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Sample records for thin slab cast

  1. Mold flux characterization for thin slab casting of steel

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Ramirez, A.; Vargas-Ramirez, M.; Hernandez-Perez, M. A.; Palacios-Beas, E.; Chavez-Alcala, J. E.

    2012-11-01

    The mineralogical constitution and the melting-solidification behavior of two commercial fluxes for thin slab casting of steel were determined. The characterization of the commercial fluxes as received show the presence of wollastonite (CaO . SiO{sub 2}), a sodium carbonate (Na{sub 2}CO{sub 3}), calcite (CaCO{sub 3}), fluorite (CaF{sub 2}) and carbon as the main components by X ray powder diffraction (XRD) and microscopic techniques. When fluxes were heated to 1573 K and further solidification, there was almost a whole transformation from the original compounds to cuspidine (3CaO. 2SiO{sub 2}.CaF{sub 2}) and nepheline (Na{sub 2}O . Al{sub 2}O{sub 3}. 2SiO{sub 2}) phases. The thermal gravimetrical analysis showed an important weight reduction in both fluxes due to the thermal decompositions of calcite and sodium carbonate. The characterization reveals that fluxes are produced by an agglomeration process. (Author) 15 refs.

  2. Analysis of segregation solute redistribution and centerline in continuously cast thin slab

    Directory of Open Access Journals (Sweden)

    Changwen MA

    2004-11-01

    Full Text Available A model has been built to calculate the solute redistribution in continuously cast thin slab and the effect of the fluid flow in mush on the centerline segregation was analyzed. The corresponding simulation program was developed by applying the SIMPLER algorithm. The momentum, energy and species conservation equations were solved simultaneously. The macro-segregation of a 3-D thin slab with 900 mm x 50 mm cross section was simulated. The obtained results show that negative segregation forms near the slab surface and severe centerline segregation forms in the mid-thickness plane. The species concentration in the centerline of the slab increases obviously at the final solidification stage.

  3. Mold flux characterization for thin slab casting of steel

    Directory of Open Access Journals (Sweden)

    Cruz-Ramírez, A.

    2012-08-01

    Full Text Available The mineralogical constitution and the melting-solidification behavior of two commercial fluxes for thin slab casting of steel were determined. The characterization of the commercial fluxes as received show the presence of wollastonite (CaO. SiO2, a sodium carbonate (Na2CO3, calcite (CaCO3, fluorite (CaF2 and carbon as the main components by X ray powder diffraction (XRD and microscopic techniques. When fluxes were heated to 1573 K and further solidification, there was almost a whole transformation from the original compounds to cuspidine (3CaO - 2SiO2 - CaF2 and nepheline (Na2O - Al2O3 - 2SiO2 phases. The thermal gravimetrical analysis showed an important weight reduction in both fluxes due to the thermal decompositions of calcite and sodium carbonate. The characterization reveals that fluxes are produced by an agglomeration process.

    Se determinó la composición mineralógica y el comportamiento de fusión-solidificación de dos fundentes comerciales para la colada de planchón delgado de acero. La caracterización de los fundentes comerciales por difracción de rayos X (XRD y técnicas de microscopía muestra la presencia de wollastonita (CaO - SiO2, un carbonato de sodio (Na2CO3, calcita (CaCO3, fluorita (CaF2 y carbono como los principales componentes. Cuando los fundentes se calentaron a 1.573 K y después de la solidificación, hubo una transformación casi total de los compuestos originales a las fases cuspidina (3CaO - 2SiO2 - CaF2 y nefelina (Na2O - Al2O3 - 2SiO2. El análisis termogravimétrico muestra una importante reducción de peso en los fundentes debido a la descomposición térmica de la calcita y el carbonato de sodio. La caracterización indica que los fundentes son producidos por

  4. Modeling of the flow-solidification interaction in thin slab casting

    Science.gov (United States)

    Vakhrushev, A.; Wu, M.; Ludwig, A.; Tang, Y.; Hackl, G.; Nitzl, G.

    2012-07-01

    A key issue for modelling the thin slab casting (TSC) is to consider the evolution of the solid shell, which strongly interacts with the turbulent flow and in the meantime is subject to continuous deformation due to the funnel shape (curvature) of the mould. Here an enthalpy-based mixture solidification model with consideration of turbulent flow [Prescott and Incropera, ASME HTD, vol. 280, 1994, pp. 59] is employed, and further enhanced to include the deforming solid shell. The solid velocity in the fully-solidified strand shell and partially-solidified mushy zone is estimated by solving the Laplace's equation. Primary goals of this work are to examine the sensitivity of the modelling result to different model implementation schemes, and to explore the importance of the deforming and moving solid shell in the solidification. Therefore, a 2D benchmark, to mimic the solidification and deformation behaviour of the thin slab casting, is firstly simulated and evaluated. An example of 3D TSC is also presented. Due to the limitation of the current computation resources additional numerical techniques like parallel computing and mesh adaptation are necessarily applied to ensure the calculation accuracy for the full-3D TSC.

  5. Numerical Investigation of Shell Formation in Thin Slab Casting of Funnel-Type Mold

    Science.gov (United States)

    Vakhrushev, A.; Wu, M.; Ludwig, A.; Tang, Y.; Hackl, G.; Nitzl, G.

    2014-06-01

    The key issue for modeling thin slab casting (TSC) process is to consider the evolution of the solid shell including fully solidified strand and partially solidified dendritic mushy zone, which strongly interacts with the turbulent flow and in the meantime is subject to continuous deformation due to the funnel-type mold. Here an enthalpy-based mixture solidification model that considers turbulent flow [Prescott and Incropera, ASME HTD, 1994, vol. 280, pp. 59-69] is employed and further enhanced by including the motion of the solidifying and deforming solid shell. The motion of the solid phase is calculated with an incompressible rigid viscoplastic model on the basis of an assumed moving boundary velocity condition. In the first part, a 2D benchmark is simulated to mimic the solidification and motion of the solid shell. The importance of numerical treatment of the advection of latent heat in the deforming solid shell (mushy zone) is specially addressed, and some interesting phenomena of interaction between the turbulent flow and the growing mushy zone are presented. In the second part, an example of 3D TSC is presented to demonstrate the model suitability. Finally, techniques for the improvement of calculation accuracy and computation efficiency as well as experimental evaluations are also discussed.

  6. The Influence of Vanadium Microalloying on the Production of Thin Slab Casting and Direct Rolled Steel Strip

    Science.gov (United States)

    Li, Yu; Milbourn, David

    Vanadium microalloying is highly effective in high strength strip steels produced by thin slab casting and direct rolled process. Because of the high solubility of V(C,N) in austenite, vanadium is likely to remain in solution during casting, equalisation and rolling. Vanadium microalloyed steels have better hot ductility and are less prone to transverse cracking than niobium containing steels. Despite a coarse as-cast austenite grain size before rolling, significant grain refinement can be achieved in vanadium microalloyed steels by repeated recrystallization during rolling, resulting in a fine uniform ferrite microstructure in final strip. Almost all vanadium present in microalloyed steels is available to precipitate in ferrite as very fine particles, contributing to precipitation strengthening. Vanadium microalloyed steels show less sensitivity to rolling process variables and exhibit excellent combination of strength and toughness.

  7. Thin-slab casting–New possibilities

    Indian Academy of Sciences (India)

    Additionally, what started as a step for reducing investment in hot rolling has, in fact, given new opportunity for direct hot rolling of thickness that were, for long, ... A techno-economic analysis of thin-slab casting has been presented along with the benefits that arise when a thin-slab caster is linked to the blast furnace and ...

  8. Thermo-mechanical properties and cracking during solidification of thin slab cast steel

    NARCIS (Netherlands)

    Santillana, M.B.

    2013-01-01

    Nowadays a vast majority of the steel produced worldwide is via the continuous casting process route because this is the most low-cost, efficient and high quality method to mass produce metal products in a variety of sizes and shapes. Most of the continuous casters are the initial manufacturing step

  9. Photon transport in thin disordered slabs

    Indian Academy of Sciences (India)

    We examine using Monte Carlo simulations, photon transport in optically `thin' slabs whose thickness is only a few times the transport mean free path *, with particles of different scattering anisotropies. The confined geometry causes an auto-selection of only photons with looping paths to remain within the slab.

  10. Photon transport in thin disordered slabs

    Indian Academy of Sciences (India)

    This approximation of an incoherent energy transport is valid in the weak scattering limit ( Р*. ^ 1, where = 2. ). In this paper, we describe the results of our Monte Carlo simulations to study photon transport in thin slabs. We show that in small slabs, photons that traverse large paths are forced by the constrained geometry to ...

  11. Industrial online surface defects detection in continuous casting hot slabs

    Science.gov (United States)

    Alvarez, Ignacio; Marina, Jorge; Enguita, Jose Maria; Fraga, Cesar; Garcia, Ricardo

    2009-06-01

    Early surface defects inspection in hot steel products is a difficult task, but can help to reduce significantly production costs. This is the case of steel slabs when they are produced in the continuous casting line. Conoscopic holography phase-based long stand-off profilometers have shown to be a great tool for this kind of inspection, and a breakthrough system based on them is being used for more than 2 years in production conditions with high reliability and economical impact. This paper presents the results of this system and the challenges it has overcome: hot material up to 900°C, dust, scale over the inspected surface.

  12. Computer Modeling of DC Casting Magnesium Alloy WE43 Rolling Slabs

    Science.gov (United States)

    Turski, M.; Grandfield, J. F.; Wilks, T.; Davis, B.; DeLorme, R.; Cho, K.

    During direct chill (DC) casting, significant stresses can develop within the material leading to cracking within the cast slab. The situation is made worse for higher strength magnesium alloys, such as Elektron™ WE43, which exhibits high strength at elevated temperatures. Consequently, the temperature and stress field must be well understood during the casting process to avoid failure during casting.

  13. Software Analytical Instrument for Assessment of the Process of Casting Slabs

    International Nuclear Information System (INIS)

    Franek, Zdenek; Kavicka, Frantisek; Stetina, Josef; Masarik, Milos

    2010-01-01

    The paper describes the original proposal of ways of solution and function of the program equipment for assessment of the process of casting slabs. The program system LITIOS was developed and implemented in EVRAZ Vitkovice Steel Ostrava on the equipment of continuous casting of steel (further only ECC). This program system works on the data warehouse of technological parameters of casting and quality parameters of slabs. It enables an ECC technologist to analyze the course of casting melt and with using statistics methods to set the influence of single technological parameters on the duality of final slabs. The system also enables long term monitoring and optimization of the production.

  14. Root Cause Analysis of Surface Defects in Coils Produced through Thin Slab Route

    Science.gov (United States)

    Bhattacharya, Diptak; Misra, Siddhartha; Kumar, Avinash; Mahashabde, Vinay V.

    A metallurgical analysis of longitudinal cracks in a medium carbon grade of steel, produced through Thin Slab Casting and Rolling (TSCR) process is presented in this paper. Using characterization techniques, it was established that the defect originated from the funnel mold of thin slab caster. Temperature profiles of thermocouples in caster mold were employed to evaluate the heat transfer characteristics during primary solidification. The profiles helped to assess the performance of a standard mold flux used for casting this grade and hypothesize a possible mechanism of defect evolution. Slightly changed characteristics of the mold flux addressed the defect by promoting a stable and uniform heat transfer. This drastically lowered defect occurrence and rejections due to longitudinal cracks in this grade.

  15. Experimental research of slab cast over precast joists with prestressed reinforcement

    Directory of Open Access Journals (Sweden)

    Koyankin Aleksandr Aleksandrovich

    2016-03-01

    Full Text Available At the present time reinforced concrete is the main construction material in civil and industrial construction. Cast-in-place and precast construction is gradually becoming a more widespread type of house-building, but still there is a lack of data, including experimental data, which allows evaluating the stress and strain state of a construction of a slab cast over precast joists. Experimental research of stress and strain state of slab cast over precast joists with prestressed reinforcement was carried out. An experimental model of a fragment of a hybrid precast/cast-in-place building was produced and tested (reduction scale 1:6. The experimental investigations of slab cast over precast joists with prestressed reinforcement proved that the construction solution of the framework offered in the previous works of the authors possess good stiffness, crack-resistance and bearing capacity. It well fits for constructing the slabs of long spans in residential and public buildings.

  16. Thin slab processing of acicular ferrite steels with high toughness

    Energy Technology Data Exchange (ETDEWEB)

    Reip, Carl-Peter; Hennig, Wolfgang; Hagmann, Rolf [SMS Demag Aktiengesellschaft, Duesseldorf (Germany); Sabrudin, Bin Mohamad Suren; Susanta, Ghosh; Weng Lan Lee [Megasteel Sdn Bhd, Banting (Malaysia)

    2005-07-01

    Near-net-shape casting processes today represent an important option in steelmaking. High productivity and low production cost as well as the variety of steel grades that can be produced plus an excellent product quality are key factors for the acceptance of such processes in markets all over the world. Today's research focuses on the production of pipe steel with special requirements in terms of toughness at low temperatures. The subject article describes the production of hot strip made from acicular ferritic / bainitic steel grades using the CSP thin-slab technology. In addition, the resulting strength and toughness levels as a function of the alloying concepts are discussed. Optimal control of the CSP process allows the production of higher-strength hot-rolled steel grades with a fine-grain acicular-ferritic/bainitic microstructure. Hot strip produced in this way is characterized by a high toughness at low temperatures. In a drop weight tear test, transition temperatures of up to -50 deg C can be achieved with a shear-fracture share of 85%. (author)

  17. Thin section casting program. Volume 2: Horizontal TSC (Thin-Section Casting) approach

    Science.gov (United States)

    1989-01-01

    In horizontal thin-section casting (HTSC), 1-inch-thick steel sections are produced at speeds up to 600 ipm or about 60 tons per hour per foot of width (tphf). Liquid steel is fed from the ladle, and flows through a specially designed tundish, then flows through a refractory feeding tube and nozzle, with approximately the same external dimensions as the cast section, into a near-horizontal rectangular mold whose all four sides are traveling in the same direction and speed as the steel casting. This report is the second of a six volume set on thin section casting. This volume covers the research on horizontal thin section casting (TSC).

  18. Photon transport in thin disordered slabs

    Indian Academy of Sciences (India)

    ... auto-selection of only photons with looping paths to remain within the slab. The results of the Monte Carlo simulations are borne out by our analytical treatment that incorporates directional persistence by the use of the Ornstein–Uhlenbeck process, which interpolates between the short time ballistic and long time diffusive ...

  19. Research on mechanical behavior of casting slab during dynamic soft reduction

    Science.gov (United States)

    Qin, Qin; Huang, Jianlin; Zhou, Daomou; Yang, Xiaoying

    2017-10-01

    A three-dimensional dynamic solidification model incorporating the thermo-elastic-plastic coupling model has been proposed in this paper by ABAQUS considering the dynamic contact between the slab and rolls. The thermo-mechanical coupling model produces outputs such as temperature and mechanical behavior of the slab. And the stress-strain distribution of the high-temperature slab at the solidification end has been investigated in this paper. The influences of various reduction interval, reduction amount and reduction distribution on mechanical behavior of casting slab have been systematically discussed.

  20. Thin wall ductile and austempered iron castings

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2010-07-01

    Full Text Available It has been shown that it is possible to produce thin wall castings made of ductile iron with wall thickness in the range of 1.2 to 2.9 mm(without chills, cold laps and misruns. Thin wall ductile iron castings can be lighter (380 g than their substitutes made of aluminium alloys (580g. The kinetics of austenitising transformation was studied in unalloyed ductile iron. The advance of transformations during austenitising was monitored by measurement the fraction of martensite and also by dilatometic studies. It has been shown that in thin wall ductile iron castings austenitising at 880 oC for 20 minutes is adequate to obtain the austenite matrix at the end of the first stage of austempering heat treatment cycle.

  1. Reasonable Temperature Schedules for Cold or Hot Charging of Continuously Cast Steel Slabs

    Science.gov (United States)

    Li, Yang; Chen, Xin; Liu, Ke; Wang, Jing; Wen, Jin; Zhang, Jiaquan

    2013-12-01

    Some continuously cast steel slabs are sensitive to transverse fracture problems during transportation or handling away from their storage state, while some steel slabs are sensitive to surface transverse cracks during the following rolling process in a certain hot charging temperature range. It is revealed that the investigated steel slabs with high fracture tendency under room cooling condition always contain pearlite transformation delayed elements, which lead to the internal brittle bainitic structure formation, while some microalloyed steels exhibit high surface crack susceptibility to hot charging temperatures due to carbonitride precipitation. According to the calculated internal cooling rates and CCT diagrams, the slabs with high fracture tendency during cold charging should be slowly cooled after cutting to length from hot strand or charged to the reheating furnace directly above their bainite formation temperatures. Based on a thermodynamic calculation for carbonitride precipitation in austenite, the sensitive hot charging temperature range of related steels was revealed for the determination of reasonable temperature schedules.

  2. Analysis of Meniscus Fluctuation in a Continuous Casting Slab Mold

    Science.gov (United States)

    Zhang, Kaitian; Liu, Jianhua; Cui, Heng; Xiao, Chao

    2018-03-01

    A water model of slab mold was established to analyze the microscopic and macroscopic fluctuation of meniscus. The fast Fourier transform and wavelet entropy were adopted to analyze the wave amplitude, frequency, and components of fluctuation. The flow patterns under the meniscus were measured by using particle image velocimetry measurement and then the mechanisms of meniscus fluctuation were discussed. The results reflected that wavelet entropy had multi-scale and statistical properties, and it was suitable for the study of meniscus fluctuation details both in time and frequency domain. The basic wave, frequency of which exceeding 1 Hz in the condition of no mold oscillation, was demonstrated in this work. In fact, three basic waves were found: long-wave with low frequency, middle-wave with middle frequency, and short-wave with high frequency. In addition, the upper roll flow in mold had significant effect on meniscus fluctuation. When the position of flow impinged was far from the meniscus, long-wave dominated the fluctuation and the stability of meniscus was enhanced. However, when the velocity of flow was increased, the short-wave dominated the meniscus fluctuation and the meniscus stability was decreased.

  3. A computational study of low-head direct chill slab casting of aluminum alloy AA2024

    Science.gov (United States)

    Hasan, Mainul; Begum, Latifa

    2016-04-01

    The steady state casting of an industrial-sized AA2024 slab has been modeled for a vertical low-head direct chill caster. The previously verified 3-D CFD code is used to investigate the solidification phenomena of the said long-range alloy by varying the pouring temperature, casting speed and the metal-mold contact heat transfer coefficient from 654 to 702 °C, 60-180 mm/min, and 1.0-4.0 kW/(m2 K), respectively. The important predicted results are presented and thoroughly discussed.

  4. Manufacturing of thin walled near net shape iron castings

    DEFF Research Database (Denmark)

    Larsen, Per Leif

    2003-01-01

    to be substituting iron casings with aluminum castings. Substituting iron castings with aluminum castings is not as easy as first believed, and hence the substitution is very slow. This combined with the lack of fully exploiting the potential in iron castings, makes research in iron castings interesting. The 60......The demand for near net shape thin walled iron castings is growing. This has several reasons, the main one is the need for lowering the fuel consumption of cars; the easiest way to do that is to lower the weight of the cars. The best way to do this was for a period of time believed.......000.000 cars produced world wide each year consumes enormous amounts of cast parts ! The aim of the project is to develop the green sand molding method on DISAMATIC to be able to deal with the new demands for thin walled near net shape castings in iron....

  5. Horizontal electromagnetic casting of thin metal sheets

    Science.gov (United States)

    Hull, John R.; Lari, Robert J.; Praeg, Walter F.; Turner, Larry R.

    1987-01-01

    Thin metal sheets are cast by magnetically suspending molten metal deposited within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled to form a solid metal sheet. Magnetic flux increases as the molten metal sheet moves downward and decreases as the molten metal sheet moves upward to stabilize the sheet and maintain it in equilibrium as it is linearly displaced and solidified by cooling gases. A conducting shield is electrically coupled to the molten metal sheet by means of either metal sheet engaging rollers or brushes on the solidified metal, and by means of an electrode in the vessel containing the molten metal thereby providing a return path for the eddy currents induced in the metal sheet by the AC coil generated magnetic flux. Variation in the geometry of the conducting shield allows the magnetic flux between the metal sheet and the conducting shield to be varied and the thickness in surface quality of the metal sheet to be controlled. Side guards provide lateral containment for the molten metal sheet and stabilize and shape the magnetic field while a leader sheet having electromagnetic characteristics similar to those of the metal sheet is used to start the casting process and precedes the molten metal sheet through the magnet and forms a continuous sheet therewith. The magnet may be either U-shaped with a single racetrack coil or may be rectangular with a pair of facing bedstead coils.

  6. Horizontal electromagnetic casting of thin metal sheets

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL); Lari, Robert J. (Aurora, IL); Praeg, Walter F. (Palos Park, IL); Turner, Larry R. (Naperville, IL)

    1988-01-01

    Thin metal sheets are cast by magnetically suspending molten metal deposited within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled to form a solid metal sheet. Magnetic flux increases as the molten metal sheet moves downward and decreases as the molten metal sheet moves upward to stabilize the sheet and maintain it in equilibrium as it is linearly displaced and solidified by cooling gases. A conducting shield is electrically coupled to the molten metal sheet by means of either metal sheet engaging rollers or brushes on the solidified metal, and by means of an electrode in the vessel containing the molten metal thereby providing a return path for the eddy currents induced in the metal sheet by the AC coil generated magnetic flux. Variation in the geometry of the conducting shield allows the magnetic flux between the metal sheet and the conducting shield to be varied and the thickness in surface quality of the metal sheet to be controlled. Side guards provide lateral containment for the molten metal sheet and stabilize and shape the magnetic field while a leader sheet having electromagnetic characteristics similar to those of the metal sheet is used to start the casting process and precedes the molten metal sheet through the magnet and forms a continuous sheet therewith. The magnet may be either U-shaped with a single racetrack coil or may be rectangular with a pair of facing bedstead coils.

  7. Undercooling and nodule count in thin walled ductile iron castings

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    Casting experiments have been performed with eutectic and hypereutectic castings with plate thick¬nesses from 2 to 8 mm involving both temperature measurements during solidification and micro¬structural examination afterwards. The nodule count was the same for the eutectic and hypereutectic...... castings in the thin plates ( 4.3 mm) while in the 8 mm plate the nodule count was higher in the hypereutectic than in the eutectic castings. The minimum temperature prior to the eutectic recalescence (Tmin) was 15 to 20C lower for the eutectic than the hypereutectic castings. This is due to nucleation...... of graphite nodules which begins at a lover temperature in the eutectic than in the hypereutectic castings The recalescence (Trec) was however also larger for the eutectic casting and in the thin plates the maximum temperature after recalescence (Tmax) was the same in the eutectic and hypereutectic plates...

  8. Undercooling and nodule count in thin walled ductile iron castings

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    Casting experiments have been performed with eutectic and hypereutectic castings with plate thicknesses from 2 to 8 mm involving both temperature measurements during solidification and microstructural examination afterwards. The nodule count was the same for the eutectic and hypereutectic castings...... in the thin plates (≤4.3 mm) while in the 8 mm plate the nodule count was higher in the hypereutectic than in the eutectic castings. The minimum temperature before the eutectic recalescence (Tmin) was 15 to 20ºC lower for the eutectic than for the hypereutectic castings. This is due to nucleation of graphite...... nodules which begins at a lower temperature in the eutectic than in the hypereutectic castings. The recalescence ∆Trec was however also larger for the eutectic casting and in the thin plates the maximum temperature after recalescence (Tmax) was the same in the eutectic and hypereutectic plates...

  9. Argon bubble behavior in slide-gate tundish nozzles during continuous casting of steel slabs

    Science.gov (United States)

    Bai, Hua

    2000-10-01

    Argon injection into a tundish nozzle is an efficient and widely employed method to reduce nozzle clogging in the continuous casting process. It also affects casting operation and product quality by changing the flow pattern in the nozzle and mold. The current work combines mathematical modeling and experiments to investigate the argon bubble behavior in slide-gate nozzles and to analyze phenomena related to product defects and operational problems during the continuous casting of steel slabs. Water model experiments are performed to study bubble formation behavior, including bubble size, frequency, mode and effects of variables such as liquid velocity, gas injection flow rate, gas injection hole size and gas density. An analytical model is developed to predict the average bubble size. Argon gas bubbles are predicted to be 1--5mm. This is larger than air bubbles in water, especially at low speed. A three-dimensional finite difference model is developed to study the turbulent flow of liquid steel and argon bubble in the slide-gate nozzles. Experiments are performed on a 0.4-scale "water caster" to verify the model by comparing the model prediction with the measurements using PIV (Particle Image Velocimetry) technology. A weighted average scheme for the overall outflow is developed to quantify jet characteristics such as jet angle, jet speed, back flow zone fraction, turbulence and biased mass flow. Swirl is generated at nozzle ports. The validated model is employed to perform extensive parametric studies to investigate the effects of casting operation conditions such as gas injection, slide-gate orientation, casting speed, gate opening and bubble size and nozzle port design including port angle and port shape. The interrelated effects of nozzle clogging, argon injection, tundish bath depth, slide gate opening and nozzle bore diameter on the flow rate and pressure in tundish nozzles are quantified using an inverse model, based on interpolation of the numerical

  10. High-Temperature Creep Behaviour and Positive Effect on Straightening Deformation of Q345c Continuous Casting Slab

    Science.gov (United States)

    Guo, Long; Zhang, Xingzhong

    2018-03-01

    Mechanical and creep properties of Q345c continuous casting slab subjected to uniaxial tensile tests at high temperature were considered in this paper. The minimum creep strain rate and creep rupture life equations whose parameters are calculated by inverse-estimation using the regression analysis were derived based on experimental data. The minimum creep strain rate under constant stress increases with the increase of the temperature from 1000 °C to 1200 °C. A new casting machine curve with the aim of fully using high-temperature creep behaviour is proposed in this paper. The basic arc segment is cancelled in the new curve so that length of the straightening area can be extended and time of creep behaviour can be increased significantly. For the new casting machine curve, the maximum straightening strain rate at the slab surface is less than the minimum creep strain rate. So slab straightening deformation based on the steel creep behaviour at high temperature can be carried out in the process of Q345c steel continuous casting. The effect of creep property at high temperature on slab straightening deformation is positive. It is helpful for the design of new casting machine and improvement of old casting machine.

  11. Analysis of Internal Cracks in Continuous Casting Slabs with Soft Reduction

    Science.gov (United States)

    Wang, Bo; Zhang, Jiongming; Xiao, Chao; Wang, Shunxi; Song, Wei

    2016-03-01

    The formation of internal cracks in continuous casting slabs is mainly attributed to the strain status and microsegregation near the solidifying front of the slabs. By analyzing the internal cracks of medium carbon microalloy steel, the obtained conclusions are that C, P, S, etc. enrich in dendrites and exist in grain boundaries, but these are just the internal causes, and the root cracking causes the tensile stress of solidification front. When the slab passes through the straightening segments, the liquid core thickness is large, and the liquid steel in the space of columnar crystals is not completely frozen. Therefore, the reduction effect of rollers results in the strain of solidification front exceeding the critical value. However, the corresponding strain in the arc and horizontal segments does not exceed this critical value, so the solidification front in the straightening segments would be much easy to crack. The statistics analysis shows that after soft reduction and straightening process are separately carried out, the occurrence rate of intermediate cracks is reduced by 41.3%.

  12. Prevention of halfway cracks in continuous cast A36 steel slabs containing boron

    Directory of Open Access Journals (Sweden)

    Jian-chao Ma

    2015-01-01

    Full Text Available The formation of halfway cracks in continuous cast A36 steel slabs containing 17 ppm boron was studied by investigating the zero ductility temperature (ZDT, zero strength temperature (ZST, solidification characteristics, and strain distribution in the steels. Results show that the formation of halfway cracks in A36-B slab is attributed to the increase in both the internal crack susceptibility (ZDT and ZST of the steel and the external tensile strain at the solidification front. The ZST of both steels with (A36-B and without (A36 boron addition is nearly the same, but the ZDT of A36-B steel is found 50 篊 lower due to a considerable increase of boron content at the final stage of solidification. The decrease of ZDT enlarges the solidification cracking susceptibility zone and results in the A36-B steel being more prone to cracking. In addition, during the unbending segments, a large tensile strain, resulting from the unbending process and the misalignment deviation of supporting rolls, occurs in the upper part of the solidified shell, which is another reason causing halfway cracks in A36-B slab. By decreasing the P and S content to be less than 50 ppm and 150 ppm, respectively, controlling B content in the range of 10 to 15 ppm, increasing the secondary cooling specific water ratio from 0.76 to 0.85 L穔g-1, and restricting roll alignment deviation to less than plus or minus 0.3 mm, halfway cracks in the boron containing slab are almost eliminated.

  13. Physical and Clinical Evaluation of Hip Spica Cast applied with Three-slab Technique using Fibreglass Material

    Directory of Open Access Journals (Sweden)

    Bitar KM

    2016-11-01

    Full Text Available Introduction: Hip spica casting is an important component of treatment for developmental dysplasia of the hip (DDH and popular treatment method for femur fractures in children. Breakage at the hip region is a relatively common problem of this cast. We have developed a three-slab technique of hip spica application using fibreglass as the cast material. The purpose of this review was to evaluate the physical durability of the spica cast and skin complications with its use. Methodology: A retrospective review of children with various conditions requiring hip spica immobilisation which was applied using our method. Study duration was from 1st of January 2014 until 31st December 2015. Our main outcomes were cast breakage and skin complications. For children with hip instability, the first cast would be changed after one month, and the second cast about two months later. Results: Twenty-one children were included, with an average age of 2.2 years. The most common indication for spica immobilisation was developmental dysplasia of the hip. One child had skin irritation after spica application. No spica breakage was noted. Conclusion: This study showed that the three-slab method of hip spica cast application using fibreglass material was durable and safe with low risk of skin complications.

  14. Physical and Clinical Evaluation of Hip Spica Cast applied with Three-slab Technique using Fibreglass Material.

    Science.gov (United States)

    Bitar, K M; Ferdhany, M E; Ashraf, E I; Saw, A

    2016-11-01

    Introduction: Hip spica casting is an important component of treatment for developmental dysplasia of the hip (DDH) and popular treatment method for femur fractures in children. Breakage at the hip region is a relatively common problem of this cast. We have developed a three-slab technique of hip spica application using fibreglass as the cast material. The purpose of this review was to evaluate the physical durability of the spica cast and skin complications with its use. Methodology: A retrospective review of children with various conditions requiring hip spica immobilisation which was applied using our method. Study duration was from 1st of January 2014 until 31st December 2015. Our main outcomes were cast breakage and skin complications. For children with hip instability, the first cast would be changed after one month, and the second cast about two months later. Results: Twenty-one children were included, with an average age of 2.2 years. The most common indication for spica immobilisation was developmental dysplasia of the hip. One child had skin irritation after spica application. No spica breakage was noted. Conclusion: This study showed that the three-slab method of hip spica cast application using fibreglass material was durable and safe with low risk of skin complications.

  15. Numerical simulation of flow and heat transfer of continous cast steel slab under traveling magnetic field

    Directory of Open Access Journals (Sweden)

    Gong Haijun

    2013-03-01

    Full Text Available A unified numerical model for simulating solidification transport phenomena (STP of steel slab in electromagnetic continuous casting (EMCC process was developed. In order to solve the multi-physics fields coupled problem conveniently, the complicated bidirectional coupled process between EM and STP was simplified as a unidirectional one, and a FEM/FVM-combined numerical simulation technique was adopted. The traveling magnetic fields (TMFs applied to the EMCC process were calculated using the ANSYS11.0 software, and then the EM-data output by ANSYS were converted to FVM-format using a data-format conversion program developed previously. Thereafter, the governing equations were solved using a pressure-based Direct-SIMPLE algorithm. The simulation results of the STP in CC-process show that, due to the influences of Lorentz force and Joule heat, the two strong circulating flows and the temperature field can be obviously damped and changed once TMF with one pair of poles (1-POPs or 2-POPs is applied, which would accordingly improve the quality of casting. It was found in the present research that the integrated actions of 2-POPs TMF are superior to 1-POPs. All the computations indicate that the present numerical model of EM-STP as well as the FEM/FVM-combined technique is successful.

  16. Transverse Crack Modeling of Continuously Casted Slabs through Finite Element Method in Roughing Rolling at Wide Strip Mill

    Science.gov (United States)

    Pesin, A.; Salganik, V.; Pustovoytov, D.

    2010-06-01

    In the pipe billet production at the wide strip mills of hot rolling big metal losses are caused by surface defects that affect most parts of the finished strips. The rolling surface defects are referred to the breach of steelmaking technology. Specialists mostly face defects of metal surface such as "scab" and "crack". The only area suffered from these defects is a slab edge. This area has the least surface temperature at the unbending of the continuous-casting machine, and together with deep buckles made by reciprocating motion of the crystallizer it is mostly subjected to transverse cracks that can be up to several millimeters. Each surface defect of the continuously casted slab will further turn into the surface defect of the strip bar. For some grade sets, mostly made of pipe steel grades the amount of strips with these defects can reach up to 60-70%. The area that is mostly prone to these defects is the edge of the strip. The work reveals investigation of the form change peculiarities in the transverse cracks of the continuously casted slab in roughing rolling in the horizontal rollers. The finite element method with software DEFORM 3D V6.1 has been applied in modeling. The work gives a form change mechanism of transverse cracks of slabs in deformation. Further crack growth in rolling is assessed due to Cockroft-Latham criteria.

  17. MR fetography using heavily T2-weighted sequences: comparison of thin- and thick-slab acquisitions.

    Science.gov (United States)

    Huisman, Thierry A G M; Solopova, Alina

    2009-09-01

    To evaluate the use of MR-fetography sequences in identifying the major fetal structures and to compare thick- and thin-slab acquisitions for their diagnostic value. Twenty-one consecutive, pregnant women with suspected fetal pathology underwent fetal magnetic resonance imaging (MRI) using a 1.5 T MRI unit. Heavily T2-weighted, single-shot fast spin-echo (SSFSE) sequences with a long echo train (MR-fetography) were acquired in a thick- and thin-slab modus. Thick- and thin-slab acquisitions were reviewed by two experienced radiologists with regard to the overall image quality and landmark anatomical structures (spinal canal, spinal cord, posterior fossa, cerebellum, brainstem, basal cisterns, stomach, urinary bladder and umbilical cord according to a three-scale grading system (good, moderate and poor). Visibility scores were calculated and compared between both sequences. Overall image quality was graded good in 76.2%, moderate in 19.0% and poor in 4.8% for thick-slab images and good in 81%, moderate in 14.3% and poor in 4.8% for thin-slab images. The visibility scores of the thick/thin-slab images for evaluation of the main fetal structures were as follows: for the spinal canal 2.8+/-0.4/2.9+/-0.54 (p>0.05), spinal cord 2.4+/-0.75/2.7+/-0.66 (p>0.05), posterior fossa components (cerebellum, brainstem and basal cisterns) 2.4+/-0.68/2.8+/-0.54; 2.4+/-0.67/2.7+/-0.66; 2.5+/-0.51/2.7+/-0.56 (p0.05), urinary bladder 2.8+/-0.51/2.8+/-0.54 (p>0.05) and umbilical cord 2.9+/-0.30/2.6+/-0.60 (pslab acquisitions render complementary information. Thick-slab images display the entire fetus in one projection while thin-slab images provide more detailed anatomical information. The short imaging time usually allows measuring both thick- and thin-slab images. MR-fetography is as a helpful addition to conventional fetal MRI. MR-fetography should not be viewed as a single, stand alone sequence but as a supporting fast MR sequence in a well-designed multisequence fetal MRI protocol

  18. Analysis of the effects of an electromagnetic brake (EMBR on flow behaviors in the large slab continuous casting mold

    Directory of Open Access Journals (Sweden)

    C. J. Xu

    2016-07-01

    Full Text Available In the present paper, molten steel flow in the submerged entry nozzle (SEN and mold cavity of large slab continuous caster in both environments (with EMBR and without EMBR were investigated with the method of numerical simulation. In addition, the impacts of electromagnetic brake (EMBR on mol ten steel flow and meniscus fluctuation were discussed while the bath meniscus fluctuation was monitored in a steel plant. Computation results were compared with experimental findings of the factory and it is verified that EMBR can be an efficient technology to control liquid steel flow behaviors in the large slab continuous casting mold.

  19. Application of yield line theory in pre-cast waffle slab | Akinyele ...

    African Journals Online (AJOL)

    Analysis of precast waffle slabs have concentrated on the rib portions, while the slab portion were left unanalyzed. This has led to cracks or outright failure of the slab portions due to under reinforcement. This paper proposed the use of yield line theory in solving this problem. Yield line theory was adopted to develop a ...

  20. MR fetography using heavily T2-weighted sequences: Comparison of thin- and thick-slab acquisitions

    Energy Technology Data Exchange (ETDEWEB)

    Huisman, Thierry A.G.M. [Department of Diagnostic Imaging, University Children' s Hospital Zurich (Switzerland); Division Pediatric Radiology, Johns Hopkins Hospital, Baltimore (United States)], E-mail: thuisma1@jhmi.edu; Solopova, Alina [Department of Diagnostic Imaging, University Children' s Hospital Zurich (Switzerland)

    2009-09-15

    Purpose: To evaluate the use of MR-fetography sequences in identifying the major fetal structures and to compare thick- and thin-slab acquisitions for their diagnostic value. Materials and methods: Twenty-one consecutive, pregnant women with suspected fetal pathology underwent fetal magnetic resonance imaging (MRI) using a 1.5 T MRI unit. Heavily T2-weighted, single-shot fast spin-echo (SSFSE) sequences with a long echo train (MR-fetography) were acquired in a thick- and thin-slab modus. Thick- and thin-slab acquisitions were reviewed by two experienced radiologists with regard to the overall image quality and landmark anatomical structures (spinal canal, spinal cord, posterior fossa, cerebellum, brainstem, basal cisterns, stomach, urinary bladder and umbilical cord according to a three-scale grading system (good, moderate and poor). Visibility scores were calculated and compared between both sequences. Results: Overall image quality was graded good in 76.2%, moderate in 19.0% and poor in 4.8% for thick-slab images and good in 81%, moderate in 14.3% and poor in 4.8% for thin-slab images. The visibility scores of the thick/thin-slab images for evaluation of the main fetal structures were as follows: for the spinal canal 2.8 {+-} 0.4/2.9 {+-} 0.54 (p > 0.05), spinal cord 2.4 {+-} 0.75/2.7 {+-} 0.66 (p > 0.05), posterior fossa components (cerebellum, brainstem and basal cisterns) 2.4 {+-} 0.68/2.8 {+-} 0.54; 2.4 {+-} 0.67/2.7 {+-} 0.66; 2.5 {+-} 0.51/2.7 {+-} 0.56 (p < 0.05), stomach 2.8 {+-} 0.44/2.9 {+-} 0.48 (p > 0.05), urinary bladder 2.8 {+-} 0.51/2.8 {+-} 0.54 (p > 0.05) and umbilical cord 2.9 {+-} 0.30/2.6 {+-} 0.60 (p < 0.05). Conclusion: Heavily T2-weighted MR-fetography renders a quick overview of fetal contours, fetal position, amount of amniotic fluid and integrity and presence of several major fluid containing structures. Thick- and thin-slab acquisitions render complementary information. Thick-slab images display the entire fetus in one projection while

  1. Collision-induced light scattering in a thin xenon layer between graphite slabs - MD study.

    Science.gov (United States)

    Dawid, A; Górny, K; Wojcieszyk, D; Dendzik, Z; Gburski, Z

    2014-08-14

    The collision-induced light scattering many-body correlation functions and their spectra in thin xenon layer located between two parallel graphite slabs have been investigated by molecular dynamics computer simulations. The results have been obtained at three different distances (densities) between graphite slabs. Our simulations show the increased intensity of the interaction-induced light scattering spectra at low frequencies for xenon atoms in confined space, in comparison to the bulk xenon sample. Moreover, we show substantial dependence of the interaction-induced light scattering correlation functions of xenon on the distances between graphite slabs. The dynamics of xenon atoms in a confined space was also investigated by calculating the mean square displacement functions and related diffusion coefficients. The structural property of confined xenon layer was studied by calculating the density profile, perpendicular to the graphite slabs. Building of a fluid phase of xenon in the innermost part of the slot was observed. The nonlinear dependence of xenon diffusion coefficient on the separation distance between graphite slabs has been found. Copyright © 2014. Published by Elsevier B.V.

  2. Thin wall ductile iron casting as a substitute for aluminum alloy casting in automotive industry

    Directory of Open Access Journals (Sweden)

    M. Górny

    2009-01-01

    Full Text Available In paper it is presented thin wall ductile iron casting (TWDI as a substitute of aluminium alloy casting. Upper control arm made of ductile iron with wall thickness ranging from 2 – 3.7 mm was produced by inmold process. Structure, mechanical properties and computer simulations were investigated. Structural analysis of TWDI shows pearlitic-ferritic matrix free from chills and porosity. Mechanical testing disclose superior ultimate tensile strength (Rm, yield strength (Rp0,2 and slightly lower elongation (E of TWDI in comparison with forged control arm made of aluminium alloy (6061-T6. Moreover results of computer simulation of static loading for tested control arms are presented. Analysis show that the light-weight ductile iron casting can be loaded to similar working conditions as the forged Al alloy without any potential failures.

  3. Numerical and Physical Parametric Analysis of a SEN with Flow Conditioners in Slab Continuous Casting Mold

    Directory of Open Access Journals (Sweden)

    Gonzalez-Trejo J.

    2017-06-01

    Full Text Available Some of the most recent technologies that improves the performance in continuous casting process has installed infrastructure outside the mold to modify the natural fluid flow pattern to obtain a quasi-steady condition and promote a uniform solidified shell of steel. The submerged entry nozzle distributes the liquid steel in the mold and can be used to obtain the flow symmetry condition with external geometry improvements. The fluid flow conditioners were located near the outlet ports of the nozzle. The aim of the modifiers is to impose a pseudo symmetric pattern in the upper zone of the mold by inhibiting the fluid exchange between the zones created by conditioners. This work evaluates the effect of the thickness and length of the fluid-flow modifiers on the overall performance of the submerged nozzle. These properties of the fluid-flow modifiers were normalized based on two of the geometric dimensions of the standard equipment. Numerical and physical simulations suggest that the flow modifier should be as thin as possible.

  4. The rate of thermal expansion of a thin metallic slab of arbitrary shape.

    Science.gov (United States)

    Lee, Y C

    2009-08-12

    In a previous paper the rate of thermal expansion of a long, slender insulating bar has been worked out. Our present aim is to extend that work to the thermal expansion rate of not only a long metallic bar, but to further generalize it to a thin metallic slab of arbitrary shape. Assuming that the thickness of the slab is small compared to the linear dimension of its area we again take advantage of the two distinct, disparate timescales to turn the familiar problem of thermal expansion into a time-dependent problem of the rate of the expansion. Based on the previously established finite physical momentum of an acoustic phonon when translational invariance is broken, we show that the combined pressure of the phonons and the free electrons due to their outward momenta would suffer a Doppler reduction as the specimen expands upon heating. This Doppler reduction gives rise to damping of the expanding motion, thus yielding as a first result the time of thermal expansion of a long slender metal bar. The generalization to the important case of a thin metallic slab of any shape is then worked out in detail before a concluding section containing a long physical discussion and summary.

  5. Temperature measurement during solidification of thin wall ductile cast iron. Part 1: Theory and experiment

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2008-01-01

    Temperature measurement using thermocouples (TC’s) influence solidification of the casting, especially in thin wall castings. The problems regarding acquisition of detailed cooling curves from thin walled castings is discussed. Experiments were conducted where custom made TC’s were used to acquire...... cooing curves in thin wall ductile iron castings. The experiments show how TC’s of different design interact with the melt and how TC design and surface quality affect the results of the data acquisition. It is discussed which precautions should be taken to ensure reliable acquisition of cooling curves...

  6. Research on Soft Reduction Amount Distribution to Eliminate Typical Inter-dendritic Crack in Continuous Casting Slab of X70 Pipeline Steel by Numerical Model

    Science.gov (United States)

    Liu, Ke; Wang, Chang; Liu, Guo-liang; Ding, Ning; Sun, Qi-song; Tian, Zhi-hong

    2017-04-01

    To investigate the formation of one kind of typical inter-dendritic crack around triple point region in continuous casting(CC) slab during the operation of soft reduction, fully coupled 3D thermo-mechanical finite element models was developed, also plant trials were carried out in a domestic continuous casting machine. Three possible types of soft reduction amount distribution (SRAD) in the soft reduction region were analyzed. The relationship between the typical inter-dendritic cracks and soft reduction conditions is presented and demonstrated in production practice. Considering the critical strain of internal crack formation, a critical tolerance for the soft reduction amount distribution and related casing parameters have been proposed for better contribution of soft reduction to the internal quality of slabs. The typical inter-dendritic crack around the triple point region had been eliminated effectively through the application of proposed suggestions for continuous casting of X70 pipeline steel in industrial practice.

  7. Effect of slab thickness on the CT detection of pulmonary nodules: use of sliding thin-slab maximum intensity projection and volume rendering.

    Science.gov (United States)

    Kawel, Nadine; Seifert, Burkhardt; Luetolf, Marcus; Boehm, Thomas

    2009-05-01

    The objective of this study was to evaluate the detection rates of pulmonary nodules on CT as a function of slab thickness using sliding thin-slab maximum intensity projection (MIP) and volume rendering (VR). Eighty-eight oncology patients (33 women, 55 men; mean age, 59 years; age range, 18-81 years) who routinely underwent chest CT examinations were prospectively included. Two radiologists independently evaluated each CT examination for the presence of pulmonary nodules using MIP and VR, with each image reconstructed using three different slab thicknesses (5, 8, 11 mm). The standard of reference was the maximum number of detected nodules, which were classified by localization and size, judged to be true-positives by a consensus panel. Interreader agreement was assessed by kappa value on a nodule-by-nodule basis. Sensitivities for both reconstruction techniques and for the three slab thicknesses were calculated using the proportion procedure for survey data with the patient as the primary sample unit and were compared using the Wilcoxon's signed rank test with Bonferroni correction for both readers separately. One thousand fifty-eight true-positive nodules were detected. Interreader agreement was fair to moderate. Sensitivity for pulmonary nodules was superior for 8-mm MIP (reader 1, 84%; reader 2, 81%) and was significantly better than the sensitivities of all other tested techniques for both readers (p 8 mm). A higher sensitivity was achieved using MIP than VR. MIP with a slab thickness of 8 mm is superior in the detection of pulmonary nodules to all other tested techniques.

  8. Investigation of solidification of thin walled ductile cast iron using temperature measurement

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels

    2005-01-01

    Investigation of solidification of thin walled ductile cast iron can be improved using temperature measurement. This article includes some background of the precautions that have to be taken when measuring temperatures in thin walled castings. The aim is to minimize influence of temperature...... measurement on castings and to get sufficient response time of thermocouples. Investigation of thin wall ductile iron has been performed with temperature measurement in plates with thickness between 2,8 and 8mm. The cooling curves achieved are combined with examination of the microstructure in order to reveal...

  9. Role of Titanium in Thin Wall Vermicular Graphite Iron Castings Production

    Directory of Open Access Journals (Sweden)

    Górny M.

    2013-06-01

    Full Text Available In this paper the effects of titanium addition in an amount up to 0.13 wt.% have been investigated to determine their effect on the microstructure and mechanical properties of Thin Wall Vermicular Graphite Iron Castings (TWVGI. The study was performed for thinwalled iron castings with 3-5 mm wall thickness and for the reference casting with 13 mm. Microstructural changes were evaluated by analyzing quantitative data sets obtained by image analyzer and also using scanning electron microscope (SEM. Metallographic examinations show that in thin-walled castings there is a significant impact of titanium addition to vermicular graphite formation. Thinwalled castings with vermicular graphite have a homogeneous structure, free of chills, and good mechanical properties. It may predispose them as a potential use as substitutes for aluminum alloy castings in diverse applications.

  10. Comparative analysis of the results of experimental and numerical studies of the performance of cross-beam butt joint with a column in slab cast over precast joists

    Directory of Open Access Journals (Sweden)

    Koyankin Aleksandr Aleksandrovich

    2015-12-01

    Full Text Available At the present moment in Russia the construction of precast and cast-in-place frame buildings are widely spread in Russia. This technology is the most advanced because of the possibility of maximally efficient simultaneous use of the advantages of precast and monolithic housing construction with minimizing their disadvantages. At the same time the volume of the scientific researches on stress-strain state of cast-in-place and precast constructions is not enough to objectively evaluate the bearing capacity, rigidity and crack-resistance of such buildings. Cast-in-place and precast construction covers a considerable part in large-scale construction, but despite this, there is a great variety of gaps in the understanding of such construction performance. Reasoning from this fact, numerical and experimental research has been carried out on studying of the performance of longitudinal beam joint to column with a column in slab cast over precast joists.

  11. Electromagnetic augmentation for casting of thin metal sheets

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL)

    1989-01-01

    Thin metal sheets are cast by magnetically levitating molten metal deposited in a mold within a ferromagnetic yoke and between AC conducting coils and linearly displacing the magnetically levitated liquid metal while it is being cooled by the water-cooled walls of the mold to form a solid metal sheet. A conducting shield is electrically coupled to the molten metal sheet to provide a return path for eddy currents induced in the metal sheet by the current in the AC conducting coils. In another embodiment, a DC conducting coil is coupled to the metal sheet for providing a direct current therein which interacts with the magnetic field to levitate the moving metal sheet. Levitation of the metal sheet in both molten and solid forms reduces its contact pressure with the mold walls while maintaining sufficient engagement therebetween to permit efficient conductive cooling by the mold through which a coolant fluid may be circulated. The magnetic fields associated with the currents in the aforementioned coils levitate the molten metal sheet while the mold provides for its lateral and vertical confinement. A leader sheet having electromagnetic characteristics similar to those of the molten metal sheet is used to start the casing process and precedes the molten metal sheet through the yoke/coil arrangement and mold and forms a continuous sheet therewith. The yoke/coil arrangement may be either U-shaped with a single racetrack coil or may be rectangular with a pair of spaced, facing bedstead coils.

  12. Low-head feeding system for thin section castings

    Science.gov (United States)

    Daniel, Sabah S.; Kleeb, Thomas R.; Lewis, Thomas W.; McDermott, John F.; Ozgu, Mustafa R.; Padfield, Ralph C.; Rego, Donovan N.; Vassilicos, Achilles

    1990-01-01

    A feed system is provided for conveying molten metal to a thin section caster having mold surfaces moving exclusively in the direction of casting. The feed system has a passage of circular cross section adjacent to one end thereof for receiving molten metal and a rectangular cross section at the delivery end thereof adjacent to the caster. The feed system is designed for supplying molten metal to the caster at low pressure for "closed-pool" type caster operation. The point of highest elevation in the metal flow passage of the feed system is on the upper surface of a transition portion where the cross section changes from circular to rectangular adjacent to the nozzle. The level or height of the high point above the centerline of the nozzle exit is selected so as to be less than the pressure of the metal measured in inches at the nozzle exit. This feature enables the maintenance of positive pressure in the metal within the feed system so that ingress of air into the metal is prevented.

  13. Numerical modelling of thin-walled hypereutectic ductile cast iron parts

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Hattel, Jesper Henri; Tiedje, Niels Skat

    2006-01-01

    Solidification of hypereutectic thin-walled ductile cast iron has been modelled in one dimension taking into account the precipitation of off-eutectic austenite dendrites during solidification. The simulations have been compared with casting experiments on plate geometries with plate thicknesses...

  14. Optimization of low-contrast detectability in thin-collimated modern multidetector CT using an interactive sliding-thin-slab averaging algorithm.

    Science.gov (United States)

    von Falck, Christian; Hartung, Alexander; Berndzen, Frank; King, Benjamin; Galanski, Michael; Shin, Hoen-oh

    2008-04-01

    To analyze the effects of the sliding-thin-slab averaging algorithm on low-contrast performance in MDCT imaging and to find reasonable parameters for clinical routine work. A low-contrast phantom simulating hypodense lesions (20 HU object contrast) was scanned with a 16-slice spiral CT scanner using different mAs-settings of 25, 50, 100, and 195 mAs. Other scan parameters were as follows: tube voltage = 120 kVp, slice collimation = 0.625 mm, pitch = 1.375 (high speed), reconstruction interval = 0.5 mm. Images were reconstructed with soft, standard, and bone algorithms, resulting in a total of 12 datasets. A sliding-thin-slab averaging algorithm was applied to these primary datasets, systematically varying the slab thickness between 0.5 and 5.0 mm. The low-contrast performance of the resulting datasets was semi-automatically analyzed using a statistical reader-independent approach: A size-dependent analysis of the image noise within the phantom was used to empirically generate a contrast discrimination function (CDF). The ratio between the actual contrast and the minimum contrast necessary for the detection (as given by the CDF) was calculated for all lesions in each dataset and used to evaluate the low-contrast detectability of the different lesions at increasing slab thickness. The results were compared with the original datasets to calculate the improvement in low-contrast detectability. Using the sliding-thin-slab algorithm, low-contrast performance was increased by a factor between 1.1 and 1.7 when compared with the primary dataset. The improvement of the visibility index at optimal slab thickness when compared with the original slice thickness (0.625 mm) was statistically significant (P slab thickness over all datasets was 43% (+/-3%) of the diameter of the lesion to be detected. The use of an interactive sliding-thin-slab averaging algorithm can be readily applied to optimize low-contrast detectability in thin-collimated CT datasets. As a general rule for

  15. Solidification and microstructure of thin walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin

    2006-01-01

    In the recent years there has been an increasing interest in light constructions in order to save weight in e.g. cars. Ductile cast iron has good mechanical properties but it is necessary to re­duce the wall thicknesses of the castings in order to reduce the weight. Reducing the wall thicknesses...... of the casting will increase the cooling rates and by that change the conditions for nucleation and growth during solidification....

  16. Surface Modification of Cored, Thin Walled Castings of Nickel Superalloy IN-713C

    Directory of Open Access Journals (Sweden)

    Binczyk F.

    2015-09-01

    Full Text Available In current casting technology of cored, thin walled castings, the modifying coating is applied on the surface of wax pattern and, after the removal of the wax, is transferred to inner mould surface. This way the modification leading to grain refinement occur on the surface of the casting. In thin walled castings the modification effect can also be seen on the other (external side of the casting. Proper reproduction of details in thin walled castings require high pouring temperature which intensify the chemical reactions on the mould – molten metal interface. This may lead to degradation of the surface of the castings. The core modification process is thought to circumvent this problem. The modifying coating is applied to the surface of the core. The degradation of internal surface of the casting is less relevant. The most important factor in this technology is “trough” modification – obtaining fine grained structure on the surface opposite to the surface reproduced by the core.

  17. Numerical modelling of solidification of thin walled hypereutectic ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Hattel, Jesper; Tiedje, Niels

    2006-01-01

    Numerical simulation of solidification of ductile cast iron is normally based on a model where graphite nodules are surrounded by an austenite shell. The two phases are then growing as two concentric spheres governed by diffusion of carbon through the austenite shell. Experiments have however shown...... simulation of thin-walled ductile iron castings. Simulations have been performed with a 1-D numerical solidi¬fication model that includes the precipitation of non-eutectic austenite during the eutectic stage. Results from the simulations have been compared with experimental castings with wall thick...... the presence of austenite dendrites even in hypereutectic castings. In thin-walled castings the presence of austenite dendrites is even more pronounced, which increases the risk of shrinkage porosities. This off-eutectic austenite is therefore an important part that should be taken into account during...

  18. Temperature measurement during solidification of thin wall ductile cast iron. Part 2: Numerical simulations

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2008-01-01

    Temperature measurements in castings are carried out with thermocouples (TC’s), which are inserted in the melt. The TC influence solidification of the casting, especially in thin wall castings where the heat content of the melt is small compared to the cooling power of the TC. A numerical analysis...... of factors influencing temperature measurement in thin walled castings was carried out. The calculations are based on and compared with experiments presented in part 1 of this paper. The analysis shows that the presence of the TC has only a minor influence on the microstructure of the casting. The influence...... is restricted to a volume within 2mm from the TC. Measured cooling curves will have the right shape. In a 2 mm plate the measured temperature was 17 °C below the true temperature in the melt. However, the cooling curve provides important information about nucleation and growth during solidification....

  19. Graphite nodule count and size distribution in thin-walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2008-01-01

    Graphite nodule count and size distribution have been analysed in thin walled ductile cast iron. The 2D nodule counts have been converted into 3D nodule count by using Finite Difference Method (FDM). Particles having a diameter smaller than 5 µm should be neglected in the nodule count...... as these are inclusions and micro porosities that do not influence the solidification morphology. If there are many small graphite nodules as in thin walled castings only 3D nodule count calculated by FDM will give reliable results. 2D nodule count and 3D nodule count calculated by simple equations will give too low...... results. The 3D size distribution showed presence of primary graphite nodules in hypereutectic castings. In thin plates the nodule count is similar in eutectic and hypereutectic plates. In thicker plates the hypereutectic casting has the highest nodule count....

  20. Fabrication and properties of strip casting 4.5 wt% Si steel thin sheet

    International Nuclear Information System (INIS)

    Zu, Guoqing; Zhang, Xiaoming; Zhao, Jingwei; Wang, Yuqian; Yan, Yi; Li, Chengang; Cao, Guangming; Jiang, Zhengyi

    2017-01-01

    Three 4.5 wt% Si steel thin sheets with different thicknesses were efficiently fabricated by twin-roll strip casting, warm rolling and cold rolling followed by final annealing. A comprehensive investigation from the workability of the as-cast strip to the magnetic property of the produces was performed to illustrate the superiority of the new materials. The results show that the as-cast strip, which has a much lower Vickers hardness than that of the 6.5 wt% Si steel, is suitable for rolling processing. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies confirm that no ordering phase exists in the as-cast strip. The cold-rolled thin sheets exhibit good surface quality without edge cracks. Furthermore, all the three 4.5 wt% Si steel thin sheets possess relative strong <100>//ND texture and present high magnetic inductions and low iron losses after finial annealing. - Highlights: • 4.5 wt% Si as-cast sheet with excellent workability was produced by strip casting. • Three 4.5 wt% Si thin sheets were effectively fabricated by warm and cold rolling. • The microstructure and macro-texture of the thin sheets were elucidated. • High magnetic inductions and low iron losses were achieved simultaneously.

  1. Fabrication and properties of strip casting 4.5 wt% Si steel thin sheet

    Energy Technology Data Exchange (ETDEWEB)

    Zu, Guoqing, E-mail: gz854@uowmail.edu.au [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Zhang, Xiaoming [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Zhao, Jingwei [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Wang, Yuqian [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Yan, Yi [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Li, Chengang; Cao, Guangming [State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Jiang, Zhengyi [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia)

    2017-02-15

    Three 4.5 wt% Si steel thin sheets with different thicknesses were efficiently fabricated by twin-roll strip casting, warm rolling and cold rolling followed by final annealing. A comprehensive investigation from the workability of the as-cast strip to the magnetic property of the produces was performed to illustrate the superiority of the new materials. The results show that the as-cast strip, which has a much lower Vickers hardness than that of the 6.5 wt% Si steel, is suitable for rolling processing. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies confirm that no ordering phase exists in the as-cast strip. The cold-rolled thin sheets exhibit good surface quality without edge cracks. Furthermore, all the three 4.5 wt% Si steel thin sheets possess relative strong <100>//ND texture and present high magnetic inductions and low iron losses after finial annealing. - Highlights: • 4.5 wt% Si as-cast sheet with excellent workability was produced by strip casting. • Three 4.5 wt% Si thin sheets were effectively fabricated by warm and cold rolling. • The microstructure and macro-texture of the thin sheets were elucidated. • High magnetic inductions and low iron losses were achieved simultaneously.

  2. Development of a thin steel strip casting process. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Williams, R.S.

    1994-04-01

    This is a comprehensive effort to develop direct strip casting to the point where a pilot scale program for casting carbon steel strip could be initiated. All important aspects of the technology were being investigated, however the program was terminated early due to a change in the business strategy of the primary contractor, Armco Inc. (focus to be directed at specialty steels, not low carbon steel). At termination, the project was on target on all milestones and under budget. Major part was casting of strip at the experiment casting facility. A new caster, capable of producing direct cast strip of up to 12 in. wide in heats of 1000 and 3000 lb, was used. A total of 81 1000-1200 lb heats were cast as well as one test heat of 3000 lb. Most produced strip of from 0.016 to 0.085 in. thick. Process reliability was excellent for short casting times; quality was generally poor from modern hot strip mill standards, but the practices necessary for good surface quality were identified.

  3. Rapid precision casting for complex thin-walled aluminum alloy parts

    Directory of Open Access Journals (Sweden)

    Xuanpu DONG

    2004-11-01

    Full Text Available Based on Vacuum Differential Pressure Casting (VDPC precision forming technology and the Selective Laser Sintering (SLS Rapid Prototyping (RP technology, a rapid manufacturing method called Rapid Precision Casting (RPC process from computer three-dimensional solid models to metallic parts was investigated. The experimental results showed that the main advantage of RPC was not only its ability to cast higher internal quality and more accurate complex thin-walled aluminum alloy parts, but also the greatly-reduced lead time cycle from Selective Laser Sintering(SLS plastic prototyping to metallic parts. The key forming technology of RPC for complex thin-walled metallic parts has been developed for new casting production and Rapid Tooling (RT, and it is possible to rapidly manufacture high-quality and accurate metallic parts by means of RP in foundry industry.

  4. Solidification of Hypereutectic Thin Wall Ductile Cast Iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2006-01-01

    Hypereutectic ductile iron was cast in green sand moulds with four plates with thickness of 1.5, 2, 3 and 4 mm in each mould. Temperatures were measured in the 3 and 4 mm plate. The temperature curves showed that eutectic solidification was divided into two stages: primary and secondary eutectic...

  5. Development of Thin Section Zinc Die Casting Technology

    Energy Technology Data Exchange (ETDEWEB)

    Goodwin, Frank [International Lead Zinc Research Org., Inc., Durham, NC (United States)

    2013-10-31

    A new high fluidity zinc high pressure die casting alloy, termed the HF alloy, was developed during laboratory trials and proven in industrial production. The HF alloy permits castings to be achieved with section thicknesses of 0.3 mm or less. Technology transfer activities were conducted to develop usage of the HF high fluidity alloy. These included production of a brochure and a one-hour webinar on the HF alloy. The brochure was then sent to 1,184 product designers in the Interzinc database. There was excellent reception to this mailing, and from this initial contact 5 technology transfer seminars were conducted for 81 participants from 30 companies across a wide range of business sectors. Many of the successful applications to date involve high quality surface finishes. Design and manufacturing assistance was given for development of selected applications.

  6. Mechanism of Filling and Feeding of Thin-Walled Structures during Gravity Casting

    Directory of Open Access Journals (Sweden)

    Faguo Li

    2015-06-01

    Full Text Available The filling and feeding of thin-walled structures in metal castings pose significant difficulties in manufacturing aerospace structural materials. Samples containing 2 mm and 5 mm thin-walled structures were designed to study the kinetics of filling. The microstructural evolution of the solidification of thin-walled structures was studied with synchrotron X-radiation imaging. The formation of dendritic networks and the isotherm profiles of samples of different thickness were examined. The experimental results showed solidification microstructures of 2 mm and 5 mm thin-walled parts containing elongated equiaxed grains and normal equiaxed grains, respectively. The filling and feeding abilities of thin-walled parts were found to depend more on the wall thickness than on the pouring temperature.

  7. Modelling of fluid flow in tape casting of thin ceramics: Analytical approaches and numerical investigations

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri

    2016-01-01

    Tape casting has been used to produce thin layers of ceramics that can be used as single layers or can be stacked and laminated into multilayered structures. Many startup products such as multilayered inductors, multilayered varistors, piezoelectrics, ceramic fuel cells and lithium ion battery...... the physical parameters crucial to the process. A review of the development of the tape casting process with particular focus on modelling the material flow is presented and in this context the current status is examined and future potential discussed....

  8. Gating System Design for Casting thin Aluminium Alloy (Al-Si Plates

    Directory of Open Access Journals (Sweden)

    Victor ANJO

    2013-11-01

    Full Text Available The main problems caused by improper gating are entrained aluminium oxide films, cuts and washes, low casting yield and entrapped gas. This study describes the design of a gating system to produce thin Aluminium cast alloy plates of different sizes and thicknesses of 4mm, 6mm, 8mm, and 10mm using the non-pressurized gating with ratio of 1:4:4 and green sand moulding technique. The gating design was based on the laws of fluid mechanics and empirical rules of gating for non ferrous metals. The equipments used for this experiment includes; a coal fired crucible furnace and an X-Ray machine. Materials used include; silica sand, clay, wood, glue and Aluminium alloy scraps. The experimental procedure involved: the gating design calculations, construction of wooden pattern and gating; using the wooden pattern and gating to produce the mould cavities and gating; melting, melt treatment and pouring of melt in the sand mould to produce the casting. The plate castings after removal from mould were visually examined for surface defects and after fettling and cleaning X-Ray radiography was used to find the internal soundness of the castings. From the results obtained in the experiment, it was found that there were no internal defects and quality castings were produced.

  9. Thin Gauge Twin-Roll Casting, Process Capabilities and Product Quality

    Science.gov (United States)

    Daaland, O.; Espedal, A. B.; Nedreberg, M. L.; Alvestad, I.

    Traditionally industrial twin roll casters have been operated at gauges 6-10 mm, depending on the type of caster and the final product requirements. Over the past few years it has become apparent that a significant increase in productivity can be achieved when the casting gauge is reduced. Hydro Aluminium embarked on an extensive research and development, thin gauge casting programme, in the beginning of the 1990's and this paper presents some results from a five year lasting project (joint programme between Hydro Aluminium a.s. and Lauener Engineering). Based on more than 400 casting trials the major benefits and limitations of casting at reduced gauge and increased speed are outlined. Important aspects related to process development and product quality are discussed including: productivity and limitations, surface defects, microstructural characteristics, cooling rates and dendrite structure, segregation behaviour and mechanical properties after thermo-mechanical processing. Results for casting of several alloys are given. Additionally, numerical modelling results of the strip casting process are included.

  10. Experimental validation of error in temperature measurements in thin walled ductile iron castings

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2007-01-01

    An experimental analysis has been performed to validate the measurement error of cooling curves measured in thin walled ductile cast iron. Specially designed thermocouples with Ø0.2 mm thermocouple wire in Ø1.6 mm ceramic tube was used for the experiments. Temperatures were measured in plates...... with thicknesses between 2 and 4.3 mm. The thermocouples were accurately placed at the same distance from the surface of the casting for different plate thicknesses. It is shown that when measuring the temperature in plates with thickness between 2 and 4.3 mm the measured temperature will be parallel shifted...... to a level about 20C lower than the actual temperature in the casting. Factors affecting the measurement error (oxide layer on the thermocouple wire, penetration into the ceramic tube and variation in placement of thermocouple) are discussed. Finally, it is shown how useful cooling curve may be obtained...

  11. Conductivity of PEDOT:PSS on Spin-Coated and Drop Cast Nanofibrillar Cellulose Thin Films.

    Science.gov (United States)

    Valtakari, Dimitar; Liu, Jun; Kumar, Vinay; Xu, Chunlin; Toivakka, Martti; Saarinen, Jarkko J

    2015-12-01

    Aqueous dispersion of conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) ( PSS) was deposited on spin-coated and drop cast nanofibrillar cellulose (NFC)-glycerol (G) matrix on a glass substrate. A thin glycerol film was utilized on plasma-treated glass substrate to provide adequate adhesion for the NFC-glycerol (NFC-G) film. The effects of annealing temperature, the coating method of NFC-G, and the coating time intervals on the electrical performance of the PSS were characterized. PSS on drop cast NFC-G resulted in 3 orders of magnitude increase in the electrical conductivity compared to reference PSS film on a reference glass substrate, whereas the optical transmission was only slightly decreased. The results point out the importance of the interaction between the PSS and the NFC-G for the electrical and barrier properties for thin film electronics applications.

  12. Multichannel all–optical switch based on a thin slab of resonant two–level emitters

    Directory of Open Access Journals (Sweden)

    Malikov Ramil

    2017-01-01

    Full Text Available We discuss the possibility of using a thin layer of inhomogeneously broadened resonant emitters as a multichannel all–optical switch. Switching time from the lower stable branch of the system's bistable characteristics to the upper one and vice versa, which determines the speed of operation of a bistable device, is studied.

  13. Development of Integrated Die Casting Process for Large Thin-Wall Magnesium Applications

    Energy Technology Data Exchange (ETDEWEB)

    Carter, Jon T. [General Motors LLC, Warren, MI (United States); Wang, Gerry [Meridian Lightweight Technologies, Plymouth MI (United States); Luo, Alan [General Motors LLC, Warren, MI (United States)

    2017-11-29

    The purpose of this project was to develop a process and product which would utilize magnesium die casting and result in energy savings when compared to the baseline steel product. The specific product chosen was a side door inner panel for a mid-size car. The scope of the project included: re-design of major structural parts of the door, design and build of the tooling required to make the parts, making of parts, assembly of doors, and testing (both physical and simulation) of doors. Additional work was done on alloy development, vacuum die casting, and overcasting, all in order to improve the performance of the doors and reduce cost. The project achieved the following objectives: 1. Demonstrated ability to design a large thin-wall magnesium die casting. 2. Demonstrated ability to manufacture a large thin-wall magnesium die casting in AM60 alloy. 3. Tested via simulations and/or physical tests the mechanical behavior and corrosion behavior of magnesium die castings and/or lightweight experimental automotive side doors which incorporate a large, thin-wall, powder coated, magnesium die casting. Under some load cases, the results revealed cracking of the casting, which can be addressed with re-design and better material models for CAE analysis. No corrosion of the magnesium panel was observed. 4. Using life cycle analysis models, compared the energy consumption and global warming potential of the lightweight door with those of a conventional steel door, both during manufacture and in service. Compared to a steel door, the lightweight door requires more energy to manufacture but less energy during operation (i.e., fuel consumption when driving vehicle). Similarly, compared to a steel door, the lightweight door has higher global warming potential (GWP) during manufacture, but lower GWP during operation. 5. Compared the conventional magnesium die casting process with the “super-vacuum” die casting process. Results achieved with cast tensile bars suggest some

  14. Elongated phase separation domains in spin-cast polymer blend thin films characterized using a panoramic image.

    Science.gov (United States)

    Zhang, Hong; Okamura, Yosuke

    2018-02-14

    Polymer thin films with micro/nano-structures can be prepared by a solvent evaporation induced phase separation process via spin-casting a polymer blend, where the elongated phase separation domains are always inevitable. The striation defect, as a thickness nonunifomity in spin-cast films, is generally coexistent with the elongated domains. Herein, the morphologies of polymer blend thin films are recorded from the spin-cast center to the edge in a panoramic view. The elongated domains are inclined to appear at the ridge regions of striations with increasing radial distance and align radially, exhibiting a coupling between the phase separation morphology and the striation defect that may exist. We demonstrate that the formation of elongated domains is not attributed to shape deformation, but is accomplished in situ. A possible model to describe the initiation and evolution of the polymer blend phase separation morphology during spin-casting is proposed.

  15. Sliding thin slab, minimum intensity projection of the lung in asymptomatic subjects: lower limits of lung attenuation, without airways

    International Nuclear Information System (INIS)

    Ishihara, Katsutoshi; Satoh, Shiro; Ohdama, Shinichi; Shibuya, Hitoshi

    2006-01-01

    A sliding thin slab, minimum intensity projection (STS-MinIP) is considered to be useful for detecting diseases that decrease lung attenuation. For evaluating these diseases, it would be useful to ascertain the lower limits of normal lung attenuation, allowing a division between normal and subnormal attenuation. However, normal lung attenuation may vary depending on respiratory status, anatomical position, and patient background factors. Our aim was to determine whether the lower limits of lung attenuation, without airways, in asymptomatic subjects using STS-MinIP varies under different conditions. The study subjects were 43 volunteers without pulmonary symptoms. STS-MinIP was performed at full inspiration and full expiration at three levels of the lung. The lower limits of lung attenuation were compared among the three lung levels and between full inspiration and full expiration, the sexes, age groups, smokers and nonsmokers, and the right and left lungs. The lower limits of lung attenuation had significantly different Hounsfield unit values among lung levels, between the sexes at full inspiration, and between age groups at full expiration. This study shows that the lower limits of lung attenuation are influenced by lung fields, sex, and, on expiration, age. (author)

  16. The effect of cast-to-cast variations on the quality of thin section nickel alloy welded joints

    International Nuclear Information System (INIS)

    Lambert, J.A.

    1989-02-01

    The welding behaviour of 26 commercial casts of Alloy 800 has been quantified for mechanised, autogenous, full penetration, bead-on-strip tungsten inert gas welding tests. Weld front and back widths have been measured and correlated with minor element variations. Casts with similar welding responses have been sorted into groups. The behaviour of the weld pool, surface slags and arc have been compared and a convection controlled model has been used to account for differences between the groups of casts. The main factors governing laboratory process control variability have been identified and a statistical method has been used to identify all the components of weld variance. An optimum size of welding test matrix has been proposed to determine typical cast-to-cast variations at high significance levels. (author)

  17. Carcass and physical meat characteristics of thin tail sheep (TTS based on calpastatin gene (CAST (Locus intron 5 – exon 6 genotypes variation

    Directory of Open Access Journals (Sweden)

    Muhammad Ihsan Andi Dagong

    2012-03-01

    Full Text Available The quality of sheep carcass is mostly determined by the total lean meat production, meat distribution on the carcass and the quality of meat. Calpastatin gene (CAST is known to have an association with carcass and meat quality traits. The objective of this research was to identify the association between CAST polymorphisms and carcass characteristics in Thin Tail Sheep (TTS. Thirty three heads of sheep representing three genotypes of CAST (CAST-11, CAST-12 and CAST-22 were identified for carcass and meat characterisation. There was no significant difference between CAST polymorphisms with meat tenderness, pH, water holding capacity and cooking loss, neither with carcass weight and dressing percentage among genotypes. Shoulder proportion of CAST-11 genotype was larger than that of CAST-12 or CAST-22, but the lean meat proportion of CAST-22 genotype in shoulder, rack and loin were higher than those of CAST-11 but not different from CAST-12. The fat percentage of CAST-11 was the highest among the genotypes. CAST-22 genotype has higher lean meat percentage than the CAST-11. Variation in CAST gene could be used as marker assisted selection in sheep for higher lean meat proportion.

  18. Spread prestressed concrete slab beam bridges.

    Science.gov (United States)

    2015-04-01

    TxDOT uses prestressed slab beam bridges for short-span bridges ranging from approximately 3050 ft in : length. These bridges have precast, pretensioned slab beams placed immediately adjacent to one another : with a cast-in-place slab made composi...

  19. Experimental study of thin square slabs, embedded on all four sides (pressure vessel floors)

    International Nuclear Information System (INIS)

    Valentin, A.

    1967-03-01

    This work was designed to test experimentally the mechanical strength of large thin plates made of non-magnetic stainless steel and subjected to transverse forces; these plates are intended to be used as the flooring of pressure vessels. The characteristics are as follows: Test 1: type: NS 22 S - Ugine; overall cross-section mm x mm: 1497 x 1555,5; thickness mm: 3 Test 2: type: Fluginox 130 - Ugine; overall cross-section mm x mm: 2100 x 2100; thickness mm: 3 Test 3: type: 832 MVR - Avesta; overall cross-section mm x mm: 2090 x 2090; thickness mm: 5. The plates were mounted on frames, each pillar of which had been previously pre-stressed, at its centre point, with a force of 300 kg (test 1), 600 kg (test 2), 800 kg (test 3). The experiments showed that the amounts of flexion at the centre w were related to the loads q by equations of the type: qa 4 /Dh = w/h[A+B(w/h) 2 ] where 2a, h and D represent respectively the length of a side, the thickness and the rigidity under flexion of the plates held on the four sides. The coefficients A and B have been determined for different cases; the equations obtained are discussed. It is shown in particular that prestressing of the pillars is beneficial but that the movement of the plates at their edges cannot be considered to be non-existent with the set-ups used. (author) 1967 [fr

  20. Optimization of Gating System Design for Die Casting of Thin Magnesium Alloy-Based Multi-Cavity LCD Housings

    Science.gov (United States)

    Lee, B. D.; Baek, U. H.; Han, J. W.

    2012-09-01

    High-pressure die casting is the preferred process for manufacturing Mg-alloy components used for numerous applications. High-pressure die casting is suitable for mass production and has the advantage of also being suitable for accurately fashioning objects of complicated shapes. One disadvantage of high-speed die casting is the occurrence of defects such as shrinkage or air entrainment. Gating system design must be very effective in actual manufacturing facilities to avoid the occurrence of such defects. The objective of this study is to present a methodology for obtaining optimal designs of 4-cavity thin electronic component housings. The fluid behavior and amount of air entrainment caused by the overflows and air vent designs were analyzed using a computer fluid dynamics (CFD) simulator. The effectiveness of the proposed system was demonstrated through CFD simulations and experiments using an actual manufacturing process. Also, the effect of vacuum systems on the porosity and mechanical properties of the castings was studied. The volume of porosity in the casting was found to be significantly reduced using vacuum assistance during die casting. As a result, the tensile strength and the elongation of the die casting products are improved.

  1. Bridge approach slabs for Missouri DOT field evaluation of alternative and cost efficient bridge approach slabs.

    Science.gov (United States)

    2013-05-01

    Based on a recent study on cost efficient alternative bridge approach slab (BAS) designs (Thiagarajan et : al. 2010) has recommended three new BAS designs for possible implementation by MoDOT namely a) 20 feet cast-inplace : slab with sleeper slab (C...

  2. Influence of rare earths on shrinkage porosity in thin walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2009-01-01

    Ductile cast iron has been cast in test bars with thickness from 2 to 10 mm. The rare earth elements La and Ce have been added to some of the castings to evaluate their influence on microstructure and shrinkage tendency. Both La and Ce increased the graphite nodule count, especially for thickness...

  3. Indirect Fabrication of Lattice Metals with Thin Sections Using Centrifugal Casting.

    Science.gov (United States)

    Mun, Jiwon; Ju, Jaehyung; Thurman, James

    2016-05-14

    One of the typical methods to manufacture 3D lattice metals is the direct-metal additive manufacturing (AM) process such as Selective Laser Melting (SLM) and Electron Beam Melting (EBM). In spite of its potential processing capability, the direct AM method has several disadvantages such as high cost, poor surface finish of final products, limitation in material selection, high thermal stress, and anisotropic properties of parts. We propose a cost-effective method to manufacture 3D lattice metals. The objective of this study is to provide a detailed protocol on fabrication of 3D lattice metals having a complex shape and a thin wall thickness; e.g., octet truss made of Al and Cu alloys having a unit cell length of 5 mm and a cell wall thickness of 0.5 mm. An overall experimental procedure is divided into eight sections: (a) 3D printing of sacrificial patterns (b) melt-out of support materials (c) removal of residue of support materials (d) pattern assembly (e) investment (f) burn-out of sacrificial patterns (g) centrifugal casting (h) post-processing for final products. The suggested indirect AM technique provides the potential to manufacture ultra-lightweight lattice metals; e.g., lattice structures with Al alloys. It appears that the process parameters should be properly controlled depending on materials and lattice geometry, observing the final products of octet truss metals by the indirect AM technique.

  4. Simplified model of metal solidification in the thin plane cavity of the casting mould

    Directory of Open Access Journals (Sweden)

    L. Sowa

    2008-03-01

    Full Text Available In thc papcr, a innthcmatical inodcl of thc solidification of a thin-wallcd casting, which takcs into account thc proccss or filling thc mouldcavity wilh moltcn tnetal. has hccn proposed. Prcssurc and vcloci~yf iclds wcrc obtaincd by solving thc ino~ncntl~mctl iiations and rhccontinuity cquation. whilc [he thcrtnal hclds were ubtaincd by solving thc hcat conduction equation containing rhc convcciion tcrm.Making assumptions rcla~ingt o both thc rnatcrial and Ihc gcornctry e l t he rcgion. thc gcncral equations for continuity and rnomcntiun havcbccn rcduccd to single cquation for prcssurc. This approach Icads as to furlhcr si~npliryo f ~licf luid flow cnlculations, I11 thc tnodcl onctakes into account intcrdcpcndcncc Ihc hcat Iransfcr and fluid flow phcnomcna. Coupling of zhc thcrmnl and fluid flow plicnomcna hasbccn takcn into consideration by the changcs of thc fluidity fitnction and thcnnophysical paramctcrs of alloy with rcspcct lo thcrcrnperaLure. Thc problem has bccn solvcd by ihc finilc clcmcnt mcrhod.

  5. Slab track

    OpenAIRE

    Golob, Tina

    2014-01-01

    The last 160 years has been mostly used conventional track with ballasted bed, sleepers and steel rail. Ensuring the high speed rail traffic, increasing railway track capacities, providing comfortable and safe ride as well as high reliability and availability railway track, has led to development of innovative systems for railway track. The so-called slab track was first built in 1972 and since then, they have developed many different slab track systems around the world. Slab track was also b...

  6. Undercooling, nodule count and carbides in thin walled ductile cast iron

    DEFF Research Database (Denmark)

    Pedersen, Karl Martin; Tiedje, Niels Skat

    2008-01-01

    Ductile cast iron has been cast in plate thicknesses between 2 to 8 mm. The temperature has been measured during the solidification and the graphite nodule count and size distribution together with the type and amount of carbides have been analysed afterwards. Low nodule count gives higher...

  7. Evaluation of nano ceramic coating on radiographic defects of thin-walled AL4-4 aluminum alloy sand casting

    Directory of Open Access Journals (Sweden)

    Mansour Borouni

    2016-10-01

    Full Text Available Internal defects are among the problems in gravity casting of aluminum parts. The main internal volumetric defects are gas and shrinkage defects which form during solidification of the melt and drastically reduce the quality of the produced parts. These defects adversely affect the mechanical properties of thin walled castings parts. In this study, ceramic nanoparticles coatings were applied on the sand mold and the effect of mold coatings on the reduction of defects were investigated. X-ray radiography was used to detect defects in sand molds with ceramic nanoparticles coatings. For comparison, this test was performed on molds with micro-ceramic and graffiti coatings and uncoated sand mold. The results showed that the maximum amount of gas and shrinkage defects was observed in casting parts from AL4-1 alloy in uncoated molds. On the other hand, the minimum defects were found in molds coated with ceramic nanoparticles. It seems that the reduced defects in casting parts in molds coated with ceramic nanoparticles may be due to high thermal and chemical stability and higher heat transfer rate of the coating. These results can facilitate the production of high quality aluminum alloys parts using nanotechnology.

  8. Effect of the electron transport through thin slabs on the simulation of linear electron accelerators of use in therapy: A comparative study of various Monte Carlo codes

    Energy Technology Data Exchange (ETDEWEB)

    Vilches, M. [Servicio de Fisica y Proteccion Radiologica, Hospital Regional Universitario ' Virgen de las Nieves' , Avda. de las Fuerzas Armadas, 2, E-18014 Granada (Spain)], E-mail: mvilches@ugr.es; Garcia-Pareja, S. [Servicio de Radiofisica Hospitalaria, Hospital Regional Universitario ' Carlos Haya' , Avda. Carlos Haya, s/n, E-29010 Malaga (Spain); Guerrero, R. [Servicio de Radiofisica, Hospital Universitario ' San Cecilio' , Avda. Dr. Oloriz, 16, E-18012 Granada (Spain); Anguiano, M.; Lallena, A.M. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain)

    2007-09-21

    When a therapeutic electron linear accelerator is simulated using a Monte Carlo (MC) code, the tuning of the initial spectra and the renormalization of dose (e.g., to maximum axial dose) constitute a common practice. As a result, very similar depth dose curves are obtained for different MC codes. However, if renormalization is turned off, the results obtained with the various codes disagree noticeably. The aim of this work is to investigate in detail the reasons of this disagreement. We have found that the observed differences are due to non-negligible differences in the angular scattering of the electron beam in very thin slabs of dense material (primary foil) and thick slabs of very low density material (air). To gain insight, the effects of the angular scattering models considered in various MC codes on the dose distribution in a water phantom are discussed using very simple geometrical configurations for the LINAC. The MC codes PENELOPE 2003, PENELOPE 2005, GEANT4, GEANT3, EGSnrc and MCNPX have been used.

  9. Monte Carlo simulation of the electron transport through thin slabs: A comparative study of PENELOPE, GEANT3, GEANT4, EGSnrc and MCNPX

    International Nuclear Information System (INIS)

    Vilches, M.; Garcia-Pareja, S.; Guerrero, R.; Anguiano, M.; Lallena, A.M.

    2007-01-01

    The Monte Carlo simulation of the electron transport through thin slabs is studied with five general purpose codes: PENELOPE, GEANT3, GEANT4, EGSnrc and MCNPX. The different material foils analyzed in the old experiments of Kulchitsky and Latyshev [L.A. Kulchitsky, G.D. Latyshev, Phys. Rev. 61 (1942) 254] and Hanson et al. [A.O. Hanson, L.H. Lanzl, E.M. Lyman, M.B. Scott, Phys. Rev. 84 (1951) 634] are used to perform the comparison between the Monte Carlo codes. Non-negligible differences are observed in the angular distributions of the transmitted electrons obtained with the some of the codes. The experimental data are reasonably well described by EGSnrc, PENELOPE (v.2005) and GEANT4. A general good agreement is found for EGSnrc and PENELOPE (v.2005) in all the cases analyzed

  10. Monte Carlo simulation of the electron transport through thin slabs: A comparative study of PENELOPE, GEANT3, GEANT4, EGSnrc and MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Vilches, M. [Servicio de Fisica y Proteccion Radiologica, Hospital Regional Universitario ' Virgen de las Nieves' , Avda. de las Fuerzas Armadas, 2, E-18014 Granada (Spain)]. E-mail: mvilches@ugr.es; Garcia-Pareja, S. [Servicio de Radiofisica Hospitalaria, Hospital Regional Universitario ' Carlos Haya' , Avda. Carlos Haya, s/n, E-29010 Malaga (Spain)]. E-mail: garciapareja@gmail.com; Guerrero, R. [Servicio de Radiofisica, Hospital Universitario ' San Cecilio' , Avda. Dr. Oloriz, 16, E-18012 Granada (Spain)]. E-mail: rafael.guerrero.alcalde.sspa@juntadeandalucia.es; Anguiano, M. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain)]. E-mail: mangui@ugr.es; Lallena, A.M. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain)]. E-mail: lallena@ugr.es

    2007-01-15

    The Monte Carlo simulation of the electron transport through thin slabs is studied with five general purpose codes: PENELOPE, GEANT3, GEANT4, EGSnrc and MCNPX. The different material foils analyzed in the old experiments of Kulchitsky and Latyshev [L.A. Kulchitsky, G.D. Latyshev, Phys. Rev. 61 (1942) 254] and Hanson et al. [A.O. Hanson, L.H. Lanzl, E.M. Lyman, M.B. Scott, Phys. Rev. 84 (1951) 634] are used to perform the comparison between the Monte Carlo codes. Non-negligible differences are observed in the angular distributions of the transmitted electrons obtained with the some of the codes. The experimental data are reasonably well described by EGSnrc, PENELOPE (v.2005) and GEANT4. A general good agreement is found for EGSnrc and PENELOPE (v.2005) in all the cases analyzed.

  11. Low-Dose (2-mSv) CT in Adolescents and Young Adults With Suspected Appendicitis: Advantages of Additional Review of Thin Sections Using Multiplanar Sliding-Slab Averaging Technique.

    Science.gov (United States)

    Lee, Yoon Jin; Kim, Bohyoung; Ko, Yousun; Cho, Kyung Eun; Hong, Seong Sook; Kim, Dong Hwan; Song, Hyunjoo; Lee, Kyoung Ho

    2015-11-01

    The purpose of this study is to assess the advantages of additional multiplanar sliding-slab averaging review of 2-mm-thick (thin) sections over stack review of 5-mm-thick (thick) sections in difficult cases of 2-mSv CT in adolescents and young adults with suspected appendicitis. We included 149 patients (mean age, 28.0 years; 61 male patients and 88 female patients) for whom the initial CT reports were inconclusive for the diagnosis of appendicitis. Five independent radiologists retrospectively reviewed the thick sections in the stack mode and then the thin sections using sliding-slab averaging. In each review, they rated the likelihood of appendicitis and the appendix visualization using 5- and 3-point Likert scales, respectively. Diagnostic performance and confidence were compared between the two reviews using ROC analysis, McNemar tests, and Wilcoxon signed-rank tests. The pooled AUCs were 0.90 and 0.93 for the stack and sliding-slab averaging reviews, respectively (90% CI for the difference, 0.002-0.06; p = 0.087). For the individual readers, the sliding-slab averaging review tended to increase the AUC (range, 0.86-0.93 for stack vs 0.87-0.97 for sliding-slab averaging review), improve the confidence in diagnosing (mean score, 3.6-4.7 vs 3.9-4.7) or ruling out (1.6-2.1 vs 1.5-1.9) appendicitis, reduce indeterminate interpretations (0-15% vs 0-11%), and enhance the normal appendix visualization (1.1-1.7 vs 1.1-1.9), although the differences were not always statistically significant. Sliding-slab averaging review of thin sections is helpful when the diagnosis of appendicitis is difficult at 2-mSv CT in adolescents and young adults.

  12. The Control of Solidification Kinetics of the Vacuum-cast Thin-wall Nickel-based Superalloys by Changing the Geometrical Characteristics of the Ceramic Mold

    Directory of Open Access Journals (Sweden)

    Cygan R.

    2013-12-01

    Full Text Available This paper provides an analysis of experimental research and results of investment casting process. Temperature field in a ceramic mold is one of the problems during numerical simulation. Reducing the costs of production in precision casting involves the reduction of scraps, which is one of the fundamental problems of the foundry industry. Reducing these costs is associated with optimization of precision casting technology of aircraft engines critical parts, including control of the solidification front in thin-walled castings of nickel super alloys cast in a vacuum. It is achieved by changing the geometrical characteristics of the ceramic mold. The results of the tests were used to optimize the industrial production of aircraft components in Precision Foundry of WSK Rzeszów. Temperature distribution gained in the conducted tests allowed verification and optimization of computer simulations.

  13. A Physical Model to Study the Effects of Nozzle Design on Dispersed Two-Phase Flows in a Slab Mold Casting Ultra-Low-Carbon Steels

    Science.gov (United States)

    Salazar-Campoy, María M.; Morales, R. D.; Nájera-Bastida, A.; Calderón-Ramos, Ismael; Cedillo-Hernández, Valentín; Delgado-Pureco, J. C.

    2018-02-01

    The effects of nozzle design on dispersed, two-phase flows of the steel-argon system in a slab mold are studied using a water-air model with particle image velocimetry and ultrasound probe velocimetry techniques. Three nozzle designs were tested with the same bore size and different port geometries, including square (S), special bottom design with square ports (U), and circular (C). The meniscus velocities of the liquid increase two- or threefold in two-phase flows regarding one-phase flows using low flow rates of the gas phase. This effect is due to the dragging effects on bubbles by the liquid jets forming two-way coupled flows. Liquid velocities (primary phase) along the narrow face of the mold also are higher for two-phase flows. Flows using nozzle U are less dependent on the effects of the secondary phase (air). The smallest bubble sizes are obtained using nozzle U, which confirms that bubble breakup is dependent on the strain rates of the fluid and dissipation of kinetic energy in the nozzle bottom and port edges. Through dimensionless analysis, it was found that the bubble sizes are inversely proportional to the dissipation rate of the turbulent kinetic energy, ɛ 0.4. A simple expression involving ɛ, surface tension, and density of metal is derived to scale up bubble sizes in water to bubble sizes in steel with different degrees of deoxidation. The validity of water-air models to study steel-argon flows is discussed. Prior works related with experiments to model argon bubbling in steel slab molds under nonwetting conditions are critically reviewed.

  14. A Physical Model to Study the Effects of Nozzle Design on Dispersed Two-Phase Flows in a Slab Mold Casting Ultra-Low-Carbon Steels

    Science.gov (United States)

    Salazar-Campoy, María M.; Morales, R. D.; Nájera-Bastida, A.; Calderón-Ramos, Ismael; Cedillo-Hernández, Valentín; Delgado-Pureco, J. C.

    2018-04-01

    The effects of nozzle design on dispersed, two-phase flows of the steel-argon system in a slab mold are studied using a water-air model with particle image velocimetry and ultrasound probe velocimetry techniques. Three nozzle designs were tested with the same bore size and different port geometries, including square (S), special bottom design with square ports (U), and circular (C). The meniscus velocities of the liquid increase two- or threefold in two-phase flows regarding one-phase flows using low flow rates of the gas phase. This effect is due to the dragging effects on bubbles by the liquid jets forming two-way coupled flows. Liquid velocities (primary phase) along the narrow face of the mold also are higher for two-phase flows. Flows using nozzle U are less dependent on the effects of the secondary phase (air). The smallest bubble sizes are obtained using nozzle U, which confirms that bubble breakup is dependent on the strain rates of the fluid and dissipation of kinetic energy in the nozzle bottom and port edges. Through dimensionless analysis, it was found that the bubble sizes are inversely proportional to the dissipation rate of the turbulent kinetic energy, ɛ 0.4. A simple expression involving ɛ, surface tension, and density of metal is derived to scale up bubble sizes in water to bubble sizes in steel with different degrees of deoxidation. The validity of water-air models to study steel-argon flows is discussed. Prior works related with experiments to model argon bubbling in steel slab molds under nonwetting conditions are critically reviewed.

  15. Twin-belt continuous caster with containment and cooling of the exiting cast product for enabling high-speed casting of molten-center product

    Science.gov (United States)

    Dykes, Charles D.; Daniel, Sabah S.; Wood, J. F. Barry

    1990-02-20

    In continuously casting molten metal into cast product by a twin-belt machine, it is desirable to achieve dramatic increases in speed (linear feet per minute) at which cast product exits the machine, particularly in installations where steel cast product is intended to feed a downstream regular rolling mill (as distinct from a planetary mill) operating in tandem with the twin-belt caster. Such high-speed casting produces product with a relatively thin shell and molten interior, and the shell tends to bulge outwardly due to metallostatic head pressure of the molten center. A number of cooperative features enable high-speed, twin-belt casting: (1) Each casting belt is slidably supported adjacent to the caster exit pulley for bulge control and enhanced cooling of cast product. (2) Lateral skew steering of each belt provides an effective increase in moving mold length plus a continuity of heat transfer not obtained with prior art belt steering apparatus. (3) The exiting slab is contained and supported downstream from the casting machine to prevent bulging of the shell of the cast product, and (4) spray cooling is incorporated in the exit containment apparatus for secondary cooling of cast product.

  16. Periodicity effects on compound waves guided by a thin metal slab sandwiched between two periodically nonhomogeneous dielectric materials

    Science.gov (United States)

    Chiadini, Francesco; Fiumara, Vincenzo; Scaglione, Antonio; Lakhtakia, Akhlesh

    2017-10-01

    Surface-plasmon-polariton waves can be compounded when a sufficiently thin metal layer is sandwiched between two half spaces filled with dissimilar periodically nonhomogeneous dielectric materials. We solved the boundary-value problem for compound waves guided by a layer of a homogeneous and isotropic metal sandwiched between a structurally chiral material (SCM) and a periodically multilayered isotropic dielectric (PMLID) material. We found that the periodicities of the PMLID material and the SCM are crucial to excite a multiplicity of compound guided waves arising from strong coupling between the two interfaces.

  17. Hair casts

    OpenAIRE

    Sweta S Parmar; Kirti S Parmar; Bela J Shah

    2014-01-01

    Hair casts or pseudonits are circumferential concretions, which cover the hair shaft in such a way that, it could be easily removed. They are thin, cylindrical, and elongated in length. We present an unusual case of an 8-year-old girl presenting with hair casts. Occurrence of these is unusual, and they may have varied associations. This patient was suffering from developmental delay. It is commonly misdiagnosed as and very important to differentiate from pediculosis capitis.

  18. Triple Plate Mold Final Report: Optimization of the Mold Design and Casting Parameters for a Thin U-10mo Fuel Casting

    Energy Technology Data Exchange (ETDEWEB)

    Aikin, Jr., Robert M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-04

    This work describes the experiments and modeling that have been performed to improve and try to optimize the simultaneous casting of three plates of U-10wt%Mo in a single coil vacuum induction melting (VIM) furnace. The plates of interest are 280 mm wide by 203 mm tall by 5 mm thick (11" x 8" x 0.2"). The initial mold design and processing parameters were supplied by Y-12. The mold and casting cavity were instrumented with a number of thermocouples, and the casting performed to determine the thermal history of the mold and casting. The resulting cast plates were radiographed and numerous defects identified. Metallography was performed to help identify the nature of the radiographically observed defects. This information was then used to validate a mold filling and solidification model of that casting. Based on the initial casting, good casting design practice, and process simulation of several design alternatives, a revised design was developed with the goal of minimizing casting defects such as porosity. The redesigned mold had a larger hot-top and had its long axis along the horizontal direction. These changes were to try to develop a strong thermal gradient conducive to good feeding and minimization of micro- and macroporosity in the cast plates. An instrumented casting was then performed with the revised mold design and a linear distributor. This design yielded cast plates with significantly less radiographically identified defects. Unfortunately, there was significant variation in plate weight and metal content in their hot-tops. Fluid flow simulations were then performed on this mold/distributor design. This helped identify the issue with this linear distributor design. Additional simulations were then performed on candidate distributor redesigns and a preferred distributor annular design was identified. This improved annular design was used to produce a third instrumented casting with favorable results. These refined designs and their radiographic

  19. Energy-Saving Melting and Revert Reduction Technology (E-SMARRT): Lost Foam Thin Wall - Feasibility of Producing Lost Foam Castings in Aluminum and Magnesium Based Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fasoyinu, Yemi [CanmetMATERIALS; Griffin, John A. [University of Alabama - Birmingham

    2014-03-31

    With the increased emphasis on vehicle weight reduction, production of near-net shape components by lost foam casting will make significant inroad into the next-generation of engineering component designs. The lost foam casting process is a cost effective method for producing complex castings using an expandable polystyrene pattern and un-bonded sand. The use of un-bonded molding media in the lost foam process will impose less constraint on the solidifying casting, making hot tearing less prevalent. This is especially true in Al-Mg and Al-Cu alloy systems that are prone to hot tearing when poured in rigid molds partially due to their long freezing range. Some of the unique advantages of using the lost foam casting process are closer dimensional tolerance, higher casting yield, and the elimination of sand cores and binders. Most of the aluminum alloys poured using the lost foam process are based on the Al-Si system. Very limited research work has been performed with Al-Mg and Al-Cu type alloys. With the increased emphasis on vehicle weight reduction, and given the high-strength-to-weight-ratio of magnesium, significant weight savings can be achieved by casting thin-wall (≤ 3 mm) engineering components from both aluminum- and magnesium-base alloys.

  20. Machinability of clean thin-wall gray and ductile iron castings. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Bates, C.E.; Littleton, H.E.; Eleftheriou, E.; Griffin, R.D.; Dwyer, Z.B.; DelSorbo, C.; Sprague, J.

    1997-02-01

    First phase was to develop a laboratory technique for evaluating the machinability of gray and ductile iron; longer term goal is to learn how to modify the foundry process to produce castings meeting all specified mechanical properties while providing improved machining behavior. Microcarbides present in the irons were found to dominate the machinability of iron. Pearlitic irons with acceptable machinability contain 8.9 to 10.5 wt% microcarbides. The weight fraction microcarbides in the iron is influenced by carbide forming element concentrations, presence of elements that retard carbon diffusion, and cooling rate from the eutectic through the eutectoid temperature range. Tool wear rate increased at higher surface machining speeds and fraction microcarbides; all irons containing above 11.5% microcarbides had poor machinability. Graphite size, shape, distribution, etc. had a lesser effect on machinability. Reducing the addition of a foundry grade Ca and Al bearing 75% FeSi inoculant from 0.5 to 0.2% increased the tool life 100%. Inoculation test castings were also poured in a class 40 gray iron; laboratory analysis is currently underway. Exploratory studies were conducted to determine if tool force could be used to predict tool life: torque and feed forces were found to correlate with machinability.

  1. Analysis of Heat-and-Mass Transfer Conjugated Problem Solution while Forming Thin-Wall Castings

    Directory of Open Access Journals (Sweden)

    R. I. Еsman

    2009-01-01

    Full Text Available The paper contains an analysis of heat-and-mass transfer conjugated problem in case of moving of liquid melts in channels of metallic forms (moulds, dies, crystallizers etc.. Investigations of velocity profiles at various flow sections, current lines in the calculated area, pressure and viscosity fields in non-stationary state have been carried out in the paper.The paper reveals that current is of parabolic shape in the annular channel at rather large distance from a projection up and down the flow and pressure along channel section is practically unchangeable.The executed investigations of heat-and-mass transfer in the moving melt make it possible to create a data base of control parameters for development of prospective technologies  of special casting methods. 

  2. A scanning Kelvin probe study of charge trapping in zone-cast pentacene thin film transistors

    International Nuclear Information System (INIS)

    Hallam, T; Duffy, C M; Ando, M; Sirringhaus, H; Minakata, T

    2009-01-01

    We have used scanning Kelvin probe microscopy (SKPM) as a local probe to study charge trapping in zone-cast pentacene field effect transistors on both SiO 2 and benzocyclobutene (BCB) substrates. Annealing at 130 deg. C was found to reduce the threshold voltage, susceptibility to negative gate bias stress and trapping of positive charges within single pentacene grains. We conclude that oxygen is able to penetrate and disassociatively incorporate into crystalline pentacene, chemically creating electrically active defect states. Screening of a positive gate bias caused by electron injection from Au into pentacene was directly observed with SKPM. The rate of screening was found to change significantly after annealing of the film and depended on the choice of gate dielectric.

  3. Slab reformer

    Science.gov (United States)

    Spurrier, Francis R. (Inventor); DeZubay, Egon A. (Inventor); Murray, Alexander P. (Inventor); Vidt, Edward J. (Inventor)

    1985-01-01

    Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot combustion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

  4. Slab reformer

    Science.gov (United States)

    Spurrier, Francis R.; DeZubay, Egon A.; Murray, Alexander P.; Vidt, Edward J.

    1984-02-07

    Slab-shaped high efficiency catalytic reformer configurations particularly useful for generation of fuels to be used in fuel cell based generation systems. A plurality of structures forming a generally rectangular peripheral envelope are spaced about one another to form annular regions, an interior annular region containing a catalytic bed and being regeneratively heated on one side by a hot comubstion gas and on the other side by the gaseous products of the reformation. An integrally mounted combustor is cooled by impingement of incoming oxidant.

  5. Iron Melt Flow in Thin Walled Sections Cast in Vertically Parted Green Sand Moulds

    DEFF Research Database (Denmark)

    Larsen, Per; Andersen, Uffa; Rasmussen, Niels

    consumption and pollution of passenger cars, trucks etc. The engine design can be optimized for higher efficiency, the wind resistance can be reduced, combinations of combustion engines and electrical power can be used etc. But no matter which approach is taken, parts have to be used for building the vehicles...... will be initiated by the hammer effect when the melt reaches the dead end of the runner. Pressure shock waves can also be initiated when the last air pocket in a partly filled runner is closed. The pressure shock waves result in disintegrating melt surfaces. Flow in thin walled sections is not only important when...

  6. Surface termination dependent atomic relaxation of RT5 ultra-thin slabs (R = Y, Ce, Sm and T = Fe, Co, Ni) and their electronic and magnetic properties

    Science.gov (United States)

    Chandrasekaran, S. Selva; Murugan, P.; Saravanan, P.

    2017-10-01

    Investigations on two different surface terminated (0001) slabs of RT5 (R = Y, Ce, Sm and T = Fe, Co, Ni) compounds are performed by first principles calculations, in order to compare their structural stability, magnetic, and electronic properties. In bulk RT5 compounds, atomic sub-layers - RT2 (R-rich) and T3 (T-rich) - are alternatively stacked along z-axis. Therefore, two different RT5 (0001) slabs are constructed with terminating R-rich and T-rich sub-layers at both top and bottom of surfaces. Our calculations show that T-rich slabs are having higher structural stability owing to charge smoothing and inward relaxations of atoms at the surface, whereas R-atoms presented in the surface of slabs, particularly 4f elements experience outward relaxation as a consequence of corrugated surface charge density. The reason for inward and outward relaxations of respective atoms is quantitatively understood by the Bader charge analysis. Our results suggest that as the Co and Fe-rich surface slabs possess high structural stability and enhanced spin moment when compared to respective R-rich slabs, they can be potentially used for fabricating the multilayered exchange spring magnet.

  7. Research on cracking mechanism of the thin shell mould in expendable pattern shell casting during pattern removal process

    Directory of Open Access Journals (Sweden)

    Jiang Wenming

    2010-08-01

    Full Text Available Aiming at the cracking phenomenon of the thin shell mould in the expendable pattern shell casting during the pattern removing process, some systemic researches are presented. The influence of the pattern removing method and temperature on the pattern removing were investigated. The shell mould cracking mechanism was analyzed by using thermo-gravimetric analysis (TGA, and combining the temperature field and the volume change of the expanded polystyrene (EPS foam pattern being tested. The results indicated that the shell mould was not easily cracked when the pattern removing process was carried out with the furnace being heated little by little because of the shell slowly shrinking with dehydration and shell strength gradually increasing. The shell mould was soon destroyed when it was set directly into the furnace at above 400 ℃ because of the thin shell mould rapidly shrinking and the foam pattern hindering. However, the shell mould had no cracking when it had been preheated for a long time even if the furnace temperature was above 400 篊 and the shell was put into the furnace directly. Moreover, when the shell mould was directly set into the furnace at lower temperatures, 250 to 300 ℃, the shell would shrink slowly and the foam pattern would stay at the maximum expansion stage temperature of 100 to 110 ℃ for a long time; and the shell mould would experience an expansion force from the foam pattern for a long time. The expansion force is related to the pattern removing temperature, holding time, foam pattern thickness and density. Therefore, the foam pattern with higher density could make the shell crack.

  8. Precast alternative for flat slab bridges : final report.

    Science.gov (United States)

    2013-10-26

    The cast-in-place (CIP) concrete slab bridge and the hollow core flat slab bridge are two very common bridge types utilized by the : South Carolina Department of Transportation (SCDOT). The CIP bridge is durable but has a long construction time while...

  9. Microstructural evolution in warm-rolled and cold-rolled strip cast 6.5 wt% Si steel thin sheets and its influence on magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xianglong, E-mail: 215454278@qq.com; Liu, Zhenyu, E-mail: zyliu@mail.neu.edu.cn; Li, Haoze; Wang, Guodong

    2017-07-01

    Highlights: • The experimental materials used in the study are based on strip casting. • Magnetic properties between warm rolled and cold rolled sheets are investigated. • Cold rolled 6.5% Si sheet has better magnetic properties than warm rolled sheet. • The γ and λ-fiber recrystallization textures can be optimized after cold rolling. • Cold rolling should be more suitable for fabricating 6.5% Si steel thin sheets. - Abstract: 6.5 wt% Si steel thin sheets were usually fabricated by warm rolling. In our previous work, 6.5 wt% Si steel thin sheets with good magnetic properties had been successfully fabricated by cold rolling based on strip casting. In the present work, the main purposes were to find out the influences of warm rolling and cold rolling on microstructures and magnetic properties of the thin sheets with the thickness of 0.2 mm, and to confirm which rolling method was more suitable for fabricating 6.5 wt% Si steel thin sheets. The results showed that the cold rolled sheet could obtain good surface quality and flatness, while the warm rolled sheet could not. The intensity of γ-fiber rolling texture (<1 1 1>//ND) of cold rolled specimen was weaker than that of the warm rolled specimen, especially for the {1 1 1}<1 1 2> component at surface layer and {1 1 1}<1 1 0> component at center layer. After the same annealing treatment, the cold rolled specimen, which had higher stored energy and weaker intensity of γ-fiber rolling texture, could obtain smaller recrystallization grain size, weaker intensity of γ-fiber recrystallization texture and stronger intensity of λ-fiber recrystallization texture. Therefore, due to the good surface quality, smaller recrystallization grain size and optimum recrystallization texture, the cold rolled specimen possessed improved magnetic properties, and cold rolling should be more suitable for fabricating 6.5 wt% Si steel thin sheets.

  10. LIGHTWEIGHT SLAB CAST OVER PRECAST JOISTS

    Directory of Open Access Journals (Sweden)

    Koyankin Aleksandr Aleksandrovich

    2017-07-01

    Full Text Available Precast-monolithic house-building in domestic and world practice is a significant part in the mass construction. We propose a relatively large number of designs of precast-monolithic buildings, as well as its individual elements. Despite this, we cannot say that found the most effective constructive solutions able to satisfy the requirements of consumers (future residents and builders. On this basis, we developed quite effective, from the point of view of construction and further operation, a constructive solution of light weight precast-monolithic overlap. Some features offered are overlapping: smaller mass, compared with beams of heavy concrete; increased heat and sound insulation properties; optimal use of the structural properties of heavy and light precast monolithic concrete and longitudinal reinforcement, depending on the stage of construction. The author has carried out in this article the results of numerical studies the proposed design of precast-monolithic overlap, confirming its compliance with the requirements of 1st and 2nd group of limit States.

  11. Heavy vehicle simulator testing on pre-cast concrete panels

    CSIR Research Space (South Africa)

    Du Plessis, L

    2007-07-01

    Full Text Available commonly found in California, pre-cast concrete slabs are considered to be a very suitable repair material for extending the service life of intermittently distressed concrete pavements. This is because of the long life expectancy of concrete slabs cast...

  12. LOST FOAM CASTING OF MAGNESIUM ALLOYS

    Energy Technology Data Exchange (ETDEWEB)

    Han, Qingyou [ORNL; Dinwiddie, Ralph Barton [ORNL; Sklad, Philip S [ORNL; Currie, Kenneth [Tennessee Technological University; Abdelrahman, Mohamed [Tennessee Technological University; Vondra, Fred [Tennessee Technological University; Walford, Graham [Walford Technologies; Nolan, Dennis J [Foseco-Morval

    2007-01-01

    The lost foam casting process has been successfully used for making aluminum and cast iron thin walled castings of complex geometries. Little work has been carried out on cast magnesium alloys using the lost foam process. The article describes the research activities at Oak Ridge National Laboratory and Tennessee Technological University on lost foam casting of magnesium alloys. The work was focused on castings of simple geometries such as plate castings and window castings. The plate castings were designed to investigate the mold filling characteristics of magnesium and aluminum alloys using an infrared camera. The pate castings were then characterized for porosity distribution. The window castings were made to test the castability of the alloys under lost foam conditions. Significant differences between lost foam aluminum casting and lost foam magnesium casting have been observed.

  13. Microstructure and texture evolution of ultra-thin grain-oriented silicon steel sheet fabricated using strip casting and three-stage cold rolling method

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hong-Yu; Liu, Hai-Tao, E-mail: liuht@ral.neu.edu.cn; Wang, Yin-Ping; Wang, Guo-Dong

    2017-03-15

    A 0.1 mm-thick grain-oriented silicon steel sheet was successfully produced using strip casting and three-stage cold rolling method. The microstructure, texture and inhibitor evolution during the processing was briefly analyzed. It was found that Goss texture was absent in the hot rolled sheet because of the lack of shear deformation. After normalizing, a large number of dispersed MnS precipitates with the size range of 15–90 nm were produced. During first cold rolling, dense shear bands were generated in the deformed ferrite grains, resulting in the intense Goss texture after first intermediate annealing. The microstructure was further refined and homogenized during the subsequent cold rolling and annealing processes. After primary recrystallization annealing, a homogeneous microstructure consisting of fine and equiaxed grains was produced while the associated texture was characterized by a strong γ-fiber texture. Finally, a complete secondary recrystallization microstructure consisting of entirely large Goss grains was produced. The magnetic induction B{sub 8} and iron loss P{sub 10/400} was 1.79 T and 6.9 W/kg, respectively. - Highlights: • Ultra-thin grain-oriented silicon steel was produced by strip casting process. • Microstructure, texture and inhibitor evolution was briefly investigated. • Goss texture was absent in primary recrystallization annealed sheet. • MnS precipitates with a size range of 15–90 nm formed after normalizing. • A complete secondary recrystallization microstructure was produced.

  14. Mantle wedge serpentinization effects on slab dips

    Directory of Open Access Journals (Sweden)

    Eh Tan

    2017-01-01

    Full Text Available The mechanical coupling between a subducting slab and the overlying mantle wedge is an important factor in controlling the subduction dip angle and the flow in mantel wedge. This paper investigates the role of the amount of mantle serpentinization on the subduction zone evolution. With numerical thermos-mechanical models with elasto-visco-plastic rheology, we vary the thickness and depth extent of mantle serpentinization in the mantle wedge to control the degree of coupling between the slab and mantle wedge. A thin serpentinized mantle layer is required for stable subduction. For models with stable subduction, we find that the slab dip is affected by the down-dip extent and the mantle serpentinization thickness. A critical down-dip extent exists in mantle serpentinization, determined by the thickness of the overriding lithosphere. If the down-dip extent does not exceed the critical depth, the slab is partially coupled to the overriding lithosphere and has a constant dip angle regardless of the mantle serpentinization thickness. However, if the down-dip extent exceeds the critical depth, the slab and the base of the overriding lithosphere would be separated and decoupled by a thick layer of serpentinized peridotite. This allows further slab bending and results in steeper slab dip. Increasing mantle serpentinization thickness will also result in larger slab dip. We also find that with weak mantle wedge, there is no material flowing from the asthenosphere into the serpentinized mantle wedge. All of these results indicate that serpentinization is an important ingredient when studying the subduction dynamics in the mantle wedge.

  15. Performance evaluation of solid oxide fuel cells with thin film electrolyte fabricated by binder-assisted slurry casting

    Energy Technology Data Exchange (ETDEWEB)

    Guo, W.M.; Liu, X.M.; Li, L.J. [Department of Biological and Chemical Engineering, Guangxi University of Technology, Liuzhou 545006 (China); Xiao, Y.F. [Department of Stomatology, Liuzhou Maternity and Child Health Hospital, Liuzhou 545001 (China); Chen, Y. [School of Yingdong Life Science, Shaoguan University, Shaoguan 512005 (China)

    2011-10-15

    A gas-tight yttria-stabilized zirconia (YSZ) electrolyte film was fabricated on porous NiO-YSZ anode substrates by a binder-assisted slurry casting technique. The scanning electron microscope (SEM) results showed that the YSZ film was relatively dense with a thickness of 10 {mu}m. La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSM)-YSZ was applied to cathode using a screen-print technique and the single fuel cells were tested in a temperature range from 600 to 800 C. An open circuit voltage (OCV) of over 1.0 V was observed. The maximum power densities at 600, 700, and 800 C were 0.13, 0.44, and 1.1 W cm{sup -2}, respectively. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Ultra-thin grain-oriented silicon steel sheet fabricated by a novel way: Twin-roll strip casting and two-stage cold rolling

    Science.gov (United States)

    Wang, Yin-Ping; Liu, Hai-Tao; Song, Hong-Yu; Liu, Jia-Xin; Shen, Hui-Ying; Jin, Yang; Wang, Guo-Dong

    2018-04-01

    0.05-0.15 mm-thick ultra-thin grain-oriented silicon steel sheets were successfully produced by a novel processing route including strip casting, hot rolling, normalizing, two-stage cold rolling with intermediate annealing, primary recrystallization annealing and secondary recrystallization annealing. The evolutions of microstructure, texture and inhibitor along the processing were briefly investigated. The results showed that the initial Goss orientation originated due to the heterogenous nucleation of δ-ferrite grains during solidification. Because of the lack of shear deformation, only a few Goss grains were observed in the hot rolled sheet. After the first cold rolling and intermediate annealing, Goss texture was enhanced and distributed in the whole thickness. A small number of Goss grains having a high fraction of high energy boundaries exhibited in the primary recrystallization annealed sheet. A large number of fine and dispersed MnS and AlN and a few co-precipitates MnS and AlN with the size range of 10-70 nm were also observed. Interestingly, a well-developed secondary recrystallization microstructure characterized by 10-60 mm grains and a sharp Goss texture were finally produced in the 0.05-0.15 mm-thick ultra-thin sheets. A magnetic induction B8 of 1.72-1.84 T was obtained. Another new finding was that a few {2 3 0}〈0 0 1〉 and {2 1 0}〈1 2 7〉 grains also can grow up abnormally because of the high fraction of high energy boundaries and the size and number advantage, respectively. These non-Goss grains finally deteriorated the magnetic properties of the ultra-thin sheets. In addition, low surface energies of {hk0} planes may also contribute to the abnormal growth of Goss, {2 3 0}〈0 0 1〉 and {2 1 0}〈1 2 7〉 grains.

  17. Alternate approach slab reinforcement.

    Science.gov (United States)

    2010-06-01

    The upper mat of reinforcing steel, in exposed concrete bridge approach slabs, is prone to corrosion damage. Chlorides applied to the highways : for winter maintenance can penetrate this concrete layer. Eventually chlorides reach the steel and begin ...

  18. Slab replacement maturity guidelines.

    Science.gov (United States)

    2014-04-01

    This study investigated the use of maturity method to determine early age strength of concrete in slab : replacement application. Specific objectives were (1) to evaluate effects of various factors on the compressive : maturity-strength relationship ...

  19. A dynamic control water distribution model of steel in continuous casting

    International Nuclear Information System (INIS)

    Fu Jianxun; Hwang, Weng-Sing; Tsai, De-Chang; Tsai, Ming Hsiu; Wang, Chien-Hsun

    2012-01-01

    After investigation in many continuous casting shop of steel, a dynamic water distribution model is proposed for flexible control on secondary cooling in continuous casting. In this model, the water cooling intensity is determined by the model casting speed instead of the real casting speed. When the casting speed is steady, the model casting speed is equal to the real casting speed. When the real casting speed is changing, the model casting speed according to calculating algorithm to adjust and approaches to the real one, but there is a time delay between them, so it can avoid the slab surface temperature fluctuated due to casting speed changes. The secondary cooling can be dynamically controlled by monitoring the model casting speed. The compare of the simulation results and the measured results reveals that the temperature field and thickness of slab shell in simulations agree very well with the real production situations.

  20. The gravitational field of an infinite flat slab

    International Nuclear Information System (INIS)

    Fulling, S A; Bouas, J D; Carter, H B

    2015-01-01

    We study Einstein's equations with a localized plane-symmetric source, with close attention to gauge freedom/fixing and to listing all physically distinct solutions. In the vacuum regions there are only two qualitatively different solutions, one curved and one flat; in addition, on each of the two sides there is a free parameter describing how the slab is embedded into the vacuum region. Surprisingly, for a generic slab source the solution must be curved on one side and flat on the other. We treat infinitely thin slabs in full detail and indicate how thick slabs can increase the variety of external geometry pairs. Positive energy density seems to force external geometries with curvature singularities at some distance from the slab; we speculate that such singularities occur in regions where the solution cannot be physically relevant anyway. (invited comment)

  1. Numerical simulation for mold-filling of thin-walled aluminum alloy castings in traveling magnetic field

    Directory of Open Access Journals (Sweden)

    Shiping WU

    2004-11-01

    Full Text Available The numeical simulation for mold-filling of thin-walled aluminum alloy castins in horizontal traveling magnetic field is performed. A force model of Al alloy melt in the traveling magnetic field is founded by analyzing traveling magnetic field carefully. Numerical model of Al alloy mold-filling is founded based on N-S equation, which was suitable for traveling magnetic field. By using acryl glass mold with indium as alloy melt, the experiment testiied the filling state of alloy in traveling magnetic field. The results of numerical simulation indicate that the mold-filling ability of gallium melt increases continually with the incease of the input ampere turns.

  2. Manipulation of enhanced absorption with tilted hexagonal boron nitride slabs

    Science.gov (United States)

    Wu, Xiaohu; Fu, Ceji

    2018-04-01

    The wavevector of electromagnetic wave propagation in a hexagonal boron nitride (hBN) slab can be controlled by tilting its optical axis. This property can be used to manipulate the absorption in a hBN slab. By carefully analyzing the dependence of the absorptivity of a thin hBN slab on the tilted angle of its optical axis, we propose a structure that can realize great absorptivity enhancement in a band by stacking hBN slabs of different tilted angles. Our numerical results show that the absorptivity of a structure made of 91 stacked hBN slabs can be achieved higher than 0.94 in the wavenumber range from 1367 to 1580 cm-1 when the tilted angles of the slabs are properly arranged. The strong absorption is attributed to the combination of impedance matching at the slab interfaces and enlarged wavevectors in the slabs. This work reveals a novel way to realize strong absorption with anisotropic materials for applications in areas such as thermal radiative energy harvesting and conversion.

  3. Slab Leaf Bowls

    Science.gov (United States)

    Suitor, Cheryl

    2012-01-01

    In science class, fourth graders investigate the structure of plants and leaves from trees and how the process of photosynthesis turns sunlight into sugar proteins. In this article, the author fuses art and science for a creative and successful clay slab project in her elementary art classroom. (Contains 1 online resource.)

  4. Reliability of Plastic Slabs

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    1989-01-01

    In the paper it is shown how upper and lower bounds for the reliability of plastic slabs can be determined. For the fundamental case it is shown that optimal bounds of a deterministic and a stochastic analysis are obtained on the basis of the same failure mechanisms and the same stress fields....

  5. Experimental and finite element study of ultimate strength of continuous composite concrete slabs with steel decking

    Science.gov (United States)

    Gholamhoseini, Alireza

    2018-02-01

    Composite one-way concrete slabs with profiled steel decking as permanent formwork are commonly used in the construction industry. The steel decking supports the wet concrete of a cast in situ reinforced or post-tensioned concrete slab and, after the concrete sets, acts as external reinforcement. In this type of slab, longitudinal shear failure between the concrete and the steel decking is the most common type of failure at the ultimate load stage. Design codes require the experimental evaluation of the ultimate load capacity and longitudinal shear strength of each type of steel decking using full-scale tests on simple-span slabs. There is also no procedure in current design codes to evaluate the ultimate load capacity and longitudinal shear strength of continuous composite slabs and this is often assessed experimentally by full-scale tests. This paper presents the results of three full-scale tests up to failure on continuous composite concrete slabs cast with trapezoidal steel decking profile (KF70) that is widely used in Australia. Slab specimens were tested in four-point bending at each span with shear spans of span/4. The longitudinal shear failure of each slab is evaluated and the measured mid-span deflection, the end slip and the mid-span steel and concrete strains are also presented and discussed. Redistribution of bending moment in each slab is presented and discussed. A finite element model is proposed and verified by experimental data using interface element to model the bond properties between steel decking and concrete slab and investigate the ultimate strength of continuous composite concrete slabs.

  6. Experimental and finite element study of ultimate strength of continuous composite concrete slabs with steel decking

    Science.gov (United States)

    Gholamhoseini, Alireza

    2018-03-01

    Composite one-way concrete slabs with profiled steel decking as permanent formwork are commonly used in the construction industry. The steel decking supports the wet concrete of a cast in situ reinforced or post-tensioned concrete slab and, after the concrete sets, acts as external reinforcement. In this type of slab, longitudinal shear failure between the concrete and the steel decking is the most common type of failure at the ultimate load stage. Design codes require the experimental evaluation of the ultimate load capacity and longitudinal shear strength of each type of steel decking using full-scale tests on simple-span slabs. There is also no procedure in current design codes to evaluate the ultimate load capacity and longitudinal shear strength of continuous composite slabs and this is often assessed experimentally by full-scale tests. This paper presents the results of three full-scale tests up to failure on continuous composite concrete slabs cast with trapezoidal steel decking profile (KF70) that is widely used in Australia. Slab specimens were tested in four-point bending at each span with shear spans of span/4. The longitudinal shear failure of each slab is evaluated and the measured mid-span deflection, the end slip and the mid-span steel and concrete strains are also presented and discussed. Redistribution of bending moment in each slab is presented and discussed. A finite element model is proposed and verified by experimental data using interface element to model the bond properties between steel decking and concrete slab and investigate the ultimate strength of continuous composite concrete slabs.

  7. Microstructure Examinations in Corners of the Low-Carbon Steel Slabs from Continuos Caster Machine

    Directory of Open Access Journals (Sweden)

    Kwinta G.

    2016-12-01

    Full Text Available The exposed selvedge layers in slabs cast by the continuous process should be free from surface defects, which in most cases appear in the form of cracks on the casting surface and run to its interior. In addition to the parameters of the casting process, the occurrence of such defects depends on the chemical composition of cast steel, on the segregation of surface active elements and formation of the precipitates of carbides, nitrides and other phases. Due to the frequent occurrence of defects in corners of the slabs, non-destructive testing was performed on the mechanically cleaned surfaces of slabs. The test material was low-carbon API(American Petroleum Institute API 5L standard steel micro alloyed with Nb and Ti designed for the production of pipes to handle gas, oil and other liquid and gaseous fuels. Despite the use of different methods of inspection, i.e. ultrasonic, magnetic particle and penetrant, cracks were not traced in the examined material. Then, from the corners of the examined slabs, specimens were cut out for metallographic examinations. The main purpose of these examinations was to disclose the presence of possible cracks and micro cracks on the surfaces transversal and longitudinal to the direction of casting. At the same time, studies were conducted to establish the number and morphology of non-metallic inclusions in selvedge layers of the slab corners and axis. Additionally, hardness of the slabs was measured. The conducted studies revealed only some minor differences in the slab hardness along its axis (130 ÷ 135 HB and in selvedge layers (120 ÷ 123 HB.

  8. Evanescent field phase shifting in a silicon nitride waveguide using a coupled silicon slab

    DEFF Research Database (Denmark)

    Jensen, Asger Sellerup; Oxenløwe, Leif Katsuo; Green, William M. J.

    2015-01-01

    An approach for electrical modulation of low-loss silicon nitride waveguides is proposed, using a silicon nitride waveguide evanescently loaded with a thin silicon slab. The thermooptic phase-shift characteristics are investigated in a racetrack resonator configuration....

  9. Flexural Strengthening of RC Slabs Using a Hybrid FRP-UHPC System Including Shear Connector

    Directory of Open Access Journals (Sweden)

    Jiho Moon

    2017-01-01

    Full Text Available A polymeric hybrid composite system made of UHPC and CFRP was proposed as a retrofit system to enhance flexural strength and ductility of RC slabs. While the effectiveness of the proposed system was confirmed previously through testing three full-scale one-way slabs having two continuous spans, the slabs retrofitted with the hybrid system failed in shear. This sudden shear failure would stem from the excessive enhancement of the flexural strength over the shear strength. In this study, shear connectors were installed between the hybrid system and a RC slab. Using simple beam, only positive moment section was examined. Two full-scale RC slabs were cast and tested to failure: the first as a control and the second using this new strengthening technique. The proposed strengthening system increased the ultimate load carrying capacity of the slab by 70%, the stiffness by 60%, and toughness by 128%. The efficiency of shear connectors on ductile behavior of the retrofitted slab was also confirmed. After the UHPC top is separated from the slab, the shear connector transfer shear load and the slab system were in force equilibrium by compression in UHPC and tension in CFRP.

  10. Caste System

    OpenAIRE

    Hoff, Karla

    2016-01-01

    In standard economics, individuals are rational actors and economic forces undermine institutions that impose large inefficiencies. The persistence of the caste system is evidence of the need for psychologically more realistic models of decision-making in economics. The caste system divides South Asian society into hereditary groups whose lowest ranks are represented as innately polluted. ...

  11. Effect of rheological approximations on slab detachment in 3D numerical simulations of continental collision

    Science.gov (United States)

    Pusok, Adina E.; Kaus, Boris; Popov, Anton

    2017-04-01

    It is commonly accepted that slab detachment results from the development of extensional stresses within the subducting slab. Subduction slowdown due to arrival of buoyant continental material at the trench is considered to cause such stress build up in the slab. Following slab detachment, slab pull partially or completely loses its strength and hot asthenosphere may flow through the slab window, which can have major consequences for continental collision. The dynamics of slab detachment has been extensively studied in 2D (i.e. analytical and numerical), but 3D models of slab detachment during continental collision remain largely unexplored. Some of the previous 3D models have investigated the role of an asymmetric margin on the propagation of slab detachment (van Hunen and Allen, 2011), the impact of slab detachment on the curvature of orogenic belts (Capitanio and Replumaz, 2013), the role of the collision rate on slab detachment depth (Li et al., 2013) or the effect of along-trench variations on slab detachment (Duretz et al., 2014). However, rheology of mantle and lithosphere is known to have a major influence on the dynamics of subduction. Here, we explore a range of different rheological approximations to understand their sensitivity on the possible scenarios. We employ the code LaMEM (Kaus et al., 2016) to perform 3D simulations of subduction/continental collision in an integrated lithospheric and upper-mantle scale model. The models exhibit a wide range of behaviours depending on the rheological law employed: from linear, to temperature-dependent visco-elasto-plastic rheology that takes into account both diffusion and dislocation creep. For example, we find that slab dynamics varies drastically between end member models: in viscous approximations, slab detachment is slow, dominated by viscous thinning, while for a non-linear visco-elasto-plastic rheology, slab detachment is relatively fast, dominated by plastic breaking and inducing strong mantle flow in

  12. Long-life slab replacement concrete.

    Science.gov (United States)

    2015-03-01

    This research was initiated following reports of high incidence of cracking on FDOT concrete pavement replacement : slab projects. Field slabs were instrumented for data acquisition from high-early-strength concrete pavement : replacement slabs place...

  13. SUB-SLAB PROBE INSTALLATION

    Science.gov (United States)

    Sub-slab sampling has become an integral part of vapor intrusion investigations. It is now recommended in guidance documents developed by EPA and most states. A method for sub-slab probe installation was devised in 2002, presented at conferences through 2005, and finally docume...

  14. Laseroptical speed measurement during continuous casting of steel

    Energy Technology Data Exchange (ETDEWEB)

    Schwenzfeier, W.; Kawa, F.

    1986-03-01

    The speed of a continuously cast strand can give important information about the casting process. In order to be able to properly observe the casting process over long periods, it is necessary to use reliable and sufficiently precise speed measuring systems. This report presents first experiences with contactless laser-optical measurement of the real strand speed during the casting of billets, blooms and slabs. For this purpose a newly conceived, especially durable measuring instrument, operating on the basis of the differential Doppler arrangement, was used successfully.

  15. Topological susceptibility from slabs

    Energy Technology Data Exchange (ETDEWEB)

    Bietenholz, Wolfgang [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, Distrito Federal, C.P. 04510 (Mexico); Forcrand, Philippe de [Institute for Theoretical Physics, ETH Zürich,CH-8093 Zürich (Switzerland); CERN, Physics Department, TH Unit, CH-1211 Geneva 23 (Switzerland); Gerber, Urs [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, Distrito Federal, C.P. 04510 (Mexico); Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo,Edificio C-3, Apdo. Postal 2-82, Morelia, Michoacán, C.P. 58040 (Mexico)

    2015-12-14

    In quantum field theories with topological sectors, a non-perturbative quantity of interest is the topological susceptibility χ{sub t}. In principle it seems straightforward to measure χ{sub t} by means of Monte Carlo simulations. However, for local update algorithms and fine lattice spacings, this tends to be difficult, since the Monte Carlo history rarely changes the topological sector. Here we test a method to measure χ{sub t} even if data from only one sector are available. It is based on the topological charges in sub-volumes, which we denote as slabs. Assuming a Gaussian distribution of these charges, this method enables the evaluation of χ{sub t}, as we demonstrate with numerical results for non-linear σ-models.

  16. Topological Susceptibility from Slabs

    CERN Document Server

    Bietenholz, Wolfgang; Gerber, Urs

    2015-01-01

    In quantum field theories with topological sectors, a non-perturbative quantity of interest is the topological susceptibility chi_t. In principle it seems straightforward to measure chi_t by means of Monte Carlo simulations. However, for local update algorithms and fine lattice spacings, this tends to be difficult, since the Monte Carlo history rarely changes the topological sector. Here we test a method to measure chi_t even if data from only one sector are available. It is based on the topological charges in sub-volumes, which we denote as slabs. Assuming a Gaussian distribution of these charges, this method enables the evaluation of chi_t, as we demonstrate with numerical results for non-linear sigma-models.

  17. Solidification and casting

    CERN Document Server

    Cantor, Brian

    2002-01-01

    INDUSTRIAL PERSPECTIVEDirect chillcasting of aluminium alloysContinuous casting of aluminium alloysContinuous casting of steelsCastings in the automotive industryCast aluminium-silicon piston alloysMODELLING AND SIMULATIONModelling direct chill castingMold filling simulation of die castingThe ten casting rulesGrain selection in single crystal superalloy castingsDefects in aluminium shape castingPattern formation during solidificationPeritectic solidificationSTRUCTURE AND DEFECTSHetergeneous nucleation in aluminium alloysCo

  18. Deceased Slabs Drive Oil

    Science.gov (United States)

    Stein, H. J.; Hannah, J. L.

    2017-12-01

    The application of Re-Os isotope geochemistry to dating single oils is a nascent field [1,2]. Challenges include dissection of oils into asphaltene-maltene (ASPH-MALT) components in a way that preserves meaningful chronologic and source information. Significantly, oil-water mixing rapidly transfers Os to the oil, while Re exchange is sluggish [3]. The Os initial ratio of the oil is shifted in the direction of Os carried in the aqueous fluid, whereas the Re-Os isotopic age is preserved. We show that this phenomenon is operative in natural systems. Further, we show that deserpentinization of old oceanic slabs [4], may be linked to expulsion of Os-enriched waters into overlying sedimentary sections - a process that may be of fundamental importance for oil generation. This conclusion does not diminish the role of traditional organic-rich shales as source rocks for the hydrocarbon, but shows that external fluids are essential to petroleum generation. Moreover, the external fluids may be an important driver for expulsion and migration of oils. We have taken apart several petroleum systems from source rock, to residual oil, to tar mat development, to in situ live oil, through to produced oil. In many cases, a fluid with low 187Os/188Os - unlike that of normal basinal brines - provides a critical component to the oil-water mixture. Funding - CHRONOS project supported by Norwegian petroleum industry (Eni-Norge, Lundin, Aker BP) Acknowledgement - Christine Fichler [4], who first queried us on old slabs and oil, and stimulated ideas. [1] Georgiev, S.V., Stein, H.J., Hannah, J.L., Galimberti, R., Nali, M., Yang, G., and Zimmerman, A. (2016) Re-Os dating of maltenes and asphaltenes within single samples of crude oil: Geochim. Cosmochim. Acta 179: 53-75. [doi.org/10.1016/j.gca.2016.01.016] [2] DiMarzio, J., Georgiev, S.V., Stein, H.J., and Hannah, J.L. (in press) Residency of rhenium and osmium in a heavy crude oil: Geochim. Cosmochim. Acta. [3] Hurtig, N.C., Georgiev, S

  19. Slab replacement maturity guidelines : [summary].

    Science.gov (United States)

    2014-04-01

    Concrete sets in hours at moderate temperatures, : but the bonds that make concrete strong continue : to mature over days to years. However, for : replacement concrete slabs on highways, it is : crucial that concrete develop enough strength : within ...

  20. New Packaging for Amplifier Slabs

    Energy Technology Data Exchange (ETDEWEB)

    Riley, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thorsness, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Suratwala, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Steele, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rogowski, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-03-18

    The following memo provides a discussion and detailed procedure for a new finished amplifier slab shipping and storage container. The new package is designed to maintain an environment of <5% RH to minimize weathering.

  1. Structure Distribution in Precise Cast Iron Moulded on Meltable Model

    Directory of Open Access Journals (Sweden)

    Skrbek B.

    2015-12-01

    Full Text Available Topic of this work is to compare metalurgy of cast irons poured into sand moulds and into shell molds at IEG Jihlava company and from it following differencies in structures of thin- and thick-walled castings. This work is dealing with investigation and experimental measurement on surfaces and sections suitable thin- and thick-walled investment castings at IEG Jihlava. Cast irons with flake graphite (grey cast iron and cast irons with spheroidal graphite (ductile cast iron. Both mechanical and physical properties are determined using calculations from as measured values of wall thicknesses L and Lu, Vickers hardness and remanent magnetism. Measurement results are discussed, findings are formulated and methods for castings metallurgical quality improvement are recommended finally.

  2. Strong Plate, Weak Slab Dichotomy

    Science.gov (United States)

    Petersen, R. I.; Stegman, D. R.; Tackley, P.

    2015-12-01

    Models of mantle convection on Earth produce styles of convection that are not observed on Earth.Moreover non-Earth-like modes, such as two-sided downwellings, are the de facto mode of convection in such models.To recreate Earth style subduction, i.e. one-sided asymmetric recycling of the lithosphere, proper treatment of the plates and plate interface are required. Previous work has identified several model features that promote subduction. A free surface or pseudo-free surface and a layer of material with a relatively low strength material (weak crust) allow downgoing plates to bend and slide past overriding without creating undue stress at the plate interface. (Crameri, et al. 2012, GRL)A low viscosity mantle wedge, possibly a result of slab dehydration, decouples the plates in the system. (Gerya et al. 2007, Geo)Plates must be composed of material which, in the case of the overriding plate, are is strong enough to resist bending stresses imposed by the subducting plate and yet, as in the case of the subducting plate, be weak enough to bend and subduct when pulled by the already subducted slab. (Petersen et al. 2015, PEPI) Though strong surface plates are required for subduction such plates may present a problem when they encounter the lower mantle.As the subducting slab approaches the higher viscosity, lower mantle stresses are imposed on the tip.Strong slabs transmit this stress to the surface.There the stress field at the plate interface is modified and potentially modifies the style of convection. In addition to modifying the stress at the plate interface, the strength of the slab affects the morphology of the slab at the base of the upper mantle. (Stegman, et al 2010, Tectonophysics)Slabs that maintain a sufficient portion of their strength after being bent require high stresses to unbend or otherwise change their shape.On the other hand slabs that are weakened though the bending process are more amenable to changes in morphology. We present the results of

  3. Analysis of the quality renovated continuous steel casting roller

    Indian Academy of Sciences (India)

    S¯adhan¯a Vol. 38, Part 3, June 2013, pp. 477–490. c Indian Academy of Sciences. Analysis of the quality renovated continuous steel casting roller. J VI ˇNÁŠ. ∗ ... Department of Technology and Materials, Faculty of Mechanical Engineering, .... Mentioned line is able to produce slabs with section of 190–250 mm × 960–.

  4. Thin Wall Austempered Ductile Iron (TWADI

    Directory of Open Access Journals (Sweden)

    M. Górny

    2009-07-01

    Full Text Available In this paper the analysis of thin walled castings made of ductile iron is considered. It is shown that thin wall austempered ductile iron can be obtained by means of short-term heat treatment of thin wall castings without addition of alloying elements. Metallographic examinations of 2 mm thin walled castings along with casting with thicker wall thickness (20x28 mm after different austempring conditions are presented. It has been proved that short-term heat treatment amounted 20 minutes of austenitizing at 880 oC followed by holding at 400 oC for 5 minutes causes ausferrite matrix in 2 mm wall thickness castings, while casting with thicker wall thickness remain untransformed and martensite is still present in a matrix. Finally there are shown that thin wall ductile iron is an excellent base material for austempering heat treatments. As a result high mechanical properties received in thin wall plates made of austempered ductile iron.

  5. Real-Time, Model-Based Spray-Cooling Control System for Steel Continuous Casting

    Science.gov (United States)

    Petrus, Bryan; Zheng, Kai; Zhou, X.; Thomas, Brian G.; Bentsman, Joseph

    2011-02-01

    This article presents a new system to control secondary cooling water sprays in continuous casting of thin steel slabs (CONONLINE). It uses real-time numerical simulation of heat transfer and solidification within the strand as a software sensor in place of unreliable temperature measurements. The one-dimensional finite-difference model, CON1D, is adapted to create the real-time predictor of the slab temperature and solidification state. During operation, the model is updated with data collected by the caster automation systems. A decentralized controller configuration based on a bank of proportional-integral controllers with antiwindup is developed to maintain the shell surface-temperature profile at a desired set point. A new method of set-point generation is proposed to account for measured mold heat flux variations. A user-friendly monitor visualizes the results and accepts set-point changes from the caster operator. Example simulations demonstrate how a significantly better shell surface-temperature control is achieved.

  6. MODOS GUIADOS EM SLABS METAMATERIAIS GUIDED MODES IN METAMATERIAL SLABS

    Directory of Open Access Journals (Sweden)

    Leonardo André Ambrosio

    2006-12-01

    Full Text Available Este trabalho apresenta um estudo de revisão de modos propagantes em um guia-de-onda slab constituído de materiais com índices de refração negativo, os chamados metamateriais, Mostra-se que os modos guiados em um slab metamaterial possuem algumas propriedades particulares, tais como a propagação de ondas lentas simétricas ou anti-simétricas, a ausência de modos fundamentais para ondas rápidas e a possibilidade de propagação de ondas guiadas em um meio menos denso. A análise é baseada em expansões de campo no guia e nos espaços superior e inferior ao mesmo.This paper presents a review of the propagation modes in a slab waveguide consisting of negative refraction index materials, known as metamaterials. Some particular properties of guided modes in a metamaterial slab, such as slow symmetric or antisymmetric slow wave propagation, the absence of fundamental modes for fast waves and the possibility of guided waves in a less dense medium. The analysis is based on field expansions in the guide and the upper and lower spaces of it.

  7. Fracture Mechanisms and Strengthening of Slab Lasers

    Science.gov (United States)

    Marion, John E.

    1987-04-01

    The fracture mechanisms of slab lasers are examined and the critical defects, induced during optical fabrication, are identified. A rationale for determining an appropriate operating stress for the slab laser is outlined, based on Weibull statistics, and this method is experimentally assessed in full-sized slab fracture tests. Techniques for achieving strong slabs are then examined. We determine that strengthening by subsurface damage minimization has the highest potential for strengthening, but that slab durability must also be enhanced in order for the slab to remain strong in practice. Good chemical durability is achieved by the use of water-proof overcoats. Good mechanical durability is achieved by the use of compressive surface layers. The compressive surface layers prevent the deterioration in slab strength from physical damage to the slab surface.

  8. Long-life slab replacement concrete : [summary].

    Science.gov (United States)

    2015-04-01

    Concrete slab replacement projects in Florida have demonstrated a high incidence of : replacement slab cracking. Causes of cracking have not been reliably determined. University of South Florida researchers : sought to identify the factors or : param...

  9. ARC Code TI: SLAB Spatial Audio Renderer

    Data.gov (United States)

    National Aeronautics and Space Administration — SLAB is a software-based, real-time virtual acoustic environment rendering system being developed as a tool for the study of spatial hearing. SLAB is designed to...

  10. Casting materials

    Science.gov (United States)

    Chaudhry, Anil R [Xenia, OH; Dzugan, Robert [Cincinnati, OH; Harrington, Richard M [Cincinnati, OH; Neece, Faurice D [Lyndurst, OH; Singh, Nipendra P [Pepper Pike, OH

    2011-06-14

    A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

  11. Transient slab flattening beneath Colombia

    Science.gov (United States)

    Wagner, L. S.; Jaramillo, J. S.; Ramírez-Hoyos, L. F.; Monsalve, G.; Cardona, A.; Becker, T. W.

    2017-07-01

    Subduction of the Nazca and Caribbean Plates beneath northwestern Colombia is seen in two distinct Wadati Benioff Zones, one associated with a flat slab to the north and one associated with normal subduction south of 5.5°N. The normal subduction region is characterized by an active arc, whereas the flat slab region has no known Holocene volcanism. We analyze volcanic patterns over the past 14 Ma to show that in the mid-Miocene a continuous arc extended up to 7°N, indicating normal subduction of the Nazca Plate all along Colombia's Pacific margin. However, by 6 Ma, we find a complete cessation of this arc north of 3°N, indicating the presence of a far more laterally extensive flat slab than at present. Volcanism did not resume between 3°N and 6°N until after 4 Ma, consistent with lateral tearing and resteepening of the southern portion of the Colombian flat slab at that time.

  12. Fabrication and characterization of subwavelength nanostructures on freestanding GaN slab.

    Science.gov (United States)

    Wang, Yongjin; Hu, Fangren; Kanamori, Yoshiaki; Sameshima, Hidehisa; Hane, Kazuhiro

    2010-02-01

    We develop a novel way to fabricate subwavelength nanostructures on the freestanding GaN slab using a GaN-on-silicon system by combining self-assemble technique and backside thinning method. Silicon substrate beneath the GaN slab is removed by bulk silicon micromachining, generating the freestanding GaN slab and eliminating silicon absorption of the emitted light. Fast atom beam (FAB) etching is conducted to thin the freestanding GaN slab from the backside, reducing the number of confined modes inside the GaN slab. With self-assembled silica nanospheres acting as an etching mask, subwavelength nanostructures are realized on the GaN surface by FAB etching. The reflection losses at the GaN interfaces are thus suppressed. When the InGaN/GaN multiple quantum wells (MQWs) active layers are excited, the light extraction efficiency is significantly improved for the freestanding nanostructured GaN slab. This work provides a very practical approach to fabricate freestanding nanostructures on the GaN-on-silicon system for further improving the light extraction efficiency.

  13. Method for Bubbledeck Concrete Slab with Gaps

    Directory of Open Access Journals (Sweden)

    Sergiu Călin

    2009-01-01

    Full Text Available The composite slabs are made of BubbleDeck type slab elements with spherical gaps, poured in place on transversal and longitudinal directions. By introducing the gaps leads to a 30...50\\% lighter slab which reduces the loads on the columns, walls and foundations, and of course of the entire building. BubbleDeck slab elements are plates with ribs on two directions made of reinforced concrete or precast concrete with spherical shaped bubbles. These slab elements have a bottom and an upper concrete part connected with vertical ribs that go around the gaps.

  14. Extraordinary wavelength reduction in terahertz graphene-cladded photonic crystal slabs

    Science.gov (United States)

    Williamson, Ian A. D.; Mousavi, S. Hossein; Wang, Zheng

    2016-01-01

    Photonic crystal slabs have been widely used in nanophotonics for light confinement, dispersion engineering, nonlinearity enhancement, and other unusual effects arising from their structural periodicity. Sub-micron device sizes and mode volumes are routine for silicon-based photonic crystal slabs, however spectrally they are limited to operate in the near infrared. Here, we show that two single-layer graphene sheets allow silicon photonic crystal slabs with submicron periodicity to operate in the terahertz regime, with an extreme 100× wavelength reduction from graphene’s large kinetic inductance. The atomically thin graphene further leads to excellent out-of-plane confinement, and consequently photonic-crystal-slab band structures that closely resemble those of ideal two-dimensional photonic crystals, with broad band gaps even when the slab thickness approaches zero. The overall photonic band structure not only scales with the graphene Fermi level, but more importantly scales to lower frequencies with reduced slab thickness. Just like ideal 2D photonic crystals, graphene-cladded photonic crystal slabs confine light along line defects, forming waveguides with the propagation lengths on the order of tens of lattice constants. The proposed structure opens up the possibility to dramatically reduce the size of terahertz photonic systems by orders of magnitude. PMID:27143314

  15. Extraordinary wavelength reduction in terahertz graphene-cladded photonic crystal slabs.

    Science.gov (United States)

    Williamson, Ian A D; Mousavi, S Hossein; Wang, Zheng

    2016-05-04

    Photonic crystal slabs have been widely used in nanophotonics for light confinement, dispersion engineering, nonlinearity enhancement, and other unusual effects arising from their structural periodicity. Sub-micron device sizes and mode volumes are routine for silicon-based photonic crystal slabs, however spectrally they are limited to operate in the near infrared. Here, we show that two single-layer graphene sheets allow silicon photonic crystal slabs with submicron periodicity to operate in the terahertz regime, with an extreme 100× wavelength reduction from graphene's large kinetic inductance. The atomically thin graphene further leads to excellent out-of-plane confinement, and consequently photonic-crystal-slab band structures that closely resemble those of ideal two-dimensional photonic crystals, with broad band gaps even when the slab thickness approaches zero. The overall photonic band structure not only scales with the graphene Fermi level, but more importantly scales to lower frequencies with reduced slab thickness. Just like ideal 2D photonic crystals, graphene-cladded photonic crystal slabs confine light along line defects, forming waveguides with the propagation lengths on the order of tens of lattice constants. The proposed structure opens up the possibility to dramatically reduce the size of terahertz photonic systems by orders of magnitude.

  16. High-quality slab-based intermixing method for fusion rendering of multiple medical objects.

    Science.gov (United States)

    Kim, Dong-Joon; Kim, Bohyoung; Lee, Jeongjin; Shin, Juneseuk; Kim, Kyoung Won; Shin, Yeong-Gil

    2016-01-01

    The visualization of multiple 3D objects has been increasingly required for recent applications in medical fields. Due to the heterogeneity in data representation or data configuration, it is difficult to efficiently render multiple medical objects in high quality. In this paper, we present a novel intermixing scheme for fusion rendering of multiple medical objects while preserving the real-time performance. First, we present an in-slab visibility interpolation method for the representation of subdivided slabs. Second, we introduce virtual zSlab, which extends an infinitely thin boundary (such as polygonal objects) into a slab with a finite thickness. Finally, based on virtual zSlab and in-slab visibility interpolation, we propose a slab-based visibility intermixing method with the newly proposed rendering pipeline. Experimental results demonstrate that the proposed method delivers more effective multiple-object renderings in terms of rendering quality, compared to conventional approaches. And proposed intermixing scheme provides high-quality intermixing results for the visualization of intersecting and overlapping surfaces by resolving aliasing and z-fighting problems. Moreover, two case studies are presented that apply the proposed method to the real clinical applications. These case studies manifest that the proposed method has the outstanding advantages of the rendering independency and reusability. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. Cast irons

    CERN Document Server

    1996-01-01

    Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...

  18. The ancient Chinese casting techniques

    OpenAIRE

    Tan Derui; Lian Haiping

    2011-01-01

    In the course of Chinese civilization, which lasted more than 5,000 years, casting production has made a huge contribution. In this paper, some representative metal castings were presented. According to their forming techniques, they can be grouped into stone mould casting, clay mould casting, ablation casting, lost wax casting, stack casting, permanent mould casting, sand casting, etc. According to their materials, they can be categorized into tin bronze, bimetallic bronze, malleable cast ir...

  19. Special thermite cast irons

    OpenAIRE

    Yu. Zhiguts; I. Kurytnik

    2008-01-01

    The given paper deals with the problems of the synthesis of cast iron by metallothermy synthesis. On the basis of investigated method of calculations structures of charges have been arranged and cast iron has been synthesized further. Peculiarities metallothermic smelting were found, mechanical properties and structure of received cast iron were investigated and different technologies for cast iron receiving were worked out.

  20. Oblique incidence of semi-guided waves on rectangular slab waveguide discontinuities: A vectorial QUEP solver

    NARCIS (Netherlands)

    Hammer, Manfred

    2015-01-01

    The incidence of thin-film-guided, in-plane unguided waves at oblique angles on straight discontinuities of dielectric slab waveguides, an early problem of integrated optics, is being re-considered. The 3-D frequency domain Maxwell equations reduce to a parametrized inhomogeneous vectorial problem

  1. Finite Element Modelling of Mechanical Phenomena Connected to the Technological Process of Continuous Casting of Steel

    Directory of Open Access Journals (Sweden)

    J. Heger

    2004-01-01

    Full Text Available A finite element method algorithm is presented that enables numerical simulation of real phenomena that take place during an industrial process of continuous casting of steel. The algorithm takes into account all known kinds of nonlinearities: material nonlinearity connected to the nonlinear temperature dependence of material properties, large deformations from the process of material forming and contacts between the slab and rollers of the strand. Received results describe the sensitivity of the product to crack initiation, not only during the process of continuous casting itself but also in the finished and cooled slab.

  2. Enhanced Accelerated Drying of Concrete Floor Slabs

    OpenAIRE

    Holmes, Niall; West, Roger P.

    2013-01-01

    Concrete floor slabs dry out through a process of evaporation and diffusion provided the ambient environment promotes such drying. Impermeable floor coverings laid on concrete slabs can be subject to damage caused by high levels of residual moisture trapped by premature sealing of the surface. This damage can include timber floor boards buckling, vinyls blistering or tiles lifting. Whether or not it is safe to apply such a covering depends on whether the slab is sufficiently dry. Furthermore,...

  3. Generating Atomistic Slab Surfaces with Adsorbates

    Science.gov (United States)

    2017-12-01

    of spatial orientation on the possible adsorption sites. This framework was developed to coordinate the passing of structure information throughout...when making slabs. The list should be composed of strings that represent the name of the compound to skip. If no list is given for settings, then...8217_’+str(min_vac)) # Makes a slab directory except: pass iface_slab = Interface(structure, hkl

  4. Development of Flat Slab – Column Interaction with Different Thickness

    Directory of Open Access Journals (Sweden)

    Binti Joohari Ilya

    2017-01-01

    Full Text Available Flat slab – column connection has received much attention in recent years due to its simplicity of construction where beam is not required to support the slab. Flat slab has many usages in the construction field and has been investigated as a potential building material. Despite its many benefits, flat slab is easily subjected to punching shear failure. A simple approach to minimize punching shear failure is by increasing the slab thickness. It is generally accepted that the performance of flat slab is improved by using shear reinforcement; however, little attention has been paid to the selection of thickness. This research focuses on the crack behaviour of flat slab due to different slab thickness. Two specimens with different slab thickness have been constructed and tested to obtain the flat slab strength and crack pattern behaviour. Increasing the slab thickness was found to improve the strength of the flat slab and minimize the deflection and crack appearance on the slab.

  5. Impact resistance of sustainable construction material using light weight oil palm shells reinforced geogrid concrete slab

    International Nuclear Information System (INIS)

    Muda, Z C; Usman, F; Beddu, S; Alam, M A; Mustapha, K N; Birima, A H; Sidek, L M; Rashid, M A; Malik, G; Zarroq, O S

    2013-01-01

    This paper investigate the performance of lightweight oil palm shells (OPS) concrete slab with geogrid reinforcement of 300mm × 300mm size with 20mm, 30mm and 40 mm thick casted with different geogrid orientation and boundary conditions subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.2 kg drop at 1 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance the slab thickness, boundary conditions and geogrid reinforcement orientation. Test results indicate that the used of the geogrid reinforcement increased the impact resistance under service (first) limit crack up to 5.9 times and at ultimate limit crack up to 20.1 times against the control sample (without geogrid). A good linear relationship has been established between first and ultimate crack resistance against the slab thickness. The orientation of the geogrid has minor significant to the crack resistance of the OPS concrete slab. OPS geogrid reinforced slab has a good crack resistance properties that can be utilized as a sustainable impact resistance construction materials.

  6. Slab Waveguide and Optical Fibers for Novel Plasmonic Sensor Configurations.

    Science.gov (United States)

    Cennamo, Nunzio; Mattiello, Francesco; Zeni, Luigi

    2017-06-24

    The use of plasmonic sensor devices often requires replaceable parts and disposable chips for easy, fast and on-site detection analysis. In light of these requests, we propose a novel low-cost surface plasmon resonance sensor platform for possible selective detection of analytes in aqueous solutions. It is based on a Polymethyl methacrylate (PMMA) slab waveguide with a thin gold film on the top surface inserted in a special holder, designed to produce the plasmonic resonance at the gold-dielectric interface. A wide-band light is launched in the PMMA slab waveguide through a trench realized in the holder directly, and illuminated with a PMMA plastic optical fiber (POF) to excite surface Plasmon waves. The output light is then collected by another PMMA POF kept at the end of the slab at an angle of 90° to the trench, and carried to a spectrometer. In this configuration, the trench has been used because a large incident angle is required for surface plasmon resonance excitation. The preliminary results showed that the sensor's performances make it suitable for bio-chemical applications. The easy replacement of the chip allows for the production of an engineered platform by simplifying the measurement procedures.

  7. Analysis and design of reinforced concrete slab

    OpenAIRE

    Kališnik, Žiga

    2014-01-01

    The graduation thesis examines the analysis and design of a reinforced concrete slab. Slab loads are based on guidelines from standards SIST EN 1990 and SIST EN 1991-1-1, and the design is made according to standard SIST EN 1992-1-1, which covers concrete structures' design. The slab is analysed with finite element method using Safe computer code. The process of modeling slab structure in Safe computer code is described. Based on loads from ultimate limit state reinforcement is calculated and...

  8. One-Way Coupling of an Advanced CFD Multi-Physics Model to FEA for Predicting Stress-Strain in the Solidifying Shell during Continuous Casting of Steel

    Science.gov (United States)

    Svensson, Johan; Ramírez López, Pavel E.; Jalali, Pooria N.; Cervantes, Michel

    2015-06-01

    One of the main targets for Continuous Casting (CC) modelling is the actual prediction of defects during transient events. However, the majority of CC models are based on a statistical approach towards flow and powder performance, which is unable to capture the subtleties of small variations in casting conditions during real industrial operation or the combined effects of such changes leading eventually to defects. An advanced Computational Fluid Dynamics (CFD) model; which accounts for transient changes on lubrication during casting due to turbulent flow dynamics and mould oscillation has been presented on MCWASP XIV (Austria) to address these issues. The model has been successfully applied to the industrial environment to tackle typical problems such as lack of lubrication or unstable flows. However, a direct application to cracking had proven elusive. The present paper describes how results from this advanced CFD-CC model have been successfully coupled to structural Finite Element Analysis (FEA) for prediction of stress-strains as a function of irregular lubrication conditions in the mould. The main challenge for coupling was the extraction of the solidified shell from CFD calculations (carried out with a hybrid structured mesh) and creating a geometry by using iso-surfaces, re-meshing and mapping loads (e.g. temperature, pressure and external body forces), which served as input to mechanical stress-strain calculations. Preliminary results for CC of slabs show that the temperature distribution within the shell causes shrinkage and thermal deformation; which are in turn, the main source of stress. Results also show reasonable stress levels of 10-20 MPa in regions, where the shell is thin and exposed to large temperature gradients. Finally, predictions are in good agreement with prior works where stresses indicate compression at the slab surface, while tension is observed at the interior; generating a characteristic stress-strain state during solidification in CC.

  9. Impact sound insulation improvement of wooden floors on concrete slabs

    DEFF Research Database (Denmark)

    Rasmussen, Birgit; Hoffmeyer, Dan; Hansen, Rói

    2014-01-01

    renovating housing. In Denmark, there are about 1 million dwellings in multi-storey housing. About half of the dwellings are built with timber floors, and the other half with wooden floors on concrete slabs, either in-situ cast or prefabricated hollow-core elements. In a project including mapping of sound...... insulation in the Danish housing stock and investigation of improvement possibilities, a pilot laboratory study of wooden floors on concrete was carried out. The laboratory study included impact sound improvement measurements of full-scale samples (10 m2) fulfilling the conditions in EN ISO 10140....... The measurements indicated up to about 8 dB improvement potential compared to floor constructions typical before the latest change of regulations, namely wooden floors on joists on PE wedges or similar. In addition, tests of small-scale samples (1 m2) – unsuitable for type testing – were performed to provide...

  10. A slab expression in the Gibraltar arc?

    Science.gov (United States)

    Nijholt, Nicolai; Govers, Rob; Wortel, Rinus

    2017-04-01

    The present-day geodynamic setting of the Gibraltar arc region results from several Myrs of subduction rollback in the overall (oblique) convergence of Africa and Iberia. As for most rollback settings in a convergence zone, the interaction of these two components is complex and distinctly non-stationary. Gibraltar slab rollback is considered to have stalled, or at least diminished largely in magnitude, since the late Miocene/early Pliocene, suggesting that the effect of the slab on present-day surface motions is negligible. However, GPS measurements indicate that the Gibraltar arc region has an anomalous motion with respect to both Iberia and Africa, i.e., the Gibraltar arc region does not move as part of the rigid Iberian, or the rigid African plate. A key question is whether this surface motion is an expression of the Gibraltar slab. Seismic activity in the Gibraltar region is diffuse and considerable in magnitude, making it a region of high seismic risk. Unlike the North African margin to the east, where thrust earthquakes dominate the focal mechanism tables, a complex pattern is observed with thrust, normal and strike-slip earthquakes in a region stretching between the northern Moroccan Atlas across the Gibraltar arc and Alboran Sea (with the Trans-Alboran Shear Zone) to the Betics of southern Spain. Even though no large mega-thrust earthquakes have been observed in recent history, slab rollback may not have completely ceased. However, since no activity has been observed in the accretionary wedge, probably since the Pliocene, it is likely that the subduction interface is locked. In this study, we perform a series of numerical models in which we combine the relative plate convergence, variable magnitude of friction on fault segments, regional variations in gravitational potential energy and slab pull of the Gibraltar slab. We seek to reproduce the GPS velocities and slip sense on regional faults and thereby determine whether the Gibraltar slab has an effect on

  11. Constraining subducted slab properties with deep earthquakes

    Science.gov (United States)

    Zhan, Z.; Yang, T.; Gurnis, M.; Shen, Z.; Wu, F.

    2017-12-01

    The discovery of deep earthquakes and Wadati-Benioff zone was a critical piece in the early history of plate tectonics. Today, deep earthquakes continue to serve as important markers/probes of subducted slab geometry, structure, and stress state. Here we discuss three examples in which we have recently used deep earthquakes to provide new insights to subducted slab properties. In the first application, we investigate the slab morphology and stress regimes under different trench motion histories with geodynamic models. We find that the isolation of the 2015 Mw 7.9 Bonin Islands deep earthquake from the background Wadati-Benioff zone may be explained as a result of Pacific slab buckling in response to the slow trench retreat. Additionally, subducted slab is inherently heterogeneous due to non-linear viscosity, contributing to the occurrences of isolated deep earthquakes. In the second application, we quantify the coda waveform differences from nearby deep earthquakes to image fine-scale slab structures. We find that large metastable olivine wedge suggested by several previous studies can not fit our observations. Therefore, the effects of metastable olivine on slab dynamics should be re-assessed. In the third application, we take advantage of P and S differential travel times from deep earthquake clusters to isolate signatures of Vp/Vs ratios within slabs from ambient mantle. We observe substantial deviations of slab Vp/Vs from that in 1D reference Earth models, and even possible lateral variations. This sheds light on potential difference in slab temperature or water content. All three applications underscore that deep earthquakes are still incredibly useful in informing us more about subducted slabs.

  12. Chemical and energetic characterization for utilization of thinning and slab wood from Australian red cedar Caracterização química e energética para aproveitamento da madeira de costaneira e desbaste de cedro australiano

    Directory of Open Access Journals (Sweden)

    Lina Bufalino

    2012-06-01

    Full Text Available

    This work aimed to quantify and compare chemical and energetic properties of Australian red cedar Toona ciliata MJ Roem var. australis (FV Muell. C. DC wood from thinning and primary sawing for reconstituted panel and energy production; and also to verify the efficiency of extractive removal by water treatments, in order to improve wood quality for particleboard production. Lignin, holocellulose, extractives, ash, carbon, hydrogen, oxygen, nitrogen and sulfur contents and higher heating value were determined. Two water treatments for extractive removal were performed: immersion in cold water for 24 hours and immersion in boiling water for 2 hours. Lower values of ash, holocellulose, hydrogen and nitrogen contents and higher contents of lignin, total extractives, hydrogen and nitrogen contents were found for wood from primary sawing residues. For other properties, the values were significantly equal. Australian red cedar wood presents high extractive content, being water pre-treatment necessary for the production of some particleboards. Higher heating values of materials indicate potential for energy production.

    doi: 10.4336/2012.pfb.32.70.13

    O objetivo desse trabalho foi quantificar e comparar as propriedades químicas e energéticas da madeira de cedro australiano Toona ciliata MJ Roem var. australis (FV Muell. C. DC proveniente de desbaste e desdobro para produção de painéis reconstituídos e energia, além de verificar a eficiência da remoção de extrativos por tratamentos em água para viabilizar a produção de painéis de partículas. Os teores de lignina, holocelulose, extrativos totais, cinzas, carbono, hidrogênio, oxigênio, nitrogênio, enxofre e poder calorífico superior foram determinados. Dois tratamentos em água para remoção de extrativos foram realizados nos materiais: imersão em água fria durante 24 horas e em água fervente durante 2 horas. Foram encontrados menores teores de cinzas, holocelulose

  13. 0-6722 : spread prestressed concrete slab beam bridges.

    Science.gov (United States)

    2014-08-01

    The Texas Department of Transportation uses : precast prestressed concrete slab beam bridges for : shorter-span bridges of approximately 3050 ft in : length. Conventional slab beam bridges have slab : beams placed immediately adjacent to one anoth...

  14. Shear assessment of reinforced concrete slab bridges

    NARCIS (Netherlands)

    Lantsoght, E.O.L.; Van der Veen, C.; Walraven, J.C.; De Boer, A.

    2013-01-01

    The capacity of reinforced concrete solid slab bridges in shear is assessed by comparing the design beam shear resistance to the design value of the applied shear force due to the permanent actions and live loads. Results from experiments on half-scale continuous slab bridges are used to develop a

  15. Air slab-correction for Γ-ray attenuation measurements

    Science.gov (United States)

    Mann, Kulwinder Singh

    2017-12-01

    Gamma (γ)-ray shielding behaviour (GSB) of a material can be ascertained from its linear attenuation coefficient (μ, cm-1). Narrow-beam transmission geometry is required for μ-measurement. In such measurements, a thin slab of the material has to insert between point-isotropic γ-ray source and detector assembly. The accuracy in measurements requires that sample's optical thickness (OT) remain below 0.5 mean free path (mfp). Sometimes it is very difficult to produce thin slab of sample (absorber), on the other hand for thick absorber, i.e. OT >0.5 mfp, the influence of the air displaced by it cannot be ignored during μ-measurements. Thus, for a thick sample, correction factor has been suggested which compensates the air present in the transmission geometry. The correction factor has been named as an air slab-correction (ASC). Six samples of low-Z engineering materials (cement-black, clay, red-mud, lime-stone, cement-white and plaster-of-paris) have been selected for investigating the effect of ASC on μ-measurements at three γ-ray energies (661.66, 1173.24, 1332.50 keV). The measurements have been made using point-isotropic γ-ray sources (Cs-137 and Co-60), NaI(Tl) detector and multi-channel-analyser coupled with a personal computer. Theoretical values of μ have been computed using a GRIC2-toolkit (standardized computer programme). Elemental compositions of the samples were measured with Wavelength Dispersive X-ray Fluorescence (WDXRF) analyser. Inter-comparison of measured and computed μ-values, suggested that the application of ASC helps in precise μ-measurement for thick samples of low-Z materials. Thus, this hitherto widely ignored ASC factor is recommended to use in similar γ-ray measurements.

  16. Plastic casting resin poisoning

    Science.gov (United States)

    Epoxy poisoning; Resin poisoning ... Epoxy and resin can be poisonous if they are swallowed or their fumes are breathed in. ... Plastic casting resins are found in various plastic casting resin products.

  17. Diode-side-pumped Alexandrite slab lasers.

    Science.gov (United States)

    Damzen, M J; Thomas, G M; Minassian, A

    2017-05-15

    We present the investigation of diode-side-pumping of Alexandrite slab lasers in a range of designs using linear cavity and grazing-incidence bounce cavity configurations. An Alexandrite slab laser cavity with double-pass side pumping produces 23.4 mJ free-running energy at 100 Hz rate with slope efficiency ~40% with respect to absorbed pump energy. In a slab laser with single-bounce geometry output power of 12.2 W is produced, and in a double-bounce configuration 6.5 W multimode and 4.5 W output in TEM 00 mode is produced. These first results of slab laser and amplifier designs in this paper highlight some of the potential strategies for power and energy scaling of Alexandrite using diode-side-pumped Alexandrite slab architectures with future availability of higher power red diode pumping.

  18. Casting and Splinting

    Science.gov (United States)

    2017-08-21

    article /80165-technigue Self Evaluation Is injured extremity in desired position? »- Empty can position »- Wrist extension 20° );;>- MCP Oexion...periodically throughout the day If cast feels tight despite elevation seek medical assistance Do not scratch under cast; do not get cast wet Get

  19. A cryogenic slab CO laser

    International Nuclear Information System (INIS)

    Ionin, Andrei A; Kozlov, A Yu; Seleznev, L V; Sinitsyn, D V

    2009-01-01

    A compact capacitive transverse RF-discharge-pumped slab CO laser with cryogenically cooled electrodes, which operates both in the cw and repetitively pulsed regimes, is fabricated. The laser operation is studied in the free running multifrequency regime at the vibrational - rotational transitions of the fundamental (V + 1 → V) vibrational bands of the CO molecule in the spectral region from 5.1 to 5.4 μm. Optimal operation conditions (gas mixture composition and pressure, RF pump parameters) are determined. It is shown that only gas mixtures with a high content of oxygen (up to 20% with respect to the concentration of CO molecules) can be used as an active medium of this laser. It is demonstrated that repetitively pulsed pumping is more efficient compared to cw pumping. In this case, quasi-cw lasing regime can be obtained. The maximum average output power of ∼12 W was obtained for this laser operating on fundamental bands and its efficiency achieved ∼14 %. The frequency-selective operation regime of the slab RF-discharge-pumped CO laser was realised at ∼ 100 laser lines in the spectral region from 5.0 to 6.5 μm with the average output power of up to several tens of milliwatts in each line. Lasing at the transitions of the first vibrational overtone (V + 2 → V) of the CO molecule is obtained in the spectral region from 2.5 to 3.9 μm. The average output power of the overtone laser achieved 0.3 W. All the results were obtained without the forced gas mixture exchange in the discharge chamber. Under fixed experimental conditions, repetitively pulsed lasing (with fluctuations of the output characteristics no more than ±10 %) was stable for more than an hour. (lasers)

  20. Some problems in the production of ductile irons by investment casting

    Directory of Open Access Journals (Sweden)

    Yu Bo

    2008-02-01

    Full Text Available Because of the excellent performance of ductile irons and the unique superiority of investment casting, the preparation of complicated and thin-wall ductile iron castings by investment casting shows a good development prospect. In this present work, combined with the actual product experiments, the characteristics of shell making, spheroidization, inoculation and defect prevention are presented, and some suggestions are given for investment casting of ductile iron.

  1. Cretaceous Arctic magmatism: Slab vs. plume? Or slab and plume?

    Science.gov (United States)

    Gottlieb, E. S.; Miller, E. L.; Andronikov, A. V.; Brumley, K.; Mayer, L. A.; Mukasa, S. B.

    2010-12-01

    Tectonic models for the Cretaceous paleogeographic evolution of the Arctic Ocean and its adjacent landmasses propose that rifting in the Amerasia Basin (AB) began in Jura-Cretaceous time, accompanied by the development of the High Arctic Large Igneous Province (HALIP). During the same timespan, deformation and slab-related magmatism, followed by intra-arc rifting, took place along the Pacific side of what was to become the Arctic Ocean. A compilation and comparison of the ages, characteristics and space-time variation of circum-Arctic magmatism allows for a better understanding of the role of Pacific margin versus Arctic-Atlantic plate tectonics and the role of plume-related magmatism in the origin of the Arctic Ocean. In Jura-Cretaceous time, an arc built upon older terranes overthrust the Arctic continental margins of North America and Eurasia, shedding debris into foreland basins in the Brooks Range, Alaska, across Chukotka, Russia, to the Lena Delta and New Siberian Islands region of the Russian Arctic. These syn-tectonic sediments have some common sources (e.g., ~250-300 Ma magmatic rocks) as determined by U-Pb detrital zircon geochronology. They are as young as Valanginian-Berriasian (~136 Ma, Gradstein et al., 2004) and place a lower limit on the age of formation of the AB. Subsequent intrusions of granitoid plutons, inferred to be ultimately slab-retreat related, form a belt along the far eastern Russian Arctic continental margin onto Seward Peninsula and have yielded a continuous succession of zircon U-Pb ages from ~137-95 Ma (n=28) and a younger suite ~91-82 Ma (n=16). All plutons dated were intruded in an extensional tectonic setting based on their relations to wall-rock deformation. Regional distribution of ages shows a southward migration of the locus of magmatism during Cretaceous time. Basaltic lavas as old as 130 Ma and as young as 80 Ma (40Ar/39Ar)) erupted across the Canadian Arctic Islands, Svalbard and Franz Josef Land and are associated with

  2. Estimation of the Reliability of Plastic Slabs

    DEFF Research Database (Denmark)

    Pirzada, G. B. : Ph.D.

    In this thesis, work related to fundamental conditions has been extended to non-fundamental or the general case of probabilistic analysis. Finally, using the ss-unzipping technique a door has been opened to system reliability analysis of plastic slabs. An attempt has been made in this thesis...... to give a probabilistic treatment of plastic slabs which is parallel to the deterministic and systematic treatment of plastic slabs by Nielsen (3). The fundamental reason is that in Nielsen (3) the treatment is based on a deterministic modelling of the basic material properties for the reinforced...

  3. A Preliminary Experimental Study on Vibration Responses of Foamed Concrete Composite Slabs

    Science.gov (United States)

    Rum, R. H. M.; Jaini, Z. M.; Ghaffar, N. H. Abd; Rahman, N. Abd

    2017-11-01

    In recent years, composite slab has received utmost demand as a floor system in the construction industry. The composite slab is an economical type of structure and able to accelerate the construction process. Basically, the composite slab can be casting by using a combination of corrugated steel deck and normal concrete in which selfweight represents a very large proportion of the total action. Therefore, foamed concrete become an attractive alternative to be utilized as a replacement of normal concrete. However, foamed concrete has high flexibility due to the presence of large amount of air-void and low modulus elasticity. It may result in vibration responses being greater. Hence, this experimental study investigates the vibration responses of composite slab made of corrugated steel deck and foamed concrete. The specimens were prepared with dimension of 750mm width, 1600mm length and 125mm thickness. The hammer-impact test was conducted to obtain the acceleration-time history. The analysis revealed that the first natural frequency is around 27.97 Hz to 40.94 Hz, while the maximum acceleration reaches 1.31 m/s2 to 1.88 m/s2. The first mode shape depicts normal pattern and favourable agreement of deformation.

  4. The Terminal Stage of Subduction: the Hindu Kush Slab Break-off

    Science.gov (United States)

    Kufner, S. K.; Schurr, B.; Sippl, C.; Yuan, X.; Ratschbacher, L.; Akbar, A. S. M.; Ischuk, A.; Murodkulov, S.; Schneider, F.; Mechie, J.; Tilmann, F. J.

    2016-12-01

    The terminal stage of subduction arrives when the ocean basin is closed and the continental margin arrives at the trench. The opposite forces of the sinking slab and buoyant continent ultimately leads to break-off of the subducted slab. This process, although common in geological history, is rarely observed, because it is short-lived. Here we report new precise earthquake hypocenters, detailed tomographic images and earthquake source mechanisms from the Hindu Kush region in Central Asia, which hint at continental subduction and plate necking. Our images provide a rare glimpse at the ephemeral process of slab break-off: the Hindu Kush slablet in its uppermost section is thinned or already severed and that intermediate depth earthquakes cluster at the neck connecting it to the deeper slab. From a strain rate analysis, we deduce that the deep portion of the slab is in the process of detaching from the shallower fragment at much higher rates than the current convergence rate at the surface. The increased strain rate might arise as the buoyant continental crust, which is dragged into the subduction system in its terminal stage, resists subduction, whereas the earlier subducted mantle lithosphere pulls from underneath.

  5. Development of new model of mold oscillator in continuous casting

    International Nuclear Information System (INIS)

    Kang, G. P.; Shin, G.; Kang, C. G.

    2007-01-01

    To develop the hydraulic mold oscillator in continuous casting machine, the guiding mechanism of mold was studied. The main topics of this study were to design the guiding mechanism of mold which oscillates to prevent the sticking and to reduce the friction resistant force between the solidified shell and mold on casting. We studied many guiding types to analyze the features of worldwide mold oscillator and developed the new model of hydraulic mold oscillator. On the basis of the mold oscillating experiment, the capability of guiding system was proofed by the position error measuring system. The experiment was carried out up to 50∼500 cpm frequencies and 2∼10 mm stroke in the variable waveform and the casting results was analyzed by the oscillation mark of slab surface which was formed unavoidably by oscillation

  6. FLEXURAL BEHAVIOUR OF FERROCEMENT COMPOSITE SLAB.

    OpenAIRE

    S.Dharanidharan *

    2016-01-01

    This project deals with an investigational program to understood the flexural behavior of a Ferro cement composite slabs under mid third loading. The concept of composite slabs bring in shut decking or shear connectors are well established. But still, in countries like India, the application of same is limited due to difficulties in manufacture and also due to concerns like fire resistance, durability, aesthetics etc., this study is an attempt to exploit the concept of steel – concrete compos...

  7. Photocatalytic, highly hydrophilic porcelain stoneware slabs

    Science.gov (United States)

    Raimondo, M.; Guarini, G.; Zanelli, C.; Marani, F.; Fossa, L.; Dondi, M.

    2011-10-01

    Photocatalytic, highly hydrophilic industrial porcelain stoneware large slabs were realized by deposition of nanostructured TiO2 coatings. Different surface finishing and experimental conditions were considered in order to assess the industrial feasibility. Photocatalytic and wetting behaviour of functionalized slabs mainly depends on surface phase composition in terms of anatase/rutile ratio, this involving - as a key issue - the deposition of TiO2 on industrially sintered products with an additional annealing step to strengthen coatings' performances and durability.

  8. Expandable pattern casting research

    Science.gov (United States)

    1993-09-01

    The Expandable Pattern Casting (EPC) Process is a developing foundry technology that allows designers the opportunity to consolidate parts, reduce machining, and minimize assembly operations. An air gauging system was developed for measuring foam patterns; exact shrinkage depended on type and density of the foam. Compaction studies showed that maximum sand densities in cavities and under overhangs are achieved with vibrational amplitudes 0.001-0.004 in., and that sand moved most freely within a few inches of the top free surface. Key to complete mold filling while minimizing casting defects lies in removing the foam decomposition products. The most precise iron castings were made by EPC in four commercial EPC foundries, with attention paid to molding and compaction. EP cast 60-45-12 ductile iron had yield strengths, ultimate strengths, and elastic modulus similar to conventionally cast ductile iron cast from the same ladle.

  9. Development of Flat Slab – Column Interaction with Different Thickness

    OpenAIRE

    Binti Joohari Ilya; Binti Mohd Amin Norliyati

    2017-01-01

    Flat slab – column connection has received much attention in recent years due to its simplicity of construction where beam is not required to support the slab. Flat slab has many usages in the construction field and has been investigated as a potential building material. Despite its many benefits, flat slab is easily subjected to punching shear failure. A simple approach to minimize punching shear failure is by increasing the slab thickness. It is generally accepted that the performance of fl...

  10. Caste and power

    DEFF Research Database (Denmark)

    Roy, Dayabati

    2011-01-01

    This paper explores the institution of caste and its operation in a micro-level village setting of West Bengal, an Indian state, where state politics at grass roots level is vibrant with functioning local self-government and entrenched political parties. This ethnographic study reveals that caste......–ideological field, the concept of caste-hierarchy seems to continue as an influencing factor, even in the operation of leftist politics....

  11. Evolution of halictine castes

    Science.gov (United States)

    Knerer, Gerd

    1980-03-01

    Social halictine bees have female castes that range from species with no size differences to those with a discrete bimodality. Female caste differences are inversely correlated with the number of males produced in the first brood. It is proposed that the sexual dimorphism of solitary forms is being usurped by the female caste system of species in the process of turning social. Thus, caste differences and summer male suppression are greatest in the social species originating from solitary precursors with distinct sexual dimorphism, and are least in species evolving from solitary ancestors with a continuous sexual polymorphism.

  12. Analysis of Mold Friction in a Continuous Casting Using Wavelet Transform

    Science.gov (United States)

    Ma, Yong; Fang, Bohan; Ding, Qiqi; Wang, Fangyin

    2018-04-01

    Mold friction (MDF) is an important parameter reflecting the lubrication condition between the initial shell and the mold during continuous casting. In this article, based on practical MDF from the slab continuous casting driven by a mechanical vibration device, the characteristics of friction were analyzed by continuous wavelet transform (CWT) and discrete wavelet transform (DWT) in different casting conditions, such as normal casting, level fluctuation, and alarming of the temperature measurement system. The results show that the CWT of friction accurately captures the subtle changes in friction force, such as the periodic characteristic of MDF during normal casting and the disordered feature of MDF during level fluctuation. Most important, the results capture the occurrence of abnormal casting and display the friction frequency characteristics at this abnormal time. In addition, in this article, there are some abnormal casting conditions, and the friction signal is stable until there is a sudden large change when abnormal casting, such as split breakout and submerged entry nozzle breakage, occurs. The DWT has a good ability to capture the friction characteristics for such abnormal situations. In particular, the potential abnormal features of MDF were presented in advance, which provides strong support for identifying abnormal casting and even preventing abnormal casting.

  13. Caste in Itself, Caste and Class, or Caste in Class

    OpenAIRE

    Ramkrishna Mukherjee

    2015-01-01

    After the British conquered Bengal and eventually the whole of India,they set out to administer the colony. In this context they encountered two phenomena with which they were not familiar: (1) the relation of people to land for production (and not for revenue receiving, household living, etc.), and (2) the caste system of India, viz. the jati strati?cation of society.

  14. Big mantle wedge, anisotropy, slabs and earthquakes beneath the Japan Sea

    Science.gov (United States)

    Zhao, Dapeng

    2017-09-01

    The Japan Sea is a part of the western Pacific trench-arc-backarc system and has a complex bathymetry and intense seismic activities in the crust and upper mantle. Local seismic tomography revealed strong lateral heterogeneities in the crust and uppermost mantle beneath the eastern margin of the Japan Sea, which was determined using P and S wave arrival times of suboceanic earthquakes relocated precisely with sP depth phases. Ambient-noise tomography revealed a thin crust and a thin lithosphere beneath the Japan Sea and significant low-velocity (low-V) anomalies in the shallow mantle beneath the western and eastern margins of the Japan Sea. Observations with ocean-bottom seismometers and electromagnetometers revealed low-V and high-conductivity anomalies at depths of 200-300 km in the big mantle wedge (BMW) above the subducting Pacific slab, and the anomalies are connected with the low-V zone in the normal mantle wedge beneath NE Japan, suggesting that both shallow and deep slab dehydrations occur and contribute to the arc and back-arc magmatism. The Pacific slab has a simple geometry beneath the Japan Sea, and earthquakes occur actively in the slab down to a depth of ∼600 km beneath the NE Asian margin. Teleseismic P and S wave tomography has revealed that the Philippine Sea plate has subducted aseismically down to the mantle transition zone (MTZ, 410-660 km) depths beneath the southern Japan Sea and the Tsushima Strait, and a slab window is revealed within the aseismic Philippine Sea slab. Seismic anisotropy tomography revealed a NW-SE fast-velocity direction in the BMW, which reflects corner flows induced by the fast deep subduction of the Pacific slab. Large deep earthquakes (M > 7.0; depth > 500 km) occur frequently beneath the Japan Sea western margin, which may be related to the formation of the Changbai and Ulleung intraplate volcanoes. A metastable olivine wedge is revealed within the cold core of the Pacific slab at the MTZ depth, which may be related

  15. On Degradation of Cast Iron Surface-Protective Paint Coat Joint

    Directory of Open Access Journals (Sweden)

    Tupaj M.

    2016-09-01

    Full Text Available The paper is a presentation of a study on issues concerning degradation of protective paint coat having an adverse impact on aesthetic qualities of thin-walled cast-iron castings fabricated in furan resin sand. Microscopic examination and microanalyses of chemistry indicated that under the coat of paint covering the surface of a thin-walled casting, layers of oxides could be found presence of which can be most probably attributed to careless cleaning of the casting surface before the paint application process, as well as corrosion pits evidencing existence of damp residues under the paint layers contributing to creation of corrosion micro-cells

  16. Cracking behavior of structural slab bridge decks

    Science.gov (United States)

    Baah, Prince

    Bridge deck cracking is a common problem throughout the United States, and it affects the durability and service life of concrete bridges. Several departments of transportation (DOTs) in the United States prefer using continuous three-span solid structural slab bridges without stringers over typical four-lane highways. Recent inspections of such bridges in Ohio revealed cracks as wide as 0.125 in. These measured crack widths are more than ten times the maximum limit recommended in ACI 224R-01 for bridge decks exposed to de-icing salts. Measurements using digital image correlation revealed that the cracks widened under truck loading, and in some cases, the cracks did not fully close after unloading. This dissertation includes details of an experimental investigation of the cracking behavior of structural concrete. Prism tests revealed that the concrete with epoxy-coated bars (ECB) develops the first crack at smaller loads, and develops larger crack widths compared to the corresponding specimens with uncoated (black) bars. Slab tests revealed that the slabs with longitudinal ECB developed first crack at smaller loads, exhibited wider cracks and a larger number of cracks, and failed at smaller ultimate loads compared to the corresponding test slabs with black bars. To develop a preventive measure, slabs with basalt and polypropylene fiber reinforced concrete were also included in the test program. These test slabs exhibited higher cracking loads, smaller crack widths, and higher ultimate loads at failure compared to the corresponding slab specimens without fibers. Merely satisfying the reinforcement spacing requirements given in AASHTO or ACI 318-11 is not adequate to limit cracking below the ACI 224R-01 recommended maximum limit, even though all the relevant design requirements are otherwise met. Addition of fiber to concrete without changing any steel reinforcing details is expected to reduce the severity and extent of cracking in reinforced concrete bridge decks.

  17. Casting Footprints for Eternity

    Science.gov (United States)

    1999-01-01

    Apollo 11 Astronaut Buzz Aldrin has his footprints casted during the dedication ceremony of the rocket fountain at Building 4200 at Marshall Space Flight Center. The casts of Aldrin's footprints will be placed in the newly constructed Von Braun courtyard representing the accomplishments of the Apollo 11 lunar landing.

  18. Higher Education's Caste System

    Science.gov (United States)

    Iannone, Ron

    2004-01-01

    In this article, the author discusses the history of the present caste system in higher education. He shows how the public's perception of this caste system is based on image and not usually on the quality of teaching and curriculum in colleges and universities. Finally, he discusses a model for accessibility to higher education and how higher…

  19. Cool Cast Facts

    Science.gov (United States)

    ... sleeve to protect it in the bath or shower. A splint does the same thing as a cast: It keeps the broken or injured bone from moving so it can heal. It also usually has a soft layer of cotton inside. A splint can be made from the same materials as a cast or may be a pre- ...

  20. Impact and Energy Dissipation Characteristics of Squeeze and Die Cast Magnesium Alloy AM60

    Science.gov (United States)

    DiCecco, Sante; Hu, Henry; Altenhof, William

    High-pressure die cast (HPDC) magnesium alloy AM60 is recognized for its versatility in the manufacturing of weight sensitive components of relatively thin cross section. To further expand practical applications of the alloy, squeeze casting has been proposed to allow for thicker castings. In this study, AM60 alloy specimens of 10mm thickness were squeeze cast using a hydraulic press with an applied pressure of 60 MPa. Fracture energies, following a Charpy Impact Testing protocol, of the squeeze cast specimens were characterized in comparison with the HPDC counterparts using both experimental and numerical techniques. The experimental results show the squeeze cast alloy absorbing approximately 46.2% more energy during impact than its HPDC counterpart. Scanning electron microscopy fractography reveals the favourable quasi-cleavage fracture mode of the squeeze cast alloy AM60, relative to the decohesive rupture fracture mode present in the die cast alloy.

  1. Multi-layers castings

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2010-01-01

    Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

  2. Accidents due to falls from roof slabs.

    Science.gov (United States)

    Rudelli, Bruno Alves; Silva, Marcelo Valerio Alabarce da; Akkari, Miguel; Santili, Claudio

    2013-01-01

    CONTEXT AND OBJECTIVE Falls from the roof slabs of houses are accidents of high potential severity that occur in large Brazilian cities and often affect children and adolescents. The aims of this study were to characterize the factors that predispose towards this type of fall involving children and adolescents, quantify the severity of associated lesions and suggest preventive measures. DESIGN AND SETTING Descriptive observational prospective longitudinal study in two hospitals in the metropolitan region of São Paulo. METHODS Data were collected from 29 cases of falls from roof slabs involving children and adolescents between October 2008 and October 2009. RESULTS Cases involving males were more prevalent, accounting for 84%. The predominant age group was schoolchildren (7 to 12 years old; 44%). Leisure activities were most frequently being practiced on the roof slab at the time of the fall (86%), and flying a kite was the most prevalent game (37.9%). In 72% of the cases, the children were unaccompanied by an adult responsible for them. Severe conditions such as multiple trauma and traumatic brain injuries resulted from 79% of the accidents. CONCLUSION Falls from roof slabs are accidents of high potential severity, and preventive measures aimed towards informing parents and guardians about the dangers and risk factors associated with this type of accident are needed, along with physical protective measures, such as low walls around the slab and gates with locks to restrict free access to these places.

  3. Accidents due to falls from roof slabs

    Directory of Open Access Journals (Sweden)

    Bruno Alves Rudelli

    Full Text Available CONTEXT AND OBJECTIVE Falls from the roof slabs of houses are accidents of high potential severity that occur in large Brazilian cities and often affect children and adolescents. The aims of this study were to characterize the factors that predispose towards this type of fall involving children and adolescents, quantify the severity of associated lesions and suggest preventive measures. DESIGN AND SETTING Descriptive observational prospective longitudinal study in two hospitals in the metropolitan region of São Paulo. METHODS Data were collected from 29 cases of falls from roof slabs involving children and adolescents between October 2008 and October 2009. RESULTS Cases involving males were more prevalent, accounting for 84%. The predominant age group was schoolchildren (7 to 12 years old; 44%. Leisure activities were most frequently being practiced on the roof slab at the time of the fall (86%, and flying a kite was the most prevalent game (37.9%. In 72% of the cases, the children were unaccompanied by an adult responsible for them. Severe conditions such as multiple trauma and traumatic brain injuries resulted from 79% of the accidents. CONCLUSION Falls from roof slabs are accidents of high potential severity, and preventive measures aimed towards informing parents and guardians about the dangers and risk factors associated with this type of accident are needed, along with physical protective measures, such as low walls around the slab and gates with locks to restrict free access to these places.

  4. Mechanical Properties of Aluminum Die-casting Alloys

    Directory of Open Access Journals (Sweden)

    Sun Xiaodong

    2016-01-01

    Full Text Available The effects of strontium addition on the microstructure and mechanical properties of aluminum alloys 380 and 413 are researched. All samples are prepared through high pressure die-casting, and the effect of the sample’s thickness is also compared. The results indicate that the Sr addition can refine the metallographic microstructure of two alloys in different degrees, mainly to eutectic Si phase. The mechanical properties of the two alloys are improved slightly through Sr modification to the thin wall castings. The enhancement of mechanical properties is evident to the thick wall castings.

  5. Caste in Itself, Caste and Class, or Caste in Class

    Directory of Open Access Journals (Sweden)

    Ramkrishna Mukherjee

    2015-08-01

    Full Text Available After the British conquered Bengal and eventually the whole of India,they set out to administer the colony. In this context they encountered two phenomena with which they were not familiar: (1 the relation of people to land for production (and not for revenue receiving, household living, etc., and (2 the caste system of India, viz. the jati strati?cation of society.

  6. properties of the SN - equivalent integral transport operator in slab geometry and the iterative acceleration of neutron transport methods

    International Nuclear Information System (INIS)

    Massimiliano, Rosa; Azmy, Y.Y.; Morel, J.E.

    2005-01-01

    The general expressions for the matrix elements of the discrete Sn-equivalent integral transport operator have been derived in slab geometry. Their asymptotic behavior has been investigated both for a homogeneous slab and for a heterogeneous slab characterized by a periodic material discontinuity wherein each optically thick cell is surrounded by two optically thin cells in a repeating pattern. In the case of a homogeneous slab, the asymptotic analysis conducted in a diffusive limit obtained as the thick limit of computational cell size for a highly scattering medium, has shown that the discretized integral transport operator is approximated by a sparse matrix characterized by a tri-diagonal diffusion-like coupling stencil. Also, the tri-diagonal matrix structure, characteristic of the diffusion coupling stencil, is approached at a fast exponential rate. In the case of periodically heterogeneous slab configurations, the asymptotic behavior investigated is that in which the cells' optical thicknesses are pushed apart, i.e. the thick is made thicker while the thin is made thinner at a prescribed rate. It has been shown that in this limit the discretized integral transport operator is approximated by a penta-diagonal structure. Notwithstanding, the discrete operator is amenable to algebraic transformations leading to a matrix representation still asymptotically approaching a tri-diagonal structure at a fast exponential rate. The existence of a low order tri-diagonal approximation to the full discrete integral transport operator in the case of a periodically heterogeneous slab might provide a basic understanding of the superior convergence properties of diffusion-based acceleration schemes observed in slab geometry, even in the presence of sharp material discontinuities. The obtained results also suggest that a sparse approximation to the S n -equivalent integral transport operator might itself be used as the low-order operator in an acceleration scheme for the

  7. Influence of slab length on dynamic characteristics of subway train-steel spring floating slab track-tunnel coupled system

    Directory of Open Access Journals (Sweden)

    Qing-yuan Xu

    Full Text Available A subway train-steel spring floating slab track-tunnel coupling dynamic model, considering short and middle-long wavelength random track irregularities, and longitudinal connection between adjacent slabs of steel spring floating slab track, was developed. And the influence of slab length on dynamic characteristics of the system under different track conditions and train speeds are theoretically studied. The calculated results show: (1 In general, the acceleration of each component of the coupled system decreases with the increase of slab length under the perfectly smooth track condition; (2 Slab length has different influence laws on acceleration of each component of subway train-steel spring floating slab track-tunnel coupled system under random irregularity of track condition. The lower the dominant frequency distribution of vibration acceleration is, the higher influence slab length has; (3 With the increase of slab length, the force of rail, fastener and steel spring also decreases significantly, which helps to lengthen the service life of these components; (4 With the increase of slab length, the longitudinal bending moment of slab increases sharply at first, then it begins to drop slightly. When slab length exceeds the distance between two bogies of a vehicle, the longitudinal bending moment of slab changes little; (5 Slab length has significant influence on the dynamic force and displacement of the coupled system when train speed is higher.

  8. Slab tears and intermediate-depth seismicity

    Science.gov (United States)

    Meighan, Hallie E.; ten Brink, Uri S.; Pulliam, Jay

    2013-01-01

    Active tectonic regions where plate boundaries transition from subduction to strike slip can take several forms, such as triple junctions, acute, and obtuse corners. Well-documented slab tears that are associated with high rates of intermediate-depth seismicity are considered here: Gibraltar arc, the southern and northern ends of the Lesser Antilles arc, and the northern end of Tonga trench. Seismicity at each of these locations occurs, at times, in the form of swarms or clusters, and various authors have proposed that each marks an active locus of tear propagation. The swarms and clusters start at the top of the slab below the asthenospheric wedge and extend 30–60 km vertically downward within the slab. We propose that these swarms and clusters are generated by fluid-related embrittlement of mantle rocks. Focal mechanisms of these swarms generally fit the shear motion that is thought to be associated with the tearing process.

  9. Zooming into the Hindu Kush slab break-off: a rare glimpse on the transition from subduction to collision

    Science.gov (United States)

    Kufner, Sofia-Katerina; Schurr, Bernd; Haberland, Christian; Zhang, Yong; Saul, Joachim; Ischuk, Anatoly; Oimahmadov, Ilhomjon

    2017-04-01

    The transition from oceanic subduction to continental collision involves the entrainment of continental lithosphere into the subduction system. The opposing forces of the sinking slab and the buoyant continent then stretch the subducted lithosphere and ultimately lead to its break-off. Although many orogens show geological indications for such events, slab break-off is currently rarely observed as the final pinching-off is thought to be a fast process. The deep seismicity under the Hindu Kush mountains in Central Asia is such a rare case. Here, we use new data from a four years lasting seismic network to create a high resolution picture of slab break-off and infer its dynamics. Travel time tomography resolves a near-vertically dipping subducting slab beneath the Hindu Kush down to 600 km and subduction of continental crust down to 180 km. The subducted slab is critically thinned at 200 km, where also seismicity is most intense (e.g. five Mw>7 earthquakes in the last 30 years). Earthquake source mechanisms indicate sub-vertical extension in the entire slab but highest seismic strain rates occur in the deeper seismogenic portion of the slab, below the subducted crust. Extending our data set to larger time-spans by including and relocating the largest earthquakes of the past 30 years, we calculate a stretching rate of 40 km/Ma. From this combined seismicity distribution and the rupture mechanisms we further deduce that the break-off advances along-strike of the Hindu Kush seismic zone at the base of the subducted continental crust. The dominant deformation mechanism in the subducted mantle lithosphere changes along-strike from simple to pure shear. The fastest detachment rates and largest earthquakes occur during the simple shear dominated stage. Smaller and less frequent earthquakes above the rapidly extending slab might be triggered by processes related to the subduction of crustal rocks.

  10. Impact of as-cast structure on structure and properties of twin-roll cast AA8006 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Slamova, M.; Ocenasek, V. [Vyzkumny Ustav Kovu, Panenske Brezany (Czechoslovakia); Juricek, Z.

    2000-07-01

    Sheet production by twin-roll casting (TRC) process is a well established practice in the aluminium industry because it offers several advantages in comparison with DC casting and hot rolling, esp. lower production and investment costs. Thin strips exhibiting a combination of good strength and high ductility are required for various applications and for this reason alloys with higher Fe and Mn content such as AA 8006 displace AA 1xxx or AA 8011 alloys. However, TRC of AA 8006 strips involves several problems, e.g. casting conditions and subsequent treatment procedures need fine tuning. The results of an investigation of the effect of casting conditions on structure and properties of AA 8006 strips are presented. The influence of casting speed, grain refiner addition, molten metal level in the tundish, tip setback and roll separating force was investigated. The impact of imperfect as-cast structure on structure and properties of thin strips in H22 and O tempers was evaluated and compared with strips from good as-cast material. (orig.)

  11. The ancient Chinese casting techniques

    Directory of Open Access Journals (Sweden)

    Tan Derui

    2011-02-01

    Full Text Available In the course of Chinese civilization, which lasted more than 5,000 years, casting production has made a huge contribution. In this paper, some representative metal castings were presented. According to their forming techniques, they can be grouped into stone mould casting, clay mould casting, ablation casting, lost wax casting, stack casting, permanent mould casting, sand casting, etc. According to their materials, they can be categorized into tin bronze, bimetallic bronze, malleable cast iron, ductile cast iron, brass, cupronickel alloy (Packtong, etc. According to their surface decorative techniques they can be devided into gem inlay, gilding, gold and silver inlay, copper inlay, engraved decoration, surface tin-enrichment, mother-of-pearl inlay, burnished works with gold or silver inlay, surface coloring and cloisonné enamel, etc.

  12. Clean Metal Casting

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The objective of this project is to develop a technology for clean metal processing that is capable of consistently providing a metal cleanliness level that is fit for a given application. The program has five tasks: Development of melt cleanliness assessment technology, development of melt contamination avoidance technology, development of high temperature phase separation technology, establishment of a correlation between the level of melt cleanliness and as cast mechanical properties, and transfer of technology to the industrial sector. Within the context of the first task, WPI has developed a standardized Reduced Pressure Test that has been endorsed by AFS as a recommended practice. In addition, within the context of task1, WPI has developed a melt cleanliness sensor based on the principles of electromagnetic separation. An industrial partner is commercializing the sensor. Within the context of the second task, WPI has developed environmentally friendly fluxes that do not contain fluorine. Within the context of the third task, WPI modeled the process of rotary degassing and verified the model predictions with experimental data. This model may be used to optimize the performance of industrial rotary degassers. Within the context of the fourth task, WPI has correlated the level of melt cleanliness at various foundries, including a sand casting foundry, a permanent mold casting foundry, and a die casting foundry, to the casting process and the resultant mechanical properties. This is useful in tailoring the melt cleansing operations at foundries to the particular casting process and the desired properties of cast components.

  13. Entropy distribution in accelerated gaseous slabs

    International Nuclear Information System (INIS)

    Thomas, L.P.; Diez, J.A.

    1990-01-01

    Shocks developed in an accelerated plane layer of ideal gas are studied. The layer is driven towards vacuum by an ideal rigid piston. There can be an intermediate solid slab between the gas and the piston. It gives to the slabs a stepwise pressure pulse with or without prepulse. The shock compressions build up non-uniform profiles in the gas. Explicit analytical expressions for the Lagrangian distribution of entropy are found. Then, the width of innermost part of the gas with higher specific entropy was obtained. These results are of interest to regulate the spark formation parameters in ICF experiments. (Author)

  14. Behaviour of reinforced concrete slabs with steel fibers

    Science.gov (United States)

    Baarimah, A. O.; Syed Mohsin, S. M.

    2017-11-01

    This paper investigates the potential effect of steel fiber added into reinforced concrete slabs. Four-point bending test is conducted on six slabs to investigate the structural behaviour of the slabs by considering two different parameters; (i) thickness of slab (ii) volume fraction of steel fiber. The experimental work consists of six slabs, in which three slabs are designed in accordance to Eurocode 2 to fulfil shear capacity characteristic, whereas, the other three slabs are designed with 17% less thickness, intended to fail in shear. Both series of slabs are added with steel fiber with a volume fraction of Vf = 0%, Vf = 1% and Vf = 2% in order to study the effect and potential of fiber to compensate the loss in shear capacity. The slab with Vf = 0% steel fiber and no reduction in thickness is taken as the control slab. The experimental result suggests promising improvement of the load carrying capacity (up to 32%) and ductility (up to 87%) as well as delayed in crack propagation for the slabs with Vf = 2%. In addition, it is observed that addition of fibers compensates the reduction in the slab thickness as well as changes the failure mode of the slab from brittle to a more ductile manner.

  15. Symptomatic stent cast.

    LENUS (Irish Health Repository)

    Keohane, John

    2012-02-03

    Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.

  16. The slab geometry laser. II - Thermal effects in a finite slab

    Science.gov (United States)

    Kane, T. J.; Byer, R. L.; Eggleston, J. M.

    1985-01-01

    This paper presents two methods for calculating the thermally induced stress, focusing, and depolarization in a pumped zigzag-slab solid-state laser. A computer program capable of detailed calculations of thermal effects in the general case is described. An approximate analysis of slab thermal effects in many cases allows calculation of these effects without use of the computer model directly. The analysis predicts that slabs of square cross section can be designed to have low depolarization and thermal focusing compared to Nd:YAG laser rods.

  17. On the interrelation between bulk and thin-film Fermi surfaces

    KAUST Repository

    Schwingenschlögl, Udo

    2010-12-01

    A general scheme for inferring the Fermi surface of a finite slab from ab initio electronic-structure calculations for the parent bulk system is introduced. The simple cubic ReO 3 oxide is studied as an example system. We show that our scheme provides an accurate approximation of the Fermi surface even for very thin slabs. © 2010 Europhysics Letters Association.

  18. Inter-Batch Variation and the Effect of Casting Vacuum on Ballistic and Mechanical Properties of a High Performing Cast Composite Rocket Propellant

    Science.gov (United States)

    2014-12-01

    Tensile testing of propellant in the form of ‘ dog bones’ or uniaxial tensile test pieces cut from cast slabs of propellant was performed to assess inter... dog bones were cut from the top of the mould. It is possible that the strands for both partial and full vacuum had a slightly higher solids content... Behaviour of AP/HTPB Propellant Using Coarse and Fine AP Particles. Propellants, Explosives, Pyrotechnics, 2011. 36: p. 57-64. 9. Smith, P.C

  19. Influence of formwork surface on the orientation of steel fibres within self-compacting concrete and on the mechanical properties of cast structural elements

    DEFF Research Database (Denmark)

    Svec, Oldrich; Zirgulis, Giedrius; Bolander, John E.

    2014-01-01

    The influences of formwork surface on the final orientation of steel fibres immersed in self-compacting concrete and on the resulting mechanical response of the cast structural elements are investigated. Experimental observations of fibre orientation within cast slabs, obtained via computed...... tomography, indicate that fibres tend to orient according to the flow patterns during casting, but such tendencies are suppressed near rough formwork surfaces. Fibre orientation, in turn, affects the mechanical properties of the concrete as demonstrated by the load testing of beams extracted from the cast...... and the mechanical response of the structural elements. (C) 2013 Elsevier Ltd. All rights reserved....

  20. Reinforcement of the concrete base slab of the ATLAS cavern

    CERN Multimedia

    Maximilien Brice

    2002-01-01

    Photo 02: UX15 cavern, preparation for concreting of base slab first lift. Photo 05: UX15 cavern, placing of reinforcement for base slab first lift. Photo 07: UX15 cavern, preparation for concreting of base slab first lift. Photo 09: UX15 cavern, placing of reinforcement for base slab first lift. Photo 10: UX15 cavern, view into PX14 shaft above. Photo 12: UX15 cavern, temporary access platform of RB16 tunnel. Photo 15: UJ17 chamber, invert excavation.

  1. The need and benefit of slab track: case of Lithuania

    OpenAIRE

    Gailienė, Inesa; Laurinavičius, Alfredas

    2017-01-01

    Slab track structures have been used in the world for several decades now. However, the ballasted track is still much more popular compared to slab track structures, which is primarily due to its lower price. This article reviews and analyses development of slab tracks, with their advantages and disadvantages. Based on conditions prevailing on Lithuanian railways, the paper also distinguishes cases in which slab track structures could be of benefit, both economically and technologically. The ...

  2. Cost analysis of reinforced concrete slabs and columns

    OpenAIRE

    Spuś, Piotr

    2013-01-01

    The construction industry is increasingly looking for solutions that are both simple and effective and that provide cost savings, speed and flexibility of execution. Two-way slabs are a form of construction unique to reinforced concrete comparing with the other major structural materials. It is an efficient, economical, and widely used structural system. The present dissertation aims to analyze and compare costs between four types of slabs: waffle slab with recuperate molds, flat slabs wit...

  3. HFIR Fuel Casting Support

    Energy Technology Data Exchange (ETDEWEB)

    Imhoff, Seth D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gibbs, Paul Jacob [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Solis, Eunice Martinez [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-28

    Process exploration for fuel production for the High Flux Isotope Reactor (HFIR) using cast LEU-10wt.%Mo as an initial processing step has just begun. This project represents the first trials concerned with casting design and quality. The studies carried out over the course of this year and information contained in this report address the initial mold development to be used as a starting point for future operations. In broad terms, the final billet design is that of a solid rolling blank with an irregular octagonal cross section. The work covered here is a comprehensive view of the initial attempts to produce a sound casting. This report covers the efforts to simulate, predict, cast, inspect, and revise the initial mold design.

  4. Lifetime Reliability Assessment of Concrete Slab Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    A procedure for lifetime assesment of the reliability of short concrete slab bridges is presented in the paper. Corrosion of the reinforcement is the deterioration mechanism used for estimating the reliability profiles for such bridges. The importance of using sensitivity measures is stressed...

  5. Scattering by a slab: an exact calculation

    Czech Academy of Sciences Publication Activity Database

    Bentosela, F.; Tater, Miloš

    2005-01-01

    Roč. 38, č. 22 (2005), s. 4835-4841 ISSN 0305-4470 R&D Projects: GA AV ČR IAA100480501 Institutional research plan: CEZ:AV0Z10480505 Keywords : scattering by a slab Subject RIV: BE - Theoretical Physics Impact factor: 1.566, year: 2005

  6. All-polymer photonic crystal slab sensor

    DEFF Research Database (Denmark)

    Hermannsson, Pétur Gordon; Sørensen, Kristian Tølbøl; Vannahme, Christoph

    2015-01-01

    An all-polymer photonic crystal slab sensor is presented, and shown to exhibit narrow resonant reflection with a FWHM of less than 1 nm and a sensitivity of 31 nm/RIU when sensing media with refractive indices around that of water. This results in a detection limit of 4.5x10-6 RIU when measured i...

  7. Numerical Evaluations of Functionally Graded RC Slabs

    Directory of Open Access Journals (Sweden)

    M. Mastali

    2014-01-01

    Full Text Available Nowadays, using fibrous materials is used widely in strengthening applications such as cross-section enlargement and using functionally graded reinforced concrete. Functionally graded reinforced concrete is used as multireinforced concrete layers that can be reinforced by different fiber types. The objective of this research was to address the structural benefits of functionally graded concrete materials by performing analytical simulations. In order to achieve this purpose, in the first stage of this study, three functionally graded reinforced concretes by steel and polypropylene (PP were experimentally tested under flexural loading. Inverse analysis was applied to obtain the used material properties of reinforced concrete by FEMIX software. After obtaining the material properties, to assess the performance of proposed slabs, some other cases were proposed and numerically evaluated under flexural and shear loading. The results showed that increasing steel fiber in reinforced entire cross section led to achieve better shear and flexural performance while the best performance of reinforced functionally graded slabs was achieved for slab at 1% fiber content. In the second stage, nineteen reinforced functionally graded RC slabs with steel bars were simulated and assessed and some other cases were considered which were not experimentally tested.

  8. Development Length for Headed Bars in Slab-Column Joints of RC Slab Bridges

    Science.gov (United States)

    2015-12-04

    In accordance with the Caltrans Seismic Design Criteria, the superstructure in a slab bridge should remain essentially elastic and only the pile extensions/columns are permitted to develop inelastic deformations during a seismic event. Hence, the lon...

  9. Modified bond model for shear in slabs under concentrated loads

    NARCIS (Netherlands)

    Lantsoght, E.O.L.; Van der Veen, C.; De Boer, A.

    2015-01-01

    Slabs subjected to concentrated loads close to supports, as occurring for truck loads on slab bridges, are less studied than beams in shear or slab-column connections in punching. To predict the shear capacity for this case, the Bond Model for concentric punching shear was studied initially.

  10. Control of exceptional points in photonic crystal slabs

    DEFF Research Database (Denmark)

    Kaminski, Piotr Marek; Taghizadeh, Alireza; Breinbjerg, Olav

    2017-01-01

    Various ways of controlling the extent of the ring of exceptional points in photonic crystal slabs are investigated. The extent of the ring in photonic crystal slabs is found to vary with the thickness of the slab. This enables recovery of Dirac cones in open, non-Hermitian systems, such as a pho...

  11. Slab detachment of subducted Indo-Australian plate beneath Sunda ...

    Indian Academy of Sciences (India)

    ... complicate the subduction zone processes and slab architecture. Based on evidences which include patterns of seismicity, seismic tomography and geochemistry of arc volcanoes, we have identified a horizontal slab tear in the subducted Indo-Australian slab beneath the Sunda arc. It strongly reflects on trench migration, ...

  12. Modelling the solidification of ductile cast iron parts with varying wall thicknesses

    DEFF Research Database (Denmark)

    Bjerre, Mathias Karsten; Tiedje, Niels Skat; Thorborg, Jesper

    2015-01-01

    In the present paper modelling the solidification of cast iron parts is considered. Common for previous efforts in this field is that they have mainly considered thin walled to medium thickness castings. Hence, a numerical model combining the solidification model presented by Lesoultet al. [1] wi...

  13. Influence of slab length on dynamic characteristics of subway train-steel spring floating slab track-tunnel coupled system

    OpenAIRE

    Xu, Qing-yuan; Yan, Bin; Lou, Ping; Zhou, Xiao-lin

    2015-01-01

    A subway train-steel spring floating slab track-tunnel coupling dynamic model, considering short and middle-long wavelength random track irregularities, and longitudinal connection between adjacent slabs of steel spring floating slab track, was developed. And the influence of slab length on dynamic characteristics of the system under different track conditions and train speeds are theoretically studied. The calculated results show: (1) In general, the acceleration of each component of the cou...

  14. Influence of Temperature and Rolling Speed on Twin Roll Cast Strip

    Science.gov (United States)

    Kurz, G.; Bohlen, J.; Stutz, L.; Letzig, D.; Kainer, K. U.

    Reducing vehicle weight and emissions by lightweight design is a major goal of the automotive industry. Magnesium as the lightest structural metal offers a significant weight saving potential compared to steel and aluminum. Cast magnesium components are widely used, e.g. as engine blocks or gear box housings. The application of magnesium sheets is currently hampered by the low formability of magnesium which means that a large number of rolling passes is required to roll a DC cast slab to final gauge sheet. This large number of rolling steps is the main reason for the high cost of magnesium sheets. An alternative, cost-efficient production route for magnesium sheets with improved properties is feedstock production by twin roll casting (TRC). In this paper we report the results of twin roll casting experiments on the magnesium alloy AZ31 (Mg-3Al-lZn-Mn) and discuss the influence of the process on the micro structure and texture of the strips.

  15. Optical Intensity Modulation in an LiNbO3 Slab-Coupled Waveguide

    Directory of Open Access Journals (Sweden)

    Yalin Lu

    2008-01-01

    Full Text Available Optical intensity modulation has been demonstrated through switching the optical beam between the main core waveguide and a closely attached leaky slab waveguide by applying a low-voltage electrical field. Theory for simulating such an LiNbO3 slab-coupled waveguide structure was suggested, and the result indicates the possibility of making the spatial guiding mode large, circular and symmetric, which further allows the potential to significantly reduce the coupling losses with adjacent lasers and optical networks. Optical intensity modulation using electro-optic effect was experimentally demonstrated in a 5 cm long waveguide fabricated by using a procedure of soft proton exchange and then an overgrowth of thin LN film on top of a c-cut LiNbO3 wafer.

  16. Analysis of the impact of an aircraft crash on underground concrete ducts with protective slab at reactor buildings

    International Nuclear Information System (INIS)

    Kotulla, B.; Hansson, V.

    1977-01-01

    In this paper different types of idealization for a dynamic analysis of underground concrete ducts with protective slab are discussed and compared. Ducts between reactor and control building of a nuclear power plant are to be designed for loadings produced by an aircraft crash. These ducts have a height of about three to four meters and are two to eight meters wide. They are designed with a protective slab about 1.5 m in thickness at ground level and with an intermediate layer of earth of about one meter in thickness. An analysis has to take into account the combined effects of a protective slab with a relatively thin intermediate layer of earth and the underlaying duct and layer of soil with the nonlinear behavior of concrete due to cracking. For describing this behavior two types of idealization were made. One type is a continuum type calculation which describes the slab, the soil and the duct by finite elements. In the other type of idealization a model consisting of springs and lumped masses is used. The protective slab and the intermediate layer of earth may be described as a plate on elastic foundation. The behavior of the cracked part of the plate and the part of earth layer beneath and loads transferred to the uncracked part of the slab and the surrounding soil may be described by parallel springs. Spring and mass of this part of the model have to take into account the cracking of the upper slab which leads to a nonlinear characteristic of the spring. In addition the location of the loading in relation to the duct has to be considered. The duct may be described by a beam on elastic foundation which is loaded locally. From this model representative mass and spring have to be determined

  17. Trench dynamics: Effects of dynamically migrating trench on subducting slab morphology and characteristics of subduction zones systems

    Science.gov (United States)

    Yoshida, Masaki

    2017-07-01

    Understanding the mechanisms of trench migration (retreat or advance) is crucial to characterizing the driving forces of Earth's tectonics plates, the origins of subducting slab morphologies in the deep mantle, and identifying the characteristics of subduction zones systems, which are among the fundamental issues of solid Earth science. A series of numerical simulations of mantle convection, focusing on plate subduction in a three-dimensional (3-D) regional spherical shell coordinate system, was performed to examine subduction zone characteristics, including geodynamic relationships among trench migration, back-arc stress, and slab morphology. The results show that a subducting slab tends to deflect around the base of the mantle transition zone and form a sub-horizontal slab because its front edge (its 'toe') is subject to resistance from the highly viscous lower mantle. As the sub-horizontal slab starts to penetrate into the lower mantle from its 'heel,' the toe of the slab is drawn into the lower mantle. The results for models with dynamically migrating trenches suggest that trench retreat is the dynamically self-consistent phenomenon in trench migration. The reason for this is that the strong lateral mantle flow that is generated as a sequence of events leading from corner flow at the subduction initiation to return flow of the formation of a sub-horizontal slab in the shallower part of mantle wedge produces the retreat of the subducting slab. In fact, a 'mantle suction force,' which is generated in the mantle wedge to fill space left by the retreating subducting plate, is enhanced by the subsequent trench retreat. Even when upwelling flow with significant positive buoyancy originates just above a mantle phase boundary at a depth of 410 km (as inferred from independent seismic tomographic, geodynamic, geochemical, and mineral physics), reaches the base of the overriding plate, and the overriding plate is slightly thinned, lithospheric stress tends to be

  18. Sliding interleaved kY (SLINKY) acquisition: a novel 3D MRA technique with suppressed slab boundary artifact.

    Science.gov (United States)

    Liu, K; Rutt, B K

    1998-01-01

    This work addresses the elimination of the slab boundary artifact (SBA) or venetian blind artifact in three-dimensional multiple overlapped thin slab acquisition (3D MOTSA) for magnetic resonance angiography (MRA). Our method uses a sliding-slab, interleaved kY (SLINKY) data acquisition strategy, equalizing flow-related signal intensity weighting across the entire slab dimension. This technique demodulates signal intensity changes along the slab direction and can essentially eliminate the SBA while retaining the same or better imaging time efficiency than that of conventional MOTSA, providing robustness to complicated flow patterns and thereby resulting in more accurate depiction of vascular morphology. In addition, this technique does not need specialized reconstruction and extra computation. The unique penalty of this technique is the sensitivity to phase inconsistency in the data. Both phantom and in vivo experiments verify the clinical significance of the technique. The new MRA images acquired with this imaging technique show highly reliable mapping of vascular morphology without the SBA and reduction of signal voids in complex/slow flow regions.

  19. Tectonic Stacking of HP/LT Metamorphic Rocks in Accretionary Wedges and the Role of Shallowing Slab-Mantle Decoupling

    Science.gov (United States)

    Aygül, Mesut; Oberhänsli, Roland

    2017-11-01

    High-pressure/low-temperature (HP/LT) chloritoid-bearing micaschists crop out widely in the central part of northern Turkey and represent deep-seated subduction-accretionary complexes. Three peak metamorphic assemblages are identified in the area studied: (1) garnet-chloritoid-glaucophane with pseudomorphs after lawsonite; (2) chloritoid with pseudomorphs after glaucophane; and (3) chloritoid with pseudomorphs after jadeite in addition to phengite, paragonite, quartz, chlorite, rutile, and apatite. The latter is interpreted as transformation of a chloritoid + glaucophane assemblage to chloritoid + jadeite with increasing pressure; PT modeling indicates 17 and 22-25 kbars for the two peak parageneses. The diversity of peak metamorphic assemblages and the PT estimates suggest that basal accretion occurred at different depths within the wedge. The depth of the basal accretion is possibly controlled by the slab-mantle decoupling depth. Stretching and thinning of the lithospheric fore arc induced by the slab rollback possibly caused shallowing of the slab-mantle decoupling depth which limited depth of the basal accretion from 70-80 km to 55 km within the subduction channel. A slab-mantle coupling depth-controlled basal accretion may also explain the scarcity of eclogite and high-grade blueschist facies metamorphic rocks in active intraoceanic subduction zones. Because the overriding plate is young and hot in intraoceanic subductions, the slab and mantle are coupled at a relatively shallow depth before eclogitization of the oceanic crust. This prevents accretion and exhumation of eclogite along the subduction channel.

  20. Novel Radon Sub-Slab Suctioning System

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn

    2013-01-01

    A new principle for radon protection is currently presented which makes use of a system of horizontal pressurised air ducts located within the lower part of the rigid insulation layer of the ground-floor slab. The function of this system is based on the principles of pressure reduction within...... a grid of horizontal air ducts with low pressure which are able to remove air and radon from the ground. Results showed the system to be effective in preventing radon infiltrating from the ground through the ground-floor slab, avoiding high concentrations of radon being accumulated inside houses....... For the system to be effective, the pressure within the ducts must be lower than the pressure inside the house. The new principle was shown to be effective in preventing radon from polluting the indoor air by introducing low pressure in the horizontal grid of air ducts. A lower pressure than the pressure inside...

  1. Melt Cast High Explosives

    Directory of Open Access Journals (Sweden)

    Stanisław Cudziło

    2014-12-01

    Full Text Available [b]Abstract[/b]. This paper reviews the current state and future developments of melt-cast high explosives. First the compositions, properties and methods of preparation of trinitrotoluene based (TNT conventional mixtures with aluminum, hexogen (RDX or octogen (HMX are described. In the newer, less sensitive explosive formulations, TNT is replaced with dinitroanisole (DNANDNANDNAN and nitrotriazolone (NTONTONTO, nitroguanidine (NG or ammonium perchlorate (AP are the replacement for RDRDX and HMX. Plasticized wax or polymer-based binder systems for melt castable explosives are also included. Hydroxyl terminated polybutadiene (HPTB is the binder of choice, but polyethylene glycol, and polycaprolactone with energetic plasticizers are also used. The most advanced melt-cast explosives are compositions containing energetic thermoplastic elastomers and novel highly energetic compounds (including nitrogen rich molecules in whose particles are nanosized and practically defect-less.[b]Keywords[/b]: melt-cast explosives, detonation parameters

  2. Fast Waves in Smooth Coronal Slab

    Science.gov (United States)

    Lopin, I.; Nagorny, I.

    2015-03-01

    This work investigates the effect of transverse density structuring in coronal slab-like waveguides on the properties of fast waves. We generalized previous results obtained for the exponential and Epstein profiles to the case of an arbitrary transverse density distribution. The criteria are given to determine the possible (trapped or leaky) wave regime, depending on the type of density profile function. In particular, there are plasma slabs with transverse density structuring that support pure trapped fast waves for all wavelengths. Their phase speed is nearly equal to the external Alfvén speed for the typical parameters of coronal loops. Our findings are obtained on the basis of Kneser’s oscillation theorem. To confirm the results, we analytically solved the wave equation evaluated at the cutoff point and the original wave equation for particular cases of transverse density distribution. We also used the WKB method and obtained approximate solutions of the wave equation at the cutoff point for an arbitrary transverse density profile. The analytic results were supplemented by numerical solutions of the obtained dispersion relations. The observed high-quality quasi-periodic pulsations of flaring loops are interpreted in terms of the trapped fundamental fast-sausage mode in a slab-like coronal waveguide.

  3. Comparison of marginal accuracy of castings fabricated by conventional casting technique and accelerated casting technique: an in vitro study.

    Science.gov (United States)

    Reddy, S Srikanth; Revathi, Kakkirala; Reddy, S Kranthikumar

    2013-01-01

    Conventional casting technique is time consuming when compared to accelerated casting technique. In this study, marginal accuracy of castings fabricated using accelerated and conventional casting technique was compared. 20 wax patterns were fabricated and the marginal discrepancy between the die and patterns were measured using Optical stereomicroscope. Ten wax patterns were used for Conventional casting and the rest for Accelerated casting. A Nickel-Chromium alloy was used for the casting. The castings were measured for marginal discrepancies and compared. Castings fabricated using Conventional casting technique showed less vertical marginal discrepancy than the castings fabricated by Accelerated casting technique. The values were statistically highly significant. Conventional casting technique produced better marginal accuracy when compared to Accelerated casting. The vertical marginal discrepancy produced by the Accelerated casting technique was well within the maximum clinical tolerance limits. Accelerated casting technique can be used to save lab time to fabricate clinical crowns with acceptable vertical marginal discrepancy.

  4. Ceramic tape casting: A review of current methods and trends with emphasis on rheological behaviour and flow analysis

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Bulatova, Regina; Tok, A. I Y

    2016-01-01

    Tape casting has been used to produce thin layers of ceramics that can be used as single layers or can be stacked and laminated into multilayered structures. Today, tape casting is the basic fabrication process that provides multilayered capacitors and multilayered ceramic packages. In tape casting...... fluid flow analysis of tape casting. In the present paper a review of the development of the tape casting process with particular focus on the rheological classifications as well as modelling the material flow is hence presented and in this context the current status is examined and future potential...

  5. Viscous Dissipation and Criticality of Subducting Slabs

    Science.gov (United States)

    Riedel, Mike; Karato, Shun; Yuen, Dave

    2016-04-01

    Rheology of subducting lithosphere appears to be complicated. In the shallow part, deformation is largely accomodated by brittle failure, whereas at greater depth, at higher confining pressures, ductile creep is expected to control slab strength. The amount of viscous dissipation ΔQ during subduction at greater depth, as constrained by experimental rock mechanics, can be estimated on the basis of a simple bending moment equation [1,2] 2ɛ˙0(z) ∫ +h/2 2 M (z) = h ṡ -h/2 4μ(y,z)y dy , (1) for a complex multi-phase rheology in the mantle transition zone, including the effects of a metastable phase transition as well as the pressure, temperature, grain-size and stress dependency of the relevant creep mechanisms; μ is here the effective viscosity and ɛ˙0(z) is a (reference) strain rate. Numerical analysis shows that the maximum bending moment, Mcrit, that can be sustained by a slab is of the order of 1019 Nm per m according to Mcrit˜=σp ∗h2/4, where σp is the Peierl's stress limit of slab materials and h is the slab thickness. Near Mcrit, the amount of viscous dissipation grows strongly as a consequence of a lattice instability of mantle minerals (dislocation glide in olivine), suggesting that thermo-mechanical instabilities become prone to occur at places where a critical shear-heating rate is exceeded, see figure. This implies that the lithosphere behaves in such cases like a perfectly plastic solid [3]. Recently available detailed data related to deep seismicity [4,5] seems to provide support to our conclusion. It shows, e.g., that thermal shear instabilities, and not transformational faulting, is likely the dominating mechanism for deep-focus earthquakes at the bottom of the transition zone, in accordance with this suggested "deep criticality" model. These new findings are therefore briefly outlined and possible implications are discussed. References [1] Riedel, M. R., Karato, S., Yuen, D. A. Criticality of Subducting Slabs. University of Minnesota

  6. Machine Casting of Ferrous Alloys

    Science.gov (United States)

    1974-10-01

    Figure 55 Die casting machine. Shot sleeve at S, melt furnace at M, ladle preheat at L. Figure 56 Aluminum die casting top surface. Risers removed... ladle and transferred to the shot sleeve. Upon pouring the metal, the ram is actuated and the casting made. To test the mechanical operation of...mnui i .MI iiiiiuH ’ -84- Figure 55. Die casting machine. Shot sleeve at S, melt furnace at M, ladle preheat at L. ■ ■ wmmm*mm

  7. Segregation in cast products

    Indian Academy of Sciences (India)

    Unknown

    are also available (Moore 1984; Ohnaka 1988; Flemings 1990; Roy et al 1992; Ghosh. 1997). In addition, some recent research papers will also be referred to as required. Original references of earlier studies are omitted for the sake of brevity. The basic principles of formation of microsegregation in castings and ingots were.

  8. ToxCast Dashboard

    Science.gov (United States)

    The ToxCast Dashboard helps users examine high-throughput assay data to inform chemical safety decisions. To date, it has data on over 9,000 chemicals and information from more than 1,000 high-throughput assay endpoint components.

  9. Wear resistance of cast iron

    OpenAIRE

    S. Pietrowski; G. Gumienny

    2008-01-01

    In this paper investigations of abrasive and adhesive wear resistance of different cast iron grades have been presented. Examinations showed, that the most advantageous pair of materials is the cast iron – the hardened steel with low-tempered martensite. It was found, that martensitic nodular cast iron with carbides is the most resistant material.

  10. Evidence of fire resistance of hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes) are predo......Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes....... The present paper analyses the evidence now available for assessment of the fire resistance of extruded hollow-core slabs. The 162 fire tests from the Holcofire report are compared against the requirements for testing from the product standard for hollow-core slabs EN1168 and knowledge about the possible...

  11. A STUDY ON THE WHEELSET/SLAB TRACK VERTICAL INTERACTION

    Directory of Open Access Journals (Sweden)

    Traian MAZILU

    2012-05-01

    Full Text Available This paper deals with the interaction between a moving wheelset and a slab track due to the short-pitch corrugated rail. The wheelset is modeled using a free-free Timoshenko beam with attached rigid bodies as the axle boxes, wheels and brake discs. The slab track model consists of elastically supported double Euler-Bernoulli beams. In fact, both wheelset and slab track are symmetric structures and the issue of the wheelset/slab track interaction is reduced to the wheel/rail interaction. The nonlinear equations of motion describing the wheelset/slab track interaction due to the short-pitch corrugated rail are solved using the time-domain Green’s functions method and the convolution theorem. The wheelset/slab track interaction due to the short-pitch corrugated rail exhibits a critical velocity when the vibration reaches the maximum level

  12. Subdiffraction-limited imaging based on longitudinal modes in a spatially dispersive slab

    Science.gov (United States)

    Yanai, Avner; Levy, Uriel

    2014-08-01

    It was proposed that a flat silver layer could be used to form a subdiffraction-limited image when illuminated near its surface plasmon resonance frequency [J. B. Pendry, Phys. Rev. Lett. 85, 3966 (2000), 10.1103/PhysRevLett.85.3966]. In this paper, we study the possibility of obtaining sub diffraction resolution using a different mechanism, with no surface plasmons involved. Instead, by taking into account the nonlocal response of a thin silver slab, we show that longitudinal modes contribute to the formation of a subdiffraction-limited image in a frequency regime above the plasma frequency. The differences between these two distinct mechanisms are studied and explained.

  13. Hot Charging and Transporting to Continuous Discussion on Casting Slab at Tanggang

    Directory of Open Access Journals (Sweden)

    Dai Jun

    2017-01-01

    Full Text Available This paper introduces technological design and equipment of hot delivery and hot charge in Tanggang and Steel Co and its notable economic benefit.At the same ,the difficulty and problems in realizing hot delivery and charge are point out.

  14. Stress and Friction Distribution around Slab Corner in Continuous Casting Mold with Different Corner Structures

    Science.gov (United States)

    Yu, Sheng; Long, Mujun; Chen, Huabiao; Chen, Dengfu; Liu, Tao; Duan, Huamei; Cao, Junsheng

    2018-02-01

    The non-uniform friction and thermal stress in the mold are important as causes of the transverse cracks around strand corner. To analyze the stress distribution features around strand corner, a three-dimensional thermo-elastoplastic finite-element mold model with different corner structures (right-angle, big-chamfer, multi-chamfer, and fillet) was established. The temperature field in the mold was indirectly coupled through a three-dimensional fluid flow and heat transfer model. In addition, the non-uniform mold friction stress loaded on the strand surface was calculated through a friction model. The results show that the stress distribution on the shell is similar to the temperature distribution. The stress concentration appears in the strand corner and the lower part of wide face. The friction stress enhances the corner stress around the edge of the air-gap. For chamfered molds, the stress around the corner between the wide face and chamfer face is larger than that between the narrow face and chamfer face. Around the corner region, both the stress peak and the area of the large stress zone of the right-angle strand are the largest, while those of big-chamfered, multi-chamfered, and fillet strands decrease in that order. The stress peak position of the chamfered strands is closer to the mold exit than that of the right-angle strand. Compared with the use of the right-angle mold, the application of chamfered molds is able to reduce the stress concentration around the strand corner.

  15. Thermal degradation in Carrara marbles as the cause of deformation of cladding slabs

    Directory of Open Access Journals (Sweden)

    A. Spagnoli

    2014-10-01

    Full Text Available Marble slabs, typically used as façade panels to externally cover buildings, might permanently deform after a certain time of environmental exposure. This phenomenon, called bowing, is generally accompanied by a reduction of strength which increases with increasing degree of bowing. In the present paper, a theoretical model to calculate the progressive bowing of marble slabs submitted to temperature cycles is briefly recalled and applied to a specific Carrara marble sample. The marble is investigated by a microscopic analysis of thin sections cut along three orthogonal directions. The digital photographs are treated by an image analysis code which is capable of extracting grain size and shape distributions. In this way the anisotropic microstructure of the marble is quantified and taken into account in the numerical analyses. The influence of size distribution of grains as well as of their distribution of optic axis orientation on the slab bowing is discussed with the attempt of offering a quantitative tool for a better understanding of in situ bowing measurements.

  16. CFRP strengthened openings in two-way concrete slabs

    DEFF Research Database (Denmark)

    Enochsson, O.; Lundqvist, J.; Täljsten, Björn

    2006-01-01

    Rehabilitation and strengthening of concrete structures with externally bonded fibre reinforced polymers (FRPs) has been a viable technique for at least a decade. An interesting and useful application is strengthening of slabs or walls where openings are introduced. In these situations, FRP sheets....... In this paper, laboratory tests on I I slabs with openings, loaded with a distributed load are presented together with analytical and numerical evaluations. Six slabs with openings have been strengthened with carbon fibre reinforced polymers (CFRPs) sheets. These slabs are compared with traditionally steel...

  17. STRUCTURAL TEST AND ANALYSIS OF RC SLAB AFTER FIRE LOADING

    Directory of Open Access Journals (Sweden)

    CHUL-HUN CHUNG

    2013-04-01

    Full Text Available In the present study the behavior of fire and the residual strength of fire-ignited RC slabs are investigated by experimental tests and numerical simulations. The fire tests of RC slabs were carried out in a furnace using the ISO 834 standard fire. The load capacity of the cooled RC slabs that were not loaded during the fire tests was evaluated by additional 3 point bending tests. The influence of the proportion of PP (polypropylene fibers in the RC slabs on the structural behavior of the RC slabs after the fire loading was investigated. The results of the fire tests showed that the maximum temperature of concrete with PP fiber was lower than that of concrete without PP fiber. As the concrete was heated, the ultimate compressive strength decreased and the ultimate strain increased. The load-deflection relations of RC slabs after fire loading were compared by using existing stress-strain-temperature models. The comparison between the numerical analysis and the experimental tests showed that some numerical analyses were reliable and therefore, can be applied to evaluate the ultimate load of RC slabs after fire loading. The ultimate load capacity after cooling down the RC slabs without PP fiber showed a considerable reduction from that of the RC slabs with PP fiber.

  18. Structural Test and Analysis of RC Slab After Fire Loading

    International Nuclear Information System (INIS)

    Chung, Chulhun; Im, Cho Rong; Park, Jaegyun

    2013-01-01

    In the present study the behavior of fire and the residual strength of fire-ignited RC slabs are investigated by experimental tests and numerical simulations. The fire tests of RC slabs were carried out in a furnace using the ISO 834 standard fire. The load capacity of the cooled RC slabs that were not loaded during the fire tests was evaluated by additional 3 point bending tests. The influence of the proportion of PP (polypropylene) fibers in the RC slabs on the structural behavior of the RC slabs after the fire loading was investigated. The results of the fire tests showed that the maximum temperature of concrete with PP fiber was lower than that of concrete without PP fiber. As the concrete was heated, the ultimate compressive strength decreased and the ultimate strain increased. The load-deflection relations of RC slabs after fire loading were compared by using existing stress-strain-temperature models. The comparison between the numerical analysis and the experimental tests showed that some numerical analyses were reliable and therefore, can be applied to evaluate the ultimate load of RC slabs after fire loading. The ultimate load capacity after cooling down the RC slabs without PP fiber showed a considerable reduction from that of the RC slabs with PP fiber

  19. A STUDY ON THE WHEELSET/SLAB TRACK VERTICAL INTERACTION

    OpenAIRE

    Traian MAZILU

    2012-01-01

    This paper deals with the interaction between a moving wheelset and a slab track due to the short-pitch corrugated rail. The wheelset is modeled using a free-free Timoshenko beam with attached rigid bodies as the axle boxes, wheels and brake discs. The slab track model consists of elastically supported double Euler-Bernoulli beams. In fact, both wheelset and slab track are symmetric structures and the issue of the wheelset/slab track interaction is reduced to the wheel/rail interaction. The n...

  20. Reconstructing subducted oceanic lithosphere by “reverse-engineering” slab geometries : The northern Philippine Sea Plate

    NARCIS (Netherlands)

    Pownall, Jonathan M.; Lister, Gordon S.; Spakman, Wim|info:eu-repo/dai/nl/074103164

    Subducting slabs commonly acquire complex geometries from the migration of subduction trenches, slab-mantle interaction, slab tearing, and collision of slabs at depth. Although it is possible to construct three-dimensional models of subducted slabs using earthquake hypocenter locations and

  1. Slab thickness tuning approach for solid-state strong coupling between photonic crystal slab nanocavity and a quantum dot.

    Science.gov (United States)

    Chen, Gengyan; Liu, Jing-Feng; Jiang, Haoxiang; Zhuo, Xiao-Lu; Yu, Yi-Cong; Jin, Chongjun; Wang, Xue-Hua

    2013-04-23

    The quality factor and mode volume of a nanocavity play pivotal roles in realizing the strong coupling interaction between the nanocavity mode and a quantum dot. We present an extremely simple method to obtain the mode volume and investigate the effect of the slab thickness on the quality factor and mode volume of photonic crystal slab nanocavities. We reveal that the mode volume is approximatively proportional to the slab thickness. As compared with the previous structure finely optimized by introducing displacement of the air holes, via tuning the slab thickness, the quality factor can be enhanced by about 22%, and the ratio between the coupling coefficient and the nanocavity decay rate can be enhanced by about 13%. This can remarkably enhance the capability of the photonic crystal slab nanocavity for realizing the strong coupling interaction. The slab thickness tuning approach is feasible and significant for the experimental fabrication of the solid-state nanocavities.

  2. Behavior of Partially Restrained Reinforced Concrete Slabs.

    Science.gov (United States)

    1986-09-01

    1assiied 22a NAME OF RESPONSIBLE INDIVIDUAL 22b TELEPHONE (Include Area Code) 22c OFFICE SYMBOL DO FORM 1473, 84 MAR 83 APR edition may be used untI...Takehira, Derecho , and Iqbal [34] followed a similar approach to arrive at recommended design criteria for 1 the Naval Facilities Engineering Command...Compression in./in. Slab STI ST2 ST3 SSB - ___2 SB3_ CT _CB3 1 BC+ - C- CD+ - AB+ 0.0005 0.009 2 BC+ D+ - DE + AB+ AB+ 3 BC+ DE + CD+ D+ AB+ AB+ 0.011

  3. STRUCTURE FORMATION IN FOUNDATION SLAB CONCRETE

    Directory of Open Access Journals (Sweden)

    V. V. Kovalenko

    2016-04-01

    Full Text Available Purpose. The work involves identifying the dependence of structural and mechanical properties of the concrete on the composition of used modifier additives, the nature of changes of structural and mechanical properties depending on the period of concrete hardening of test and modified samples. Methodology. The applied microstructural, fractographic, microprobe analyses and physico-mechanical tests revealed the required dependencies. Findings. The microstructure of the cement stone under equal conditions of concrete mix selection depends on the composition of used raw materials and production technology. This paper investigates the structural changes in the setting time of hard mixture concrete and effect of component parts of the complex modifier additive PLKP (produced by «Logia», Dnepropetrovsk on morphology, dispersion and chemical composition of the cement stone, as well as the mechanical characteristics of concrete for the foundation slab. The study of the structural and physical-mechanical characteristics of the test samples and modified concrete at various hardening stages showed that the use Ukrainian hyper-plasticizer PLKP contributes to the formation of nano-structured concrete. The addition of hardening accelerators to the super-plasticizer additive reduces the diameter of crystal whiskers, increases the structural homogeneity and stability and improves the complex of the concrete mechanical characteristics. Application of new PLKP polycarboxylate additives in the production of concrete mixtures for the foundation slab allows eliminating the steaming from the foundation slab production technology. The absence of salt component in the additive improves the concrete durability. Originality. The paper showed that modification of the concrete with complex additive PLKP facilitates the formation of the most homogeneous structure of cement stone, which consists of compact crystals surrounded by fibrous crystals that are tightly

  4. Cast iron - a predictable material

    Directory of Open Access Journals (Sweden)

    Jorg C. Sturm

    2011-02-01

    Full Text Available High strength compacted graphite iron (CGI or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications. The mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron castings. New products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast components. During the last 20 years, casting process simulation has developed from predicting hot spots and solidification to an integral assessment tool for foundries for the entire manufacturing route of castings. The support of the feeding related layout of the casting is still one of the most important duties for casting process simulation. Depending on the alloy poured, different feeding behaviors and self-feeding capabilities need to be considered to provide a defect free casting. Therefore, it is not enough to base the prediction of shrinkage defects solely on hot spots derived from temperature fields. To be able to quantitatively predict these defects, solidification simulation had to be combined with density and mass transport calculations, in order to evaluate the impact of the solidification morphology on the feeding behavior as well as to consider alloy dependent feeding ranges. For cast iron foundries, the use of casting process simulation has become an important instrument to predict the robustness and reliability of their processes, especially since the influence of alloying elements, melting practice and metallurgy need to be considered to quantify the special shrinkage and solidification behavior of cast iron. This allows the prediction of local structures, phases and ultimately the local mechanical properties of cast irons, to asses casting quality in the foundry but also to make use of this quantitative information during design of the casting. Casting quality issues related to thermally driven

  5. Sub-slab vs. Near-slab Soil Vapor Profiles at a Chlorinated Solvent Site (1)

    Science.gov (United States)

    A critical issue in assessing the vapor intrusion pathway is the distribution and migration of VOCs from the subsurface source to the near surface environment. Of particular importance is the influence of a slab. Therefore, EPA/ORD is funding a research program with the primary...

  6. Slab temperature controls on the Tonga double seismic zone and slab mantle dehydration.

    Science.gov (United States)

    Wei, S Shawn; Wiens, Douglas A; van Keken, Peter E; Cai, Chen

    2017-01-01

    Double seismic zones are two-layered distributions of intermediate-depth earthquakes that provide insight into the thermomechanical state of subducting slabs. We present new precise hypocenters of intermediate-depth earthquakes in the Tonga subduction zone obtained using data from local island-based, ocean-bottom, and global seismographs. The results show a downdip compressional upper plane and a downdip tensional lower plane with a separation of about 30 km. The double seismic zone in Tonga extends to a depth of about 300 km, deeper than in any other subduction system. This is due to the lower slab temperatures resulting from faster subduction, as indicated by a global trend toward deeper double seismic zones in colder slabs. In addition, a line of high seismicity in the upper plane is observed at a depth of 160 to 280 km, which shallows southward as the convergence rate decreases. Thermal modeling shows that the earthquakes in this "seismic belt" occur at various pressures but at a nearly constant temperature, highlighting the important role of temperature in triggering intermediate-depth earthquakes. This seismic belt may correspond to regions where the subducting mantle first reaches a temperature of ~500°C, implying that metamorphic dehydration of mantle minerals in the slab provides water to enhance faulting.

  7. Vibration improved the fluidity of aluminum alloys in thin wall ...

    African Journals Online (AJOL)

    Misrun is a term used to describe the incomplete filling of the mould cavity. It is a major defect in the investment casting process when used to produce turbine blades, impellers and impulse blades for turbo pumps which have complex profiles, thin walls and sharp edges. From the casting engineering point of view, poor ...

  8. Development of technology for thin substrate polycrystalline solar cells for practical use. Development of manufacturing technologies for low-cost substrates (low-cost Si sheets by continuous casting method); Usugata takessho taiyo denchi seizo gijutsu no jitsuyoka kenkyu. Tei cost kiban seizo gijutsu kaihatsu (renzoku cast ho ni yoru tei cost Si kiban seizo gijutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    Tatsuta, M. [New Energy and Industrial Technology Development Organization, Tokyo (Japan)

    1994-12-01

    This paper reports the study results on manufacturing of low-cost Si substrates by continuous casting method in fiscal 1994. (1) On manufacturing of ingots of 16 piece size, the ingot of nearly 170kg was manufactured by batch process using the Si melt injection unit prepared in last year. (2) On oxygen and carbon contents in wafers, the contents were measured by FT-IR after slicing of the ingot. As a result, the oxygen and carbon contents could be successfully reduced to the targets of 10ppma and 5ppma or less, respectively. (3) The resistivity distribution of the ingot ranged over the target of 1-2ohm-cm. (4) Cells of 100 {times} 100mm{sup 2} wide and 350{mu}m thick were verified by in-house evaluation process. Although lower cell conversion efficiency was found at the center top of the ingot, a vertical efficiency stability was nearly sufficient as a whole. (5) On the crystal growth unit prepared in fiscal 1994, any problems were not found on automatic driving and vibration during moving. 8 figs.

  9. Influence of weak layer heterogeneity and slab properties on slab tensile failure propensity and avalanche release area

    Science.gov (United States)

    Gaume, J.; Chambon, G.; Eckert, N.; Naaim, M.; Schweizer, J.

    2015-04-01

    Dry-snow slab avalanches are generally caused by a sequence of fracture processes, including failure initiation in a weak snow layer underlying a cohesive slab followed by crack propagation within the weak layer (WL) and tensile fracture through the slab. During past decades, theoretical and experimental work has gradually increased our knowledge of the fracture process in snow. However, our limited understanding of crack propagation and fracture arrest propensity prevents the evaluation of avalanche release sizes and thus impedes hazard assessment. To address this issue, slab tensile failure propensity is examined using a mechanically based statistical model of the slab-WL system based on the finite element method. This model accounts for WL heterogeneity, stress redistribution by slab elasticity and possible tensile failure of the slab. Two types of avalanche release are distinguished in the simulations: (1) full-slope release if the heterogeneity is not sufficient to stop crack propagation and trigger a tensile failure within the slab; (2) partial-slope release if fracture arrest and slab tensile failure occur due to the WL heterogeneity. The probability of these two release types is presented as a function of the characteristics of WL heterogeneity and the slab. One of the main outcomes is that, for realistic values of the parameters, the tensile failure propensity is mainly influenced by slab properties. Hard and thick snow slabs are more prone to wide-scale crack propagation and thus lead to larger avalanches (full-slope release). In this case, the avalanche size is mainly influenced by topographical and morphological features such as rocks, trees, slope curvature and the spatial variability of the snow depth as often claimed in the literature.

  10. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  11. Slab Profile Encoding (PEN) for Minimizing Slab Boundary Artifact in 3D Diffusion-Weighted Multislab Acquisition*

    Science.gov (United States)

    Van, Anh T; Aksoy, Murat; Holdsworth, Samantha J; Kopeinigg, Daniel; Vos, Sjoerd B; Bammer, Roland

    2014-01-01

    Purpose To propose a method for mitigating slab boundary artifacts in 3D multislab diffusion imaging with no or minimal increases in scan time. Methods The multislab acquisition was treated as parallel imaging acquisition where the slab profiles acted as the traditional receiver sensitivity profiles. All the slabs were then reconstructed simultaneously along the slab direction using Cartesian-based sensitivity encoding (SENSE) reconstruction. The slab profile estimation was performed using either a Bloch simulation or a calibration scan. Results Both phantom and in vivo results showed negligible slab boundary artifacts after reconstruction using the proposed method. The performance of the proposed method is comparable to the state-of-the-art slab combination method without the scan time penalty that depends on the number of acquired volumes. The obtained g-factor map of the SENSE reconstruction problem showed a maximum g-factor of 1.7 in the region of interest. Conclusion We proposed a novel method for mitigating slab boundary artifacts in 3D diffusion imaging by treating the multislab acquisition as a parallel imaging acquisition and reconstructing all slabs simultaneously using Cartesian SENSE. Unlike existing methods, the scan time increase, if any, does not scale with the number of image volumes acquired. PMID:24691843

  12. Slab profile encoding (PEN) for minimizing slab boundary artifact in three-dimensional diffusion-weighted multislab acquisition.

    Science.gov (United States)

    Van, Anh T; Aksoy, Murat; Holdsworth, Samantha J; Kopeinigg, Daniel; Vos, Sjoerd B; Bammer, Roland

    2015-02-01

    To propose a method for mitigating slab boundary artifacts in three-dimensional (3D) multislab diffusion imaging with no or minimal increases in scan time. The multislab acquisition was treated as parallel imaging acquisition where the slab profiles acted as the traditional receiver sensitivity profiles. All the slabs were then reconstructed simultaneously along the slab direction using Cartesian-based sensitivity encoding (SENSE) reconstruction. The slab profile estimation was performed using either a Bloch simulation or a calibration scan. Both phantom and in vivo results showed negligible slab boundary artifacts after reconstruction using the proposed method. The performance of the proposed method is comparable to the state-of-the-art slab combination method without the scan time penalty that depends on the number of acquired volumes. The obtained g-factor map of the SENSE reconstruction problem showed a maximum g-factor of 1.7 in the region of interest. We proposed a novel method for mitigating slab boundary artifacts in 3D diffusion imaging by treating the multislab acquisition as a parallel imaging acquisition and reconstructing all slabs simultaneously using Cartesian SENSE. Unlike existing methods, the scan time increase, if any, does not scale with the number of image volumes acquired. © 2014 Wiley Periodicals, Inc.

  13. Study on Mud Pumping Mechanism of Subgrade Surface Layer in Slab Ballastless Track Zone

    Directory of Open Access Journals (Sweden)

    Xiaopei CAI

    2015-03-01

    Full Text Available Mud pumping has a significant impact on dynamic behavior of high-speed railway. An elaborate study focused on the structure characteristics of CRTS I (China Railway Track System slab ballastless track was made to explain the mechanism of mud pumping from the aspects of displacement between the base plate and subgrade, gap growing, disfunction of drainage system and dynamic load of the train. Finite element software ABAQUS was applied to simulate the dynamic responses between the base plate and the subgrade surface layer in different conditions of gap length and gap size. It has been found that the dynamic force between the base plate and the surface layer of subgrade is up to 4,576.29 kN. Suggestions have been given to the related department such as slip-casting, white-out, sealing plug to solve the problem.

  14. Cast Aluminum Structures Technology (CAST) Phase VI. Technology Transfer.

    Science.gov (United States)

    1980-04-01

    o Metal preparation o Ladle fill o Pouring 0 Mold shakeout o Casting cleanup o Inspection o Weld correction o Heat treatment and straightening o...presents a summary of foundry data for the 10 Hitchcock cast - ings. Included are the ladle chemistry and the pouring date, temperature, and time for each...properties, and full range stress- strain curves to failure for each specimen d. Chemistry of molten metal in ladle for each casting 3.4.3.2 The foundry

  15. Accelerated slab replacement using temporary precast panels and self-consolidating concrete : [summary].

    Science.gov (United States)

    2016-06-01

    Researchers at Florida State University demonstrated the feasibility of using precast reinforced concrete panels to temporarily fill slab removal pits. The precast slabs can be driven on so traffic lanes can be open during the day, and new slab casti...

  16. Three-dimensional MRI with independent slab excitation and encoding.

    Science.gov (United States)

    Eissa, Amir; Wilman, Alan H

    2012-02-01

    Three-dimensional MRI is typically performed with the same orientation for radiofrequency slab excitation and slab select phase encoding. We introduce independent slab excitation and encoding to create a new degree of freedom in three-dimensional MRI, which is the angular relationship between the prescribed excitation volume and the voxel encoding grid. By separating the directions of slab excitation and slab phase encoding, the independent slab excitation and encoding method allows choice of optimal voxel orientation, while maintaining volume excitation based on anatomic landmarks. The method requires simple pulse sequence modifications and uses standard image reconstruction followed by removal of aliasing and image reformatting. The independent slab excitation and encoding method enables arbitrary oblique angle imaging using fixed voxel encoding gradients to maintain similar eddy current, concomitant field, or magnetic dipole effects independent of the oblique angle of excitation. We apply independent slab excitation and encoding to phase and susceptibility-weighted imaging using fixed voxel encoding aligned with the main magnetic field to demonstrate its value in both standardizing and improving image contrast, when using arbitrary oblique imaging volumes. Copyright © 2011 Wiley Periodicals, Inc.

  17. On Early Age Crack Formation in FRC Slabs

    DEFF Research Database (Denmark)

    Olesen, John Forbes; Stang, Henrik

    1997-01-01

    The problem of early age crack formation in FRC slabs due to restrained temperature and shrinkage deformations, is given an analytical treatment. A model taking into account the ageing properties of the tensile softening curve and the continued development in the temperature and shrinkage...... deformations after crack initiation, is presented. Based on this model a design strategy for FRC slabs is outlined....

  18. Fire resistance of extruded hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Giuliani, Luisa; Sørensen, Lars Schiøtt

    2016-01-01

    Prefabricated extruded hollow-core slabs are preferred building components for floor structures in several countries. It is therefore important to be able to document the fire resistance of these slabs proving fulfilment of standard fire resistance requirements of 60- and 120 minutes found in most...

  19. Fire resistance of extruded hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    2017-01-01

    Purpose – Prefabricated extruded hollow-core slabs are preferred building components for floor structures in several countries. It is therefore important to be able to document the fire resistance of these slabs proving fulfilment of standard fire resistance requirements of 60 and 120 min found...

  20. Shear capacity of slabs under a combination of loads

    NARCIS (Netherlands)

    Lantsoght, E.O.L.; Van der Veen, C.; Walraven, J.C.

    2013-01-01

    Existing solid slab bridges under a combination of wheel loads and distributed traffic loads sometimes do not fulfil the code requirements for shear. However, reinforced concrete slabs loaded close to the support are subjected to shear stresses which might result in a failure mode of combined

  1. Safety of Premature Loading on Reinforced Concrete Slabs | Shema ...

    African Journals Online (AJOL)

    ... two-thirds of its characteristic strength. The reliability indices of a prematurely loaded reinforced concrete slab in flexure are directly proportional to the characteristic strength of concrete. Therefore in practice, due consideration must be given to early-age strength development in reinforced concrete slabs before loading.

  2. Shear and Anchorage Behaviour of Fire Exposed Hollow Core Slabs

    NARCIS (Netherlands)

    Fellinger, J.H.H.

    2004-01-01

    Hollow core (HC) slabs are made of precast concrete with pretensioned strands. These slabs are popular as floor structures in offices and housing. At ambient conditions, the load bearing capacity can be dominated by four different failure modes, i.e. flexure, anchorage, shear compression and shear

  3. Shear and anchorage behaviour of fire exposed hollow core slabs

    NARCIS (Netherlands)

    Fellinger, J.H.H.; Stark, J.; Walraven, J.C.

    2005-01-01

    The fire resistance of hollow core slabs is currently assessed considering flexural failure only. However, fire tests showed that shear or anchorage failure can also govern the load bearing behaviour. As the shear and anchorage capacity of these slabs rely on the tensile strength of the concrete,

  4. Empirical Strengths of Concrete Roof Slabs After 34 Years Service ...

    African Journals Online (AJOL)

    This paper examines the strengths of four reinforced concrete roof slabs which have been in service for over 34years. The non-destructive test hammer was used to obtain data for the empirical determination of the practical strengths of the existing structures. A total of 110 tests were performed on each slab at 11 points ...

  5. Surface Waves Propagating on Grounded Anisotropic Dielectric Slab

    Directory of Open Access Journals (Sweden)

    Zhuozhu Chen

    2018-01-01

    Full Text Available This paper investigates the characteristics of surface waves propagating on a grounded anisotropic dielectric slab. Distinct from the existing analyses that generally assume that the fields of surface wave uniformly distribute along the transverse direction of the infinitely large grounded slab, our method takes into account the field variations along the transverse direction of a finite-width slab. By solving Maxwell’s equations in closed-form, it is revealed that no pure transverse magnetic (TM or transverse electric (TE mode exists if the fields are non-uniformly distributed along the transverse direction of the grounded slab. Instead, two hybrid modes, namely quasi-TM and quasi-TE modes, are supported. In addition, the propagation characteristics of two hybrid modes supported by the grounded anisotropic slab are analyzed in terms of the slab thickness, slab width, as well as the relative permittivity tensor of the anisotropic slab. Furthermore, different methods are employed to compare the analyses, as well as to validate our derivations. The proposed method is very suitable for practical engineering applications.

  6. Restoration of s-polarized evanescent waves and subwavelength imaging by a single dielectric slab

    International Nuclear Information System (INIS)

    El Gawhary, Omar; Schilder, Nick J; Costa Assafrao, Alberto da; Pereira, Silvania F; Paul Urbach, H

    2012-01-01

    It was predicted a few years ago that a medium with negative index of refraction would allow for perfect imaging. Although no material has been found so far that behaves as a perfect lens, some experiments confirmed the theoretical predictions in the near-field, or quasi-static, regime where the behaviour of a negative index medium can be mimicked by a thin layer of noble metal, such as silver. These results are normally attributed to the excitation of surface plasmons in the metal, which only leads to the restoration of p-polarized evanescent waves. In this work, we show that the restoration of s-polarized evanescent waves and, correspondingly, sub-wavelength imaging by a single dielectric slab are possible. Specifically, we show that at λ = 632 nm a thin layer of GaAs behaves as a superlens for s-polarized waves. Replacing the single-metal slab by a dielectric is not only convenient from a technical point of view, it being much easier to deposit and control the thickness and flatness of dielectric films than metal ones, but also invites us to re-think the connection between surface plasmon excitation and the theory of negative refraction. (paper)

  7. Fracture Mechanisms in Steel Castings

    Directory of Open Access Journals (Sweden)

    Stradomski Z.

    2013-09-01

    Full Text Available The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism of decohesion - the intergranular one - occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C revealed low or very low strength of high-carbon cast steels.

  8. Numerical Study of FRP Reinforced Concrete Slabs at Elevated Temperature

    Directory of Open Access Journals (Sweden)

    Masoud Adelzadeh

    2014-02-01

    Full Text Available One-way glass fibre reinforced polymer (GFRP reinforced concrete slabs at elevated temperatures are investigated through numerical modeling. Serviceability and strength requirements of ACI-440.1R are considered for the design of the slabs. Diagrams to determine fire endurance of slabs by employing “strength domain” failure criterion are presented. Comparisons between the existing “temperature domain” method with the more representative “strength domain” method show that the “temperature domain” method is conservative. Additionally, a method to increase the fire endurance of slabs by placing FRP reinforcement in two layers is investigated numerically. The amount of fire endurance gained by placing FRP in two layers increases as the thickness of slab increases.

  9. Shear strength of end slabs of prestressed concrete reactor vessels

    International Nuclear Information System (INIS)

    Cheung, K.C.; Gotschall, H.L.; Liu, T.C.

    1975-01-01

    Prestressed concrete reactor vessels (PCRV's) have been adopted for primary containments in most large high-temperature gas-cooled reactor installations. The most common configuration for PCRVs is a right-vertical cylinder with thick end slabs. In order to assess the integrity of a PCRV it is necessary to predict the ultimate strength of the end slabs. The complexity of the basic mechanism of shear failure in the PCRV end slabs has thus far prohibited the development of a completely analytical solution. However, many experimental investigations of PCRV end slabs have been conducted over the past decade. This information makes it possible to establish empirical formulae for the ultimate strength of PCRV end slabs. The basis and development of an empirical shear-flexure interaction expression is presented. (Auth.)

  10. Punching strength of reinforced concrete flat slabs without shear reinforcement

    Directory of Open Access Journals (Sweden)

    P. V. P. Sacramento

    Full Text Available Punching strength is a critical point in the design of flat slabs and due to the lack of a theoretical method capable of explaining this phenomenon, empirical formulations presented by codes of practice are still the most used method to check the bearing capacity of slab-column connections. This paper discusses relevant aspects of the development of flat slabs, the factors that influence the punching resistance of slabs without shear reinforcement and makes comparisons between the experimental results organized in a database with 74 slabs carefully selected with theoretical results using the recommendations of ACI 318, EUROCODE 2 and NBR 6118 and also through the Critical Shear Crack Theory, presented by Muttoni (2008 and incorporated the new fib Model Code (2010.

  11. Evaluation of dynamic behavior of waffle slab to gym center

    Directory of Open Access Journals (Sweden)

    Yuri Cláudio Vieira da Costa

    Full Text Available In Brazil, the use of reinforced concrete waffle slab in multi-story buildings is widespread nowadays. These buildings are projected for different purposes such as fitness centers, supermarkets, parking garages, offices and residential units. Simple activities as walking, skipping and jumping can generate vibrations in these slabs. Vibrations can cause inconvenience in persons, questions about structure´s safety, and collapse risk that it is determined by its intensity of vibrations. The objective of this paper is evaluating the behavior of reinforced concrete waffle slabs due to the human rhythmic activities. Slabs are modeled by finite elements method using the SAP2000 program. The results are verified according to Brazilian and international codes. The waffle slabs are submitted to high-levels of acceleration and velocity generating discomfort in users.

  12. Characterizing wet slab and glide slab avalanche occurrence along the Going-to-the-Sun Road, Glacier National Park, Montana, USA

    Science.gov (United States)

    Peitzsch, Erich H.; Hendrikx, Jordy; Fagre, Daniel B.; Reardon, Blase

    2010-01-01

    Wet slab and glide slab snow avalanches are dangerous and yet can be particularly difficult to predict. Both wet slab and glide slab avalanches are thought to depend upon free water moving through the snowpack but are driven by different processes. In Glacier National Park, Montana, both types of avalanches can occur in the same year and affect the Going-to-the-Sun Road (GTSR). Both wet slab and glide slab avalanches along the GTSR from 2003-2010 are investigated. Meteorological data from two high-elevation weather stations and one SNOTEL site are used in conjunction with an avalanche database and snowpit profiles. These data were used to characterize years when only glide slab avalanches occurred and those years when both glide slab and wet slab avalanches occurred. Results of 168 glide slab and 57 wet slab avalanches along the GTSR suggest both types of avalanche occurrence depend on sustained warming periods with intense solar radiation (or rain on snow) to produce free water in the snowpack. Differences in temperature and net radiation metrics between wet slab and glide slab avalanches emerge as one moves from one day to seven days prior to avalanche occurrence. On average, a more rapid warming precedes wet slab avalanche occurrence. Glide slab and wet slab avalanches require a similar amount of net radiation. Wet slab avalanches do not occur every year, while glide slab avalanches occur annually. These results aim to enhance understanding of the required meteorological conditions for wet slab and glide slab avalanches and aid in improved wet snow avalanche forecasting.

  13. Global Adjoint Tomography - Hotspots and Slabs

    Science.gov (United States)

    Ruan, Y.; Lei, W.; Lefebvre, M. P.; Modrak, R. T.; Smith, J. A.; Orsvuran, R.; Bozdag, E.; Tromp, J.

    2017-12-01

    Plumes rise from the deep mantle due to thermal or/and chemical buoyancy, forming hotspots at the surface, and oceanic plates subduct underneath continents, piling up at discontinuities or sinking down to the core-mantle boundary. Despite these basic convection mechanisms, many questions remain about the origin of mantle plumes, slab subduction, their interaction with mantle convection, and their relationship with the large low shear velocity provinces (LLSVPs) at the base of the mantle. Plume and slab morphology at depth provide further insight into these questions but imaging them in the mid and lower mantle is known to be very challenging due to a lack of data coverage and resolvability limits of conventional body-wave traveltime tomography. The deployment of regional dense arrays (e.g., USArray) and development of full waveform inversion techniques provide opportunities to resolve finer 3D details of mantle plumes and slabs. Harnessing the power of supercomputer ''Titan'' at Oak Ridge National Laboratory, we employed a spectral-element method to accurately simulate seismograms in complex 3D Earth models and an adjoint method to obtain model updates. Bozdag et al. (2016) iteratively determined a transversely isotropic earth model (GLAD_M15) using 253 events. To achieve higher resolution and better coverage in the deep mantle, we expanded our database to 1,040 events; a 1/3 of them are deep earthquakes (>500 km). We reinverted source parameters using model GLAD_M15, recalculated synthetic seismograms, selected time windows that show good agreement between data and the synthetics, and made measurements within these windows. From the measurements, we further assess the overall quality of each event and station and exclude bad measurements using very conservative criteria. Thus far, we assimilated more than 10 million windows in three period bands from 17-250 s. As the model improves, we correct the centroid time and scalar moment of each event using its mean

  14. Improved Casting Furnace Conceptual Design

    Energy Technology Data Exchange (ETDEWEB)

    Fielding, Randall Sidney [Idaho National Lab. (INL), Idaho Falls, ID (United States); Tolman, David Donald [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-02-01

    In an attempt to ensure more consistent casting results and remove some schedule variance associated with casting, an improved casting furnace concept has been developed. The improved furnace uses the existing arc melter hardware and glovebox utilities. The furnace concept was designed around physical and operational requirements such as; a charge sized of less than 30 grams, high heating rates and minimal additional footprint. The conceptual model is shown in the report as well as a summary of how the requirements were met.

  15. Steel Casting Requirements for Ordnance.

    Science.gov (United States)

    Steel , *Castings, *Nondestructive testing , * Charpy impact tests , Tensile properties, Loads(Forces), Toughness, Hardness, Etching, Heat treatment, Microstructure, Shells(Structural forms), Economic analysis

  16. Possible deviations from Griffith’s criterion in shallow slabs, and consequences on slab avalanche release

    Directory of Open Access Journals (Sweden)

    F. Louchet

    2002-01-01

    Full Text Available Possible reasons for deviations from Griffith’s criterion in slab avalanche triggerings are examined. In the case of a major basal crack, we show (i that the usual form of Griffith’s criterion is valid if elastic energy is stored in a shallow and hard slab only, and (ii that rapid healing of broken ice bonds may lead to shear toughnesses larger than expected from tensile toughness experiments. In the case of avalanches resulting from failure of multi-cracked weak layers, where a simple Griffith’s criterion cannot be applied, frequency/size plots obtained from discrete elements and cellular automata simulations are shown to obey scale invariant power law distributions. These findings are confirmed by both frequency/acoustic emission duration and frequency/size plots obtained from field data, suggesting that avalanche triggerings may be described using the formalism of critical phenomena.

  17. LASERS: A cryogenic slab CO laser

    Science.gov (United States)

    Ionin, Andrei A.; Kozlov, A. Yu; Seleznev, L. V.; Sinitsyn, D. V.

    2009-03-01

    A compact capacitive transverse RF-discharge-pumped slab CO laser with cryogenically cooled electrodes, which operates both in the cw and repetitively pulsed regimes, is fabricated. The laser operation is studied in the free running multifrequency regime at the vibrational - rotational transitions of the fundamental (V + 1 → V) vibrational bands of the CO molecule in the spectral region from 5.1 to 5.4 μm. Optimal operation conditions (gas mixture composition and pressure, RF pump parameters) are determined. It is shown that only gas mixtures with a high content of oxygen (up to 20% with respect to the concentration of CO molecules) can be used as an active medium of this laser. It is demonstrated that repetitively pulsed pumping is more efficient compared to cw pumping. In this case, quasi-cw lasing regime can be obtained. The maximum average output power of ~12 W was obtained for this laser operating on fundamental bands and its efficiency achieved ~14 %. The frequency-selective operation regime of the slab RF-discharge-pumped CO laser was realised at ~ 100 laser lines in the spectral region from 5.0 to 6.5 μm with the average output power of up to several tens of milliwatts in each line. Lasing at the transitions of the first vibrational overtone (V + 2 → V) of the CO molecule is obtained in the spectral region from 2.5 to 3.9 μm. The average output power of the overtone laser achieved 0.3 W. All the results were obtained without the forced gas mixture exchange in the discharge chamber. Under fixed experimental conditions, repetitively pulsed lasing (with fluctuations of the output characteristics no more than ±10 %) was stable for more than an hour.

  18. Controlling coverage of solution cast materials with unfavourable surface interactions

    KAUST Repository

    Burlakov, V. M.

    2014-03-03

    Creating uniform coatings of a solution-cast material is of central importance to a broad range of applications. Here, a robust and generic theoretical framework for calculating surface coverage by a solid film of material de-wetting a substrate is presented. Using experimental data from semiconductor thin films as an example, we calculate surface coverage for a wide range of annealing temperatures and film thicknesses. The model generally predicts that for each value of the annealing temperature there is a range of film thicknesses leading to poor surface coverage. The model accurately reproduces solution-cast thin film coverage for organometal halide perovskites, key modern photovoltaic materials, and identifies processing windows for both high and low levels of surface coverage. © 2014 AIP Publishing LLC.

  19. Colour Metallography of Cast Iron - White Cast Iron (Ⅱ

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2011-11-01

    Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron. Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron, uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditional materials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour

  20. Impact Resistance Behaviour of Banana Fiber Reinforced Slabs

    Science.gov (United States)

    Che Muda, Zakaria; Syamsir, Agusril; Nasharuddin Mustapha, Kamal; Rifdy Samsudin, Muhamad; Thiruchelvam, Sivadass; Usman, Fathoni; Beddu, Salmia; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Birima, Ahmed H.; Zaroog, O. S.

    2016-03-01

    This paper investigate the performance of banana fibre reinforced slabs 300mm × 300mm size with varied thickness subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.25 kg drop at 1 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance against the BF contents and slab thickness. A linear relationship has been established between first and ultimate crack resistance against BF contents and slab thickness by the experiment. The linear relationship has also been established between the service (first) crack and ultimate crack resistance against the BF contents for a constant spacing for various banana fibre reinforced slab thickness. The increment in BF content has more effect on the first crack resistance than the ultimate crack resistance. The linear relationship has also been established between the service (first) crack and ultimate crack resistance against the various slab thickness. Overall 1.5% BF content with slab thickness of 40 mm exhibit better first and ultimate crack resistance up to 16 times and up to 17 times respectively against control slab (without BF)

  1. Education and Caste in India

    Science.gov (United States)

    Chauhan, Chandra Pal Singh

    2008-01-01

    This paper analyses the policy of reservation for lower castes in India. This policy is similar to that of affirmative action in the United States. The paper provides a brief overview of the caste system and discusses the types of groups that are eligible for reservation, based on data from government reports. The stance of this paper is that…

  2. Cost Analysis of Precast and Cast-in-Place Concrete Construction for Selected Public Buildings in Ghana

    Directory of Open Access Journals (Sweden)

    Richard Oduro Asamoah

    2016-01-01

    Full Text Available The construction industry in Ghana is becoming efficient in the area of cost and achieving advance technologies. The effective management of cost enables clients, developers, and facilitators to achieve value for money. Concrete is a major component in every construction project. The use of precast concrete technology has been embraced by the construction industry in Ghana. This study seeks to analyze cost estimating of the structural frame (column and slab by considering cast-in-place and precast concrete slabs and columns, respectively. Relative importance and Kendall’s concordance agreement were used to determine the rankings and agreement of advantages of using precast concrete. The study established that precast concrete slabs were on average 23.22% cheaper than the cast-in-place concrete elements and precast columns were averagely 21.4% less than cast-in-place concrete columns. The study established that professionals prefer the use of precast concrete products because of the life cycle cost.

  3. The Effect of Temperature on the Result of Complex Modification of IN-713C Superalloy Castings

    Directory of Open Access Journals (Sweden)

    Binczyk F.

    2015-12-01

    Full Text Available The paper presents the results of research on the determination of the effect of pouring temperature on the macrostructure of the castings subjected to complex (surface and volume modification and double filtration. Tested castings were made of post-production scrap (gating system parts of IN-713C superalloy. Tests included the evaluation of the number of grains per 1 mm2, mean grain surface area, shape factor and tensile strength. Casting temperature below 1470 °C positively influenced the modification effect. The grains were finer and the mechanical properties increased, especially for castings with thicker walls. On the other hand, manufacture of thin walled castings of high quality require pouring temperature above 1480 °C.

  4. Colour Metallography of Cast Iron

    Directory of Open Access Journals (Sweden)

    Zhou Jiyang

    2009-05-01

    Full Text Available Cast iron, as a traditional metal material, has advantages of low total cost, good castability and machinability, good wear resistance and low notch sensitivity, and is still facing tough challenge in quality, property and variety of types etc. Experts and engineers studying and producing iron castings all around world extremely concern this serious challenge. Over more than 30 years, a great of research work has been carried out on how to further improve its property, expand its application and combine cast iron technology with some hi-techs (for example, computer technology. Nevertheless, cast iron is a multi-element and multi-phase alloy and has complex and variety of structures and still has great development potential in structure and property. For further studying and developing cast iron, theoretical research work is important promise, and the study on solidification process and control mechanism of graphite morphology is fundamental for improving property of cast iron and developing new type of cast iron.Metallography of cast iron normally includes two sections: liquid phase transformation and solid phase transformation. The book, Colour Metallography of Cast Iron , uses colour metallography technique to study solidification structures of cast irons: graphite, carbides, austenite and eutectics; and focuses on solidification processes. With progress of modern solidification theory, the control of material solidification process becomes important measure for improving traditionalmaterials and developing new materials. Solidification structure not only influences mechanical and physical properties of cast iron, but also affects its internal quality. The book uses a large amount of colour photos to describe the formation of solidification structures and their relations. Crystallization phenomena, which cannot be displayed with traditional metallography, are presented and more phase transformation information is obtained from these colour

  5. Broadband high reflectivity in subwavelength-grating slab waveguides.

    Science.gov (United States)

    Tian, Hao; Cui, Xuan; Du, Yan; Tan, Peng; Shi, Guang; Zhou, Zhongxiang

    2015-10-19

    We computationally study a subwavelength dielectric grating structure, show that slab waveguide modes can be used to obtain broadband high reflectivity, and analyze how slab waveguide modes influence reflection. A structure showing interference between Fabry-Perot modes, slab waveguide modes, and waveguide array modes is designed with ultra-broadband high reflectivity. Owing to the coupling of guided modes, the region with reflectivity R > 0.99 has an ultra-high bandwidth (Δf / ̅f > 30%). The incident-angle region with R > 0.99 extends over a range greater than 40°. Moreover, an asymmetric waveguide structure with a semiconductor substrate is studied.

  6. Interaction of an ion bunch with a plasma slab

    Energy Technology Data Exchange (ETDEWEB)

    Krasovitskiy, V. B., E-mail: krasovit@mail.ru [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Turikov, V. A. [Peoples’ Friendship University of Russia (Russian Federation)

    2016-11-15

    Charge neutralization of a short ion bunch passing through a plasma slab is studied by means of numerical simulation. It is shown that a fraction of plasma electrons are trapped by the bunch under the action of the collective charge separation field. The accelerated electrons generated in this process excite beam−plasma instability, thereby violating the trapping conditions. The process of electron trapping is also strongly affected by the high-frequency electric field caused by plasma oscillations at the slab boundaries. It is examined how the degree of charge neutralization depends on the parameters of the bunch and plasma slab.

  7. Rayleigh-Taylor instability in accelerated elastic-solid slabs

    Science.gov (United States)

    Piriz, S. A.; Piriz, A. R.; Tahir, N. A.

    2017-12-01

    We develop the linear theory for the asymptotic growth of the incompressible Rayleigh-Taylor instability of an accelerated solid slab of density ρ2, shear modulus G , and thickness h , placed over a semi-infinite ideal fluid of density ρ110.1007/s000330050121] to arbitrary values of AT and unveil the singular feature of an instability threshold below which the slab is stable for any perturbation wavelength. As a consequence, an accelerated elastic-solid slab is stable if ρ2g h /G ≤2 (1 -AT) /AT .

  8. Defect detection in slab surface: a novel dual Charge-coupled Device imaging-based fuzzy connectedness strategy.

    Science.gov (United States)

    Zhao, Liming; Ouyang, Qi; Chen, Dengfu; Udupa, Jayaram K; Wang, Huiqian; Zeng, Yuebin

    2014-11-01

    To provide an accurate surface defects inspection system and make the automation of robust image segmentation method a reality in routine production line, a general approach is presented for continuous casting slab (CC-slab) surface defects extraction and delineation. The applicability of the system is not tied to CC-slab exclusively. We combined the line array CCD (Charge-coupled Device) traditional scanning imaging (LS-imaging) and area array CCD laser three-dimensional (3D) scanning imaging (AL-imaging) strategies in designing the system. Its aim is to suppress the respective imaging system's limitations. In the system, the images acquired from the two CCD sensors are carefully aligned in space and in time by maximum mutual information-based full-fledged registration schema. Subsequently, the image information is fused from these two subsystems such as the unbroken 2D information in LS-imaging and 3D depressed information in AL-imaging. Finally, on the basis of the established dual scanning imaging system the region of interest (ROI) localization by seed specification was designed, and the delineation for ROI by iterative relative fuzzy connectedness (IRFC) algorithm was utilized to get a precise inspection result. Our method takes into account the complementary advantages in the two common machine vision (MV) systems and it performs competitively with the state-of-the-art as seen from the comparison of experimental results. For the first time, a joint imaging scanning strategy is proposed for CC-slab surface defect inspection that allows a feasible way of powerful ROI delineation strategies to be applied to the MV inspection field. Multi-ROI delineation by using IRFC in this research field may further improve the results.

  9. Caste, social stigma and identity processes

    OpenAIRE

    Jaspal, Rusi

    2011-01-01

    Caste persists as an important socio-psychological phenomenon in many spheres of Indian social life and particularly within village contexts. It is argued that socio-psychological insights into caste identity and caste- based stigma may complement ongoing sociological and anthropological research into caste. Drawing upon identity process theory, this article explores the possible functions performed by caste-based stigma both for the higher caste groups (HCGs) and the ‘Scheduled Caste’ (SC) g...

  10. Ceramic tape casting: A review of current methods and trends with emphasis on rheological behaviour and flow analysis

    International Nuclear Information System (INIS)

    Jabbari, M.; Bulatova, R.; Tok, A.I.Y.; Bahl, C.R.H.; Mitsoulis, E.; Hattel, J.H.

    2016-01-01

    Highlights: • Brief review of the tape casting process for ceramics. • Role of fluid flow analysis in tape casting of ceramics. • Rheological classification of common fluids in tape casting. • Review of commonly used rheological behaviour for ceramics in tape casting. - Abstract: Tape casting has been used to produce thin layers of ceramics that can be used as single layers or can be stacked and laminated into multilayered structures. Today, tape casting is the basic fabrication process that provides multilayered capacitors and multilayered ceramic packages. In tape casting the rheological behaviour of the slurry as well as the material flow during casting are of utmost importance since these phenomena to a large extent determine the final properties and hence the quality of the cast product. During the last decades this has led to an increasing number of works in literature within fluid flow analysis of tape casting. In the present paper a review of the development of the tape casting process with particular focus on the rheological classifications as well as modelling the material flow is hence presented and in this context the current status is examined and future potential discussed.

  11. May eclogite dehydration cause slab fracturation ?

    Science.gov (United States)

    Loury, Chloé; Lanari, Pierre; Rolland, Yann; Guillot, Stéphane; Ganino, Clément

    2015-04-01

    Petrological and geophysical evidences strongly indicate that fluids releases play a fundamental role in subduction zones as in subduction-related seismicity and arc magmatism. It is thus important to assess quantitatively their origin and to try to quantify the amount of such fluids. In HP metamorphism, it is well known that pressure-dependent dehydration reactions occur during the prograde path. Many geophysical models show that the variations in slab physical properties along depth could be linked to these fluid occurrences. However it remains tricky to test such models on natural sample, as it is difficult to assess or model the water content evolution in HP metamorphic rocks. This difficulty is bound to the fact that these rocks are generally heterogeneous, with zoned minerals and preservation of different paragenesis reflecting changing P-T conditions. To decipher the P-T-X(H2O) path of such heterogeneous rocks the concept of local effective bulk (LEB) composition is essential. Here we show how standardized X-ray maps can be used to constrain the scale of the equilibration volume of a garnet porphyroblast and to measure its composition. The composition of this equilibrium volume may be seen as the proportion of the rock likely to react at a given time to reach a thermodynamic equilibrium with the growing garnet. The studied sample is an eclogite coming from the carboniferous South-Tianshan suture (Central Asia) (Loury et al. in press). Compositional maps of a garnet and its surrounding matrix were obtained from standardized X-ray maps processed with the program XMapTools (Lanari et al, 2014). The initial equilibration volume was modeled using LEB compositions combined together with Gibbs free energy minimization. P-T sections were calculated for the next stages of garnet growth taking into account the fractionation of the composition at each stage of garnet growth. The modeled P-T-X(H2O) path indicates that the rock progressively dehydrates during the

  12. Functionally Graded Ceramics Fabricated with Side-by-Side Tape Casting for Use in Magnetic Refrigeration

    DEFF Research Database (Denmark)

    Bulatova, Regina; Bahl, Christian; Andersen, Kjeld Bøhm

    2015-01-01

    Functionally graded ceramic tapes have been fabricated by a side-by-side tape casting technique. This study shows the possibility and describes the main principles of adjacent coflow of slurries resulting in formation of thin plates of graded ceramic material. Results showed that the small...... variations of solvent and binder system concentrations have a substantial effect on slurry viscosity. Varying these parameters showed that side-by-side tape casting with a well-defined interface area is possible for slurries with viscosities above 3500 mPa s at a casting shear rate of 3.3 s -1...

  13. Magmatic and Seismic Evidence for the Neogene Evolution of the Subducting Slab and Crustal and Mantle Lithosphere under the Central Andes

    Science.gov (United States)

    Kay, S. M.; Sandvol, E. A.

    2017-12-01

    Geophysical models coupled with the distribution, chemistry and age of magmatic rocks provide powerful tools for reconstructing the thermal and material balance and deformational history of the Central Andean crust and lithosphere in time and space. Two examples are given. In the first, a model for changing slab geometry, delamination (foundering) of the crust and mantle and forearc subduction erosion beneath the southern Puna plateau comes from studies of Miocene to Recent magmatic rocks linked with seismic studies. The distribution and chemistry (e.g., Sm/Yb, La/Ta, Ba/La, isotopes) of the volcanic rocks support an 18-7 Ma period of slab shallowing, followed by slab steepening and forearc subduction erosion linked with backarc crustal and lithospheric delamination and eruption of large ignimbrites. Support for delamination comes from seismic attenuation and Vs tomographic images that reveal an 100 km wide high velocity anomaly associated with an irregular shear wave splitting pattern, which is interpreted as a delaminated block above a nearly aseismic segment of the subducting slab at a depth of 150-200 km (Calixto et al., 2013, 2014; Liang et al. 2014). This block underlies the 1350°C at 2 Gpa followed by fractionation and mixing with melts of garnet-pyroxene-amphibole bearing crust (Risse et al., 2013). In accord, the lavas are over a region where receiver functions indicate a lithosphere-asthenosphere boundary at 60-80 km and a regionally thin 45-55 km thick crust with a low Vp/Vs (< 1.70) ratio (Heit et al., 2014). Calculations of crustal loss and gain allow up to 10% of the southern Puna lower crust to have been lost in the last 10 Ma. A second region where the characteristics of the magmatic rocks provide clues to the timing of slab shallowing and proposed slab tears (e.g., Lynner et al, 2017) is over and on the margins of the Chilean flat-slab). In this case, shallowing of the slab as the trench normal portion of the Juan Fernandez Ridge began to subduct

  14. Method of producing thin cellulose nitrate film

    International Nuclear Information System (INIS)

    Lupica, S.B.

    1975-01-01

    An improved method for forming a thin nitrocellulose film of reproducible thickness is described. The film is a cellulose nitrate film, 10 to 20 microns in thickness, cast from a solution of cellulose nitrate in tetrahydrofuran, said solution containing from 7 to 15 percent, by weight, of dioctyl phthalate, said cellulose nitrate having a nitrogen content of from 10 to 13 percent

  15. Inoculated Slightly Hypereutectic Gray Cast Irons

    Science.gov (United States)

    Chisamera, Mihai; Riposan, Iulian; Stan, Stelian; Militaru, Cristina; Anton, Irina; Barstow, Michael

    2012-03-01

    The current experimental investigation in this article was designed to characterize the structure of mold (M) and ladle (L) inoculated, low-S (0.025 wt.% S), low-Al (0.003 wt.% Al), slightly hypereutectic (CE = 4.4-4.5 wt.%) electric melted gray irons, typical for high performance thin-wall castings. It describes the effect of a Ca, Al, Zr-FeSi inoculant addition of 0-0.25 wt.% on structure characteristics, and compares to similar treatments with hypoeutectic irons (3.5-3.6 wt.% CE, 0.025 wt.% S, and 0.003 wt.% Al). A complex structure including primary graphite, austenite dendrites, and eutectic cells is obtained in hypereutectic irons, as the result of nonequilibrium solidification following the concept of a coexisting region. Dendrites appear to be distributed between eutectic cells at higher eutectic undercooling, while in inoculated irons and for lower undercooling, the eutectic cells are "reinforced" by eutectic austenite dendrites. A Zr, Ca, Al-FeSi alloy appears to be an effective inoculant in low S, low Al, gray cast irons, especially for a late inoculation technique, with beneficial effects on both graphite and austenite phases. First, inoculation influenced the nucleation of graphite/eutectic cell, and then their characteristics. A further role of these active elements directly contributed to form nucleation sites for austenite, as complex (Mn,X)S particles.

  16. Optimising the Slab Yard Planning and Crane Scheduling Problem using a two-stage heuristic

    DEFF Research Database (Denmark)

    Hansen, Anders Dohn; Clausen, Jens

    2010-01-01

    In this paper, we present the Slab Yard Planning and Crane Scheduling Problem. The problem has its origin in steel production facilities with a large throughput. A slab yard is used as a buffer for slabs that are needed in the upcoming production. Slabs are transported by cranes and the problem...

  17. 29 CFR 1926.705 - Requirements for lift-slab construction operations.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Requirements for lift-slab construction operations. 1926... Masonry Construction § 1926.705 Requirements for lift-slab construction operations. (a) Lift-slab...-slab construction. Such plans and designs shall be implemented by the employer and shall include...

  18. Calculation of shear strength of prestressed hollow core slabs by use of plastic theory

    DEFF Research Database (Denmark)

    Hoang, Linh Cao; Jørgensen, H.G.; Nielsen, Mogens Peter

    2014-01-01

    Th is paper deals with calculations of the shear capacity of precast, prestressed hollow core slabs. Such slabs are often used as floor systems in building structures. A common way to produce hollow core slabs is to use the extrusion technique where long strips of slabs are extruded and thereafter...

  19. Global methods for reinforced concrete slabs

    International Nuclear Information System (INIS)

    Hoffmann, A.; Lepareux, M.; Combescure, A.

    1985-08-01

    This paper develops the global method strategy to compute elastoplastic thin shells or beams. It is shown how this methodology can be applied to the case of reinforced concrete structures. Two cases of applications are presented: one static, the other dynamic. The numerical results are compared to experimental data

  20. Integral bridge abutment-to-approach slab connection.

    Science.gov (United States)

    2008-06-01

    The Iowa Department of Transportation has long recognized that approach slab pavements of integral abutment bridges are prone to settlement and cracking, which manifests as the "bump at the end of the bridge". A commonly recommended solution is to in...

  1. The rideability of a deflected bridge approach slab.

    Science.gov (United States)

    2009-11-01

    This report presents the findings associated with the development of a new pavement roughness index called the Posted Speed Localized Roughness Index (LRIPS) that can be used to rate the ride quality on bridge approach slabs. Currently established pa...

  2. Field demonstration of new bridge approach slab designs and performance.

    Science.gov (United States)

    2014-06-01

    The Louisiana Department of Transportation and Development (DOTD) has initiated a major effort to minimize the bridge end bump problem associated : with differential settlement. As a result, a new design for the approach slab was proposed, which requ...

  3. Evaluation of precast concrete slabs using a heavy vehicle simulator

    CSIR Research Space (South Africa)

    Kohler, E

    2008-10-01

    Full Text Available -controlled conditions and that fully cured precast slabs can potentially be open to traffic almost immediately upon installation, making them attractive for use on heavily travelled highways. This paper describes an accelerated pavement testing experiment conducted...

  4. Effects of Posttensioning Slippage on 2-Way Spanning Concrete Slabs

    Directory of Open Access Journals (Sweden)

    Niall Holmes

    2015-01-01

    Full Text Available This paper investigates the effect of improper posttensioning of a 2-way spanning concrete slab subject to a central point load. Due to plate slippage alone, the support conditions only offered a 1-way spanning action which could have led to premature failure with dangerous consequences. Posttensioning can strengthen a flat slab against punching shear by controlling deflections and cracking under service loads compared with traditional punching shear reinforcing methods leading to more slender structures and economic solutions for longer spans. However, if the method is not properly applied, these thinner floor plates can fail in a brittle and sudden manner by punching at ultimate limit state and excessive deflection in serviceability. Concrete slabs containing traditional shear reinforcement performed adequately and demonstrated that the critical punching shear perimeter, defined as twice the depth of the slab, was confirmed from measured deflections and crack pattern analysis.

  5. Diffusion of radon through cracks in a concrete slab.

    Science.gov (United States)

    Landman, K A

    1982-07-01

    A mathematical model is developed to describe diffusion of radon through cracks or gaps in concrete slabs which are used in building foundations. As radon approaches the soil surface from underlying soil, it encounters a concrete slab. The radon will diffuse toward any air-filled cracks. The rate of exhalation through a portion of a cracked slab is determined and compared to the rate of exhalation from the same surface area of bare soil. In a typical case, this ratio is approx. 0.25. This is about a 20-fold increase to the ratio found when the concrete slab has no cracks. Therefore crack pathways are potentially a major source of indoor radon.

  6. The heterogeneous response method in slab geometry

    International Nuclear Information System (INIS)

    Villarino, E.A.; Stamm'ler, R.J.J.

    1984-01-01

    The heterogeneous response method (HRM) has been developed to calculate the multigroup flux in a heterogeneous system, e.g. a fuel assembly, without having to resort to dubious homogenization recipes. Here, the method is described in slab geometry in a manner that facilitates its computerization. By dividing the system into subsystems or nodes, say pin cells, two levels of calculation are created, which define a set of local problems and a global problem, respectively. In the local problem, collision probabilities are used to obtain for a node in vacuum, its response fluxes caused by sources and in-currents. They preserve the heterogeneous character of the node. In the global problem, the nodes are coupled by cosine currents. A suitable transformation reduces the number of two unknown currents per interface to one unknown per node, its total transmitted in-current. The global equation system thus becomes a set of three-point relations, which can be solved efficiently. In cases typical of fuel-assembly situations, the HRM produces fluxes that compare very well with the direct solution of the entire system by collision probabilities, though at a fraction of the computer cost. Extension of the method to 2- and 3-D systems is discussed. (author)

  7. Magnetoelectric sensor excitations in hexaferrite slabs

    Science.gov (United States)

    Zare, Saba; Izadkhah, Hessam; Somu, Sivasubramanian; Vittoria, Carmine

    2015-06-01

    We developed techniques for H- and E-field sensors utilizing single phase magnetoelectric (ME) hexaferrite slabs in the frequency range of 100 Hz to 10 MHz. Novel circuit designs incorporating both spiral and solenoid coils and single and multi-capacitor banks were developed to probe the physics and properties of ME hexaferrites and explore ME effects for sensor detections. Fundamental measurements of the anisotropic tensor elements of the magneto-electric coupling parameter were performed using these novel techniques. In addition, for H-field sensing experiments we measured sensitivity of about 3000 Vm-1/G using solenoid coils and 8000 Vm-1/G using spiral coils. For E-field, sensing the sensitivity was 10-4 G/Vm-1 and using single capacitor detector. Sensitivity for multi-capacitor detectors was measured to be in the order of 10-3 G/Vm-1 and frequency dependent exhibiting a maximum value at ˜1 MHz. Tunability of 0.1%-90% was achieved for tunable inductor applications using both single and multi-capacitors excitation. We believe that significant (˜106) improvements in sensitivity and tunability are feasible with simple modifications of the fabrication process.

  8. Calculation of shear strength of prestressed hollow core slabs by use of plastic theory

    DEFF Research Database (Denmark)

    Hoang, Linh Cao; Jørgensen, Henrik Brøner; Nielsen, Mogens Peter

    2014-01-01

    This paper deals with calculations of the shear capacity of precast, prestressed hollow core slabs. Such slabs are often used as floor systems in Building structures. A common way to produce hollow core slabs is to use the extrusion technique where long strips of slabs are extruded and thereafter...... saw-cut into units with the desirable length. For this reason, hollow core slabs are usually not shear reinforced and anchorage of the prestressing strands has to be established by bond. Hollow core slabs may therefore be more critical to shear and Anchorage failure than ordinary two-way spanning...... reinforced concrete slabs....

  9. Calculation of shear strength of prestressed hollow core slabs by use of plastic theory

    DEFF Research Database (Denmark)

    Hoang, Linh Cao; Jørgensen, H.G.; Nielsen, Mogens Peter

    2014-01-01

    Th is paper deals with calculations of the shear capacity of precast, prestressed hollow core slabs. Such slabs are often used as floor systems in building structures. A common way to produce hollow core slabs is to use the extrusion technique where long strips of slabs are extruded and thereafter...... saw-cut into units with the desirable length. For this reason, hollow core slabs are usually not shear reinforced and anchorage of the prestressing strands has to be established by bond. Hollow core slabs may therefore be more critical to shear and anchorage failure than ordinary two-way spanning...... reinforced concrete slabs....

  10. Radon exhalation study from cement, cement slabs and concrete slabs with variation in fly ash

    International Nuclear Information System (INIS)

    Sharma, Nisha; Singh, Jaspal

    2012-01-01

    Fly ash is a waste product from coal-fired power plants. Fly ash has become a subject of world-wide interest in recent years because of its diverse uses, e.g. in the manufacture of concrete for building purposes, for the filling of underground cavities, or as a component of building material. The fly ash may contain enhanced levels of the natural radionuclides in the uranium and thorium series and by using the fly ash in building materials, the radiation levels in houses may thus be technologically enhanced. Because of its relatively high radionuclide contents (including 226 Ra), fly ash may, however, present a potential hazard to the population through its radon emanation, which would be highly undesirable. Since fly ash is frequently used as a building material, the idea of the experiment was to mix fly ash in different proportions in the cement in the powder form, cemented slabs and concrete slabs to study the combined behaviors. Alpha sensitive LR-115 type II plastic track detector, commonly known as Solid State Nuclear Track Detectors (SSNTDs), were used to measure the radon concentration. The alpha particles emitted from the radon causes the radiation damaged tracks. The chemical etching in NaOH at 60°C for about 90 minutes was done to reveal these latent tracks, which were then scanned and counted by an optical microscope of suitable magnification. By calculating the track density of registered tracks, the radon concentrations were determined. In case of cement in the powder form and in cemented slab, starting from the pure cement, fly ash was added up to 70% by weight. In this case the radon exhalation rate has increased by addition of fly ash in the cement and in case of concrete slabs by the addition of fly ash in the cement the radon exhalation increases up to 60% and then decreases. Therefore, on the basis of our investigations we concluded that in general radon exhalation rate increases with the addition of fly ash. (author)

  11. Punching of flat slabs supported on rectangular columns

    OpenAIRE

    Sagaseta, Juan; Tassinari, Luca; Fernández Ruiz, Miguel; Muttoni, Aurelio

    2014-01-01

    This paper investigates the structural behaviour of RC flat slabs supported on rectangular interior columns and the influence of the loading conditions (one or two-way bending) on their punching shear strength. The punching shear strength of slabs at rectangular columns can be lower than at equivalent square col- umns with a similar length of the control perimeter. This is due to a potential concentration of shear forces alongthecontrol perimeter. Some, but notall designformulas for punchingd...

  12. Slab2 - Updated Subduction Zone Geometries and Modeling Tools

    Science.gov (United States)

    Moore, G.; Hayes, G. P.; Portner, D. E.; Furtney, M.; Flamme, H. E.; Hearne, M. G.

    2017-12-01

    The U.S. Geological Survey database of global subduction zone geometries (Slab1.0), is a highly utilized dataset that has been applied to a wide range of geophysical problems. In 2017, these models have been improved and expanded upon as part of the Slab2 modeling effort. With a new data driven approach that can be applied to a broader range of tectonic settings and geophysical data sets, we have generated a model set that will serve as a more comprehensive, reliable, and reproducible resource for three-dimensional slab geometries at all of the world's convergent margins. The newly developed framework of Slab2 is guided by: (1) a large integrated dataset, consisting of a variety of geophysical sources (e.g., earthquake hypocenters, moment tensors, active-source seismic survey images of the shallow slab, tomography models, receiver functions, bathymetry, trench ages, and sediment thickness information); (2) a dynamic filtering scheme aimed at constraining incorporated seismicity to only slab related events; (3) a 3-D data interpolation approach which captures both high resolution shallow geometries and instances of slab rollback and overlap at depth; and (4) an algorithm which incorporates uncertainties of contributing datasets to identify the most probable surface depth over the extent of each subduction zone. Further layers will also be added to the base geometry dataset, such as historic moment release, earthquake tectonic providence, and interface coupling. Along with access to several queryable data formats, all components have been wrapped into an open source library in Python, such that suites of updated models can be released as further data becomes available. This presentation will discuss the extent of Slab2 development, as well as the current availability of the model and modeling tools.

  13. Shear and anchorage behaviour of fire exposed hollow core slabs

    OpenAIRE

    Fellinger, J.H.H.; Stark, J.; Walraven, J.C.

    2005-01-01

    The fire resistance of hollow core slabs is currently assessed considering flexural failure only. However, fire tests showed that shear or anchorage failure can also govern the load bearing behaviour. As the shear and anchorage capacity of these slabs rely on the tensile strength of the concrete, the load bearing capacity with respect to these failure modes decreases dramatically during fire due to the impact of thermal stresses. This paper presents a FE model for the shear and anchorage beha...

  14. Macrosegregation in horizontal direct chill casting of ternary Al alloys: Investigation of solid motion

    International Nuclear Information System (INIS)

    Vušanović, I; Krane, M J M

    2012-01-01

    Macrosegregation in direct chill casting processes is controlled by fluid flow due to the thermosolutal natural and forced convection, shrinkage, and transport of unattached solid grains. Because grain refinement is usually used in aluminum direct chill casting, some effort must be made to model free-floating solid grains, and their attachment to a rigid mushy zone. Criteria for attachment vary, but many are based on using a critical solid packing fraction, which is treated as uniform and constant throughout the domain. In the case of horizontal casting (HDC), gravity acts perpendicularly to the casting direction, and the assumption of a uniform packing fraction cannot be applied because the solid particles attach to some surfaces by settling and others by being swept into the rigid solid from below. In this simulation of HDC casting of an Al-Cu-Mg alloy, the rigid and unattached solid is tracked separately, and a rule set is developed to determine the attachment of free-floating solid. Comparison between cases with and without unattached solid movement shows qualitatively different results, particularly in bottom part of slab. Non-uniform packing fractions cause very different segregation patterns in the lower half of the ingot compared to the cases with no solid movement, less segregation near centerline compared to uniform packing fraction cases, and positive segregation near the place where inlet jet impinges on the mushy zone.

  15. Quantitative NDT structuroscopy of cast iron castings for vehicles

    Czech Academy of Sciences Publication Activity Database

    Skrbek, B.; Tomáš, Ivan

    2011-01-01

    Roč. 6, 3-4 (2011), s. 293-305 ISSN 1741-8410 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic method * structuroscopy * cast iron * clutch disks Subject RIV: BM - Solid Matter Physics ; Magnetism

  16. Recent progress in high-power slab lasers in Japan

    International Nuclear Information System (INIS)

    Fujii, Y.

    1988-01-01

    Recently, many solid-state lasers have been widely employed in Japanese industries, especially in the electronics industries for precise and reliable processing. To expand the use of solid-state lasers and to achieve higher processing speed, the authors are developing slab lasers of high power, high repetition rate, and high beam quality. Metal processing systems with optical fibers for large and complex 3-D work, multiwork station systems linked to only one laser with optical fibers, and compact x-ray sources for lithography are promising areas for such lasers. Surnitomo Metal Mining is growing Nd:GGG and Nd:YAG crystals 60 mm in diameter and 200 mm long. From 2 at.% Nd-doped GGG crystals without central core regions. The authors obtained two slab materials with dimensions of 35 X 9 X 192 and 55 X 15 X 213 mm/sup 3/. By using the smaller slab, they constructed a slab laser and obtained 370-W laser output power at 24-kW lamp input power and 10-pps repetition rate. Now they are constructing a 1-kW slab laser using the other larger size slab

  17. Strengthening of RC bridge slabs using CFRP sheets

    Directory of Open Access Journals (Sweden)

    Fahmy A. Fathelbab

    2014-12-01

    Full Text Available Many old structures became structurally insufficient to carry the new loading conditions requirements. Moreover, they suffer from structural degradation, reinforcement steel bars corrosion, bad weather conditions…etc. Many official authorities in several countries had recognized many old bridges and buildings as structurally deficient by today’s standards. Due to these reasons, structural strengthening became an essential requirement and different strengthening techniques appeared in market. Fiber Reinforced Polymer (FRP strengthening techniques established a good position among all other techniques, giving excellent structural results, low time required and moderate cost compared with the other techniques. The main purpose of this research is to study analytically the strengthening of a reinforced concrete bridge slabs due to excessive loads, using externally bonded FRP sheets technique. A commercial finite element program ANSYS was used to perform a structural linear and non-linear analysis for strengthened slab models using several schemes of FRP sheets. A parametric study was performed to evaluate analytically the effect of changing both FRP stiffness and FRP schemes in strengthening RC slabs. Comparing the results with control slab (reinforced concrete slab without strengthening it is obvious that attaching FRP sheets to the RC slab increases its capacity and enhances the ductility/toughness.

  18. Seismic anisotropy and mantle flow below subducting slabs

    Science.gov (United States)

    Walpole, Jack; Wookey, James; Kendall, J.-Michael; Masters, T.-Guy

    2017-05-01

    Subduction is integral to mantle convection and plate tectonics, yet the role of the subslab mantle in this process is poorly understood. Some propose that decoupling from the slab permits widespread trench parallel flow in the subslab mantle, although the geodynamical feasibility of this has been questioned. Here, we use the source-side shear wave splitting technique to probe anisotropy beneath subducting slabs, enabling us to test petrofabric models and constrain the geometry of mantle fow. Our global dataset contains 6369 high quality measurements - spanning ∼ 40 , 000 km of subduction zone trenches - over the complete range of available source depths (4 to 687 km) - and a large range of angles in the slab reference frame. We find that anisotropy in the subslab mantle is well characterised by tilted transverse isotropy with a slow-symmetry-axis pointing normal to the plane of the slab. This appears incompatible with purely trench-parallel flow models. On the other hand it is compatible with the idea that the asthenosphere is tilted and entrained during subduction. Trench parallel measurements are most commonly associated with shallow events (source depth slab. This may correspond to the shape preferred orientation of cracks, fractures, and faults opened by slab bending. Meanwhile the deepest events probe the upper lower mantle where splitting is found to be consistent with deformed bridgmanite.

  19. Fan Fuel Casting Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Imhoff, Seth D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-28

    LANL was approached to provide material and design guidance for a fan-shaped fuel element. A total of at least three castings were planned. The first casting is a simple billet mold to be made from high carbon DU-10Mo charge material. The second and third castings are for optimization of the actual fuel plate mold. The experimental scope for optimization is only broad enough for a second iteration of the mold design. It is important to note that partway through FY17, this project was cancelled by the sponsor. This report is being written in order to capture the knowledge gained should this project resume at a later date.

  20. NUMERICAL MODELING OF HARDENING OF UNINTERRUPTEDLY-CASTED BRONZE CASTING

    Directory of Open Access Journals (Sweden)

    E. I. Marukovich

    2009-01-01

    Full Text Available The three-dimensional numerical model for calculation of thermal fields during solidification of continuously casted bronze casting is developed. Coefficients of heat transfer on borders of calculation areas on the basis of the solution of inverse heat transfer conduction problem are determined. The analysis of thermal fields, depending on loop variables of drawing and the sizes of not cooled zone of crystallizer is curried out.

  1. Energy Method Solution for the Vertical Deformation of Longitudinally Coupled Prefabricated Slab Track

    OpenAIRE

    Juanjuan Ren; Shijie Deng; Zhibin Jin; Junbin Yang; Xueyi Liu

    2017-01-01

    Upwarping on the longitudinally coupled prefabricated slab track system caused by the rising temperature is a common distress, which deteriorates the mechanical properties of the coupled slabs and the vertical stability of slabs. The objective of this paper is to quantify the upwarping deformation on the slab subjected to temperature force and to find out the influence of different factors on the upwarping phenomenon of the slabs. An analytical expression is deduced using energy method, and a...

  2. Porous Organic Cage Thin Films and Molecular-Sieving Membranes.

    Science.gov (United States)

    Song, Qilei; Jiang, Shan; Hasell, Tom; Liu, Ming; Sun, Shijing; Cheetham, Anthony K; Sivaniah, Easan; Cooper, Andrew I

    2016-04-06

    Porous organic cage molecules are fabricated into thin films and molecular-sieving membranes. Cage molecules are solution cast on various substrates to form amorphous thin films, with the structures tuned by tailoring the cage chemistry and processing conditions. For the first time, uniform and pinhole-free microporous cage thin films are formed and demonstrated as molecular-sieving membranes for selective gas separation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Modelling of flow phenomena during DC casting

    NARCIS (Netherlands)

    Zuidema, J.

    2005-01-01

    Modelling of Flow Phenomena during DC Casting Jan Zuidema The production of aluminium ingots, by semi-continuous casting, is a complex process. DC Casting stands for direct chill casting. During this process liquid aluminium transforms to solid aluminium while cooling down. This is not an

  4. Preventing cracks when casting steel slag ladles

    OpenAIRE

    Ivanov, M.; Shvetsov, V.

    2014-01-01

    The paper is dedicated to the improvement of large steel casting technology where slag ladle casting is taken as an example. The temperature measurement of the crystallization process of casting is held. The causes of the formation of cracks are reviewed. To prevent the formation of cracks the recommendations are developed to improve the casting technology.

  5. Reducing slab boundary artifacts in three‐dimensional multislab diffusion MRI using nonlinear inversion for slab profile encoding (NPEN)

    Science.gov (United States)

    Koopmans, Peter J.; Frost, Robert; Miller, Karla L.

    2015-01-01

    Purpose To propose a method to reduce the slab boundary artifacts in three‐dimensional multislab diffusion MRI. Methods Bloch simulation is used to investigate the effects of multiple factors on slab boundary artifacts, including characterization of residual errors on diffusion quantification. A nonlinear inversion method is proposed to simultaneously estimate the slab profile and the underlying (corrected) image. Results Correction results of numerical phantom and in vivo data demonstrate that the method can effectively remove slab boundary artifacts for diffusion data. Notably, the nonlinear inversion is also successful at short TR, a regimen where previously proposed methods (slab profile encoding and weighted average) retain residual artifacts in both diffusion‐weighted images and diffusion metrics (mean diffusion coefficient and fractional anisotropy). Conclusion The nonlinear inversion for removing slab boundary artifacts provides improvements over existing methods, particularly at the short TRs required to maximize SNR efficiency. Magn Reson Med 76:1183–1195, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:26510172

  6. Reducing slab boundary artifacts in three-dimensional multislab diffusion MRI using nonlinear inversion for slab profile encoding (NPEN).

    Science.gov (United States)

    Wu, Wenchuan; Koopmans, Peter J; Frost, Robert; Miller, Karla L

    2016-10-01

    To propose a method to reduce the slab boundary artifacts in three-dimensional multislab diffusion MRI. Bloch simulation is used to investigate the effects of multiple factors on slab boundary artifacts, including characterization of residual errors on diffusion quantification. A nonlinear inversion method is proposed to simultaneously estimate the slab profile and the underlying (corrected) image. Correction results of numerical phantom and in vivo data demonstrate that the method can effectively remove slab boundary artifacts for diffusion data. Notably, the nonlinear inversion is also successful at short TR, a regimen where previously proposed methods (slab profile encoding and weighted average) retain residual artifacts in both diffusion-weighted images and diffusion metrics (mean diffusion coefficient and fractional anisotropy). The nonlinear inversion for removing slab boundary artifacts provides improvements over existing methods, particularly at the short TRs required to maximize SNR efficiency. Magn Reson Med 76:1183-1195, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

  7. Silicon nanocrystal-based photonic crystal slabs with broadband and efficient directional light emission.

    Science.gov (United States)

    Ondič, L; Varga, M; Pelant, I; Valenta, J; Kromka, A; Elliman, R G

    2017-07-18

    Light extraction from a thin planar layer can be increased by introducing a two-dimensional periodic pattern on its surface. This structure, the so-called photonic crystal (PhC) slab, then not only enhances the extraction efficiency of light but can direct the extracted emission into desired angles. Careful design of the structures is important in order to have a spectral overlap of the emission with extraction (leaky) modes. We show that by fabricating PhC slabs with optimized dimensions from silicon nanocrystals (SiNCs) active layers, the extraction efficiency of vertical light emission from SiNCs at a particular wavelength can be enhanced ∼ 11 times compared to that of uncorrugated SiNCs-rich layer. More importantly, increased light emission can be obtained in a broad spectral range and, simultaneously, the extracted light can stay confined within relatively narrow angle around the normal to the sample plane. We demonstrate experimentally and theoretically that the physical origin of the enhancement is such that light originating from SiNCs first couples to leaky modes of the PhCs and is then efficiently extracted into the surrounding.

  8. Modeling radon entry into Florida slab-on-grade houses.

    Science.gov (United States)

    Revzan, K L; Fisk, W J; Sextro, R G

    1993-10-01

    Radon entry into a Florida house whose concrete slab is supported by a permeable concrete-block stem wall and a concrete footer is modeled. The slab rests on backfill material; the same material is used to fill the footer trench. A region of undisturbed soil is assumed to extend 10 m beyond and below the footer. The soil is assumed homogeneous and isotropic except for certain simulations in which soil layers of high permeability or radium content are introduced. Depressurization of the house induces a pressure field in the soil and backfill. The Laplace equation, resulting from Darcy's law and the continuity equation, is solved using a steady-state finite-difference model to determine this field. The mass-transport equation is then solved to obtain the diffusive and advective radon entry rates through the slab; the permeable stem wall; gaps at the intersections of the slab, stem wall, and footer; and gaps in the slab. These rates are determined for variable soil, backfill, and stem-wall permeability and radium content, slab-opening width and position, slab and stem-wall diffusivity, and water table depth. The variations in soil permeability and radium content include cases of horizontally stratified soil. We also consider the effect of a gap between the edge of the slab and the stem wall that restricts the passage of soil gas from the stem wall into the house. Calculations indicate that the total radon entry rate is relatively low unless the soil or backfill permeability or radium content is high. Variations in most of the factors, other than the soil permeability and radium content, have only a small effect on the total radon entry rate. However, for a fixed soil permeability, the total radon entry rate may be reduced by a factor of 2 or more by decreasing the backfill permeability, by making the stem wall impermeable and gap-free, (possibly by constructing a one-piece slab/stem-wall/footer), or by increasing the pressure in the interior of the stem wall (by

  9. The CAST Time Projection Chamber

    CERN Document Server

    Autiero, D.; Carmona, J.M.; Cebrian, S.; Chesi, E.; Davenport, M.; Delattre, M.; Di Lella, L.; Formenti, F.; Irastorza, I.G.; Gomez, H.; Hasinoff, M.; Lakic, B.; Luzon, G.; Morales, J.; Musa, L.; Ortiz, A.; Placci, A.; Rodriguez, A.; Ruz, J.; Villar, J.A.; Zioutas, K.

    2007-01-01

    One of the three X-ray detectors of the CAST experiment searching for solar axions is a Time Projection Chamber (TPC) with a multi-wire proportional counter (MWPC) as a readout structure. Its design has been optimized to provide high sensitivity to the detection of the low intensity X-ray signal expected in the CAST experiment. A low hardware threshold of 0.8 keV is safely set during normal data taking periods, and the overall efficiency for the detection of photons coming from conversion of solar axions is 62 %. Shielding has been installed around the detector, lowering the background level to 4.10 x 10^-5 counts/cm^2/s/keV between 1 and 10 keV. During phase I of the CAST experiment the TPC has provided robust and stable operation, thus contributing with a competitive result to the overall CAST limit on axion-photon coupling and mass.

  10. Some Theoretical Considerations on Caste

    Directory of Open Access Journals (Sweden)

    Madhusudan Subedi

    2014-05-01

    Full Text Available Caste as a system of social stratification was an encompassing system in the past. There was reciprocal system of exchange goods and services. With time, occupation and mode of generation of livelihood of various caste groups changed, and the traditional form of jajmani system fizzled out. This paper provides an account of changing perspectives of caste relations in social science writing and political discourse. The discourse of caste has been shifted from ritual hierarchy and social discrimination to an instrument to mobilize people for economic and political gain. DOI: http://dx.doi.org/10.3126/dsaj.v7i0.10437 Dhaulagiri Journal of Sociology and Anthropology Vol. 7, 2013; 51-86

  11. Standing sausage modes in curved coronal slabs

    Science.gov (United States)

    Pascoe, D. J.; Nakariakov, V. M.

    2016-09-01

    Context. Magnetohydrodynamic waveguides such as dense coronal loops can support standing modes. The ratios of the periods of oscillations for different longitudinal harmonics depend on the dispersive nature of the waveguide and so may be used as a seismological tool to determine coronal parameters. Aims: We extend models of standing sausage modes in low β coronal loops to include the effects of loop curvature. The behaviour of standing sausage modes in this geometry is used to explain the properties of observed oscillations that cannot be accounted for using straight loop models. Methods: We perform 2D numerical simulations of an oscillating coronal loop, modelled as a dense slab embedded in a potential magnetic field. The loop is field-aligned and so experiences expansion with height in addition to being curved. Standing sausage modes are excited by compressive perturbations of the loop and their properties are studied. Results: The spatial profiles of standing sausage modes are found to be modified by the expanding loop geometry typical for flaring loops and modelled by a potential magnetic field in our simulations. Longitudinal harmonics of order n > 1 have anti-nodes that are shifted towards the loop apex and the amplitude of anti-nodes near the loop apex is smaller than those near the loop footpoints. Conclusions: We find that the observation of standing sausage modes by the Nobeyama Radioheliograph in a flaring coronal loop on 12 January 2000 is consistent with interpretation in terms of the global mode (n = 1) and third harmonic (n = 3). This interpretation accounts for the period ratio and spatial structure of the observed oscillations.

  12. Inoculation of chromium white cast iron

    Directory of Open Access Journals (Sweden)

    D. Kopyciński

    2009-01-01

    Full Text Available It has been proved that an addition of boron carbide introduced as an inoculant to the chromium white cast iron changes the structureof castings. Castings after inoculation revealed a different structure with numerous grains. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  13. Numerical simulation and fabrication of silicon sheet via spin casting.

    Science.gov (United States)

    Lee, Jaewoo; Kim, Hyunhui; Lee, Changbum; Kim, Joonsoo; Jang, Bo-Yun; Lee, Jinseok; Ahn, Youngsoo; Yoon, Wooyoung

    2013-05-01

    A spin-casting process for fabricating polycrystalline silicon sheets for use as solar cell wafers is proposed, and the parameters that control the sheet thickness are investigated. A numerical study of the fluidity of molten silicon indicates that the formation of thin silicon sheets without a mold and via spin casting is feasible. The faster the rotation speed of graphite mold, the thinner the thickness of sheet. After the spread of the molten silicon to cover the graphite mold with rotation speed of above 500 rpm, the solidification has to start. Silicon sheets can be produced by using the centrifugal force under appropriate experimental conditions. The spin-cast sheet had a vertical columnar microstructure due to the normal heat extraction to the substrate, and the sheet lifetime varied from 0.1 microS to 0.3 microS measured by using the microwave photoconductance decay (MW-PCD) to confirm that the spin-cast silicon sheet is applicable to photovoltaics.

  14. Elimination or Minimization of Oscillation Marks: A Path To Improved Cast Surface Quality

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Alan W. Cramb

    2007-12-17

    Oscillation marks are the most recognizable feature of continuous casting and can be related to the subsurface defects that can be found on product rolled from continuous cast slabs. The purpose of this work was to develop strategies that can be used on industrial continuous casters to reduce oscillation mark depth and, in particular, to minimize the formation of hook type defects that are prevalent on ultra low carbon grades. The major focus of the work was on developing a technique to allow heat transfer in the meniscus region of the continuous caster to be measured and the effect of mold slag chemistry and chrystallization to be documented. A new experimental technique was developed that allowed the effect of mold flux chemistry and chrystallization on the radiation heat transfer rate to be measured dynamically.

  15. Modeling radon entry into Florida slab-on-grade houses

    International Nuclear Information System (INIS)

    Revzan, K.L.; Fisk, W.J.; Sextro, R.G.

    1993-01-01

    Radon entry into a Florida house whose concrete slab is supported by a permeable concrete-block stem wall and a concrete footer is modeled. The slab rests on backfill material; the same material is used to fill the footer trench. A region of undisturbed soil is assumed to extend 10 m beyond and below the footer. The soil is assumed homogeneous and isotropic except for certain simulations in which soil layers of high permeability or radium content are introduced. Depressurization of the house induces a pressure field in the soil and backfill. The Laplace equation, resulting from Darcy's law and the continuity equation, is solved using a steady-state finite-difference model to determine this field. The mass-transport equation is then solved to obtain the diffusive and advective radon entry rates through the slab; the permeable stem wall; gaps at the intersections of the slab, stem wall, and footer; and gaps in the slab. These rates are determined for variable soil, backfill, and stem-wall permeability and radium content, slab-opening width and position, slab and stem-wall diffusivity, and water table depth. The variations in soil permeability and radium content include cases of horizontally stratified soil. We also consider the effect of a gap between the edge of the slab and the stem wall that restricts the passage of soil gas from the stem wall into the house. Calculations indicate that the total radon entry rate is relatively low unless the soil or backfill permeability or radium content is high. Variations in most of the factors, other than the soil permeability and radium content, have only a small effect on the total radon entry rate. However, for a fixed soil permeability, the total radon entry rate may be reduced by a factor of 2 or more by decreasing the backfill permeability, by making the stem wall impermeable and gap-free, (possibly by constructing a one-piece slab/stem-wall/footer), or by increasing the pressure in the interior of the stem wall

  16. Optical distortions in end-pumped zigzag slab lasers.

    Science.gov (United States)

    Tang, Bing; Zhou, Tangjian; Wang, Dan; Li, Mi

    2015-04-01

    Ray tracing is performed to investigate the optical distortions in the end-pumped, zigzag slab. Optical path differences caused by temperature, slab deformation, and stress birefringence are calculated under uniform pumping; the results show a steep edge in the width dimension and a thermal lens with an effective focal length as short as several meters in the thickness dimension. Dependence of depolarization on total internal reflection phase retardance as well as the slab's cut angle is studied by the Jones matrix technique; results show that although at the pumping power of 10 kW, the mean depolarization of the 2.5  mm×30  mm×150.2  mm Nd:YAG slab is generally below 3%, and it increases rapidly with pumping power. Besides, for the 0°- or 60°-cut slab, an optimal phase retardance range of 5° to 13° exists, in which the depolarization loss can be lower than 0.5%. Finally, experiments on temperature and depolarization measurements verify the numerical results.

  17. Sub-wavelength grating mode transformers in silicon slab waveguides.

    Science.gov (United States)

    Bock, Przemek J; Cheben, Pavel; Schmid, Jens H; Delâge, André; Xu, Dan-Xia; Janz, Siegfried; Hall, Trevor J

    2009-10-12

    We report on several new types of sub-wavelength grating (SWG) gradient index structures for efficient mode coupling in high index contrast slab waveguides. Using a SWG, an adiabatic transition is achieved at the interface between silicon-on-insulator waveguides of different geometries. The SWG transition region minimizes both fundamental mode mismatch loss and coupling to higher order modes. By creating the gradient effective index region in the direction of propagation, we demonstrate that efficient vertical mode transformation can be achieved between slab waveguides of different core thickness. The structures which we propose can be fabricated by a single etch step. Using 3D finite-difference time-domain simulations we study the loss, polarization dependence and the higher order mode excitation for two types (triangular and triangular-transverse) of SWG transition regions between silicon-on-insulator slab waveguides of different core thicknesses. We demonstrate two solutions to reduce the polarization dependent loss of these structures. Finally, we propose an implementation of SWG structures to reduce loss and higher order mode excitation between a slab waveguide and a phase array of an array waveguide grating (AWG). Compared to a conventional AWG, the loss is reduced from -1.4 dB to < -0.2 dB at the slab-array interface.

  18. Processing and properties of large-sized ceramic slabs

    International Nuclear Information System (INIS)

    Raimondo, M.; Dondi, M.; Zanelli, C.; Guarini, G.; Gozzi, A.; Marani, F.; Fossa, L.

    2010-01-01

    Large-sized ceramic slabs with dimensions up to 360x120 cm 2 and thickness down to 2 mm are manufactured through an innovative ceramic process, starting from porcelain stoneware formulations and involving wet ball milling, spray drying, die-less slow-rate pressing, a single stage of fast drying-firing, and finishing (trimming, assembling of ceramic-fiberglass composites). Fired and unfired industrial slabs were selected and characterized from the technological, compositional (XRF, XRD) and microstructural (SEM) viewpoints. Semi-finished products exhibit a remarkable microstructural uniformity and stability in a rather wide window of firing schedules. The phase composition and compact microstructure of fired slabs are very similar to those of porcelain stoneware tiles. The values of water absorption, bulk density, closed porosity, functional performances as well as mechanical and tribological properties conform to the top quality range of porcelain stoneware tiles. However, the large size coupled with low thickness bestow on the slab a certain degree of flexibility, which is emphasized in ceramic-fiberglass composites. These outstanding performances make the large-sized slabs suitable to be used in novel applications: building and construction (new floorings without dismantling the previous paving, ventilated facades, tunnel coverings, insulating panelling), indoor furnitures (table tops, doors), support for photovoltaic ceramic panels. (Author) 24 refs.

  19. Analysis and design of composite slab by varying different parameters

    Science.gov (United States)

    Lambe, Kedar; Siddh, Sharda

    2018-03-01

    Composite deck slabs are in demand because of its faster, lighter and economical construction work. Composite slab consists of cold formed deck profiled sheet and concrete either lightweight or normal. Investigation of shear behaviour of the composite slab is very complex. Shear bond strength depends on the various parameter such as a shape of sheeting, a thickness of the sheet, type of embossment and its frequency of use, shear stiffener or intermediate stiffener, type of load, an arrangement of load, length of shear span, the thickness of concrete and support friction etc. In present study finite element analysis is carried out with ABAQUS 6.13, a simply supported composite slab is considered for the investigation of the shear bond behaviour of the composite slab by considering variation in three different parameters, the shape of a sheet, thickness of sheet and shear span. Different shear spans of two different shape of cold formed deck profiled sheet i.e. with intermediate stiffeners and without intermediate stiffeners are considered with two different thicknesses (0.8 mm and 1.2 mm) for simulation. In present work, simulation of models has done for static loading with 20 mm mesh size is considered.

  20. Untouchable castes of Uttar Pradesh

    Directory of Open Access Journals (Sweden)

    Kharinin Artem Igorevich

    2015-04-01

    Full Text Available The Untouchable Castes of Uttar Pradesh are examined in this article. This region is one of the most populated in India. Also it is one of the most social mixed-composed in whole State. That’s why main conclusions which were made on this material can be extrapolated to all social space of country. The authors choose four ethno-caste groups, which represent the majority in untouchables and the three smallest in jaties. Their positions in regional hierarchy and economic specialization are analyzed in detail. There are a lot of information about their number, social structure, literacy rating, endogamy, day-to-day practices, customs and other features. Special accents were pointed on mind orientation of their elites toward integration in modern society or, conversely, toward the conservation of traditional forms of existence. The issues of origin and social evolution of untouchable castes of Uttar Pradesh are examined. There is assessment of castes’ sanskritization or other forms of social selfdevelopment. The quality of “scheduled” castes social environment is analyzed. As a marks of its positiveness the data about discrimination untouchables from other social groups and degree of political representativeness of “scheduled” castes, accessibility of education and labour were chosen. The conclusions were made about development degree of some castes. The factors that play role in positive changes in contemporary conditions were determined. The authors put forward their own hypothesis of future development of untouchable castes in Uttar Pradesh. Empiric base of this article was established on sources that have Indian origin and historical and social research of outstanding western indologies.

  1. Initial solidification phenomena: Factors affecting heat transfer in strip casting

    Science.gov (United States)

    Nolli, Paolo

    In the last few years a few companies have announced the final stage of the commercial development of strip casting of steels. In strip casting heat extraction and productivity are limited by the thermal resistance at the interface between processed material and moving mold (rolls for twin-roll strip casters). Among many factors influencing interfacial heat transfer, films of various composition, either formed during casting or deposited before casting on the surface of the rolls, melt superheat and gas atmosphere composition can have a significantly positive or negative effect on the achieved heat transfer rate. From an industrial point view, methods to improve interfacial heat transfer rates must be found, in order to increase productivity. The objective of this research project is to assess if it is feasible to improve heat transfer rates during solidification of steel in direct contact with a copper mold: (1) by the application of thin coatings on the mold surface; (2) by adding a reactive gas species containing sulfur in the gas shrouding where casting is performed. To address the former, solidification experiments were performed with the mold surface either kept uncoated or coated with coatings of different compositions. To address the latter, the experiments were performed in gas shrouding atmospheres with or without sulphydric acid. It was observed that the resulting heat extraction rates were improved by the application of certain coatings and by the addition of H2S to the gas atmosphere. These findings prove that the application of coatings and the use of small amounts of reactive gaseous species containing sulfur may be methods to increase productivity in strip casting. The effect of superheat and the effect of naturally deposited oxides (Mn-oxide) were also evaluated experimentally. A numerical study of the effect of the critical undercooling on the productivity of a twin-roll strip caster showed that the maximum allowable casting speed can be increased

  2. Instant Casting Movie Theater: The Future Cast System

    Science.gov (United States)

    Maejima, Akinobu; Wemler, Shuhei; Machida, Tamotsu; Takebayashi, Masao; Morishima, Shigeo

    We have developed a visual entertainment system called “Future Cast” which enables anyone to easily participate in a pre-recorded or pre-created film as an instant CG movie star. This system provides audiences with the amazing opportunity to join the cast of a movie in real-time. The Future Cast System can automatically perform all the processes required to make this possible, from capturing participants' facial characteristics to rendering them into the movie. Our system can also be applied to any movie created using the same production process. We conducted our first experimental trial demonstration of the Future Cast System at the Mitsui-Toshiba pavilion at the 2005 World Exposition in Aichi Japan.

  3. Standard digital reference images for investment steel castings for aerospace applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 The digital reference images provided in the adjunct to this standard illustrate various types and degrees of discontinuities occurring in thin-wall steel investment castings. Use of this standard for the specification or grading of castings requires procurement of the adjunct digital reference images which illustrate the discontinuity types and severity levels. They are intended to provide the following: 1.1.1 A guide enabling recognition of thin-wall steel casting discontinuities and their differentiation both as to type and degree through digital radiographic examination. 1.1.2 Example digital radiographic illustrations of discontinuities and a nomenclature for reference in acceptance standards, specifications and drawings. 1.2 Two illustration categories are covered as follows: 1.2.1 Graded—Six common discontinuity types each illustrated in eight degrees of progressively increasing severity. 1.2.2 Ungraded—Twelve single illustrations of additional discontinuity types and of patterns and imper...

  4. Assessment of skin dose modification caused by application of immobilizing cast in head and neck radiotherapy

    International Nuclear Information System (INIS)

    Soleymanifard, Shokouhozaman; Toossi, Mohammad T.B.; Khosroabadi, Mohsen; Noghreiyan, Atefeh Vejdani; Shahidsales, Soodabeh; Tabrizi, Fatemeh Varshoee

    2014-01-01

    Skin dose assessment for radiotherapy patients is important to ensure that the dose received by skin is not excessive and does not cause skin reactions. Immobilizing casts may have a buildup effect, and can enhance the skin dose. This study has quantified changes to the surface dose as a result of head and neck immobilizing casts. Medtech and Renfu casts were stretched on the head of an Alderson Rando-Phantom. Irradiation was performed using 6 and 15 MV X-rays, and surface dose was measured by thermoluminescence dosimeters. In the case of 15MV photons, immobilizing casts had no effect on the surface dose. However, the mean surface dose increase reached up to 20 % when 6MV X-rays were applied. Radiation incidence angle, thickness, and meshed pattern of the casts affected the quantity of dose enhancement. For vertical beams, the surface dose increase was more than tangential beams, and when doses of the points under different areas of the casts were analysed separately, results showed that only doses of the points under the thick area had been changed. Doses of the points under the thin area and those within the holes were identical to the same points without immobilizing casts. Higher dose which was incurred due to application of immobilizing casts (20 %) would not affect the quality of life and treatment of patients whose head and neck are treated. Therefore, the benefits of head and neck thermoplastic casts are more than their detriments. However, producing thinner casts with larger holes may reduce the dose enhancement effect.

  5. Dispersion and rheological studies of Y–PSZ tape casting slurry

    Indian Academy of Sciences (India)

    Optimized tape casting slurry was prepared using PEG 600 and BBP as plasticizers and PVB as the binder. Cyclohexanone was used as the homogenizer. The optimized slurry composition with 58% solid loading exhibited shear-thinning pseudoplastic rheological behaviour. Y–PSZ tapes of ∼ 50 m thickness free from ...

  6. Thermal distortion of disc-shaped ductile iron castings in vertically parted moulds

    DEFF Research Database (Denmark)

    Vedel-Smith, Nikolaj Kjelgaard; Rasmussen, Jakob; Tiedje, Niels Skat

    2015-01-01

    A disc-shaped casting with an inner boss and an outer rim, separated by a thin walled section, was examined. This measurable deformation varied with the feeding modulus. The influence of alloy composition, particularly Si content, was examined with a pearlitic ductile iron (EN-GJS-500-7) and a fu...

  7. High-Mobility Aligned Pentacene Films Grown by Zone-Casting

    DEFF Research Database (Denmark)

    Duffy, Claudia M.; Andreasen, Jens Wenzel; Breiby, Dag W.

    2008-01-01

    We investigate the growth and field-effect transistor performance of aligned pentacene thin films deposited by zone-casting from a solution of unsubstituted pentacene molecules in a chlorinated solvent. Polarized optical microscopy shows that solution processed pentacene films grow as large cryst...

  8. The Effect of Shell Thickness, Insulation and Casting Temperature on Defects Formation During Investment Casting of Ni-base Turbine Blades

    Directory of Open Access Journals (Sweden)

    Raza M.

    2015-12-01

    Full Text Available Turbine blades have complex geometries with free form surface. Blades have different thickness at the trailing and leading edges as well as sharp bends at the chord-tip shroud junction and sharp fins at the tip shroud. In investment casting of blades, shrinkage at the tip-shroud and cord junction is a common casting problem. Because of high temperature applications, grain structure is also critical in these castings in order to avoid creep. The aim of this work is to evaluate the effect of different process parameters, such as, shell thickness, insulation and casting temperature on shrinkage porosity and grain size. The test geometry used in this study was a thin-walled air-foil structure which is representative of a typical hot-gas-path rotating turbine component. It was observed that, in thin sections, increased shell thickness helps to increase the feeding distance and thus avoid interdendritic shrinkage. It was also observed that grain size is not significantly affected by shell thickness in thin sections. Slower cooling rate due to the added insulation and steeper thermal gradient at metal mold interface induced by the thicker shell not only helps to avoid shrinkage porosity but also increases fill-ability in thinner sections.

  9. Development of Flexible Link Slabs using Ductile Fiber Reinforced Concrete

    DEFF Research Database (Denmark)

    Lárusson, Lárus Helgi

    Civil engineering structures with large dimensions, such as multi-span bridges, overpasses and viaducts, are typically equipped with mechanical expansion joints. These joints allow the individual spans of the structure to undergo unrestrained deformations due to thermal expansions and load......, it is suggested to replace the mechanical expansion joint and implement a flexible, precast ductile concrete link slab element between simply supported bridge spans. To design and analyze the suggested link slab element, each constituent of the element, i.e. the structural reinforcement and the cementitious...... and under cyclic loading. The findings from the investigations on bond-slip, tension stiffening and tension strengthening are used in Chapter 5 as inputfor the design and analysis of the loaddeformation response and the crack development of a prefabricated flexible link slab elements potentially connecting...

  10. Abrupt tectonics and rapid slab detachment with grain damage.

    Science.gov (United States)

    Bercovici, David; Schubert, Gerald; Ricard, Yanick

    2015-02-03

    A simple model for necking and detachment of subducting slabs is developed to include the coupling between grain-sensitive rheology and grain-size evolution with damage. Necking is triggered by thickened buoyant crust entrained into a subduction zone, in which case grain damage accelerates necking and allows for relatively rapid slab detachment, i.e., within 1 My, depending on the size of the crustal plug. Thick continental crustal plugs can cause rapid necking while smaller plugs characteristic of ocean plateaux cause slower necking; oceanic lithosphere with normal or slightly thickened crust subducts without necking. The model potentially explains how large plateaux or continental crust drawn into subduction zones can cause slab loss and rapid changes in plate motion and/or induce abrupt continental rebound.

  11. Band-notched ultrawide band antenna loaded with ferrite slab

    Science.gov (United States)

    Wang, Hao; Zong, Weihua; Sun, Nian X.; Lin, Hwaider; Li, Shandong

    2017-05-01

    In this paper, a novel technique to design a band-notched UWB antenna by using Yttrium Iron Garnet (YIG) ferrite is proposed. A printed slot UWB antenna with size of 21mm×26 mm×0.8 mm is adopted as a basic antenna. A piece of ferrite slab with size of 5 mm×10 mm×2 mm is attached on the feeding layer of the antenna to achieve band-notched characteristics. The measured -10 dB bandwidth of the antenna without ferrite slab is 2.91-10.98 GHz. With loading of ferrite slab, the bandwidth turns to 2.73-5.12 and 5.87-10.78 GHz. A band notch of 5.12- 5.87 GHz is achieved to filter WLAN 5 GHz (5.15-5.825 GHz) band. The proposed technique has virtue of easy fabrication and keeping antenna miniaturization.

  12. Optimal Material Layout - Applied on Reinforced Concrete Slabs

    DEFF Research Database (Denmark)

    Dollerup, Niels; Jepsen, Michael S.; Damkilde, Lars

    2015-01-01

    This paper introduces a general, finite-element-based optimisation tool for improving the material layout of concrete structures. The application presented is general and exemplified by material optimisation of reinforced concrete slabs. By utilising the optimisation tool, it is possible to deter......This paper introduces a general, finite-element-based optimisation tool for improving the material layout of concrete structures. The application presented is general and exemplified by material optimisation of reinforced concrete slabs. By utilising the optimisation tool, it is possible...... to determine the optimal material layout of a slab in the ultimate load state, based on simple inputs such as outer geometry, boundary conditions, multiple load cases and design domains. The material layout of the optimal design can either be fully orthotropic or isotropic, or a combination with a predefined...

  13. Criticality of neutron transport in a slab with finite reflectors

    International Nuclear Information System (INIS)

    Pao, C.V.

    1978-01-01

    The purpose of this paper is to investigate the subcriticality and the supercriticality for the neutron transport in a slab which is surrounded by two finite reflectors. The mathematical problem is to determine when the coupled boundary-value problem has or has no positive solution. It is shown under some explicit conditions on the material properties of the transport mediums and the size of the slab length that the coupled problem has a unique solution which insures the subcriticality of the system. It is also shown under some different conditions on the same physical quantities that the system cannot have a nonnegative solution when there is an external source, and it only has the trivial solution when there is no source in the system. This conclusion leads to the supercriticality of the system. Both upper and lower bounds for the critical length of the slab are explicitly given

  14. Microinstabilities in a radially contracting inhomogeneous cylindrical plasma slab

    International Nuclear Information System (INIS)

    Deutsch, R.; Kaeppeler, H.J.

    1980-07-01

    In order to study the development of microinstabilities in a collapsing cylindrical plasma sheath, corresponding to the situations in a z-pinch or a plasma focus, the dispersion relation for electromagnetic perturbations is derived with the aid of a newly established slab-model for an inhomogeneous, radially contracting plasma. In contrast to previously used slab-models, the orientation of the electric field is in direction of the cylinder axis and the azimuthal magnetic field is induced by the current flowing through the cylindrical plasma slab. The Vlasov equation is used together with the Krook collision term in order to include the influence of collisions. The results of this theory presented in this report will be used to calculate the growth of drift instabilities in the compression phase of a plasma focus, and shall serve as a basis for further development of a more general dispersion relation including runaway-effects. (orig.)

  15. IMPROVEMENT OF SLAB REHEATING PROCESS AT USIMINAS THROUGH MATHEMATICAL SIMULATION

    Directory of Open Access Journals (Sweden)

    Antônio Adel dos Santos

    2012-09-01

    Full Text Available Basic characteristics and application examples of the mathematical simulator for reheating process in walking-beam type furnaces, that has been developed and applied to Usiminas plate mill line at Ipatinga, are shown in this paper. This is a bi-dimensional mathematical model solved by the finite volume method, validated by temperature measurements inside the slab during heating and coded as a visual tool. Among these applications, the following can be highlighted: (i determination of suitable furnace zone temperatures and residence times for processing steels by accelerated cooling technology; (ii determination of slab average temperature at discharging as well as at each zone exit, supplying data to be fed to the automation system at the comissioning stage; (iii analyses of slab thermal distribution through the reheating process, enabling operational optimization

  16. Cost Effectiveness of Precast Reinforced Concrete Roof Slabs

    Science.gov (United States)

    Parskiy, N. D.; Molodtsov, M. V.; Molodtsova, V. E.

    2017-11-01

    Engineers always seek to free interior space from intermediate supporting elements. Nowadays plants, being at the forefront of technology, produce a new generation of exclusive patented prefabricated reinforced concrete elements with a high load-bearing capacity, excellent heat resistance characteristics combined with the aesthetics and beauty. It is a system of Seagull Gabbiano prestressed roof slabs for the spans of 12m - 40m. The article shows the advantages of the Seagull slabs over conventional precast reinforced concrete and metal roof trusses. It also gives the analysis of the technical and economic indices of design and construction of a building with the Seagull slabs depending on the size of spans to cover. The use of structural systems with increased spans allows for the modern buildings and structures of prefabricated reinforced concrete with enhanced functionality and aesthetics alongside with a wide range of planning solutions.

  17. Investigation on Blast Resistance of Precast Reinforced Concrete Floor Slab

    Science.gov (United States)

    Bonora, Nicola; Gentile, Domenico; Iannitti, Gianluca; Ruggiero, Andrew; Testa, Gabriel; Bernabei, Manuele; Cassioli, Luigi; Grossi, Silvana

    2017-06-01

    The knowledge of the effective blast resistance of civil infrastructures is a fundamental information for risk assessment and modelling consequences of terrorist attack in high population density urban environment. In this work, blast resistance of precast reinforced concrete floor slab, commonly used for commercial parking, was investigated performing blast tests, detonating bare explosive charge of RDX 80-20 in contact with the slab. The charge mass, and the stand-off distance, was varied in order to generate different damage extents, from visible to fully breached condition. Numerical simulations were performed considering all slab structural elements. Failure model for concrete was calibrated on breach size and shape observed in the experiments. The explosive and blast wave-structure interaction were simulated using arbitrary Lagrangian-Eulerian method (ALE) and particle blast method (PBM) for comparison.

  18. Development of vacuum die-casting process

    OpenAIRE

    Masashi Uchida

    2009-01-01

    The vacuum die-casting process, started 25 years ago in Japan, has been widely applied. This technology contributes very much to improvement of castings quality. The main factor causing the defects of die castings is the trapped air in the mold cavity, while the key technology of vacuum die-casting process is to avoid the trapped air effectively by evacuating the cavity before casting. At the same time, due to the shot speed and the casting pressure reduced in half, the service life of the di...

  19. Radon Sub-slab Suctioning System Integrated in Insulating Layer

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn

    2013-01-01

    This poster presents a new radon sub-slab suctioning system. This system makes use of a grid of horizontal pressurised air ducts located within the lower part of the rigid insulation layer of the ground floor slab. For this purpose a new system of prefabricated lightweight elements is introduced....... The system is shown to be effective in preventing radon from polluting the indoor air by introducing low pressure in the horizontal grid of air ducts. How to implement and use the system in an effective way is described....

  20. Seismic Behaviour of Masonry Vault-Slab Structures

    International Nuclear Information System (INIS)

    Chesi, Claudio; Butti, Ferdinando; Ferrari, Marco

    2008-01-01

    Spandrel walls typically play a structural role in masonry buildings, transferring load from a slab to the supporting vault. Some indications are given in the literature on the behaviour of spandrels under the effect of vertical loads, but little attention is given to the effect coming from lateral forces acting on the building. An opportunity to investigate this problem has come from the need of analyzing a monumental building which was damaged by the Nov. 24, 2004 Val Sabbia earthquake in the north of Italy. The finite element model set up for the analysis of the vault-spandrel-slab system is presented and the structural role resulting for the spandrels is discussed

  1. Dynamic evolution of aluminum nanoparticle impacted by RDX slab

    Science.gov (United States)

    Wang, Ning; Cheng, Jie; Li, Haibo; Du, Fang; Li, Chenghu; Hu, Jianjiang; Peng, Jinhua

    2018-03-01

    A modified ReaxFF force field was used to study dynamic deformation of Al nanoparticles (ANPs) and chemical evolution of RDX/Al mixtures. When small ANPs impact RDX crystal planes, the interaction between RDX and Al at the initial stage does not affect the order of shock-induced anisotropic response of RDX crystal and different thickness of alumina shell on ANPs exhibits different capacity to resist structural deformation. When Al slab with 30 wt% is coated with a 3 nm thickness of alumina, Al slab exhibits inert characteristics and provides high compression condition to enhance decomposition of RDX molecules during the initial impact stage.

  2. Concrete mixtures with high-workability for ballastless slab tracks

    Directory of Open Access Journals (Sweden)

    Olga Smirnova

    2017-10-01

    Full Text Available The concrete track-supporting layer and the monolithic concrete slab of ballastless track systems are made in-situ. For this reason the concrete mixtures of high workability should be used. Influence of the sand kind, the quartz microfiller fineness and quantity as well as quantity of superplasticizer on workability of fresh concrete and durability of hardened concrete is shown. The compositions of the high-workability concrete mixtures with lower consumption of superplasticizer are developed. The results of the research can be recommended for high performance concrete of ballastless slab track.

  3. Spalling tests on embedded cores and slabs: A comparative study

    Directory of Open Access Journals (Sweden)

    Pimienta P.

    2013-09-01

    Full Text Available A comparative analysis of the spalling of (a cores made of 3 concrete mixes embedded into 3 slabs made of the 3 same concrete mixes; and (b 3 reference slabs made again of the same 3 concrete mixes has been made. Samples have been exposed to the French Increased HydroCarbon temperature curve. Results confirm that concrete spalling phenomena is not only related to the material properties. Concrete spalling is also very much influenced by the geometry of the samples.

  4. Spalling of concrete: A synthesis of experimental tests on slabs

    Directory of Open Access Journals (Sweden)

    Taillefer Nicolas

    2013-09-01

    Full Text Available The article reviews the results of many commercial or research tests carried out in CSTB on middle size concrete slabs. They concern 22 concrete slabs, made of normal and high strength concrete, for a rather wide range of thickness and compressive strength classes. Test procedures and a synthesis of main results are presented in order to provide deeper understanding of near-reality conditions of concrete structures. The tests concerned both new and existing tunnels. Results are detailed in relation with main parameters that are identified as impacting spalling in previous studies, such as concrete composition, concrete properties and specimen size.

  5. Analog optical computing by half-wavelength slabs

    Science.gov (United States)

    Zangeneh-Nejad, Farzad; Khavasi, Amin; Rejaei, Behzad

    2018-01-01

    A new approach to perform analog optical differentiation is presented using half-wavelength slabs. First, a half-wavelength dielectric slab is used to design a first order differentiator. The latter works properly for both major polarizations, in contrast to our previously design based on Brewster effect (Youssefi et al., 2016). Inspired by the proposed dielectric differentiator, and by exploiting the unique features of graphene, we further design and demonstrate a reconfigurable and highly miniaturized differentiator using a half-wavelength plasmonic graphene film. To the best of our knowledge, our proposed graphene-based differentiator is even smaller than the most compact differentiator presented so far.

  6. Bayesian Inference for Structured Spike and Slab Priors

    DEFF Research Database (Denmark)

    Andersen, Michael Riis; Winther, Ole; Hansen, Lars Kai

    2014-01-01

    Sparse signal recovery addresses the problem of solving underdetermined linear inverse problems subject to a sparsity constraint. We propose a novel prior formulation, the structured spike and slab prior, which allows to incorporate a priori knowledge of the sparsity pattern by imposing a spatial...... Gaussian process on the spike and slab probabilities. Thus, prior information on the structure of the sparsity pattern can be encoded using generic covariance functions. Furthermore, we provide a Bayesian inference scheme for the proposed model based on the expectation propagation framework. Using...

  7. Permanent storage of light in a double-slab structure

    Science.gov (United States)

    Chen, Jiangwei; Yuan, Guoxuan; Tao, Zhikuo

    2017-11-01

    In this paper, we shall demonstrate firstly that a normal incidence can be totally reflected from a slab made of active metamaterial with purely-imaginary-impedance. Then we shall predict that a localized steady state of electromagnetic wave dependent on initial input can exist in a double-slab structure, which relates to the non null solution of equations formed by electromagnetic field boundary conditions. These results may provide a feasible way to effectively treat loss and/or gain problems and thus store electromagnetic wave (light) permanently at room temperature. In addition, our work indicates that metamaterials with purely-imaginary-impedance may enable remarkable electromagnetic phenomena and merit further study.

  8. CAST Physics Proposal to SPSC

    CERN Document Server

    CAST, Collaboration

    2011-01-01

    The CAST experiment has the potential to search for solar axions (dark matter particle candidates) or other particles with similar coupling. E.g., paraphtons (Hidden Sector), chameleons (dark energy), while considering the possibility whether CAST could be transformed to an antenna for relic axions with rest mass up to 0.1 to 1meV. While axion searches suggest detectors with lower background, paraphoton and chameleon searches require detectors with sub-keV threshold energy and the use of transparent windows in front of the Micromegas detectors, which cover 3 out of the 4 CAST magnet exits. Ongoing theoretical estimates and experimental investigations will define the priorities of the suggested 4 physics items of this proposal for the period 2012-2014.

  9. Titanium Aluminide Casting Technology Development

    Science.gov (United States)

    Bünck, Matthias; Stoyanov, Todor; Schievenbusch, Jan; Michels, Heiner; Gußfeld, Alexander

    2017-12-01

    Titanium aluminide alloys have been successfully introduced into civil aircraft engine technology in recent years, and a significant order volume increase is expected in the near future. Due to its beneficial buy-to-fly ratio, investment casting bears the highest potential for cost reduction of all competing production technologies for TiAl-LPTB. However, highest mechanical properties can be achieved by TiAl forging. In view of this, Access e.V. has developed technologies for the production of TiAl investment cast parts and TiAl die cast billets for forging purposes. While these parts meet the highest requirements, establishing series production and further optimizing resource and economic efficiency are present challenges. In order to meet these goals, Access has recently been certified according to aircraft standards, aiming at qualifying parts for production on technology readiness level 6. The present work gives an overview of the phases of development and certification.

  10. Behavior of hybrid high-strength fiber reinforced concrete slab-column connections under the effect of high tempera

    Directory of Open Access Journals (Sweden)

    Reham H. Ahmed

    2016-04-01

    Full Text Available Concrete can be modified to perform in a more ductile form by the addition of randomly distributed discrete fibers in the concrete matrix. The combined effect of the addition of two types of fibers (steel fiber and polypropylene fiber with different percentages to concrete matrix, which is called hybrid effect is currently under investigation worldwide. The current research work presents the conducted experimental program to observe the behavior of hybrid high strength reinforced concrete slab-column connections under the effect of high temperature. For this purpose, ten slab-column connections were casted and tested. The experimental program was designed to investigate the effect of different variables such as concrete mixture, column location and temperature fighting system. All specimens were exposed to a temperature of 500 °C for duration of two hours. To observe the effect of each variable, specimens were divided into four groups according to the studied parameters. The test results revealed that using hybrid high strength concrete HFHSC produced more strength in punching failure compared with high strength concrete HSC when exposed to elevated temperature. Fighting by air had higher initial crack load compared with that for without fighting and fighting by water. On the other hand, fighting by water decreased the ultimate load.

  11. Punching Shear Behavior of Continuous Bubbled Reinforced Reactive Powder Concrete Slab

    Directory of Open Access Journals (Sweden)

    Mohammad Redha K. Mahmood

    2017-03-01

    Full Text Available This paper presents an experimental investigation on punching shear behavior of continuous bubbled reinforced Reactive Powder Concrete (RPC slabs. Bubbled slab is one of the various types of voided slabs. It consists of bubbles placed inside a concrete slab which will reduce the self-weight of the structure by about 35% (Tina Lai 2009. On the other hand, using RPC make it possible for structural member to have smaller dimensions due to the great strength of this type of concrete. In this study, these two method to increase the building spaces dimensions by reducing self-weigh of the structure by using bubbled slabs and to decrease the structural members' dimensions by using RPC have been investigated together. To study the punching shear behavior of continuous bubbled flat slabs such as the ultimate load carrying capacity, central deflection and slabs crack pattern at the ultimate load, nine different types of slabs were tested. The parameters of the study were type of concrete (RPC and Normal Concrete (NC, bubbles diameter to slab thickness ratio (D/t of (0.6 and 0.7, bubbles location (at all slab area, started from distance D and 1.5D from the center slab and solid slab. The test results show that the crack pattern and ultimate load capacity as well as maximum deflection depends on all of the mentioned parameters, were by increasing (D/t ratio the ultimate load capacity increases about (6.49 and 9.58% for slabs with bubbles started at distance 2D and 3D, respectively. But in the slabs with bubbles at all slab area the ultimate load and the maximum deflection decreases about (6.63 and 9.47% and (7.96 and 6.84% for RPC and NC slabs, respectively. Also, the solid slab increases the ultimate load about (5.28% compare to bubbled slab at all area. It was found that by removing bubbles from center of the slab at distance 2D and 3D the ultimate load will increase about (14.72 and 8.76%, respectively for slabs with (D/t = 0.6 compare to slabs with

  12. Reentry and Ectopic Pacemakers Emerge in a Three-Dimensional Model for a Slab of Cardiac Tissue with Diffuse Microfibrosis near the Percolation Threshold.

    Science.gov (United States)

    Alonso, Sergio; Dos Santos, Rodrigo Weber; Bär, Markus

    2016-01-01

    Arrhythmias in cardiac tissue are generally associated with irregular electrical wave propagation in the heart. Cardiac tissue is formed by a discrete cell network, which is often heterogeneous. Recently, it was shown in simulations of two-dimensional (2D) discrete models of cardiac tissue that a wave crossing a fibrotic, heterogeneous region may produce reentry and transient or persistent ectopic activity provided the fraction of conducting connections is just above the percolation threshold. Here, we investigate the occurrence of these phenomena in three-dimensions by simulations of a discrete model representing a thin slab of cardiac tissue. This is motivated (i) by the necessity to study the relevance and properties of the percolation-related mechanism for the emergence of microreentries in three dimensions and (ii) by the fact that atrial tissue is quite thin in comparison with ventricular tissue. Here, we simplify the model by neglecting details of tissue anatomy, e. g. geometries of atria or ventricles and the anisotropy in the conductivity. Hence, our modeling study is confined to the investigation of the effect of the tissue thickness as well as to the comparison of the dynamics of electrical excitation in a 2D layer with the one in a 3D slab. Our results indicate a strong and non-trivial effect of the thickness even for thin tissue slabs on the probability of microreentries and ectopic beat generation. The strong correlation of the occurrence of microreentry with the percolation threshold reported earlier in 2D layers persists in 3D slabs. Finally, a qualitative agreement of 3D simulated electrograms in the fibrotic region with the experimentally observed complex fractional atrial electrograms (CFAE) as well as strong difference between simulated electrograms in 2D and 3D were found for the cases where reentry and ectopic activity were triggered by the micro-fibrotic region.

  13. Reentry and Ectopic Pacemakers Emerge in a Three-Dimensional Model for a Slab of Cardiac Tissue with Diffuse Microfibrosis near the Percolation Threshold.

    Directory of Open Access Journals (Sweden)

    Sergio Alonso

    Full Text Available Arrhythmias in cardiac tissue are generally associated with irregular electrical wave propagation in the heart. Cardiac tissue is formed by a discrete cell network, which is often heterogeneous. Recently, it was shown in simulations of two-dimensional (2D discrete models of cardiac tissue that a wave crossing a fibrotic, heterogeneous region may produce reentry and transient or persistent ectopic activity provided the fraction of conducting connections is just above the percolation threshold. Here, we investigate the occurrence of these phenomena in three-dimensions by simulations of a discrete model representing a thin slab of cardiac tissue. This is motivated (i by the necessity to study the relevance and properties of the percolation-related mechanism for the emergence of microreentries in three dimensions and (ii by the fact that atrial tissue is quite thin in comparison with ventricular tissue. Here, we simplify the model by neglecting details of tissue anatomy, e. g. geometries of atria or ventricles and the anisotropy in the conductivity. Hence, our modeling study is confined to the investigation of the effect of the tissue thickness as well as to the comparison of the dynamics of electrical excitation in a 2D layer with the one in a 3D slab. Our results indicate a strong and non-trivial effect of the thickness even for thin tissue slabs on the probability of microreentries and ectopic beat generation. The strong correlation of the occurrence of microreentry with the percolation threshold reported earlier in 2D layers persists in 3D slabs. Finally, a qualitative agreement of 3D simulated electrograms in the fibrotic region with the experimentally observed complex fractional atrial electrograms (CFAE as well as strong difference between simulated electrograms in 2D and 3D were found for the cases where reentry and ectopic activity were triggered by the micro-fibrotic region.

  14. Deep India meets deep Asia: a seismological view of lithospheric slab interactions under Hindu Kush and Pamir

    Science.gov (United States)

    Schurr, Bernd; Kufner, Sofia; Sippl, Christian; Schneider, Felix; Yuan, Xiaohui; Ratschbacher, Lothar; Mechie, James

    2016-04-01

    It is part of the plate-tectonic paradigm that buoyant continental lithosphere subducts only in tow of a sinking oceanic plate after continent collision and that large deep (> 100 km) earthquakes occur exclusively in subducted oceanic lithosphere. Yet under the Pamir in Central Asia, far away from any (paleo-)ocean basins, continental lithosphere appears to subduct by itself and the Pamir-Hindu Kush seismic zone is one of the most active intermediate (100-300 km) depth earthquake zones globally. We show that large-scale indentation of cratonic Asia by a promontory of the Indian plate is causing subduction of continental lithosphere under the Pamir and that the Hindu Kush earthquakes are due to detachment of a narrow plate sliver. New precise earthquake hypocenters, a large number of source mechanisms and detailed receiver function sections and tomographic images allow us to distinguish an arcuate, stretched and partly torn slab of Asian lithosphere beneath the Pamir and a piece of Indian lithosphere beneath the deepest Hindu Kush earthquakes. This peculiar double subduction zone arises by contrasting modes of convergence under Pamir and Hindu Kush imposed by the different mechanical properties of the three types of lithosphere involved: We suggest that the buoyant northwestern salient of (1) Cratonic India bulldozes into (2) Cratonic Asia forcing delamination and rollback of its lithosphere. At the same time (3) India's thinned margin tears off from Cratonic India and subducts under Asia. The narrow swath of the subducted Indian continental margin forms a prominent high-velocity anomaly down to the mantle transition zone. Its uppermost section is thinned or already severed and intermediate depth earthquakes cluster at the final neck connecting it to the deeper slab. These images provide a rare glimpse of the ephemeral process of slab break-off.

  15. Slab fluid release: localized in space and time

    Science.gov (United States)

    John, T.; Gussone, N. C.; Podladchikov, Y. Y.

    2012-12-01

    As subducting oceanic plates descend into the Earth's mantle, increasing pressures and temperatures lead to the progressive destabilization of hydrous mineral phases and the release of H2O-rich fluids. Some fraction of these fluids ascend into the overlying mantle wedge, inducing partial melting, and their "chemical freight" is thought to contribute to the distinctive chemical signature of the resulting arc magmas. Field evidences suggest that channelized fluid flow may be the dominant mechanism for intra-slab fluid flow. Along their pathways within slabs, these fluids can trigger mineral reactions and produce chemical changes in rocks with which they interact. However, the spatial and temporal scales of this fluid flow remain largely unknown. We employed the Ca and Li isotope systems on a fossil high-pressure fluid pathway and its associated reaction halo (Chinese Tianshan), formed at ~70 km depth during subduction of a coherent oceanic slab, allowing us to constrain the fluid flux, fluid source and the duration of the fluid-rock interaction. In the reaction halo, the degree of eclogitization along with Ca concentration increases towards the vein. A high fluid flux is required to obtain the observed Ca increase and changes in δ44/40Ca. The Ca isotope composition indicate mixing of two distinct Ca sources, the wall-rock blueschist and an external fluid source, the latter of which is enriched in heavy Ca isotopes. The relatively high δ44/40Ca (>1.3‰) of the infiltrating fluid is suggestive of partially hydrated slab mantle as the fluid source. Alternatively, Ca derived from MORB, (0.7 to 0.9‰) and AOC (0.6 to 1.0‰) might evolve towards heavier Ca isotope values while it is ascending through the slab and reacting with wall-rocks and forming carbonates, which are usually associated with the flow structures. This is because calcium carbonate precipitation preferentially removes light Ca from the fluid while the residual fluid will get heavier proportional to

  16. Investigation of approach slab and its settlement for roads and bridges.

    Science.gov (United States)

    2014-01-01

    Approach slabs serve as a transitional system between an approach road and a bridge. Settlement of bridge approach slabs and their : supporting backfill has been experienced by more than ten Departments of Transportation throughout the United States....

  17. Punching Shear in Steel Fibre Reinforced Concrete Slabs Without Traditional Reinforcement

    Science.gov (United States)

    Tan, K. H.; Venkateshwaran, A.

    2017-09-01

    The punching shear capacity of steel fibre reinforced concrete (SFRC) slabs without traditional steel bar reinforcement was investigated by conducting central point-load tests on twelve square slabs. The test parameters covered fibres with different multi-hook ends, concrete compressive strength, reinforcing index and slab thickness. The statistical performance of two existing models for the prediction of punching shear capacity of SFRC slabs without traditional reinforcement was examined. The load carrying capacity of these slabs were also assessed using the yield line theory. It is noted that the slabs failed primarily in flexure and the yield line theory predicted the load carrying capacities of the slabs most accurately. The reason for a flexural failure in SFRC slabs without steel bars is attributed to the lesser energy required in the propagation of an existing flexural cracks than in the creation of a new circumferential cracks around the column face.

  18. Metal Casting--Industry of the Future

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-23

    This 8-page brochure describes the Office of Industrial Technologies Metal Casting Industry of The Future; a partnership between the Department of Energy and the metal casting industry established to increase industrial energy and cost efficiency.

  19. CAST-IRONS AT HIGH TEMPERATURES

    Directory of Open Access Journals (Sweden)

    A. N. Krutilin

    2008-01-01

    Full Text Available The results of investigations of physical-mechanical characteristics of cast iron slugs, received by semicontinuos way of casting, at temperatures from 850 up to 1100^ С are given. 

  20. Cast Care: Do's and Don'ts

    Science.gov (United States)

    ... al. Cast care. In: Instructions for Sports Medicine Patients. 2nd ed. Philadelphia, Pa.: Saunders Elsevier; 2012. https://www.clinicalkey.com. Accessed Jan. 25, 2018. Pfenninger JL, et al. Casts immobilization and upper extremity splinting. In: Pfenninger and Fowler's ...

  1. WEAR-RESISTANCE OF CHROMIC CAST IRONS OF EUTECTIC COMPOSITION

    Directory of Open Access Journals (Sweden)

    K. E. Baranovskij

    2009-01-01

    Full Text Available Casting of wear-resistant chrome cast irons in combined molds and iron chills is studied. Application of these ways of casting results in blending of carbides and increasing of hardness of castings.

  2. Parametric excitation of drift waves in a sheared slab geometry

    International Nuclear Information System (INIS)

    Vranjes, J.; Weiland, J.

    1992-01-01

    The threshold for parametric excitation of drift waves in a sheared slab geometry is calculated for a pump wave that is a standing wave along the magnetic field, using the Hasegawa-Mima nonlinearity. The shear damping is counteracted by the parametric coupling and the eigenvalue problem is solved analytically using Taylor's strong coupling approximation. (au)

  3. Characterization of pore structure of PHEMA-based slabs

    Czech Academy of Sciences Publication Activity Database

    Hradil, Jiří; Horák, Daniel

    2005-01-01

    Roč. 62, - (2005), s. 1-9 ISSN 1381-5148 R&D Projects: GA MŠk LN00A065 Institutional research plan: CEZ:AV0Z4050913 Keywords : poly(2-hydroxyethyl methacrylate) * ethylene dimethacrylate * slabs Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.565, year: 2005

  4. Lower Bound Limit Analysis Of Slabs With Nonlinear Yield Criteria

    DEFF Research Database (Denmark)

    Krabbenhøft, Kristian; Damkilde, Lars

    2002-01-01

    A finite element formulation of the limit analysis of perfectly plastic slabs is given. An element with linear moment fields for which equilibrium is satisfied exactly is used in connection with an optimization algorithm taking into account the full nonlinearity of the yield criteria. Both load...

  5. Analysis of Concrete Slabs Subject to Concentrated Loads | Albrecht ...

    African Journals Online (AJOL)

    A simplified procedure for the calculation of the additional reinforcement which is required under concentrated loads acting on concrete slabs is provided. The introduced method can also be used for the treatment of line loads. Conditions for the application of this procedure are stated and tables for necessary design values ...

  6. Enhancement of polarizabilities of cylinders with cylinder-slab resonances.

    Science.gov (United States)

    Xiao, Meng; Huang, Xueqin; Liu, H; Chan, C T

    2015-02-02

    If an object is very small in size compared with the wavelength of light, it does not scatter light efficiently. It is hence difficult to detect a very small object with light. We show using analytic theory as well as full wave numerical calculation that the effective polarizability of a small cylinder can be greatly enhanced by coupling it with a superlens type metamaterial slab. This kind of enhancement is not due to the individual resonance effect of the metamaterial slab, nor due to that of the object, but is caused by a collective resonant mode between the cylinder and the slab. We show that this type of particle-slab resonance which makes a small two-dimensional object much "brighter" is actually closely related to the reverse effect known in the literature as "cloaking by anomalous resonance" which can make a small cylinder undetectable. We also show that the enhancement of polarizability can lead to strongly enhanced electromagnetic forces that can be attractive or repulsive, depending on the material properties of the cylinder.

  7. Optimization of design formulations for reinforced concrete slabs ...

    African Journals Online (AJOL)

    The predictions for flexural requirement in singly reinforced concrete slabs and sections have been assessed using the minimum weight approach and mathematical programming. Results indicate that although the predictions in the codes are safe; they are quite conservative, expensive and encourage although the ...

  8. Bayesian Inference for Structured Spike and Slab Priors

    DEFF Research Database (Denmark)

    Andersen, Michael Riis; Winther, Ole; Hansen, Lars Kai

    2014-01-01

    Sparse signal recovery addresses the problem of solving underdetermined linear inverse problems subject to a sparsity constraint. We propose a novel prior formulation, the structured spike and slab prior, which allows to incorporate a priori knowledge of the sparsity pattern by imposing a spatial...

  9. Designing Meta Material Slabs Exhibiting Negative Refraction Using Topology Optimization

    DEFF Research Database (Denmark)

    Christiansen, Rasmus Ellebæk; Sigmund, O.

    2016-01-01

    This paper proposes a topology optimization based approach for designing meta materials exhibiting a desired negative refraction with high transmission at a given angle of incidence and frequency. The approach considers a finite slab of meta material consisting of axis-symmetric designable unit...

  10. Structural response of reinforced concrete slabs to impulsive loads

    International Nuclear Information System (INIS)

    Florence, A.L.

    1977-01-01

    The structure treated here is a clamped circular slab of reinforced concrete. The loading is a rectangular pulse uniformly distributed over a central area. The practical value of this problem is that it probably represents a most severe loading case for bending response among more realistic cases, because it replaces the local loaded area with a circular area at the slab center, and because it replaces the pulse with a rectangular pulse of the same peak pressure and impulse. In the theoretical treatment the pulse is assumed to produce plastic deformations large enough to neglect elastic deformation but small enough to neglect membrane action. Yielding of the reinforced concrete slab is assumed to be governed by the Johansen criterion and the associated flow rule. For simplicity, the analysis is restricted to isotropic slabs with top and bottom steel reinforcement arranged to provide the same yield moment magnitude for positive and negative curvature changes. A consequence of the assumed rigid-perfectly plastic behavior is that the deformation modes may be considered as simple mechanism governed by a yield circle. Moreover, the yield circle is stationary while the constant pressure is being applied and expands to the support once the pressure is removed. After the yield circle has arrived at the support, the remaining deformation occurs in the static collapse mode. The principal results are explicit simple formulas for permanent central deflection in terms of pressure, duration, loaded area radius, and plate properties (radius, density, yield moment)

  11. Tensor-guided fitting of subduction slab depths

    Science.gov (United States)

    Bazargani, Farhad; Hayes, Gavin P.

    2013-01-01

    Geophysical measurements are often acquired at scattered locations in space. Therefore, interpolating or fitting the sparsely sampled data as a uniform function of space (a procedure commonly known as gridding) is a ubiquitous problem in geophysics. Most gridding methods require a model of spatial correlation for data. This spatial correlation model can often be inferred from some sort of secondary information, which may also be sparsely sampled in space. In this paper, we present a new method to model the geometry of a subducting slab in which we use a data‐fitting approach to address the problem. Earthquakes and active‐source seismic surveys provide estimates of depths of subducting slabs but only at scattered locations. In addition to estimates of depths from earthquake locations, focal mechanisms of subduction zone earthquakes also provide estimates of the strikes of the subducting slab on which they occur. We use these spatially sparse strike samples and the Earth’s curved surface geometry to infer a model for spatial correlation that guides a blended neighbor interpolation of slab depths. We then modify the interpolation method to account for the uncertainties associated with the depth estimates.

  12. Use of fiber reinforced concrete for concrete pavement slab replacement.

    Science.gov (United States)

    2014-03-01

    Unlike ordinary concrete pavement, replacement concrete slabs need to be open to traffic within 24 hours (sooner in : some cases). Thus, high early-strength concrete is used; however, it frequently cracks prematurely as a result of high : heat of hyd...

  13. Concrete slabs under a combination of loads in shear

    NARCIS (Netherlands)

    Lantsoght, E.O.L.; Van der Veen, C.; Walraven, J.C.

    2013-01-01

    Previous experimental research at Delft University of Technology indicated an increased shear capacity of slabs under concentrated loads as a function of decreasing distance to the adjacent line support. Expressions have been derived for this increase, including the definition of an appropriate

  14. Collisional Effect On Magnetosonic Solitons In A Dusty Plasma Slab ...

    African Journals Online (AJOL)

    An analytical investigation of collisional effect on magnetosonic solitons in a dusty plasma slab is presented. We have derived and presented solutions of nonlinear magetohydrodynamic equations for a warm dusty magnetoplasma. It is observed that, our work could be considered a general case for magnetosonic solutions ...

  15. Behavior of the equivalent slab thickness over three European stations

    Czech Academy of Sciences Publication Activity Database

    Mosert, M.; Magdaleno, S.; Burešová, Dalia; Altadill, D.; Gende, M.; Gularte, E.; Scida, L.

    2013-01-01

    Roč. 51, č. 4 (2013), s. 677-682 ISSN 0273-1177 Institutional support: RVO:68378289 Keywords : Ionospheric slab thickness * F2- layer peak * TEC * European stations Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.238, year: 2013 http://www.sciencedirect.com/science/article/pii/S0273117712003754

  16. A differentiated plane wave: its passage through a slab

    International Nuclear Information System (INIS)

    Hannay, J H; Nye, J F

    2013-01-01

    Differentiating a monochromatic uniform plane electromagnetic wavefield with respect to its direction produces, from a field that is completely lacking in localized specific features, one that contains a straight vortex-like line, a ‘C-line’ of defined circular polarization. There is also a second separate C-line of opposite handedness; indeed, in a sense, a straight line of every polarization is realized. Because of its primitive construction it is analytically simple to study the passage of a differentiated wave obliquely through a plane interface into a medium of different refractive index, to trace its C-line. This was done in an earlier paper. Here we extend the method to passage through a parallel-sided transparent slab. There are multiple reflections within the slab, as in a Fabry–Pérot interferometer. The exiting wave, as a single differentiated plane wave, has a straight oblique C-line. Inside the slab, and in front of it, there is wave interference. The result is a coiled, helix-like, C-line in front of the slab and another inside it. The two coils wrap around separate hyperboloids of one sheet, like cooling towers. The emerging straight C-line is shifted (with respect to a C-line in a notional undisturbed incident plane wave) both in the plane of incidence and transversely to it, and the second C-line behaves similarly. The analysis is exact and could be extended in a straightforward way to a general stratified medium. (paper)

  17. Fringe integral equation method for a truncated grounded dielectric slab

    DEFF Research Database (Denmark)

    Jørgensen, Erik; Maci, S.; Toccafondi, A.

    2001-01-01

    The problem of scattering by a semi-infinite grounded dielectric slab illuminated by an arbitrary incident TMz polarized electric field is studied by solving a new set of “fringe” integral equations (F-IEs), whose functional unknowns are physically associated to the wave diffraction processes...

  18. Emplacement of the Kodiak batholith and slab-window migration

    Science.gov (United States)

    Farris, David W.; Haeussler, P.; Friedman, R.; Paterson, Scott R.; Saltus, R.W.; Ayuso, R.

    2006-01-01

    The Kodiak batholith is one of the largest, most elongate intrusive bodies in the forearc Sanak-Baranof plutonic belt located in southern Alaska. This belt is interpreted to have formed during the subduction of an oceanic spreading center and the associated migration of a slab window. Individual plutons of the Kodiak batholith track the location and evolution of the underlying slab window. Six U/Pb zircon ages from the axis of the batholith exhibit a northeastward-decreasing age progression of 59.2 ± 0.2 Ma at the southwest end to 58.4 ± 0.2 Ma at the northeast tip. The trench-parallel rate of age progression is within error of the average slab-window migration rate for the entire Sanak-Baranof belt (~19 cm/yr). Structural relationships, U/Pb ages, and a model of new gravity data indicate that magma from the Kodiak batholith ascended 5-10 km as a northeastward-younging series of 1-8-km-diameter viscoelastic diapirs. Individual plutons ascended by multiple emplacement mechanisms including downward flow, collapse of wall rock, stoping, and diking. Stokes flow xenolith calculations suggest ascent rates of 5-100 m/yr and an effective magmatic viscosity of 107-108 Pa s. Pre-existing structural or lithologic heterogeneities did not dominantly control the location of the main batholith. Instead, its location was determined by migration of the slab window at depth. 

  19. Shear and anchorage behaviour of fire exposed hollow core slabs

    NARCIS (Netherlands)

    Fellinger, J.

    2005-01-01

    The fire resistance of hollow core slabs is currently assessed considering flexural failure only. However, fire tests show that shear or anchorage failure can also govern the load bearing behaviour. This paper is based on the dissertation by the author1 and discusses existing and new fire tests. It

  20. Study of global stability of tall buildings with prestressed slabs

    Directory of Open Access Journals (Sweden)

    L. A. Feitosa

    Full Text Available The use of prestressed concrete flat slabs in buildings has been increasing in recent years in the Brazilian market. Since the implementation of tall and slender buildings a trend in civil engineering and architecture fields, arises from the use of prestressed slabs a difficulty in ensuring the overall stability of a building without beams. In order to evaluate the efficiency of the main bracing systems used in this type of building, namely pillars in formed "U" in elevator shafts and stairs, and pillars in which the lengths are significantly larger than their widths, was elaborated a computational models of fictional buildings, which were processed and analyzed using the software CAD/TQS. From the variation of parameters such as: geometry of the pillars, thick slabs, characteristic strength of the concrete, reduceofthe coefficient of inertia for consideration of non-linearities of the physical elements, stiffness of the connections between slabs and pillars, among others, to analyze the influence of these variables on the overall stability of the building from the facing of instability parameter Gama Z, under Brazilian standard NBR 6118, in addition to performing the processing of building using the P-Delta iterative calculation method for the same purpose.

  1. Some consequences of the subduction of young slabs

    NARCIS (Netherlands)

    England, P.; Wortel, R.

    The negative buoyancy force exerted by a subducting oceanic slab depends on its descent velocity, and strongly on its age. For lithosphere close to thermal equilibrium, this force dominates by a large margin the resisting forces arising from friction on the plate boundary and compositional buoyancy.

  2. Puzzling features of western Mediterranean tectonics explained by slab dragging

    Science.gov (United States)

    Spakman, Wim; Chertova, Maria V.; van den Berg, Arie.; van Hinsbergen, Douwe J. J.

    2018-02-01

    The recent tectonic evolution of the western Mediterranean region is enigmatic. The causes for the closure of the Moroccan marine gateway prior to the Messinian salinity crisis, for the ongoing shortening of the Moroccan Rif and for the origin of the seismogenic Trans-Alboran shear zone and eastern Betics extension are unclear. These puzzling tectonic features cannot be fully explained by subduction of the east-dipping Gibraltar slab in the context of the regional relative plate motion frame. Here we use a combination of geological and geodetic data, as well as three-dimensional numerical modelling of subduction, to show that these unusual tectonic features could be the consequence of slab dragging—the north to north-eastward dragging of the Gibraltar slab by the absolute motion of the African Plate. Comparison of our model results to patterns of deformation in the western Mediterranean constrained by geological and geodetic data confirm that slab dragging provides a plausible mechanism for the observed deformation. Our results imply that the impact of absolute plate motion on subduction is identifiable from crustal observations. Identifying such signatures elsewhere may improve the mantle reference frame and provide insights on subduction evolution and associated crustal deformation.

  3. Slab flattening and exhumation of the Eastern Cordillera of Colombia

    Science.gov (United States)

    Siravo, G.; Faccenna, C.; Fellin, M. G.; Herman, F.; Becker, T. W.; Molin, P.

    2017-12-01

    Mountain belt topography is shaped by processes acting at different time scales and depths, from the surface down to the crust and mantle. In particular, subduction dynamics is expected to strongly affect upper plate topography. Here, we present the case of the Eastern Cordillera (EC) in Colombia as a case history for dynamic mantle forcing from a subduction zone on the upper plate topography. The EC is an active double-vergent fold and thrust belt formed during the Cenozoic by the inversion of a Mesozoic rift, and topography there has grown up to 5000 m (Cocuy Sierra). The EC is located far ( 500 km) from the trench where the Nazca slab subducts below the South American plate. Tomography and seismicity show the presence of a flat slab subduction north of 5° N (Chiarabba et al., 2016). Slab flattening may have occurred transitionally from 10 to 5 Ma shutting down the arc volcanism (Wagner et al., 2017). We reconstruct the exhumation of the EC based on previously published and new thermochronologic data collected in the area of the Cocuy Sierra. Results of this analysis show notably fast exhumation rates since Late Miocene. We also analyze the likely contributions to topography and show that neither the present-day crustal thickness nor the cumulative shortening in the Cenozoic as extracted form balanced cross section can isostatically explain the present day topography. We conclude that fast EC exhumation and uplift are driven by mantle dynamics and likely occurred during the recent episode of slab flattening.

  4. Developing technological process of obtaining giality casts

    Directory of Open Access Journals (Sweden)

    A. Issagulov

    2014-10-01

    Full Text Available The article considers the process of manufacturing castings using sand-resin forms and alloying furnace. Were the optimal technological parameters of manufacturing shell molds for the manufacture of castings of heating equipment. Using the same upon receipt of castings by casting in shell molds furnace alloying and deoxidation of the metal will provide consumers with quality products and have a positive impact on the economy in general engineering.

  5. Reducing the Incidence of Cast-related Skin Complications in Children Treated With Cast Immobilization.

    Science.gov (United States)

    Difazio, Rachel L; Harris, Marie; Feldman, Lanna; Mahan, Susan T

    2017-12-01

    Cast immobilization remains the mainstay of pediatric orthopaedic care, yet little is known about the incidence of cast-related skin complications in children treated with cast immobilization. The purposes of this quality improvement project were to: (1) establish a baseline rate of cast-related skin complications in children treated with cast immobilization, (2) identify trends in children who experienced cast-related skin complications, (3) design an intervention aimed at decreasing the rate of cast-related skin complications, and (4) determine the effectiveness of the intervention. A prospective interrupted time-series design was used to determine the incidence of cast-related skin complications overtime and compare the rates of skin complications before and after an intervention designed to decrease the incidence of cast-related heel complications. All consecutive patients who were treated with cast immobilization from September 2012 to September 2014 were included. A cast-related skin complications data collection tool was used to capture all cast-related skin complications. A high rate of heel events was noted in our preliminary analysis and an intervention was designed to decrease the rate of cast-related skin complications, including the addition of padding during casting and respective provider education. The estimated cast-related skin events rate for all patients was 8.9 per 1000 casts applied. The rate for the total preintervention sample was 13.6 per 1000 casts which decreased to 6.6 in the postintervention sample. When examining the heel-only group, the rate was 17.1 per 1000 lower extremity casts applied in the preintervention group and 6.8 in the postintervention group. Incorporating padding to the heel of lower extremity cast was an effective intervention in decreasing the incidence of cast-related skin complications in patients treated with cast immobilization. Level II.

  6. Advanced Lost Foam Casting Technology

    Energy Technology Data Exchange (ETDEWEB)

    Charles E. Bates; Harry E. Littleton; Don Askeland; Taras Molibog; Jason Hopper; Ben Vatankhah

    2000-11-30

    This report describes the research done under the six tasks to improve the process and make it more functional in an industrial environment. Task 1: Pattern Pyrolysis Products and Pattern Properties Task 2: Coating Quality Control Task 3: Fill and Solidification Code Task 4: Alternate Pattern Materials Task 5: Casting Distortion Task 6: Technology Transfer

  7. Inoculation Effects of Cast Iron

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2012-12-01

    Full Text Available The paper presents a solidification sequence of graphite eutectic cells of A and D types, as well as globular and cementite eutectics. The morphology of eutectic cells in cast iron, the equations for their growth and the distances between the graphite precipitations in A and D eutectic types were analyzed. It is observed a critical eutectic growth rate at which one type of eutectic transformed into another. A mathematical formula was derived that combined the maximum degree of undercooling, the cooling rate of cast iron, eutectic cell count and the eutectic growth rate. One type of eutectic structure turned smoothly into the other at a particular transition rate, transformation temperature and transformational eutectic cell count. Inoculation of cast iron increased the number of eutectic cells with flake graphite and the graphite nodule count in ductile iron, while reducing the undercooling. An increase in intensity of inoculation caused a smooth transition from a cementite eutectic structure to a mixture of cementite and D type eutectic structure, then to a mixture of D and A types of eutectics up to the presence of only the A type of eutectic structure. Moreover, the mechanism of inoculation of cast iron was studied.

  8. Graphite Formation in Cast Iron

    Science.gov (United States)

    Stefanescu, D. M.

    1985-01-01

    In the first phase of the project it was proven that by changing the ratio between the thermal gradient and the growth rate for commercial cast iron samples solidifying in a Bridgman type furnace, it is possible to produce all types of graphite structures, from flake to spheroidal, and all types of matrices, from ferritic to white at a certain given level of cerium. KC-135 flight experiments have shown that in a low-gravity environment, no flotation occurs even in spheroidal graphite cast irons with carbon equivalent as high as 5%, while extensive graphite flotation occurred in both flake and spheroidal graphite cast irons, in high carbon samples solidified in a high gravity environment. This opens the way for production of iron-carbon composite materials, with high carbon content (e.g., 10%) in a low gravity environment. By using KC-135 flights, the influence of some basic elements on the solidification of cast iron will be studied. The mechanism of flake to spheroidal graphite transition will be studied, by using quenching experiments at both low and one gravity for different G/R ratios.

  9. Search for chameleons with CAST

    DEFF Research Database (Denmark)

    Anastassopoulos, V.; Arik, M.; Aune, S.

    2015-01-01

    In this work we present a search for (solar) chameleons with the CERN Axion Solar Telescope (CAST). This novel experimental technique, in the field of dark energy research, exploits both the chameleon coupling to matter (βm) and to photons (βΥ) via the Primako eect. By reducing the X-ray detection...

  10. Cure shrinkage in casting resins

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, J. Brock [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-02-01

    A method is described whereby the shrinkage of a casting resin can be determined. Values for the shrinkage of several resin systems in frequent use by Sandia have been measured. A discussion of possible methods for determining the stresses generated by cure shrinkage and thermal contraction is also included.

  11. Slab melting and magma formation beneath the southern Cascade arc

    Science.gov (United States)

    Walowski, Kristina J.; Wallace, Paul J.; Clynne, Michael A.; Rasmussen, D.J.; Weis, D.

    2016-01-01

    The processes that drive magma formation beneath the Cascade arc and other warm-slab subduction zones have been debated because young oceanic crust is predicted to largely dehydrate beneath the forearc during subduction. In addition, geochemical variability along strike in the Cascades has led to contrasting interpretations about the role of volatiles in magma generation. Here, we focus on the Lassen segment of the Cascade arc, where previous work has demonstrated across-arc geochemical variations related to subduction enrichment, and H-isotope data suggest that H2O in basaltic magmas is derived from the final breakdown of chlorite in the mantle portion of the slab. We use naturally glassy, olivine-hosted melt inclusions (MI) from the tephra deposits of eight primitive (MgO>7 wt%) basaltic cinder cones to quantify the pre-eruptive volatile contents of mantle-derived melts in this region. The melt inclusions have B concentrations and isotope ratios that are similar to mid-ocean ridge basalt (MORB), suggesting extensive dehydration of the downgoing plate prior to reaching sub-arc depths and little input of slab-derived B into the mantle wedge. However, correlations of volatile and trace element ratios (H2O/Ce, Cl/Nb, Sr/Nd) in the melt inclusions demonstrate that geochemical variability is the result of variable addition of a hydrous subduction component to the mantle wedge. Furthermore, correlations between subduction component tracers and radiogenic isotope ratios show that the subduction component has less radiogenic Sr and Pb than the Lassen sub-arc mantle, which can be explained by melting of subducted Gorda MORB beneath the arc. Agreement between pMELTS melting models and melt inclusion volatile, major, and trace element data suggests that hydrous slab melt addition to the mantle wedge can produce the range in primitive compositions erupted in the Lassen region. Our results provide further evidence that chlorite-derived fluids from the mantle portion of the

  12. Field demonstration of new bridge approach slab designs and performance : [research project capsule].

    Science.gov (United States)

    2008-10-01

    A normal bridge approach slab in Louisiana is a reinforced concrete slab. It connects : the bridge deck to the adjacent paved roadway. Its intended functions are: : 1. To span the void that may develop below the slab due to soil erosion or : embankme...

  13. High-power diode-pumped Tm:YLF slab laser

    CSIR Research Space (South Africa)

    Schellhorn, M

    2009-06-01

    Full Text Available The aim is to develop a high-power Tm:YLF slab laser which can be utilized to pump a Ho slab laser. A 68 W Tm:YLF slab laser was recently presented in [1] pumped from one end by a single 6-bar stack delivering ~300 W of pump power. In this work, we...

  14. Pressure distribution in centrifugal dental casting.

    Science.gov (United States)

    Nielsen, J P

    1978-02-01

    Equations are developed for liquid metal pressure in centrifugal dental casting, given the instantaneous rotational velocity, density, and certain dimensions of the casting machine and casting pattern. A "reference parabola" is introduced making the fluid pressure concept more understandable. A specially designed specimen demonstrates experimentally the reference parabola at freezing.

  15. 14 CFR 23.621 - Casting factors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Casting factors. 23.621 Section 23.621... Casting factors. (a) General. The factors, tests, and inspections specified in paragraphs (b) through (d... do not support structural loads. (b) Bearing stresses and surfaces. The casting factors specified in...

  16. A boxing procedure for corrected cast impressions.

    Science.gov (United States)

    Ansari, I H

    1994-01-01

    This new method for boxing a corrected cast impression for a distal extension removable partial denture improves the procedure. The framework with its impression is seated on the remainder of the cast after anatomic ridges have been removed and luted with sticky wax, and the assembly is inserted into a previously formed thermoplastic box and poured to make a new corrected cast.

  17. When Your Child Needs a Cast

    Science.gov (United States)

    ... fractures, but can be used when limbs are healing after a surgery. There are many types of casts. The most common casts are: Short arm casts: placed from the knuckles of the hand to just below the elbow. These types of ...

  18. Assimilating lithosphere and slab history in 4-D Earth models

    Science.gov (United States)

    Bower, Dan J.; Gurnis, Michael; Flament, Nicolas

    2015-01-01

    We develop methods to incorporate paleogeographical constraints into numerical models of mantle convection. Through the solution of the convection equations, the models honor geophysical and geological data near the surface while predicting mantle flow and structure at depth and associated surface deformation. The methods consist of four constraints determined a priori from a plate history model: (1) plate velocities, (2) thermal structure of the lithosphere, (3) thermal structure of slabs in the upper mantle, and (4) velocity of slabs in the upper mantle. These constraints are implemented as temporally- and spatially-dependent conditions that are blended with the solution of the convection equations at each time step. We construct Earth-like regional models with oceanic and continental lithosphere, trench migration, oblique subduction, and asymmetric subduction to test the robustness of the methods by computing the temperature, velocity, and buoyancy flux of the lithosphere and slab. Full sphere convection models demonstrate how the methods can determine the flow associated with specific tectonic environments (e.g., back-arc basins, intraoceanic subduction zones) to address geological questions and compare with independent data, both at present-day and in the geological past (e.g., seismology, residual topography, stratigraphy). Using global models with paleogeographical constraints we demonstrate (1) subduction initiation at the Izu-Bonin-Mariana convergent margin and flat slab subduction beneath North America, (2) enhanced correlation of model slabs and fast anomalies in seismic tomography beneath North and South America, and (3) comparable amplitude of dynamic and residual topography in addition to improved spatial correlation of dynamic and residual topography lows.

  19. Seismicity Structure of the Downgoing Nazca Slab in Northern Chile

    Science.gov (United States)

    Sippl, C.; Schurr, B.

    2017-12-01

    We applied an automatized earthquake detection and location algorithm to 8 years of continuous seismic data from the IPOC network in Northern Chile, located in the forearc between about 18.5°S and 24°S. The resulting seismicity catalog contains more than 113k double-difference relocated earthquake hypocenters and features a completeness magnitude around 2.8. Despite the occurrence of two megathrust earthquakes with vigorous aftershock seismicity in the studied time period (the 2007 Tocopilla and the 2014 Iquique earthquakes), >60% of the retrieved seismicity is located in a highly active band of intermediate-depth earthquakes (80-120 km deep) within the downgoing Nazca slab.We obtain a triple seismic zone in the updip part of the slab, with the three parallel dipping planes corresponding to the plate interface, the oceanic Moho (ca. 8 km below the interface) and a third band in the mantle lithosphere 26-28 km beneath the slab top. The plate interface seismicity terminates abruptly at a depth of 55 km. At about 80-90 km depth, the remaining two planes of seismicity then merge into the single, 20 km thick cluster of vigorous seismicity mentioned above, which terminates at 120 km depth. This cluster is located directly beneath the volcanic arc and shows a pronounced kink in the slab dipping angle. Intra-slab seismicity is most likely related to metamorphic dehydration reactions, hence our high-resolution earthquake distribution can be considered a map of metamorphic reactions (although a possibly incomplete one, since not all reactions necessarily invoke seismicity). By correlating this distribution with isotherms from thermal models as well as geophysical imaging results from previous studies, we attempt to get a glimpse at the processes that produce the different patches of intraslab seismicity at intermediate depths.

  20. Effects of Electromagnetic Vibration Frequencies on Microstructure and Tensile Properties of Al-15 Wt Pct Sn Alloy in Semi-continuous Casting Process

    Science.gov (United States)

    Zhong, Yunbo; Wang, Huai; Wang, Yingbin; Wang, Jiang; Shen, Zhe; Zheng, Tianxiang; Zhu, Dongsheng; Ren, Weili; Lei, Zuosheng; Ren, Zhongming; Huang, Jingwen

    2017-07-01

    The electromagnetic vibration (EMV) generated by the action of the AC current and the magnetic field was applied in the crystallizer during the semi-continuous casting of the Al-15 wt pct Sn alloy. The influences of the electromagnetic vibration frequency (EMVF) on the metallographic structure, inverse segregation, and tensile properties were studied. The results indicated that the equiaxed grain ratios of the slabs were increased by decreasing the EMVFs from 500 to 5 Hz. The inverse segregation around the sides of the slab was improved at a low EMVF. The results of the 3D numerical simulation showed that the forced flows led to the refinement of grains and the improvement of the inverse segregation. The slabs with equiaxed grains which were produced with the low EMVFs showed the poor tensile properties comparing to the slabs with columnar grains obtained with the EMVFs of 50, 200, and 500 Hz and without the EMV. This phenomenon was mainly due to the distribution of the brittle Sn-rich phases: the reticular Sn-rich phases appeared around the boundary of the equiaxed grains, while the worm-like Sn-rich phases appeared between the column dendrites intermittently in the slabs with columnar grains.

  1. Shear wave velocities in the Pampean flat-slab region from Rayleigh wave tomography: Implications for slab and upper mantle hydration

    Science.gov (United States)

    Porter, Ryan; Gilbert, Hersh; Zandt, George; Beck, Susan; Warren, Linda; Calkins, Josh; Alvarado, Patricia; Anderson, Megan

    2012-11-01

    The Pampean flat-slab region, located in central Argentina and Chile between 29° and 34°S, is considered a modern analog for Laramide flat-slab subduction within western North America. Regionally, flat-slab subduction is characterized by the Nazca slab descending to ˜100 km depth, flattening out for ˜300 km laterally before resuming a more "normal" angle of subduction. Flat-slab subduction correlates spatially with the track of the Juan Fernandez Ridge, and is associated with the inboard migration of deformation and the cessation of volcanism within the region. To better understand flat-slab subduction we combine ambient-noise tomography and earthquake-generated surface wave measurements to calculate a regional 3D shear velocity model for the region. Shear wave velocity variations largely relate to changes in lithology within the crust, with basins and bedrock exposures clearly defined as low- and high-velocity regions, respectively. We argue that subduction-related hydration plays a significant role in controlling shear wave velocities within the upper mantle. In the southern part of the study area, where normal-angle subduction is occurring, the slab is visible as a high-velocity body with a low-velocity mantle wedge above it, extending eastward from the active arc. Where flat-slab subduction is occurring, slab velocities increase to the east while velocities in the overlying lithosphere decrease, consistent with the slab dewatering and gradually hydrating the overlying mantle. The hydration of the slab may be contributing to the excess buoyancy of the subducting oceanic lithosphere, helping to drive flat-slab subduction.

  2. Determining casting defects in near-net shape casting aluminum parts by computed tomography

    Science.gov (United States)

    Li, Jiehua; Oberdorfer, Bernd; Habe, Daniel; Schumacher, Peter

    2018-03-01

    Three types of near-net shape casting aluminum parts were investigated by computed tomography to determine casting defects and evaluate quality. The first, second, and third parts were produced by low-pressure die casting (Al-12Si-0.8Cu-0.5Fe-0.9Mg-0.7Ni-0.2Zn alloy), die casting (A356, Al-7Si-0.3Mg), and semi-solid casting (A356, Al-7Si-0.3Mg), respectively. Unlike die casting (second part), low-pressure die casting (first part) significantly reduced the formation of casting defects (i.e., porosity) due to its smooth filling and solidification under pressure. No significant casting defect was observed in the third part, and this absence of defects indicates that semi-solid casting could produce high-quality near-net shape casting aluminum parts. Moreover, casting defects were mostly distributed along the eutectic grain boundaries. This finding reveals that refinement of eutectic grains is necessary to optimize the distribution of casting defects and reduce their size. This investigation demonstrated that computed tomography is an efficient method to determine casting defects in near-net shape casting aluminum parts.

  3. Wavefront aberration measurement in a cryogenically cooled Yb:YAG slab using a wavefront sensor

    Science.gov (United States)

    Sikocinski, P.; Novak, O.; Smrz, M.; Pilar, J.; Jelinkova, H.; Endo, A.; Lucianetti, A.; Mocek, T.

    2017-05-01

    We investigated wavefront aberrations in a cryogenically cooled Yb:YAG slab with a wavefront sensor using a probe beam technique under non-lasing condition. To analyze the pump-induced phase aberrations created in the crystal, the measured wavefronts were fitted with orthonormal Zernike polynomials. The Yb:YAG crystal of 2 mm thickness, 10 mm diameter, and 3 at.% doping concentration was mounted in a copper holder in a closed-loop pulse tube cryostat with cooling capacity of 12 W at 100 K. The gain medium was single-end pumped by a fiber-coupled laser diode at pumping intensity of 6.5 kW/cm2 with a maximum repetition rate of 100 Hz, pulse duration of 1 ms, and pump spot diameter of 2.5 mm. The time resolved measurement revealed that defocus, which was the main wavefront aberration, represents not only a thermal lensing effect but also an electronic lensing effect. The thermally induced defocus is more dominant at high repetition rate than the electronically induced defocus. We also measured wavefront aberrations of amplified beams in a cryogenically cooled Yb:YAG slab. A room temperature operated thin-disk regenerative amplifier was used as a seed laser. The seed beam was amplified in the cryogenically cooled crystal at 160 K in a double pass configuration. The wavefront measurement was conducted at semi-saturated conditions, at three different repetition rates: 10 Hz, 20 Hz and 40 Hz, and at five different pump intensities in the range between 6.5 kW/cm2 and 14.8 kW/cm2. Under lasing condition, only defocus aberration were induced. Due to opposite signs of the defocus aberration of the seed beam and pumped induced in the Yb:YAG crystal, wavefront of the amplified beam had smaller PtV (Peak to Valley) and RMS values than the seed beam.

  4. Single tunable laser interrogation of slab-coupled optical sensors through resonance tuning.

    Science.gov (United States)

    Chadderdon, Spencer; Woodard, Leeland; Perry, Daniel; Selfridge, Richard H; Schultz, Stephen M

    2013-04-20

    This paper describes a method for tuning the resonant wavelengths of slab-coupled optical fiber sensors (SCOSs). This method allows multiple sensors to be interrogated simultaneously with a single tunable laser. The resonances are tuned by rotating a biaxial slab waveguide relative to an optical D-fiber. As the slab waveguide rotates, its effective index of refraction changes causing the coupling wavelengths of the slab waveguide and D-fiber to shift. A SCOS fabricated with potassium titanyl phosphate crystal as the slab waveguide is shown to have resonance tuning ranges of 6.67 and 22.24 nm, respectively, for TM and TE polarized modes.

  5. Prediction of Part Distortion in Die Casting

    Energy Technology Data Exchange (ETDEWEB)

    R. Allen Miller

    2005-03-30

    The die casting process is one of the net shape manufacturing techniques and is widely used to produce high production castings with tight tolerances for many industries. An understanding of the stress distribution and the deformation pattern of parts produced by die casting will result in less deviation from the part design specification, a better die design and eventually more productivity and cost savings. This report presents methods that can be used to simulate the die casting process in order to predict the deformation and stresses in the produced part and assesses the degree to which distortion modeling is practical for die casting at the current time. A coupled thermal-mechanical finite elements model was used to simulate the die casting process. The simulation models the effect of thermal and mechanical interaction between the casting and the die. It also includes the temperature dependant material properties of the casting. Based on a designed experiment, a sensitivity analysis was conducted on the model to investigate the effect of key factors. These factors include the casting material model, material properties and thermal interaction between casting and dies. To verify the casting distortion predictions, it was compared against the measured dimensions of produced parts. The comparison included dimensions along and across the parting plane and the flatness of one surface.

  6. Emulsion based cast booster - a priming system

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.N.; Mishra, A.K. [National Institute of Rock Mechanics, KGF (India)

    2005-07-01

    This paper explores the potential of emulsion based cast booster to be used as primer to initiate bulk delivered emulsion explosives used in mines. An attempt has been made for comparative study between conventional cast booster and emulsion based cast booster in terms of the initiation process developed and their capability to develop and maintain the stable detonation process in the column explosives. The study has been conducted using a continuous velocity of detonation (VOD) measuring instrument. During this study three blasts have been monitored. In each blast two holes have been selected for study, the first hole being initiated with conventional cast booster while the other one with emulsion based cast booster. The findings of the study advocates that emulsion based cast booster is capable of efficient priming of bulk delivered column explosive with stable detonation process in the column. Further, the booster had advantages over the conventional PETN/TNT based cast booster. 5 refs., 2 figs., 1 tab., 1 photo.

  7. Numerical predictions of misruns in development of near-net shape casting process

    OpenAIRE

    Jana, Santhanu Shakti Pada

    2015-01-01

    In this thesis, numerical investigations for development of a near net shape casting process for TiAl alloy are presented. The casting object used in this work is low pressure turbine (LPT) blade, which is characterized by extremely thin section areas that are prone to misruns. The work specifically focuses on predictions of misruns and developing strategies to avoid them. The numerical simulation methodology used in this work, is based on modelling all the three-phases i.e., gas, liquid and ...

  8. Development of an Analog System to Simulate Interface Formation During Fusion™ Casting

    Science.gov (United States)

    Di Ciano, Massimo; Weckman, D. C.; Wells, M. A.

    2016-04-01

    To improve casting and product yields of Fusion™ cast AA3003-core/AA4045-clad laminate ingots, a fundamental understanding of the wetting and interface formation process between the oxidized AA3003 cast surface and the AA4045 melt is required. In this study, a laboratory scale analog/immersion test was developed which mimics the wetting and interface formation process that occurs during Fusion™ casting. The effects of reheating and remelting of the AA3003 cast surface, the degree of surface oxidation present during initial contact of the two alloys, and the atmospheric conditions (air or argon) on interface formation when dipped into an AA4045 melt were examined. Results indicated that in an argon atmosphere, wetting and dissolution of the solid, oxidized AA3003 samples by liquid AA4045 occurred at temperatures both above and below the measured onset of AA3003 remelting. AA3003/AA4045 interfaces were similar to those produced during Fusion™ casting, with a thin layer of AA4045 forming an oxide-free, metallurgical interface to the AA3003 after immersion. The AA3003 surface oxides were not an impediment to wetting and bond formation. Mg surface segregation was observed on the oxidized AA3003 surfaces and may play a role to help penetrate the oxide layer. For tests conducted in air, wetting of the sample by AA4045 liquid was generally poor regardless of temperature.

  9. Preparation and optical characterization of DNA-riboflavin thin films

    Science.gov (United States)

    Paulson, Bjorn; Shin, Inchul; Kong, Byungjoo; Sauer, Gregor; Dugasani, Sreekantha Reddy; Khazaeinezhad, Reza; Jung, Woohyun; Joo, Boram; Oh, Kyunghwan

    2016-09-01

    Thin films of DNA biopolymer thin film are fabricated by a drop casting process on glass and silicon substrates, as well as freestanding. The refractive index is measured by elliposmetry and in bulk DNA film the refractive index is shown to be increased in the 600 to 900 nm DNA transparency window by doping with riboflavin. Further analysis with FT-IR, Raman, and XRD are used to determine whether binding between riboflavin and DNA occurs.

  10. Investigation of Effect of Slab Opening Location to the Shear Stress

    Directory of Open Access Journals (Sweden)

    Burak Yön

    2010-01-01

    Full Text Available In this study, it is investigated the effect of slab opening location in reinforced concrete building to the structural behavior. For investigation of slab irregularity, three multi storey irregular structures that have different slab opening locations in structure plans and one regular structure are designed. Linear dynamic analyses are performed for the structure models using Time History Analysis method. 13 March 1992 Erzincan Earthquake acceleration records are used for these analyses. It is assumed that slabs of selected structures are modeled as elastic diaphragm. SAP2000 Structural Analysis Program is used in the analyses. Values of slab that near space shear stress obtained from dynamic analyses of selected structures are comparatively evaluated. According to analyses results, it is determined that location of slab opening of structures reasonably both affects the behavior of structures and occurs great slab shear stress.

  11. Analysis of the Behaviour of Composite Steel and Steel Fiber Reinforced Concrete Slabs

    Directory of Open Access Journals (Sweden)

    Mindaugas Petkevičius

    2011-04-01

    Full Text Available There was a pending influence of steel fiber on the strength and stiffness of composite steel–concrete slabs under statical short–time load. Steel profiled sheeting and steel fiber reinforced concrete were used for specimens. Four composite slabs were made. Experimental investigations into the behaviour and influence of steel fiber reinforced concrete in composite slabs were conducted. Transverse, longitudinal, shear deformation and deflection of the slab were measured. The results indicated that the use of steel fiber in composite slabs was effective: strength was 20–24 % higher and the meanings of deflections under the action of the bending moment were 0,6MR (where MR is the bending moment at failure of the slabs and were 16–18 % lower for slabs with usual concrete. Article in Lithuanian

  12. Pressure rig for repetitive casting

    Science.gov (United States)

    Vasquez, Peter; Hutto, William R.; Philips, Albert R.

    1989-09-01

    The invention is a pressure rig for repetitive casting of metal. The pressure rig performs like a piston for feeding molten metal into a mold. Pressure is applied to an expandable rubber diaphragm which expands like a balloon to force the metal into the mold. A ceramic cavity which holds molten metal is lined with blanket-type insulating material, necessitating only a relining for subsequent use and eliminating the lengthy cavity preparation inherent in previous rigs. In addition, the expandable rubber diaphragm is protected by the insulating material thereby decreasing its vulnerability to heat damage. As a result of the improved design the life expectancy of the pressure rig contemplated by the present invention is more than doubled. Moreover, the improved heat protection has allowed the casting of brass and other alloys with higher melting temperatures than possible in the conventional pressure rigs.

  13. Search for chameleons with CAST

    CERN Document Server

    Anastassopoulos, V; Aune, S; Barth, K; Belov, A; Bräuninger, H; Cantatore, G; Carmona, J M; Cetin, S A; Christensen, F; Collar, J I; Dafni, T; Davenport, M; Desch, K; Dermenev, A; Eleftheriadis, C; Fanourakis, G; Ferrer-Ribas, E; Friedrich, P; Galán, J; García, J A; Gardikiotis, A; Garza, J G; Gazis, E N; Geralis, T; Giomataris, I; Hailey, C; Haug, F; Hasinoff, M D; Hofmann, D H H; Iguaz, F J; Irastorza, I G; Jacoby, J; Jakobsen, A; Jakovčić, K; Kaminski, J; Karuza, M; Kavuk, M; Krčmar, M; Krieger, C; Krüger, A; Lakić, B; Laurent, J M; Liolios, A; Ljubičić, A; Luzón, G; Neff, S; Ortega, I; Papaevangelou, T; Pivovarov, M J; Raffelt, G; Riege, H; Rosu, M; Ruz, J; Savvidis, I; Solanki, S K; Vafeiadis, T; Villar, J A; Vogel, J K; Yildiz, S C; Zioutas, K; Brax, P; Lavrentyev, I; Upadhye, A

    2015-01-01

    In this work we present a search for (solar) chameleons with the CERN Axion Solar Telescope (CAST). This novel experimental technique, in the field of dark energy research, exploits both the chameleon coupling to matter ($\\beta_{\\rm m}$) and to photons ($\\beta_{\\gamma}$) via the Primakoff effect. By reducing the X-ray detection energy threshold used for axions from 1$\\,$keV to 400$\\,$eV CAST became sensitive to the converted solar chameleon spectrum which peaks around 600$\\,$eV. Even though we have not observed any excess above background, we can provide a 95% C.L. limit for the coupling strength of chameleons to photons of $\\beta_{\\gamma}\\!\\lesssim\\!10^{11}$ for $1<\\beta_{\\rm m}<10^6$.

  14. Search for chameleons with CAST

    Directory of Open Access Journals (Sweden)

    V. Anastassopoulos

    2015-10-01

    Full Text Available In this work we present a search for (solar chameleons with the CERN Axion Solar Telescope (CAST. This novel experimental technique, in the field of dark energy research, exploits both the chameleon coupling to matter (βm and to photons (βγ via the Primakoff effect. By reducing the X-ray detection energy threshold used for axions from 1 keV to 400 eV CAST became sensitive to the converted solar chameleon spectrum which peaks around 600 eV. Even though we have not observed any excess above background, we can provide a 95% C.L. limit for the coupling strength of chameleons to photons of βγ≲1011 for 1<βm<106.

  15. Reconstructing subducted oceanic lithosphere by "reverse-engineering" slab geometries: The northern Philippine Sea Plate

    Science.gov (United States)

    Pownall, Jonathan M.; Lister, Gordon S.; Spakman, Wim

    2017-09-01

    Subducting slabs commonly acquire complex geometries from the migration of subduction trenches, slab-mantle interaction, slab tearing, and collision of slabs at depth. Although it is possible to construct three-dimensional models of subducted slabs using earthquake hypocenter locations and tomographic models, it is often not possible to rigorously test their accuracy. Here we present a methodology for performing such a test, by "reverse-engineering" the presubduction configuration of a slab of oceanic lithosphere from interpretations of its present-day morphology. We illustrate our approach for the Ryukyu and Shikoku slabs, northwest Philippine Sea, having simulated them as viscoelastic sheets that we unfolded and "floated" to the surface. The net strain distribution of the floated mesh indicated which parts of the original slab model were geometrically viable (minimal net strain) and which parts of the mesh required additional tears and/or zones of localized ductile extension to have enabled the slab to deform during subduction. In the instance of the Ryukyu and Shikoku slabs, the Palau-Kyushu and Gagua ridges are shown to have both acted as planes of weakness that broke into major vertical slab tears. These subducted ridges are connected by a trench-parallel tear that represented the former contact between the Huatung and West Philippine Basins. The fossil spreading center of the Shikoku Basin formed a separate slab window upon subduction along the Nankai Trough. The methodology presented herein is a powerful tool to evaluate complex slab morphologies, infer the locations of slab tears, and therefore reconstruct intricate configurations of subducted oceanic lithosphere.

  16. Flexural Behavior of Continuous Bubbled Reinforced Reactive Powder Concrete Flat Slab

    Directory of Open Access Journals (Sweden)

    Mohammad Redha K. Mahmood

    2017-05-01

    Full Text Available This paper presents an experimental investigation on flexural behavior of continuous bubbled reinforced Reactive Powder Concrete (RPC flat slabs. Bubbled slab is one of the various types of voided slabs. It consist of bubbles placed inside a concrete slab which will reduce the self-weight of the structure by about 35% (Tina Lai 2009. On the other hand, using RPC make it possible for structural member to have smaller dimensions due to the great strength of this type of concrete. In this study these two method are used to increase the building spaces dimensions by reducing self-weigh of the structure by using bubbled slabs and to decrease the structural members' dimensions by using RPC have been investigated together. To study the flexural behavior of continuous bubbled flat slabs such as the ultimate load carrying capacity, central deflection and slabs crack pattern at the ultimate load, seven types of slabs were tested. The parameters of the study were type of concrete (RPC and Normal Concrete (NC, bubbles diameter to slab thickness ratio (D/t of (0.6 and 0.7, type of loading (distributed and line load and solid slab. The test results show that the crack pattern and ultimate load capacity as well as maximum deflection depends on all of the mentioned parameters, were by increasing (D/t ratio the ultimate load capacity increases about (7.36%, 5.46% and 16.52% for RPC slabs under distributed load, line load and NC slabs, respectively. The solid slab increases the ultimate load about (4.05% compare to bubbled slab. Also, the line load decreases the ultimate load compare to distributed load by (3.45-5.16% for different (D/t ratio, and using the NC also decreases the ultimate load compare to RPC by (48-52.13% for different (D/t ratio

  17. Thin Places

    OpenAIRE

    Lockwood, Sandra Elizabeth

    2013-01-01

    This inquiry into the three great quests of the twentieth century–the South Pole, Mount Everest, and the Moon–examines our motivations to venture into these sublime, yet life-taking places. The Thin Place was once the destination of the religious pilgrim seeking transcendence in an extreme environment. In our age, the Thin Place quest has morphed into a challenge to evolve beyond the confines of our own physiology; through human ingenuity and invention, we reach places not meant to accommod...

  18. Interface and material engineering for zigzag slab lasers.

    Science.gov (United States)

    Liu, Fei; Dong, Siyu; Zhang, Jinlong; Jiao, Hongfei; Ma, Bin; Wang, Zhanshan; Cheng, Xinbin

    2017-12-01

    Laser damage of zigzag slab lasers occurs at interface between laser crystal and SiO 2 film. Although an additional HfO 2 layer could be used to manipulate electric-field on the crystal-film interface, their high absorption and polycrystalline structure were unacceptable. SiO 2 was then doped in HfO 2 to suppress its crystallization and to achieve low absorption by annealing. Hf x Si 1-x O 2 nanocomposite layers were then inserted between laser crystal and SiO 2 film to minimize electric-field at crystal-film interface. Laser damage resistance of this new architecture is two times higher than that of traditional zigzag slab lasers.

  19. Oscillating Casimir force between two slabs in a Fermi sea

    DEFF Research Database (Denmark)

    Li-Wei, Chen; Guo-Zhen, Su; Jin-Can, Chen

    2012-01-01

    The Casimir effect for two parallel slabs immersed in an ideal Fermi sea is investigated at both zero and nonzero temperatures. It is found that the Casimir effect in a Fermi gas is distinctly different from that in an electromagnetic field or a massive Bose gas. In contrast to the familiar result...... that the Casimir force decreases monotonically with the increase of the separation L between two slabs in an electromagnetic field and a massive Bose gas, the Casimir force in a Fermi gas oscillates as a function of L. The Casimir force can be either attractive or repulsive, depending sensitively on the magnitude...... of L. In addition, it is found that the amplitude of the Casimir force in a Fermi gas decreases with the increase of the temperature, which also is contrary to the case in a Bose gas, since the bosonic Casimir force increases linearly with the increase of the temperature in the region T

  20. Minimization of heat slab nodes with higher order boundary conditions

    International Nuclear Information System (INIS)

    Solbrig, C.W.

    1992-01-01

    The accuracy of a numerical solution can be limited by the numerical approximation to the boundary conditions rather than the accuracy of the equations which describe the interior. The study presented in this paper compares the results from two different numerical formulations of the convective boundary condition on the face of a heat transfer slab. The standard representation of the boundary condition in a test problem yielded an unacceptable error even when the heat transfer slab was partitioned into over 300 nodes. A higher order boundary condition representation was obtained by using a second order approximation for the first derivative at the boundary and combining it with the general equation used for inner nodes. This latter formulation produced reasonable results when as few as ten nodes were used

  1. Radon Sub-slab Suctioning System Integrated in Insulating Layer

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn

    2013-01-01

    of prefabricated lightweight elements were introduced and demonstrated. The principle was demonstrated on a concrete ground slab floor with a concrete slab on top of a thermal insulation layer above a capillary-breaking layer mounted on stable ground. The thermal insulation and the capillary-breaking layer......A new principle for radon protection, using a system containing a horizontal grid of air ducts pressurised within the rigid insulation material, was presented. The principle was based on the principles for pressure reduction of the zone underneath the ground floor construction. A new element...... consisted of a rigid insulation material. The new solution integrates the capillary-breaking layer and a pressure reduction zone,denoted the radon–suctioning layer, in one element. The new solution introduces the radonsuctioning layer as a horizontal grid of air ducts with low pressure to catch air...

  2. Watertightness in anti-flotation slabs: MIS-RJ case

    Directory of Open Access Journals (Sweden)

    C. Britez

    Full Text Available It is common in coastal cities as Rio de Janeiro, that buildings located close to the shoreline have their basements below water table level. In most cases, the engineering solution for these buildings is to design a massive anti-flotation slab to satisfy, principally, the issues related to structural dimensioning and calculation hypothesis. On the other hand, the execution of this solution imply in significant construction problems related to reinforced concrete watertightness and durability. This paper presents a case study about challenges and solutions devised to execute an anti-flotation, 1m thick, 1200m³ reinforced concrete slab for the new Museu de Imagem e Som (MIS - Sound and Image Museum, located at 50m from the seashore, at Copacabana in Rio de Janeiro, RJ. The results show that concrete proportions, concreting plan and pouring method adopted were decisive in obtaining a watertight structure, avoiding thus the employment of traditional waterproofing alternatives.

  3. Anticrack nucleation as triggering mechanism for snow slab avalanches.

    Science.gov (United States)

    Heierli, J; Gumbsch, P; Zaiser, M

    2008-07-11

    Snow slab avalanches are believed to begin by the gravity-driven shear failure of weak layers in stratified snow. The critical crack length for shear crack propagation along such layers should increase without bound as the slope decreases. However, recent experiments show that the critical length of artificially introduced cracks remains constant or, if anything, slightly decreases with decreasing slope. This surprising observation can be understood in terms of volumetric collapse of the weak layer during failure, resulting in the formation and propagation of mixed-mode anticracks, which are driven simultaneously by slope-parallel and slope-normal components of gravity. Such fractures may propagate even if crack-face friction impedes downhill sliding of the snowpack, indicating a scenario in which two separate conditions have to be met for slab avalanche release.

  4. Bolometric detection of ferromagnetic resonance in YIG slab

    Science.gov (United States)

    Tu, Sa; Białek, Marcin; Zhang, Youguang; Zhao, Weisheng; Yu, Haiming; Ansermet, Jean-Philippe

    2017-10-01

    The resistance of the Pt bar deposited on the YIG slab was monitored while the magnetic field was ramped through the ferromagnetic resonance with the YIG slab facing a coplanar waveguide resonator excited at 4.3 GHz excitation. The resistance change provides detection of the ferromagnetic resonance with a high signal-to-noise ratio. It is ascribed to a change in the temperature of the Pt bars. The thermal origin of the signal is confirmed by the observation that the signal vanishes when field modulation is applied at frequencies above 6 Hz. The spin pumping effect was vanishingly small, and the anisotropic magnetoresistance of the Pt bar, though quite easily observed, would imply a rectification voltage that is much smaller than the bolometric effect.

  5. Time-of-Flight Effects in Microwave Transmission Through a Thin Metal Slab

    DEFF Research Database (Denmark)

    Henningsen, J. O.; Falk, David S.

    1971-01-01

    A 45-GHz size-effect experiment on Ag revealed significant structure in the combined transmission and leakage signal below the first-belly-electron size effects. The oscillations, which behave differently for different field orientations, are shown to be due to the time-of-flight phase delay of e...

  6. Slab detachment under the Eastern Alps seen by seismic anisotropy.

    Science.gov (United States)

    Qorbani, Ehsan; Bianchi, Irene; Bokelmann, Götz

    2015-01-01

    We analyze seismic anisotropy for the Eastern Alpine region by inspecting shear-wave splitting from SKS and SKKS phases. The Eastern Alpine region is characterized by a breakdown of the clear mountain-chain-parallel fast orientation pattern that has been previously documented for the Western Alps and for the western part of the Eastern Alps. The main interest of this paper is a more detailed analysis of the anisotropic character of the Eastern Alps, and the transition to the Carpathian-Pannonian region. SK(K)S splitting measurements reveal a rather remarkable lateral change in the anisotropy pattern from the west to the east of the Eastern Alps with a transition area at about 12°E. We also model the backazimuthal variation of the measurements by a vertical change of anisotropy. We find that the eastern part of the study area is characterized by the presence of two layers of anisotropy, where the deeper layer has characteristics similar to those of the Central Alps, in particular SW-NE fast orientations of anisotropic axes. We attribute the deeper layer to a detached slab from the European plate. Comparison with tomographic studies of the area indicates that the detached slab might possibly connect with the lithosphere that is still in place to the west of our study area, and may also connect with the slab graveyard to the East, at the depth of the upper mantle transition zone. On the other hand, the upper layer has NW-SE fast orientations coinciding with a low-velocity layer which is found above a more-or-less eastward dipping high-velocity body. The anisotropy of the upper layer shows large-scale NW-SE fast orientation, which is consistent with the presence of asthenospheric flow above the detached slab foundering into the deeper mantle.

  7. Concrete mixtures with high-workability for ballastless slab tracks

    OpenAIRE

    Olga Smirnova

    2017-01-01

    The concrete track-supporting layer and the monolithic concrete slab of ballastless track systems are made in-situ. For this reason the concrete mixtures of high workability should be used. Influence of the sand kind, the quartz microfiller fineness and quantity as well as quantity of superplasticizer on workability of fresh concrete and durability of hardened concrete is shown. The compositions of the high-workability concrete mixtures with lower consumption of superplasticizer are developed...

  8. Slab track systems for high-speed railways.

    OpenAIRE

    Michas, Georgios

    2012-01-01

    In the last 40 years an increase in train speed and axle load around the world and other challenges in the conventional ballasted track system gave birth to ballastless railway track system. This study examines in depth the various slab track systems that are being used today. Their design characteristics as well as the various requirements for efficient use are thoroughly explained. At least 34 different ballastless systems have been recorded in many railway networks throughout the world. Th...

  9. Evaluating the potential shielding properties of periodic metamaterial slabs

    OpenAIRE

    SEETHARAMDOO, D; BERBINEAU, M; TAROT, A; MAHDJOUBI, K

    2009-01-01

    Metamaterials can prove to be good candidates for shields in EMC applications where weight reduction is a challenge. Indeed metamaterial slabs can provide the same reflective properties as conventional metallic screens but with a lower density and reduced weight. Another advantage is that they can be tailored to exhibit required frequency-selective properties. However, their performance in terms of shielding performance has yet to be evaluated. In this paper, a method to evaluate the shieldin...

  10. Characteristics of Recycled Concrete Aggregates from Precast Slab Block Buildings

    Science.gov (United States)

    Venkrbec, Václav; Nováková, Iveta; Henková, Svatava

    2017-10-01

    Precast slab block buildings (PSBB) typically and frequently occur in Central and Eastern Europe, as well as elsewhere in the world. Some of these buildings are currently used beyond their service life capacity. The utilization of recycled materials from these buildings with regard to applying the principles of sustainable construction and using recycled materials will probably be significant in the following years. Documentation from the manufacturing processes of prefabricated blocks for precast slab block buildings is not available, and also it is difficult to declare technological discipline during the construction of these buildings. Therefore, properties of recycled concrete aggregates (RCA) produced from construction and demolition waste (C&DW) of precast slab block buildings build between 1950s to 1990s are not sufficiently known. The demolition of these buildings is very rare today, but it can be assumed an increase in demolitions of these buildings in the future. The use of RCA in new concrete requires verification/testing of the geometrical and physical properties of RCA according to the EN 12 620+A1 standard. The aim of the contribution is to present a case study of the demolition of slab block building with emphasis on RCA usage. The paper presents the results of the tests according to European standards for determining selected geometrical and physical properties of the RCA. The paper describes and evaluates tests such as determination of particle size distribution - Sieve Analysis, content of fine particles, determination of density and water absorption. The results of the properties testing of RCA are compared with the properties of natural aggregate. The general boundary conditions of RCA particular tests are presented.

  11. Brueckner G matrix for a planar slab of nuclear matter

    International Nuclear Information System (INIS)

    Baldo, M.; Lombardo, U.; Saperstein, E.E.; Zverev, M.V.

    2001-01-01

    The equation for the Brueckner G matrix is investigated for planar-slab geometry. A method for calculating the G matrix for a planar slab of nuclear matter is developed for a separable form of NN interaction. Actually, the separable version of the Paris NN potential is used. The singlet 1 S 0 and the triplet 3 S 1 - 3 D 1 channel are considered. The present analysis relies on the mixed momentum-coordinate representation, where use is made of the momentum representation in the slab plane and of the coordinate representation in the orthogonal direction. The full two-particle Hilbert space is broken down into the model subspace, where the two-particle propagator is considered exactly, and the complementary subspace, where the local-potential approximation is used, which was proposed previously for calculating the effective pairing potential. Specific calculations are performed for the case where the model subspace is constructed on the basis of negative-energy single-particle states. The G matrix is parametrically dependent on the total two-particle energy E and the total momentum P perpendicular in the slab plane. Since the G matrix is assumed to be further used to calculate the Landau-Migdal amplitude, the total two-particle energy is fixed at the value E = 2μ, where μ is the chemical potential of the system under investigation. The calculations are performed predominantly for P perpendicular = 0. The role of nonzero values of P perpendicular is assessed. The resulting G matrix is found to depend greatly on μ in the surface region

  12. Analytical approximation formulae for hydrogen diffusion in a metal slab

    International Nuclear Information System (INIS)

    Pohl, F.; Bohdansky, J.

    1984-12-01

    This report treats hydrogen diffusion in the first wall of a fusion machine (INTOR, reactor, etc.), taking the thermal load into account. Analytical approximation formulae are given for the concentration and flux density of hydrogen diffusing through a plane metal slab. The re-emission flux, particularly during the dwell time(s) of machine operation, is also described with analytical formulae. The analytical formulae are compared with numerical calculations for steel as first wall material. (orig.)

  13. Oscillation modes and transmission into a Fibonacci slab

    Science.gov (United States)

    Castro-Arce, Lamberto; Molinar-Tabares, Martin; Campos-Garcia, Julio; Figueroa-Navarro, Carlos; Isasi-Siqueiros, Leonardo; Manzanares-Martinez, Betsabe

    In our contribution we developed a study on the behavior of the transmission modes and a Pt / Zn slab of a Fibonacci array of longitudinal and transverse acoustic waves. We have worked with arrangements from n = 1 to10 and has managed to find the energy bands and transmission, filling factor 0.4 observing the appearance of Pseudo-Gaps in the evolution of the study when the arrangement Fibonacci increases. We acknowledge the support of SNI CONACYT.

  14. Effect of cast steel production metallurgy on the emergence of casting defects

    Directory of Open Access Journals (Sweden)

    L. Čamek

    2016-10-01

    Full Text Available The paper documents metallurgical possibilities of high alloy cast steel production in open induction medium frequency furnaces and an electric arc furnace in a gravity die casting foundry. The observation was focused on the emergence of gas defects in steel castings. The content of gases achieved during the metallurgical processes was evaluated for every unit of the production equipment and the casting ladle before casting into disposable sand moulds. The sand mould area was considered to be constant. The aim was to evaluate the current metallurgical possibilities of affecting the content of gases in high alloy cast steel in the current technical conditions of the foundry.

  15. High Performance Slab-on-Grade Foundation Insulation Retrofits

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, Louise F. [NorthernSTAR, St. Paul, MN (United States); Mosiman, Garrett E. [NorthernSTAR, St. Paul, MN (United States)

    2015-09-01

    ?A more accurate assessment of SOG foundation insulation energy savings than traditionally possible is now feasible. This has been enabled by advances in whole building energy simulation with 3-dimensional foundation modelling integration at each time step together with an experimental measurement of the site energy savings of SOG foundation insulation. Ten SOG insulation strategies were evaluated on a test building to identify an optimum retrofit insulation strategy in a zone 6 climate (Minneapolis, MN). The optimum insulation strategy in terms of energy savings and cost effectiveness consisted of two components: (a) R-20 XPS insulation above grade, and, (b) R-20 insulation at grade (comprising an outer layer of R-10 insulation and an interior layer of R-12 poured polyurethane insulation) tapering to R-10 XPS insulation at half the below-grade wall height (the lower half of the stem wall was uninsulated). The optimum insulation strategy was applied to single and multi-family residential buildings in climate zone 4 - 7. The highest site energy savings of 5% was realized for a single family home in Duluth, MN, and the lowest savings of 1.4 % for a 4-unit townhouse in Richmond, VA. SOG foundation insulation retrofit simple paybacks ranged from 18 to 47 years. There are other benefits of SOG foundation insulation resulting from the increase in the slab surface temperatures. These include increased occupant thermal comfort, and a decrease in slab surface condensation particularly around the slab perimeter.

  16. Surface waves in the partially ionized solar plasma slab

    Science.gov (United States)

    Pandey, B. P.

    2013-12-01

    The properties of surface waves in the partially ionized, incompressible magnetized plasma slab are investigated in the present work. The waves are affected by the non-ideal magnetohydrodynamic (MHD) effects which cause the finite drift of the magnetic field in the medium. When the finite drift of the magnetic field is ignored, the characteristics of the wave propagation in the partially ionized plasma fluid are similar to the ideal MHD, except now the propagation properties depend on the fractional ionization of the medium. In the presence of the Hall diffusion, the propagation of the sausage and kink surface waves depends on the level of fractional ionization of the medium. For example, short wavelength surface modes cannot propagate in the medium if the scale over which Hall operates is comparable to the size of the plasma slab. With the increasing ionization, the surface modes of shorter wavelength are permitted in the system. When both the Hall and Pedersen diffusion are present in the medium, the waves undergo damping. In the case of Pedersen dominating Hall, the damping of the long wavelength fluctuations is dependent on the ratio of the plasma densities inside and outside the slab and on the square of the Pedersen diffusivity. For typical solar parameters, waves may damp over few minutes.

  17. From stripe to slab confinement for DNA linearization in nanochannels

    Science.gov (United States)

    Cifra, Peter; Benkova, Zuzana; Namer, Pavol

    We investigate suggested advantageous analysis in the linearization experiments with macromolecules confined in a stripe-like channel using Monte Carlo simulations. The enhanced chain extension in a stripe that is due to significant excluded volume interactions between monomers in two dimensions weakens on transition to experimentally feasible slit-like channel. Based on the chain extension-confinement strength dependence and the structure factor behavior for the chain in stripe we infer the excluded volume regime typical for two-dimensional systems. On transition to the slab geometry, the advantageous chain extension decreases and the Gaussian regime is observed for not very long semiflexible chains. The evidence for pseudo-ideality in confined chains is based on indicators such as the extension curves, variation of the extension with the persistence length or the structure factor. The slab behavior is observed when the stripe (originally of monomer thickness) reaches the thickness larger than cca 10nm in the third dimension. This maximum height of the slab to retain the advantage of the stripe is very low and this have implication for DNA linearization experiments. The presented analysis, however, has a broader relevance for confined polymers. Support from Slovak R&D Agency (SRDA-0451-11) is acknowledged.

  18. Reducing Railway Noise with Porous Sound-Absorbing Concrete Slabs

    Directory of Open Access Journals (Sweden)

    Caiyou Zhao

    2014-01-01

    Full Text Available The effect of porous sound-absorbing concrete slabs on railway noise reduction is examined in this paper. First, the acoustical absorption coefficients of porous concrete materials with various aggregate types, gradations, fibre contents, and compaction indexes are measured in the laboratory. The laboratory results show that porous concrete that uses a composite of expanded perlite and slag as aggregate can not only obtain good acoustical absorption properties but also satisfy mechanical requirements. Also, the gradation of the combined aggregate has a significant effect on the acoustic absorption performance of the porous concrete, with an optimal aggregate gradation of 1~3 mm. Furthermore, the fibre content and compaction index affect both the strength and the acoustic absorption property of the porous concrete, with the optimum value of 0.3% and 1.6, respectively. Then, the findings from the laboratory studies are used to make porous sound-absorbing concrete slabs, which are applied in a test section. The measurements indicate that porous sound-absorbing concrete slabs can significantly reduce railway noise at different train speeds and that the amount of the noise reduction changes roughly linearly with speed when the train is traveling at less than 200 km/h. The maximum noise reduction is 4.05 dB at a speed of 200 km/h.

  19. The Green's function method for critical heterogeneous slabs

    International Nuclear Information System (INIS)

    Kornreich, D.E.

    1996-01-01

    Recently, the Green's Function Method (GFM) has been employed to obtain benchmark-quality results for nuclear engineering and radiative transfer calculations. This was possible because of fast and accurate calculations of the Green's function and the associated Fourier and Laplace transform inversions. Calculations have been provided in one-dimensional slab geometries for both homogeneous and heterogeneous media. A heterogeneous medium is analyzed as a series of homogeneous slabs, and Placzek's lemma is used to extend each slab to infinity. This allows use of the infinite medium Green's function (the anisotropic plane source in an infinite homogeneous medium) in the solution. To this point, a drawback of the GFM has been the limitation to media with c 1; however, mathematical solutions exist which result in oscillating Green's functions. Such calculations are briefly discussing. The limitation to media with c < 1 has been relaxed so that the Green's function may also be calculated for media with c ≥ 1. Thus, materials that contain fissionable isotopes may be modeled

  20. Calibrating a large slab vessel: A battle of the bulge

    International Nuclear Information System (INIS)

    Thomas, I.R.

    1993-01-01

    Slab tanks (critically-safe-by-geometry vessels) were proposed for the storage of concentrated, highly-enriched uranium solution in the design of the Fuel Processing Restoration (FPR) Facility at the Idaho Chemical Processing Plant (ICPP). Currently, measurements of bulk mass in ICPP annular vessels have standard deviations on the order of 0.2%, or less. ICPP personnel felt that their inexperience with the aforementioned expansions would prevent them from attaining comparable precision with slab tanks. To help assess the measurement accuracy of slab vessels, a full-scale mockup of those proposed for the FPR Facility was installed for test calibrations. These calibrations were designed to detect vessel expansion under differing conditions. This paper will compare the base-line, water calibrations with those of the higher-density aluminum nitrate, and any observed deflection will be described using vessel calibration techniques. The calibration using water at an elevated temperature was not performed due to the difficulty of maintaining the elevated temperature. This calibration probably will not be conducted because the construction of the FPR Facility has been halted

  1. Thin book

    DEFF Research Database (Denmark)

    En lille bog om teater og organisationer, med bidrag fra 19 teoretikere og praktikere, der deltog i en "Thin Book Summit" i Danmark i 2005. Bogen bidrager med en state-of-the-art antologi om forskellige former for samarbejde imellem teater og organisationer. Bogen fokuserer både på muligheder og...

  2. Thin Film

    African Journals Online (AJOL)

    a

    organic substances. KEY WORDS: Photoelectrocatalysis, Titanium dioxide, Cuprous oxide, Composite thin film, Photo electrode. INTRODUCTION ... reddish p-type semiconductor with a direct band gap of 2.0-2.2 eV [18, 19]. ... Photoelectrocatalytic removal of color from water using TiO2 and TiO2/Cu2O electrodes. Bull.

  3. Marginal Accuracy of Castings Fabricated with Ringless Casting Investment System and Metal Ring Casting Investment System: A Comparative Study.

    Science.gov (United States)

    Kalavathi, M; Sachin, Bhuvana; Prasanna, B G; Shreeharsha, T V; Praveen, B; Ragher, Mallikarjuna

    2016-02-01

    The thermal expansion of the investment can be restricted by the metal casting ring because the thermal expansion of the ring is less than that of the investment. The ringless casting procedure is in use in clinical dentistry, though there is little scientific data to support its use in fixed partial dentures. In this study, marginal discrepancy of castings produced with the ringless casting technique and the conventional technique using the metal rings were compared. A total of 30 wax patterns were fabricated directly on a metal die. Optical stereomicroscope was used to measure the marginal discrepancy between the metal die and wax patterns. A total of 15 castings were invested using Bellavest T phosphate-bonded investment with the ringless technique and 15 were invested with the same investment with a metal ring; 30 castings were produced using a nickel-chromium ceramo-metal alloy. The internal surface of the castings was not modified and seated with finger pressure. The vertical marginal discrepancy was measured using an optical stereomicroscope at a magnification of 100x. The data obtained were statistically analyzed using students t-test (paired t-test and unpaired t-test). The castings of the ringless technique provided less vertical marginal discrepancy (240.56 ± 45.81 μ) than the castings produced with the conventional metal ring technique (281.98± 53.05 μ). The difference was statistically significant. The ringless casting technique had produced better marginal accuracy compared with conventional casting technique. Ringless casting system can be used routinely for clinical purpose.

  4. Gd(5)Si(4-x)Bi(x) structures: novel slab sequences achieved by turning off the directionality of nearest-slab interactions.

    Science.gov (United States)

    Svitlyk, Volodymyr; Campbell, Branton J; Mozharivskyj, Yurij

    2009-11-02

    Substitution of Bi for Si leads to the complete cleavage of the interslab dimers T-T in the Gd(5)Si(4-x)Bi(x) system with x = 1.58 - 2.42 (T is a mixture of Si and Bi). Equivalence of the interslab T...T contacts, achieved through combination of the electronic and geometrical parameters, removes directionality of nearest-slab interactions and allows for a novel slab stacking. Two new slab sequences, ABCDABCD (x = 2.07, I4(1)/acd space group) and ABADABAD (x = 2.42, P4(2)bc), have been discovered in Gd(5)Si(4-x)Bi(x) in addition to the known one, ABAB, that is dominant among the RE(5)X(4) phases (RE is a rare-earth element, X is a p-element). The slab stacking for x = 2.07 and x = 2.42 is dictated by the second-nearest slab interactions which promote an origin shift either for the entire slab sequence as in ABCDABCD or for every other second-nearest slab pair as in ABADABAD. The loss of the directionality of the nearest-slab bonding allows for extensive stacking faults and leads to diffuse scattering.

  5. Evolution of the slab bending radius and the bending dissipation in three-dimensional subduction models with a variable slab to upper mantle viscosity ratio

    NARCIS (Netherlands)

    Schellart, W. P.

    2009-01-01

    Three-dimensional laboratory subduction models are presented investigating the influence of the slab/upper mantle viscosity ratio (ηSP/ηUM) on the slab bending radius (RB), with ηSP/ηUM = 66-1375. Here, RB is non-dimensionalized by dividing it by the upper mantle thickness (TUM). The results show

  6. An Integrated Study on the Evolution of Inclusions in EH36 Shipbuilding Steel with Mg Addition: From Casting to Welding

    Science.gov (United States)

    Zou, Xiaodong; Zhao, Dapeng; Sun, Jincheng; Wang, Cong; Matsuura, Hiroyuki

    2018-04-01

    Inclusion evolution behaviors, in terms of composition, size, and number density, and associated influence on the microstructures of the as-cast slabs, rolled plates, and simulated welded samples of plain EH36 and EH36-Mg shipbuilding steels have been systematically investigated. The results indicate that the inclusions in the as-cast plain EH36 are almost Al-Ca-S-O-(Mn) complex oxides with sizes ranging from 1.0 to 2.0 μm. After Mg addition, a large amount of individually fine MnS precipitates and Mg-containing Ti-Al-Mg-O-(Mn-S) complex inclusions are generated, which significantly refine the microstructure and are conducive to the nucleation of acicular ferrite in the rolled and welded sample. Moreover, after rolling and welding thermal simulation, the number of individual MnS decreases gradually due to its precipitation on the surface of Ti-Al-Mg-O oxides.

  7. The evaluation of working casts prepared from digital impressions.

    Science.gov (United States)

    Hwang, Y C; Park, Y S; Kim, H K; Hong, Y S; Ahn, J S; Ryu, J J

    2013-01-01

    The aim of this study is to evaluate the reproducibility of working casts of a digital impression system by comparing them with the original, virtual, and rapid prototyping casts. A total of 54 cast sets in clinically stable occlusion were used. They were scanned by an iTero intraoral scanner and converted into STL format virtual casts. Rapid prototyping casts and polyurethane casts were fabricated from the iTero milling system based on the virtual casts. Several horizontal and vertical measurements were performed from the four types of casts, that is, original stone casts, virtual casts, rapid prototyping casts, and polyurethane casts of iTero. Measurement error, intraclass correlation coefficient (ICC), and differences among the casts were calculated and compared. Casts from iTero milling machines exhibited greater dimensional differences and lower ICC values than did other casts. In addition, many of the measurements of the iTero working casts showed statistically significant differences in comparison to the three other types of casts. In contrast, there were no statistically significant differences between the virtual and original casts. Virtual casts made by the iTero intraoral scanner exhibited excellent reproducibility. However, the casts from the iTero milling machine showed greater dimensional differences and lower reproducibility compared to other types of casts.

  8. Tomography of the subducting Pacific slab and the 2015 Bonin deepest earthquake (Mw 7.9).

    Science.gov (United States)

    Zhao, Dapeng; Fujisawa, Moeto; Toyokuni, Genti

    2017-03-15

    On 30 May 2015 an isolated deep earthquake (~670 km, Mw 7.9) occurred to the west of the Bonin Islands. To clarify its causal mechanism and its relationship to the subducting Pacific slab, we determined a detailed P-wave tomography of the deep earthquake source zone using a large number of arrival-time data. Our results show that this large deep event occurred within the subducting Pacific slab which is penetrating into the lower mantle. In the Izu-Bonin region, the Pacific slab is split at ~28° north latitude, i.e., slightly north of the 2015 deep event hypocenter. In the north the slab becomes stagnant in the mantle transition zone, whereas in the south the slab is directly penetrating into the lower mantle. This deep earthquake was caused by joint effects of several factors, including the Pacific slab's fast deep subduction, slab tearing, slab thermal variation, stress changes and phase transformations in the slab, and complex interactions between the slab and the ambient mantle.

  9. Post-Tensioned Concrete Long-Span Slabs in Projects of Modern Building Construction

    Science.gov (United States)

    Szydlowski, Rafal; Labuzek, Barbara

    2017-10-01

    Nowadays, design of modern an architectural building structures requires the use of slender and free from numerous supports slabs. The most suitable solution for above requirements are the post-tensioned slabs with unbounded tendons. Slabs prestressed by unbounded tendons are successfully used worldwide for several decades. During that time many recommendations dealing with the forming of geometry and prestressing, dimensioning and erection technology were issued. During the recent years prestressed slabs characterized by span and slenderness substantially exceeding recommended limitations were designed and erected with success in Poland. During the slabs erection and in two years of their using, the deflection of three oversized slabs were monitoring. In spite of designed the slabs significantly larger and slenderer than the recommended maximum value of span and span to depth ratio, the deflection of the slabs is definitely far from the limit value. The paper shows the geometry, characteristic and deflection of erected slabs and conclusion. Description of a very large span slab (21.3m), that was designed regarded to the information obtained from the previous realisation, is presented in this paper.

  10. Design of energy efficient building with radiant slab cooling

    Science.gov (United States)

    Tian, Zhen

    2007-12-01

    Air-conditioning comprises a substantial fraction of commercial building energy use because of compressor-driven refrigeration and fan-driven air circulation. Core regions of large buildings require year-round cooling due to heat gains from people, lights and equipment. Negative environmental impacts include CO2 emissions from electric generation and leakage of ozone-depleting refrigerants. Some argue that radiant cooling simultaneously improves building efficiency and occupant thermal comfort, and that current thermal comfort models fail to reflect occupant experience with radiant thermal control systems. There is little field evidence to test these claims. The University of Calgary's Information and Communications Technology (ICT) Building, is a pioneering radiant slab cooling installation in North America. Thermal comfort and energy performance were evaluated. Measurements included: (1) heating and cooling energy use, (2) electrical energy use for lighting and equipment, and (3) indoor temperatures. Accuracy of a whole building energy simulation model was evaluated with these data. Simulation was then used to compare the radiant slab design with a conventional (variable air volume) system. The radiant system energy performance was found to be poorer mainly due to: (1) simultaneous cooling by the slab and heating by other systems, (2) omission of low-exergy (e.g., groundwater) cooling possible with the high cooling water temperatures possible with radiant slabs and (3) excessive solar gain and conductive heat loss due to the wall and fenestration design. Occupant thermal comfort was evaluated through questionnaires and concurrent measurement of workstation comfort parameters. Analysis of 116 sets of data from 82 occupants showed that occupant assessment was consistent with estimates based on current thermal comfort models. The main thermal comfort improvements were reductions in (1) local discomfort from draft and (2) vertical air temperature stratification. The

  11. Delamination wear mechanism in gray cast irons

    International Nuclear Information System (INIS)

    Salehi, M.

    2000-01-01

    An investigation of the friction and sliding wear of gray cast iron against chromium plated cast irons was carried out on a newly constructed reciprocating friction and wear tester. The tests were the first to be done on the test rig under dry conditions and at the speed of 170 cm/min, and variable loads of 20-260 N for a duration of 15 min. to 3 hours. The gray cast iron surfaces worn by a process of plastic deformation at the subsurface, crack nucleation, and crack growth leading to formation of plate like debris and therefore the delamination theory applies. No evidence of adhesion was observed. This could be due to formation of oxides on the wear surface which prevent adhesion. channel type chromium plating ''picked'' up cast iron from the counter-body surfaces by mechanically trapping cast iron debris on and within the cracks. The removal of the plated chromium left a pitted surface on the cast iron

  12. Homogenity of Die Casting and Returning Material

    Directory of Open Access Journals (Sweden)

    J. Malik

    2012-04-01

    Full Text Available Homogeneity of die castings is influenced by wide range of technological parameters as piston velocity in filling chamber of die casting machine, filling time of mould cavity, temperature of cast alloy, temperature of the mould, temperature of filling chamber, surface pressure on alloy during mould filling, final pressure and others. Based on stated parameters it is clear, that main parameters of die casting are filling time of die mould cavity and velocity of the melt in the ingates. Filling time must ensure the complete filling of the mould cavity before solidification process can negatively influence it. Among technological parameters also belong the returning material, which ratio in charge must be constrained according to requirement on final homogeneity of die castings. With the ratio of returning material influenced are the mechanical properties of castings, inner homogeneity and chemical composition.

  13. Clean Cast Steel Technology, Phase IV

    Energy Technology Data Exchange (ETDEWEB)

    Charles E. Bates

    2003-02-24

    The objective of the Clean Cast Steel Technology Program was to improve casting product quality by removing or minimizing oxide defects and to allow the production of higher integrity castings for high speed machining lines. Previous research has concentrated on macro-inclusions that break, chip, or crack machine tool cutters and drills and cause immediate shutdown of the machining lines. The overall goal of the project is to reduce the amount of surface macro-inclusions and improve the machinability of steel castings. Macro-inclusions and improve the machinability of steel castings. Macro-inclusions have been identified by industrial sponsors as a major barrier to improving the quality and marketability of steel castings.

  14. Single-step fabrication of quantum funnels via centrifugal colloidal casting of nanoparticle films.

    KAUST Repository

    Kim, Jin Young

    2015-07-13

    Centrifugal casting of composites and ceramics has been widely employed to improve the mechanical and thermal properties of functional materials. This powerful method has yet to be deployed in the context of nanoparticles--yet size-effect tuning of quantum dots is among their most distinctive and application-relevant features. Here we report the first gradient nanoparticle films to be constructed in a single step. By creating a stable colloid of nanoparticles that are capped with electronic-conduction-compatible ligands we were able to leverage centrifugal casting for thin-films devices. This new method, termed centrifugal colloidal casting, is demonstrated to form films in a bandgap-ordered manner with efficient carrier funnelling towards the lowest energy layer. We constructed the first quantum-gradient photodiode to be formed in a single deposition step and, as a result of the gradient-enhanced electric field, experimentally measured the highest normalized detectivity of any colloidal quantum dot photodetector.

  15. Directional Solidification of Nodular Cast Iron

    Science.gov (United States)

    Curreri, P. A.; Stefanescu, D. M.; Hendrix, J. C.

    1987-01-01

    Cerium enhances formation of graphite nodules. Preliminary experiments in directional solidification of cast iron shows quantitative correlation of graphite microstructure with growth rate and thermal gradient, with sufficient spheroidizing element to form spheroidal graphite under proper thermal conditions. Experimental approach enables use of directional solidification to study solidification of spheriodal-graphite cast iron in low gravity. Possible to form new structural materials from nodular cast iron.

  16. Theory of uniqueness of Indian Caste System

    OpenAIRE

    Ashwin Kumar

    2006-01-01

    Classical studies on pre-modern Indian social structure have suggested apparent differences between the Indian caste system and social stratification as one can discern in other parts of the world. However, one needs to question such dogmatic assertions that such vast differences really existed. An endeavor is made in this research paper to reflect on the nature of caste hierarchy in pre-modern India. The caste system forms the significant basis of pre-modern Indian social structure. Early wr...

  17. Enhanced Extraction of Silicon-Vacancy Centers Light Emission Using Bottom-Up Engineered Polycrystalline Diamond Photonic Crystal Slabs.

    Science.gov (United States)

    Ondič, Lukáš; Varga, Marian; Hruška, Karel; Fait, Jan; Kapusta, Peter

    2017-03-28

    Silicon vacancy (SiV) centers are optically active defects in diamond. The SiV centers, in contrast to nitrogen vacancy (NV) centers, possess narrow and efficient luminescence spectrum (centered at ≈738 nm) even at room temperature, which can be utilized for quantum photonics and sensing applications. However, most of light generated in diamond is trapped in the material due to the phenomenon of total internal reflection. In order to overcome this issue, we have prepared two-dimensional photonic crystal slabs from polycrystalline diamond thin layers with high density of SiV centers employing bottom-up growth on quartz templates. We have shown that the spectral overlap between the narrow light emission of the SiV centers and the leaky modes extracting the emission into almost vertical direction (where it can be easily detected) can be obtained by controlling the deposition time. More than 14-fold extraction enhancement of the SiV centers photoluminescence was achieved compared to an uncorrugated sample. Computer simulation confirmed that the extraction enhancement originates from the efficient light-matter interaction between light emitted from the SiV centers and the photonic crystal slab.

  18. Energy Saving Melting and Revert Reduction Technology (Energy-SMARRT): Clean Steel Casting Production

    Energy Technology Data Exchange (ETDEWEB)

    Kuyucak, Selcuk [CanmetMATERIALS; Li, Delin [CanmetMATERIALS

    2013-12-31

    Inclusions in steel castings can cause rework, scrap, poor machining, and reduced casting performance, which can obviously result in excess energy consumption. Significant progress in understanding inclusion source, formation and control has been made. Inclusions can be defined as non-metallic materials such as refractory, sand, slag, or coatings, embedded in a metallic matrix. This research project has focused on the mold filling aspects to examine the effects of pouring methods and gating designs on the steel casting cleanliness through water modeling, computer modeling, and melting/casting experiments. Early in the research project, comprehensive studies of bottom-pouring water modeling and low-alloy steel casting experiments were completed. The extent of air entrainment in bottom-poured large castings was demonstrated by water modeling. Current gating systems are designed to prevent air aspiration. However, air entrainment is equally harmful and no prevention measures are in current practice. In this study, new basin designs included a basin dam, submerged nozzle, and nozzle extension. The entrained air and inclusions from the gating system were significantly reduced using the new basin method. Near the end of the project, there has been close collaboration with Wescast Industries Inc., a company manufacturing automotive exhaust components. Both computer modeling using Magma software and melting/casting experiments on thin wall turbo-housing stainless steel castings were completed in this short period of time. Six gating designs were created, including the current gating on the pattern, non-pressurized, partially pressurized, naturally pressurized, naturally pressurized without filter, and radial choke gating without filter, for Magma modeling. The melt filling velocity and temperature were determined from the modeling. Based on the simulation results, three gating designs were chosen for further melting and casting experiments on the same casting pattern using

  19. Spray casting project final report

    International Nuclear Information System (INIS)

    Churnetski, S.R.; Thompson, J.E.

    1996-08-01

    Lockheed Martin Energy Systems, Inc. (Energy Systems), along with other participating organizations, has been exploring the feasibility of spray casting depleted uranium (DU) to near-net shape as a waste minimization effort. Although this technology would be useful in a variety of applications where DU was the material of choice, this effort was aimed primarily at gamma-shielding components for use in storage and transportation canisters for high-level radioactive waste, particularly in the Multipurpose Canister (MPC) application. In addition to the waste-minimization benefits, spray casting would simplify the manufacturing process by allowing the shielding components for MPC to be produced as a single component, as opposed to multiple components with many fabrication and assembly steps. In earlier experiments, surrogate materials were used to simulate the properties (specifically reactivity and density) of DU. Based on the positive results from those studies, the project participants decided that further evaluation of the issues and concerns that would accompany spraying DU was warranted. That evaluation occupied substantially all of Fiscal Year 1995, yielding conceptual designs for both an intermediate facility and a production facility and their associated engineering estimates. An intermediate facility was included in this study to allow further technology development in spraying DU. Although spraying DU to near-net shape seems to be feasible, a number of technical, engineering, and safety issues would need to be evaluated before proceeding with a production facility. This report is intended to document the results from the spray-casting project and to provide information needed by anyone interested in proceeding to the next step

  20. Microstructured metal molds fabricated via investment casting

    International Nuclear Information System (INIS)

    Cannon, Andrew H; King, William P

    2010-01-01

    This paper describes an investment casting process to produce aluminum molds having integrated microstructures. Unlike conventional micromolding tools, the aluminum mold was large and had complex curved surfaces. The aluminum was cast from curved microstructured ceramic molds which were themselves cast from curved microstructured rubber. The aluminum microstructures had an aspect ratio of 1:1 and sizes ranging from 25 to 50 µm. Many structures were successfully cast into the aluminum with excellent replication fidelity, including circular, square and triangular holes. We demonstrate molding of large, curved surfaces having surface microstructures using the aluminum mold.