardened surface layer, surface expansion increasing the area of virgin surface, extrusion of virgin material through cracks...... of the original surface layer, and establishment of real contact and bonding between virgin material. This implies that normal pressure as well as surface expansion are basic parameters governing the bond strength. Experimental investigations of pressure welding Al-Al under plane strain compression in a specially...
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Mitmest pilvelõhkujast piisab 9/11 mälestamiseks? / Eda Post
Post, Eda, 1983-
2009-01-01
New Yorgis terroristide hävitatud Maailma Kaubanduskeskuse kaksiktornide alale uue projekti leidmiseks korraldatud võistlusel valiti 2003. a. välja arhitekt Daniel Libeskindi kavand "Memory Foundation", mis nägi ette mälestuskompleksi hukkunutele tornide asukohas ja selle ümber viie uue pilvelõhkuja ehitamise. Tornid projekteerisid David Childs, Norman Foster, Richard Rogers, Fumihiko Maki ja arhitektuuribüroo Kohn Pedersen Fox. Valminud on torn Seitse, 2006. a. algas ehitus peaväljakul. Vaidlusest selle üle, kas on mõistlik viis torni välja ehitada
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Jõgi, Aime, 1958-
2014-01-01
Jaan Poska gümnaasiumis õppiva Meriliin Kade gluteeniteemalist uurimistööd juhendab Tartu tervishoiukõrgkooli 3. kursuse üliõpilane Juliana Baranova. Kokku viis neid Teadmiste värav, Ahhaa keskuse algatus toetamaks koostööd ülikoolide ja üldhariduskoolide vahel
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International Nuclear Information System (INIS)
Kodeli, I.; Diop, C.M.; Nimal, J.C.
1994-01-01
In the framework of future Boron Neutron Capture Therapy (BNCT) experiments, where cells and animals irradiations are planned at the research reactor of Strasbourg University, the feasibility to obtain a suitable epithermal neutron beam is investigated. The neutron fluence and spectra calculations in the reactor are performed using the 3D Monte Carlo code TRIPOLI-3 and the 2D SN code TWODANT. The preliminary analysis of Al 2 O 3 and Al-Al 2 O 3 filters configurations are carried out in an attempt to optimize the flux characteristics in the beam tube facility. 7 figs., 7 refs
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Statistical Analysis Software for the TRS-80 Microcomputer.
1981-09-01
1450 3190 PRINT : INPUT ’Enter Desired Confidence Lvel (e.g. .95)’,AL : IF AL) I THEN AL=AL/100 3200 IF ALCO OR AL)1 THEN PRINT".- ERROR -# ENTER A...4540 PRIX P-Value a’lt IF 1 W OR ZAIsL" PRINT 0OX ELSE PRINT FOX 4=0 PRINTt INPUrinter Desired Alpha LVel "’.AL 4560 17 AL.0 OR AL>1 THEN PEN*T...Abramowitz M. and Stegun, I. A., Handbook of Mathematical Functions, p. 932, National Bureau of Standards, 1964 7. Ibid., p. 941 8. Poole, L. and
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Dielectric properties of DC reactive magnetron sputtered Al2O3 thin films
International Nuclear Information System (INIS)
Prasanna, S.; Mohan Rao, G.; Jayakumar, S.; Kannan, M.D.; Ganesan, V.
2012-01-01
Alumina (Al 2 O 3 ) thin films were sputter deposited over well-cleaned glass and Si substrates by DC reactive magnetron sputtering under various oxygen gas pressures and sputtering powers. The composition of the films was analyzed by X-ray photoelectron spectroscopy and an optimal O/Al atomic ratio of 1.59 was obtained at a reactive gas pressure of 0.03 Pa and sputtering power of 70 W. X-ray diffraction results revealed that the films were amorphous until 550 °C. The surface morphology of the films was studied using scanning electron microscopy and the as-deposited films were found to be smooth. The topography of the as-deposited and annealed films was analyzed by atomic force microscopy and a progressive increase in the rms roughness of the films from 3.2 nm to 4.53 nm was also observed with increase in the annealing temperature. Al-Al 2 O 3 -Al thin film capacitors were then fabricated on glass substrates to study the effect of temperature and frequency on the dielectric property of the films. Temperature coefficient of capacitance, AC conductivity and activation energy were determined and the results are discussed. - Highlights: ► Al 2 O 3 thin films were deposited by DC reactive magnetron sputtering. ► The films were found to be amorphous up to annealing temperature of 550 C. ► An increase in rms roughness of the films was observed with annealing. ► Al-Al 2 O 3 -Al thin film capacitors were fabricated and dielectric constant was 7.5. ► The activation energy decreased with increase in frequency.
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Effect of ionization on the oxidation kinetics of aluminum nanoparticles
Zheng, Yao-Ting; He, Min; Cheng, Guang-xu; Zhang, Zaoxiao; Xuan, Fu-Zhen; Wang, Zhengdong
2018-03-01
Molecular dynamics simulation (MD) of the observed stepwise oxidation of core-shell structured Al/Al2O3 nanoparticles is presented. Different from the metal ion hopping process in the Cabrera-Mott model, which is assumed to occur only at a certain distance from the oxide layer, the MD simulation shows that Al atoms jump over various interfacial gaps directly under the thermal driving force. The energy barrier for Al ionization is found to be increased along with the enlargement of interfacial gap. A mechanism of competition between thermal driving force and ionization potential barrier is proposed in the interpretation of stepwise oxidation behavior.
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Amor nõustab noori seksuaaltervise alal / Triin Raudsepp, Kaie Toomet ; interv. Anne Veskimeister
Raudsepp, Triin
2004-01-01
Pereplaneerimise Liit on 10 aasta jooksul arendanud välja noorte nõustamiskeskuste võrgustiku. 16 keskust kannavad ühisnime Amor. Vestlus noorte nõustamisprogrammi juhi ja internetinõustamise projektijuhiga. Lisa: Noorte nõustamiskeskuste kontaktandmed
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Doktoritöö trammi arvutipõhise juhtimise, seire ja diagnostika alal / Rain Lahtmets
Lahtmets, Rain
2005-01-01
30. aug. kaitses Tallinna Tehnikaülikooli energeetikateaduskonnas oma väitekirja "Kergrööbastranspordi juhtimine, talitusjärelvalve ja diagnostika" elektriajamite ja jõuelektroonika instituudi teadur Argo Rosin
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Stripe-teeth metamaterial Al- and Nb-based rectennas (Presentation Recording)
Osgood, Richard M.; Giardini, Stephen A.; Carlson, Joel B.; Joghee, Prabhuram; O'Hayre, Ryan P.; Diest, Kenneth; Rothschild, Mordechai
2015-09-01
Unlike a semiconductor, where the absorption is limited by the band gap, a "microrectenna array" could theoretically very efficiently rectify any desired portion of the infrared frequency spectrum (25 - 400 THz). We investigated vertical metal-insulator-metal (MIM) diodes that rectify vertical high-frequency fields produced by a metamaterial planar stripe-teeth Al or Au array (above the diodes), similar to stripe arrays that have demonstrated near-perfect absorption in the infrared due to critical coupling [1]. Using our design rules that maximize asymmetry (and therefore the component of the electric field pointed into the substrate, analogous to Second Harmonic Generation), we designed, fabricated, and analyzed these metamaterial-based microrectenna arrays. NbOx and Al2O3 were produced by anodization and ALD, respectively. Smaller visible-light Pt-NbOx-Nb rectennas have produced output power when illuminated by visible (514 nm) light [2]. The resonances of these new Au/NbOx/Nb and Al/Al2O3/Al microrectenna arrays, with larger dimensions and more complex nanostructures than in Ref. 1, were characterized by microscopic FTIR microscopy and agreed well with FDTD models, once the experimental refractive index values were entered into the model. Current-voltage measurements were carried out, showed that the Al/Al2O3/Al diodes have very large barrier heights and breakdown voltages, and were compared to our model of the MIM diode. We calculate expected THz-rectification using classical [3] and quantum [4] rectification models, and compare to measurements of direct current output, under infrared illumination. [1] C. Wu, et. al., Phys. Rev. B 84 (2011) 075102. [2] R. M. Osgood III, et. al., Proc. SPIE 8096, 809610 (2011). [3] A. Sanchez, et. al., J. Appl. Phys. 49 (1978) 5270. [4] J. R. Tucker and M. J. Feldman, Rev. of Mod. Phys. 57, (1985)1055.
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International Nuclear Information System (INIS)
Miyake, K; Nakano, M; Korenaga, A; Mano, H; Ando, Y
2010-01-01
The tribological properties of nanostripe surface structures were investigated using a pin-on-plate tribometer in order to propose a design concept for improving the tribological properties. The authors used four kinds of nanostripe structures consisting of different combinations of materials (Fe-Au, C-SiC, Al-Al 2 O 3 and Al-Pt) fabricated by a process they had previously proposed. The frictional properties of the nanostripe structures depended on the materials that constituted the nanostripes. When the sliding direction in friction tests was parallel to the microgrooves, nanostripe structures remained on all surfaces even after friction tests. Based on the friction test results, the authors considered a design concept for nanostripe structures in tribological applications.
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Islamic and Jewish Law of Ḥalal&Ḥaram: Analysis of Similarities & Differences (Urdu
Directory of Open Access Journals (Sweden)
Dr. Muhammad Ikramullah
2017-01-01
Full Text Available The world Semitic religions like Judaism, Christianity and Islam have given comprehensive regulations and code of life. Therefore; there has been a complete system and directions about “ḥalal” and “ḥaram” (kosher non-kosher means legal and illegal (treif’ in Jewish law.As Islam gives clear cut directives in beliefs, worships, ethics, economy and ways of life to guide the men in life; similarly the Judaism has also given clear regulations in these fields to guide its followers.Islam has taught its followers to eat and drink ‘ḥalal’ (Tayyib, so Judaism has also stressed on eating only ‘kosher’ (food that can be consumed according to Jewish law. For example in animals; meat of cow, bull, sheep and goat etc are legitimizing for eating in both the religions. Similarly the meat of pig is not allowed for men. Many things are similar in both these religions regarding dietary law.This article describes about ‘ḥalal’ and ‘kosher’ things in detail and tells what the similarities and dissimilarities regarding dietary laws are found in their religious literatures.
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Friction Stir Welding of Dissimilar Al/Al and Al/Non-Al Alloys: A Review
Wang, Xiangbin; Pan, Yi; Lados, Diana A.
2018-05-01
Friction stir welding is a solid-state welding technique that has many advantages over traditional fusion welding, and has been widely adopted in the aerospace and automotive industries. This article reviews research developments in friction stir welding of dissimilar alloys systems, including combinations of aluminum alloys with Mg alloys, Cu, and steel. Microstructural evolution, hardness, tensile and fatigue properties, residual stresses, and corrosion behavior of dissimilar welds will be reported. The effects of processing parameters such as tool rotation and traverse speeds, tool position, material position, and tool geometry on the weld quality are also presented. Discussions on future research directions in friction stir welding will also be provided in the context of existing literature and future high-integrity applications.
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Grove, C. A.; Judd, G.; Ansell, G. S.
1972-01-01
Thin foils of high purity aluminium and an Al-Al2O3 SAP type of alloy were oxidised in a specially designed hot stage specimen chamber in an electron microscope. Below 450 C, amorphous aluminium oxide formed on the foil surface and was first detectable at foil edges, holes, and pits. Islands of aluminium then nucleated in this amorphous oxide. The aluminium islands displayed either a lateral growth with eventual coalescence with other islands, or a reoxidation process which caused the islands to disappear. The aluminium island formation was determined to be related to the presence of the electron beam. A mechanism based upon electron charging due to the electron beam was proposed to explain the nucleation, growth, coalescence, disappearance, and geometry of the aluminium islands.
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120 aastat professor Nikolai Maimi sünnist / Väino J. Riismandel
Riismandel, Väino, 1920-2017
2004-01-01
Professor Maim (26. veeb. 1884 Tartus - 10. jaan. 1976 USA) on lõpetanud Moskva ülikooli õigusteaduskonna (1909), Tartu Ülikooli riigiõiguse erialal (1915). Ta on töötanud Vene keisririigi siseministeeriumi teenistuse eriülesandeis ametnikuna, Eesti Vabriigis siseministri abina, välisministeeriumi juriskonsultina. Maimi peamiseks ülesandeks kujunes korraldamisjärgus oleva Tartu Ülikooli õigusteaduskonna organiseerimine. Peale 1944. aastal Eestist põgenemist oli ta õppejõuks Marburgi ülikoolis riigiteaduse ja riigiõiguse alal. LL.M. (George Washingtoni ülikool) Väino J. Riismandel on District of Columbia advokatuuri liige, oli professor Maimi õpilane ja töökaaslane Tartu Ülikoolis. Lisatud: professor Maimi trükis ilmunud tööd lk. 65
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A thin two-phase foils deformed by an interfacial dislocation in anisotropic elasticity
Directory of Open Access Journals (Sweden)
Madani, Salah
2005-04-01
Full Text Available The purpose of this work is the numerical resolution, in the case of anisotropic elasticity, of the problem of a dislocation parallel and near to the two free surfaces of a thin bicrystal. This case is obtained while making the period of a network of misfit dislocations much greater than the thickness of the two foils. As a result, in the vicinity of the dislocation, the limiting bondary conditions will be close to that of Volterra translation dislocation. The elastic fields of displacement and stress are calculated for various orientations of the burgers vector. Before this calculation, we tested the precision of the results of the program by comparing the interfacial relative displacement obtained from this one to the results of the analytical expression describing this same displacement. The thin bicristal Al/Al2Cu, that made the object of several investigations, is treated like example. The results obtained are compared to those obtained in isotropic elasticity.
Este trabajo aborda la resolución numérica en anisotropía elástica, del problema de una dislocación paralela cercana a las superficies libres de un bi-cristal delgado. Este problema se genera cuando el periodo de la red de dislocaciones desplazadas es mucho mayor que el espesor de la bi-lámina. Como resultados, en la vecindad de la dislocación, las condiciones de contorno estarán cercanas a la dislocación de traslación de Volterra. Los campos elásticos de desplazamiento y las tensiones se calcularon para distintas orientaciones del vector de burgers. Como paso previo a los cálculos, se comprobó la precisión de los resultados del programa comparando le desplazamiento relativo interracial obtenido con los resultados de la expresión analítica que describen dicho desplazamiento. Se emplearon como ejemplo bi-cristales de Al/Al2Cu, debido a su empleo en varias investigaciones. Los resultados fueron comparados con los obtenidos en elasticidad isótropa. -
Real-time X-ray transmission microscopy for fundamental studies solidification: Al-Al2Au eutectic
International Nuclear Information System (INIS)
Curreri, Peter A.; Kaukler, William F.; Sen, Subhayu
1998-01-01
High resolution real-time X-ray Transmission Microscopy, XTM, has been applied to obtain information fundamental to solidification of optically opaque metallic systems. We have previously reported the measurement of the solute profile in the liquid, phase growth, and detailed solid-liquid interfacial morphology of aluminum based alloys with exposure times less than 2 seconds. Recent advances in XTM furnace design have provided an increase in real-time magnification (during solidification) for the XTM from 40X to 160X. The increased magnification has enabled for the first time the XTM imaging of real-time growth of fibers and particles with diameters of 5 μm. We have previously applied this system to study the kinetics of formation and morphological evolution of secondary fibers and particles in Al-Bi monotectic alloys. In this paper we present the preliminary results of the first real-time observations of fiber morphology evolution in optically opaque bulk metal sample of Aluminum-Gold eutectic alloy. These studies show that the XTM can be applied to study the fundamentals of eutectic and monotectic solidification. We are currently attempting to apply this technology in the fundamentals of solidification in microgravity
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Õpetajakoolituse üliõpilaste hoiakud ja teadlikkus soolise võrdõiguslikkuse küsimuses
Directory of Open Access Journals (Sweden)
Eve Mägi
2016-04-01
Full Text Available Soolise võrdõiguslikkuse taotlemisel lähtutakse põhimõttest, et naistel ja meestel on võrdsed õigused, kohustused, võimalused ja vastutus nii hariduse omandamisel kui ka tööelus. Kuna haridusel, sh õpetajakoolitusel, on väärtuste ja hoiakute kujundamisel oluline roll, käsitletakse seda sageli soolise võrdõiguslikkuse edendamise ühe võtmevaldkonnana. Uurimuse eesmärk on kirjeldada Eesti õpetajakoolituse ja kasvatusteaduste valdkonna üliõpilaste hoiakuid ja teadlikkust soolise võrdõiguslikkuse küsimuses, sh osutada nende erinevustele üliõpilaste üldkogumist. Selleks kombineeriti kvantitatiivset ja kvalitatiivset uurimisviisi. Uuringus küsitleti üliõpilasi (N = 2748 soolise võrdõiguslikkusega seotud hoiakute ja kogemuste teemal ning intervjueeriti õpetajakoolituse üliõpilasi (N = 20 fookusrühmades, et mõtestada kõrgkoolide õpetamispraktikat ning seda mõjutavaid väärtusi ja norme soolise võrdõiguslikkuse vaatenurgast. Ilmnes, et üliõpilased suhtuvad soolisesse võrdõiguslikkusse soosivalt ja tajuvad ebavõrdset kohtlemist soo alusel probleemina. See on hea potentsiaal, mille varal arendada tulevaste õpetajate valmisolekut sootundlikuks pedagoogikaks. Selgelt eristusid ka nende üliõpilaste rühmad, kelle hoiakutes väljenduvad teiste rühmadega võrreldes enam soolised stereotüübid (algajad üliõpilased ja mehed. Uurimuse tulemused täiendavad varasemate uurimuste omi, milles käsitletakse sugupoolte aspekti arvestamist hariduses, ning neil on praktiline väärtus õpetajakoolituse õppekavade kujundamisel. Summary
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Epitaxial Al2O3 capacitors for low microwave loss superconducting quantum circuits
Directory of Open Access Journals (Sweden)
K.-H. Cho
2013-10-01
Full Text Available We have characterized the microwave loss of high-Q parallel plate capacitors fabricated from thin-film Al/Al2O3/Re heterostructures on (0001 Al2O3 substrates. The superconductor-insulator-superconductor trilayers were grown in situ in a hybrid deposition system: the epitaxial Re base and polycrystalline Al counterelectrode layers were grown by sputtering, while the epitaxial Al2O3 layer was grown by pulsed laser deposition. Structural analysis indicates a highly crystalline epitaxial Al2O3 layer and sharp interfaces. The measured intrinsic (low-power, low-temperature quality factor of the resonators is as high as 3 × 104. These results indicate that low-loss grown Al2O3 is an attractive candidate dielectric for high-fidelity superconducting qubit circuits.
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High-performance flexible resistive memory devices based on Al2O3:GeOx composite
Behera, Bhagaban; Maity, Sarmistha; Katiyar, Ajit K.; Das, Samaresh
2018-05-01
In this study a resistive switching random access memory device using Al2O3:GeOx composite thin films on flexible substrate is presented. A bipolar switching characteristic was observed for the co-sputter deposited Al2O3:GeOx composite thin films. Al/Al2O3:GeOx/ITO/PET memory device shows excellent ON/OFF ratio (∼104) and endurance (>500 cycles). GeOx nanocrystals embedded in the Al2O3 matrix have been found to play a significant role in enhancing the switching characteristics by facilitating oxygen vacancy formation. Mechanical endurance was retained even after several bending. The conduction mechanism of the device was qualitatively discussed by considering Ohmic and SCLC conduction. This flexible device is a potential candidate for next-generation electronics device.
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Quantification of interfacial segregation by analytical electron microscopy
Muellejans, H
2003-01-01
The quantification of interfacial segregation by spatial difference and one-dimensional profiling is presented in general where special attention is given to the random and systematic uncertainties. The method is demonstrated for an example of Al-Al sub 2 O sub 3 interfaces in a metal-ceramic composite material investigated by energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy in a dedicated scanning transmission electron microscope. The variation of segregation measured at different interfaces by both methods is within the uncertainties, indicating a constant segregation level and interfacial phase formation. The most important random uncertainty is the counting statistics of the impurity signal whereas the specimen thickness introduces systematic uncertainties (via k factor and effective scan width). The latter could be significantly reduced when the specimen thickness is determined explicitly. (orig.)
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Heating of multi-layered samples by a Nd: YAG pulsed laser
International Nuclear Information System (INIS)
Diniz Neto, O.O.
1998-01-01
In the work we examine the heating of multi-layered samples by a powerful Nd-YAG pulsed laser. The samples are made of two and three layers, conductor-isolator (Al-Al 2 O 3 ). conductor-conductor (Al-Ag: Al-Au) an conductor-conductor-conductor (Al-Au-Ag:Ag-Au-Al). The transient behaviour of the temperature distribution throughout the samples is computed. We carry out three dimensional model calculations for the heating process in which we consider not only the temperature dependence of the sample thermal and optical parameters but also the space and time characteristics of the laser beams as the heating source. We showed the influence of the substrate in the thermal profile, in space and time, and maximum temperature on the multi-layered samples. (Author) 11 refs
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Helium trapping in aluminum and sintered aluminum powders
International Nuclear Information System (INIS)
Das, S.K.; Kaminsky, M.; Rossing, T.
1975-01-01
The surface erosion of annealed aluminum and of sintered aluminum powder (SAP) due to blistering from implantation of 100-keV 4 He + ions at room temperature has been investigated. A substantial reduction in the blistering erosion rate in SAP was observed from that in pure annealed aluminum. In order to determine whether the observed reduction in blistering is due to enhanced helium trapping or due to helium released, the implanted helium profiles in annealed aluminum and in SAP have been studied by Rutherford backscattering. The results show that more helium is trapped in SAP than in aluminum for identical irradiation conditions. The observed reduction in erosion from helium blistering in SAP is more likely due to the dispersion of trapped helium at the large Al-Al 2 O 3 interfaces and at the large grain boundaries in SAP than to helium release
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International Nuclear Information System (INIS)
Hascalik, Ahmet; Orhan, Nuri
2007-01-01
The aim of this study is to investigate the feasibility of joining Al 2 O 3 reinforced Al alloy composite to SAE 1020 steel by rotational friction welding. The aluminum-based metal matrix composite (MMC) material containing 5, 10 and 15 vol% Al 2 O 3 particles with average particle sizes of 30 and 60 μm was produced by powder metallurgy technique. The integrity of the joints has been investigated by optical and scanning electron microscopy, while the mechanical properties assessment included microhardness and shear tests. Results indicated that Al/Al 2 O 3 composite could be joined to SAE 1020 steel by friction welding. However, it was pointed out that the quality of the joint was effected negatively with the increase in particle size and volume percentage of the oxide particles in the MMC
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International Nuclear Information System (INIS)
Sun Lipeng; Irving, Douglas L.; Zikry, Mohammed A.; Brenner, D.W.
2009-01-01
Density functional theory was used to characterize the atomic structure and bonding of the Al | Ω interface in a Al-Cu-Mg-Ag alloy. The most stable interfacial structure was found to be connected by Al-Al bonds with a hexagonal Al lattice on the surface of the Ω phase sitting on the vacant hollow sites of the Al {1 1 1} matrix plane. The calculations predict that when substituted separately for Al at this interface, Ag and Mg do not enhance the interface stability through chemical bonding. Combining Ag and Mg, however, was found to chemically stabilize this interface, with the lowest-energy structure examined being a bi-layer with Ag atoms adjacent to the Al matrix and Mg adjacent to the Ω phase. This study provides an atomic arrangement for the interfacial bi-layer observed experimentally in this alloy.
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Synthesis behavior of nanocrystalline Al-Al2O3 composite during low time mechanical milling process
International Nuclear Information System (INIS)
Alizadeh, Mostafa; Aliabadi, Morteza Mirzaei
2011-01-01
Research highlights: → In the low time milling the effect of Al 2 O 3 amount is investigated → Al 2 O 3 particles are distributed uniformly in the Al matrix → In the low time milling it is possible to produce nanostructured composite powder → Median size and bulk density measurements demonstrate reaching the steady state. - Abstract: In this work, four different volume fractions of Al 2 O 3 (10, 20, 30 and 40 vol.%) were mixed with the fine Al powder and the powder blends were milled for 5 h. Scanning electron microscopy analysis, particle size analysis and bulk density measurements were used to investigate the morphological changes and achieving the steady state conditions. The results showed that increasing the Al 2 O 3 content can provide the steady state particle size in 5 h milling process. It was found that increasing the volume fraction of Al 2 O 3 leads to increasing the uniformity of Al 2 O 3 . Standard deviations of microhardness measurements confirmed this result. The XRD pattern and XRF investigations depicted that increasing the Al 2 O 3 content causes an increase in the crystal defects, micro-strain and Fe contamination during 5 h milling process of nanocrystalline composite powders while the grain size is decreased. To investigate the effect of milling time, Al-30 vol.% Al 2 O 3 (which achieved steady state during 5 h milling process) was milled for 1-4 h. The results depicted that the milling time lower than 5 h, do not achieve to steady state conditions.
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Data characterizing compressive properties of Al/Al2O3 syntactic foam core metal matrix sandwich
Directory of Open Access Journals (Sweden)
Mohammed Yaseer Omar
2015-12-01
Full Text Available Microstructural observations and compressive property datasets of metal matrix syntactic foam core sandwich composite at quasi-static and high strain rate (HSR conditions (525–845 s−1 are provided. The data supplied in this article includes sample preparation procedure prior to scanning electron and optical microscopy as well as the micrographs. The data used to construct the stress–strain curves and the derived compressive properties of all specimens in both quasi-static and HSR regions are included. Videos of quasi-static compressive failure and that obtained by a high speed image acquisition system during deformation and failure of HSR specimen are also included.
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Maróti, P; Hanson, D K; Baciou, L; Schiffer, M; Sebban, P
1994-06-07
Light-induced charge separation in the photosynthetic reaction center results in delivery of two electrons and two protons to the terminal quinone acceptor QB. In this paper, we have used flash-induced absorbance spectroscopy to study three strains that share identical amino acid sequences in the QB binding site, all of which lack the protonatable amino acids Glu-L212 and Asp-L213. These strains are the photosynthetically incompetent site-specific mutant Glu-L212/Asp-L213-->Ala-L212/Ala-L213 and two different photocompetent derivatives that carry both alanine substitutions and an intergenic suppressor mutation located far from QB (class 3 strain, Ala-Ala + Arg-M231-->Leu; class 4 strain, Ala-Ala + Asn-M43-->Asp). At pH 8 in the double mutant, we observe a concomitant decrease of nearly 4 orders of magnitude in the rate constants of second electron and proton transfer to QB compared to the wild type. Surprisingly, these rates are increased to about the same extent in both types of suppressor strains but remain > 2 orders of magnitude smaller than those of the wild type. In the double mutant, at pH 8, the loss of Asp-L213 and Glu-L212 leads to a substantial stabilization (> or = 60 meV) of the semiquinone energy level. Both types of compensatory mutations partially restore, to nearly the same level, the original free energy difference for electron transfer from primary quinone QA to QB. The pH dependence of the electron and proton transfer processes in the double-mutant and the suppressor strains suggests that when reaction centers of the double mutant are shifted to lower pH (1.5-2 units), they function like those of the suppressor strains at physiological pH. Our data suggest that the main effect of the compensatory mutations is to partially restore the negative electrostatic environment of QB and to increase an apparent "functional" pK of the system for efficient proton transfer to the active site. This emphasizes the role of the protein in tuning the
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International Nuclear Information System (INIS)
Qin, X.H.; Jiang, D.L.; Dong, S.M.
2004-01-01
Composite powder, which is a mixture of Al/Al 2 O 3 composite particles and nanometer, submicron and micron sized aluminum powder, was prepared by semi-solid mechanical stirring method with addition of Al 2 O 3 ceramic particles. The ceramic particles have an average diameter of 80 μm and a volume fraction of 15% in the slurry. The methods used to measure the size distribution of particles greater than 50 μm and less than 50 μm were sieve analysis and photosedimentation, respectively. The surface morphology and transverse sections of the composite powder of different sizes were examined by scanning electron microscope (SEM), optical microscope and auger electron spectroscopy (AES). The results indicate that the composite powder prepared in present work have a wide size distribution ranging from less than 50-900 μm, and the aluminum particles and Al/Al 2 O 3 composite particles are separated and isolated. The particles greater than 200 μm and less than 50 μm are almost pure aluminum powder. The rate of conversion of ingot aluminum into particles less than 1 μm containing nanometer and submicron sizes is 1.777 wt.% in this work. The aluminum powder of different sizes has different shape and surface morphology, quasi-spherical in shape with rough surface for aluminum particles of micron scale, irregular in shape for aluminum particles of submicron scale, and quite close to a globular or an excellent globular in shape for aluminum particles of nanometer size. On the other hand, the surface of ceramic particle was coated by aluminum particles with maximum thickness less than 10 μm containing nanometer and submicron sizes as a single layer. It is suggested that the surface of ceramic particles can provide more nucleation sites for solidification of liquid aluminum and the nucleation of liquid aluminum can take place readily, grow and adhere on the surface of ceramic particles, although it is poorly wetted by the liquid aluminum and the semi-solid slurry can
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Coho, Aleksander; Kioussis, Nicholas
2003-03-01
We use the semidiscrete variational generelized Peierls-Nabarro model to study the effect of Cu alloying on the dislocation properties of Al. First-principles density functional theory (DFT) is used to calculate the generalized-stacking-fault (GSF) energy surface when a plane, on which one in four Al atoms has been replaced with a Cu atom, slips over a pure Al plane. Various dislocation core properties (core width, energy, Peierls stress, dissociation tendency) are investigated and compared with the pure Al case. Cu alloying lowers the intrinsic stacking fault (ISF) energy, which makes dislocations more likely to dissociate into partials. We also try to understand the lowering of ISF energy in terms of Al-Cu and Al-Al bond formation and braking during shearing along the direction. From the above we draw conclusions about the effects of Cu alloying on the mechanical properties of Al.
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International Nuclear Information System (INIS)
Springer, R.W.; Hosford, C.D.
1981-01-01
A dc triode magnetron has been used to produce freestanding Al/Al + AlN lamellar foils by sputter deposition. The 5-μm-thick foils produced on both flat substrates as well as curved substrates exhibited good specularity as well as excellent mechanical properties. The pulse spacing was varied from none to 100-nm spacing. The yield strength of the material was found to obey the Hall-Petch relation sigma/sub ys/ = 230 + .07/d/sup 1/2/, where sigma/sub ys/ is in MPa. Auger electron Spectroscopy and Secondary Ion Mass Spectroscopy indicate that the large flow stress of 230 MPa must be due to grain refinement of the extended source and not an impurity effect. The result is that limitations of masking found in uniaxial flux sources for curved surfaces can be removed allowing the high quality coating of more general shapes
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Influence of copper content on microstructure development of AlSi9Cu3 alloy
Directory of Open Access Journals (Sweden)
Brodarac Zovko Z.
2014-01-01
Full Text Available Microstructure development and possible interaction of present elements have been determined in charge material of EN AlSi9Cu3 quality. Literature review enables prediction of solidification sequence. Modelling of equilibrium phase diagram for examined chemical composition has been performed, which enables determination of equilibrium solidification sequence. Microstructural investigation indicated distribution and morphology of particular phase. Metallographic analysis tools enable exact determination of microstructural constituents: matrix αAl, eutectic αAl+βSi, iron base intermetallic phase - Al5FeSi, Alx(Fe,MnyCuuSiw and/or Alx(Fe,MnyMgzCuuSiw and copper base phases in ternary eutectic morphology Al-Al2Cu-Si and in complex intermetallic ramified morphology Alx(Fe,MnyMgzSiuCuw. Microstructure development examination reveals potential differences due to copper content which is prerequisite for high values of final mechanical, physical and technological properties of cast products.
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Simulations of the Light Scattering Properties of Metal/Oxide Core/Shell Nanospheres
International Nuclear Information System (INIS)
Ruffino, F.; Piccitto, G.; Grimaldi, M.G.; Ruffino, F.; Grimaldi, M.G.
2014-01-01
Given the importance of the optical properties of metal/dielectric core/shell nanoparticles, in this work we focus our attention on the light scattering properties, within the Mie framework, of some specific categories of these noteworthy nano structures. In particular, we report theoretical results of angle-dependent light scattering intensity and scattering efficiency for Ag/Ag 2 O, Al/Al 2 O 2 , Cu/Cu 2 O, Pd/PdO, and Ti/TiO 2 core/shell nanoparticles as a function of the core radius/shell thickness ratio and on a relative comparison. The results highlight the light scattering characteristics of these systems as a function of the radius/shell thickness ratio, helping in the choice of the more suitable materials and sizes for specific applications (i.e., dynamic light scattering for biological and molecular recognition, increasing light trapping in thin-film silicon, organic solar cells for achieving a higher photocurrent).
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Polvos de Al-Al3Ti obtenidos mediante aleado mecánico y tratamiento térmico
Directory of Open Access Journals (Sweden)
Gallardo, J. M.
2005-12-01
Full Text Available Mixed powders of aluminium and titanium (10 wt % have been mechanically alloyed in an Attritor mill. A metastable solution of titanium in an aluminium matrix is obtained. Changes produced on shape and particle size, structure and microstructure, have been studied when milling time varies between 2 and 10 h. The final processing is carried out for a milling time of 10 h, with approximately 9 wt % of titanium dissolved in the matrix. Finally, a heat treatment is carried out at different temperatures, up to a maximum of 625 °C, which produces the precipitation of different phases such as different structures of Al3Ti and Al4C3. The appearance of these second phases is characterized according to the selected heat treatment temperature.Polvos mezclados de aluminio y titanio (10 % en peso han sido aleados mecánicamente en un molino Attritor, obteniéndose una solución metaestable de titanio en la matriz de aluminio. Se han estudiado los cambios producidos en la forma y tamaño de las partículas, estructura y microestructura, al variar el tiempo de molienda entre 2 y 10 h. El procesado final se realiza para un tiempo de 10 h, habiéndose disuelto aproximadamente un 9 % en peso de titanio. Finalmente, se realiza un tratamiento térmico a diversas temperaturas, hasta un máximo de 625 °C, lo que produce la precipitación de diversas fases, como distintas estructuras de Al3Ti y Al4C3. La aparición de estas segundas fases es caracterizada en función de la temperatura de tratamiento utilizada.
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Theoretical modeling of critical temperature increase in metamaterial superconductors
Smolyaninov, Igor; Smolyaninova, Vera
Recent experiments have demonstrated that the metamaterial approach is capable of drastic increase of the critical temperature Tc of epsilon near zero (ENZ) metamaterial superconductors. For example, tripling of the critical temperature has been observed in Al-Al2O3 ENZ core-shell metamaterials. Here, we perform theoretical modelling of Tc increase in metamaterial superconductors based on the Maxwell-Garnett approximation of their dielectric response function. Good agreement is demonstrated between theoretical modelling and experimental results in both aluminum and tin-based metamaterials. Taking advantage of the demonstrated success of this model, the critical temperature of hypothetic niobium, MgB2 and H2S-based metamaterial superconductors is evaluated. The MgB2-based metamaterial superconductors are projected to reach the liquid nitrogen temperature range. In the case of an H2S-based metamaterial Tc appears to reach 250 K. This work was supported in part by NSF Grant DMR-1104676 and the School of Emerging Technologies at Towson University.
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Thermal conductivities of thin, sputtered optical films
International Nuclear Information System (INIS)
Henager, C.H. Jr.; Pawlewicz, W.T.
1991-05-01
The normal component of the thin film thermal conductivity has been measured for the first time for several advanced sputtered optical materials. Included are data for single layers of boron nitride (BN), aluminum nitride (AIN), silicon aluminum nitride (Si-Al-N), silicon aluminum oxynitride (Si-Al-O-N), silicon carbide (SiC), and for dielectric-enhanced metal reflectors of the form Al(SiO 2 /Si 3 N 4 ) n and Al(Al 2 O 3 /AIN) n . Sputtered films of more conventional materials like SiO 2 , Al 2 O 3 , Ta 2 O 5 , Ti, and Si have also been measured. The data show that thin film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or very fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film/substrate interface contribution is presented
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International Nuclear Information System (INIS)
Beygi, H.; Sajjadi, S.A.; Zebarjad, S.M.
2014-01-01
Aluminum matrix composites used in the aerospace, military and automotive industries are typically fabricated by a stir casting method. However, when nanoparticles are used for reinforcement, fabrication of composite materials by this method leads to the formation of a large number of structural defects. In this study, copper coating of alumina reinforcement particles is investigated as a technique for improving the structure of Al-Al 2 O 3 composites. Microstructural investigations by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersion spectroscopy (EDS) and transmission electron microscopy (TEM) showed that the alumina particles were coated uniformly with copper shells. Copper coating of the reinforcing particles significantly increased their wettability in the molten aluminum alloy, strengthened the matrix-particle interfaces and improved the distribution of reinforcing particles within the matrix. Due to these microstructural improvements, the hardness, compressive strength, yield stress, tensile strength and elongation of the composites were enhanced by copper coating of the alumina particles
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High Temperature Strength of Oxide Dispersion Strengthened Aluminium
DEFF Research Database (Denmark)
Clauer, A.H.; Hansen, Niels
1984-01-01
constant (except for the material with the lowest oxide content). The high temperature values of the modulus-corrected yield stresses are approximately two-thirds of the low temperature value. During high temperature creep, there is a definite indication of a threshold stress. This threshold stress......The tensile flow stress of coarse-grained dispersion strengthened Al-Al2O3 materials were measured as a function of temperature (77–873 K) and volume fraction (0.19-0.92 vol.%) of aluminium oxide. For the same material, the creep strength was determined as a function of temperature in the range 573......–873 K. The modulus-corrected yield stress (0.01 offset) is found to be temperature independent at low temperature (195–472 K). Between 473 and 573 K, the yield stress starts to decrease with increasing temperature. At high temperatures (573–873 K), the modulus-corrected yield stress is approximately...
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Polarization Behavior of Squeeze Cast Al2O3 Fiber Reinforced Aluminum Matrix Composites
International Nuclear Information System (INIS)
Ham, S. H.; Kang, Y. C.; Cho, K. M.; Park, I. M.
1992-01-01
Electrochemical polarization behavior of squeeze cast Al 2 O 3 short fiber reinforced Al alloy matrix composites was investigated for the basic understanding of the corrosion properties of the composites. The composites were fabricated with variations of fiber volume fraction and matrix alloys. It was found that the reinforced composites are more susceptible to corrosion attack than the unreinforced matrix alloys in general. Corrosion resistance shows decreasing tendency with increasing Al 2 O 3 fiber volume fraction in AC8A matrix. Effect of the matrix alloys revealed that the AC8A Al matrix composite is less susceptible to corrosion attack than the 2024 and 7075 Al matrix composites. Effect of plastic deformation on electrochemical polarization behavior of the squeeze cast Al/Al 2 O 3 composites was examined after extrusion of AC8A-10v/o Al 2 O 3 . Result shows that corrosion resistance is deteriorated after plastic deformation
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A first-principles study of B2 NiAl alloyed with rare earth elements Pr, Pm, Sm, and Eu
Institute of Scientific and Technical Information of China (English)
He Jun-Qi; Wang You; Yan Mu-Fu; Pan Zhao-Yi; Guo Li-Xin
2013-01-01
The structural,elastic,and electronic properties of NiAl alloyed with rare earth elements Pr,Pm,Sm,and Eu are investigated by using density functional theory (DFT).The study suggests that Pr,Pm,Sm,and Eu all tend to be substituted for an Al site.Ni8Al7Pm possesses the largest ductility.Only the hardness and ductility of Ni8Al7Eu are enhanced simultaneously.The covalency strength of the Ni-Al bond in Ni8Al7Pm is higher than that in Ni8Al7Eu.The covalency strength of an Al-Al bond and that of a Ni-Ni bond in Ni8Al7Eu are higher than that in Ni8Al7Pm.The Ni-Pm bond and the Ni-Eu bond are covalent,and the covalency strength of the Ni-Pm bond is greater.The Al-Pm bond and the Al-Eu bond show great covalency strength and ionicity,respectively.
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Fabrication of a Porous Metal via Selective Phase Dissolution in Al-Cu Alloys
Directory of Open Access Journals (Sweden)
Juan Vargas-Martínez
2018-05-01
Full Text Available Through free corrosion, a new low cost porous material was successfully fabricated by removing a single phase of a binary aluminum-copper alloy. This selective phase dissolution was carried out an Al-Al2Cu eutectic alloy of the Al-Cu binary system and additionally for two hypereutectic compositions. The porosity of the material depends on the microstructure formed upon solidification. For this reason, several solidification methods were studied to define the most convenient in terms of uniformity and refinement of the average pore and ligament sizes. The samples were corroded in a 10% v/v NaOH aqueous solution, which demonstrated to be the most convenient in terms of time involved and resulting porosity conditions after the corrosion process. The porosity was measured through analysis of secondary electron images. The effectiveness of the process was verified using X-ray diffraction, which showed that, under the proposed methodology, there was complete removal of one of the phases, namely the aluminum one.
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Directory of Open Access Journals (Sweden)
A. Mostafapour
2012-10-01
Full Text Available Friction stir processing was applied for fabricating an aluminum alloy based hybrid nano composite reinforced with nano sized Al2O3 and micro sized graphite particles. A mixture of Al2O3 and graphite particles was packed into a groove with 1 mm width and 4.5 mm depth, which had been cut in 5083 aluminum plate of 10 mm thick. Packed groove was subjected to friction stir processing in order to implement powder mixture into the aluminum alloy matrix. Microstructural properties were investigated by means of optical microscopy and scanning electron microscopy (SEM. It was found that reinforcement particle mixture was distributed uniformly in nugget zone. Wear resistance of composite was measured by dry sliding wear test. As a result, hybrid composite revealed significant reduction in wear rate in comparison with Al/AL2O3 composite produced by friction stir processing. Worn surface of the wear test samples were examined by SEM in order to determine wear mechanism.
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Plastic deformation of Al13Fe4 particles in Al-Al13Fe4 by high-speed compression
International Nuclear Information System (INIS)
Yoneyama, N.; Mizoguchi, K.; Kumai, S.; Sato, A.; Kiritani, M.
2003-01-01
Spray-formed Al-Fe alloys having undergone high-speed deformation were examined under a high-voltage electron microscope. Two types of specimens were examined; one containing fine Al 13 Fe 4 particles, and the other containing large particles. In the former specimen, deformation is found to proceed in three patterns, depending on specimen thickness and strain rate: (1) without deformation of the Al 13 Fe 4 ; (2) breaking of the Al 13 Fe 4 ; or (3) melting of the Al 13 Fe 4 . Local melting is found to alter some of the Al 13 Fe 4 particles, to impart five-fold symmetry in diffraction or an amorphous structure. In the latter specimen, introduction of glide dislocations enabled us to determine a shear system in the mc102 monoclinic c2/m crystal of Al 13 Fe 4 . On the bases of these observations, the mechanism of high-speed deformation is discussed while taking into account the highly stressed and/or heated states of Al 13 Fe 4 embedded in Al matrix
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Remiksimist, kirjaoskust ja loovust käsitleva teaduskirjanduse analüütiline ülevaade
Directory of Open Access Journals (Sweden)
Michele Knobel
2017-10-01
Full Text Available Loovust on hakatud pidama riikide majanduskasvu võtmeteguriks, mis tagab ühiskonnas toimetuleku ja mille abil tagatakse isiklik või ühiskondlik heaolu. Seda silmas pidades on mõistlik süveneda loovuse käsitusse ja praktilisse olemusse ning uurida nende seostamise võimalusi hariduse kontekstis. Olukord koolides on mahukate uurimistulemuste põhjal koolivälise tegelikkusega teravas vastuolus, sest vähe võetakse arvesse inimeste loomingulisust ja suurt kujutlusvõimet tähenduste loomisel, mille üks väljendusvorme on remiksimine. Artikli eesmärk on anda ülevaade olemasolevatest ingliskeelsetest uurimustest, milles käsitletakse digitaalset remiksimist ja kirjaoskust, ning selgitada välja mustrid, mis näitavad, kuidas tavalised inimesed on ennast loominguliselt väljendanud. Analüütilise ülevaate koostamisel uuriti viimase kahe kümnendi jooksul inglise keeles ilmunud empiirilisi publikatsioone ning koostati ülevaade avaldatud teadusartiklitest koolivälise remiksimise ja kirjaoskuse kohta. Uurimise käigus selgitati välja need loominguliste püüdluste ja tähenduste loomise viisid, millest koolipedagoogika saaks midagi kasulikku õppida. Ühtlasi vaadeldi, kuidas digitaalset remiksimist ja kirjaoskust on uuritud. Kõigis 36 analüüsitud uurimuses rõhutati, et lähenemine loovusele kui sügavalt sotsiaalsele nähtusele aitab vastu seista kasulikkust taga ajavatele lähenemisviisidele. Uurimustes vaatluse all olnud remiksitud tööd näitavad teadlikku loovuse arendamise püüdlust, mis võib aidata inimestel loominguliselt hakkama saada või reageerida kiiretele muutustele ning ühiskondlikele, riiklikele ja keskkondlikele probleemidele praegu ja tulevikus, luues ja säilitades samal ajal suhteid suurte vahemaade ja erinevuste kiuste. Full text
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Deformation processed Al/Ca nano-filamentary composite conductors for HVDC applications
Czahor, C. F.; Anderson, I. E.; Riedemann, T. M.; Russell, A. M.
2017-07-01
Efficient long-distance power transmission is necessary as the world continues to implement renewable energy sources, often sited in remote areas. Light, strong, high-conductivity materials are desirable for this application to reduce both construction and operational costs. In this study an Al/Ca (11.5% vol.) composite with nano-filamentary reinforcement was produced by powder metallurgy then extruded, swaged, and wire drawn to a maximum true strain of 12.7. The tensile strength increased exponentially as the filament size was reduced to the sub-micron level. In an effort to improve the conductor’s ability to operate at elevated temperatures, the deformation-processed wires were heat-treated at 260°C to transform the Ca-reinforcing filaments to Al2Ca. Such a transformation raised the tensile strength by as much as 28%, and caused little change in ductility, while the electrical conductivity was reduced by only 1% to 3%. Al/Al2Ca composites are compared to existing conductor materials to show how implementation could affect installation and performance.
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Yamada, Takayuki; Takahashi, Mutsuya; Ozawa, Takashi; Tawara, Satoshi; Goto, Takayuki
2002-11-01
The purpose of this work is to demonstrate that a novel fabrication method for 3-D microstructures (FORMULA) is applicable to fabrication of micro mechanical parts with a large flexibility. This method is a kind of layer manufacturing method of thin films for metallic or dielectric microstructures using surface-activated bonding (SAB). The bonding interfaces of thin films are investigated by transmission electron microscope (TEM). Voids were observed at the interfaces of both pure aluminum films and Al-Cu alloy films. The ratio of void on the Al-Cu/Al-Cu interface is much larger than that of Al/Al interface, although the films have the same surface roughness of 3nm in Ra (average roughness). And approximately 10nm-thick amorphous intermediate layers were found at the interfaces. Furthermore, we have fabricated a micro gear of 900μm in diameter and 200μm in height, which is about ten times as large as our previous test pieces. Overhung structures such as a bridge structure and a cantilever were also fabricated without supporting layers beneath them.
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Molecular dynamics study of interstitial-solute interactions in irradiated alloys
International Nuclear Information System (INIS)
Lam, N.Q.; Doan, N.V.; Adda, Y.
1980-01-01
The molecular dynamics technique has been used, in conjunction with the interionic potentials of Dagens et al, to study the stability, configuration, binding, and induced migration of mixed dumbbells in an irradiated Al-Zn alloy. For the purpose of comparisons, self-interstitials in pure Al were also investigated. The Al-Al and Al-Zn interactions were described by pair potentials which extended to ninth-neighbour distances. Both the self-interstitial dumbbell and the mixed dumbbell were found to be stable in the configuration. The formation energy of the self-interstitial is 2.89 eV and the mixed-dumbbell binding energy is 0.38 eV. As a result of this strong binding, the threshold energy required to induce the migration of the mixed dumbbell is about 1.2 eV, which is significantly larger than the minimum energy of about 0.15 eV transferred to a self-interstitial to induce its jumps in pure Al. Caging motions of the mixed dumbbell were observed. The present computer-simulation results are compared with experimental measurements. (author)
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Energy Technology Data Exchange (ETDEWEB)
Yan, Zhi; Deng, Weizhi; Zhang, Xia; Yuan, Qian; Deng, Peiran; Sun, Lei [Material Engineering College, Shanghai University of Engineering Science (China); Liang, Jun [School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen University Town (China)
2014-11-15
Al-doped CuInSe{sub 2} material is prepared by a low-cost wet chemical process. The key properties of Al-doped CuInSe{sub 2} as a successful solar cell material are investigated, such as crystal structure, morphology, optical properties, and bandgap. In situ X-ray diffraction measurements indicate that the doping of Al has induced noticeable lattice distortion. The material shows excellent thermal stability up to 600 C annealing temperature. By increasing the Al-doping concentration, the crystal unit-cell parameter of the material becomes smaller and the change of crystal structure leads to an increase of the grain size and surface roughness. The bandgap of Al-doped CuInSe{sub 2} can be continuously tuned in a range of 1.07-1.67 eV as Al/(Al + In) content ratio varies from 0 to 0.49. Finally, the effect mechanism on the properties of CuInSe{sub 2} after Al doping is discussed based on the ionic radius, crystal structure, and bonding state. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
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International Nuclear Information System (INIS)
Shafiei-Zarghani, A.; Kashani-Bozorg, S.F.; Zarei-Hanzaki, A.
2009-01-01
In this study, a new processing technique, friction stir processing (FSP) was attempted to incorporate nano-sized Al 2 O 3 into 6082 aluminum alloy to form particulate composite surface layer. Samples were subjected to various numbers of FSP passes from one to four, with and without Al 2 O 3 powder. Microstructural observations were carried out by employing optical and scanning electron microscopy (SEM) of the cross sections both parallel and perpendicular to the tool traverse direction. Mechanical properties include microhardness and wear resistance, were evaluated in detail. The results show that the increasing in number of FSP passes causes a more uniform in distribution of nano-sized alumina particles. The microhardness of the surface improves by three times as compared to that of the as-received Al alloy. A significant improvement in wear resistance in the nano-composite surfaced Al is observed as compared to the as-received Al
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Directory of Open Access Journals (Sweden)
Tiina Ann Kirss
2012-04-01
nime tarkusejumalanna ema Metise järgi, on sellele nimele lisatud h-täht, et siiski vältida kordamist. Esiteks ei soovi toimetus tekitada identiteedisegadusi, sest Hollandis ilmub samuti humanitaarteaduslik ajakiri Metis. Teiseks on oluline märkida, et Methisel on eelkäijad: uus ajakiri asendab Tartu Ülikooli eesti kirjanduse õppetooli senist sarja „Studia litteraria estonica” ja Eesti Kirjandusmuuseumi artiklikogumike sarja („Traditsioon & pluralism”, „Kohanevad tekstid” jt. Algusest peale võeti sihiks kujundada uus väljaanne perioodiliseks, avaldada teadusartikleid ja artiklikobaraid ning koostada ka erinumbreid. Ajakiri hakkab ilmuma kaks korda aastas, vähemalt iga kolmas number jääb vabanumbriks , eeldades kaastööd noorematelt kultuuri-, kirjandus- ja teatriuurijatelt. Methis on sündinud koostööst kahe kirjandust uuriva ning õpetava asutuse vahel – vaimse, mitte pelgalt vormilise – koostöö lootuses. Ka tema „toitmine-katmine” ja „kasvatamine” on kahe koostööpartneri mure ja rõõm. Methis ei korda ega dubleeri teisi olemasolevaid eestikeelseid kirjandus- ja kultuuriteaduslikke väljaandeid, vaid loodab kujundada oma nägu ja tegu. Rahvusvahelise toimetuskolleegiumi ja eelretsenseeritava väljaandena vastab see teaduslikele nõuetele ning seab eesmärgiks elava mitmehäälse dialoogi kujundamist autorite, kolleegiumi liikmete ja retsensentide vahel. Kirjutada Methisele võiks olla ning peakski olema ohtlik – kirjatükki ja uurimust avaldamiskõlbulikuks kohendades on nii autoril kui ka retsensendil ja toimetajal oht selles dialoogis targemaks saada. Soov seda elavat, vaimselt nõudlikku sidet alal hoida, vaheda mõtte ja kauni stiili nimel, on vastus teadusbürokraatlikule pealiskaudsusele, mida kannustab „siisikeste” korjamise sund. Alates Methise neljandast numbrist hakkab leiduma igas numbris lisaks teadusartiklitele veel kolm rubriiki : 1 tõlgitud teoreetiline artikkel, mis täiendab eestikeelset kirjandus- ja
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DEFF Research Database (Denmark)
Lindbo, Jørgen
1966-01-01
A technique for thinning 1 mm wire samples of aluminium and aluminium-alumina alloys for transmission electron microscopy is described. The essential feature of the technique, which involves spark machining and electropolishing in a polytetrafluoroethylene holder followed by chemical polishing...
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Removal of nitrate and sulphate from biologically treated municipal wastewater by electrocoagulation
Sharma, Arun Kumar; Chopra, A. K.
2017-06-01
The present investigation observed the effect of current density ( j), electrocoagulation (EC) time, inter electrode distance, electrode area, initial pH and settling time on the removal of nitrate (NO3 -) and sulphate (SO4 2-) from biologically treated municipal wastewater (BTMW), and optimization of the operating conditions of the EC process. A glass chamber of two-liter volume was used for the experiments with DC power supply using two electrode plates of aluminum (Al-Al). The maximum removal of NO3 - (63.21 %) and SO4 2- (79.98 %) of BTMW was found with the optimum operating conditions: current density: 2.65 A/m2, EC time: 40 min, inter electrode distance: 0.5 cm, electrode area: 160 cm2, initial pH: 7.5 and settling time: 60 min. The EC brought down the concentration of NO3 - within desirable limit of the Bureau of Indian Standard (BIS)/WHO for drinking water. Under optimal operating conditions, the operating cost was found to be 1.01/m3 of water in terms of the electrode consumption (23.71 × 10-5 kg Al/m3) and energy consumption (101.76 kWh/m3).
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Oxidation behavior of arc evaporated Al-Cr-Si-N thin films
Energy Technology Data Exchange (ETDEWEB)
Tritremmel, Christian; Daniel, Rostislav; Mitterer, Christian; Mayrhofer, Paul H.; Lechthaler, Markus; Polcik, Peter [Christian Doppler Laboratory for Advanced Hard Coatings, Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Christian Doppler Laboratory for Application Oriented Coating Development, Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); OC Oerlikon Balzers AG, Iramali 18, LI-9496 Balzers (Liechtenstein); PLANSEE Composite Materials GmbH, Siebenbuergerstrasse 23, D-86983 Lechbruck am See (Germany)
2012-11-15
The impact of Al and Si on the oxidation behavior of Al-Cr-(Si)-N thin films synthesized by arc evaporation of powder metallurgically prepared Al{sub x}Cr{sub 1-x} targets with x = Al/(Al + Cr) of 0.5, 0.6, and 0.7 and (Al{sub 0.5}Cr{sub 0.5}){sub 1-z}Si{sub z} targets with Si contents of z = 0.05, 0.1, and 0.2 in N{sub 2} atmosphere was studied in detail by means of differential scanning calorimetry, thermogravimetric analysis (TGA), x-ray diffraction, and Raman spectroscopy. Dynamical measurements in synthetic air (up to 1440 Degree-Sign C) revealed the highest onset temperature of pronounced oxidation for nitride coatings prepared from the Al{sub 0.4}Cr{sub 0.4}Si{sub 0.2} target. Isothermal TGA at 1100, 1200, 1250, and 1300 Degree-Sign C highlight the pronounced improvement of the oxidation resistance of Al{sub x}Cr{sub 1-x}N coatings by the addition of Si. The results show that Si promotes the formation of a dense coating morphology as well as a dense oxide scale when exposed to air.
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Microstructure and properties of an Al-Ti-Cu-Si brazing alloy for SiC-metal joining
Dai, Chun-duo; Ma, Rui-na; Wang, Wei; Cao, Xiao-ming; Yu, Yan
2017-05-01
An Al-Ti-Cu-Si solid-liquid dual-phase alloy that exhibits good wettability and appropriate interfacial reaction with SiC at 500-600°C was designed for SiC-metal joining. The microstructure, phases, differential thermal curves, and high-temperature wetting behavior of the alloy were analyzed using scanning electron microscopy, X-ray diffraction analysis, differential scanning calorimetry, and the sessile drop method. The experimental results show that the 76.5Al-8.5Ti-5Cu-10Si alloy is mainly composed of Al-Al2Cu and Al-Si hypoeutectic low-melting-point microstructures (493-586°C) and the high-melting-point intermetallic compound AlTiSi (840°C). The contact angle, determined by high-temperature wetting experiments, is approximately 54°. Furthermore, the wetting interface is smooth and contains no obvious defects. Metallurgical bonding at the interface is attributable to the reaction between Al and Si in the alloy and ceramic, respectively. The formation of the brittle Al4C3 phase at the interface is suppressed by the addition of 10wt% Si to the alloy.
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International Nuclear Information System (INIS)
Kim, Jihoon; Song, Jaewon; Kwon, Ohsung; Kim, Sungkeun; Hwang, Cheol Seong; Park, Sang-Hee'Ko; Yun, Sun Jin; Jeong, Jaehack; Hyun, Kwang Soo
2002-01-01
The electrical conduction properties of 10-nm-thick atomic-layer deposited Al 2 O 3 thin films with Al bottom and Pt top electrodes were characterized for use in field emission display. The as-deposited films, grown at 300 deg. C, exhibited such a high electrical leakage that their electrical properties could not be measured. However, post-treatment at 300 deg. C under a remote O 2 or H 2 O plasma for 30 min improved the insulating properties of the Al 2 O 3 films. However, the electrical conduction mechanism, particularly in the high field (>4 MV/cm) was not Fowler-Nordheim (F-N) tunneling but was influenced by space charge limited conduction implying that there were many traps inside the dielectric film or the electrode interfaces. Postannealing of the top electrode at 300 deg. C in an oxygen atmosphere resulted in a F-N conduction mechanism by removing the interfacial traps. The calculated barrier height at the Al/Al 2 O 3 interface from the F-N fitting of the current density versus voltage curves using the electron effective mass (m * ) of 0.5 m 0 was approximately 2.0 eV
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Microstructure and properties of aluminium-aluminium oxide graded composite materials
Kamaruzaman, F. F.; Nuruzzaman, D. M.; Ismail, N. M.; Hamedon, Z.; Iqbal, A. K. M. A.; Azhari, A.
2018-03-01
In this research works, four-layered aluminium-aluminium oxide (Al-Al2O3) graded composite materials were fabricated using powder metallurgy (PM) method. In processing, metal-ceramic graded composite materials of 0%, 10%, 20% and 30% weight percentage of ceramic concentration were prepared under 30 ton compaction load using a cylindrical die-punch set made of steel. After that, two-step pressureless sintering was carried out at sintering temperature and time 600°C and 3 hours respectively. It was observed that the sintered cylindrical specimens of 30 mm diameter were prepared successfully. The graded composite specimens were analysed and the properties such as density, microstructure and hardness were measured. It was found that after sintering process, the diameter of the graded cylindrical structure was decreased. Using both Archimedes method and rule of mixture (ROM), he density of structure was measured. The obtained results revealed that the microvickers hardness was increased as the ceramic component increases in the graded layer. Moreover, it was observed that the interface of the graded structure is clearly distinguished within the multilayer stack and the ceramic particles are almost uniformly distributed in the Al matrix.
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Treatment of Biodiesel Wastewater by Electrocoagulation Process
Directory of Open Access Journals (Sweden)
Anchalee Srirangsan
2009-07-01
Full Text Available The objective of this research was to determine the optimum conditions for biodiesel wastewater treatment using an electrocoagulation process. Wastewater samples were obtained from a small-scale, commercial biodiesel production plant that employs an alkali-catalyzed tranesterification process. The wastewater was characterized by the high contents of alkali and high oil content of 6,020 mg/L. Tested operational conditions included types of electrode, current density, retention time and initial pH. The tested electrode materials for electrocoagulation were aluminum (Al, iron (Fe and graphite (C. Five tested pairs of anode and cathode materials included Fe-Fe, Fe-C, Al-Al, Al-C, C-C. Results show that the optimum conditions were achieved by using the electrodes of Al-C, applying the current density of 8.32 mA/cm2 to the wastewater with an initial pH value of 6 for 25 min. The removal efficiency was found to be 97.8 % for grease & oil (G&O, 96.9 % for SS and 55.4 % for COD. Moreover, the small amount of produced sludge was readily to remove from the treated wastewater.
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International Nuclear Information System (INIS)
Santos, Desireé M. de los; Navas, Javier; Sánchez-Coronilla, Antonio; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Martín-Calleja, Joaquín
2015-01-01
Highlights: • Highly Al-doped TiO 2 nanoparticles were synthesized using a Ball Mill Method. • Al doping delayed anatase to rutile phase transformation. • Al doping allow controlling the structural and electronic properties of nanoparticles. - Abstract: This study presents an easy method for synthesizing highly doped TiO 2 nanoparticles. The Ball Mill method was used to synthesize pure and Al-doped titanium dioxide, with an atomic percentage up to 15.7 at.% Al/(Al + Ti). The samples were annealed at 773 K, 973 K and 1173 K, and characterized using ICP-AES, XRD, Raman spectroscopy, FT-IR, TG, STEM, XPS, and UV–vis spectroscopy. The effect of doping and the calcination temperature on the structure and properties of the nanoparticles were studied. The results show high levels of internal doping due to the substitution of Ti 4+ ions by Al 3+ in the TiO 2 lattice. Furthermore, anatase to rutile transformation occurs at higher temperatures when the percentage of doping increases. Therefore, Al doping allows us to control the structural and electronic properties of the nanoparticle synthesized. So, it is possible to obtain nanoparticles with anatase as predominant phase in a higher range of temperature
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International Nuclear Information System (INIS)
Lotus, A.F.; Kang, Y.C.; Walker, J.I.; Ramsier, R.D.; Chase, G.G.
2010-01-01
Zinc oxide nanofibers doped with aluminum oxide were prepared by sol-gel processing and electrospinning techniques using polyvinylpyrrolidone (PVP), zinc acetate and aluminum acetate as precursors. The resulting nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy, and current-voltage (I-V) properties. The nanofibers had diameters in the range of 60-150 nm. The incorporation of aluminum oxide resulted in a decrease in the crystallite sizes of the zinc oxide nanofibers. Aluminum oxide doped zinc oxide (AOZO) nanofibers exhibited lower bandgap energies compared to undoped zinc oxide nanofibers. However, as the aluminum content (Al/(Al + Zn) x 100%) was increased from 1.70 at.% to 3.20 at.% in the electrospinning solution, the bandgap energy increased resulting in lower conductivity. The electrical conductivity of the AOZO samples was found to depend on the amount of aluminum dopant in the matrix as reflected in the changes in oxidation state elucidated from XPS data. Electrospinning was found to be a productive, simple, and easy method for tuning the bandgap energy and conductivity of zinc oxide semiconducting nanofibers.
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International Nuclear Information System (INIS)
Ardakani, Mohammad Reza Kamali; Amirkhanlou, Sajjad; Khorsand, Shohreh
2014-01-01
Lightweight metal-matrix nanocomposites (MMNCs—metal matrix with nanosized ceramic particles) can be of significance for automobile, aerospace, and numerous other applications. There are some problems in obtaining suitable mechanical properties of MMNCs, including weak bonding between reinforcement and matrix, non-uniformity of reinforcement nanoparticles and high porosity content. In this study, aluminum/alumina nanocomposite was fabricated by stircasting method. Subsequently, cross accumulative roll bonding (CARB) process was used as an effective method for refinement of microstructure and improvement of mechanical properties. The microstructural evolution and the mechanical properties of the nanocomposites during various CARB cycles were examined by the Archimedes method, X-ray defractometer, scanning electron microscopy and tensile testing. The results showed that the microstructure of the nanocomposite after eight cycles of CARB had an excellent distribution of alumina nanoparticles in aluminum matrix without any remarkable porosity. The X-ray diffraction results showed that the crystallite size of the nanocomposite was 71 nm by employing eight cycles of CARB technique. Mechanical experiment also indicated that the ultimate tensile strength and the elongation of the nanocomposite increased as the number of CARB cycles increased. After eight CARB cycles, ultimate tensile strength and the elongation values reached 344 MPa and 6.4%, which were 3.13 and 3.05 times greater than those of as-cast nanocomposites, respectively
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Yaman, Bilge; Onuklu, Eren; Korpe, Nese O.
2017-09-01
Pure Al and alumina (2, 5, 10 wt.% Al2O3)-added Al composite foams were fabricated through powder metallurgy technique, where boric acid (H3BO3) is employed as a new alternative foaming agent. It is aimed to determine the effects of boric acid on the foaming behavior and cellular structure and also purposed to develop the mechanical properties of Al foams by addition of Al2O3. Al and Al composite foams with porosity fraction in the range of 46-53% were achieved by sintering at 620 °C for 2 h. Cell morphology was characterized using a combination of stereomicroscope equipped with image analyzer and scanning electron microscopy. Microhardness values were measured via using Vickers indentation technique. Quasi-static compression tests were performed at strain rate of 10-3 s-1. Compressive strength and energy absorption of the composite foams enhanced not only by the increasing weight fraction of alumina, but also by the usage of boric acid which leads to formation of boron oxide (B2O3) acting as a binder in obtaining dense cell walls. The results revealed that the boric acid has outstanding potential as foaming agent in the fabrication of Al and Al composite foams by providing improved mechanical properties.
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Directory of Open Access Journals (Sweden)
Winnicki M.
2014-10-01
Full Text Available The paper deals with effect of working gas pressure and temperature on surface stereometry of coatings deposited by low-pressure cold spray method. Examinations were focused on aluminium coatings which are commonly used to protect substrate against corrosion. A commercial Al spherical feedstock powder with admixture of Al2O3 (Al + 60vol.-% Al2O3, granulation -50+10 µm, was used to coat steel, grade S235JR. Thedeposited coatings were studied to determine their stereometry, i.e. roughness, transverse and longitudinal waviness, topography of surface and thickness as the functions of gas pressure and temperature. A profilometer and focal microscope were used to evaluate the stereometric properties. In order to reduce the number of variables, the remaining process parameters, i.e. shape and size of de Laval nozzle, nozzle-to-substrate distance, powder mass flow rate, linear velocity of spraying gun, were kept unchanged. The investigation confirmed influence of temperature and pressure on coating thickness as well as on the surface seterometry.
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Electron trapping in neutron-irradiated very thin films of Al2O3
International Nuclear Information System (INIS)
Srivastava, P.C.; Bardhan, A.R.
1979-01-01
Oxide layers of thicknesses less than 100 A have been prepared by thermal-oxidation of a base metal electrode film of aluminium. These films were then neutron-irradiated from a laboratory Ra-Be source to a fluence of approximately 10 11 neutrons cm -2 and the sandwich structure, Al-Al 2 O 3 -Au, was completed by depositing a thin metal film of gold over the irradiated oxide layer. D.C. steady and transient flow through the sandwich structures have been studied. Results obtained in the experiments with irradiated sandwiches have been compared with unirradiated ones to show that traps are introduced because of the damage caused by the incident neutrons. Transient voltage measurement across the junction gives a trap density of approximately 10 18 cm -3 . A capture cross-section of the order 10 -28 cm 2 is estimated for the traps. It is found that the (identified) traps are uniformly distributed within an energy of 0.099 eV below the conduction band edge of aluminium oxide. The physical nature of the traps is discussed by comparing the capture cross-sections of the physically known trapping centres. The possibility of vacancies or F-centres acting as traps (for the identified ones) has been suggested. (author)
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Weldability of Al4C3-Al composites via diffusion welding technique
International Nuclear Information System (INIS)
Arik, Halil; Aydin, Mustafa; Kurt, Adem; Turker, Mehmet
2005-01-01
In this study, Al-Al 4 C 3 composites, produced by powder metallurgy in situ techniques, were joined by diffusion welding technique at 250 MPa pressure with various welding temperatures and durations. Microstructures and shear strengths of the joined areas were determined. Al powders were mixed with 2% carbon black and milled in a high energy ball mill (mechanical alloying) for up to 20 h. In order to obtain cylindrical blanks with 10 mm in diameter and 15 mm in height, powders were compacted in a single action press at 1000 MPa. Samples were sintered in Ar atmosphere at 650 deg C and metal matrix composite (MMC) containing 8% Al 4 C 3 particles were produced. Products were then joined to each other by using diffusion welding techniques. Scanning electron microscopy examination was carried out on the welded interfaces and shear tests were conducted to the sample interfaces to find out the effect of welding temperatures and duration on the weldability properties. It was found that high welding temperatures resulted in increase of both joined strength and shear properties. However, increase in welding duration did not make any detectable changes. Results indicated that MMC could be joined by diffusion welding technique successfully with the 88% strength of base material
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Energy Technology Data Exchange (ETDEWEB)
Santos, Desireé M. de los, E-mail: desire.delossantos@uca.es; Navas, Javier, E-mail: javier.navas@uca.es; Sánchez-Coronilla, Antonio; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Martín-Calleja, Joaquín
2015-10-15
Highlights: • Highly Al-doped TiO{sub 2} nanoparticles were synthesized using a Ball Mill Method. • Al doping delayed anatase to rutile phase transformation. • Al doping allow controlling the structural and electronic properties of nanoparticles. - Abstract: This study presents an easy method for synthesizing highly doped TiO{sub 2} nanoparticles. The Ball Mill method was used to synthesize pure and Al-doped titanium dioxide, with an atomic percentage up to 15.7 at.% Al/(Al + Ti). The samples were annealed at 773 K, 973 K and 1173 K, and characterized using ICP-AES, XRD, Raman spectroscopy, FT-IR, TG, STEM, XPS, and UV–vis spectroscopy. The effect of doping and the calcination temperature on the structure and properties of the nanoparticles were studied. The results show high levels of internal doping due to the substitution of Ti{sup 4+} ions by Al{sup 3+} in the TiO{sub 2} lattice. Furthermore, anatase to rutile transformation occurs at higher temperatures when the percentage of doping increases. Therefore, Al doping allows us to control the structural and electronic properties of the nanoparticle synthesized. So, it is possible to obtain nanoparticles with anatase as predominant phase in a higher range of temperature.
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Electroless Cu Plating on Anodized Al Substrate for High Power LED.
Rha, Sa-Kyun; Lee, Youn-Seoung
2015-03-01
Area-selective copper deposition on screen printed Ag pattern/anodized Al/Al substrate was attempted using a neutral electroless plating processes for printed circuit boards (PCBs), according to a range of variation of pH 6.5-pH 8 at 70 °C. The utilized basic electroless solution consisted of copper(II) sulfate pentahydrate, sodium phosphinate monohydrate, sodium citrate tribasic dihydrate, ammonium chloride, and nickel(II) sulfate hexahydrate. The pH of the copper plating solutions was adjusted from pH 6.5 to pH 8 using NH4OH. Using electroless plating in pH 6.5 and pH 7 baths, surface damage to the anodized Al layer hardly occurred; the structure of the plated Cu-rich films was a typical fcc-Cu, but a small Ni component was co-deposited. In electroless plating at pH 8, the surface of the anodized Al layer was damaged and the Cu film was composed of a lot of Ni and P which were co-deposited with Cu. Finally, in a pH 7 bath, we can make a selectively electroless plated Cu film on a PCB without any lithography and without surface damage to the anodized Al layer.
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Energy Technology Data Exchange (ETDEWEB)
Suzuki, M; Watanabe, S; Yoshimura, N [Akita Univ., Akita (Japan); Fujita, H [The University of Tokyo, Tokyo (Japan)
1992-12-20
Discussions were given on measurements of coefficients for static friction between different types of thin films. A small light-weight mover of a millimeter size was driven electrostatically to measure friction in a condition close to operation of a micromachine. The thin film materials were fabricated using a sol-gel process, sputtering, vacuum deposition and a CVD process. The materials include Ni, Ti, Al, SiO2, SiNx, Si wafers and glasses. The measured values for Ni-Ni, Al-Al and Ni-Al were larger by from 0.1 to 0.2 than values for bulk. The reason for this would be because of the friction generating mechanisms being different and the sample weight being lighter. Measured values for different types of thin films on silicon wafers were higher. This may be because OH groups are formed on the wafer surface causing high adhesiveness. Values for glasses are small in general. Friction coefficients for SiO2 thin films are small on the whole. However, SiO2-SiO2 showed larger values. This indicates that SiO2 is a useful material for micromechatronics, but proper selection of contacting opponents is important. 7 refs., 4 figs., 7 tabs.
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International Nuclear Information System (INIS)
Chen, Cunguang; Guo, Leichen; Luo, Ji; Hao, Junjie; Guo, Zhimeng; Volinsky, Alex A.
2015-01-01
Al matrix composite reinforced by hexagonal boron nitride (h-BN) with nearly full densification was successfully fabricated by the semi-solid powder metallurgy technique. The h-BN/Al composites were synthesized with elemental pure Al powder size of d_5_0=35, 12 and 2 μm. The powder morphology and the structural characteristics of the composites were analyzed using X-ray diffraction, scanning and transmission electron microscopy. The density, Brinell hardness and compressive behavior of the samples were characterized. Density measurement of the Al composites revealed that the composite densification can be effectively promoted by plenty of embedded liquid phase under pressure. Composites prepared using Al powder with varying granularity showed different grain characteristics, and in situ recrystallization occurred inside the original grains with 35 μm Al powder. A sharp interface consisting of Al/Al_2O_3/h-BN was present in the composites. Both the compressive strength and the fracture strain of the investigated composites increased with the decrease of the Al powder size, along with the Brinell hardness. The composite with 2 μm Al powder exhibited the highest relative density (99.3%), Brinell harness (HB 128), compressive strength (763 MPa) and fracture strain (0.299).
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International Nuclear Information System (INIS)
Balog, Martin; Simancik, Frantisek; Walcher, Martin; Rajner, Walter; Poletti, Cecilia
2011-01-01
Highlights: → 25 gas atomised Al 99.5% powders with particle size 2 O 3 dispersoids. → Compacts showed good thermal stability due to grain pinning of Al 2 O 3 dispersoids. - Abstract: Twenty-five samples of commercially available, gas-atomised Al (99.5%) powders with particle sizes 2 O 3 composites formed in situ during extrusion. The effect of particle size, surface area, oxygen content and atomisation atmosphere of the powder on the microstructure and mechanical properties of the extruded compacts were studied by Brunauer, Emmett, Teller (BET) analysis, hot gas extraction, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and tensile tests. Thermal stability of the compacts and the individual strengthening mechanisms operating in the compacts were discussed. It was found that the properties of the compacts stemmed from the extraordinary grain boundary strengthening effect of the ultrafine-grained compacts due to their microstructures. The efficiency of the grain boundary strengthening was significantly enhanced by the presence of nano-metric Al 2 O 3 dispersoids introduced in situ. The strength of the compacts was closely related to the surface area of the powder particles. In addition, the entrapped gasses and chemically bonded humidity had a negative effect on the mechanical properties of the compacts.
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Czech Academy of Sciences Publication Activity Database
Besterci, M.; Dobeš, Ferdinand; Ballóková, B.; Sülleiová, K.; Kvačkaj, T.
2011-01-01
Roč. 30, č. 3 (2011), s. 205-210 ISSN 0334-6455 R&D Projects: GA AV ČR 1QS200410502; GA AV ČR IAA200410801 Grant - others:Vega(SK) 2/0025/11 Institutional research plan: CEZ:AV0Z20410507 Keywords : Equal channel angular pressing * small-punch creep * fracture * metal-matrix composites Subject RIV: JI - Composite Materials Impact factor: 0.242, year: 2011
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Paez-Leon, Cristobal D.; Patino, Antonio R.; Aguillon, Luis
1991-03-01
This paper describes the results of a five-year study carried out in 38 power substations (230, 115, 34.5 and 13.8 Kv), located in the Western power electric system of CADAFE (Venezuela's national Electric Utility). A total of 154 hot spots were found between 1980 and 1982, a time span considered a reliable source of information in connection with methodology, term and results. The distribution of hot spots found during those years was 77, 33 and 44. The reduction of the spot/substation parameter was found to be 4.1, 3.3 and 3.1, respectively. Every item detected could have been the cause of major interruptions, locally and regionally, or even the system's blackout. The methodology used to determine the major concentration of findings and their location on the equipment, followed the sequence of Pareto's Diagram and Ishikawa's Graphic. Based on the results of the study whose results are presented here, a lubricant and compound-aid connector for Al-Al and bimetallic electric connections was formulated, developed, manufactured, tested (at IREQ laboratories) and traded (CONECTECH CAC- 01). To date, the whole process represents 12 years of work. The connector's behavior and reliability are being tested throughout Venezuela's national electric system (responsible for the supply of around 50,000 Gwh/year) with the use of 12 Tons of CONECTECH CAC-01.
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Electronic structure and interatomic bonding in Al10V
International Nuclear Information System (INIS)
Jahnatek, M; Krajci, M; Hafner, J
2003-01-01
On the basis of ab initio calculations we analysed the electron density distribution in the elementary cell of the compound Al 10 V. We found covalent bonding between certain atoms. The Al-V bonds of enhanced covalency are linked into -Al-V-Al-V- chains that extend over the whole crystal. The chains intersect at each V site and together form a Kagome network of corner-sharing tetrahedra. The large voids of this network are filled by Z 16 Friauf polyhedra consisting of Al atoms only. The skeleton of the Friauf polyhedron has the form of a truncated tetrahedron and consists of 12 strongly bonded Al atoms. These Al-Al bonds also have covalent character. The bonding is dominated by sp 2 hybridization. The centre of the Friauf polyhedron may be empty or occupied by an Al atom. The thermodynamic stability of the phase is investigated. The Al 21 V 2 phase with occupied voids is at low temperatures less stable than Al 10 V. The Al 10 V structure can be considered as a special case of the Al 18 Cr 2 Mg 3 structural class. We have found the same picture of bonding as we report here for Al 10 V for several other aluminium-rich alloys belonging to the Al 18 Cr 2 Mg 3 structural class also
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International Nuclear Information System (INIS)
Kirihara, K.; Nagata, T.; Kimura, K.; Kato, K.; Takata, M.; Nishibori, E.; Sakata, M.
2003-01-01
X-ray charge densities of Al-based icosahedral quasicrystalline approximant crystals α-AlReSi, α-AlMnSi, and Al 12 Re were observed by a combination of the maximum entropy method with the Rietveld method. We successfully obtained the clear images of interatomic covalent bonds between Al and transition metals (Mn, Re) and those in the Al (or Si) icosahedron in Mackay icosahedral clusters of both α-AlReSi and α-AlMnSi approximant crystals. The bonding nature of the three kinds of glue atom sites connecting Mackay icosahedral clusters was also clarified. This covalent bonding nature should strongly relate with the enhancement of the electron density-of-states pseudogap near the Fermi level. In addition, the interatomic covalent bonds of α-AlReSi are stronger than those of α-AlMnSi. This fact leads to the low effective carrier density of α-AlReSi in comparison with that of α-AlMnSi. Unlike the covalent bonding nature of an icosahedron in α-AlReSi and α-AlMnSi crystals, the Al icosahedron with an Re center atom exhibits no Al-Al interatomic covalent bonds in the Al 12 Re crystal. The tendency for metallic-covalent bonding conversion in the Al icosahedron, which is related to the atom site occupancy of the icosahedral cluster center, is also strongly supported
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Laser synthesis of aluminium nanoparticles in biocompatible polymer solutions
Singh, Rina; Soni, R. K.
2014-08-01
Pulsed laser ablation of Aluminium (Al) in pure water rapidly forms a thin alumina (Al2O3) layer which drastically modifies surface plasmon resonance (SPR) absorption characteristics in deep-UV region. Initially, pure aluminium nanoparticles (NPs) are generated in water without any stabilizers or surfactants at low laser fluence which gradually transform to stable Al-Al2O3 core-shell nanostructure with increasing either residency time or fluence. The role of laser wavelength and fluence on the SPR properties and oxidation characteristics of Al NPs has been investigated in detail. We also present a one-step in situ synthesis of oxide-free stable Al NPs in biocompatible polymer solutions using laser ablation in liquid method. We have used nonionic polymers (PVP, PVA and PEG) and anionic surfactant (SDS) stabilizer to suppress the Al2O3 formation and studied the effect of polymer functional group, polymeric chain length, polymer concentration and anionic surfactant on the incipient embryonic aluminium particles and their sizes. The different functional groups of polymers resulted in different oxidation states of Al. PVP and PVA polymers resulted in pure Al NPs; however, PEG and SDS resulted in alumina-modified Al NPs. The Al nanoparticles capped with PVP, PVA, and PEG show a good correlation between nanoparticle stability and monomeric length of the polymer chain.
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Directory of Open Access Journals (Sweden)
Hongzhong Li
2014-01-01
Full Text Available Marine siliceous rocks are widely distributed in the central orogenic belt (COB of China and have a close connection to the geological evolution and metallogenesis. They display periodic distributions from Mesoproterozoic to Jurassic with positive peaks in the Mesoproterozoic, Cambrian—Ordovician, and Carboniferous—Permian and their deposition is enhanced by the tensional geological settings. The compressional regimes during the Jinning, Caledonian, Hercynian, Indosinian, and Yanshanian orogenies resulted in sudden descent in their distribution. The siliceous rocks of the Bafangshan-Erlihe ore deposit include authigenic quartz, syn-depositional metal sulphides, and scattered carbonate minerals. Their SiO2 content (71.08–95.30%, Ba (42.45–503.0 ppm, and ΣREE (3.28–19.75 ppm suggest a hydrothermal sedimentation origin. As evidenced by the Al/(Al + Fe + Mn, Sc/Th, (La/YbN, and (La/CeN ratios and δCe values, the studied siliceous rocks were deposited in a marginal sea basin of a limited ocean. We suggest that the Bafangshan-Erlihe area experienced high- and low-temperature stages of hydrothermal activities. The hydrothermal sediments of the former stage include metal sulphides and silica, while the latter was mainly composed of silica. Despite the hydrothermal sedimentation of the siliceous rocks, minor terrigenous input, magmatism, and biological activity partly contributed to geochemical features deviating from the typical hydrothermal characteristics.
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Fabrications and application of single crystalline GaN for high-performance deep UV photodetectors
Energy Technology Data Exchange (ETDEWEB)
Velazquez, R.; Rivera, M.; Feng, P., E-mail: p.feng@upr.edu [Department of Physics, College of Natural Sciences, University of Puerto Rico, San Juan, 00936-8377, PR/USA (Puerto Rico); Aldalbahi, A. [Department of Chemistry, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia)
2016-08-15
High-quality single crystalline Gallium Nitride (GaN) semiconductor has been synthesized using molecule beam epitaxy (MBE) technique for development of high-performance deep ultraviolet (UV) photodetectors. Thickness of the films was estimated by using surface profile meter and scanning electron microscope. Electronic states and elemental composition of the films were obtained using Raman scattering spectroscopy. The orientation, crystal structure and phase purity of the films were examined using a Siemens x-ray diffractometer radiation. The surface microstructure was studied using high resolution scanning electron microscopy (SEM). Two types of metal pairs: Al-Al, Al-Cu or Cu-Cu were used for interdigital electrodes on GaN film in order to examine the Schottky properties of the GaN based photodetector. The characterizations of the fabricated prototype include the stability, responsivity, response and recovery times. Typical time dependent photoresponsivity by switching different UV light source on and off five times for each 240 seconds at a bias of 2V, respectively, have been obtained. The detector appears to be highly sensitive to various UV wavelengths of light with very stable baseline and repeatability. The obtained photoresponsivity was up to 354 mA/W at the bias 2V. Higher photoresponsivity could be obtained if higher bias was applied but it would unavoidably result in a higher dark current. Thermal effect on the fabricated GaN based prototype was discussed.
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EESTI KEELEKOGUKONNA SÄILIMISEST TAANIS
Directory of Open Access Journals (Sweden)
Maarika Teral
2010-01-01
Full Text Available Käesolev artikkel keskendub Taanis elavatele, põhiliselt Teise maailmasõja ajal ja järel sinna ümber asunud eestlaste ning nende järeltulijate eesti keele kasutuse vaatlemisele. Taani eestlaste kogukond on suhteliselt väike ning on jäänud teiste, suuremate väliseesti kogukondade varju. Taani eestlaste esimeseks põlvkonnaks nimetatakse artiklis neid eestlasi, kes tulid Taani Teise maailmasõja ajal. Teise põlvkonna moodustavad nende lapsed, kes on sündinud juba väljaspool Eestit. Esimene Taani eestlaste põlvkond, kes lahkus Eestist kodumaal omandatud eesti keelega ja on seda keelt läbi pagulasaastate alal hoidnud, on hääbumas, paljud neist on viimastel aastatel elust lahkunud. Pärast Teist maailmasõda või selle ajal sündinud teise põlvkonna taanieestlasi, kes räägivad eesti keelt, on vähem kui elusolevaid esimese põlvkonna taanieestlasi. Carol-Myers Scotton on välja toonud rea faktoreid, mis mõjutavad keele säilimist ja/või vahetust, jagades need kolme rühma: ühiskondlikud, grupisisesed ning individuaalsed (2006. Artiklis analüüsitakse Taani eestlaste eesti keele säilimist ja/või vahetust mõjutavaid tegureid, lähtudes Myers-Scottoni välja toodud faktoritest, tegemaks kindlaks, kas ülekaalus on keele säilitamist või vahetust soosivad tegurid.
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Novel technologies for the lost foam casting process
Jiang, Wenming; Fan, Zitian
2018-03-01
Lost foam casting (LFC) is a green precision casting process categorized as a near net forming technology. Yet, despite its popularity, it still suffers from some technological problems, such as poor filling ability of the castings, coarse and non-dense microstructure, low mechanical properties for the Al and Mg LFC processes, and defective carburization for the low carbon steel LFC process. These drawbacks restrict the development and widespread application of the LFC process. To solve these problems, the present study developed several novel LFC technologies, namely, LFC technologies under vacuum and low pressure, vibration solidification, and pressure solidification conditions; expendable shell casting technology; and preparation technology of bimetallic castings based on the LFC process. The results showed that the LFC under vacuum and low pressure evidently improved the filling ability and solved the oxidization problem of the alloys, which is suitable for producing complex and thinwall castings. The vibration and pressure solidifications increased the compactness of the castings and refined the microstructure, significantly improving the mechanical properties of the castings. The expendable shell casting technology could solve the pore, carburization, and inclusion defects of the traditional LFC method, obtaining castings with acceptable surface quality. Moreover, the Al/Mg and Al/Al bimetallic castings with acceptable metallurgical bonding were successfully fabricated using the LFC process. These proposed novel LFC technologies can solve the current technological issues and promote the technological progress of the LFC process.
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International Nuclear Information System (INIS)
Grin, J.; Burkhardt, U.; Ellner, M.; Peters, K.
1994-01-01
The crystal structure of Fe 4 Al 13 was refined using single crystal diffractometer data: pearson symbol mC102, space group C2/m; a=15.492(2) A, b=8.078(2) A, c=12.471(1) A, β=107.69(1) ; R F =0.053, R F (w)=0.044 for 1127 reflections and 137 refined parameters. The coordination numbers of atoms are 9, 10, 11 for iron and 10, 12, 13, 14 for aluminium. The shortest interatomic distances are: Fe-Fe - 2.902 A, Fe-Al - 2.374 A, Al-Al - 2.533 A. A preferred occupation of pentagonal prismatic coordinated positions by aluminium was found. The structural relationship between the Fe 4 Al 13 structure and chemically homologous and homeotypical structures of aluminium and gallium containing systems with the 3d transition metals is discussed. The greatest similarity was found concerning the coordination polyhedra, especially that of transition metal atoms. The main common feature of these homeotypical structures is the presence of pentagonal ''channels'', which is strongly dependent on the chemical composition. With increasing atomic number of the 3d transition metal, the stability range of these structures shifts to the transition metal-rich concentration. It is concluded that there is a connection between the occurrence of aluminium and gallium-containing decagonal and icosahedral phases and the existence of the infinite one-dimensional pentagonal channels in the intermetallic compounds showing a similar chemical composition. (orig.)
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Matori, Khamirul Amin; Ostovan, Farhad; Abdul Aziz, Sidek; Mamat, Md Shuhazlly
2017-01-01
The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al2O3 (Al-5Al2O3) has been investigated. Al-5Al2O3 nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al2O3 nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD) analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness (HV), nano-hardness (HN), and Young’s modulus (E) of Al-5Al2O3 nanocomposites. HV, HN, and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively. PMID:29072632
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Directory of Open Access Journals (Sweden)
Meysam Toozandehjani
2017-10-01
Full Text Available The effect of milling time on the morphology, microstructure, physical and mechanical properties of pure Al-5 wt % Al2O3 (Al-5Al2O3 has been investigated. Al-5Al2O3 nanocomposites were fabricated using ball milling in a powder metallurgy route. The increase in the milling time resulted in the homogenous dispersion of 5 wt % Al2O3 nanoparticles, the reduction of particle clustering, and the reduction of distances between the composite particles. The significant grain refining during milling was revealed which showed as a reduction of particle size resulting from longer milling time. X-Ray diffraction (XRD analysis of the nanocomposite powders also showed that designated ball milling contributes to the crystalline refining and accumulation of internal stress due to induced severe plastic deformation of the particles. It can be argued that these morphological and microstructural variations of nanocomposite powders induced by designated ball milling time was found to contribute to an improvement in the density, densification, micro-hardness (HV, nano-hardness (HN, and Young’s modulus (E of Al-5Al2O3 nanocomposites. HV, HN, and E values of nanocomposites were increased by ~48%, 46%, and 40%, after 12 h of milling, respectively.
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International Nuclear Information System (INIS)
Ildefonse, P.; Calas, G.; Flank, A.M.; Lagarde, P.
1995-01-01
Soft X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy have been performed at the Mg-, Al- and Si-K edges in order to establish the ability of this spectroscopy to derive structural information in disordered solids such as glasses and gels. Mg- and Al-K XANES are good structural probes to determine the coordination state of these elements in important minerals, glasses and gels. In a CaO-MgO-2SiO 2 glass Mg XANES spectra differ from that found in the crystalline equivalent, with a significant shift of the edge maxima to lower energy, consistent with a CN lower than 6. Mg-EXAFS on the same sample are in agreement and indicate the presence of 5-coordinated Mg with Mg-O distances of 2.01 A. In aluminosilicate gels, Al-K XANES has been used to investigate the [4]Al/Al total ratios. These ratios increase as the Al/Si ratios decrease. Aluminosilicate and ferric-silicate gels were studied by using Si-K edge XANES. XANES spectra differ significantly among the samples studied. Aluminosilicate gels with Al/Si=1 present a different Al and Si local environment from that known in clay minerals with the same Al/Si ratio. The gel-to-mineral transformation thus implies a dissolution-recrystallization mechanism. On the contrary, ferric-silicate gel presents a Si local environment close to that found in nontronite which may be formed by a long range ordering of the initial gels. (orig.)
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International Nuclear Information System (INIS)
Ezatpour, H.R.; Torabi Parizi, M.; Sajjadi, S.A.; Ebrahimi, G.R.; Chaichi, A.
2016-01-01
Aluminum metal-matrix nanocomposites (AMMNCs) fabricated by conventional stir-casting process usually show high porosity and poor distribution of nanoparticles within the matrix. In the current study, for the improvement of nanoparticles distribution in the aluminum matrix and enhancement of the mechanical properties, a mixture of Al/nano-Al 2 O 3 powders were injected by pure argon gas into the molten 7075 aluminum alloy and this mixture was extruded at high temperature. Mechanical behavior of the final product was investigated by tensile and compression tests, hardness measurements, Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM) and Optical Microscopy. This nanocomposite exhibited some superior properties such as a fine grain microstructure and a reasonable uniform distribution of nanoparticles in the matrix. Mechanical experiments results confirmed that the addition of Al 2 O 3 nanoparticles and the extrusion process effectively improved ultimate tensile strength, compression strength and hardness. In next step, we used a Preference Selection Index (PSI) materials selection method to select best combination of strength and workability of Al7075−Al 2 O 3 nanocomposites. By this method, extruded Al7075/0.4 and 0.8 wt % Al 2 O 3 has best combination of strength and workability. - Highlights: • Injection Al/Al 2 O 3 powder is benefit way for improving nanoparticles distribution. • Nanocomposites present superior mechanical properties. • Extrusion process improved significantly mechanical properties of nanocomposites. • Preference Selection Index is a simple and benefit method in material selection.
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Directory of Open Access Journals (Sweden)
Devendra Lal
2002-01-01
Full Text Available The elements Be and Al exhibit very short residence time in ocean waters, and therefore serve as useful tracers for the study of biogeochemical processes in seawater. A unique feature of these tracers is that nuclear interactions of cosmic rays in the atmosphere produce appreciable amounts of two radioactive isotopes, 10Be (with a half-life of 1.5 my and 26Al (with a half-life of 0.7 my, which are introduced in the hydrosphere, cryosphere, and lithosphere via precipitation. Thus, these elements are labeled by their respective radioactive isotopes, which help quantitative tagging of their biogeochemical cycles. Finally, as we report here, several marine organisms incorporate them in their skeletal shells in certain fixed proportions to their concentrations in the seawater, so that it seems possible to study changes in the ocean chemistry and climate over the past several million years. We summarize here the recent discovery by Dong et al.[9] of significant enrichments of intrinsic Be and Al in marine foraminiferal calcite and coral aragonite, and of Al in opal (radiolarians and aragonite (corals, which should make it possible to determine 10Be/Be and 26Al/Al in oceans in the past. We also summarize their measured 10Be/9Be in foraminiferal calcite in Pacific Ocean cores, which reveal that the concentrations and ratios of the stable and cosmogenic isotopes of Be and Al have varied significantly in the past 30 ky. The implications of these results are discussed.
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Sebban, P; Maróti, P; Schiffer, M; Hanson, D K
1995-07-04
Two point mutants from the purple bacterium Rhodobacter capsulatus, both modified in the M protein of the photosynthetic reaction center, have been studied by flash-induced absorbance spectroscopy. These strains carry either the M231Arg --> Leu or M43ASN --> Asp mutations, which are located 9 and 15 A, respectively, from the terminal electron acceptor QB. In the wild-type Rb. sphaeroides structure, M231Arg is involved in a conserved salt bridge with H125Glu and H232Glu and M43Asn is located among several polar residues that form or surround the QB binding site. These substitutions were originally uncovered in phenotypic revertants isolated from the photosynthetically incompetent L212Glu-L213Asp --> Ala-Ala site-specific double mutant. As second-site suppressor mutations, they have been shown to restore the proton transfer function that is interrupted in the L212Ala-L213Ala double mutant. The electrostatic effects that are induced in reaction centers by the M231Arg --> Leu and M43Asn --> Asp substitutions are roughly the same in either the double-mutant or wild-type backgrounds. In a reaction center that is otherwise wild type in sequence, they decrease the free energy gap between the QA- and QB- states by 24 +/- 5 and 45 +/- 5 meV, respectively. The pH dependences of K2, the QA-QB QAQB- equilibrium constant, are altered in reaction centers that carry either of these substitutions, revealing differences in the pKas of titratable groups compared to the wild type.(ABSTRACT TRUNCATED AT 250 WORDS)
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International Nuclear Information System (INIS)
Nguyen Thanh Tuy; Luong Duc Long
2008-01-01
Cement is produced by heating naturally occurring raw materials containing the required oxides in kiln, which results in a product called clinker. To obtain the finished cement, the clinker is then ground together with gypsum, which controls setting properties, to a fine powder. Portland cement is a mixture of compounds formed from the oxides of Ca(CaO), Si(SiO 2 ), Al(Al 2 O 3 ), and Fe(Fe 2 O 3 ). In addition to these four main constituents it also contains smaller amounts of MgO, K 2 O, SO 3 , etc. Effective process control of cement is important to ensure high quality of the product. Traditionally wavelength dispersive x-ray fluorescence (WDXRF) spectrometers are used for cement quality control at the modern cement factories. The XRF-NCS02 is a compact energy dispersive X-ray fluorescence (EDXRF) analyzer. These spectrometers also are used for cement quality control at the small size cement plant. Product description: The XRF-NCS02 , table-top cement analyzer is a computer-based EDXRF spectrometer. The high efficiency and high resolution Si PIN detector is coupled to a 4096 channel MCA for data collection. The special low-power x-ray tube of the system requires no cooling and obligates the need for radioisotopes, as commonly found on such instruments. Computer: Compatible notebook or desktop PC, Pentium processor with CD-ROM. Software: XRF - NCS02 software for quantitative analysis; Interactive, operation under Windows XP. Installation: dimensions 500x380x300 mm (W x D x H); weight: 10 kg. (author)
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International Nuclear Information System (INIS)
Chauhan, Lalit; Gupta, Suman; Jaiswal, Piyush; Bhat, Navakanta; Shivashankar, S.A.; Hughes, G.
2015-01-01
The effect of inserting ultra-thin atomic layer deposited Al 2 O 3 dielectric layers (1 nm and 2 nm thick) on the Schottky barrier behaviour for high (Pt) and low (Al) work function metals on n- and p-doped InGaAs substrates has been investigated. Rectifying behaviour was observed for the p-type substrates (both native oxide and sulphur passivated) for both the Al/p-InGaAs and Al/Al 2 O 3 /p-InGaAs contacts. The Pt contacts directly deposited on p-InGaAs displayed evidence of limited rectification which increased with Al 2 O 3 interlayer thickness. Ohmic contacts were formed for both metals on n-InGaAs in the absence of an Al 2 O 3 interlayer, regardless of surface passivation. However, limited rectifying behaviour was observed for both metals on the 2 nm Al 2 O 3 /n-InGaAs samples for the sulphur passivated InGaAs surface, indicating the importance of both surface passivation and the presence of an ultra-thin dielectric interlayer on the current–voltage characteristics displayed by these devices. - Highlights: • Investigation of the modification of metal–InGaAs Schottky barrier (SB) behaviour • Improving metal–InGaAs interface by sulphur passivation and ultrathin interlayer • Examine the effect of low work function and high work function metals on SB • Different SB behaviours observed on both n-type InGaAs and p-type InGaAs • Metal/n-InGaAs interface is more strongly pinned than the metal/p-InGaAs interface
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Phonon optimized interatomic potential for aluminum
Directory of Open Access Journals (Sweden)
Murali Gopal Muraleedharan
2017-12-01
Full Text Available We address the problem of generating a phonon optimized interatomic potential (POP for aluminum. The POP methodology, which has already been shown to work for semiconductors such as silicon and germanium, uses an evolutionary strategy based on a genetic algorithm (GA to optimize the free parameters in an empirical interatomic potential (EIP. For aluminum, we used the Vashishta functional form. The training data set was generated ab initio, consisting of forces, energy vs. volume, stresses, and harmonic and cubic force constants obtained from density functional theory (DFT calculations. Existing potentials for aluminum, such as the embedded atom method (EAM and charge-optimized many-body (COMB3 potential, show larger errors when the EIP forces are compared with those predicted by DFT, and thus they are not particularly well suited for reproducing phonon properties. Using a comprehensive Vashishta functional form, which involves short and long-ranged interactions, as well as three-body terms, we were able to better capture interactions that reproduce phonon properties accurately. Furthermore, the Vashishta potential is flexible enough to be extended to Al2O3 and the interface between Al-Al2O3, which is technologically important for combustion of solid Al nano powders. The POP developed here is tested for accuracy by comparing phonon thermal conductivity accumulation plots, density of states, and dispersion relations with DFT results. It is shown to perform well in molecular dynamics (MD simulations as well, where the phonon thermal conductivity is calculated via the Green-Kubo relation. The results are within 10% of the values obtained by solving the Boltzmann transport equation (BTE, employing Fermi’s Golden Rule to predict the phonon-phonon relaxation times.
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Phonon optimized interatomic potential for aluminum
Muraleedharan, Murali Gopal; Rohskopf, Andrew; Yang, Vigor; Henry, Asegun
2017-12-01
We address the problem of generating a phonon optimized interatomic potential (POP) for aluminum. The POP methodology, which has already been shown to work for semiconductors such as silicon and germanium, uses an evolutionary strategy based on a genetic algorithm (GA) to optimize the free parameters in an empirical interatomic potential (EIP). For aluminum, we used the Vashishta functional form. The training data set was generated ab initio, consisting of forces, energy vs. volume, stresses, and harmonic and cubic force constants obtained from density functional theory (DFT) calculations. Existing potentials for aluminum, such as the embedded atom method (EAM) and charge-optimized many-body (COMB3) potential, show larger errors when the EIP forces are compared with those predicted by DFT, and thus they are not particularly well suited for reproducing phonon properties. Using a comprehensive Vashishta functional form, which involves short and long-ranged interactions, as well as three-body terms, we were able to better capture interactions that reproduce phonon properties accurately. Furthermore, the Vashishta potential is flexible enough to be extended to Al2O3 and the interface between Al-Al2O3, which is technologically important for combustion of solid Al nano powders. The POP developed here is tested for accuracy by comparing phonon thermal conductivity accumulation plots, density of states, and dispersion relations with DFT results. It is shown to perform well in molecular dynamics (MD) simulations as well, where the phonon thermal conductivity is calculated via the Green-Kubo relation. The results are within 10% of the values obtained by solving the Boltzmann transport equation (BTE), employing Fermi's Golden Rule to predict the phonon-phonon relaxation times.
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Electrocoagulation Process for Treatment of Detergent and Phosphate
Directory of Open Access Journals (Sweden)
Afshin Takdastan
2017-01-01
Full Text Available Background & Aims of the Study: Detergent and phosphate are one of the main and vital threats (eutrophication phenomenon and production of synthetic foam for the source of drinking water, agriculture and industrial uses in the Ahvaz, Iran that threaten human health. The aim of this study is the evaluation of the efficiency of the electrocoagulation (EC process in the removal of detergent and phosphate from car wash effluent. Materials & Methods: In this experimental study, we used a glass tank with a volume of 2-4 liters (effective volume of 2 liters containing 4 electrode-plate iron and aluminum (AL-AL, AL-Fe, Fe-Fe. Bipolar method was used to convert alternative electricity to direct; electrodes were connected to a power supply. Daily samples were collected from different car washes sewage. Initial PHs of samples was from 7 to 9. At first, different tests were performed on primary samples. Reaction times were set for 90, 60 and 30 minutes with middle intervals of 2 cm. Results: According to the result of this study, percentage of phosphate removal in the EC with Al-Fe electrode, with an optimum pH = 7, has been from 34 % (in the 10 Volt to 78% (in the 30 Volt. Percentage of detergent removal in the EC with AL electrode, with an optimum pH = 7, has been from 68 % (in the 10 Volt to 94% (in the 30 Volt. Conclusions: Altogether, it was found that this method can be used as a confident and convenient method for treating car wash effluent and according to the highest removal efficiency of the process, effluent can be discharged safely into the environment.
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Sarma, Nittala S.; Kiran, Rayaprolu; Rama Reddy, M.; Iyer, Sridhar D.; Peketi, A.; Borole, D. V.; Krishna, M. S.
2018-01-01
Anomalously high concentrations of humic-rich dissolved organic matter (DOM) in extant submarine hydrothermal vent plumes traveled far from source are increasingly being reported. This DOM, able to mobilize trace metals (e.g., Fe2+) has been hypothesized as originating from organic matter produced by thermogenic bacteria. To eliminate a possible abiogenic origin of this DOM, study is required of well-preserved organic compounds that can be attributed to thermogenic bacteria. The Central Indian Ocean Basin (CIOB) is part of a diffuse plate boundary and an intraplate deformation zone. Coarse fraction (>63 µ) characteristics, mineralogy, magnetic susceptibility, and geochemistry were examined in sediments of a core raised close to a north-south fracture zone near the Equator. Two horizons of distinctly brown-colored sediments were shown as hydrothermally altered from their charred fragments and geochemistry (CaCO3, Corg, Ti/Al, Al/(Al + Fe + Mn), Sr/Ba, Mg/Li, Mn micronodules, Fe/Mn). We examined whether humic substances were preserved in these sediments, and if so whether their carbon isotope distribution would support their hydrothermal origin. Alkali extraction of sediments afforded humic acids (HA) in yields up to 1.2% in the brown sediments. The remaining portions of the core had nil or low concentrations of HA. The carbon of hydrothermal HA is isotopically heavier (average δ13C, ˜ -16.3‰) compared to nonhydrothermal HA (-18.1‰), suggesting that they were probably formed from organic matter that remained after elimination of lighter carbon enriched functional groups during diagenesis. The results provide compelling evidence of HA formation from lipids originating from thermogenic bacteria.
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Directory of Open Access Journals (Sweden)
Soubhagya Ranjan Tripathy
2016-12-01
Conclusion: For routine neurosurgical practice, these entities are extremely rare; and hence a working knowledge is very essential for appropriate & timely management notwithstanding the neurosurgical desire to rule out the compressive lesions first. Neurological status deterioration may be halted with timely institution of appropriate chemotherapy. In the extensive literature review in pubmed, this may be only the 1st case of MPAL with extramedullary neurological manifestation, at the first clinical presentation.
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A study of atomic distribution in the intermetallic compound by AP-FIM
International Nuclear Information System (INIS)
Ren, D.G.
1993-01-01
This paper reports a study of the atomic distributions in the intermetallic compound by field ion microscope and atom probe (AP-FIM). The samples used in this work had nearly stoichiometry composition of Ni 3 Al with boron and without boron. The samples of TiAl also had nearly stoichiometry composition and adding Zr and Mn. The field ion image of Ni 3 Al without boron displays essentially the ordered f.c.c. crystal structure (Ll 2 ) with the center of (001) face. The field ion image of B-doped Ni 3 Al shows that the extent of ordering is reduced by addition of boron. The results of AP analysis show that the distribution of boron atom in Ni 3 Al is approximately homogeneous for the low boron contents. The atomic arrangements of Ni and Al in Ni 3 Al crystal lattice were changed by addition of boron. It is shown in the probability of consecutive evaporative sequence Al-Al and Ni-Ni is increased with B-doping. The field ion image of TiAl shows two regions with ordered f.c.t crystal structure (r-TiAl) and disordered. The distributions of Ti and Al atoms in the TiAl alloy show that the structure of a lamellar mixture were confirmed by AP profiles. The results of AP analysis show that distributions of Ti, Al, Mn and Zr in the alloy essentially is homogeneous. The results of AP analysis also exhibit that the interface of an oxide exists in the alloys. These interfaces of oxides consist of TiO and AlO in the TiAl, NiO in the Ni 3 Al. The broadness of the oxides interface were estimated about 8-10nm
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Calculation of solidification microstructure maps for the system Al-Fe-Si
International Nuclear Information System (INIS)
Gilgien, P.
1996-01-01
Computer programs have been developed in order to calculate solidification microstructure maps for binary and ternary alloys. These programs are based on recent analytical models for the constrained growth of dendrites and eutectics. Due to the importance of phase diagrams data, programs for the calculation of growth kinetics are coupled with ThermoCalc, a commercial software for phase diagram calculations. These programs have been used to calculate a solidification microstructure map for the Al-Fe system from 0 to 4 at%Fe. Comparison of the calculated results with an experimental solidification microstructure map from the literature shows that all microstructure transitions were predicted. Nevertheless there remain significant discrepancies between some calculated and experimental transition velocities. The programs were also used to calculate solidification microstructure maps in the Al-rich corner of the Al-Fe-Si system (0 to 8 at% Fe and 0 to 8 at% Si). In this case also, calculated results were in satisfactory agreement with experimental solidification microstructure maps, although the comparison was only partial since experimental ternary microstructure maps are less complete than for the binary system, and because the available thermodynamic database does not, as yet, include metastable phases. Laser surface remelting experiments were carried out on an Al-4 at% Fe alloy in order to link results from the literature, obtained at high solidification rates by laser surface remelting and at low solidification rates by Bridman experiments. Finally, Bridman experiments were carried out with an Al-2.63 wt% Fe alloy in order to determine the critical velocity at which a planar Al-Al 13 Fe 4 eutectic front is destabilised in a cellular eutectic by a small amount of Si. The critical solidification velocity thus obtained was in agreement with a criterion of constitutional undercooling. (author) figs., tabs., refs
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Directory of Open Access Journals (Sweden)
Afshin Takdastan
2011-10-01
Full Text Available This study evaluated the efficiency of Electrical coagulation process in removal of COD, turbidity, detergent and phosphate from carwash effluent. An experimental study in laboratory scale was carried out and a glass tank with volume of 3 liters (effective volume of 2 liters containing 4 electrode-page iron and aluminum (AL-AL, AL-Fe, Fe-Fe were used. Electrodes were connected to a power supply with using bipolar method to convert alternative electricity to direct current. Daily samples were collected from different carwash effluents. Initial pH of samples were reported between 7 to 9.At first different tests were performed on primary samples. Percentage of removal was calculated in range pH and electrical potential of 11, 7, 3 and 30, 20, 10 volts respectively. Reaction times were set 90, 60, 30 minutes with middle intervals of 2 cm. The results showed the efficiency of COD removal in the optimum range of pH=3, voltage of 30 and retention time of 90 minutes removal efficiency in pH of 7 after 90 minutes retention time, voltage of 30, with aluminum electrode reached more than 99%. According to the results obtained electrical energy consumption in aluminum electrodes was less than others. However aluminum is more expensive than iron and the difference in energy consumption between iron and aluminum can be ingnored. Apart from that COD and detergent removal efficiency of iron electrodes is higher than aluminum electrodes therefore, using iron as the electrode is more economical and recommended. Altogether it was found that this method can be use as a safe and convenient method for treating carwash effluent and according to the high removal efficiency of process, effluent can be discharged safely into the environment.
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Double-Barrier Memristive Devices for Unsupervised Learning and Pattern Recognition.
Hansen, Mirko; Zahari, Finn; Ziegler, Martin; Kohlstedt, Hermann
2017-01-01
The use of interface-based resistive switching devices for neuromorphic computing is investigated. In a combined experimental and numerical study, the important device parameters and their impact on a neuromorphic pattern recognition system are studied. The memristive cells consist of a layer sequence Al/Al 2 O 3 /Nb x O y /Au and are fabricated on a 4-inch wafer. The key functional ingredients of the devices are a 1.3 nm thick Al 2 O 3 tunnel barrier and a 2.5 mm thick Nb x O y memristive layer. Voltage pulse measurements are used to study the electrical conditions for the emulation of synaptic functionality of single cells for later use in a recognition system. The results are evaluated and modeled in the framework of the plasticity model of Ziegler et al. Based on this model, which is matched to experimental data from 84 individual devices, the network performance with regard to yield, reliability, and variability is investigated numerically. As the network model, a computing scheme for pattern recognition and unsupervised learning based on the work of Querlioz et al. (2011), Sheridan et al. (2014), Zahari et al. (2015) is employed. This is a two-layer feedforward network with a crossbar array of memristive devices, leaky integrate-and-fire output neurons including a winner-takes-all strategy, and a stochastic coding scheme for the input pattern. As input pattern, the full data set of digits from the MNIST database is used. The numerical investigation indicates that the experimentally obtained yield, reliability, and variability of the memristive cells are suitable for such a network. Furthermore, evidence is presented that their strong I - V non-linearity might avoid the need for selector devices in crossbar array structures.
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International Nuclear Information System (INIS)
Huang, J. C.
1997-01-01
Wide applications of superplastic forming still face several problems, one is the high temperature that promotes grain growth, another is the low forming rate that makes economically inefficient. The current study is intended to develop a series of fabrication and thermomechanical processing, so as to result in materials possessing either low temperature superplasticity (LTSP) or high rate superplasticity (HRSP). The former has been achieved in the cast Al alloys, while the latter was accomplished in powder-metallurgy aluminium matrix composites. The aluminium alloys, after special thermomechanical processes, exhibited LTSP from 300 to 450 degree C with elongations varying from 300 to 700 %. The LTSP sheets after 700 % elongation at 350 degree C still possessed fine grains 3.7 μm size and narrow surface solute depletion zones 11 μm in with, resulting in a post-SP T6 strength of 500 MPa, significantly higher than that of the HTSP superplasticity alloys tested at 525 degree C or above. Meanwhile, it was found that LTSP materials may be transferred into HTSP materials simply by adding a preloading at 300-400 degree C for a small amount of work. As for the endeavor in making HRSP materials, 2024Al/SiC, 6061Al/SiC and Al/Al 3 Ti systems processed by powder metallurgy or mechanical alloying methods are under investigation. The average sizes of the reinforcing SiC or A13Ti particles, as well as the grain size are all around 1 μm. The aluminium composites have exhibited HRSP at 525-620 degree C and 10 -2 -10 -1 s -l , with elongations varying from 150 to 350 %. This ultimate goal is to produce an alloy or composite exhibiting low temperature and high strain rate superplasticity (LT and HRSP). (author)
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Sen, S.; Kaukler, W. F.; Curreri, P. A.
1999-01-01
Solidification phenomenon which occur at the solid/liquid (s/I) interface play a major role in the determination of structure and hence the technologically important properties of a casting. However, metals being opaque, conclusions related to several important phenomenon such as boundary layer thickness, morphological evolution, and eutectic and cell spacing are deduced from quenching experiments and subsequent post solidification metallographic analysis. Consequently, limited information is obtained about the dynamics of the process. This paper will discuss the recent efforts at the Space Science Laboratory, NASA Marshall Space Flight Center, to view and quantify in-situ and in real time the dynamics of the solidification process and to measure interfacial undercooling. First, a high resolution x-ray transmission microscope (XTM) has been developed to monitor fundamental interfacial phenomena during directional solidification of metals and alloys. The XTM operates in the range of 10-100 KeV and through projection is capable of achieving magnification of up to 16OX. Secondly, an innovative collapsible furnace has been designed to quantify interfacial undercooling by measuring the temperature of a moving s/I interface in reference to a fixed s/l interface. This measurement technique is non-intrusive in nature and is based on the Seebeck principle. In this paper real time results obtained to characterize the dynamics of irregular eutectic spacing will be presented. As an example fiber to lamella or plate transition in the Al-Al2Au eutectic system will be discussed. Further, a resolution limit of 25 micron has permitted viewing in real time morphological instability and cellular growth in Al-Au and Al-Ag systems. Simultaneously, a systematic investigation has been carried out to measure interfacial undercooling for Pb-1 wt.% Sn at and near the marginal stability regime. In conjunction with the XTM observations this study attempts to validate existing relationships
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Czech Academy of Sciences Publication Activity Database
Bačík, P.; Cempírek, J.; Uher, P.; Novák, M.; Ozdín, D.; Filip, J.; Škoda, R.; Breiter, Karel; Klementová, Mariana; Ďuďa, R.; Groat, L. A.
2013-01-01
Roč. 98, 2/3 (2013), s. 485-492 ISSN 0003-004X Institutional support: RVO:67985831 ; RVO:68378271 Keywords : Oxy-schorl * tourmaline-supergroup minerals * new mineral * electron microanalysis * crystal-structure refinement * Přibyslavice * Zlatá Idka Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.059, year: 2013
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Corrosion of Continuous Fiber Reinforced Aluminum Metal Matrix Composites (CF-AMCs)
Tiwari, Shruti
The first objective of this research is to study the atmospheric corrosion behavior of continuous reinforced aluminum matrix composites (CF-AMCs). The materials used for this research were alumina (Al2O3) and nickel (Ni) coated carbon (C) fibers reinforced AMCs. The major focus is to identify the correlation between atmospheric parameters and the corrosion rates of CF-AMCs in the multitude of microclimates and environments in Hawai'i. The micro-structures of CF-AMCs were obtained to correlate the microstructures with their corrosion performances. Also electrochemical polarization experiments were conducted in the laboratory to explain the corrosion mechanism of CF-AMCs. In addition, CF-AMCs were exposed to seven different test sites for three exposure periods. The various climatic conditions like temperature (T), relative humidity (RH), rainfall (RF), time of wetness (TOW), chloride (Cl- ) and sulfate (SO42-) deposition rate, and pH were monitored for three exposure period. Likewise, mass losses of CF-AMCs at each test site for three exposure periods were determined. The microstructure of the CF-AMCS showed that Al/C/50f MMCs contained a Ni-rich phase in the matrix, indicating that the Ni coating on the C fiber dissolved in the matrix. The intermetallic phases obtained in Al-2wt% Cu/Al 2O3/50f-T6 MMC and Al-2wt%-T6 monolith were rich in Cu and Fe. The intermetallic phases obtained in Al 7075/Al2O3/50f-T6 MMC and Al 7075-T6 monolith also contained traces of Mg, Zn, Ni, and Si. Electrochemical polarization experiment indicated that the Al/Al 2O3/50f Al-2wt% Cu/Al2O3/50f-T6 and Al 7075/Al2O3/50f-T6 MMC showed similar corrosion trends as their respective monoliths pure Al, Al-2wt%-T6 and Al 7075-T6 in both aerated and deaerated condition. Al2O3 fiber, being an insulator, did not have a great effect on the polarization behavior of the composites. Al/C/50f MMCs corroded at a much faster rate as compared to pure Al monolith due to the galvanic effect between C and Al
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Berryman, Eleanor J.; Wunder, Bernd; Wirth, Richard; Rhede, Dieter; Schettler, Georg; Franz, Gerhard; Heinrich, Wilhelm
2015-03-01
Tourmaline was synthesized in the system MgO-Al2O3-B2O3-SiO2-KCl-NaCl-H2O from an oxide mixture and excess fluid at 500-700 °C and 0.2-4.0 GPa to investigate the effect of pressure, temperature, and fluid composition on the relative incorporation of Na and K in dravitic tourmaline. Incorporation of K at the X-site increases with pressure, temperature, and KCl concentration; a maximum of 0.71 K pfu (leaving 0.29 X-vacant sites pfu) was incorporated into K-dravite synthesized at 4.0 GPa, 700 °C from a 4.78 m KCl, Na-free fluid. In contrast, Na incorporation depends predominately on fluid composition, rather than pressure or temperature; dravite with the highest Na content of 1.00 Na pfu was synthesized at 0.4 GPa and 700 °C from a 3.87 m NaCl and 1.08 m KCl fluid. All synthesized crystals are zoned, and the dominant solid solution in the Na- and K-bearing system is between magnesio-foitite [□(Mg2Al)Al6Si6O18(BO3)3(OH)3OH] and dravite [NaMg3Al6Si6O18(BO3)3(OH)3(OH)], with the dravitic component increasing with the concentration of Na in the fluid. In the K-bearing, Na-free system, the dominant solid solution is between magnesio-foitite and K-dravite [KMg3Al6Si6O18(BO3)3(OH)3(OH)], with the K-dravitic component increasing with pressure, temperature, and the concentration of K in the fluid. The unit-cell volume of tourmaline increases with K incorporation from 1555.1(3) to 1588.1(2) Å3, reflecting the incorporation of the relatively large K+ ion. Comparison of our results to the compositional data for maruyamaite (K-dominant tourmaline) from the ultrahigh-pressure rocks of the Kokchetav Massif in Kazakhstan suggests that the latter was formed in a K-rich, Na-poor environment at ultrahigh-pressure conditions near the diamond-stability field.
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Nature and morphology of the joints of metal matrix composites to metals
International Nuclear Information System (INIS)
Pietrzak, K.
1997-01-01
Metal matrix composites (MMCs) reinforced with short ceramic fibres (e.g. carbon or Al 2 O 3 fibres) or with other metals (such as e.g., tungsten) show numerous advantages since their properties can be programmed by modifying appropriately their composition and technology. A point of considerable importance is the possibility of joining the composites with metals or their alloys. The major problem here is to choose the appropriate joining technique, such that ensures the formation of a high quality joint resistant to the service conditions, avoids the degradation of the composite microstructure, in particular of the interface layer between the matrix and the reinforcement, and still, is not expensive (1). The paper presents the results of experiments on joining the following composites: 6061Al-based materials containing 15 vol.% of δ-alumina fibres, CuCrl-based materials containing 20 vol.% of carbon fibres (C f ), CuZrl-based materials containing 20 vol.% of C f and Cu-based materials with 10 vol.% of dispersed tungsten powder. The CuCrI-C f and CuZrl-C f composites were joined with austenitic steel, the 6061Al-Al 2 O 3 composite - with the 6061Al alloy and the CuW composite - with copper of 99.99 % purity. The material pairs were chosen so as to take into account their possible application. Several different joining techniques were examined. This paper discusses the results obtained when using diffusion bonding, vacuum brazing and gluing. The morphology and the nature of the interface layer after bonding process between the matrix and the reinforcement and between the MMCs and metal were examined by analysing the distributions of the elements, by SEM and by X-ray techniques. The degree of the degradation of the MMCs structure was taken to be described by the coefficient of the relative content of the reinforcing material RCRM = X/B, where X is the percent content of the reinforcing phase in the composite after the joining process, and B is the percent content of
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PENGOLAHAN LINDI DENGAN OZON DAN PROSES OKSIDASI LANJUT BERBASIS OZON
Directory of Open Access Journals (Sweden)
Mohamad Rangga Sururi
2014-05-01
Full Text Available Limbah industri tekstil di area pinggir kota Surabaya mempunyai karakteristik perbandingan COD dan BOD = 5.57. Limbah jenis ini sulit untuk dibiodegradasi. Studi ini mempelajari tekonologi elektrokoagulasi untuk mengolah limbah tekstil dengan menurunkan intensitas warna, Total Suspended Solid (TSS dan Chemical Oxygen Demand (COD. Percobaan batch pada suhu kamar dilakukan untuk mempelajari pengaruh pH, jarak elektroda terhadap penurunan warna,TSS dan COD dan membandingkan biaya operasinya jika menggunakan pengolahan kimia.Effisiensi penurunan tertinggi untuk warna (91.96%, TSS (49.17%, dan COD (29.67% terjadi pada pH awal 4.0 dan jarak elektroda 2 cm dengan elektroda Al/Al. Waktu optimum penurunan intensitas warna dalah 10 menit. Laju penurunan COD adalah : -dC/dt = 0.0053 C +0.056 , dengan C adalah konsentrasi COD. Jumlah sludge yang dihasilkan daripengolahan elektrokoagulasi 3.4 % lebih kecil dibandingkan menggunakan bahan kimia. Biaya yang digunakan untuk pengolahan dengan elektrokoagulasi 52.35 % lebih murah dibandingkan jika menggunakan koagulasi dengan bahan kimia ( tawas. Kata kunci : elektrokoagulasi, penurunan warna, penurunan TSS, laju degradasi COD, imbah tekstil Abstract Waste water from textile industry which is located in one suburb of Surabaya city as characteristic which the ratio of COD to BOD was 5.57. This type of waste water is difficult to be biodegraded. This study investigated elektrokoagulasi technology to treat textile waste water by removing color, total suspended solid, and Chemical Oxygen Demand. Batch experiment at room temperature was carried out to study the effect of pH, electrode distance for color, TSS and COD removal. This study also tried to compare the operation cost between elektrokoagulasi and chemical processes. The best removal efficiencies by Al electrodes was 91.96 % for color, 49.17 % for TSS and 29.67 % for COD which were under initial pH 4.0 and electrodes distance 2 cm. The optimum operation
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PENGOLAHAN PRIMER LIMBAH TEKSTIL DENGAN ELEKTROKOAGULASI
Directory of Open Access Journals (Sweden)
Lieke Riadi
2014-12-01
Full Text Available Limbah industri tekstil di area pinggir kota Surabaya mempunyai karakteristik perbandingan COD dan BOD = 5.57. Limbah jenis ini sulit untuk dibiodegradasi. Studi ini mempelajari tekonologi elektrokoagulasi untuk mengolah limbah tekstil dengan menurunkan intensitas warna, Total Suspended Solid (TSS dan Chemical Oxygen Demand (COD. Percobaan batch pada suhu kamar dilakukan untuk mempelajari pengaruh pH, jarak elektroda terhadap penurunan warna,TSS dan COD dan membandingkan biaya operasinya jika menggunakan pengolahan kimia.Effisiensi penurunan tertinggi untuk warna (91.96%, TSS (49.17%, dan COD (29.67% terjadi pada pH awal 4.0 dan jarak elektroda 2 cm dengan elektroda Al/Al. Waktu optimum penurunan intensitas warna dalah 10 menit. Laju penurunan COD adalah : -dC/dt = 0.0053 C +0.056 , dengan C adalah konsentrasi COD. Jumlah sludge yang dihasilkan daripengolahan elektrokoagulasi 3.4 % lebih kecil dibandingkan menggunakan bahan kimia. Biaya yang digunakan untuk pengolahan dengan elektrokoagulasi 52.35 % lebih murah dibandingkan jika menggunakan koagulasi dengan bahan kimia ( tawas. Kata kunci : elektrokoagulasi, penurunan warna, penurunan TSS, laju degradasi COD, imbah tekstil Abstract Waste water from textile industry which is located in one suburb of Surabaya city as characteristic which the ratio of COD to BOD was 5.57. This type of waste water is difficult to be biodegraded. This study investigated elektrokoagulasi technology to treat textile waste water by removing color, total suspended solid, and Chemical Oxygen Demand. Batch experiment at room temperature was carried out to study the effect of pH, electrode distance for color, TSS and COD removal. This study also tried to compare the operation cost between elektrokoagulasi and chemical processes. The best removal efficiencies by Al electrodes was 91.96 % for color, 49.17 % for TSS and 29.67 % for COD which were under initial pH 4.0 and electrodes distance 2 cm. The optimum operation
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Sol-gel/drop-coated micro-thick TiO{sub 2} memristors for γ-ray sensing
Energy Technology Data Exchange (ETDEWEB)
Abunahla, Heba [Department of Electrical and Computer Engineering, Khalifa University of Science, Technology and Research, Abu Dhabi (United Arab Emirates); Jaoude, Maguy Abi, E-mail: maguy.abijaoude@kustar.ac.ae [Department of Applied Mathematics and Sciences, Khalifa University of Science, Technology and Research, Abu Dhabi (United Arab Emirates); O' Kelly, Curtis J.; Mohammad, Baker [Department of Electrical and Computer Engineering, Khalifa University of Science, Technology and Research, Abu Dhabi (United Arab Emirates)
2016-12-01
Sol-gel/drop-coated micro-thick TiO{sub 2} memristors were investigated and developed for low-power radiation sensing. Devices constructed with coated aluminum (Al) electrodes exhibited unipolar I-V characteristics with dynamic turn-on voltage, and progressive R{sub OFF}/R{sub ON} ratio loss under applied bias. Endurance failure of micro-thick Al/Al stacks is ascribed to gradual passivation of Al surface resulting from an electrically-enhanced oxygen-ion diffusion. By exchanging a single Al contact with higher work function copper (Cu) metal, two distinct superimposed TiO{sub 2} phases were formed. The TiO{sub 2} coating on Al surface was carbon-contaminated and amorphous, while that on Cu was found to be additionally doped with Cu{sup (I/II)} ions resulting from the corrosion of the surface of the electrode by the amine-based gelation agent. After initial forming, the hybrid stack could achieve a bipolar memristance, with high R{sub OFF}/R{sub ON} (up to 10{sup 6}), and over 10 switching cycles at low-operating voltages (±1 V). The enhanced memristive switching properties of Al/Cu devices are explained via cooperative valence-change/electrochemical-metallization processes, involving migration of oxygen and copper species. The advanced micro-thick TiO{sub 2} memristors were exposed to Cs-137 γ-rays, providing for the first time initial insights into their radiation detection capabilities. The sensing mechanism through these devices could be actuated by synergistic radiation-induced and field-driven photo-electric effects. - Highlights: • Micro-thick TiO{sub 2} memristors with Al or Cu electrodes are advanced via sol-gel drop-coating. • Memristive switching in Al/TiO{sub 2}/Al structure is not viable due to resistance build-up. • Drop-coated Cu electrode gets corroded by ethanolamine additive, introducing Cu{sup (I/II)} cations into bulk TiO{sub 2}. • Bipolar memristance in Al/TiO{sub 2}/Cu{sup (I/II)} doped-TiO{sub 2}/Cu structure is depicted for the
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Haimbodi, Moses Warotua
CuInSe2 films and related alloys have been used to fabricate the highest efficiency thin film solar cells. Alloying CuInSe2 with CuAlSe2 provides a way to engineer the band gap of the resulting films from 1 to 2.7 eV, thereby providing a pathway for improving device performance. In this work, thin films of CuIn1-xAlxSe 2 obtained by multi-source PVD were characterized and investigated for their potential use as high band gap solar cells. The band gap of the films was varied by controlling the [Al]/[Al + In] ratio. Deposition of these films with varying [Cu]/[Al + In] ratios and thickness (1--4 mum) was carried out at substrate temperatures from 350--530°C. CuIn1-xAlxSe2 based solar cells have been fabricated using the structure glass/Mo/CuIn1-xAl xSe2/CdS/ZnO/grid. The effect of varying the band gap on device performance will be discussed. The highest efficiency obtained in this work is 11% using a film with Eg ≈ 1.3 eV. For high Al content, x > 0.3, device-performance decreases mainly due to poor FF similar to that observed in CuIn1-xGaxSe2 devices and is attributed to poor minority carrier collection. For CuIn1-xAlxSe2 films with x = 1, data is analyzed and presented with respect to [Cu]/[Al] and Se to total metal flux ratio, RSe/RM. Phase analysis shows that the resulting films contain different phases that depend on these parameters. Several of these films also contain concentrations of oxygen varying from 12 to 60 at. % as the [Cu]/[Al] ratio decreases. For RSe/R M > 10, a new structure we label as CuxAlySe z was observed. The oxygen content in all of the films obtained under RSe/RM > 10 vary between 1--3 at. %. Based on the Cu-Se, Al-Se, Cu-Al binary and the Cu2Se-Al2Se 3 pseudo-binary phase diagrams, a phenomenological film growth model is presented showing that the film growth kinetics are controlled by the delivery of Se.
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Fudger, Sean James
Macro hybridized systems consisting of steel encapsulated light metal matrix composites (MMCs) were produced with the goal of creating a low cost/light weight composite system with enhanced mechanical properties. MMCs are frequently incorporated into advanced material systems due to their tailorable material properties. However, they often have insufficient ductility for many structural applications. The macro hybridized systems take advantage of the high strength, modulus, and damage tolerance of steels and high specific stiffness and low density of MMCs while mitigating the high density of steels and the poor ductility of MMCs. Furthermore, a coefficient of thermal expansion (CTE) mismatch induced residual compressive stress method is utilized as a means of improving the ductility of the MMCs and overall efficiency of the macro hybridized systems. Systems consisting of an A36, 304 stainless steel, or NitronicRTM 50 stainless steel shell filled with an Al-SiC, Al-Al2O3, or Mg-B4C MMC are evaluated in this work. Upon cooling from processing temperatures, residual strains are generated due to a CTE mismatch between each of the phases. The resulting systems offer higher specific properties and a more structurally efficient system can be attained. Mechanical testing was performed and improvements in yield stress, ultimate tensile stress, and ductility were observed. However, the combination of these dissimilar materials often results in the formation of intermetallic compounds. In certain loading situations, these typically brittle intermetallic layers can result in degraded performance. X-ray Diffraction (XRD), X-ray Energy Dispersive Spectroscopy (EDS), and Electron Backscatter Diffraction (EBSD) are utilized to characterize the intermetallic layer formation at the interface between the steel and MMC. As the residual stress condition in each phase has a large impact on the mechanical property improvement, accurate quantification of these strains/stresses is
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Energy Technology Data Exchange (ETDEWEB)
Jacobs, Yasemin Erika Charlotte
2007-02-23
In this work the electronic structures, densities of states, chemical bonding, magnetic exchange Parameters and Curie temperatures of binary and ternary ferromagnetic alloys are analyzed. The electronic structure of ferromagnetic MnAl has been calculated using density-functional techniques (TB-LMTO-ASA, FPLAPW) and quantum chemically analyzed by means of the crystal orbital Hamilton population analysis. The crystal structure of the ferromagnetic tetragonal MnAl may be understood to originate from the structure of nonmagnetic cubic MnAl with a CsCl motif through a two-step process. While the nonmagnetic cubic structure is stable against a structural deformation, antibonding Mn-Mn interactions at the Fermi level lead to spin polarization and the onset of magnetism, i.e., a symmetry reduction taking place solely in the electronic degrees of freedom, by that emptying antibonding Mn-Mn states. Residual antibonding Al--Al states can only be removed by a subsequent, energetically smaller structural deformation towards the tetragonal system. As a final result, homonuclear bonding is strengthened and heteronuclear bonding is weakened. Corresponding DFT calculations of the electronic structure as well as the calculation of the chemical bonding and the magnetic exchange interactions have been performed on the basis of LDA and GGA for a series of ferromagnetic full Heusler alloys of general formula Co2MnZ (Z=Ga,Si,Ge,Sn), Rh2MnZ (Z=Ge,Sn,Pb), Ni2MnZ (Z=Ga,In,Sn), Pd2MnZ (Z=Sn,Sb) and Cu2MnZ (Z=Al,In,Sn). The connection between the electronic spectra and the magnetic interactions have been studied. Correlations between the chemical bondings in Heusler alloys derived from COHP analysis and magnetic phenomena are obvious, and different mechanisms leading to spin polarization and ferromagnetism are derived. The band dependence of the exchange parameters, their dependence on volume and valence electron concentration have been thoroughly analyzed within the Green function technique
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Nozzle erosion characterization and minimization for high-pressure rocket motor applications
Evans, Brian
correlation also incorporates the RMS data, accounting for swirling flow of the products in the RMS combustor. These correlations are useful for rocket nozzle designs. The correlation for non-metallized propellant and RMS firings was developed in terms of the effective oxidizer mass fraction and effective Reynolds number. The results calculated from this correlation were compared with measured erosion rate data within +/-15% or 0.05 mm/s (2 mils/s). For metallized propellant, the nozzle erosion rate was found to be relatively independent of the concentration of oxidizing species due to the diffusion-controlled process and the partial surface coverage by the liquid Al/Al2O3 layer. The nozzle erosion rate was also found to be lower than those of non-metallized propellant cases. Agreement between predicted and measured erosion rates was found to be within +/-20% or 0.04 mm/s (2 mils/s).
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Calculation of the 13C NMR shieldings of the C0 2 complexes of aluminosilicates
Tossell, J. A.
1995-04-01
13C NMR shieldings have been calculated using the random-phase-approximation, localized-orbital local-origins version of ab initio coupled Hartree-Fuck perturbation theory for CO 2 and and for several complexes formed by the reaction of CO 2 with molecular models for aluminosilicate glasses, H 3TOT'H3 3-n, T,T' = Si,Al. Two isomeric forms of the CO 2-aluminosilicate complexes have been considered: (1) "CO 2-like" complexes, in which the CO 2 group is bound through carbon to a bridging oxygen and (2) "CO 3-like" complexes, in which two oxygens of a central CO 3 group form bridging bonds to the two TH 3 groups. The CO 2-like isomer of CO 2-H 3SiOSiH 3 is quite weakly bonded and its 13C isotropic NMR shielding is almost identical to that in free CO 2. As Si is progressively replaced by Al in the - H terminated aluminosilicate model, the CO 2-like isomers show increasing distortion from the free CO 2 geometry and their 13C NMR shieldings decrease uniformly. The calculated 13C shielding value for H 3AlO(CO 2)AlH 3-2 is only about 6 ppm larger than that calculated for point charge stabilized CO 3-2. However, for a geometry of H 3SiO(CO 2) AlH 3-1, in which the bridging oxygen to C bond length has been artificially increased to that found in the - OH terminated cluster (OH) 3SiO(CO 2)Al(OH) 3-1, the calculated 13C shielding is almost identical to that for free CO 2. The CO 3-like isomers of the CO 2-aluminosili-cate complexes show carbonate like geometries and 13C NMR shieldings about 4-9 ppm larger than those of carbonate for all T,T' pairs. For the Si,Si tetrahedral atom pair the CO 2-like isomer is more stable energetically, while for the Si,Al and Al,Al cases the CO 3-like isomer is more stable. Addition of Na + ions to the CO 3-2 or H 3AlO(CO 2)AlH 3-2 complexes reduces the 13C NMR shieldings by about 10 ppm. Complexation with either Na + or CO 2 also reduces the 29Si NMR shieldings of the aluminosilicate models, while the changes in 27Al shielding with Na + or CO 2
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Brivio, Davide; Sajo, Erno; Zygmanski, Piotr
2017-12-01
We developed a method for measuring signal enhancement produced by high-Z nanofilm electrodes in parallel plate ionization chambers with variable thickness microgaps. We used a laboratory-made variable gap parallel plate ionization chamber with nanofilm electrodes made of aluminum-aluminum (Al-Al) and aluminum-tantalum (Al-Ta). The electrodes were evaporated on 1 mm thick glass substrates. The interelectrode air gap was varied from 3 μm to 1 cm. The gap size was measured using a digital micrometer and it was confirmed by capacitance measurements. The electric field in the chamber was kept between 0.1 kV/cm and 1 kV/cm for all the gap sizes by applying appropriate compensating voltages. The chamber was exposed to 120 kVp X-rays. The current was measured using a commercial data acquisition system with temporal resolution of 600 Hz. In addition, radiation transport simulations were carried out to characterize the dose, D(x), high-energy electron current, J(x), and deposited charge, Q(x), as a function of distance, x, from the electrodes. A deterministic method was selected over Monte Carlo due to its ability to produce results with 10 nm spatial resolution without stochastic uncertainties. Experimental signal enhancement ratio, SER(G) which we defined as the ratio of signal for Al-air-Ta to signal for Al-air-Al for each gap size, was compared to computations. The individual contributions of dose, electron current, and charge deposition to the signal enhancement were determined. Experimental signals matched computed data for all gap sizes after accounting for several contributions to the signal: (a) charge carrier generated via ionization due to the energy deposited in the air gap, D(x); (b) high-energy electron current, J(x), leaking from high-Z electrode (Ta) toward low-Z electrode (Al); (c) deposited charge in the air gap, Q(x); and (d) the decreased collection efficiency for large gaps (>~500 μm). Q(x) accounts for the electrons below 100 eV, which are
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Computational study of pristine and titanium-doped sodium alanates for hydrogen storage applications
Dathar, Gopi Krishna Phani
formalism as implemented in CASTEP (Cambridge Serial Total Energy Package) is used to study the structure and energetics of pristine and Ti-doped sodium alanates. From investigations of various models of sodium alanates with Ti dopants, it is shown that the difference between the energy required for Ti→SNa (Ti-substituted Na at the lattice site on the surface) and Ti→TI (Ti placed on top of the surface interstitial SI site) is 0.003 eV atom-1, and is minimal compared to other models. Since less energy is required for Ti→S Na and Ti→TI, these two sites (SNa and T I) would be preferred by the Ti dopants. In Ti→SNa model, Ti is coordinated to two aluminum and seven hydrogen atoms resulting in the possible formation of a TiAl2H7 complex. At elevated temperatures (423 and 448 K), the number of aluminum atoms coordinating with titanium in the complex increase from two (at distances in the 2.6-2.7 A range) to five (at distances in the 2.6-2.7 A range). Besides the formation of a Ti-Al-H complex, Al-Al association (with a 2.97 A bond length) is also seen from the DFT-MD results. In the case of Ti→TI, Ti is coordinated to two aluminum and two hydrogen atoms resulting in the possible formation of a TiAl2H2 complex. TiAl2 H2 complex becomes TiAl3H6 and TiAl 3H7 at elevated temperatures of 423 and 448 K, respectively. The investigation of thermodynamics pathways in Ti-doped sodium alanates illustrates a three step reaction pathway to the formation of TiAl3 (Ti and AlH3 after the first reaction, TiAl after the second and finally TiAl3). This investigation also suggests aluminum in its +3 oxidation state present in aluminum hydride species is responsible in the formation of Ti-Al alloys. From kinetics studies, the proposed mechanism is related to transition from AlH4- to AlH6 3-. The rate limiting step is determined to be associated with hydrogen evolution from association of AlH3 species nucleating aluminum phase. This step is 15 kJ/mol higher than the nearest highest
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Directory of Open Access Journals (Sweden)
Maria Mandri
2015-06-01
Full Text Available Teesid: Artikkel keskendub A. H. Tammsaare „Tõe ja õiguse“ pentaloogia I osas leiduvale murdelisele tegelaskõnele. Murdeline tegelaskõne on ilukirjanduslik võte, mis lähtub autori loomingulistest taotlustest ning on seega lahutamatu teose sisust. Keele- ja kirjandusteadust ühendades pakub artikkel seni puudu nud kontekstisidusa käsitluse „Tõe ja õiguse“ I osa tegelaskõnes kasutatud murdepärasuste omadustest ning funktsioonist teose sisu ja kompositsiooni toetamisel. Murdeline tegelaskõne osutab geograafiliselt kesk- ja läänemurde alale, iseloomustab tegelasi kui talurahva hulka kuulujaid, taotleb külaühiskonna realistlikku esitlust, toetab keeleliselt Vargamäe Ees- ja Tagapere ning vanade ja noorte vastandust. SU M M A R Y The use of language in Part I of A. H. Tammsaare’s five-volume novel Truth and Justice (Tõde ja Õigus has received quite a bit of scholarly attention. However, up till now there have been few treatments of dialect in characters’ speech that also take into account the coherence of context and the writer’s aesthetic goals. Features of dialect in characters’ speech have been noticed by many researchers, but they mostly limited themselves to giving descriptive accounts of dialect words. These earlier accounts often approached these passages as authentic specimens of dialect, and did not interpret them in context or as aspects of literary form. This article is based on the literary dialect theory of linguist and literary scholar Sumner Ives, who argues from the principle that dialect phenomena in literature cannot be studied as authentic specimens of dialect. In literature, when characters speak in dialect, this serves goals related to the content and composition of the work, and does not attempt to be a precise representation of real dialect speech. In this spirit, I will examine dialect in the characters’ speech in the first volume of Tammsaare’s cycle of novels Truth and Justice