New Models for Velocity/Pressure-Gradient Correlations in Turbulent Boundary Layers

Science.gov (United States)

Poroseva, Svetlana; Murman, Scott

2014-11-01

To improve the performance of Reynolds-Averaged Navier-Stokes (RANS) turbulence models, one has to improve the accuracy of models for three physical processes: turbulent diffusion, interaction of turbulent pressure and velocity fluctuation fields, and dissipative processes. The accuracy of modeling the turbulent diffusion depends on the order of a statistical closure chosen as a basis for a RANS model. When the Gram-Charlier series expansions for the velocity correlations are used to close the set of RANS equations, no assumption on Gaussian turbulence is invoked and no unknown model coefficients are introduced into the modeled equations. In such a way, this closure procedure reduces the modeling uncertainty of fourth-order RANS (FORANS) closures. Experimental and direct numerical simulation data confirmed the validity of using the Gram-Charlier series expansions in various flows including boundary layers. We will address modeling the velocity/pressure-gradient correlations. New linear models will be introduced for the second- and higher-order correlations applicable to two-dimensional incompressible wall-bounded flows. Results of models' validation with DNS data in a channel flow and in a zero-pressure gradient boundary layer over a flat plate will be demonstrated. A part of the material is based upon work supported by NASA under award NNX12AJ61A.

A survey of repair practices for nuclear power plant containment metallic pressure boundaries

Energy Technology Data Exchange (ETDEWEB)

Oland, C.B.; Naus, D.J. [Oak Ridge National Lab., TN (United States)

1998-05-01

The Nuclear Regulatory Commission has initiated a program at the Oak Ridge National Laboratory to provide assistance in their assessment of the effects of potential degradation on the structural integrity and leaktightness of metal containment vessels and steel liners of concrete containments in nuclear power plants. One of the program objectives is to identify repair practices for restoring metallic containment pressure boundary components that have been damaged or degraded in service. This report presents issues associated with inservice condition assessments and continued service evaluations and identifies the rules and requirements for the repair and replacement of nonconforming containment pressure boundary components by welding or metal removal. Discussion topics include base and welding materials, welding procedure and performance qualifications, inspection techniques, testing methods, acceptance criteria, and documentation requirements necessary for making acceptable repairs and replacements so that the plant can be returned to a safe operating condition.

A survey of repair practices for nuclear power plant containment metallic pressure boundaries

International Nuclear Information System (INIS)

Oland, C.B.; Naus, D.J.

1998-05-01

The Nuclear Regulatory Commission has initiated a program at the Oak Ridge National Laboratory to provide assistance in their assessment of the effects of potential degradation on the structural integrity and leaktightness of metal containment vessels and steel liners of concrete containments in nuclear power plants. One of the program objectives is to identify repair practices for restoring metallic containment pressure boundary components that have been damaged or degraded in service. This report presents issues associated with inservice condition assessments and continued service evaluations and identifies the rules and requirements for the repair and replacement of nonconforming containment pressure boundary components by welding or metal removal. Discussion topics include base and welding materials, welding procedure and performance qualifications, inspection techniques, testing methods, acceptance criteria, and documentation requirements necessary for making acceptable repairs and replacements so that the plant can be returned to a safe operating condition

Grain boundary cavity growth under applied stress and internal pressure

International Nuclear Information System (INIS)

Mancuso, J.F.

1977-08-01

The growth of grain boundary cavities under applied stress and internal gas pressure was investigated. Methane gas filled cavities were produced by the C + 4H reversible CH4 reaction in the grain boundaries of type 270 nickel by hydrogen charging in an autoclave at 500 0 C with a hydrogen pressure of either 3.4 or 14.5 MPa. Intergranular fracture of nickel was achieved at a charging temperature of 300 0 C and 10.3 MPa hydrogen pressure. Cavities on the grain boundaries were observed in the scanning electron microscope after fracture. Photomicrographs of the cavities were produced in stereo pairs which were analyzed so as to correct for perspective distortion and also to determine the orientational dependence of cavity growth under an applied tensile stress

Basic fracture toughness requirements for ferritic materials of nuclear class pressure retaining equipment in NPP

International Nuclear Information System (INIS)

Ning Dong; Yao Weida

2005-01-01

In this paper, theory basis on cold brittleness and anti-brittle fracture design of ferritic materials are introduced summarily and fracture toughness requirements for ferritic materials in ASME code for nuclear safety class pressure retaining equipment in NPP are summarized and evaluated. The results show that notch impact toughness requirements for materials relate to nuclear safety class of materials so as to ensure that brittle fracture of retaining pressure boundary in NPP can not occur. (authors)

Modified Pressure-Correction Projection Methods: Open Boundary and Variable Time Stepping

KAUST Repository

Bonito, Andrea

2014-10-31

© Springer International Publishing Switzerland 2015. In this paper, we design and study two modifications of the first order standard pressure increment projection scheme for the Stokes system. The first scheme improves the existing schemes in the case of open boundary condition by modifying the pressure increment boundary condition, thereby minimizing the pressure boundary layer and recovering the optimal first order decay. The second scheme allows for variable time stepping. It turns out that the straightforward modification to variable time stepping leads to unstable schemes. The proposed scheme is not only stable but also exhibits the optimal first order decay. Numerical computations illustrating the theoretical estimates are provided for both new schemes.

Modified Pressure-Correction Projection Methods: Open Boundary and Variable Time Stepping

KAUST Repository

Bonito, Andrea; Guermond, Jean-Luc; Lee, Sanghyun

2014-01-01

© Springer International Publishing Switzerland 2015. In this paper, we design and study two modifications of the first order standard pressure increment projection scheme for the Stokes system. The first scheme improves the existing schemes in the case of open boundary condition by modifying the pressure increment boundary condition, thereby minimizing the pressure boundary layer and recovering the optimal first order decay. The second scheme allows for variable time stepping. It turns out that the straightforward modification to variable time stepping leads to unstable schemes. The proposed scheme is not only stable but also exhibits the optimal first order decay. Numerical computations illustrating the theoretical estimates are provided for both new schemes.

Wall-pressure fluctuations beneath a spatially evolving turbulent boundary layer

Science.gov (United States)

Mahesh, Krishnan; Kumar, Praveen

2016-11-01

Wall-pressure fluctuations beneath a turbulent boundary layer are important in applications dealing with structural deformation and acoustics. Simulations are performed for flat plate and axisymmetric, spatially evolving zero-pressure-gradient turbulent boundary layers at inflow Reynolds number of 1400 and 2200 based on momentum thickness. The simulations generate their own inflow using the recycle-rescale method. The results for mean velocity and second-order statistics show excellent agreement with the data available in literature. The spectral characteristics of wall-pressure fluctuations and their relation to flow structure will be discussed. This work is supported by ONR.

Structure of grain boundaries in hexagonal materials

International Nuclear Information System (INIS)

Sarrazit, F.

1998-05-01

The work presented in this thesis describes experimental and theoretical aspects associated with the structure of grain boundaries in hexagonal materials. It has been found useful to classify grain boundaries as low-angle, special or general on the basis of their structure. High-angle grain boundaries were investigated in tungsten carbide (WC) using conventional electron microscopy techniques, and three examples characteristic of the interfaces observed in this material were studied extensively. Three-dimensionally periodic patterns are proposed as plausible reference configurations, and the Burgers vectors of observed interfacial dislocations were predicted using a theory developed recently. The comparison of experimental observations with theoretical predictions proved to be difficult as contrast simulation techniques require further development for analysis to be completed confidently. Another part of this work involves the characterisation of high-angle grain boundaries in zinc oxide (ZnO) using circuit mapping. Two boundaries displayed structural features characteristic of the 'special' category, however, one boundary presented features which did not conform to this model. It is proposed that the latter observation shows a structural transition from the special to a more general type. Material fluxes involved in defect interactions were considered using the topological framework described in this work. A genera) expression was derived for the total flux arising which allows the behaviour of line-defects to be studied in complex interfacial processes. (author)

Entropy Generation in Steady Laminar Boundary Layers with Pressure Gradients

Directory of Open Access Journals (Sweden)

Donald M. McEligot

2014-07-01

Full Text Available In an earlier paper in Entropy [1] we hypothesized that the entropy generation rate is the driving force for boundary layer transition from laminar to turbulent flow. Subsequently, with our colleagues we have examined the prediction of entropy generation during such transitions [2,3]. We found that reasonable predictions for engineering purposes could be obtained for flows with negligible streamwise pressure gradients by adapting the linear combination model of Emmons [4]. A question then arises—will the Emmons approach be useful for boundary layer transition with significant streamwise pressure gradients as by Nolan and Zaki [5]. In our implementation the intermittency is calculated by comparison to skin friction correlations for laminar and turbulent boundary layers and is then applied with comparable correlations for the energy dissipation coefficient (i.e., non-dimensional integral entropy generation rate. In the case of negligible pressure gradients the Blasius theory provides the necessary laminar correlations.

Boundary element analysis of earthquake induced hydrodynamic pressures in a water reservoir

International Nuclear Information System (INIS)

Jablonski, A.M.

1988-11-01

The seismic analysis of concrete gravity and arch dams is affected by the hydrodynamic pressures in the water reservoir. Boundary element method (BEM) formulations are derived for the hydrodynamic pressures arising in a gravity dam-reservoir-foundation system, treating both 2- and 3-dimensional cases. The formulations are based on the respective mathematical models which are governed by two- and three-dimensional Helmholtz equations with appropriate boundary conditions. For infinite reservoirs, loss of energy due to pressure waves moving away toward infinity strongly influence response. Since it is not possible to discretize an infinite extent, the radiation damping due to outgoing waves is accounted for by incorporating special boundary conditions at the far end, and in a similar manner the loss of energy due to absorption of waves by a flexible bottom of reservoir and banks can be accounted for by a special condition along the boundaries. Numerical results are obtained and compared with available classical solutions and convergence of numerical results with the size and number of boundary elements is studied. It is concluded that the direct boundary element method is an effective tool for the evaluation of the hydrodynamic pressures in finite and infinite dam-reservoir-foundation systems subjected to harmonic-type motion, and can easily be extended to any type of random motion with fast Fourier transform techniques. 82 refs., 65 figs., 25 tabs

Plane-stress fields for sharp notches in pressure-sensitive materials

International Nuclear Information System (INIS)

Al-Abduljabbar, Abdulhamid

2003-01-01

The effect of pressure sensitive yield on materials toughness can be determined by investigating stress fields around cracks and notches. In this work, fully-developed plastic stress fields around sharp wedge-shaped notches of perfectly-plastic pressure-sensitive materials are investigated for plane-stress case and Mode 1 loading condition. The pressure-sensitive yielding behavior is represented using the Drucker-Prager criterion. Using equilibrium equations, boundary conditions, and the yield criterion, closed-form expressions for stress fields are derived. The analysis covers the gradual change in the notch angle and compares it with the limiting case of a pure horizontal crack. Effects of notch geometry and pressure sensitivity on stress fields are examined by considering different specimen geometries, as well as different levels of pressure sensitivity. Results indicate that while the stress values directly ahead of the notch-tip are not affected, the extent of stress sector at notch front is reduced, thereby causing increase in the radial stress value around the notch. As the pressure sensitivity increases the reduction of the stress sector directly ahead of the notch tip is more evident. Also, for high pressure sensitivity values, introduction of the notch angle reduces the variation of the stress levels. Results are useful for design of structural components. (author)

Development of pressure boundaries leak detection technology for nuclear reactor

International Nuclear Information System (INIS)

Zhang Yao; Zhang Dafa; Chen Dengke; Zhang Liming

2008-01-01

The leak detection for the pressure boundaries is an important safeguard in nuclear reactor operation. In the paper, the status and the characters on the development of the pressure boundaries leak detection technology for the nuclear reactor were reviewed, especially, and the advance of the radiation leak detection technology and the acoustic emission leak detection technology were analyzed. The new advance trend of the leak detection technology was primarily explored. According to the analysis results, it is point out that the advancing target of the leak detection technology is to enhance its response speed, sensitivity, and reliability, and to provide effective information for operator and decision-maker. The realization of the global leak detection and the whole life cycle health monitoring for the nuclear boundaries is a significant advancing tendency of the leak detection technology. (authors)

Role of the vertical pressure gradient in wave boundary layers

DEFF Research Database (Denmark)

Jensen, Karsten Lindegård; Sumer, B. Mutlu; Vittori, Giovanna

2014-01-01

By direct numerical simulation (DNS) of the flow in an oscillatory boundary layer, it is possible to obtain the pressure field. From the latter, the vertical pressure gradient is determined. Turbulent spots are detected by a criterion involving the vertical pressure gradient. The vertical pressure...... gradient is also treated as any other turbulence quantity like velocity fluctuations and statistical properties of the vertical pressure gradient are calculated from the DNS data. The presence of a vertical pressure gradient in the near bed region has significant implications for sediment transport....

Application of pressure-sensitive paint in shock-boundary layer interaction experiments

OpenAIRE

Seivwright, Douglas L.

1996-01-01

Approved for public release; distribution is unlimited A new type of pressure transducer, pressure-sensitive paint, was used to obtain pressure distributions associated with shock-boundary layer interaction. Based on the principle of photoluminescence and the process of oxygen quenching, pressure-sensitive paint provides a continous mapping of a pressure field over a surface of interest. The data measurement and acquisition system developed for use with the photoluminescence sensor was eva...

Intergranular and inter-phased boundaries in the materials

International Nuclear Information System (INIS)

Aslanides, A.; Backhaus-Ricoult, M.; Bayle-Guillemaud, P.

2000-01-01

This document collects the abstracts of the talks presented during the colloquium J2IM on the intergranular and inter-phased boundaries in the materials. Around the themes of the interfaces behaviour and grain boundaries defects in materials, these days dealt with the microstructure behaviour in many domains such as the interfaces in batteries, the irradiation damages and the special case of the fuel-cladding interactions, the stressed interfaces, the alumina or silicon carbides substrates. (A.L.B.)

Pressure-induced transition in the grain boundary of diamond

Science.gov (United States)

Chen, J.; Tang, L.; Ma, C.; Fan, D.; Yang, B.; Chu, Q.; Yang, W.

2017-12-01

Equation of state of diamond powder with different average grain sizes was investigated using in situ synchrotron x-ray diffraction and a diamond anvil cell (DAC). Comparison of compression curves was made for two samples with average grain size of 50nm and 100nm. The two specimens were pre-pressed into pellets and loaded in the sample pressure chamber of the DAC separately to minimized differences of possible systematic errors for the two samples. Neon gas was used as pressure medium and ruby spheres as pressure calibrant. Experiments were conducted at room temperature and high pressures up to 50 GPa. Fitting the compression data in the full pressure range into the third order Birch-Murnaghan equation of state yields bulk modulus (K) and its pressure derivative (K') of 392 GPa and 5.3 for 50nm sample and 398GPa and 4.5 for 100nm sample respectively. Using a simplified core-shell grain model, this result indicates that the grain boundary has an effective bulk modulus of 54 GPa. This value is similar to that observed for carbon nanotube[1] validating the recent theoretical diamond surface modeling[2]. Differential analysis of the compression cures demonstrates clear relative compressibility change at the pressure about 20 GPa. When fit the compression data below and above this pressure separately, the effect of grain size on bulk modulus reverses in the pressure range above 20 GPa. This observation indicates a possible transition of grain boundary structure, likely from sp2 hybridization at the surface[2] towards sp3like orbital structure which behaves alike the inner crystal. [1] Jie Tang, Lu-Chang Qin, Taizo Sasaki, Masako Yudasaka, Akiyuki Matsushita, and Sumio Iijima, Compressibility and Polygonization of Single-Walled Carbon Nanotubes under Hydrostatic Pressure, Physical Review Letters, 85(9), 1187-1198, 2000. [2] Shaohua Lu, Yanchao Wang, Hanyu Liu, Mao-sheng Miao, and Yanming Ma, Self-assembled ultrathin nanotubes on diamond (100) surface, Nature

Prevention of bolting degradation or failure in pressure boundary and support applications

International Nuclear Information System (INIS)

Merrick, E.A.; Rivers, A.; Bickford, J.; Marston, T.U.

1986-01-01

A discussion is presented of bolting degradation or failure experience in pressure boundary and component support applications in US commercial nuclear plants and the industry program to prevent failures in the future. The focus turns to steps which plant owners can take today to guard against pressure boundary bolt failure or degradation for existing plants or units being constructed. 'Tools' or products which the plant owner can expect from current industry programs which will be available in the near future to aid in understanding and improving bolting practices are described. (author)

Grain boundaries of nanocrystalline materials - their widths, compositions, and internal structures

International Nuclear Information System (INIS)

Fultz, B.; Frase, H.N.

2000-01-01

Nanocrystalline materials contain many atoms at and near grain boundaries. Sufficient numbers of Moessbauer probe atoms can be situated in grain boundary environments to make a clear contribution to the measured Moessbauer spectrum. Three types of measurements on nanocrystalline materials are reported here, all using Moessbauer spectrometry in conjunction with X-ray diffractometry, transmission electron microscopy, or small angle neutron scattering. By measuring the fraction of atoms contributing to the grain boundary component in a Moessbauer spectrum, and by knowing the grain size of the material, it is possible to deduce the average width of grain boundaries in metallic alloys. It is found that these widths are approximately 0.5 nm for fcc alloys and slightly larger than 1.0 nm for bcc alloys.Chemical segregation to grain boundaries can be measured by Moessbauer spectrometry, especially in conjunction with small angle neutron scattering. Such measurements on Fe-Cu and Fe 3 Si-Nb were used to study how nanocrystalline materials could be stabilized against grain growth by the segregation of Cu and Nb to grain boundaries. The segregation of Cu to grain boundaries did not stabilize the Fe-Cu alloys against grain growth, since the grain boundaries were found to widen and accept more Cu atoms during annealing. The Nb additions to Fe 3 Si did suppress grain growth, perhaps because of the low mobility of Nb atoms, but also perhaps because Nb atoms altered the chemical ordering in the alloy.The internal structure of grain boundaries in nanocrystalline materials prepared by high-energy ball milling is found to be unstable against internal relaxations at low temperatures. The Moessbauer spectra of the nanocrystalline samples showed changes in the hyperfine fields attributable to movements of grain boundary atoms. In conjunction with SANS measurements, the changes in grain boundary structure induced by cryogenic exposure and annealing at low temperature were found to be

Status of LWR primary pressure boundary structural materials

Energy Technology Data Exchange (ETDEWEB)

Chi, Se Hwan; Hong, Jun Hwa; Byun, Taek Sang; Kang, Sung Sik; Ryu, Woo Seog; Lee, Bong Sang; Kook, Il Hyun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1994-07-01

The integrity of major systems, structures and components is a prerequisite to the economy and safety of an existing light water reactor and also for the next generation reactors. As few reactor structural materials are being manufactured by domestic companies, based on economic and safety reasons, a new demand to improve the quality of domestic reactor structural materials and to develop reactor structural steels has arisen. Investigations on the state-of-the-art of the materials specifications, performance and current state of structural materials development were performed as a first step to domestic reactor structural steel development and summarized the result in the present report. (Author) 10 refs., 10 figs., 21 tabs.

Transient pressure and productivity analysis in carbonate geothermal reservoirs with changing external boundary flux

Directory of Open Access Journals (Sweden)

Wang Dongying

2017-01-01

Full Text Available In this paper, a triple-medium flow model for carbonate geothermal reservoirs with an exponential external boundary flux is established. The pressure solution under constant production conditions in Laplace space is solved. The geothermal wellbore pressure change considering wellbore storage and skin factor is obtained by Stehfest numerical inversion. The well test interpretation charts and Fetkovich production decline chart for carbonate geothermal reservoirs are proposed for the first time. The proposed Fetkovich production decline curves are applied to analyze the production decline behavior. The results indicate that in carbonate geothermal reservoirs with exponential external boundary flux, the pressure derivative curve contains a triple dip, which represents the interporosity flow between the vugs or matrix and fracture system and the invading flow of the external boundary flux. The interporosity flow of carbonate geothermal reservoirs and changing external boundary flux can both slow down the extent of production decline and the same variation tendency is observed in the Fetkovich production decline curve.

Aging of the containment pressure boundary in light-water reactor plants

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

1997-01-01

Research is being conducted by the Oak Ridge National Laboratory to address aging of the containment pressure boundary in light-water reactor plants. The objectives of this work are to (1) identify the significant factors related to occurrence of corrosion, efficacy of inspection, and structural capacity reduction of steel containments and liners of concrete containments, and to make recommendations on use of risk models in regulatory decisions; (2) provide NRC reviewers a means of establishing current structural capacity margins for steel containments, and concrete containments as limited by liner integrity; and (3) provide recommendations, as appropriate, on information to be requested of licensees for guidance that could be utilized by NRC reviewers in assessing the seriousness of reported incidences of containment degradation. In meeting these objectives research is being conducted in two primary task areas - pressure boundary condition assessment and root-cause resolution practices, and reliability-based condition assessments. Under the first task area a degradation assessment methodology was developed for use in characterizing the in-service condition of metal and concrete containment pressure boundary components and quantifying the amount of damage that is present. An assessment of available destructive and nondestructive techniques for examining steel containments and liners is ongoing. Under the second task area quantitative structural reliability analysis methods are being developed for application to degraded metallic pressure boundaries to provide assurances that they will be able to withstand future extreme loads during the desired service period with a level of reliability that is sufficient for public safety. To date, mathematical models that describe time-dependent changes in steel due to aggressive environmental factors have been identified, and statistical data supporting their use in time-dependent reliability analysis have been summarized

Jets from pulsed-ultrasound-induced cavitation bubbles near a rigid boundary

Science.gov (United States)

Brujan, Emil-Alexandru

2017-06-01

The dynamics of cavitation bubbles, generated from short (microsecond) pulses of ultrasound and situated near a rigid boundary, are investigated numerically. The temporal development of the bubble shape, bubble migration, formation of the liquid jet during bubble collapse, and the kinetic energy of the jet are investigated as a function of the distance between bubble and boundary. During collapse, the bubble migrates towards the boundary and the liquid jet reaches a maximum velocity between 80 m s-1 and 120 m s-1, depending on the distance between bubble and boundary. The conversion of bubble energy to kinetic energy of the jet ranges from 16% to 23%. When the bubble is situated in close proximity to the boundary, the liquid jet impacts the boundary with its maximum velocity, resulting in an impact pressure of the order of tens of MPa. The rapid expansion of the bubble, the impact of the liquid jet onto the nearby boundary material, and the high pressure developed inside the bubble at its minimum volume can all contribute to the boundary material damage. The high pressure developed during the impact of the liquid jet onto the biological material and the shearing forces acting on the material surface as a consequence of the radial flow of the jet outward from the impact site are the main damage mechanisms of rigid biological materials. The results are discussed with respect to cavitation damage of rigid biological materials, such as disintegration of renal stones and calcified tissue and collateral effects in pulsed ultrasound surgery.

Jets from pulsed-ultrasound-induced cavitation bubbles near a rigid boundary

International Nuclear Information System (INIS)

Brujan, Emil-Alexandru

2017-01-01

The dynamics of cavitation bubbles, generated from short (microsecond) pulses of ultrasound and situated near a rigid boundary, are investigated numerically. The temporal development of the bubble shape, bubble migration, formation of the liquid jet during bubble collapse, and the kinetic energy of the jet are investigated as a function of the distance between bubble and boundary. During collapse, the bubble migrates towards the boundary and the liquid jet reaches a maximum velocity between 80 m s −1 and 120 m s −1 , depending on the distance between bubble and boundary. The conversion of bubble energy to kinetic energy of the jet ranges from 16% to 23%. When the bubble is situated in close proximity to the boundary, the liquid jet impacts the boundary with its maximum velocity, resulting in an impact pressure of the order of tens of MPa. The rapid expansion of the bubble, the impact of the liquid jet onto the nearby boundary material, and the high pressure developed inside the bubble at its minimum volume can all contribute to the boundary material damage. The high pressure developed during the impact of the liquid jet onto the biological material and the shearing forces acting on the material surface as a consequence of the radial flow of the jet outward from the impact site are the main damage mechanisms of rigid biological materials. The results are discussed with respect to cavitation damage of rigid biological materials, such as disintegration of renal stones and calcified tissue and collateral effects in pulsed ultrasound surgery. (paper)

A Sharp-Interface Immersed Boundary Method with Improved Mass Conservation and Reduced Spurious Pressure Oscillations.

Science.gov (United States)

Seo, Jung Hee; Mittal, Rajat

2011-08-10

A method for reducing the spurious pressure oscillations observed when simulating moving boundary flow problems with sharp-interface immersed boundary methods (IBMs) is proposed. By first identifying the primary cause of these oscillations to be the violation of the geometric conservation law near the immersed boundary, we adopt a cut-cell based approach to strictly enforce geometric conservation. In order to limit the complexity associated with the cut-cell method, the cut-cell based discretization is limited only to the pressure Poisson and velocity correction equations in the fractional-step method and the small-cell problem tackled by introducing a virtual cell-merging technique. The method is shown to retain all the desirable properties of the original finite-difference based IBM while at the same time, reducing pressure oscillations for moving boundaries by roughly an order of magnitude.

Permeability measurement of some barrier materials as a function of temperature and pressure

International Nuclear Information System (INIS)

Maqsood, M.; Faisal, S.; Ali, J.; Usman, A.; Alamgir, K.; Farooq, K.

2011-01-01

Barrier materials possess the ability to restrict the passage of gases, vapors, and organic liquids through their boundaries. These barrier materials have large number of applications in industry and scientific research. To measure the permeability of barrier materials, a specific gas flow system has been developed, pure helium gas is used to measure the back ground reading through SS-316. The permeability and break-through time has been measured through Inconel X-750, NBR and Viton below and above the atmospheric pressure and at different temperatures 20 deg. C, 40 deg. C and 70 deg. C. (author)

Pressure estimation from single-snapshot tomographic PIV in a turbulent boundary layer

NARCIS (Netherlands)

Schneiders, J.F.G.; Pröbsting, S.; Dwight, R.P.; Van Oudheusden, B.W.; Scarano, F.

2016-01-01

A method is proposed to determine the instantaneous pressure field from a single tomographic PIV velocity snapshot and is applied to a flat-plate turbulent boundary layer. The main concept behind the single-snapshot pressure evaluation method is to approximate the flow acceleration using the

Acoustic Emission for on-line reactor pressure boundary monitoring

International Nuclear Information System (INIS)

Hutton, P.H.; Kurtz, R.J.; Pappas, R.A.

1985-01-01

The program objective is to develop AE for continuous surveillance to assess flaw growth in reactor pressure boundaries. Technology in the laboratory is being evaluated on structures. Results have demonstrated basic feasibility of the program objective. AE monitoring a long term fatigue test of a pressure vessel demonstrated an instrument system, and the ability to detect unexpected as well as well as known fatigue cracks. Monitoring a nuclear reactor system shows that the coolant flow noise problem is manageable and AE can be detected under simulated operating conditions

A Rotational Pressure-Correction Scheme for Incompressible Two-Phase Flows with Open Boundaries

Science.gov (United States)

Dong, S.; Wang, X.

2016-01-01

Two-phase outflows refer to situations where the interface formed between two immiscible incompressible fluids passes through open portions of the domain boundary. We present several new forms of open boundary conditions for two-phase outflow simulations within the phase field framework, as well as a rotational pressure correction based algorithm for numerically treating these open boundary conditions. Our algorithm gives rise to linear algebraic systems for the velocity and the pressure that involve only constant and time-independent coefficient matrices after discretization, despite the variable density and variable viscosity of the two-phase mixture. By comparing simulation results with theory and the experimental data, we show that the method produces physically accurate results. We also present numerical experiments to demonstrate the long-term stability of the method in situations where large density contrast, large viscosity contrast, and backflows occur at the two-phase open boundaries. PMID:27163909

Sound transmission through double cylindrical shells lined with porous material under turbulent boundary layer excitation

Science.gov (United States)

Zhou, Jie; Bhaskar, Atul; Zhang, Xin

2015-11-01

This paper investigates sound transmission through double-walled cylindrical shell lined with poroelastic material in the core, excited by pressure fluctuations due to the exterior turbulent boundary layer (TBL). Biot's model is used to describe the sound wave propagating in the porous material. Three types of constructions, bonded-bonded, bonded-unbonded and unbonded-unbonded, are considered in this study. The power spectral density (PSD) of the inner shell kinetic energy is predicted for two turbulent boundary layer models, different air gap depths and three types of polyimide foams, respectively. The peaks of the inner shell kinetic energy due to shell resonance, hydrodynamic coincidence and acoustic coincidence are discussed. The results show that if the frequency band over the ring frequency is of interest, an air gap, even if very thin, should exist between the two elastic shells for better sound insulation. And if small density foam has a high flow resistance, a superior sound insulation can still be maintained.

Hypersonic Wind-Tunnel Measurements of Boundary-Layer Pressure Fluctuations

Science.gov (United States)

2009-08-01

Fluctuation Cone The Pressure-Fluctuation Cone was used for all wind-tunnel tests (Figure 3.7). The model is a 7◦ half-angle stainless - steel cone. It...analysis as a medium for fault detection: A review. Journal of Tribology , 130, January 2008. [80] L. M. Mack. Boundary layer linear stability theory. In

Green's function and boundary elements of multifield materials

CERN Document Server

Qin, Qing-Hua

2007-01-01

Green's Function and Boundary Elements of Multifield Materials contains a comprehensive treatment of multifield materials under coupled thermal, magnetic, electric, and mechanical loads. Its easy-to-understand text clarifies some of the most advanced techniques for deriving Green's function and the related boundary element formulation of magnetoelectroelastic materials: Radon transform, potential function approach, Fourier transform. Our hope in preparing this book is to attract interested readers and researchers to a new field that continues to provide fascinating and technologically important challenges. You will benefit from the authors' thorough coverage of general principles for each topic, followed by detailed mathematical derivation and worked examples as well as tables and figures where appropriate. In-depth explanations of the concept of Green's function Coupled thermo-magneto-electro-elastic analysis Detailed mathematical derivation for Green's functions.

Non-adiabatic pressure loss boundary condition for modelling turbocharger turbine pulsating flow

International Nuclear Information System (INIS)

Chiong, M.S.; Rajoo, S.; Romagnoli, A.; Costall, A.W.; Martinez-Botas, R.F.

2015-01-01

Highlights: • Bespoke non-adiabatic pressure loss boundary for pulse flow turbine modelling. • Predictions show convincing results against experimental and literature data. • Predicted pulse pressure propagation is in good agreement with literature data. • New methodology is time efficient and requires minimal geometrical inputs. - Abstract: This paper presents a simplified methodology of pulse flow turbine modelling, as an alternative over the meanline integrated methodology outlined in previous work, in order to make its application to engine cycle simulation codes much more straight forward. This is enabled through the development of a bespoke non-adiabatic pressure loss boundary to represent the turbine rotor. In this paper, turbocharger turbine pulse flow performance predictions are presented along with a comparison of computation duration against the previously established integrated meanline method. Plots of prediction deviation indicate that the mass flow rate and actual power predictions from both methods are highly comparable and are reasonably close to experimental data. However, the new boundary condition required significantly lower computational time and rotor geometrical inputs. In addition, the pressure wave propagation in this simplified unsteady turbine model at different pulse frequencies has also been found to be in agreement with data from the literature, thereby supporting the confidence in its ability to simulate the wave action encountered in turbine pulse flow operation

Modelling of pressurized water reactor fuel, rod time dependent radial heat flow with boundary element method; Modeliranje spremenljivega radijalnega toplotnega toka tlacnovodne gorivne palice z metodo robnih elementov

Energy Technology Data Exchange (ETDEWEB)

Sarler, B [Institut Jozef Stefan, Ljubljana (Yugoslavia)

1987-07-01

The basic principles of the boundary element method numerical treatment of the radial flow heat diffusion equation are presented. The algorithm copes the time dependent Dirichlet and Neumann boundary conditions, temperature dependent material properties and regions from different materials in thermal contact. It is verified on the several analytically obtained test cases. The developed method is used for the modelling of unsteady radial heat flow in pressurized water reactor fuel rod. (author)

Lattice Boltzmann simulations of pressure-driven flows in microchannels using Navier–Maxwell slip boundary conditions

KAUST Repository

Reis, Tim

2012-01-01

We present lattice Boltzmann simulations of rarefied flows driven by pressure drops along two-dimensional microchannels. Rarefied effects lead to non-zero cross-channel velocities, nonlinear variations in the pressure along the channel. Both effects are absent in flows driven by uniform body forces. We obtain second-order accuracy for the two components of velocity the pressure relative to asymptotic solutions of the compressible Navier-Stokes equations with slip boundary conditions. Since the common lattice Boltzmann formulations cannot capture Knudsen boundary layers, we replace the usual discrete analogs of the specular diffuse reflection conditions from continuous kinetic theory with a moment-based implementation of the first-order Navier-Maxwell slip boundary conditions that relate the tangential velocity to the strain rate at the boundary. We use these conditions to solve for the unknown distribution functions that propagate into the domain across the boundary. We achieve second-order accuracy by reformulating these conditions for the second set of distribution functions that arise in the derivation of the lattice Boltzmann method by an integration along characteristics. Our moment formalism is also valuable for analysing the existing boundary conditions. It reveals the origin of numerical slip in the bounce-back other common boundary conditions that impose conditions on the higher moments, not on the local tangential velocity itself. © 2012 American Institute of Physics.

Temperature and stress distribution in pressure vessel by the boundary element method

International Nuclear Information System (INIS)

Alujevic, A.; Apostolovic, D.

1990-01-01

The aim of this paper is to demonstrate the applicability of boundary element method for the solution of temperatures and thermal stresses in the body of reactor pressure vessel of the NPP Krsko . In addition to the theory of boundary elements for thermo-elastic continua (2D, 3D) results are given of a numerically evaluated meridional cross-section. (author)

Pressure tuning of the morphotropic phase boundary in piezoelectric lead zirconate titanate

International Nuclear Information System (INIS)

Rouquette, J.; Haines, J.; Bornand, V.; Pintard, M.; Papet, Ph.; Bousquet, C.; Konczewicz, L.; Gorelli, F. A.; Hull, S.

2004-01-01

Titanium-rich PZT solid solutions were studied under high pressure by neutron and x-ray diffraction, Raman spectroscopy and dielectric measurements. The results show that high pressure stabilizes the ferroelectric monoclinic phases, which are proposed to be responsible for the high piezoelectric properties characteristic of the morphotropic composition PbZr 0.52 Ti 0.48 O 3 . Pressure may thus be used to tune the morphotropic phase boundary in the composition-pressure plane to include a wide range of titanium-rich PZT compositions

Integrity of the reactor coolant boundary of the European pressurized water reactor (EPR)

Energy Technology Data Exchange (ETDEWEB)

Goetsch, D.; Bieniussa, K.; Schulz, H.; Jalouneix, J.

1997-04-01

This paper is an abstract of the work performed in the frame of the development of the IPSN/GRS approach in view of the EPR conceptual safety features. EPR is a pressurized water reactor which will be based on the experience gained by utilities and designers in France and in Germany. The reactor coolant boundary of a PWR includes the reactor pressure vessel (RPV), those parts of the steam generators (SGs) which contain primary coolant, the pressurizer (PSR), the reactor coolant pumps (RCPs), the main coolant lines (MCLs) with their branches as well as the other connecting pipes and all branching pipes including the second isolation valves. The present work covering the integrity of the reactor coolant boundary is mainly restricted to the integrity of the main coolant lines (MCLs) and reflects the design requirements for the main components of the reactor coolant boundary. In the following the conceptual aspects, i.e. design, manufacture, construction and operation, will be assessed. A main aspect is the definition of break postulates regarding overall safety implications.

Integrity of the reactor coolant boundary of the European pressurized water reactor (EPR)

International Nuclear Information System (INIS)

Goetsch, D.; Bieniussa, K.; Schulz, H.; Jalouneix, J.

1997-01-01

This paper is an abstract of the work performed in the frame of the development of the IPSN/GRS approach in view of the EPR conceptual safety features. EPR is a pressurized water reactor which will be based on the experience gained by utilities and designers in France and in Germany. The reactor coolant boundary of a PWR includes the reactor pressure vessel (RPV), those parts of the steam generators (SGs) which contain primary coolant, the pressurizer (PSR), the reactor coolant pumps (RCPs), the main coolant lines (MCLs) with their branches as well as the other connecting pipes and all branching pipes including the second isolation valves. The present work covering the integrity of the reactor coolant boundary is mainly restricted to the integrity of the main coolant lines (MCLs) and reflects the design requirements for the main components of the reactor coolant boundary. In the following the conceptual aspects, i.e. design, manufacture, construction and operation, will be assessed. A main aspect is the definition of break postulates regarding overall safety implications

Tuning of turbulent boundary layer anisotropy for improved surface pressure and trailing-edge noise modeling

DEFF Research Database (Denmark)

Bertagnolio, Franck; Fischer, Andreas; Zhu, Wei Jun

2014-01-01

The modeling of the surface pressure spectrum beneath a turbulent boundary layer is investigated, focusing on the case of airfoil flows and associated trailing edge noise prediction using the so-called TNO model. This type of flow is characterized by the presence of an adverse pressure gradient...... along the airfoil chord. It is shown that discrepancies between measurements and results from the TNO model increase as the pressure gradient increases. The original model is modified by introducing anisotropy in the definition of the turbulent vertical velocity spectrum across the boundary layer...

Grain boundary engineering for structure materials of nuclear reactors

Science.gov (United States)

Tan, L.; Allen, T. R.; Busby, J. T.

2013-10-01

Grain boundary engineering (GBE), primarily implemented by thermomechanical processing, is an effective and economical method of enhancing the properties of polycrystalline materials. Among the factors affecting grain boundary character distribution, literature data showed definitive effect of grain size and texture. GBE is more effective for austenitic stainless steels and Ni-base alloys compared to other structural materials of nuclear reactors, such as refractory metals, ferritic and ferritic-martensitic steels, and Zr alloys. GBE has shown beneficial effects on improving the strength, creep strength, and resistance to stress corrosion cracking and oxidation of austenitic stainless steels and Ni-base alloys.

Grain boundary engineering for structure materials of nuclear reactors

Energy Technology Data Exchange (ETDEWEB)

Tan, L., E-mail: tanl@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory (United States); Allen, T.R. [Department of Engineering Physics, University of Wisconsin–Madison (United States); Busby, J.T. [Materials Science and Technology Division, Oak Ridge National Laboratory (United States)

2013-10-15

Grain boundary engineering (GBE), primarily implemented by thermomechanical processing, is an effective and economical method of enhancing the properties of polycrystalline materials. Among the factors affecting grain boundary character distribution, literature data showed definitive effect of grain size and texture. GBE is more effective for austenitic stainless steels and Ni-base alloys compared to other structural materials of nuclear reactors, such as refractory metals, ferritic and ferritic–martensitic steels, and Zr alloys. GBE has shown beneficial effects on improving the strength, creep strength, and resistance to stress corrosion cracking and oxidation of austenitic stainless steels and Ni-base alloys.

DNS of transcritical turbulent boundary layers at supercritical pressures under abrupt variations in thermodynamic properties

Science.gov (United States)

Kawai, Soshi

2014-11-01

In this talk, we first propose a numerical strategy that is robust and high-order accurate for enabling to simulate transcritical flows at supercritical pressures under abrupt variations in thermodynamic properties due to the real fluid effects. The method is based on introducing artificial density diffusion in a physically-consistent manner in order to capture the steep variation of thermodynamic properties in transcritical conditions robustly, while solving a pressure evolution equation to achieve pressure equilibrium at the transcritical interfaces. We then discuss the direct numerical simulation (DNS) of transcritical heated turbulent boundary layers on a zero-pressure-gradient flat plate at supercritical pressures. To the best of my knowledge, the present DNS is the first DNS of zero-pressure-gradient flat-plate transcritical turbulent boundary layer. The turbulent kinetic budget indicates that the compressibility effects (especially, pressure-dilatation correlation) are not negligible at the transcritical conditions even if the flow is subsonic. The unique and interesting interactions between the real fluid effects and wall turbulence, and their turbulence statistics, which have never been seen in the ideal-fluid turbulent boundary layers, are also discussed. This work was supported in part by Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Young Scientists (A) KAKENHI 26709066 and the JAXA International Top Young Fellowship Program.

Boundary layers affected by different pressure gradients investigated computationally by a zonal RANS-LES method

International Nuclear Information System (INIS)

Roidl, B.; Meinke, M.; Schröder, W.

2014-01-01

Highlights: • Reformulated synthetic turbulence generation method (RSTGM) is applied. • Zonal RANS-LES method is applied to boundary layers at pressure gradients. • Good agreement with the pure LES and other reference data is obtained. • The RSTGM is applicable to pressure gradient flows without modification. • RANS-to-LES boundary should be located where -1·10 6 6 is satisfied. -- Abstract: The reformulated synthetic turbulence generation (RSTG) method is used to compute by a fully coupled zonal RANS-LES approach turbulent non-zero-pressure gradient boundary layers. The quality of the RSTG method, which is based on the same shape functions and length scale distributions as in zero-pressure gradient flow, is discussed by comparing the zonal RANS-LES findings with pure LES, pure RANS, direct numerical simulation (DNS), and experimental data. For the favorable pressure gradient (FPG) simulation the RANS-to-LES transition occurs in the accelerated flow region and for the adverse pressure gradient (APG) case it is located in the decelerated flow region. The results of the time and spanwise averaged skin-friction distributions, velocity profiles, and Reynolds stress distributions of the zonal RANS-LES simulation show a satisfactory to good agreement with the pure LES, reference DNS, and experimental data. The quality of the findings shows that the rigorous formulation of the synthetic turbulence generation makes the RSTG method applicable without a priori knowledge of the flow properties but those determined by the RANS solution and without using additional control planes to regulate the shear stress budget to a wide range of Reynolds numbers and pressure gradients. The method is a promising approach to formulate embedded RANS-to-LES boundaries in flow regions where the Pohlhausen or acceleration parameter satisfies -1·10 -6 ⩽K⩽2·10 -6

Experimental Investigation of Separated and Transitional Boundary Layers Under Low-Pressure Turbine Airfoil Conditions

Science.gov (United States)

Hultgren, Lennart S.; Volino, Ralph J.

2002-01-01

Modern low-pressure turbine airfoils are subject to increasingly stronger pressure gradients as designers impose higher loading in an effort to improve efficiency and to reduce part count. The adverse pressure gradients on the suction side of these airfoils can lead to boundary-layer separation, particularly under cruise conditions. Separation bubbles, notably those which fail to reattach, can result in a significant degradation of engine efficiency. Accurate prediction of separation and reattachment is hence crucial to improved turbine design. This requires an improved understanding of the transition flow physics. Transition may begin before or after separation, depending on the Reynolds number and other flow conditions, has a strong influence on subsequent reattachment, and may even eliminate separation. Further complicating the problem are the high free-stream turbulence levels in a real engine environment, the strong pressure gradients along the airfoils, the curvature of the airfoils, and the unsteadiness associated with wake passing from upstream stages. Because of the complicated flow situation, transition in these devices can take many paths that can coexist, vary in importance, and possibly also interact, at different locations and instances in time. The present work was carried out in an attempt to systematically sort out some of these issues. Detailed velocity measurements were made along a flat plate subject to the same nominal dimensionless pressure gradient as the suction side of a modern low-pressure turbine airfoil ('Pak-B'). The Reynolds number based on wetted plate length and nominal exit velocity, Re, was varied from 50;000 to 300; 000, covering cruise to takeoff conditions. Low, 0.2%, and high, 7%, inlet free-stream turbulence intensities were set using passive grids. These turbulence levels correspond to about 0.2% and 2.5% turbulence intensity in the test section when normalized with the exit velocity. The Reynolds number and free

Investigation of Materials for Boundary Layer Control in a Supersonic Wind Tunnel

Science.gov (United States)

Braafladt, Alexander; Lucero, John M.; Hirt, Stefanie M.

2013-01-01

During operation of the NASA Glenn Research Center 15- by 15-Centimeter Supersonic Wind Tunnel (SWT), a significant, undesirable corner flow separation is created by the three-dimensional interaction of the wall and floor boundary layers in the tunnel corners following an oblique-shock/ boundary-layer interaction. A method to minimize this effect was conceived by connecting the wall and floor boundary layers with a radius of curvature in the corners. The results and observations of a trade study to determine the effectiveness of candidate materials for creating the radius of curvature in the SWT are presented. The experiments in the study focus on the formation of corner fillets of four different radii of curvature, 6.35 mm (0.25 in.), 9.525 mm (0.375 in.), 12.7 mm (0.5 in.), and 15.875 mm (0.625 in.), based on the observed boundary layer thickness of 11.43 mm (0.45 in.). Tests were performed on ten candidate materials to determine shrinkage, surface roughness, cure time, ease of application and removal, adhesion, eccentricity, formability, and repeatability. Of the ten materials, the four materials which exhibited characteristics most promising for effective use were the heavy body and regular type dental impression materials, the basic sculpting epoxy, and the polyurethane sealant. Of these, the particular material which was most effective, the heavy body dental impression material, was tested in the SWT in Mach 2 flow, and was observed to satisfy all requirements for use in creating the corner fillets in the upcoming experiments on shock-wave/boundary-layer interaction.

Bruce Power's nuclear pressure boundary quality assurance program requirements, implementation and transition

International Nuclear Information System (INIS)

Krane, J.C.

2009-01-01

The development of a full scope nuclear pressure boundary quality assurance program in Canada requires extensive knowledge of the structure and detailed requirements of codes and standards published by the Canadian Standards Association (CSA) and American Society of Mechanical Engineers (ASME). Incorporation into company governance documents and implementation of these requirements while managing the transition to more recent revisions of these codes and standards represents a significant challenge for Bruce Power, Canada's largest independent nuclear operator. This paper explores the key developments and innovative changes that are used to ensure successful regulatory compliance and effective implementation of the Bruce Power Pressure Boundary Quality Assurance Program. Challenges and mitigating strategies to sustain this large compliance based program at Bruce Power's 8 unit nuclear power plant site will also be detailed. (author)

Significance of grain boundaries and stacking faults on hydrogen storage properties of Mg2Ni intermetallics processed by high-pressure torsion

International Nuclear Information System (INIS)

Hongo, Toshifumi; Edalati, Kaveh; Arita, Makoto; Matsuda, Junko; Akiba, Etsuo; Horita, Zenji

2015-01-01

Mg 2 Ni intermetallics are processed using three different routes to produce three different microstructural features: annealing at high temperature for coarse grain formation, severe plastic deformation through high-pressure torsion (HPT) for nanograin formation, and HPT processing followed by annealing for the introduction of stacking faults. It is found that both grain boundaries and stacking faults are significantly effective to activate the Mg 2 Ni intermetallics for hydrogen storage at 423 K (150 °C). The hydrogenation kinetics is also considerably enhanced by the introduction of large fractions of grain boundaries and stacking faults while the hydrogenation thermodynamics remains unchanged. This study shows that, similar to grain boundaries and cracks, stacking faults can act as quick pathways for the transportation of hydrogen in the hydrogen storage materials

Boundary surface and microstructure analysis of ceramic materials

International Nuclear Information System (INIS)

Woltersdorf, J.; Pippel, E.

1992-01-01

The article introduces the many possibilities of high voltage (HVEM) and high resolution electron microscopy (HREM) for boundary surface and microstructure analysis of ceramic materials. The investigations are limited to ceramic long fibre composites and a ceramic fibre/glass matrix system. (DG) [de

Numerical study of ambient pressure for laser-induced bubble near a rigid boundary

Science.gov (United States)

Li, BeiBei; Zhang, HongChao; Han, Bing; Lu, Jian

2012-07-01

The dynamics of the laser-induced bubble at different ambient pressures was numerically studied by Finite Volume Method (FVM). The velocity of the bubble wall, the liquid jet velocity at collapse, and the pressure of the water hammer while the liquid jet impacting onto the boundary are found to increase nonlinearly with increasing ambient pressure. The collapse time and the formation time of the liquid jet are found to decrease nonlinearly with increasing ambient pressure. The ratios of the jet formation time to the collapse time, and the displacement of the bubble center to the maximal radius while the jet formation stay invariant when ambient pressure changes. These ratios are independent of ambient pressure.

Electrical properties of grain boundaries in polycrystalline materials under intrinsic or low doping

International Nuclear Information System (INIS)

Chowdhury, M H; Kabir, M Z

2011-01-01

An analytical model is developed to study the electrical properties (electric field and potential distributions, potential energy barrier height and polarization phenomenon) of polycrystalline materials at intrinsic or low doping for detector and solar cell applications by considering an arbitrary amount of grain boundary charge and a finite width of grain boundary region. The general grain boundary model is also applicable to highly doped polycrystalline materials. The electric field and potential distributions are obtained by solving Poisson's equation in both depleted grains and grain boundary regions. The electric field and potential distributions across the detector are analysed under various doping, trapping and applied biases. The electric field collapses, i.e. a nearly zero-average electric field region exists in some part of the biased detector at high trapped charge densities at the grain boundaries. The model explains the conditions of existence of a zero-average field region, i.e. the polarization mechanisms in polycrystalline materials. The potential energy barrier at the grain boundary exists if the electric field changes its sign at the opposite side of the grain boundary. The energy barrier does not exist in all grain boundaries in the low-doped polycrystalline detector and it never exists in intrinsic polycrystalline detectors under applied bias condition provided that there is no charge trapping in the grain.

Boundary element analysis of stress due to thermal shock loading or reactor pressure vessel nozzle; Napetostna analiza pri nestacionarni termicni obremenitvi cevnega prikljucka reaktorske tlacne posode z metodo robnih elementov

Energy Technology Data Exchange (ETDEWEB)

Kramberger, J; Potrc, I [Tehniska fakulteta, Maribor (Yugoslavia)

1989-07-01

Apart from being exposed to the primary loading of internal pressure and steady temperature field, the reactor pressure vessel is also subject to various thermal transients (thermal shocks). Theoretical and experimental stress analyses show that severe material stresses occur in the nozzle area of the pressure vessel which may lead to defects (cracks). It has been our aim to evaluate these stresses by the use of the Boundary Element method. (author)

Acoustic emission and estimation of flaw significance in reactor pressure boundaries

International Nuclear Information System (INIS)

Hutton, P.H.; Kurtz, R.J.

1982-01-01

The work discussed is intended to establish the feasibility of using acoustic emission (AE) to detect and evaluate growing flaws in nuclear reactor pressure boundaries. Basic AE identification and interpretation methods have grown out of Phase 1. Phases 2 and 3 to test and demonstrate developed methodology on a vessel test and on a reactor are in progress

Problems and chances for probabilistic fracture mechanics in the analysis of steel pressure boundary reliability

Energy Technology Data Exchange (ETDEWEB)

Staat, M [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Sicherheitsforschung und Reaktortechnik

1996-12-01

It is shown that the difficulty for probabilistic fracture mechanics (PFM) is the general problem of the high reliability of a small population. There is no way around the problem as yet. Therefore what PFM can contribute to the reliability of steel pressure boundaries is demonstrated with the example of a typical reactor pressure vessel and critically discussed. Although no method is distinguishable that could give exact failure probabilities, PFM has several additional chances. Upper limits for failure probability may be obtained together with trends for design and operating conditions. Further, PFM can identify the most sensitive parameters, improved control of which would increase reliability. Thus PFM should play a vital role in the analysis of steel pressure boundaries despite all shortcomings. (author). 19 refs, 7 figs, 1 tab.

Problems and chances for probabilistic fracture mechanics in the analysis of steel pressure boundary reliability

International Nuclear Information System (INIS)

Staat, M.

1996-01-01

It is shown that the difficulty for probabilistic fracture mechanics (PFM) is the general problem of the high reliability of a small population. There is no way around the problem as yet. Therefore what PFM can contribute to the reliability of steel pressure boundaries is demonstrated with the example of a typical reactor pressure vessel and critically discussed. Although no method is distinguishable that could give exact failure probabilities, PFM has several additional chances. Upper limits for failure probability may be obtained together with trends for design and operating conditions. Further, PFM can identify the most sensitive parameters, improved control of which would increase reliability. Thus PFM should play a vital role in the analysis of steel pressure boundaries despite all shortcomings. (author). 19 refs, 7 figs, 1 tab

Magnetic and Superconducting Materials at High Pressures

Energy Technology Data Exchange (ETDEWEB)

Struzhkin, Viktor V. [Carnegie Inst. of Washington, Washington, DC (United States)

2015-03-24

The work concentrates on few important tasks in enabling techniques for search of superconducting compressed hydrogen compounds and pure hydrogen, investigation of mechanisms of high-Tc superconductivity, and exploring new superconducting materials. Along that route we performed several challenging tasks, including discovery of new forms of polyhydrides of alkali metal Na at very high pressures. These experiments help us to establish the experimental environment that will provide important information on the high-pressure properties of hydrogen-rich compounds. Our recent progress in RIXS measurements opens a whole field of strongly correlated 3d materials. We have developed a systematic approach to measure major electronic parameters, like Hubbard energy U, and charge transfer energy Δ, as function of pressure. This technique will enable also RIXS studies of magnetic excitations in iridates and other 5d materials at the L edge, which attract a lot of interest recently. We have developed new magnetic sensing technique based on optically detected magnetic resonance from NV centers in diamond. The technique can be applied to study superconductivity in high-TC materials, to search for magnetic transitions in strongly correlated and itinerant magnetic materials under pressure. Summary of Project Activities; development of high-pressure experimentation platform for exploration of new potential superconductors, metal polyhydrides (including newly discovered alkali metal polyhydrides), and already known superconductors at the limit of static high-pressure techniques; investigation of special classes of superconducting compounds (high-Tc superconductors, new superconducting materials), that may provide new fundamental knowledge and may prove important for application as high-temperature/high-critical parameter superconductors; investigation of the pressure dependence of superconductivity and magnetic/phase transformations in 3d transition metal compounds, including

Initial boundary-value problem for the spherically symmetric Einstein equations with fluids with tangential pressure.

Science.gov (United States)

Brito, Irene; Mena, Filipe C

2017-08-01

We prove that, for a given spherically symmetric fluid distribution with tangential pressure on an initial space-like hypersurface with a time-like boundary, there exists a unique, local in time solution to the Einstein equations in a neighbourhood of the boundary. As an application, we consider a particular elastic fluid interior matched to a vacuum exterior.

Correlations for modeling transitional boundary layers under influences of freestream turbulence and pressure gradient

International Nuclear Information System (INIS)

Suluksna, Keerati; Dechaumphai, Pramote; Juntasaro, Ekachai

2009-01-01

This paper presents mathematical expressions for two significant parameters which control the onset location and length of transition in the γ-Re θ transition model of Menter et al. [Menter, F.R., Langtry, R.B., Volker, S., Huang, P.G., 2005. Transition modelling for general purpose CFD codes. In: ERCOFTAC International Symposium on Engineering Turbulence Modelling and Measurements]. The expressions are formulated and calibrated by means of numerical experiments for predicting transitional boundary layers under the influences of freestream turbulence and pressure gradient. It was also found that the correlation for transition momentum thickness Reynolds number needs only to be expressed in terms of local turbulence intensity, so that the more complex form that includes pressure gradient effects is unnecessary. Transitional boundary layers on a flat plate both with and without pressure gradients are employed to assess the performance of these two expressions for predicting the transition. The results show that the proposed expressions can work well with the model of Menter et al. (2005)

Direct numerical simulation of thermally-stratified turbulent boundary layer subjected to adverse pressure gradient

International Nuclear Information System (INIS)

Hattori, Hirofumi; Kono, Amane; Houra, Tomoya

2016-01-01

Highlights: • We study various thermally-stratified turbulent boundary layers having adverse pressure gradient (APG) by means of DNS. • The detailed turbulent statistics and structures in various thermally-stratified turbulent boundary layers having APG are discussed. • It is found that the friction coefficient and Stanton number decrease along the streamwise direction due to the effects of stable thermal stratification and APG, but those again increase due to the APG effect in the case of weak stable thermal stratification. • In the case of strong stable stratification with or without APG, the flow separation is observed in the downstream region. - Abstract: The objective of this study is to investigate and observe turbulent heat transfer structures and statistics in thermally-stratified turbulent boundary layers subjected to a non-equilibrium adverse pressure gradient (APG) by means of direct numerical simulation (DNS). DNSs are carried out under conditions of neutral, stable and unstable thermal stratifications with a non-equilibrium APG, in which DNS results reveal heat transfer characteristics of thermally-stratified non-equilibrium APG turbulent boundary layers. In cases of thermally-stratified turbulent boundary layers affected by APG, heat transfer performances increase in comparison with a turbulent boundary layer with neutral thermal stratification and zero pressure gradient (ZPG). Especially, it is found that the friction coefficient and Stanton number decrease along the streamwise direction due to the effects of stable thermal stratification and APG, but those again increase due to the APG effect in the case of weak stable thermal stratification (WSBL). Thus, the analysis for both the friction coefficient and Stanton number in the case of WSBL with/without APG is conducted using the FIK identity in order to investigate contributions from the transport equations, in which it is found that both Reynolds-shear-stress and the mean convection terms

Pressure and tension waves from bubble collapse near a solid boundary: A numerical approach.

Science.gov (United States)

Lechner, Christiane; Koch, Max; Lauterborn, Werner; Mettin, Robert

2017-12-01

The acoustic waves being generated during the motion of a bubble in water near a solid boundary are calculated numerically. The open source package OpenFOAM is used for solving the Navier-Stokes equation and extended to include nonlinear acoustic wave effects via the Tait equation for water. A bubble model with a small amount of gas is chosen, the gas obeying an adiabatic law. A bubble starting from a small size with high internal pressure near a flat, solid boundary is studied. The sequence of events from bubble growth via axial microjet formation, jet impact, annular nanojet formation, torus-bubble collapse, and bubble rebound to second collapse is described. The different pressure and tension waves with their propagation properties are demonstrated.

Aging of elastomers in CANDU pressure boundary service

International Nuclear Information System (INIS)

VanBerlo, C.; Leidner, J.

1987-09-01

This report describes the properties and aging of elastomers, and examines the performance of major elastomeric components in CANDU pressure boundary service. The components examined are vacuum building roof seals, pressure relief duct seals, airlock door seals, fuelling machine hoses, and cable penetrations. For each of these components, the design requirements, technical specifications and component testing procedures are compared with applicable standards. Information on actual and recommended monitoring and maintenance methods is presented. Operational and environmental stressors are identified. Component failure modes, causes and frequencies are described, as well as the remedial action taken. Many different elastomers are used in CANDU plants, for many different applications. Standards and manufacturers' recommendations are not consistent and may vary from one component to another. Accordingly, the monitoring, maintenance and replacement practices tend to vary from one application to another, and may also be different at different stations. Recommendations are given in this report for improved monitoring and maintenance, in an attempt to provide more consistency in approach. A summary of some experiences with elastomers from non-Canadian sources is contained in the last section. 125 refs

Role of non destructive techniques for monitoring structural integrity of primary circuit of pressurized water reactor nuclear power plant

International Nuclear Information System (INIS)

Sharma, P.K.; Sreenivas, P.

2015-01-01

The safety of nuclear installations is ensured by assessing status of primary equipment for performing the intended function reliably and maintaining the integrity of pressure boundaries. The pressure boundary materials undergo material degradation during the plant operation. Pressure boundary materials are subjected to operating stresses and material degradation that results in material properties changes, discontinuities initiation and increase in size of existing discontinuities. Pre-Service Inspection (PSI) is performed to generate reference base line data of initial condition of the pressure boundary. In-Service Inspections (ISI) are performed periodically to confirm integrity of pressure boundaries through comparison with respect to base line data. The non destructive techniques are deployed considering nature of the discontinuities expected to be generated through operating conditions and degradation mechanisms. The paper is prepared considering Pressurized Water Reactor (PWR) Nuclear Power Plant. The paper describes the degradation mechanisms observed in the PWR nuclear power plants and salient aspect of PSI and ISI and considerations in selecting non destructive testing. The paper also emphasises on application of acoustic emission (AE) based condition monitoring systems that can supplement in-service inspections for detecting and locating discontinuities in pressure boundaries. Criticality of flaws can be quantitatively evaluated by determining their size through in-service inspection. Challenges anticipated in deployment of AE based monitoring system and solutions to cater those challenges are also discussed. (author)

Local characteristics of the nocturnal boundary layer in response to external pressure forcing

NARCIS (Netherlands)

van der Linden, S.J.A.; Baas, P.; van Hooft, J.A.; van Hooijdonk, I.G.S.; Bosveld, F.C.; van de Wiel, B.J.H.

2017-01-01

Geostrophic wind speed data, derived from pressure observations, are used in combination with tower measurements to investigate the nocturnal stable boundary layer at Cabauw (The Netherlands). Since the geostrophic wind speed is not directly influenced by local nocturnal stability, it may be

The online sealing performance test of the primary circuit pressure boundary check valve in nuclear power plants

International Nuclear Information System (INIS)

Yang Yunfei; Huang Huimin

2013-01-01

The primary circuit pressure boundary check valves of 320 MW pressurized water reactor is a nuclear grade I key equipment. The sealing demand is very high, which is directly related to the internal leakage rate of the primary circuit system. After the welding check valve is repaired, the sealing performance is judged by color printing checks. If there is water or humid vapor in the pipe, it will affect the accuracy of the color printing checks. For the particularity of the online check valve tightness test, online detecting device is designed by the hydraulic pressure drop method in other nuclear power plants, but the method has some shortcomings and restrictions. In this paper, we design a reliable and portable test equipment by the low-pressure gas seal test flow measurement, which make accurate and quantitative judgment of sealing property after the pressure boundary check valves are repaired. (authors)

An optimal control method for fluid structure interaction systems via adjoint boundary pressure

Science.gov (United States)

Chirco, L.; Da Vià, R.; Manservisi, S.

2017-11-01

In recent year, in spite of the computational complexity, Fluid-structure interaction (FSI) problems have been widely studied due to their applicability in science and engineering. Fluid-structure interaction systems consist of one or more solid structures that deform by interacting with a surrounding fluid flow. FSI simulations evaluate the tensional state of the mechanical component and take into account the effects of the solid deformations on the motion of the interior fluids. The inverse FSI problem can be described as the achievement of a certain objective by changing some design parameters such as forces, boundary conditions and geometrical domain shapes. In this paper we would like to study the inverse FSI problem by using an optimal control approach. In particular we propose a pressure boundary optimal control method based on Lagrangian multipliers and adjoint variables. The objective is the minimization of a solid domain displacement matching functional obtained by finding the optimal pressure on the inlet boundary. The optimality system is derived from the first order necessary conditions by taking the Fréchet derivatives of the Lagrangian with respect to all the variables involved. The optimal solution is then obtained through a standard steepest descent algorithm applied to the optimality system. The approach presented in this work is general and could be used to assess other objective functionals and controls. In order to support the proposed approach we perform a few numerical tests where the fluid pressure on the domain inlet controls the displacement that occurs in a well defined region of the solid domain.

Automatic kinetic Monte-Carlo modeling for impurity atom diffusion in grain boundary structure of tungsten material

Directory of Open Access Journals (Sweden)

Atsushi M. Ito

2017-08-01

Full Text Available The diffusion process of hydrogen and helium in plasma-facing material depends on the grain boundary structures. Whether a grain boundary accelerates or limits the diffusion speed of these impurity atoms is not well understood. In the present work, we proposed the automatic modeling of a kinetic Monte-Carlo (KMC simulation to treat an asymmetric grain boundary structure that corresponds to target samples used in fusion material experiments for retention and permeation. In this method, local minimum energy sites and migration paths for impurity atoms in the grain boundary structure are automatically found using localized molecular dynamics. The grain boundary structure was generated with the Voronoi diagram. Consequently, we demonstrate that the KMC simulation for the diffusion process of impurity atoms in the generated grain boundary structure of tungsten material can be performed.

Materials and fabrication requirements for APWR systems

International Nuclear Information System (INIS)

Boothby, R.M.; Hippsley, C.A.; Gorton, O.K.; Garwood, S.J.

1995-01-01

Materials specifications for advanced pressurized water-cooled reactor (APWR) systems are generally based on existing designs, with improved materials and fabrication procedures being developed to counter known degradation effects. In this paper, materials ageing and degradation mechanisms in PWR primary circuit pressure boundary components (i.e. the reactor pressure vessel (RPV), control rod drive mechanisms (CRDMs), coolant piping, coolant pump casing, pressurizer, and steam generators) are reviewed. Important degradation mechanisms include irradiation embrittlement of the RPV, thermal ageing embrittlement of ferritic (e.g. the pressurizer) and cast austenitic (e.g. coolant pump casing and pipe elbows) steel components and environmentally assisted cracking of steam generator tubing and CRDM penetrations. Improved materials specifications and component design and fabrication issues affecting the integrity of the pressure boundary are discussed in the light of these materials problems. Improved fabrication procedures adopted for Sizewell B, such as the utilization of ring forgings to eliminate axial welds in the RPV and steam generator shells and the use of one-piece castings for coolant pump casings, provide a benchmark against which other APWR designs may be judged. (author)

Flexible Composite-Material Pressure Vessel

Science.gov (United States)

Brown, Glen; Haggard, Roy; Harris, Paul A.

2003-01-01

A proposed lightweight pressure vessel would be made of a composite of high-tenacity continuous fibers and a flexible matrix material. The flexibility of this pressure vessel would render it (1) compactly stowable for transport and (2) more able to withstand impacts, relative to lightweight pressure vessels made of rigid composite materials. The vessel would be designed as a structural shell wherein the fibers would be predominantly bias-oriented, the orientations being optimized to make the fibers bear the tensile loads in the structure. Such efficient use of tension-bearing fibers would minimize or eliminate the need for stitching and fill (weft) fibers for strength. The vessel could be fabricated by techniques adapted from filament winding of prior composite-material vessels, perhaps in conjunction with the use of dry film adhesives. In addition to the high-bias main-body substructure described above, the vessel would include a low-bias end substructure to complete coverage and react peak loads. Axial elements would be overlaid to contain damage and to control fiber orientation around side openings. Fiber ring structures would be used as interfaces for connection to ancillary hardware.

MDEP Technical Report TR-CSWG-02. Technical Report on Lessons Learnt on Achieving Harmonisation of Codes and Standards for Pressure Boundary Components in Nuclear Power Plants

International Nuclear Information System (INIS)

2013-01-01

This report was prepared by the Multinational Design Evaluation Program's (MDEP's) Codes and Standards Working Group (CSWG). The primary, long-term goal of MDEP's CSWG is to achieve international harmonisation of codes and standards for pressure-boundary components in nuclear power plants. The CSWG recognised early on that the first step to achieving harmonisation is to understand the extent of similarities and differences amongst the pressure-boundary codes and standards used in various countries. To assist the CSWG in its long-term goals, several standards developing organisations (SDOs) from various countries performed a comparison of their pressure-boundary codes and standards to identify the extent of similarities and differences in code requirements and the reasons for their differences. The results of the code-comparison project provided the CSWG with valuable insights in developing the subsequent actions to take with SDOs and the nuclear industry to pursue harmonisation of codes and standards. The results enabled the CSWG to understand from a global perspective how each country's pressure-boundary code or standard evolved into its current form and content. The CSWG recognised the important fact that each country's pressure-boundary code or standard is a comprehensive, living document that is continually being updated and improved to reflect changing technology and common industry practices unique to each country. The rules in the pressure-boundary codes and standards include comprehensive requirements for the design and construction of nuclear power plant components including design, materials selection, fabrication, examination, testing and overpressure protection. The rules also contain programmatic and administrative requirements such as quality assurance; conformity assessment (e.g., third-party inspection); qualification of welders, welding equipment and welding procedures; non-destructive examination (NDE) practices and

Structure and properties of fluid-filled grain boundaries under stress in geological materials. Geologica Ultraiectina (290)

NARCIS (Netherlands)

van Noort, R.

2008-01-01

Two of the three processes making up the deformation mechanism of intergranular pressure solution, being dissolution and diffusion, take place in the grain boundary fluid phase. Hence, the structure and physical properties of wet grain boundaries under stress can be expected to influence the

Two-dimensional properties of n-inversion layers in InSb grain boundaries under high hydrostatic pressure

International Nuclear Information System (INIS)

Kraak, W.; Herrmann, R.; Nachtwei, G.

1985-01-01

Magnetotransport properties of n-inversion layers in grain boundaries of p-InSb bicrystals are investigated under high hydrostatic pressure up to 10 3 MPa. A rapid decrease of the carrier concentration in the inversion layer is observed when hydrostatic pressure is applied. A simple model taking into account the pressure dependence of the energy band structure of pure InSb is proposed to describe this behaviour. (author)

Grain-boundary engineering applied to grain growth in a high temperature material

International Nuclear Information System (INIS)

Huda, Z.

1993-01-01

Crystallography of grain boundaries are determined for a high temperature material, before and after grain growth processes, so as to study the induction of special properties useful for application in components of a gas-turbine engine. The philosophy of grain-boundary engineering is applied to grain growth in APK-6, a powder formed nickel-base superalloy so as to establish the possible structure/property relationships. The alloy in the as received condition is shown to possess a strong texture and contained coincident site lattices (CSL) boundaries with most boundaries having sigma values in the range of 3 > sigma > 25. A normal grain-growth heat treatment result in a good population of low angle grain boundaries, and drastically reduces the proportion of CSL boundaries. A strong [011] annealing texture is observed after an intermediate grain growth; most grain boundaries, here, tend to be high angle indicating a possibility of possessing special properties. (author)

Computerized reactor pressure vessel materials information system

International Nuclear Information System (INIS)

Strosnider, J.; Monserrate, C.; Kenworthy, L.D.; Tether, C.D.

1980-10-01

A computerized information system for storage and retrieval of reactor pressure vessel materials data was established, as part of Task Action Plan A-11, Reactor Vessel Materials Toughness. Data stored in the system are necessary for evaluating the resistance of reactor pressure vessels to flaw-induced fracture. This report includes (1) a description of the information system; (2) guidance on accessing the system; and (3) a user's manual for the system

Instability waves and transition in adverse-pressure-gradient boundary layers

Science.gov (United States)

Bose, Rikhi; Zaki, Tamer A.; Durbin, Paul A.

2018-05-01

Transition to turbulence in incompressible adverse-pressure-gradient (APG) boundary layers is investigated by direct numerical simulations. Purely two-dimensional instability waves develop on the inflectional base velocity profile. When the boundary layer is perturbed by isotropic turbulence from the free stream, streamwise elongated streaks form and may interact with the instability waves. Subsequent mechanisms that trigger transition depend on the intensity of the free-stream disturbances. All evidence from the present simulations suggest that the growth rate of instability waves is sufficiently high to couple with the streaks. Under very low levels of free-stream turbulence (˜0.1 % ), transition onset is highly sensitive to the inlet disturbance spectrum and is accelerated if the spectrum contains frequency-wave-number combinations that are commensurate with the instability waves. Transition onset and completion in this regime is characterized by formation and breakdown of Λ vortices, but they are more sporadic than in natural transition. Beneath free-stream turbulence with higher intensity (1-2 % ), bypass transition mechanisms are dominant, but instability waves are still the most dominant disturbances in wall-normal and spanwise perturbation spectra. Most of the breakdowns were by disturbances with critical layers close to the wall, corresponding to inner modes. On the other hand, the propensity of an outer mode to occur increases with the free-stream turbulence level. Higher intensity free-stream disturbances induce strong streaks that favorably distort the boundary layer and suppress the growth of instability waves. But the upward displacement of high amplitude streaks brings them to the outer edge of the boundary layer and exposes them to ambient turbulence. Consequently, high-amplitude streaks exhibit an outer-mode secondary instability.

Implicit Large-Eddy Simulations of Zero-Pressure Gradient, Turbulent Boundary Layer

Science.gov (United States)

Sekhar, Susheel; Mansour, Nagi N.

2015-01-01

A set of direct simulations of zero-pressure gradient, turbulent boundary layer flows are conducted using various span widths (62-630 wall units), to document their influence on the generated turbulence. The FDL3DI code that solves compressible Navier-Stokes equations using high-order compact-difference scheme and filter, with the standard recycling/rescaling method of turbulence generation, is used. Results are analyzed at two different Re values (500 and 1,400), and compared with spectral DNS data. They show that a minimum span width is required for the mere initiation of numerical turbulence. Narrower domains ((is) less than 100 w.u.) result in relaminarization. Wider spans ((is) greater than 600 w.u.) are required for the turbulent statistics to match reference DNS. The upper-wall boundary condition for this setup spawns marginal deviations in the mean velocity and Reynolds stress profiles, particularly in the buffer region.

DEM Simulation of Biaxial Compression Experiments of Inherently Anisotropic Granular Materials and the Boundary Effects

Directory of Open Access Journals (Sweden)

Zhao-Xia Tong

2013-01-01

Full Text Available The reliability of discrete element method (DEM numerical simulations is significantly dependent on the particle-scale parameters and boundary conditions. To verify the DEM models, two series of biaxial compression tests on ellipse-shaped steel rods are used. The comparisons on the stress-strain relationship, strength, and deformation pattern of experiments and simulations indicate that the DEM models are able to capture the key macro- and micromechanical behavior of inherently anisotropic granular materials with high fidelity. By using the validated DEM models, the boundary effects on the macrodeformation, strain localization, and nonuniformity of stress distribution inside the specimens are investigated using two rigid boundaries and one flexible boundary. The results demonstrate that the boundary condition plays a significant role on the stress-strain relationship and strength of granular materials with inherent fabric anisotropy if the stresses are calculated by the force applied on the wall. However, the responses of the particle assembly measured inside the specimens are almost the same with little influence from the boundary conditions. The peak friction angle obtained from the compression tests with flexible boundary represents the real friction angle of particle assembly. Due to the weak lateral constraints, the degree of stress nonuniformity under flexible boundary is higher than that under rigid boundary.

Active Brownian particles near straight or curved walls: Pressure and boundary layers

Science.gov (United States)

Duzgun, Ayhan; Selinger, Jonathan V.

2018-03-01

Unlike equilibrium systems, active matter is not governed by the conventional laws of thermodynamics. Through a series of analytic calculations and Langevin dynamics simulations, we explore how systems cross over from equilibrium to active behavior as the activity is increased. In particular, we calculate the profiles of density and orientational order near straight or circular walls and show the characteristic width of the boundary layers. We find a simple relationship between the enhancements of density and pressure near a wall. Based on these results, we determine how the pressure depends on wall curvature and hence make approximate analytic predictions for the motion of curved tracers, as well as the rectification of active particles around small openings in confined geometries.

Formation of a Boundary-Free Dust Cluster in a Low-Pressure Gas-Discharge Plasma

International Nuclear Information System (INIS)

Usachev, A. D.; Zobnin, A. V.; Petrov, O. F.; Fortov, V. E.; Annaratone, B. M.; Thoma, M. H.; Hoefner, H.; Kretschmer, M.; Fink, M.; Morfill, G. E.

2009-01-01

An attraction between negatively charged micron-sized plastic particles was observed in the bulk of a low-pressure gas-discharge plasma under microgravity conditions. This attraction had led to the formation of a boundary-free dust cluster, containing one big central particle with a radius of about 6 μm and about 30 1 μm-sized particles situated on a sphere with a radius of 190 μm and with the big particle in the center. The stability of this boundary-free dust cluster was possible due to its confinement by the plasma flux on the central dust particle

Development of technology on the material surveillance of CANDU pressure tubes

Energy Technology Data Exchange (ETDEWEB)

Noh, Kye Hoh; Han, Jung Hoh; Lee, Duk Hyun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1995-05-01

Material degradation of pressure tubes, which are the most important components in CANDU fuel channel, can only be evaluated by removing and examining them(material surveillance). This study aimed at establishment of overall evaluation technology including the evaluation of the material degradation for the integrity of pressure tubes of Wolsung units. Material tests for pressure tubes were performed as follows; (1) Evaluation on life limiting factors of pressure tubes (2) Review on leak-before-break and integrity maintenance technology of pressure tubes (3) Survey on selection criteria for tubes to be inspected and on related regulations for material surveillance (4) Analysis of material surveillance test procedure (5) Basic examinations of Wolsung unit 1 pressure tube material(TEM, texture, chemical component etc) (6) Manufacture of test equipments and test (DHCV, hydriding, grip and tensile specimen etc). 23 figs, 6 tabs, 59 refs. (Author).

Development of technology on the material surveillance of CANDU pressure tubes

International Nuclear Information System (INIS)

Noh, Kye Hoh; Han, Jung Hoh; Lee, Duk Hyun

1995-05-01

Material degradation of pressure tubes, which are the most important components in CANDU fuel channel, can only be evaluated by removing and examining them(material surveillance). This study aimed at establishment of overall evaluation technology including the evaluation of the material degradation for the integrity of pressure tubes of Wolsung units. Material tests for pressure tubes were performed as follows; (1) Evaluation on life limiting factors of pressure tubes (2) Review on leak-before-break and integrity maintenance technology of pressure tubes (3) Survey on selection criteria for tubes to be inspected and on related regulations for material surveillance (4) Analysis of material surveillance test procedure (5) Basic examinations of Wolsung unit 1 pressure tube material(TEM, texture, chemical component etc) (6) Manufacture of test equipments and test (DHCV, hydriding, grip and tensile specimen etc). 23 figs, 6 tabs, 59 refs. (Author)

Structural mechanisms of the flux effect for VVER-1000 reactor pressure vessel materials

International Nuclear Information System (INIS)

Gurovich, B.; Kuleshova, E.; Fedotova, S.; Maltsev, D.; Zabusov, O.; Frolov, A.; Erak, D.; Zhurko, D.

2015-01-01

To justify the lifetime extension of VVER-1000 reactor pressure vessels (RPV) up to 60 years and more it is necessary to expand the existing surveillance samples database to beyond design fluence by means of accelerated irradiation in a research reactor. Herewith since the changes in mechanical properties of materials under irradiation are due to occurring structural changes, correct analysis of the data obtained at accelerated irradiation of VVER-1000 RPV materials requires a clear understanding of the structural mechanisms that are responsible for the flux effect in VVER-1000 RPV steels. Two mechanisms are responsible for radiation embrittlement of VVER-1000 RPV steels: the hardening one (radiation hardening due to formation of radiation-induced Ni-based precipitates and radiation defects) and non-hardening one (due to formation of impurities segregations at grain boundaries - reversible temper brittleness). In this context for an adequate interpretation of the mechanical tests results when justifying the lifetime extension of existing units a complex of comparative structural studies (TEM, SEM and AES) of VVER-1000 RPV materials irradiated in different conditions (in research reactor IR-8 and within surveillance samples) was performed. It is shown that the flux effect is observed for materials with high nickel content (weld metals with Ni content > 1.35%) and it is mostly due to the contribution of non-hardening mechanism of radiation embrittlement (the difference in the accumulation kinetics of grain boundary phosphorus segregation) and somewhat contribution of the hardening mechanism (the difference in density of radiation-induced precipitates). Therefore when analyzing the results obtained from the accelerated irradiation of VVER-1000 WM the correction for the flux effect should be made. (authors)

The structure of a three-dimensional boundary layer subjected to streamwise-varying spanwise-homogeneous pressure gradient

International Nuclear Information System (INIS)

Bentaleb, Y.; Leschziner, M.A.

2013-01-01

Highlights: • We study a spatially-evolving three-dimensional boundary layer. • We impose a streamwise-varying spanwise-homogeneous pressure gradient. • A collateral flow is formed close to the wall, and this is investigated alongside the skewed upper part of the boundary layer. • A wide range of flow-physical properties have been studied. -- Abstract: A spatially-evolving three-dimensional boundary layer, subjected to a streamwise-varying spanwise-homogeneous pressure gradient, equivalent to a body force, is investigated by way of direct numerical simulation. The pressure gradient, prescribed to change its sign half-way along the boundary layer, provokes strong skewing of the velocity vector, with a layer of nearly collateral flow forming close to the wall up to the position of maximum spanwise velocity. A wide range of flow-physical properties have been studied, with particular emphasis on the near-wall layer, including second-moments, major budget contributions and wall-normal two-point correlations of velocity fluctuations and their angles, relative to wall-shear fluctuations. The results illustrate the complexity caused by skewing, including a damping in turbulent mixing and a significant lag between strains and stresses. The study has been undertaken in the context of efforts to develop and test novel hybrid LES–RANS schemes for non-equilibrium near-wall flows, with an emphasis on three-dimensional near-wall straining. Fundamental flow-physical issues aside, the data derived should be of particular relevance to a priori studies of second-moment RANS closure and the development and validation of RANS-type near-wall approximations implemented in LES schemes for high-Reynolds-number complex flows

Free-boundary Full-pressure Island Healing in a Stellarator: Coil-healing

International Nuclear Information System (INIS)

Hudson, S.R.; Reiman, A.; Strickler, D.; Brooks, A.; Monticello, D.A.; Hirshman, S.P.

2002-01-01

The lack of axisymmetry in stellarators guarantees that in general magnetic islands and chaotic magnetic field lines will exist. As particle transport is strongly tied to the magnetic field lines, magnetic islands and chaotic field lines result in poor plasma confinement. For stellarators to be feasible candidates for fusion power stations it is essential that, to a good approximation, the magnetic field lines lie on nested flux-surfaces, and the suppression of magnetic islands is a critical issue for stellarator coil design, particularly for small aspect ratio devices. A procedure for modifying stellarator coil designs to eliminate magnetic islands in free-boundary full-pressure magnetohydrodynamic equilibria is presented. Islands may be removed from coil-plasma free-boundary equilibria by making small changes to the coil geometry and also by variation of trim coil currents. A plasma and coil design relevant to the National Compact Stellarator Experiment is used to illustrate the technique

Influence of nano-inclusions' grain boundaries on crack propagation modes in materials

International Nuclear Information System (INIS)

Karakasidis, T.E.; Charitidis, C.A.

2011-01-01

The effect of nano-inclusions on materials' strength and toughness has attracted great interest in recent years. It has been shown that tuning the morphological and microstructural features of materials can tailor their fracture modes. The existence of a characteristic size of inclusions that favours the fracture mode (i.e. transgranular or intergranular) has been experimentally observed but also predicted by a 2D model based on energetic arguments which relates the crack propagation mode to the ratio of the interface area between the crystalline inclusion and the matrix with the area of the crystallite inclusion in a previous work. In the present work, a 3D model is proposed in order to extend the 2D model and take into account the influence of the size of grain boundary zone on the toughening/hardening behavior of the material as it was observed experimentally in the literature. The model relates crack propagation mode to the ratio of the volume of the grain boundary zone between the crystalline inclusion and the matrix with the volume of the nano-inclusion. For a ratio below a critical value, transgranular propagation is favoured while for larger values, intergranular propagation is favoured. We also demonstrate that the extent of the grain boundary region also can significantly affect this critical value. The results of the model are in agreement with the literature experimental observations related to the toughening/hardening behavior as a function of the size of crystalline inclusions as well as the width of the grain boundary regions.

High-pressure on f-element materials

International Nuclear Information System (INIS)

Haire, R.G.

1991-01-01

540Studies of the f-elements under pressure provide important insights into their solid state chemistry and physics. From such studies of the elements and their alloys, it has been established that the normally localized f-electrons of several of these elements can become involved in bonding under pressure. The electronic behavior of f-element compounds under pressure tend to be more difficult to interpret, due to the variety and the nature of electronic orbitals that are present. The 4f-elements and some 60% of the 5f-elements have been studied under pressure. The systematic comparisons that have been established for these materials are discussed. 76 refs., 3 figs

Analysis of Numerical Simulation Database for Pressure Fluctuations Induced by High-Speed Turbulent Boundary Layers

Science.gov (United States)

Duan, Lian; Choudhari, Meelan M.

2014-01-01

Direct numerical simulations (DNS) of Mach 6 turbulent boundary layer with nominal freestream Mach number of 6 and Reynolds number of Re(sub T) approximately 460 are conducted at two wall temperatures (Tw/Tr = 0.25, 0.76) to investigate the generated pressure fluctuations and their dependence on wall temperature. Simulations indicate that the influence of wall temperature on pressure fluctuations is largely limited to the near-wall region, with the characteristics of wall-pressure fluctuations showing a strong temperature dependence. Wall temperature has little influence on the propagation speed of the freestream pressure signal. The freestream radiation intensity compares well between wall-temperature cases when normalized by the local wall shear; the propagation speed of the freestream pressure signal and the orientation of the radiation wave front show little dependence on the wall temperature.

Study of Boundary Layer Convective Heat Transfer with Low Pressure Gradient Over a Flat Plate Via He's Homotopy Perturbation Method

International Nuclear Information System (INIS)

Fathizadeh, M.; Aroujalian, A.

2012-01-01

The boundary layer convective heat transfer equations with low pressure gradient over a flat plate are solved using Homotopy Perturbation Method, which is one of the semi-exact methods. The nonlinear equations of momentum and energy solved simultaneously via Homotopy Perturbation Method are in good agreement with results obtained from numerical methods. Using this method, a general equation in terms of Pr number and pressure gradient (λ) is derived which can be used to investigate velocity and temperature profiles in the boundary layer.

Reynolds stress structures in a self-similar adverse pressure gradient turbulent boundary layer at the verge of separation.

Science.gov (United States)

Atkinson, C.; Sekimoto, A.; Jiménez, J.; Soria, J.

2018-04-01

Mean Reynolds stress profiles and instantaneous Reynolds stress structures are investigated in a self-similar adverse pressure gradient turbulent boundary layer (APG-TBL) at the verge of separation using data from direct numerical simulations. The use of a self-similar APG-TBL provides a flow domain in which the flow gradually approaches a constant non-dimensional pressure gradient, resulting in a flow in which the relative contribution of each term in the governing equations is independent of streamwise position over a domain larger than two boundary layer thickness. This allows the flow structures to undergo a development that is less dependent on the upstream flow history when compared to more rapidly decelerated boundary layers. This APG-TBL maintains an almost constant shape factor of H = 2.3 to 2.35 over a momentum thickness based Reynolds number range of Re δ 2 = 8420 to 12400. In the APG-TBL the production of turbulent kinetic energy is still mostly due to the correlation of streamwise and wall-normal fluctuations, 〈uv〉, however the contribution form the other components of the Reynolds stress tensor are no longer negligible. Statistical properties associated with the scale and location of sweeps and ejections in this APG-TBL are compared with those of a zero pressure gradient turbulent boundary layer developing from the same inlet profile, resulting in momentum thickness based range of Re δ 2 = 3400 to 3770. In the APG-TBL the peak in both the mean Reynolds stress and the production of turbulent kinetic energy move from the near wall region out to a point consistent with the displacement thickness height. This is associated with a narrower distribution of the Reynolds stress and a 1.6 times higher relative number of wall-detached negative uv structures. These structures occupy 5 times less of the boundary layer volume and show a similar reduction in their streamwise extent with respect to the boundary layer thickness. A significantly lower percentage

Pressure hydrogenation of solid carbonaceous material

Energy Technology Data Exchange (ETDEWEB)

Pier, M; Kroenig, W

1942-09-28

A process is described for the continuous pressure hydrogenation of solid, nonfusible carbonaceous material, such as coal, oil shale, or peat, in a pasted condition, characterized in that the charge is heated in a known way under pressure, together with water, nearly to the reaction temperature, then it is led into a pressure vessel, whose volume amounts to 20 to 40% of the usual reaction space without any change at the same temperature, and the charge then goes through the reaction vessel, after which its temperature is raised to the reaction height.

Interaction between a normal shock wave and a turbulent boundary layer at high transonic speeds. I - Pressure distribution

Science.gov (United States)

Messiter, A. F.

1980-01-01

Asymptotic solutions are derived for the pressure distribution in the interaction of a weak normal shock wave with a turbulent boundary layer. The undisturbed boundary layer is characterized by the law of the wall and the law of the wake for compressible flow. In the limiting case considered, for 'high' transonic speeds, the sonic line is very close to the wall. Comparisons with experiment are shown, with corrections included for the effect of longitudinal wall curvature and for the boundary-layer displacement effect in a circular pipe.

A preliminary investigation of boundary-layer transition along a flat plate with adverse pressure gradient

Science.gov (United States)

Von Doenhoff, Albert E

1938-01-01

Boundary-layer surveys were made throughout the transition region along a smooth flat plate placed in an airstream of practically zero turbulence and with an adverse pressure gradient. The boundary-layer Reynolds number at the laminar separation point was varied from 1,800 to 2,600. The test data, when considered in the light of certain theoretical deductions, indicated that transition probably began with separation of the laminar boundary layer. The extent of the transition region, defined as the distance from a calculated laminar separation point to the position of the first fully developed turbulent boundary-layer profile, could be expressed as a constant Reynolds number run of approximately 70,000. Some speculations are presented concerning the application of the foregoing concepts, after certain assumptions have been made, to the problem of the connection between transition on the upper surface of an airfoil at high angles of attack and the maximum lift.

Derivation of Zagarola-Smits scaling in zero-pressure-gradient turbulent boundary layers

Science.gov (United States)

Wei, Tie; Maciel, Yvan

2018-01-01

This Rapid Communication derives the Zagarola-Smits scaling directly from the governing equations for zero-pressure-gradient turbulent boundary layers (ZPG TBLs). It has long been observed that the scaling of the mean streamwise velocity in turbulent boundary layer flows differs in the near surface region and in the outer layer. In the inner region of small-velocity-defect boundary layers, it is generally accepted that the proper velocity scale is the friction velocity, uτ, and the proper length scale is the viscous length scale, ν /uτ . In the outer region, the most generally used length scale is the boundary layer thickness, δ . However, there is no consensus on velocity scales in the outer layer. Zagarola and Smits [ASME Paper No. FEDSM98-4950 (1998)] proposed a velocity scale, U ZS=(δ1/δ ) U∞ , where δ1 is the displacement thickness and U∞ is the freestream velocity. However, there are some concerns about Zagarola-Smits scaling due to the lack of a theoretical base. In this paper, the Zagarola-Smits scaling is derived directly from a combination of integral, similarity, and order-of-magnitude analysis of the mean continuity equation. The analysis also reveals that V∞, the mean wall-normal velocity at the edge of the boundary layer, is a proper scale for the mean wall-normal velocity V . Extending the analysis to the streamwise mean momentum equation, we find that the Reynolds shear stress in ZPG TBLs scales as U∞V∞ in the outer region. This paper also provides a detailed analysis of the mass and mean momentum balance in the outer region of ZPG TBLs.

Intergranular and inter-phased boundaries in the materials; Joints intergranulaires et interphases dans les materiaux

Energy Technology Data Exchange (ETDEWEB)

Aslanides, A. [Electricite de France, Dept. CIMA, 77 - Moret sur Loing (France); Backhaus-Ricoult, M. [Centre d' Etudes de Chimie metallurgique, 94 - Vitry-sur-Seine (France); Bayle-Guillemaud, P. [CEA Grenoble, Dept. de Recherche Fondamentale sur la Matiere Condensee, 38 (France)] [and others

2000-07-01

This document collects the abstracts of the talks presented during the colloquium J2IM on the intergranular and inter-phased boundaries in the materials. Around the themes of the interfaces behaviour and grain boundaries defects in materials, these days dealt with the microstructure behaviour in many domains such as the interfaces in batteries, the irradiation damages and the special case of the fuel-cladding interactions, the stressed interfaces, the alumina or silicon carbides substrates. (A.L.B.)

Grain Boundary Segregation in Metals

CERN Document Server

Lejcek, Pavel

2010-01-01

Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.

On the rutile alpha-PbO"2-type phase boundary of TiO"2

DEFF Research Database (Denmark)

Olsen, J.S.; Gerward, Leif; Jiang, Jianzhong

1999-01-01

The high-pressure, high-temperature phase quilibria of TiO"2 have been studied with special emphasis on the rutile and alpha-PbO"2-type phases. It is found that the phase boundary, when plotted in a pressure-temperature diagram, changes from having a negative to having a positive slope...... with increasing temperature at about 6GPa and 850^oC. For nanophase material, the phase boundary is shifted towards lower pressure. The room-temperature bulk moduli are 210(120)GPa, 258(8)GPa and 290(20)GPa for rutile, the alpha-PbO"2-type phase and the baddeleyite-type phase, respectively....

Recommended reference materials for realization of physicochemical properties pressure-volume-temperature relationships

CERN Document Server

Herington, E F G

1977-01-01

Recommended Reference Materials for Realization of Physicochemical Properties presents recommendations of reference materials for use in measurements involving physicochemical properties, namely, vapor pressure; liquid-vapor critical temperature and critical pressure; orthobaric volumes of liquid and vapor; pressure-volume-temperature properties of the unsaturated vapor or gas; and pressure-volume-temperature properties of the compressed liquid. This monograph focuses on reference materials for vapor pressures at temperatures up to 770 K, as well as critical temperatures and critical pressures

Material migration in tokamak plasmas with a three-dimensional boundary

International Nuclear Information System (INIS)

Laengner, Ruth

2013-01-01

In this work, the influence of a 3D boundary induced by resonant magnetic perturbations (RMPs) on the material migration, i.e. the erosion from wall material due to the plasma surface interaction and the transport of these impurities is investigated for the first time. With applied RMPs two new domains occur in the magnetic field structure. Three dimensional SOL flux tubes with predominantly transport parallel to short magnetic field lines and a region of longer stochastic field lines with diffusive gradient driven radial transport. The plasma wall interaction and the material transport in these domains were investigated. A globally higher radial electric field E r as well as local changes in the magnetic field structure such as pressure driven sonic flows or locally higher E r fields can potentially influence the material transport with applied RMPs. The experiments were performed at the tokamak TEXTOR, the RMPs were induced by the dynamic ergodic divertor (DED). The plasma discharges and DED application was chosen to have a spatially separated 3D structure to be able to investigate the underlying physics. Two spherical carbon test limiters were positioned in different poloidal and toroidal positions which allowed to analyse the material migration in a 3D SOL flux tube and a stochastic region at the same time. Methane doped with 13 C was injected through the test limiters during three different plasma scenarios, without RMPs, with static RMPs and an RMP sweep. The test limiters and the injected methane were monitored in situ with different cameras and spectrometers. The deposition of the injected particles was measured post mortem by colourimetry, nuclear reaction analysis and secondary ion mass spectrometry. The most profound change from no RMP to the RMP cases is a 90 re-direction of the low ionised carbon C + and C 2+ into the E r x B-drift direction. From a comparison of the experiments and numerical field line tracing it was found that this is a global effect

Sensitivity of the Boundary Plasma to the Plasma-Material Interface

International Nuclear Information System (INIS)

Canik, John M.; Tang, X.-Z.

2017-01-01

While the sensitivity of the scrape-off layer and divertor plasma to the highly uncertain cross-field transport assumptions is widely recognized, the plasma is also sensitive to the details of the plasma-material interface (PMI) models used as part of comprehensive predictive simulations. Here in this paper, these PMI sensitivities are studied by varying the relevant sub-models within the SOLPS plasma transport code. Two aspects are explored: the sheath model used as a boundary condition in SOLPS, and fast particle reflection rates for ions impinging on a material surface. Both of these have been the study of recent high-fidelity simulation efforts aimed at improving the understanding and prediction of these phenomena. It is found that in both cases quantitative changes to the plasma solution result from modification of the PMI model, with a larger impact in the case of the reflection coefficient variation. Finally, this indicates the necessity to better quantify the uncertainties within the PMI models themselves, and perform thorough sensitivity analysis to propagate these throughout the boundary model; this is especially important for validation against experiment, where the error in the simulation is a critical and less-studied piece of the code-experiment comparison.

Development of boundary layers

International Nuclear Information System (INIS)

Herbst, R.

1980-01-01

Boundary layers develop along the blade surfaces on both the pressure and the suction side in a non-stationary flow field. This is due to the fact that there is a strongly fluctuating flow on the downstream blade row, especially as a result of the wakes of the upstream blade row. The author investigates the formation of boundary layers under non-stationary flow conditions and tries to establish a model describing the non-stationary boundary layer. For this purpose, plate boundary layers are measured, at constant flow rates but different interferent frequency and variable pressure gradients. By introducing the sample technique, measurements of the non-stationary boundary layer become possible, and the flow rate fluctuation can be divided in its components, i.e. stochastic turbulence and periodical fluctuation. (GL) [de

Detailed evaluation of RCS boundary rupture during high-pressure severe accident sequences

International Nuclear Information System (INIS)

Park, Rae-Joon; Hong, Seong-Wan

2011-01-01

A depressurization possibility of the reactor coolant system (RCS) before a reactor vessel rupture during a high-pressure severe accident sequence has been evaluated for the consideration of direct containment heating (DCH) and containment bypass. A total loss of feed water (TLOFW) and a station blackout (SBO) of the advanced power reactor 1400 (APR 1400) has been evaluated from an initiating event to a creep rupture of the RCS boundary by using the SCDAP/RELAP5 computer code. In addition, intentional depressurization of the RCS using power-operated safety relief valves (POSRVs) has been evaluated. The SCDAPRELAP5 results have shown that the pressurizer surge line broke before the reactor vessel rupture failure, but a containment bypass did not occur because steam generator U tubes did not break. The intentional depressurization of the RCS using POSRV was effective for the DCH prevention at a reactor vessel rupture. (author)

N13 - based reactor coolant pressure boundary leakage system

International Nuclear Information System (INIS)

Dissing, E.; Marbaeck, L.; Sandell, S.; Svansson, L.

1980-05-01

A system for the monitoring of leakage of coolant from the reactor coolant pressure boundary and auxiliary systems to the reactor containment, based on the detection of the N13 content in the atmosphere, has been tested. N13 is produced from the oxyegen of the reactor water via the recoil photon nuclear process H1 + 016 + He4. The generation of N13 is therefore independent of fuel element leakage and of the corrosion product content in the water. In the US AEC regulatory guide 1.45 has a leakage increase of 4 liter/ min been suggested as the response limit. The experiments carried out in Ringhals indicate, that with the accomplishment of minor improvements in the installation, a 4 liter/min leakage to the containment will give rise to a signal with a random error range of +- 0.25 liter/min, 99.7 % confidence level. (author)

Ionic conduction in sodium azide under high pressure: Experimental and theoretical approaches

Science.gov (United States)

Wang, Qinglin; Ma, Yanzhang; Sang, Dandan; Wang, Xiaoli; Liu, Cailong; Hu, Haiquan; Wang, Wenjun; Zhang, Bingyuan; Fan, Quli; Han, Yonghao; Gao, Chunxiao

2018-04-01

Alkali metal azides can be used as starting materials for the synthesis of polymeric nitrogen, a potential material of high energy density. In this letter, we report the ionic transport behavior in sodium azide under high pressure by in situ impedance spectroscopy and density functional theory calculations. The ionic transportation consists of ion transfer and Warburg diffusion processes. The ionic migration channels and barrier energy were given for the high-pressure phases. The enhanced ionic conductivity of the γ phase with pressure is because of the formation of space charge regions in the grain boundaries. This ionic conduction and grain boundary effect in NaN3 under pressures could shed light on the better understanding of the conduction mechanism of alkali azides and open up an area of research for polymeric nitrogen in these compounds and other high-energy-density polynitrides.

Plasticity of pressure-sensitive materials

CERN Document Server

Ochsner, Andreas

2014-01-01

Classical plasticity theory of metals is independent of the hydrostatic pressure. However, if the metal contains voids or pores or if the structure is composed of cells, this classical assumption is no more valid and the influence of the hydrostatic pressure must be incorporated in the constitutive description. Looking at the microlevel, metal plasticity is connected with the uniform planes of atoms organized with long-range order. Planes may slip past each other along their close-packed directions. The result is a permanent change of shape within the crystal and plastic deformation. The presence of dislocations increases the likelihood of planes slipping. Nowadays, the theory of pressure sensitive plasticity is successfully applied to many other important classes of materials (polymers, concrete, bones etc.) even if the phenomena on the micro-level are different to classical plasticity of metals. The theoretical background of this phenomenological approach based on observations on the macro-level is describe...

An Evaluation of a Phase-Lag Boundary Condition for Francis Hydroturbine Simulations Using a Pressure-Based Solver

Science.gov (United States)

Wouden, Alex; Cimbala, John; Lewis, Bryan

2014-11-01

While the periodic boundary condition is useful for handling rotational symmetry in many axisymmetric geometries, its application fails for analysis of rotor-stator interaction (RSI) in multi-stage turbomachinery flow. The inadequacy arises from the underlying geometry where the blade counts per row differ, since the blade counts are crafted to deter the destructive harmonic forces of synchronous blade passing. Therefore, to achieve the computational advantage of modeling a single blade passage per row while preserving the integrity of the RSI, a phase-lag boundary condition is adapted to OpenFOAM® software's incompressible pressure-based solver. The phase-lag construct is accomplished through restating the implicit periodic boundary condition as a constant boundary condition that is updated at each time step with phase-shifted data from the coupled cells adjacent to the boundary. Its effectiveness is demonstrated using a typical Francis hydroturbine modeled as single- and double-passages with phase-lag boundary conditions. The evaluation of the phase-lag condition is based on the correspondence of the overall computational performance and the calculated flow parameters of the phase-lag simulations with those of a baseline full-wheel simulation. Funded in part by DOE Award Number: DE-EE0002667.

Analysis of events related to cracks and leaks in the reactor coolant pressure boundary

Energy Technology Data Exchange (ETDEWEB)

Ballesteros, Antonio, E-mail: Antonio.Ballesteros-Avila@ec.europa.eu [JRC-IET: Institute for Energy and Transport of the Joint Research Centre of the European Commission, Postbus 2, NL-1755 ZG Petten (Netherlands); Sanda, Radian; Peinador, Miguel; Zerger, Benoit [JRC-IET: Institute for Energy and Transport of the Joint Research Centre of the European Commission, Postbus 2, NL-1755 ZG Petten (Netherlands); Negri, Patrice [IRSN: Institut de Radioprotection et de Sûreté Nucléaire (France); Wenke, Rainer [GRS: Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH (Germany)

2014-08-15

Highlights: • The important role of Operating Experience Feedback is emphasised. • Events relating to cracks and leaks in the reactor coolant pressure boundary are analysed. • A methodology for event investigation is described. • Some illustrative results of the analysis of events for specific components are presented. - Abstract: The presence of cracks and leaks in the reactor coolant pressure boundary may jeopardise the safe operation of nuclear power plants. Analysis of cracks and leaks related events is an important task for the prevention of their recurrence, which should be performed in the context of activities on Operating Experience Feedback. In response to this concern, the EU Clearinghouse operated by the JRC-IET supports and develops technical and scientific work to disseminate the lessons learned from past operating experience. In particular, concerning cracks and leaks, the studies carried out in collaboration with IRSN and GRS have allowed to identify the most sensitive areas to degradation in the plant primary system and to elaborate recommendations for upgrading the maintenance, ageing management and inspection programmes. An overview of the methodology used in the analysis of cracks and leaks related events is presented in this paper, together with the relevant results obtained in the study.

High-Pressure Design of Advanced BN-Based Materials

Directory of Open Access Journals (Sweden)

Oleksandr O. Kurakevych

2016-10-01

Full Text Available The aim of the present review is to highlight the state of the art in high-pressure design of new advanced materials based on boron nitride. Recent experimental achievements on the governing phase transformation, nanostructuring and chemical synthesis in the systems containing boron nitride at high pressures and high temperatures are presented. All these developments allowed discovering new materials, e.g., ultrahard nanocrystalline cubic boron nitride (nano-cBN with hardness comparable to diamond, and superhard boron subnitride B13N2. Thermodynamic and kinetic aspects of high-pressure synthesis are described based on the data obtained by in situ and ex situ methods. Mechanical and thermal properties (hardness, thermoelastic equations of state, etc. are discussed. New synthetic perspectives, combining both soft chemistry and extreme pressure–temperature conditions are considered.

Influences of triple junctions on stress-assisted grain boundary motion in nanocrystalline materials

International Nuclear Information System (INIS)

Aramfard, Mohammad; Deng, Chuang

2014-01-01

Stress-assisted grain boundary motion is among the most studied modes of microstructural evolution in crystalline materials. In this study, molecular dynamics simulations were used to systematically investigate the influences of triple junctions on the stress-assisted motion of symmetric tilt grain boundaries in Cu by considering a honeycomb nanocrystalline model. It was found that the grain boundary motion in nanocrystalline models was highly sensitive to the loading mode, and a strong coupling effect which was prevalent in bicrystal models was only observed when simple shear was applied. In addition, the coupling factor extracted from the honeycomb model was found to be larger and more sensitive to temperature change than that from bicrystal models for the same type of grain boundary under the same loading conditions. Furthermore, the triple junctions seemed to exhibit unusual asymmetric pinning effects to the migrating grain boundary and the constraints by the triple junctions and neighboring grains led to remarkable non-linear grain boundary motion in directions both parallel and normal to the applied shear, which was in stark contrast to that observed in bicrystal models. In addition, dislocation nucleation and propagation, which were absent in the bicrystal model, were found to play an important role on shear-induced grain boundary motion when triple junctions were present. In the end, a generalized model for shear-assisted grain boundary motion was proposed based on the findings from this research. (paper)

High-pressure phase transitions of deep earth materials

International Nuclear Information System (INIS)

Hirose, Kei

2009-01-01

Recent developments in synchrotron XRD measurements combined with laser-heated diamond-anvil cell (LHDAC) techniques have enabled us to search for a novel phase transition at extremely high pressure and temperature. A phase transition from MgSiO 3 perovskite to post-perovskite was discovered through a drastic change in XRD patterns above 120 GPa and 2500 K, corresponding to the condition in the lowermost mantle (Murakami et al., 2004; Oganov and Ono, 2004). A pressure-induced phase transformation from ABO 3 -type perovskite to any denser structures was not known at that time. This new MgSiO 3 polymorph called post-perovskite has an orthorhombic symmetry (space group: Cmcm) with a sheet-stacking structure. The Mg site in post-perovskite is smaller than that in perovskite, which results in a volume reduction by 1.0-1.5% from perovskite structure. The electrical conductivity of post-perovskite is higher by three orders of magnitude than that of perovskite at similar pressure range (Ohta et al., 2008). This is likely due to a shorter Fe-Fe distance in post-perovskite structure, while conduction mechanism is yet to be further examined. Phase transition boundary between perovskite and post-perovskite has been determined in a wide temperature range up to 4400 K at 170 GPa (Tateno et al., 2008). Phase relations of Fe alloys have been also studied at core pressures (>135 GPa), although the generation of high temperature is more difficult at higher pressures. A new high-pressure B2 phase of B2 phase of FeS was recently discovered above 180 GPa (Sata et al., 2008). The Fe-Ni alloys have a wide pressure-temperature stability field of fcc phase at the core pressure range, depending on the Ni content (Kuwayama et al., 2008). (author)

Characterization of phosphorus segregation in neutron-irradiated Russian pressure vessel steel weld

International Nuclear Information System (INIS)

Miller, M.K.; Jayaram, R.; Russell, K.F.

1995-01-01

An atom probe field ion microscopy characterization of three Russian pressure vessel steels has been performed. Field ion micrographs of several lath boundaries have indicated that they are decorated with a semicontinuous film of discrete brightly-imaging precipitates that were identified as molybdenum carbonitrides. In addition, extremely high phosphorus levels were measured at the lath boundaries. The phosphorus was found to be confined to an extremely narrow region indicative of monolayer type segregation. The phosphorus coverage determined from the atom probe results of the unirradiated materials agree with predictions based on McLean's equilibrium model of grain boundary segregation. The boundary phosphorus coverage of a neutron-irradiated weld material was significantly higher than in the unirradiated material. Ultrafine darkly-imaging copper- and phosphorus-enriched precipitates were also observed in the matrix of the neutron-irradiated material. (orig.)

A two pressure-velocity approach for immersed boundary methods in three dimensional incompressible flows

International Nuclear Information System (INIS)

Sabir, O; Ahmad, Norhafizan; Nukman, Y; Tuan Ya, T M Y S

2013-01-01

This paper describes an innovative method for computing fluid solid interaction using Immersed boundary methods with two stage pressure-velocity corrections. The algorithm calculates the interactions between incompressible viscous flows and a solid shape in three-dimensional domain. The fractional step method is used to solve the Navier-Stokes equations in finite difference schemes. Most of IBMs are concern about exchange of the momentum between the Eulerian variables (fluid) and the Lagrangian nodes (solid). To address that concern, a new algorithm to correct the pressure and the velocity using Simplified Marker and Cell method is added. This scheme is applied on staggered grid to simulate the flow past a circular cylinder and study the effect of the new stage on calculations cost. To evaluate the accuracy of the computations the results are compared with the previous software results. The paper confirms the capacity of new algorithm for accurate and robust simulation of Fluid Solid Interaction with respect to pressure field

Historical cartographic materials as a source for international and cadastral boundary management in rivers

Science.gov (United States)

Srebro, Haim

2018-05-01

International and cadastral boundaries are important for ensuring stable legal territorial matters. This article deals with the long-term location and management of boundaries in rivers and the depiction of the rivers on cartographic materials. A few countries have agreed that the boundary will not follow changes in the river (like in the Mongolia-China Border Treaty), whereas most agree that the boundary will follow slow, natural and gradual changes in the river (like is stated in the Israel-Jordan Peace Treaty). The international boundary under the British Mandate between Palestine and Trans-Jordan in the Jordan and Yarmuk rivers was defined in 1922. The cadastral boundaries were defined in these rivers in the 1930s along the international boundary. For more than 70 years, until the Israel-Jordan 1994 Peace Treaty, the rivers have changed their channels east and westward to distances up to hundreds of meters. During that period the mandatory boundaries in these rivers changed their political status to the armistice lines, the cease-fire lines, and to international boundaries between sovereign states. These lines were usually delineated on topographic maps in the rivers, drawn by cartographers following contemporary map revision. During that entire period the cadastral boundaries were not changed in order to adapt them to the actual position of the rivers and to the delineated international boundaries. Owing to large water works on both rivers, including the construction of dams and diversion channels in order to meet the increasing needs of the population on both sides, the water flow of the rivers decreased dramatically to less than one tenth of the original natural flow. The population today is more than ten times than it used to be under the British Mandate. The changes in the water channels during the last 20 years since the 1994 peace treaty are in the magnitude of 10 meters versus hundreds of meters in the past. In addition, intensive land cultivation

Boundary-Layer Separation Control under Low-Pressure Turbine Airfoil Conditions using Glow-Discharge Plasma Actuators

Science.gov (United States)

Hultgren, Lennart S.; Ashpis, David E.

2003-01-01

Modem low-pressure turbines, in general, utilize highly loaded airfoils in an effort to improve efficiency and to lower the number of airfoils needed. Typically, the airfoil boundary layers are turbulent and fully attached at takeoff conditions, whereas a substantial fraction of the boundary layers on the airfoils may be transitional at cruise conditions due to the change of density with altitude. The strong adverse pressure gradients on the suction side of these airfoils can lead to boundary-layer separation at the latter low Reynolds number conditions. Large separation bubbles, particularly those which fail to reattach, cause a significant degradation of engine efficiency. A component efficiency drop of the order 2% may occur between takeoff and cruise conditions for large commercial transport engines and could be as large as 7% for smaller engines at higher altitude. An efficient means of of separation elimination/reduction is, therefore, crucial to improved turbine design. Because the large change in the Reynolds number from takeoff to cruise leads to a distinct change in the airfoil flow physics, a separation control strategy intended for cruise conditions will need to be carefully constructed so as to incur minimum impact/penalty at takeoff. A complicating factor, but also a potential advantage in the quest for an efficient strategy, is the intricate interplay between separation and transition for the situation at hand. Volino gives a comprehensive discussion of several recent studies on transition and separation under low-pressure-turbine conditions, among them one in the present facility. Transition may begin before or after separation, depending on the Reynolds number and other flow conditions. If the transition occurs early in the boundary layer then separation may be reduced or completely eliminated. Transition in the shear layer of a separation bubble can lead to rapid reattachment. This suggests using control mechanisms to trigger and enhance early

Two and three dimensional electron backscattered diffraction analysis of solid oxide cells materials

DEFF Research Database (Denmark)

Saowadee, Nath

in solid oxide fuel cell and electrolysis cell. Conductivity of STN is one of the important properties that researchers desire to improve. Grin boundary conductivity contributes to the overall conductivity of the STN. Grain boundary density controlled by mainly grain growth in material processing. Grain......There are two main technique were developed in this work: a technique to calculate grain boundary energy and pressure and a technique to measure lattice constant from EBSD. The techniques were applied to Nb-doped Strontium titanate (STN) and yttria stabilized zirconia (YSZ) which are commonly used...... boundary migration in grain growth involves grain boundary mobility and net pressure on it. Thus grain boundary energy and pressure of STN were calculated in this work. Secondary phase is undesired in STN and YSZ synthesis. The secondary phase in ceramics with the same compounds can have different lattice...

Grain boundary corrosion of copper canister material

International Nuclear Information System (INIS)

Fennell, P.A.H.; Graham, A.J.; Smart, N.R.; Sofield, C.J.

2001-03-01

The proposed design for a final repository for spent fuel and other long-lived residues in Sweden is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will then be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container fitted inside a corrosion-resistant copper canister. During fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow they will tend to concentrate impurities within the copper at the new grain boundaries. The work described in this report was undertaken to determine whether there is any possibility of enhanced corrosion at grain boundaries within the copper canister. The potential for grain boundary corrosion was investigated by exposing copper specimens, which had undergone different heat treatments and hence had different grain sizes, to aerated artificial bentonite-equilibrated groundwater with two concentrations of chloride, for increasing periods of time. The degree of grain boundary corrosion was determined by atomic force microscopy (AFM) and optical microscopy. AFM showed no increase in grain boundary 'ditching' for low chloride groundwater. In high chloride groundwater the surface was covered uniformly with a fine-grained oxide. No increases in oxide thickness were observed. No significant grain boundary attack was observed using optical microscopy either. The work suggests that in aerated artificial groundwaters containing chloride ions, grain boundary corrosion of copper is unlikely to adversely affect SKB's copper canisters

Eccentric pressurized tube for measuring creep rupture

International Nuclear Information System (INIS)

Schwab, P.R.

1981-01-01

Creep rupture is a long term failure mode in structural materials that occurs at high temperatures and moderate stress levels. The deterioration of the material preceding rupture, termed creep damage, manifests itself in the formation of small cavities on grain boundaries. To measure creep damage, sometimes uniaxial tests are performed, sometimes density measurements are made, and sometimes the grain boundary cavities are measured by microscopy techniques. The purpose of the present research is to explore a new method of measuring creep rupture, which involves measuring the curvature of eccentric pressurized tubes. Theoretical investigations as well as the design, construction, and operation of an experimental apparatus are included in this research

Minimized Capillary End Effect During CO2 Displacement in 2-D Micromodel by Manipulating Capillary Pressure at the Outlet Boundary in Lattice Boltzmann Method

Science.gov (United States)

Kang, Dong Hun; Yun, Tae Sup

2018-02-01

We propose a new outflow boundary condition to minimize the capillary end effect for a pore-scale CO2 displacement simulation. The Rothman-Keller lattice Boltzmann method with multi-relaxation time is implemented to manipulate a nonflat wall and inflow-outflow boundaries with physically acceptable fluid properties in 2-D microfluidic chip domain. Introducing a mean capillary pressure acting at CO2-water interface to the nonwetting fluid at the outlet effectively prevents CO2 injection pressure from suddenly dropping upon CO2 breakthrough such that the continuous CO2 invasion and the increase of CO2 saturation are allowed. This phenomenon becomes most pronounced at capillary number of logCa = -5.5, while capillary fingering and massive displacement of CO2 prevail at low and high capillary numbers, respectively. Simulations with different domain length in homogeneous and heterogeneous domains reveal that capillary pressure and CO2 saturation near the inlet are reproducible compared with those with a proposed boundary condition. The residual CO2 saturation uniquely follows the increasing tendency with increasing capillary number, corroborated by experimental evidences. The determination of the mean capillary pressure and its sensitivity are also discussed. The proposed boundary condition is commonly applicable to other pore-scale simulations to accurately capture the spatial distribution of nonwetting fluid and corresponding displacement ratio.

High-pressure structural behaviour of nanocrystalline Ge

International Nuclear Information System (INIS)

Wang, H; Liu, J F; He, Y; Wang, Y; Chen, W; Jiang, J Z; Olsen, J Staun; Gerward, L

2007-01-01

The equation of state and the pressure of the I-II transition have been studied for nanocrystalline Ge using synchrotron x-ray diffraction. The bulk modulus and the transition pressure increase with decreasing particle size for both Ge-I and Ge-II, but the percentage volume collapse at the transition remains constant. Simplified models for the high-pressure structural behaviour are presented, based on the assumption that a large fraction of the atoms reside in grain boundary regions of the nanocrystalline material. The interface structure plays a significant role in affecting the transition pressure and the bulk modulus

Microstructural examination of irradiated zircaloy-2 pressure tube material

International Nuclear Information System (INIS)

Srivastava, D.; Tewari, R.; Dey, G.K.; Sah, D.N.; Banerjee, S.

2005-01-01

Irradiation induced microstructural changes in Zr alloys strongly influence the creep, growth and mechanical properties of pressure tube material. Since dimensional changes and mechanical property degradation can limit the life of pressure tube, it is essential to study and develop an understanding of the microstructure produced by neutron irradiation, by examining samples taken from the irradiated components. In the present work, an effort has been made to examine, microstructure of the Zircaloy-2 pressure tube material irradiated in the Indian Pressurized Heavy Water Reactor (PHWR). The present work is a first step towards a comprehensive program of characterization of microstructure of reactor materials after irradiation to different fluence levels in power reactors. In this study, samples from a Zircaloy-2 pressure tube, which had been in operation in the high flux region of Rajasthan Atomic Power Station Unit 1, for a period for 6.77 effective full power years (EFPYs), have been prepared and examined. The samples selected from the tube are expected to have a cumulative radiation damage of about 3 dpa. Samples prepared from the off cuts of RAPS-1 pressure tubes were also studied for examining the unirradiated microstructure of the material. The samples were examined in a 200kV JEOL 2000 FX microscope. This paper presents the distinct features observed in irradiated sample and a comprehensive comparison of the microstructures of the unirradiated and irradiated material. The effect of annealing on the annihilation of the defects generated during irradiation has been also studied. The bright field micrographs revealed that microstructure of the irradiated samples was different in many respects from the microstructure of the unirradiated samples. The presence of defect structure in the form of loops etc could be seen in the irradiated sample. These loops were mostly c-type loops lying in the basal plane. The dissolution and redistribution of the precipitates were

Under pressure: Climate change, upwelling and eastern boundary upwelling ecosystems

Directory of Open Access Journals (Sweden)

Marisol eGarcía-Reyes

2015-12-01

Full Text Available The IPCC AR5 provided an overview of the likely effects of climate change on Eastern Boundary Upwelling Systems (EBUS, stimulating increased interest in research examining the issue. We use these recent studies to develop a new synthesis describing climate change impacts on EBUS. We find that model and observational data suggest coastal upwelling-favorable winds in poleward portions of EBUS have intensified and will continue to do so in the future. Although evidence is weak in data that are presently available, future projections show that this pattern might be driven by changes in the positioning of the oceanic high-pressure systems rather than by deepening of the continental low-pressure systems, as previously proposed. There is low confidence regarding the future effects of climate change on coastal temperatures and biogeochemistry due to uncertainty in the countervailing responses to increasing upwelling and coastal warming, the latter of which could increase thermal stratification and render upwelling less effective in lifting nutrient-rich deep waters into the photic zone. Although predictions of ecosystem responses are uncertain, EBUS experience considerable natural variability and may be inherently resilient. However, multi-trophic level, end-to-end (i.e., winds to whales studies are needed to resolve the resilience of EBUS to climate change, especially their response to long-term trends or extremes that exceed pre-industrial ranges.

Method of extraction under pressure of fossil material

Energy Technology Data Exchange (ETDEWEB)

Fredenmark, G L

1942-02-24

A method is described of extraction under pressure of fossil material, such as coal, brown coal (lignite), peat, oil shale. It is characterized by carrying out the process of extraction by utilization of fractions of shale oils and/or peat tar with a boiling point above 170/sup 0/C and under such as pressure that the medium of extraction is in a liquid state.

The enhanced local pressure model for the accurate analysis of fluid pressure driven fracture in porous materials

NARCIS (Netherlands)

Remij, E.W.; Remmers, J.J.C.; Huyghe, J.M.R.J.; Smeulders, D.M.J.

2015-01-01

In this paper, we present an enhanced local pressure model for modelling fluid pressure driven fractures in porous saturated materials. Using the partition-of-unity property of finite element shape functions, we describe the displacement and pressure fields across the fracture as a strong

Risk-based priorities for inspection of nuclear pressure boundary components at selected LWRs

International Nuclear Information System (INIS)

Vo, T.V.; Simonen, F.A.; Gore, B.F.; Doctor, S.R.; Smith, B.W.

1990-01-01

Data from existing probabilistic risk assessments for eight representative nuclear power plants were used to identify and prioritize the most relevant systems to plant safety. The objective of this paper is to assess current in-service inspection requirements for pressure boundary systems and components, and to develop recommendations for improvements. This study demonstrates the feasibility of using risk-based methods to develop plant-specific inspection plans. Results for the eight representative plants also indicate generic trends that suggest improvements in current inspection plans now based on priorities set in accordance with code definitions of Class 1, 2, and 3 systems

Risk-based priorities for inspection of nuclear pressure boundary components at selected LWRs

International Nuclear Information System (INIS)

Vo, T.V.; Simonen, F.A.; Gore, B.F.; Doctor, S.R.; Smith, B.W.

1990-03-01

Data from existing probabilistic risk assessments for eight representative nuclear power plants were used to identify and prioritize the most relevant systems to plant safety. The objective was to assess current in-service inspection requirements for pressure boundary systems and components, and to develop recommendations for improvements. This study demonstrates the feasibility of using risk-based methods to develop plant-specific inspection plans. Results for the eight representative plants also indicate generic trends that suggest improvements in current inspection plans now based on priorities set in accordance with code definitions of Class 1, 2, and 3 systems. 2 refs., 4 figs., 5 tabs

Multilayer Pressure Vessel Materials Testing and Analysis. Phase 1

Science.gov (United States)

Cardinal, Joseph W.; Popelar, Carl F.; Page, Richard A.

2014-01-01

To provide NASA a comprehensive suite of materials strength, fracture toughness and crack growth rate test results for use in remaining life calculations for aging multilayer pressure vessels, Southwest Research Institute (R) (SwRI) was contracted in two phases to obtain relevant material property data from a representative vessel. This report describes Phase 1 of this effort which includes a preliminary material property assessment as well as a fractographic, fracture mechanics and fatigue crack growth analyses of an induced flaw in the outer shell of a representative multilayer vessel that was subjected to cyclic pressure test. SwRI performed this Phase 1 effort under contract to the Digital Wave Corporation in support of their contract to Jacobs ATOM for the NASA Ames Research Center.

Boundary integral methods for unsaturated flow

International Nuclear Information System (INIS)

Martinez, M.J.; McTigue, D.F.

1990-01-01

Many large simulations may be required to assess the performance of Yucca Mountain as a possible site for the nations first high level nuclear waste repository. A boundary integral equation method (BIEM) is described for numerical analysis of quasilinear steady unsaturated flow in homogeneous material. The applicability of the exponential model for the dependence of hydraulic conductivity on pressure head is discussed briefly. This constitutive assumption is at the heart of the quasilinear transformation. Materials which display a wide distribution in pore-size are described reasonably well by the exponential. For materials with a narrow range in pore-size, the exponential is suitable over more limited ranges in pressure head. The numerical implementation of the BIEM is used to investigate the infiltration from a strip source to a water table. The net infiltration of moisture into a finite-depth layer is well-described by results for a semi-infinite layer if αD > 4, where α is the sorptive number and D is the depth to the water table. the distribution of moisture exhibits a similar dependence on αD. 11 refs., 4 figs.,

Brazing of Sealing for Instrumentation Feed through of high Pressure Vessel

International Nuclear Information System (INIS)

Jeong, H. Y.; Ahn, S. H.; Joung, C. Y.; Lee, J. M.; Lee, C. Y.

2011-01-01

Fuel Test Loop(FTL) is a facility which could conduct a fuel irradiation test at HANARO(High-flux Advanced Neutron Application Reactor). FTL simulates commercial NPP's operating conditions such as the pressure, temperature and neutron flux levels to conduct the irradiation and thermo-hydraulic tests. It is composed of an In-Pile test Section(IPS) and an Out- Pile System(OPS). The OPS contains a pressurizer, cooler, pump, heater and purification system which are necessary to maintain the proper fluid conditions. In addition, the OPS contains engineered safety systems that could safely shutdown both HANARO and FTL if an accident occurs. The IPS accommodating fuel pins has loaded IP-1 hole in HANARO has a double pressure vessel for the design conditions of 350 .deg. C, 17.5MPa and is composed of outer assembly and inner assembly. It has instruments such as a thermocouple, LVDT and SPND to measure the fuel performances during the test. FTL coolant is supplied to the IPS at the core of commercial nuclear power plants and the same temperature, pressure and flow conditions. Sensors installed on the inside of IPS to send a signal transmission MI-Cables to the outside for instrumentation is through the pressure boundary. Therefore, pressure boundary should be maintained in the sealing performance. Brazing is typically lower than the melting point of material without melting the material almost would be like welding when it is necessary to use. It is commonly used to use BAg(ASME II SFA-5.8 UNS-P07563) filler metal, but corrosion occurs containing a large quantity of copper in Bag, and when contact with the coolant, the coolant water quality is influenced. Therefore, using BNi-2(ASME II SFA-5.8 UNS-N99620) filler metal is considered. Brazing at the Sealing Plug in the top of IPS was considered for Mi-cable's integrity and to maintain the pressure boundary. After brazing is performed, brazing the Mi-cable integrity and pressure boundary sealing performance was tested

Brazing of Sealing for Instrumentation Feed through of high Pressure Vessel

Energy Technology Data Exchange (ETDEWEB)

Jeong, H. Y.; Ahn, S. H.; Joung, C. Y.; Lee, J. M.; Lee, C. Y. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-05-15

Fuel Test Loop(FTL) is a facility which could conduct a fuel irradiation test at HANARO(High-flux Advanced Neutron Application Reactor). FTL simulates commercial NPP's operating conditions such as the pressure, temperature and neutron flux levels to conduct the irradiation and thermo-hydraulic tests. It is composed of an In-Pile test Section(IPS) and an Out- Pile System(OPS). The OPS contains a pressurizer, cooler, pump, heater and purification system which are necessary to maintain the proper fluid conditions. In addition, the OPS contains engineered safety systems that could safely shutdown both HANARO and FTL if an accident occurs. The IPS accommodating fuel pins has loaded IP-1 hole in HANARO has a double pressure vessel for the design conditions of 350 .deg. C, 17.5MPa and is composed of outer assembly and inner assembly. It has instruments such as a thermocouple, LVDT and SPND to measure the fuel performances during the test. FTL coolant is supplied to the IPS at the core of commercial nuclear power plants and the same temperature, pressure and flow conditions. Sensors installed on the inside of IPS to send a signal transmission MI-Cables to the outside for instrumentation is through the pressure boundary. Therefore, pressure boundary should be maintained in the sealing performance. Brazing is typically lower than the melting point of material without melting the material almost would be like welding when it is necessary to use. It is commonly used to use BAg(ASME II SFA-5.8 UNS-P07563) filler metal, but corrosion occurs containing a large quantity of copper in Bag, and when contact with the coolant, the coolant water quality is influenced. Therefore, using BNi-2(ASME II SFA-5.8 UNS-N99620) filler metal is considered. Brazing at the Sealing Plug in the top of IPS was considered for Mi-cable's integrity and to maintain the pressure boundary. After brazing is performed, brazing the Mi-cable integrity and pressure boundary sealing performance was

On a free boundary problem for a strongly degenerate quasilinear parabolic equation with an application to a model of pressure filtration

Energy Technology Data Exchange (ETDEWEB)

Buerger, R.; Frid, H.; Karlsen, K.H.

2002-07-01

We consider a free boundary problem of a quasilinear strongly degenerate parabolic equation arising from a model of pressure filtration of flocculated suspensions. We provide definitions of generalized solutions of the free boundary problem in the framework of L2 divergence-measure fields. The formulation of boundary conditions is based on a Gauss-Green theorem for divergence-measure fields on bounded domains with Lipschitz deformable boundaries and avoids referring to traces of the solution. This allows to consider generalized solutions from a larger class than BV. Thus it is not necessary to derive the usual uniform estimates on spatial and time derivatives of the solutions of the corresponding regularized problem requires in the BV approach. We first prove existence and uniqueness of the solution of the regularized parabolic free boundary problem and then apply the vanishing viscosity method to prove existence of a generalized solution to the degenerate free boundary problem. (author)

Slovenian-Croatian boundary: backgrounds of boundary-making and boundary-breaking in Istria regarding the contemporary boundary dispute

Directory of Open Access Journals (Sweden)

Damir Josipovič

2012-06-01

Full Text Available Boundary-making in Istria is an old undertaking. It has actually never ceasesed, not even today. Istrian peninsula has thus undergone substantial boundary shifts during the last couple of centuries (especially after the Venetian demise in 1797. But Istria carries its worldwide fame also due to one of probably the harshest disputes on the post-war European grounds – the Trieste territory dispute. In author's perspective, this dispute is one of the four main corner-stones of the current Slovenian-Croatian boundary dispute. The remaining three include the Kozler's boundary around Dragonja (Rokava River, the ungraspable notions of Austrian censuses in Istria, and the narratives of partisan settlements on military jurisdiction. However, there are other very important aspects which significantly shaped the development of the dispute, but we will focus at assessing the importance of the aforementioned ones. In this sense, the analysis of the effects of the outcome of the Trieste dispute and its implications to the contemporary interstate dispute is set forth. By unveiling its material and consequently its psychological effects upon the contemporary bilateral relations, its analyses simultaneously reveals backgrounds of never answered question, why Kozler's proposed linguistic boundary around Dragonja (Rokava River turned out to become a boundary of national character. Though nowadays disputed, there is absolutely no chance for both involved parties to substantially draw away from once decisively drawn line of a layman. Despite the fierce battle of words in Slovenian public media on whether should the interstate boundary be placed on Mirna (Quieto or Dragonja Rivers, it will be argued here that the actual choice of the Valley of Dragonja as a boundary is by all means Slovenian. The arguments are based on extensive analyses of cartographic materials, relevant literature, documents, and statistical data.

Slovenian-Croatian boundary: backgrounds of boundary-making and boundary-breaking in Istria regarding the contemporary boundary dispute

Directory of Open Access Journals (Sweden)

Damir Josipovič

2012-01-01

Full Text Available Boundary-making in Istria is an old undertaking. It has actually never ceasesed, not even today. Istrian peninsula has thus undergone substantial boundary shifts during the last couple of centuries (especially after the Venetian demise in 1797. But Istria carries its worldwide fame also due to one of probably the harshest disputes on the post-war European grounds – the Trieste territory dispute. In author's perspective, this dispute is one of the four main corner-stones of the current Slovenian-Croatian boundary dispute. The remaining three include the Kozler's boundary around Dragonja (Rokava River, the ungraspable notions of Austrian censuses in Istria, and the narratives of partisan settlements on military jurisdiction. However, there are other very important aspects which significantly shaped the development of the dispute, but we will focus at assessing the importance of the aforementioned ones. In this sense, the analysis of the effects of the outcome of the Trieste dispute and its implications to the contemporary interstate dispute is set forth. By unveiling its material and consequently its psychological effects upon the contemporary bilateral relations, its analyses simultaneously reveals backgrounds of never answered question, why Kozler's proposed linguistic boundary around Dragonja (Rokava River turned out to become a boundary of national character. Though nowadays disputed, there is absolutely no chance for both involved parties to substantially draw away from once decisively drawn line of a layman. Despite the fierce battle of words in Slovenian public media on whether should the interstate boundary be placed on Mirna (Quieto or Dragonja Rivers, it will be argued here that the actual choice of the Valley of Dragonja as a boundary is by all means Slovenian. The arguments are based on extensive analyses of cartographic materials, relevant literature, documents, and statistical data.

Characterization of Rare Reverse Flow Events in Adverse Pressure Gradient Turbulent Boundary Layers

Science.gov (United States)

Kaehler, Christian J.; Bross, Matthew; Fuchs, Thomas

2017-11-01

Time-resolved tomographic flow fields measured in the viscous sublayer region of a turbulent boundary layer subjected to an adverse pressure gradient (APG) are examined with the aim to resolve and characterize reverse flow events at Reτ = 5000. The fields were measured using a novel high resolution tomographic particle tracking technique. It is shown that this technique is able to fully resolve mean and time dependent features of the complex three-dimensional flow with high accuracy down to very near-wall distances ( 10 μm). From time resolved Lagrangian particle trajectories, statistical information as well as instantaneous topological features of near-wall flow events are deduced. Similar to the zero pressure gradient case (ZPG), it was found that individual events with reverse flow components still occur relatively rarely under the action of the pressure gradient investigated here. However, reverse flow events comprised of many individual events, are shown to appear in relatively organized groupings in both spanwise and streamise directions. Furthermore, instantaneous measurements of reverse flow events show that these events are associated with the motion of low-momentum streaks in the near-wall region. This work is supported by the Priority Programme SPP 1881 Turbulent Superstructures and the individual project Grant KA1808/8-2 of the Deutsche Forschungsgemeinschaft.

Boundary lubrication of stainless steel and CoCrMo alloy materials based on three ester-based additives

NARCIS (Netherlands)

Yan, J.; Zeng, Xiangqiong; Ren, T.; van der Heide, Emile

2014-01-01

Material selection and lubricant additive development are two important aspects for engineering applications. This work explores the possibilities of three different ester-based additives (DBOP, ODOC and DOB) to generate boundary films on two corrosion and wear resistant materials, stainless steel

Unravelling the High-Pressure Behaviour of Dye-Zeolite L Hybrid Materials

Directory of Open Access Journals (Sweden)

Lara Gigli

2018-02-01

Full Text Available Self-assembly of chromophores nanoconfined in porous materials such as zeolite L has led to technologically relevant host-guest systems exploited in solar energy harvesting, photonics, nanodiagnostics and information technology. The response of these hybrid materials to compression, which would be crucial to enhance their application range, has never been explored to date. By a joint high-pressure in situ synchrotron X-ray powder diffraction and ab initio molecular dynamics approach, herein we unravel the high-pressure behaviour of hybrid composites of zeolite L with fluorenone dye. High-pressure experiments were performed up to 6 GPa using non-penetrating pressure transmitting media to study the effect of dye loading on the structural properties of the materials under compression. Computational modelling provided molecular-level insight on the response to compression of the confined dye assemblies, evidencing a pressure-induced strengthening of the interaction between the fluorenone carbonyl group and zeolite L potassium cations. Our results reveal an impressive stability of the fluorenone-zeolite L composites at GPa pressures. The remarkable resilience of the supramolecular organization of dye molecules hyperconfined in zeolite L channels may open the way to the realization of optical devices able to maintain their functionality under extreme conditions.

Preliminary fracture analysis of the core pressure boundary tube for the Advanced Neutron Source Research Reactor

International Nuclear Information System (INIS)

Schulz, K.C.

1995-08-01

The outer core pressure boundary tube (CPBT) of the Advanced neutron Source (ANS) reactor being designed at Oak Ridge National Laboratory is currently specified as being composed of 6061-T6 aluminum. ASME Boiler and Pressure Vessel Code fracture analysis rules for nuclear components are based on the use of ferritic steels; the expressions, tables, charts and equations were all developed from tests and analyses conducted for ferritic steels. Because of the nature of the Code, design with thin aluminum requires analytical approaches that do not directly follow the Code. The intent of this report is to present a methodology comparable to the ASME Code for ensuring the prevention of nonductile fracture of the CPBT in the ANS reactor. 6061-T6 aluminum is known to be a relatively brittle material; the linear elastic fracture mechanics (LEFM) approach is utilized to determine allowable flaw sizes for the CPBT. A J-analysis following the procedure developed by the Electric Power Research Institute was conducted as a check; the results matched those for the LEFM analysis for the cases analyzed. Since 6061-T6 is known to embrittle when irradiated, the reduction in K Q due to irradiation is considered in the analysis. In anticipation of probable requirements regarding maximum allowable flaw size, a survey of nondestructive inspection capabilities is also presented. A discussion of probabilistic fracture mechanics approaches, principally Monte Carlo techniques, is included in this report as an introduction to what quantifying the probability of nonductile failure of the CPBT may entail

High-pressure Raman spectroscopy of phase change materials

Energy Technology Data Exchange (ETDEWEB)

Hsieh, Wen-Pin, E-mail: wphsieh@stanford.edu; Mao, Wendy L. [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States); Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305 (United States); Zalden, Peter [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States); Wuttig, Matthias [I. Physikalisches Institut (IA), RWTH Aachen University, 52056 Aachen (Germany); JARA – Fundamentals of Future Information Technology, RWTH Aachen University, 52056 Aachen (Germany); Lindenberg, Aaron M. [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); SLAC National Accelerator Laboratory, PULSE Institute, Menlo Park, California 94025 (United States)

2013-11-04

We used high-pressure Raman spectroscopy to study the evolution of vibrational frequencies of the phase change materials (PCMs) Ge{sub 2}Sb{sub 2}Te{sub 5}, GeSb{sub 2}Te{sub 4}, and SnSb{sub 2}Te{sub 4}. We found that the critical pressure for triggering amorphization in the PCMs decreases with increasing vacancy concentration, demonstrating that the presence of vacancies, rather than differences in the atomic covalent radii, is crucial for pressure-induced amorphization in PCMs. Compared to the as-deposited amorphous phase, the pressure-induced amorphous phase has a similar vibrational spectrum but requires much lower laser power to transform into the crystalline phase, suggesting different kinetics of crystallization, which may have implications for applications of PCMs in non-volatile data storage.

Mean flow structure of non-equilibrium boundary layers with adverse ...

Indian Academy of Sciences (India)

According to them, an equilibrium boundary layer might exist if the pressure ... of adverse pressure gradient on the turbulent boundary layer at the flat plate for ..... of a constant-pressure turbulent layer to the sudden application of an sudden.

Emerging boundaries

DEFF Research Database (Denmark)

Løvschal, Mette

2014-01-01

of temporal and material variables have been applied as a means of exploring the processes leading to their socioconceptual anchorage. The outcome of this analysis is a series of interrelated, generative boundary principles, including boundaries as markers, articulations, process-related devices, and fixation...

Transient integral boundary layer method to calculate the translesional pressure drop and the fractional flow reserve in myocardial bridges

Directory of Open Access Journals (Sweden)

Möhlenkamp Stefan

2006-06-01

Full Text Available Abstract Background The pressure drop – flow relations in myocardial bridges and the assessment of vascular heart disease via fractional flow reserve (FFR have motivated many researchers the last decades. The aim of this study is to simulate several clinical conditions present in myocardial bridges to determine the flow reserve and consequently the clinical relevance of the disease. From a fluid mechanical point of view the pathophysiological situation in myocardial bridges involves fluid flow in a time dependent flow geometry, caused by contracting cardiac muscles overlying an intramural segment of the coronary artery. These flows mostly involve flow separation and secondary motions, which are difficult to calculate and analyse. Methods Because a three dimensional simulation of the haemodynamic conditions in myocardial bridges in a network of coronary arteries is time-consuming, we present a boundary layer model for the calculation of the pressure drop and flow separation. The approach is based on the assumption that the flow can be sufficiently well described by the interaction of an inviscid core and a viscous boundary layer. Under the assumption that the idealised flow through a constriction is given by near-equilibrium velocity profiles of the Falkner-Skan-Cooke (FSC family, the evolution of the boundary layer is obtained by the simultaneous solution of the Falkner-Skan equation and the transient von-Kármán integral momentum equation. Results The model was used to investigate the relative importance of several physical parameters present in myocardial bridges. Results have been obtained for steady and unsteady flow through vessels with 0 – 85% diameter stenosis. We compare two clinical relevant cases of a myocardial bridge in the middle segment of the left anterior descending coronary artery (LAD. The pressure derived FFR of fixed and dynamic lesions has shown that the flow is less affected in the dynamic case, because the distal

Hydrostatic high pressures for material deformations. Application to Chevrel phase superconductors

International Nuclear Information System (INIS)

Massat, H.

1984-01-01

The effect of hydrostatic high pressures on the ductility of materials is reviewed and applications are made to powder metallurgy under isostatic pressure and hydrostatic extrusion of superconductors [fr

Effect of mixing rule boundary conditions on high pressure (liquid + liquid) equilibrium prediction

International Nuclear Information System (INIS)

Hsieh, Min-Kang; Lin, Shiang-Tai

2012-01-01

Highlights: ► Prediction of LLE from the combined use of EOS and liquid model are examined. ► The mixing rule used affects the predicted pressure dependence of LLE. ► MHV1 mixing rule predicts decent LLE at low pressures. ► WS mixing rule predicts more accurate excess volume and LLE at high pressures. ► The hybrid of MHV1 and WS mixing rule gives overall the best predictions. - Abstract: We examine the prediction of high pressure (liquid + liquid) equilibrium (LLE) from the Peng–Robinson equation with three excess Gibbs free energy (G ex )-based mixing rules (MR): the first order modified Huron–Vidal (MHV1), the Wong–Sandler (WS), and a hybrid of these two (referred to as G ex B 2 ). These mixing rules differ by the boundary conditions used for determination of the temperature and composition dependence of parameters a and b in the PR EOS. The condition of matching the excess Gibbs free energy from the EOS at zero pressure to that from the G ex model, used in MHV1 and G ex B 2 MR, leads to a similar miscibility gap from PR EOS and the G ex model used. On the other hand, the condition of matching excess Helmholtz energy from the EOS at infinite pressure to that from the G ex model, used in the WS MR, shows remarkable deviations. The condition of quadratic composition dependence in the second virial coefficient (B 2 ), used in WS and G ex B 2 MR, allows for both positive and negative values in the molar excess volume. Depending on the mixture, either the increase or decrease of the miscibility gap with pressure can be observed when the WS or the G ex B 2 MR is used. The condition of linear combination of molecular sizes of each component used in the MHV1 MR, however, often leads to small, positive molar excess volumes. As a consequence, the predicted LLE from using the MHV1 MR are insensitive to pressure. Therefore, we find that the G ex B 2 mixing rule provides the best predictive power for the LLE over a wide range of temperature and pressure.

The use of high pressure in basic, materials, and life sciences

International Nuclear Information System (INIS)

Schilling, James S.

2000-01-01

Four of the most important applications of the high pressure technique in today's science are: (1) to help identify the materials which reside deep within our earth or other heavenly bodies and determine their properties, (2) to uncover underlying systematics and critically test theoretical models, (3) to synthesize novel and useful materials not readily available by other means, and (4) to determine the effect of pressure on living organisms and explore the conditions favorable for the origin of life itself. High pressure studies currently enjoy an increasing popularity which is fueled by recent advances in the notably difficult experimental techniques. In this paper I will attempt to capture some of the current excitement in this field by offering brief synopses of selected experiments in the basic, materials, and life sciences

Theory of superplastic flow in two-phase materials: roles of interphase-boundary dislocations, ledges, and diffusion

International Nuclear Information System (INIS)

Gittus, J.H.

1977-01-01

A new theory is developed to explain superplastic flow in two-phase materials. It is postulated that boundary-dislocations, piled up in dislocation-Interphase-Boundaries (IPBs) climb away into disordered regions of the IPB. Sliding then occurs at an IPB as dislocations glide toward the head of the pile up to replace those which have climbed into disordered regions of the boundary. An energy barrier which would otherwise render sliding virtually impossible on dislocation-IPBs can, it is shown, be largely eliminated if the dislocations glide in pairs. The disorder (actually an antiphase domain boundary) which is created by the passage of the leading dislocation is then repaired by passage of its successor. The threshold stress for superplastic flow is provisionally identified with the stress which pins IPB dislocations to boundary ledges. The activation energy is theoretically that for IPB diffusion. Good agreement is obtained between the theoretical equation for superplastic flow and the results of published experiments

Development of a high-pressure microbalance for hydrogen storage materials

DEFF Research Database (Denmark)

Vestbø, Andreas Peter; Jensen, Jens Oluf; Bjerrum, Niels

2007-01-01

Pressure-composition isotherms (PCI's) help to determine thermodynamic properties related to hydrogen uptake of materials. PCI's are normally obtained volumetrically with a Sieverts type apparatus or gravimetrically with a microbalance. A potential problem with the gravimetric technique is that t......Pressure-composition isotherms (PCI's) help to determine thermodynamic properties related to hydrogen uptake of materials. PCI's are normally obtained volumetrically with a Sieverts type apparatus or gravimetrically with a microbalance. A potential problem with the gravimetric technique...... of an electromagnetic microbalance, pressure resistant casing for up to 100 bar hydrogen, a flow system for hydrogen and inert gas, heating elements for temperature control, and software for controlling the system. Thermal convection effects are observed and dampened by heating on both the sample and a counterweight...

Pressure transmission area and maximum pressure transmission of different thermoplastic resin denture base materials under impact load.

Science.gov (United States)

Nasution, Hubban; Kamonkhantikul, Krid; Arksornnukit, Mansuang; Takahashi, Hidekazu

2018-01-01

The purposes of the present study were to examine the pressure transmission area and maximum pressure transmission of thermoplastic resin denture base materials under an impact load, and to evaluate the modulus of elasticity and nanohardness of thermoplastic resin denture base. Three injection-molded thermoplastic resin denture base materials [polycarbonate (Basis PC), ethylene propylene (Duraflex), and polyamide (Valplast)] and one conventional heat-polymerized acrylic resin (PMMA, SR Triplex Hot) denture base, all with a mandibular first molar acrylic resin denture tooth set in were evaluated (n=6). Pressure transmission area and maximum pressure transmission of the specimens under an impact load were observed by using pressure-sensitive sheets. The modulus of elasticity and nanohardness of each denture base (n=10) were measured on 15×15×15×3mm 3 specimen by using an ultramicroindentation system. The pressure transmission area, modulus of elasticity, and nanohardness data were statistically analyzed with 1-way ANOVA, followed by Tamhane or Tukey HSD post hoc test (α=.05). The maximum pressure transmission data were statistically analyzed with Kruskal-Wallis H test, followed by Mann-Whitney U test (α=.05). Polymethyl methacrylate showed significantly larger pressure transmission area and higher maximum pressure transmission than the other groups (Pelasticity and nanohardness among the four types of denture bases (Pelasticity and nanohardness of each type of denture base were demonstrated. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

TEM examination of irradiated zircaloy-2 pressure tube material

International Nuclear Information System (INIS)

Srivastava, D.; Tewari, R.; Dey, G.K.; Sharma, B.P.; Sah, D.N.; Banerjee, Suparna; Sahoo, K.C.

2005-09-01

In the present work, microstructure of the zircaloy-2 pressure tube material irradiated in the Indian Pressurized Heavy Water RAPP-1. Reactor (PHWR) has been examined for the first time using transmission electron microscope (TEM). The samples were obtained from a zircaloy-2 pressure tube, which had been in operation in the high flux region of Rajasthan Atomic Power Station Unit -1, for a period for 6.77 effective full power years (EFPYs) and expected to have a cumulative radiation damage of about 3 dpa. In this study irradiated microstructure has been characterized and compared it with the microstructure of the unirradiated pressure tube samples. The effect of irradiation on the hydriding behaviour is also studied. (author)

Materials control and accounting (MC and A): the evolutionary pressures

International Nuclear Information System (INIS)

Shipley, J.P.

1983-01-01

Nuclear materials control and accounting systems are subject to pressures of both regulatory and institutional natures. This fact, coupled with the emergence of new technology, is causing evolutionary changes in materials control and accounting systems. These changes are the subject of this paper

Pressurized water reactor simulator. Workshop material

International Nuclear Information System (INIS)

2003-01-01

The International Atomic Energy Agency (IAEA) has established an activity in nuclear reactor simulation computer programs to assist its Member States in education. The objective is to provide, for a variety of advanced reactor types, insight and practice in their operational characteristics and their response to perturbations and accident situations. To achieve this, the IAEA arranges for the development and distribution of simulation programs and educational material and sponsors courses and workshops. The workshops are in two parts: techniques and tools for reactor simulator development; and the use of reactor simulators in education. Workshop material for the first part is covered in the IAEA Training Course Series No. 12, 'Reactor Simulator Development' (2001). Course material for workshops using a WWER- 1000 reactor department simulator from the Moscow Engineering and Physics Institute, the Russian Federation is presented in the IAEA Training Course Series No. 21 'WWER-1000 Reactor Simulator' (2002). Course material for workshops using a boiling water reactor simulator developed for the IAEA by Cassiopeia Technologies Incorporated of Canada (CTI) is presented in the IAEA publication: Training Course Series No.23 'Boiling Water Reactor Simulator' (2003). This report consists of course material for workshops using a pressurized water reactor simulator

High-Reynolds-number turbulent-boundary-layer wall-pressure fluctuations with dilute polymer solutions

Science.gov (United States)

Elbing, Brian R.; Winkel, Eric S.; Ceccio, Steven L.; Perlin, Marc; Dowling, David R.

2010-08-01

Wall-pressure fluctuations were investigated within a high-Reynolds-number turbulent boundary layer (TBL) modified by the addition of dilute friction-drag-reducing polymer solutions. The experiment was conducted at the U.S. Navy's Large Cavitation Channel on a 12.9 m long flat-plate test model with the surface hydraulically smooth (k+<0.2) and achieving downstream-distance-based Reynolds numbers to 220×106. The polymer (polyethylene oxide) solution was injected into the TBL through a slot in the surface. The primary flow diagnostics were skin-friction drag balances and an array of flush-mounted dynamic pressure transducers 9.8 m from the model leading edge. Parameters varied included the free-stream speed (6.7, 13.4, and 20.2 m s-1) and the injection condition (polymer molecular weight, injection concentration, and volumetric injection flux). The behavior of the pressure spectra, convection velocity, and coherence, regardless of the injection condition, were determined primarily based on the level of drag reduction. Results were divided into two regimes dependent on the level of polymer drag reduction (PDR), nominally separated at a PDR of 40%. The low-PDR regime is characterized by decreasing mean-square pressure fluctuations and increasing convection velocity with increasing drag reduction. This shows that the decrease in the pressure spectra with increasing drag reduction is due in part to the moving of the turbulent structures from the wall. Conversely, with further increases in drag reduction, the high-PDR regime has negligible variation in the mean-squared pressure fluctuations and convection velocity. The convection velocity remains constant at approximately 10% above the baseline-flow convection velocity, which suggests that the turbulent structures no longer move farther from the wall with increasing drag reduction. In light of recent numerical work, the coherence results indicate that in the low-PDR regime, the turbulent structures are being elongated in

EIT-based fabric pressure sensing.

Science.gov (United States)

Yao, A; Yang, C L; Seo, J K; Soleimani, M

2013-01-01

This paper presents EIT-based fabric sensors that aim to provide a pressure mapping using the current carrying and voltage sensing electrodes attached to the boundary of the fabric patch. Pressure-induced shape change over the sensor area makes a change in the conductivity distribution which can be conveyed to the change of boundary current-voltage data. This boundary data is obtained through electrode measurements in EIT system. The corresponding inverse problem is to reconstruct the pressure and deformation map from the relationship between the applied current and the measured voltage on the fabric boundary. Taking advantage of EIT in providing dynamical images of conductivity changes due to pressure induced shape change, the pressure map can be estimated. In this paper, the EIT-based fabric sensor was presented for circular and rectangular sensor geometry. A stretch sensitive fabric was used in circular sensor with 16 electrodes and a pressure sensitive fabric was used in a rectangular sensor with 32 electrodes. A preliminary human test was carried out with the rectangular sensor for foot pressure mapping showing promising results.

EIT-Based Fabric Pressure Sensing

Directory of Open Access Journals (Sweden)

A. Yao

2013-01-01

Full Text Available This paper presents EIT-based fabric sensors that aim to provide a pressure mapping using the current carrying and voltage sensing electrodes attached to the boundary of the fabric patch. Pressure-induced shape change over the sensor area makes a change in the conductivity distribution which can be conveyed to the change of boundary current-voltage data. This boundary data is obtained through electrode measurements in EIT system. The corresponding inverse problem is to reconstruct the pressure and deformation map from the relationship between the applied current and the measured voltage on the fabric boundary. Taking advantage of EIT in providing dynamical images of conductivity changes due to pressure induced shape change, the pressure map can be estimated. In this paper, the EIT-based fabric sensor was presented for circular and rectangular sensor geometry. A stretch sensitive fabric was used in circular sensor with 16 electrodes and a pressure sensitive fabric was used in a rectangular sensor with 32 electrodes. A preliminary human test was carried out with the rectangular sensor for foot pressure mapping showing promising results.

Reactor pressure boundary material - A study on evaluation and improvement of non-radiational characteristics low alloy steel weld

Energy Technology Data Exchange (ETDEWEB)

Lee, C. H.; Kim, K. S.; Ahn, H. J. [Hanyang University, Seoul (Korea)

2000-04-01

Metallurgical factors influencing on the toughness of the Intercritically Reheated Coarse-Grained Heat Affected Zone (ICCGHAZ) of multiple welded SA508-c1.3 Reactor Pressure vessel steel was evaluated. The ICCGAZ is formed when the CGHZ is reheated to the intercritical temperature range(between A{sub C1} and A{sub C3} temperature) in which {gamma} phase and {alpha} phase coexist. During heating, austenite was formed along the prior austenite grain boundaries and lath interface. On cooling, the newly formed austenite was transformed into bainite and/or martensite. The newly formed martensite always included some retained austenite(M-A constituents). The characteristics(amount, hardness, density, and size) of M-A constituents were found to be strongly associated with the last pass peak temperature and cooling time ({delta} t{sub 8/592)}). Toughness in the ICCGHAZ was deteriorated with increasing amount of M-A constituents of with was increased with increasing the last peak temperature within the intercritical temperature range. Meanwhile, for the same intercritical peak temperature, toughness decreased with increasing cooling time. When cooling time was short, the dominant factor influencing on the toughness of the ICCGHAZ was amount of M-A constituents. However, when the cooling time was long, the dominant factor was found to be the hardness difference between M-A constituents and softened matrix (tempered martensite). When the restraint was applied, restraint didn't affect on transformation temperature of martensite. But the transformation in austenite to banitic ferrite was found to be greatly affected. This austenited {gamma}-bainitic phase transformation was lowered hardness but raised toughness. Slightly, especially, when the cooling rate was relatively fast, toughness was greatly improved, but a longer cooling time did not change the characteristics considerably. 23 refs., 81 figs., 7 tabs. (Author)

An analytical model for dispersion of material in the atmospheric planetary boundary layer in presence of precipitation

International Nuclear Information System (INIS)

Mayhoub, A.B.; Etman, S.M.

1985-05-01

An analytical model for the dispersion of particulates and finely divided material released into the atmosphere near the ground is presented. The possible precipitation when the particles are dense enough and large enough to have deposition velocity, is taken into consideration. The model is derived analytically in the mixing layer or Ekman boundary layer where the mixing process is a direct consequence of turbulent and convective motions generated in the boundary layer. (author)

Beta limitation of matter-antimatter boundary layers

International Nuclear Information System (INIS)

Lehnert, B.

1987-08-01

A model has earlier been proposed for a boundary layer which separates a cloud of matter from one of antimatter in a magnetized ambiplasma. In this model steady pressure equilibrium ceases to exist when a certain beta limit is exceeded. The latter is defined as the ratio between the ambiplasma and magnetic field pressures which balance each other in the boundary layer. Thus, at an increasing density, the high-energy particles created by annihilation within the layer are 'pumped up' to a pressure which cannot be balanced by a given magnetic field. The boundary layer then 'disrupts'. The critical beta limit thus obtained falls within the observed parameter ranges of galaxies and other large cosmical objects. Provided that the considered matter-antimatter balance holds true, this limit is thus expected to impose certain existence conditions on matter-antimatter boundary layers. Such a limitation may apply to certain cosmical objects and cosmological models. The maximum time scale for the corresponding disruption development has been estimated to be in the range from about 10 -4 to 10 2 seconds for boundary layers at ambiplasma particle densities in the range from 10 4 to 10 -2 m -3 , respectively. (author)

Stability of spatially developing boundary layers

Science.gov (United States)

Govindarajan, Rama

1993-07-01

A new formulation of the stability of boundary-layer flows in pressure gradients is presented, taking into account the spatial development of the flow. The formulation assumes that disturbance wavelength and eigenfunction vary downstream no more rapidly than the boundary-layer thickness, and includes all terms of O(1) and O(R(exp -1)) in the boundary-layer Reynolds number R. Although containing the Orr-Sommerfeld operator, the present approach does not yield the Orr-Sommerfeld equation in any rational limit. In Blasius flow, the present stability equation is consistent with that of Bertolotti et al. (1992) to terms of O(R(exp -1)). For the Falkner-Skan similarity solutions neutral boundaries are computed without the necessity of having to march in space. Results show that the effects of spatial growth are striking in flows subjected to adverse pressure gradients.

High-pressure torsion for new hydrogen storage materials.

Science.gov (United States)

Edalati, Kaveh; Akiba, Etsuo; Horita, Zenji

2018-01-01

High-pressure torsion (HPT) is widely used as a severe plastic deformation technique to create ultrafine-grained structures with promising mechanical and functional properties. Since 2007, the method has been employed to enhance the hydrogenation kinetics in different Mg-based hydrogen storage materials. Recent studies showed that the method is effective not only for increasing the hydrogenation kinetics but also for improving the hydrogenation activity, for enhancing the air resistivity and more importantly for synthesizing new nanostructured hydrogen storage materials with high densities of lattice defects. This manuscript reviews some major findings on the impact of HPT process on the hydrogen storage performance of different titanium-based and magnesium-based materials.

The needs of the nuclear pressure boundary industry in the 1990s

International Nuclear Information System (INIS)

Amano, Makio

1990-01-01

In order to meet the increasing demand for electric power, it is recognized in Japan that light water reactors (BWR and PWR) will continue to play an important role in the 1990s. Some technical developments and research are considered necessary in the 1990s for the further establishment of the structural integrity of the light water reactors. Based on a review of a series of problems experienced at pressure boundaries, the desired improvements and the prospects for their achievement are discussed in the following 3 fields. (1) Improvements in order to attain availability: some new techniques and the importance of preventive maintenance, (2) Nuclear plant life extension: The integrity assessment method of aged plants and the development of diagnostic and monitoring techniques, and (3) Human factor considerations in the NSSS Vendor: Technology transfer to the next generation. (orig.)

Kinetic boundaries and phase transformations of ice i at high pressure

Science.gov (United States)

Wang, Yu; Zhang, Huichao; Yang, Xue; Jiang, Shuqing; Goncharov, Alexander F.

2018-01-01

Raman spectroscopy in diamond anvil cells has been employed to study phase boundaries and transformation kinetics of H2O ice at high pressures up to 16 GPa and temperatures down to 15 K. Ice i formed at nearly isobaric cooling of liquid water transforms on compression to high-density amorphous (HDA) ice at 1.1-3 GPa at 15-100 K and then crystallizes in ice vii with the frozen-in disorder (ice vii') which remains stable up to 14.1 GPa at 80 K and 15.9 GPa at 100 K. Unexpectedly, on decompression of ice vii', it transforms to ice viii in its domain of metastability, and then it relaxes into low-density amorphous (LDA) ice on a subsequent pressure release and warming up. On compression of ice i at 150-170 K, ice ix is crystallized and no HDA ice is found; further compression of ice ix results in the sequential phase transitions to stable ices vi and viii. Cooling ice i to 210 K at 0.3 GPa transforms it to a stable ice ii. Our extensive investigations provide previously missing information on the phase diagram of water, especially on the kinetic paths that result in formation of phases which otherwise are not accessible; these results are keys for understanding the phase relations including the formation of metastable phases. Our observations inform on the ice modifications that can occur naturally in planetary environments and are not accessible for direct observations.

Impact of Compound Hydrate Dynamics on Phase Boundary Changes

Science.gov (United States)

Osegovic, J. P.; Max, M. D.

2006-12-01

Compound hydrate reactions are affected by the local concentration of hydrate forming materials (HFM). The relationship between HFM composition and the phase boundary is as significant as temperature and pressure. Selective uptake and sequestration of preferred hydrate formers (PF) has wide ranging implications for the state and potential use of natural hydrate formation, including impact on climate. Rising mineralizing fluids of hydrate formers (such as those that occur on Earth and are postulated to exist elsewhere in the solar system) will sequester PF before methane, resulting in a positive relationship between depth and BTU content as ethane and propane are removed before methane. In industrial settings the role of preferred formers can separate gases. When depressurizing gas hydrate to release the stored gas, the hydrate initial composition will set the decomposition phase boundary because the supporting solution takes on the composition of the hydrate phase. In other settings where hydrate is formed, transported, and then dissociated, similar effects can control the process. The behavior of compound hydrate systems can primarily fit into three categories: 1) In classically closed systems, all the material that can form hydrate is isolated, such as in a sealed laboratory vessel. In such systems, formation and decomposition are reversible processes with observed hysteresis related to mass or heat transfer limitations, or the order and magnitude in which individual hydrate forming gases are taken up from the mixture and subsequently released. 2) Kinetically closed systems are exposed to a solution mass flow across a hydrate mass. These systems can have multiple P-T phase boundaries based on the local conditions at each face of the hydrate mass. A portion of hydrate that is exposed to fresh mineralizing solution will contain more preferred hydrate formers than another portion that is exposed to a partially depleted solution. Examples of kinetically closed

Anisotropic deformation of Zr–2.5Nb pressure tube material at high temperatures

Energy Technology Data Exchange (ETDEWEB)

Fong, R.W.L., E-mail: fongr@aecl.ca [Fuel and Fuel Channel Safety Branch, Atomic Energy of Canada Limited, Chalk River Nuclear Laboratories, Chalk River, Ontario (Canada)

2013-09-15

Zr–2.5Nb alloy is used for the pressure tubes in CANDU® reactor fuel channels. In reactor, the pressure tube normally operates at 300 °C and experiences a primary coolant fluid internal pressure of approximately 10 MPa. Manufacturing and processing procedures generate an anisotropic state in the pressure tube which makes the tube stronger in the hoop (transverse) direction than in the axial (longitudinal) direction. This anisotropy condition is present for temperatures less than 500 °C. During postulated accident conditions where the material temperature could reach 1000 °C, it might be assumed that the high temperature and subsequent phase change would reduce the inherent anisotropy, and thus affect the deformation behaviour (ballooning) of the pressure tube. From constant-load, rapid-temperature-ramp, uniaxial deformation tests, the deformation rate in the longitudinal direction of the tube behaves differently than the deformation rate in the transverse direction of the tube. This anisotropic mechanical behaviour appears to persist at temperatures up to 1000 °C. This paper presents the results of high-temperature deformation tests using longitudinal and transverse specimens taken from as-received Zr–2.5Nb pressure tubes. It is shown that the anisotropic deformation behaviour observed at high temperatures is largely due to the stable crystallographic texture of the α-Zr phase constituent in the material that was previously observed by neutron diffraction measurements during heating at temperatures up to 1050 °C. The deformation behaviour is also influenced by the phase transformation occurring at high temperatures during heating. The effects of texture and phase transformation on the anisotropic deformation of as-received Zr–2.5Nb pressure tube material are discussed in the context of the tube ballooning behaviour. Because of the high temperatures in postulated accident scenarios, any irradiation damage will be annealed from the pressure tube material

F-8 supercritical wing flight pressure, Boundary layer, and wake measurements and comparisons with wind tunnel data

Science.gov (United States)

Montoya, L. C.; Banner, R. D.

1977-01-01

Data for speeds from Mach 0.50 to Mach 0.99 are presented for configurations with and without fuselage area-rule additions, with and without leading-edge vortex generators, and with and without boundary-layer trips on the wing. The wing pressure coefficients are tabulated. Comparisons between the airplane and model data show that higher second velocity peaks occurred on the airplane wing than on the model wing. The differences were attributed to wind tunnel wall interference effects that caused too much rear camber to be designed into the wing. Optimum flow conditions on the outboard wing section occurred at Mach 0.98 at an angle of attack near 4 deg. The measured differences in section drag with and without boundary-layer trips on the wing suggested that a region of laminar flow existed on the outboard wing without trips.

Materials characterization for advanced pressurized water reactors: Pt. 2

International Nuclear Information System (INIS)

Little, E.A.; Gage, G.

1994-01-01

A compilation and overview is presented of the experimental techniques available for characterization of the microstructural changes induced by neutron irradiation of PWR pressure vessel steels, and directed towards monitoring of embrittlement processes by examination of surveillance samples from advanced reactor systems. The microstructural features of significance include copper precipitation, dislocation loop and/or microvoid matrix damage and grain boundary solute segregation. The techniques of transmission electron microscopy, field-emission gun scanning transmission electron microscopy, small angle neutron scattering, positron annihilation and field-ion microscopy have all developed to a degree of sophistication such that they are capable of providing detailed microstructural information in these areas, and afford considerable insight into embrittlement processes when used in combination. (author)

Topical study on IRS events involving foreign material intrusion in plant systems. First issue. Report of a consultants meeting. Working material

International Nuclear Information System (INIS)

1997-01-01

Recent exchange of operational safety experience among countries, within the framework of the IRS, revealed a noticeable increase in incidents involving foreign material intrusion (FMI) in nuclear power plant systems. These incidents appeared to have safety impact, sometimes widespread, on many systems and components, including the reactor core, control rods, the secondary side, and other support systems such as the electrical, air, and water systems. Notwithstanding the economic penalties and the operational problems that can arise from the FMI, many events indicated severe component damages, challenges to safety systems and to fuel integrity. Difficulties encountered with the removal of foreign material present further challenges due to the long term effects of such material remaining in the system and interacting with either fuel cladding, with the potential of releasing fission products in coolant systems, or with the system pressure boundary with the potential for material wear and sudden failure of the pressure boundary. The FMI topic was, therefore, one of a number of topics that was recommended by the TCM in 1996 for investigation. A consultant meeting was held at the IAEA during the period 14-18 April 1997 to address this topic. Figs

Subgroup report on grain boundary and interphase boundary structure and properties

International Nuclear Information System (INIS)

Balluffi, R.W.; Cannon, R.M.; Clarke, D.R.; Heuer, A.H.; Ho, P.S.; Kear, B.H.; Vitek, V.; Weertman, J.R.; White, C.L.

1979-01-01

In many high temperature structural applications, the performance characteristics of a materials system are largely controlled by the properties of its grain and interphase boundaries. Failure in creep and fatigue frequently occurs by cavitation, or cracking along grain boundaries. In a few special cases, this failure problem has been overcome by directional alignment of grain and interphase boundaries by various types of metallurgical processing such as directional solidification and directional recrystallization. A good example is to be found in the application of directionally aligned structures in high performance gas-turbine airfoils. However, where fine, equiaxed grain structures are desirable, other methods of controlling grain boundary properties have been developed. Important among these has been the introduction of improvements in primary melting practices, designed to control important impurities. This is of decisive importance because even traces of certain impurity elements present in grain boundaries in high temperature materials can seriously affect properties. Impurities are deleterious and need to be removed. However, in certain cases, (e.g., creep fracture) controlled impurity additions can be beneficial and result in improved properties

Superplasticity of Inconel 718 after processing by high-pressure sliding (HPS)

Czech Academy of Sciences Publication Activity Database

Takizawa, Y.; Kajita, T.; Král, Petr; Masuda, T.; Watanabe, K.; Yumoto, M.; Otagiri, Y.; Sklenička, Václav; Horita, Z.

2017-01-01

Roč. 682, JAN (2017), s. 603-612 ISSN 0921-5093 Institutional support: RVO:68081723 Keywords : High-pressure sliding (HPS) * Severe plastic deformation (SPD) * Ni-based superalloy * Superplasticity * Grain boundary sliding * Lattice diffusion Subject RIV: JG - Metallurgy OBOR OECD: Materials engineering Impact factor: 3.094, year: 2016

Progress in understanding the mechanical behavior of pressure-vessel materials at elevated temperatures

International Nuclear Information System (INIS)

Swindeman, R.W.; Brinkman, C.R.

1981-01-01

Progress during the 1970's on the production of high-temperature mechanical properties data for pressure vessel materials was reviewed. The direction of the research was toward satisfying new data requirements to implement advances in high-temperature inelastic design methods. To meet these needs, servo-controlled testing machines and high-resolution extensometry were developed to gain more information on the essential behavioral features of high-temperature alloys. The similarities and differences in the mechanical response of various pressure vessel materials were identified. High-temperature pressure vessel materials that have received the most attention included Type 304 stainless steel, Type 316 stainless steel, 2 1/4 Cr-1 Mo steel, alloy 800H, and Hastelloy X

New perspectives on potential hydrogen storage materials using high pressure.

Science.gov (United States)

Song, Yang

2013-09-21

In addressing the global demand for clean and renewable energy, hydrogen stands out as the most suitable candidate for many fuel applications that require practical and efficient storage of hydrogen. Supplementary to the traditional hydrogen storage methods and materials, the high-pressure technique has emerged as a novel and unique approach to developing new potential hydrogen storage materials. Static compression of materials may result in significant changes in the structures, properties and performance that are important for hydrogen storage applications, and often lead to the formation of unprecedented phases or complexes that have profound implications for hydrogen storage. In this perspective article, 22 types of representative potential hydrogen storage materials that belong to four major classes--simple hydride, complex hydride, chemical hydride and hydrogen containing materials--were reviewed. In particular, their structures, stabilities, and pressure-induced transformations, which were reported in recent experimental works together with supporting theoretical studies, were provided. The important contextual aspects pertinent to hydrogen storage associated with novel structures and transitions were discussed. Finally, the summary of the recent advances reviewed and the insight into the future research in this direction were given.

Rankine earth pressure theory considering microstructure of porous materials

Science.gov (United States)

Li, Junhu; Xue, Wei; Zhang, Chao; Zhang, Wenchao; Xu, Riqing

2017-11-01

Soil as an engineering material has very complex properties, such as non-continuous, non-uniformity and nonlinear mechanical. In a certain extent, macroscopic properties of soil are affected by the changes of the microstructure. And microscopic porosity of soft clay and its influencing factors, the relationship between macro and micro porosity, the average contact area rate and its influencing factors are studied. Some mechanics problems were analyzed by using the relationship between macro-porosity and the average contact area rate. Combining soil lateral stress transfer principle, a calculation theory of earth pressure considering soil contact area was got. The possible reason of the differences between earth pressure and the actual monitoring earth pressure was analyzed by the case.

Self-diffusion and heterodiffusion in Zr-2.5%Nb α/β interfaces comparison with grain boundary diffusion in α-Zr

International Nuclear Information System (INIS)

Iribarren, M.J.; Dyment, F.

1991-01-01

Conventional radioactive tracer section techniques were used to make an experimental determination of diffusion parameters for Zr, Nb and Ni along the α/β boundary interfaces of Zr-2.5%Nb and comparing them with those for Zr, Nb and Co in α-Zr grain boundaries. Both determinations were made for a wide range of temperatures, including reactor working temperatures. Different materials were used for this purpose, both specially prepared alloys for diffusion experiments and part of the material from the actual pressure tubes. Different stabilizing thermal treatments were performed and results were analyzed based on the different morphologies obtained. (Author) [es

Improvement of corrosion resistance in austenitic stainless steel by grain boundary character distribution control

International Nuclear Information System (INIS)

Wang, Yun; Kaneda, Junya; Kasahara, Shigeki; Shigenaka, Naoto

2012-01-01

Strauss test, Coriou test and Huey test were conducted on a Type 316L austenitic stainless steel. Improvement in grain boundary corrosion resistance was verified after raising low Σ coincidence site lattice (CSL) grain boundary (GB) frequency by controlling grain boundary character distribution (GBCD). During crevice corrosion test under gamma-ray irradiation, initiation frequency of GB corrosion after GBCD controlled specimens decreased to 1/10 of GBCD uncontrolled counterpart along with lower depth of corrosion. Stress corrosion cracking (SCC) propagation rate of GBCD controlled specimen decreased to less than 1/2 of GBCD uncontrolled specimen in high temperature and high pressure water. Based on these results, we expect that GBCD control will improve corrosion resistance of austenitic material in a wide range of application and environment. (author)

Diffusion-accomodated rigid-body translations along grain boundaries in nanostructured materials

International Nuclear Information System (INIS)

Bachurin, D.V.; Nazarov, A.A.; Shenderova, O.A.; Brenner, D.W.

2003-01-01

A model for the structural relaxation of grain boundaries (GBs) in nanostructured materials (NSMs) by diffusion-accommodated rigid body translations along GBs is proposed. The model is based on the results of recent computer simulations that have demonstrated that the GBs in NSMs retain a high-energy structure with random translational states due to severe geometrical constraints applied from neighboring grains (J. Appl. Phys. 78 (1995) 847; Scripta Metall. Mater. 33 (1995) 1245). The shear stresses within a GB caused by non-optimized rigid-body translations (RBTs) can be accommodated by diffusive flow of atoms along a GB. This mechanism is particularly important for low-angle and vicinal GBs, the energy of which noticeably depends on the rigid body translations. At moderate and high temperatures the model yields relaxation times that are very short and therefore GBs in NSMs can attain an equilibrium structure with optimized rigid body translations. In contrast, at room temperature the model predicts that in some metals non-equilibrium structures can be preserved for a long time, which may result in the observation of grain boundary structures different from those in coarse grained polycrystals

Swelling pressures of a potential buffer material for high-level waste repository

International Nuclear Information System (INIS)

Lee, Jae Owan; Cho, Won Jin; Chun, Kwan Sik

1999-01-01

The swelling pressure of a potential buffer material was measured and the effect of dry density, bentonite content and initial water content on the swelling pressure was investigated to provide the information for the selection of buffer material in a high-level waste repository. Swelling tests were carried out according to Box-Behnken's experimental design. Measured swelling pressures were in the wide range of 0.7 Kg/cm 2 to 190.2 Kg/cm 2 under given experimental conditions. Based upon the experimental data, a 3-factor polynomial swelling model was suggested to analyze the effect of dry density, bentonite content and initial water content on the swelling pressure. The swelling pressure increased with an increase in the dry density and bentonite content, while it decreased with increasing the initial water content and, beyond about 12 wt.% of the initial water content, levelled to nearly constant value. (author). 21 refs., 10 figs., 4 tabs

Permeability changes induced by microfissure closure and opening in tectonized materials. Effect on slope pore pressure regime.

Science.gov (United States)

De la Fuente, Maria; Vaunat, Jean; Pedone, Giuseppe; Cotecchia, Federica; Sollecito, Francesca; Casini, Francesca

2015-04-01

Tectonized clays are complex materials characterized by several levels of structures that may evolve during load and wetting/drying processes. Some microstructural patterns, as microfissures, have a particular influence on the value of permeability which is one of the main factors controlling pore pressure regime in slopes. In this work, the pore pressure regime measured in a real slope of tectonized clay in Southern Italy is analyzed by a numerical model that considers changes in permeability induced by microfissure closure and opening during the wetting and drying processes resulting from climatic actions. Permeability model accounts for the changes in Pore Size Distribution observed by Microscopy Intrusion Porosimetry. MIP tests are performed on representative samples of ground in initial conditions ("in situ" conditions) and final conditions (deformed sample after applying a wetting path that aims to reproduce the saturation of the soil under heavy rains). The resulting measurements allow for the characterization at microstructural level of the soil, identifying the distribution of dominant families pores in the sample and its evolution under external actions. Moreover, comparison of pore size density functions allows defining a microstructural parameter that depends on void ratio and degree of saturation and controls the variation of permeability. Model has been implemented in a thermo-hydro-mechanical code provided with a special boundary condition for climatic actions. Tool is used to analyze pore pressure measurements obtained in the tectonized clay slope. Results are analyzed at the light of the effect that permeability changes during wetting and drying have on the pore pressure regime.

Role of boundary layer diffusion in vapor deposition growth of chalcogenide nanosheets: the case of GeS.

Science.gov (United States)

Li, Chun; Huang, Liang; Snigdha, Gayatri Pongur; Yu, Yifei; Cao, Linyou

2012-10-23

We report a synthesis of single-crystalline two-dimensional GeS nanosheets using vapor deposition processes and show that the growth behavior of the nanosheet is substantially different from those of other nanomaterials and thin films grown by vapor depositions. The nanosheet growth is subject to strong influences of the diffusion of source materials through the boundary layer of gas flows. This boundary layer diffusion is found to be the rate-determining step of the growth under typical experimental conditions, evidenced by a substantial dependence of the nanosheet's size on diffusion fluxes. We also find that high-quality GeS nanosheets can grow only in the diffusion-limited regime, as the crystalline quality substantially deteriorates when the rate-determining step is changed away from the boundary layer diffusion. We establish a simple model to analyze the diffusion dynamics in experiments. Our analysis uncovers an intuitive correlation of diffusion flux with the partial pressure of source materials, the flow rate of carrier gas, and the total pressure in the synthetic setup. The observed significant role of boundary layer diffusions in the growth is unique for nanosheets. It may be correlated with the high growth rate of GeS nanosheets, ~3-5 μm/min, which is 1 order of magnitude higher than other nanomaterials (such as nanowires) and thin films. This fundamental understanding of the effect of boundary layer diffusions may generally apply to other chalcogenide nanosheets that can grow rapidly. It can provide useful guidance for the development of general paradigms to control the synthesis of nanosheets.

Pressure Resistance Welding of High Temperature Metallic Materials

International Nuclear Information System (INIS)

Jerred, N.; Zirker, L.; Charit, I.; Cole, J.; Frary, M.; Butt, D.; Meyer, M.; Murty, K.L.

2010-01-01

Pressure Resistance Welding (PRW) is a solid state joining process used for various high temperature metallic materials (Oxide dispersion strengthened alloys of MA957, MA754; martensitic alloy HT-9, tungsten etc.) for advanced nuclear reactor applications. A new PRW machine has been installed at the Center for Advanced Energy Studies (CAES) in Idaho Falls for conducting joining research for nuclear applications. The key emphasis has been on understanding processing-microstructure-property relationships. Initial studies have shown that sound joints can be made between dissimilar materials such as MA957 alloy cladding tubes and HT-9 end plugs, and MA754 and HT-9 coupons. Limited burst testing of MA957/HT-9 joints carried out at various pressures up to 400 C has shown encouraging results in that the joint regions do not develop any cracking. Similar joint strength observations have also been made by performing simple bend tests. Detailed microstructural studies using SEM/EBSD tools and fatigue crack growth studies of MA754/HT-9 joints are ongoing.

Pressure induced superconductivity in the antiferromagnetic Dirac material BaMnBi2

OpenAIRE

Huimin Chen; Lin Li; Qinqing Zhu; Jinhu Yang; Bin Chen; Qianhui Mao; Jianhua Du; Hangdong Wang; Minghu Fang

2017-01-01

The so-called Dirac materials such as graphene and topological insulators are a new class of matter different from conventional metals and (doped) semiconductors. Superconductivity induced by doing or applying pressure in these systems may be unconventional, or host mysterious Majorana fermions. Here, we report a successfully observation of pressure-induced superconductivity in an antiferromagnetic Dirac material BaMnBi2 with T c of ~4?K at 2.6?GPa. Both the higher upper critical field, ? 0 H...

Experimental study on effects of inlet boundary layer thickness and boundary layer fence in a turbine cascade

International Nuclear Information System (INIS)

Jun, Y. M.; Chung, J. T.

2000-01-01

The working fluid from the combustor to the turbine stage of a gas turbine makes various boundary layer thickness. Since the inlet boundary layer thickness is one of the important factors that affect the turbine efficiency, It is necessary to investigate secondary flow and loss with various boundary layer thickness conditions. In the present study, the effect of various inlet boundary layer thickness on secondary flow and loss and the proper height of the boundary layer fences for various boundary layer thickness were investigated. Measurements of secondary flow velocity and total pressure loss within and downstream of the passage were taken under 5 boundary layer thickness conditions, 16, 36, 52, 69, 110mm. It was found that total pressure loss and secondary flow areas were increased with increase of thickness but they were maintained almost at the same position. At the following research about the boundary layer fences, 1/6, 1/3, 1/2 of each inlet boundary layer thickness and 12mm were used as the fence heights. As a result, it was observed that the proper height of the fences was generally constant since the passage vortex remained almost at the same position. Therefore once the geometry of a cascade is decided, the location of the passage vortex and the proper fence height are appeared to be determined at the same time. When the inlet boundary layer thickness is relatively small, the loss caused by the proper fence becomes bigger than end wall loss so that it dominates secondary loss. In these cases the proper fence height is decided not by the cascade geometry but by the inlet boundary layer thickness as previous investigations

Pressurized-water reactors

International Nuclear Information System (INIS)

Bush, S.H.

1983-03-01

An overview of the pressurized-water reactor (PWR) pressure boundary problems is presented. Specifically exempted will be discussions of problems with pumps, valves and steam generators on the basis that they will be covered in other papers. Pressure boundary reliability is examined in the context of real or perceived problems occurring over the past 5 to 6 years since the last IAEA Reliability Symposium. Issues explicitly covered will include the status of the pressurized thermal-shock problem, reliability of inservice inspections with emphasis on examination of the region immediately under the reactor pressure vessel (RPV) cladding, history of piping failures with emphasis on failure modes and mechanisms. Since nondestructive examination is the topic of one session, discussion will be limited to results rather than techniques

Application of Boundary Element Method in Galvanic Corrosion Analysis for Metallic Materials used in Nuclear Power Plant

International Nuclear Information System (INIS)

Zaifol Samsu; Muhamad Daud; Siti Radiah Mohd Kamarudin

2011-01-01

Boundary element method (BEM) is a numerical technique that used for modeling infinite domain as is the case for galvanic corrosion analysis. This paper presents the application of boundary element method for galvanic corrosion analysis between two different metallic materials. Aluminium (Al), and zinc (Zn) alloys were used separately coupled with the Carbon Steel (CS) in natural seawater. The measured conductivity of sea water is 30,800 μS/ cm at ambient temperature. Computer software system based on boundary element likes BEASY and ABAQUS can be used to accurately model and simulate the galvanic corrosion. However, the BEM based BEASY program will be used reasonably for predicting the galvanic current density distribution of coupled Al-CS and Zn-CS in this study. (author)

Thermoelastic analysis of non-uniform pressurized functionally graded cylinder with variable thickness using first order shear deformation theory(FSDT) and perturbation method

Science.gov (United States)

Khoshgoftar, M. J.; Mirzaali, M. J.; Rahimi, G. H.

2015-11-01

Recently application of functionally graded materials(FGMs) have attracted a great deal of interest. These materials are composed of various materials with different micro-structures which can vary spatially in FGMs. Such composites with varying thickness and non-uniform pressure can be used in the aerospace engineering. Therefore, analysis of such composite is of high importance in engineering problems. Thermoelastic analysis of functionally graded cylinder with variable thickness under non-uniform pressure is considered. First order shear deformation theory and total potential energy approach is applied to obtain the governing equations of non-homogeneous cylinder. Considering the inner and outer solutions, perturbation series are applied to solve the governing equations. Outer solution for out of boundaries and more sensitive variable in inner solution at the boundaries are considered. Combining of inner and outer solution for near and far points from boundaries leads to high accurate displacement field distribution. The main aim of this paper is to show the capability of matched asymptotic solution for different non-homogeneous cylinders with different shapes and different non-uniform pressures. The results can be used to design the optimum thickness of the cylinder and also some properties such as high temperature residence by applying non-homogeneous material.

Pressure sensor to determine spatial pressure distributions on boundary layer flows

Science.gov (United States)

Sciammarella, Cesar A.; Piroozan, Parham; Corke, Thomas C.

1997-03-01

The determination of pressures along the surface of a wind tunnel proves difficult with methods that must introduce devices into the flow stream. This paper presents a sensor that is part of the wall. A special interferometric reflection moire technique is developed and used to produce signals that measures pressure both in static and dynamic settings. The sensor developed is an intelligent sensor that combines optics and electronics to analyze the pressure patterns. The sensor provides the input to a control system that is capable of modifying the shape of the wall and preserve the stability of the flow.

DELINEATION OF BOUNDARY CONTOURS OF MINERAL RAW MATERIALS WITHIN THE DEPOSIT SPACE CONSIDERING THE QUALITY

Directory of Open Access Journals (Sweden)

Ivan Tomašić

1990-12-01

Full Text Available On the basis of performed explorations, in the phase of deposit preparation and development for exploitation the obtained results regarding the raw material quality were transfered to the surface. The results served both for the development and planning of deposit excavation dynamics and for the delineation of boundary contours by mineral raw materials within the deposit space considering the quality, The case presented in the article refers to the marl and limestone open pit for the cement industry, the »Partizan« near Split (the paper is published in Croatian.

Basic requirements of mechanical properties for nuclear pressure vessel materials in ASME-BPV code

International Nuclear Information System (INIS)

Ning Dong; Yao Weida

2011-01-01

The four basic aspects of strengths, ductility, toughness and fatigue strengths can be summarized for overall mechanical properties requirements of materials for nuclear pressure-retaining vessels in ASME-BPV code. These mechanical property indexes involve in the factors of melting, manufacture, delivery conditions, check or recheck for mechanical properties and chemical compositions, etc. and relate to degradation and damage accumulation during the use of materials. This paper specifically accounts for the basic requirements and theoretic basis of mechanical properties for nuclear pressure vessel materials in ASME-BPV code and states the internal mutual relationships among the four aspects of mechanical properties. This paper focuses on putting forward at several problems on mechanical properties of materials that shall be concerned about during design and manufacture for nuclear pressure vessels according to ASME-BPV code. (author)

Impact of interfacial imperfection on transverse wave in a functionally graded piezoelectric material structure with corrugated boundaries

Science.gov (United States)

Kumar Singh, Abhishek; Kumar, Santan; Kumari, Richa

2018-03-01

The propagation behavior of Love-type wave in a corrugated functionally graded piezoelectric material layered structure has been taken into account. Concretely, the layered structure incorporates a corrugated functionally graded piezoelectric material layer imperfectly bonded to a functionally graded piezoelectric material half-space. An analytical treatment has been employed to determine the dispersion relation for both cases of electrically open condition and electrically short condition. The phase velocity of the Love-type wave has been computed numerically and its dependence on the wave number has been depicted graphically for a specific type of corrugated boundary surfaces for both said conditions. The crux of the study lies in the fact that the imperfect bonding of the interface, the corrugated boundaries present in the layer, and the material properties of the layer and the half-space strongly influence the phase velocity of the Love-type wave. It can be remarkably noted that the imperfect bonding of the interface reduces the phase velocity of the Love-type wave significantly. As a special case of the problem, it is noticed that the procured dispersion relation for both cases of electrically open and electrically short conditions is in accordance with the classical Love wave equation.

Energy principle with included boundary conditions

International Nuclear Information System (INIS)

Lehnert, B.

1994-01-01

Earlier comments by the author on the limitations of the classical form of the extended energy principle are supported by a complementary analysis on the potential energy change arising from free-boundary displacements of a magnetically confined plasma. In the final formulation of the extended principle, restricted displacements, satisfying pressure continuity by means of plasma volume currents in a thin boundary layer, are replaced by unrestricted (arbitrary) displacements which can give rise to induced surface currents. It is found that these currents contribute to the change in potential energy, and that their contribution is not taken into account by such a formulation. A general expression is further given for surface currents induced by arbitrary displacements. The expression is used to reformulate the energy principle for the class of displacements which satisfy all necessary boundary conditions, including that of the pressure balance. This makes a minimization procedure of the potential energy possible, for the class of all physically relevant test functions which include the constraints imposed by the boundary conditions. Such a procedure is also consistent with a corresponding variational calculus. (Author)

Superconductivity in hydrogen-rich materials at high pressures

Energy Technology Data Exchange (ETDEWEB)

Drozdov, Alexander

2016-07-01

A room temperature superconductor is probably one of the most desired systems in solid state physics. The highest critical temperature (T{sub c}) that has been achieved so far is in the copper oxide system: 133 kelvin (K) at ambient pressure ([82]Schilling et al. 1993) and 160 K under pressure ([42]Gao et al. 1994). The nature of superconductivity in the cuprates and in the recently discovered iron-based superconductor family (T{sub c}=57 K) is still not fully understood. In contrast, there is a class of superconductors which is well-described by the Bardeen, Cooper, Schrieffer (BCS) theory - conventional superconductors. Great efforts were spent in searching for high-temperature (T{sub c} > 77 K) conventional superconductor but only T{sub c} = 39 K has been reached in MgB2 ([68]Nagamatsu et al. 2001). BCS theory puts no bounds for T{sub c} as follows from Eliashberg's formulation of BCS theory. T{sub c} can be high, if there is a favorable combination of high-frequency phonons, strong electron-phonon coupling, and a high density of states. It does not predict however in which materials all three parameters are large. At least it gives a clear indication that materials with light elements are favorable as light elements provide high frequencies in the phonon spectrum. The lightest element is hydrogen, and Ashcroft made a first prediction that metallic hydrogen will be a high-temperature superconductor ([6]Ashcroft 1968). As pressure of hydrogen metallization was too high (about 400-500 GPa) for experimental techniques then he proposed that compounds dominated by hydrogen (hydrides) also might be good high temperature superconductors ([6]Ashcroft 1968; [7]Ashcroft 2004). A lot of the followed calculations supported this idea. T{sub c} in the range of 50-235 kelvin was predicted for many hydrides. Unfortunately, only a moderate T{sub c} of 17 kelvin has been observed experimentally ([27]Eremets et al. 2008) so far. A goal of the present work is to find a

Estimates of the eigenvalues of operator arising in swelling pressure model

International Nuclear Information System (INIS)

Kanguzhin, Baltabek; Zhapsarbayeva, Lyailya

2016-01-01

Swelling pressures from materials confined by structures can cause structural deformations and instability. Due to the complexity of interactions between expansive solid and solid-liquid equilibrium, the forces exerting on retaining structures from swelling are highly nonlinear. This work is our initial attempt to study a simplistic spectral problem based on the Euler-elastic beam theory and some simplistic swelling pressure model. In this work estimates of the eigenvalues of some initial/boundary value problem for nonlinear Euler-elastic beam equation are obtained.

Development of metallic system multi-composite materials for compound environment and corrosion monitoring technology

International Nuclear Information System (INIS)

Kiuchi, Kiyoshi

1996-01-01

For the structural materials used for the pressure boundary of nuclear power plants and others, the long term durability over several decades under the compound environment, in which the action of radiation and the corrosion and erosion in the environment of use are superposed, is demanded. To its controlling factors, the secular change of materials due to irradiation ageing and the chemical and physical properties of extreme compound environment are related complicatedly. In the first period of this research, the development of the corrosion-resistant alloys with the most excellent adaptability to environments was carried out by the combination of new alloy design and alloy manufacturing technology. In the second period, in order to heighten the adaptability as the pressure boundary materials between different compound environments, the creation of metallic system multi-composite materials has been advanced. Also corrosion monitoring technique is being developed. The stainless steel for water-cooled reactors, the wear and corrosion-resistant superalloy for reactor core, the corrosion-resistant alloy and the metallic refractory material for reprocessing nitric acid reaction vessels are reported. (K.I.)

Nanocomposite Thermolectric Materials by High Pressure Powder Consolidation Manufacturing, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — In response to NASA's need to develop advanced nanostructured thermolectric materials, UTRON is proposing an innovative high pressure powder consolidation...

Nanocomposite Thermolectric Materials by High Pressure Powder Consolidation Manufacturing, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — In response to NASA's need to develop advanced nanostructured thermolectric materials, UTRON is proposing an innovative high pressure powder consolidation...

A new boundary control scheme for simultaneous achievement of H-mode and radiative cooling (SHC boundary)

International Nuclear Information System (INIS)

Ohyabu, N.

1995-05-01

We have proposed a new boundary control scheme (SHC boundary), which could allow simultaneous achievement of the H-mode type confinement improvement and radiative cooling with wide heat flux distribution. In our proposed configuration, a low m island layer sharply separates a plasma confining region from an open 'ergodic' boundary. The degree of openness in the ergodic boundary must be high enough to make the plasma pressure constant along the field line, which in turn separates low density plasma just outside the plasma confining region (the key external condition for achieving a good H-mode discharge) from very high density, cold radiative plasma near the wall (required for effective edge radiative cooling). Examples of such proposed SHC boundaries for Heliotron typed devices and tokamaks are presented. (author)

The inversion of relative shear rigidity in different material classes at megabar pressures

CERN Document Server

Brazhkin, V V

2002-01-01

The behaviour of elastic moduli of substances is analysed in the megabar pressure range. A new effect - inversion of the shear moduli and mechanical properties upon compression - is predicted for various classes of substances. The melting-curve data for different materials confirm the predicted phenomenon. The materials traditionally considered the softest, such as rare-gas solids and molecular substances, may become the hardest in the megabar range. This should be taken into account in developing experimental high-pressure techniques.

Aspects Concerning Modelling Contact Pressure of Polymeric Materials Used in Robotic Soft Elements

Directory of Open Access Journals (Sweden)

Florina-Carmen Ciornei

2015-06-01

Full Text Available Compliant materials are used in applications of robotics for final elements of robotic systems. Contact pressure between a spherical indenter and a linear viscoelastic halfspace is modeled for a cosine normal load. The Maxwell viscoelastic halfspace is described by relaxation function and creep function. For the working frequency domain, the material does not present obvious relaxation. Only for very low frequencies, the pressure variation presents a maximum during approaching delayed with respect to maximum force

NASA GRC's High Pressure Burner Rig Facility and Materials Test Capabilities

Science.gov (United States)

Robinson, R. Craig

1999-01-01

The High Pressure Burner Rig (HPBR) at NASA Glenn Research Center is a high-velocity. pressurized combustion test rig used for high-temperature environmental durability studies of advanced materials and components. The facility burns jet fuel and air in controlled ratios, simulating combustion gas chemistries and temperatures that are realistic to those in gas turbine engines. In addition, the test section is capable of simulating the pressures and gas velocities representative of today's aircraft. The HPBR provides a relatively inexpensive. yet sophisticated means for researchers to study the high-temperature oxidation of advanced materials. The facility has the unique capability of operating under both fuel-lean and fuel-rich gas mixtures. using a fume incinerator to eliminate any harmful byproduct emissions (CO, H2S) of rich-burn operation. Test samples are easily accessible for ongoing inspection and documentation of weight change, thickness, cracking, and other metrics. Temperature measurement is available in the form of both thermocouples and optical pyrometery. and the facility is equipped with quartz windows for observation and video taping. Operating conditions include: (1) 1.0 kg/sec (2.0 lbm/sec) combustion and secondary cooling airflow capability: (2) Equivalence ratios of 0.5- 1.0 (lean) to 1.5-2.0 (rich), with typically 10% H2O vapor pressure: (3) Gas temperatures ranging 700-1650 C (1300-3000 F): (4) Test pressures ranging 4-12 atmospheres: (5) Gas flow velocities ranging 10-30 m/s (50-100) ft/sec.: and (6) Cyclic and steady-state exposure capabilities. The facility has historically been used to test coupon-size materials. including metals and ceramics. However complex-shaped components have also been tested including cylinders, airfoils, and film-cooled end walls. The facility has also been used to develop thin-film temperature measurement sensors.

Pressure Retarded Osmosis and Forward Osmosis Membranes: Materials and Methods

Directory of Open Access Journals (Sweden)

May-Britt Hägg

2013-03-01

Full Text Available In the past four decades, membrane development has occurred based on the demand in pressure driven processes. However, in the last decade, the interest in osmotically driven processes, such as forward osmosis (FO and pressure retarded osmosis (PRO, has increased. The preparation of customized membranes is essential for the development of these technologies. Recently, several very promising membrane preparation methods for FO/PRO applications have emerged. Preparation of thin film composite (TFC membranes with a customized polysulfone (PSf support, electorspun support, TFC membranes on hydrophilic support and hollow fiber membranes have been reported for FO/PRO applications. These novel methods allow the use of other materials than the traditional asymmetric cellulose acetate (CA membranes and TFC polyamide/polysulfone membranes. This review provides an outline of the membrane requirements for FO/PRO and the new methods and materials in membrane preparation.

Investigation of turbulence models with compressibility corrections for hypersonic boundary flows

Directory of Open Access Journals (Sweden)

Han Tang

2015-12-01

Full Text Available The applications of pressure work, pressure-dilatation, and dilatation-dissipation (Sarkar, Zeman, and Wilcox models to hypersonic boundary flows are investigated. The flat plate boundary layer flows of Mach number 5–11 and shock wave/boundary layer interactions of compression corners are simulated numerically. For the flat plate boundary layer flows, original turbulence models overestimate the heat flux with Mach number high up to 10, and compressibility corrections applied to turbulence models lead to a decrease in friction coefficients and heating rates. The pressure work and pressure-dilatation models yield the better results. Among the three dilatation-dissipation models, Sarkar and Wilcox corrections present larger deviations from the experiment measurement, while Zeman correction can achieve acceptable results. For hypersonic compression corner flows, due to the evident increase of turbulence Mach number in separation zone, compressibility corrections make the separation areas larger, thus cannot improve the accuracy of calculated results. It is unreasonable that compressibility corrections take effect in separation zone. Density-corrected model by Catris and Aupoix is suitable for shock wave/boundary layer interaction flows which can improve the simulation accuracy of the peak heating and have a little influence on separation zone.

A measurement method for piezoelectric material properties under longitudinal compressive stress–-a compression test method for thin piezoelectric materials

International Nuclear Information System (INIS)

Kang, Lae-Hyong; Lee, Dae-Oen; Han, Jae-Hung

2011-01-01

We introduce a new compression test method for piezoelectric materials to investigate changes in piezoelectric properties under the compressive stress condition. Until now, compression tests of piezoelectric materials have been generally conducted using bulky piezoelectric ceramics and pressure block. The conventional method using the pressure block for thin piezoelectric patches, which are used in unimorph or bimorph actuators, is prone to unwanted bending and buckling. In addition, due to the constrained boundaries at both ends, the observed piezoelectric behavior contains boundary effects. In order to avoid these problems, the proposed method employs two guide plates with initial longitudinal tensile stress. By removing the tensile stress after bonding a piezoelectric material between the guide layers, longitudinal compressive stress is induced in the piezoelectric layer. Using the compression test specimens, two important properties, which govern the actuation performance of the piezoelectric material, the piezoelectric strain coefficients and the elastic modulus, are measured to evaluate the effects of applied electric fields and re-poling. The results show that the piezoelectric strain coefficient d 31 increases and the elastic modulus decreases when high voltage is applied to PZT5A, and the compression in the longitudinal direction decreases the piezoelectric strain coefficient d 31 but does not affect the elastic modulus. We also found that the re-poling of the piezoelectric material increases the elastic modulus, but the piezoelectric strain coefficient d 31 is not changed much (slightly increased) by re-poling

Grain boundary structure and properties

International Nuclear Information System (INIS)

Balluffi, R.W.

1979-01-01

An attempt is made to distinguish those fundamental aspects of grain boundaries which should be relevant to the problem of the time dependent fracture of high temperature structural materials. These include the basic phenomena which are thought to be associated with cavitation and cracking at grain boundaries during service and with the more general microstructural changes which occur during both processing and service. A very brief discussion of the current state of our knowledge of these fundamentals is given. Included are the following: (1) structure of ideal perfect boundaries; (2) defect structure of grain boundaries; (3) diffusion at grain boundaries; (4) grain boundaries as sources/sinks for point defects; (5) grain boundary migration; (6) dislocation phenomena at grain boundaries; (7) atomic bonding and cohesion at grain boundaries; (8) non-equilibrium properties of grain boundaries; and (9) techniques for studying grain boundaries

Material Fracture Characterization and Toughness Improving Technology Developments

International Nuclear Information System (INIS)

Lee, Bong Sang; Kim, M. C.; Lee, H. J. and others

2005-04-01

Reactor pressure boundary components including pressure vessel and piping are facing a severe aging condition that can degrade the physical-mechanical properties under neutron irradiation, high temperature, high pressure, and corrosive environments. In order to increase the safety of nuclear power plants, it is inevitable to improve the credibility and capability of evaluation technology based on the quantitative fracture mechanics for aging assessment of reactor components. Irradiation embrittlement is the primary aging mechanism of reactor pressure vessel and various techniques have been developed to predict the aging characteristics by using only small volume of irradiated materials. Material database of the domestic structural steels for KSNP's under reactor environments must be very important to play a role in developing an advanced material, in improving the safety of nuclear components, and also in expanding the nuclear industry abroad. This research project has been focused on developing an advanced technology of testing and analysis in the fracture mechanical point of view as well as acquiring test data and improving the performance of nuclear structural steels

Solution of problems with material nonlinearities with a coupled finite element/boundary element scheme using an iterative solver. Yucca Mountain Site Characterization Project

International Nuclear Information System (INIS)

Koteras, J.R.

1996-01-01

The prediction of stresses and displacements around tunnels buried deep within the earth is an important class of geomechanics problems. The material behavior immediately surrounding the tunnel is typically nonlinear. The surrounding mass, even if it is nonlinear, can usually be characterized by a simple linear elastic model. The finite element method is best suited for modeling nonlinear materials of limited volume, while the boundary element method is well suited for modeling large volumes of linear elastic material. A computational scheme that couples the finite element and boundary element methods would seem particularly useful for geomechanics problems. A variety of coupling schemes have been proposed, but they rely on direct solution methods. Direct solution techniques have large storage requirements that become cumbersome for large-scale three-dimensional problems. An alternative to direct solution methods is iterative solution techniques. A scheme has been developed for coupling the finite element and boundary element methods that uses an iterative solution method. This report shows that this coupling scheme is valid for problems where nonlinear material behavior occurs in the finite element region

Cluster formation in in-service thermally aged pressurizer welds

Science.gov (United States)

Lindgren, Kristina; Boåsen, Magnus; Stiller, Krystyna; Efsing, Pål; Thuvander, Mattias

2018-06-01

Thermal aging of reactor pressure vessel steel welds at elevated temperatures may affect the ductile-to-brittle transition temperature. In this study, unique weld material from a pressurizer, with a composition similar to that of the reactor pressure vessel, that has been in operation for 28 years at 345 °C is examined. Despite the relatively low temperature, the weld becomes hardened during operation. This is attributed to nanometre sized Cu-rich clusters, mainly located at Mo- and C-enriched dislocation lines and on boundaries. The welds have been characterized using atom probe tomography, and the characteristics of the precipitates/clusters is related to the hardness increase, giving the best agreement for the Russell-Brown model.

Materiality matters: Blurred boundaries and the domestication of functional foods.

Science.gov (United States)

Weiner, Kate; Will, Catherine

2015-06-01

Previous scholarship on novel foods, including functional foods, has suggested that they are difficult to categorise for both regulators and users. It is argued that they blur the boundary between 'food' and 'drug' and that uncertainties about the products create 'experimental' or 'restless' approaches to consumption. We investigate these uncertainties drawing on data about the use of functional foods containing phytosterols, which are licensed for sale in the EU for people wishing to reduce their cholesterol. We start from an interest in the products as material objects and their incorporation into everyday practices. We consider the scripts encoded in the physical form of the products through their regulation, production and packaging and find that these scripts shape but do not determine their use. The domestication of phytosterols involves bundling the products together with other objects (pills, supplements, foodstuffs). Considering their incorporation into different systems of objects offers new understandings of the products as foods or drugs. In their accounts of their practices, consumers appear to be relatively untroubled by uncertainties about the character of the products. We conclude that attending to materials and practices offers a productive way to open up and interrogate the idea of categorical uncertainties surrounding new food products.

Constructing integrable full-pressure full-current free-boundary stellarator magnetohydrodynamic equilibrium solutions

International Nuclear Information System (INIS)

Hudson, S.R.

2002-01-01

For stellarators to be feasible candidates for fusion power stations it is essential that the magnetic field lines lie on nested flux surfaces; however, the lack of a continuous symmetry implies that magnetic islands, caused by Pfirsch-Schlueter currents, diamagnetic currents and resonant coil fields, are guaranteed to exist. The challenge is to design the plasma and coils such that these effects cancel. Magnetic islands in free-boundary full-pressure full-current stellarator magnetohydrodynamic equilibria are suppressed using a procedure based on the PIES code [Comp. Phys. Comm., 43:157, 1986] which iterates the equilibrium equations to obtain the plasma equilibrium. At each iteration, changes to a Fourier representation of the coil geometry are made to cancel resonant fields produced by the plasma. The changes are constrained to lie in the nullspace of certain measures of engineering acceptability and kink stability. As the iterations continue, the coil geometry and the plasma simultaneously converge to an equilibrium in which the island content is negligible. The method is applied to a candidate plasma and coil design for NCSX [Phys. Plas., 7:1911, 2000]. (author)

Computer system for International Reactor Pressure Vessel Materials Database support

International Nuclear Information System (INIS)

Arutyunjan, R.; Kabalevsky, S.; Kiselev, V.; Serov, A.

1997-01-01

This report presents description of the computer tools for support of International Reactor Pressure Vessel Materials Database developed at IAEA. Work was focused on raw, qualified, processed materials data, search, retrieval, analysis, presentation and export possibilities of data. Developed software has the following main functions: provides software tools for querying and search of any type of data in the database; provides the capability to update the existing information in the database; provides the capability to present and print selected data; provides the possibility of export on yearly basis the run-time IRPVMDB with raw, qualified and processed materials data to Database members; provides the capability to export any selected sets of raw, qualified, processed materials data

Pressure effects on thermal conductivity and expansion of geologic materials

International Nuclear Information System (INIS)

Sweet, J.N.

1979-02-01

Through analysis of existing data, an estimate is made of the effect of pressure or depth on the thermal conductivity and expansion of geologic materials which could be present in radioactive waste repositories. In the case of homogeneous dense materials, only small shifts are predicted to occur at depths less than or equal to 3 km, and these shifts will be insignificant as compared with those caused by temperature variations. As the porosity of the medium increases, the variation of conductivity and expansion with pressure becomes greater, with conductivity increasing and expansion decreasing as pressure increases. The pressure dependence of expansion can be found from data on the temperature variation of the isobaric compressibility. In a worst case estimate, a decrease in expansion of approx. 25% is predicted for 5% porous sandstone at a depth of 3 km. The thermal conductivity of a medium with gaseous inclusions increases as the porosity decreases, with the magnitude of the increase being dependent on the details of the porosity collapse. Based on analysis of existing data on tuff and sandstone, a weighted geometric mean formula is recommended for use in calculating the conductivity of porous rock. As a result of this study, it is recommended that measurement of rock porosity versus depth receive increased attention in exploration studies and that the effect of porosity on thermal conductivity and expansion should be examined in more detail

Robust boundary treatment for open-channel flows in divergence-free incompressible SPH

Science.gov (United States)

Pahar, Gourabananda; Dhar, Anirban

2017-03-01

A robust Incompressible Smoothed Particle Hydrodynamics (ISPH) framework is developed to simulate specified inflow and outflow boundary conditions for open-channel flow. Being purely divergence-free, the framework offers smoothed and structured pressure distribution. An implicit treatment of Pressure Poison Equation and Dirichlet boundary condition is applied on free-surface to minimize error in velocity-divergence. Beyond inflow and outflow threshold, multiple layers of dummy particles are created according to specified boundary condition. Inflow boundary acts as a soluble wave-maker. Fluid particles beyond outflow threshold are removed and replaced with dummy particles with specified boundary velocity. The framework is validated against different cases of open channel flow with different boundary conditions. The model can efficiently capture flow evolution and vortex generation for random geometry and variable boundary conditions.

Does increasing pressure always accelerate the condensed material decay initiated through bimolecular reactions? A case of the thermal decomposition of TKX-50 at high pressures.

Science.gov (United States)

Lu, Zhipeng; Zeng, Qun; Xue, Xianggui; Zhang, Zengming; Nie, Fude; Zhang, Chaoyang

2017-08-30

Performances and behaviors under high temperature-high pressure conditions are fundamentals for many materials. We study in the present work the pressure effect on the thermal decomposition of a new energetic ionic salt (EIS), TKX-50, by confining samples in a diamond anvil cell, using Raman spectroscopy measurements and ab initio simulations. As a result, we find a quadratic increase in decomposition temperature (T d ) of TKX-50 with increasing pressure (P) (T d = 6.28P 2 + 12.94P + 493.33, T d and P in K and GPa, respectively, and R 2 = 0.995) and the decomposition under various pressures initiated by an intermolecular H-transfer reaction (a bimolecular reaction). Surprisingly, this finding is contrary to a general observation about the pressure effect on the decomposition of common energetic materials (EMs) composed of neutral molecules: increasing pressure will impede the decomposition if it starts from a bimolecular reaction. Our results also demonstrate that increasing pressure impedes the H-transfer via the enhanced long-range electrostatic repulsion of H +δ H +δ of neighboring NH 3 OH + , with blue shifts of the intermolecular H-bonds. And the subsequent decomposition of the H-transferred intermediates is also suppressed, because the decomposition proceeds from a bimolecular reaction to a unimolecular one, which is generally prevented by compression. These two factors are the basic root for which the decomposition retarded with increasing pressure of TKX-50. Therefore, our finding breaks through the previously proposed concept that, for the condensed materials, increasing pressure will accelerate the thermal decomposition initiated by bimolecular reactions, and reveals a distinct mechanism of the pressure effect on thermal decomposition. That is to say, increasing pressure does not always promote the condensed material decay initiated through bimolecular reactions. Moreover, such a mechanism may be feasible to other EISs due to the similar intermolecular

Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials

Science.gov (United States)

Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; di, Chong-An; Zhu, Daoben

2015-09-01

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Studies of Grain Boundaries in Materials Subjected to Diffusional Creep

DEFF Research Database (Denmark)

Nørbygaard, Thomas

Grain boundaries in crystalline Cu(2%Ni) creep specimens have been studied by use of scanning and transmission electron microscopy in order to establish the mechanism of deformation. Creep rate measurements and dependencies were found to fit reasonably well with the model for diffusional creep......) with the activity displayed during diffusional creep testing. It was found that boundaries with low deviation from perfect Σ did not contribute macroscopically to the creep strain. A resist deposition procedure was examined to improve the reference surface grid so as to allow determination of the grain boundary...... plane by use of simple stereomicroscopy directly on the surface. The etched pattern deteriorated heav-ily during creep testing, supposedly because of dislocation creep, due to exces-sive creep stress. Grain boundaries have been studied and characterised by TEM providing an insight into the diversity...

Risk-informed appendices G and E for section XI of the ASME Boiler and Pressure Vessel Code

International Nuclear Information System (INIS)

Carter, B; Spanner, J.; Server, W.; Gamble, R.; Bishop, B.; Palm, N.; Heinecke, C.

2011-01-01

Full text of publication follows: The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section XI, contains two appendices (G and E) related to reactor pressure boundary integrity. Appendix G provides procedures for defining Service Level A and B pressure temperature limits for ferritic components in the reactor coolant pressure boundary. Recently, an alternative risk informed methodology has been developed for ASME Section XI, Appendix G. The alternative methodology provides simple procedures to define risk informed pressure temperature limits for Service Level A and B events, including leak testing and reactor start up and shut down for both pressurized water reactors (PWRs) and boiling water reactors (BWRs). Risk informed pressure temperature limits provide more operational flexibility, particularly for reactor pressure vessels (RPV) with relatively high irradiation levels and radiation sensitive materials. Appendix E of Section XI provides a methodology for assessing conditions when the Appendix G limits are exceeded. A similar risk informed methodology is being considered for Appendix E. The probabilistic fracture mechanics evaluations used to develop the risk informed relationships included appropriate material properties for the range of RPV materials in operating plants in the United States and operating history and system operational constraints in both BWRs and PWRs. The analysis results were used to define pressure temperature relationships that provide an acceptable level of risk, consistent with safety goals defined by the U.S. Nuclear Regulatory Commission. The alternative methodologies for Appendices G and E will provide greater operational flexibility, especially for Service Level A and B events that may adversely affect efficient and safe plant operation, such as low temperature over pressurization for PWRs and BWR leak testing. Overall, application of the risk informed appendices can result in increased plant

Grain Boundaries From Theory to Engineering

CERN Document Server

Priester, Louisette

2013-01-01

Grain boundaries are a main feature of crystalline materials. They play a key role in determining the properties of materials, especially when grain size decreases and even more so with the current improvements of  processing tools and methods that allow us to control various elements in a polycrystal. This book presents the theoretical basis of the study of  grain boundaries and aims to open up new lines of research in this area. The treatment is light on mathematical approaches while emphasizing practical examples; the issues they raise are discussed with reference to theories. The general approach of the book has two main goals: to lead the reader from the concept of ‘ideal’ to ‘real’ grain boundaries; to depart from established knowledge and address the opportunities emerging through "grain boundary engineering",  the control of morphological and crystallographic features that affect material properties. The book is divided in three parts:  I ‘From interganular order to disorder’ deals wit...

Crack growth behaviour of low alloy steels for pressure boundary components under transient light water reactor operating conditions (CASTOC)

International Nuclear Information System (INIS)

Foehl, J.; Weissenberg, T.; Gomez-Briceno, D.; Lapena, J.; Ernestova, M.; Zamboch, M.; Seifert, H.P.; Ritter, S.; Roth, A.; Devrient, B.; Ehrnsten, U.

2004-01-01

The CASTOC project addresses environmentally assisted cracking (EAC) phenomena in low alloy steels used for pressure boundary components in both Western type boiling water reactors (BWR) and Russian type pressurised water reactors (VVER). It comprises the four work packages (WP): inter-laboratory comparison test (WP1); EAC behaviour under static load (WP2), EAC behaviour under cyclic load and load transients (WP3); evaluation of the results with regard to their relevance for components in practice (WP4). The use of sophisticated test facilities and measurement techniques for the on-line detection of crack advances have provided a more detailed understanding of the mechanisms of environmentally assisted cracking and provided quantitative data of crack growth rates as a function of loading events and time, respectively. The effect of several major parameters controlling EAC was investigated with particular emphasis on the transferability of the results to components in service. The obtained crack growth rate data were reflected on literature data and on commonly applied prediction curves as presented in the appropriate Code. At relevant stress intensity factors it could be shown that immediate cessation of growing cracks occurs after changing from cyclic to static load in high purity oxygenated BWR water and oxygen-free VVER water corresponding to steady state operation conditions. Susceptibility to environmentally assisted cracking under static load was observed for a heat affected zone material in oxygenated high purity water and also in base materials during a chloride transient representing BWR water condition below Action Level 1 of the EPRI Water Chemistry Guidelines according to the lectrical conductivity of the water but in the range of Action Level 2 according to the content of chlorides. Time based crack growth was also observed in one Russian type base material in oxygenated VVER water and in one Western type base material in oxygenated high purity BWR

High pressure {mu}SR studies: rare earths and related materials

Energy Technology Data Exchange (ETDEWEB)

Kalvius, G.M., E-mail: kalvius@ph.tum.de; Schreier, E. [Technical University Munich, Physics Department (Germany)], E-mail: kalvius@ph.tum.de; Ekstroem, M.; Hartmann, O. [Uppsala University, Physics Department (Sweden); Henneberger, S., E-mail: kalvius@ph.tum.de; Kratzer, A. [Technical University Munich, Physics Department (Germany)], E-mail: kalvius@ph.tum.de; Waeppling, R. [Uppsala University, Physics Department (Sweden); Martin, E., E-mail: kalvius@ph.tum.de; Burghart, F.J. [Technical University Munich, Physics Department (Germany)], E-mail: kalvius@ph.tum.de; Ballou, R.; Deportes, J. [CNRS, Laboratoire Louis Neel (France); Niedermayer, Ch. [University of Constance, Faculty of Physics (Germany)

2000-11-15

After a short introduction to {mu}SR with respect to the study of magnetic properties, followed by a brief outline of the principle of the high pressure-low temperature {mu}SR spectrometer installed at the Paul Scherrer Institute, we discuss some measurements on rare earth materials employing this instrument. They are concerned with: (1) The pressure dependence of the spin turning process in ferromagnetic Gd. (2) The volume dependence of the internal magnetic field in the heavy rare earth metals Gd, Dy, and Ho in their ordered magnetic states. (3) The response of the (first order) magnetic transition in the frustrated antiferromagnets of type RMn{sub 2} (R = Y,Gd) to pressure. (4) The variation of magnetic parameters with pressure in La{sub 2}CuO{sub 4} (powder sample), the antiferromagnetic parent compound of the high T{sub C} superconductors of type La{sub 2-x}(Sr, Ba){sub x}CuO{sub 4}. In conclusion a short outlook on further developments is given.

Unit Reynolds number, Mach number and pressure gradient effects on laminar-turbulent transition in two-dimensional boundary layers

Science.gov (United States)

Risius, Steffen; Costantini, Marco; Koch, Stefan; Hein, Stefan; Klein, Christian

2018-05-01

The influence of unit Reynolds number (Re_1=17.5× 106-80× 106 {m}^{-1}), Mach number (M= 0.35-0.77) and incompressible shape factor (H_{12} = 2.50-2.66) on laminar-turbulent boundary layer transition was systematically investigated in the Cryogenic Ludwieg-Tube Göttingen (DNW-KRG). For this investigation the existing two-dimensional wind tunnel model, PaLASTra, which offers a quasi-uniform streamwise pressure gradient, was modified to reduce the size of the flow separation region at its trailing edge. The streamwise temperature distribution and the location of laminar-turbulent transition were measured by means of temperature-sensitive paint (TSP) with a higher accuracy than attained in earlier measurements. It was found that for the modified PaLASTra model the transition Reynolds number (Re_{ {tr}}) exhibits a linear dependence on the pressure gradient, characterized by H_{12}. Due to this linear relation it was possible to quantify the so-called `unit Reynolds number effect', which is an increase of Re_{ {tr}} with Re_1. By a systematic variation of M, Re_1 and H_{12} in combination with a spectral analysis of freestream disturbances, a stabilizing effect of compressibility on boundary layer transition, as predicted by linear stability theory, was detected (`Mach number effect'). Furthermore, two expressions were derived which can be used to calculate the transition Reynolds number as a function of the amplitude of total pressure fluctuations, Re_1 and H_{12}. To determine critical N-factors, the measured transition locations were correlated with amplification rates, calculated by incompressible and compressible linear stability theory. By taking into account the spectral level of total pressure fluctuations at the frequency of the most amplified Tollmien-Schlichting wave at transition location, the scatter in the determined critical N-factors was reduced. Furthermore, the receptivity coefficients dependence on incidence angle of acoustic waves was used to

Pressurized water reactor simulator. Workshop material. 2. ed

International Nuclear Information System (INIS)

2005-01-01

The International Atomic Energy Agency (IAEA) has established an activity in nuclear reactor simulation computer programs to assist its Member States in education. The objective is to provide, for a variety of advanced reactor types, insight and practice in their operational characteristics and their response to perturbations and accident situations. To achieve this, the IAEA arranges for the development and distribution of simulation programs and educational material and sponsors courses and workshops. The workshops are in two parts: techniques and tools for reactor simulator development. And the use of reactor simulators in education. Workshop material for the first part is covered in the IAEA Training Course Series No. 12, 'Reactor Simulator Development' (2001). Course material for workshops using a WWER- 1000 reactor department simulator from the Moscow Engineering and Physics Institute, the Russian Federation is presented in the IAEA Training Course Series No. 21, 2nd edition, 'WWER-1000 Reactor Simulator' (2005). Course material for workshops using a boiling water reactor simulator developed for the IAEA by Cassiopeia Technologies Incorporated of Canada (CTI) is presented in the IAEA publication: Training Course Series No.23, 2nd edition, 'Boiling Water Reactor Simulator' (2005). This report consists of course material for workshops using a pressurized water reactor simulator

Emission of partial dislocations from triple junctions of grain boundaries in nanocrystalline materials

International Nuclear Information System (INIS)

Gutkin, M Yu; Ovid'ko, I A; Skiba, N V

2005-01-01

A theoretical model is suggested that describes emission of partial Shockley dislocations from triple junctions of grain boundaries (GBs) in deformed nanocrystalline materials. In the framework of the model, triple junctions accumulate dislocations due to GB sliding along adjacent GBs. The dislocation accumulation at triple junctions causes partial Shockley dislocations to be emitted from the dislocated triple junctions and thus accommodates GB sliding. Ranges of parameters (applied stress, grain size, etc) are calculated in which the emission events are energetically favourable in nanocrystalline Al, Cu and Ni. The model accounts for the corresponding experimental data reported in the literature

Buckling of pressure-loaded, long, shear deformable, cylindrical laminated shells

Science.gov (United States)

Anastasiadis, John S.; Simitses, George J.

A higher-order shell theory was developed (kinematic relations, constitutive relations, equilibrium equations and boundary conditions), which includes initial geometric imperfections and transverse shear effects for a laminated cylindrical shell under the action of pressure, axial compression and in-plane shear. Through the perturbation technique, buckling equations are derived for the corresponding 'perfect geometry' symmetric laminated configuration. Critical pressures are computed for very long cylinders for several stacking sequences, several radius-to-total-thickness ratios, three lamina materials (boron/epoxy, graphite/epoxy, and Kevlar/epoxy), and three shell theories: classical, first-order shear deformable and higher- (third-)order shear deformable. The results provide valuable information concerning the applicability (accurate prediction of buckling pressures) of the various shell theories.

The influence of grain boundary structure on diffusional creep

DEFF Research Database (Denmark)

Thorsen, Peter Anker; Bilde-Sørensen, Jørgen

1999-01-01

the deformation caused by deposition of material at (or removal of material from) grain boundaries. The misorientation across the grain boundaries, and hence the character of the boundaries, was measured with the use of electron back-scattering patterns. The deformation behavior of the individual boundaries......A Cu-2wt%Ni-alloy was deformed in tension in the diffusional creep regime (Nabarro-Herring creep). A periodic grid consisting of alumina was deposited on the surface of the creep specimen prior to creep. This makes it possible to separate the deformation caused by grain boundary sliding from...

Ultrasound enhanced plasma surface modification at atmospheric pressure

DEFF Research Database (Denmark)

Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion

and the material surface, and thus many reactive species generated in the plasma can reach the surface before inactivated, and be efficiently utilized for surface modification. In the present work polyester plates are treated using a dielectric barrier discharge (DBD) and a gliding arc at atmospheric pressure......Atmospheric pressure plasma treatment can be highly enhanced by simultaneous high-power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above approximately 140 dB can reduce the thickness of a boundary gas layer between the plasma...... irradiation, the water contact angle dropped markedly, and tended to decrease furthermore at higher power. The ultrasonic irradiation during the plasma treatment consistently improved the wettability. Oxygen containing polar functional groups were introduced at the surface by the plasma treatment...

Critical deflagration waves leading to detonation onset under different boundary conditions

International Nuclear Information System (INIS)

Lin Wei; Zhou Jin; Lin Zhi-Yong; Fan Xiao-Hua

2015-01-01

High-speed turbulent critical deflagration waves before detonation onset in H 2 –air mixture propagated into a square cross section channel, which was assembled of optional rigid rough, rigid smooth, or flexible walls. The corresponding propagation characteristic and the influence of the wall boundaries on the propagation were investigated via high-speed shadowgraph and a high-frequency pressure sampling system. As a comprehensive supplement to the different walls effect investigation, the effect of porous absorbing walls on the detonation propagation was also investigated via smoke foils and the high-frequency pressure sampling system. Results are as follows. In the critical deflagration stage, the leading shock and the closely following turbulent flame front travel at a speed of nearly half the CJ detonation velocity. In the preheated zone, a zonary flame arises from the overlapping part of the boundary layer and the pressure waves, and then merges into the mainstream flame. Among these wall boundary conditions, the rigid rough wall plays a most positive role in the formation of the zonary flame and thus accelerates the transition of the deflagration to detonation (DDT), which is due to the boost of the boundary layer growth and the pressure wave reflection. Even though the flexible wall is not conducive to the pressure wave reflection, it brings out a faster boundary layer growth, which plays a more significant role in the zonary flame formation. Additionally, the porous absorbing wall absorbs the transverse wave and yields detonation decay and velocity deficit. After the absorbing wall, below some low initial pressure conditions, no re-initiation occurs and the deflagration propagates in critical deflagration for a relatively long distance. (paper)

Flat Plate Boundary Layer Stimulation Using Trip Wires and Hama Strips

Science.gov (United States)

Peguero, Charles; Henoch, Charles; Hrubes, James; Fredette, Albert; Roberts, Raymond; Huyer, Stephen

2017-11-01

Water tunnel experiments on a flat plate at zero angle of attack were performed to investigate the effect of single roughness elements, i.e., trip wires and Hama strips, on the transition to turbulence. Boundary layer trips are traditionally used in scale model testing to force a boundary layer to transition from laminar to turbulent flow at a single location to aid in scaling of flow characteristics. Several investigations of trip wire effects exist in the literature, but there is a dearth of information regarding the influence of Hama strips on the flat plate boundary layer. The intent of this investigation is to better understand the effects of boundary layer trips, particularly Hama strips, and to investigate the pressure-induced drag of both styles of boundary layer trips. Untripped and tripped boundary layers along a flat plate at a range of flow speeds were characterized with multiple diagnostic measurements in the NUWC/Newport 12-inch water tunnel. A wide range of Hama strip and wire trip thicknesses were used. Measurements included dye flow visualization, direct skin friction and parasitic drag force, boundary layer profiles using LDV, wall shear stress fluctuations using hot film anemometry, and streamwise pressure gradients. Test results will be compared to the CFD and boundary layer model results as well as the existing body of work. Conclusions, resulting in guidance for application of Hama strips in model scale experiments and non-dimensional predictions of pressure drag will be presented.

Receptivity of Hypersonic Boundary Layers over Straight and Flared Cones

Science.gov (United States)

Balakumar, Ponnampalam; Kegerise, Michael A.

2010-01-01

The effects of adverse pressure gradients on the receptivity and stability of hypersonic boundary layers were numerically investigated. Simulations were performed for boundary layer flows over a straight cone and two flared cones. The steady and the unsteady flow fields were obtained by solving the two-dimensional Navier-Stokes equations in axi-symmetric coordinates using the 5th order accurate weighted essentially non-oscillatory (WENO) scheme for space discretization and using third-order total-variation-diminishing (TVD) Runge-Kutta scheme for time integration. The mean boundary layer profiles were analyzed using local stability and non-local parabolized stability equations (PSE) methods. After the most amplified disturbances were identified, two-dimensional plane acoustic waves were introduced at the outer boundary of the computational domain and time accurate simulations were performed. The adverse pressure gradient was found to affect the boundary layer stability in two important ways. Firstly, the frequency of the most amplified second-mode disturbance was increased relative to the zero pressure gradient case. Secondly, the amplification of first- and second-mode disturbances was increased. Although an adverse pressure gradient enhances instability wave growth rates, small nose-tip bluntness was found to delay transition due to the low receptivity coefficient and the resulting weak initial amplitude of the instability waves. The computed and measured amplitude-frequency spectrums in all three cases agree very well in terms of frequency and the shape except for the amplitude.

Understanding creep in sandstone reservoirs - theoretical deformation mechanism maps for pressure solution in granular materials

Science.gov (United States)

Hangx, Suzanne; Spiers, Christopher

2014-05-01

Subsurface exploitation of the Earth's natural resources removes the natural system from its chemical and physical equilibrium. As such, groundwater extraction and hydrocarbon production from subsurface reservoirs frequently causes surface subsidence and induces (micro)seismicity. These effects are not only a problem in onshore (e.g. Groningen, the Netherlands) and offshore hydrocarbon fields (e.g. Ekofisk, Norway), but also in urban areas with extensive groundwater pumping (e.g. Venice, Italy). It is known that fluid extraction inevitably leads to (poro)elastic compaction of reservoirs, hence subsidence and occasional fault reactivation, and causes significant technical, economic and ecological impact. However, such effects often exceed what is expected from purely elastic reservoir behaviour and may continue long after exploitation has ceased. This is most likely due to time-dependent compaction, or 'creep deformation', of such reservoirs, driven by the reduction in pore fluid pressure compared with the rock overburden. Given the societal and ecological impact of surface subsidence, as well as the current interest in developing geothermal energy and unconventional gas resources in densely populated areas, there is much need for obtaining better quantitative understanding of creep in sediments to improve the predictability of the impact of geo-energy and groundwater production. The key problem in developing a reliable, quantitative description of the creep behaviour of sediments, such as sands and sandstones, is that the operative deformation mechanisms are poorly known and poorly quantified. While grain-scale brittle fracturing plus intergranular sliding play an important role in the early stages of compaction, these time-independent, brittle-frictional processes give way to compaction creep on longer time-scales. Thermally-activated mass transfer processes, like pressure solution, can cause creep via dissolution of material at stressed grain contacts, grain-boundary

Evaluation of fatigue damage of pressure vessel materials by observation of microstructures

International Nuclear Information System (INIS)

Yoshida, Kazuo

1994-01-01

As the important factor as the secular change mode of pressure vessel materials, there is fatigue damage. In USA, there is the move to use LWRs by extending their life, and it becomes necessary to show the soundness of the structures of machinery and equipment for long period. For exactly evaluating the soundness of the structures of machinery and equipment, it is important to clarify the degree of secular deterioration of the materials. In this report, by limiting to the fatigue damage of LWR pressure vessel steel, the method of grasping the change of microstructure and the method of estimating the degree of fatigue damage from the change of microstructure are shown. The change of microstructure arising in materials due to fatigue advances in the following steps, namely, the multiplication of dislocations, the tangling of dislocations, the formation of cell structure, the turning of cells, the formation of microcracks, the growth of cracks and fracture. In the case of pressure vessel steel, due to the quenching and tempering, the cell structure is formed from the beginning, and the advance of fatigue is recognized as the increase of the turning angle of cell structures. The detection of fatigue damage by microstructure is reported. (K.I.)

Design of a smart textile mat to study pressure distribution on multiple foam material configurations

NARCIS (Netherlands)

Donselaar, van R.; Chen, W.

2011-01-01

In this paper, we present a design of a smart textile pressure mat to study the pressure distribution with multiple foam material configurations for neonatal monitoring at Neonatal Intensive Care Units (NICU). A smart textile mat with 64 pressure sensors has been developed including software at the

Theoretical Analysis of Pore Pressure Diffusion in Some Basic Rock Mechanics Experiments

Science.gov (United States)

Braun, Philipp; Ghabezloo, Siavash; Delage, Pierre; Sulem, Jean; Conil, Nathalie

2018-05-01

Non-homogeneity of the pore pressure field in a specimen is an issue for characterization of the thermo-poromechanical behaviour of low-permeability geomaterials, as in the case of the Callovo-Oxfordian claystone ( k radioactive waste disposal in France. In tests with drained boundary conditions, excess pore pressure can result in significant errors in the measurement of material parameters. Analytical solutions are presented for the change in time of the pore pressure field in a specimen submitted to various loading paths and different rates. The pore pressure field in mechanical and thermal undrained tests is simulated with a 1D finite difference model taking into account the dead volume of the drainage system of the triaxial cell connected to the specimen. These solutions provide a simple and efficient tool for the estimation of the conditions that must hold for reliable determination of material parameters and for optimization of various test conditions to minimize the experimental duration, while keeping the measurement errors at an acceptable level.

Direct measurement of methane hydrate composition along the hydrate equilibrium boundary

Science.gov (United States)

Circone, S.; Kirby, S.H.; Stern, L.A.

2005-01-01

The composition of methane hydrate, namely nW for CH 4??nWH2O, was directly measured along the hydrate equilibrium boundary under conditions of excess methane gas. Pressure and temperature conditions ranged from 1.9 to 9.7 MPa and 263 to 285 K. Within experimental error, there is no change in hydrate composition with increasing pressure along the equilibrium boundary, but nW may show a slight systematic decrease away from this boundary. A hydrate stoichiometry of n W = 5.81-6.10 H2O describes the entire range of measured values, with an average composition of CH4??5.99(??0.07) H2O along the equilibrium boundary. These results, consistent with previously measured values, are discussed with respect to the widely ranging values obtained by thermodynamic analysis. The relatively constant composition of methane hydrate over the geologically relevant pressure and temperature range investigated suggests that in situ methane hydrate compositions may be estimated with some confidence. ?? 2005 American Chemical Society.

Porewater salinity and the development of swelling pressure in bentonite-based buffer and backfill materials

Energy Technology Data Exchange (ETDEWEB)

Dixon, D.A. [Atomic Energy of Canada Limited (Canada)

2000-06-01

At the depths proposed for a nuclear fuel waste repository, it is likely that saline groundwater conditions will be encountered in the granitic rocks of Finland and Canada. The potential for saline groundwater to influence of the ability of bentonite-based buffer and backfilling materials to swell and thereby generate swelling pressure has been reviewed. Based on the data collected from existing literature, it would appear that porewater salinities as high as 100 g/l will not compromise the ability of confined, bentonite-based materials to develop a swelling pressure of at least 100 kPa on its confinement, provided the effective clay dry density (ECDD), exceeds approximately 0.9 Mg/m{sup 3}. At densities less than approximately 0.9 Mg/m{sup 3} the swelling pressure of bentonite-based materials may be reduced and become sensitive to salt concentration. The influence of porewater salinity on swelling pressure can be compared on the basis of the ECDD required to develop 100 kPa of swelling pressure. In order to generate 100 kPa of swelling pressure an ECDD of approximately 0.7 Mg/m{sup 3} is required to be present under fresh water or brackish porewater conditions. This density would need to be increased to approximately 0.9 Mg/m{sup 3} where the groundwater conditions were saline. The impact that groundwater salinity will have on density specifications for buffer and backfilling materials are discussed with reference to the nuclear fuel waste disposal concepts of Finland and Canada. (orig.)

Extrinsic response enhancement at the polymorphic phase boundary in piezoelectric materials

Energy Technology Data Exchange (ETDEWEB)

Ochoa, Diego A.; García, José E., E-mail: jose.eduardo.garcia@upc.edu [Department of Physics, Universitat Politècnica de Catalunya - BarcelonaTech, Barcelona 08034 (Spain); Esteves, Giovanni; Jones, Jacob L. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27696 (United States); Rubio-Marcos, Fernando; Fernández, José F. [Department of Electroceramics, Instituto de Cerámica y Vidrio - CSIC, Madrid 28049 (Spain)

2016-04-04

Polymorphic phase boundaries (PPBs) in piezoelectric materials have attracted significant interest in recent years, in particular, because of the unique properties that can be found in their vicinity. However, to fully harness their potential as micro-nanoscale functional entities, it is essential to achieve reliable and precise control of their piezoelectric response, which is due to two contributions known as intrinsic and extrinsic. In this work, we have used a (K,Na)NbO{sub 3}-based lead-free piezoceramic as a model system to investigate the evolution of the extrinsic contribution around a PPB. X-ray diffraction measurements are performed over a wide range of temperatures in order to determine the structures and transitions. The relevance of the extrinsic contribution at the PPB region is evaluated by means of nonlinear dielectric response measurements. Though it is widely appreciated that certain intrinsic properties of ferroelectric materials increase as PPBs are approached, our results demonstrate that the extrinsic contribution also maximizes. An enhancement of the extrinsic contribution is therefore also responsible for improving the functional properties at the PPB region. Rayleigh's law is used to quantitatively analyze the nonlinear response. As a result, an evolution of the domain wall motion dynamics through the PPB region is detected. This work demonstrates that the extrinsic contribution at a PPB may have a dynamic role in lead-free piezoelectric materials, thereby exerting a far greater influence on their functional properties than that considered to date.

Systems and Methods for Fabricating Structures Including Metallic Glass-Based Materials Using Low Pressure Casting

Science.gov (United States)

Hofmann, Douglas C. (Inventor); Kennett, Andrew (Inventor)

2018-01-01

Systems and methods to fabricate objects including metallic glass-based materials using low-pressure casting techniques are described. In one embodiment, a method of fabricating an object that includes a metallic glass-based material includes: introducing molten alloy into a mold cavity defined by a mold using a low enough pressure such that the molten alloy does not conform to features of the mold cavity that are smaller than 100 microns; and cooling the molten alloy such that it solidifies, the solid including a metallic glass-based material.

Five-dimensional visualization of phase transition in BiNiO3 under high pressure

International Nuclear Information System (INIS)

Liu, Yijin; Wang, Junyue; Yang, Wenge; Azuma, Masaki; Mao, Wendy L.

2014-01-01

Colossal negative thermal expansion was recently discovered in BiNiO 3 associated with a low density to high density phase transition under high pressure. The varying proportion of co-existing phases plays a key role in the macroscopic behavior of this material. Here, we utilize a recently developed X-ray Absorption Near Edge Spectroscopy Tomography method and resolve the mixture of high/low pressure phases as a function of pressure at tens of nanometer resolution taking advantage of the charge transfer during the transition. This five-dimensional (X, Y, Z, energy, and pressure) visualization of the phase boundary provides a high resolution method to study the interface dynamics of high/low pressure phase

Boundary-Layer Characteristics of Persistent Regional Haze Events and Heavy Haze Days in Eastern China

Directory of Open Access Journals (Sweden)

Peng Huaqing

2016-01-01

Full Text Available This paper analyzed the surface conditions and boundary-layer climate of regional haze events and heavy haze in southern Jiangsu Province in China. There are 5 types with the surface conditions which are equalized pressure (EQP, the advancing edge of a cold front (ACF, the base of high pressure (BOH, the backside of high pressure (BAH, the inverted trough of low pressure (INT, and saddle pressure (SAP with the haze days. At that time, 4 types are divided with the regional haze events and each of which has a different boundary-layer structure. During heavy haze, the surface mainly experiences EQP, ACF, BOH, BAH, and INT which also have different boundary-layer structures.

On-off controller for installation to test the pressurized water reactor material

International Nuclear Information System (INIS)

Zauq, M.H.

1982-05-01

This report describes the design of an ON-OFF controller based on the 6800 microprocessor in its assembly language and its interfacing with its environment (sensors, periphery, etc). The controller is meant to control the temperature and the pressure inside an experimental chamber in which the material under test is placed. The ''Design basis accident'' conditions (e.g., LOCA) for a pressurized water reactor are simulated in the experimental chamber [fr

Improvement of technical purpose materials performance characteristics with the radio frequency low pressure plasma

Science.gov (United States)

Makhotkina, L. Yu; Khristoliubova, V. I.

2017-11-01

The main aim of the work is to solve the actual problem of increasing the competitiveness of tanning products by reducing the prime cost and improving the quality of finished products due to the increased durability of the working elements of tanneries. The impact of the low pressure radio frequency (RF) plasma in the processes of treating for modification of the materials for special purposes is considered in the article. The results of working elements of tanneries and the materials for special purposes sample processing by a RF low pressure plasma are described. As a result of leather materials nano structuring and nano modifying physical, mechanical and hygienic characteristics were increased. Processing of the technical purpose materials allows to increase operational performance of products and extend their lifespan.

Boundary vapor contentsin an annular channel

International Nuclear Information System (INIS)

Remizov, O.V.; Shurkin, N.G.; Podgornyj, K.K.; Gal'chenko, Eh.F.; Bukhteev, I.S.

1978-01-01

The work is aimed at the experimental investigation of the worsening of the heat transfer in an annular channel. The experiments have been carried out on the annular channel 32x28x3000 mm with the even distribution of the heat flux along the length at pressures of 6.9-19.6 MPa, flow rate of 350-1000 kg/m 2 s, and specific heat fluxes from 0.18 up to 0.6 MW/m 2 . Heating is external, oneside. Water monodistillate of the following composition has been used as a coolant: pH 9; dry residue - 0.8-1.2 mg/kg, oxygen -10-15 mg/kg. It is found out that the change character of the temperature field of the heating surface of the annular channel at the regime with the worsen of heat emission depends on the ratio of regime parameters. At pressures of 6.9-13.7 MPa and flow rate of 350-500 kg/m 2 s the channel wall temperature rises monotoneously, never reaching its maximum. With pressure rise > 13.7 MPa and mass velocity > 500 kg/m 2 s the temperature of the heat emitting surface reaches its maximum, and then slowly falls. At pressures of 6.9-11.8 MPa the boundary vapor content value within the whole range of mass velocities does not depend on the specific heat flux q. At pressures higher than 13.7 MPa and mass velocities of 350-1000 kg/m 2 s the boundary vapor content depends on q. The heating of the external or internal surface of the annular channel affects the value of the boundary vapor content within the whole range of regime parameters' change under investigation

Influence of model boundary conditions on blood flow patterns in a patient specific stenotic right coronary artery.

Science.gov (United States)

Liu, Biyue; Zheng, Jie; Bach, Richard; Tang, Dalin

2015-01-01

In literature, the effect of the inflow boundary condition was investigated by examining the impact of the waveform and the shape of the spatial profile of the inlet velocity on the cardiac hemodynamics. However, not much work has been reported on comparing the effect of the different combinations of the inlet/outlet boundary conditions on the quantification of the pressure field and flow distribution patterns in stenotic right coronary arteries. Non-Newtonian models were used to simulate blood flow in a patient-specific stenotic right coronary artery and investigate the influence of different boundary conditions on the phasic variation and the spatial distribution patterns of blood flow. The 3D geometry of a diseased artery segment was reconstructed from a series of IVUS slices. Five different combinations of the inlet and the outlet boundary conditions were tested and compared. The temporal distribution patterns and the magnitudes of the velocity, the wall shear stress (WSS), the pressure, the pressure drop (PD), and the spatial gradient of wall pressure (WPG) were different when boundary conditions were imposed using different pressure/velocity combinations at inlet/outlet. The maximum velocity magnitude in a cardiac cycle at the center of the inlet from models with imposed inlet pressure conditions was about 29% lower than that from models using fully developed inlet velocity data. Due to the fact that models with imposed pressure conditions led to blunt velocity profile, the maximum wall shear stress at inlet in a cardiac cycle from models with imposed inlet pressure conditions was about 29% higher than that from models with imposed inlet velocity boundary conditions. When the inlet boundary was imposed by a velocity waveform, the models with different outlet boundary conditions resulted in different temporal distribution patterns and magnitudes of the phasic variation of pressure. On the other hand, the type of different boundary conditions imposed at the

Robust aqua material. A pressure-resistant self-assembled membrane for water purification

International Nuclear Information System (INIS)

Cohen, Erez; Weissman, Haim; Rybtchinski, Boris; Shimoni, Eyal; Kaplan-Ashiri, Ifat; Werle, Kai; Wohlleben, Wendel

2017-01-01

''Aqua materials'' that contain water as their major component and are as robust as conventional plastics are highly desirable. Yet, the ability of such systems to withstand harsh conditions, for example, high pressures typical of industrial applications has not been demonstrated. We show that a hydrogel-like membrane self-assembled from an aromatic amphiphile and colloidal Nafion is capable of purifying water from organic molecules, including pharmaceuticals, and heavy metals in a very wide range of concentrations. Remarkably, the membrane can sustain high pressures, retaining its function. The robustness and functionality of the water-based self-assembled array advances the idea that aqua materials can be very strong and suitable for demanding industrial applications. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Element stacking method for topology optimization with material-dependent boundary and loading conditions

DEFF Research Database (Denmark)

Yoon, Gil Ho; Park, Y.K.; Kim, Y.Y.

2007-01-01

A new topology optimization scheme, called the element stacking method, is developed to better handle design optimization involving material-dependent boundary conditions and selection of elements of different types. If these problems are solved by existing standard approaches, complicated finite...... element models or topology optimization reformulation may be necessary. The key idea of the proposed method is to stack multiple elements on the same discretization pixel and select a single or no element. In this method, stacked elements on the same pixel have the same coordinates but may have...... independent degrees of freedom. Some test problems are considered to check the effectiveness of the proposed stacking method....

Boundary and PMI Diagnostics for the DIII-D National Fusion Facility

Science.gov (United States)

Thomas, D. M.; Bray, B. D.; Chrobak, C.; Leonard, A. W.; Allen, S. L.; Lasnier, C. J.; McLean, A. G.; Briesemeister, A. R.; Boedo, J. A.; Elder, D.; Watkins, J. G.

2014-10-01

The Boundary and Plasma Materials Interaction Center is planning an improved set of boundary and divertor diagnostics for DIII-D in order to develop and validate robust heat flux solutions for future fusion devices on a timescale relevant to the design of FNSF. We intend to develop and test advanced divertor configurations on DIII-D using high performance plasma scenarios that are compatible with advanced tokamak operations in FNSF as well as providing a comprehensive testbed for modeling. Simultaneously, candidate PFC material solutions can be easily tested in these scenarios. Additional diagnostic capability is vital to help understand and validate these solutions. We will describe a number of desired measurements and our plans for deployment. These include better accounting of divertor radiation, including species identification and spatial distribution, divertor/SOL main ion temperature and neutral pressure, fuller 2D Te /ne imaging, and toroidally separated 3D heat flux measurements. Work supported by the US Department of Energy under DE-FC02-04ER54698, DE-AC52-07NA27344, DE-AC05-00OR22725, DE-FG02-07EAR54917, and DE-AC04-94AL85000.

Axisymmetric MHD stability of sharp-boundary Tokamaks

International Nuclear Information System (INIS)

Rebhan, E.; Salat, A.

1976-09-01

For a sharp-boundary, constant pressure plasma model of axisymmetric equilibria the MHD stability problem of axisymmetric perturbations is solved by analytic reduction to a one-dimensional problem on the boundary and subsequent numerical treatment, using the energy principle. The stability boundaries are determined for arbitrary aspect ratio, arbitrary βsub(p) and elliptical, triangular and rectangular plasma cross-sections, wall stabilization not being taken into account. It is found that the axisymmetric stability strongly depends on the plasma shape and is almost independent of the safety factor q. (orig.) [de

Cylindrical prominences and the magnetic influence of the photospheric boundary

International Nuclear Information System (INIS)

Lerche, I.; Chicago Univ., IL; Low, B.C.

1980-01-01

We construct exact, non-linear, solutions for an horizontal, cylindrical, current-carrying, prominence supported against solar gravity by the action of a Lorentz force. The solutions incorporate the photosphere boundary condition, proposed by van Tend and Kuperus (1978), and analyzed by them for line filaments. Our solutions have finite radius for the prominence material and, as well as satisfying the equations of magnetostatic equilibrium, they allow for the continuity of gas pressure, and of the normal and tangential components of magnetic field across the circular prominence boundary. We show that an infinity of solutions is possible and we illustrate the basic behavior by investigation of a special case. We also give a prescription for constructing equilibrium fields for any horizontal prominence with arbitrary cross-section and with an arbitrary external magnetic field. The prescription is ideally suited for numerical codes and we suggest that both the equilibrium of such shapes can easily be accomplished numerically together with their evolutionary history. (orig.)

Plasma transport near material boundaries

International Nuclear Information System (INIS)

Singer, C.E.

1985-06-01

The fluid theory of two-dimensional (2-d) plasma transport in axisymmetric devices is reviewed. The forces which produce flow across the magnetic field in a collisional plasma are described. These flows may lead to up-down asymmetries in the poloidal rotation and radial fluxes. Emphasis is placed on understanding the conditions under which the known 2-d plasma fluid equations provide a valid description of these processes. Attempts to extend the fluid treatment to less collisional, turbulent plasmas are discussed. A reduction to the 1-d fluid equations used in many computer simulations is possible when sources or boundary conditions provide a large enough radial scale length. The complete 1-d fluid equations are given in the text, and 2-d fluid equations are given in the Appendix

Pressure induced superconductivity in the antiferromagnetic Dirac material BaMnBi2.

Science.gov (United States)

Chen, Huimin; Li, Lin; Zhu, Qinqing; Yang, Jinhu; Chen, Bin; Mao, Qianhui; Du, Jianhua; Wang, Hangdong; Fang, Minghu

2017-05-09

The so-called Dirac materials such as graphene and topological insulators are a new class of matter different from conventional metals and (doped) semiconductors. Superconductivity induced by doing or applying pressure in these systems may be unconventional, or host mysterious Majorana fermions. Here, we report a successfully observation of pressure-induced superconductivity in an antiferromagnetic Dirac material BaMnBi 2 with T c of ~4 K at 2.6 GPa. Both the higher upper critical field, μ 0 H c2 (0) ~ 7 Tesla, and the measured current independent of T c precludes that superconductivity is ascribed to the Bi impurity. The similarity in ρ ab (B) linear behavior at high magnetic fields measured at 2 K both at ambient pressure (non-superconductivity) and 2.6 GPa (superconductivity, but at the normal state), as well as the smooth and similar change of resistivity with pressure measured at 7 K and 300 K in zero field, suggests that there may be no structure transition occurred below 2.6 GPa, and superconductivity observed here may emerge in the same phase with Dirac fermions. Our findings imply that BaMnBi 2 may provide another platform for studying SC mechanism in the system with Dirac fermions.

Fracture Toughness Round Robin Test International in pressure tube materials

International Nuclear Information System (INIS)

Villagarcia, M.P.; Liendo, M.F.

1993-01-01

Part of the pressure tubes surveillance program of CANDU type reactors is to determine the fracture toughness using a special fracture specimen and test procedure. Atomic Energy of Canada Limited decided to hold a Round Robin Test International and 9 laboratories participated worldwide in which several pressure tube materials were selected: Zircaloy-2, Zr-2.5%Nb cold worked and Zr-2.5%Nb heat treated. The small specimens used held back the thickness and curvature of the tube. J-R curves at room temperature were obtained and the crack extension values were determined by electrical potential drop techniques. These values were compared with results generated from other laboratories and a bid scatter was founded. It could be due to slight variations in the test method or inhomogeneity of the materials and a statistical study must be done to see if there is any pattern. The next step for the Round Robin Test would be to make some modifications in the test method in order to reduce the scatter. (Author)

Heat-Induced, Pressure-Induced and Centrifugal-Force-Induced Exact Axisymmetric Thermo-Mechanical Analyses in a Thick-Walled Spherical Vessel, an Infinite Cylindrical Vessel, and a Uniform Disk Made of an Isotropic and Homogeneous Material

Directory of Open Access Journals (Sweden)

Vebil Yıldırım

2017-07-01

Full Text Available Heat-induced, pressure-induced, and centrifugal force-induced axisymmetric exact deformation and stresses in a thick-walled spherical vessel, a cylindrical vessel, and a uniform disk are all determined analytically at a specified constant surface temperature and at a constant angular velocity. The inner and outer pressures are both included in the formulation of annular structures made of an isotropic and homogeneous linear elastic material. Governing equations in the form of Euler-Cauchy differential equation with constant coefficients are solved and results are presented in compact forms. For disks, three different boundary conditions are taken into account to consider mechanical engineering applications. The present study is also peppered with numerical results in graphical forms.

Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials.

Science.gov (United States)

Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; Di, Chong-an; Zhu, Daoben

2015-09-21

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of pressure-sensing sensitivity of up to 28.9 kPa(-1). More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Pressure-jump induced rapid solidification of melt: a method of preparing amorphous materials

Science.gov (United States)

Liu, Xiuru; Jia, Ru; Zhang, Doudou; Yuan, Chaosheng; Shao, Chunguang; Hong, Shiming

2018-04-01

By using a self-designed pressure-jump apparatus, we investigated the melt solidification behavior in rapid compression process for several kinds of materials, such as elementary sulfur, polymer polyether-ether-ketone (PEEK) and poly-ethylene-terephthalate, alloy La68Al10Cu20Co2 and Nd60Cu20Ni10Al10. Experimental results clearly show that their melts could be solidified to be amorphous states through the rapid compression process. Bulk amorphous PEEK with 24 mm in diameter and 12 mm in height was prepared, which exceeds the size obtained by melt quenching method. The bulk amorphous sulfur thus obtained exhibited extraordinarily high thermal stability, and an abnormal exothermic transition to liquid sulfur was observed at around 396 K for the first time. Furthermore, it is suggested that the glass transition pressure and critical compression rate exist to form the amorphous phase. This approach of rapid compression is very attractive not only because it is a new technique of make bulk amorphous materials, but also because novel properties are expected in the amorphous materials solidified by the pressure-jump within milliseconds or microseconds.

A reformulated synthetic turbulence generation method for a zonal RANS–LES method and its application to zero-pressure gradient boundary layers

International Nuclear Information System (INIS)

Roidl, B.; Meinke, M.; Schröder, W.

2013-01-01

Highlights: • A synthetic turbulence generation method (STGM) is presented. • STGM is applied to sub and supersonic flows at low and moderate Reynolds numbers. • STGM shows a convincing quality in zonal RANS–LES for flat-plate boundary layers (BLs). • A good agreement with the pure LES and reference DNS findings is obtained. • RANS-to-LES transition length is reduced to less than four boundary-layer thicknesses. -- Abstract: A synthetic turbulence generation (STG) method for subsonic and supersonic flows at low and moderate Reynolds numbers to provide inflow distributions of zonal Reynolds-averaged Navier–Stokes (RANS) – large-eddy simulation (LES) methods is presented. The STG method splits the LES inflow region into three planes where a local velocity signal is decomposed from the turbulent flow properties of the upstream RANS solution. Based on the wall-normal position and the local flow Reynolds number, specific length and velocity scales with different vorticity content are imposed at the inlet plane of the boundary layer. The quality of the STG method for incompressible and compressible zero-pressure gradient boundary layers is shown by comparing the zonal RANS–LES data with pure LES, pure RANS, and direct numerical simulation (DNS) solutions. The distributions of the time and spanwise wall-shear stress, Reynolds stress distributions, and two point correlations of the zonal RANS–LES simulations are smooth in the transition region and in good agreement with the pure LES and reference DNS findings. The STG approach reduces the RANS-to-LES transition length to less than four boundary-layer thicknesses

Superhard MgB sub 2 bulk material prepared by high-pressure sintering

CERN Document Server

Ma, H A; Chen, L X; Zhu, P W; Ren, G Z; Guo, W L; Fu, X Q; Zou Guang Tian; Ren, Z A; Che, G C; Zhao, Z X

2002-01-01

Superhard MgB sub 2 bulk material with a golden metallic shine was synthesized by high-pressure sintering for 8 h at 5.5 GPa and different temperatures. Appropriate pressure and temperature conditions for synthesizing polycrystalline MgB sub 2 with high hardness were investigated. The samples were characterized by means of atomic force microscopy and x-ray diffraction. The Vickers hardness, bulk density, and electrical resistivity were measured at room temperature.

Delayed hydride cracking and elastic properties of Excel, a candidate CANDU-SCWR pressure tube material

International Nuclear Information System (INIS)

Pan, Z.L.

2010-01-01

Excel, a Zr alloy which contains 3.5%Sn, 0.8%Nb and 0.8%Mo, shows high strength, good corrosion resistance, excellent creep-resistance and dimension stability and thus is selected as a candidate pressure tube material for CANDU-SCWR. In the present work, the delayed hydride cracking properties (K IH and the DHC growth rates), the hydrogen solubility and elastic modulus were measured in the irradiated and unirradiated Excel pressure tube material. (author)

Acoustic Radiation From a Mach 14 Turbulent Boundary Layer

Science.gov (United States)

Zhang, Chao; Duan, Lian; Choudhari, Meelan M.

2016-01-01

Direct numerical simulations (DNS) are used to examine the turbulence statistics and the radiation field generated by a high-speed turbulent boundary layer with a nominal freestream Mach number of 14 and wall temperature of 0:18 times the recovery temperature. The flow conditions fall within the range of nozzle exit conditions of the Arnold Engineering Development Center (AEDC) Hypervelocity Tunnel No. 9 facility. The streamwise domain size is approximately 200 times the boundary-layer thickness at the inlet, with a useful range of Reynolds number corresponding to Re 450 ?? 650. Consistent with previous studies of turbulent boundary layer at high Mach numbers, the weak compressibility hypothesis for turbulent boundary layers remains applicable under this flow condition and the computational results confirm the validity of both the van Driest transformation and Morkovin's scaling. The Reynolds analogy is valid at the surface; the RMS of fluctuations in the surface pressure, wall shear stress, and heat flux is 24%, 53%, and 67% of the surface mean, respectively. The magnitude and dominant frequency of pressure fluctuations are found to vary dramatically within the inner layer (z/delta 0.< or approx. 0.08 or z+ < or approx. 50). The peak of the pre-multiplied frequency spectrum of the pressure fluctuation is f(delta)/U(sub infinity) approx. 2.1 at the surface and shifts to a lower frequency of f(delta)/U(sub infinity) approx. 0.7 in the free stream where the pressure signal is predominantly acoustic. The dominant frequency of the pressure spectrum shows a significant dependence on the freestream Mach number both at the wall and in the free stream.

Grain boundaries in high temperature superconductors

NARCIS (Netherlands)

Hilgenkamp, Johannes W.M.; Mannhart, J.

2002-01-01

Since the first days of high-Tc superconductivity, the materials science and the physics of grain boundaries in superconducting compounds have developed into fascinating fields of research. Unique electronic properties, different from those of the grain boundaries in conventional metallic

Developing Boundary/PMI Solutions for Next-Step Fusion Devices

Science.gov (United States)

Guo, H. Y.; Leonard, A. W.; Thomas, D. M.; Allen, S. L.; Hill, D. N.; Unterberg, Z.

2014-10-01

The path towards next-step fusion development requires increased emphasis on the boundary/plasma-material interface. The new DIII-D Boundary/Plasma-Material Interactions (PMI) Center has been established to address these critical issues on a timescale relevant to the design of FNSF, adopting the following transformational approaches: (1) Develop and test advanced divertor configurations on DIII-D compatible with core plasma high performance operational scenarios in FNSF; (2) Validate candidate reactor PFC materials at reactor-relevant temperatures in DIII-D high-performance plasmas, in collaboration with the broad material research/development community; (3) Integrate validated boundary-materials interface with high performance plasmas to provide viable boundary/PMI solutions for next-step fusion devices. This program leverages unique DIII-D capabilities, promotes synergistic programs within the broad PMI community, including linear material research facilities. It will also enable us to build a compelling bridge for the US research on long-pulse facilities. Work supported by the US DOE under DE-FC02-04ER54698 and DE-AC52-07NA27344, DE-AC05-00OR2725.

Failure rates in Barsebaeck-1 reactor coolant pressure boundary piping. An application of a piping failure database

International Nuclear Information System (INIS)

Lydell, B.

1999-05-01

This report documents an application of a piping failure database to estimate the frequency of leak and rupture in reactor coolant pressure boundary piping. The study used Barsebaeck-1 as reference plant. The study tried two different approaches to piping failure rate estimation: 1) PSA-style, simple estimation using Bayesian statistics, and 2) fitting of statistical distribution to failure data. A large, validated database on piping failures (like the SKI-PIPE database) supports both approaches. In addition to documenting leak and rupture frequencies, the SKI report describes the use of piping failure data to estimate frequency of medium and large loss of coolant accidents (LOCAs). This application study was co sponsored by Barsebaeck Kraft AB and SKI Research

New atom probe approaches to studying segregation in nanocrystalline materials.

Science.gov (United States)

Samudrala, S K; Felfer, P J; Araullo-Peters, V J; Cao, Y; Liao, X Z; Cairney, J M

2013-09-01

Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. Copyright © 2013 Elsevier B.V. All rights reserved.

A study on the bonding residual thermal stress analysis of dissimilar materials using boundary element method

International Nuclear Information System (INIS)

Yi, Won; Yu, Yeong Chul; Jeong, Eui Seob; Lee, Chang Ho

1995-01-01

It is very important to evaluate the bonding residual thermal stress in dissimilar materials such as LSI package. In this study, the bonding residual thermal stress was calculated using the boundary element method, varing with the sub-element, geometry of specimen and adhesive thickness. The present results reveal a stress singularity at the edge of the interface, therefore the bonding strength of metal/resin interface can be estimated by taking into account it.

Robust aqua material. A pressure-resistant self-assembled membrane for water purification

Energy Technology Data Exchange (ETDEWEB)

Cohen, Erez; Weissman, Haim; Rybtchinski, Boris [Department of Organic Chemistry, Weizmann Institute of Science, 234 Herzl Street, Rehovot, 7610001 (Israel); Shimoni, Eyal; Kaplan-Ashiri, Ifat [Department of Chemical Research Support, Weizmann Institute of Science, 234 Herzl Street, Rehovot, 7610001 (Israel); Werle, Kai; Wohlleben, Wendel [Department of Material Physics, Materials and Systems Research, BASF SE, 67056, Ludwigshafen (Germany)

2017-02-13

''Aqua materials'' that contain water as their major component and are as robust as conventional plastics are highly desirable. Yet, the ability of such systems to withstand harsh conditions, for example, high pressures typical of industrial applications has not been demonstrated. We show that a hydrogel-like membrane self-assembled from an aromatic amphiphile and colloidal Nafion is capable of purifying water from organic molecules, including pharmaceuticals, and heavy metals in a very wide range of concentrations. Remarkably, the membrane can sustain high pressures, retaining its function. The robustness and functionality of the water-based self-assembled array advances the idea that aqua materials can be very strong and suitable for demanding industrial applications. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Effect of aging on properties of pressure vessel steels

Energy Technology Data Exchange (ETDEWEB)

Druce, S.G.; Gage, G.; Jordan, G.

1986-04-01

Manganese-molybdenum-nickel steels are used in nuclear pressure vessels operating at temperatures up to 350/sup 0/C. The effects of thermal ageing in the temperature range 300-550/sup 0/C for durations up to 2 x 10/sup 4/ h have been studied in conventionally quenched and tempered and simulated heat-affected-zone (HAZ) microstructural conditions. Quantitative fractography and Auger spectroscopy have been used to relate changes in mechanical properties with changes in fracture mode and grain boundary chemistry. Aging increases the ductile-brittle transition temperature by an amount dependent on material, prior heat treatment, aging temperature and time. Embrittlement is associated with segregation of phosphorus to grain boundaries and is modelled using McLean's approach to equilibrium segregation.

Effects of pressure and temperature on thermal contact resistance between different materials

Directory of Open Access Journals (Sweden)

Zhao Zhe

2015-01-01

Full Text Available To explore whether pressure and temperature can affect thermal contact resistance, we have proposed a new experimental approach for measurement of the thermal contact resistance. Taking the thermal contact resistance between phenolic resin and carbon-carbon composites, cuprum, and aluminum as the examples, the influence of the thermal contact resistance between specimens under pressure is tested by experiment. Two groups of experiments are performed and then an analysis on influencing factors of the thermal contact resistance is presented in this paper. The experimental results reveal that the thermal contact resistance depends not only on the thermal conductivity coefficient of materials, but on the interfacial temperature and pressure. Furthermore, the thermal contact resistance between cuprum and aluminum is more sensitive to pressure and temperature than that between phenolic resin and carbon-carbon composites.

Effect of Reynolds Number and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Intermittency Behavior Along the Suction Surface of a Low Pressure Turbine Blade

Science.gov (United States)

Schobeiri, M. T.; Ozturk, B.; Ashpis, David E.

2007-01-01

The paper experimentally studies the effects of periodic unsteady wake flow and different Reynolds numbers on boundary layer development, separation and re-attachment along the suction surface of a low pressure turbine blade. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. The experiments were carried out at Reynolds numbers of 110,000 and 150,000 (based on suction surface length and exit velocity). One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The reduced frequencies chosen cover the operating range of LP turbines. In addition to the unsteady boundary layer measurements, surface pressure measurements were performed. The inception, onset, and the extent of the separation bubble information collected from the pressure measurements were compared with the hot wire measurements. The results presented in ensemble-averaged, and the contour plot forms help to understand the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds number. It was found that the suction surface displayed a strong separation bubble for these three different reduced frequencies. For each condition, the locations defining the separation bubble were determined carefully analyzing and examining the pressure and mean velocity profile data. The location of the boundary layer separation was dependent of the Reynolds number. It is observed that starting point of the separation bubble and the re-attachment point move further downstream by increasing Reynolds number from 110,000 to 150,000. Also, the size of the separation bubble is smaller when compared to that for Re=110,000.

Materials, manufacture and testing of pressurized components of high-power steam power plants

International Nuclear Information System (INIS)

Blind, D.; Foehl, J.; Issler, L.; Schellhammer, W.; Sturm, D.; Kussmaul, K.; Heinrich, D.; Meyer, H.J.; Prestel, W.

1981-01-01

This is the first German review of materials, production and testing of pressure components of high-capacity steam power plants. The authors have been working in this field for years; their special subject has been the availability and reliability of pressure vessels, in particular in nuclear engineering. Fundamentals are presented as well as the findings obtained at the state Materials Testing Institute in Stuttgart. The material is presented in a well-structured classification; the most recent international findings, especially of the USA, are presented. This is possible due to the close cooperation between the Stuttgart institute and a number of US research institutes. The new subject of fracture mechanics is treated in some detail; its fundamentals are discussed from the American point of view while German considerations - in particular of the Reactor Safety Commission - are taken into account in the field of applications. (orig.) [de

Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions

KAUST Repository

Samu, Gergely F.; Scheidt, Rebecca A; Kamat, Prashant V.; Janá ky, Csaba

2017-01-01

The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and to assemble their hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr3 and hybrid organic-inorganic MaPbI3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. We believe that the presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that easier comparisons can be made.

Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions.

Science.gov (United States)

Samu, Gergely F; Scheidt, Rebecca A; Kamat, Prashant V; Janáky, Csaba

2018-02-13

The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and for assembling them into hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr 3 and hybrid organic-inorganic MAPbI 3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. The presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that comparisons can more easily be made.

Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions

KAUST Repository

Samu, Gergely F.

2017-12-06

The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and to assemble their hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr3 and hybrid organic-inorganic MaPbI3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. We believe that the presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that easier comparisons can be made.

Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions

Science.gov (United States)

2017-01-01

The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and for assembling them into hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr3 and hybrid organic–inorganic MAPbI3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. The presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that comparisons can more easily be made. PMID:29503507

Effects of oxide distributed in grain boundaries on microstructure stability of nanocrystalline metals

Science.gov (United States)

Zhou, Kai; Li, Hui; Biao Pang, Jin; Wang, Zhu

2013-06-01

Nanocrystalline copper and zinc prepared by high-pressure compaction method have been studied by positron lifetime spectroscopy associated with X-ray diffraction. For nanocrystalline Cu, mean grain sizes of the samples decrease after being annealed at 900 °C and increase during aging at 180 °C, revealing that the atoms exchange between the two regions. The positron lifetime results indicate that the vacancy clusters formed in the annealing process are unstable and decomposed at the aging time below 6 hours. In addition, the partially oxidized surfaces of the nanoparticles hinder the grain growth during the ageing at 180 °C, and the vacancy clusters inside the disorder regions which are related to Cu2O need longer aging time to decompose. In the case of nanocrystalline Zn, the open volume defect (not larger than divacancy) is dominant according to the high relative intensity for the short positron lifetime (τ1). The oxide (ZnO) inside the grain boundaries has been found having an effect to hinder the decrease of average positron lifetime (τav) during the annealing, which probably indicates that the oxide stabilizes the microstructure of the grain boundaries. For both nanocrystalline copper and zinc, the oxides in grain boundaries enhance the thermal stability of the microstucture, in spite of their different crystal structures. This effect is very important for the nanocrystalline materials using as radiation resistant materials.

Effects of oxide distributed in grain boundaries on microstructure stability of nanocrystalline metals

International Nuclear Information System (INIS)

Zhou Kai; Li Hui; Pang Jinbiao; Wang Zhu

2013-01-01

Nanocrystalline copper and zinc prepared by high-pressure compaction method have been studied by positron lifetime spectroscopy associated with X-ray diffraction. For nanocrystalline Cu, mean grain sizes of the samples decrease after being annealed at 900 °C and increase during aging at 180 °C, revealing that the atoms exchange between the two regions. The positron lifetime results indicate that the vacancy clusters formed in the annealing process are unstable and decomposed at the aging time below 6 hours. In addition, the partially oxidized surfaces of the nanoparticles hinder the grain growth during the ageing at 180 °C, and the vacancy clusters inside the disorder regions which are related to Cu 2 O need longer aging time to decompose. In the case of nanocrystalline Zn, the open volume defect (not larger than divacancy) is dominant according to the high relative intensity for the short positron lifetime (τ 1 ). The oxide (ZnO) inside the grain boundaries has been found having an effect to hinder the decrease of average positron lifetime (τ av ) during the annealing, which probably indicates that the oxide stabilizes the microstructure of the grain boundaries. For both nanocrystalline copper and zinc, the oxides in grain boundaries enhance the thermal stability of the microstucture, in spite of their different crystal structures. This effect is very important for the nanocrystalline materials using as radiation resistant materials.

Atmospheric-Pressure Plasma Interaction with Soft Materials as Fundamental Processes in Plasma Medicine.

Science.gov (United States)

Takenaka, Kosuke; Miyazaki, Atsushi; Uchida, Giichiro; Setsuhara, Yuichi

2015-03-01

Molecular-structure variation of organic materials irradiated with atmospheric pressure He plasma jet have been investigated. Optical emission spectrum in the atmospheric-pressure He plasma jet has been measured. The spectrum shows considerable emissions of He lines, and the emission of O and N radicals attributed to air. Variation in molecular structure of Polyethylene terephthalate (PET) film surface irradiated with the atmospheric-pressure He plasma jet has been observed via X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). These results via XPS and FT-IR indicate that the PET surface irradiated with the atmospheric-pressure He plasma jet was oxidized by chemical and/or physical effect due to irradiation of active species.

On hairpin vortices in a transitional boundary layer

Directory of Open Access Journals (Sweden)

Uruba Václav

2012-04-01

Full Text Available In the presented paper the results of experiments on transitional boundary layer are presented. The boundary layer was generated on smooth flat wall with zero pressure gradient forming one side of the channel of rectangular cross section. The hairpin vortices, packets of hairpin vortices, turbulent spots and calmed regions were experimentally investigated using time-resolved PIV technique.

Ferroelectric domain continuity over grain boundaries

DEFF Research Database (Denmark)

Mantri, Sukriti; Oddershede, Jette; Damjanovic, Dragan

2017-01-01

Formation and mobility of domain walls in ferroelectric materials is responsible for many of their electrical and mechanical properties. Domain wall continuity across grain boundaries has been observed since the 1950's and is speculated to affect the grain boundary-domain interactions, thereby...... impacting macroscopic ferroelectric properties in polycrystalline systems. However detailed studies of such correlated domain structures across grain boundaries are limited. In this work, we have developed the mathematical requirements for domain wall plane matching at grain boundaries of any given...... orientation. We have also incorporated the effect of grain boundary ferroelectric polarization charge created when any two domains meet at the grain boundary plane. The probability of domain wall continuity for three specific grain misorientations is studied. Use of this knowledge to optimize processing...

SOCOOL-2, Molten Materials Na Coolant Interaction, Temperature and Pressure Transient

International Nuclear Information System (INIS)

Padilla, A. Jr.

1973-01-01

1 - Description of problem or function: SOCOOL2 calculates the transient temperatures, pressures, and mechanical work energy when a molten material is instantaneously and uniformly dispersed in liquid sodium which is initially under acoustic constraint. 2 - Method of solution: A unit cell consisting of a single spherical particle of molten material surrounded concentrically by sodium is used as the basis for the calculation. Heat transfer from the molten particle to the sodium is calculated by an implicit numerical technique assuming negligible contact resistance at the interface of the particle. The expansion of the heated sodium is calculated by the one-dimensional acoustic equation until vaporization conditions are attained. Upon vaporization, it is assumed that the particle becomes vapor-blanketed and that no further heat transfer to or from the sodium occurs. The heated sodium is then expanded to the specific final pressure in an isentropic expansion process. 3 - Restrictions on the complexity of the problem: The presence of an initial amount of sodium vapor or noncondensable gas cannot be taken into account. Time delays in the process of fragmentation and mixing of the molten material into the sodium cannot be considered. Heat transfer during the two-phase expansion of sodium is neglected

A Comment Upon Previous Studies on 3-D Boundary Layer Transition

OpenAIRE

ÇARPINLIOĞLU, Melda Özdinç

2014-01-01

The common feature of the experimental studies upon 3-D boundary layer development on swept flat plates cited in the available literature is the application of streamwise and/or spanwise pressure gradients. In fact; presence of the pressure gradients was suggested to be vital for having crossflow effective in 3-D boundary layer transition. In the presented paper here, this idea is questioned evaluating the results of an experimental investigation conducted on swept flat plates under the ab...

Failure rates in Barsebaeck-1 reactor coolant pressure boundary piping. An application of a piping failure database

Energy Technology Data Exchange (ETDEWEB)

Lydell, B. [RSA Technologies, Vista, CA (United States)

1999-05-01

This report documents an application of a piping failure database to estimate the frequency of leak and rupture in reactor coolant pressure boundary piping. The study used Barsebaeck-1 as reference plant. The study tried two different approaches to piping failure rate estimation: 1) PSA-style, simple estimation using Bayesian statistics, and 2) fitting of statistical distribution to failure data. A large, validated database on piping failures (like the SKI-PIPE database) supports both approaches. In addition to documenting leak and rupture frequencies, the SKI report describes the use of piping failure data to estimate frequency of medium and large loss of coolant accidents (LOCAs). This application study was co sponsored by Barsebaeck Kraft AB and SKI Research 41 refs, figs, tabs

Pressure Dependent Decomposition Kinetics of the Energetic Material HMX up to 3.6 GPa

Energy Technology Data Exchange (ETDEWEB)

Glascoe, E A; Zaug, J M; Burnham, A K

2009-05-29

The effect of pressure on the thermal decomposition rate of the energetic material HMX was studied. HMX was precompressed in a diamond anvil cell (DAC) and heated at various rates. The parent species population was monitored as a function of time and temperature using Fourier transform infrared (FTIR) spectroscopy. Decomposition rates were determined by fitting the fraction reacted to the extended-Prout-Tompkins nucleation-growth model and the Friedman isoconversional method. The results of these experiments and analysis indicate that pressure accelerates the decomposition at low to moderate pressures (i.e. between ambient pressure and 1 GPa) and decelerates the decomposition at higher pressures. The decomposition acceleration is attributed to pressure enhanced autocatalysis whereas the deceleration at high pressures is attributed pressure inhibiting bond homolysis step(s), which would result in an increase in volume. These results indicate that both {beta} and {delta} phase HMX are sensitive to pressure in the thermally induced decomposition kinetics.

Abrasive Wear of AlSi12-Al2O3 Composite Materials Manufactured by Pressure Infiltration

Directory of Open Access Journals (Sweden)

Kremzer M.

2016-09-01

Full Text Available The aim of this study is to investigate tribological properties of EN AC-AlSi12 alloy composite materials matrix manufactured by pressure infiltration of Al2O3 porous preforms. In the paper, a technique of manufacturing composite materials was described in detail as well as wear resistance made on pin on disc was tested. Metallographic observations of wear traces of tested materials using stereoscopic and confocal microscopy were made. Studies allow concluding that obtained composite materials have much better wear resistance than the matrix alloy AlSi12. It was further proved that the developed technology of their preparation consisting of pressure infiltration of porous ceramic preforms can find a practical application.

Fabrication techniques of metal liner used for pressure vessels made by composite material

International Nuclear Information System (INIS)

Takahashi, W.K.; Al-Qureshi, H.A.

1982-01-01

Different viable techniques for the manufacturing of metal liner used for pressure vessels are presented. The aim of these metal liner is to avoid the fluid leakage from the pressurized vessel and to serve as a mandreal to be wound by composite material. The studied techniques are described and the practical results are illustrated. Finally a comparative study of the manufacturing techniques is made in order to define the process that furnishes the metal liner with the best characteristics. The advantages offered by these type of pressure vessels when compared with the conventional metallic vessels, are also presented. (Author) [pt

Shakedown boundary determination of a 90° back-to-back pipe bend subjected to steady internal pressures and cyclic in-plane bending moments

International Nuclear Information System (INIS)

Abdalla, Hany F.

2014-01-01

No experimental data exist within open literature, to the best knowledge of the author, for determining shakedown boundaries of 90° back-to-back pipe bends. Ninety degree back-to-back pipe bends are extensively utilized within piping networks of nuclear submarines and modern turbofan aero-engines where space limitation is considered a paramount concern. In the current research, the 90° back-to-back pipe bend setup analyzed is subjected to a spectrum of steady internal pressures and cyclic in-plane bending moments. A previously developed direct non-cyclic simplified technique for determining elastic shakedown limit loads is utilized to generate the elastic shakedown boundary of the analyzed structure. The simplified technique outcomes showed excellent correlation with the results of full elastic–plastic cyclic loading finite element simulations. - Highlights: • No shakedown experimental data exist for 90° back-to-back pipe bends. • A non-cyclic technique is utilized to generate the elastic shakedown boundary. • The non-cyclic technique succeeded in generating the structure's Bree diagram. • The non-cyclic technique correlated well with full cyclic loading FE simulations

GPU-based, parallel-line, omni-directional integration of measured acceleration field to obtain the 3D pressure distribution

Science.gov (United States)

Wang, Jin; Zhang, Cao; Katz, Joseph

2016-11-01

A PIV based method to reconstruct the volumetric pressure field by direct integration of the 3D material acceleration directions has been developed. Extending the 2D virtual-boundary omni-directional method (Omni2D, Liu & Katz, 2013), the new 3D parallel-line omni-directional method (Omni3D) integrates the material acceleration along parallel lines aligned in multiple directions. Their angles are set by a spherical virtual grid. The integration is parallelized on a Tesla K40c GPU, which reduced the computing time from three hours to one minute for a single realization. To validate its performance, this method is utilized to calculate the 3D pressure fields in isotropic turbulence and channel flow using the JHU DNS Databases (http://turbulence.pha.jhu.edu). Both integration of the DNS acceleration as well as acceleration from synthetic 3D particles are tested. Results are compared to other method, e.g. solution to the Pressure Poisson Equation (e.g. PPE, Ghaemi et al., 2012) with Bernoulli based Dirichlet boundary conditions, and the Omni2D method. The error in Omni3D prediction is uniformly low, and its sensitivity to acceleration errors is local. It agrees with the PPE/Bernoulli prediction away from the Dirichlet boundary. The Omni3D method is also applied to experimental data obtained using tomographic PIV, and results are correlated with deformation of a compliant wall. ONR.

Irradiation experiments on materials for core internals, pressure vessel and fuel cladding

Energy Technology Data Exchange (ETDEWEB)

Tsukada, Takashi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-03-01

Materials degradation due to the aging phenomena is one of the key issues for the life assessment and extension of the light water reactors (LWRs). This presentation introduces JAERI`s activities in the field of LWR material researches which utilize the research and testing reactors for irradiation experiments. The activities are including the material studies for the core internals, pressure vessel and fuel cladding. These materials are exposed to the neutron/gamma radiation and high temperature water environments so that it is worth reviewing their degradation phenomena as the continuum. Three topics are presented; For the core internal materials, the irradiation assisted stress corrosion cracking (IASCC) of austenitic stainless steels is the present major concern. At JAERI the effects of alloying elements on IASCC have been investigated through the post-irradiation stress corrosion cracking tests in high-temperature water. The radiation embrittlement of pressure vessel steels is still a significant issue for LWR safety, and at JAERI some factors affecting the embrittlement behavior such as a dose rate have been investigated. Waterside corrosion of Zircaloy fuel cladding is one of the limiting factors in fuel rod performance and an in-situ measurement of the corrosion rate in high-temperature water was performed in JMTR. To improve the reliability of experiments and to extent the applicability of experimental techniques, a mutual utilization of the technical achievements in those irradiation experiments is desired. (author)

Ultimate load analysis of prestressed concrete reactor pressure vessels considering a general material law

International Nuclear Information System (INIS)

Schimmelpfennig, K.

1975-01-01

A method of analysis is presented, by which progressive fracture processes in axisymmetric prestressed concrete pressure vessels during increasing internal pressure can be evaulated by means of a continuum calculation considering a general material law. Formulations used in the analysis concerning material behaviour are derived on one hand from appropriate results of testing small concrete specimens, and are on the other hand gained by parametric studies in order to solve questions still existing by recalulating fracture tests on concrete bodies with more complex states of stress. Due attention is focussed on investigating the behaviour of construction members subjected to high shear forces (end slabs.). (Auth.)

Repair-welding technology of irradiated materials - WIM project

International Nuclear Information System (INIS)

Nakata, K.; Oishi, M.

1998-01-01

A new project on the development of repair-welding technology for core internals and reactor (pressure) vessel, consigned by the Ministry of International Trade and Industry (MITI), has been started from October 1997. The objective of the project is classified into three points as follows: (1) to develop repair-welding techniques for neutron irradiated materials, (2) to prove the availability of the techniques for core internals and reactor (pressure) vessel, and (3) to recommend the updated repair-welding for the Technical Rules and Standards. Total planning, neutron irradiation, preparation of welding equipment are now in progress. The materials are austenitic stainless steels and a low alloy steel. Neutron irradiation is performed using test reactors. In order to suppress the helium aggregation along grain boundaries, low heat input welding techniques, such as laser, low heat input TIG and friction weldings, will be applied. (author)

Grain boundary segregation and intergranular failure

International Nuclear Information System (INIS)

White, C.L.

1980-01-01

Trace elements and impurities often segregate strongly to grain boundaries in metals and alloys. Concentrations of these elements at grain boundaries are often 10 3 to 10 5 times as great as their overall concentration in the alloy. Because of such segregation, certain trace elements can exert a disproportionate influence on material properties. One frequently observed consequence of trace element segregation to grain boundaries is the occurrence of grain boundary failure and low ductility. Less well known are incidences of improved ductility and inhibition of grain boundary fracture resulting from trace element segregation to grain boundaries in certain systems. An overview of trace element segregation and intergranular failure in a variety of alloy systems as well as preliminary results from studies on Al 3% Li will be presented

Modelling of HTR Confinement Behaviour during Accidents Involving Breach of the Helium Pressure Boundary

Directory of Open Access Journals (Sweden)

Joan Fontanet

2009-01-01

Full Text Available Development of HTRs requires the performance of a thorough safety study, which includes accident analyses. Confinement building performance is a key element of the system since the behaviour of aerosol and attached fission products within the building is of an utmost relevance in terms of the potential source term to the environment. This paper explores the available simulation capabilities (ASTEC and CONTAIN codes and illustrates the performance of a postulated HTR vented confinement under prototypical accident conditions by a scoping study based on two accident sequences characterized by Helium Pressure Boundary breaches, a small and a large break. The results obtained indicate that both codes predict very similar thermal-hydraulic responses of the confinement both in magnitude and timing. As for the aerosol behaviour, both codes predict that most of the inventory coming into the confinement is eventually depleted on the walls and only about 1% of the aerosol dust is released to the environment. The crosscomparison of codes states that largest differences are in the intercompartmental flows and the in-compartment gas composition.

Planetary boundaries: exploring the safe operating space for humanity

Science.gov (United States)

Johan Rockström; Will Steffen; Kevin Noone; Asa Persson; F. Stuart Chapin; Eric Lambin; Timothy M. Lenton; Marten Scheffer; Carl Folke; Hans Joachim Schellnhuber; Björn Nykvist; Cynthia A. de Wit; Terry Hughes; Sander van der Leeuw; Henning Rodhe; Sverker Sörlin; Peter K. Snyder; Robert Costanza; Uno Svedin; Malin Falkenmark; Louise Karlberg; Robert W. Corell; Victoria J. Fabry; James Hansen; Brian Walker; Diana Liverman; Katherine Richardson; Paul Crutzen; Jonathan Foley

2009-01-01

Anthropogenic pressures on the Earth System have reached a scale where abrupt global environmental change can no longer be excluded. We propose a new approach to global sustainability in which we define planetary boundaries within which we expect that humanity can operate safely. Transgressing one or more planetary boundaries may be deleterious or even catastrophic due...

Characteristics of wall pressure over wall with permeable coating

Energy Technology Data Exchange (ETDEWEB)

Song, Woo Seog; Shin, Seungyeol; Lee, Seungbae [Inha Univ., Incheon (Korea, Republic of)

2012-11-15

Fluctuating wall pressures were measured using an array of 16 piezoelectric transducers beneath a turbulent boundary layer. The coating used in this experiment was an open cell, urethane type foam with a porosity of approximately 50 ppi. The ultimate objective of the coating is to provide a mechanical filter to reduce the wall pressure fluctuations. The ultimate objective of the coating is to provide a mechanical filter to reduce the wall pressure fluctuations. The boundary layer on the flat plate was measured by using a hot wire probe, and the CPM method was used to determine the skin friction coefficient. The wall pressure autospectra and streamwise wavenumber frequency spectra were compared to assess the attenuation of the wall pressure field by the coating. The coating is shown to attenuate the convective wall pressure energy. However, the relatively rough surface of the coating in this investigation resulted in a higher mean wall shear stress, thicker boundary layer, and higher low frequency wall pressure spectral levels compared to a smooth wall.

Some techniques and results from high-pressure shock-wave experiments utilizing the radiation from shocked transparent materials

International Nuclear Information System (INIS)

McQueen, R.G.; Fritz, J.N.

1981-01-01

It has been known for many years that some transparent materials emit radiation when shocked to high pressures. This property was used to determine the temperature of shocked fused and crystal quartz, which in turn allowed the thermal expansion of SiO 2 at high pressure and also the specific heat to be calculated. Once the radiative energy as a function of pressure is known for one material it is shown how this can be used to determine the temperature of other transparent materials. By the nature of the experiments very accurate shock velocities can be measured and hence high quality equation of state data obtained. Some techniques and results are presented on measuring sound velocities from symmetrical impact of nontransparent materials using radiation emitting transparent analyzers, and on nonsymmetrical impact experiments on transparent materials. Because of special requirements in the later experiments, techniques were developed that lead to very high-precision shock-wave data. Preliminary results, using these techniques are presented for making estimates of the melting region and the yield strength of some metals under strong shock conditions

Liquid radioactive waste processing system for pressurized water reactor plants

International Nuclear Information System (INIS)

Anon.

1976-01-01

This Standard sets forth design, construction, and performance requirements, with due consideration for operation, of the Liquid Radioactive Waste Processing System for pressurized water reactor plants for design basis inputs. For the purpose of this Standard, the Liquid Radioactive Waste Processing System begins at the interfaces with the reactor coolant pressure boundary and the interface valve(s) in lines from other systems, or at those sumps and floor drains provided for liquid waste with the potential of containing radioactive material; and it terminates at the point of controlled discharge to the environment, at the point of interface with the waste solidification system, and at the point of recycle back to storage for reuse

Fuselage boundary-layer refraction of fan tones radiated from an installed turbofan aero-engine.

Science.gov (United States)

Gaffney, James; McAlpine, Alan; Kingan, Michael J

2017-03-01

A distributed source model to predict fan tone noise levels of an installed turbofan aero-engine is extended to include the refraction effects caused by the fuselage boundary layer. The model is a simple representation of an installed turbofan, where fan tones are represented in terms of spinning modes radiated from a semi-infinite circular duct, and the aircraft's fuselage is represented by an infinitely long, rigid cylinder. The distributed source is a disk, formed by integrating infinitesimal volume sources located on the intake duct termination. The cylinder is located adjacent to the disk. There is uniform axial flow, aligned with the axis of the cylinder, everywhere except close to the cylinder where there is a constant thickness boundary layer. The aim is to predict the near-field acoustic pressure, and in particular, to predict the pressure on the cylindrical fuselage which is relevant to assess cabin noise. Thus no far-field approximations are included in the modelling. The effect of the boundary layer is quantified by calculating the area-averaged mean square pressure over the cylinder's surface with and without the boundary layer included in the prediction model. The sound propagation through the boundary layer is calculated by solving the Pridmore-Brown equation. Results from the theoretical method show that the boundary layer has a significant effect on the predicted sound pressure levels on the cylindrical fuselage, owing to sound radiation of fan tones from an installed turbofan aero-engine.

Intergranular fracture stress and phosphorus grain boundary segregation of a Mn-Ni-Mo steel

International Nuclear Information System (INIS)

Naudin, C.; Frund, J.M.; Pineau, A.

1999-01-01

Nuclear Reactor Pressure Vessel (RPV) steel A508 class 3 which is a low alloyed steel is not usually sensitive to reversible temper embrittlement when properly heat treated. However heterogeneous zones may be present in particular near the inner side of the vessel. These zones result from the segregation of the alloying elements (C, Mn, Ni, Mo) and impurities (S, P) taking place during solidification of the material. They are called segregated zones (or ghost lines). They can reach 2 mm thick along the radius and 30 mm long through the circumferential direction. Their susceptibility to reversible temper embrittlement is mainly due to grain boundary phosphorus segregation triggering brittle intergranular fracture when the material is tested at low temperature. In this material like in other steels the influence of some other alloying elements (Mo, Mn...) is clearly significant and should also be taken into account. But phosphorus effect has proved to be predominant. The aim of the present study is therefore to find out a quantitative relationship between grain boundary phosphorus segregation and critical intergranular fracture stress. A synthetic steel with a chemical composition representative of an average segregated zone was prepared for the present study. A number of heat treatments were applied to reach different embrittlement conditions. Then brittle fracture properties were obtained by performing cryogenic fracture tests on notched tensile specimens while the corresponding grain boundary phosphorus levels were measured by Auger electron spectroscopy. Systematic fractographic observations were carried out. Moreover an attempt to determine the influence of temperature on the critical intergranular fracture stress was made

Transonic shock wave. Boundary layer interaction at a convex wall

NARCIS (Netherlands)

Koren, B.; Bannink, W.J.

1984-01-01

A standard finite element procedure has been applied to the problem of transonic shock wave – boundary layer interaction at a convex wall. The method is based on the analytical Bohning-Zierep model, where the boundary layer is perturbed by a weak normal shock wave which shows a singular pressure

Boundary Slip and Surface Interaction: A Lattice Boltzmann Simulation

International Nuclear Information System (INIS)

Yan-Yan, Chen; Hua-Bing, Li; Hou-Hui, Yi

2008-01-01

The factors affecting slip length in Couette geometry flows are analysed by means of a two-phase mesoscopic lattice Boltzmann model including non-ideal fluid-fluid and fluid-wall interactions. The main factors influencing the boundary slip are the strength of interactions between fluid-fluid and fluid-wall particles. Other factors, such as fluid viscosity, bulk pressure may also change the slip length. We find that boundary slip only occurs under a certain density (bulk pressure). If the density is large enough, the slip length will tend to zero. In our simulations, a low density layer near the wall does not need to be postulated a priori but emerges naturally from the underlying non-ideal mesoscopic dynamics. It is the low density layer that induces the boundary slip. The results may be helpful to understand recent experimental observations on the slippage of micro flows

Molten material relocation into the lower plenum: a status report

International Nuclear Information System (INIS)

1998-09-01

This report, prepared by the task group 'Degraded Core Cooling' (DCC) for the CSNI, summarizes the experimental and theoretical knowledge of molten material relocation from a degraded core to the lower plenum of the reactor vessel under the main severe accident scenarios envisaged for both PWRs and BWRs, and boundary conditions. Consequences of movement of material to the lower head are considered with respect to the potential for reactor pressure vessel failure. The following models are reviewed: SCDAP/RELAP5, ICARE/CATHARE, ATHLET-CD/KESS, MELCOR, MAAP4, ESCADRE, etc.

Pressurized Thermal Shock, Pts

International Nuclear Information System (INIS)

Boyd, C.

2008-01-01

Pressurized Thermal Shock (Pts) refers to a condition that challenges the integrity of the reactor pressure vessel. The root cause of this problem is the radiation embrittlement of the reactor vessel. This embrittlement leads to an increase in the reference temperature for nil ductility transition (RTNDT). RTNDT can increase to the point where the reactor vessel material can loose fracture toughness during overcooling events. The analysis of the risk of having a Pts for a specific plant is a multi-disciplinary problem involving probabilistic risk analysis (PRA), thermal-hydraulic analysis, and ultimately a structural and fracture analysis of the vessel wall. The PRA effort involves the postulation of overcooling events and ultimately leads to an integrated risk analysis. The thermal-hydraulic effort involves the difficult task of predicting the system behavior during a postulated overcooling scenario with a special emphasis on predicting the thermal and mechanic loadings on the reactor pressure vessel wall. The structural and fracture analysis of the reactor vessel wall relies on the thermal-hydraulic conditions as boundary conditions. The US experience has indicated that medium and large diameter primary system breaks dominate the risk of Pts along with scenarios that involve a stuck open valve (and associated system cooldown) that recloses resulting in system re-pressurization while the vessel wall is cool.

Total dose radiation effects of pressure sensors fabricated on uni-bond-SOI materials

International Nuclear Information System (INIS)

Zhu Shiyang; Huang Yiping; Wang Jin; Li Anzhen; Shen Shaoqun; Bao Minhang

2001-01-01

Piezoresistive pressure sensors with a twin-island structure were successfully fabricated using high quality Uni-bond-SOI (On Insulator) materials. Since the piezoresistors were structured by the single crystalline silicon overlayer of the SOI wafer and were totally isolated by the buried SiO 2 , the sensors are radiation-hard. The sensitivity and the linearity of the pressure sensors keep their original values after being irradiated by 60 Co γ-rays up to 2.3 x 10 4 Gy(H 2 O). However, the offset voltage of the sensor has a slight drift, increasing with the radiation dose. The absolute value of the offset voltage deviation depends on the pressure sensor itself. For comparison, corresponding polysilicon pressure sensors were fabricated using the similar process and irradiated at the same condition

Boundary element method for normal non-adhesive and adhesive contacts of power-law graded elastic materials

Science.gov (United States)

Li, Qiang; Popov, Valentin L.

2018-03-01

Recently proposed formulation of the boundary element method for adhesive contacts has been generalized for contacts of power-law graded materials with and without adhesion. Proceeding from the fundamental solution for single force acting on the surface of an elastic half space, first the influence matrix is obtained for a rectangular grid. The inverse problem for the calculation of required stress in the contact area from a known surface displacement is solved using the conjugate-gradient technique. For the transformation between the stresses and displacements, the Fast Fourier Transformation is used. For the adhesive contact of graded material, the detachment criterion based on the energy balance is proposed. The method is validated by comparison with known exact analytical solutions as well as by proving the independence of the mesh size and the grid orientation.

Airfoil boundary layer separation and control at low Reynolds numbers

Energy Technology Data Exchange (ETDEWEB)

Yarusevych, S.; Sullivan, P.E. [University of Toronto, Department of Mechanical and Industrial Engineering, Toronto, ON (Canada); Kawall, J.G. [Ryerson University, Department of Mechanical and Industrial Engineering, Toronto, ON (Canada)

2005-04-01

The boundary layer separation on a NACA 0025 airfoil was studied experimentally via hot-wire anemometry and surface pressure measurements. The results provide added insight into periodic boundary layer control, suggesting that matching the excitation frequency with the most amplified disturbance in the separated shear layer is optimal for improving airfoil performance. (orig.)

Dynamism or Disorder at High Pressures?

Science.gov (United States)

Angel, R. J.; Bismayer, U.; Marshall, W. G.

2002-12-01

Phase transitions in minerals at elevated temperatures typically involve dynamics as a natural consequence of the increase in thermal energy available to the system. Classic examples include quartz, cristobalite, and carbonates in which the high-temperature, high symmetry phase is dynamically disordered. This disorder has important thermodynamic consequences, including displacement and curvature of phase boundaries (e.g. calcite-aragonite). In other minerals such as clinopyroxenes and anorthite feldspar, the dynamic behaviour is restricted to the neighbourhood of the phase transition. The fundamental question is whether increasing pressure generally suppresses such dynamic behaviour (as in anorthite; Angel, 1988), or not. In the latter case it must be included in thermodynamic models of high-pressure phase equilibria and seismological modelling of the mantle; the potential dynamics and softening in stishovite may provide the critical observational constraint on the presence or otherwise of free silica in the lower mantle. We have continued to use the lead phosphate as a prototype ferroelastic in which to understand dynamic behaviour, simply because its dynamics and transition behaviour is far better characterised than any mineral. Furthermore, the phase transition is at a pressure where experimental difficulties do not dominate the experimental results. Our previous neutron diffraction study (Angel et al., 2001) revealed that some disorder, either dynamic or static, is retained in the high-symmetry, high-pressure phase just above the phase transition. New neutron diffraction data on the pure material now suggests that this disorder slowly decreases with increasing pressure until at twice the transition pressure it is ordered. Further data for doped material provides insights into the nature of this disorder. Angel (1988) Amer. Mineral. 73:1114. Angel et al (2001) J PhysC 13: 5353.

Problems of matter-antimatter boundary layers

International Nuclear Information System (INIS)

Lehnert, B.

1975-01-01

This paper outlines the problems of the quasi-steady matter-antimatter boundary layers discussed in Klein-Alfven's cosmological theory, and a crude model of the corresponding ambiplasma balance is presented: (i) at interstellar particle densities, no well-defined boundary layer can exist in presence of neutral gas, nor can such a layer be sustained in an unmagnetized fully ionized ambiplasma. (ii) Within the limits of applicability of the present model, sharply defined boundary layers are under certain conditions found to exist in a magnetized ambiplasma. Thus, at beta values less than unity, a steep pressure drop of the low-energy components of matter and antimatter can be balanced by a magnetic field and the electric currents in the ambiplasma. (iii) The boundary layer thickness is of the order of 2x 0 approximately 10/BT 0 sup(1/4) meters, where B is the magnetic field strength in MKS units and T 0 the characteristic temperature of the low-energy components in the layer. (Auth.)

Integration of piezo-capacitive and piezo-electric nanoweb based pressure sensors for imaging of static and dynamic pressure distribution.

Science.gov (United States)

Jeong, Y J; Oh, T I; Woo, E J; Kim, K J

2017-07-01

Recently, highly flexible and soft pressure distribution imaging sensor is in great demand for tactile sensing, gait analysis, ubiquitous life-care based on activity recognition, and therapeutics. In this study, we integrate the piezo-capacitive and piezo-electric nanowebs with the conductive fabric sheets for detecting static and dynamic pressure distributions on a large sensing area. Electrical impedance tomography (EIT) and electric source imaging are applied for reconstructing pressure distribution images from measured current-voltage data on the boundary of the hybrid fabric sensor. We evaluated the piezo-capacitive nanoweb sensor, piezo-electric nanoweb sensor, and hybrid fabric sensor. The results show the feasibility of static and dynamic pressure distribution imaging from the boundary measurements of the fabric sensors.

A pressure-amplifying framework material with negative gas adsorption transitions.

Science.gov (United States)

Krause, Simon; Bon, Volodymyr; Senkovska, Irena; Stoeck, Ulrich; Wallacher, Dirk; Többens, Daniel M; Zander, Stefan; Pillai, Renjith S; Maurin, Guillaume; Coudert, François-Xavier; Kaskel, Stefan

2016-04-21

Adsorption-based phenomena are important in gas separations, such as the treatment of greenhouse-gas and toxic-gas pollutants, and in water-adsorption-based heat pumps for solar cooling systems. The ability to tune the pore size, shape and functionality of crystalline porous coordination polymers--or metal-organic frameworks (MOFs)--has made them attractive materials for such adsorption-based applications. The flexibility and guest-molecule-dependent response of MOFs give rise to unexpected and often desirable adsorption phenomena. Common to all isothermal gas adsorption phenomena, however, is increased gas uptake with increased pressure. Here we report adsorption transitions in the isotherms of a MOF (DUT-49) that exhibits a negative gas adsorption; that is, spontaneous desorption of gas (methane and n-butane) occurs during pressure increase in a defined temperature and pressure range. A combination of in situ powder X-ray diffraction, gas adsorption experiments and simulations shows that this adsorption behaviour is controlled by a sudden hysteretic structural deformation and pore contraction of the MOF, which releases guest molecules. These findings may enable technologies using frameworks capable of negative gas adsorption for pressure amplification in micro- and macroscopic system engineering. Negative gas adsorption extends the series of counterintuitive phenomena such as negative thermal expansion and negative refractive indices and may be interpreted as an adsorptive analogue of force-amplifying negative compressibility transitions proposed for metamaterials.

Fiat or bona fide boundary--a matter of granular perspective.

Directory of Open Access Journals (Sweden)

Lars Vogt

Full Text Available Distinguishing bona fide (i.e. natural and fiat (i.e. artificial physical boundaries plays a key role for distinguishing natural from artificial material entities and is thus relevant to any scientific formal foundational top-level ontology, as for instance the Basic Formal Ontology (BFO. In BFO, the distinction is essential for demarcating two foundational categories of material entity: object and fiat object part. The commonly used basis for demarcating bona fide from fiat boundary refers to two criteria: (i intrinsic qualities of the boundary bearers (i.e. spatial/physical discontinuity, qualitative heterogeneity and (ii mind-independent existence of the boundary. The resulting distinction of bona fide and fiat boundaries is considered to be categorial and exhaustive.By Referring to various examples from biology, we demonstrate that the hitherto used distinction of boundaries is not categorial: (i spatial/physical discontinuity is a matter of scale and the differentiation of bona fide and fiat boundaries is thus granularity-dependent, and (ii this differentiation is not absolute, but comes in degrees. By reducing the demarcation criteria to mind-independence and by also considering dispositions and historical relations of the bearers of boundaries, instead of only considering their spatio-structural properties, we demonstrate with various examples that spatio-structurally fiat boundaries can nevertheless be mind-independent and in this sense bona fide.We argue that the ontological status of a given boundary is perspective-dependent and that the strictly spatio-structural demarcation criteria follow a static perspective that is ignorant of causality and the dynamics of reality. Based on a distinction of several ontologically independent perspectives, we suggest different types of boundaries and corresponding material entities, including boundaries based on function (locomotion, physiology, ecology, development, reproduction and common history

New atom probe approaches to studying segregation in nanocrystalline materials

International Nuclear Information System (INIS)

Samudrala, S.K.; Felfer, P.J.; Araullo-Peters, V.J.; Cao, Y.; Liao, X.Z.; Cairney, J.M.

2013-01-01

Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. - Highlights: ► New data treatment methods allow delineation of grain boundaries, even without segregation. ► Proxigrams calculated from the surfaces accurately show the extent of segregation. ► Tessellation of the data volume can be used to map the Gibbsian interfacial excess

New atom probe approaches to studying segregation in nanocrystalline materials

Energy Technology Data Exchange (ETDEWEB)

Samudrala, S.K.; Felfer, P.J.; Araullo-Peters, V.J. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); The Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia); Cao, Y.; Liao, X.Z. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); Cairney, J.M., E-mail: julie.cairney@sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); The Australian Centre for Microscopy and Microanalysis, The University of Sydney, NSW 2006 (Australia)

2013-09-15

Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping. - Highlights: ► New data treatment methods allow delineation of grain boundaries, even without segregation. ► Proxigrams calculated from the surfaces accurately show the extent of segregation. ► Tessellation of the data volume can be used to map the Gibbsian interfacial excess.

Container materials in environments of corroded spent nuclear fuel

Science.gov (United States)

Huang, F. H.

1996-07-01

Efforts to remove corroded uranium metal fuel from the K Basins wet storage to long-term dry storage are underway. The multi-canister overpack (MCO) is used to load spent nuclear fuel for vacuum drying, staging, and hot conditioning; it will be used for interim dry storage until final disposition options are developed. Drying and conditioning of the corroded fuel will minimize the possibility of gas pressurization and runaway oxidation. During all phases of operations the MCO is subjected to radiation, temperature and pressure excursions, hydrogen, potential pyrophoric hazard, and corrosive environments. Material selection for the MCO applications is clearly vital for safe and efficient long-term interim storage. Austenitic stainless steels (SS) such as 304L SS or 316L SS appear to be suitable for the MCO. Of the two, Type 304L SS is recommended because it possesses good resistance to chemical corrosion, hydrogen embrittlement, and radiation-induced corrosive species. In addition, the material has adequate strength and ductility to withstand pressure and impact loading so that the containment boundary of the container is maintained under accident conditions without releasing radioactive materials.

Intrinsic stress in ZrN thin films: Evaluation of grain boundary contribution from in situ wafer curvature and ex situ x-ray diffraction techniques

International Nuclear Information System (INIS)

Koutsokeras, L. E.; Abadias, G.

2012-01-01

Low-mobility materials, like transition metal nitrides, usually undergo large residual stress when sputter-deposited as thin films. While the origin of stress development has been an active area of research for high-mobility materials, atomistic processes are less understood for low-mobility systems. In the present work, the contribution of grain boundary to intrinsic stress in reactively magnetron-sputtered ZrN films is evaluated by combining in situ wafer curvature measurements, providing information on the overall biaxial stress, and ex situ x-ray diffraction, giving information on elastic strain (and related stress) inside crystallites. The thermal stress contribution was also determined from the in situ stress evolution during cooling down, after deposition was stopped. The stress data are correlated with variations in film microstructure and growth energetics, in the 0.13-0.42 Pa working pressure range investigated, and discussed based on existing stress models. At low pressure (high energetic bombardment conditions), a large compressive stress is observed due to atomic peening, which induces defects inside crystallites but also promotes incorporation of excess atoms in the grain boundary. Above 0.3-0.4 Pa, the adatom surface mobility is reduced, leading to the build-up of tensile stress resulting from attractive forces between under-dense neighbouring column boundary and possible void formation, while crystallites can still remain under compressive stress.

A friction test between steel and a brittle material at high contact pressures and high sliding velocities

Directory of Open Access Journals (Sweden)

Picart D.

2012-08-01

Full Text Available Our aim is to characterize the interface behaviour between an aggregate material and steel. This work focuses on contact pressures and sliding velocities reaching 100 MPa and 10 m/s. The set-up consists in a cylindrical sample of the aggregate material which slips into a steel tube. The tube is both a confinement vessel and a sliding surface. Thanks to confinement, the material can be tested under high stresses without failure. The interface pressure is generated by an axial compression. The sample is pressed on a spring, so it can be simultaneously compressed and rubbed on the tube. The set-up has been tested in the case of a quasi-static loading and the 100 MPa pressure has been reached. Then the set-up was mounted on a Split Hopkinson Pressure Bar device in order to reach higher velocities. Numerical simulations have been realized to check the feasibility and the relevance of this dynamic test. These results are analysed and compared to the experimental ones.

Swelling characteristics of buffer material

International Nuclear Information System (INIS)

Suzuki, Hideaki; Fujita, Tomoo

1999-12-01

After emplacement of the engineered barrier system (EBS), it is expected that the near-field environment will be impacted by phenomena such as heat dissipation by conduction and other heat transfer mechanism, infiltration of groundwater from the surrounding rock into the EBS, generation of swelling pressure in the buffer due to water infiltration and the stress imposed by the overburden pressure. These phenomena are not all independent, but can be strongly influenced by, and coupled with, each other. Evaluating these coupled thermo-hydro-mechanical phenomena is important in order to clarify the initial transient behavior of the engineered barrier system within the near-field. This report describes the results on measurement of swelling amount and stress at boundary built up under restraint condition with water uptake. The following results are identified. (1) The swelling stress of buffer material at saturated condition tends to be independent of effects of pore water pressure and synthetic sea water, and to decrease with increasing temperature. The swelling stress can be explained by the effective dry density. (2) The strain due to swelling estimated from the results of the swelling amount of buffer material is proportional to swelling stress. (3) The swelling stress and strain under unsaturated condition increase with water uptake. (author)

Boundary-Layer Bypass Transition Over Large-Scale Bodies

Science.gov (United States)

2016-12-16

behaviour of the velocity and pressure changes with the curvature. This work aims to extend the results of the flat-plate boundary layer to a Rankine...example, consume an enormous amount of energy due to friction, many works have been directed to the suppression of transitional boundary layer disturbances...decrease of the enormous amount of energy consumed by airplanes during flight, moreover flight costs and aerodynamic noise could be reduced and number

Boundary value problems of the circular cylinders in the strain-gradient theory of linear elasticity

International Nuclear Information System (INIS)

Kao, B.G.

1979-11-01

Three boundary value problems in the strain-gradient theory of linear elasticity are solved for circular cylinders. They are the twisting of circular cylinder, uniformly pressuring of concentric circular cylinder, and pure-bending of simply connected cylinder. The comparisons of these solutions with the solutions in classical elasticity and in couple-stress theory reveal the differences in the stress fields as well as the apparent stress fields due to the influences of the strain-gradient. These aspects of the strain-gradient theory could be important in modeling the failure behavior of structural materials

Nonlinear vibration of a traveling belt with non-homogeneous boundaries

Science.gov (United States)

Ding, Hu; Lim, C. W.; Chen, Li-Qun

2018-06-01

Free and forced nonlinear vibrations of a traveling belt with non-homogeneous boundary conditions are studied. The axially moving materials in operation are always externally excited and produce strong vibrations. The moving materials with the homogeneous boundary condition are usually considered. In this paper, the non-homogeneous boundaries are introduced by the support wheels. Equilibrium deformation of the belt is produced by the non-homogeneous boundaries. In order to solve the equilibrium deformation, the differential and integral quadrature methods (DIQMs) are utilized to develop an iterative scheme. The influence of the equilibrium deformation on free and forced nonlinear vibrations of the belt is explored. The DIQMs are applied to solve the natural frequencies and forced resonance responses of transverse vibration around the equilibrium deformation. The Galerkin truncation method (GTM) is utilized to confirm the DIQMs' results. The numerical results demonstrate that the non-homogeneous boundary conditions cause the transverse vibration to deviate from the straight equilibrium, increase the natural frequencies, and lead to coexistence of square nonlinear terms and cubic nonlinear terms. Moreover, the influence of non-homogeneous boundaries can be exacerbated by the axial speed. Therefore, non-homogeneous boundary conditions of axially moving materials especially should be taken into account.

Science at the interface : grain boundaries in nanocrystalline metals.

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, Mark Andrew; Follstaedt, David Martin; Knapp, James Arthur; Brewer, Luke N.; Holm, Elizabeth Ann; Foiles, Stephen Martin; Hattar, Khalid M.; Clark, Blythe B.; Olmsted, David L.; Medlin, Douglas L.

2009-09-01

Interfaces are a critical determinant of the full range of materials properties, especially at the nanoscale. Computational and experimental methods developed a comprehensive understanding of nanograin evolution based on a fundamental understanding of internal interfaces in nanocrystalline nickel. It has recently been shown that nanocrystals with a bi-modal grain-size distribution possess a unique combination of high-strength, ductility and wear-resistance. We performed a combined experimental and theoretical investigation of the structure and motion of internal interfaces in nanograined metal and the resulting grain evolution. The properties of grain boundaries are computed for an unprecedented range of boundaries. The presence of roughening transitions in grain boundaries is explored and related to dramatic changes in boundary mobility. Experimental observations show that abnormal grain growth in nanograined materials is unlike conventional scale material in both the level of defects and the formation of unfavored phases. Molecular dynamics simulations address the origins of some of these phenomena.

Boundary-layer effects in droplet splashing

Science.gov (United States)

Riboux, Guillaume; Gordillo, Jose Manuel

2017-11-01

A drop falling onto a solid substrate will disintegrate into smaller parts when its impact velocity exceeds the so called critical velocity for splashing. Under these circumstances, the very thin liquid sheet ejected tangentially to the solid after the drop touches the substrate, lifts off as a consequence of the aerodynamic forces exerted on it and finally breaks into smaller droplets, violently ejected radially outwards, provoking the splash. Here, the tangential deceleration experienced by the fluid entering the thin liquid sheet is investigated making use of boundary layer theory. The velocity component tangent to the solid, computed using potential flow theory provides the far field boundary condition as well as the pressure gradient for the boundary layer equations. The structure of the flow permits to find a self similar solution of the boundary layer equations. This solution is then used to calculate the boundary layer thickness at the root of the lamella as well as the shear stress at the wall. The splash model presented in, which is slightly modified to account for the results obtained from the boundary layer analysis, provides a very good agreement between the measurements and the predicted values of the critical velocity for the splash.

A simple and efficient outflow boundary condition for the incompressible Navier–Stokes equations

Directory of Open Access Journals (Sweden)

Yibao Li

2017-01-01

Full Text Available Many researchers have proposed special treatments for outlet boundary conditions owing to lack of information at the outlet. Among them, the simplest method requires a large enough computational domain to prevent or reduce numerical errors at the boundaries. However, an efficient method generally requires special treatment to overcome the problems raised by the outlet boundary condition used. For example, mass flux is not conserved and the fluid field is not divergence-free at the outlet boundary. Overcoming these problems requires additional computational cost. In this paper, we present a simple and efficient outflow boundary condition for the incompressible Navier–Stokes equations, aiming to reduce the computational domain for simulating flow inside a long channel in the streamwise direction. The proposed outflow boundary condition is based on the transparent equation, where a weak formulation is used. The pressure boundary condition is derived by using the Navier–Stokes equations and the outlet flow boundary condition. In the numerical algorithm, a staggered marker-and-cell grid is used and temporal discretization is based on a projection method. The intermediate velocity boundary condition is consistently adopted to handle the velocity–pressure coupling. Characteristic numerical experiments are presented to demonstrate the robustness and accuracy of the proposed numerical scheme. Furthermore, the agreement of computational results from small and large domains suggests that our proposed outflow boundary condition can significantly reduce computational domain sizes.

Atomic-scale processes revealing dynamic twin boundary strengthening mechanisms in face-centered cubic materials

International Nuclear Information System (INIS)

Yang, Z.Q.; Chisholm, M.F.; He, L.L.; Pennycook, S.J.; Ye, H.Q.

2012-01-01

We report experimental investigations on interactions/reactions between dislocations and twin boundaries in Al. The absorption of screw dislocations via cross-slip and the production of stair-rods via reactions with non-screw dislocations were verified by atomic resolution imaging. Importantly, the resulting partial dislocations moving along twin boundaries can produce secondary sessile defects. These immobile defects act as obstacles to other dislocations and also serve to pin the twin boundaries. These findings show the atomic-level dynamics of the dislocation–twin boundary processes and the unique strengthening mechanism of twin boundaries in face-centered cubic metals.

Comparative evaluation of pressure generated on a simulated maxillary oral analog by impression materials in custom trays of different spacer designs: An in vitro study

Directory of Open Access Journals (Sweden)

Sakshi Chopra

2016-01-01

Full Text Available Introduction: Literature reveals that masticatory load on denture bearing tissues through complete dentures should be maximum on primary stress bearing areas and least on relief area in accordance with the histology of underlying tissues. A study to validate the existing beliefs was planned to compare the pressure on mucosa using selective pressure technique and minimal pressure technique, with the incorporation of two different impression materials utilizing the pressure sensors during secondary impression procedure. Materials and Methods: The study was performed using a maxillary analog. Three pressure sensors were imbedded in the oral analog, one in the mid palatine area and the other two in the right and left ridge crest. Custom trays of two different configurations were fabricated. The two impression materials tested were light body and zinc oxide eugenol. A total of 40 impressions were made. A constant weight of 1 kg was placed, and the pressure was recorded as initial and end pressures. Results: A significant difference in the pressure produced using different impression materials was found (P < 0.001. Light body vinyl polysiloxane produced significantly lesser pressure than zinc oxide eugenol impression materials. The presence of relief did affect the magnitude of pressure at various locations. Conclusion: All impression materials produced pressure during maxillary edentulous impression making. Tray modification is an important factor in changing the amount of pressure produced. The impression materials used also had a significant role to play on the pressures acting on the tissues during impression procedure. Clinical Implication: Light body VPS impression material may be recommended to achieve minimal pressure on the denture bearing tissues in both selective as well as minimal pressure techniques.

Study of some properties of point defects in grain boundaries

International Nuclear Information System (INIS)

Martin, Georges

1973-01-01

With the aim of deducing simple informations on the grain boundary core structure, we investigated self diffusion under hydrostatic pressure, impurity diffusion (In and Au), electromigration (Sb) along certain types of grain boundaries in Ag bicrystals, and the Moessbauer effect of 57 Co located in the grain boundaries of polycrystalline Be. Our results lead to the following conclusions: the formation of a vacancy like defects is necessary to grain boundary diffusion; solute atoms may release most of their elastic energy of dissolution as they segregate at the boundary; in an electrical field, the drift of Sb ions parallel to the boundary takes place toward the anode as in the bulk. The force on the grain boundary ions is larger than in the bulk; Moessbauer spectroscopy revealed the formation of Co-rich aggregates, which may proves important in the study of early stages of grain boundary precipitation. (author) [fr

Effect of beta phase composition and surface machining on the oxidation behavior of Zr-2.5Nb pressure tube material

International Nuclear Information System (INIS)

Nouduru, S.K.; Kiran Kumar, M.; Kain, V.; Khanna, A.S.

2015-01-01

Zr-2.5Nb is commonly used as the pressure tube material in pressurized heavy water reactors. it is also the pressure tube material for Advanced Heavy Water Reactor (AHWR) being developed indigenously in India with light water as coolant and water chemistry similar to Boiling Water Reactors (BWR). Oxidation of the pressure tube depends on various factors like material composition, microstructure, fabrication route, and water chemistry. In the present research, the role of the composition and morphology of second phase β on the high temperature and pressure oxidation behavior of Zr-2.5Nb pressure tube material in steam was systematically studied. The as-received pressure tube material (fabricated through cold worked and stress relieved, CWSR route) was subjected to selective heat treatments to generate microstructures containing predominantly β(Zr) (∼ 20% Nb) and β(Nb) (∼ 80% Nb) phases. The presence of such phases was characterized by X-ray diffraction and transmission electron microscopy-energy dispersive spectroscopy. Subsequently both the heat treated materials were subjected to surface machining. The Zr-2.5Nb material in different microstructural conditions was subjected to accelerated oxidation exposures in steam at 400 C. degrees, and 10 MPa pressure up to 30 days. Raman spectroscopy was carried out on the oxide surfaces to observe the variation in tetragonal versus monoclinic phase fractions with oxidation duration. The microstructure consisting of predominantly β(Nb) showed a relatively improved oxidation resistance as compared to the one with predominantly β(Zr). The tetragonal phase fraction in the oxide film decreased with oxidation time in all microstructural conditions and was found to be the least in the microstructure containing β(Zr) after 10 days of exposures. The explanation for the observed higher oxidation resistance of β(Nb) microstructure lies in the context of depleted matrix Nb content in the case of β(Nb). Surface machining

Sterilization of beehive material with a double inductively coupled low pressure plasma

International Nuclear Information System (INIS)

Priehn, M; Leichert, L I; Denis, B; Awakowicz, P; Aumeier, P; Kirchner, W H

2016-01-01

American Foulbrood is a severe, notifiable disease of the honey bee. It is caused by infection of bee larvae with spores of the gram-positive bacterium Paenibacillus larvae . Spores of this organism are found in high numbers in an infected hive and are highly resistant to physical and chemical inactivation methods. The procedures to rehabilitate affected apiaries often result in the destruction of beehive material. In this study we assess the suitability of a double inductively coupled low pressure plasma as a non-destructive, yet effective alternative inactivation method for bacterial spores of the model organism Bacillus subtilis on beehive material. Plasma treatment was able to effectively remove spores from wax, which, under protocols currently established in veterinary practice, normally is destroyed by ignition or autoclaved for sterilization. Spores were removed from wooden surfaces with efficacies significantly higher than methods currently used in veterinary practice, such as scorching by flame treatment. In addition, we were able to non-destructively remove spores from the highly delicate honeycomb wax structures, potentially making treatment of beehive material with double inductively coupled low pressure plasma part of a fast and reliable method to rehabilitate infected bee colonies with the potential to re-use honeycombs. (paper)

Characterization and Modeling of Grain Boundary Chemistry Evolution in Ferritic Steels under Irradiation

Energy Technology Data Exchange (ETDEWEB)

Marquis, Emmanuelle [Univ. of Michigan, Ann Arbor, MI (United States); Wirth, Brian [Univ. of Tennessee, Knoxville, TN (United States); Was, Gary [Univ. of Michigan, Ann Arbor, MI (United States)

2016-03-28

Ferritic/martensitic (FM) steels such as HT-9, T-91 and NF12 with chromium concentrations in the range of 9-12 at.% Cr and high Cr ferritic steels (oxide dispersion strengthened steels with 12-18% Cr) are receiving increasing attention for advanced nuclear applications, e.g. cladding and duct materials for sodium fast reactors, pressure vessels in Generation IV reactors and first wall structures in fusion reactors, thanks to their advantages over austenitic alloys. Predicting the behavior of these alloys under radiation is an essential step towards the use of these alloys. Several radiation-induced phenomena need to be taken into account, including phase separation, solute clustering, and radiation-induced segregation or depletion (RIS) to point defect sinks. RIS at grain boundaries has raised significant interest because of its role in irradiation assisted stress corrosion cracking (IASCC) and corrosion of structural materials. Numerous observations of RIS have been reported on austenitic stainless steels where it is generally found that Cr depletes at grain boundaries, consistently with Cr atoms being oversized in the fcc Fe matrix. While FM and ferritic steels are also subject to RIS at grain boundaries, unlike austenitic steels, the behavior of Cr is less clear with significant scatter and no clear dependency on irradiation condition or alloy type. In addition to the lack of conclusive experimental evidence regarding RIS in F-M alloys, there have been relatively few efforts at modeling RIS behavior in these alloys. The need for predictability of materials behavior and mitigation routes for IASCC requires elucidating the origin of the variable Cr behavior. A systematic detailed high-resolution structural and chemical characterization approach was applied to ion-implanted and neutron-irradiated model Fe-Cr alloys containing from 3 to 18 at.% Cr. Atom probe tomography analyses of the microstructures revealed slight Cr clustering and segregation to dislocations and

Materials technologies of light water reactors

International Nuclear Information System (INIS)

Begley, R.

1984-01-01

Satisfactory materials performance is a key element in achieving reliable operation of light water reactors. Outstanding performance under rigorous operational conditions has been exhibited by pressure boundary components, core internals, fuel cladding, and other critical components of these systems. Corrosion and stress corrosion phenomena have, however, had an impact on plant availability, most notably relating to pipe cracking in BWR systems and steam generator corrosion in PWR systems. These experiences have stimulated extensive development activities by the nuclear industry in improved NDE techniques, investigation of corrosion phenomena, as well as improved materials and repair processes. This paper reviews key materials performance aspects of light water reactors with particular emphasis on the progress which has been made in modeling of corrosion phenomena, control of the plant operating environment, advanced material development, and application of sophisticated repair procedures. Implementation of this technology provides the basis for improved plant availability

Altered Ecological Flows Blur Boundaries in Urbanizing Watersheds

Directory of Open Access Journals (Sweden)

Todd R. Lookingbill

2009-12-01

Full Text Available The relevance of the boundary concept to ecological processes has been recently questioned. Humans in the post-industrial era have created novel lateral transport fluxes that have not been sufficiently considered in watershed studies. We describe patterns of land-use change within the Potomac River basin and demonstrate how these changes have blurred traditional ecosystem boundaries by increasing the movement of people, materials, and energy into and within the basin. We argue that this expansion of ecological commerce requires new science, monitoring, and management strategies focused on large rivers and suggest that traditional geopolitical and economic boundaries for environmental decision making be appropriately revised. Effective mitigation of the consequences of blurred boundaries will benefit from a broad-scale, interdisciplinary framework that can track and explicitly account for ecological fluxes of water, energy, materials, and organisms across human-dominated landscapes.

On some boundary value problems in quantum statistical mechanics

International Nuclear Information System (INIS)

Angelescu, N.

1978-01-01

The following two topics of equilibrium quantum statistical mechanics are discussed in this thesis: (i) the independence of the thermodynamic limit of grand-canonical pressure on the boundary conditions; (ii) the magnetic properties of free quantum gases. Problem (i) is handled with a functional integration technique. Wiener-type conditional measures are constructed for a given domain and a general class of mixed conditions on its boundary, these measures are used to write down Feynman-Kac formulae for the kernels of exp(-βH), where H is the Hamiltonian of N interacting particles in the given domain. These measures share the property that they assign the same mass as the usual Wiener measure to any set of trajectories not intersecting the boundary. Local estimates on the kernels of exp(-βH) are derived, which imply independence of the pressure on the boundary conditions in the thermodynamic limit. Problem (ii) has a historical development: since Landau's work (1930), much discussion has been devoted to the influence of the finite size on the susceptibility. In finite volume, Dirichlet boundary conditions are imposed, on the ground that they ensure gauge invariance. The thermodynamic limit of the pressure is proved, using again functional integration. The functional measure is now complex but absolutely continuous with respect to Wiener measure, so the usual local estimates hold true. The controversy in the literature was concentrated on the commutativity of the operations of H-derivation and thermodynamic limit, so the existence of this limit for the zero-field susceptibility and its surface term are proved separately, demonstrating this commutativity. The proof relies on the following result of independent interest: the perturbation theory of self-adjoint trace-class semigroups is trace-class convergent and analytic. (author)

Effects of Sweep Angle on the Boundary-Layer Stability Characteristics of an Untapered Wing at Low Speeds

Science.gov (United States)

Boltz, Frederick W.; Kenyon, George C.; Allen, Clyde Q.

1960-01-01

An investigation was conducted in the Ames 12-Foot Low-Turbulence Pressure Tunnel to determine the effects of sweep on the boundary-layer stability characteristics of an untapered variable-sweep wing having an NACA 64(2)A015 section normal to the leading edge. Pressure distribution and transition were measured on the wing at low speeds at sweep angles of 0, 10, 20, 30, 40, and 50 deg. and at angles of attack from -3 to 3 deg. The investigation also included flow-visualization studies on the surface at sweep angles from 0 to 50 deg. and total pressure surveys in the boundary layer at a sweep angle of 30 deg. for angles of attack from -12 to 0 deg. It was found that sweep caused premature transition on the wing under certain conditions. This effect resulted from the formation of vortices in the boundary layer when a critical combination of sweep angle, pressure gradient, and stream Reynolds number was attained. A useful parameter in indicating the combined effect of these flow variables on vortex formation and on beginning transition is the crossflow Reynolds number. The critical values of crossflow Reynolds number for vortex formation found in this investigation range from about 135 to 190 and are in good agreement with those reported in previous investigations. The values of crossflow Reynolds number for beginning transitions were found to be between 190 and 260. For each condition (i.e., development of vortices and initiation of transition at a given location) the lower values in the specified ranges were obtained with a light coating of flow-visualization material on the surface. A method is presented for the rapid computation of crossflow Reynolds number on any swept surface for which the pressure distribution is known. From calculations based on this method, it was found that the maximum values of crossflow Reynolds number are attained under conditions of a strong pressure gradient and at a sweep angle of about 50 deg. Due to the primary dependence on pressure

Latex paint as a delivery vehicle for diethylphthalate and di-n-butylphthalate: predictable boundary layer concentrations and emission rates.

Science.gov (United States)

Schripp, Tobias; Salthammer, Tunga; Fauck, Christian; Bekö, Gabriel; Weschler, Charles J

2014-10-01

The description of emission processes of volatile and semi-volatile organic compounds (VOCs and SVOCs) from building products requires a detailed understanding of the material and the air flow conditions at the surface boundary. The mass flux between the surface of the material and air depends on the mass transfer coefficient (hm) through the boundary layer, the gas phase concentration of the target compound immediately adjacent to the material (y0), and the gas-phase concentration in bulk air (y(t)). In the present study emission experiments were performed in two chambers of quite different sizes (0.25 m(3) and 55 m(3)), and, in the larger chamber, at two different temperatures (23°C and 30°C). The emitting material was latex wall paint that had been doped with two plasticizers, diethylphthalate (DEP) and di-n-butylphthalate (DnBP). The phthalate content in the paint was varied in the small chamber experiment to evaluate the impact of the initial concentration in the bulk material (C0) on the emission rate. Boundary layer theory was applied to calculate hm for the specific phthalates from the Sherwood number (Sh) and the diffusion coefficient (Dair). Then y0 was determined based on the bulk gas-phase concentration at steady state (y¯). For both, DEP and DnBP, the y0 obtained was lower than the respective saturation vapor pressure (Ps). Furthermore, for both phthalates in latex paint, the material/air partition coefficient (C0/y0) was close in value to the octanol/air partition coefficient (KOA). This study provides a basis for designing phthalate emitting reference materials that mimic the emission behavior of common building materials. Copyright © 2014 Elsevier B.V. All rights reserved.

Discontinuous phase formation and selective attack of SiC materials exposed to low oxygen partial pressure environments

Energy Technology Data Exchange (ETDEWEB)

Butt, D.P. [Los Alamos National Lab., NM (United States); Tressler, R.E.; Spear, K.E. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering

1993-09-01

Three SiC materials were exposed to gas mixtures containing N{sub 2}, H{sub 2}, and CO at 1000-1300C, 1-740 torr for a few to 1000 h. Kinetic and thermodynamic studies indicate that CO is the predominant oxidizing species. A variety of corrosion processes were observed, including surface and internal pit formation, needle growth, grain boundary attack, and attack of impurities and surrounding material. In the case of a siliconized SiC, impurities such as Ca, Al, and Fe diffused rapidly through the Si matrix forming complex calcium aluminosilicates on the surface, leaving behind internal voids. Evaluation of the mechanical properties, including fractography, revealed a variety of degradative phenomena. Efforts to identify causes of pit formation suggested that the overall process was complex. Pits formed during attack of grain boundaries and regions containing transition metal impurities. Studies of single crystals showed preferential attack near impurities and crystalline defects, indicating that damaged crystals or certain crystal orientations in the polycrystalline materials are susceptible to attack. In addition, under some conditions where pit formation was observed, the strength of certain materials increased apparently due to flaw healing. It is suggested that flaws can heal in the absence of mechanical stress due to their high surface energy. However, second phases observed within partially healed surface cracks suggest impurities also contribute to the flaw healing processes.

Grain Boundary Engineering of Electrodeposited Thin Films

DEFF Research Database (Denmark)

Alimadadi, Hossein

is not yet well-understood. This, at least partly, owes to the lack of robust characterization methods for analyzing the nature of grain boundaries including the grain boundary plane characteristics, until recently. In the past decade, significant improvements in the 2-dimensional and 3-dimensional analysis...... of the favorable boundaries that break the network of general grain boundaries. Successful dedicated synthesis of a textured nickel film fulfilling the requirements of grain boundary engineered materials, suggests improved boundary specific properties. However, the textured nickel film shows fairly low...... thermal stability and growth twins annihilate by thermal treatment at 600 degree C. In contrast, for oriented grains, growth nano-twins which are enveloped within columnar grains show a high thermal stability even after thermal treatment at 600 degree C. In order to exploit the high thermal...

German boiler and pressure vessel codes and standards: materials, manufacture, testing, equipment, erection and operation

International Nuclear Information System (INIS)

Steffen, H.P.

1987-01-01

The methods by which the safety objectives on the operation of steam boilers and pressure vessels in Germany can be reached are set out in Technical Rules which are compiled and established in technical committees. Typical applications are described in the Technical Rules. A chart shows how the laws, provisions and Technical Rules for the sections 'steam boiler plant' and 'pressure vessels' are interlinked. This chapter concentrates on legal aspects, materials, manufacture, testing, erection and operation of boilers and pressure vessels in Germany. (U.K.)

Reynolds-Stress Budgets in an Impinging Shock Wave/Boundary-Layer Interaction

Science.gov (United States)

Vyas, Manan A.; Yoder, Dennis A.; Gaitonde, Datta V.

2018-01-01

Implicit large-eddy simulation (ILES) of a shock wave/boundary-layer interaction (SBLI) was performed. Comparisons with experimental data showed a sensitivity of the current prediction to the modeling of the sidewalls. This was found to be common among various computational studies in the literature where periodic boundary conditions were used in the spanwise direction, as was the case in the present work. Thus, although the experiment was quasi-two-dimensional, the present simulation was determined to be two-dimensional. Quantities present in the exact equation of the Reynolds-stress transport, i.e., production, molecular diffusion, turbulent transport, pressure diffusion, pressure strain, dissipation, and turbulent mass flux were calculated. Reynolds-stress budgets were compared with past large-eddy simulation and direct numerical simulation datasets in the undisturbed portion of the turbulent boundary layer to validate the current approach. The budgets in SBLI showed the growth in the production term for the primary normal stress and energy transfer mechanism was led by the pressure strain term in the secondary normal stresses. The pressure diffusion term, commonly assumed as negligible by turbulence model developers, was shown to be small but non-zero in the normal stress budgets, however it played a key role in the primary shear stress budget.

Heavy section steel technology program technical report No. 38. Fracture toughness characterization of HSST intermediate pressure vessel material

International Nuclear Information System (INIS)

Mager, T.R.; Yanichko, S.E.; Singer, L.R.

1974-12-01

The primary objective of the Heavy Section Steel Technology (HSST) Program is to develop pertinent fracture technology to demonstrate the structural reliability of present and contemplated water-cooled nuclear reactor pressure vessels. In order to demonstrate the ability to predict failure of large, heavy-walled pressure vessels under service type loading conditions, the fracture toughness properties of the vessel's materials must be characterized. The sampling procedure and test results are presented for vessel material supplied by the Oak Ridge National Laboratory that were used to characterize the fracture toughness of the HSST Intermediate Test Vessels. The metallurgical condition and heat treatment of the test material was representative of the vessel simulated service test condition. Test specimen locations and orientations were selected by the Oak Ridge National Laboratory and are representative of flaw orientations incorporated in the test vessels. The fracture toughness is documented for the materials from each of the eight HSST Intermediate Pressure Vessels tested to date. 7 references. (U.S.)

Description of internal flow problems by a boundary integral method with dipole panels

International Nuclear Information System (INIS)

Krieg, R.; Hailfinger, G.

1979-01-01

In reactor safety studies the failure of single components is postulated or sudden accident loadings are assumed and the consequences are investigated. Often as a first consequence highly transient three dimensional flow problems occur. In contrast to classical flow problems, in most of the above cases the fluid velocities are relatively small whereas the accelerations assume high values. As a consequence both, viscosity effects and dynamic pressures which are proportional to the square of the fluid velocities are usually negligible. For cases, where the excitation times are considerably longer than the times necessary for a wave to traverse characteristic regions of the fluid field, also the fluid compressibility is negligible. Under these conditions boundary integral methods are an appropriate tool to deal with the problem. Flow singularities are distributed over the fluid boundaries in such a way that pressure and velocity fields are obtained which satisfy the boundary conditions. In order to facilitate the numerical treatment the fluid boundaries are approximated by a finite number of panels with uniform singularity distributions on each of them. Consequently the pressure and velocity field of the given problem may be obtained by superposition of the corresponding fields due to these panels with their singularity intensities as unknown factors. Then satisfying the boundary conditions in so many boundary points as panels have been introduced, yields a system of linear equations which in general allows for a unique determination of the unknown intensities. (orig./RW)

Grain boundary structure and properties

International Nuclear Information System (INIS)

Balluffi, R.W.

1979-05-01

An attempt is made to distinguish those fundamental aspects of grain boundaries which should be relevant to the problem of the time dependent fracture of high temperature structural materials. These include the basic phenomena which are thought to be associated with cavitation and cracking at grain boundaries during service and with the more general microstructural changes which occur during both processing and service. A very brief discussion of the current state of knowledge of these fundamentals is given

Competing Grain Boundary and Interior Deformation Mechanisms with Varying Sizes

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wei [University of Tennessee (UT); Gao, Yanfei [ORNL; Nieh, T. G. [University of Tennessee, Knoxville (UTK)

2018-01-01

In typical coarse-grained alloys, the dominant plastic deformations are dislocation gliding or climbing, and material strengths can be tuned by dislocation interactions with grain boundaries, precipitates, solid solutions, and other defects. With the reduction of grain size, the increase of material strengths follows the classic Hall-Petch relationship up to nano-grained materials. Even at room temperatures, nano-grained materials exhibit strength softening, or called the inverse Hall-Petch effect, as grain boundary processes take over as the dominant deformation mechanisms. On the other hand, at elevated temperatures, grain boundary processes compete with grain interior deformation mechanisms over a wide range of the applied stress and grain sizes. This book chapter reviews and compares the rate equation model and the microstructure-based finite element simulations. The latter explicitly accounts for the grain boundary sliding, grain boundary diffusion and migration, as well as the grain interior dislocation creep. Therefore the explicit finite element method has clear advantages in problems where microstructural heterogeneities play a critical role, such as in the gradient microstructure in shot peening or weldment. Furthermore, combined with the Hall-Petch effect and its breakdown, the above competing processes help construct deformation mechanism maps by extending from the classic Frost-Ashby type to the ones with the dependence of grain size.

Grain-boundary unzipping by oxidation in polycrystalline graphene

Science.gov (United States)

Alexandre, Simone; Lucio, Aline; Nunes, Ricardo

2011-03-01

The need for large-scale production of graphene will inevitably lead to synthesis of the polycrystalline material [1,2]. Understanding the chemical, mechanical, and electronic properties of grain boundaries in graphene polycrystals will be crucial for the development of graphene-based electronics. Oxidation of this material has been suggested to lead to graphene ribbons, by the oxygen-driven unzipping mechanism. A cooperative-strain mechanism, based on the formation of epoxy groups along lines of parallel bonds in the hexagons of graphene's honeycomb lattice, was proposed to explain the unzipping effect in bulk graphene In this work we employ ab initio calculations to study the oxidation of polycrystalline graphene by chemisorption of oxygen at the grain boundaries. Our results indicate that oxygen tends to segregate at the boundaries, and that the unzipping mechanism is also operative along the grain boundaries, despite the lack of the parallel bonds due to the presence of fivefold and sevenfold carbon rings along the boundary core. We acknowledge support from the Brazilian agencies: CNPq, Fapemig, and INCT-Materiais de Carbono.

Structural integrity evaluation of PWR nuclear reactor pressure vessels

International Nuclear Information System (INIS)

Cruz, Julio R.B.; Mattar Neto, Miguel

1999-01-01

The reactor pressure vessel (RPV) is the most important structural component of a PWR nuclear power plant. It contains the reactor core and is the main component of the primary system pressure boundary, the system responsible for removing the heat generated by the nuclear reactions. It is considered not replaceable and, therefore, its lifetime is a key element to define the plant life as a whole. Three critical issues related to the reliability of the RPV structural integrity come out by reason of the radiation damage imposed to the vessel material during operation. These issues concern the definition of pressure versus temperature limits for reactor heatup and cooldown, pressurized thermal shock evaluation and assessment of reactor vessels with low upper shelf Charpy impact energy levels. This work aims to present the major aspects related to these topics. The requirements for preventing fracture of the RPV are reviewed as well as the available technology for assessing the safety margins. For each mentioned problem, the several steps for structural integrity evaluation are described and the analysis methods are discussed. (author)

The installation welding of pressure water reactor coolant piping

International Nuclear Information System (INIS)

Deng Feng

2010-01-01

Large pressure water reactor nuclear power plants are constructing in our country. There are three symmetry standard loops in reactor coolant system. Each loop possesses a steam generator and a primary poop, in which one of the loops is equipped with a pressurizer. These components are connected with reactor pressure vessel by installation welding of the coolant piping. The integrity of reactor coolant pressure boundary is the second barrier to protect the radioactive substance from release to outside, so the safe operation of nuclear power plant is closely related to the quality of coolant piping installation welding. The heavy tube with super low carbon content austenitic stainless steel is selected for coolant piping. This kind of material has good welding behavior, but the poor thermal conductivity, the big liner expansion coefficient and the big welding deformation will cause bigger welding stress. To reduce the welding deformation, to control the dimension precision, to reduce the residual stress and to ensure the welding quality the installation sequence should be properly designed and the welding technology should be properly controlled. (authors)

On the estimation of wall pressure coherence using time-resolved tomographic PIV

Science.gov (United States)

Pröbsting, Stefan; Scarano, Fulvio; Bernardini, Matteo; Pirozzoli, Sergio

2013-07-01

Three-dimensional time-resolved velocity field measurements are obtained using a high-speed tomographic Particle Image Velocimetry (PIV) system on a fully developed flat plate turbulent boundary layer for the estimation of wall pressure fluctuations. The work focuses on the applicability of tomographic PIV to compute the coherence of pressure fluctuations, with attention to the estimation of the stream and spanwise coherence length. The latter is required for estimations of aeroacoustic noise radiation by boundary layers and trailing edge flows, but is also of interest for vibro-structural problems. The pressure field is obtained by solving the Poisson equation for incompressible flows, where the source terms are provided by time-resolved velocity field measurements. Measured 3D velocity data is compared to results obtained from planar PIV, and a Direct Numerical Simulation (DNS) at similar Reynolds number. An improved method for the estimation of the material based on a least squares estimator of the velocity derivative along a particle trajectory is proposed and applied. Computed surface pressure fluctuations are further verified by means of simultaneous measurements by a pinhole microphone and compared to the DNS results and a semi-empirical model available from literature. The correlation coefficient for the reconstructed pressure time series with respect to pinhole microphone measurements attains approximately 0.5 for the band-pass filtered signal over the range of frequencies resolved by the velocity field measurements. Scaled power spectra of the pressure at a single point compare favorably to the DNS results and those available from literature. Finally, the coherence of surface pressure fluctuations and the resulting span- and streamwise coherence lengths are estimated and compared to semi-empirical models and DNS results.

Destruction of organic materials by pressurized microwave digestion

Energy Technology Data Exchange (ETDEWEB)

Schramel, P. (GSF - Research Center for Environment and Health, Inst. of Ecological Chemistry, Neuherberg (Germany)); Hasse, S. (GSF - Research Center for Environment and Health, Inst. of Ecological Chemistry, Neuherberg (Germany))

This paper describes the utility of pressurized microwave digestion (up to 85 bar) for a broad spectrum of organic materials (blood, urine, milk powder, tissues). The 'quality' of the sample solution was tested by the determination of Pb, Cd and Cu (additionally Ni and Co in some of the matrices) by anodic stripping voltammetry (DPASV) and Hydride Generation AAS (HAAS) for As. It is clearly shown that no universal 'cooking recipe' can be given. The necessary oxidation potential is very dependent on the type of organic matrix and therefore the use of acid combinations (HNO[sub 3]/HClO[sub 4]/H[sub 2]SO[sub 4]) is generally necessary to obtain adequate solution of the sample. In some cases the power of the microwave oven was not high enough to digest two samples simultaneoulsy. (Significant differences in the ease of solution are shown in the digestion of one or two samples). Some important improvements for sample preparation, such as moistening the powdered material with water and mixing well with the acid used before closing the digestion vessel etc., are also given. (orig.)

The effect of ambient pressure on the evaporation rate of materials

Science.gov (United States)

Naumann, R. J.; Russell, W. M.

1972-01-01

A simple expression is obtained using a diffusion model for the effect of ambient pressure on the outgassing or evaporation rate of materials. The correctness of the expression is demonstrated by comparing the estimates from this expression with actual weight loss measurements. It is shown that the rate of mass loss is governed by the ratio of mean free path to the characteristic dimension of the surface in question.

Effects of Cross-Linking on the Hydrostatic Pressure Testing for HDPE Pipe Material using Electron Beam Machine

International Nuclear Information System (INIS)

Mohd Jamil Bin Hashim

2011-01-01

One of the most inventive, sustainable strategies used in engineering field is to improve the quality of material and minimize production cost of material for example in this paper is HDPE material. This is because HDPE is an oil base material. This paper proposes to improve its hydrostatic pressure performance for HDPE pipe. The burst test is the most direct measurement of a pipe materials resistance to hydrostatic pressure. Test will be conducted in accordance with ASTM standard for HDPE pipe that undergo electron beam irradiation cross-linking. Studies show the effect of electron beam irradiation will improve the mechanical properties of HDPE pipe. When cross-linking is induced, the mechanical properties such as tensile strength and young modulus is increase correspond to the radiation dose. This happen because the structure of HDPE, which is thermoplastic change to thermosetting. This will indicate the variability of irradiation dose which regard to the pipe pressure rating. Hence, the thickness ratio of pipe will be re-examining in order to make the production of HDPE pipe become more economical. This research review the effects of electron beam on HDPE pipe, as well as to reduce the cost of its production to improve key properties of selected plastic pipe products. (author)

Research on new materials development and elucidation of degradation phenomena in nuclear environments

International Nuclear Information System (INIS)

Terai, Takayuki

2003-01-01

Advanced materials technologies are required to develop the pressure boundary materials used in nuclear corrosive environments under irradiation. The outline of the materials research for overcoming the requirements is described. The applicability and fusibility of new materials technology and major characteristics are shown with respect to several examples. A new-type coating method of diamond-like carbide films by using RF magnetron sputtering, mechanistic analysis on tritium release behavior from molten lithium-tin alloy in-reactor, neutron irradiation assisted change in pinning properties of Bi 2 Sr 2 CaCu 2 O 8+x single crystals are discussed as typical outputs concerning the research. (author)

Apparatus and method for fatigue testing of a material specimen in a high-pressure fluid environment

Science.gov (United States)

Wang, Jy-An; Feng, Zhili; Anovitz, Lawrence M; Liu, Kenneth C

2013-06-04

The invention provides fatigue testing of a material specimen while the specimen is disposed in a high pressure fluid environment. A specimen is placed between receivers in an end cap of a vessel and a piston that is moveable within the vessel. Pressurized fluid is provided to compression and tension chambers defined between the piston and the vessel. When the pressure in the compression chamber is greater than the pressure in the tension chamber, the specimen is subjected to a compression force. When the pressure in the tension chamber is greater than the pressure in the compression chamber, the specimen is subjected to a tension force. While the specimen is subjected to either force, it is also surrounded by the pressurized fluid in the tension chamber. In some examples, the specimen is surrounded by hydrogen.

Method of treating organic material. [addition of formate, heating under pressure, and distilling the mass

Energy Technology Data Exchange (ETDEWEB)

Bergstrom, H O.V.; Cederquist, K N

1932-02-08

A method is given of treating organic material such as wood, peat, shale, etc. It is characterized by the addition of formate to the material, before, during, or after heating it under pressure with alkalis, earth alkalis, et cetera, and by the mass thus produced undergoing dry distillation. The patent has three more claims.

Large deformation analysis of adhesive by Eulerian method with new material model

International Nuclear Information System (INIS)

Maeda, K; Nishiguchi, K; Iwamoto, T; Okazawa, S

2010-01-01

The material model to describe large deformation of a pressure sensitive adhesive (PSA) is presented. A relationship between stress and strain of PSA includes viscoelasticity and rubber-elasticity. Therefore, we propose the material model for describing viscoelasticity and rubber-elasticity, and extend the presented material model to the rate form for three dimensional finite element analysis. After proposing the material model for PSA, we formulate the Eulerian method to simulate large deformation behavior. In the Eulerian calculation, the Piecewise Linear Interface Calculation (PLIC) method for capturing material surface is employed. By using PLIC method, we can impose dynamic and kinematic boundary conditions on captured material surface. The representative two computational examples are calculated to check validity of the present methods.

Fracture-mechanics data deduced from thermal-shock and related experiments with LWR pressure-vessel material

International Nuclear Information System (INIS)

Cheverton, R.D.; Canonico, D.A.; Iskander, S.K.; Bolt, S.E.; Holz, P.P.; Nanstad, R.K.; Stelzman, W.J.

1982-01-01

Pressurized water reactors (PWRs) are susceptible to certain types of hypothetical accidents that can subject the reactor pressure vessel to severe thermal shock, that is, a rapid cooling of the inner surface of the vessel wall. The thermal-shock loading, coupled with the radiation-induced reduction in the material fracture toughness, introduces the possibility of propagation of preexistent flaws and what at one time were regarded as somewhat unique fracture-oriented conditions. Several postulated reactor accidents have been analyzed to discover flaw behavior trends; seven intermediate-scale thermal-shock experiments with steel cylinders have been conducted; and corresponding materials characterization studies have been performed. Flaw behavior trends and related fracture-mechanics data deduced from these studies are discussed

Boundary layer on a flat plate with suction

International Nuclear Information System (INIS)

Favre, A.; Dumas, R.; Verollet, E.

1961-01-01

This research done in wind tunnel concerns the turbulent boundary layer of a porous flat plate with suction. The porous wall is 1 m long and begins 1 m downstream of the leading edge. The Reynolds number based on the boundary layer thickness is of the order of 16.300. The suction rate defined as the ratio of the velocity perpendicular to the wall to the external flow velocity ranges from 0 to 2 per cent. The pressure gradient can be controlled. The mean velocity profiles have been determined for various positions and suction rates by means of total pressure probes together with the intensities of the turbulent velocity fluctuations components, energy spectra and correlations by means of hot wire anemometers, spectral analyser and correlator. The stream lines, the values of the viscous and turbulent shear stresses, of the local wall friction, of the turbulent energy production term, with some information on the dissipation of the energy have been derived from these measurements. For these data the integral of equation of continuity in boundary layer have been drawn. The suction effects on the boundary layer are important. The suction thoroughly alters the mean velocity profiles by increasing the viscous shear stresses near the wall and decreasing them far from the wall, it diminishes the longitudinal and transversal turbulence intensities, the turbulent shear stresses, and the production of energy of turbulence. These effects are much stressed in the inner part of the boundary layer. On the other hand the energy spectra show that the turbulence scale is little modified, the boundary layer thickness being not much diminished by the suction. The suction effects can be appreciated by comparing twice the suction rate to the wall friction coefficient (assumed airtight), quite noticeable as soon as the rate is about unity, they become very important when it reaches ten. (author) [fr

The curved kinetic boundary layer of active matter.

Science.gov (United States)

Yan, Wen; Brady, John F

2018-01-03

A body submerged in active matter feels the swim pressure through a kinetic accumulation boundary layer on its surface. The boundary layer results from a balance between translational diffusion and advective swimming and occurs on the microscopic length scale . Here , D T is the Brownian translational diffusivity, τ R is the reorientation time and l = U 0 τ R is the swimmer's run length, with U 0 the swim speed [Yan and Brady, J. Fluid. Mech., 2015, 785, R1]. In this work we analyze the swim pressure on arbitrary shaped bodies by including the effect of local shape curvature in the kinetic boundary layer. When δ ≪ L and l ≪ L, where L is the body size, the leading order effects of curvature on the swim pressure are found analytically to scale as J S λδ 2 /L, where J S is twice the (non-dimensional) mean curvature. Particle-tracking simulations and direct solutions to the Smoluchowski equation governing the probability distribution of the active particles show that λδ 2 /L is a universal scaling parameter not limited to the regime δ, l ≪ L. The net force exerted on the body by the swimmers is found to scale as F net /(n ∞ k s T s L 2 ) = f(λδ 2 /L), where f(x) is a dimensionless function that is quadratic when x ≪ 1 and linear when x ∼ 1. Here, k s T s = ζU 0 2 τ R /6 defines the 'activity' of the swimmers, with ζ the drag coefficient, and n ∞ is the uniform number density of swimmers far from the body. We discuss the connection of this boundary layer to continuum mechanical descriptions of active matter and briefly present how to include hydrodynamics into this purely kinetic study.

Magnetohydrodynamic boundary layer on a wedge

International Nuclear Information System (INIS)

Rao, B.N.; Mittal, M.L.

1981-01-01

The effects of the Hall and ionslip currents on the gas-dynamic boundary layer are investigated in view of the increasing prospects for using the MHD principle in electric power generation. The currents are included in the analysis using the generalized Ohm's law (Sherman and Sutton, 1964), and the resulting two nonlinear coupled equations are solved using a modification in the method suggested by Nachtsheim and Swigert (1965), Dewey and Gross (1967), and Steinheuer (1968). Solutions are presented for the incompressible laminar boundary-layer equations in the absence and the presence of the load parameter, and for the pressure gradient parameter for flow separation

Cross-sectional measurement of grain boundary segregation using WDS

Energy Technology Data Exchange (ETDEWEB)

Christien, F., E-mail: frederic.christien@emse.fr [Laboratoire Georges Friedel, CNRS, Ecole des Mines de Saint-Etienne, 158 Cours Fauriel, 42023 Saint-Etienne (France); Risch, P. [Institut des Matériaux Jean Rouxel (IMN), CNRS, Université de Nantes, Rue Christian Pauc, 44306 Nantes (France)

2016-11-15

A new method is proposed for the quantification of grain boundary segregation using Wavelength Dispersive Spectroscopy (WDS) in a Scanning Electron Microscope (SEM). Analyses are undertaken on a simple metallographically polished section of material. The method is demonstrated for the model system of sulphur segregation to nickel grain boundaries. Quantification was carried out from sulphur concentration profiles acquired across 11 grain boundaries of a nickel specimen containing 5.4 wt ppm of sulphur in the bulk and equilibrated at 550 °C. The average sulphur grain boundary concentration determined is µ=35.2 ng cm{sup −2}=6.6×10{sup 14} atoms cm{sup −2}≈0.5 monolayer, which is in good agreement with a previous quantification obtained from SIMS (Secondary Ion Mass Spectrometry) on the same material. However this is lower by a factor of two than the quantification obtained using “surface” techniques on fractured specimens of the same material. With the conditions of analysis used in this study, the limit of detection of the method developed is found to be better than 10% of a sulphur monolayer. - Highlights: • Impurity grain boundary segregation can be measured using WDS in a SEM. • The method proposed is quantitative. • The specimen preparation is simple: metallographical section.

Deformation behavior of irradiated Zr-2.5Nb pressure tube material

International Nuclear Information System (INIS)

Himbeault, D.D.; Chow, C.K.; Puls, M.P.

1994-01-01

A study of the deformation behavior of irradiated highly textured Zr-2.5Nb pressure tube material in the temperature range of 30 degree C to 300 degree C was undertaken to understand better the mechanism for the deterioration of the fracture toughness with neutron irradiation. Strain localization behavior, believed to be a main contributor to reduced toughness, was observed in irradiated transverse tensile specimens at temperature greater than 100 degree C. The strain localization behavior was found to occur by the cooperative twinning of the highly textured grains of the material, resulting in a local softening of the material, where the flow than localizes. It is believed that the effect of the irradiation is to favor twinning at the expense of slip in the early stages of deformation. This effect becomes more pronounced at higher temperature, thus leading to the high-temperature strain localization behavior of the material. A limited amount of dislocation channeling was also observed; however, it is not considered to have a major role in the strain localization behavior of the material. Contrary to previous reports on irradiated zirconium alloys, static strain aging is observed in the irradiated material in the temperature range of 150 degree C to 300 degree C

Materials for pressure equipment under the new approach directives: a one-year home-experience

International Nuclear Information System (INIS)

Zdankiewicz, M.

2005-01-01

The New Approach Directives concerning pressure equipment set forth basic safety requirements for their designing, manufacturing and testing. The said requirements are being implemented in the field of materials in Poland after one-year experience. (author)

Embrittlement of the nuclear icebreaker Lenin reactor pressure vessel materials reconstruction

International Nuclear Information System (INIS)

Krasikov, E.A.; Nikolaenko, V.A.

2008-01-01

Paper deals with the results of the efforts to examine the radiation damage of the Lenin nuclear-powered ice-breaker decommissioned reactor pressure vessel on the basis of which one has determined the peculiar features of the metal radiation embrittlement. Under 10 10 -10 11 s -1 cm -2 low density neutron flux irradiation one notes the most intensive embrittlement of the metal. Then, as the noxious element content in the metal matrix grows smaller the embrittlement reduces up to the change of sign as to the normal curve plotted at the neutron flux density exceeding 10 13 s -1 cm -2 . One assumes that as a result of the low density neutron flux irradiation the reactor pressure vessel edge spaces at some operation stages may be damaged more severely in contrast to these near the reactor core. The neutron irradiation density is the factor affecting the reactor vessel material embrittlement, that is why, it is important to study the damage mechanism of the materials of the power reactor vessels under design characterized by the low radiation load. The mentioned is important, as well, to evaluate the efficiency of the efforts undertaken to mitigate the effect of the neutron radiation on the reactor vessel [ru

Generalized wall function and its application to compressible turbulent boundary layer over a flat plate

Science.gov (United States)

Liu, J.; Wu, S. P.

2017-04-01

Wall function boundary conditions including the effects of compressibility and heat transfer are improved for compressible turbulent boundary flows. Generalized wall function formulation at zero-pressure gradient is proposed based on coupled velocity and temperature profiles in the entire near-wall region. The parameters in the generalized wall function are well revised. The proposed boundary conditions are integrated into Navier-Stokes computational fluid dynamics code that includes the shear stress transport turbulence model. Numerical results are presented for a compressible boundary layer over a flat plate at zero-pressure gradient. Compared with experimental data, the computational results show that the generalized wall function reduces the first grid spacing in the directed normal to the wall and proves the feasibility and effectivity of the generalized wall function method.

Feasibility of developing risk-based rankings of pressure boundary systems for inservice inspection

Energy Technology Data Exchange (ETDEWEB)

Vo, T.V.; Smith, B.W.; Simonen, F.A.; Gore, B.F.

1994-08-01

The goals of the Evaluation and Improvement of Non-destructive Examination Reliability for the In-service Inspection of Light Water Reactors Program sponsored by the Nuclear Regulatory Commission at Pacific Northwest Laboratory (PNL) are to (1) assess current ISI techniques and requirements for all pressure boundary systems and components, (2) determine if improvements to the requirements are needed, and (3) if necessary, develop recommendations for revising the applicable ASME Codes and regulatory requirements. In evaluating approaches that could be used to provide a technical basis for improved inservice inspection plans, PNL has developed and applied a method that uses results of probabilistic risk assessment (PRA) to establish piping system ISI requirements. In the PNL program, the feasibility of generic ISI requirements is being addressed in two phases. Phase I involves identifying and prioritizing the systems most relevant to plant safety. The results of these evaluations will be later consolidated into requirements for comprehensive inservice inspection of nuclear power plant components that will be developed in Phase II. This report presents Phase I evaluations for eight selected plants and attempts to compare these PRA-based inspection priorities with current ASME Section XI requirements for Class 1, 2 and 3 systems. These results show that there are generic insights that can be extrapolated from the selected plants to specific classes of light water reactors.

Feasibility of developing risk-based rankings of pressure boundary systems for inservice inspection

International Nuclear Information System (INIS)

Vo, T.V.; Smith, B.W.; Simonen, F.A.; Gore, B.F.

1994-08-01

The goals of the Evaluation and Improvement of Non-destructive Examination Reliability for the In-service Inspection of Light Water Reactors Program sponsored by the Nuclear Regulatory Commission at Pacific Northwest Laboratory (PNL) are to (1) assess current ISI techniques and requirements for all pressure boundary systems and components, (2) determine if improvements to the requirements are needed, and (3) if necessary, develop recommendations for revising the applicable ASME Codes and regulatory requirements. In evaluating approaches that could be used to provide a technical basis for improved inservice inspection plans, PNL has developed and applied a method that uses results of probabilistic risk assessment (PRA) to establish piping system ISI requirements. In the PNL program, the feasibility of generic ISI requirements is being addressed in two phases. Phase I involves identifying and prioritizing the systems most relevant to plant safety. The results of these evaluations will be later consolidated into requirements for comprehensive inservice inspection of nuclear power plant components that will be developed in Phase II. This report presents Phase I evaluations for eight selected plants and attempts to compare these PRA-based inspection priorities with current ASME Section XI requirements for Class 1, 2 and 3 systems. These results show that there are generic insights that can be extrapolated from the selected plants to specific classes of light water reactors

Flutter Sensitivity to Boundary Layer Thickness, Structural Damping, and Static Pressure Differential for a Shuttle Tile Overlay Repair Concept

Science.gov (United States)

Scott, Robert C.; Bartels, Robert E.

2009-01-01

This paper examines the aeroelastic stability of an on-orbit installable Space Shuttle patch panel. CFD flutter solutions were obtained for thick and thin boundary layers at a free stream Mach number of 2.0 and several Mach numbers near sonic speed. The effect of structural damping on these flutter solutions was also examined, and the effect of structural nonlinearities associated with in-plane forces in the panel was considered on the worst case linear flutter solution. The results of the study indicated that adequate flutter margins exist for the panel at the Mach numbers examined. The addition of structural damping improved flutter margins as did the inclusion of nonlinear effects associated with a static pressure difference across the panel.

Field measurements of bottom boundary layer and suspend particle materials on Jyoban coast in Japan

International Nuclear Information System (INIS)

Yagi, Hiroshi; Sugimatsu, Kouichi; Nishi, Yoshihiro; Kawamata, Shigeru; Nakayama, Akiyoshi; Udagawa, Toru; Suzuki, Akira

2013-01-01

To understand the characteristics of the bottom boundary layer (BBL), movements of suspended particle material (SPM) and its related radionuclide transport on Jyoban coast, the continuous monitoring of bottom environments using the mooring system and the intensive field survey of BBL with FRA-TRIPOD were performed. The observation results have shown the fundamental characteristics of BBL (vertical distributions of velocities and bottom roughness, etc.) and bottom turbidity variations. The turbidity at the shallow water depth (30 m) was strongly influenced by waves and turbid water generated on rough wave conditions was transported by the coastal currents with the several days period. Turbidities at the deeper depths (80 m and 130 m) were affected by semidiurnal internal tides. (author)

Twin boundary cavitation in aged type 304 stainless steel

International Nuclear Information System (INIS)

Sikka, V.K.; Swindeman, R.W.; Brinkman, C.R.

1975-10-01

A transition from grain to twin boundary cavitation was observed in aged-and-creep-tested type 304 stainless steel. Evidence of twin boundary cavitation has also been observed for unaged material under certain test conditions. This same behavior was also found in aged type 316 stainless steel. Several possible reasons have been suggested for the absence of frequently observed grain boundary cavitation

On Perturbation Solutions for Axisymmetric Bending Boundary Values of a Deep Thin Spherical Shell

Directory of Open Access Journals (Sweden)

Rong Xiao

2014-01-01

Full Text Available On the basis of the general theory of elastic thin shells and the Kirchhoff-Love hypothesis, a fundamental equation for a thin shell under the moment theory is established. In this study, the author derives Reissner’s equation with a transverse shear force Q1 and the displacement component w. These basic unknown quantities are derived considering the axisymmetry of the deep, thin spherical shell and manage to constitute a boundary value question of axisymmetric bending of the deep thin spherical shell under boundary conditions. The asymptotic solution is obtained by the composite expansion method. At the end of this paper, to prove the correctness and accuracy of the derivation, an example is given to compare the numerical solution by ANSYS and the perturbation solution. Meanwhile, the effects of material and geometric parameters on the nonlinear response of axisymmetric deep thin spherical shell under uniform external pressure are also analyzed in this paper.

Waste Material Based "Terrazzo" Tiles: The Effect Of Curing Time And Extreme Environmental Conditions Over Glass Aggregate/Cement Matrix Boundary

Science.gov (United States)

Paris, E.; Radica, F.; Stabile, P.; Ansaloni, F.; Giuli, G.; Carroll, M. R.

2017-12-01

Currently, more than half of all materials extracted globally (over three billion tonnes/year in the EU only) are transformed for use in construction. Before year 2020, the EU aims to reduce the environmental impact of the construction sector by recycling or re-using large amounts of these materials, thus reducing the consumption of raw materials and helping promote the sector's economic stability. With this challenge in mind an aesthetically pleasant and fully recycled (up to 78%) pre-cast cement based tile (Terrazzo tiles) was designed by replacing raw materials with Glass Waste (GW) and Construction/Demolition Waste (CDW). Several recent studies explored the effect of the addition of GW in the manufacture of urban pavements, concluding that the use of GW can improve various phases of pavement life and structure by enhancing the structural performance, durability, environmental friendliness, and aesthetic features. In this study we extend this knowledge also to interior cement-based tiles by evaluating the technical performances of this this novel designed tile, in particular by focusing on the interface between the GW aggregates and different Portland cement based matrix at extreme environmental conditions. For this work three representative waste material based "terrazzo" tiles were selected and characterized by means of XRD and SEM imaging in order to study the boundary effect between GW aggregate and different binding materials: limestone powder, quartz powder and fine ground WG powder. A fourth additional mixture of Portland cement and CDW material was characterized. Fragments of a Limestone matrix tile were also thermally threated at -18°C and at 60°C for one week to witness the possible formation of new harmful phases at the grain-matrix boundary. Preliminary results on X-ray diffraction patterns show that 1 year after manufacture and/or thermal treatment there is no new formation of harmful phases other than the starting ones. High magnification SEM

Material Usage in High Pressure Oxygen Systems for the International Space Station

Science.gov (United States)

Kravchenko, Michael; Sievers, D. Elliott

2014-01-01

The Nitrogen/Oxygen Recharge System (NORS) for the International Space Station (ISS) Program was required as part of the Space Shuttle retirement efforts to sustain the ISS life support systems. The system is designed around a 7000 psia Oxygen or Nitrogen Recharge Tank Assembly which is able to be utilized both internally and externally to the ISS. Material selection and usage were critical to ensure oxygen compatibility for the design, while taking into consideration toxicity, weldability, brazability and general fabrication and assembly techniques. The system uses unique hardware items such a composite overwrap pressure vessel (COPV), high pressure mechanical gauges, compact regulators and valves, quick disconnects, metal tubing and flexhoses. Numerous challenges and anomalies were encountered due to the exotic nature of this project which will be discussed in detail. The knowledge gained from these anomalies and failure resolutions can be applied to more than space applications, but can also be applicable to industry pressurized systems.

Thermodynamic investigation of the phase equilibrium boundary between TiO2 rutile and its α-PbO2-type high-pressure polymorph

Science.gov (United States)

Kojitani, Hiroshi; Yamazaki, Monami; Kojima, Meiko; Inaguma, Yoshiyuki; Mori, Daisuke; Akaogi, Masaki

2018-06-01

Heat capacity (C P) of rutile and α-PbO2 type TiO2 (TiO2-II) were measured by the differential scanning calorimetry and thermal relaxation method. Using the results, standard entropies at 1 atm and 298.15 K of rutile and TiO2-II were determined to be 50.04(4) and 46.54(2) J/mol K, respectively. Furthermore, thermal expansivity (α) determined by high-temperature X-ray diffraction measurement and mode Grüneisen parameters obtained by high-pressure Raman spectroscopy suggested the thermal Grüneisen parameter (γ th) for TiO2-II of 1.7(1). By applying the obtained low-temperature C P and γ th, the measured C P and α data of TiO2-II were extrapolated to higher temperature region using a lattice vibrational model calculation, as well as rutile. Internally consistent thermodynamic data sets of both rutile and TiO2-II assessed in this study were used to thermodynamically calculate the rutile‒TiO2-II phase equilibrium boundary. The most plausible boundary was obtained to be P (GPa) = 0.0074T (K) - 1.7. Our boundary suggests that the crystal growth of TiO2-II observed below 5.5 GPa and 900 K in previous studies advanced in its stability field. The phase boundary calculation also suggested small, exothermic phase transition enthalpy from rutile to TiO2-II at 1 atm and 298.15 K of - 0.5 to - 1.1 kJ/mol. This implies that the thermodynamic stability of rutile at 1 atm above room temperature is due to larger contribution of entropy term.

Pressure-driven brine migration in a salt repository

International Nuclear Information System (INIS)

Hwang, Y.; Chambre, P.L.; Pigford, T.H.; Lee, W.W.L.

1989-01-01

The traditional view is that salt is the ideal rock for isolation of nuclear waste because it is ''dry'' and probably ''impermeable.'' The existence of salt through geologic time is prima facie evidence of such properties. Experiments and experience at potential salt sites for geologic repositories have indicated that while porosity and permeability of salt are low, the salt may be saturated with brine. If this hypothesis is correct, then it is possible to have brine flow due to pressure differences within the salt. If there is pressure-driven brine migration in salt repositories then it is paramount to know the magnitude of such flow because inward brine flow would affect the corrosion rate of nuclear waste containers and outward brine flow might affect radionuclide transport rates. Brine exists in natural salt as inclusions in salt crystals and in grain boundaries. Brine inclusions in crystals move to nearby grain boundaries when subjected to a temperature gradient, because of temperature-dependent solubility of salt. Brine in grain boundaries moves under the influence of a pressure gradient. When salt is mined to create a waste repository, brine from grain boundaries will migrate into the rooms, tunnels and boreholes because these cavities are at atmospheric pressure. After a heat-emitting waste package is emplaced and backfilled, the heat will impose a temperature gradient in the surrounding salt that will cause inclusions in the nearby salt to migrate to grain boundaries within a few years, adding to the brine that was already present in the grain boundaries. The formulation of brine movement with salt as a thermoelastic porous medium, in the context of the continuum theory of mixtures, has been described. In this report we show the mathematical details and discuss the results predicted by this analysis

Active control of flow noise sources in turbulent boundary layer on a flat-plate using piezoelectric bimorph film

International Nuclear Information System (INIS)

Song, Woo Seog; Lee, Seung Bae; Shin, Dong Shin; Na, Yang

2006-01-01

The piezoelectric bimorph film, which, as an actuator, can generate more effective displacement than the usual PVDF film, is used to control the turbulent boundary-layer flow. The change of wall pressures inside the turbulent boundary layer is observed by using the multi-channel microphone array flush-mounted on the surface when actuation at the non-dimensional frequency f b + =0.008 and 0.028 is applied to the turbulent boundary layer. The wall pressure characteristics by the actuation to produce local displacement are more dominantly influenced by the size of the actuator module than the actuation frequency. The movement of large-scale turbulent structures to the upper layer is found to be the main mechanism of the reduction in the wall-pressure energy spectrum when the 700ν/u τ -long bimorph film is periodically actuated at the non-dimensional frequency f b + =0.008 and 0.028. The bimorph actuator is triggered with the time delay for the active forcing at a single frequency when a 1/8' pressure-type, pin-holed microphone sensor detects the large-amplitude pressure event by the turbulent spot. The wall-pressure energy in the late-transitional boundary layer is partially reduced near the convection wavenumber by the open-loop control based on the large amplitude event

Application of micromechanical models of ductile fracture initiation to reactor pressure vessel materials

International Nuclear Information System (INIS)

Chaouadi, R.; Walle, E. van; Fabry, A.; Velde, J. van de; Meester, P. de

1996-01-01

The aim of the current study is the application of local micromechanical models to predict crack initiation in ductile materials. Two reactor pressure vessel materials have been selected for this study: JRQ IAEA monitor base metal (A533B Cl.1) and Doel-IV weld material. Charpy impact tests have been performed in both un-irradiated and irradiated conditions. In addition to standard tensile tests, notched tensile specimens have been tested. The upper shelf energy of the weld material remains almost un-affected by irradiation, whereas a decrease of 20% is detected for the base metal. Accordingly, the tensile properties of the weld material do not reveal a clear irradiation effect on the yield and ultimate stresses, this in contrast to the base material flow properties. The tensile tests have been analyzed in terms of micromechanical models. A good correlation is found between the standard tests and the micromechanical models, that are able to predict the ductile damage evolution in these materials. Additional information on the ductility behavior of these materials is revealed by this micromechanical analysis

Has land use pushed terrestrial biodiversity beyond the planetary boundary? A global assessment.

Science.gov (United States)

Newbold, Tim; Hudson, Lawrence N; Arnell, Andrew P; Contu, Sara; De Palma, Adriana; Ferrier, Simon; Hill, Samantha L L; Hoskins, Andrew J; Lysenko, Igor; Phillips, Helen R P; Burton, Victoria J; Chng, Charlotte W T; Emerson, Susan; Gao, Di; Pask-Hale, Gwilym; Hutton, Jon; Jung, Martin; Sanchez-Ortiz, Katia; Simmons, Benno I; Whitmee, Sarah; Zhang, Hanbin; Scharlemann, Jörn P W; Purvis, Andy

2016-07-15

Land use and related pressures have reduced local terrestrial biodiversity, but it is unclear how the magnitude of change relates to the recently proposed planetary boundary ("safe limit"). We estimate that land use and related pressures have already reduced local biodiversity intactness--the average proportion of natural biodiversity remaining in local ecosystems--beyond its recently proposed planetary boundary across 58.1% of the world's land surface, where 71.4% of the human population live. Biodiversity intactness within most biomes (especially grassland biomes), most biodiversity hotspots, and even some wilderness areas is inferred to be beyond the boundary. Such widespread transgression of safe limits suggests that biodiversity loss, if unchecked, will undermine efforts toward long-term sustainable development. Copyright © 2016, American Association for the Advancement of Science.

Refinement of the bottom boundary of the INES scale

International Nuclear Information System (INIS)

Ferjencik, Milos

2010-01-01

No existing edition of the International Nuclear Events Scale (INES) Manual addresses in depth the determination of the bottom boundary of the Scale, although a need for a definition is felt. The article introduces a method for determining the INES bottom boundary applicable to pressurized water reactors. This bottom boundary is put identical with the threshold of degradation of the installation's nuclear safety assurance. A comprehensive flowchart has been developed as the main outcome of the analysis of the nuclear safety assurance violation issue. The use of this flowchart in INES classification to replace the introductory question in the General INES Rating Procedure in the INES Manual is recommended. (orig.)

Constructing Integrable High-pressure Full-current Free-boundary Stellarator Magnetohydrodynamic Equilibrium Solutions

International Nuclear Information System (INIS)

Hudson, S.R.; Monticello, D.A.; Reiman, A.H.; Strickler, D.J.; Hirshman, S.P.; Ku, L-P; Lazarus, E.; Brooks, A.; Zarnstorff, M.C.; Boozer, A.H.; Fu, G-Y.; Neilson, G.H.

2003-01-01

For the (non-axisymmetric) stellarator class of plasma confinement devices to be feasible candidates for fusion power stations it is essential that, to a good approximation, the magnetic field lines lie on nested flux surfaces; however, the inherent lack of a continuous symmetry implies that magnetic islands responsible for breaking the smooth topology of the flux surfaces are guaranteed to exist. Thus, the suppression of magnetic islands is a critical issue for stellarator design, particularly for small aspect ratio devices. Pfirsch-Schluter currents, diamagnetic currents, and resonant coil fields contribute to the formation of magnetic islands, and the challenge is to design the plasma and coils such that these effects cancel. Magnetic islands in free-boundary high-pressure full-current stellarator magnetohydrodynamic equilibria are suppressed using a procedure based on the Princeton Iterative Equilibrium Solver [Reiman and Greenside, Comp. Phys. Comm. 43 (1986) 157] which iterate s the equilibrium equations to obtain the plasma equilibrium. At each iteration, changes to a Fourier representation of the coil geometry are made to cancel resonant fields produced by the plasma. The changes are constrained to preserve certain measures of engineering acceptability and to preserve the stability of ideal kink modes. As the iterations continue, the coil geometry and the plasma simultaneously converge to an equilibrium in which the island content is negligible, the plasma is stable to ideal kink modes, and the coils satisfy engineering constraints. The method is applied to a candidate plasma and coil design for the National Compact Stellarator Experiment [Reiman, et al., Phys. Plasmas 8 (May 2001) 2083

Constructing integrable high-pressure full-current free-boundary stellarator magnetohydrodynamic equilibrium solutions

International Nuclear Information System (INIS)

Hudson, S.R.; Monticello, D.A.; Reiman, A.H.

2003-01-01

For the (non-axisymmetric) stellarator class of plasma confinement devices to be feasible candidates for fusion power stations it is essential that, to a good approximation, the magnetic field lines lie on nested flux surfaces; however, the inherent lack of a continuous symmetry implies that magnetic islands responsible for breaking the smooth topology of the flux surfaces are guaranteed to exist. Thus, the suppression of magnetic islands is a critical issue for stellarator design, particularly for small aspect ratio devices. Pfirsch-Schlueter currents, diamagnetic currents and resonant coil fields contribute to the formation of magnetic islands, and the challenge is to design the plasma and coils such that these effects cancel. Magnetic islands in free-boundary high-pressure full-current stellarator magnetohydrodynamic equilibria are suppressed using a procedure based on the Princeton Iterative Equilibrium Solver (Reiman and Greenside 1986 Comput. Phys. Commun. 43 157) which iterates the equilibrium equations to obtain the plasma equilibrium. At each iteration, changes to a Fourier representation of the coil geometry are made to cancel resonant fields produced by the plasma. The changes are constrained to preserve certain measures of engineering acceptability and to preserve the stability of ideal kink modes. As the iterations continue, the coil geometry and the plasma simultaneously converge to an equilibrium in which the island content is negligible, the plasma is stable to ideal kink modes, and the coils satisfy engineering constraints. The method is applied to a candidate plasma and coil design for the National Compact Stellarator eXperiment (Reiman et al 2001 Phys. Plasma 8 2083). (author)

Comparative evaluation of pressure generated on a simulated maxillary oral analog by impression materials in custom trays of different spacer designs: An in vitro study.

Science.gov (United States)

Chopra, Sakshi; Gupta, Narendra Kumar; Tandan, Amrit; Dwivedi, Ravi; Gupta, Swati; Agarwal, Garima

2016-01-01

Literature reveals that masticatory load on denture bearing tissues through complete dentures should be maximum on primary stress bearing areas and least on relief area in accordance with the histology of underlying tissues. A study to validate the existing beliefs was planned to compare the pressure on mucosa using selective pressure technique and minimal pressure technique, with the incorporation of two different impression materials utilizing the pressure sensors during secondary impression procedure. The study was performed using a maxillary analog. Three pressure sensors were imbedded in the oral analog, one in the mid palatine area and the other two in the right and left ridge crest. Custom trays of two different configurations were fabricated. The two impression materials tested were light body and zinc oxide eugenol. A total of 40 impressions were made. A constant weight of 1 kg was placed, and the pressure was recorded as initial and end pressures. A significant difference in the pressure produced using different impression materials was found (P changing the amount of pressure produced. The impression materials used also had a significant role to play on the pressures acting on the tissues during impression procedure. Light body VPS impression material may be recommended to achieve minimal pressure on the denture bearing tissues in both selective as well as minimal pressure techniques.

Application of the boundary elements method for modeling of the fracture of cylindrical bodies by hydraulic fracturing

Science.gov (United States)

Legan, M. A.; Blinov, V. A.; Larichkin, A. Yu; Novoselov, A. N.

2017-10-01

Experimental study of hydraulic fracturing of thick-walled cylinders with a central circular hole was carried out using the machine that creates a high oil pressure. Experiments on the compression fracture of the solid cylinders by diameter and rectangular parallelepipeds perpendicular to the ends were carried out with a multipurpose test machine Zwick / Roell Z100. Samples were made of GF-177 material based on cement. Ultimate stresses in the material under study were determined for three types of stress state: under compression, with a pure shear on the surface of the hole under frecking conditions and under a compound stress state under conditions of diametral compression of a solid cylinder. The value of the critical stress intensity factor of GF-177 material was obtained. The modeling of the fracturing process taking into account the inhomogeneity of the stress state near the hole was carried out using the boundary elements method (in the variant of the fictitious load method) and the gradient fracture criterion. Calculation results of the ultimate pressure were compared with values obtained analytically on the basis of the Lame solution and with experimental data.

Pressurized Thermal Shock Analysis for OPR1000 Pressure Vessel

Energy Technology Data Exchange (ETDEWEB)

Bhowmik, P. K.; Shamim, J. A.; Gairola, A.; Suh, Kune Y. [Seoul National Univ., Seoul (Korea, Republic of)

2014-10-15

The study provides a brief understanding of the analysis procedure and techniques using ANSYS, such as the acceptance criteria, selection and categorization of events, thermal analysis, structural analysis including fracture mechanics assessment, crack propagation and evaluation of material properties. PTS may result from instrumentation and control malfunction, inadvertent steam dump, and postulated accidents such as smallbreak (SB) LOCA, large-break (LB) LOCA, main steam line break (MSLB), feedwater line breaks and steam generator overfill. In this study our main focus is to consider only the LB LOCA due to a cold leg break of the Optimized Power Reactor 1000 MWe (OPR1000). Consideration is given as well to the emergency core cooling system (ECCS) specific sequence with the operating parameters like pressure, temperature and time sequences. The static structural and thermal analysis to investigate the effects of PTS on RPV is the main motivation of this study. Specific surface crack effects and its propagation is also considered to measure the integrity of the RPV. This study describes the procedure for pressurized thermal shock analysis due to a loss of coolant accidental condition and emergency core cooling system operation for reactor pressure vessel.. Different accidental events that cause pressurized thermal shock to nuclear RPV that can also be analyzed in the same way. Considering the limitations of low speed computer only the static analysis is conducted. The modified LBLOCA phases and simplified geometry can is utilized to analyze the effect of PTS on RPV for general understanding not for specific specialized purpose. However, by integrating the disciplines of thermal and structural analysis, and fracture mechanics analysis a clearer understanding of the total aspect of the PTS problem has resulted. By adopting the CFD, thermal hydraulics, uncertainties and risk analysis for different type of accidental conditions, events and sequences with proper

Free Vibrations of Uniform Pipes Made From Composite Materials at an Internal Flow Under Effect of Additional Boundary Conditions

Directory of Open Access Journals (Sweden)

Nawal H. Al – Raheimy

2016-09-01

Full Text Available In this paper the approximate method of Raleigh method can be used to study the effect of additional boundary conditions (clamped – free & clamped – clamped on the free transverse vibrations of uniform pipes which have length, L (1m , inner radius, "Ri" (1cm & thickness, "t" (1mm made from composite materials, where the resin of unsaturated polyester represented the matrix material reinforced by aligned (E-fibers glass in the first case and used aligned fiber (Kevlar-49 in the second case. The length of fibers is in the two types, the first type is long fibers (continuous and the second is short fibers (discontinuous for different length all at volume fraction of fibers, "f" (0.15 & 0.25. At any construction of the pipe in composite material the natural frequency decreased when the velocity of flow increased from zero to critical velocity also can be observed the pipe at clamped – clamped boundary conditions predicts natural frequency & critical velocity greater than that pipe at clamped – free. The natural frequency and critical velocity increase with increasing volume fraction and length of discontinuous fiber. The value of natural frequency for pipes which have continuous fibers is constant at certain velocity of flow while are variable in pipes which have discontinuous fibers according to ratio between length of short fiber to critical length of discontinuous fiber whereas the natural frequency increase with increasing this ratio. Finally the pipes with Kevlar fiber have high critical velocity and natural frequency compare with pipes for fiber glass.

Effective Stress Law in Unconventional Reservoirs under Different Boundary Conditions

Science.gov (United States)

Saurabh, S.; Harpalani, S.

2017-12-01

Unconventional reservoirs have attracted a great deal of research interest worldwide during the past two decades. Low permeability and specialized techniques required to exploit these resources present opportunities for improvement in both production rates and ultimate recovery. Understanding subsurface stress modifications and permeability evolution are valuable when evaluating the prospects of unconventional reservoirs. These reservoir properties are functions of effective stress. As a part of this study, effective stress law, specifically the variation of anisotropic Biot's coefficient under various boundary conditions believed to exist in gas reservoirs by different researchers, has been established. Pressure-dependent-permeability (PdK) experiments were carried out on San Juan coal under different boundary conditions, that is, uniaxial strain condition and constant volume condition. Stress and strain in the vertical and horizontal directions were monitored throughout the experiment. Data collected during the experiments was used to determine the Biot's coefficient in vertical and horizontal directions under these two boundary conditions, treating coal as transversely isotropic. The variation of Biot's coefficient was found to be well correlated with the variation in coal permeability. Based on the estimated values of Biot's coefficients, a theory of variation in its value is presented for other boundary conditions. The findings of the study shed light on the inherent behavior of Biot's coefficient under different reservoir boundary conditions. This knowledge can improve the modeling work requiring estimation of effective stress in reservoirs, such as, pressure-/stress- dependent permeability. At the same time, if the effective stresses are known with more certainty by other methods, it enables assessment of the unknown reservoir boundary conditions.

Evaluation of responses to IE Bulletin 82-02: degradation of threaded fasteners in reactor coolant pressure boundary of pressurized-water-reactor plants

International Nuclear Information System (INIS)

Anderson, W.; Sterner, P.

1985-05-01

IE Bulletin 82-02 was issued by the NRC on June 2, 1982, to notify licensees about incidents of severe degradation of threaded fasteners. The bulletin required appropriate action including submittal of information from pressurized water reactors having an operating license. Responses from 41 licensees included their recent experience with degradation of threaded fasteners in primary system components. Data from recent regular inspections of reactor coolant pressure boundary component connections of 6-in. size and larger are compiled for technical evaluation. Statistical analysis is used to determine significant factors related to frequency of leakage incidents in connections, occurrence of degradation of bolts and studs, and the need for bolt replacement. Factors examined include the age of the plant, types of components, use of lubricants and sealants, and differences between plants. The compiled data indicate that, on the average, 10% of the bolted connections show evidence of leaking during an 18-month period. Also, 80% of the connections that show evidence of leakage undergo some degradation of the bolting. Results of the analysis show a significant decrease in the occurrence of bolting degradation events as the age of the plant increases. The data also show that valves are less subject to bolting corrosion. A group of 5 of the 41 plants accounted for about one-half of the reported leakage and corrosion events. The common characteristic found for four of these five plants was the lubricant used. The use of nickel-graphite based lubricants appears to offer a significantly reduced incidence of leakage and corrosion, based on late corrections to the reported data. The data also permit the conclusion that the use of molybdenum-disulfide-based lubricants and graphite-based lubricants results in a significantly increased incidence of leakage and corrosion. Reporting of data on lubricants was of poor quality and detracted from the value of the bulletin responses

Estimation of possibility of brittle fracture in high pressure boiler drums

International Nuclear Information System (INIS)

Grin', E.A.

2005-01-01

Paper presents the results of analysis of the problem to ensure brittle strength of high pressure boiler drums made with application of the present-day methods of linear and nonlinear fracture mechanics. The charts of the temperature boundaries of brittle fracture and of the critical factors of stress intensity plotted depending on the actual properties of the material and on dimensions of flaws are presented for standard size drums made of 22K and 16GNM steels. In the paper there are some examples of the practical application of the given charts [ru

Experimental Investigation of Magnetic Superconducting and other Phase Transitions in Novel f-Electron Materials at Ultra-high Pressures using Designer Diamond Anvils

International Nuclear Information System (INIS)

Maple, M. Brian; Jeffries, Jason R.; Ho, Pei-Chun; Butch, Nicholas P.

2004-01-01

Pressure is often used as a controlled parameter for the investigation of condensed matter systems. In particular, pressure experiments can provide valuable information into the nature of superconductivity, magnetism, and the coexistence of these two phenomena. Some f-electron, heavy-fermion materials display interesting and novel behavior at moderately low pressures achievable with conventional experimental techniques; however, a growing number of condensed matter systems require ultrahigh pressure techniques, techniques that generate significantly higher pressures than conventional methods, to sufficiently explore their important properties. To that end, we have been funded to develop an ultrahigh pressure diamond anvil cell facility at the University of California, San Diego (UCSD) in order to investigate superconductivity, magnetism, non-Fermi liquid behavior, and other phenomena. Our goals for the first year of this grant were as follows: (a) set up and test a suitable refrigerator; (b) set up a laser and spectrometer fluorescence system to determine the pressure within the diamond anvil cell; (c) perform initial resistivity measurements at moderate pressures from room temperature to liquid helium temperatures (∼1K); (d) investigate f-electron materials within our current pressure capabilities to find candidate materials for high-pressure studies. During the past year, we have ordered almost all the components required to set up a diamond anvil cell facility at UCSD, we have received and implemented many of the components that have been ordered, we have performed low pressure research on several materials, and we have engaged in a collaborative effort with Sam Weir at Lawrence Livermore National Lab (LLNL) to investigate Au4V under ultrahigh pressure in a designer diamond anvil cell (dDAC). This report serves to highlight the progress we have made towards developing an ultrahigh pressure research facility at UCSD, the research performed in the past year, as

The first word in material control is material

International Nuclear Information System (INIS)

Martin, H.R.; Wilkey, D.D.

1989-01-01

Material control has tended to rely on containment and access control, augmented by physical inventories, to meet the material control and accounting (MC ampersand A) goals of detecting theft/diversion and providing assurance that all nuclear material (NM) is present. Such systems have significant deficiencies. Material containment strategies are generally based on protection provided at boundaries around the NM and rely on alarms at the boundary for detection of theft/diversion. Assurance that all NM is present requires a negative inference based on the absence of alarms. Additionally, design of effective boundary protection systems requires that the designer be able to anticipate and provide protection for all scenarios that the insider adversary might utilize in removing material from the facility. Access control is an administrative system that cannot protect against malevolent actions by insiders authorized to access the material. Inventories may not provide timely detection of theft/diversion, and the sensitivity of detection depends on the magnitude of the variance of the inventory difference. More effective material control is provided for both material in storage and in process by a material-oriented system designed to detect abnormal events involving NM. Abnormal events are defined as any unauthorized activity involving NM, whether accidental or deliberate, and are assessed to determine the cause of the discrepancy. The designs of material-oriented control systems vary greatly, depending on the operations involved; however, a model system would include the use of process monitoring data for material control and automated surveillance of material in storage

Significance of Shrinkage Induced Clamping Pressure in Fiber-Matrix Bonding in Cementitious Composite Materials

DEFF Research Database (Denmark)

Stang, Henrik

1996-01-01

used in high performance cementitious composite materials.Assuming a Coulomb type of friction on the fiber/matrix interface andusing typical values for the frictional coefficient it is shownthat the shrinkage induced clamping pressure could be one of the mostimportant factors determining the frictional...

Study on Material Selection of Reactor Pressure Vessel of SCWR

Science.gov (United States)

Ma, Shuli; Luo, Ying; Yin, Qinwei; Li, Changxiang; Xie, Guofu

This paper first analyzes the feasibility of SA-508 Grade 3 Class 1 Steel as an alternative material for Supercritical Water-Cooled Reactor (SCWR) Reactor Pressure Vessel (RPV). This kind of steel is limited to be applied in SCWR RPV due to its quenching property, though large forging could be accomplished by domestic manufacturers in forging aspect. Therefore, steels with higher strength and better quenching property are needed for SWCR RPV. The chemical component of SA-508 Gr.3 Cl.2 steel is similar to that of SA-508 Gr.3 Cl.1 steel, and more appropriate matching of strength and toughness could be achieved by the adjusting the elements contents, as well as proper control of tempering temperature and time. In light of the fact that Cl.2 steel has been successfully applied to steam generator, it could be an alternative material for SWCR RPV. SA-508 Gr.4N steel with high strength and good toughness is another alternative material for SCWR RPV. But large amount of research work before application is still needed for the lack of data on welding and irradiation etc.

Explicitly represented polygon wall boundary model for the explicit MPS method

Science.gov (United States)

Mitsume, Naoto; Yoshimura, Shinobu; Murotani, Kohei; Yamada, Tomonori

2015-05-01

This study presents an accurate and robust boundary model, the explicitly represented polygon (ERP) wall boundary model, to treat arbitrarily shaped wall boundaries in the explicit moving particle simulation (E-MPS) method, which is a mesh-free particle method for strong form partial differential equations. The ERP model expresses wall boundaries as polygons, which are explicitly represented without using the distance function. These are derived so that for viscous fluids, and with less computational cost, they satisfy the Neumann boundary condition for the pressure and the slip/no-slip condition on the wall surface. The proposed model is verified and validated by comparing computed results with the theoretical solution, results obtained by other models, and experimental results. Two simulations with complex boundary movements are conducted to demonstrate the applicability of the E-MPS method to the ERP model.

INVESTIGATION OF MATERIAL RESISTANCE TO PLASTIC DEFORMATION AT PROCESSING METALS BY PRESSURE WITH IMPOSING ULTRASONIC OSCILLATIONS

Directory of Open Access Journals (Sweden)

V. V. Klubovich

2007-01-01

Full Text Available The paper contains substantiation for application of experimental technique in order to investigate material resistance to plastic deformation at processing metals by pressure with imposing ultrasonic oscillations while proceeding from laws of similarity. It is shown that at modeling any metal processing by pressure with imposing ultrasonic oscillations it is possible to consider that actual elastic and plastic metal properties remain constant during processing under ultrasound action. The second aspect that requires a special attention at modeling is pulse or vibration-shock deformation at processing metals by pressure with imposing ultrasonic oscillations.

Engineering model for low-velocity impacts of multi-material cylinder on a rigid boundary

Directory of Open Access Journals (Sweden)

Delvare F.

2012-08-01

Full Text Available Modern ballistic problems involve the impact of multi-material projectiles. In order to model the impact phenomenon, different levels of analysis can be developed: empirical, engineering and simulation models. Engineering models are important because they allow the understanding of the physical phenomenon of the impact materials. However, some simplifications can be assumed to reduce the number of variables. For example, some engineering models have been developed to approximate the behavior of single cylinders when impacts a rigid surface. However, the cylinder deformation depends of its instantaneous velocity. At this work, an analytical model is proposed for modeling the behavior of a unique cylinder composed of two different metals cylinders over a rigid surface. Material models are assumed as rigid-perfectly plastic. Differential equation systems are solved using a numerical Runge-Kutta method. Results are compared with computational simulations using AUTODYN 2D hydrocode. It was found a good agreement between engineering model and simulation results. Model is limited by the impact velocity which is transition at the interface point given by the hydro dynamical pressure proposed by Tate.

LB03.04: SPHYGMOMANOMETER CUFF CONSTRUCTION AND MATERIALS AFFECT TRANSMISSION OF PRESSURE FROM CUFF TO ARTERIAL WALL. FINITE ELEMENT ANALYSIS OF HUMAN PRESSURE MEASUREMENTS AND DICOM DATA.

Science.gov (United States)

Lewis, P; Naqvi, S; Mandal, P; Potluri, P

2015-06-01

Sphygmomanometer cuff pressure during deflation is assumed to equal systolic arterial pressure at the point of resumption of flow. Previous studies demonstrated that pressure decreases with increasing depth of soft tissues whilst visco-elastic characteristics of the arm tissue cause spatial and temporal variation in pressure magnitude. These generally used non-anatomical axisymmetrical arm simulations without incorporating arterial pressure variation. We used data from a volunteer's Magnetic Resonance (MR) arm scan and investigated the effect of variations in cuff materials and construction on the simulated transmission of pressure from under the cuff to the arterial wall under sinusoidal flow conditions. Pressure was measured under 8 different cuffs using Oxford Pressure Monitor Sensors placed at 90 degrees around the mid upper arm of a healthy male. Each cuff was inflated 3 times to 155 mmHg and then deflated to zero with 90 seconds between inflations. Young's modulus, flexural rigidity and thickness of each cuff was measured.Using DICOM data from the MR scan of the arm, a 3D model was derived using ScanIP and imported into Abaqus for Finite Element Analysis (FEA). Published mechanical properties of arm tissues and geometric non-linearity were assumed. The measured sub-cuff pressures were applied to the simulated arm and pressure was calculated around the brachial arterial wall. which was loaded with a sinusoidal pressure of 125/85 mmHg. FEA estimates of pressure around the brachial artery cuffs varied by up to 27 mmHg SBP and 17 mmHg DBP with different cuffs. Pressures within the cuffs varied up to 27 mmHg. Pressure transmission from the cuff to the arterial surface achieved a 95% transmission ratio with one rubber-bladdered cuff but varied between 76 and 88% for the others. Non-uniform pressure distribution around the arterial wall was strongly related to cuff fabric elastic modulus. Identical size cuffs with a separate rubber bladder produced peri

Numerical study of compressible magnetoconvection with an open transitional boundary

International Nuclear Information System (INIS)

Hanami, H.; Tajima, T.

1990-08-01

We study by computer simulation nonlinear evolution of magnetoconvection in a system with a dynamical open boundary between the convection region and corona of the sun. We study a model in which the fluid is subject to the vertical gravitation, magnetohydrodynamics (MHD), and high stratification, through an MHD code with the MacCormack-Donner cell hybrid scheme in order to well represent convective phenomena. Initially the vertical fluid flux penetrates from the convectively unstable zone at the bottom into the upper diffuse atmosphere. As the instability develops, the magnetic fields are twisted by the convection motion and the folding magnetic fields is observed. When the magnetic pressure is comparable to the thermal pressure in the upper layer of convective zone, strong flux expulsion from the convective cell interior toward the cell boundary appears. Under appropriate conditions our simulation exhibits no shock formation incurred by the fluid convected to the photosphere, in contrast to earlier works with box boundaries. The magnetic field patterns observed are those of concentrated magnetic flux tubes, accumulation of dynamo flux near the bottom boundary, pinched flux near the downdraft region, and the surface movement of magnetic flux toward the downdraft region. Many of these computationally observed features are reminiscent of solar observations of the fluid and magnetic structures of their motions

Pressure-Sensitive Resistor Material

Science.gov (United States)

Du Fresne, E. R.

1986-01-01

Low-conductivity particles in rubber offer wide dynamic range. Sensor consists of particles of relatively low conductivity embedded in rubber. Resistance of sensor decreases by about 100 times as pressure on it increases from zero to 0.8 MN/M to the second power. Resistor promising candidate as tactile sensor for robots and remote manipulators.

The atomic-scale origins of grain boundary superconducting properties

International Nuclear Information System (INIS)

Pennycook, S.J.; Chisholm, M.F.; Buban, J.; Browning, N.D.; Prouteau, C.; Univ. of Illinois, Chicago, IL; Nellist, P.D.

1998-02-01

Due to the extremely short coherence lengths of the high-T c superconductors, defects such as grain boundaries are obvious barriers to the flow of supercurrent. Within a few months of the discovery of these materials, it was shown how the critical current dropped four orders of magnitude as the grain boundary misorientation increased from zero to 45 degree. Even today, there is no quantitative understanding of this behavior. A qualitative understanding is however possible through atomic resolution Z-contrast imaging on YBa 2 Cu 3 O 7-δ and SrTiO 3 bicrystal grain boundaries, combined with bond-valence-sum analysis. The Z-contrast image of a YBa 2 Cu 3 O 7-δ low angle grain boundary shows the same kind of reconstructed dislocation cores as seen in SrTiO 3 , containing reconstructions on both the Cu and Y/Ba sublattices. An image of an asymmetric 30 degree boundary in YBa 2 Cu 3 O 7-δ shows the same units and unit sequence as expected for SrTiO 3 . YBa 2 Cu 3 O 7-δ boundaries are wavy because of their non-equilibrium growth process, and therefore mostly asymmetric in nature, although small segments have the symmetric structure. It seems reasonable to assume that boundaries of other angles will also have similar structures in these two materials

Impact of condensed matter theories on material studies at high pressures

International Nuclear Information System (INIS)

Godwal, B.K.; Rao, R.S.; Sikka, S.K.; Chidambaram, R.

1997-01-01

We are vigorously pursuing a program to study the behaviour of materials under pressure for the last three decades. Theoretical component has been an important part of our activity. The initial phase of such efforts was devoted to the development of equation of state models at arbitrary temperature and matter density. With the advent of diamond anvil cell device and improvements of the diagnostic technique in dynamic methods, the focus of our studies switched over to the predictions and interpretations of phase transitions. Many times these have led to intense experimental studies and sometimes helped in resolving the controversies. The introduction of linear methods in electron band theory and availability of supercomputers and parallel processors have given boost to the computational physics, and the efforts are now being extended more and more to the ab-initio molecular dynamics simulations. These simulations have a promise to avoid the tedious search for structural stability by trail and error in phase transition studies under pressure or temperature. The current status of our efforts in this direction will be listed with an illustration on liquid sulphur. Our past work on electronic topological transition in zinc led to many experimental and theoretical investigations. The results of electronic structure changes in similar metal cadmium shall be compared with existing understanding in Zn under pressure. Our studies on other compounds (AuIn 2 , YNi 2 B 2 C), which have also been found to display electronic topological transition under pressure, will be discussed. (author)

Receptivity of Hypersonic Boundary Layers to Acoustic and Vortical Disturbances (Invited)

Science.gov (United States)

Balakumar, P.

2015-01-01

Boundary-layer receptivity to two-dimensional acoustic and vortical disturbances for hypersonic flows over two-dimensional and axi-symmetric geometries were numerically investigated. The role of bluntness, wall cooling, and pressure gradients on the receptivity and stability were analyzed and compared with the sharp nose cases. It was found that for flows over sharp nose geometries in adiabatic wall conditions the instability waves are generated in the leading-edge region and that the boundary layer is much more receptive to slow acoustic waves as compared to the fast waves. The computations confirmed the stabilizing effect of nose bluntness and the role of the entropy layer in the delay of boundary layer transition. The receptivity coefficients in flows over blunt bodies are orders of magnitude smaller than that for the sharp cone cases. Wall cooling stabilizes the first mode strongly and destabilizes the second mode. However, the receptivity coefficients are also much smaller compared to the adiabatic case. The adverse pressure gradients increased the unstable second mode regions.

Capillary pressure-saturation relationships for porous granular materials: Pore morphology method vs. pore unit assembly method

Science.gov (United States)

Sweijen, Thomas; Aslannejad, Hamed; Hassanizadeh, S. Majid

2017-09-01

In studies of two-phase flow in complex porous media it is often desirable to have an estimation of the capillary pressure-saturation curve prior to measurements. Therefore, we compare in this research the capability of three pore-scale approaches in reproducing experimentally measured capillary pressure-saturation curves. To do so, we have generated 12 packings of spheres that are representative of four different glass-bead packings and eight different sand packings, for which we have found experimental data on the capillary pressure-saturation curve in the literature. In generating the packings, we matched the particle size distributions and porosity values of the granular materials. We have used three different pore-scale approaches for generating the capillary pressure-saturation curves of each packing: i) the Pore Unit Assembly (PUA) method in combination with the Mayer and Stowe-Princen (MS-P) approximation for estimating the entry pressures of pore throats, ii) the PUA method in combination with the hemisphere approximation, and iii) the Pore Morphology Method (PMM) in combination with the hemisphere approximation. The three approaches were also used to produce capillary pressure-saturation curves for the coating layer of paper, used in inkjet printing. Curves for such layers are extremely difficult to determine experimentally, due to their very small thickness and the presence of extremely small pores (less than one micrometer in size). Results indicate that the PMM and PUA-hemisphere method give similar capillary pressure-saturation curves, because both methods rely on a hemisphere to represent the air-water interface. The ability of the hemisphere approximation and the MS-P approximation to reproduce correct capillary pressure seems to depend on the type of particle size distribution, with the hemisphere approximation working well for narrowly distributed granular materials.

Effect of oxygen partial pressure on the density of antiphase boundaries in Fe3O4 thin films on Si(100)

Science.gov (United States)

Singh, Suraj Kumar; Husain, Sajid; Kumar, Ankit; Chaudhary, Sujeet

2018-02-01

Polycrystalline Fe3O4 thin films were grown on Si(100) substrate by reactive DC sputtering at different oxygen partial pressures PO2 for controlling the growth associated density of antiphase boundaries (APBs). The micro-Raman analyses were performed to study the structural and electronic properties in these films. The growth linked changes in the APBs density are probed by electron-phonon coupling strength (λ) and isothermal magnetization measurements. The estimated values of λ are found to vary from 0.39 to 0.56 with the increase in PO2 from 2.2 × 10-5 to 3.0 × 10-5 Torr, respectively. The saturation magnetization (saturation field) values are found to increase (decrease) from 394 (5.9) to 439 (3.0) emu/cm3 (kOe) with the increase in PO2 . The sharp Verwey transition (∼120 K), low saturation field, high saturation magnetization and low value of λ (comparable to the bulk value ∼0.51) clearly affirm the negligible amount of APBs in the high oxygen partial pressure deposited thin films.

Role of Grain Boundaries under Long-Time Radiation

Science.gov (United States)

Zhu, Yichao; Luo, Jing; Guo, Xu; Xiang, Yang; Chapman, Stephen Jonathan

2018-06-01

Materials containing a high proportion of grain boundaries offer significant potential for the development of radiation-resistant structural materials. However, a proper understanding of the connection between the radiation-induced microstructural behavior of a grain boundary and its impact at long natural time scales is still missing. In this Letter, point defect absorption at interfaces is summarized by a jump Robin-type condition at a coarse-grained level, wherein the role of interface microstructure is effectively taken into account. Then a concise formula linking the sink strength of a polycrystalline aggregate with its grain size is introduced and is well compared with experimental observation. Based on the derived model, a coarse-grained formulation incorporating the coupled evolution of grain boundaries and point defects is proposed, so as to underpin the study of long-time morphological evolution of grains induced by irradiation. Our simulation results suggest that the presence of point defect sources within a grain further accelerates its shrinking process, and radiation tends to trigger the extension of twin boundary sections.

Topology optimization of pressure adaptive honeycomb for a morphing flap

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Vos, Roelof; Scheepstra, Jan; Barrett, Ron

2011-03-01

The paper begins with a brief historical overview of pressure adaptive materials and structures. By examining avian anatomy, it is seen that pressure-adaptive structures have been used successfully in the Natural world to hold structural positions for extended periods of time and yet allow for dynamic shape changes from one flight state to the next. More modern pneumatic actuators, including FAA certified autopilot servoactuators are frequently used by aircraft around the world. Pneumatic artificial muscles (PAM) show good promise as aircraft actuators, but follow the traditional model of load concentration and distribution commonly found in aircraft. A new system is proposed which leaves distributed loads distributed and manipulates structures through a distributed actuator. By using Pressure Adaptive Honeycomb (PAH), it is shown that large structural deformations in excess of 50% strains can be achieved while maintaining full structural integrity and enabling secondary flight control mechanisms like flaps. The successful implementation of pressure-adaptive honeycomb in the trailing edge of a wing section sparked the motivation for subsequent research into the optimal topology of the pressure adaptive honeycomb within the trailing edge of a morphing flap. As an input for the optimization two known shapes are required: a desired shape in cruise configuration and a desired shape in landing configuration. In addition, the boundary conditions and load cases (including aerodynamic loads and internal pressure loads) should be specified for each condition. Finally, a set of six design variables is specified relating to the honeycomb and upper skin topology of the morphing flap. A finite-element model of the pressure-adaptive honeycomb structure is developed specifically tailored to generate fast but reliable results for a given combination of external loading, input variables, and boundary conditions. Based on two bench tests it is shown that this model correlates well

Boundary migration in a 3D deformed microstructure inside an opaque sample

DEFF Research Database (Denmark)

Zhang, Yubin; Budai, J D; Tischler, Jonathan Z.

2017-01-01

How boundaries surrounding recrystallization grains migrate through the 3D network of dislocation boundaries in deformed crystalline materials is unknown and critical for the resulting recrystallized crystalline materials. Using X-ray Laue diffraction microscopy, we show for the first time....... The results show that neither of these two parameters can explain the observed migration behavior. Instead we suggest that the subdivision of the deformed microstructure ahead of the boundary plays the dominant role. The present experimental observations challenge the assumptions of existing recrystallization...

Transitional and turbulent boundary layer with heat transfer

Science.gov (United States)

Wu, Xiaohua; Moin, Parviz

2010-08-01

We report on our direct numerical simulation of an incompressible, nominally zero-pressure-gradient flat-plate boundary layer from momentum thickness Reynolds number 80-1950. Heat transfer between the constant-temperature solid surface and the free-stream is also simulated with molecular Prandtl number Pr=1. Skin-friction coefficient and other boundary layer parameters follow the Blasius solutions prior to the onset of turbulent spots. Throughout the entire flat-plate, the ratio of Stanton number and skin-friction St/Cf deviates from the exact Reynolds analogy value of 0.5 by less than 1.5%. Mean velocity and Reynolds stresses agree with experimental data over an extended turbulent region downstream of transition. Normalized rms wall-pressure fluctuation increases gradually with the streamwise growth of the turbulent boundary layer. Wall shear stress fluctuation, τw,rms'+, on the other hand, remains constant at approximately 0.44 over the range, 800spots are tightly packed with numerous hairpin vortices. With the advection and merging of turbulent spots, these young isolated hairpin forests develop into the downstream turbulent region. Isosurfaces of temperature up to Reθ=1900 are found to display well-resolved signatures of hairpin vortices, which indicates the persistence of the hairpin forests.

Performance-oriented Architecture and the Spatial and Material Organisation Complex. Rethinking the Definition, Role and Performative Capacity of the Spatial and Material Boundaries of the Built Environment

Directory of Open Access Journals (Sweden)

Michael Ulrich Hensel

2011-03-01

Full Text Available This article is based on the proposition that performance-oriented design is characterised by four domains of ‘active agency’: the human subject, the spatial and material organisation complex and the environment (Hensel, 2010. While these four domains are seen to be interdependent and interacting with one another, it is nevertheless necessary to examine each in its own right. However, the spatial and material organisation complex contains both the spatial and material domains, which are interdependent to such a degree that these need to be examined in relation to one another and also in relation to the specific environment they are set within and interacting with. To explore this combined domain within the context of performance-oriented design is the aim of this article, in particularly in relation to the question of the definition and performative capacity of spatial and material boundaries. The various sections are accompanied by research by design efforts undertaken in specified academic contexts, which are intended as examples of modes and areas of inquiry relative to the purpose of this article.

Boundary modulation effects on MHD instabilities in Heliotrons

International Nuclear Information System (INIS)

Nakajima, N.; Hudson, S.R.; Hegna, C.C.; Nakamura, Y.

2005-01-01

In three-dimensional configurations, the confinement region is surrounded by the stochastic magnetic field lines related to magnetic islands or separatrix, leading to the fact that the plasma-vacuum boundary is not so definite compared with tokamaks that the various modulations of the plasma-vacuum boundary will be induced around the stochastic region by a large Shafranov shift of the whole plasma, in especially high-β operations. To examine such the modulation effects of the plasma boundary on MHD instabilities, high-β plasmas allowing a large Shafranov shift are considered in the inward-shifted LHD configurations with the vacuum magnetic axis R ax of 3.6m, for which previous theoretical analyses indicate that pressure-driven modes are significantly more unstable compared with experimental observations. It is shown that the boundary modulation due to a free motion of the equilibrium plasma has not only significant stabilizing effects on ideal MHD instabilities, but also characteristics consistent to experimental observations. (author)

Pore water pressures and slope stability: a joint geophysical and geotechnical analysis

International Nuclear Information System (INIS)

Perrone, Angela; Lapenna, Vincenzo; Vassallo, Roberto; Maio, Caterina Di

2008-01-01

Slope stability is influenced by many factors, among which are subsoil structure and pore water pressure distribution. This paper presents a multi-disciplinary approach for the determination of these two factors and for the construction of a reliable model of the subsoil for the slope stability analysis. The case of a clay slope located in the Southern Apennines (Italy) is presented and discussed. Geophysical imaging (2D electrical resistivity tomography—ERT), in situ geotechnical monitoring (measurements of pore pressures and horizontal displacements) and laboratory geotechnical tests (for the determination of index, hydraulic and mechanical properties of soils) have been carried out. The comparison and the integration between ERT images and direct observations of the material extracted from boreholes have allowed us to reconstruct the subsoil stratigraphy with continuity. Thus, a reliable 2D model of the subsoil has been obtained, with well-defined boundaries on which it has been possible to apply appropriate hydraulic conditions. This geotechnical model has been used for studying the pore water pressure distribution and for analysing how the hydraulic boundary conditions—among which rain events—influence the slope stability. Our findings demonstrate the powerful skill of the ERT, if integrated with borehole data, to generate an accurate subsoil model. It is also evident that geophysical imaging can be a source of ambiguity and misjudgement if interpreted without a comparison with geotechnical data

Thermocouple Rakes for Measuring Boundary Layer Flows Extremely Close to Surface

Science.gov (United States)

Hwang, Danny P.; Fralick, Gustave C.; Martin, Lisa C.; Blaha, Charles A.

2001-01-01

Of vital interest to aerodynamic researchers is precise knowledge of the flow velocity profile next to the surface. This information is needed for turbulence model development and the calculation of viscous shear force. Though many instruments can determine the flow velocity profile near the surface, none of them can make measurements closer than approximately 0.01 in. from the surface. The thermocouple boundary-layer rake can measure much closer to the surface than conventional instruments can, such as a total pressure boundary layer rake, hot wire, or hot film. By embedding the sensors (thermocouples) in the region where the velocity is equivalent to the velocity ahead of a constant thickness strut, the boundary-layer flow profile can be obtained. The present device fabricated at the NASA Glenn Research Center microsystem clean room has a heater made of platinum and thermocouples made of platinum and gold. Equal numbers of thermocouples are placed both upstream and downstream of the heater, so that the voltage generated by each pair at the same distance from the surface is indicative of the difference in temperature between the upstream and downstream thermocouple locations. This voltage differential is a function of the flow velocity, and like the conventional total pressure rake, it can provide the velocity profile. In order to measure flow extremely close to the surface, the strut is made of fused quartz with extremely low heat conductivity. A large size thermocouple boundary layer rake is shown in the following photo. The latest medium size sensors already provide smooth velocity profiles well into the boundary layer, as close as 0.0025 in. from the surface. This is about 4 times closer to the surface than the previously used total pressure rakes. This device also has the advantage of providing the flow profile of separated flow and also it is possible to measure simultaneous turbulence levels within the boundary layer.

Optimization of Composite Material System and Lay-up to Achieve Minimum Weight Pressure Vessel

Science.gov (United States)

Mian, Haris Hameed; Wang, Gang; Dar, Uzair Ahmed; Zhang, Weihong

2013-10-01

The use of composite pressure vessels particularly in the aerospace industry is escalating rapidly because of their superiority in directional strength and colossal weight advantage. The present work elucidates the procedure to optimize the lay-up for composite pressure vessel using finite element analysis and calculate the relative weight saving compared with the reference metallic pressure vessel. The determination of proper fiber orientation and laminate thickness is very important to decrease manufacturing difficulties and increase structural efficiency. In the present work different lay-up sequences for laminates including, cross-ply [ 0 m /90 n ] s , angle-ply [ ±θ] ns , [ 90/±θ] ns and [ 0/±θ] ns , are analyzed. The lay-up sequence, orientation and laminate thickness (number of layers) are optimized for three candidate composite materials S-glass/epoxy, Kevlar/epoxy and Carbon/epoxy. Finite element analysis of composite pressure vessel is performed by using commercial finite element code ANSYS and utilizing the capabilities of ANSYS Parametric Design Language and Design Optimization module to automate the process of optimization. For verification, a code is developed in MATLAB based on classical lamination theory; incorporating Tsai-Wu failure criterion for first-ply failure (FPF). The results of the MATLAB code shows its effectiveness in theoretical prediction of first-ply failure strengths of laminated composite pressure vessels and close agreement with the FEA results. The optimization results shows that for all the composite material systems considered, the angle-ply [ ±θ] ns is the optimum lay-up. For given fixed ply thickness the total thickness of laminate is obtained resulting in factor of safety slightly higher than two. Both Carbon/epoxy and Kevlar/Epoxy resulted in approximately same laminate thickness and considerable percentage of weight saving, but S-glass/epoxy resulted in weight increment.

On mathematical modelling and numerical simulation of transient compressible flow across open boundaries

Energy Technology Data Exchange (ETDEWEB)

Rian, Kjell Erik

2003-07-01

In numerical simulations of turbulent reacting compressible flows, artificial boundaries are needed to obtain a finite computational domain when an unbounded physical domain is given. Artificial boundaries which fluids are free to cross are called open boundaries. When calculating such flows, non-physical reflections at the open boundaries may occur. These reflections can pollute the solution severely, leading to inaccurate results, and the generation of spurious fluctuations may even cause the numerical simulation to diverge. Thus, a proper treatment of the open boundaries in numerical simulations of turbulent reacting compressible flows is required to obtain a reliable solution for realistic conditions. A local quasi-one-dimensional characteristic-based open-boundary treatment for the Favre-averaged governing equations for time-dependent three-dimensional multi-component turbulent reacting compressible flow is presented. A k-{epsilon} model for turbulent compressible flow and Magnussen's EDC model for turbulent combustion is included in the analysis. The notion of physical boundary conditions is incorporated in the method, and the conservation equations themselves are applied on the boundaries to complement the set of physical boundary conditions. A two-dimensional finite-difference-based computational fluid dynamics code featuring high-order accurate numerical schemes was developed for the numerical simulations. Transient numerical simulations of the well-known, one-dimensional shock-tube problem, a two-dimensional pressure-tower problem in a decaying turbulence field, and a two-dimensional turbulent reacting compressible flow problem have been performed. Flow- and combustion-generated pressure waves seem to be well treated by the non-reflecting subsonic open-boundary conditions. Limitations of the present open-boundary treatment are demonstrated and discussed. The simple and solid physical basis of the method makes it both favourable and relatively easy to

Characterization of the Boundary Layer on Full-Scale Bluefin Tuna

Science.gov (United States)

Amaral, Brian; Cipolla, Kimberly; Henoch, Charles

2014-11-01

The physics that enable tuna to cross large expanses of ocean while feeding and avoiding predators is not presently understood, and could involve complex control of turbulent boundary layer transition and drag reduction. Typical swimming speeds of Bluefin tuna are 1-2 m/s, but can be higher during strong accelerations. The goal of this work is to experimentally determine the approximate lateral location at which transition to turbulence occurs on the tuna for various speeds. The question is whether laminar flow or an advanced propulsion mechanism (or both) allows them to swim at high speeds. Uncertainties include the surface roughness of the skin, local favorable and adverse pressure gradients, and discontinuities such as the open mouth or juncture at the fins. Historically, much of the fluid mechanics work in the area of fish locomotion has focused on vortex shedding issues rather than the boundary layer. Here, the focus is obtaining information on the boundary layer characteristics of a rigid tuna model. A full scale model of a Pacific Bluefin tuna was fabricated using a mold made from an actual deceased tuna, preserving the surface features and details of the appendages. The model was instrumented with 32 wall pressure sensors and experiments performed in a tow tank. Results from flow visualization, drag and wall pressure measurements over a range of speeds and varying angles of attack will be presented.