Total contact cast wall load in patients with a plantar forefoot ulcer and diabetes.

PubMed

Begg, Lindy; McLaughlin, Patrick; Vicaretti, Mauro; Fletcher, John; Burns, Joshua

2016-01-01

The total contact cast (TCC) is an effective intervention to reduce plantar pressure in patients with diabetes and a plantar forefoot ulcer. The walls of the TCC have been indirectly shown to bear approximately 30 % of the plantar load. A new direct method to measure inside the TCC walls with capacitance sensors has shown that the anterodistal and posterolateral-distal regions of the lower leg bear the highest load. The objective of this study was to directly measure these two regions in patients with Diabetes and a plantar forefoot ulcer to further understand the mechanism of pressure reduction in the TCC. A TCC was applied to 17 patients with Diabetes and a plantar forefoot ulcer. TCC wall load (contact area, peak pressure and max force) at the anterodistal and posterolateral-distal regions of the lower leg were evaluated with two capacitance sensor strips measuring 90 cm(2) (pliance®, novel GmbH, Germany). Plantar load (contact area, peak pressure and max force) was measured with a capacitance sensor insole (pedar®, novel GmbH, Germany) placed inside the TCC. Both pedar® and pliance® collected data simultaneously at a sampling rate of 50Hz synchronised to heel strike. The magnitude of TCC wall load as a proportion of plantar load was calculated. The TCC walls were then removed to determine the differences in plantar loading between the TCC and the cut down shoe-cast for the whole foot, rearfoot, midfoot and forefoot (region of interest). TCC wall load was substantial. The anterodistal lower leg recorded 48 % and the posterolateral-distal lower leg recorded 34 % of plantar contact area. The anterodistal lower leg recorded 28 % and the posterolateral-distal lower leg recorded 12 % of plantar peak pressure. The anterodistal lower leg recorded 12 % and the posterolateral-distal lower leg recorded 4 % of plantar max force. There were significant differences in plantar load between the TCC and the cut down shoe-cast for the whole foot, rearfoot, midfoot and forefoot (region of ulcer). Contact area significantly increased by 5 % beneath the whole foot, 8 % at the midfoot and 6 % at the forefoot in the shoe-cast (p < 0.05). Peak pressure significantly increased by 8 % beneath the midfoot and 13 % at the forefoot in the shoe-cast (p < 0.05). Max force significantly increased 6 % beneath the midfoot in the (shoe-cast p < 0.05). In patients with diabetes and a plantar forefoot ulcer, the walls of the TCC bear considerable load. Reduced plantar contact area in the TCC compared to the shoe-cast suggests that the foot is suspended by the considerable load bearing capacity of the walls of the TCC which contributes mechanically to the pressure reduction and redistribution properties of the TCC.

Finite element analyses of continuous filament ties for masonry applications : final report for the Arquin Corporation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Quinones, Armando, Sr.; Bibeau, Tiffany A.; Ho, Clifford Kuofei

2008-08-01

Finite-element analyses were performed to simulate the response of a hypothetical vertical masonry wall subject to different lateral loads with and without continuous horizontal filament ties laid between rows of concrete blocks. A static loading analysis and cost comparison were also performed to evaluate optimal materials and designs for the spacers affixed to the filaments. Results showed that polypropylene, ABS, and polyethylene (high density) were suitable materials for the spacers based on performance and cost, and the short T-spacer design was optimal based on its performance and functionality. Simulations of vertical walls subject to static loads representing 100 mph windsmore » (0.2 psi) and a seismic event (0.66 psi) showed that the simulated walls performed similarly and adequately when subject to these loads with and without the ties. Additional simulations and tests are required to assess the performance of actual walls with and without the ties under greater loads and more realistic conditions (e.g., cracks, non-linear response).« less

Safety Harness For Work Under Suspended Load

NASA Technical Reports Server (NTRS)

Sunoo, Su Young

1994-01-01

Safety device protects worker under suspended engine or other heavy load. Mechanically linked with load so if load should fall, worker yanked safely away. Worker wears chest-plate vest with straps crossing eye on back. Lower safety cable connected to eye extends horizontally away from worker to nearby wall, wrapped on pulley and extends upward to motion amplifier or reducer. Safety cables transform any sudden downward motion of overhanging load into rapid sideways motion of worker. Net catches worker, preventing worker from bumping against wall.

Looking Northwest at First Floor Typical Wall and Ceiling Juncture ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Looking Northwest at First Floor Typical Wall and Ceiling Juncture in Oxide Building and Loading Dock - Hematite Fuel Fabrication Facility, Oxide Building & Oxide Loading Dock, 3300 State Road P, Festus, Jefferson County, MO

76 FR 30399 - Duke Energy Carolinas, LLC, Oconee Nuclear Station, Units 1, 2, and 3, Notice of Consideration of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-25

... the use of fiber reinforced polymer on masonry walls for uniform pressure loads resulting from a... fail as a result of damage caused by natural phenomena. The in-fill masonry walls to be strengthened... system on existing Auxiliary Building masonry walls will allow them to resist uniform pressure loads...

Transient three-dimensional startup side load analysis of a regeneratively cooled nozzle

NASA Astrophysics Data System (ADS)

Wang, Ten-See

2009-07-01

The objective of this effort is to develop a computational methodology to capture the side load physics and to anchor the computed aerodynamic side loads with the available data by simulating the startup transient of a regeneratively cooled, high-aspect-ratio nozzle, hot-fired at sea level. The computational methodology is based on an unstructured-grid, pressure-based, reacting flow computational fluid dynamics and heat transfer formulation, and a transient inlet history based on an engine system simulation. Emphases were put on the effects of regenerative cooling on shock formation inside the nozzle, and ramp rate on side load reduction. The results show that three types of asymmetric shock physics incur strong side loads: the generation of combustion wave, shock transitions, and shock pulsations across the nozzle lip, albeit the combustion wave can be avoided with sparklers during hot-firing. Results from both regenerative cooled and adiabatic wall boundary conditions capture the early shock transitions with corresponding side loads matching the measured secondary side load. It is theorized that the first transition from free-shock separation to restricted-shock separation is caused by the Coanda effect. After which the regeneratively cooled wall enhances the Coanda effect such that the supersonic jet stays attached, while the hot adiabatic wall fights off the Coanda effect, and the supersonic jet becomes detached most of the time. As a result, the computed peak side load and dominant frequency due to shock pulsation across the nozzle lip associated with the regeneratively cooled wall boundary condition match those of the test, while those associated with the adiabatic wall boundary condition are much too low. Moreover, shorter ramp time results show that higher ramp rate has the potential in reducing the nozzle side loads.

Parametric Study on the Response of Compression-Loaded Composite Shells With Geometric and Material Imperfections

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.; Starnes, James H., Jr.

2004-01-01

The results of a parametric study of the effects of initial imperfections on the buckling and postbuckling response of three unstiffened thinwalled compression-loaded graphite-epoxy cylindrical shells with different orthotropic and quasi-isotropic shell-wall laminates are presented. The imperfections considered include initial geometric shell-wall midsurface imperfections, shell-wall thickness variations, local shell-wall ply-gaps associated with the fabrication process, shell-end geometric imperfections, nonuniform applied end loads, and variations in the boundary conditions including the effects of elastic boundary conditions. A high-fidelity nonlinear shell analysis procedure that accurately accounts for the effects of these imperfections on the nonlinear responses and buckling loads of the shells is described. The analysis procedure includes a nonlinear static analysis that predicts stable response characteristics of the shells and a nonlinear transient analysis that predicts unstable response characteristics.

Application of ECT inspection to the first wall of a fusion reactor with wavelet analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, G.; Yoshida, Y.; Miya, K.

1994-12-31

The first wall of a fusion reactor will be subjected to intensive loads during fusion operations. Since these loads may cause defects in the first wall, nondestructive evaluation techniques of the first wall should be developed. In this paper, we try to apply eddy current testing (ECT) technique to the inspection of the first wall. A method based on current vector potential and wavelet analysis is proposed. Owing to the use of wavelet analysis, a new theory developed recently, the accuracy of the present method is shown to be better than a conventional one.

Layer-dependent role of collagen recruitment during loading of the rat bladder wall.

PubMed

Cheng, Fangzhou; Birder, Lori A; Kullmann, F Aura; Hornsby, Jack; Watton, Paul N; Watkins, Simon; Thompson, Mark; Robertson, Anne M

2018-04-01

In this work, we re-evaluated long-standing conjectures as to the source of the exceptionally large compliance of the bladder wall. Whereas these conjectures were based on indirect measures of loading mechanisms, in this work we take advantage of advances in bioimaging to directly assess collagen fibers and wall architecture during biaxial loading. A custom biaxial mechanical testing system compatible with multiphoton microscopy was used to directly measure the layer-dependent collagen fiber recruitment in bladder tissue from 9 male Fischer rats (4 adult and 5 aged). As for other soft tissues, the bladder loading curve was exponential in shape and could be divided into toe, transition and high stress regimes. The relationship between collagen recruitment and loading curves was evaluated in the context of the inner (lamina propria) and outer (detrusor smooth muscle) layers. The large extensibility of the bladder was found to be possible due to folds in the wall (rugae) that provide a mechanism for low resistance flattening without any discernible recruitment of collagen fibers throughout the toe regime. For more extensible bladders, as the loading extended into the transition regime, a gradual coordinated recruitment of collagen fibers between the lamina propria layer and detrusor smooth muscle layer was found. A second important finding was that wall extensibility could be lost by premature recruitment of collagen in the outer wall that cut short the toe region. This change was correlated with age. This work provides, for the first time, a mechanistic understanding of the role of collagen recruitment in determining bladder extensibility and capacitance.

Behavior of Steel-Sheathed Shear Walls Subjected to Seismic and Fire Loads.

PubMed

Hoehler, Matthew S; Smith, Christopher M; Hutchinson, Tara C; Wang, Xiang; Meacham, Brian J; Kamath, Praveen

2017-07-01

A series of tests was conducted on six 2.7 m × 3.7 m shear wall specimens consisting of cold-formed steel framing sheathed on one side with sheet steel adhered to gypsum board and on the opposite side with plain gypsum board. The specimens were subjected to various sequences of simulated seismic shear deformation and fire exposure to study the influence of multi-hazard interactions on the lateral load resistance of the walls. The test program was designed to complement a parallel effort at the University of California, San Diego to investigate a six-story building subjected to earthquakes and fires. The test results reported here indicate that the fire exposure caused a shift in the failure mode of the walls from local buckling of the sheet steel in cases without fire exposure, to global buckling of the sheet steel with an accompanying 35 % reduction in lateral load capacity after the wall had been exposed to fire. This behavior appears to be predictable, which is encouraging from the standpoint of residual lateral load capacity under these severe multi-hazard actions.

Thermal dynamic simulation of wall for building energy efficiency under varied climate environment

NASA Astrophysics Data System (ADS)

Wang, Xuejin; Zhang, Yujin; Hong, Jing

2017-08-01

Aiming at different kind of walls in five cities of different zoning for thermal design, using thermal instantaneous response factors method, the author develops software to calculation air conditioning cooling load temperature, thermal response factors, and periodic response factors. On the basis of the data, the author gives the net work analysis about the influence of dynamic thermal of wall on air-conditioning load and thermal environment in building of different zoning for thermal design regional, and put forward the strategy how to design thermal insulation and heat preservation wall base on dynamic thermal characteristic of wall under different zoning for thermal design regional. And then provide the theory basis and the technical references for the further study on the heat preservation with the insulation are in the service of energy saving wall design. All-year thermal dynamic load simulating and energy consumption analysis for new energy-saving building is very important in building environment. This software will provide the referable scientific foundation for all-year new thermal dynamic load simulation, energy consumption analysis, building environment systems control, carrying through farther research on thermal particularity and general particularity evaluation for new energy -saving walls building. Based on which, we will not only expediently design system of building energy, but also analyze building energy consumption and carry through scientific energy management. The study will provide the referable scientific foundation for carrying through farther research on thermal particularity and general particularity evaluation for new energy saving walls building.

Nonlinear load-deflection behavior of abutment backwalls with varying height and soil density.

DOT National Transportation Integrated Search

2011-12-01

We address the scaling of abutment wall lateral response with wall height and compaction condition through testing and analytical work. The : analytical work was undertaken to develop hyperbolic curves representing the load-deflection response of bac...

Method of measuring material properties of rock in the wall of a borehole

DOEpatents

Overmier, David K.

1985-01-01

To measure the modulus of elasticity of the rock in the wall of a borehole, a plug is cut in the borehole wall. The plug, its base attached to the surrounding rock, acts as a short column in response to applied forces. A loading piston is applied to the top of the plug and compression of the plug is measured as load is increased. Measurement of piston load and plug longitudinal deformation are made to determine the elastic modulus of the plug material. Poisson's ratio can be determined by simultaneous measurements of longitudinal and lateral deformation of the plug in response to loading. To determine shear modulus, the top of the plug is twisted while measurements are taken of torsional deformation.

Method of measuring material properties of rock in the wall of a borehole

DOEpatents

Overmier, D.K.

1984-01-01

To measure the modulus of elasticity of the rock in the wall of a borehole, a plug is cut in the borehole wall. The plug, its base attached to the surrounding rock, acts as a short column in response to applied forces. A loading piston is applied to the top of the plug and compression of the plug is measured as load is increased. Measurements of piston load and plug longitudinal deformation are made to determine the elastic modulus of the plug material. Poisson's ratio can be determined by simultaneous measurements of longitudinal and lateral deformation of the plug in response to loading. To determine shear modulus, the top of the plug is twisted while measurements are taken of torsional deformation.

Conceptual design of divertor and first wall for DEMO-FNS

NASA Astrophysics Data System (ADS)

Sergeev, V. Yu.; Kuteev, B. V.; Bykov, A. S.; Gervash, A. A.; Glazunov, D. A.; Goncharov, P. R.; Dnestrovskij, A. Yu.; Khayrutdinov, R. R.; Klishchenko, A. V.; Lukash, V. E.; Mazul, I. V.; Molchanov, P. A.; Petrov, V. S.; Rozhansky, V. A.; Shpanskiy, Yu. S.; Sivak, A. B.; Skokov, V. G.; Spitsyn, A. V.

2015-11-01

Key issues of design of the divertor and the first wall of DEMO-FNS are presented. A double null closed magnetic configuration was chosen with long external legs and V-shaped corners. The divertor employs a cassette design similar to that of ITER. Water-cooled first wall of the tokamak is made of Be tiles and CuCrZr-stainless steel shells. Lithium injection and circulation technologies are foreseen for protection of plasma facing components. Simulations of thermal loads onto the first wall and divertor plates suggest a possibility to distribute heat loads making them less than 10 MW m-2. Evaluations of sputtering and evaporation of plasma-facing materials suggest that lithium may protect the first wall. To prevent Be erosion at the outer divertor plates either the full detached divertor operation or arrangement of the renewal lithium flow on targets should be implemented. Test bed experiments on the Tsefey-M facility with the first wall mockup coated by Ве tiles and cooled by water are presented. The temperature of the surface of tiles reached 280-300 °С at 5 MW m-2 and 600-650 °С at 10.5 MW m-2. The mockup successfully withstood 1000 cycles with the lower thermal loading and 100 cycles with higher thermal loading.

Failure Behavior of Elbows with Local Wall Thinning

NASA Astrophysics Data System (ADS)

Lee, Sung-Ho; Lee, Jeong-Keun; Park, Jai-Hak

Wall thinning defect due to corrosion is one of major aging phenomena in carbon steel pipes in most plant industries, and it results in reducing load carrying capacity of the piping components. A failure test system was set up for real scale elbows containing various simulated wall thinning defects, and monotonic in-plane bending tests were performed under internal pressure to find out the failure behavior of them. The failure behavior of wall-thinned elbows was characterized by the circumferential angle of thinned region and the loading conditions to the piping system.

Aviation Urban Operations Multiservice Procedures for Aviation Urban Operations FM 3-06/1, MCRP 3-35/3A, NTTP 3-01.04, and AFTP(l)3-2.29

DTIC Science & Technology

2001-04-01

construction, numerous non load- bearing walls, and large windows. Commercial offices and high rise buildings are generally framed with steel girders...Mass buildings are built so exterior walls bear the weight of the structure. The walls of mass structures are usually thick and constructed of...buildings are similar in size to Type 5 office buildings, but with less glass and with load- bearing reinforced concrete walls. They offer greater protection

Erosion simulation of first wall beryllium armour under ITER transient heat loads

NASA Astrophysics Data System (ADS)

Bazylev, B.; Janeschitz, G.; Landman, I.; Pestchanyi, S.; Loarte, A.

2009-04-01

The beryllium is foreseen as plasma facing armour for the first wall in the ITER in form of Be-clad blanket modules in macrobrush design with brush size about 8-10 cm. In ITER significant heat loads during transient events (TE) are expected at the main chamber wall that may leads to the essential damage of the Be armour. The main mechanisms of metallic target damage remain surface melting and melt motion erosion, which determines the lifetime of the plasma facing components. Melting thresholds and melt layer depth of the Be armour under transient loads are estimated for different temperatures of the bulk Be and different shapes of transient loads. The melt motion damages of Be macrobrush armour caused by the tangential friction force and the Lorentz force are analyzed for bulk Be and different sizes of Be-brushes. The damage of FW under radiative loads arising during mitigated disruptions is numerically simulated.

High pressure, energy, and impulse loading of the wall in a 1-GJ Laboratory Microfusion Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrach, R.J.

1989-07-24

A proposed Laboratory Microfusion Facility (LMF) must be able to withstand repeated, low-repetition-rate fusion explosions at the 1-GJ (one-quarter ton) yield level. The energy release will occur at the center of a chamber only a few meters in radius, subjecting the interior or first wall to severe levels of temperature, pressure, and impulse. We show by theory and computation that the wall loading can be ameliorated by interposing a spherical shell of low-Z material between the fuel and the wall. This sacrificial shield converts the source energy components that are most damaging to the wall (soft x-rays and fast ions)more » to more benign plasma kinetic energy from the vaporized shield, and stretches the time duration over which this energy is delivered to the wall from nanoseconds to microseconds. Numerical calculations emphasize thin, volleyball-sized plastic shields, and much thicker ones of frozen nitrogen. Wall shielding criteria of small (or no) amount of surface ablation, low impulse and pressure loading, minimal shrapnel danger, small expense, and convenience in handling all favor the thin plastic shields. 7 refs., 4 figs.« less

Investigation on Wall Panel Sandwiched With Lightweight Concrete

NASA Astrophysics Data System (ADS)

Lakshmikandhan, K. N.; Harshavardhan, B. S.; Prabakar, J.; Saibabu, S.

2017-08-01

The rapid population growth and urbanization have made a massive demand for the shelter and construction materials. Masonry walls are the major component in the housing sector and it has brittle characteristics and exhibit poor performance against the uncertain loads. Further, the structure requires heavier sections for carrying the dead weight of masonry walls. The present investigations are carried out to develop a simple, lightweight and cost effective technology for replacing the existing wall systems. The lightweight concrete is developed for the construction of sandwich wall panel. The EPS (Expanded Polystyrene) beads of 3 mm diameter size are mixed with concrete and developed a lightweight concrete with a density 9 kN/m3. The lightweight sandwich panel is cast with a lightweight concrete inner core and ferrocement outer skins. This lightweight wall panel is tested for in-plane compression loading. A nonlinear finite element analysis with damaged plasticity model is carried out with both material and geometrical nonlinearities. The experimental and analytical results were compared. The finite element study predicted the ultimate load carrying capacity of the sandwich panel with reasonable accuracy. The present study showed that the lightweight concrete is well suitable for the lightweight sandwich wall panels.

In vitro assessment of retention and resistance failure loads of two preparation designs for maxillary anterior teeth.

PubMed

Bintivanou, Aimilia; Pissiotis, Argirios; Michalakis, Konstantinos

2017-04-01

Parallel labiolingual walls and the preservation of the cingulum in anterior tooth preparations have been advocated. However, their contribution to retention and resistance form has not been evaluated. The purpose of this in vitro study was to evaluate the retention and resistance failure loads of 2 preparation designs for maxillary anterior teeth. Forty metal restorations were fabricated and paired with 40 cobalt-chromium prepared tooth analogs. Twenty of the specimens had parallel buccolingual walls at the cervical part (group PBLW; the control group), whereas the remaining 20 had converging buccolingual walls (group CBLW; the experimental group). The restorations were cemented to the tooth analogs with a resin-modified glass ionomer luting agent. Ten specimens from each group were subjected to tensile loading with a universal testing machine; the rest were subjected to compression loading until failure. Descriptive statistics and the independent t test (α=.05) were used to determine the effect of failure loads in the tested groups. The independent t test revealed statistically significant differences between the tested groups in tensile loading (P<.001) and in compressive loading (P<.001). The PBLW group presented a higher tensile failure load than the CBLW. On the contrary, the PBLW group presented a smaller compression failure load than the CBLW. Parallelism of the buccolingual axial walls in anterior maxillary teeth increased the retention form but decreased the resistance form. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations.

PubMed

Liu, Wenchao; Cao, Wanlin; Zhang, Jianwei; Qiao, Qiyun; Ma, Heng

2016-03-02

The seismic performance of recycled aggregate concrete (RAC) composite shear walls with different expandable polystyrene (EPS) configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC) protective layer (EPS modules as the external insulation layer), and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls.

Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations

PubMed Central

Liu, Wenchao; Cao, Wanlin; Zhang, Jianwei; Qiao, Qiyun; Ma, Heng

2016-01-01

The seismic performance of recycled aggregate concrete (RAC) composite shear walls with different expandable polystyrene (EPS) configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC) protective layer (EPS modules as the external insulation layer), and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls. PMID:28773274

Pressurizer tank upper support

DOEpatents

Baker, Tod H.; Ott, Howard L.

1994-01-01

A pressurizer tank in a pressurized water nuclear reactor is mounted between structural walls of the reactor on a substructure of the reactor, the tank extending upwardly from the substructure. For bearing lateral loads such as seismic shocks, a girder substantially encircles the pressurizer tank at a space above the substructure and is coupled to the structural walls via opposed sway struts. Each sway strut is attached at one end to the girder and at an opposite end to one of the structural walls, and the sway struts are oriented substantially horizontally in pairs aligned substantially along tangents to the wall of the circular tank. Preferably, eight sway struts attach to the girder at 90.degree. intervals. A compartment encloses the pressurizer tank and forms the structural wall. The sway struts attach to corners of the compartment for maximum stiffness and load bearing capacity. A valve support frame carrying the relief/discharge piping and valves of an automatic depressurization arrangement is fixed to the girder, whereby lateral loads on the relief/discharge piping are coupled directly to the compartment rather than through any portion of the pressurizer tank. Thermal insulation for the valve support frame prevents thermal loading of the piping and valves. The girder is shimmed to define a gap for reducing thermal transfer, and the girder is free to move vertically relative to the compartment walls, for accommodating dimensional variation of the pressurizer tank with changes in temperature and pressure.

Behaviour of Masonry Walls under Horizontal Shear in Mining Areas

NASA Astrophysics Data System (ADS)

Kadela, Marta; Bartoszek, Marek; Fedorowicz, Jan

2017-12-01

The paper discusses behaviour of masonry walls constructed with small-sized elements under the effects of mining activity. It presents some mechanisms of damage occurring in such structures, its forms in real life and the behaviour of large fragments of masonry walls subjected to specific loads in FEM computational models. It offers a constitutive material model, which enables numerical analyses and monitoring of the behaviour of numerical models as regards elastic-plastic performance of the material, with consideration of its degradation. Results from the numerical analyses are discussed for isolated fragments of the wall subjected to horizontal shear, with consideration of degradation, impact of imposed vertical load as well as the effect of weakening of the wall, which was achieved by introducing openings in it, on the performance and deformation of the wall.

Some considerations on instability of combined loaded thin-walled tubes with a crack

NASA Astrophysics Data System (ADS)

Shariati, M.; Akbarpour, A.

2016-05-01

Instability of a thin-walled stainless steel tube with a crack-shaped defect under combined loading is studied in this paper. Furthermore, the effects of the tube length, crack orientation, and crack length on the buckling behavior of tubes are investigated. The behavior of tubes subjected to combined is analyzed by using the finite element method (by Abaqus software). For cracked tubes with a fixed thickness, the buckling load decreases as the tube length and the ratio of the tube length to its diameter increase. Moreover, the buckling load of cracked tubes under combined loading also decreases with increasing crack length.

Ported jacket for use in deformation measurement apparatus

DOEpatents

Wagner, L.A.; Senseny, P.E.; Mellegard, K.D.; Olsberg, S.B.

1990-03-06

A device for allowing deformation measurement of a jacketed specimen when the specimen is loaded includes an elastomeric specimen container or jacket surrounding a specimen while the specimen is being loaded by a test apparatus. The specimen jacket wall is compressible, and the wall follows and allows deformation of the specimen. The jacket wall of compressible material is provided with at least one opening and a thin layer or shim of substantially non-compressible (metal) material which covers and seals this opening. An extensometer is then positioned with its specimen engaging contact members engaging the substantially non-compressible material to measure the deformation of the specimen when the specimen is loaded, without compressibility effects of the jacket. 9 figs.

Experimental and numerical investigation of a RC wall loaded by snow-like avalanche pressure signal

NASA Astrophysics Data System (ADS)

Ousset, Isabelle; Bertrand, David; Brun, Michaël; Limam, Ali; Naaïm, Mohamed

2013-04-01

Nowadays, civil engineering structures exposed to snow avalanches are mostly designed considering static loadings involving large safety factors. These latters highlight the lack of knowledge about the effects of the loading generated by a snow flow, and generally lead to oversize the civil structure. Indeed, the transient nature of the loading signal and also the composition of the snow flow can generate dynamic phenomena which cannot be taken into account considering only static loadings. The case of the avalanche of the Taconnaz (France), which occurred in 1999 and where important parts of the defense structure were destroyed, showed that static design approaches can lead to underestimate the potential effect of the snow flow. Thus, in order to give some new insights about this issue, the effect of the temporal variations of the snow loading on the mechanical behavior of an idealized defense structure is investigated. Therefore, a reinforced concrete (RC) wall with a L-like shape has been considered which is supposed to represent a part of the defense structure situated in Taconnaz. Static pushover tests, carried out in laboratory conditions on 1/6 scale physical model of the RC structure, allowed obtaining the capacity of the tested structure (Berthet-Rambaud et al. (2007)). Finite Element (FE) models have been developed and calibrated from the previous experimental data. The FE approach allows simulating the dynamic mechanical response of the structure. The effect of the transient nature of the loading of the avalanche has been explored applying out-of-plan dynamic loadings on the RC wall. In order to be as close as possible of a "field" snow avalanche, the imposed time evolution of the loading has been generated from in situ measurements recorded at the French experimental site "le col du Lautaret" (Thibert et al. (2008)). The RC mechanical behaviour has been described by four nonlinear constitutive laws. The four behaviour laws are compared and analyzed for specific loading situations. Next, the influences of typical parameters characterizing the avalanche loading signal are proposed. In particular, a special focused is presented on the effect of the loading rate. Finally, the vulnerability of the RC wall is studied in a reliability framework. Damage index are proposed and the probability of failure of the RC wall is derived. These relations might be useful for risk analysis.

Analysis of Brick Masonry Wall using Applied Element Method

NASA Astrophysics Data System (ADS)

Lincy Christy, D.; Madhavan Pillai, T. M.; Nagarajan, Praveen

2018-03-01

The Applied Element Method (AEM) is a versatile tool for structural analysis. Analysis is done by discretising the structure as in the case of Finite Element Method (FEM). In AEM, elements are connected by a set of normal and shear springs instead of nodes. AEM is extensively used for the analysis of brittle materials. Brick masonry wall can be effectively analyzed in the frame of AEM. The composite nature of masonry wall can be easily modelled using springs. The brick springs and mortar springs are assumed to be connected in series. The brick masonry wall is analyzed and failure load is determined for different loading cases. The results were used to find the best aspect ratio of brick to strengthen brick masonry wall.

Seismic performance of geosynthetic-soil retaining wall structures

NASA Astrophysics Data System (ADS)

Zarnani, Saman

Vertical inclusions of expanded polystyrene (EPS) placed behind rigid retaining walls were investigated as geofoam seismic buffers to reduce earthquake-induced loads. A numerical model was developed using the program FLAC and the model validated against 1-g shaking table test results of EPS geofoam seismic buffer models. Two constitutive models for the component materials were examined: elastic-perfectly plastic with Mohr-Coulomb (M-C) failure criterion and non-linear hysteresis damping model with equivalent linear method (ELM) approach. It was judged that the M-C model was sufficiently accurate for practical purposes. The mechanical property of interest to attenuate dynamic loads using a seismic buffer was the buffer stiffness defined as K = E/t (E = buffer elastic modulus, t = buffer thickness). For the range of parameters investigated in this study, K ≤50 MN/m3 was observed to be the practical range for the optimal design of these systems. Parametric numerical analyses were performed to generate design charts that can be used for the preliminary design of these systems. A new high capacity shaking table facility was constructed at RMC that can be used to study the seismic performance of earth structures. Reduced-scale models of geosynthetic reinforced soil (GRS) walls were built on this shaking table and then subjected to simulated earthquake loading conditions. In some shaking table tests, combined use of EPS geofoam and horizontal geosynthetic reinforcement layers was investigated. Numerical models were developed using program FLAC together with ELM and M-C constitutive models. Physical and numerical results were compared against predicted values using analysis methods found in the journal literature and in current North American design guidelines. The comparison shows that current Mononobe-Okabe (M-O) based analysis methods could not consistently satisfactorily predict measured reinforcement connection load distributions at all elevations under both static and dynamic loading conditions. The results from GRS model wall tests with combined EPS geofoam and geosynthetic reinforcement layers show that the inclusion of a EPS geofoam layer behind the GRS wall face can reduce earth loads acting on the wall facing to values well below those recorded for conventional GRS wall model configurations.

Interaction between drilled shaft and mechanically stabilized earth (MSE) wall : project summary.

DOT National Transportation Integrated Search

2015-08-31

Drilled shafts are being constructed within the reinforced zone of mechanically stabilized earth (MSE) walls (Figure 1). The drilled shafts may be subjected to horizontal loads and push against the front of the wall. Distress of MSE wall panels has b...

Pressurizer tank upper support

DOEpatents

Baker, T.H.; Ott, H.L.

1994-01-11

A pressurizer tank in a pressurized water nuclear reactor is mounted between structural walls of the reactor on a substructure of the reactor, the tank extending upwardly from the substructure. For bearing lateral loads such as seismic shocks, a girder substantially encircles the pressurizer tank at a space above the substructure and is coupled to the structural walls via opposed sway struts. Each sway strut is attached at one end to the girder and at an opposite end to one of the structural walls, and the sway struts are oriented substantially horizontally in pairs aligned substantially along tangents to the wall of the circular tank. Preferably, eight sway struts attach to the girder at 90[degree] intervals. A compartment encloses the pressurizer tank and forms the structural wall. The sway struts attach to corners of the compartment for maximum stiffness and load bearing capacity. A valve support frame carrying the relief/discharge piping and valves of an automatic depressurization arrangement is fixed to the girder, whereby lateral loads on the relief/discharge piping are coupled directly to the compartment rather than through any portion of the pressurizer tank. Thermal insulation for the valve support frame prevents thermal loading of the piping and valves. The girder is shimmed to define a gap for reducing thermal transfer, and the girder is free to move vertically relative to the compartment walls, for accommodating dimensional variation of the pressurizer tank with changes in temperature and pressure. 10 figures.

Characterization of frictional interference in closely-spaced reinforcements in MSE walls.

DOT National Transportation Integrated Search

2014-09-01

This research addresses one of several knowledge gaps in the understanding of tall MSE wall behavior: prediction of reinforcement loads impacted by frictional interference of closely-spaced reinforcements associated with tall walls.

Contribution of Gypsum Wallboard to Racking Resistance of Light-Frame Walls.

DTIC Science & Technology

1983-12-01

contribution to wall ’ ~sheathing to the framing members, and axial loads on racking resistance. Such information may lead to more diagonal braces used...wallboard was centered over the joint and fastened to the narrow face of the wood pieces using 1-1/4-inch drywall nails . Two nails were used to fasten...pulled apart placing a lateral load on the nailed connection, similar to the connector loading incurred at the nailed connection along the bottom plate of

23. BUILDING NO. 452, ORDNANCE FACILITY (BAG CHARGE FILLING PLANT), ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. BUILDING NO. 452, ORDNANCE FACILITY (BAG CHARGE FILLING PLANT), INTERIOR, LOOKING SOUTH DOWN CENTRAL CORRIDOR. NOTE BINS IN WALLS ON EITHER SIDE OF CORRIDOR, USED FOR PASSING EXPLOSIVES AND LOADED ITEMS TO SIEVING ROOMS BEYOND WALLS. - Picatinny Arsenal, 400 Area, Gun Bag Loading District, State Route 15 near I-80, Dover, Morris County, NJ

Modeling Force Transfer around Openings in Wood-Frame Shear Walls

Treesearch

Minghao Li; Frank Lam; Borjen Yeh; Tom Skaggs; Doug Rammer; James Wacker

2012-01-01

This paper presented a modeling study on force transfer around openings (FTAO) in wood-frame shear walls detailed for FTAO. To understand the load transfer in the walls, this study used a finite-element model WALL2D, which is able to model individual wall components, including framing members, sheathing panels, oriented panel-frame nailed connections, framing...

24 CFR 3280.302 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Body and Frame Construction Requirements.... Loads: (1) Dead load: means the weight of all permanent construction including walls, floors, roof... occupancy of the manufactured home, including wind load and snow load, but not including dead load. (3) Wind...

24 CFR 3280.302 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Body and Frame Construction Requirements.... Loads: (1) Dead load: means the weight of all permanent construction including walls, floors, roof... occupancy of the manufactured home, including wind load and snow load, but not including dead load. (3) Wind...

24 CFR 3280.302 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Body and Frame Construction Requirements.... Loads: (1) Dead load: means the weight of all permanent construction including walls, floors, roof... occupancy of the manufactured home, including wind load and snow load, but not including dead load. (3) Wind...

24 CFR 3280.302 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... DEVELOPMENT MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS Body and Frame Construction Requirements.... Loads: (1) Dead load: means the weight of all permanent construction including walls, floors, roof... occupancy of the manufactured home, including wind load and snow load, but not including dead load. (3) Wind...

Double wall vacuum tubing and method of manufacture

DOEpatents

Stahl, Charles R.; Gibson, Michael A.; Knudsen, Christian W.

1989-01-01

An evacuated double wall tubing is shown together with a method for the manufacture of such tubing which includes providing a first pipe of predetermined larger diameter and a second pipe having an O.D. substantially smaller than the I.D. of the first pipe. An evacuation opening is then in the first pipe. The second pipe is inserted inside the first pipe with an annular space therebetween. The pipes are welded together at one end. A stretching tool is secured to the other end of the second pipe after welding. The second pipe is then prestressed mechanically with the stretching tool an amount sufficient to prevent substantial buckling of the second pipe under normal operating conditions of the double wall pipe. The other ends of the first pipe and the prestressed second pipe are welded together, preferably by explosion welding, without the introduction of mechanical spacers between the pipes. The annulus between the pipes is evacuated through the evacuation opening, and the evacuation opening is finally sealed. The first pipe is preferably of steel and the second pipe is preferably of titanium. The pipes may be of a size and wall thickness sufficient for the double wall pipe to be structurally load bearing or may be of a size and wall thickness insufficient for the double wall pipe to be structurally load bearing, and the double wall pipe positioned with a sliding fit inside a third pipe of a load-bearing size.

Time-varying wall stress: an index of ventricular vascular coupling.

PubMed

Dell'Italia, L J; Blackwell, G G; Thorn, B T; Pearce, D J; Bishop, S P; Pohost, G M

1992-08-01

Previous work in the isolated heart and intact circulation has suggested that the relationship between wall stress and time during left ventricular (LV) ejection is linear and that the slope, which will be referred to as time-varying wall stress, increases in response to augmentation in afterload. However, the etiology of the increase in slope has not been determined in an intact animal. Magnetic resonance imaging coupled with high-fidelity LV pressure measurement using a nonferrous catheter-tip manometer generates a detailed assessment of wall stress in an animal model where the thorax and pericardium have never been disturbed. Accordingly, six anesthetized dogs were studied during autonomic blockade with atropine and propranolol during angiotensin infusion, producing three widely disparate left ventricular systolic pressures (87 +/- 7 vs. 124 +/- 13 vs. 152 +/- 10 mmHg, P less than 0.001). Time-varying wall stress did not change from low to medium load (-42.4 +/- 9.5 to -27.3 +/- 22.3 g.cm-2.ms-1) but increased significantly at high load (-21.7 +/- 14.9 g.cm-2.ms-1, P less than 0.05). Analysis of the relative contribution of pressure, chamber radius, wall thickness, and long-axis dimension to the changes in time-varying wall stress demonstrated only the pressure component to change its relative contribution at medium (P less than 0.001) and high load (P less than 0.001). Therefore, we conclude that the increase in time-varying wall stress results from augmentation of pressure in the latter one-half of systole that is incompletely offset by shortening and wall thickening.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of various descent trajectories for a hypersonic-cruise, cold-wall research airplane

NASA Technical Reports Server (NTRS)

Lawing, P. L.

1975-01-01

The probable descent operating conditions for a hypersonic air-breathing research airplane were examined. Descents selected were cruise angle of attack, high dynamic pressure, high lift coefficient, turns, and descents with drag brakes. The descents were parametrically exercised and compared from the standpoint of cold-wall (367 K) aircraft heat load. The descent parameters compared were total heat load, peak heating rate, time to landing, time to end of heat pulse, and range. Trends in total heat load as a function of cruise Mach number, cruise dynamic pressure, angle-of-attack limitation, pull-up g-load, heading angle, and drag-brake size are presented.

Non-equilibrium phase behavior and friction of confined molecular films under shear: A non-equilibrium molecular dynamics study.

PubMed

Maćkowiak, Sz; Heyes, D M; Dini, D; Brańka, A C

2016-10-28

The phase behavior of a confined liquid at high pressure and shear rate, such as is found in elastohydrodynamic lubrication, can influence the traction characteristics in machine operation. Generic aspects of this behavior are investigated here using Non-equilibrium Molecular Dynamics (NEMD) simulations of confined Lennard-Jones (LJ) films under load with a recently proposed wall-driven shearing method without wall atom tethering [C. Gattinoni et al., Phys. Rev. E 90, 043302 (2014)]. The focus is on thick films in which the nonequilibrium phases formed in the confined region impact on the traction properties. The nonequilibrium phase and tribological diagrams are mapped out in detail as a function of load, wall sliding speed, and atomic scale surface roughness, which is shown can have a significant effect. The transition between these phases is typically not sharp as the external conditions are varied. The magnitude of the friction coefficient depends strongly on the nonequilibrium phase adopted by the confined region of molecules, and in general does not follow the classical friction relations between macroscopic bodies, e.g., the frictional force can decrease with increasing load in the Plug-Slip (PS) region of the phase diagram owing to structural changes induced in the confined film. The friction coefficient can be extremely low (∼0.01) in the PS region as a result of incommensurate alignment between a (100) face-centered cubic wall plane and reconstructed (111) layers of the confined region near the wall. It is possible to exploit hysteresis to retain low friction PS states well into the central localization high wall speed region of the phase diagram. Stick-slip behavior due to periodic in-plane melting of layers in the confined region and subsequent annealing is observed at low wall speeds and moderate external loads. At intermediate wall speeds and pressure values (at least) the friction coefficient decreases with increasing well depth of the LJ potential between the wall atoms, but increases when the attractive part of the potential between wall atoms and confined molecules is made larger.

The role of wall calcium in the extension of cell walls of soybean hypocotyls

NASA Technical Reports Server (NTRS)

Virk, S. S.; Cleland, R. E.

1990-01-01

Calcium crosslinks are load-bearing bonds in soybean (Glycine max (L.) Merr.) hypocotyl cell walls, but they are not the same load-bearing bonds that are broken during acid-mediated cell elongation. This conclusion is reached by studying the relationship between wall calcium, pH and the facilitated creep of frozen-thawed soybean hypocotyl sections. Supporting data include the following observations: 1) 2-[(2-bis-[carboxymethyl]amino-5-methylphenoxy)methyl]-6-methoxy-8-bis[car boxymethyl]aminoquinoline (Quin 2) and ethylene glycol-bis(2-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) caused only limited facilitated creep as compared with acid, despite removal of comparable or larger amounts of wall calcium; 2) the pH-response curves for calcium removal and acid-facilitated creep were different; 3) reversible acid-extension occurred even after removal of almost all wall calcium with Quin 2; and 4) growth of abraded sections did not involve a proportional loss of wall calcium. Removal of wall calcium, however, increased the capacity of the walls to undergo acid-facilitated creep. These data indicate that breakage of calcium crosslinks is not a major mechanism of cell-wall loosening in soybean hypocotyl tissues.

Plasma Chamber and First Wall of the Ignitor Experiment^*

NASA Astrophysics Data System (ADS)

Cucchiaro, A.; Coppi, B.; Bianchi, A.; Lucca, F.

2005-10-01

The new designs of the Plasma Chamber (PC) and of the First Wall (FW) system are based on updated scenarios for vertical plasma disruption (VDE) as well as estimates for the maximum thermal wall loadings at ignition. The PC wall thickness has been optimized to reduce the deformation during the worst disruption event without sacrificing the dimensions of the plasma column. A non linear dynamic analysis of the PC has been performed on a 360^o model of it, taking into account possible toroidal asymmetries of the halo current. Radial EM loads obtained by scaling JET measurements have been also considered. The low-cycle fatigue analysis confirms that the PC is able to meet a lifetime of few thousand cycles for the most extreme combinations of magnetic fields and plasma currents. The FW, made of Molybdenum (TZM) tiles covering the entire inner surface of the PC, has been designed to withstand thermal and EM loads, both under normal operating conditions and in case of disruption. Detailed elasto-plastic structural analyses of the most (EM) loaded tile-carriers show that these are compatible with the adopted fabrication requirements. ^*Sponsored in part by ENEA of Italy and by the U.S. DOE.

Biaxial fatigue loading of notched composites

NASA Technical Reports Server (NTRS)

Francis, P. H.; Walrath, D. E.; Sims, D. F.; Weed, D. N.

1977-01-01

Thin-walled, 2.54-cm diameter tubular specimens of graphite/epoxy were fatigue cycled in combinations of axial, torsional, and internal pressure loading. Two different four-ply layup configurations were tested: (0-90)s and (+ or- 45)s; each tube contained a 0.48-cm diameter circular hole penetrating one wall midway along the tube length. S-N curves were developed to characterize fatigue behavior under pure axial, torsional, or internal pressure loading, as well as combined loading fatigue. A theory was developed based on a plane stress model which enabled the S-N curve for combined stress states to be predicted from the S-N data for the uniaxial loading modes. Correlation of the theory with the experimental data proved to be remarkably good.

Cost optimization of reinforced concrete cantilever retaining walls under seismic loading using a biogeography-based optimization algorithm with Levy flights

NASA Astrophysics Data System (ADS)

Aydogdu, Ibrahim

2017-03-01

In this article, a new version of a biogeography-based optimization algorithm with Levy flight distribution (LFBBO) is introduced and used for the optimum design of reinforced concrete cantilever retaining walls under seismic loading. The cost of the wall is taken as an objective function, which is minimized under the constraints implemented by the American Concrete Institute (ACI 318-05) design code and geometric limitations. The influence of peak ground acceleration (PGA) on optimal cost is also investigated. The solution of the problem is attained by the LFBBO algorithm, which is developed by adding Levy flight distribution to the mutation part of the biogeography-based optimization (BBO) algorithm. Five design examples, of which two are used in literature studies, are optimized in the study. The results are compared to test the performance of the LFBBO and BBO algorithms, to determine the influence of the seismic load and PGA on the optimal cost of the wall.

Investigation of the seismic resistance of interior building partitions, phase 1

NASA Astrophysics Data System (ADS)

Anderson, R. W.; Yee, Y. C.; Savulian, G.; Barclay, B.; Lee, G.

1981-02-01

The effective participation of wood-framed interior shear wall partitions when determining the ultimate resistance capacity of two- and three-story masonry apartment buildings to seismic loading was investigated. Load vs. deflection tests were performed on 8 ft by 8 ft wall panel specimens constructed of four different facing materials, including wood lath and plaster, gypsum lath and plaster, and gypsum wallboard with joints placed either horizontally or vertically. The wood lath and plaster construction is found to be significantly stronger and stiffer than the other three specimens. Analyses of the test panels using finite element methods to predict their static resistance characteristics indicates that the facing material acts as the primary shear-resisting structural element. Resistance of shear wall partitions to lateral loads was assessed.

Effect of load eccentricity on the buckling of thin-walled laminated C-columns

NASA Astrophysics Data System (ADS)

Wysmulski, Pawel; Teter, Andrzej; Debski, Hubert

2018-01-01

The study investigates the behaviour of short, thin-walled laminated C-columns under eccentric compression. The tested columns are simple-supported. The effect of load inaccuracy on the critical and post-critical (local buckling) states is examined. A numerical analysis by the finite element method and experimental tests on a test stand are performed. The samples were produced from a carbon-epoxy prepreg by the autoclave technique. The experimental tests rest on the assumption that compressive loads are 1.5 higher than the theoretical critical force. Numerical modelling is performed using the commercial software package ABAQUS®. The critical load is determined by solving an eigen problem using the Subspace algorithm. The experimental critical loads are determined based on post-buckling paths. The numerical and experimental results show high agreement, thus demonstrating a significant effect of load inaccuracy on the critical load corresponding to the column's local buckling.

Buckling test of a 3-meter-diameter corrugated graphite-epoxy ring-stiffened cylinder

NASA Technical Reports Server (NTRS)

Davis, R. C.

1982-01-01

A three m diameter by three m long corrugated cylindrical shell with external stiffening rings was tested to failure by buckling. The corrugation geometry for the graphite epoxy composite cylinder wall was optimized to withstand a compressive load producing an ultimate load intensity of 157.6 kN/m without buckling. The test method used to produce the design load intensity was to mount the specimen as a cantilevered cylinder and apply a pure bending moment to the end. A load introduction problem with the specimen was solved by using the BOSOR 4 shell of revolution computer code to analyze the shell and attached loading fixtures. The cylinder test loading achieved was 101 percent of design ultimate, and the resulting mass per unit of shell wall area was 1.96 kg/sq m.

Computer design synthesis of a below knee-Syme prosthesis

NASA Technical Reports Server (NTRS)

Elangovan, P. T.; Ghista, D. N.; Alwar, R. S.

1979-01-01

A detailed design synthesis analysis of the BK Syme prosthesis is provided, to determine the socket's cutout orientation size and shape, cutout fillet shape, socket wall thickness distribution and the reinforced fiber distribution in the socket wall, for a minimally stressed structurally safe lightweight prosthesis. For analysis purposes, the most adverse socket loading is obtained at the push-off stage of gait; this loading is idealized as an axial in-plane loading on the bottom edge of the circular cylindrical socket shell whose top edge is considered fixed. Finite element stress analysis of the socket shell (with uniform and graded wall thickness) are performed for various orientations of the cutout and for various types of corner fillets. A lateral cutout with a streamline fillet is recommended. The wall material (i.e., thickness) distribution is determined so as to minimize the stresses, while ensuring that the wall material's stress limits are not exceeded. For such a maximally stressed lightweight socket shell, the panels in the neighborhood of the cutout are checked to ensure that they do not buckle under their acquired stresses. A fiber-reinforced laminated composite socket shell is also analyzed in order to recommend optimum variables in orientations and densities of reinforcing fibers.

Effective load transfer by a chromium carbide nanostructure in a multi-walled carbon nanotube/copper matrix composite

NASA Astrophysics Data System (ADS)

Cho, Seungchan; Kikuchi, Keiko; Kawasaki, Akira; Kwon, Hansang; Kim, Yangdo

2012-08-01

Multi-walled carbon nanotube (MWCNT) reinforced copper (Cu) matrix composites, which exhibit chromium (Cr) carbide nanostructures at the MWCNT/Cu interface, were prepared through a carbide formation using CuCr alloy powder. The fully densified and oriented MWCNTs dispersed throughout the composites were prepared using spark plasma sintering (SPS) followed by hot extrusion. The tensile strengths of the MWCNT/CuCr composites increased with increasing MWCNTs content, while the tensile strength of MWCNT/Cu composite decreased from that of monolithic Cu. The enhanced tensile strength of the MWCNT/CuCr composites is a result of possible load-transfer mechanisms of the interfacial Cr carbide nanostructures. The multi-wall failure of MWCNTs observed in the fracture surface of the MWCNT/CuCr composites indicates an improvement in the load-bearing capacity of the MWCNTs. This result shows that the Cr carbide nanostructures effectively transferred the tensile load to the MWCNTs during fracture through carbide nanostructure formation in the MWCNT/Cu composite.

Experimental study on lateral strength of wall-slab joint subjected to lateral cyclic load

NASA Astrophysics Data System (ADS)

Masrom, Mohd Asha'ari; Mohamad, Mohd Elfie; Hamid, Nor Hayati Abdul; Yusuff, Amer

2017-10-01

Tunnel form building has been utilised in building construction since 1960 in Malaysia. This method of construction has been applied extensively in the construction of high rise residential house (multistory building) such as condominium and apartment. Most of the tunnel form buildings have been designed according to British standard (BS) whereby there is no provision for seismic loading. The high-rise tunnel form buildings are vulnerable to seismic loading. The connections between slab and shear walls in the tunnel-form building constitute an essential link in the lateral load resisting mechanism. Malaysia is undergoing a shifting process from BS code to Eurocode (EC) for building construction since the country has realised the safety threats of earthquake. Hence, this study is intended to compare the performance of the interior wall slab joint for a tunnel form structure designed based on Euro and British codes. The experiment included a full scale test of the wall slab joint sub-assemblages under reversible lateral cyclic loading. Two sub-assemblage specimens of the wall slab joint were designed and constructed based on both codes. Each specimen was tested using lateral displacement control (drift control). The specimen designed by using Eurocode was found could survive up to 3.0% drift while BS specimen could last to 1.5% drift. The analysis results indicated that the BS specimen was governed by brittle failure modes with Ductility Class Low (DCL) while the EC specimen behaved in a ductile manner with Ductility Class Medium (DCM). The low ductility recorded in BS specimen was resulted from insufficient reinforcement provided in the BS code specimen. Consequently, the BS specimen could not absorb energy efficiently (low energy dissipation) and further sustain under inelastic deformation.

Biaxial fatigue loading of notched composites

NASA Technical Reports Server (NTRS)

Francis, P. H.; Walrath, D. E.; Sims, D. F.; Weed, D. N.

1977-01-01

Thin walled, 2.54-cm (1-in.) diameter tubular specimens of T300/934 graphite/epoxy were fabricated and fatigue cycled in combinations of axial, torsional, and internal pressure loading. Two different four-ply layup configurations were tested: (0/90)S and (+ or - 45)S; all tubes contained a 0.48-cm (3/16-in.) diameter circular hole penetrating one wall midway along the tube length. S-N curves were developed to characterize fatigue behavior under pure axial, torsional, or internal pressure loading, as well as combined loading fatigue. A theory was developed based on the Hill plane stress model which enabled the S-N curve for combined stress states to be predicted from the S-N data for the uniaxial loading modes. Correlation of the theory with the experimental data proved to be remarkably good.

An Applied Method for Predicting the Load-Carrying Capacity in Compression of Thin-Wall Composite Structures with Impact Damage

NASA Astrophysics Data System (ADS)

Mitrofanov, O.; Pavelko, I.; Varickis, S.; Vagele, A.

2018-03-01

The necessity for considering both strength criteria and postbuckling effects in calculating the load-carrying capacity in compression of thin-wall composite structures with impact damage is substantiated. An original applied method ensuring solution of these problems with an accuracy sufficient for practical design tasks is developed. The main advantage of the method is its applicability in terms of computing resources and the set of initial data required. The results of application of the method to solution of the problem of compression of fragments of thin-wall honeycomb panel damaged by impacts of various energies are presented. After a comparison of calculation results with experimental data, a working algorithm for calculating the reduction in the load-carrying capacity of a composite object with impact damage is adopted.

Cylindrical Shells Made of Stainless Steel - Investigation of Postbuckling

NASA Astrophysics Data System (ADS)

Stehr, Sebastian; Stranghöner, Natalie

2017-06-01

The relevant load case of open thin-walled shells is often wind loading during construction. Because of the missing stabilization effect of the roof they show a very high sensitivity to buckling which results into higher wall thicknesses. As part of the European RFCS research project BiogaSS the Institute for Metal and Lightweight Structures of the University of Duisburg-Essen carried out investigations on open thin-walled tanks made of austenitic and duplex stainless steels under wind load to study a possible economic advantage which might be gained from the consideration of the elastic postbuckling behaviour. This contribution presents not only experimental and numerical results but also first recommendations regarding the range of possible buckling reduction factors which might be incorporated in future revisions of EN 1993-1-6 and EN 1993-4-2.

Lateral resistance of piles near vertical MSE abutment walls.

DOT National Transportation Integrated Search

2013-03-01

Full scale lateral load tests were performed on eight piles located at various distances behind MSE walls. The objective of the testing was to determine the effect of spacing from the wall on the lateral resistance of the piles and on the force induc...

Calcium bridges are not load-bearing cell-wall bonds in Avena coleoptiles

NASA Technical Reports Server (NTRS)

Rayle, D. L.

1989-01-01

I examined the ability of frozen-thawed Avena sativa L. coleoptile sections under applied load to extend in response to the calcium chelators ethyleneglycol-bis-(beta-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) and 2-[(2-bis-[carboxymethyl]amino-5-methylphenoxy)methyl]-6-methoxy-8-bis[car boxymethyl]aminoquinoline (Quin II). Addition of 5 mM EGTA to weakly buffered (0.1 mM, pH 6.2) solutions of 2(N-morpholino) ethanesulfonic acid (Mes) initiated rapid extension and wall acidification. When the buffer strength was increased (e.g. from 20 to 100 mM Mes, pH 6.2) EGTA did not initiate extension nor did it cause wall acidification. At 5 mM Quin II failed to stimulate cell extension or wall acidification at all buffer molarities tested (0.1 to 100 mM Mes). Both chelators rapidly and effectively removed Ca2+ from Avena sections. These data indicate that Ca2+ chelation per se does not result in loosening of Avena cells walls. Rather, EGTA promotes wall extension indirectly via wall acidification.

Transient Three-Dimensional Analysis of Nozzle Side Load in Regeneratively Cooled Engines

NASA Technical Reports Server (NTRS)

Wang, Ten-See

2005-01-01

Three-dimensional numerical investigations on the start-up side load physics for a regeneratively cooled, high-aspect-ratio nozzle were performed. The objectives of this study are to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and a transient inlet condition based on an engine system simulation. Computations were performed for both the adiabatic and cooled walls in order to understand the effect of boundary conditions. Finite-rate chemistry was used throughout the study so that combustion effect is always included. The results show that three types of shock evolution are responsible for side loads: generation of combustion wave; transitions among free-shock separation, restricted-shock separation, and simultaneous free-shock and restricted shock separations; along with oscillation of shocks across the lip. Wall boundary conditions drastically affect the computed side load physics: the adiabatic nozzle prefers free-shock separation while the cooled nozzle favors restricted-shock separation, resulting in higher peak side load for the cooled nozzle than that of the adiabatic nozzle. By comparing the computed physics with those of test observations, it is concluded that cooled wall is a more realistic boundary condition, and the oscillation of the restricted-shock separation flow pattern across the lip along with its associated tangential shock motion are the dominant side load physics for a regeneratively cooled, high aspect-ratio rocket engine.

High power water load for microwave and millimeter-wave radio frequency sources

DOEpatents

Ives, R. Lawrence; Mizuhara, Yosuke M.; Schumacher, Richard V.; Pendleton, Rand P.

1999-01-01

A high power water load for microwave and millimeter wave radio frequency sources has a front wall including an input port for the application of RF power, a cylindrical dissipation cavity lined with a dissipating material having a thickness which varies with depth, and a rear wall including a rotating reflector for the reflection of wave energy inside the cylindrical cavity. The dissipation cavity includes a water jacket for removal of heat generated by the absorptive material coating the dissipation cavity, and this absorptive material has a thickness which is greater near the front wall than near the rear wall. Waves entering the cavity reflect from the rotating reflector, impinging and reflecting multiple times on the absorptive coating of the dissipation cavity, dissipating equal amounts of power on each internal reflection.

Transfer cell wall ingrowths and vein loading characteristics in pea leaf discs. [Pisum sativum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wimmers, L.E.; Turgeon, R.

1987-04-01

Transfer cell wall ingrowths are thought to increase transport capacity by increasing plasmalemma surface area. Leaf minor vein phloem transfer cells presumably enhance phloem loading. In Pisum sativum cv. Little marvel grown under different light regimes (150 to 1000 ..mu..mol photons m/sup -2/ sec/sup -1/) there is a positive correlation between light intensity and wall ingrowth area in phloem transfer cells. The extent of ingrowth and correlation to light intensity is greatest in minor veins, decreasing as vein size increases. Vein loading was assayed by floating abraded leaf discs on /sup 14/C-sucrose (10 mM). There is a positive correlation betweenmore » uptake and transfer cell wall area, although the latter increased more than the former. The difference in uptake is stable throughout the photoperiod, and is also stable in mature leaves for at least four days after plants are transfered to a different light intensity. Sucrose uptake is biphasic. The saturable component of uptake is sensitive to light intensity, the Km for sucrose is negatively correlated to light intensity, while V/sub max/remains unchanged.« less

The influence of head diameter and wall thickness on deformations of metallic acetabular press-fit cups and UHMWPE liners: a finite element analysis.

PubMed

Goebel, Paul; Kluess, Daniel; Wieding, Jan; Souffrant, Robert; Heyer, Horst; Sander, Manuela; Bader, Rainer

2013-03-01

To increase the range of motion of total hip endoprostheses, prosthetic heads need to be enlarged, which implies that the cup and/or liner thickness must decrease. This may have negative effects on the wear rate, because the acetabular cups and liners could deform during press-fit implantation and hip joint loading. We compared the metal cup and polyethylene liner deformations that occurred when different wall thicknesses were used in order to evaluate the resulting changes in the clearance of the articulating region. A parametric finite element model utilized three cup and liner wall thicknesses to analyze cup and liner deformations after press-fit implantation into the pelvic bone. The resultant hip joint force during heel strike was applied while the femur was fixed, accounting for physiological muscle forces. The deformation behavior of the liner under joint loading was therefore assessed as a function of the head diameter and the resulting clearance. Press-fit implantation showed diametral cup deformations of 0.096, 0.034, and 0.014 mm for cup wall thicknesses of 3, 5, and 7 mm, respectively. The largest deformations (average 0.084 ± 0.003 mm) of liners with thicknesses of 4, 6, and 8 mm occurred with the smallest cup wall thickness (3 mm). The smallest liner deformation (0.011 mm) was obtained with largest cup and liner wall thicknesses. Under joint loading, liner deformations in thin-walled acetabular cups (3 mm) reduced the initial clearance by about 50 %. Acetabular press-fit cups with wall thicknesses of ≤5 mm should only be used in combination with polyethylene liners >6 mm thick in order to minimize the reduction in clearance.

Propagation behavior of the stress wave in a hollow Hopkinson transmission bar

NASA Astrophysics Data System (ADS)

Zou, G.; Shen, X.; Guo, C.; Vecchio, K. S.; Jiang, F.

2018-03-01

In order to investigate the stress wave propagation behavior through a hollow elastic bar that is used in a Hopkinson-bar-loaded fracture testing system, three-point bending fracture experiments were performed in such a system. The effects of sample span and diameter and wall thickness of the hollow elastic bar on the stress wave propagation behavior were studied numerically using the software of ANSYS/LS-DYNA. The experimental results demonstrated that the incident, reflected, and transmitted pulses calculated by the finite element method are coincident with those obtained from the Hopkinson-bar-loaded fracture tests. Compared to the solid transmission bar, the amplitude of the transmitted pulse is relatively larger in the hollow transmission bar under the same loading conditions and decreases with increasing wall thickness. On the other hand, when the inside diameter is fixed, the effect of the wall thickness on the stress wave characteristics is more obvious.

Study on the Unsteady Creep of Composite Beams with an Irregular Laminar Fibrous Structure Made from Nonlinear Hereditary Materials

NASA Astrophysics Data System (ADS)

Yankovskii, A. P.

2017-09-01

The creep of homogenous and hybrid composite beams of an irregular laminar fibrous structure is investigated. The beams consist of thin walls and flanges (load-carrying layers). The walls may be reinforced longitudinally or crosswise in the plane, and the load-carrying layers are reinforced in the longitudinal direction. The mechanical behavior of phase materials is described by the Rabotnov nonlinear hereditary theory of creep taking into account their possible different resistance to tension and compression. On the basis of hypotheses of the Timoshenko theory, with using the method of time steps, a problem is formulated for the inelastic bending deformation of such beams with account of the weakened resistance of their walls to the transverse shear. It is shown that, at discrete instants of time, the mechanical behavior of such structures can formally be described by the governing relations for composite beams made of nonlinear elastic anisotropic materials with a known initial stress state. The method of successive iterations, similar to the method of variable parameters of elasticity, is used to linearize the boundary-value problem at each instant of time. The bending deformation is investigated for homogeneous and reinforced cantilever and simply supported beams in creep under the action of a uniformly distributed transverse load. The cross sections of the beams considered are I-shaped. It is found that the use of the classical theory for such beams leads to the prediction of indefensibly underestimated flexibility, especially in long-term loading. It is shown that, in beams with reinforced load-carrying layers, the creep mainly develops due to the shear strains of walls. It is found that, in short- and long-term loadings of composite beams, the reinforcement structures rational by the criterion of minimum flexibility are different.

Axial Compression Behavior of a New Type of Prefabricated Concrete Sandwich Wall Panel

NASA Astrophysics Data System (ADS)

Qun, Xie; Shuai, Wang; Chun, Liu

2018-03-01

A novel type of prefabricated concrete sandwich wall panel which could be used as a load-bearing structural element in buildings has been presented in this paper. Compared with the traditional sandwich panels, there are several typical characteristics for this wall system, including core columns confined by spiral stirrup along the cross-section of panel with 600mm spacing, precast foamed concrete block between two structural layers as internal insulation part, and a three-dimensional (3D) steel wire skeleton in each layer which is composed of two vertical steel wire meshes connected by horizontally short steel bar. All steel segments in the panel are automatically prefabricated in factory and then are assembled to form steel system in site. In order to investigate the structural behavior of this wall panel, two full-scale panels have been experimentally studied under axial compressive load. The test results show that the wall panel presents good load-bearing capacity and integral stiffness without out-of-plane flexural failure. Compared to the panel with planar steel wire mesh in concrete layer, the panel with 3D steel wire skeleton presents higher strength and better rigidity even in the condition of same steel ratio in panels which verifies that the 3D steel skeleton could greatly enhance the structural behavior of sandwich panel.

Sustained expression of MCP-1 by low wall shear stress loading concomitant with turbulent flow on endothelial cells of intracranial aneurysm.

PubMed

Aoki, Tomohiro; Yamamoto, Kimiko; Fukuda, Miyuki; Shimogonya, Yuji; Fukuda, Shunichi; Narumiya, Shuh

2016-05-09

Enlargement of a pre-existing intracranial aneurysm is a well-established risk factor of rupture. Excessive low wall shear stress concomitant with turbulent flow in the dome of an aneurysm may contribute to progression and rupture. However, how stress conditions regulate enlargement of a pre-existing aneurysm remains to be elucidated. Wall shear stress was calculated with 3D-computational fluid dynamics simulation using three cases of unruptured intracranial aneurysm. The resulting value, 0.017 Pa at the dome, was much lower than that in the parent artery. We loaded wall shear stress corresponding to the value and also turbulent flow to the primary culture of endothelial cells. We then obtained gene expression profiles by RNA sequence analysis. RNA sequence analysis detected hundreds of differentially expressed genes among groups. Gene ontology and pathway analysis identified signaling related with cell division/proliferation as overrepresented in the low wall shear stress-loaded group, which was further augmented by the addition of turbulent flow. Moreover, expression of some chemoattractants for inflammatory cells, including MCP-1, was upregulated under low wall shear stress with concomitant turbulent flow. We further examined the temporal sequence of expressions of factors identified in an in vitro study using a rat model. No proliferative cells were detected, but MCP-1 expression was induced and sustained in the endothelial cell layer. Low wall shear stress concomitant with turbulent flow contributes to sustained expression of MCP-1 in endothelial cells and presumably plays a role in facilitating macrophage infiltration and exacerbating inflammation, which leads to enlargement or rupture.

An Evaluation of Frangible Materials as Veneers on Vented Structural Member Designs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jameson, Kevin Jay

2015-10-01

Literature shows there has been extensive research and testing done in the area of wall panels and frangible materials. There is evidence from past research that shows it is possible to vent a structure that has had an accidental internal explosion [1]. The reviewed literature shows that most designs vent the entire wall panel versus a frangible material attached to the wall panel. The frangible material attachment points are important to determine the overall loading of the wall panel structure [2]. The materials used in the reviewed literature were securely attached as well as strong enough to remain intact duringmore » the pressure loading to move the entire wall panel. Since the vented wall panel was the weakest part of the overall structure, the other walls of the structure were substantially larger. The structure was usually built from concrete and large amounts of steel with dirt and sand over the top of the structure.The study will be conducted at Sandia National Laboratories located in Albuquerque New Mexico. The skeletal structural design for evaluation is a rectangular frame with a square grid pattern constructed from steel. The skeletal structure has been given to the researcher as a design requirement. The grid pattern will be evaluated strictly on plastic deformation and the loading that is applied from the frangible material. The frangible material tested will either fit into the grid or will be a veneer lightly attached to the structure frame. The frangible material may be required on both sides of the structure to adequately represent the application.« less

Material Characterization for Composite Materials in Load Bearing Wave Guides

DTIC Science & Technology

2012-03-01

ISIS Integrated Sensor Is Structure MUSTRAP Multifunctional Structural Aperture MWCNT Multi-walled Carbon Nanotube SWCNT Single-walled Carbon...CNTs go through a specific process to coat them with nickel. The process includes conditioning the CNTs in different solutions and adding...a single-walled carbon nanotube (SWCNT), a multi-walled carbon nanotube ( MWCNT ), or a graphene nanoribbon (GNR). A SWCNT is a hollow cylindrical

Wall-Friction Support of Vertical Loads in Submerged Sand and Gravel Columns

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walton, O. R.; Vollmer, H. J.; Hepa, V. S.

Laboratory studies of the ‘floor-loads’ under submerged vertical columns of sand and/or gravel indicate that such loads can be approximated by a buoyancy-corrected Janssen-silo-theory-like relationship. Similar to conditions in storage silos filled with dry granular solids, most of the weight of the sand or gravel is supported by wall friction forces. Laboratory measurements of the loads on the floor at the base of the water-filled columns (up to 25-diameters tall) indicate that the extra floor-load from the addition of the granular solid never exceeded the load that would exist under an unsupported (wide) bed of submerged sand or gravel thatmore » has a total depth corresponding to only two column-diameters. The measured floorloads reached an asymptotic maximum value when the depth of granular material in the columns was only three or four pipe-diameters, and never increased further as the columns were filled to the top (e.g. up to heights of 10 to 25 diameters). The floor-loads were stable and remained the same for days after filling. Aggressive tapping (e.g. hitting the containing pipe on the outside, manually with a wrench up and down the height and around the circumference) could increase (and occasionally decrease) the floor load substantially, but there was no sudden collapse or slumping to a state without significant wall friction effects. Considerable effort was required, repeatedly tapping over almost the entire column wall periphery, in order to produce floor-loads that corresponded to the total buoyancy-corrected weight of granular material added to the columns. Projecting the observed laboratory behavior to field conditions would imply that a stable floor-load condition, with only a slightly higher total floor pressure than the preexisting hydrostatic-head, would exist after a water-filled bore-hole is filled with sand or gravel. Significant seismic vibration (either a large nearby event or many micro-seismic events over an extended period) would likely be necessary before the full (buoyancy-corrected) weight of the sand and/or gravel would be ‘delivered’ to the bottom of the submerged column.« less

Vibrations and structureborne noise in space station

NASA Technical Reports Server (NTRS)

Vaicaitis, R.

1985-01-01

Theoretical models were developed capable of predicting structural response and noise transmission to random point mechanical loads. Fiber reinforced composite and aluminum materials were considered. Cylindrical shells and circular plates were taken as typical representatives of structural components for space station habitability modules. Analytical formulations include double wall and single wall constructions. Pressurized and unpressurized models were considered. Parametric studies were conducted to determine the effect on structural response and noise transmission due to fiber orientation, point load location, damping in the core and the main load carrying structure, pressurization, interior acoustic absorption, etc. These analytical models could serve as preliminary tools for assessing noise related problems, for space station applications.

Radial force on the vacuum chamber wall during thermal quench in tokamaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pustovitov, V. D., E-mail: pustovitov-vd@nrcki.ru

The radial force balance during a thermal quench in tokamaks is analyzed. As a rule, the duration τ{sub tp} of such events is much shorter than the resistive time τ{sub w} of the vacuum chamber wall. Therefore, the perturbations of the magnetic field B produced by the evolving plasma cannot penetrate the wall, which makes different the magnetic pressures on its inner and outer sides. The goal of this work is the analytical estimation of the resulting integral radial force on the wall. The plasma is considered axially symmetric; for the description of radial forces on the wall, the resultsmore » of V.D. Shafranov’s classical work [J. Nucl. Energy C 5, 251 (1963)] are used. Developed for tokamaks, the standard equilibrium theory considers three interacting systems: plasma, poloidal field coils, and toroidal field coils. Here, the wall is additionally incorporated with currents driven by ∂B/∂t≠0 accompanying the fast loss of the plasma thermal energy. It is shown that they essentially affect the force redistribution, thereby leading to large loads on the wall. The estimates prove that these loads have to be accounted for in the disruptive scenarios in large tokamaks.« less

Performance of masonry enclosure walls: lessons learned from recent earthquakes

NASA Astrophysics Data System (ADS)

Vicente, Romeu Silva; Rodrigues, Hugo; Varum, Humberto; Costa, Aníbal; Mendes da Silva, José António Raimundo

2012-03-01

This paper discusses the issue of performance requirements and construction criteria for masonry enclosure and infill walls. Vertical building enclosures in European countries are very often constituted by non-load-bearing masonry walls, using horizontally perforated clay bricks. These walls are generally supported and confined by a reinforced concrete frame structure of columns and beams/slabs. Since these walls are commonly considered to be nonstructural elements and their influence on the structural response is ignored, their consideration in the design of structures as well as their connection to the adjacent structural elements is frequently negligent or insufficiently detailed. As a consequence, nonstructural elements, as for wall enclosures, are relatively sensitive to drift and acceleration demands when buildings are subjected to seismic actions. Many international standards and technical documents stress the need for design acceptability criteria for nonstructural elements, however they do not specifically indicate how to prevent collapse and severe cracking, and how to enhance the overall stability in the case of moderate to high seismic loading. Furthermore, a review of appropriate measures to improve enclosure wall performance and both in-plane and out-of-plane integrity under seismic actions is addressed.

An analytical study of the effects of transverse shear deformation and anisotropy on buckling loads of laminated cylinders. M.S. Thesis - George Washington Univ.

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.

1987-01-01

Buckling loads of thick-walled orthotropic and anisotropic simply supported circular cylinders are predicted using a higher-order transverse-shear deformation theory. A comparison of buckling loads predicted by the conventional first-order transverse-shear deformation theory and the higher-order theory show that the additional allowance for transverse shear deformation has a negligible effect on the predicted buckling loads of medium-thick metallic isotropic cylinders. However, the higher-order theory predicts buckling loads which are significantly lower than those predicted by the first-order transverse-shear deformation theory for certain short, thick-walled cylinders which have low through-the-thickness shear moduli. A parametric study of the effects of ply orientation on the buckling load of axially compressed cylinders indicates that laminates containing 45 degree plies are most sensitive to transverse-shear deformation effects. Interaction curves for buckling loads of cylinders subjected to axial compressive and external pressure loadings indicate that buckling loads due to external pressure loadings are as sensitive to transverse-shear deformation effects as buckling loads due to axial compressive loadings. The effects of anisotropy are important over a much wider range of cylinder geometries than the effects of transverse shear deformation.

Use of Natural-Fiber Bio-Composites in Construction versus Traditional Solutions: Operational and Embodied Energy Assessment.

PubMed

Galan-Marin, Carmen; Rivera-Gomez, Carlos; Garcia-Martinez, Antonio

2016-06-13

During the last decades natural polymers have become more and more frequent to replace traditional inorganic stabilizers in building materials. The purpose of this research is to establish a comparison between the most conventional building material solutions for load-bearing walls and a type of biomaterial. This comparison will focus on load-bearing walls as used in a widespread type of twentieth century dwelling construction in Europe and still used in developing countries nowadays. To carry out this analysis, the structural and thermal insulation characteristics of different construction solutions are balanced. The tool used for this evaluation is the life cycle assessment throughout the whole lifespan of these buildings. This research aims to examine the environmental performance of each material assessed: fired clay brick masonry walls (BW), concrete block masonry walls (CW), and stabilized soil block masonry walls (SW) stabilized with natural fibers and alginates. These conventional and new materials are evaluated from the point of view of both operational and embodied energy.

Infill Walls Contribution on the Progressive Collapse Resistance of a Typical Mid-rise RC Framed Building

NASA Astrophysics Data System (ADS)

Besoiu, Teodora; Popa, Anca

2017-10-01

This study investigates the effect of the autoclaved aerated concrete infill walls on the progressive collapse resistance of a typical RC framed structure. The 13-storey building located in Brăila (a zone with high seismic risk in Romania) was designed according to the former Romanian seismic code P13-70 (1970). Two models of the structure are generated in the Extreme Loading® for Structures computer software: a model with infill walls and a model without infill walls. Following GSA (2003) Guidelines, a nonlinear dynamic procedure is used to determine the progressive collapse risk of the building when a first-storey corner column is suddenly removed. It was found that, the structure is not expected to fail under the standard GSA loading: DL+0.25LL. Moreover, if the infill walls are introduced in the model, the maximum vertical displacement of the node above the removed column is reduced by about 48%.

Use of Natural-Fiber Bio-Composites in Construction versus Traditional Solutions: Operational and Embodied Energy Assessment

PubMed Central

Galan-Marin, Carmen; Rivera-Gomez, Carlos; Garcia-Martinez, Antonio

2016-01-01

During the last decades natural polymers have become more and more frequent to replace traditional inorganic stabilizers in building materials. The purpose of this research is to establish a comparison between the most conventional building material solutions for load-bearing walls and a type of biomaterial. This comparison will focus on load-bearing walls as used in a widespread type of twentieth century dwelling construction in Europe and still used in developing countries nowadays. To carry out this analysis, the structural and thermal insulation characteristics of different construction solutions are balanced. The tool used for this evaluation is the life cycle assessment throughout the whole lifespan of these buildings. This research aims to examine the environmental performance of each material assessed: fired clay brick masonry walls (BW), concrete block masonry walls (CW), and stabilized soil block masonry walls (SW) stabilized with natural fibers and alginates. These conventional and new materials are evaluated from the point of view of both operational and embodied energy. PMID:28773586

Technology Solutions Case Study: Hygrothermal Performance of a Double-Stud Cellulose Wall

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2015-06-01

Moisture problems within the building shell can be caused by a number of factors including excess interior moisture that is transported into the wall through air leakage and vapor drive, bulk water intrusion from leaks and wind-driven rain, capillary action from concrete to wood connections, and through wetted building materials such as siding wetted from rain splash back. With the increasing thickness of walls, moisture issues could increase. Several builders have successfully used “double-wall” systems to more practically achieve higher R-values in thicker framed walls. A double wall typically consists of a load-bearing external frame wall constructed with 2 ×more » 4 framing at 16 in. on center using conventional methods. After the building is enclosed, an additional frame wall is constructed several inches inside the load-bearing wall. Several researchers have used moisture modeling software to conduct extensive analysis of these assemblies; however, little field research has been conducted to validate the results. In this project, the Building America research team Consortium for Advanced Residential Buildings monitored a double-stud assembly in climate zone 5A to determine the accu¬racy of moisture modeling and make recommendations to ensure durable and efficient assemblies.« less

Performance of Steel Stud Walls Subjected to Blast Loads

DTIC Science & Technology

2010-02-01

be used as load-bearing components or non-load-bearing components, and a variety of exterior finishes and internal sheathing may be used. From an...common sheathing materials such as drywall , oriented strand board (OSB), stucco, etc., utilizing conventional structural connections (e.g., slip

An Experimental Investigation on the Ultimate Strength of Partially Infilled: Braced Steel Frames

NASA Astrophysics Data System (ADS)

Dubey, Shailendra Kumar Damodar; Kute, Sunil Y.

2017-12-01

Infilled walls are usually, considered as non-structural elements. However, these walls are effective in carrying lateral loads. In this regard, an experimental investigation was planned and conducted to study the effect of braced and partially infilled steel frames with cement mortar and concrete in comparison to the bare frames. All these frames were tested up to collapse and subjected only to horizontal loads to obtain an effective and possible solution for soft storey which are generally not infilled. In comparison to bare steel frames, partially infilled frames have an increase of lateral load capacity by 45-60%. Central bracing is more effective than that of the corner bracing. For the same load partially infilled frames have significantly less deflection than that of the bare frames. A reduced load factor is suggested for the design of soft storey columns with the partial infills. A mathematical model has been proposed to calculate the theoretical ultimate load for the braced, cement mortar and concrete partial infilled frames.

On the Lateral Compressive Behavior of Empty and Ex-Situ Aluminum Foam-Filled Tubes at High Temperature

PubMed Central

Movahedi, Nima; Marsavina, Liviu

2018-01-01

In this research work, the effect of lateral loading (LL) on the crushing performance of empty tubes (ETs) and ex situ aluminum foam-filled tubes (FFTs) was investigated at 300 °C. The cylindrical thin-walled steel tube was filled with the closed-cell aluminum alloy foam that compressed under quasi-static loading conditions. During the compression test, the main mechanical properties of the ETs improved due to the interaction effect between the cellular structure of the foam and the inner wall of the empty tube. In addition, the initial propagated cracks on the steel tubes reduced considerably as a result of such interaction. Furthermore, the obtained results of the LL loading were compared with the axial loading (AL) results for both ETs and FFTs at the same temperature. The findings indicated that the application of loading on the lateral surface of the composite causes the lower mechanical properties of both ETs and FFTs in comparison with the axial loading conditions. PMID:29617300

Load transfer in the proximal tibia following implantation with a unicompartmental knee replacement: a static snapshot.

PubMed

Simpson, D J; Kendrick, B J L; Dodd, C A F; Price, A J; Gill, H S; Murray, D W

2011-05-01

Unicompartmental knee replacement (UKR) is an appealing alternative to total knee replacement when the patient has isolated medial compartment osteoarthritis. A common observation post-operatively is radiolucency between the tibial tray wall and the bone. In addition, some patients complain of persistent pain over the proximal tibia antero-medially; this may be related to elevated bone strains in the tibia. Currently, there is no intentionally made mechanical bond between the vertical wall of an Oxford UKR and the adjacent bone; whether one exists or not will influence the load transmission in the proximal tibia and may affect the elevated tibia strain. The aim of this study was to investigate how introducing a mechanical tie between the tibial tray wall and the adjacent bone might alter the load carried into the tibia for both cemented and cementless UKRs. Strain energy density in the region of bone adjacent to the tray wall was considerably increased when a mechanical tie was introduced; this has the potential of reducing the likelihood of a radiolucency occurring in that region. Moreover, a mechanical tie had the effect of reducing proximal tibia strain, which may decrease the incidence of pain following implantation with a UKR.

Investigating Wind-Driven Rain Intrusion in Walls with the CARWASh

Treesearch

C.R. Boardman; Samuel V. Glass

2013-01-01

Wind-driven rain provides the primary external moisture load for exterior walls.Water absorption by the cladding, runoff, and penetration through the cladding or at details determine how a wall system performs. In this paper we describe a new laboratory facility that can create controlled outdoor and indoor conditions and use it to investigate the water...

Termites utilise clay to build structural supports and so increase foraging resources.

PubMed

Oberst, Sebastian; Lai, Joseph C S; Evans, Theodore A

2016-02-08

Many termite species use clay to build foraging galleries and mound-nests. In some cases clay is placed within excavations of their wooden food, such as living trees or timber in buildings; however the purpose for this clay is unclear. We tested the hypotheses that termites can identify load bearing wood, and that they use clay to provide mechanical support of the load and thus allow them to eat the wood. In field and laboratory experiments, we show that the lower termite Coptotermes acinaciformis, the most basal species to build a mound-nest, can distinguish unloaded from loaded wood, and use clay differently when eating each type. The termites target unloaded wood preferentially, and use thin clay sheeting to camouflage themselves while eating the unloaded wood. The termites attack loaded wood secondarily, and build thick, load-bearing clay walls when they do. The termites add clay and build thicker walls as the load-bearing wood is consumed. The use of clay to support wood under load unlocks otherwise unavailable food resources. This behaviour may represent an evolutionary step from foraging behaviour to nest building in lower termites.

A method for determination of equine hoof strain patterns using photoelasticity: an in vitro study.

PubMed

Dejardin, L M; Arnoczky, S P; Cloud, G L

1999-05-01

During impact, equine hooves undergo viscoelastic deformations which may result in potentially harmful strains. Previous hoof strain studies using strain gauges have been inconclusive due to arbitrary gauge placement. Photoelastic stress analysis (PSA) is a full-field technique which visually displays strains over entire loaded surfaces. This in vitro study identifies normal hoof strain patterns using PSA. Custom-made photoelastic plastic sheets were applied to the hoof surface. The hooves were axially loaded (225 kg) under level and varus/valgus conditions. Strain patterns were video-recorded through a polariscope. Strains were concentrated between middle and distal thirds of the hoof wall regardless of the loading conditions. This strain distribution appears to result from the differential expansion of the hoof wall under load. Increasing load resulted in higher strains and asymmetric loading resulted in an ipsilateral increase in strain magnitudes without altering strain locations. This study shows that PSA is a reliable method with which to evaluate hoof strains in vitro and is sensitive enough to reflect subtle load-related strain alterations.

Development of LRFD resistance factors for mechanically stabilized earth (MSE) walls : [technical summary].

DOT National Transportation Integrated Search

2013-12-01

Bridge approach embankments and many other : transportation-related applications make use of : reinforced earth retaining structures. Mechanically : Stabilized Earth (MSE) walls are designed under : the Load and Resistance Factor Design (LRFD) : meth...

Evaluation of Extended Wall OSB Sheathing Connection under Combined Uplift and Shear Loading for 24-inch Heel Trusses

Treesearch

Vladimir Kochkin; Andrew DeRenzis; Xiping Wang

2014-01-01

This study was designed to evaluate the performance of the extended wall structural panel connection in resisting combined uplift and shear forces at the roof-to-wall interface with a focus on a truss heel height of 24 in. to address the expected increases in the depth of attic insulation used in Climate Zones 5 and higher. Five full-size roof-wall assemblies were...

Moisture Management for High R-Value Walls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lepage, R.; Schumacher, C.; Lukachko, A.

2013-11-01

The following report explains the moisture-related concerns for High R-value wall assemblies and discusses past Building America research work that informs this study. Hygrothermal simulations were prepared for several common approaches to High R-value wall construction in six cities (Houston, Atlanta, Seattle, St. Louis, Chicago, and International Falls) representing a range of climate zones (2, 3, 4C, 4, 5A, and 7, respectively). The simulations are informed by experience gained from past research in this area and validated by field measurement and forensic experience. The modeling program was developed to assess the moisture durability of the wall assemblies based on threemore » primary sources of moisture: construction moisture, air leakage condensation, and bulk water leakage. The peak annual moisture content of the wood based exterior sheathing was used to comparatively analyze the response to the moisture loads for each of the walls in each given city. Walls which experienced sheathing moisture contents between 20% and 28% were identified as risky, whereas those exceeding 28% were identified as very high risk. All of the wall assemblies perform well under idealized conditions. However, only the walls with exterior insulation, or cavity insulation which provides a hygrothermal function similar to exterior insulation, perform adequately when exposed to moisture loads. Walls with only cavity insulation are particularly susceptible to air leakage condensation. None of the walls performed well when a precipitation based bulk water leak was introduced to the backside of the sheathing, emphasizing the importance of proper flashing details.« less

Moisture Management of High-R Walls (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

2013-12-01

The following report explains the moisture-related concerns for High R-value wall assemblies and discusses past Building America research work that informs this study. Hygrothermal simulations were prepared for several common approaches to High R-value wall construction in six cities (Houston, Atlanta, Seattle, St. Louis, Chicago, and International Falls) representing a range of climate zones (2, 3, 4C, 4, 5A, and 7, respectively). The simulations are informed by experience gained from past research in this area and validated by field measurement and forensic experience. The modeling program was developed to assess the moisture durability of the wall assemblies based on threemore » primary sources of moisture: construction moisture, air leakage condensation, and bulk water leakage. The peak annual moisture content of the wood based exterior sheathing was used to comparatively analyze the response to the moisture loads for each of the walls in each given city. Walls which experienced sheathing moisture contents between 20% and 28% were identified as risky, whereas those exceeding 28% were identified as very high risk. All of the wall assemblies perform well under idealized conditions. However, only the walls with exterior insulation, or cavity insulation which provides a hygrothermal function similar to exterior insulation, perform adequately when exposed to moisture loads. Walls with only cavity insulation are particularly susceptible to air leakage condensation. None of the walls performed well when a precipitation based bulk water leak was introduced to the backside of the sheathing, emphasizing the importance of proper flashing details.« less

Laboratory testing of a building envelope segment based on cellular concrete

NASA Astrophysics Data System (ADS)

Fořt, Jan; Pavlík, Zbyšek; Černý, Robert

2016-07-01

Hygrothermal performance of a building envelope based on cellular concrete blocks is studied in the paper. Simultaneously, the strain fields induced by the heat and moisture changes are monitored. The studied wall is exposed to the climatic load corresponding to the winter climatic conditions of the moderate year for Prague. The winter climatic exposure is chosen in order to simulate the critical conditions of the building structure from the point of view of material performance and temperature and humidity loading. The evaluation of hygrothermal performance of a researched wall is done on the basis of relative humidity and temperature profiles measured along the cross section of the cellular concrete blocks. Strain gauges are fixed on the wall surface in expected orientation of the blocks expansion. The obtained results show a good hygrothermal function of the analyzed cellular concrete wall and its insignificant strain.

Leucine/Pd-loaded (5,5) single-walled carbon nanotube matrix as a novel nanobiosensors for in silico detection of protein.

PubMed

Yoosefian, Mehdi; Etminan, Nazanin

2018-06-01

We have designed a novel nanobiosensor for in silico detecting proteins based on leucine/Pd-loaded single-walled carbon nanotube matrix. Density functional theory at the B3LYP/6-31G (d) level of theory was realized to analyze the geometrical and electronic structure of the proposed nanobiosensor. The solvent effects were investigated using the Tomasi's polarized continuum model. Atoms-in-molecules theory was used to study the nature of interactions by calculating the electron density ρ(r) and Laplacian at the bond critical points. Natural bond orbital analysis was performed to achieve a deep understanding of the nature of the interactions. The biosensor has potential application for high sensitive and rapid response to protein due to the chemical adsorption of L-leucine amino acid onto Pd-loaded single-walled carbon nanotube and reactive functional groups that can incorporate in hydrogen binding, hydrophobic interactions and van der Waals forces with the protein surface in detection process.

Sensitive electrochemical sensing platform for microRNAs detection based on shortened multi-walled carbon nanotubes with high-loaded thionin.

PubMed

Deng, Keqin; Liu, Xinyan; Li, Chunxiang; Huang, Haowen

2018-05-31

The loading capacity of thionin (Thi) on shortened multi-walled carbon nanotubes (S-MWCNTs) and acidified multi-walled carbon nanotubes (A-MWCNTs) was compared. Two DNA probe fragments were designed for hybridization with microRNA-21 (miR-21), the microRNAs (miRNAs) model analyte. DNA probe 1 (P1) was assembled on Au nanoparticles (AuNPs) modified electrode. MiR-21 was captured by the pre-immobilized P1. A signal nanoprobe was synthesized by loading large amount of Thi on S-MWCNTs with covalently bonded probe 2 (P2). Owing to the large effective surface area of MWCNTs, fast electron shuttle of MWCNTs, high-loaded Thi on S-MWCNTs, and the increased conductivity from AuNPs, after signal probe hybridized with miR-21, it gave rise to a magnified current response on electrode. The increased electrochemical current enabled us to quantitatively detect miR-21. Expensive bioreagents and labeled target/detection DNA or miRNAs were avoided in this strategy. The operation complexity and assay cost were also reduced. Copyright © 2018 Elsevier B.V. All rights reserved.

A new concept of precast concrete retaining wall: from laboratory model to the in-situ tests

NASA Astrophysics Data System (ADS)

Bui, T. T.; Tran, H. V.; Limam, A.; Bost, M.; Bui, Q. B.; Robit, P.

2018-04-01

A new concept for the soil nail walls is here proposed and validated through experimental and numerical approaches. This process, based on the use of precast elements that are easier to install, is cheaper and more aesthetic than the classical methods, but the main advantage is reducing the cement consumption which conducts to divided carbon footprint by three. In order to characterize the structural capacity of this new process, this article present an investigation on two in-situ representative walls, one in shotcrete which is the old way of construction, and the other, consisting the precast reinforced concrete slabs, which is the new process. We thus have a demonstrator on a real scale, and perfectly representative, since the constructive modes, as well as the mechanical, thermal, and hydric loadings are the real ones associated with the environment in situ. Substantial instrumentation has been realized over a long period (nearly 2 years), enabling to follow the evolution of the displacements of each wall and the efforts in the anchor nails. To determine the bearing capacity of the constituent element of the precast nail wall, an experimental study coupled with a numerical simulation has been conducted in the laboratory on a single precast slab. This study allows the evaluation of the load associated to crack initiation and the bearing capacity associated to the ultimate state, at the scale of the constituent elements. Finally, in order to evaluate the behaviour of the two concepts of nail walls in the case of extreme solicitation, a dynamic loading induced by an explosion has been conducted on the site.

Hydraulic properties of 3D rough-walled fractures during shearing: An experimental study

NASA Astrophysics Data System (ADS)

Yin, Qian; Ma, Guowei; Jing, Hongwen; Wang, Huidong; Su, Haijian; Wang, Yingchao; Liu, Richeng

2017-12-01

This study experimentally analyzed the influence of shear processes on nonlinear flow behavior through 3D rough-walled rock fractures. A high-precision apparatus was developed to perform stress-dependent fluid flow tests of fractured rocks. Then, water flow tests on rough-walled fractures with different mechanical displacements were conducted. At each shear level, the hydraulic pressure ranged from 0 to 0.6 MPa, and the normal load varied from 7 to 35 kN. The results show that (i) the relationship between the volumetric flow rate and hydraulic gradient of rough-walled fractures can be well fit using Forchheimer's law. Notably, both the linear and nonlinear coefficients in Forchheimer's law decrease during shearing; (ii) a sixth-order polynomial function is used to evaluate the transmissivity based on the Reynolds number of fractures during shearing. The transmissivity exhibits a decreasing trend as the Reynolds number increases and an increasing trend as the shear displacement increases; (iii) the critical hydraulic gradient, critical Reynolds number and equivalent hydraulic aperture of the rock fractures all increase as the shear displacement increases. When the shear displacement varies from 0 to 15 mm, the critical hydraulic gradient ranges from 0.3 to 2.2 for a normal load of 7 kN and increases to 1.8-8.6 for a normal load of 35 kN; and (iv) the Forchheimer law results are evaluated by plotting the normalized transmissivity of the fractures during shearing against the Reynolds number. An increase in the normal load shifts the fitted curves downward. Additionally, the Forchheimer coefficient β decreases with the shear displacement but increases with the applied normal load.

An Approximate Solution and Master Curves for Buckling of Symmetrically Laminated Composite Cylinders

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.

2013-01-01

Nondimensional linear-bifurcation buckling equations for balanced, symmetrically laminated cylinders with negligible shell-wall anisotropies and subjected to uniform axial compression loads are presented. These equations are solved exactly for the practical case of simply supported ends. Nondimensional quantities are used to characterize the buckling behavior that consist of a stiffness-weighted length-to-radius parameter, a stiffness-weighted shell-thinness parameter, a shell-wall nonhomogeneity parameter, two orthotropy parameters, and a nondimensional buckling load. Ranges for the nondimensional parameters are established that encompass a wide range of laminated-wall constructions and numerous generic plots of nondimensional buckling load versus a stiffness-weighted length-to-radius ratio are presented for various combinations of the other parameters. These plots are expected to include many practical cases of interest to designers. Additionally, these plots show how the parameter values affect the distribution and size of the festoons forming each response curve and how they affect the attenuation of each response curve to the corresponding solution for an infinitely long cylinder. To aid in preliminary design studies, approximate formulas for the nondimensional buckling load are derived, and validated against the corresponding exact solution, that give the attenuated buckling response of an infinitely long cylinder in terms of the nondimensional parameters presented herein. A relatively small number of "master curves" are identified that give a nondimensional measure of the buckling load of an infinitely long cylinder as a function of the orthotropy and wall inhomogeneity parameters. These curves reduce greatly the complexity of the design-variable space as compared to representations that use dimensional quantities as design variables. As a result of their inherent simplicity, these master curves are anticipated to be useful in the ongoing development of buckling-design technology.

Design of SC walls and slabs for impulsive loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varma, Amit H.

2015-11-11

Reinforced concrete (RC) structures have historically been the preferred choice for blast resistant structures because of their mass and the ductility provided by steel reinforcement. Steel-plate composite (SC) walls are a viable alternative to RC for protecting the infrastructure against explosive threats. SC structures consist of two steel faceplates with a plain concrete core between them. The steel faceplates are anchored to the concrete using stud anchors and connected to each other using tie bars. SC structures provide mass from the concrete infill and ductility from the continuous external steel faceplates. This dissertation presents findings and recommendations from experimental andmore » analytical investigations of the performance of SC walls subjected to far-field blast loads.« less

Numerical Simulation of Wall Heat Load in Combustor Flow

NASA Astrophysics Data System (ADS)

Panara, D.; Hase, M.; Krebs, W.; Noll, B.

2007-09-01

Due to the major mechanism of NOx generation, there is generally a temperature trade off between improved cycle efficiency, material constraints and low NOx emission. The cycle efficiency is proportional to the highest cycle temperature, but unfortunately also the NOx production increases with increasing combustion temperature. For this reason, the modern combustion chamber design has been oriented towards lean premixed combustion system and more and more attention must be focused on the cooling air management. The challenge is to ensure sufficiently low temperature of the combustion liner with very low amount of film or effusion cooling air. Correct numerical prediction of temperature fields and wall heat load are therefore of critical interest in the modern combustion chamber design. Moreover, lean combustion technology has shown the appearance of thermo-acoustic instabilities which have to be taken into account in the simulation and, more in general, in the design of reliable combustion systems. In this framework, the present investigation addresses the capability of a commercial multiphysics code (ANSYS CFX) to correctly predict the wall heat load and the core flow temperature field in a scaled power generation combustion chamber with a simplified ceramic liner. Comparison are made with the experimental results from the ITS test rig at the University of Karlsruhe [1] and with a previous numerical campaign from [2]. In addition the effect of flow unsteadyness on the wall heat load is discussed showing some limitations of the traditional steady state flow thermal design.

Deformational injection rate measuring method

NASA Astrophysics Data System (ADS)

Marčič, Milan

2002-09-01

After completing the diesel engine endurance testing, we detected various traces of thermal load on the walls of combustion chambers located in the engine pistons. The engines were fitted with ω combustion chambers. The thermal load of different intensity levels occurred where the spray of fuel, fuel vapor, and air interacted with the combustion chamber wall. The uneven thermal load distribution of the combustion chamber wall results from varying injection rates in each injection nozzle hole. The most widely applied controlling methods so far for injection rate measurement, such as the Zeuch and Bosch concepts, allow measurement of only the total injection rate in multihole nozzles, without providing any indication whatsoever of the injection rate differences in individual injection nozzle holes. The new deformational measuring method described in the article allows the injection rate to be measured in each hole of the multihole nozzle. The results of the measurements using this method showed that the differences occurred in injection rates of individual injection nozzle holes. These differences may be the cause of various thermal loads on the combustion chamber walls. The criterion for injection rate is the deformation of the membrane due to an increase in the fuel quantity in the measuring space and due to the pressure waves resulting from the fuel being injected into the measuring space. The membrane deformation is measured using strain gauges, glued to the membrane and forming the Wheatstone's bridge. We devoted special attention to the temperature compensation of the Wheatstone's bridge and the membrane, heated up during the measurements.

High-oil-load encapsulation of medium-chain triglycerides and D-limonene mixture in modified starch by spray drying.

PubMed

Paramita, Vita; Furuta, Takeshi; Yoshii, Hidefumi

2012-02-01

Oil mixtures of medium-chain triglycerides (MCT) and D-limonene in mixing ratios from 10 to 100 wt% were encapsulated in modified starch (wall material) by spray drying to produce oil-rich powders. The oil load (mass ratio of oil mixture to wall material) of the infeed emulsion markedly influenced the properties of the infeed liquid and the characteristics of the resulting powder. The viscosity of the infeed liquid and the particle size of the powder exponentially decreased with increasing oil load, while the emulsion droplet size in the infeed liquid increased. In addition, retention of D-limonene during spray drying also decreased markedly with increasing oil load. Irrespective of the different oil loads and concentrations of the wall material, D-limonene retention was well correlated with the emulsion droplet diameter of the infeed liquid. The encapsulation efficiency of the oil mixture exhibited a maximum value (almost 100%) at an oil load between 0.5 and 1.0, before decreasing at higher oil loads. At an oil load of 2.0, the encapsulation efficiency of D-limonene was reduced to almost zero, while around 40% of the initial MCT was encapsulated in the powder. The increase in oil load also led to increased amounts of surface oil of MCT and D-limonene in the resulting powder due to the increasing emulsion droplet diameter of the infeed liquids. This study proposes the microencapsulation of medium-chain triglycerides under high-oil-load conditions by spray drying. The powders prepared by this process provide significant benefits in terms of rapid energy conversion after consumption without accumulation in the body. Important quality factors of the powder products such as the encapsulation efficiency and the amount of surface oil were examined to understand the optimum process conditions for spray drying. © 2012 Institute of Food Technologists®

Development of LRFD resistance factors for mechanically stabilized earth (MSE) walls.

DOT National Transportation Integrated Search

2013-12-01

Over 100 centrifuge tests were conducted to assess Load and Resistance Factor : Design (LRFD) resistance factors for external stability of Mechanically Stabilized Earth (MSE) walls : founded on granular soils. In the case of sliding stability, the te...

Overview of experimental preparation for the ITER-Like Wall at JET

NASA Astrophysics Data System (ADS)

Jet Efda Contributors Brezinsek, S.; Fundamenski, W.; Eich, T.; Coad, J. P.; Giroud, C.; Huber, A.; Jachmich, S.; Joffrin, E.; Krieger, K.; McCormick, K.; Lehnen, M.; Loarer, T.; de La Luna, E.; Maddison, G.; Matthews, G. F.; Mertens, Ph.; Nunes, I.; Philipps, V.; Riccardo, V.; Rubel, M.; Stamp, M. F.; Tsalas, M.

2011-08-01

Experiments in JET with carbon-based plasma-facing components have been carried out in preparation of the ITER-Like Wall with beryllium main chamber and full tungsten divertor. The preparatory work was twofold: (i) development of techniques, which ensure safe operation with the new wall and (ii) provision of reference plasmas, which allow a comparison of operation with carbon and metallic wall. (i) Compatibility with the W divertor with respect to energy loads could be achieved in N2 seeded plasmas at high densities and low temperatures, finally approaching partial detachment, with only moderate confinement reduction of 10%. Strike-point sweeping increases the operational space further by re-distributing the load over several components. (ii) Be and C migration to the divertor has been documented with spectroscopy and QMBs under different plasma conditions providing a database which will allow a comparison of the material transport to remote areas with metallic walls. Fuel retention rates of 1.0-2.0 × 1021 D s-1 were obtained as references in accompanied gas balance studies.

Heterogeneous upper-bound finite element limit analysis of masonry walls out-of-plane loaded

NASA Astrophysics Data System (ADS)

Milani, G.; Zuccarello, F. A.; Olivito, R. S.; Tralli, A.

2007-11-01

A heterogeneous approach for FE upper bound limit analyses of out-of-plane loaded masonry panels is presented. Under the assumption of associated plasticity for the constituent materials, mortar joints are reduced to interfaces with a Mohr Coulomb failure criterion with tension cut-off and cap in compression, whereas for bricks both limited and unlimited strength are taken into account. At each interface, plastic dissipation can occur as a combination of out-of-plane shear, bending and torsion. In order to test the reliability of the model proposed, several examples of dry-joint panels out-of-plane loaded tested at the University of Calabria (Italy) are discussed. Numerical results are compared with experimental data for three different series of walls at different values of the in-plane compressive vertical loads applied. The comparisons show that reliable predictions of both collapse loads and failure mechanisms can be obtained by means of the numerical procedure employed.

The Buckling of Curved Tension-field Girders

NASA Technical Reports Server (NTRS)

Limpert, G

1938-01-01

The present paper reports on experiments made to determine the buckling load under shear of circular curved tension-field webs. The buckling load of the webs may be expressed with reference to the buckling load of the stiffeners. It is found that within the explored range the buckling load is approximately twice as great as that of the identically stiffened flat wall of equal web depth.

Theoretical study of the tunnel-boundary lift interference due to slotted walls in the presence of the trailing-vortex system of a lifting model

NASA Technical Reports Server (NTRS)

Matthews, Clarence W

1955-01-01

The equations presented in this report give the interference on the trailing-vortex system of a uniformly loaded finite-span wing in a circular tunnel containing partly open and partly closed walls, with special reference to symmetrical arrangements of the open and closed portions. Methods are given for extending the equations to include tunnel shapes other than circular. The rectangular tunnel is used to demonstrate these methods. The equations are also extended to nonuniformly loaded wings.

Stresses In And Near A Bend In A Thin-Walled Duct

NASA Technical Reports Server (NTRS)

Min, J. B.; Aggarwal, P. K.

1995-01-01

Report describes computational study of distributions of stresses in and near 90 degrees bend in thin-walled duct subject to various applied loads. Purpose of study to help satisfy need for more accurate knowledge of local concentrations of stresses caused by loads: such knowledge makes possible to design light-weight ducts to survive reasonably foreseeable operating conditions with some degree of reliability. Also guides selection of locations for mounting strain gauges to measure local stresses for comparison with computed values, contributing to refinement of theoretical concepts and computational techniques.

Behaviour of partially composite precast concrete sandwich panels under flexural and axial loads

NASA Astrophysics Data System (ADS)

Tomlinson, Douglas George

Precast concrete sandwich panels are commonly used on building exteriors. They are typically composed of two concrete wythes that surround rigid insulation. They are advantageous as they provide both structural and thermal resistance. The structural response of sandwich panels is heavily influenced by shear connectors that link the wythes together. This thesis presents a study on partially composite non-prestressed precast concrete wall panels. Nine flexure tests were conducted on a wall design incorporating 'floating' concrete studs and Glass Fibre Reinforced Polymer (GFRP) connectors. The studs encapsulate and stiffen the connectors, reducing shear deformations. Ultimate loads increased from 58 to 80% that of a composite section as the connectors' reinforcement ratio increased from 2.6 to 9.8%. This design was optimized by reinforcing the studs and integrating them with the structural wythe; new connectors composed of angled steel or Basalt-FRP (BFRP) were used. The load-slip response of the new connector design was studied through 38 double shear push-through tests using various connector diameters and insertion angles. Larger connectors were stronger but more likely to pull out. Seven flexure tests were conducted on the new wall design reinforced with different combinations of steel and BFRP connectors and reinforcement. Composite action varied from 50 to 90% depending on connector and reinforcement material. Following this study, the axial-bending interaction curves were established for the new wall design using both BFRP and steel connectors and reinforcement. Eight panels were axially loaded to predesignated loads then loaded in flexure to failure. A technique is presented to experimentally determine the effective centroid of partially composite sections. Beyond the tension and compression-controlled failure regions of the interaction curve, a third region was observed in between, governed by connector failure. Theoretical models were developed for the bond-slip behaviour of the shear connection and to analyze the full panel's flexural and axial response to determine the longitudinal shear force transferred between wythes and account for partial composite behavior. The models were validated against experiments and used to conduct a parametric study. Among several interesting findings, the study demonstrated how composite action increases with the slenderness of axially loaded panels.

Inelastic behavior of cold-formed braced walls under monotonic and cyclic loading

NASA Astrophysics Data System (ADS)

Gerami, Mohsen; Lotfi, Mohsen; Nejat, Roya

2015-06-01

The ever-increasing need for housing generated the search for new and innovative building methods to increase speed and efficiency and enhance quality. One method is the use of light thin steel profiles as load-bearing elements having different solutions for interior and exterior cladding. Due to the increase in CFS construction in low-rise residential structures in the modern construction industry, there is an increased demand for performance inelastic analysis of CFS walls. In this study, the nonlinear behavior of cold-formed steel frames with various bracing arrangements including cross, chevron and k-shape straps was evaluated under cyclic and monotonic loading and using nonlinear finite element analysis methods. In total, 68 frames with different bracing arrangements and different ratios of dimensions were studied. Also, seismic parameters including resistance reduction factor, ductility and force reduction factor due to ductility were evaluated for all samples. On the other hand, the seismic response modification factor was calculated for these systems. It was concluded that the highest response modification factor would be obtained for walls with bilateral cross bracing systems with a value of 3.14. In all samples, on increasing the distance of straps from each other, shear strength increased and shear strength of the wall with bilateral bracing system was 60 % greater than that with lateral bracing system.

Abdomino-phrenic dyssynergia in patients with abdominal bloating and distension.

PubMed

Villoria, Albert; Azpiroz, Fernando; Burri, Emanuel; Cisternas, Daniel; Soldevilla, Alfredo; Malagelada, Juan-R

2011-05-01

The abdomen normally accommodates intra-abdominal volume increments. Patients complaining of abdominal distension exhibit abnormal accommodation of colonic gas loads (defective contraction and excessive protrusion of the anterior wall). However, abdominal imaging demonstrated diaphragmatic descent during spontaneous episodes of bloating in patients with functional gut disorders. We aimed to establish the role of the diaphragm in abdominal distension. In 20 patients complaining of abdominal bloating and 15 healthy subjects, we increased the volume of the abdominal cavity with a colonic gas load, while measuring abdominal girth and electromyographic activity of the anterior abdominal muscles and of the diaphragm. In healthy subjects, the colonic gas load increased girth, relaxed the diaphragm, and increased anterior wall tone. With the same gas load, patients developed significantly more abdominal distension; this was associated with paradoxical contraction of the diaphragm and relaxation of the internal oblique muscle. In this experimental provocation model, abnormal accommodation of the diaphragm is involved in abdominal distension.

Study on seismic performance of BFRP geogrid reinforced Tibetan rubble wall

NASA Astrophysics Data System (ADS)

Yang, Dan; Jia, Bin; Huang, Hui; Deng, Chuangli

2018-03-01

For the study of BFRP geogrid influence on Tibetan rubble wall seismic performance, in this paper, on the premise of not change the way of traditional masonry, laying and not join geogrid respectively on the the rubble wall, and carries on the cyclic loading experiment on them. The damage characteristics, crack width and seismic performance of the rubble walls with BFRP geogrid are studied. The experimental results show that the deformation of the rubble wall is mainly the shear deformation under the action of horizontal force, and the bearing capacity and energy dissipation capacity of the wall can be improved significantly after joining the geogrid.

On the force-velocity relationship of a bundle of rigid bio-filaments

NASA Astrophysics Data System (ADS)

Perilli, Alessia; Pierleoni, Carlo; Ciccotti, Giovanni; Ryckaert, Jean-Paul

2018-03-01

In various cellular processes, bio-filaments like F-actin and F-tubulin are able to exploit chemical energy associated with polymerization to perform mechanical work against an obstacle loaded with an external force. The force-velocity relationship quantitatively summarizes the nature of this process. By a stochastic dynamical model, we give, together with the evolution of a staggered bundle of Nf rigid living filaments facing a loaded wall, the corresponding force-velocity relationship. We compute the evolution of the model in the infinite wall diffusion limit and in supercritical conditions (monomer density reduced by critical density ρ^ 1>1 ), and we show that this solution remains valid for moderate non-zero values of the ratio between the wall diffusion and the chemical time scales. We consider two classical protocols: the bundle is opposed either to a constant load or to an optical trap setup, characterized by a harmonic restoring force. The constant load case leads, for each F value, to a stationary velocity Vs t a t(F ;Nf,ρ^ 1 ) after a relaxation with characteristic time τmicro(F). When the bundle (initially taken as an assembly of filament seeds) is subjected to a harmonic restoring force (optical trap load), the bundle elongates and the load increases up to stalling over a characteristic time τOT. Extracted from this single experiment, the force-velocity VO T(F ;Nf,ρ^ 1 ) curve is found to coincide with Vs t a t(F ;Nf,ρ^ 1 ) , except at low loads. We show that this result follows from the adiabatic separation between τmicro and τOT, i.e., τmicro ≪ τOT.

Termites utilise clay to build structural supports and so increase foraging resources

PubMed Central

Oberst, Sebastian; Lai, Joseph C. S.; Evans, Theodore A.

2016-01-01

Many termite species use clay to build foraging galleries and mound-nests. In some cases clay is placed within excavations of their wooden food, such as living trees or timber in buildings; however the purpose for this clay is unclear. We tested the hypotheses that termites can identify load bearing wood, and that they use clay to provide mechanical support of the load and thus allow them to eat the wood. In field and laboratory experiments, we show that the lower termite Coptotermes acinaciformis, the most basal species to build a mound-nest, can distinguish unloaded from loaded wood, and use clay differently when eating each type. The termites target unloaded wood preferentially, and use thin clay sheeting to camouflage themselves while eating the unloaded wood. The termites attack loaded wood secondarily, and build thick, load-bearing clay walls when they do. The termites add clay and build thicker walls as the load-bearing wood is consumed. The use of clay to support wood under load unlocks otherwise unavailable food resources. This behaviour may represent an evolutionary step from foraging behaviour to nest building in lower termites. PMID:26854187

Effect of Premolar Axial Wall Height on Computer-Aided Design/Computer-Assisted Manufacture Crown Retention.

PubMed

Martin, Curt; Harris, Ashley; DuVall, Nicholas; Wajdowicz, Michael; Roberts, Howard Wayne

2018-03-28

To evaluate the effect of premolar axial wall height on the retention of adhesive, full-coverage, computer-aided design/computer-assisted manufacture (CAD/CAM) restorations. A total of 48 premolar teeth randomized into four groups (n = 12 per group) received all-ceramic CAD/CAM restorations with axial wall heights (AWH) of 3, 2, 1, and 0 mm and 16-degree total occlusal convergence (TOC). Specimens were restored with lithium disilicate material and cemented with self-adhesive resin cement. Specimens were loaded to failure after 24 hours. The 3- and 2-mm AWH specimens demonstrated significantly greater failure load. Failure analysis suggests a 2-mm minimum AWH for premolars with a TOC of 16 degrees. Adhesive technology may compensate for compromised AWH.

Behavior of tunnel form buildings under quasi-static cyclic lateral loading

USGS Publications Warehouse

Yuksel, S.B.; Kalkan, E.

2007-01-01

In this paper, experimental investigations on the inelastic seismic behavior of tunnel form buildings (i.e., box-type or panel systems) are presented. Two four-story scaled building specimens were tested under quasi-static cyclic lateral loading in longitudinal and transverse directions. The experimental results and supplemental finite element simulations collectively indicate that lightly reinforced structural walls of tunnel form buildings may exhibit brittle flexural failure under seismic action. The global tension/compression couple triggers this failure mechanism by creating pure axial tension in outermost shear-walls. This type of failure takes place due to rupturing of longitudinal reinforcement without crushing of concrete, therefore is of particular interest in emphasizing the mode of failure that is not routinely considered during seismic design of shear-wall dominant structural systems.

Molecular deformation mechanisms of the wood cell wall material.

PubMed

Jin, Kai; Qin, Zhao; Buehler, Markus J

2015-02-01

Wood is a biological material with outstanding mechanical properties resulting from its hierarchical structure across different scales. Although earlier work has shown that the cellular structure of wood is a key factor that renders it excellent mechanical properties at light weight, the mechanical properties of the wood cell wall material itself still needs to be understood comprehensively. The wood cell wall material features a fiber reinforced composite structure, where cellulose fibrils act as stiff fibers, and hemicellulose and lignin molecules act as soft matrix. The angle between the fiber direction and the loading direction has been found to be the key factor controlling the mechanical properties. However, how the interactions between theses constitutive molecules contribute to the overall properties is still unclear, although the shearing between fibers has been proposed as a primary deformation mechanism. Here we report a molecular model of the wood cell wall material with atomistic resolution, used to assess the mechanical behavior under shear loading in order to understand the deformation mechanisms at the molecular level. The model includes an explicit description of cellulose crystals, hemicellulose, as well as lignin molecules arranged in a layered nanocomposite. The results obtained using this model show that the wood cell wall material under shear loading deforms in an elastic and then plastic manner. The plastic regime can be divided into two parts according to the different deformation mechanisms: yielding of the matrix and sliding of matrix along the cellulose surface. Our molecular dynamics study provides insights of the mechanical behavior of wood cell wall material at the molecular level, and paves a way for the multi-scale understanding of the mechanical properties of wood. Copyright © 2014 Elsevier Ltd. All rights reserved.

The dynamics and control of fluctuating pressure loads in the reattachment region of a supersonic free shear layer

NASA Technical Reports Server (NTRS)

Smits, A. J.

1990-01-01

The primary aim is to investigate the mechanisms which cause the unsteady wall-pressure fluctuations in shock wave turbulent shear layer interactions. The secondary aim is to find means to reduce the magnitude of the fluctuating pressure loads by controlling the unsteady shock motion. The particular flow proposed for study is the unsteady shock wave interaction formed in the reattachment zone of a separated supersonic flow. Similar flows are encountered in many practical situations, and they are associated with high levels of fluctuating wall pressure. Wall pressure fluctuations were measured in the reattachment region of the supersonic free shear layer. The free shear layer was formed by the separation of a Mach 2.9 turbulent boundary layer from a backward facing step. Reattachment occurred on a 20 deg ramp. By adjusting the position of the ramp, the base pressure was set equal to the freestream pressure, and the free shear layer formed in the absence of a separation shock. An array of flush-mounted, miniature, high-frequency pressure transducers was used to make multichannel measurements of the fluctuating wall pressure in the vicinity of the reattachment region. Contrary to previous observations of this flow, the reattachment region was found to be highly unsteady, and the pressure fluctuations were found to be significant. The overall behavior of the wall pressure loading is similar in scale and magnitude to the unsteadiness of the wall pressure field in compression ramp flows at the same Mach number. Rayleigh scattering was used to visualize the instantaneous shock structure in the streamwise and spanwise direction. Spanwise wrinkles on the order of half the boundary layer thickness were observed.

Molecular dynamics study of the behavior of nitromethanes enclosed inside carbon nanotube containers.

PubMed

Bae, Se Won; Cho, Soo Gyeong

2016-07-01

We utilized molecular dynamics (MD) to investigate the behavior of nitromethane molecules (NMs) enclosed inside carbon nanotube (CNT) containers sealed with buckybowl caps. Two different sizes of CNT containers, i.e., (10,10) and (20,20), were employed to contain the energetic NMs. After loading the NMs into these containers, MD simulations were carried out at different loading densities. The loading density was changed from 0.4 to 2.0 g/cc. At low loading densities, NMs preferentially resided near the surface of the CNT wall (orienting themselves in the cylindrical direction) and near the buckybowl caps (orienting themselves in the principal-axis direction). This behavior suggests the buckybowl caps and the CNT wall have attractive interactions with the NMs. The distribution of the NMs inside the containers did not change upon increasing the temperature from ambient to 100 °C. However, the positional preference of the NMs found at ambient temperature to 100 °C was not the same as that observed at 1000 °C due to the increased thermal motions of the NMs. The size of the CNT container had a significant effect on the fluidity of the NMs. From 25 to 100 °C, the NMs inside the (10,10) CNT container were only mobile at low loading densities. On the other hand, in the (20,20) CNT container, the NMs showed good mobility up to a loading density of 1.6 g/cc. Graphical Abstract Attractive interactions between the nitromethanes and the buckybowl caps as well as the carbon nanotube wall.

Numerical 3D flow simulation of ultrasonic horns with attached cavitation structures and assessment of flow aggressiveness and cavitation erosion sensitive wall zones.

PubMed

Mottyll, Stephan; Skoda, Romuald

2016-07-01

As a contribution to a better understanding of cavitation erosion mechanisms, a compressible inviscid finite volume flow solver with barotropic homogeneous liquid-vapor mixture cavitation model is applied to ultrasonic horn set-ups with and without stationary specimen, that exhibit attached cavitation at the horn tip. Void collapses and shock waves, which are closely related to cavitation erosion, are resolved. The computational results are compared to hydrophone, shadowgraphy and erosion test data. At the horn tip, vapor volume and topology, subharmonic oscillation frequency as well as the amplitude of propagating pressure waves are in good agreement with experimental data. For the evaluation of flow aggressiveness and the assessment of erosion sensitive wall zones, statistical analyses of wall loads and of the multiplicity of distinct collapses in wall-adjacent flow regions are applied to the horn tip and the stationary specimen. An a posteriori projection of load collectives, i.e. cumulative collapse rate vs. collapse pressure, onto a reference grid eliminates the grid dependency effectively for attached cavitation at the horn tip, whereas a significant grid dependency remains at the stationary specimen. The load collectives show an exponential decrease towards higher collapse pressures. Erosion sensitive wall zones are well predicted for both, horn tip and stationary specimen, and load profiles are in good qualitative agreement with measured topography profiles of eroded duplex stainless steel samples after long-term runs. For the considered amplitude and gap width according to ASTM G32-10 standard, the analysis of load collectives reveals that the distinctive erosive ring shape at the horn tip can be attributed to frequent breakdown and re-development of a small portion of the tip-attached cavity. This partial breakdown of the attached cavity repeats at each driving cycle and is associated with relatively moderate collapse peak pressures, whereas the stationary specimen is rather unfrequently stressed at the end of each subharmonic oscillation cycle by the violent collapse of the complete cavity. Copyright © 2016 Elsevier B.V. All rights reserved.

Full-scale testing and numerical modeling of a multistory masonry structure subjected to internal blast loading

NASA Astrophysics Data System (ADS)

Zapata, Brian Jarvis

As military and diplomatic representatives of the United States are deployed throughout the world, they must frequently make use of local, existing facilities; it is inevitable that some of these will be load bearing unreinforced masonry (URM) structures. Although generally suitable for conventional design loads, load bearing URM presents a unique hazard, with respect to collapse, when exposed to blast loading. There is therefore a need to study the blast resistance of load bearing URM construction in order to better protect US citizens assigned to dangerous locales. To address this, the Department of Civil and Environmental Engineering at the University of North Carolina at Charlotte conducted three blast tests inside a decommissioned, coal-fired, power plant prior to its scheduled demolition. The power plant's walls were constructed of URM and provided an excellent opportunity to study the response of URM walls in-situ. Post-test analytical studies investigated the ability of existing blast load prediction methodologies to model the case of a cylindrical charge with a low height of burst. It was found that even for the relatively simple blast chamber geometries of these tests, simplified analysis methods predicted blast impulses with an average net error of 22%. The study suggested that existing simplified analysis methods would benefit from additional development to better predict blast loads from cylinders detonated near the ground's surface. A hydrocode, CTH, was also used to perform two and three-dimensional simulations of the blast events. In order to use the hydrocode, Jones Wilkins Lee (JWL) equation of state (EOS) coefficients were developed for the experiment's Unimax dynamite charges; a novel energy-scaling technique was developed which permits the derivation of new JWL coefficients from an existing coefficient set. The hydrocode simulations were able to simulate blast impulses with an average absolute error of 34.5%. Moreover, the hydrocode simulations provided highly resolved spatio-temporal blast loading data for subsequent structural simulations. Equivalent single-degree-of-freedom (ESDOF) structural response models were then used to predict the out-of-plane deflections of blast chamber walls. A new resistance function was developed which permits a URM wall to crack at any height; numerical methodologies were also developed to compute transformation factors required for use in the ESDOF method. When combined with the CTH derived blast loading predictions, the ESDOF models were able to predict out-of-plane deflections with reasonable accuracy. Further investigations were performed using finite element models constructed in LS-DYNA; the models used elastic elements combined with contacts possessing a tension/shear cutoff and the ability to simulate fracture energy release. Using the CTH predicted blast loads and carefully selected constitutive parameters, the LS-DYNA models were able to both qualitatively and quantitatively predict blast chamber wall deflections and damage patterns. Moreover, the finite element models suggested several modes of response which cannot be modeled by current ESDOF methods; the effect of these response modes on the accuracy of ESDOF predictions warrants further study.

Chest Wall Diseases: Respiratory Pathophysiology.

PubMed

Tzelepis, George E

2018-06-01

The chest wall consists of various structures that function in an integrated fashion to ventilate the lungs. Disorders affecting the bony structures or soft tissues of the chest wall may impose elastic loads by stiffening the chest wall and decreasing respiratory system compliance. These alterations increase the work of breathing and lead to hypoventilation and hypercapnia. Respiratory failure may occur acutely or after a variable period of time. This review focuses on the pathophysiology of respiratory function in specific diseases and disorders of the chest wall, and highlights pathogenic mechanisms of respiratory failure. Copyright © 2018 Elsevier Inc. All rights reserved.

Impact and mitigation of disruptions with the ITER-like wall in JET

NASA Astrophysics Data System (ADS)

Lehnen, M.; Arnoux, G.; Brezinsek, S.; Flanagan, J.; Gerasimov, S. N.; Hartmann, N.; Hender, T. C.; Huber, A.; Jachmich, S.; Kiptily, V.; Kruezi, U.; Matthews, G. F.; Morris, J.; Plyusnin, V. V.; Reux, C.; Riccardo, V.; Sieglin, B.; de Vries, P. C.; EFDA Contributors, JET

2013-09-01

Disruptions are a critical issue for ITER because of the high thermal and magnetic energies that are released on short timescales, which results in extreme forces and heat loads. The choice of material of the plasma-facing components (PFCs) can have significant impact on the loads that arise during a disruption. With the ITER-like wall (ILW) in JET made of beryllium in the main chamber and tungsten in the divertor, the main finding is a low fraction of radiation. This has dropped significantly with the ILW from 50-100% of the total energy being dissipated during disruptions in CFC wall plasmas, to less than 50% on average and down to just 10% for vertical displacement events (VDEs). All other changes in disruption properties and loads are consequences of this low radiation: long current quenches (CQs), high vessel forces caused by halo currents and toroidal current asymmetries as well as severe heat loads. Temperatures close to the melting limit have been locally observed on upper first wall structures during deliberate VDE and even at plasma currents as low as 1.5 MA and thermal energy of about 1.5 MJ only. A high radiation fraction can be regained by massive injection of a mixture of 10% Ar with 90% D2. This accelerates the CQ thus reducing the halo current and sideways impulse. The temperature of PFCs stays below 400 °C. MGI is now a mandatory tool to mitigate disruptions in closed-loop operation for currents at and above 2.5 MA in JET.

Geotechnical LFRD calculations of settlement and bearing capacity of GDOT shallow bridge foundations and retaining walls.

DOT National Transportation Integrated Search

2016-08-09

The AASHTO codes for Load Resistance Factored Design (LRFD) regarding shallow bridge foundations : and walls have been implemented into a set of spreadsheet algorithms to facilitate the calculations of bearing : capacity and footing settlements on na...

Consideration of critical axial properties of pristine and defected carbon nanotubes under compression.

PubMed

Ranjbartoreh, A R; Su, D; Wang, G

2012-06-01

Carbon nanotubes are hexagonally configured carbon atoms in cylindrical structures. Exceptionally high mechanical strength, electrical conductivity, surface area, thermal stability and optical transparency of carbon nanotubes outperformed other known materials in numerous advanced applications. However, their mechanical behaviors under practical loading conditions remain to be demonstrated. This study investigates the critical axial properties of pristine and defected single- and multi-walled carbon nanotubes under axial compression. Molecular dynamics simulation method has been employed to consider the destructive effects of Stone-Wales and atom vacancy defects on mechanical properties of armchair and zigzag carbon nanotubes under compressive loading condition. Armchair carbon nanotube shows higher axial stability than zigzag type. Increase in wall number leads to less susceptibility of multi-walled carbon nanotubes to defects and higher stability of them under axial compression. Atom vacancy defect reveals higher destructive effect than Stone-Wales defect on mechanical properties of carbon nanotubes. Critical axial strain of single-walled carbon nanotube declines by 67% and 26% due to atom vacancy and Stone-Wales defects.

Static in-plane shear behaviour of prefabricated wood-wool panel wallettes

NASA Astrophysics Data System (ADS)

Noh, M. S. Md; Ahmad, Z.; Ibrahim, A.; Kamarudin, A. F.; Mokhatar, S. N.

2018-04-01

The green construction material and technique are the current issue toward improving sustainability in the construction industry in Malaysia. The use of construction material that produced from renewable resources is a part of the effort for greening this industry. WWCP (Wood-wool cement panel) is a wood based product available to the construction industry to be used as a structural building wall element. This renewable material has the potential to replace the less eco-friendly materials such as bricks and other masonry element. However, the behaviour of wall subjected to the different load conditions is not well established and therefore, this study aimed to investigate the structural behaviour of the small scale wall (wallettes) subjected to in-plane lateral load. As a comparison, two types of fabrication technique of wallettes with dimension of 1200 mm × 1200 mm (± 30 mm) were considered. The conventional vertical stacking technique was denoted as W1 and new propose techniques (cross laminated) was denoted as W2. Three replicates of each type were fabricated and tested under in-plane lateral load until failure. The test results revealed that, the wallettes fabricated using the new fabrication technique significantly increased two times in load carrying capacity compared to wallettes with conventional technique.

Lateral Torsional Buckling of Anisotropic Laminated Composite Beams Subjected to Various Loading and Boundary Conditions

NASA Astrophysics Data System (ADS)

Ahmadi, Habiburrahman

Thin-walled structures are major components in many engineering applications. When a thin-walled slender beam is subjected to lateral loads, causing moments, the beam may buckle by a combined lateral bending and twisting of cross-section, which is called lateral-torsional buckling. A generalized analytical approach for lateral-torsional buckling of anisotropic laminated, thin-walled, rectangular cross-section composite beams under various loading conditions (namely, pure bending and concentrated load) and boundary conditions (namely, simply supported and cantilever) was developed using the classical laminated plate theory (CLPT), with all considered assumptions, as a basis for the constitutive equations. Buckling of such type of members has not been addressed in the literature. Closed form buckling expressions were derived in terms of the lateral, torsional and coupling stiffness coefficients of the overall composite. These coefficients were obtained through dimensional reduction by static condensation of the 6x6 constitutive matrix mapped into an effective 2x2 coupled weak axis bending-twisting relationship. The stability of the beam under different geometric and material parameters, like length/height ratio, ply thickness, and ply orientation, was investigated. The analytical formulas were verified against finite element buckling solutions using ABAQUS for different lamination orientations showing excellent accuracy.

Carbon nanotubes as VEGF carriers to improve the early vascularization of porcine small intestinal submucosa in abdominal wall defect repair

PubMed Central

Liu, Zhengni; Feng, Xueyi; Wang, Huichun; Ma, Jun; Liu, Wei; Cui, Daxiang; Gu, Yan; Tang, Rui

2014-01-01

Insufficient early vascularization in biological meshes, resulting in limited host tissue incorporation, is thought to be the primary cause for the failure of abdominal wall defect repair after implantation. The sustained release of exogenous angiogenic factors from a biocompatible nanomaterial might be a way to overcome this limitation. In the study reported here, multiwalled carbon nanotubes (MWNT) were functionalized by plasma polymerization to deliver vascular endothelial growth factor165 (VEGF165). The novel VEGF165-controlled released system was incorporated into porcine small intestinal submucosa (PSIS) to construct a composite scaffold. Scaffolds incorporating varying amounts of VEGF165-loaded functionalized MWNT were characterized in vitro. At 5 weight percent MWNT, the scaffolds exhibited optimal properties and were implanted in rats to repair abdominal wall defects. PSIS scaffolds incorporating VEGF165-loaded MWNT (VEGF–MWNT–PSIS) contributed to early vascularization from 2–12 weeks postimplantation and obtained more effective collagen deposition and exhibited improved tensile strength at 24 weeks postimplantation compared to PSIS or PSIS scaffolds, incorporating MWNT without VEGF165 loading (MWNT–PSIS). PMID:24648727

Overview of the JET results with the ITER-like wall

NASA Astrophysics Data System (ADS)

Romanelli, F.; EFDA Contributors, JET

2013-10-01

Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Zeff (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H98,y2 close to 1 and βN ˜ 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.

Investigation of Tokamak Solid Divertor Target Options.

DTIC Science & Technology

1981-05-26

but materials are not known which could operate at the high resulting wall temperatures . Mist- steam flows would also demand a relatively high ...flux P = coolant density = bulk coolant viscosity w = coolant viscosity at average wall temperature = units conversion At high heat loads and moderate...therefore, the inner wall temperature will be over 300 OF, posing a high temp- erature materials challenge. E. Swirl and Mixed Flow Schemes Extensive work

Simplified Dynamic Structural Time History Response Analysis of Flexible Approach Walls Founded on Clustered Pile Groups Using Impact_Deck

DTIC Science & Technology

2016-07-01

Abstract Flexible approach walls are being considered for retrofits, replacements, or upgrades to Corps lock structures that have exceeded their...case of Lock and Dam 3, the peak reaction force for any individual pile group was 11% of the peak impact load. DISCLAIMER: The contents of this...Generation Flexible Approach Walls ......................................... 1 1.2.1 Lock and Dam 3

Capturing strain localization behind a geosynthetic-reinforced soil wall

NASA Astrophysics Data System (ADS)

Lai, Timothy Y.; Borja, Ronaldo I.; Duvernay, Blaise G.; Meehan, Richard L.

2003-04-01

This paper presents the results of finite element (FE) analyses of shear strain localization that occurred in cohesionless soils supported by a geosynthetic-reinforced retaining wall. The innovative aspects of the analyses include capturing of the localized deformation and the accompanying collapse mechanism using a recently developed embedded strong discontinuity model. The case study analysed, reported in previous publications, consists of a 3.5-m tall, full-scale reinforced wall model deforming in plane strain and loaded by surcharge at the surface to failure. Results of the analysis suggest strain localization developing from the toe of the wall and propagating upward to the ground surface, forming a curved failure surface. This is in agreement with a well-documented failure mechanism experienced by the physical wall model showing internal failure surfaces developing behind the wall as a result of the surface loading. Important features of the analyses include mesh sensitivity studies and a comparison of the localization properties predicted by different pre-localization constitutive models, including a family of three-invariant elastoplastic constitutive models appropriate for frictional/dilatant materials. Results of the analysis demonstrate the potential of the enhanced FE method for capturing a collapse mechanism characterized by the presence of a failure, or slip, surface through earthen materials.

Hollow-core FRP-concrete-steel bridge columns under extreme loading.

DOT National Transportation Integrated Search

2015-04-01

This report presents the behavior of hollow-core fiber reinforced polymer concrete - steel columns (HC-FCS) under : combined axial-flexural as well as vehicle collision loads. The HC-FCS column consists of a concrete wall sandwiched between an ou...

Isotropic thin-walled pressure vessel experiment

NASA Technical Reports Server (NTRS)

Denton, Nancy L.; Hillsman, Vernon S.

1992-01-01

The objectives are: (1) to investigate the stress and strain distributions on the surface of a thin walled cylinder subject to internal pressure and/or axial load; and (2) to relate stress and strain distributions to material properties and cylinder geometry. The experiment, supplies, and procedure are presented.

Structural characteristics of methylsilsesquioxane based porous low-k thin films fabricated with increasing cross-linked particle porogen loading

NASA Astrophysics Data System (ADS)

Lee, Hae-Jeong; Soles, Christopher L.; Liu, Da-Wei; Bauer, Barry J.; Lin, Eric K.; Wu, Wen-Li; Gallagher, Michael

2006-09-01

Methylsilsesquioxane (MSQ) based porous low-k dielectric films are characterized by x-ray porosimetry (XRP) to determine their pore size distribution, average density, wall density, and porosity. By varying the porogen content from 1% to 30% by mass, the porosity changes from 12% to 34% by volume, indicating that the base MSQ matrix material contains approximately 10% by volume inherent microporosity. The wall density of this matrix material is measured to be 1.33-1.35g/cm3, independent of porosity. The average pore radii determined from the XRP adsorption isotherms increase from 6to27Å with increased porogen loadings. Small angle neutron scattering measurements confirm these XRP average pore radii for the films with porogen loading higher than 10% by mass.

Self-assembling segmented coiled tubing

DOEpatents

Raymond, David W.

2016-09-27

Self-assembling segmented coiled tubing is a concept that allows the strength of thick-wall rigid pipe, and the flexibility of thin-wall tubing, to be realized in a single design. The primary use is for a drillstring tubular, but it has potential for other applications requiring transmission of mechanical loads (forces and torques) through an initially coiled tubular. The concept uses a spring-loaded spherical `ball-and-socket` type joint to interconnect two or more short, rigid segments of pipe. Use of an optional snap ring allows the joint to be permanently made, in a `self-assembling` manner.

Strength Design of Reinforced Concrete Hydraulic Structures; Report 3, T-Wall Design.

DTIC Science & Technology

1982-01-01

A8 Flexure and Axial Load ..... ................ A10 Shear Strength Requirement ..... ............. A21 TABLE Al APPENDIX B: EFFECT OF...load, earthquake load, and other structural effects of differ- ential settlement, creep, shrinkage, and temperature change. Dead load (D) 10. The...considered to be equal to the depth of the plane below the ground sur- face multiplied by the average unit weight of the soil. Because of the buoyant effect

Magnetically-induced forces on a ferromagnetic HT-9 first wall/blanket module

NASA Astrophysics Data System (ADS)

Lechtenberg, T. A.; Dahms, C. F.; Attaya, H.

1984-05-01

A model of the Starfire commercial tokamak reactor was used as the basis for calculating magnetic loads induced on typical fusion reactor first wall components fabricated of ferromagnetic material. The component analyzed was the first wall/blanket module because this structure experiences the greatest neutron fluence level and is the component for which the low swelling ferromagnetic Sandvik alloy, HT-9, may have the greatest benefit. The magnitudes of the magnetic body forces calculated were consistent with analyses performed on structures within other types of reactors. The loads generated within the module structure by the magnetic forces were found to be of the same order of magnitude as those arising from other sources such as pressure differential, dead weight, temperature distribution. Only small structural design modifications would be required if the magnetic alloy, Sandvik HT-9 were utilized.

A thermoelastic transversely isotropic thick walled cylinder/disk application: An analytical solution and study

NASA Technical Reports Server (NTRS)

Arnold, S. M.

1989-01-01

A continuum theory is utilized to represent the thermoelastic behavior of a thick walled composite cylinder that can be idealized as transversely isotropic. A multiaxial statement of the constitutive theory employed is presented, as well as the out of the plane of isotropy, plane stress, and plane strain reductions. The derived analytical solution presented is valid for a cylindrical tube or thin disk with a concentric hole, subjected to internal and/or external pressure and a general radial temperature distribution. A specific problem examined is that of a thick walled cylinder subjected to an internal and external pressure loading and a linear radial temperature distribution. The results are expressed in nondimensional form and the effects on the response behavior are examined for various material properties, fiber orientation and types of loadings.

Structural and mechanical design of tissue interfaces in the giant reed Arundo donax.

PubMed

Rüggeberg, Markus; Burgert, Ingo; Speck, Thomas

2010-03-06

The culms of the giant reed Arundo donax represent slender tube-like structures. Several nodes along the culm, a ring of sclerenchymatous fibres in the periphery of the culm wall and numerous isolated vascular bundles enclosed by fibre rings in the culm wall function as stiffening elements. The bundles are embedded in lignified parenchyma. Micromechanical analysis indicated differences in stiffness between the individual tissues of more than one order of magnitude. In case of abrupt transitions in stiffness at the interfaces, stress discontinuities arise under dynamic loads. This eventually leads to critical shear stresses at cell ends, and culm failure may be initiated at these points. Pronounced mechanical differences between individual tissues can be compromised by gradual transitions at their interfaces. Ultrastructural and spectroscopic investigations with high spatial resolution revealed a gradual transition of cell parameters (cell wall area fraction and cell length). However, cell wall parameters (cellulose microfibril angle and lignin content) showed abrupt transitions or remained almost constant across the interfaces between various tissues. The design principles found at the interfaces between tissues in the culm walls of A. donax are discussed as an adaptation strategy to mechanical loads at different levels of hierarchy.

Structural and mechanical design of tissue interfaces in the giant reed Arundo donax

PubMed Central

Rüggeberg, Markus; Burgert, Ingo; Speck, Thomas

2010-01-01

The culms of the giant reed Arundo donax represent slender tube-like structures. Several nodes along the culm, a ring of sclerenchymatous fibres in the periphery of the culm wall and numerous isolated vascular bundles enclosed by fibre rings in the culm wall function as stiffening elements. The bundles are embedded in lignified parenchyma. Micromechanical analysis indicated differences in stiffness between the individual tissues of more than one order of magnitude. In case of abrupt transitions in stiffness at the interfaces, stress discontinuities arise under dynamic loads. This eventually leads to critical shear stresses at cell ends, and culm failure may be initiated at these points. Pronounced mechanical differences between individual tissues can be compromised by gradual transitions at their interfaces. Ultrastructural and spectroscopic investigations with high spatial resolution revealed a gradual transition of cell parameters (cell wall area fraction and cell length). However, cell wall parameters (cellulose microfibril angle and lignin content) showed abrupt transitions or remained almost constant across the interfaces between various tissues. The design principles found at the interfaces between tissues in the culm walls of A. donax are discussed as an adaptation strategy to mechanical loads at different levels of hierarchy. PMID:19726440

Design and Fabrication of a Ring-Stiffened Graphite-Epoxy Corrugated Cylindrical Shell

NASA Technical Reports Server (NTRS)

Johnson, R., Jr.

1978-01-01

Design and fabrication of supplement test panels that represent key portions of the cylinder are described, as are supporting tests of coupons, sample joints, and stiffening ring elements. The cylindrical shell is a ring-stiffened, open corrugation design that uses T300/5208 graphite-epoxy tape as the basic material for the shell wall and stiffening rings. The test cylinder is designed to withstand bending loads producing the relatively low maximum load intensity in the shell wall of 1,576 N/cm. The resulting shell wall weight, including stiffening rings and fasteners, is 0.0156 kg/m. The shell weight achieved in the graphite-epoxy cylinder represents a weight saving of approximately 23 percent, compared to a comparable aluminum shell. A unique fabrication approach was used in which the cylinder wall was built in three flat segments, which were then wrapped to the cylindrical shape. Such an approach, made possible by the flexibility of the thin corrugated wall in a radial direction, proved to be a simple approach to building the test cylinder. Based on tooling and fabrication methods in this program, the projected costs of a production run of 100 units are reported.

Control of Mechanical Stresses of High Pressure Container Walls by Magnetoelastic Method

NASA Astrophysics Data System (ADS)

Kulak, S. M.; Novikov, V. F.; Baranov, A. V.

2016-10-01

Deformations of the walls of pressure vessels arising in the process of testing and operation, as well as reduce their thickness due to corrosion, to create the prerequisites for the growth of mechanical stresses which accelerating the processes of strain aging, embrittlement of the material and reducing its fatigue properties. This article is devoted to researches of the magnetoelastic demagnetization in the wall of steel vessel of loading by internal pressure. It is established that the increasing pressure on the vessel wall is accompanied by a monotonic decrease in the intensity of the magnetic stray field of local magnetization of steel. It is shown that a magnetic stray field of local magnetization of the wall of steel vessel is non-uniform due to differences in structure and stresses. It is proposed to use the obtained results to control the stress state of vessels, experiencing multi-axial loads generated by internal pressure (pipelines, oil tanks, etc.) The method of magnetoelastic of the demagnetization of the steel has a high sensitivity to mechanical stress, the simplicity of implementation and expressiveness compared to the strain gauge and method of coercive force.

The effect of variable size posterior wall acetabular fractures on contact characteristics of the hip joint.

PubMed

Olson, S A; Bay, B K; Pollak, A N; Sharkey, N A; Lee, T

1996-01-01

The indications for open reduction and internal fixation of posterior wall acetabular fractures associated with a clinically stable hip joint are unclear. In previous work a large posterior wall defect (27% articular surface area) resulted in significant alteration of load transmission across the hip; specifically, there was a transition from evenly distributed loading along the acetabular articular surface to loading concentrated mainly in the superior portion of the articular surface during simulated single leg stance. However, the majority of posterior wall fractures involve a smaller amount of the articular surface. Posterior wall acetabular fractures not associated with instability of the hip are commonly treated nonoperatively. This practice does not account for the size of the posterior wall fracture. To study the biomechanical consequences of variably sized articular defects, a laboratory experiment was conducted evaluating three progressively larger posterior wall defects of the acetabulum during simulated single leg stance using superlow Fuji prescale film (Itochu International, New York): (a) 1/3 articular surface width through a 50 degrees arc along the posterior wall of the acetabulum, (b) 2/3, and (c) 3/3 articular width defects through the same 50 degrees arc along the posterior wall of the acetabulum. In the intact acetabulum, 48% of the total articular contact was located in the superior acetabulum. Twenty-eight percent of articular contact was in the anterior wall region of the acetabulum and 24% in the posterior wall region. After the 1/3 width posterior wall defect, 64% of the articular contact was located in the superior acetabulum (p = 0.0011). The 2/3 width posterior wall defect resulted in 71% of articular contact area being located in the superior acetabulum (p = 0.0006). After the 3/3 width posterior wall defect, 77% of articular contact was located in the superior acetabulum, significantly greater than the intact condition (p < 0.0001) and 1/3 width defect (p = 0.0222). The total absolute contact areas for all defect conditions were significantly less than the intact conditions. The results of this study reconfirm the observation that posterior wall fractures of the acetabulum significantly alter the articular contact characteristics in the hip during single leg stance. The relationship between defect size and changes in joint contact showed that the smallest defect resulted in the greatest alteration in joint contact areas, whereas larger defects resulted in minor increments of change in contact area. This finding is of concern because the clinical practice of managing acetabular fractures nonoperatively if the hip joint is stable is based on the supposition that the joint retains enough integrity to function without undue risk of late posttraumatic osteoarthritis. A better understanding of the natural history of stable posterior wall acetabular fractures is needed to ascertain whether some of these fractures merit operative repair.

Calculations of Wall Effects on Propeller Noise

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Eversman, Walter

1987-01-01

Reverberations affect sound levels in wind tunnels. Report describes calculations of acoustic field of propeller in wind tunnel having walls of various degrees of softness. Understanding provided by this and related studies necessary for correct interpretation of wind-tunnel measurements of noise generated by high speed, highly loaded, multiple-blade turbopropellers.

Design of mechanically stabilized earth wall connections and end of walls subjected to seismic loads.

DOT National Transportation Integrated Search

2014-01-01

The 4th Edition of the AASHTO LRFD Bridge Design Specifications requires all states to design for a 1,000- : year return period earthquake, as opposed to earlier editions 500-year return period. In response to this : requirement, the Colorado Depa...

Development of a real-time system for ITER first wall heat load control

NASA Astrophysics Data System (ADS)

Anand, Himank; de Vries, Peter; Gribov, Yuri; Pitts, Richard; Snipes, Joseph; Zabeo, Luca

2017-10-01

The steady state heat flux on the ITER first wall (FW) panels are limited by the heat removal capacity of the water cooling system. In case of off-normal events (e.g. plasma displacement during H-L transitions), the heat loads are predicted to exceed the design limits (2-4.7 MW/m2). Intense heat loads are predicted on the FW, even well before the burning plasma phase. Thus, a real-time (RT) FW heat load control system is mandatory from early plasma operation of the ITER tokamak. A heat load estimator based on the RT equilibrium reconstruction has been developed for the plasma control system (PCS). A scheme, estimating the energy state for prescribed gaps defined as the distance between the last closed flux surface (LCFS)/separatrix and the FW is presented. The RT energy state is determined by the product of a weighted function of gap distance and the power crossing the plasma boundary. In addition, a heat load estimator assuming a simplified FW geometry and parallel heat transport model in the scrape-off layer (SOL), benchmarked against a full 3-D magnetic field line tracer is also presented.

Buckling Behavior of Compression-Loaded Composite Cylindrical Shells With Reinforced Cutouts

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.; Sarnes, James H., Jr.

2004-01-01

Results from a numerical study of the response of thin-walled compression-loaded quasi-isotropic laminated composite cylindrical shells with unreinforced and reinforced square cutouts are presented. The effects of cutout reinforcement orthotropy, size, and thickness on the nonlinear response of the shells are described. A nonlinear analysis procedure has been used to predict the nonlinear response of the shells. The results indicate that a local buckling response occurs in the shell near the cutout when subjected to load and is caused by a nonlinear coupling between local shell-wall deformations and in-plane destabilizing compression stresses near the cutout. In general, reinforcement around a cutout in a compression-loaded shell is shown to retard or eliminate the local buckling response near the cutout and increase the buckling load of the shell. However, some results show that certain reinforcement configurations can cause an unexpected increase in the magnitude of local deformations and stresses in the shell and cause a reduction in the buckling load. Specific cases are presented that suggest that the orthotropy, thickness, and size of a cutout reinforcement in a shell can be tailored to achieve improved buckling response characteristics.

Thermocryogenic buckling and stress analyses of a partially filled cryogenic tank subjected to cylindrical strip heating

NASA Technical Reports Server (NTRS)

Ko, William L.

1994-01-01

Thermocryogenic buckling and stress analyses were conducted on a horizontally oriented cryogenic tank using the finite element method. The tank is a finite-length circular cylindrical shell with its two ends capped with hemispherical shells. The tank is subjected to cylindrical strip heating in the region above the liquid-cryogen fill level and to cryogenic cooling below the fill level (i.e., under thermocryogenic loading). The effects of cryogen fill level on the buckling temperature and thermocryogenic stress field were investigated in detail. Both the buckling temperature and stress magnitudes were relatively insensitive to the cryogen fill level. The buckling temperature, however, was quite sensitive to the radius-to-thickness ratio. A mechanical stress analysis of the tank also was conducted when the tank was under: (1) cryogen liquid pressure loading; (2) internal pressure loading; and (3) tank-wall inertia loading. Deformed shapes of the cryogenic tanks under different loading conditions were shown, and high-stress domains were mapped on the tank wall for the strain-gage installations. The accuracies of solutions from different finite element models were compared.

Sensitivity of dual-wall structures under hypervelocity impact to multi-layer thermal insulation thickness and placement

NASA Astrophysics Data System (ADS)

Schonberg, William P.

1993-04-01

Results are presented from an experimental study in which Al dual-wall structures were tested, under various high-speed impact conditions, with a view to the effect of multilayer insulation thickness and location on perforation resistance. Attention is given to comparisons of the damage sustained by dual-wall systems with multilayer insulation blankets of various thicknesses and at various locations within the dual-wall system, under comparable impact loading conditions. The placement of the insulation has a significant effect on the ballistic limit of the dual-wall structures considered, while reducing insulation thickness by as much as a third did not.

An experimental study on compressive behavior of rubble stone walls retrofitted with BFRP grids

NASA Astrophysics Data System (ADS)

Huang, Hui; Jia, Bin; Li, Wenjing; Liu, Xiao; Yang, Dan; Deng, Chuanli

2018-03-01

An experimental study was conducted to investigate the compressive behavior of rubble stone walls retrofitted with BFRP grids. The experimental program consisted of four rubble stone walls: one unretrofitted rubble stone wall (reference wall) and three BFRP grids retrofitted rubble stone walls. The main purpose of the tests was to gain a better understanding of the compressive behavior of rubble stone walls retrofitted with different amount of BFRP grids. The experimental results showed that the reference wall failed with out-of-plane collapse due to poor connection between rubble stone blocks and the three BFRP grids retrofitted walls failed with BFRP grids rupture followed by out-of-plane collapse. The measured compressive strength of the BFRP grids retrofitted walls is about 1.4 to 2.5 times of that of the reference wall. Besides, the rubble stone wall retrofitted with the maximum amount of BFRP grids showed the minimum vertical and out-of-plane displacements under the same load.

Inter-wall bridging induced peeling of multi-walled carbon nanotubes during tensile failure in aluminum matrix composites.

PubMed

Chen, Biao; Li, Shufeng; Imai, Hisashi; Umeda, Junko; Takahashi, Makoto; Kondoh, Katsuyoshi

2015-02-01

In situ scanning electron microscopy (SEM) observation of a tensile test was performed to investigate the fracturing behavior of multi-walled carbon nanotubes (MWCNTs) in powder metallurgy Al matrix composites. A multiple peeling phenomenon during MWCNT fracturing was clearly observed. Its formation mechanism and resultant effect on the composite strength were examined. Through transition electron microscopy characterizations, it was observed that defective structures like inter-wall bridges cross-linked adjacent walls of MWCNTs. This structure was helpful to improve the inter-wall bonding conditions, leading to the effective load transfer between walls and resultant peeling behaviors of MWCNTs. These results might provide new understandings of the fracturing mechanisms of carbon nanotube reinforcements for designing high-performance nanocomposites. Copyright © 2014 Elsevier Ltd. All rights reserved.

Composite Behavior of Insulated Concrete Sandwich Wall Panels Subjected to Wind Pressure and Suction.

PubMed

Choi, Insub; Kim, JunHee; Kim, Ho-Ryong

2015-03-19

A full-scale experimental test was conducted to analyze the composite behavior of insulated concrete sandwich wall panels (ICSWPs) subjected to wind pressure and suction. The experimental program was composed of three groups of ICSWP specimens, each with a different type of insulation and number of glass-fiber-reinforced polymer (GFRP) shear grids. The degree of composite action of each specimen was analyzed according to the load direction, type of the insulation, and number of GFRP shear grids by comparing the theoretical and experimental values. The failure modes of the ICSWPs were compared to investigate the effect of bonds according to the load direction and type of insulation. Bonds based on insulation absorptiveness were effective to result in the composite behavior of ICSWP under positive loading tests only, while bonds based on insulation surface roughness were effective under both positive and negative loading tests. Therefore, the composite behavior based on surface roughness can be applied to the calculation of the design strength of ICSWPs with continuous GFRP shear connectors.

A simple, effective and clinically applicable method to compute abdominal aortic aneurysm wall stress.

PubMed

Joldes, Grand Roman; Miller, Karol; Wittek, Adam; Doyle, Barry

2016-05-01

Abdominal aortic aneurysm (AAA) is a permanent and irreversible dilation of the lower region of the aorta. It is a symptomless condition that if left untreated can expand to the point of rupture. Mechanically-speaking, rupture of an artery occurs when the local wall stress exceeds the local wall strength. It is therefore desirable to be able to non-invasively estimate the AAA wall stress for a given patient, quickly and reliably. In this paper we present an entirely new approach to computing the wall tension (i.e. the stress resultant equal to the integral of the stresses tangent to the wall over the wall thickness) within an AAA that relies on trivial linear elastic finite element computations, which can be performed instantaneously in the clinical environment on the simplest computing hardware. As an input to our calculations we only use information readily available in the clinic: the shape of the aneurysm in-vivo, as seen on a computed tomography (CT) scan, and blood pressure. We demonstrate that tension fields computed with the proposed approach agree well with those obtained using very sophisticated, state-of-the-art non-linear inverse procedures. Using magnetic resonance (MR) images of the same patient, we can approximately measure the local wall thickness and calculate the local wall stress. What is truly exciting about this simple approach is that one does not need any information on material parameters; this supports the development and use of patient-specific modelling (PSM), where uncertainty in material data is recognised as a key limitation. The methods demonstrated in this paper are applicable to other areas of biomechanics where the loads and loaded geometry of the system are known. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biaxial deformation of collagen and elastin fibers in coronary adventitia

PubMed Central

Chen, Huan; Slipchenko, Mikhail N.; Liu, Yi; Zhao, Xuefeng; Cheng, Ji-Xin; Lanir, Yoram

2013-01-01

The microstructural deformation-mechanical loading relation of the blood vessel wall is essential for understanding the overall mechanical behavior of vascular tissue in health and disease. We employed simultaneous mechanical loading-imaging to quantify in situ deformation of individual collagen and elastin fibers on unstained fresh porcine coronary adventitia under a combination of vessel inflation and axial extension loading. Specifically, the specimens were imaged under biaxial loads to study microscopic deformation-loading behavior of fibers in conjunction with morphometric measurements at the zero-stress state. Collagen fibers largely orientate in the longitudinal direction, while elastin fibers have major orientation parallel to collagen, but with additional orientation angles in each sublayer of the adventitia. With an increase of biaxial load, collagen fibers were uniformly stretched to the loading direction, while elastin fibers gradually formed a network in sublayers, which strongly depended on the initial arrangement. The waviness of collagen decreased more rapidly at a circumferential stretch ratio of λθ = 1.0 than at λθ = 1.5, while most collagen became straightened at λθ = 1.8. These microscopic deformations imply that the longitudinally stiffer adventitia is a direct result of initial fiber alignment, and the overall mechanical behavior of the tissue is highly dependent on the corresponding microscopic deformation of fibers. The microstructural deformation-loading relation will serve as a foundation for micromechanical models of the vessel wall. PMID:24092692

Details of Side Load Test Data and Analysis for a Truncated Ideal Contour Nozzle and a Parabolic Contour Nozzle

NASA Technical Reports Server (NTRS)

Ruf, Joseph H.; McDaniels, David M.; Brown, Andrew M.

2010-01-01

Two cold flow subscale nozzles were tested for side load characteristics during simulated nozzle start transients. The two test article contours were a truncated ideal and a parabolic. The current paper is an extension of a 2009 AIAA JPC paper on the test results for the same two nozzle test articles. The side load moments were measured with the strain tube approach in MSFC s Nozzle Test Facility. The processing techniques implemented to convert the strain gage signals into side load moment data are explained. Nozzle wall pressure profiles for separated nozzle flow at many NPRs are presented and discussed in detail. The effect of the test cell diffuser inlet on the parabolic nozzle s wall pressure profiles for separated flow is shown. The maximum measured side load moments for the two contours are compared. The truncated ideal contour s peak side load moment was 45% of that of the parabolic contour. The calculated side load moments, via mean-plus-three-standard-deviations at each nozzle pressure ratio, reproduced the characteristics and absolute values of measured maximums for both contours. The effect of facility vibration on the measured side load moments is quantified and the effect on uncertainty is calculated. The nozzle contour designs are discussed and the impact of a minor fabrication flaw in the nozzle contours is explained.

Multiscale Investigation from Subcellular to Tissue Scale of Onion Epidermal Plant Cell Wall Mechanical Properties

NASA Astrophysics Data System (ADS)

Zamil, Mohammad Shafayet

The physical and mechanical properties of cell walls, their shape, how they are arranged and interact with each other determine the architecture of plant organs and how they mechanically respond to different environmental and loading conditions. Due to the distinctive hierarchy from subcellular to tissue scale, plant materials can exhibit remarkably different mechanical properties. To date, how the subcellular scale arrangement and the mechanical properties of plant cell wall structural constituents give rise to macro or tissue scale mechanical responses is not yet well understood. Although the tissue scale plant cell wall samples are easy to prepare and put to different types of mechanical tests, the hierarchical features that emerge when moving towards a higher scale make it complicated to link the macro scale results to micro or subcellular scale structural components. On the other hand, the microscale size of cell brings formidable challenges to prepare and grip samples and carry mechanical tests under tensile loading at subcellular scale. This study attempted to develop a set of test protocols based on microelectromechanical system (MEMS) tensile testing devices for characterizing plant cell wall materials at different length scales. For the ease of sample preparation and well established database of the composition and conformation of its structural constituents, onion epidermal cell wall profile was chosen as the study material. Based on the results and findings of multiscale mechanical characterization, a framework of architecture-based finite element method (FEM) computational model was developed. The computational model laid the foundation of bridging the subcellular or microscale to the tissue or macroscale mechanical properties. This study suggests that there are important insights of cell wall mechanics and structural features that can only be investigated by carrying tensile characterization of samples not confounded by extracellular parameters. To the best of our knowledge, the plant cell wall at subcellular scale was never characterized under tensile loading. By coupling the structure based multiscale modeling and mechanical characterizations at different length scales, an attempt was made to provide novel insights towards understanding the mechanics and architecture of cell wall. This study also suggests that a multiscale investigation is essential for garnering fundamental insights into the hierarchical deformation of biological systems.

Method of energy load management using PCM for heating and cooling of buildings

DOEpatents

Stovall, T.K.; Tomlinson, J.J.

1996-03-26

A method is described for energy load management for the heating and cooling of a building. The method involves utilizing a wallboard as a portion of the building, the wallboard containing about 5 to about 30 wt.% phase change material such that melting of the phase change material occurs during a rise in temperature within the building to remove heat from the air, and a solidification of the phase change material occurs during a lowering of the temperature to dispense heat into the air. At the beginning of either of these cooling or heating cycles, the phase change material is preferably ``fully charged``. In preferred installations one type of wallboard is used on the interior surfaces of exterior walls, and another type as the surface on interior walls. The particular PCM is chosen for the desired wall and room temperature of these locations. In addition, load management is achieved by using PCM-containing wallboards that form cavities of the building such that the cavities can be used for the air handling duct and plenum system of the building. Enhanced load management is achieved by using a thermostat with reduced dead band of about the upper half of a normal dead band of over three degrees. In some applications, air circulation at a rate greater than normal convection provides additional comfort. 7 figs.

Method of energy load management using PCM for heating and cooling of buildings

DOEpatents

Stovall, Therese K.; Tomlinson, John J.

1996-01-01

A method of energy load management for the heating and cooling of a building. The method involves utilizing a wallboard as a portion of the building, the wallboard containing about 5 to about 30 wt. % a phase change material such that melting of the phase change material occurs during a rise in temperature within the building to remove heat from the air, and a solidification of the phase change material occurs during a lowering of the temperature to dispense heat into the air. At the beginning of either of these cooling or heating cycles, the phase change material is preferably "fully charged". In preferred installations one type of wallboard is used on the interior surfaces of exterior walls, and another type as the surface on interior walls. The particular PCM is chosen for the desired wall and room temperature of these locations. In addition, load management is achieved by using PCM-containing wallboard that form cavities of the building such that the cavities can be used for the air handling duct and plenum system of the building. Enhanced load management is achieved by using a thermostat with reduced dead band of about the upper half of a normal dead band of over three degree. In some applications, air circulation at a rate greater than normal convection provides additional comfort.

Method of energy load management using PCM for heating and cooling of buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stovall, T.K.; Tomlinson, J.J.

1996-03-26

A method is described for energy load management for the heating and cooling of a building. The method involves utilizing a wallboard as a portion of the building, the wallboard containing about 5 to about 30 wt.% phase change material such that melting of the phase change material occurs during a rise in temperature within the building to remove heat from the air, and a solidification of the phase change material occurs during a lowering of the temperature to dispense heat into the air. At the beginning of either of these cooling or heating cycles, the phase change material ismore » preferably ``fully charged``. In preferred installations one type of wallboard is used on the interior surfaces of exterior walls, and another type as the surface on interior walls. The particular PCM is chosen for the desired wall and room temperature of these locations. In addition, load management is achieved by using PCM-containing wallboards that form cavities of the building such that the cavities can be used for the air handling duct and plenum system of the building. Enhanced load management is achieved by using a thermostat with reduced dead band of about the upper half of a normal dead band of over three degrees. In some applications, air circulation at a rate greater than normal convection provides additional comfort. 7 figs.« less

Effect of electrical and mechanical poling history on domain orientation and piezoelectric properties of soft and hard PZT ceramics

NASA Astrophysics Data System (ADS)

Marsilius, Mie; Granzow, Torsten; Jones, Jacob L.

2011-02-01

The superior piezoelectric properties of all polycrystalline ferroelectrics are based on the extent of non-180° domain wall motion under electrical and mechanical poling loads. To distinguish between 180° and non-180° domain wall motion in a soft-doped and a hard-doped lead zirconate titanate (PZT) ceramic, domain texture measurements were performed using x-ray and neutron diffraction after different loading procedures. Comparing the results to measurements of the remanent strain and piezoelectric coefficient allowed the differentiation between different microstructural contributions to the macroscopic parameters. Both types of ceramic showed similar behavior under electric field, but the hard-doped material was more susceptible to mechanical load. A considerable fraction of the piezoelectric coefficient originated from poling by the preferred orientation of 180° domains.

Numerical 3D flow simulation of attached cavitation structures at ultrasonic horn tips and statistical evaluation of flow aggressiveness via load collectives

NASA Astrophysics Data System (ADS)

Mottyll, S.; Skoda, R.

2015-12-01

A compressible inviscid flow solver with barotropic cavitation model is applied to two different ultrasonic horn set-ups and compared to hydrophone, shadowgraphy as well as erosion test data. The statistical analysis of single collapse events in wall-adjacent flow regions allows the determination of the flow aggressiveness via load collectives (cumulative event rate vs collapse pressure), which show an exponential decrease in agreement to studies on hydrodynamic cavitation [1]. A post-processing projection of event rate and collapse pressure on a reference grid reduces the grid dependency significantly. In order to evaluate the erosion-sensitive areas a statistical analysis of transient wall loads is utilised. Predicted erosion sensitive areas as well as temporal pressure and vapour volume evolution are in good agreement to the experimental data.

Fire development and wall endurance in sandwich and wood-frame structures

Treesearch

Carlton A. Holmes; Herbert W. Eickner; John J. Brenden; Curtis C. Peters; Robert H. White

1980-01-01

Large-scale fire tests were conducted on seven 16- by 24-foot structures. Four of these structures were of sandwich construction with cores of plastic or paper honeycomb and three were of wood-frame construction. The wasss were loaded to a computer design loading, and the fire endurance determined under a fire exposure from a typical building contents loading of 4-1/2...

A Systematic Approach for Determining Vertical Pile Depth of Embedment in Cohensionless Soils to Withstand Lateral Barge Train Impact Loads

DTIC Science & Technology

2017-01-30

dynamic structural time- history response analysis of flexible approach walls founded on clustered pile groups using Impact_Deck. In Preparation, ERDC...research (Ebeling et al. 2012) has developed simplified analysis procedures for flexible approach wall systems founded on clustered groups of vertical...history response analysis of flexible approach walls founded on clustered pile groups using Impact_Deck. In Preparation, ERDC/ITL TR-16-X. Vicksburg, MS

DOE Zero Energy Ready Home Case Study: Palo Duro Homes, Albuquerque, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

none,

2013-09-01

Palo Duro uses advanced framing techniques like 2x6 24-inch on-center framing, open headers above windows on non-load-bearing walls, 2-stud corners, ladder blocking where walls intersect, and single top and bottom plates. These techniques reduce the amount of lumber in the wall, allowing more room for insulation and reducing costs and installation time. The builder garnered a 2013 Housing Innovation Award in the production builder category.

Modified locking thread form for fastener

NASA Technical Reports Server (NTRS)

Roopnarine, (Inventor); Vranish, John D. (Inventor)

1998-01-01

A threaded fastener has a standard part with a standard thread form characterized by thread walls with a standard included angle, and a modified part complementary to the standard part having a modified thread form characterized by thread walls which are symmetrically inclined with a modified included angle that is different from the standard included angle of the standard part's thread walls, such that the threads of one part make pre-loaded edge contact with the thread walls of the other part. The thread form of the modified part can have an included angle that is greater, less, or compound as compared to the included angle of the standard part. The standard part may be a bolt and the modified part a nut, or vice versa. The modified thread form holds securely even under large vibrational forces, it permits bi-directional use of standard mating threads, is impervious to the build up of tolerances and can be manufactured with a wider range of tolerances without loss of functionality, and distributes loading stresses (per thread) in a manner that decreases the possibility of single thread failure.

An Experimental Study on the Shear Hysteresis and Energy Dissipation of the Steel Frame with a Trapezoidal-Corrugated Steel Plate

PubMed Central

Shon, Sudeok; Yoo, Mina; Lee, Seungjae

2017-01-01

The steel frame reinforced with steel shear wall is a lateral load resisting system and has higher strength and shear performance than the concrete shear wall system. Especially, using corrugated steel plates in these shear wall systems improves out-of-plane stiffness and flexibility in the deformation along the corrugation. In this paper, a cyclic loading test of this steel frame reinforced with trapezoidal-corrugated steel plate was performed to evaluate the structural performance. The hysteresis behavior and the energy dissipation capacity of the steel frame were also compared according to the corrugated direction of the plate. For the test, one simple frame model without the wall and two frame models reinforced with the plate are considered and designed. The test results showed that the model reinforced with the corrugated steel plate had a greater accumulated energy dissipation capacity than the experimental result of the non-reinforced model. Furthermore, the energy dissipation curves of two reinforced frame models, which have different corrugated directions, produced similar results. PMID:28772624

High-Fidelity Buckling Analysis of Composite Cylinders Using the STAGS Finite Element Code

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.

2014-01-01

Results from previous shell buckling studies are presented that illustrate some of the unique and powerful capabilities in the STAGS finite element analysis code that have made it an indispensable tool in structures research at NASA over the past few decades. In particular, prototypical results from the development and validation of high-fidelity buckling simulations are presented for several unstiffened thin-walled compression-loaded graphite-epoxy cylindrical shells along with a discussion on the specific methods and user-defined subroutines in STAGS that are used to carry out the high-fidelity simulations. These simulations accurately account for the effects of geometric shell-wall imperfections, shell-wall thickness variations, local shell-wall ply-gaps associated with the fabrication process, shell-end geometric imperfections, nonuniform applied end loads, and elastic boundary conditions. The analysis procedure uses a combination of nonlinear quasi-static and transient dynamic solution algorithms to predict the prebuckling and unstable collapse response characteristics of the cylinders. Finally, the use of high-fidelity models in the development of analysis-based shell-buckling knockdown (design) factors is demonstrated.

An Experimental Study on the Shear Hysteresis and Energy Dissipation of the Steel Frame with a Trapezoidal-Corrugated Steel Plate.

PubMed

Shon, Sudeok; Yoo, Mina; Lee, Seungjae

2017-03-06

The steel frame reinforced with steel shear wall is a lateral load resisting system and has higher strength and shear performance than the concrete shear wall system. Especially, using corrugated steel plates in these shear wall systems improves out-of-plane stiffness and flexibility in the deformation along the corrugation. In this paper, a cyclic loading test of this steel frame reinforced with trapezoidal-corrugated steel plate was performed to evaluate the structural performance. The hysteresis behavior and the energy dissipation capacity of the steel frame were also compared according to the corrugated direction of the plate. For the test, one simple frame model without the wall and two frame models reinforced with the plate are considered and designed. The test results showed that the model reinforced with the corrugated steel plate had a greater accumulated energy dissipation capacity than the experimental result of the non-reinforced model. Furthermore, the energy dissipation curves of two reinforced frame models, which have different corrugated directions, produced similar results.

Lateral pile cap load tests with gravel backfill of limited width.

DOT National Transportation Integrated Search

2010-08-01

This study investigated the increase in passive force produced by compacting a dense granular fill adjacent to a pile cap or abutment wall when the surrounding soil is in a relative loose state. Lateral load tests were performed on a pile cap with th...

Valve for fuel pin loading system

DOEpatents

Christiansen, David W.

1985-01-01

A cyclone valve surrounds a wall opening through which cladding is projected. An axial valve inlet surrounds the cladding. Air is drawn through the inlet by a cyclone stream within the valve. An inflatable seal is included to physically engage a fuel pin subassembly during loading of fuel pellets.

Numerical nonlinear inelastic analysis of stiffened shells of revolution. Volume 1: Theory manual for STARS-2P digital computer program

NASA Technical Reports Server (NTRS)

Svalbonas, V.; Levine, H.

1975-01-01

The theoretical analysis background for the STARS-2P nonlinear inelastic program is discussed. The theory involved is amenable for the analysis of large deflection inelastic behavior in axisymmetric shells of revolution subjected to axisymmetric loadings. The analysis is capable of considering such effects as those involved in nonproportional and cyclic loading conditions. The following are also discussed: orthotropic nonlinear kinematic hardening theory; shell wall cross sections and discrete ring stiffeners; the coupled axisymmetric large deflection elasto-plastic torsion problem; and the provision for the inelastic treatment of smeared stiffeners, isogrid, and waffle wall constructions.

Inhibitory effect of cervical trachea and chest wall vibrations on cough reflex sensitivity and perception of urge-to-cough in healthy male never-smokers

PubMed Central

2013-01-01

Background Non-pharmacological options for symptomatic management of cough are desired. Although chest wall mechanical vibration is known to ameliorate cough reflex sensitivity, the effect of mechanical vibrations on perceptions of urge-to-cough has not been studied. Therefore, we investigated the effect of mechanical vibration of cervical trachea, chest wall and femoral muscle on cough reflex sensitivity, perceptions of urge-to-cough as well as dyspnea. Methods Twenty-four healthy male never-smokers were investigated for cough reflex sensitivity, perceptions of the urge-to-cough and dyspnea with or without mechanical vibration. Cough reflex sensitivity and urge-to-cough were evaluated by the inhalation of citric acid. The perception of dyspnea was evaluated by Borg scores during applications of external inspiratory resistive loads. Mechanical vibration was applied by placing a vibrating tuning fork on the skin surface of cervical trachea, chest wall and femoral muscle. Results Cervical trachea vibration significantly increased cough reflex threshold, as expressed by the lowest concentration of citric acid that elicited five or more coughs (C5), and urge-to-cough threshold, as expressed by the lowest concentration of citric acid that elicited urge-to-cough (Cu), but did not significantly affect dypnea sensation during inspiratory resistive loading. On the other hand, the chest wall vibration not only significantly increased C5 and Cu but also significantly ameliorated the load-response curve of dyspnea sensation. Conclusions Both cervical and trachea vibrations significantly inhibited cough reflex sensitivity and perception of urge-to-cough. These vibration techniques might be options for symptomatic cough management. PMID:24088411

Lunar Return Reentry Thermal Analysis of a Generic Crew Exploration Vehicle Wall Structures

NASA Technical Reports Server (NTRS)

Ko, William L.; Tran, Van T.; Bowles, Jeff

2007-01-01

Thermostructural analysis was performed on generic crew exploration vehicle (GCEV) heat shielded wall structures subjected to reentry heating rates based on five potential lunar return reentry trajectories. The GCEV windward outer wall is fabricated with a graphite/epoxy composite honeycomb sandwich panel and the inner wall with an aluminum honeycomb sandwich panel. The outer wall is protected with an ablative Avcoat-5026-39H/CG thermal protection system (TPS). A virtual ablation method (a graphical approximation) developed earlier was further extended, and was used to estimate the ablation periods, ablation heat loads, and the TPS recession layer depths. It was found that up to 83 95 percent of the total reentry heat load was dissipated in the TPS ablation process, leaving a small amount (3-15 percent) of the remaining total reentry heat load to heat the virgin TPS and maintain the TPS surface at the ablation temperature, 1,200 F. The GCEV stagnation point TPS recession layer depths were estimated to be in the range of 0.280-0.910 in, and the allowable minimum stagnation point TPS thicknesses that could maintain the substructural composite sandwich wall at the limit temperature of 300 F were found to be in the range of 0.767-1.538 in. Based on results from the present analyses, the lunar return abort ballistic reentry was found to be quite attractive because it required less TPS weight than the lunar return direct, the lunar return skipping, or the low Earth orbit guided reentry, and only 11.6 percent more TPS weight than the low Earth orbit ballistic reentry that will encounter a considerable weight penalty to obtain the Earth orbit. The analysis also showed that the TPS weight required for the lunar return skipping reentry was much more than the TPS weight necessary for any of the other reentry trajectories considered.

Quasi-static axial crushes on woven jute/polyester AA6063T52 composite tubes

NASA Astrophysics Data System (ADS)

Othman, A.; Ismail, AE

2018-04-01

Quasi-static axial loading have been studied in this paper to determine the behaviour of jute/polyester wrapped on aluminium alloy 6063T52. The filler material also was include into crush box specimen, which is polyurethane (PU) and polystyrene (PE) rigid foam at ranging 40 and 45 kg/m3 densities. All specimen profile was fabricated using hand layup techniques and the length of each specimen were fixed at 100 mm as well as diameter and width of the tube at 50.8 mm. The two types of tubular cross-section were studied of round and square thin-walled profiles and the angle of fibre at 450 were analysed for four layers. Thin walled of aluminium was 1.9 mm and end frontal of each specimen of composite were chamfered at 450 to prevent catastrophic failure mode. The specific absorbed energy (SEA) and crush force efficiency (CFE) were analyses for each specimen to see the behaviour on jute/polyester wrapped on metallic structure can give influence the energy management for automotive application. Result show that the four layers’ jute/polyester with filler material show significant value in term of specific absorbed energy compared empty and polyurethane profiles higher 26.66% for empty and 15.19% compared to polyurethane profiles. It has been found that the thin walled square profile of the jute/polyester tubes with polystyrene foam-filled is found higher respectively 27.42% to 13.13% than empty and polyurethane (PU) foam tubes. An introduce filler material onto thin walled composite profiles gave major advantage increases the mean axial load of 31.87% from 32.94 kN to 48.35 kN from empty to polystyrene thin walled round jute/polyester profiles and 31.7% from 23.11 KN to 33.84 kN from empty to polystyrene thin walled square jute/polyester profiles. Failure mechanisms of the axially loaded composite tubes were also observed and discussed.

Screening and characterization of plant cell walls using carbohydrate microarrays.

PubMed

Sørensen, Iben; Willats, William G T

2011-01-01

Plant cells are surrounded by cell walls built largely from complex carbohydrates. The primary walls of growing plant cells consist of interdependent networks of three polysaccharide classes: cellulose, cross-linking glycans (also known as hemicelluloses), and pectins. Cellulose microfibrils are tethered together by cross-linking glycans, and this assembly forms the major load-bearing component of primary walls, which is infiltrated with pectic polymers. In the secondary walls of woody tissues, pectins are much reduced and walls are reinforced with the phenolic polymer lignin. Plant cell walls are essential for plant life and also have numerous industrial applications, ranging from wood to nutraceuticals. Enhancing our knowledge of cell wall biology and the effective use of cell wall materials is dependent to a large extent on being able to analyse their fine structures. We have developed a suite of techniques based on microarrays probed with monoclonal antibodies with specificity for cell wall components, and here we present practical protocols for this type of analysis.

24 CFR 3280.811 - Calculations.

Code of Federal Regulations, 2011 CFR

2011-04-01

... appliance receptacle circuit (see definition of “Appliance Portable” with Note): e.g. Number of circuits × 1..., wall-mounted oven, cooking units. Where number of these appliances exceeds three, use 75 percent of... neutral load determined by Article 220.61 of the National Electrical Code, NFPA No. 70-2005. The loads...

Strategy Guideline: Compact Air Distribution Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burdick, A.

2013-06-01

This Strategy Guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. Traditional systems sized by 'rule of thumb' (i.e., 1 ton of cooling per 400 ft2 of floor space) that 'wash' the exterior walls with conditioned air from floor registers cannot provide appropriate air mixing and moisture removal in low-load homes. A compact air distribution system locates the HVAC equipment centrally with shorter ducts run to interior walls, and ceiling supply outlets throw the air toward themore » exterior walls along the ceiling plane; alternatively, high sidewall supply outlets throw the air toward the exterior walls. Potential drawbacks include resistance from installing contractors or code officials who are unfamiliar with compact air distribution systems, as well as a lack of availability of low-cost high sidewall or ceiling supply outlets to meet the low air volumes with good throw characteristics. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.« less

Non-Euclidean stress-free configuration of arteries accounting for curl of axial strips sectioned from vessels.

PubMed

Takamizawa, Keiichi; Nakayama, Yasuhide

2013-11-01

It is well known that arteries are subject to residual stress. In earlier studies, the residual stress in the arterial ring relieved by a radial cut was considered in stress analysis. However, it has been found that axial strips sectioned from arteries also curled into arcs, showing that the axial residual stresses were relieved from the arterial walls. The combined relief of circumferential and axial residual stresses must be considered to accurately analyze stress and strain distributions under physiological loading conditions. In the present study, a mathematical model of a stress-free configuration of artery was proposed using Riemannian geometry. Stress analysis for arterial walls under unloaded and physiologically loaded conditions was performed using exponential strain energy functions for porcine and human common carotid arteries. In the porcine artery, the circumferential stress distribution under physiological loading became uniform compared with that without axial residual strain, whereas a gradient of axial stress distribution increased through the wall thickness. This behavior showed almost the same pattern that was observed in a recent study in which approximate analysis accounting for circumferential and axial residual strains was performed, whereas the circumferential and axial stresses increased from the inner surface to the outer surface under a physiological condition in the human common carotid artery of a two-layer model based on data of other recent studies. In both analyses, Riemannian geometry was appropriate to define the stress-free configurations of the arterial walls with both circumferential and axial residual strains.

Strength Tests on Thin-walled Duralumin Cylinders in Torsion

NASA Technical Reports Server (NTRS)

Lundquist, Eugene E

1932-01-01

This report is the first of a series presenting the results of strength tests on thin-walled cylinders and truncated cones of circular and elliptical section; it comprises the results obtained to date from torsion (pure shear) tests on 65 thin-walled duralumin cylinders of circular section with ends clamped to rigid bulkheads. The effect of variations in the length/radius and radius/thickness ratios on the type of failure is indicated, and a semi-empirical equation for the shearing stress at maximum load is given.

Dispersion of Single Wall Carbon Nanotubes by in situ Polymerization Under Sonication

NASA Technical Reports Server (NTRS)

Park, Cheol; Ounaies, Zoubeida; Watson, Kent A.; Crooks, Roy E.; Smith, Joseph, Jr.; Lowther, Sharon E.; Connell, John W.; Siochi, Emilie J.; Harrison, Joycelyn S.; St.Clair, Terry L.

2002-01-01

Single wall nanotube reinforced polyimide nanocomposites were synthesized by in situ polymerization of monomers of interest in the presence of sonication. This process enabled uniform dispersion of single wall carbon nanotube (SWNT) bundles in the polymer matrix. The resultant SWNT-polyimide nanocomposite films were electrically conductive (antistatic) and optically transparent with significant conductivity enhancement (10 orders of magnitude) at a very low loading (0.1 vol%). Mechanical properties as well as thermal stability were also improved with the incorporation of the SWNT.

Thin-walled SnO2 nanotubes functionalized with Pt and Au catalysts via the protein templating route and their selective detection of acetone and hydrogen sulfide molecules

NASA Astrophysics Data System (ADS)

Jang, Ji-Soo; Kim, Sang-Joon; Choi, Seon-Jin; Kim, Nam-Hoon; Hakim, Meggie; Rothschild, Avner; Kim, Il-Doo

2015-10-01

Bio-inspired Pt (~2 nm) and Au (~2.7 nm) catalysts encapsulated by a protein shell, i.e., Pt-apoferritin (Pt@AF) and Au-apoferriten (Au@AF), were synthesized via the hollow protein nanocage (apoferritin) templating route and directly functionalized on the interior and exterior walls of electrospun SnO2 nanotubes (NTs) during controlled single-nozzle electrospinning followed by high temperature calcination with heating rate control. Fast crystallization of the exterior shell and outward diffusion of the interior Sn precursors and crystallites result in the continued growth of a tubular wall, which is related to rapid heating driven Ostwald-ripening behavior. Very importantly, the Pt and Au nanoparticles (NPs) were immobilized onto thin-walled SnO2 NTs with a diameter of ~350 nm and a shell thickness of ~40 nm without any aggregation of catalysts due to high dispersibility, which originated from repulsive electrostatic (Coulombic) forces acting on the surface charged protein shells, leading to an enhanced catalytic effect and outstanding gas sensing properties. Pt-loaded SnO2 NTs exhibited superior acetone response (Rair/Rgas = 92 at 5 ppm) compared to pure SnO2 NFs (Rair/Rgas = 4.8 at 5 ppm) and SnO2 NTs (Rair/Rgas = 11 at 5 ppm) while Au-loaded SnO2 NTs showed a high response when exposed to hydrogen sulfide (Rair/Rgas = 34 at 5 ppm), offering selective gas detection with minimal cross-sensitivity against other interfering gases such as NH3, CO, NO, C6H5CH3, and C5H12. Our results provide a new insight into facile, cost-effective, and highly dispersible catalyst loading on the interior and exterior walls of hollow metal oxide NTs via simple electrospinning as a potential breath analyzer.Bio-inspired Pt (~2 nm) and Au (~2.7 nm) catalysts encapsulated by a protein shell, i.e., Pt-apoferritin (Pt@AF) and Au-apoferriten (Au@AF), were synthesized via the hollow protein nanocage (apoferritin) templating route and directly functionalized on the interior and exterior walls of electrospun SnO2 nanotubes (NTs) during controlled single-nozzle electrospinning followed by high temperature calcination with heating rate control. Fast crystallization of the exterior shell and outward diffusion of the interior Sn precursors and crystallites result in the continued growth of a tubular wall, which is related to rapid heating driven Ostwald-ripening behavior. Very importantly, the Pt and Au nanoparticles (NPs) were immobilized onto thin-walled SnO2 NTs with a diameter of ~350 nm and a shell thickness of ~40 nm without any aggregation of catalysts due to high dispersibility, which originated from repulsive electrostatic (Coulombic) forces acting on the surface charged protein shells, leading to an enhanced catalytic effect and outstanding gas sensing properties. Pt-loaded SnO2 NTs exhibited superior acetone response (Rair/Rgas = 92 at 5 ppm) compared to pure SnO2 NFs (Rair/Rgas = 4.8 at 5 ppm) and SnO2 NTs (Rair/Rgas = 11 at 5 ppm) while Au-loaded SnO2 NTs showed a high response when exposed to hydrogen sulfide (Rair/Rgas = 34 at 5 ppm), offering selective gas detection with minimal cross-sensitivity against other interfering gases such as NH3, CO, NO, C6H5CH3, and C5H12. Our results provide a new insight into facile, cost-effective, and highly dispersible catalyst loading on the interior and exterior walls of hollow metal oxide NTs via simple electrospinning as a potential breath analyzer. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04487a

Single-stage evaluation of highly-loaded high-Mach-number compressor stages 5. Data and performance of baseline, corner-blow wall suction and combined corner blow wall suction stator

NASA Technical Reports Server (NTRS)

Nikkanen, J. P.; Brooky, J. P.

1972-01-01

A single-stage compressor with a rotor tip speed of 1600 ft/sec and a 0.5 hub tip ratio was used to investigate the effects of several stator endwall treatment methods on stage range and performance. These endwall treatment methods consisted of stator corner-blow, annular wall suction upstream of stator leading edge, and combined corner-blow and annular wall suction. The overall stage performance with corner blow was essentially the same as the baseline performance. The performance for the annular wall suction and the combined corner-blow and wall suction showed a reduction in peak efficiency of 2.5 percentage points compared to the baseline data.

Effects of reducing temperatures on the hydrogen storage capacity of double-walled carbon nanotubes with Pd loading.

PubMed

Sheng, Qu; Wu, Huimin; Wexler, David; Liu, Huakun

2014-06-01

The effects of different temperatures on the hydrogen sorption characteristics of double-walled carbon nanotubes (DWCNTs) with palladium loading have been investigated. When we use different temperatures, the particle sizes and specific surface areas of the samples are different, which affects the hydrogen storage capacity of the DWCNTs. In this work, the amount of hydrogen storage capacity was determined (by AMC Gas Reactor Controller) to be 1.70, 1.85, 2.00, and 1.93 wt% for pristine DWCNTS and for 2%Pd/DWCNTs-300 degrees C, 2%Pd/DWCNTs-400 degrees C, and 2%Pd/DWCNTs-500 degrees C, respectively. We found that the hydrogen storage capacity can be enhanced by loading with 2% Pd nanoparticles and selecting a suitable temperature. Furthermore, the sorption can be attributed to the chemical reaction between atomic hydrogen and the dangling bonds of the DWCNTs.

Fracture modes in human teeth.

PubMed

Lee, J J-W; Kwon, J-Y; Chai, H; Lucas, P W; Thompson, V P; Lawn, B R

2009-03-01

The structural integrity of teeth under stress is vital to functional longevity. We tested the hypothesis that this integrity is limited by fracture of the enamel. Experiments were conducted on molar teeth, with a metal rod loaded onto individual cusps. Fracture during testing was tracked with a video camera. Two longitudinal modes of cracking were observed: median cracking from the contact zone, and margin cracking along side walls. Median cracks initiated from plastic damage at the contact site, at first growing slowly and then accelerating to the tooth margin. Margin cracks appeared to originate from the cemento-enamel junction, and traversed the tooth wall adjacent to the loaded cusp from the gingival to the occlusal surface. All cracks remained confined within the enamel shell up to about 550 N. At higher loads, additional crack modes--such as enamel chipping and delamination--began to manifest themselves, leading to more comprehensive failure of the tooth structure.

Mechanical behaviour of connections between CLT panels under monotonic and cyclic loading

NASA Astrophysics Data System (ADS)

Xiong, HB; Huynh, A.

2018-05-01

The experimental research presented in this paper investigates the mechanical behaviour of commercial metal connections in three-ply Chinese-manufactured cross-laminated timber (CLT) panels. Monotonic and cyclic loading tests were conducted at Tongji University on angle bracket and joints with inclined self-tapping screws. According to the standard EN 12512, the force-displacement curves are exploited to assess the mechanical properties of the connections such as the strength capacity, yielding point, ductility and equivalent damping ratios. From the test results, the main load-carrying direction of the angle bracket is shear direction but the connection exhibits more ductile and dissipative behaviour in tension direction. In general, screwed joints demonstrate relatively brittle behaviour except in the case of shear wall-to-wall connection. Based on the capacity-based design principles, the experimental results and the failure modes are discussed to propose some design suggestions.

Impact Deformation of Thin-Walled Circular Tube Filled with Aluminum Foam in Lateral Compression

NASA Astrophysics Data System (ADS)

Kobayashi, Hidetoshi; Horikawa, Keitaro; Ogawa, Kinya; Hori, Masahiro

In this study, the impact deformation of thin-walled circular tubes filled with aluminum foam in lateral compression was investigated using a special load cell for long time measurement and a high-speed video camera to check the displacement of specimens. It was found that the absorbed energy up to the deformation of 60% of the specimen diameter obtained from impact tests is greater than that obtained in static tests, because of strain rate dependency of aluminum foam. The loaddisplacement curve of circular tubes with aluminum foam just inserted was consistent with the sum of the curves individually obtained. In both dynamic and static tests, however, the load of the tube with the foam inserted and glued by adhesive resin became larger than the sum of the individual loads, because of the interaction between circular tubes and aluminum foam cores.

Hydraulic transients in the long diversion-type hydropower station with a complex differential surge tank.

PubMed

Yu, Xiaodong; Zhang, Jian; Zhou, Ling

2014-01-01

Based on the theory of hydraulic transients and the method of characteristics (MOC), a mathematic model of the differential surge tank with pressure-reduction orifices (PROs) and overflow weirs for transient calculation is proposed. The numerical model of hydraulic transients is established using the data of a practical hydropower station; and the probable transients are simulated. The results show that successive load rejection is critical for calculating the maximum pressure in spiral case and the maximum rotating speed of runner when the bifurcated pipe is converging under the surge tank in a diversion-type hydropower station; the pressure difference between two sides of breast wall is large during transient conditions, and it would be more serious when simultaneous load rejections happen after load acceptance; the reasonable arrangement of PROs on breast wall can effectively decrease the pressure difference.

The effect of platinum precursor concentrations on chlorine sensing characteristics of platinum nanoparticles-loaded single walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Choi, Sun-Woo; Byun, Young Tae

2018-03-01

The correlation between platinum (Pt) functionalization and chlorine (Cl2) sensing capability in single-walled carbon nanotubes (SWCNTs) was investigated. Utilizing a photoreduction technique via ultraviolet (UV) irradiation, the Pt nanoparticles (NPs) with various diameters of 7-80 nm, which were controlled by Pt precursor concentrations, were successfully functionalized on the sidewalls of SWCNTs. The discrete Pt NP-loaded SWCNTs exhibited significantly enhanced response value (-(ΔR/R0) × 100 = 33.8%) for 1 ppm Cl2 at room temperature (25 °C) compared with that (no response) of pure SWCNTs. On the other hand, in case of continuous Pt NP-loaded SWCNTs, Cl2 sensing capabilities were significantly degraded. The Cl2 sensing capabilities of fabricated sensors tended to correlate with geometric configurations of the catalytic Pt NPs on the sidewalls of SWCNTs, due to differences in the electron pathway.

[CALCULATION OF RADIATION LOADS ON THE ANTHROPOMORPHIC PHANTOM ONBOARD THE SPACE STATION IN THE CASE OF ADDITIONAL SHIELDING].

PubMed

Kartashov, D A; Shurshakov, V A

2015-01-01

The paper presents the results of calculating doses from space ionizing radiation for a modeled orbital station cabin outfitted with an additional shield aimed to reduce radiation loads on cosmonaut. The shield is a layer with the mass thickness of -6 g/cm2 (mean density = 0.62 g/cm3) that covers the outer cabin wall and consists of wet tissues and towels used by cosmonauts for hygienic purposes. A tissue-equivalent anthropomorphic phantom imitates human body. Doses were calculated for the standard orbit of the International space station (ISS) with consideration of the longitudinal and transverse phantom orientation relative to the wall with or without the additional shield. Calculation of dose distribution in the human body improves prediction of radiation loads. The additional shield reduces radiation exposure of human critical organs by -20% depending on their depth and body spatial orientation in the ISS compartment.

Hydraulic Transients in the Long Diversion-Type Hydropower Station with a Complex Differential Surge Tank

PubMed Central

Yu, Xiaodong; Zhang, Jian

2014-01-01

Based on the theory of hydraulic transients and the method of characteristics (MOC), a mathematic model of the differential surge tank with pressure-reduction orifices (PROs) and overflow weirs for transient calculation is proposed. The numerical model of hydraulic transients is established using the data of a practical hydropower station; and the probable transients are simulated. The results show that successive load rejection is critical for calculating the maximum pressure in spiral case and the maximum rotating speed of runner when the bifurcated pipe is converging under the surge tank in a diversion-type hydropower station; the pressure difference between two sides of breast wall is large during transient conditions, and it would be more serious when simultaneous load rejections happen after load acceptance; the reasonable arrangement of PROs on breast wall can effectively decrease the pressure difference. PMID:25133213

Optical and Thermo-optical Properties of Polyimide-Single-Walled Carbon Nanotube Films: Experimental Results and Empirical Equations

NASA Technical Reports Server (NTRS)

Smith, Joseph G., Jr.; Connell, John W.; Watson, Kent A.; Danehy, Paul M.

2005-01-01

The incorporation of single-walled carbon nanotubes (SWNTs) into the bulk of space environmentally durable polymers at loading levels greater than or equal to 0.05 wt % has afforded thin films with surface and volume resistivities sufficient for electrostatic charge mitigation. However, the optical transparency at 500 nm decreased and the thermo-optical properties (solar absorptivity and thermal emissivity) increased with increaed SWNT loading. These properties were also dependent on film thickness. The absorbance characteristics of the films as a function of SWNT loading and film thickness were measured and determined to follow the classical Beer-Lambert law. Based on these results, an empirical relationship was derived and molar absorptivities determined for both the SWNTs and polymer matrix to provide a predictive approximation of these properties. The molar absorptivity determined for SWNTs dispersed in the polymer was comparable to reported solution determined values for HiPco SWNTs.

Six Basic Plan Concepts Used for California School Housing. A Sequential Development from 1900 to Today.

ERIC Educational Resources Information Center

California State Dept. of Education, Sacramento. Bureau of School Planning.

A floor plan accompanies each of six chronologically arranged schemes for housing educational programs. Scheme A represents the in-line corridor plan whose main characteristics are--(1) double loaded corridors with fixed bearing walls, (2) single window walls providing minimal light and ventilation, and (3) small classrooms with fixed desks and…

Close Encounters of the Best Kind: The Latest Sci-Fi

ERIC Educational Resources Information Center

Kunzel, Bonnie

2008-01-01

Not only is science fiction alive and well--it's flourishing. From the big screen (howdy, Wall-E) to the big books (like Suzanne Collins's The Hunger Games, which has attracted loads of prepublication praise), 2008 has been a great year for sci-fi. Publishers have released truckloads of new sci-fi titles this year, but what's particularly…

Relaxivity enhancement of aquated Tris(β-diketonate)gadolinium(III) chelates by confinement within ultrashort single-walled carbon nanotubes.

PubMed

Law, Justin J; Guven, Adem; Wilson, Lon J

2014-01-01

Ultrashort single-walled carbon nanotubes loaded with gadolinium ions (gadonanotubes) have been previously shown to exhibit extremely high T1 -weighted relaxivities (>100 mm(-1) s(-1) ). To further examine the effect of nanoconfinement on the relaxivity of gadolinium-based contrast agents for magnetic resonance imaging, a series of ultrashort single-walled carbon nanotube (US-tube) materials internally loaded with gadolinium chelates have been prepared and studied. US-tubes were loaded with Gd(acac)3  · 2H2 O, Gd(hfac)3  · 2H2 O, and Gd(thd)3 (acac = acetylacetone, hfac = hexafluoroacetylacetone, thd = tetramethylheptanedione). The longitudinal relaxivities of the prepared materials determined at 25°C in a 1.5 T field were 103 mm(-1) s(-1) for Gd(acac)3  · 2H2 O@US-tubes, 105 mm(-1) s(-1) for Gd(hfac)3  · 2H2 O@US-tubes and 26 mm(-1) s(-1) for Gd(thd)3 @US-tubes. Compared with the relaxivities obtained for the unloaded chelates (<10 mm(-1) s(-1) ) as well as accounting for the T1 reduction observed for the empty US-tubes, the boost in relaxivity for chelate-loaded US-tubes is attributed to confinement within the nanotube and depends on the number of coordinated water molecules. Copyright © 2014 John Wiley & Sons, Ltd.

Tungsten and beryllium armour development for the JET ITER-like wall project

NASA Astrophysics Data System (ADS)

Maier, H.; Hirai, T.; Rubel, M.; Neu, R.; Mertens, Ph.; Greuner, H.; Hopf, Ch.; Matthews, G. F.; Neubauer, O.; Piazza, G.; Gauthier, E.; Likonen, J.; Mitteau, R.; Maddaluno, G.; Riccardi, B.; Philipps, V.; Ruset, C.; Lungu, C. P.; Uytdenhouwen, I.; EFDA contributors, JET

2007-03-01

For the ITER-like wall project at JET the present main chamber CFC tiles will be exchanged with Be tiles and in parallel a fully tungsten-clad divertor will be prepared. Therefore three R&D programmes were initiated: Be coatings on Inconel as well as Be erosion markers were developed for the first wall of the main chamber. High heat flux screening and cyclic loading tests carried out on the Be coatings on Inconel showed excellent performance, above the required power and energy density. For the divertor a conceptual design for a bulk W horizontal target plate was investigated, with the emphasis on minimizing electromagnetic forces. The design consisted of stacks of W lamellae of 6 mm width that were insulated in the toroidal direction. High heat flux tests of a test module were performed with an electron beam at an absorbed power density up to 9 MW m-2 for more than 150 pulses and finally with increasing power loads leading to surface temperatures in excess of 3000 °C. No macroscopic failure occurred during the test while SEM showed the development of micro-cracks on the loaded surface. For all other divertor parts R&D was performed to provide the technology to coat the 2-directional CFC material used at JET with thin tungsten coatings. The W-coated CFC tiles were subjected to heat loads with power densities ranging up to 23.5 MW m-2 and exposed to cyclic heat loading for 200 pulses at 10.5 MW m-2. All coatings developed cracks perpendicular to the CFC fibres due to the stronger contraction of the coating upon cool-down after the heat pulses.

Examination of the behavior of gravity quay wall against liquefaction under the effect of wall width and soil improvement.

PubMed

Firoozi, Ali Akbar; Taha, Mohd Raihan; Mir Moammad Hosseini, S M; Firoozi, Ali Asghar

2014-01-01

Deformation of quay walls is one of the main sources of damage to port facility while liquefaction of backfill and base soil of the wall are the main reasons for failures of quay walls. During earthquakes, the most susceptible materials for liquefaction in seashore regions are loose saturated sand. In this study, effects of enhancing the wall width and the soil improvement on the behavior of gravity quay walls are examined in order to obtain the optimum improved region. The FLAC 2D software was used for analyzing and modeling progressed models of soil and loading under difference conditions. Also, the behavior of liquefiable soil is simulated by the use of "Finn" constitutive model in the analysis models. The "Finn" constitutive model is especially created to determine liquefaction phenomena and excess pore pressure generation.

Examination of the Behavior of Gravity Quay Wall against Liquefaction under the Effect of Wall Width and Soil Improvement

PubMed Central

Taha, Mohd Raihan; Mir Moammad Hosseini, S. M.

2014-01-01

Deformation of quay walls is one of the main sources of damage to port facility while liquefaction of backfill and base soil of the wall are the main reasons for failures of quay walls. During earthquakes, the most susceptible materials for liquefaction in seashore regions are loose saturated sand. In this study, effects of enhancing the wall width and the soil improvement on the behavior of gravity quay walls are examined in order to obtain the optimum improved region. The FLAC 2D software was used for analyzing and modeling progressed models of soil and loading under difference conditions. Also, the behavior of liquefiable soil is simulated by the use of “Finn” constitutive model in the analysis models. The “Finn” constitutive model is especially created to determine liquefaction phenomena and excess pore pressure generation. PMID:25126595

Finite element modelling of AA6063T52 thin-walled tubes under quasi-static axial loading

NASA Astrophysics Data System (ADS)

Othman, A.; Ismail, AE

2018-04-01

The behavior of aluminum alloy 6063T52 thin walled tubes have been present in this paper to determine absorbed energy under quasi-static axial loading. The correlation and comparison have been implemented for each experimental and finite element analysis results, respectively. Wall-thickness of 1.6 and 1.9 mm were selected and all specimen tested under room temperature standard. The length of each specimen were fixed at 125 mm as well as diameter as well as a width and diameter of the tube at 50.8 mm. The two types of tubular cross-section were examined whereas a round and square thin-walled profiles. The specific absorbed energy (SEA) and crush force efficiency (CFE) were analyzed for each specimen and model to see the behavior induced to failure under progressive collapse. Result showed that a correlation less than 5% different between both of comparison experimental and finite element model. It has been found that the thin walled round tube absorbed more energy rather than square profile in term of specific energy with both of either 1.6 or 1.9 of 23.93% and 35.36%, respectively. Overall for crush force efficiency (CFE) of each tube profile around 0.42 to 0.58 value. Indicated that the all specimen profile fail under progressive damage. The calibration between deformed model and experimental specimen were examined and discussed. It was found that the similarity failure mechanism observed for each thin walled profiles.

Stability of tapered and parallel-walled dental implants: A systematic review and meta-analysis.

PubMed

Atieh, Momen A; Alsabeeha, Nabeel; Duncan, Warwick J

2018-05-15

Clinical trials have suggested that dental implants with a tapered configuration have improved stability at placement, allowing immediate placement and/or loading. The aim of this systematic review and meta-analysis was to evaluate the implant stability of tapered dental implants compared to standard parallel-walled dental implants. Applying the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement, randomized controlled trials (RCTs) were searched for in electronic databases and complemented by hand searching. The risk of bias was assessed using the Cochrane Collaboration's Risk of Bias tool and data were analyzed using statistical software. A total of 1199 studies were identified, of which, five trials were included with 336 dental implants in 303 participants. Overall meta-analysis showed that tapered dental implants had higher implant stability values than parallel-walled dental implants at insertion and 8 weeks but the difference was not statistically significant. Tapered dental implants had significantly less marginal bone loss compared to parallel-walled dental implants. No significant differences in implant failure rate were found between tapered and parallel-walled dental implants. There is limited evidence to demonstrate the effectiveness of tapered dental implants in achieving greater implant stability compared to parallel-walled dental implants. Superior short-term results in maintaining peri-implant marginal bone with tapered dental implants are possible. Further properly designed RCTs are required to endorse the supposed advantages of tapered dental implants in immediate loading protocol and other complex clinical scenarios. © 2018 Wiley Periodicals, Inc.

Numerical analysis of behaviour of cross laminated timber (CLT) in blast loading

NASA Astrophysics Data System (ADS)

Šliseris, J.; Gaile, L.; Pakrastiņš, L.

2017-10-01

A non-linear computation model for CLT wall element that includes explicit dynamics and composite damage constitutive model was developed. The numerical model was compared with classical beam theory and it turned out that shear wood layer has significant shear deformations that must be taken into account when designing CLT. It turned out that impulse duration time has a major effect on the strength of CLT. Special attention must be payed when designing CLT wall, window and door architectural system in order to guarantee the robustness of structure. The proposed numerical modelling framework can be used when designing CLT buildings that can be affected by blast loading, whilst structural robustness must be guaranteed.

The yield and post-yield behavior of high-density polyethylene

NASA Technical Reports Server (NTRS)

Semeliss, M. A.; Wong, R.; Tuttle, M. E.

1990-01-01

An experimental and analytical evaluation was made of the yield and post-yield behavior of high-density polyethylene, a semi-crystalline thermoplastic. Polyethylene was selected for study because it is very inexpensive and readily available in the form of thin-walled tubes. Thin-walled tubular specimens were subjected to axial loads and internal pressures, such that the specimens were subjected to a known biaxial loading. A constant octahederal shear stress rate was imposed during all tests. The measured yield and post-yield behavior was compared with predictions based on both isotropic and anisotropic models. Of particular interest was whether inelastic behavior was sensitive to the hydrostatic stress level. The major achievements and conclusions reached are discussed.

49 CFR 178.345-11 - Tank outlets.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 3 2012-10-01 2012-10-01 false Tank outlets. 178.345-11 Section 178.345-11... Containers for Motor Vehicle Transportation § 178.345-11 Tank outlets. (a) General. As used in this section, “loading/unloading outlet” means any opening in the cargo tank wall used for loading or unloading of lading...

49 CFR 178.345-11 - Tank outlets.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 3 2013-10-01 2013-10-01 false Tank outlets. 178.345-11 Section 178.345-11... Containers for Motor Vehicle Transportation § 178.345-11 Tank outlets. (a) General. As used in this section, “loading/unloading outlet” means any opening in the cargo tank wall used for loading or unloading of lading...

49 CFR 178.345-11 - Tank outlets.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 3 2014-10-01 2014-10-01 false Tank outlets. 178.345-11 Section 178.345-11... Containers for Motor Vehicle Transportation § 178.345-11 Tank outlets. (a) General. As used in this section, “loading/unloading outlet” means any opening in the cargo tank wall used for loading or unloading of lading...

49 CFR 178.345-11 - Tank outlets.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 3 2011-10-01 2011-10-01 false Tank outlets. 178.345-11 Section 178.345-11... Containers for Motor Vehicle Transportation § 178.345-11 Tank outlets. (a) General. As used in this section, “loading/unloading outlet” means any opening in the cargo tank wall used for loading or unloading of lading...

Investigation of the Behavior of Thin-Walled Panels with Cutouts

NASA Technical Reports Server (NTRS)

Podorozhny, A. A.

1946-01-01

The present paper deals with the computation and methods of reinforcement of stiffened panels with cutouts under bending loads such as are applied to the sides of a fuselage. A comparison is maade between the computed and test results. Results are presented of tests on panels with cutouts under tensile and compressive loads.

Composite Behavior of Insulated Concrete Sandwich Wall Panels Subjected to Wind Pressure and Suction

PubMed Central

Choi, Insub; Kim, JunHee; Kim, Ho-Ryong

2015-01-01

A full-scale experimental test was conducted to analyze the composite behavior of insulated concrete sandwich wall panels (ICSWPs) subjected to wind pressure and suction. The experimental program was composed of three groups of ICSWP specimens, each with a different type of insulation and number of glass-fiber-reinforced polymer (GFRP) shear grids. The degree of composite action of each specimen was analyzed according to the load direction, type of the insulation, and number of GFRP shear grids by comparing the theoretical and experimental values. The failure modes of the ICSWPs were compared to investigate the effect of bonds according to the load direction and type of insulation. Bonds based on insulation absorptiveness were effective to result in the composite behavior of ICSWP under positive loading tests only, while bonds based on insulation surface roughness were effective under both positive and negative loading tests. Therefore, the composite behavior based on surface roughness can be applied to the calculation of the design strength of ICSWPs with continuous GFRP shear connectors. PMID:28788001

Wall Pressure Unsteadiness and Side Loads in Overexpanded Rocket Nozzles

NASA Technical Reports Server (NTRS)

Baars, Woutijn J.; Tinney, Charles E.; Ruf, Joseph H.; Brown, Andrew M.; McDaniels, David M.

2012-01-01

Surveys of both the static and dynamic wall pressure signatures on the interior surface of a sub-scale, cold-flow and thrust optimized parabolic nozzle are conducted during fixed nozzle pressure ratios corresponding to FSS and RSS states. The motive is to develop a better understanding for the sources of off-axis loads during the transient start-up of overexpanded rocket nozzles. During FSS state, pressure spectra reveal frequency content resembling SWTBLI. Presumably, when the internal flow is in RSS state, separation bubbles are trapped by shocks and expansion waves; interactions between the separated flow regions and the waves produce asymmetric pressure distributions. An analysis of the azimuthal modes reveals how the breathing mode encompasses most of the resolved energy and that the side load inducing mode is coherent with the response moment measured by strain gauges mounted upstream of the nozzle on a flexible tube. Finally, the unsteady pressure is locally more energetic during RSS, albeit direct measurements of the response moments indicate higher side load activity when in FSS state. It is postulated that these discrepancies are attributed to cancellation effects between annular separation bubbles.

Full-scale shear wall tests for force transfer around openings

Treesearch

Tom Skaggs; Borjen Yeh; Frank Lam; Douglas Rammer; James Wacker

2010-01-01

Wood structural panel sheathed shear walls and diaphragms are the primary lateral-load resisting elements in wood-frame construction. The historical performance of light-frame structures in North America are very good due, in part, to model building codes that are designed to preserve life safety, as well as the inherent redundancy of wood-frame construction using wood...

49 CFR 179.220-17 - Gauging devices, top loading and unloading devices, venting and air inlet devices.

Code of Federal Regulations, 2010 CFR

2010-10-01

... good welding quality in conjunction with the metal of the tank shell. When the sump or siphon bowl is... cylinder of revolution must have walls of such thickness and must be so reinforced that the stresses in the walls caused by a given internal pressure are not greater than the circumferential stress which would...

49 CFR 179.200-16 - Gauging devices, top loading and unloading devices, venting and air inlet devices.

Code of Federal Regulations, 2010 CFR

2010-10-01

... be made of cast, forged, or fabricated metal. Each sump or siphon bowl must be of good welding... must have walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are not greater than the circumferential stress which would exist under the same internal...

49 CFR 179.200-16 - Gauging devices, top loading and unloading devices, venting and air inlet devices.

Code of Federal Regulations, 2013 CFR

2013-10-01

... be made of cast, forged, or fabricated metal. Each sump or siphon bowl must be of good welding... must have walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are not greater than the circumferential stress which would exist under the same internal...

49 CFR 179.200-16 - Gauging devices, top loading and unloading devices, venting and air inlet devices.

Code of Federal Regulations, 2014 CFR

2014-10-01

... be made of cast, forged, or fabricated metal. Each sump or siphon bowl must be of good welding... must have walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are not greater than the circumferential stress which would exist under the same internal...

49 CFR 179.100-13 - Venting, loading and unloading valves, measuring and sampling devices.

Code of Federal Regulations, 2013 CFR

2013-10-01

... metal. Each sump or siphon bowl must be of good welding quality in conjunction with the metal of the... walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are no greater than the circumferential stress that would exist under the same internal pressure...

49 CFR 179.220-17 - Gauging devices, top loading and unloading devices, venting and air inlet devices.

Code of Federal Regulations, 2014 CFR

2014-10-01

... good welding quality in conjunction with the metal of the tank shell. When the sump or siphon bowl is... cylinder of revolution must have walls of such thickness and must be so reinforced that the stresses in the walls caused by a given internal pressure are not greater than the circumferential stress which would...

49 CFR 179.100-13 - Venting, loading and unloading valves, measuring and sampling devices.

Code of Federal Regulations, 2012 CFR

2012-10-01

... metal. Each sump or siphon bowl must be of good welding quality in conjunction with the metal of the... walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are no greater than the circumferential stress that would exist under the same internal pressure...

49 CFR 179.220-17 - Gauging devices, top loading and unloading devices, venting and air inlet devices.

Code of Federal Regulations, 2012 CFR

2012-10-01

... good welding quality in conjunction with the metal of the tank shell. When the sump or siphon bowl is... cylinder of revolution must have walls of such thickness and must be so reinforced that the stresses in the walls caused by a given internal pressure are not greater than the circumferential stress which would...

49 CFR 179.100-13 - Venting, loading and unloading valves, measuring and sampling devices.

Code of Federal Regulations, 2014 CFR

2014-10-01

... metal. Each sump or siphon bowl must be of good welding quality in conjunction with the metal of the... walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are no greater than the circumferential stress that would exist under the same internal pressure...

49 CFR 179.200-16 - Gauging devices, top loading and unloading devices, venting and air inlet devices.

Code of Federal Regulations, 2012 CFR

2012-10-01

... be made of cast, forged, or fabricated metal. Each sump or siphon bowl must be of good welding... must have walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are not greater than the circumferential stress which would exist under the same internal...

49 CFR 179.100-13 - Venting, loading and unloading valves, measuring and sampling devices.

Code of Federal Regulations, 2011 CFR

2011-10-01

... metal. Each sump or siphon bowl must be of good welding quality in conjunction with the metal of the... walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are no greater than the circumferential stress that would exist under the same internal pressure...

49 CFR 179.220-17 - Gauging devices, top loading and unloading devices, venting and air inlet devices.

Code of Federal Regulations, 2013 CFR

2013-10-01

... good welding quality in conjunction with the metal of the tank shell. When the sump or siphon bowl is... cylinder of revolution must have walls of such thickness and must be so reinforced that the stresses in the walls caused by a given internal pressure are not greater than the circumferential stress which would...

49 CFR 179.220-17 - Gauging devices, top loading and unloading devices, venting and air inlet devices.

Code of Federal Regulations, 2011 CFR

2011-10-01

... good welding quality in conjunction with the metal of the tank shell. When the sump or siphon bowl is... cylinder of revolution must have walls of such thickness and must be so reinforced that the stresses in the walls caused by a given internal pressure are not greater than the circumferential stress which would...

49 CFR 179.200-16 - Gauging devices, top loading and unloading devices, venting and air inlet devices.

Code of Federal Regulations, 2011 CFR

2011-10-01

... be made of cast, forged, or fabricated metal. Each sump or siphon bowl must be of good welding... must have walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are not greater than the circumferential stress which would exist under the same internal...

Loads from Compressive Strain Caused by Mining Activity Illustrated with the Example of Two Buildings in Silesia

NASA Astrophysics Data System (ADS)

Kadela, Marta; Chomacki, Leszek

2017-10-01

The soil’s load on retention walls or underground elements of engineering structures consists of three basic types of pressure: active pressure (p a ), passive pressure (p b ) and at-rest pressure (p 0 ). In undisturbed areas without any mining, due to lack of activity in the soil, specific forces from the soil are stable and unchanging throughout the structure’s life. Mining activity performed at a certain depth activates the soil. Displacements take place in the surface layer of the rock mass, which begins to act on the structure embedded in it, significantly changing the original stress distribution. Deformation of the subgrade, mainly horizontal strains, becomes a source of significant additional actions in the contact zone between the structure and the soil, constituting an additional load for the structure. In order to monitor the mining influence in the form of compressive load on building walls, an observation line was set up in front of two buildings located in Silesia (in Mysłowice). In 2013, some mining activity took place directly under those buildings, with expected horizontal strains of εx = -5.8 mm/m. The measurement results discussed in this paper showed that, as predicted, the buildings were subjected only to horizontal compressive strains with the values parallel to the analysed wall being less than -4.0 ‰ for first building and -1.5‰ for second building, and values perpendicular to the analysed wall being less than -6.0‰ for first building and -4.0‰ for second building (the only exception was the measurement in line 8-13, where εx = -17.04‰ for first building and -4.57‰ for second building). The horizontal displacement indicate that the impact of mining activity was greater on first building. This is also confirmed by inspections of the damage.

Multiwalled carbon nanotubes effect on the bioavailability of artemisinin and its cytotoxity to cancerous cells

NASA Astrophysics Data System (ADS)

Rezaei, Behzad; Majidi, Najmeh; Noori, Shokoofe; Hassan, Zuhair M.

2011-12-01

Artemisinin regarded as one of the most promising anticancer drugs can bind to DNA with a binding constant of 1.04 × 104 M-1. The electrochemical experiments indicated that for longer incubation time periods, the reduction peak current of artemisinin on carbon nanotube modified electrode increases. Therefore, the uptake of drug molecules from a solution into CNTs will be achieved automatically by adsorption of 88.7% of artemisinin onto carbon nanotubes surface without alteration in drug properties. Hence, capability of carbon nanotubes to have synergistic effect on the bioavailability of artemisinin was investigated. Experimental tests on K562 cancer cell lines growth by MTT assay proved that multi-walled carbon nanotubes can enhance the cytotoxity of artemisinin to the targeted cancer cells with unprecedented accuracy and efficiency. The IC50 values were 65 and 35 μM for artemisinin and artemisinin loaded on multi-walled carbon nanotubes, respectively; demonstrating that artemisinin loaded on multi-walled carbon nanotubes is more effective in inhibition of cancer cell lines growth.

Optimum Material Composition for Minimizing the Stress Intensity Factor of Edge Crack in Thick-Walled FGM Circular Pipes Under Thermomechanical Loading

NASA Astrophysics Data System (ADS)

Sekine, Hideki; Yoshida, Kimiaki

This paper deals with the optimization problem of material composition for minimizing the stress intensity factor of radial edge crack in thick-walled functionally graded material (FGM) circular pipes under steady-state thermomechanical loading. Homogenizing the FGM circular pipes by simulating the inhomogeneity of thermal conductivity by a distribution of equivalent eigentemperature gradient and the inhomogeneity of Young's modulus and Poisson's ratio by a distribution of equivalent eigenstrain, we present an approximation method to obtain the stress intensity factor of radial edge crack in the FGM circular pipes. The optimum material composition for minimizing the stress intensity factor of radial edge crack is determined using a nonlinear mathematical programming method. Numerical results obtained for a thick-walled TiC/Al2O3 FGM circular pipe reveal that it is possible to decrease remarkably the stress intensity factor of radial edge crack by setting the optimum material composition profile.

Analysis of Slab-column Shearwall Structure of 6000 Tons Cold Storage

NASA Astrophysics Data System (ADS)

He, Dongqing; Song, Pengwei; Jie, Pengyu

2018-05-01

Combining with the functional requirements, the site conditions and the 6000 tons load characteristics of cold storage, so determine its structure system for the slab-column-shear wall structure. The paper recommends the design of foundation, the settings of column cap, the arrangement of shear wall, the punching shear of floor slab and the analysis and calculation results of main structure. By addition shear wall in slab-column structure to increase the overall stiffness of structure and improve the seismic performance of structure. Take the detached form between the main structure and the external wall insulation, while set anchorage beam between in the main floor and the ring beam along the axis of the column grid to enhance the overall stability of the external wall insulation.

Adaptive mesh refinement and load balancing based on multi-level block-structured Cartesian mesh

NASA Astrophysics Data System (ADS)

Misaka, Takashi; Sasaki, Daisuke; Obayashi, Shigeru

2017-11-01

We developed a framework for a distributed-memory parallel computer that enables dynamic data management for adaptive mesh refinement and load balancing. We employed simple data structure of the building cube method (BCM) where a computational domain is divided into multi-level cubic domains and each cube has the same number of grid points inside, realising a multi-level block-structured Cartesian mesh. Solution adaptive mesh refinement, which works efficiently with the help of the dynamic load balancing, was implemented by dividing cubes based on mesh refinement criteria. The framework was investigated with the Laplace equation in terms of adaptive mesh refinement, load balancing and the parallel efficiency. It was then applied to the incompressible Navier-Stokes equations to simulate a turbulent flow around a sphere. We considered wall-adaptive cube refinement where a non-dimensional wall distance y+ near the sphere is used for a criterion of mesh refinement. The result showed the load imbalance due to y+ adaptive mesh refinement was corrected by the present approach. To utilise the BCM framework more effectively, we also tested a cube-wise algorithm switching where an explicit and implicit time integration schemes are switched depending on the local Courant-Friedrichs-Lewy (CFL) condition in each cube.

Laboratory research of hydraulic fracturing with tangential loading of borehole wall

NASA Astrophysics Data System (ADS)

Kurlenya, MV; Patutin, AV; Rybalkin, LA; Serdyukov, SV; Shilova, TV

2017-02-01

Under study is transverse fracturing of an organic glass block through secondary shearing stress applied to the borehole wall. To this effect, a system composed of a press sealer and a collet anchor manufactured in two options has been designed. It is shown than an anchor with a circular groove allows reducing breakdown pressure and enables effective transverse fracture at the borehole bottom.

Mechanochemical Polarization of Contiguous Cell Walls Shapes Plant Pavement Cells.

PubMed

Majda, Mateusz; Grones, Peter; Sintorn, Ida-Maria; Vain, Thomas; Milani, Pascale; Krupinski, Pawel; Zagórska-Marek, Beata; Viotti, Corrado; Jönsson, Henrik; Mellerowicz, Ewa J; Hamant, Olivier; Robert, Stéphanie

2017-11-06

The epidermis of aerial plant organs is thought to be limiting for growth, because it acts as a continuous load-bearing layer, resisting tension. Leaf epidermis contains jigsaw puzzle piece-shaped pavement cells whose shape has been proposed to be a result of subcellular variations in expansion rate that induce local buckling events. Paradoxically, such local compressive buckling should not occur given the tensile stresses across the epidermis. Using computational modeling, we show that the simplest scenario to explain pavement cell shapes within an epidermis under tension must involve mechanical wall heterogeneities across and along the anticlinal pavement cell walls between adjacent cells. Combining genetics, atomic force microscopy, and immunolabeling, we demonstrate that contiguous cell walls indeed exhibit hybrid mechanochemical properties. Such biochemical wall heterogeneities precede wall bending. Altogether, this provides a possible mechanism for the generation of complex plant cell shapes. Copyright © 2017 Elsevier Inc. All rights reserved.

Seismic Behaviour of Composite Steel Fibre Reinforced Concrete Shear Walls

NASA Astrophysics Data System (ADS)

Boita, Ioana-Emanuela; Dan, Daniel; Stoian, Valeriu

2017-10-01

In this paper is presented an experimental study conducted at the “Politehnica” University of Timisoara, Romania. This study provides results from a comprehensive experimental investigation on the behaviour of composite steel fibre reinforced concrete shear walls (CSFRCW) with partially or totally encased profiles. Two experimental composite steel fibre reinforced concrete walls (CSFRCW) and, as a reference specimen, a typical reinforced concrete shear wall (RCW), (without structural reinforcement), were fabricated and tested under constant vertical load and quasi-static reversed cyclic lateral loads, in displacement control. The tests were performed until failure. The tested specimens were designed as 1:3 scale steel-concrete composite elements, representing a three storeys and one bay element from the base of a lateral resisting system made by shear walls. Configuration/arrangement of steel profiles in cross section were varied within the specimens. The main objective of this research consisted in identifying innovative solutions for composite steel-concrete shear walls with enhanced performance, as steel fibre reinforced concrete which was used in order to replace traditional reinforced concrete. A first conclusion was that replacing traditional reinforcement with steel fibre changes the failure mode of the elements, as from a flexural mode, in case of element RCW, to a shear failure mode for CSFRCW. The maximum lateral force had almost similar values but test results indicated an improvement in cracking response, and a decrease in ductility. The addition of steel fibres in the concrete mixture can lead to an increase of the initial cracking force, and can change the sudden opening of a crack in a more stable process.

Mechanisms of postprandial abdominal bloating and distension in functional dyspepsia.

PubMed

Burri, Emanuel; Barba, Elizabeth; Huaman, Jose Walter; Cisternas, Daniel; Accarino, Anna; Soldevilla, Alfredo; Malagelada, Juan-R; Azpiroz, Fernando

2014-03-01

Patients with irritable bowel syndrome and abdominal bloating exhibit abnormal responses of the abdominal wall to colonic gas loads. We hypothesised that in patients with postprandial bloating, ingestion of a meal triggers comparable abdominal wall dyssynergia. Our aim was to characterise abdominal accommodation to a meal in patients with postprandial bloating. A test meal (0.8 kcal/ml nutrients plus 27 g/litre polyethylenglycol 4000) was administered at 50 ml/min as long as tolerated in 10 patients with postprandial bloating (fulfilling Rome III criteria for postprandial distress syndrome) and 12 healthy subjects, while electromyographic (EMG) responses of the anterior wall (upper and lower rectus, external and internal oblique via bipolar surface electrodes) and the diaphragm (via six ring electrodes over an oesophageal tube in the hiatus) were measured. Means +/- SD were calculated. Healthy subjects tolerated a meal volume of 913±308 ml; normal abdominal wall accommodation to the meal consisted of diaphragmatic relaxation (EMG activity decreased by 15±6%) and a compensatory contraction (25±9% increase) of the upper abdominal wall muscles (upper rectus and external oblique), with no changes in the lower anterior muscles (lower rectus and internal oblique). Patients tolerated lower volume loads (604±310 ml; p=0.030 vs healthy subjects) and developed a paradoxical response, that is, diaphragmatic contraction (14±3% EMG increment; p<0.01 vs healthy subjects) and upper anterior wall relaxation (9±4% inhibition; p<0.01 vs healthy subjects). In functional dyspepsia, postprandial abdominal distension is produced by an abnormal viscerosomatic response to meal ingestion that alters normal abdominal accommodation.

Boundary Connection Behavior and Connection Design for Retrofitted Unreinforced Masonry Walls Subjected to Blast Loads (Preprint)

DTIC Science & Technology

2010-02-01

supports. Figure 2 – FBD of Retrofitting Component The new deformed axial length of t he m embrane resulting from the applied lateral load is...BLAST LOADS John Hoemann U.S. Army Engineer Research & Development Center (CEERD-GS-V) 3909 Halls Ferry Road Vicksburg, MS 39180 James... joint owner of the work. If published, ASCE Structures Congress may assert copyright. If so, the United States has for itself and others acting on

Analysis of stress-strain state of RVS-20000 tank under non-axisymmetric wind load action

NASA Astrophysics Data System (ADS)

Tarasenko, A. A.; Chepur, P. V.; Gruchenkova, A. A.

2018-03-01

In modern reference documentation, it is customary to set the wind load as uniformly distributed pressure over the area and wall of the tank. Experimental studies in the wind tunnel for various designs of the VST carried out under the guidance of professors V.E. Shutov and V.L. Berezin showed that when wind acts on the shell, there occur rarefaction zones, which must be taken into account during strain analysis of tanks. A finite-element model of the RVS-20000 tank was developed to calculate the wind load in a non-axisymmetric setting, taking into account the array of differentiated values of the aerodynamic coefficient. The distribution of stresses and strains of RVS-20000 metal structures under the effect of unevenly distributed wind pressure with a normal value of Qn = 600 Pa is obtained. It is established that the greatest strains and stresses occur at the interface of the wall and the fixed floor.

Fabrication of doxorubicin and heparin co-loaded microcapsules for synergistic cancer therapy.

PubMed

Chen, Jing-Xiao; Liang, Yan; Liu, Wen; Huang, Jin; Chen, Jing-Hua

2014-08-01

In this study, a layer-by-layer (LbL) assembly (HEP/CHI)5 microcapsule with doxorubicin hydrochloride (DOX) encapsulating inside was fabricated via alternatively depositing heparin (HEP) and chitosan (CHI) onto DOX-loaded CaCO3 templates. The microcapsules were of stable architecture and had good dispersity in aqueous medium. Fluorescence observation showed that DOX distributed both in the wall and in the cavity of microcapsules, while HEP presented in the capsule wall. The release rate of DOX increased at acidic pH as compared with that at basic pH, suggesting a pH-responsive drug release behavior. The microcapsules with positively charged CHI lying on the outer layer could protect HEP from heparanase degradation and achieve intracellular co-delivery of both DOX and HEP. Thus, the DOX-loaded microcapsules could have improved inhibition activity against A549 cells by combining pharmacological actions of DOX and HEP. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of the Airborne Sound Insulation of a Straw Bale Partition Wall

NASA Astrophysics Data System (ADS)

Teslík, Jiří; Fabian, Radek; Hrubá, Barbora

2017-06-01

This paper describes the results of a scientific project focused on determining of the Airborne Sound Insulation of a peripheral non-load bearing wall made of straw bales expressed by Weighted Sound Reduction Index. Weighted Sound Reduction Index was determined by measuring in the certified acoustic laboratory at the Faculty of Mechanical Engineering at Brno University of Technology. The measured structure of the straw wall was modified in combinations with various materials, so the results include a wide range of possible compositions of the wall. The key modification was application of plaster on both sides of the straw bale wall. This construction as is frequently done in actual straw houses. The additional measurements were performed on the straw wall with several variants of additional wall of slab materials. The airborne sound insulation value has been also measured in separate stages of the construction. Thus it is possible to compare and determinate the effect of the single layers on the airborne sound insulation.

Heat transfer characteristics of building walls using phase change material

NASA Astrophysics Data System (ADS)

Irsyad, M.; Pasek, A. D.; Indartono, Y. S.; Pratomo, A. W.

2017-03-01

Minimizing energy consumption in air conditioning system can be done with reducing the cooling load in a room. Heat from solar radiation which passes through the wall increases the cooling load. Utilization of phase change material on walls is expected to decrease the heat rate by storing energy when the phase change process takes place. The stored energy is released when the ambient temperature is low. Temperature differences at noon and evening can be utilized as discharging and charging cycles. This study examines the characteristics of heat transfer in walls using phase change material (PCM) in the form of encapsulation and using the sleeve as well. Heat transfer of bricks containing encapsulated PCM, tested the storage and released the heat on the walls of the building models were evaluated in this study. Experiments of heat transfer on brick consist of time that is needed for heat transfer and thermal conductivity test as well. Experiments were conducted on a wall coated by PCM which was exposed on a day and night cycle to analyze the heat storage and heat release. PCM used in these experiments was coconut oil. The measured parameter is the temperature at some points in the brick, walls and ambient temperature as well. The results showed that the use of encapsulation on an empty brick can increase the time for thermal heat transfer. Thermal conductivity values of a brick containing encapsulated PCM was lower than hollow bricks, where each value was 1.3 W/m.K and 1.6 W/m.K. While the process of heat absorption takes place from 7:00 am to 06:00 pm, and the release of heat runs from 10:00 pm to 7:00 am. The use of this PCM layer can reduce the surface temperature of the walls of an average of 2°C and slows the heat into the room.

Tissue adaptations to gravitational stress - Newborn versus adult giraffes

NASA Technical Reports Server (NTRS)

Hargens, Alan R; Gershuni, David H.; Danzig, Larry A.; Millard, Ronald W.; Pettersson, Knut

1988-01-01

Preliminary results on developmental alterations in load-bearing tissues of newborn and adult giraffes are presented. Attention is focused on vascular wall thickness in relation to local blood pressure, and on meniscal adaptations to increased load bearing in the developing giraffe. It is believed that the developing giraffe provides an excellent model for investigations of adaptive mechanisms of increased weight bearing.

Plasma Chamber Restraints in Ignitor and Relevant Disruption Analysis

NASA Astrophysics Data System (ADS)

Gasparotto, M.; Cucchiaro, A.; Capriccioli, A.; Celentano, G.; Rita, C.; Roccella, M.; Macco, B.; Micheli, I.; Ferrari, G.; Orlandi, S.; Coppi, B.

2000-10-01

The plasmas chamber (PC) of Ignitor is made of 12 D-shaped toroidal sectors of Inconel 625 welded together by automatic remote equipment. The thickness of the inboard wall is 17 mm while the middle and outboard walls are 26 mm thick. The PC is supported through the ports by the C-Clamp structure of the toroidal magnet. The main function of the PC supports is to resist the vertical and radial electromagnetic loads and to allow for free movement under thermal loads while providing electrical insulation from the C-Clamps and cryostat. The largest estimated loads are due to a Vertical Displacement Event (VDE) disruption that is followed by a thermal quench and then by the current quench. The vertical supports involve a connection of each radial port to the C-Clamp structure by a link system that withstands the calculated loads. The radial supports resist, with high stiffness, the centripetal and centrifugal forces. The end flange of each radial port is connected to the C-Clamp structure by a clamping sleeve device. The clamping sleeves are hydraulically operated to provide locking during discharge. The clamping sleeves of the radial support system have been validated by an appropriate series of tests.

Assessment of Composite Delamination Self-Healing Under Cyclic Loading

NASA Technical Reports Server (NTRS)

O'Brien, T. Kevin

2009-01-01

Recently, the promise of self-healing materials for enhanced autonomous durability has been introduced using a micro-encapsulation technique where a polymer based healing agent is encapsulated in thin walled spheres and embedded into a base polymer along with a catalyst phase. For this study, composite skin-stiffener flange debonding specimens were manufactured from composite prepreg containing interleaf layers with a polymer based healing agent encapsulated in thin-walled spheres. Constant amplitude fatigue tests in three-point bending showed the effect of self-healing on the fatigue response of the skin-stiffener flange coupons. After the cycling that created debonding, fatigue tests were held at the mean load for 24 hours. For roughly half the specimens tested, when the cyclic loading was resumed a decrease in compliance (increase in stiffness) was observed, indicating that some healing had occurred. However, with continued cycling, the specimen compliance eventually increased to the original level before the hold, indicating that the damage had returned to its original state. As was noted in a prevoius study conducted with specimens tested under monotonically increasing loads to failure, healing achieved via the micro-encapsulation technique may be limited to the volume of healing agent available relative to the crack volume.

The Effects of Single-Wall Carbon Nanotubes on the Shear Piezoelectricity of Biopolymers

NASA Technical Reports Server (NTRS)

Lovell, Conrad; Fitz-Gerald, James M.; Harrison, Joycelyn S.; Park, Cheol

2008-01-01

Shear piezoelectricity was investigated in a series of composites consisting of increased loadings of single-wall carbon nanotubes (SWCNTs) in poly (gamma-benzyl-L-glutamate), or PBLG. The effects of the SWCNTs on this material property in PBLG will be discussed. Their influence on the morphology of the polymer (degree of orientation and crystallinity), and electrical and dielectric properties of the composite will be reported

Nuclear magnetic resonance of molecular hydrogen trapped in single-walled carbon nanotube bundles.

PubMed

Shiraishi, Masashi; Ata, Masafumi

2002-10-01

Molecular dynamics of hydrogen trapped in single-walled carbon nanotube bundles was analyzed by nuclear magnetic resonance. The chemical shift of hydrogen was about 5.1 ppm at 293 K, which is similar to that of water. The relaxation time, T1, was about 0.1-0.2 s. Values in this work are comparable to those for hydrogen loaded in silica and a-Si.

2D and 3D GPR imaging of structural ceilings in historic and existing constructions

NASA Astrophysics Data System (ADS)

Colla, Camilla

2014-05-01

GPR applications in civil engineering are to date quite diversified. With respect to civil constructions and monumental buildings, detection of voids, cavities, layering in structural elements, variation of geometry, of moisture content, of materials, areas of decay, defects, cracks have been reported in timber, concrete and masonry elements. Nonetheless, many more fields of investigation remain unexplored. This contribution gives an account of a variety of examples of structural ceilings investigation by GPR radar in reflection mode, either as 2D or 3D data acquisition and visualisation. Ceilings have a pre-eminent role in buildings as they contribute to a good structural behaviour of the construction. Primarily, the following functions can be listed for ceilings: a) they carry vertical dead and live loads on floors and distribute such loads to the vertical walls; b) they oppose to external horizontal forces such as wind loads and earthquakes helping to transfer such forces from the loaded element to the other walls; c) they contribute to create the box skeleton and behaviour of a building, connecting the different load bearing walls and reducing the slenderness and flexural instability of such walls. Therefore, knowing how ceilings are made in specific buildings is of paramount importance for architects and structural engineers. According to the type of building and age of construction, ceilings may present very different solutions and materials. Moreover, in existing constructions, ceilings may have been substituted, modified or strengthened due to material decay or to change of use of the building. These alterations may often go unrecorded in technical documentation or technical drawings may be unavailable. In many cases, the position, orientation and number of the load carrying elements in ceilings may be hidden or not be in sight, due for example to the presence of false ceilings or to technical plants. GPR radar can constitute a very useful tool for investigating with rapidity and high resolution, thin as well as very thick ceilings, in a non-destructive manner. Ceilings may be made up as masonry vaults or timber/metal/concrete beams and elements laid down in one or two directions or, again, can be made as a combination of the above. A number of cases are here presented reporting on typical features to be recognised in radargrams in order to distinguish the material and possible shape of the relevant objects with the aim of providing a first small catalogue useful to the radar user and to professionals. This abstract is of interest for COST Action TU1208.

A novel tool for the prediction of tablet sticking during high speed compaction.

PubMed

Abdel-Hamid, Sameh; Betz, Gabriele

2012-01-01

During tableting, capping is a problem of cohesion while sticking is a problem of adhesion. Sticking is a multi-composite problem; causes are either material or machine related. Nowadays, detecting such a problem is a pre-requisite in the early stages of development. The aim of our study was to investigate sticking by radial die-wall pressure monitoring guided by compaction simulation. This was done by using the highly sticking drug; Mefenamic acid (MA) at different drug loadings with different fillers compacted at different pressures and speeds. By increasing MA loading, we found that viscoelastic fillers showed high residual radial pressure after compaction while plastic/brittle fillers showed high radial pressure during compaction, p < 0.05. Visually, plastic/brittle fillers showed greater tendencies for adhesion to punches than viscoelastic fillers while the later showed higher tendencies for adhesion to the die-wall. This was confirmed by higher values of axial stress transmission for plastic/brittle than viscoelastic fillers (higher punch surface/powder interaction), and higher residual die-wall and ejection forces for viscoelastic than plastic/brittle fillers, p < 0.05. Take-off force was not a useful tool to estimate sticking due to cohesive failure of the compacts. Radial die-wall pressure monitoring is suggested as a robust tool to predict sticking.

CFD modelling of abdominal aortic aneurysm on hemodynamic loads using a realistic geometry with CT.

PubMed

Soudah, Eduardo; Ng, E Y K; Loong, T H; Bordone, Maurizio; Pua, Uei; Narayanan, Sriram

2013-01-01

The objective of this study is to find a correlation between the abdominal aortic aneurysm (AAA) geometric parameters, wall stress shear (WSS), abdominal flow patterns, intraluminal thrombus (ILT), and AAA arterial wall rupture using computational fluid dynamics (CFD). Real AAA 3D models were created by three-dimensional (3D) reconstruction of in vivo acquired computed tomography (CT) images from 5 patients. Based on 3D AAA models, high quality volume meshes were created using an optimal tetrahedral aspect ratio for the whole domain. In order to quantify the WSS and the recirculation inside the AAA, a 3D CFD using finite elements analysis was used. The CFD computation was performed assuming that the arterial wall is rigid and the blood is considered a homogeneous Newtonian fluid with a density of 1050 kg/m(3) and a kinematic viscosity of 4 × 10(-3) Pa·s. Parallelization procedures were used in order to increase the performance of the CFD calculations. A relation between AAA geometric parameters (asymmetry index ( β ), saccular index ( γ ), deformation diameter ratio ( χ ), and tortuosity index ( ε )) and hemodynamic loads was observed, and it could be used as a potential predictor of AAA arterial wall rupture and potential ILT formation.

Reentry Thermal Analysis of a Generic Crew Exploration Vehicle Structure

NASA Technical Reports Server (NTRS)

Ko, William L.; Gong, Leslie; Quinn, Robert D.

2007-01-01

Comparative studies were performed on the heat-shielding characteristics of honeycomb-core sandwich panels fabricated with different materials for possible use as wall panels for the proposed crew exploration vehicle. Graphite/epoxy sandwich panel was found to outperform aluminum sandwich panel under the same geometry due to superior heat-shielding qualities and lower material density. Also, representative reentry heat-transfer analysis was performed on the windward wall structures of a generic crew exploration vehicle. The Apollo low Earth orbit reentry trajectory was used to calculate the reentry heating rates. The generic crew exploration vehicle has a graphite/epoxy composite honeycomb sandwich exterior wall and an aluminum honeycomb sandwich interior wall, and is protected with the Apollo thermal protection system ablative material. In the thermal analysis computer program used, the TPS ablation effect was not yet included; however, the results from the nonablation heat-transfer analyses were used to develop a "virtual ablation" method to estimate the ablation heat loads and the thermal protection system recession thicknesses. Depending on the severity of the heating-rate time history, the virtual ablation period was found to last for 87 to 107 seconds and the ablation heat load was estimated to be in the range of 86 to 88 percent of the total heat load for the ablation time period. The thermal protection system recession thickness was estimated to be in the range of 0.08 to 0.11 inches. For the crew exploration vehicle zero-tilt and 18-degree-tilt stagnation points, thermal protection system thicknesses of h = {0.717, 0.733} inches were found to be adequate to keep the substructural composite sandwich temperature below the limit of 300 F.

Micro-engineered first wall tungsten armor for high average power laser fusion energy systems

NASA Astrophysics Data System (ADS)

Sharafat, Shahram; Ghoniem, Nasr M.; Anderson, Michael; Williams, Brian; Blanchard, Jake; Snead, Lance; HAPL Team

2005-12-01

The high average power laser program is developing an inertial fusion energy demonstration power reactor with a solid first wall chamber. The first wall (FW) will be subject to high energy density radiation and high doses of high energy helium implantation. Tungsten has been identified as the candidate material for a FW armor. The fundamental concern is long term thermo-mechanical survivability of the armor against the effects of high temperature pulsed operation and exfoliation due to the retention of implanted helium. Even if a solid tungsten armor coating would survive the high temperature cyclic operation with minimal failure, the high helium implantation and retention would result in unacceptable material loss rates. Micro-engineered materials, such as castellated structures, plasma sprayed nano-porous coatings and refractory foams are suggested as a first wall armor material to address these fundamental concerns. A micro-engineered FW armor would have to be designed with specific geometric features that tolerate high cyclic heating loads and recycle most of the implanted helium without any significant failure. Micro-engineered materials are briefly reviewed. In particular, plasma-sprayed nano-porous tungsten and tungsten foams are assessed for their potential to accommodate inertial fusion specific loads. Tests show that nano-porous plasma spray coatings can be manufactured with high permeability to helium gas, while retaining relatively high thermal conductivities. Tungsten foams where shown to be able to overcome thermo-mechanical loads by cell rotation and deformation. Helium implantation tests have shown, that pulsed implantation and heating releases significant levels of implanted helium. Helium implantation and release from tungsten was modeled using an expanded kinetic rate theory, to include the effects of pulsed implantations and thermal cycles. Although, significant challenges remain micro-engineered materials are shown to constitute potential candidate FW armor materials.

Evaluation of the thermal and structural performance of straw bale construction

NASA Astrophysics Data System (ADS)

Beaudry, Kyle R.

This thesis is primarily divided into two distinct experimental programs evaluating: 1) the thermal performance and, 2) the structural performance of straw bale construction. The thermal performance chapter describes hot-box testing (based on ASTM C1363-11) of seven straw bale wall panels to obtain their apparent thermal conductivity values. All panels were constructed with stacked bales and cement-lime plaster skins on each side of the bales. Four panels were made with traditional, 2-string field bales of densities ranging from 89.5 kg/m3 - 131 kg/m3 and with the bales on-edge (fibres perpendicular to the heat flow). Three panels were made with manufactured high-density bales (291 kg/m3 - 372 kg/m3). The fibres of the manufactured bales were randomly oriented. The key conclusion of this work is that within the experimental error, there is no difference in the apparent thermal conductivity value for panels using normal density bales and manufactured high-density bales up to a density of 333 kg/m3. The structural performance chapter describes gravity and transverse load testing (based on ASTM E72-15) of non-plastered modular straw bale wall (DBW) panels to evaluate their strength capacity and failure modes. The out-of-plane flexural (OPF) tests exhibited a mean ultimate bending moment of 49.7 kNm. The axial compression (AC) tests exhibited a mean ultimate line load of 161.0 kN/m. The local flexural header beam (HP) tests exhibited an ultimate line load of 31.6 kN/m. The OPF and AC capacities of the DBW exceeded the capacities exhibited by a conventional 38 mm x 140 mm stud wall. However, the DBW's header beam strength and stiffness was inferior to conventional stud wall.

Constructive systems, load-bearing and enclosing structures of high-rise buildings

NASA Astrophysics Data System (ADS)

Anatol'evna Korol', Elena; Olegovna Kustikova, Yuliya

2018-03-01

As the height of the building increases, loads on load-carrying structures increase dramatically, and as a result of the development of high-rise construction, several structural systems of such buildings have been developed: frame, frame-frame, cross-wall, barrel, box-type, box-to-wall ("pipe in pipe", "Trumpet in the farm"), etc. In turn, the barrel systems have their own versions: cantilever support of the ceilings on the trunk, suspension of the outer part of the overlap to the upper carrying console "hanging house" or its support by means of the walls on the lower bearing cantilever, intermediate position of the supporting cantilevers in height to the floor, from a part of floors. The object of the study are the structural solutions of high-rise buildings. The subject of the study is the layout of structural schemes of high-rise buildings, taking into account the main parameters - altitude (height), natural climatic conditions of construction, materials of structural elements and their physical and mechanical characteristics. The purpose of the study is to identify the features and systematization of structural systems of high-rise buildings and the corresponding structural elements. The results of the research make it possible, at the stage of making design decisions, to establish rational parameters for the correspondence between the structural systems of high-rise buildings and their individual elements.

Athlete's Heart: Is the Morganroth Hypothesis Obsolete?

PubMed

Haykowsky, Mark J; Samuel, T Jake; Nelson, Michael D; La Gerche, Andre

2018-05-01

In 1975, Morganroth and colleagues reported that the increased left ventricular (LV) mass in highly trained endurance athletes versus nonathletes was primarily due to increased end-diastolic volume while the increased LV mass in resistance trained athletes was solely due to an increased LV wall thickness. Based on the divergent remodelling patterns observed, Morganroth and colleagues hypothesised that the increased "volume" load during endurance exercise may be similar to that which occurs in patients with mitral or aortic regurgitation while the "pressure" load associated with performing a Valsalva manoeuvre (VM) during resistance exercise may mimic the stress imposed on the heart by systemic hypertension or aortic stenosis. Despite widespread acceptance of the four-decade old Morganroth hypothesis in sports cardiology, some investigators have questioned whether such a divergent "athlete's heart" phenotype exists. Given this uncertainty, the purpose of this brief review is to re-evaluate the Morganroth hypothesis regarding: i) the acute effects of resistance exercise performed with a brief VM on LV wall stress, and the patterns of LV remodelling in resistance-trained athletes; ii) the acute effects of endurance exercise on biventricular wall stress, and the time course and pattern of LV and right ventricular (RV) remodelling with endurance training; and iii) the value of comparing "loading" conditions between athletes and patients with cardiac pathology. Copyright © 2018. Published by Elsevier B.V.

Axial compression behaviour of reinforced wallettes fabricated using wood-wool cement panel

NASA Astrophysics Data System (ADS)

Noh, M. S. Md; Kamarudin, A. F.; Mokhatar, S. N.; Jaudin, A. R.; Ahmad, Z.; Ibrahim, A.; Muhamad, A. A.

2018-04-01

Wood-wool cement composite panel (WWCP) is one of wood based composite material that produced in a stable panel form and suitable to be used as building wall system to replace non-ecofriendly material such as brick and other masonry element. Heavy construction material such as brick requires more manpower and consume a lot of time to build the wall panel. WWCP is a lightweight material with a density range from 300 kg/m3 to 500 kg/m3 and also capable to support an imposed load from the building. This study reported on the axial compression behaviour of prefabricated reinforced wallettes constructed with wood-wool cement panel. A total of six specimens were fabricated using two layers of cross laminated WWCP bonded with normal mortar paste (Portland cement) at a mix ratio of 1:3 (cement : sand). As part of lifting mechanism, the wallettes were equipped with three steel reinforcement (T12) that embedded inside the core of wallettes. Three replicates of wallettes specimens with dimension 600 mm width and 600 mm length were fabricated without surface plaster and with 16 mm thickness of surface plaster. The wallettes were tested under axial compression load after 28 days of fabrication until failure. The result indicated that, the application of surface plaster significantly increases the loading capacity about 35 % and different orientation of the panels improve the bonding strength of the wall.

Experimental study of plastic responses of pipe elbows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenstreet, W.L.

Load-deflection responses were determined experimentally for sixteen 152.4-mm (6-in.) (nominal) commercial carbon steel pipe elbows and four 152.4-mm (6-in.) stainless steel elbows. Each specimen was loaded with an external force of sufficient magnitude to produce predominantly plastic response. The influences of bend radius and wall thickness were studied, as well as the effect of internal prssure on load-deflection behavior. Comparisons of results from stainless steel and from carbon steel elbows indicate differences in responses attributable to material differences. The results were interpreted in terms of limit analysis concepts, and collapse loads were determined. Trends given by the collapse loads aremore » identified and discussed.« less

Solute load concentrations in some streams in the Upper Osun and Owena drainage basins, central western Nigeria

NASA Astrophysics Data System (ADS)

Jeje, L. K.; Ogunkoya, O. O.; Oluwatimilehin, J. M.

1999-12-01

The solute load dynamics of 12 third-order streams in central western Nigeria are presented, during storm and non-storm runoff events. The relevance of the Walling and Foster model for explaining storm period solute load dynamics in the humid tropical environment was assessed and it was found that this model was generally applicable to the study area. Exceptions appear to be streams draining settlements and/or farms where fertilizers are applied heavily. The solute load ranged from 5 mg l -1 to 580 mg l -1 with streams draining basins with tree-crop plantations ( Theobroma cacao, Cola sp.) as the dominant land cover having the highest solute load.

Physics-Based Simulation and Experiment on Blast Protection of Infill Walls and Sandwich Composites Using New Generation of Nano Particle Reinforced Materials

NASA Astrophysics Data System (ADS)

Irshidat, Mohammad

A critical issue for the development of nanotechnology is our ability to understand, model, and simulate the behavior of small structures and to make the connection between nano structure properties and their macroscopic functions. Material modeling and simulation helps to understand the process, to set the objectives that could guide laboratory efforts, and to control material structures, properties, and processes at physical implementation. These capabilities are vital to engineering design at the component and systems level. In this research, experimental-computational-analytical program was employed to investigate the performance of the new generation of polymeric nano-composite materials, like nano-particle reinforced elastomeric materials (NPREM), for the protection of masonry structures against blast loads. New design tools for using these kinds of materials to protect Infill Walls (e.g. masonry walls) against blast loading were established. These tools were also extended to cover other type of panels like sandwich composites. This investigation revealed that polymeric nano composite materials are strain rate sensitive and have large amount of voids distributed randomly inside the materials. Results from blast experiments showed increase in ultimate flexural resistance achieved by both unreinforced and nano reinforced polyurea retrofit systems applied to infill masonry walls. It was also observed that a thin elastomeric coating on the interior face of the walls could be effective at minimizing the fragmentation resulting from blast. More conclusions are provided with recommended future research.

Failure mechanism of shear-wall dominant multi-story buildings

USGS Publications Warehouse

Yuksel, S.B.; Kalkan, E.

2008-01-01

The recent trend in the building industry of Turkey as well as in many European countries is towards utilizing the tunnel form (shear-wall dominant) construction system for development of multi-story residential units. The tunnel form buildings diverge from other conventional reinforced concrete (RC) buildings due to the lack of beams and columns in their structural integrity. The vertical load-carrying members of these buildings are the structural-walls only, and the floor system is a flat plate. Besides the constructive advantages, tunnel form buildings provide superior seismic performance compared to conventional RC frame and dual systems as observed during the recent devastating earthquakes in Turkey (1999 Mw 7.4 Kocaeli, Mw 7.2 Duzce, and 2004 Mw 6.5 Bingol). With its proven earthquake performance, the tunnel form system is becoming the primary construction technique in many seismically active regions. In this study, a series of nonlinear analyses were conducted using finite element (FE) models to augment our understanding on their failure mechanism under lateral forces. In order to represent the nonlinear behavior adequately, The FE models were verified with the results of experimental studies performed on three dimensional (3D) scaled tunnel form building specimens. The results of this study indicate that the structural walls of tunnel form buildings may exhibit brittle flexural failure under lateral loading, if they are not properly reinforced. The global tension/compression couple triggers this failure mechanism by creating pure axial tension in the outermost shear-walls.

Buckling Behavior of Compression-Loaded Composite Cylindrical Shells with Reinforced Cutouts

NASA Technical Reports Server (NTRS)

Hilburger, Mark W.; Starnes, James H., Jr.

2002-01-01

Results from a numerical study of the response of thin-wall compression-loaded quasi-isotropic laminated composite cylindrical shells with reinforced and unreinforced square cutouts are presented. The effects of cutout reinforcement orthotropy, size, and thickness on the nonlinear response of the shells are described. A high-fidelity nonlinear analysis procedure has been used to predict the nonlinear response of the shells. The analysis procedure includes a nonlinear static analysis that predicts stable response characteristics of the shells and a nonlinear transient analysis that predicts unstable dynamic buckling response characteristics. The results illustrate how a compression-loaded shell with an unreinforced cutout can exhibit a complex nonlinear response. In particular, a local buckling response occurs in the shell near the cutout and is caused by a complex nonlinear coupling between local shell-wall deformations and in-plane destabilizing compression stresses near the cutout. In general, the addition of reinforcement around a cutout in a compression-loaded shell can retard or eliminate the local buckling response near the cutout and increase the buckling load of the shell, as expected. However, results are presented that show how certain reinforcement configurations can actually cause an unexpected increase in the magnitude of local deformations and stresses in the shell and cause a reduction in the buckling load. Specific cases are presented that suggest that the orthotropy, thickness, and size of a cutout reinforcement in a shell can be tailored to achieve improved response characteristics.

Novel nano bearings constructed by physical adsorption

PubMed Central

Zhang, Yongbin

2015-01-01

The paper proposes a novel nano bearing formed by the physical adsorption of the confined fluid to the solid wall. The bearing is formed between two parallel smooth solid plane walls sliding against one another, where conventional hydrodynamic lubrication theory predicted no lubricating effect. In this bearing, the stationary solid wall is divided into two subzones which respectively have different interaction strengths with the lubricating fluid. It leads to different physical adsorption and slip properties of the lubricating fluid at the stationary solid wall respectively in these two subzones. It was found that a significant load-carrying capacity of the bearing can be generated for low lubricating film thicknesses, because of the strong physical adsorption and non-continuum effects of the lubricating film. PMID:26412488

The effect of screw tunnels on the biomechanical stability of vertebral body after pedicle screws removal: a finite element analysis.

PubMed

Liu, Jia-Ming; Zhang, Yu; Zhou, Yang; Chen, Xuan-Yin; Huang, Shan-Hu; Hua, Zi-Kai; Liu, Zhi-Li

2017-06-01

Posterior reduction and pedicle screw fixation is a widely used procedure for thoracic and lumbar vertebrae fractures. Usually, the pedicle screws would be removed after the fracture healing and screw tunnels would be left. The aim of this study is to evaluate the effect of screw tunnels on the biomechanical stability of the lumbar vertebral body after pedicle screws removal by finite element analysis (FEA). First, the CT values of the screw tunnels wall in the fractured vertebral bodies were measured in patients whose pedicle screws were removed, and they were then compared with the values of vertebral cortical bone. Second, an adult patient was included and the CT images of the lumbar spine were harvested. Three dimensional finite element models of the L1 vertebra with unilateral or bilateral screw tunnels were created based on the CT images. Different compressive loads were vertically acted on the models. The maximum loads which the models sustained and the distribution of the force in the different parts of the models were recorded and compared with each other. The CT values of the tunnels wall and vertebral cortical bone were 387.126±62.342 and 399.204±53.612, which were not statistically different (P=0.149). The models of three dimensional tetrahedral mesh finite element of normal lumbar 1 vertebra were established with good geometric similarity and realistic appearance. After given the compressive loads, the cortical bone was the first one to reach its ultimate stress. The maximum loads which the bilateral screw tunnels model, unilateral screw tunnel model, and normal vertebral model can sustain were 3.97 Mpa, 3.83 Mpa, and 3.78 Mpa, respectively. For the diameter of the screw tunnels, the model with a diameter of 6.5 mm could sustain the largest load. In addition, the stress distributing on the outside of the cortical bone gradually decreased as the thickness of the tunnel wall increased. Based on the FEA, pedicle screw tunnels would not decrease the biomechanical stability and strength of the vertebral body. A large diameter of screw tunnel and thick tunnel wall were helpful for the biomechanical stability of the vertebral body.

45 CFR 98.2 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... decree, the grandchild, great grandchild, sibling (if such provider lives in separate residence), niece...) structural changes to the foundation, roof, floor, exterior or load-bearing walls of a facility, or the...

45 CFR 98.2 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... decree, the grandchild, great grandchild, sibling (if such provider lives in separate residence), niece...) structural changes to the foundation, roof, floor, exterior or load-bearing walls of a facility, or the...

45 CFR 98.2 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... decree, the grandchild, great grandchild, sibling (if such provider lives in separate residence), niece...) structural changes to the foundation, roof, floor, exterior or load-bearing walls of a facility, or the...

45 CFR 98.2 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... decree, the grandchild, great grandchild, sibling (if such provider lives in separate residence), niece...) structural changes to the foundation, roof, floor, exterior or load-bearing walls of a facility, or the...

45 CFR 98.2 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... decree, the grandchild, great grandchild, sibling (if such provider lives in separate residence), niece...) structural changes to the foundation, roof, floor, exterior or load-bearing walls of a facility, or the...

High-speed propeller noise predictions - Effects of boundary conditions used in blade loading calculations

NASA Technical Reports Server (NTRS)

Nallasamy, M.; Clark, B. J.; Groeneweg, J. F.

1987-01-01

The acoustics of an advanced single rotation SR-3 propeller at cruise conditions are studied employing a time-domain approach. The study evaluates the acoustic significance of the differences in blade pressures computed using nonreflecting rather than hard wall boundary conditions in the three-dimensional Euler code solution. The directivities of the harmonics of the blade passing frequency tone and the effects of chordwise loading on tone directivity are examined. The results show that the maximum difference in the computed sound pressure levels due to the use of blade pressure distributions obtained with the nonreflecting rather than the hard wall boundary conditions is about 1.5 dB. The blade passing frequency tone directivity obtained in the present study shows good agreement with jetstar flight data.

High-speed propeller noise predictions: Effects of boundary conditions used in blade loading calculations

NASA Technical Reports Server (NTRS)

Nallasamy, M.; Clark, B. J.; Groeneweg, J. F.

1987-01-01

The acoustics of an advanced single rotation SR-3 propeller at cruise conditions are studied employing a time-domain approach. The study evaluates the acoustic significance of the differences in blade pressures computed using nonreflecting rather than hard wall boundary conditions in the three-dimensional Euler code solution. The directivities of the harmonics of the blade passing frequency tone and the effects of chordwise loading on tone directivity are examined. The results show that the maximum difference in the computed sound pressure levels due to the use of blade pressure distributions obtained with the nonreflecting rather than the hard wall boundary conditions is about 1.5 dB. The blade passing frequency tone directivity obtained in the present study shows good agreement with jetstar flight data.

Combuster. [low nitrogen oxide formation

NASA Technical Reports Server (NTRS)

Mckay, R. A. (Inventor)

1978-01-01

A combuster is provided for utilizing a combustible mixture containing fuel and air, to heat a load fluid such as water or air, in a manner that minimizes the formation of nitrogen oxide. The combustible mixture passes through a small diameter tube where the mixture is heated to its combustion temperature, while the load fluid flows past the outside of the tube to receive heat. The tube is of a diameter small enough that the combustible mixture cannot form a flame, and yet is not subject to wall quench, so that combustion occurs, but at a temperature less than under free flame conditions. Most of the heat required for heating the combustible mixture to its combustion temperature, is obtained from heat flow through the walls of the pipe to the mixture.

Mechanism for Increasing the Pressure in an Oil Well by a Combustible Oxidizing Liquid Mixture

NASA Astrophysics Data System (ADS)

Melik-Gaikazov, G. V.

2014-09-01

A method of estimating the pressure pulse arising in a deep oil well as a result of the thermal explosion of a combustible oxidizing liquid mixture in it is presented. It was established that less than 10% of this mixture is expended for the formation of a pressure pulse in this well. The conditions under which a tubing string positioned in such a well experiences a plastic bending and its walls are crumpled were determined. The maximum admissible difference between the pressures at the walls of this tube were calculated, and axial compression loads were related to critical forces of different orders. It is shown that, when the indicated tube is submerged in the liquid in the well, its resistance to a short-time axial compression load increases.

Structural Analysis of Helios Filament-Wound Tanks Subjected to Internal Pressure and Cooling

NASA Technical Reports Server (NTRS)

Ko, William L

2005-01-01

A finite-element stress analysis is performed on Helios filament-wound hydrogen tanks to examine the stress field and effect of end dome geometry on the stress field. Each tank is composed of a central circular cylindrical section with either geodesic or hemispherical end domes, which have metallic polar bosses. The tanks are subjected to combined and separate internal pressure and temperature loading conditions, and the stress contributions of each loading component are examined. The tank-wall-polar-boss interfacial meridional tensile stress in the hemispherical dome is found to be approximately 27 percent lower than that in the geodesic dome. The effects of both material anisotropy and the aluminum lining on the intensities of tensile meridional stress at the tank-wall-polar-boss bonding interface are examined.

The Acid Growth Theory of auxin-induced cell elongation is alive and well

NASA Technical Reports Server (NTRS)

Rayle, D. L.; Cleland, R. E.

1992-01-01

Plant cells elongate irreversibly only when load-bearing bonds in the walls are cleaved. Auxin causes the elongation of stem and coleoptile cells by promoting wall loosening via cleavage of these bonds. This process may be coupled with the intercalation of new cell wall polymers. Because the primary site of auxin action appears to be the plasma membrane or some intracellular site, and wall loosening is extracellular, there must be communication between the protoplast and the wall. Some "wall-loosening factor" must be exported from auxin-impacted cells, which sets into motion the wall loosening events. About 20 years ago, it was suggested that the wall-loosening factor is hydrogen ions. This idea and subsequent supporting data gave rise to the Acid Growth Theory, which states that when exposed to auxin, susceptible cells excrete protons into the wall (apoplast) at an enhanced rate, resulting in a decrease in apoplastic pH. The lowered wall pH then activates wall-loosening processes, the precise nature of which is unknown. Because exogenous acid causes a transient (1-4 h) increase in growth rate, auxin must also mediate events in addition to wall acidification for growth to continue for an extended period of time. These events may include osmoregulation, cell wall synthesis, and maintenance of the capacity of walls to undergo acid-induced wall loosening. At present, we do not know if these phenomena are tightly coupled to wall acidification or if they are the products of multiple independent signal transduction pathways.

The effect of shear wall location in resisting earthquake

NASA Astrophysics Data System (ADS)

Tarigan, J.; Manggala, J.; Sitorus, T.

2018-02-01

Shear wall is one of lateral resisting structure which is used commonly. Shear wall gives high stiffness to the structure so as the structure will be stable. Applying shear wall can effectively reduce the displacement and story-drift of the structure. This will reduce the destruction comes from lateral loads such as an earthquake. Earlier studies showed that shear wall gives different performance based on its position in structures. In this paper, seismic analysis has been performed using response spectrum method for different Model of structures; they are the open frame, the shear wall at core symmetrically, the shear wall at periphery symmetrically, and the shear wall at periphery asymmetrically. The results are observed by comparing the displacement and story-drift. Based on the analysis, the placement of shear wall at the core of structure symmetrically gives the best performance to reduce the displacement and story-drift. It can reduce the displacement up to 61.16% (X-dir) and 70.60% (Y-dir). The placement of shear wall at periphery symmetrically will reduce the displacement up to 53.85% (X-dir) and 47.87% (Y-dir) while the placement of shear wall at periphery asymmetrically reducing the displacement up to 59.42% (X-dir) and 66.99% (Y-dir).

System for loading slab-gel holders for electrophoresis separation

DOEpatents

Anderson, Norman G.; Anderson, Norman L.

1979-01-01

A slab-gel loading system includes a prismatic chamber for filling a plurality of slab-gel holders simultaneously. Each slab-gel holder comprises a pair of spaced apart plates defining an intermediate volume for gel containment. The holders are vertically positioned in the chamber with their major surfaces parallel to the chamber end walls. A liquid inlet is provided at the corner between the bottom and a side wall of the chamber for distributing a polymerizable monomer solution or a coagulable colloidal solution into each of the holders. The chamber is rotatably supported so that filling can begin with the corner having the liquid inlet directed downwardly such that the solution is gently funneled upwardly, without mixing, along the diverging side and bottom surfaces. As filling proceeds, the chamber is gradually rotated to position the bottom wall in a horizontal mode. The liquid filling means includes a plastic envelope with a septum dividing it into two compartments for intermixing two solutions of different density and thereby providing a liquid flow having a density gradient. The resulting gels have a density gradient between opposite edges for subsequent use in electrophoresis separations.

Synthesis and evaluation of multi-wall carbon nanotube-paclitaxel complex as an anti-cancer agent.

PubMed

Ghasemvand, Fariba; Biazar, Esmaeil; Tavakolifard, Sara; Khaledian, Mohammad; Rahmanzadeh, Saeid; Momenzadeh, Daruosh; Afroosheh, Roshanak; Zarkalami, Faezeh; Shabannezhad, Marjan; Hesami Tackallou, Saeed; Massoudi, Nilofar; Heidari Keshel, Saeed

2016-01-01

The aim of this study was to design multi-walled carbon nanotubes (MWCNTs) loaded with paclitaxel (PTX) anti-cancer drug and investigate its anti-cancerous efficacy of human gastric cancer. Carbon nanotubes (CNTs) represent a novel nano-materials applied in various fields such as drug delivery due to their unique chemical properties and high drug loading. In this study, multi-walled carbon nanotubes (MWCNTs) pre-functionalized covalently with a paclitaxel (PTX) as an anti-cancer drug and evaluated by different analyses including, scanning electron microscope (SEM), particle size analyzer and cellular analyses. A well conjugated of anti-cancer drug on the carbon nanotube surfaces was shown. This study demonstrates that the MWCN-PTX complex is a potentially useful system for delivery of anti-cancer drugs. The flow cytometry, CFU and MTT assay results have disclosed that MWCNT/PTXs might promote apoptosis in MKN-45 gastric adenocarcinoma cell line. According to results, our simple method can be designed a candidate material for chemotherapy. It has presented a few bio-related applications including, their successful use as a nano-carriers for drug transport.

The characean internodal cell as a model system for studying wound healing

PubMed Central

Foissner, I.; Wasteneys, G.O.

2012-01-01

Summary This work describes the characean internodal cell as a model system for the study of wound healing and compares wounds induced by certain chemicals and UV irradiation with wounds occurring in the natural environment. We review the existing literature and define three types of wound response: 1) cortical window formation characterized by disassembly of microtubules, transient inhibition of actin-dependent cytoplasmic streaming and chloroplast detachment, 2) fibrillar wound walls characterized by exocytosis of vesicles carrying wall polysaccharides and membrane-bound cellulose synthase complexes coupled with endocytosis of surplus membrane and 3) amorphous, callose- and membrane-containing wound walls characterized by exocytosis of vesicles and endoplasmic reticulum (ER) cisternae in the absence of membrane recycling. We hypothesize that these three wound responses reflect the extent of damage, probably Ca2+ influx, and that the secretion of Ca2+ - loaded ER cisternae is an emergency reaction in case of severe Ca2+ load. Microtubules are not required for wound healing but their disassembly could have a signalling function. Transient reorganization of the actin cytoskeleton into a meshwork of randomly oriented filaments is required for the migration of wound wall forming organelles, just as occurs in tip-growing plant cells. New data presented in this study show that during the deposition of an amorphous wound wall numerous actin rings are present, which may indicate specific ion fluxes and/or a storage form for actin. In addition, we present new evidence for the exocytosis of FM1-43-stained organelles, putative endosomes, required for plasma membrane repair during wound healing. Finally we show that quickly growing fibrillar wound walls, even when deposited in the absence of microtubules, have a highly ordered helical structure of consistent handedness comprised of cellulose microfibrils. PMID:22118365

Thermo-sensitive liposomes loaded with doxorubicin and lysine modified single-walled carbon nanotubes as tumor-targeting drug delivery system.

PubMed

Zhu, Xiali; Xie, Yingxia; Zhang, Yingjie; Huang, Heqing; Huang, Shengnan; Hou, Lin; Zhang, Huijuan; Li, Zhi; Shi, Jinjin; Zhang, Zhenzhong

2014-11-01

This report focuses on the thermo-sensitive liposomes loaded with doxorubicin and lysine-modified single-walled carbon nanotube drug delivery system, which was designed to enhance the anti-tumor effect and reduce the side effects of doxorubicin. Doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes was prepared by reverse-phase evaporation method, the mean particle size was 232.0 ± 5.6 nm, and drug entrapment efficiency was 86.5 ± 3.7%. The drug release test showed that doxorubicin released more quickly at 42℃ than at 37℃. Compared with free doxorubicin, doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes could efficiently cross the cell membranes and afford higher anti-tumor efficacy on the human hepatic carcinoma cell line (SMMC-7721) cells in vitro. For in vivo experiments, the relative tumor volumes of the sarcomaia 180-bearing mice in thermo-sensitive liposomes group and doxorubicin group were significantly smaller than those of N.S. group. Meanwhile, the combination of near-infrared laser irradiation at 808 nm significantly enhanced the tumor growth inhibition both on SMMC-7721 cells and the sarcomaia 180-bearing mice. The quality of life such as body weight, mental state, food and water intake of sarcomaia 180 tumor-bearing mice treated with doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes were much higher than those treated with doxorubicin. In conclusion, doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes combined with near-infrared laser irradiation at 808 nm may potentially provide viable clinical strategies for targeting delivery of anti-cancer drugs. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Comparisons of four computer models with experimental data from test buildings in northern New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robertson, D.K.; Christian, J.E.

1985-01-01

Eight one-room test buildings, 20 ft (6.1 m) square and 7.5 ft (2.3 m) high, were constructed on a high desert site near Tesuque Pueblo, New Mexico, to study the influence of wall dynamic heat transfer characteristics on building heating requirements (the ''thermal mass effect''). The buildings are nominally identical except for the walls (adobe, concrete and masonry unit, wood-frame, and log) and are constructed so as to isolate the effects of the walls. The amount of mass in the walls varies from 240 lb/ft/sup 2/ (1171 kg/m/sup 2/) for the 2 ft (.61 m) thick adobe wall to 4.3more » lb/ft/sup 2/ (21 kg/m/sup 2/) for the insulated wood-frame wall. The roof, floor, and stem walls are all well insulated and the buildings were constructed with infiltration rates less than 0.4 air change per hour. The site is instrumented to record building component temperatures and heat fluxes, outside weather conditions, and heating energy use. Data were collected for two heating seasons from midwinter to late spring with the buildings in two configurations, with and without windows. Four computer codes were used to simulate the performance of the test buildings without windows, using site weather data. The codes used were DOE-2.1A, DOE-2.1C, BLAST, and DEROB. Each code was run by a different analyst. Simulations were done for midwinter, late winter, and spring. Two of the test cell comparisons are discussed; the insulated frame and an 11-in. (.28 m) adobe. This work presents a quantitative and qualitative critical comparison of the modeling and experimental results. Cumulative heating loads, wall heat fluxes, and air surface temperatures are compared, as well as input assumptions to the models. Explanations of differences and difficulties encountered are reported. The principal findings were that cumulative heating loads and the characteristic influences of wall thermal mass on hourly behavior were reproduced by the models.« less

Unsteady pressure loads in a generic high speed engine model

NASA Technical Reports Server (NTRS)

Parrott, Tony L.; Jones, Michael G.; Thurlow, Ernie M.

1992-01-01

Unsteady pressure loads were measured along the top interior wall of a generic high-speed engine (GHSE) model undergoing performance tests in the combustion-Heated Scramjet Test Facility at the Langley Research Center. Flow to the model inlet was simulated at 72000 ft and a flight Mach number of 4. The inlet Mach number was 3.5 with a total temperature and pressure of 1640 R and 92 psia. The unsteady pressure loads were measured with 5 piezoresistive gages, recessed into the wall 4 to 12 gage diameters to reduce incident heat flux to the diaphragms, and distributed from the inlet to the combustor. Contributors to the unsteady pressure loads included boundary layer turbulence, combustion noise, and transients generated by unstart loads. Typical turbulent boundary layer rms pressures in the inlet ranged from 133 dB in the inlet to 181 dB in the combustor over the frequency range from 0 to 5 kHz. Downstream of the inlet exist, combustion noise was shown to dominate boundary layer turbulence noise at increased heat release rates. Noise levels in the isolator section increased by 15 dB when the fuel-air ratio was increased from 0.37 to 0.57 of the stoichiometric ratio. Transient pressure disturbances associated with engine unstarts were measured in the inlet and have an upstream propagation speed of about 7 ft/sec and pressure jumps of at least 3 psia.

Impact of isotropic constitutive descriptions on the predicted peak wall stress in abdominal aortic aneurysms.

PubMed

Man, V; Polzer, S; Gasser, T C; Novotny, T; Bursa, J

2018-03-01

Biomechanics-based assessment of Abdominal Aortic Aneurysm (AAA) rupture risk has gained considerable scientific and clinical momentum. However, computation of peak wall stress (PWS) using state-of-the-art finite element models is time demanding. This study investigates which features of the constitutive description of AAA wall are decisive for achieving acceptable stress predictions in it. Influence of five different isotropic constitutive descriptions of AAA wall is tested; models reflect realistic non-linear, artificially stiff non-linear, or artificially stiff pseudo-linear constitutive descriptions of AAA wall. Influence of the AAA wall model is tested on idealized (n=4) and patient-specific (n=16) AAA geometries. Wall stress computations consider a (hypothetical) load-free configuration and include residual stresses homogenizing the stresses across the wall. Wall stress differences amongst the different descriptions were statistically analyzed. When the qualitatively similar non-linear response of the AAA wall with low initial stiffness and subsequent strain stiffening was taken into consideration, wall stress (and PWS) predictions did not change significantly. Keeping this non-linear feature when using an artificially stiff wall can save up to 30% of the computational time, without significant change in PWS. In contrast, a stiff pseudo-linear elastic model may underestimate the PWS and is not reliable for AAA wall stress computations. Copyright © 2018 IPEM. Published by Elsevier Ltd. All rights reserved.

Flame structure of wall-impinging diesel fuel sprays injected by group-hole nozzles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Jian; Moon, Seoksu; Nishida, Keiya

This paper describes an investigation of the flame structure of wall-impinging diesel sprays injected by group-hole nozzles in a constant-volume combustion vessel at experimental conditions typical of a diesel engine. The particular emphasis was on the effect of the included angle between two orifices (0-15 deg. in current study) on the flame structure and combustion characteristics under various simulated engine load conditions. The laser absorption scattering (LAS) technique was applied to analyze the spray and mixture properties. Direct flame imaging and OH chemiluminescence imaging were utilized to quantify the ignition delay, flame geometrical parameters, and OH chemiluminescence intensity. The imagesmore » show that the asymmetric flame structure emerges in wall-impinging group-hole nozzle sprays as larger included angle and higher engine load conditions are applied, which is consistent with the spray shape observed by LAS. Compared to the base nozzle, group-hole nozzles with large included angles yield higher overall OH chemiluminescence intensity, wider flame area, and greater proportion of high OH intensity, implying the better fuel/air mixing and improved combustion characteristics. The advantages of group-hole nozzle are more pronounced under high load conditions. Based on the results, the feasibility of group-hole nozzle for practical direct injection diesel engines is also discussed. It is concluded that the asymmetric flame structure of a group-hole nozzle spray is favorable to reduce soot formation over wide engine loads. However, the hole configuration of the group-hole nozzle should be carefully considered so as to achieve proper air utilization in the combustion chamber. Stoichiometric diesel combustion is another promising application of group-hole nozzle. (author)« less

Analysis and Design of Connections, Openings and Attachments for Protective Construction

DTIC Science & Technology

1989-10-01

precast connection details were subjected to cyclic simulated earthquake loads . The detail... column and beam flexural steel. At the onset of flexural yield under cyclical loading , crack sizes at the face of the joint increase and reinforcement... beam / column connections may be a necessity and can be placed without a great deal of difficulty. However, their placement in slab/wall connections

Effects of transverse shear deformation on buckling of laminated cylinders as a function of thickness and ply orientation

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.

1987-01-01

Buckling loads of thick-walled, orthotropic, simply-supported right circular cylinders are predicted using a new higher-order transverse shear deformation theory. The higher-order theory shows that, by more accurately accounting for transverse shear deformation effects, the predicted buckling load may be reduced by as much as 80 percent compared to predictions based on conventional transverse shear deformation theory. A parametric study of the effect of ply orientation on the buckling load of axially compressed cylinders indicates that laminates containing 0 deg plies are the most sensitive to transverse shear deformation effects. Interaction curves for buckling of cylinders with axial compressive and external pressure loadings indicate that buckling loads due to external pressure loadings are much less sensitive to transverse shear deformation effects than those due to axial compressive loadings.

LOADED WAVE GUIDES FOR LINEAR ACCELERATORS

DOEpatents

Walkinshaw, W.; Mullett, L.B.

1959-12-01

A periodically loaded waveguide having substantially coaxially arranged elements which provide an axial field for the acceleration of electrons is described. Radiofrequency energy will flow in the space between the inner wall of an outer guide and the peripheries of equally spaced irises or washes arranged coaxially with each other and with the outer guide, where the loading due to the geometry of the irises is such as to reduce the phase velocity of the r-f energy flowing in the guide from a value greater than that of light to the velocity of light or less.

Development of response models for the Earth Radiation Budget Experiment (ERBE) sensors. Part 2: Analysis of the ERBE integrating sphere ground calibration

NASA Technical Reports Server (NTRS)

Halyo, Nesim; Taylor, Deborah B.

1987-01-01

An explicit solution of the spectral radiance leaving an arbitrary point on the wall of a spherical cavity with diffuse reflectivity is obtained. The solution is applicable to spheres with an arbitrary number of openings of any size and shape, an arbitrary number of light sources with possible non-diffuse characteristics, a non-uniform sphere wall temperature distribution, non-uniform and non-diffuse sphere wall emissivity and non-uniform but diffuse sphere wall spectral reflectivity. A general measurement equation describing the output of a sensor with a given field of view, angular and spectral response measuring the sphere output is obtained. The results are applied to the Earth Radiation Budget Experiment (ERBE) integrating sphere. The sphere wall radiance uniformity, loading effects and non-uniform wall temperature effects are investigated. It is shown that using appropriate interpretation and processing, a high-accuracy short-wave calibration of the ERBE sensors can be achieved.

The forced sound transmission of finite single leaf walls using a variational technique.

PubMed

Brunskog, Jonas

2012-09-01

The single wall is the simplest element of concern in building acoustics, but there still remain some open questions regarding the sound insulation of this simple case. The two main reasons for this are the effects on the excitation and sound radiation of the wall when it has a finite size, and the fact that the wave field in the wall is consisting of two types of waves, namely forced waves due to the exciting acoustic field, and free bending waves due to reflections in the boundary. The aim of the present paper is to derive simple analytical formulas for the forced part of the airborne sound insulation of a single homogeneous wall of finite size, using a variational technique based on the integral-differential equation of the fluid loaded wall. The so derived formulas are valid in the entire audible frequency range. The results are compared with full numerical calculations, measurements and alternative theory, with reasonable agreement.

Simulation of interior ballistics flows in a shock tube

NASA Astrophysics Data System (ADS)

Seiler, F.

1983-07-01

The flow in front of and behind a projectile was investigated in a interior ballistics shock tube simulator. Flow patterns and heat flow were examined for flows with and without gas leakage. The boundary layers behind the piston can clearly be shown by differential interferograms. The dependence of the heat flow into the measuring tube wall on the base form is smaller than the signal perturbations. Flow patterns show no appreciable effect of gas leakage on the flow behind the piston; strong flow effects arise in front of the piston. The same effects are shown by heat flow measurements. In case of gas leakage heat flows into the tube wall before the piston reaches the wall. In the slit between piston and wall a maximum heat flow is found. High temperature gradients, due to the fact that hot gases come closer to the tube wall than in the boundary layer flow behind the piston, lead to high thermal loading of the wall materials which can cause cracks.

Inverse measurement of wall pressure field in flexible-wall wind tunnels using global wall deformation data

NASA Astrophysics Data System (ADS)

Brown, Kenneth; Brown, Julian; Patil, Mayuresh; Devenport, William

2018-02-01

The Kevlar-wall anechoic wind tunnel offers great value to the aeroacoustics research community, affording the capability to make simultaneous aeroacoustic and aerodynamic measurements. While the aeroacoustic potential of the Kevlar-wall test section is already being leveraged, the aerodynamic capability of these test sections is still to be fully realized. The flexibility of the Kevlar walls suggests the possibility that the internal test section flow may be characterized by precisely measuring small deflections of the flexible walls. Treating the Kevlar fabric walls as tensioned membranes with known pre-tension and material properties, an inverse stress problem arises where the pressure distribution over the wall is sought as a function of the measured wall deflection. Experimental wall deformations produced by the wind loading of an airfoil model are measured using digital image correlation and subsequently projected onto polynomial basis functions which have been formulated to mitigate the impact of measurement noise based on a finite-element study. Inserting analytic derivatives of the basis functions into the equilibrium relations for a membrane, full-field pressure distributions across the Kevlar walls are computed. These inversely calculated pressures, after being validated against an independent measurement technique, can then be integrated along the length of the test section to give the sectional lift of the airfoil. Notably, these first-time results are achieved with a non-contact technique and in an anechoic environment.

Transcript Profiling Identifies NAC-Domain Genes Involved in Regulating Wall Ingrowth Deposition in Phloem Parenchyma Transfer Cells of Arabidopsis thaliana

PubMed Central

Wu, Yuzhou; Hou, Jiexi; Yu, Fen; Nguyen, Suong T. T.; McCurdy, David W.

2018-01-01

Transfer cells (TCs) play important roles in facilitating enhanced rates of nutrient transport at key apoplasmic/symplasmic junctions along the nutrient acquisition and transport pathways in plants. TCs achieve this capacity by developing elaborate wall ingrowth networks which serve to increase plasma membrane surface area thus increasing the cell's surface area-to-volume ratio to achieve increased flux of nutrients across the plasma membrane. Phloem parenchyma (PP) cells of Arabidopsis leaf veins trans-differentiate to become PP TCs which likely function in a two-step phloem loading mechanism by facilitating unloading of photoassimilates into the apoplasm for subsequent energy-dependent uptake into the sieve element/companion cell (SE/CC) complex. We are using PP TCs in Arabidopsis as a genetic model to identify transcription factors involved in coordinating deposition of the wall ingrowth network. Confocal imaging of pseudo-Schiff propidium iodide-stained tissue revealed different profiles of temporal development of wall ingrowth deposition across maturing cotyledons and juvenile leaves, and a basipetal gradient of deposition across mature adult leaves. RNA-Seq analysis was undertaken to identify differentially expressed genes common to these three different profiles of wall ingrowth deposition. This analysis identified 68 transcription factors up-regulated two-fold or more in at least two of the three experimental comparisons, with six of these transcription factors belonging to Clade III of the NAC-domain family. Phenotypic analysis of these NAC genes using insertional mutants revealed significant reductions in levels of wall ingrowth deposition, particularly in a double mutant of NAC056 and NAC018, as well as compromised sucrose-dependent root growth, indicating impaired capacity for phloem loading. Collectively, these results support the proposition that Clade III members of the NAC-domain family in Arabidopsis play important roles in regulating wall ingrowth deposition in PP TCs. PMID:29599795

Transcript Profiling Identifies NAC-Domain Genes Involved in Regulating Wall Ingrowth Deposition in Phloem Parenchyma Transfer Cells of Arabidopsis thaliana.

PubMed

Wu, Yuzhou; Hou, Jiexi; Yu, Fen; Nguyen, Suong T T; McCurdy, David W

2018-01-01

Transfer cells (TCs) play important roles in facilitating enhanced rates of nutrient transport at key apoplasmic/symplasmic junctions along the nutrient acquisition and transport pathways in plants. TCs achieve this capacity by developing elaborate wall ingrowth networks which serve to increase plasma membrane surface area thus increasing the cell's surface area-to-volume ratio to achieve increased flux of nutrients across the plasma membrane. Phloem parenchyma (PP) cells of Arabidopsis leaf veins trans -differentiate to become PP TCs which likely function in a two-step phloem loading mechanism by facilitating unloading of photoassimilates into the apoplasm for subsequent energy-dependent uptake into the sieve element/companion cell (SE/CC) complex. We are using PP TCs in Arabidopsis as a genetic model to identify transcription factors involved in coordinating deposition of the wall ingrowth network. Confocal imaging of pseudo-Schiff propidium iodide-stained tissue revealed different profiles of temporal development of wall ingrowth deposition across maturing cotyledons and juvenile leaves, and a basipetal gradient of deposition across mature adult leaves. RNA-Seq analysis was undertaken to identify differentially expressed genes common to these three different profiles of wall ingrowth deposition. This analysis identified 68 transcription factors up-regulated two-fold or more in at least two of the three experimental comparisons, with six of these transcription factors belonging to Clade III of the NAC-domain family. Phenotypic analysis of these NAC genes using insertional mutants revealed significant reductions in levels of wall ingrowth deposition, particularly in a double mutant of NAC056 and NAC018 , as well as compromised sucrose-dependent root growth, indicating impaired capacity for phloem loading. Collectively, these results support the proposition that Clade III members of the NAC-domain family in Arabidopsis play important roles in regulating wall ingrowth deposition in PP TCs.

Buckling analysis of carbon nanotube bundles under axial compressive, bending and torsional loadings via a structural mechanics model

NASA Astrophysics Data System (ADS)

Lashkari Zadeh, Ali; Shariati, Mahmoud; Torabi, Hamid

2012-11-01

A structural mechanics model is employed for the investigation of the buckling behavior of carbon nanotube bundles of three single-walled carbon nanotubes (SWCNTs) under axial compressive, bending and torsional loadings. The effects of van der Waals (vdW) forces are further modeled using a nonlinear spring element.The effects of different types of boundary conditions are studied for nanotubes with various aspect ratios. The results reveal that bundles comprising longer SWCNTs exhibit lower critical buckling load. Moreover, for the fixed-free boundary condition the rate of critical buckling load reduction is highest, while the lowest critical buckling load occurs. Simulations show good agreement between our model and molecular dynamics results.

Predicting multi-wall structural response to hypervelocity impact using the hull code

NASA Technical Reports Server (NTRS)

Schonberg, William P.

1993-01-01

Previously, multi-wall structures have been analyzed extensively, primarily through experiment, as a means of increasing the meteoroid/space debris impact protection of spacecraft. As structural configurations become more varied, the number of tests required to characterize their response increases dramatically. As an alternative to experimental testing, numerical modeling of high-speed impact phenomena is often being used to predict the response of a variety of structural systems under different impact loading conditions. The results of comparing experimental tests to Hull Hydrodynamic Computer Code predictions are reported. Also, the results of a numerical parametric study of multi-wall structural response to hypervelocity cylindrical projectile impact are presented.

Performance Theory of Diagonal Conducting Wall MHD Accelerators

NASA Technical Reports Server (NTRS)

Litchford, R. J.

2003-01-01

The theoretical performance of diagonal conducting wall crossed field accelerators is examined on the basis of an infinite segmentation assumption using a cross-plane averaged generalized Ohm's law for a partially ionized gas, including ion slip. The desired accelerator performance relationships are derived from the cross-plane averaged Ohm's law by imposing appropriate configuration and loading constraints. A current dependent effective voltage drop model is also incorporated to account for cold-wall boundary layer effects including gasdynamic variations, discharge constriction, and electrode falls. Definition of dimensionless electric fields and current densities lead to the construction of graphical performance diagrams, which further illuminate the rudimentary behavior of crossed field accelerator operation.

One-dimensional analysis of filamentary composite beam columns with thin-walled open sections

NASA Technical Reports Server (NTRS)

Lo, Patrick K.-L.; Johnson, Eric R.

1986-01-01

Vlasov's one-dimensional structural theory for thin-walled open section bars was originally developed and used for metallic elements. The theory was recently extended to laminated bars fabricated from advanced composite materials. The purpose of this research is to provide a study and assessment of the extended theory. The focus is on flexural and torsional-flexural buckling of thin-walled, open section, laminated composite columns. Buckling loads are computed from the theory using a linear bifurcation analysis and a geometrically nonlinear beam column analysis by the finite element method. Results from the analyses are compared to available test data.

A New Model for Optimal Mechanical and Thermal Performance of Cement-Based Partition Wall

PubMed Central

Huang, Shiping; Hu, Mengyu; Cui, Nannan; Wang, Weifeng

2018-01-01

The prefabricated cement-based partition wall has been widely used in assembled buildings because of its high manufacturing efficiency, high-quality surface, and simple and convenient construction process. In this paper, a general porous partition wall that is made from cement-based materials was proposed to meet the optimal mechanical and thermal performance during transportation, construction and its service life. The porosity of the proposed partition wall is formed by elliptic-cylinder-type cavities. The finite element method was used to investigate the mechanical and thermal behaviour, which shows that the proposed model has distinct advantages over the current partition wall that is used in the building industry. It is found that, by controlling the eccentricity of the elliptic-cylinder cavities, the proposed wall stiffness can be adjusted to respond to the imposed loads and to improve the thermal performance, which can be used for the optimum design. Finally, design guidance is provided to obtain the optimal mechanical and thermal performance. The proposed model could be used as a promising candidate for partition wall in the building industry. PMID:29673176

Debonding Stress Concentrations in a Pressurized Lobed Sandwich-Walled Generic Cryogenic Tank

NASA Technical Reports Server (NTRS)

Ko, William L.

2004-01-01

A finite-element stress analysis has been conducted on a lobed composite sandwich tank subjected to internal pressure and cryogenic cooling. The lobed geometry consists of two obtuse circular walls joined together with a common flat wall. Under internal pressure and cryogenic cooling, this type of lobed tank wall will experience open-mode (a process in which the honeycomb is stretched in the depth direction) and shear stress concentrations at the junctures where curved wall changes into flat wall (known as a curve-flat juncture). Open-mode and shear stress concentrations occur in the honeycomb core at the curve-flat junctures and could cause debonding failure. The levels of contributions from internal pressure and temperature loading to the open-mode and shear debonding failure are compared. The lobed fuel tank with honeycomb sandwich walls has been found to be a structurally unsound geometry because of very low debonding failure strengths. The debonding failure problem could be eliminated if the honeycomb core at the curve-flat juncture is replaced with a solid core.

Seismic Response Of Masonry Plane Walls: A Numerical Study On Spandrel Strength

DOE Office of Scientific and Technical Information (OSTI.GOV)

Betti, Michele; Galano, Luciano; Vignoli, Andrea

2008-07-08

The paper reports the results of a numerical investigation on masonry walls subjected to in-plane seismic loads. This research aims to verify the formulae of shear and flexural strength of masonry spandrels which are given in the recent Italian Standards. Seismic pushover analyses have been carried out using finite element models of unreinforced walls and strengthened walls introducing reinforced concrete (RC) beams at the floor levels. Two typologies of walls have been considered distinguished for the height to length ratio h/l of the spandrels: a) short beams (h/l = 1.33) and b) slender beams (h/l = 0.5). Results obtained formore » the unreinforced and the strengthened walls are compared with equations for shear and flexural strength provided in Standards [1]. The numerical analyses show that the reliability of these equations is at least questionable especially for the prediction of the flexural strength. In the cases in which the axial force has not been determined by the structural analysis, Standards seems to overestimate the flexural strength of short spandrels both for the unreinforced and the strengthened wall.« less

Seismic Response Of Masonry Plane Walls: A Numerical Study On Spandrel Strength

NASA Astrophysics Data System (ADS)

Betti, Michele; Galano, Luciano; Vignoli, Andrea

2008-07-01

The paper reports the results of a numerical investigation on masonry walls subjected to in-plane seismic loads. This research aims to verify the formulae of shear and flexural strength of masonry spandrels which are given in the recent Italian Standards [1]. Seismic pushover analyses have been carried out using finite element models of unreinforced walls and strengthened walls introducing reinforced concrete (RC) beams at the floor levels. Two typologies of walls have been considered distinguished for the height to length ratio h/l of the spandrels: a) short beams (h/l = 1.33) and b) slender beams (h/l = 0.5). Results obtained for the unreinforced and the strengthened walls are compared with equations for shear and flexural strength provided in Standards [1]. The numerical analyses show that the reliability of these equations is at least questionable especially for the prediction of the flexural strength. In the cases in which the axial force has not been determined by the structural analysis, Standards [1] seems to overestimate the flexural strength of short spandrels both for the unreinforced and the strengthened wall.

A New Model for Optimal Mechanical and Thermal Performance of Cement-Based Partition Wall.

PubMed

Huang, Shiping; Hu, Mengyu; Huang, Yonghui; Cui, Nannan; Wang, Weifeng

2018-04-17

The prefabricated cement-based partition wall has been widely used in assembled buildings because of its high manufacturing efficiency, high-quality surface, and simple and convenient construction process. In this paper, a general porous partition wall that is made from cement-based materials was proposed to meet the optimal mechanical and thermal performance during transportation, construction and its service life. The porosity of the proposed partition wall is formed by elliptic-cylinder-type cavities. The finite element method was used to investigate the mechanical and thermal behaviour, which shows that the proposed model has distinct advantages over the current partition wall that is used in the building industry. It is found that, by controlling the eccentricity of the elliptic-cylinder cavities, the proposed wall stiffness can be adjusted to respond to the imposed loads and to improve the thermal performance, which can be used for the optimum design. Finally, design guidance is provided to obtain the optimal mechanical and thermal performance. The proposed model could be used as a promising candidate for partition wall in the building industry.

Physical state of poorly water soluble therapeutic molecules loaded into SBA-15 ordered mesoporous silica carriers: a case study with itraconazole and ibuprofen.

PubMed

Mellaerts, Randy; Jammaer, Jasper A G; Van Speybroeck, Michiel; Chen, Hong; Van Humbeeck, Jan; Augustijns, Patrick; Van den Mooter, Guy; Martens, Johan A

2008-08-19

The ordered mesoporous silica material SBA-15 was loaded with the model drugs itraconazole and ibuprofen using three different procedures: (i) adsorption from solution, (ii) incipient wetness impregnation, and (iii) heating of a mixture of drug and SBA-15 powder. The location of the drug molecules in the SBA-15 particles and molecular interactions were investigated using nitrogen adsorption, TGA, DSC, DRS UV-vis, and XPS. The in vitro release of hydrophobic model drugs was evaluated in an aqueous environment simulating gastric fluid. The effectiveness of the loading method was found to be strongly compound dependent. Incipient wetness impregnation using a concentrated itraconazole solution in dichloromethane followed by solvent evaporation was most efficient for dispersing itraconazole in SBA-15. The itraconazole molecules were located on the mesopore walls and inside micropores of the mesopore walls. When SBA-15 was loaded by slurrying it in a diluted itraconazole solution from which the solvent was evaporated, the itraconazole molecules ended up in the mesopores that they plugged locally. At a loading of 30 wt %, itraconazole exhibited intermolecular interactions inside the mesopores revealed by UV spectroscopy and endothermic events traced with DSC. The physical mixing of itraconazole and SBA-15 powder followed by heating above the itraconazole melting temperature resulted in formulations in which glassy itraconazole particles were deposited externally on the SBA-15 particles. Loading with ibuprofen was successful with each of the three loading procedures. Ibuprofen preferably is positioned inside the micropores. In vitro release experiments showed fast release kinetics provided the drug molecules were evenly deposited over the mesoporous surface.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Electrical, dielectric and surface wetting properties of multi-walled carbon nanotubes/nylon-6 nanocomposites

NASA Astrophysics Data System (ADS)

Long, Yun-Ze; Li, Meng-Meng; Sui, Wan-Mei; Kong, Qing-Shan; Zhang, Lei

2009-03-01

This paper reports that the multi-walled carbon nanotubes (MWCNT)/nylon-6 (PA6) nanocomposites with different MWCNT loadings have been prepared by a simple melt-compounding method. The electrical, dielectric, and surface wetting properties of the CNT/PA6 composites have been studied. The temperature dependence of the conductivity of the CNT/PA6 composite with 10.0 wt% CNT loading (σRT ~ 10-4 S/cm) are measured, and afterwards a charge-energy-limited tunnelling model (ln σ(T) ~ T-1/2) is found. With increasing CNT weight percentage from 0.0 to 10.0 wt%, the dielectric constant of the CNT/PA6 composites enhances and the dielectric loss tangent increases two orders of magnitude. In addition, water contact angles of the CNT/PA6 composites increase and the composites with CNT loading larger than 2.0 wt% even become hydrophobic. The obtained results indicate that the electrical and surface properties of the composites have been significantly enhanced by the embedded carbon nanotubes.

The three-dimensional simulation analysis of dynamic response on perforated strings

NASA Astrophysics Data System (ADS)

Li, M. F.; Liu, H. F.; Dou, Y. H.; Cao, L. H.; Liu, Y. X.

2018-06-01

It analyzes the dynamic response and stresses of perforating tubular string to detonating impact load in oil-gas well in ANSYS, obtains the response of vibration displacement, velocity and acceleration of perforating tubularstring caused by detonating impact load, finds the influence of the length and wall thickness of perforating tubular string to working stresses. The result shows that:when the detonating impact load exerts the perforating tubular string with compressive and tensile axial force alternatively;the vibration displacement, velocity and acceleration of perfora-ting tubular string change periodically at same cycle;the closer to the perforating gun, the larger the amplitude of vi-bration velocity and acceleration;the closer to the packer the smaller the vibration displacement, the larger the work-ing equivalent stress of perforating tubular string;the longer or the thicker the perforating tubular string, the smaller the working equivalent stress and the higher the strength safety. Therefore, it uses the damping tube between packer and perforating gun as well as thick walled tubing to increase the strength safety of perforating tubular string.

Reinforced Thermoplastic Polyimide with Dispersed Functionalized Single Wall Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Lebron-Colon, Marisabel; Meador, Michael A.; Gaier, James R.; Sola, Francisco; Scheiman, Daniel A.; McCorkle, Linda S.

2010-01-01

Molecular pi-complexes were formed from pristine HiPCO single-wall carbon nanotubes (SWCNTs) and 1-pyrene- N-(4- N'-(5-norbornene-2,3-dicarboxyimido)phenyl butanamide, 1. Polyimide films were prepared with these complexes as well as uncomplexed SWCNTs and the effects of nanoadditive addition on mechanical, thermal, and electrical properties of these films were evaluated. Although these properties were enhanced by both nanoadditives, larger increases in tensile strength and thermal and electrical conductivities were obtained when the SWCNT/1 complexes were used. At a loading level of 5.5 wt %, the Tg of the polyimide increased from 169 to 197 C and the storage modulus increased 20-fold (from 142 to 3045 MPa). The addition of 3.5 wt % SWCNT/1 complexes increased the tensile strength of the polyimide from 61.4 to 129 MPa; higher loading levels led to embrittlement and lower tensile strengths. The electrical conductivities (DC surface) of the polyimides increased to 1 x 10(exp -4) Scm(exp -1) (SWCNT/1 complexes loading level of 9 wt %). Details of the preparation of these complexes and their effects on polyimide film properties are discussed.

Design optimization of first wall and breeder unit module size for the Indian HCCB blanket module

NASA Astrophysics Data System (ADS)

Deepak, SHARMA; Paritosh, CHAUDHURI

2018-04-01

The Indian test blanket module (TBM) program in ITER is one of the major steps in the Indian fusion reactor program for carrying out the R&D activities in the critical areas like design of tritium breeding blankets relevant to future Indian fusion devices (ITER relevant and DEMO). The Indian Lead–Lithium Cooled Ceramic Breeder (LLCB) blanket concept is one of the Indian DEMO relevant TBM, to be tested in ITER as a part of the TBM program. Helium-Cooled Ceramic Breeder (HCCB) is an alternative blanket concept that consists of lithium titanate (Li2TiO3) as ceramic breeder (CB) material in the form of packed pebble beds and beryllium as the neutron multiplier. Specifically, attentions are given to the optimization of first wall coolant channel design and size of breeder unit module considering coolant pressure and thermal loads for the proposed Indian HCCB blanket based on ITER relevant TBM and loading conditions. These analyses will help proceeding further in designing blankets for loads relevant to the future fusion device.

Single-walled carbon nanotube-loaded doxorubicin and Gd-DTPA for targeted drug delivery and magnetic resonance imaging.

PubMed

Yan, Chenyu; Chen, Chengqun; Hou, Lin; Zhang, Huijuan; Che, Yingyu; Qi, Yuedong; Zhang, Xiaojian; Cheng, Jingliang; Zhang, Zhenzhong

2017-02-01

An aspargine-glycine-arginine (NGR) peptide modified single-walled carbon nanotubes (SWCNTs) system, developed by a simple non-covalent approach, could be loaded with the anticancer drug doxorubicin (DOX) and magnetic resonance imaging (MRI) contrast agent gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). This DOX- and Gd-DTPA-loaded NGR functionalized SWCNTs (DOX/NGR-SWCNTs/Gd-DPTA) retained both cytotoxicity of DOX and MRI contrast effect of Gd-DPTA. This drug delivery system showed excellent stability in physiological solutions. This DOX/NGR-SWCNTs/Gd-DPTA system could accumulate in tumors and enter into tumor cells, which facilitated combination chemotherapy with diagnosis of tumor in one system. An excellent in vitro anti-tumor effect was shown in MCF-7 cells treated by DOX/NGR-SWCNTs/Gd-DPTA, compared with DOX solution, DOX/SWCNTs and DOX/SWCNTs/Gd-DPTA. In vivo data of DOX/NGR-SWCNTs/Gd-DPTA group in tumor-bearing mice further confirmed that this system performed much higher tumor targeting capacity and anti-tumor efficacy than other control groups.

Response to “Comments on ‘A theoretical model of the pressure distributions arising from asymmetric intraglottal flows applied to a two-mass model of the vocal folds’” [J. Acoust. Soc. Am. 130, 389–403 (2011)

PubMed Central

Erath, Byron D.; Peterson, Sean D.; Zañartu, Matías; Wodicka, George R.; Stewart, Kelley C.; Plesniak, Michael W.

2013-01-01

Hirschberg [J. Acoust. Soc. Am. 134, 9-12 (2013)] presents a commentary and criticisms of the viscous flow model presented by Erath et al. [J. Acoust. Soc. Am. 130, 389–403 (2011)] that solves for the asymmetric pressure loading on the vocal fold walls. This pressure loading arises from asymmetric flow attachment to one vocal fold wall when the glottal channel forms a divergent configuration. Hirschberg proposes an alternative model for the asymmetric loading based upon inviscid flow curvature at the glottal inlet. In this manuscript further evidence is provided in support of the model of Erath et al. and the underlying assumptions, and demonstrates that the primary criticisms presented by Hirschberg are unwarranted. The model presented by Hirschberg is compared with the model from the original paper by Erath et al., and it is shown that each model describes different and complementary aspects of divergent glottal flows. PMID:23927090

Micro-emulsification/encapsulation of krill oil by complex coacervation with krill protein isolated using isoelectric solubilization/precipitation.

PubMed

Shi, Liu; Beamer, Sarah K; Yang, Hong; Jaczynski, Jacek

2018-04-01

This study determined feasibility of krill protein isolated with isoelectric solubilization/precipitation (ISP) as wall material to microencapsulate krill oil by freeze-drying. Effects of krill oil/krill protein ratio on properties of microcapsules were investigated. With increased ratio, crude protein of microcapsules decreased, while total lipid increased. Although microcapsule oil loading capacity increased, loading and encapsulation efficiencies decreased. Thin layer chromatography (TLC) confirmed abundance of phospholipids, which are amphiphilic; and thus, resulted in stable emulsion (emulsion stability index). Microcapsules contained ω-3 polyunsaturated fatty acids (PUFAs) at 43-60, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) at 28-41 and 9-11 g/100g of total FAs, respectively. SDS-PAGE electrophoresis revealed proteolysis of ISP krill protein, probably causing reduced loading and encapsulation efficiencies. SEM showed that krill oil/krill protein ratio affected surface microstructure. ISP krill protein showed potential as a wall material to microencapsulate krill oil; and thus, expand application of krill oil/protein for human consumption. Copyright © 2017 Elsevier Ltd. All rights reserved.

Racking strength of walls sheathed with structual flakeboards made from southern species

Treesearch

E.W. Price; Gromala D.S.

1980-01-01

Ten types of structural flakeboards and two types of southern pine plywood were evaluated. Racking loads were applied to full-size racking panels (8 by 8 ft., according to ASTME 72) and small panels (2 by 2 ft.). When subjected to a 1,600-pound racking load, 8- by 8-foot panels sheathed with flakeboards containing a mixture of hardwood and pine flakes were slightly...

Ability of finger-jointed lumber to maintain load at elevated temperatures

Treesearch

Douglas R. Rammer; Samuel L. Zelinka; Laura E Hasburgh; Steven T. Craft

2018-01-01

This article presents a test method that was developed to screen adhesive formulations for finger-jointed lumber. The goal was to develop a small-scale test that could be used to predict whether an adhesive would pass a full-scale ASTM E119 wall assembly test. The method involved loading a 38-mm square finger-jointed sample in a four-point bending test inside of an...

Racking strength of walls : let-in corner bracing, sheet materials, and effect of loading rate

Treesearch

Roger L. Tuomi; David S. Gromala

1977-01-01

Determination of the racking strength of wails, which is a measure of a building system’s ability to resist wind loads, has generally been limited to performance testing. Although a standard test method exists, deviations have often been made in speed of testing and panel configuration. The purpose of this study was to determine the relative effect of some of these...

In-pile testing of ITER first wall mock-ups at relevant thermal loading conditions

NASA Astrophysics Data System (ADS)

Litunovsky, N.; Gervash, A.; Lorenzetto, P.; Mazul, I.; Melder, R.

2009-04-01

The paper describes the experimental technique and preliminary results of thermal fatigue testing of ITER first wall (FW) water-cooled mock-ups inside the core of the RBT-6 experimental fission reactor (RIAR, Dimitrovgrad, Russia). This experiment has provided simultaneous effect of neutron fluence and thermal cycling damages on the mock-ups. A PC-controlled high-temperature graphite ohmic heater was applied to provide cyclic thermal load onto the mock-ups surface. This experiment lasted for 309 effective irradiation days with a final damage level (CuCrZr) of 1 dpa in the mock-ups. About 3700 thermal cycles with a heat flux of 0.4-0.5 MW/m 2 onto the mock-ups were realized before the heater fails. Then, irradiation was continued in a non-cycling mode.

Formation of metal clusters in halloysite clay nanotubes

NASA Astrophysics Data System (ADS)

Vinokurov, Vladimir A.; Stavitskaya, Anna V.; Chudakov, Yaroslav A.; Ivanov, Evgenii V.; Shrestha, Lok Kumar; Ariga, Katsuhiko; Darrat, Yusuf A.; Lvov, Yuri M.

2017-12-01

We developed ceramic core-shell materials based on abundant halloysite clay nanotubes with enhanced heavy metal ions loading through Schiff base binding. These clay tubes are formed by rolling alumosilicate sheets and have diameter of c.50 nm, a lumen of 15 nm and length 1 μm. This allowed for synthesis of metal nanoparticles at the selected position: (1) on the outer surface seeding 3-5 nm metal particles on the tubes; (2) inside the tube's central lumen resulting in 10-12 nm diameter metal cores shelled with ceramic wall; and (3) smaller metal nanoparticles intercalated in the tube's wall allowing up to 9 wt% of Ru, and Ag loading. These composite materials have high surface area providing a good support for catalytic nanoparticles, and can also be used for sorption of metal ions from aqueous solutions.

Formation of metal clusters in halloysite clay nanotubes.

PubMed

Vinokurov, Vladimir A; Stavitskaya, Anna V; Chudakov, Yaroslav A; Ivanov, Evgenii V; Shrestha, Lok Kumar; Ariga, Katsuhiko; Darrat, Yusuf A; Lvov, Yuri M

2017-01-01

We developed ceramic core-shell materials based on abundant halloysite clay nanotubes with enhanced heavy metal ions loading through Schiff base binding. These clay tubes are formed by rolling alumosilicate sheets and have diameter of c .50 nm, a lumen of 15 nm and length ~1 μm. This allowed for synthesis of metal nanoparticles at the selected position: (1) on the outer surface seeding 3-5 nm metal particles on the tubes; (2) inside the tube's central lumen resulting in 10-12 nm diameter metal cores shelled with ceramic wall; and (3) smaller metal nanoparticles intercalated in the tube's wall allowing up to 9 wt% of Ru, and Ag loading. These composite materials have high surface area providing a good support for catalytic nanoparticles, and can also be used for sorption of metal ions from aqueous solutions.

Numerical modelling of thin-walled Z-columns made of general laminates subjected to uniform shortening

NASA Astrophysics Data System (ADS)

Teter, Andrzej; Kolakowski, Zbigniew

2018-01-01

The numerical modelling of a plate structure was performed with the finite element method and a one-mode approach based on Koiter's method. The first order approximation of Koiter's method enables one to solve the eigenvalue problem. The second order approximation describes post-buckling equilibrium paths. In the finite element analysis, the Lanczos method was used to solve the linear problem of buckling. Simulations of the non-linear problem were performed with the Newton-Raphson method. Detailed calculations were carried out for a short Z-column made of general laminates. Configurations of laminated layers were non-symmetric. Due to possibilities of its application, the general laminate is very interesting. The length of the samples was chosen to obtain the lowest value of local buckling load. The amplitude of initial imperfections was 10% of the wall thickness. Thin-walled structures were simply supported on both ends. The numerical results were verified in experimental tests. A strain-gauge technique was applied. A static compression test was performed on a universal testing machine and a special grip, which consisted of two rigid steel plates and clamping sleeves, was used. Specimens were obtained with an autoclave technique. Tests were performed at a constant velocity of the cross-bar equal to 2 mm/min. The compressive load was less than 150% of the bifurcation load. Additionally, soft and thin pads were used to reduce inaccuracy of the sample ends.

ISSLS prize winner: microstructure and mechanical disruption of the lumbar disc annulus: part II: how the annulus fails under hydrostatic pressure.

PubMed

Veres, Samuel P; Robertson, Peter A; Broom, Neil D

2008-12-01

Mechanically induced annular disruption of lumbar intervertebral discs followed by microstructural investigation. To investigate the role that elevated nuclear pressures play in disrupting the lumbar intervertebral disc's annulus fibrosus. Compound mechanical loadings have been used to recreate clinically relevant annular disruptions in vitro. However, the role that individual loading parameters play in disrupting the lumbar disc's annulus remains unclear. The nuclei of ovine lumbar intervertebral discs were gradually pressurized by injecting a viscous radio-opaque gel via their inferior vertebrae. Pressurization was conducted until catastrophic failure of the disc occurred. Investigation of the resulting annular disruption was carried out using microcomputed tomography and differential interference contrast microscopy. Gel extrusion from the posterior annulus was the most common mode of disc failure. Unlike other aspects of the annular wall, the posterior region was unable to distribute hydrostatic pressures circumferentially. In each extrusion case, severe disruption of the posterior annulus occurred. Although intralamellar disruption occurred in the mid annulus, interlamellar disruption occurred in the outer posterior annulus. Radial ruptures between lamellae always occurred in the mid-axial plane. With respect to the annular wall, the posterior region is most susceptible to failure in the presence of high nuclear pressure, even when loaded in the neutral position. Weak interlamellar cohesion of the outer posterior lamellae may explain why the majority of herniations remain contained as protrusions within the outer annular wall.

Pipe support

DOEpatents

Pollono, Louis P.

1979-01-01

A pipe support for high temperature, thin-walled piping runs such as those used in nuclear systems. A section of the pipe to be supported is encircled by a tubular inner member comprised of two walls with an annular space therebetween. Compacted load-bearing thermal insulation is encapsulated within the annular space, and the inner member is clamped to the pipe by a constant clamping force split-ring clamp. The clamp may be connected to pipe hangers which provide desired support for the pipe.

Strength tests of thin-walled elliptic duralumin cylinders in pure bending and in combined pure bending and torsion

NASA Technical Reports Server (NTRS)

Lundquist, Eugene E; Stowell, Elbridge Z

1942-01-01

An analysis is presented of the results of tests made by the Massachusetts Institute of Technology and by the National Advisory Committee for Aeronautics on an investigation of the strength of thin-walled circular and elliptic cylinders in pure bending and in combined torsion and bending. In each of the loading conditions, the bending moments were applied in the plane of the major axis of the ellipse.

Department of the Navy. FY 1994/FY 1995 Biennial Budget Estimates. Military Construction Program. FY 1994

DTIC Science & Technology

1992-01-01

3 are severely deteriorated. The concrete deck and supporting wood -pile structure are nearing the end of their life cycle. Both piers are to be...PROPOSED CONSTRUCTION One-story building with concrete foundation walls, load bearing masonry walls, and concrete floors; roof with wood truss framing...concrete building addition; concrete foundation and slab on grade; wood truss roof; 750 KVA. 3 phase transformer; utilities; concrete and storm drain. 11

Size effect and cylinder test on several commercial explosives

NASA Astrophysics Data System (ADS)

Souers, P. Clark; Lauderbach, Lisa; Moua, Kou; Garza, Raul

2012-03-01

Some size (diameter) effect and the Cylinder test results for Kinepak (ammonium nitrate/nitromethane), Semtex 1, Semtex H and urea nitrate are presented. Cylinder test data appears normal despite faster sound speeds in the copper wall. Most explosives come to steady state in the Cylinder test as expected, but Kinepak shows a steadily increasing wall velocity with distance down the cylinder. Some data on powder densities as a function of loading procedure are also given.

Unsteady loads due to propulsive lift configurations. Part B: Pressure and velocity measurements in a three dimensional wall jet

NASA Technical Reports Server (NTRS)

Catalano, G. D.; Morton, J. B.; Humphris, R. R.

1978-01-01

The effects of increasing the velocity ratio, lambda sub j were explored. The quantities measured include the width of the mixing region, the mean velocity field, turbulent intensities and time scales. In addition, wall and static pressure velocity correlations and coherences are presented. The velocity measurements were made using a laser Doppler velocimeter with a phase locked loop processor. The fluctuating pressures were monitored using condenser type microphones.

30. VIEW OF ROOM 212 LOOKING SOUTHEAST TOWARDS EXIT DOORS. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

30. VIEW OF ROOM 212 LOOKING SOUTHEAST TOWARDS EXIT DOORS. EXPOSED MASONRY WALL WITH BRICK DETAILING OVER ARCHED DOORWAY IS UNPAINTED. ORIGINAL USE OF ROOM 212 WAS AS A HAYLOFT; EXTERIOR DOOR WAS USED FOR LOADING HAY. TRUSSWORK AND BEAMS ARE EXPOSED AND UNPAINTED. WALLS HAVE PAINTED WOOD PANELING, CEILING MATERIAL IS EXPOSED WOOD ROOF SHEATHING. - Presidio of San Francisco, Cavalry Stables, Cowles Street, between Lincoln Boulevard & McDowell Street, San Francisco, San Francisco County, CA

Cyclic Behavior of Low Rise Concrete Shear Walls Containing Recycled Coarse and Fine Aggregates.

PubMed

Qiao, Qiyun; Cao, Wanlin; Qian, Zhiwei; Li, Xiangyu; Zhang, Wenwen; Liu, Wenchao

2017-12-07

In this study, the cyclic behaviors of low rise concrete shear walls using recycled coarse or fine aggregates were investigated. Eight low rise Recycled Aggregates Concrete (RAC) shear wall specimens were designed and tested under a cyclic loading. The following parameters were varied: replacement percentages of recycled coarse or fine aggregates, reinforcement ratio, axial force ratio and X-shaped rebars brace. The failure characteristics, hysteretic behavior, strength and deformation capacity, strain characteristics and stiffness were studied. Test results showed that the using of the Recycled Coarse Aggregates (RCA) and its replacement ratio had almost no influence on the mechanical behavior of the shear wall; however, the using of Recycled Fine Aggregates (RFA) had a certain influence on the ductility of the shear wall. When the reinforcement ratio increased, the strength and ductility also increased. By increasing the axial force ratio, the strength increased but the ductility decreased significantly. The encased brace had a significant effect on enhancing the RAC shear walls. The experimental maximum strengths were evaluated with existing design codes, it was indicated that the strength evaluation of the low rise RAC shear walls can follow the existing design codes of the conventional concrete shear walls.

Spherical Cryogenic Hydrogen Tank Preliminary Design Trade Studies

NASA Technical Reports Server (NTRS)

Arnold, Steven M.; Bednarcyk, Brett A.; Collier, Craig S.; Yarrington, Phillip W.

2007-01-01

A structural analysis, sizing optimization, and weight prediction study was performed by Collier Research Corporation and NASA Glenn on a spherical cryogenic hydrogen tank. The tank consisted of an inner and outer wall separated by a vacuum for thermal insulation purposes. HyperSizer (Collier Research and Development Corporation), a commercial automated structural analysis and sizing software package was used to design the lightest feasible tank for a given overall size and thermomechanical loading environment. Weight trade studies were completed for different panel concepts and metallic and composite material systems. Extensive failure analyses were performed for each combination of dimensional variables, materials, and layups to establish the structural integrity of tank designs. Detailed stress and strain fields were computed from operational temperature changes and pressure loads. The inner tank wall is sized by the resulting biaxial tensile stresses which cause it to be strength driven, and leads to an optimum panel concept that need not be stiffened. Conversely, the outer tank wall is sized by a biaxial compressive stress field, induced by the pressure differential between atmospheric pressure and the vacuum between the tanks, thereby causing the design to be stability driven and thus stiffened to prevent buckling. Induced thermal stresses become a major sizing driver when a composite or hybrid composite/metallic material systems are used for the inner tank wall for purposes such as liners to contain the fuel and reduce hydrogen permeation.

Combined experimental and numerical evaluation of a prototype nano-PCM enhanced wallboard

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biswas, Kaushik; LuPh.D., Jue; Soroushian, Parviz

2014-01-01

In the United States, forty-eight (48) percent of the residential end-use energy consumption is spent on space heating and air conditioning. Reducing envelope-generated heating and cooling loads through application of phase change material (PCM)-enhanced building envelopes can facilitate maximizing the energy efficiency of buildings. Combined experimental testing and numerical modeling of PCM-enhanced envelope components are two important aspects of the evaluation of their energy benefits. An innovative phase change material (nano-PCM) was developed with PCM encapsulated with expanded graphite (interconnected) nanosheets, which is highly conductive for enhanced thermal storage and energy distribution, and is shape-stable for convenient incorporation into lightweightmore » building components. A wall with cellulose cavity insulation and prototype PCM-enhanced interior wallboards was built and tested in a natural exposure test (NET) facility in a hot-humid climate location. The test wall contained PCM wallboards and regular gypsum wallboard, for a side-by-side annual comparison study. Further, numerical modeling of the walls containing the nano-PCM wallboard was performed to determine its actual impact on wall-generated heating and cooling loads. The model was first validated using experimental data, and then used for annual simulations using Typical Meteorological Year (TMY3) weather data. This article presents the measured performance and numerical analysis evaluating the energy-saving potential of the nano-PCM-enhanced wallboard.« less

Nozzle Side Load Testing and Analysis at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Ruf, Joseph H.; McDaniels, David M.; Brown, Andrew M.

2009-01-01

Realistic estimates of nozzle side loads, the off-axis forces that develop during engine start and shutdown, are important in the design cycle of a rocket engine. The estimated magnitude of the nozzle side loads has a large impact on the design of the nozzle shell and the engine s thrust vector control system. In 2004 Marshall Space Flight Center (MSFC) began developing a capability to quantify the relative magnitude of side loads caused by different types of nozzle contours. The MSFC Nozzle Test Facility was modified to measure nozzle side loads during simulated nozzle start. Side load results from cold flow tests on two nozzle test articles, one with a truncated ideal contour and one with a parabolic contour are provided. The experimental approach, nozzle contour designs and wall static pressures are also discussed

The influence of an ITER-like wall on disruptions at JET

NASA Astrophysics Data System (ADS)

de Vries, Peter

2013-10-01

Disruptions are a key issue for tokamaks such as ITER because the fast release of the high thermal and magnetic energies will result in large forces and heat loads. Hence, finding methods to avoid them or mitigate their impact is vital. The recent replacement of carbon tiles with a metallic ITER-like wall (ILW) has greatly increased the significance of disruptions for JET operations. This paper summarizes how the metallic wall influenced the disruption physics itself and its influence on the causes of disruptions. Tolerable heat loads on the ILW are reduced compared to the carbon wall because of the potential for melting. This is exacerbated by the fact that with the ILW, significantly less energy is radiated during the disruption and thus more energy is conducted to the wall. The lower radiation and thus higher temperatures also slow down the current decay, yielding larger vessel forces. Mitigation by massive gas injection had to be applied routinely in order to safely operate JET with the new wall. The start of operations with the ILW showed a marked rise in the average disruption rate from 3.4% to 10%, although in the last 2 weeks, H-mode operations with only 3.3% disruptions was achieved. The increased disruption rate can be attributed to the influence of the new wall on plasma operation and control, requiring adjustments of the established carbon-wall scenarios. A detailed survey of disruption causes will be presented, showing the improvements made to avoid various disruption classes, but also indicating those disruption types responsible for the enhanced disruption rate. The latter can be mainly attributed to disruptions due to too high core radiation but also due to density control issues and error field locked modes. Detailed technical and physics understanding of disruption causes is essential for devising optimum strategies to avoid or mitigate these events. This research was funded partly by the European Communities under the contract of Association between EURATOM and FOM, and was carried out within the framework of EFDA. The views and opinions expressed herein do not necessarily reflect those of the Europe.

Acoustic emission testing of composite vessels under sustained loading

NASA Technical Reports Server (NTRS)

Lark, R. F.; Moorhead, P. E.

1978-01-01

Acoustic emission (AE) tests have been conducted on small-diameter Kevlar 49/epoxy pressure vessels subjected to long-term sustained load-to-failure tests. Single-cycle burst tests were used as a basis for determining the test pressure in the sustained-loading tests. AE data from two vessel locations were compared. The data suggest that AE from vessel wall-mounted transducers is quite different for identical vessels subjected to the same pressure loading. AE from boss-mounted transducers yielded relatively consistent values. These values were not a function of time for vessel failure. The development of an AE test procedure for predicting the residual service life or integrity of composite vessels is discussed.

Stiffening of short small-size circular composite steel–concrete columns with shear connectors

PubMed Central

Younes, Sherif M.; Ramadan, Hazem M.; Mourad, Sherif A.

2015-01-01

An experimental program was conducted to investigate the effect of shear connectors’ distribution and method of load application on load–displacement relationship and behavior of thin-walled short concrete-filled steel tube (CFT) columns when subjected to axial load. The study focused on the compressive strength of the CFT columns and the efficiency of the shear stud in distribution of the load between the concrete core and steel tube. The study showed that the use of shear connectors enhanced slightly the axial capacity of CFT columns. It is also shown that shear connectors have a great effect on load distribution between the concrete and steel tubes. PMID:27222757

Shuttle car loading system

NASA Technical Reports Server (NTRS)

Collins, E. R., Jr. (Inventor)

1985-01-01

A system is described for loading newly mined material such as coal, into a shuttle car, at a location near the mine face where there is only a limited height available for a loading system. The system includes a storage bin having several telescoping bin sections and a shuttle car having a bottom wall that can move under the bin. With the bin in an extended position and filled with coal the bin sections can be telescoped to allow the coal to drop out of the bin sections and into the shuttle car, to quickly load the car. The bin sections can then be extended, so they can be slowly filled with more while waiting another shuttle car.

Nanostructured thermoplastic polyimide films

DOEpatents

Aglan, Heshmat

2015-05-19

Structured films containing multi-walled carbon nanotubes ("MWCNTs") have enhanced mechanical performance in terms of strength, fracture resistance, and creep recovery of polyimide ("PI") films. Preferably, the loadings of MWCNTs can be in the range of 0.1 wt % to 0.5 wt %. The strength of the new PI films dried at 60.degree. C. increased by 55% and 72% for 0.1 wt % MWCNT and 0.5 wt % MWCNT loadings, respectively, while the fracture resistance increased by 23% for the 0.1 wt % MWCNTs and then decreases at a loading of 0.5 wt % MWCNTs. The films can be advantageously be created by managing a corresponding shift in the annealing temperature at which the maximum strength occurs as the MWCNT loadings increase.

Buckling of circular cylindrical shells under dynamically applied axial loads

NASA Technical Reports Server (NTRS)

Tulk, J. D.

1972-01-01

A theoretical and experimental study was made of the buckling characteristics of perfect and imperfect circular cylindrical shells subjected to dynamic axial loading. Experimental data included dynamic buckling loads (124 data points), high speed photographs of buckling mode shapes and observations of the dynamic stability of shells subjected to rapidly applied sub-critical loads. A mathematical model was developed to describe the dynamic behavior of perfect and imperfect shells. This model was based on the Donnell-Von Karman compatibility and equilibrium equations and had a wall deflection function incorporating five separate modes of deflection. Close agreement between theory and experiment was found for both dynamic buckling strength and buckling mode shapes.

Characterization of the Test Section Walls at the 14- by 22-Foot Subsonic Tunnel

NASA Technical Reports Server (NTRS)

Lunsford, Charles B.; Graves, Sharon S.

2003-01-01

The test section walls of the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel are known to move under thermal and pressure loads. Videogrammetry was used to measure wall motion during the summer of 2002. In addition, a laser distancemeter was used to measure the relative distance between the test section walls at a single point. Distancemeter and videogrammetry results were consistent. Data were analyzed as a function of temperature and pressure to determine their effects on wall motion. Data were collected between 50 and 100 F, 0 and 0.315 Mach, and dynamic pressures of 0 and 120 psf. The overall motion of each wall was found to be less than 0.25 in. and less than facility personnel anticipated. The results show how motion depends on the temperature and pressure inside the test section as well is the position of the boundary layer vane. The repeatability of the measurements was +/-0.06 in. This report describes the methods used to record the motion of the test section walls and the results of the data analysis. Future facility plans include the development of a suitable wall restraint system and the determination of the effects of the wall motion on tunnel calibration.

Effect of multi-layer thermal insulation thickness and location on the hypervelocity impact response of dual-wall structures

NASA Astrophysics Data System (ADS)

Schonberg, William P.

Traditional perforation-resistant wall design for long-duration spacecraft consists of a "bumper" that is placed a small distance away from the main "pressure wall" of a spacecraft compartment or module. This concept has been studied extensively as a means of reducing the perforation threat of hypervelocity projectiles such as meteoroids and orbital debris. If a dual-wall system is employed on an earth-orbiting spacecraft, then a blanket of multi-layer insulation (MLI) will typically be included within the dual-wall system for thermal protection purposes. This paper presents the results of an experimental study in which aluminum dual-wall structures were tested under a variety of high-speed impact conditions to study the effect of MLI thickness and location on perforation resistance. The results presented consist of test-by-test comparisons of the damage sustained by similar dual-wall systems with blanket MLI of various thicknesses and at various locations within the dual-wall systems under similar impact loading conditions. The analyses performed revealed that the placement of the MLI had a significant effect on the ballistic limit of the dual-wall structures considered while reducing the thickness of the MLI by as much as 1/3 did not.

Mechanical Properties of Plant Cell Walls Probed by Relaxation Spectra1[W][OA

PubMed Central

Hansen, Steen Laugesen; Ray, Peter Martin; Karlsson, Anders Ola; Jørgensen, Bodil; Borkhardt, Bernhard; Petersen, Bent Larsen; Ulvskov, Peter

2011-01-01

Transformants and mutants with altered cell wall composition are expected to display a biomechanical phenotype due to the structural role of the cell wall. It is often quite difficult, however, to distinguish the mechanical behavior of a mutant's or transformant's cell walls from that of the wild type. This may be due to the plant’s ability to compensate for the wall modification or because the biophysical method that is often employed, determination of simple elastic modulus and breakstrength, lacks the resolving power necessary for detecting subtle mechanical phenotypes. Here, we apply a method, determination of relaxation spectra, which probes, and can separate, the viscoelastic properties of different cell wall components (i.e. those properties that depend on the elastic behavior of load-bearing wall polymers combined with viscous interactions between them). A computer program, BayesRelax, that deduces relaxation spectra from appropriate rheological measurements is presented and made accessible through a Web interface. BayesRelax models the cell wall as a continuum of relaxing elements, and the ability of the method to resolve small differences in cell wall mechanical properties is demonstrated using tuber tissue from wild-type and transgenic potatoes (Solanum tuberosum) that differ in rhamnogalacturonan I side chain structure. PMID:21075961

Finite element tension analysis of the supporting tissues of a maxillary canine.

PubMed

Kalachev, Y S; Ralev, R D; Iordanov, P I

2001-01-01

The distribution of masticatory load on the teeth and the arising force tensions in them are factors that determine the origine of destructive processes in their periodontium. The development of mathematical models and application of new computer technologies make possible their precise study. They are still not thoroughly studied. To study the tensions, originating in the periodontium of a canine tooth during occlusal load by the modern method of finite elements (MFE). A three-dimensional model of a maxillary canine is built by MFE containing 304 finite elements with six varieties of geometrical form, linked in 1409 nodes. It is supposed that the tooth is fixed firmly to the outer surface of the periodontal membrane to the alveolar bone and is loaded in the lingual wall by a force perpendicular to its longitudinal axis and directed from the lingual to the vestibular wall. As a result of the calculations according to MFE the tension state of dental tissues is calculated for diferent degrees of destruction of the alveolar bone. It was established that with the increase of destruction of the alveolar bone for one and the same masticatory load, the tensions in the periodontal membrane also increase. The maximal tensions act in the apex of the root and around the clinical neck of the teeth. The results obtained provide precise information of distribution of force tensions in the periodontium of maxillary canines during occlusal load. They serve as a serious theoretical base for future investigations.

View of North End of Oxide Building Interior Including Roof ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of North End of Oxide Building Interior Including Roof and Wall Juncture and Crane Trolley - Hematite Fuel Fabrication Facility, Oxide Building & Oxide Loading Dock, 3300 State Road P, Festus, Jefferson County, MO

Development of sensitized pick coal interface detector system

NASA Technical Reports Server (NTRS)

Burchill, R. F.

1979-01-01

One approach for detection of the coal interface is measurement of the pick cutting hoads and shock through the use of pick strain gage load cells and accelerometers. The cutting drum of a long wall mining machine contains a number of cutting picks. In order to measure pick loads and shocks, one pick was instrumented and telementry used to transmit the signals from the drum to an instrument-type tape recorder. A data system using FM telemetry was designed to transfer cutting bit load and shock information from the drum of a longwall shearer coal mining machine to a chassis mounted data recorder.

Literature Review - Vegetation on Levees

DTIC Science & Technology

2010-12-01

seasonal high water and, which is therefore subject to water loading for periods of only a few days or weeks a year. As such, the function of levees...superimposed load on the relatively unstable embankment, in excess of the ability of the levee material to resist when saturated. As noted by Shields et...embankments from decayed roots or toppled trees; expansion of cracks or joints in concrete walls, canal lining, or pipes; and plugging of

Compression Strength of Composite Primary Structural Components

NASA Technical Reports Server (NTRS)

Johnson, Eric R.; Starnes, James H., Jr. (Technical Monitor)

2000-01-01

The focus of research activities under NASA Grant NAG-1-2035 was the response and failure of thin-walled structural components. The research is applicable to the primary load carrying structure of flight vehicles, with particular emphasis on fuselage and wing'structure. Analyses and tests were performed that are applicable to the following structural components an aft pressure bulkhead, or a composite pressure dome, pressure cabin damage containment, and fuselage frames subject to crash-type loads.

Blast Loading and Response of Underground Concrete-Arch Protective Structures

DTIC Science & Technology

1959-06-05

to approximate the load due to pasive earth pressure developed in the region of outward deflection of the arch. This Is assumed as a radial sinus...to represent a specimen from the wall matter , and preserve the gradation. Sufficient live reinforcement, the floor-slab reinforcement, and the storage...chemicals, or other foreign materials shall cleaned of latance, foreign matter , and loose parti- not be mixed with the concrete to prevent freezing. cles

Conventional Weapons Effects on Reinforced Soil Walls.

DTIC Science & Technology

1995-03-01

parametric study of the influence of specific design variables on wall panel response. D. METHODOLOGY A single degree of freedom model was modified to...t. dAev AVoF design methodologies for reinforced soil subjected o bl...at lad, LM, r..s.o.s. of these systems to such loading must be established...for many years and then on short notice be shipped to a location for use. The design for this shelter would be done as needed, although some non -site

4. OVERALL VIEW OF THE SOUTHEAST FACADE. THE BRICK MASONRY ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. OVERALL VIEW OF THE SOUTHEAST FACADE. THE BRICK MASONRY WALLS ARE LAID IN COMMON BOND WITH A BRICK DETAIL SURROUNDING THE FLAT ARCHED WOODEN DOORS. THE SYMMETRICAL PLACEMENT OF DOORS HAS BEEN VISUALLY AFFECTED BY THE ADDITION OF A WOOD FIRE STAIR. A BEAM USED TO LOAD HAY INTO THE UPPER LOFT AREA PROTRUDES THROUGH THE MASONRY WALL JUST BELOW THE ROOF LINE. - Presidio of San Francisco, Cavalry Stables, Cowles Street, between Lincoln Boulevard & McDowell Street, San Francisco, San Francisco County, CA

53. VIEW OF TIRRILL VOLTAGE REGULATOR LOCATED ON SOUTH WALL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

53. VIEW OF TIRRILL VOLTAGE REGULATOR LOCATED ON SOUTH WALL OF CONTROL ROOM. THE SOLENOID COILS AT THE TOP RIGHT OF THE PHOTOGRAPH DETECT VARIATIONS IN VOLTAGE AND CURRENT. THE ARMATURES OF THESE COILS ACT ON A SPRING LOADED BEAM. MOVEMENT OF THIS BEAM INDIRECTLY CONTROL SWITCHES WHICH CAUSE RESISTANCE GRIDS TO BE SWITCHED IN OR OUT OF THE EXCITER GENERATOR FIELD COILS (SEE CT-142A-95). - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

Vibro-acoustics for Space Station applications

NASA Technical Reports Server (NTRS)

Vaicaitis, R.; Bofilios, D. A.

1986-01-01

An analytical procedure has been developed to study noise generation in a double wall and single wall cylindrical shell due to mechanical point loads. The objective of this study is to develop theoretical procedures for parametetric evaluation of noise generation andd noise transmission for the habitability modules of the proposed Space Station operation. The solutions of the governing acoustic-structural equations are obtained utilizing modal decomposition. The numerical results include modal frequencies, deflection response spectral densities and interior noise sound pressure levels.

Applicability of tungsten/EUROFER blanket module for the DEMO first wall

NASA Astrophysics Data System (ADS)

Igitkhanov, Yu.; Bazylev, B.; Landman, I.; Boccaccini, L.

2013-07-01

In this paper we analyse a sandwich-type blanket configuration of W/EUROFER for DEMO first wall under steady-state normal operation and off-normal conditions, such as vertical displacements and runaway electrons. The heat deposition and consequent erosion of the tungsten armour is modelled under condition of helium cooling of the first wall blanket module and by taking into account the conversion of the magnetic energy stored in the runaway electron current into heat through the ohmic dissipation of the return current induced in the metallic armour structure. It is shown that under steady-state DEMO operation the first wall sandwich type module will tolerate heat loads up to ˜14 MW/m2. It will also sustain the off-normal events, apart from the hot vertical displacement events, which will melt the tungsten armour surface.

Bayesian decision and mixture models for AE monitoring of steel-concrete composite shear walls

NASA Astrophysics Data System (ADS)

Farhidzadeh, Alireza; Epackachi, Siamak; Salamone, Salvatore; Whittaker, Andrew S.

2015-11-01

This paper presents an approach based on an acoustic emission technique for the health monitoring of steel-concrete (SC) composite shear walls. SC composite walls consist of plain (unreinforced) concrete sandwiched between steel faceplates. Although the use of SC system construction has been studied extensively for nearly 20 years, little-to-no attention has been devoted to the development of structural health monitoring techniques for the inspection of damage of the concrete behind the steel plates. In this work an unsupervised pattern recognition algorithm based on probability theory is proposed to assess the soundness of the concrete infill, and eventually provide a diagnosis of the SC wall’s health. The approach is validated through an experimental study on a large-scale SC shear wall subjected to a displacement controlled reversed cyclic loading.

Fragmentation of wall rock garnets during deep crustal earthquakes

PubMed Central

Austrheim, Håkon; Dunkel, Kristina G.; Plümper, Oliver; Ildefonse, Benoit; Liu, Yang; Jamtveit, Bjørn

2017-01-01

Fractures and faults riddle the Earth’s crust on all scales, and the deformation associated with them is presumed to have had significant effects on its petrological and structural evolution. However, despite the abundance of directly observable earthquake activity, unequivocal evidence for seismic slip rates along ancient faults is rare and usually related to frictional melting and the formation of pseudotachylites. We report novel microstructures from garnet crystals in the immediate vicinity of seismic slip planes that transected lower crustal granulites during intermediate-depth earthquakes in the Bergen Arcs area, western Norway, some 420 million years ago. Seismic loading caused massive dislocation formations and fragmentation of wall rock garnets. Microfracturing and the injection of sulfide melts occurred during an early stage of loading. Subsequent dilation caused pervasive transport of fluids into the garnets along a network of microfractures, dislocations, and subgrain and grain boundaries, leading to the growth of abundant mineral inclusions inside the fragmented garnets. Recrystallization by grain boundary migration closed most of the pores and fractures generated by the seismic event. This wall rock alteration represents the initial stages of an earthquake-triggered metamorphic transformation process that ultimately led to reworking of the lower crust on a regional scale. PMID:28261660

Performance Theory of Diagonal Conducting Wall Magnetohydrodynamic Accelerators

NASA Technical Reports Server (NTRS)

Litchford, R. J.

2004-01-01

The theoretical performance of diagonal conducting wall crossed-field accelerators is examined on the basis of an infinite segmentation assumption using a cross-plane averaged generalized Ohm s law for a partially ionized gas, including ion slip. The desired accelerator performance relationships are derived from the cross-plane averaged Ohm s law by imposing appropriate configuration and loading constraints. A current-dependent effective voltage drop model is also incorporated to account for cold-wall boundary layer effects, including gasdynamic variations, discharge constriction, and electrode falls. Definition of dimensionless electric fields and current densities leads to the construction of graphical performance diagrams, which further illuminate the rudimentary behavior of crossed-field accelerator operation.

Numerical aspects and implementation of a two-layer zonal wall model for LES of compressible turbulent flows on unstructured meshes

NASA Astrophysics Data System (ADS)

Park, George Ilhwan; Moin, Parviz

2016-01-01

This paper focuses on numerical and practical aspects associated with a parallel implementation of a two-layer zonal wall model for large-eddy simulation (LES) of compressible wall-bounded turbulent flows on unstructured meshes. A zonal wall model based on the solution of unsteady three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations on a separate near-wall grid is implemented in an unstructured, cell-centered finite-volume LES solver. The main challenge in its implementation is to couple two parallel, unstructured flow solvers for efficient boundary data communication and simultaneous time integrations. A coupling strategy with good load balancing and low processors underutilization is identified. Face mapping and interpolation procedures at the coupling interface are explained in detail. The method of manufactured solution is used for verifying the correct implementation of solver coupling, and parallel performance of the combined wall-modeled LES (WMLES) solver is investigated. The method has successfully been applied to several attached and separated flows, including a transitional flow over a flat plate and a separated flow over an airfoil at an angle of attack.

Thermal Insulating Concrete Wall Panel Design for Sustainable Built Environment

PubMed Central

Zhou, Ao; Wong, Kwun-Wah

2014-01-01

Air-conditioning system plays a significant role in providing users a thermally comfortable indoor environment, which is a necessity in modern buildings. In order to save the vast energy consumed by air-conditioning system, the building envelopes in envelope-load dominated buildings should be well designed such that the unwanted heat gain and loss with environment can be minimized. In this paper, a new design of concrete wall panel that enhances thermal insulation of buildings by adding a gypsum layer inside concrete is presented. Experiments have been conducted for monitoring the temperature variation in both proposed sandwich wall panel and conventional concrete wall panel under a heat radiation source. For further understanding the thermal effect of such sandwich wall panel design from building scale, two three-story building models adopting different wall panel designs are constructed for evaluating the temperature distribution of entire buildings using finite element method. Both the experimental and simulation results have shown that the gypsum layer improves the thermal insulation performance by retarding the heat transfer across the building envelopes. PMID:25177718

Thermal insulating concrete wall panel design for sustainable built environment.

PubMed

Zhou, Ao; Wong, Kwun-Wah; Lau, Denvid

2014-01-01

Air-conditioning system plays a significant role in providing users a thermally comfortable indoor environment, which is a necessity in modern buildings. In order to save the vast energy consumed by air-conditioning system, the building envelopes in envelope-load dominated buildings should be well designed such that the unwanted heat gain and loss with environment can be minimized. In this paper, a new design of concrete wall panel that enhances thermal insulation of buildings by adding a gypsum layer inside concrete is presented. Experiments have been conducted for monitoring the temperature variation in both proposed sandwich wall panel and conventional concrete wall panel under a heat radiation source. For further understanding the thermal effect of such sandwich wall panel design from building scale, two three-story building models adopting different wall panel designs are constructed for evaluating the temperature distribution of entire buildings using finite element method. Both the experimental and simulation results have shown that the gypsum layer improves the thermal insulation performance by retarding the heat transfer across the building envelopes.

Performance assessment of MSE abutment walls in Indiana : final report.

DOT National Transportation Integrated Search

2017-05-01

This report presents a numerical investigation of the behavior of steel strip-reinforced mechanically stabilized earth (MSE) direct bridge abutments under static loading. Finite element simulations were performed using an advanced two-surface boundin...

Toroidal cell and battery. [storage battery for high amp-hour load applications

NASA Technical Reports Server (NTRS)

Nagle, W. J. (Inventor)

1981-01-01

A toroidal storage battery designed to handle relatively high amp-hour loads is described. The cell includes a wound core disposed within a pair of toroidal channel shaped electrodes spaced apart by nylon insulator. The shape of the case electrodes of this toroidal cell allows a first planar doughnut shaped surface and the inner cylindrical case wall to be used as a first electrode and a second planar doughnut shaped surface and the outer cylindrical case wall to be used as a second electrode. Connectors may be used to stack two or more toroidal cells together by connecting substantially the entire surface area of the first electrode of a first cell to substantially the entire surface area of the second electrode of a second cell. The central cavity of each toroidal cell may be used as a conduit for pumping a fluid through the toroidal cell to thereby cool the cell.

Formation of metal clusters in halloysite clay nanotubes

DOE PAGES

Vinokurov, Vladimir A.; Stavitskaya, Anna V.; Chudakov, Yaroslav A.; ...

2017-02-16

We developed ceramic core-shell materials based on abundant halloysite clay nanotubes with enhanced heavy metal ions loading through Schiff base binding. These clay tubes are formed by rolling alumosilicate sheets and have diameter of c.50 nm, a lumen of 15 nm and length ~1 μm. This allowed for synthesis of metal nanoparticles at the selected position: (1) on the outer surface seeding 3-5 nm metal particles on the tubes; (2) inside the tube’s central lumen resulting in 10-12 nm diameter metal cores shelled with ceramic wall; and (3) smaller metal nanoparticles intercalated in the tube’s wall allowing up to 9more » wt% of Ru, and Ag loading. These composite materials have high surface area providing a good support for catalytic nanoparticles, and can also be used for sorption of metal ions from aqueous solutions.« less

Split spline screw

NASA Technical Reports Server (NTRS)

Vranish, John M. (Inventor)

1993-01-01

A split spline screw type payload fastener assembly, including three identical male and female type split spline sections, is discussed. The male spline sections are formed on the head of a male type spline driver. Each of the split male type spline sections has an outwardly projecting load baring segment including a convex upper surface which is adapted to engage a complementary concave surface of a female spline receptor in the form of a hollow bolt head. Additionally, the male spline section also includes a horizontal spline releasing segment and a spline tightening segment below each load bearing segment. The spline tightening segment consists of a vertical web of constant thickness. The web has at least one flat vertical wall surface which is designed to contact a generally flat vertically extending wall surface tab of the bolt head. Mutual interlocking and unlocking of the male and female splines results upon clockwise and counter clockwise turning of the driver element.

Transparent and Self-Supporting Graphene Films with Wrinkled- Graphene-Wall-Assembled Opening Polyhedron Building Blocks for High Performance Flexible/Transparent Supercapacitors.

PubMed

Li, Na; Huang, Xuankai; Zhang, Haiyan; Li, Yunyong; Wang, Chengxin

2017-03-22

Improving mass loading while maintaining high transparency and large surface area in one self-supporting graphene film is still a challenge. Unfortunately, all of these factors are absolutely essential for enhancing the energy storage performance of transparent supercapacitors for practical applications. To solve the above bottleneck problem, we produce a novel self-supporting flexible and transparent graphene film (STF-GF) with wrinkled-wall-assembled opened-hollow polyhedron building units. Taking advantage of the microscopic morphology, the STF-GF exhibits improved mass loading with high transmittance (70.2% at 550 nm), a large surface area (1105.6 m 2 /g), and good electrochemical performance: high energy (552.3 μWh/cm 3 ), power densities (561.9 mW/cm 3 ), a superlong cycle life, and good cycling stability (the capacitance retention is ∼94.8% after 20,000 cycles).

Formation of metal clusters in halloysite clay nanotubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinokurov, Vladimir A.; Stavitskaya, Anna V.; Chudakov, Yaroslav A.

We developed ceramic core-shell materials based on abundant halloysite clay nanotubes with enhanced heavy metal ions loading through Schiff base binding. These clay tubes are formed by rolling alumosilicate sheets and have diameter of c.50 nm, a lumen of 15 nm and length ~1 μm. This allowed for synthesis of metal nanoparticles at the selected position: (1) on the outer surface seeding 3-5 nm metal particles on the tubes; (2) inside the tube’s central lumen resulting in 10-12 nm diameter metal cores shelled with ceramic wall; and (3) smaller metal nanoparticles intercalated in the tube’s wall allowing up to 9more » wt% of Ru, and Ag loading. These composite materials have high surface area providing a good support for catalytic nanoparticles, and can also be used for sorption of metal ions from aqueous solutions.« less

Homogenized rigid body and spring-mass (HRBSM) model for the pushover analysis of out-of-plane loaded unreinforced and FRP reinforced walls

NASA Astrophysics Data System (ADS)

Bertolesi, Elisa; Milani, Gabriele

2017-07-01

The present paper is devoted to the discussion of a series of unreinforced and FRP retrofitted panels analyzed adopting the Rigid Body and Spring-Mass (HRBSM) model developed by the authors. To this scope, a total of four out of plane loaded masonry walls tested up to failure are considered. At a structural level, the non-linear analyses are conducted replacing the homogenized orthotropic continuum with a rigid element and non-linear spring assemblage by means of which out of plane mechanisms are allowed. FRP retrofitting is modeled adopting two noded truss elements whose mechanical properties are selected in order to describe possible debonding phenomenon or tensile rupture of the strengthening. The outcome provided numerically are compared to the experimental results showing a satisfactory agreement in terms of global pressure-deflection curves and failure mechanisms.

Formation of metal clusters in halloysite clay nanotubes

PubMed Central

Vinokurov, Vladimir A.; Stavitskaya, Anna V.; Chudakov, Yaroslav A.; Ivanov, Evgenii V.; Shrestha, Lok Kumar; Ariga, Katsuhiko; Darrat, Yusuf A.; Lvov, Yuri M.

2017-01-01

Abstract We developed ceramic core-shell materials based on abundant halloysite clay nanotubes with enhanced heavy metal ions loading through Schiff base binding. These clay tubes are formed by rolling alumosilicate sheets and have diameter of c.50 nm, a lumen of 15 nm and length ~1 μm. This allowed for synthesis of metal nanoparticles at the selected position: (1) on the outer surface seeding 3–5 nm metal particles on the tubes; (2) inside the tube’s central lumen resulting in 10–12 nm diameter metal cores shelled with ceramic wall; and (3) smaller metal nanoparticles intercalated in the tube’s wall allowing up to 9 wt% of Ru, and Ag loading. These composite materials have high surface area providing a good support for catalytic nanoparticles, and can also be used for sorption of metal ions from aqueous solutions. PMID:28458738

Resonant coupling through a slot to a loaded cylindrical cavity: Experimental results

NASA Astrophysics Data System (ADS)

Norgard, John D.; Sega, Ronald M.

1990-03-01

The effect of cavity geometry on the energy coupled through a slot aperture is investigated through the use of planar mappings of the internal cavity field. A copper cylinder, closed at both ends, is constructed with copper mesh sections incorporated at the ends of the cylinder and in the cylinder wall opposite a thin slot aperture placed in the wall. The frequencies used for testing are 2 to 4 GHz. Internal field mapping is accomplished by placing thin carbon-loaded sheets in the plane of interest and recording the digitized temperature distribution using an infrared scanning system. The sheets are calibrated such that the temperature data is transformed to current densities or electric field strengths. Using several positions for the detection material, a three-dimensional field profile is obtained. The onset of the internal cavity resonance is studied as it is related to the energy coupled through small apertures.

Chitosan-folate decorated carbon nanotubes for site specific lung cancer delivery.

PubMed

Singh, Rahul Pratap; Sharma, Gunjan; Sonali; Singh, Sanjay; Bharti, Shreekant; Pandey, Bajarangprasad L; Koch, Biplob; Muthu, Madaswamy S

2017-08-01

The aim of this work was to formulate chitosan-folate conjugated multi-walled carbon nanotubes for the lung cancer targeted delivery of docetaxel. The chitosan-folate conjugate was synthesized and the conjugation was confirmed by Fourier transform infrared spectroscopy. The multi-walled carbon nanotubes were characterized for their particle size, polydispersity, zeta potential, surface morphology, drug encapsulation efficiency and in vitro release study. The in vitro cellular uptake, cytotoxicity, and cell cycle analysis of the docetaxel/coumarin-6 loaded multi-walled carbon nanotubes were carried out to compare the effectiveness of the formulations. The biocompatibility and safety of chitosan-folate conjugated multi-walled carbon nanotubes was analyzed by lung histopathology in comparison with marketed docetaxel formulation (Docel™) and acylated multi-walled carbon nanotubes. The cellular internalization study shown that the chitosan-folate conjugated multi-walled carbon nanotubes could be easily internalized into the lung cancer cells through a folate receptor-mediated endocytic pathway. The IC 50 values exhibited that chitosan-folate conjugated multi-walled carbon nanotubes could be 89-fold more effective than Docel™ in human lung cancer cells (A549 cells). Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental and numerical analysis of pre-compressed masonry walls in two-way-bending with second order effects

NASA Astrophysics Data System (ADS)

Milani, Gabriele; Olivito, Renato S.; Tralli, Antonio

2014-10-01

The buckling behavior of slender unreinforced masonry (URM) walls subjected to axial compression and out-of-plane lateral loads is investigated through a combined experimental and numerical homogenizedapproach. After a preliminary analysis performed on a unit cell meshed by means of elastic FEs and non-linear interfaces, macroscopic moment-curvature diagrams so obtained are implemented at a structural level, discretizing masonry by means of rigid triangular elements and non-linear interfaces. The non-linear incremental response of the structure is accounted for a specific quadratic programming routine. In parallel, a wide experimental campaign is conducted on walls in two way bending, with the double aim of both validating the numerical model and investigating the behavior of walls that may not be reduced to simple cantilevers or simply supported beams. Panels investigated are dry-joint in scale square walls simply supported at the base and on a vertical edge, exhibiting the classical Rondelet's mechanism. The results obtained are compared with those provided by the numerical model.

Effects of the magnetic field gradient on the wall power deposition of Hall thrusters

NASA Astrophysics Data System (ADS)

Ding, Yongjie; Li, Peng; Zhang, Xu; Wei, Liqiu; Sun, Hezhi; Peng, Wuji; Yu, Daren

2017-04-01

The effect of the magnetic field gradient in the discharge channel of a Hall thruster on the ionization of the neutral gas and power deposition on the wall is studied through adopting the 2D-3V particle-in-cell (PIC) and Monte Carlo collisions (MCC) model. The research shows that by gradually increasing the magnetic field gradient while keeping the maximum magnetic intensity at the channel exit and the anode position unchanged, the ionization region moves towards the channel exit and then a second ionization region appears near the anode region. Meanwhile, power deposition on the walls decreases initially and then increases. To avoid power deposition on the walls produced by electrons and ions which are ionized in the second ionization region, the anode position is moved towards the channel exit as the magnetic field gradient is increased; when the anode position remains at the zero magnetic field position, power deposition on the walls decreases, which can effectively reduce the temperature and thermal load of the discharge channel.

Building a Lego wall: Sequential action selection.

PubMed

Arnold, Amy; Wing, Alan M; Rotshtein, Pia

2017-05-01

The present study draws together two distinct lines of enquiry into the selection and control of sequential action: motor sequence production and action selection in everyday tasks. Participants were asked to build 2 different Lego walls. The walls were designed to have hierarchical structures with shared and dissociated colors and spatial components. Participants built 1 wall at a time, under low and high load cognitive states. Selection times for correctly completed trials were measured using 3-dimensional motion tracking. The paradigm enabled precise measurement of the timing of actions, while using real objects to create an end product. The experiment demonstrated that action selection was slowed at decision boundary points, relative to boundaries where no between-wall decision was required. Decision points also affected selection time prior to the actual selection window. Dual-task conditions increased selection errors. Errors mostly occurred at boundaries between chunks and especially when these required decisions. The data support hierarchical control of sequenced behavior. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Study on the CFD simulation of refrigerated container

NASA Astrophysics Data System (ADS)

Arif Budiyanto, Muhammad; Shinoda, Takeshi; Nasruddin

2017-10-01

The objective this study is to performed Computational Fluid Dynamic (CFD) simulation of refrigerated container in the container port. Refrigerated container is a thermal cargo container constructed from an insulation wall to carry kind of perishable goods. CFD simulation was carried out use cross sectional of container walls to predict surface temperatures of refrigerated container and to estimate its cooling load. The simulation model is based on the solution of the partial differential equations governing the fluid flow and heat transfer processes. The physical model of heat-transfer processes considered in this simulation are consist of solar radiation from the sun, heat conduction on the container walls, heat convection on the container surfaces and thermal radiation among the solid surfaces. The validation of simulation model was assessed uses surface temperatures at center points on each container walls obtained from the measurement experimentation in the previous study. The results shows the surface temperatures of simulation model has good agreement with the measurement data on all container walls.

Meteoroid-bumper interactions program

NASA Technical Reports Server (NTRS)

Gough, P. S.

1970-01-01

An investigation has been made of the interaction of meteoroids with shielded structures. The interaction has been simulated by the impact of Lexan cylinders onto lead shields in order to provide the vaporous debris believed to be created by meteoroid impact on a space vehicle. Shock compression data for Lexan was determined. This, in combination with the known shock compression data for the lead shield, has permitted the definition of the initial high pressure states in the impacted projectile and shield. The debris from such impact events has been permitted to interact with aluminum main walls. The walls were chosen to be sufficiently large to be effectively infinite in diameter compared to the loaded area. The thickness of the wall and the spacing from the shield were varied to determine the effect of these parameters. In addition, the effect of having a body of water behind the wall has been assessed. Measurements of the stagnation pressure in the debris cloud have been made and correlated with the response of the main wall.

Calcium deprivation disrupts enlargement of Chara corallina cells: further evidence for the calcium pectate cycle.

PubMed

Proseus, Timothy E; Boyer, John S

2012-06-01

Pectin is a normal constituent of cell walls of green plants. When supplied externally to live cells or walls isolated from the large-celled green alga Chara corallina, pectin removes calcium from load-bearing cross-links in the wall, loosening the structure and allowing it to deform more rapidly under the action of turgor pressure. New Ca(2+) enters the vacated positions in the wall and the externally supplied pectin binds to the wall, depositing new wall material that strengthens the wall. A calcium pectate cycle has been proposed for these sub-reactions. In the present work, the cycle was tested in C. corallina by depriving the wall of external Ca(2+) while allowing the cycle to run. The prediction is that growth would eventually be disrupted by a lack of adequate deposition of new wall. The test involved adding pectate or the calcium chelator EGTA to the Ca(2+)-containing culture medium to bind the calcium while the cycle ran in live cells. After growth accelerated, turgor and growth eventually decreased, followed by an abrupt turgor loss and growth cessation. The same experiment with isolated walls suggested the walls of live cells became unable to support the plasma membrane. If instead the pectate or EGTA was replaced with fresh Ca(2+)-containing culture medium during the initial acceleration in live cells, growth was not disrupted and returned to the original rates. The operation of the cycle was thus confirmed, providing further evidence that growth rates and wall biosynthesis are controlled by these sub-reactions in plant cell walls.

Sodium chloride promotes tissue inflammation via osmotic stimuli in subtotal-nephrectomized mice.

PubMed

Sakata, Fumiko; Ito, Yasuhiko; Mizuno, Masashi; Sawai, Akiho; Suzuki, Yasuhiro; Tomita, Takako; Tawada, Mitsuhiro; Tanaka, Akio; Hirayama, Akiyoshi; Sagara, Akihiro; Wada, Takashi; Maruyama, Shoichi; Soga, Tomoyoshi; Matsuo, Seiichi; Imai, Enyu; Takei, Yoshifumi

2017-04-01

Chronic inflammation, which is often associated with high all-cause and cardiovascular mortality, is prevalent in patients with renal failure; however, the precise mechanisms remain unclear. High-salt intake was reported to induce lymphangiogenesis and autoimmune diseases via osmotic stimuli with accumulation of sodium or chloride. In addition, sodium was recently reported to be stored in the extremities of dialysis patients. We studied the effects and mechanisms of high salt loading on tissue and systemic inflammation in subtotal-nephrectomized mice (5/6Nx) and in cultured cells. Macrophage infiltration in the peritoneal wall (P<0.001), heart (P<0.05) and para-aortic tissues (P<0.001) was significantly higher in 5/6Nx with salt loading (5/6Nx/NaCl) than in 5/6Nx without salt loading (5/6Nx/Water); however, there were no significant differences in blood pressure and renal function between the groups. Tissue interleukin-6, monocyte chemotactic protein-1 (MCP-1), serum- and glucocorticoid-inducible kinase 1 (Sgk1) and tonicity-responsive enhancer binding protein (TonEBP) mRNA were significantly elevated in the peritoneal wall and heart with 5/6Nx/NaCl when compared with 5/6Nx/Water. Sodium was stored in the abdominal wall, exerting high-osmotic conditions. Reversal of salt loading reduced macrophage infiltration associated with decreased TonEBP in 5/6Nx/NaCl. Macrophage infiltration associated with fibrosis induced by salt loading was decreased in the 5/6Nx/NaCl/CC chemokine receptor 2 (CCR2, receptor of MCP-1)-deficient mice when compared with 5/6Nx/NaCl/Wild mice, suggesting that CCR2 is required for macrophage infiltration in 5/6Nx with NaCl loading. In cultured mesothelial cells and cardiomyocytes, culture media with high NaCl concentration induced MCP-1, Sgk1 and TonEBP mRNA, all of which were suppressed by TonEBP siRNA, indicating that both MCP-1 and Sgk1 are downstream of TonEBP. Our study indicates that high NaCl intake induces MCP-1 expression leading to macrophage infiltration via the TonEBP-MCP-1 pathway in 5/6Nx/NaCl mice, and that TonEBP has a central role in inflammation in patients with renal failure taking high salt.

Retrofit of hollow concrete masonry infilled steel frames using glass fiber reinforced plastic laminates

NASA Astrophysics Data System (ADS)

Hakam, Zeyad Hamed-Ramzy

2000-11-01

This study focuses on the retrofit of hollow concrete masonry infilled steel frames subjected to in-plane lateral loads using glass fiber reinforced plastic (GFRP) laminates that are epoxy-bonded to the exterior faces of the infill walls. An extensive experimental investigation using one-third scale modeling was conducted and consisted of two phases. In the first phase, 64 assemblages, half of which were retrofitted, were tested under various combined in-plane loading conditions similar to those which different regions of a typical infill wall are subjected to. In the second phase, one bare and four masonry-infilled steel frames representative of a typical single-story, single-bay panel were tested under diagonal loading to study the overall behavior and the infill-frame interaction. The relative infill-to-frame stiffness was varied as a test parameter by using two different steel frame sections. The laminates altered the failure modes of the masonry assemblages and reduced the variability and anisotropic nature of the masonry. For the prisms which failed due to shear and/or mortar joint slip, significant strength increases were observed. For those exhibiting compression failure modes, a marginal increase in strength resulted. Retrofitting the infilled frames resulted in an average increase in initial stiffness of two-fold compared to the unretrofitted infilled frames, and seemed independent of the relative infill-to-frame stiffness. However, the increase in the load-carrying capacity of the retrofitted frames compared to the unretrofitted counterparts was higher for those with the larger relative infill-to-frame stiffness parameter. Unlike the unretrofitted infill walls, the retrofitted panels demonstrated almost identical failure modes that were characterized as "strictly comer crushing" in the vicinity of the loaded comers whereas no signs of distress were evident throughout the remainder of the infill. The laminates also maintained the structural integrity of the infill and prevented collapse and debris fallout even at severe loading stages. A finite element macromodel was proposed for the analysis of the GFRP-retrofitted masonry infilled frames. The infill panel was replaced with a nonlinear, compression-only, diagonal strut. This model was verified using the experimental results of the infilled frame testing and is characterized by its ease of application and accuracy.

Strongly coupled fluid-particle flows in vertical channels. I. Reynolds-averaged two-phase turbulence statistics

NASA Astrophysics Data System (ADS)

Capecelatro, Jesse; Desjardins, Olivier; Fox, Rodney O.

2016-03-01

Simulations of strongly coupled (i.e., high-mass-loading) fluid-particle flows in vertical channels are performed with the purpose of understanding the fundamental physics of wall-bounded multiphase turbulence. The exact Reynolds-averaged (RA) equations for high-mass-loading suspensions are presented, and the unclosed terms that are retained in the context of fully developed channel flow are evaluated in an Eulerian-Lagrangian (EL) framework for the first time. A key distinction between the RA formulation presented in the current work and previous derivations of multiphase turbulence models is the partitioning of the particle velocity fluctuations into spatially correlated and uncorrelated components, used to define the components of the particle-phase turbulent kinetic energy (TKE) and granular temperature, respectively. The adaptive spatial filtering technique developed in our previous work for homogeneous flows [J. Capecelatro, O. Desjardins, and R. O. Fox, "Numerical study of collisional particle dynamics in cluster-induced turbulence," J. Fluid Mech. 747, R2 (2014)] is shown to accurately partition the particle velocity fluctuations at all distances from the wall. Strong segregation in the components of granular energy is observed, with the largest values of particle-phase TKE associated with clusters falling near the channel wall, while maximum granular temperature is observed at the center of the channel. The anisotropy of the Reynolds stresses both near the wall and far away is found to be a crucial component for understanding the distribution of the particle-phase volume fraction. In Part II of this paper, results from the EL simulations are used to validate a multiphase Reynolds-stress turbulence model that correctly predicts the wall-normal distribution of the two-phase turbulence statistics.

Strongly coupled fluid-particle flows in vertical channels. I. Reynolds-averaged two-phase turbulence statistics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capecelatro, Jesse, E-mail: jcaps@illinois.edu; Desjardins, Olivier; Fox, Rodney O.

Simulations of strongly coupled (i.e., high-mass-loading) fluid-particle flows in vertical channels are performed with the purpose of understanding the fundamental physics of wall-bounded multiphase turbulence. The exact Reynolds-averaged (RA) equations for high-mass-loading suspensions are presented, and the unclosed terms that are retained in the context of fully developed channel flow are evaluated in an Eulerian–Lagrangian (EL) framework for the first time. A key distinction between the RA formulation presented in the current work and previous derivations of multiphase turbulence models is the partitioning of the particle velocity fluctuations into spatially correlated and uncorrelated components, used to define the components ofmore » the particle-phase turbulent kinetic energy (TKE) and granular temperature, respectively. The adaptive spatial filtering technique developed in our previous work for homogeneous flows [J. Capecelatro, O. Desjardins, and R. O. Fox, “Numerical study of collisional particle dynamics in cluster-induced turbulence,” J. Fluid Mech. 747, R2 (2014)] is shown to accurately partition the particle velocity fluctuations at all distances from the wall. Strong segregation in the components of granular energy is observed, with the largest values of particle-phase TKE associated with clusters falling near the channel wall, while maximum granular temperature is observed at the center of the channel. The anisotropy of the Reynolds stresses both near the wall and far away is found to be a crucial component for understanding the distribution of the particle-phase volume fraction. In Part II of this paper, results from the EL simulations are used to validate a multiphase Reynolds-stress turbulence model that correctly predicts the wall-normal distribution of the two-phase turbulence statistics.« less

Experimental study on the seismic performance of new sandwich masonry walls

NASA Astrophysics Data System (ADS)

Xiao, Jianzhuang; Pu, Jie; Hu, Yongzhong

2013-03-01

Sandwich masonry walls are widely used as energy-saving panels since the interlayer between the outer leaves can act as an insulation layer. New types of sandwich walls are continually being introduced in research and applications, and due to their unique bond patterns, experimental studies have been performed to investigate their mechanical properties, especially with regard to their seismic performance. In this study, three new types of sandwich masonry wall have been designed, and cyclic lateral loading tests were carried out on five specimens. The results showed that the specimens failed mainly due to slippage along the bottom cracks or the development of diagonal cracks, and the failure patterns were considerably influenced by the aspect ratio. Analysis was undertaken on the seismic response of the new walls, which included ductility, stiffness degradation and energy dissipation capacity, and no obvious difference was observed between the seismic performance of the new walls and traditional walls. Comparisons were made between the experimental results and the calculated results of the shear capacity. It is concluded that the formulas in the two Chinese codes (GB 50011 and GB 50003) are suitable for the calculation of the shear capacity for the new types of walls, and the formula in GB 50011 tends to be more conservative.

Effect of quasi-hydrostatical radial pressure on Ic of Nb3Sn wires

NASA Astrophysics Data System (ADS)

Mondonico, G.; Seeber, B.; Ferreira, A.; Bordini, B.; Oberli, L.; Bottura, L.; Ballarino, A.; Flükiger, R.; Senatore, C.

2012-11-01

High-performance Nb3Sn conductors are intended to be used in large-scale magnets like the International Thermonuclear Experimental Reactor (ITER) and in the upgrade of the Large Hadron Collider (LHC). Due to the occurrence of high electromagnetic forces, a detailed knowledge of the response of the critical current to the three-dimensional mechanical loads acting on the wires inside the cables is required. A detailed analysis of transverse stress effects on the critical current for powder-in-tube and bronze route Nb3Sn wires is presented. In an earlier publication, we have described the effect of transverse stress exerted on a Nb3Sn wire by means of two parallel plates. In the present paper, we analyse the effect of transverse stress exerted simultaneously by four walls on a wire being confined in a U-shaped groove. In order to get a more realistic picture of the situation of wires embedded in a Rutherford cable, the compression by four walls was also performed after impregnating the wire with epoxy in the same U-shaped groove. The result is very different from the case of pressing by means of two walls: the effect of pressure on Ic is now strongly reduced, which is attributed to the almost hydrostatic pressure in the U-shaped groove. This is further confirmed by the comparison between the effects of axial and transverse loads on the upper critical field and the pinning force. The present data are also compared against the effects of mechanical load on the critical current of cables in large-scale magnets.

Unsteady Thick Airfoil Aerodynamics: Experiments, Computation, and Theory

NASA Technical Reports Server (NTRS)

Strangfeld, C.; Rumsey, C. L.; Mueller-Vahl, H.; Greenblatt, D.; Nayeri, C. N.; Paschereit, C. O.

2015-01-01

An experimental, computational and theoretical investigation was carried out to study the aerodynamic loads acting on a relatively thick NACA 0018 airfoil when subjected to pitching and surging, individually and synchronously. Both pre-stall and post-stall angles of attack were considered. Experiments were carried out in a dedicated unsteady wind tunnel, with large surge amplitudes, and airfoil loads were estimated by means of unsteady surface mounted pressure measurements. Theoretical predictions were based on Theodorsen's and Isaacs' results as well as on the relatively recent generalizations of van der Wall. Both two- and three-dimensional computations were performed on structured grids employing unsteady Reynolds-averaged Navier-Stokes (URANS). For pure surging at pre-stall angles of attack, the correspondence between experiments and theory was satisfactory; this served as a validation of Isaacs theory. Discrepancies were traced to dynamic trailing-edge separation, even at low angles of attack. Excellent correspondence was found between experiments and theory for airfoil pitching as well as combined pitching and surging; the latter appears to be the first clear validation of van der Wall's theoretical results. Although qualitatively similar to experiment at low angles of attack, two-dimensional URANS computations yielded notable errors in the unsteady load effects of pitching, surging and their synchronous combination. The main reason is believed to be that the URANS equations do not resolve wake vorticity (explicitly modeled in the theory) or the resulting rolled-up un- steady flow structures because high values of eddy viscosity tend to \\smear" the wake. At post-stall angles, three-dimensional computations illustrated the importance of modeling the tunnel side walls.

The Effects of Nuclear Weapons

DTIC Science & Technology

1977-01-01

stage the chamber expanded to form ity and it will have crushed or fractured a spherical cavity 62 feet in radius, much of the rock in the region it...negligible if the flied. A recommended simplification -s to loading is sufficient to fracture the glass. treat the loading a. an impulse, the For asbestos...MULTISTORY, STEEL-FRAME and fracture of beams, failure of col- BU!LDINGS umns, crushing of exterior wall paneis, 5.25 There was apparently only one and

Biaxial and Shear Testing Apparatus with Force Controls

DTIC Science & Technology

2006-03-30

materials as the test specimen. (2) Description of the Prior Art [0004] It is known in the art that pressurized fabric tubes ; pressure-stabilized beams...apparatus is that these roller pins prevent any torsional load from reaching the test specimen. [0010] In Ward et al., (United States Patent No. 5,279,166...loading a specimen through pressurizing the inside surface of a cylinder is disclosed. A thin-wall tube specimen is biaxially tested for stress analysis

Effects of Carbon Nanomaterial Reinforcement on Composite Joints Under Cyclic and Impact Loading

DTIC Science & Technology

2012-03-01

prepreg . 2 Figure 1. Composite decks on DDG1000. (From [3]) Figure 2. USV built from nanotube-reinforced carbon fiber composites. (From [2...been proven that the infusion of CNTs enhances the strength and fracture toughness of CFRP laminates under static loading (mode I and mode II...Kostopoulos et al. [5] investigated the influence of the multi-walled carbon nanotubes (MWCNTs) on the impact and after-impact behavior of CFRP laminates

Blast and Penetration Resistant Tactical Shelters

DTIC Science & Technology

1979-07-01

2. Hardened Wall Material Properties 32 3. S-280 Shelter Panal Properties 33 4. Results Zor Dynamic Response of Complete S-280 Shelters 32 £-". In...insulation from a -6501 low to a 120 0F high plus a solar heating load 7. Corrosion resistance including salt fog 8. Blackout capability 9. Fungus...65 0 F), high temperature (120 0 F) plus a solar heating (BTU) load. g. Corrosion resistance (salt fog). 19 h. Blackout capability. i. Fungus

Plasma-wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

NASA Astrophysics Data System (ADS)

Brezinsek, S.; Coenen, J. W.; Schwarz-Selinger, T.; Schmid, K.; Kirschner, A.; Hakola, A.; Tabares, F. L.; van der Meiden, H. J.; Mayoral, M.-L.; Reinhart, M.; Tsitrone, E.; Ahlgren, T.; Aints, M.; Airila, M.; Almaviva, S.; Alves, E.; Angot, T.; Anita, V.; Arredondo Parra, R.; Aumayr, F.; Balden, M.; Bauer, J.; Ben Yaala, M.; Berger, B. M.; Bisson, R.; Björkas, C.; Bogdanovic Radovic, I.; Borodin, D.; Bucalossi, J.; Butikova, J.; Butoi, B.; Čadež, I.; Caniello, R.; Caneve, L.; Cartry, G.; Catarino, N.; Čekada, M.; Ciraolo, G.; Ciupinski, L.; Colao, F.; Corre, Y.; Costin, C.; Craciunescu, T.; Cremona, A.; De Angeli, M.; de Castro, A.; Dejarnac, R.; Dellasega, D.; Dinca, P.; Dittmar, T.; Dobrea, C.; Hansen, P.; Drenik, A.; Eich, T.; Elgeti, S.; Falie, D.; Fedorczak, N.; Ferro, Y.; Fornal, T.; Fortuna-Zalesna, E.; Gao, L.; Gasior, P.; Gherendi, M.; Ghezzi, F.; Gosar, Ž.; Greuner, H.; Grigore, E.; Grisolia, C.; Groth, M.; Gruca, M.; Grzonka, J.; Gunn, J. P.; Hassouni, K.; Heinola, K.; Höschen, T.; Huber, S.; Jacob, W.; Jepu, I.; Jiang, X.; Jogi, I.; Kaiser, A.; Karhunen, J.; Kelemen, M.; Köppen, M.; Koslowski, H. R.; Kreter, A.; Kubkowska, M.; Laan, M.; Laguardia, L.; Lahtinen, A.; Lasa, A.; Lazic, V.; Lemahieu, N.; Likonen, J.; Linke, J.; Litnovsky, A.; Linsmeier, Ch.; Loewenhoff, T.; Lungu, C.; Lungu, M.; Maddaluno, G.; Maier, H.; Makkonen, T.; Manhard, A.; Marandet, Y.; Markelj, S.; Marot, L.; Martin, C.; Martin-Rojo, A. B.; Martynova, Y.; Mateus, R.; Matveev, D.; Mayer, M.; Meisl, G.; Mellet, N.; Michau, A.; Miettunen, J.; Möller, S.; Morgan, T. W.; Mougenot, J.; Mozetič, M.; Nemanič, V.; Neu, R.; Nordlund, K.; Oberkofler, M.; Oyarzabal, E.; Panjan, M.; Pardanaud, C.; Paris, P.; Passoni, M.; Pegourie, B.; Pelicon, P.; Petersson, P.; Piip, K.; Pintsuk, G.; Pompilian, G. O.; Popa, G.; Porosnicu, C.; Primc, G.; Probst, M.; Räisänen, J.; Rasinski, M.; Ratynskaia, S.; Reiser, D.; Ricci, D.; Richou, M.; Riesch, J.; Riva, G.; Rosinski, M.; Roubin, P.; Rubel, M.; Ruset, C.; Safi, E.; Sergienko, G.; Siketic, Z.; Sima, A.; Spilker, B.; Stadlmayr, R.; Steudel, I.; Ström, P.; Tadic, T.; Tafalla, D.; Tale, I.; Terentyev, D.; Terra, A.; Tiron, V.; Tiseanu, I.; Tolias, P.; Tskhakaya, D.; Uccello, A.; Unterberg, B.; Uytdenhoven, I.; Vassallo, E.; Vavpetič, P.; Veis, P.; Velicu, I. L.; Vernimmen, J. W. M.; Voitkans, A.; von Toussaint, U.; Weckmann, A.; Wirtz, M.; Založnik, A.; Zaplotnik, R.; PFC contributors, WP

2017-11-01

The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, and by modelling codes that simulate edge-plasma conditions and the plasma-material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.

Plasma–wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

DOE PAGES

Brezinsek, S.; Coenen, J. W.; Schwarz-Selinger, T.; ...

2017-06-14

The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, andmore » by modelling codes that simulate edge-plasma conditions and the plasma–material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.« less

Plasma–wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brezinsek, S.; Coenen, J. W.; Schwarz-Selinger, T.

The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, andmore » by modelling codes that simulate edge-plasma conditions and the plasma–material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.« less

Evaluation of BSA protein release from hollow hydroxyapatite microspheres into PEG hydrogel

PubMed Central

Fu, Hailuo; Rahaman, Mohamed N.; Brown, Roger F.; Day, Delbert E.

2013-01-01

Implants that simultaneously function as an osteoconductive matrix and as a device for local drug or growth factor delivery could provide an attractive system for bone regeneration. In our previous work, we prepared hollow hydroxyapatite (abbreviated HA) microspheres with a high surface area, mesoporous shell wall and studied the release of a model protein, bovine serum albumin (BSA), from the microspheres into phosphate-buffered saline (PBS). The present work is an extension of our previous work to study the release of BSA from similar HA microspheres into a biocompatible hydrogel, poly(ethylene glycol) (PEG). BSA-loaded HA microspheres were placed in a PEG solution which was rapidly gelled using ultraviolet radiation. The BSA release rate into the PEG hydrogel, measured using a spectrophotometric method, was slower than into PBS, and it was dependent on the initial BSA loading and on the microstructure of the microsphere shell wall. A total of 35–40% of the BSA initially loaded into the microspheres was released into PEG over ~14 days. The results indicate that these hollow HA microspheres have promising potential as an osteoconductive device for local drug or growth factor delivery in bone regeneration and in the treatment of bone diseases. PMID:23498254

Glass Masonry - Experimental Verification of Bed Joint under Shear

NASA Astrophysics Data System (ADS)

Fíla, J.; Eliášová, M.; Sokol, Z.

2017-10-01

Glass is considered as a traditional material for building industry but was mostly used for glazing of the windows. At present, glass is an integral part of contemporary architecture where glass structural elements such as beams, stairs, railing ribs or columns became popular in the last two decades. However, using glass as structural material started at the beginning of 20th century, when masonry from hollow glass blocks were used. Using solid glass brick is very rare and only a few structures with solid glass bricks walls have been built in the last years. Pillars and walls made from solid glass bricks are mainly loaded by compression and/or bending from the eccentricity of vertical load or wind load. Due to high compressive strength of glass, the limiting factor of the glass masonry is the joint between the glass bricks as the smooth surface requires another type of mortar / glue compared to traditional masonry. Shear resistance and failure modes of brick bed joint was determined during series of tests using various mortars, two types of surface treatment and different thickness of the mortar joint. Shear tests were completed by small scale tests for mortar - determination of flexural and compressive strength of hardened mortar.

Advanced Structural and Inflatable Hybrid Spacecraft Module

NASA Technical Reports Server (NTRS)

Schneider, William C. (Inventor); delaFuente, Horacio M. (Inventor); Edeen, Gregg A. (Inventor); Kennedy, Kriss J. (Inventor); Lester, James D. (Inventor); Gupta, Shalini (Inventor); Hess, Linda F. (Inventor); Lin, Chin H. (Inventor); Malecki, Richard H. (Inventor); Raboin, Jasen L. (Inventor)

2001-01-01

An inflatable module comprising a structural core and an inflatable shell, wherein the inflatable shell is sealingly attached to the structural core. In its launch configuration, the wall thickness of the inflatable shell is collapsed by vacuum. Also in this configuration, the inflatable shell is collapsed and efficiently folded around the structural core. Upon deployment, the wall thickness of the inflatable shell is inflated; whereby the inflatable shell itself, is thereby inflated around the structural core, defining therein a large enclosed volume. A plurality of removable shelves are arranged interior to the structural core in the launch configuration. The structural core also includes at least one longeron that, in conjunction with the shelves, primarily constitute the rigid, strong, and lightweight load-bearing structure of the module during launch. The removable shelves are detachable from their arrangement in the launch configuration so that, when the module is in its deployed configuration and launch loads no longer exist, the shelves can be rearranged to provide a module interior arrangement suitable for human habitation and work. In the preferred embodiment, to provide efficiency in structural load paths and attachments, the shape of the inflatable shell is a cylinder with semi-toroidal ends.

A case study on the structural assessment of fire damaged building

NASA Astrophysics Data System (ADS)

Osman, M. H.; Sarbini, N. N.; Ibrahim, I. S.; Ma, C. K.; Ismail, M.; Mohd, M. F.

2017-11-01

This paper presents a case study on the structural assessment of building damaged by fire and discussed on the site investigations and test results prior to determine the existing condition of the building. The building was on fire for about one hour before it was extinguished. In order to ascertain the integrity of the building, a visual inspection was conducted for all elements (truss, beam, column and wall), followed by non-destructive, load and material tests. The load test was conducted to determine the ability of truss to resist service load, while the material test to determine the residual strength of the material. At the end of the investigation, a structural analysis was carried out to determine the new factor of safety by considering the residual strength. The highlighted was on the truss element due to steel behaviour that is hardly been predicted. Meanwhile, reinforced concrete elements (beam, column and wall) were found externally affected and caused its strength to be considered as sufficient for further used of building. The new factor of safety is equal to 2, considered as the minimum calculated value for the truss member. Therefore, this fire damaged building was found safe and can be used for further application.

Inflatable Vessel and Method

NASA Technical Reports Server (NTRS)

Raboin, Jasen L. (Inventor); Valle, Gerard D. (Inventor); Edeen, Gregg A. (Inventor); delaFuente, Horacio M. (Inventor); Schneider, William C. (Inventor); Spexarth, Gary R. (Inventor); Pandya, Shalini Gupta (Inventor); Johnson, Christopher J. (Inventor)

2003-01-01

An inflatable module comprising a structural core and an inflatable shell, wherein the inflatable shell is sealingly attached to the structural core. In its launch or pre-deployed configuration, the wall thickness of the inflatable shell is collapsed by vacuum. Also in this configuration, the inflatable shell is collapsed and efficiently folded around the structural core. Upon deployment, the wall thickness of the inflatable shell is inflated; whereby the inflatable shell itself, is thereby inflated around the structural core, defining therein a large enclosed volume. A plurality of removable shelves are arranged interior to the structural core in the launch configuration. The structural core also includes at least one longeron that, in conjunction with the shelves, primarily constitute the rigid, strong, and lightweight load-bearing structure of the module during launch. The removable shelves are detachable from their arrangement in the launch configuration so that, when the module is in its deployed configuration and launch loads no longer exist, the shelves can be rearranged to provide a module interior arrangement suitable for human habitation and work. In the preferred embodiment, to provide efficiency in structural load paths and attachments, the shape of the inflatable shell is a cylinder with semi-toroidal ends.

Physics Based Model for Cryogenic Chilldown and Loading. Part I: Algorithm

NASA Technical Reports Server (NTRS)

Luchinsky, Dmitry G.; Smelyanskiy, Vadim N.; Brown, Barbara

2014-01-01

We report the progress in the development of the physics based model for cryogenic chilldown and loading. The chilldown and loading is model as fully separated non-equilibrium two-phase flow of cryogenic fluid thermally coupled to the pipe walls. The solution follow closely nearly-implicit and semi-implicit algorithms developed for autonomous control of thermal-hydraulic systems developed by Idaho National Laboratory. A special attention is paid to the treatment of instabilities. The model is applied to the analysis of chilldown in rapid loading system developed at NASA-Kennedy Space Center. The nontrivial characteristic feature of the analyzed chilldown regime is its active control by dump valves. The numerical predictions are in reasonable agreement with the experimental time traces. The obtained results pave the way to the development of autonomous loading operation on the ground and space.

Altered Cell Wall Plasticity Can Restrict Plant Growth under Ammonium Nutrition.

PubMed

Podgórska, Anna; Burian, Maria; Gieczewska, Katarzyna; Ostaszewska-Bugajska, Monika; Zebrowski, Jacek; Solecka, Danuta; Szal, Bożena

2017-01-01

Plants mainly utilize inorganic forms of nitrogen (N), such as nitrate (NO 3 - ) and ammonium (NH 4 + ). However, the composition of the N source is important, because excess of NH 4 + promotes morphological disorders. Plants cultured on NH 4 + as the sole N source exhibit serious growth inhibition, commonly referred to as "ammonium toxicity syndrome." NH 4 + -mediated suppression of growth may be attributable to both repression of cell elongation and reduction of cell division. The precondition for cell enlargement is the expansion of the cell wall, which requires the loosening of the cell wall polymers. Therefore, to understand how NH 4 + nutrition may trigger growth retardation in plants, properties of their cell walls were analyzed. We found that Arabidopsis thaliana using NH 4 + as the sole N source has smaller cells with relatively thicker cell walls. Moreover, cellulose, which is the main load-bearing polysaccharide revealed a denser assembly of microfibrils. Consequently, the leaf blade tissue showed elevated tensile strength and indicated higher cell wall stiffness. These changes might be related to changes in polysaccharide and ion content of cell walls. Further, NH 4 + toxicity was associated with altered activities of cell wall modifying proteins. The lower activity and/or expression of pectin hydrolyzing enzymes and expansins might limit cell wall expansion. Additionally, the higher activity of cell wall peroxidases can lead to higher cross-linking of cell wall polymers. Overall, the NH 4 + -mediated inhibition of growth is related to a more rigid cell wall structure, which limits expansion of cells. The changes in cell wall composition were also indicated by decreased expression of Feronia , a receptor-like kinase involved in the control of cell wall extension.

Altered Cell Wall Plasticity Can Restrict Plant Growth under Ammonium Nutrition

PubMed Central

Podgórska, Anna; Burian, Maria; Gieczewska, Katarzyna; Ostaszewska-Bugajska, Monika; Zebrowski, Jacek; Solecka, Danuta; Szal, Bożena

2017-01-01

Plants mainly utilize inorganic forms of nitrogen (N), such as nitrate (NO3–) and ammonium (NH4+). However, the composition of the N source is important, because excess of NH4+ promotes morphological disorders. Plants cultured on NH4+ as the sole N source exhibit serious growth inhibition, commonly referred to as “ammonium toxicity syndrome.” NH4+-mediated suppression of growth may be attributable to both repression of cell elongation and reduction of cell division. The precondition for cell enlargement is the expansion of the cell wall, which requires the loosening of the cell wall polymers. Therefore, to understand how NH4+ nutrition may trigger growth retardation in plants, properties of their cell walls were analyzed. We found that Arabidopsis thaliana using NH4+ as the sole N source has smaller cells with relatively thicker cell walls. Moreover, cellulose, which is the main load-bearing polysaccharide revealed a denser assembly of microfibrils. Consequently, the leaf blade tissue showed elevated tensile strength and indicated higher cell wall stiffness. These changes might be related to changes in polysaccharide and ion content of cell walls. Further, NH4+ toxicity was associated with altered activities of cell wall modifying proteins. The lower activity and/or expression of pectin hydrolyzing enzymes and expansins might limit cell wall expansion. Additionally, the higher activity of cell wall peroxidases can lead to higher cross-linking of cell wall polymers. Overall, the NH4+-mediated inhibition of growth is related to a more rigid cell wall structure, which limits expansion of cells. The changes in cell wall composition were also indicated by decreased expression of Feronia, a receptor-like kinase involved in the control of cell wall extension. PMID:28848567

Sequential buckling of an elastic wall

NASA Astrophysics Data System (ADS)

Bico, Jose; Bense, Hadrien; Keiser, Ludovic; Roman, Benoit; Melo, Francisco; Abkarian, Manouk

A beam under quasistatic compression classically buckles beyond a critical threshold. In the case of a free beam, the lowest buckling mode is selected. We investigate the case of a long ``wall'' grounded of a compliant base and compressed in the axial compression. In the case of a wall of slender rectangular cross section, the selected buckling mode adopts a nearly fixed wavelength proportional to the height of the wall. Higher compressive loads only increase the amplitude of the buckle. However if the cross section has a sharp shape (such as an Eiffel tower profile), we observe successive buckling modes of increasing wavelength. We interpret this unusual evolution in terms of scaling arguments. At small scales, this variable periodicity might be used to develop tunable optical devices. We thank ECOS C12E07, CNRS-CONICYT, and Fondecyt Grant No. N1130922 for partially funding this work.

Dependence of equivalent thermal conductivity coefficients of single-wall carbon nanotubes on their chirality

NASA Astrophysics Data System (ADS)

Zarubin, V. S.; Sergeeva, E. S.

2018-04-01

Composite materials (composites) composed of a matrix and reinforcing components are currently widely used as structural materials for various engineering devices designed to operate under extreme thermal and mechanical loads. By modifying a composite with structure-sensitive inclusions such as single-wall carbon nanotubes, one can significantly improve the thermomechanical properties of the resulting material. The paper presents relationships obtained for the equivalent thermal conductivity coefficients of single-wall carbon nanotubes versus their chirality using a simulation model developed to simulate the heat transfer process through thermal conductivity in a transversely isotropic environment. With these coefficients, one can conventionally substitute a single-wall carbon nanotube with a continuous anisotropic fiber, thus allowing one to estimate the thermal properties of composites reinforced with objects of this sort by using the well-known models developed for fibered composites. The results presented here can be used to estimate the thermal properties of carbon nanotube-reinforced composites.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herk, Anastasia; Poerschke, Andrew

The New York State Energy Research and Development Authority (NYSERDA) is interested in finding cost-effective solutions for deep energy retrofits (DERs) related to exterior wall insulation in a cold climate, with targets of 50% peak load reduction and 50% space conditioning energy savings. The U.S. Department of Energy Building America team, IBACOS, in collaboration with GreenHomes America, Inc. (GHA), was contracted by NYSERDA to research exterior wall insulation solutions. In addition to exterior wall insulation, the strategies included energy upgrades where needed in the attic, mechanical and ventilation systems, basement, band joist, walls, and floors. Under Building America, IBACOS ismore » studying the impact of a “thermal enclosure” DER on the sizing of the space conditioning system and the occupant comfort if the thermal capacity of the heating and cooling system is dramatically downsized without any change in the existing heating and cooling distribution system (e.g., size, tightness and supply outlet configurations).« less

Bicuspid Axial Wall Height Effect on CAD/CAM Crown Fracture Mode on Preparations Containing Advanced Total Occlusal Convergence.

PubMed

Miller, Matthew; DuVall, Nicholas; Brewster, John; Wajdowicz, Michael N; Harris, Ashley; Roberts, Howard W

2018-02-18

To evaluate bicuspid axial wall height effect on the fracture mode of adhesively luted, all-ceramic CAD/CAM crowns with a 20° total occlusal convergence (TOC). Recently extracted premolars were randomly divided into 4 groups (n = 12) with all-ceramic crown preparations accomplished using a high-speed handpiece inserted into a milling device. Specimens were prepared containing occlusogingival axial wall heights of 3, 2, and 1 mm as well as a group containing a flat preparation surface with no axial wall height. All preparations contained a 20° TOC. Completed preparation surface area was determined, and preparation features confirmed using a digital measuring microscope. Scanned preparations (CEREC) were fitted with milled and crystallized lithium disilicate full coverage restorations and luted with a self-etching adhesive resin cement after hydrofluoric acid etching and silanation. All manufacturer recommendations were followed. Specimens were stored at 37°C/98% humidity for 24 hours. Specimens were tested to failure at a 45° angle to the long axis of the tooth root on a universal testing machine. Failure load was converted to MPa using the available bonding surface area with mean data analyzed using Kruskal-Wallis/Dunn's (p = 0.05) RESULTS: The 3 mm preparation height specimens were similar to the 2 mm specimens, and both demonstrated significantly stronger failure load than the 1 mm axial wall height and flat preparation specimens. The flat preparation and 1 mm axial wall height specimens all failed adhesively, while the 2 mm and 3 mm specimens failed largely due to tooth fracture. Further evidence is provided that CAD/CAM adhesive techniques may compensate for less than ideal preparation features. Under the conditions of this study, bicuspid preparations with a 20° TOC restored with adhesively luted, CAD/CAM e.max CAD crowns require at least 2 mm of axial wall height, but further planned fatigue studies are necessary before definitive recommendations can be made. © 2018 by the American College of Prosthodontists.

Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequencing Effects

NASA Technical Reports Server (NTRS)

Kalluri, Sreeramesh; Bonacuse, Peter J.

2000-01-01

Cumulative fatigue behavior of a wrought cobalt-base superalloy, Haynes 188 was investigated at 538 C under various single-step sequences of axial and torsional loading conditions. Initially, fully-reversed, axial and torsional fatigue tests were conducted under strain control at 538 C on thin-walled tubular specimens to establish baseline fatigue life relationships. Subsequently, four sequences (axial/axial, torsional/torsional, axial/torsional, and torsional/axial) of two load-level fatigue tests were conducted to characterize both the load-order (high/low) and load-type sequencing effects. For the two load-level tests, summations of life fractions and the remaining fatigue lives at the second load-level were computed by the Miner's Linear Damage Rule (LDR) and a nonlinear Damage Curve Approach (DCA). In general, for all four cases predictions by LDR were unconservative. Predictions by the DCA were within a factor of two of the experimentally observed fatigue lives for a majority of the cumulative axial and torsional fatigue tests.

Displacement coefficients along the inner boundaries of radially cracked ring segments subject to forces and couples

NASA Technical Reports Server (NTRS)

Gross, B.

1978-01-01

Displacement results of plane boundary collocation analysis are given for various locations on the inner boundaries of radially cracked ring segments (C-shaped specimens) subject to two complementary types of loading. Results are presented for ratios of outer to inner radius in the range of 1.1 to 2.5 and ratios a/W in the range 0.1 to 0.8, where a is the crack length for a specimen of wall thickness W. By combination of these results the resultant displacement coefficient or the corresponding influence coefficient can be obtained for any practical load line location of a pin-loaded specimen.

Compression strength of composite primary structural components

NASA Technical Reports Server (NTRS)

Johnson, Eric R.

1992-01-01

A status report of work performed during the period May 1, 1992 to October 31, 1992 is presented. Research was conducted in three areas: delamination initiation in postbuckled dropped-ply laminates; stiffener crippling initiated by delamination; and pressure pillowing of an orthogonally stiffened cylindrical shell. The geometrically nonlinear response and delamination initiation of compression-loaded dropped-ply laminates is analyzed. A computational model of the stiffener specimens that includes the capability to predict the interlaminar response at the flange free edge in postbuckling is developed. The distribution of the interacting loads between the stiffeners and the shell wall, particularly at the load transfer at the stiffener crossing point, is determined.

Effect of Transpiration Injection on Skin Friction in an Internal Supersonic Flow

NASA Technical Reports Server (NTRS)

Castiglone, L. A.; Northam, G. B.; Baker, N. R.; Roe, L. A.

1996-01-01

An experimental program was conducted at NASA Langley Research Center that included development and evaluation of an operational facility for wall drag measurement of potential scramjet fuel injection or wall cooling configurations. The facility consisted of a supersonic tunnel, with one wall composed of a series of interchangeable aluminum plates attached to an air bearing suspension system. The system was equipped with load cells that measured drag forces of 115 psia (793 kPa). This flow field contained a train of weak, unsteady, reflecting shock waves that were produced in the Mach 2 nozzle flows, the effect of reflecting shocks (which are to be expected in scramjet combustors) in internal flows has not previously been documented.

Investigation into the energy-absorbing properties of multilayered circular thin-walled tube

NASA Astrophysics Data System (ADS)

Qi, Aidong; Liu, Chuanhua; Hu, Gongli; Gu, Hongjun

2002-05-01

With the rise in collision accident and the increase in requirement for resistance of blastproof structures in recent years, people attach much importance to the research and application of energy-absorbing device. In this paper the author calculates the specific strength, the specific hardness and ultimate internal force of a circular thin-walled tube by theoretic calculations, discusses the feasibility of using circular thin-walled tube as an energy-absorbing element, analyzes the energy-absorbing properties and the energy-absorbing mechanism through the energy-absorbing experiments using various materials and forms of arrangement, reaches the conclusion that the load-bearing capacity and energy-absorbing properties of multilayered tubes are superior to that of single tube, and puts forward the concept of 'grading tube'.

Nonlinear analysis of composite thin-walled helicopter blades

NASA Astrophysics Data System (ADS)

Kalfon, J. P.; Rand, O.

Nonlinear theoretical modeling of laminated thin-walled composite helicopter rotor blades is presented. The derivation is based on nonlinear geometry with a detailed treatment of the body loads in the axial direction which are induced by the rotation. While the in-plane warping is neglected, a three-dimensional generic out-of-plane warping distribution is included. The formulation may also handle varying thicknesses and mass distribution along the cross-sectional walls. The problem is solved by successive iterations in which a system of equations is constructed and solved for each cross-section. In this method, the differential equations in the spanwise directions are formulated and solved using a finite-differences scheme which allows simple adaptation of the spanwise discretization mesh during iterations.

Drilled Shaft Foundations for Noise Barrier Walls and Slope Stabilization

DOT National Transportation Integrated Search

2002-12-01

This research project is focused on two primary objectives. The first objective relates to the development of a methodology for using the SPT (Standard Penetration Test) results to design the laterally loaded drilled shafts. The second objective aims...

Safer bridge railings, volume 1 summary report.

DOT National Transportation Integrated Search

1984-06-01

This study consisted of strength analyses of five in-service bridge railing systems, thirty full-scale vehicle crash tests on those railing systems and on a load measuring wall, the development of recommended design guidelines and deve1opment of reco...

Gravity: one of the driving forces for evolution.

PubMed

Volkmann, D; Baluska, F

2006-12-01

Mechanical load is 10(3) larger for land-living than for water-living organisms. As a consequence, antigravitational material in form of compound materials like lignified cell walls in plants and mineralised bones in animals occurs in land-living organisms preferentially. Besides cellulose, pectic substances of plant cell walls seem to function as antigravitational material in early phases of plant evolution and development. A testable hypothesis including vesicular recycling processes into the tensegrity concept is proposed for both sensing of gravitational force and responding by production of antigravitational material at the cellular level.

Nonlinear analysis of NPP safety against the aircraft attack

DOE Office of Scientific and Technical Information (OSTI.GOV)

Králik, Juraj, E-mail: juraj.kralik@stuba.sk; Králik, Juraj, E-mail: kralik@fa.stuba.sk

The paper presents the nonlinear probabilistic analysis of the reinforced concrete buildings of nuclear power plant under the aircraft attack. The dynamic load is defined in time on base of the airplane impact simulations considering the real stiffness, masses, direction and velocity of the flight. The dynamic response is calculated in the system ANSYS using the transient nonlinear analysis solution method. The damage of the concrete wall is evaluated in accordance with the standard NDRC considering the spalling, scabbing and perforation effects. The simple and detailed calculations of the wall damage are compared.

Impact of wall thickness and saccular geometry on the computational wall stress of descending thoracic aortic aneurysms.

PubMed

Shang, Eric K; Nathan, Derek P; Sprinkle, Shanna R; Fairman, Ronald M; Bavaria, Joseph E; Gorman, Robert C; Gorman, Joseph H; Jackson, Benjamin M

2013-09-10

Wall stress calculated using finite element analysis has been used to predict rupture risk of aortic aneurysms. Prior models often assume uniform aortic wall thickness and fusiform geometry. We examined the effects of including local wall thickness, intraluminal thrombus, calcifications, and saccular geometry on peak wall stress (PWS) in finite element analysis of descending thoracic aortic aneurysms. Computed tomographic angiography of descending thoracic aortic aneurysms (n=10 total, 5 fusiform and 5 saccular) underwent 3-dimensional reconstruction with custom algorithms. For each aneurysm, an initial model was constructed with uniform wall thickness. Experimental models explored the addition of variable wall thickness, calcifications, and intraluminal thrombus. Each model was loaded with 120 mm Hg pressure, and von Mises PWS was computed. The mean PWS of uniform wall thickness models was 410 ± 111 kPa. The imposition of variable wall thickness increased PWS (481 ± 126 kPa, P<0.001). Although the addition of calcifications was not statistically significant (506 ± 126 kPa, P=0.07), the addition of intraluminal thrombus to variable wall thickness (359 ± 86 kPa, P ≤ 0.001) reduced PWS. A final model incorporating all features also reduced PWS (368 ± 88 kPa, P<0.001). Saccular geometry did not increase diameter-normalized stress in the final model (77 ± 7 versus 67 ± 12 kPa/cm, P=0.22). Incorporation of local wall thickness can significantly increase PWS in finite element analysis models of thoracic aortic aneurysms. Incorporating variable wall thickness, intraluminal thrombus, and calcifications significantly impacts computed PWS of thoracic aneurysms; sophisticated models may, therefore, be more accurate in assessing rupture risk. Saccular aneurysms did not demonstrate a significantly higher normalized PWS than fusiform aneurysms.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brochard, J.; Charras, T.; Ghoudi, M.

Modifications to a computer code for ductile fracture assessment of piping systems with postulated circumferential through-wall cracks under static or dynamic loading are very briefly described. The modifications extend the capabilities of the CASTEM2000 code to the determination of fracture parameters under creep conditions. The main advantage of the approach is that thermal loads can be evaluated as secondary stresses. The code is applicable to piping systems for which crack propagation predictions differ significantly depending on whether thermal stresses are considered as primary or secondary stresses.

Intelligent Load Manager (LOADMAN): Application of Expert System Technology to Load Management Problems in Power Generation and Distribution Systems

DTIC Science & Technology

1988-08-10

addrsesed to it, the wall-receptacle module energizes a relay. Modules can be built to use a triac instead and have the capacity to increase or decrease... modulated by other constraints for a safe, functional ana effective power distribution system. 2.2.3 BackuR Equipment Alternate power sources are...environments have limited sensor capability and no remote control capability. However, future enhancements to current equipment, such as frequency- modulated

A fully coupled bolus-esophageal-gastric model for esophageal emptying based on the immersed boundary method

NASA Astrophysics Data System (ADS)

Kou, Wenjun; Pandolfino, John E.; Kahrilas, Peter J.; Patankar, Neelesh A.

2016-11-01

In this work, we develop a fully coupled bolus-esophageal-gastric model to study esophageal emptying based on the immersed boundary method. The model includes an esophageal segment, an ellipsoid-shaped stomach, and a bolus. It can easily handle the passive and active function of the lower esophageal sphincter (LES). Two groups of case studies are presented. The first group is about the influence from tissue anisotropy. Simulation shows that the weaker (or more compliant) part suffers from a higher wall shear stress and higher pressure load when the bolus is filled in and emptied from the LES segment. This implies a degradation cycle in which a weaker tissue becomes much weaker due to an increased load, a possible pathway to the esophageal lower diverticulum. The second group is about bulge formation resulting from asymmetric anatomy and a compliant LES. In particular, we find a right bulge tends to develop for a compliant LES. The bulge is most pronounced with a highest stiffness of the gastric wall. This implies that the competition between the LES stiffness and gastric wall stiffness might be another factor related to the esophageal lower diverticulum. The support of Grant R01 DK56033 and R01 DK079902 from NIH is gratefully acknowledged.

Three-Dimensional Flow Separation Induced by a Model Vocal Fold Polyp

NASA Astrophysics Data System (ADS)

Stewart, Kelley C.; Erath, Byron D.; Plesniak, Michael W.

2012-11-01

The fluid-structure energy exchange process for normal speech has been studied extensively, but it is not well understood for pathological conditions. Polyps and nodules, which are geometric abnormalities that form on the medial surface of the vocal folds, can disrupt vocal fold dynamics and thus can have devastating consequences on a patient's ability to communicate. A recent in-vitro investigation of a model polyp in a driven vocal fold apparatus demonstrated that such a geometric abnormality considerably disrupts the glottal jet behavior and that this flow field adjustment was a likely reason for the severe degradation of the vocal quality in patients. Understanding of the formation and propagation of vortical structures from a geometric protuberance, and their subsequent impact on the aerodynamic loadings that drive vocal fold dynamic, is a critical component in advancing the treatment of this pathological condition. The present investigation concerns the three-dimensional flow separation induced by a wall-mounted prolate hemispheroid with a 2:1 aspect ratio in cross flow, i.e. a model vocal fold polyp. Unsteady three-dimensional flow separation and its impact of the wall pressure loading are examined using skin friction line visualization and wall pressure measurements. Supported by the National Science Foundation, Grant No. CBET-1236351 and GW Center for Biomimetics and Bioinspired Engineering (COBRE).

Finite element based stability-constrained weight minimization of sandwich composite ducts for airship applications

NASA Astrophysics Data System (ADS)

Khode, Urmi B.

High Altitude Long Endurance (HALE) airships are platform of interest due to their persistent observation and persistent communication capabilities. A novel HALE airship design configuration incorporates a composite sandwich propulsive hull duct between the front and the back of the hull for significant drag reduction via blown wake effects. The sandwich composite shell duct is subjected to hull pressure on its outer walls and flow suction on its inner walls which result in in-plane wall compressive stress, which may cause duct buckling. An approach based upon finite element stability analysis combined with a ply layup and foam thickness determination weight minimization search algorithm is utilized. Its goal is to achieve an optimized solution for the configuration of the sandwich composite as a solution to a constrained minimum weight design problem, for which the shell duct remains stable with a prescribed margin of safety under prescribed loading. The stability analysis methodology is first verified by comparing published analytical results for a number of simple cylindrical shell configurations with FEM counterpart solutions obtained using the commercially available code ABAQUS. Results show that the approach is effective in identifying minimum weight composite duct configurations for a number of representative combinations of duct geometry, composite material and foam properties, and propulsive duct applied pressure loading.

Improving the fracture toughness and the strength of epoxy using nanomaterials--a review of the current status.

PubMed

Domun, N; Hadavinia, H; Zhang, T; Sainsbury, T; Liaghat, G H; Vahid, S

2015-06-21

The incorporation of nanomaterials in the polymer matrix is considered to be a highly effective technique to improve the mechanical properties of resins. In this paper the effects of the addition of different nanoparticles such as single-walled CNT (SWCNT), double-walled CNT (DWCNT), multi-walled CNT (MWCNT), graphene, nanoclay and nanosilica on fracture toughness, strength and stiffness of the epoxy matrix have been reviewed. The Young's modulus (E), ultimate tensile strength (UTS), mode I (GIC) and mode II (GIIC) fracture toughness of the various nanocomposites at different nanoparticle loadings are compared. The review shows that, depending on the type of nanoparticles, the integration of the nanoparticles has a substantial effect on mode I and mode II fracture toughness, strength and stiffness. The critical factors such as maintaining a homogeneous dispersion and good adhesion between the matrix and the nanoparticles are highlighted. The effect of surface functionalization, its relevancy and toughening mechanism are also scrutinized and discussed. A large variety of data comprised of the mechanical properties of nanomaterial toughened composites reported to date has thus been compiled to facilitate the evolution of this emerging field, and the results are presented in maps showing the effect of nanoparticle loading on mode I fracture toughness, stiffness and strength.

Three-Dimensional Finite Element Analysis of the Stress Distribution at the Internal Implant-Abutment Connection.

PubMed

Cho, Sung-Yong; Huh, Yoon-Hyuk; Park, Chan-Jin; Cho, Lee-Ra

2016-01-01

This study investigated stress distribution in four different implant-abutment interface conditions in the internal tapered connection implant system. Four different implant diameters (3.5 mm, 4.0 mm, 4.5 mm, and 5.0 mm) and two abutment types (hexagonal and conical) were simulated. Four unique implant-abutment interface conditions were assumed based on wall thickness, mating surface length, distance to the vertical stop, and abutment shape. Axial and oblique loading was applied during abutment screw preload, and the Von Mises stresses were measured at the implant-abutment and abutment-screw interfaces. The implant-abutment interface stress decreased as the wall thickness increased. As the mating surface increased, the stress distribution trended downward, and when the distance to the implant vertical stop was 0 μm, the Von Mises stress was extremely high at the vertical stop. Despite their different shapes, the abutments showed similar stress distributions. However, the maximum Von Mises stress was higher in the conical connection than in the hexagonal connection, particularly at the contralateral side to loading. To decrease the stress distribution at the implant-abutment interface, the implant wall thickness, mating surface contact length, distance to the vertical stop, and abutment shape should be carefully considered.

The effect of trench width on the behavior of buried rigid pipes

NASA Astrophysics Data System (ADS)

Balkaya, Müge; Saǧlamer, Ahmet

2014-12-01

In this study, in order to determine the effect of trench width (Bd) on the behavior of buried rigid pipes, a concrete pipe having an outside diameter of 150 cm and wall thickness (t) of 15 cm was analyzed using 2D PLAXIS finite element program. In the analyses, three different trench widths (Bd = 2.20 m, 3.40 m, and 4.40 m) were modeled. The results of the analyses indicated that, as the width of the trench increases, the axial force, shear force, bending moment, effective normal stress, and the earth load acting on the pipe increased. The variations of the loads acting on the pipe due to the increasing trench widths were also evaluated using the Marston load theory. When the loads calculated by the Marston Load Theory and the finite element analysis were compared with each other, it was seen that the Marston Load Theory resulted in slightly higher load values than the finite element analysis. On the other hand, for the two methods, the loads acting on the pipe increased with increasing trench width.

A discrete mesoscopic particle model of the mechanics of a multi-constituent arterial wall.

PubMed

Witthoft, Alexandra; Yazdani, Alireza; Peng, Zhangli; Bellini, Chiara; Humphrey, Jay D; Karniadakis, George Em

2016-01-01

Blood vessels have unique properties that allow them to function together within a complex, self-regulating network. The contractile capacity of the wall combined with complex mechanical properties of the extracellular matrix enables vessels to adapt to changes in haemodynamic loading. Homogenized phenomenological and multi-constituent, structurally motivated continuum models have successfully captured these mechanical properties, but truly describing intricate microstructural details of the arterial wall may require a discrete framework. Such an approach would facilitate modelling interactions between or the separation of layers of the wall and would offer the advantage of seamless integration with discrete models of complex blood flow. We present a discrete particle model of a multi-constituent, nonlinearly elastic, anisotropic arterial wall, which we develop using the dissipative particle dynamics method. Mimicking basic features of the microstructure of the arterial wall, the model comprises an elastin matrix having isotropic nonlinear elastic properties plus anisotropic fibre reinforcement that represents the stiffer collagen fibres of the wall. These collagen fibres are distributed evenly and are oriented in four directions, symmetric to the vessel axis. Experimental results from biaxial mechanical tests of an artery are used for model validation, and a delamination test is simulated to demonstrate the new capabilities of the model. © 2016 The Author(s).

A film-based wall shear stress sensor for wall-bounded turbulent flows

NASA Astrophysics Data System (ADS)

Amili, Omid; Soria, Julio

2011-07-01

In wall-bounded turbulent flows, determination of wall shear stress is an important task. The main objective of the present work is to develop a sensor which is capable of measuring surface shear stress over an extended region applicable to wall-bounded turbulent flows. This sensor, as a direct method for measuring wall shear stress, consists of mounting a thin flexible film on the solid surface. The sensor is made of a homogeneous, isotropic, and incompressible material. The geometry and mechanical properties of the film are measured, and particles with the nominal size of 11 μm in diameter are embedded on the film's surface to act as markers. An optical technique is used to measure the film deformation caused by the flow. The film has typically deflection of less than 2% of the material thickness under maximum loading. The sensor sensitivity can be adjusted by changing the thickness of the layer or the shear modulus of the film's material. The paper reports the sensor fabrication, static and dynamic calibration procedure, and its application to a fully developed turbulent channel flow at Reynolds numbers in the range of 90,000-130,000 based on the bulk velocity and channel full height. The results are compared to alternative wall shear stress measurement methods.

Bioinspired Layer-by-Layer Microcapsules Based on Cellulose Nanofibers with Switchable Permeability.

PubMed

Paulraj, Thomas; Riazanova, Anastasia V; Yao, Kun; Andersson, Richard L; Müllertz, Anette; Svagan, Anna J

2017-04-10

Green, all-polysaccharide based microcapsules with mechanically robust capsule walls and fast, stimuli-triggered, and switchable permeability behavior show great promise in applications based on selective and timed permeability. Taking a cue from nature, the build-up and composition of plant primary cell walls inspired the capsule wall assembly, because the primary cell walls in plants exhibit high mechanical properties despite being in a highly hydrated state, primarily owing to cellulose microfibrils. The microcapsules (16 ± 4 μm in diameter) were fabricated using the layer-by-layer technique on sacrificial CaCO 3 templates, using plant polysaccharides (pectin, cellulose nanofibers, and xyloglucan) only. In water, the capsule wall was permeable to labeled dextrans with a hydrodynamic diameter of ∼6.6 nm. Upon exposure to NaCl, the porosity of the capsule wall quickly changed allowing larger molecules (∼12 nm) to permeate. However, the porosity could be restored to its original state by removal of NaCl, by which permeants became trapped inside the capsule's core. The high integrity of cell wall was due to the CNF and the ON/OFF alteration of the permeability properties, and subsequent loading/unloading of molecules, could be repeated several times with the same capsule demonstrating a robust microcontainer with controllable permeability properties.

Nanocomposites of nitrile (NBR) rubber with multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Warasitthinon, Nuthathai

Nanotechnology offers the promise of creating new materials with enhanced performance. There are different kinds of fillers used in rubber nanocomposites, such as carbon black, silica, carbon fibers, and organoclays. Carbon nanotube reinforced elastomers have potential for improved rubber properties in aggressive environments. The first chapter is an introduction to the literature. The second chapter investigated the incorporation of multi-walled carbon nanotubes (MWCNTs) into rubber matrix for potential use in high temperature applications. The vulcanization kinetics of acrylonitrile butadiene rubber (NBR) reinforced with multi-walled carbon nanotubes was investigated. The vulcanized NBR rubber with different loading percentages of MWCNTs was also compared to NBR reinforced with carbon black N330. The optimum curing time at 170°C (T90) was found to decrease with increasing content of MWCNTs. Increased filler loading of both carbon black and MWCNTs gave higher modulus and strength. The MWCNTs filled materials gave better retention of modulus and tensile strength at high temperatures, but lower strength as compared to the carbon black filled samples. In the third chapter, carbon black (CB, 50phr) content in nitrile rubber (NBR) nanocomposites was partially replaced by multi-walled carbon nanotubes (MWCNTs). NBR/CB/CNTs nanocomposites with varying ratio of CB/CNTs (50/0 phr to 40/10 phr) were formulated via the melt-mixing method using an internal mixer. The reinforcing effect of single filler (CB) and mixture of fillers (CB and CNTs) on the properties of NBR nanocomposites was investigated. The cure kinetics and bound rubber content were analyzed using rheometry and solvent swelling method. In addition, mechanical behavior at both room temperature and high temperature (350°F/ 121°C) were examined. The scorch time and curing time values showed that there was no significant effect on the curing behavior of NBR nanocomposites after the partial replacement of CB with CNTs. It was observed that bound rubber content decreased with increase in CNT content for NBR/CB/CNTs nanocomposites above a loading of 1 phr CNT. In the fourth chapter, the effect of another carbon filler, fullerene, on the properties of HNBR was studied. Fullerenes are conductive and thermally stable due to their three dimensional aromaticity and high reactivity. In this work, the effect of fullerenes (C60) on the properties of HNBR rubber for potential use in aggressive environments was investigated. The vulcanized HNBR rubber with different filler loadings of fullerenes was compared with carbon black (N330). The static mechanical, dynamic mechanical and rheological behavior of the compounds was investigated, along with the vulcanization kinetics study. Increased filler loading of both carbon black and fullerene gave higher modulus and strength. The fullerene filled materials showed improved failure properties.

Study on the residual stress relaxation in girth-welded steel pipes under bending load using diffraction methods

DOE PAGES

Hempel, Nico; Bunn, Jeffrey R.; Nitschke-Pagel, Thomas; ...

2017-02-02

This research is dedicated to the experimental investigation of the residual stress relaxation in girth-welded pipes due to quasi-static bending loads. Ferritic-pearlitic steel pipes are welded with two passes, resulting in a characteristic residual stress state with high tensile residual stresses at the weld root. Also, four-point bending is applied to generate axial load stress causing changes in the residual stress state. These are determined both on the outer and inner surfaces of the pipes, as well as in the pipe wall, using X-ray and neutron diffraction. Focusing on the effect of tensile load stress, it is revealed that notmore » only the tensile residual stresses are reduced due to exceeding the yield stress, but also the compressive residual stresses for equilibrium reasons. Furthermore, residual stress relaxation occurs both parallel and perpendicular to the applied load stress.« less

Study on the residual stress relaxation in girth-welded steel pipes under bending load using diffraction methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hempel, Nico; Bunn, Jeffrey R.; Nitschke-Pagel, Thomas

This research is dedicated to the experimental investigation of the residual stress relaxation in girth-welded pipes due to quasi-static bending loads. Ferritic-pearlitic steel pipes are welded with two passes, resulting in a characteristic residual stress state with high tensile residual stresses at the weld root. Also, four-point bending is applied to generate axial load stress causing changes in the residual stress state. These are determined both on the outer and inner surfaces of the pipes, as well as in the pipe wall, using X-ray and neutron diffraction. Focusing on the effect of tensile load stress, it is revealed that notmore » only the tensile residual stresses are reduced due to exceeding the yield stress, but also the compressive residual stresses for equilibrium reasons. Furthermore, residual stress relaxation occurs both parallel and perpendicular to the applied load stress.« less

Marrow fat may distribute the energy of impact loading throughout subchondral bone

PubMed Central

Simkin, Peter A

2018-01-01

Abstract Most students of articular mechanics consider impact loads to be compressive forces that are borne by an intraosseous, trabecular scaffold. The possible role of marrow fat, which comprises about 75% of the structure, is generally ignored, and the potential contribution of type 1 collagen, the prototypic tensile protein, is not considered. Here, I question the evidence underlying these omissions and reject the conclusion of exclusive trabecular compression. Instead, I suggest that impact loading pressurizes the fat in subchondral compartments, and those pressures stretch the elastic trabecular walls, which are thereby subjected to tensile loading. The load-driven pressure pulses then diminish as they pass from each compartment to its adjoining neighbours. The resulting pressure gradient distributes the burden throughout the subchondrium, stores energy for ensuing recovery and subjects individual trabeculae only to the net pressure differences between adjacent compartments. PMID:28977578

Peg supported thermal insulation panel

DOEpatents

Nowobilski, Jeffert J.; Owens, William J.

1985-01-01

A thermal insulation panel which is lightweight, load bearing, accommodates thermal stress, and has excellent high temperature insulation capability comprising high performance insulation between thin metal walls supported by high density, high strength glass pegs made in compliance with specified conditions of time, temperature and pressure.

Drilled Shaft Foundations for Noise Barrier Walls and Slope Stabilization : Executive Summary

DOT National Transportation Integrated Search

2002-12-01

This research project is focused on two primary objectives. The first objective relates to the development of a methodology for using the SPT (Standard Penetration Test) results to design the laterally loaded drilled shafts. The second objective aims...

Analysis and seismic tests of composite shear walls with CFST columns and steel plate deep beams

NASA Astrophysics Data System (ADS)

Dong, Hongying; Cao, Wanlin; Wu, Haipeng; Zhang, Jianwei; Xu, Fangfang

2013-12-01

A composite shear wall concept based on concrete filled steel tube (CFST) columns and steel plate (SP) deep beams is proposed and examined in this study. The new wall is composed of three different energy dissipation elements: CFST columns; SP deep beams; and reinforced concrete (RC) strips. The RC strips are intended to allow the core structural elements — the CFST columns and SP deep beams — to work as a single structure to consume energy. Six specimens of different configurations were tested under cyclic loading. The resulting data are analyzed herein. In addition, numerical simulations of the stress and damage processes for each specimen were carried out, and simulations were completed for a range of location and span-height ratio variations for the SP beams. The simulations show good agreement with the test results. The core structure exhibits a ductile yielding mechanism characteristic of strong column-weak beam structures, hysteretic curves are plump and the composite shear wall exhibits several seismic defense lines. The deformation of the shear wall specimens with encased CFST column and SP deep beam design appears to be closer to that of entire shear walls. Establishing optimal design parameters for the configuration of SP deep beams is pivotal to the best seismic behavior of the wall. The new composite shear wall is therefore suitable for use in the seismic design of building structures.

Wall interaction effects for a full-scale helicopter rotor in the NASA Ames 80- by 120-foot wind tunnel

NASA Technical Reports Server (NTRS)

Shinoda, Patrick M.

1994-01-01

A full-scale helicopter rotor test was conducted in the NASA Ames 80- by 120-Foot Wind Tunnel with a four-bladed S-76 rotor system. This wind tunnel test generated a unique and extensive data base covering a wide range of rotor shaft angles-of-attack and rotor thrust conditions from 0 to 100 knots. Three configurations were tested: (1) empty tunnel; (2) test stand body (fuselage) and support system; and (3) fuselage and support system with rotor installed. Empty tunnel wall pressure data are evaluated as a function of tunnel speed to understand the baseline characteristics. Aerodynamic interaction effects between the fuselage and the walls of the tunnel are investigated by comparing wall, ceiling, and floor pressures for various tunnel velocities and fuselage angles-of-attack. Aerodynamic interaction effects between the rotor and the walls of the tunnel are also investigated by comparing wall, ceiling, and floor pressures for various rotor shaft angles, rotor thrust conditions, and tunnel velocities. Empty tunnel wall pressure data show good repeatability and are not affected by tunnel speed. In addition, the tunnel wall pressure profiles are not affected by the presence of the fuselage apart from a pressure shift. Results do not indicate that the tunnel wall pressure profiles are affected by the presence of the rotor. Significant changes in the wall, ceiling, and floor pressure profiles occur with changing tunnel speeds for constant rotor thrust and shaft angle conditions. Significant changes were also observed when varying rotor thrust or rotor shaft angle-of-attack. Other results indicate that dynamic rotor loads and blade motion are influenced by the presence of the tunnel walls at very low tunnel velocity and, together with the wall pressure data, provide a good indication of flow breakdown.

Elevated ventricular wall stress disrupts cardiomyocyte t-tubule structure and calcium homeostasis.

PubMed

Frisk, Michael; Ruud, Marianne; Espe, Emil K S; Aronsen, Jan Magnus; Røe, Åsmund T; Zhang, Lili; Norseng, Per Andreas; Sejersted, Ole M; Christensen, Geir A; Sjaastad, Ivar; Louch, William E

2016-10-01

Invaginations of the cellular membrane called t-tubules are essential for maintaining efficient excitation-contraction coupling in ventricular cardiomyocytes. Disruption of t-tubule structure during heart failure has been linked to dyssynchronous, slowed Ca(2+) release and reduced power of the heartbeat. The underlying mechanism is, however, unknown. We presently investigated whether elevated ventricular wall stress triggers remodelling of t-tubule structure and function. MRI and blood pressure measurements were employed to examine regional wall stress across the left ventricle of sham-operated and failing, post-infarction rat hearts. In failing hearts, elevated left ventricular diastolic pressure and ventricular dilation resulted in markedly increased wall stress, particularly in the thin-walled region proximal to the infarct. High wall stress in this proximal zone was associated with reduced expression of the dyadic anchor junctophilin-2 and disrupted cardiomyocyte t-tubular structure. Indeed, local wall stress measurements predicted t-tubule density across sham and failing hearts. Elevated wall stress and disrupted cardiomyocyte structure in the proximal zone were also associated with desynchronized Ca(2+) release in cardiomyocytes and markedly reduced local contractility in vivo. A causative role of wall stress in promoting t-tubule remodelling was established by applying stretch to papillary muscles ex vivo under culture conditions. Loads comparable to wall stress levels observed in vivo in the proximal zone reduced expression of junctophilin-2 and promoted t-tubule loss. Elevated wall stress reduces junctophilin-2 expression and disrupts t-tubule integrity, Ca(2+) release, and contractile function. These findings provide new insight into the role of wall stress in promoting heart failure progression. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Cardiology.

Effects of Gasoline Direct Injection Engine Operating Parameters on Particle Number Emissions

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, X.; Ratcliff, M. A.; Zigler, B. T.

2012-04-19

A single-cylinder, wall-guided, spark ignition direct injection engine was used to study the impact of engine operating parameters on engine-out particle number (PN) emissions. Experiments were conducted with certification gasoline and a splash blend of 20% fuel grade ethanol in gasoline (E20), at four steady-state engine operating conditions. Independent engine control parameter sweeps were conducted including start of injection, injection pressure, spark timing, exhaust cam phasing, intake cam phasing, and air-fuel ratio. The results show that fuel injection timing is the dominant factor impacting PN emissions from this wall-guided gasoline direct injection engine. The major factor causing high PN emissionsmore » is fuel liquid impingement on the piston bowl. By avoiding fuel impingement, more than an order of magnitude reduction in PN emission was observed. Increasing fuel injection pressure reduces PN emissions because of smaller fuel droplet size and faster fuel-air mixing. PN emissions are insensitive to cam phasing and spark timing, especially at high engine load. Cold engine conditions produce higher PN emissions than hot engine conditions due to slower fuel vaporization and thus less fuel-air homogeneity during the combustion process. E20 produces lower PN emissions at low and medium loads if fuel liquid impingement on piston bowl is avoided. At high load or if there is fuel liquid impingement on piston bowl and/or cylinder wall, E20 tends to produce higher PN emissions. This is probably a function of the higher heat of vaporization of ethanol, which slows the vaporization of other fuel components from surfaces and may create local fuel-rich combustion or even pool-fires.« less

Overview of progress in European medium sized tokamaks towards an integrated plasma-edge/wall solution

NASA Astrophysics Data System (ADS)

Meyer, H.; Eich, T.; Beurskens, M.; Coda, S.; Hakola, A.; Martin, P.; Adamek, J.; Agostini, M.; Aguiam, D.; Ahn, J.; Aho-Mantila, L.; Akers, R.; Albanese, R.; Aledda, R.; Alessi, E.; Allan, S.; Alves, D.; Ambrosino, R.; Amicucci, L.; Anand, H.; Anastassiou, G.; Andrèbe, Y.; Angioni, C.; Apruzzese, G.; Ariola, M.; Arnichand, H.; Arter, W.; Baciero, A.; Barnes, M.; Barrera, L.; Behn, R.; Bencze, A.; Bernardo, J.; Bernert, M.; Bettini, P.; Bilková, P.; Bin, W.; Birkenmeier, G.; Bizarro, J. P. S.; Blanchard, P.; Blanken, T.; Bluteau, M.; Bobkov, V.; Bogar, O.; Böhm, P.; Bolzonella, T.; Boncagni, L.; Botrugno, A.; Bottereau, C.; Bouquey, F.; Bourdelle, C.; Brémond, S.; Brezinsek, S.; Brida, D.; Brochard, F.; Buchanan, J.; Bufferand, H.; Buratti, P.; Cahyna, P.; Calabrò, G.; Camenen, Y.; Caniello, R.; Cannas, B.; Canton, A.; Cardinali, A.; Carnevale, D.; Carr, M.; Carralero, D.; Carvalho, P.; Casali, L.; Castaldo, C.; Castejón, F.; Castro, R.; Causa, F.; Cavazzana, R.; Cavedon, M.; Cecconello, M.; Ceccuzzi, S.; Cesario, R.; Challis, C. D.; Chapman, I. T.; Chapman, S.; Chernyshova, M.; Choi, D.; Cianfarani, C.; Ciraolo, G.; Citrin, J.; Clairet, F.; Classen, I.; Coelho, R.; Coenen, J. W.; Colas, L.; Conway, G.; Corre, Y.; Costea, S.; Crisanti, F.; Cruz, N.; Cseh, G.; Czarnecka, A.; D'Arcangelo, O.; De Angeli, M.; De Masi, G.; De Temmerman, G.; De Tommasi, G.; Decker, J.; Delogu, R. S.; Dendy, R.; Denner, P.; Di Troia, C.; Dimitrova, M.; D'Inca, R.; Dorić, V.; Douai, D.; Drenik, A.; Dudson, B.; Dunai, D.; Dunne, M.; Duval, B. P.; Easy, L.; Elmore, S.; Erdös, B.; Esposito, B.; Fable, E.; Faitsch, M.; Fanni, A.; Fedorczak, N.; Felici, F.; Ferreira, J.; Février, O.; Ficker, O.; Fietz, S.; Figini, L.; Figueiredo, A.; Fil, A.; Fishpool, G.; Fitzgerald, M.; Fontana, M.; Ford, O.; Frassinetti, L.; Fridström, R.; Frigione, D.; Fuchert, G.; Fuchs, C.; Furno Palumbo, M.; Futatani, S.; Gabellieri, L.; Gałązka, K.; Galdon-Quiroga, J.; Galeani, S.; Gallart, D.; Gallo, A.; Galperti, C.; Gao, Y.; Garavaglia, S.; Garcia, J.; Garcia-Carrasco, A.; Garcia-Lopez, J.; Garcia-Munoz, M.; Gardarein, J.-L.; Garzotti, L.; Gaspar, J.; Gauthier, E.; Geelen, P.; Geiger, B.; Ghendrih, P.; Ghezzi, F.; Giacomelli, L.; Giannone, L.; Giovannozzi, E.; Giroud, C.; Gleason González, C.; Gobbin, M.; Goodman, T. P.; Gorini, G.; Gospodarczyk, M.; Granucci, G.; Gruber, M.; Gude, A.; Guimarais, L.; Guirlet, R.; Gunn, J.; Hacek, P.; Hacquin, S.; Hall, S.; Ham, C.; Happel, T.; Harrison, J.; Harting, D.; Hauer, V.; Havlickova, E.; Hellsten, T.; Helou, W.; Henderson, S.; Hennequin, P.; Heyn, M.; Hnat, B.; Hölzl, M.; Hogeweij, D.; Honoré, C.; Hopf, C.; Horáček, J.; Hornung, G.; Horváth, L.; Huang, Z.; Huber, A.; Igitkhanov, J.; Igochine, V.; Imrisek, M.; Innocente, P.; Ionita-Schrittwieser, C.; Isliker, H.; Ivanova-Stanik, I.; Jacobsen, A. S.; Jacquet, P.; Jakubowski, M.; Jardin, A.; Jaulmes, F.; Jenko, F.; Jensen, T.; Jeppe Miki Busk, O.; Jessen, M.; Joffrin, E.; Jones, O.; Jonsson, T.; Kallenbach, A.; Kallinikos, N.; Kálvin, S.; Kappatou, A.; Karhunen, J.; Karpushov, A.; Kasilov, S.; Kasprowicz, G.; Kendl, A.; Kernbichler, W.; Kim, D.; Kirk, A.; Kjer, S.; Klimek, I.; Kocsis, G.; Kogut, D.; Komm, M.; Korsholm, S. B.; Koslowski, H. R.; Koubiti, M.; Kovacic, J.; Kovarik, K.; Krawczyk, N.; Krbec, J.; Krieger, K.; Krivska, A.; Kube, R.; Kudlacek, O.; Kurki-Suonio, T.; Labit, B.; Laggner, F. M.; Laguardia, L.; Lahtinen, A.; Lalousis, P.; Lang, P.; Lauber, P.; Lazányi, N.; Lazaros, A.; Le, H. B.; Lebschy, A.; Leddy, J.; Lefévre, L.; Lehnen, M.; Leipold, F.; Lessig, A.; Leyland, M.; Li, L.; Liang, Y.; Lipschultz, B.; Liu, Y. Q.; Loarer, T.; Loarte, A.; Loewenhoff, T.; Lomanowski, B.; Loschiavo, V. P.; Lunt, T.; Lupelli, I.; Lux, H.; Lyssoivan, A.; Madsen, J.; Maget, P.; Maggi, C.; Maggiora, R.; Magnussen, M. L.; Mailloux, J.; Maljaars, B.; Malygin, A.; Mantica, P.; Mantsinen, M.; Maraschek, M.; Marchand, B.; Marconato, N.; Marini, C.; Marinucci, M.; Markovic, T.; Marocco, D.; Marrelli, L.; Martin, Y.; Solis, J. R. Martin; Martitsch, A.; Mastrostefano, S.; Mattei, M.; Matthews, G.; Mavridis, M.; Mayoral, M.-L.; Mazon, D.; McCarthy, P.; McAdams, R.; McArdle, G.; McCarthy, P.; McClements, K.; McDermott, R.; McMillan, B.; Meisl, G.; Merle, A.; Meyer, O.; Milanesio, D.; Militello, F.; Miron, I. G.; Mitosinkova, K.; Mlynar, J.; Mlynek, A.; Molina, D.; Molina, P.; Monakhov, I.; Morales, J.; Moreau, D.; Morel, P.; Moret, J.-M.; Moro, A.; Moulton, D.; Müller, H. W.; Nabais, F.; Nardon, E.; Naulin, V.; Nemes-Czopf, A.; Nespoli, F.; Neu, R.; Nielsen, A. H.; Nielsen, S. K.; Nikolaeva, V.; Nimb, S.; Nocente, M.; Nouailletas, R.; Nowak, S.; Oberkofler, M.; Oberparleiter, M.; Ochoukov, R.; Odstrčil, T.; Olsen, J.; Omotani, J.; O'Mullane, M. G.; Orain, F.; Osterman, N.; Paccagnella, R.; Pamela, S.; Pangione, L.; Panjan, M.; Papp, G.; Papřok, R.; Parail, V.; Parra, F. I.; Pau, A.; Pautasso, G.; Pehkonen, S.-P.; Pereira, A.; Perelli Cippo, E.; Pericoli Ridolfini, V.; Peterka, M.; Petersson, P.; Petrzilka, V.; Piovesan, P.; Piron, C.; Pironti, A.; Pisano, F.; Pisokas, T.; Pitts, R.; Ploumistakis, I.; Plyusnin, V.; Pokol, G.; Poljak, D.; Pölöskei, P.; Popovic, Z.; Pór, G.; Porte, L.; Potzel, S.; Predebon, I.; Preynas, M.; Primc, G.; Pucella, G.; Puiatti, M. E.; Pütterich, T.; Rack, M.; Ramogida, G.; Rapson, C.; Rasmussen, J. Juul; Rasmussen, J.; Rattá, G. A.; Ratynskaia, S.; Ravera, G.; Réfy, D.; Reich, M.; Reimerdes, H.; Reimold, F.; Reinke, M.; Reiser, D.; Resnik, M.; Reux, C.; Ripamonti, D.; Rittich, D.; Riva, G.; Rodriguez-Ramos, M.; Rohde, V.; Rosato, J.; Ryter, F.; Saarelma, S.; Sabot, R.; Saint-Laurent, F.; Salewski, M.; Salmi, A.; Samaddar, D.; Sanchis-Sanchez, L.; Santos, J.; Sauter, O.; Scannell, R.; Scheffer, M.; Schneider, M.; Schneider, B.; Schneider, P.; Schneller, M.; Schrittwieser, R.; Schubert, M.; Schweinzer, J.; Seidl, J.; Sertoli, M.; Šesnić, S.; Shabbir, A.; Shalpegin, A.; Shanahan, B.; Sharapov, S.; Sheikh, U.; Sias, G.; Sieglin, B.; Silva, C.; Silva, A.; Silva Fuglister, M.; Simpson, J.; Snicker, A.; Sommariva, C.; Sozzi, C.; Spagnolo, S.; Spizzo, G.; Spolaore, M.; Stange, T.; Stejner Pedersen, M.; Stepanov, I.; Stober, J.; Strand, P.; Šušnjara, A.; Suttrop, W.; Szepesi, T.; Tál, B.; Tala, T.; Tamain, P.; Tardini, G.; Tardocchi, M.; Teplukhina, A.; Terranova, D.; Testa, D.; Theiler, C.; Thornton, A.; Tolias, P.; Tophøj, L.; Treutterer, W.; Trevisan, G. L.; Tripsky, M.; Tsironis, C.; Tsui, C.; Tudisco, O.; Uccello, A.; Urban, J.; Valisa, M.; Vallejos, P.; Valovic, M.; Van den Brand, H.; Vanovac, B.; Varoutis, S.; Vartanian, S.; Vega, J.; Verdoolaege, G.; Verhaegh, K.; Vermare, L.; Vianello, N.; Vicente, J.; Viezzer, E.; Vignitchouk, L.; Vijvers, W. A. J.; Villone, F.; Viola, B.; Vlahos, L.; Voitsekhovitch, I.; Vondráček, P.; Vu, N. M. T.; Wagner, D.; Walkden, N.; Wang, N.; Wauters, T.; Weiland, M.; Weinzettl, V.; Westerhof, E.; Wiesenberger, M.; Willensdorfer, M.; Wischmeier, M.; Wodniak, I.; Wolfrum, E.; Yadykin, D.; Zagórski, R.; Zammuto, I.; Zanca, P.; Zaplotnik, R.; Zestanakis, P.; Zhang, W.; Zoletnik, S.; Zuin, M.; ASDEX Upgrade, the; MAST; TCV Teams

2017-10-01

Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n  =  2 RMP maintaining good confinement {{H}\\text{H≤ft(98,\\text{y}2\\right)}}≈ 0.95 . Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes. In the future we will refer to the author list of the paper as the EUROfusion MST1 Team.

A multivariate approach using attenuated total reflectance mid-infrared spectroscopy to measure the surface mannoproteins and β-glucans of yeast cell walls during wine fermentations.

PubMed

Moore, John P; Zhang, Song-Lei; Nieuwoudt, Hélène; Divol, Benoit; Trygg, Johan; Bauer, Florian F

2015-11-18

Yeast cells possess a cell wall comprising primarily glycoproteins, mannans, and glucan polymers. Several yeast phenotypes relevant for fermentation, wine processing, and wine quality are correlated with cell wall properties. To investigate the effect of wine fermentation on cell wall composition, a study was performed using mid-infrared (MIR) spectroscopy coupled with multivariate methods (i.e., PCA and OPLS-DA). A total of 40 yeast strains were evaluated, including Saccharomyces strains (laboratory and industrial) and non-Saccharomyces species. Cells were fermented in both synthetic MS300 and Chardonnay grape must to stationery phase, processed, and scanned in the MIR spectrum. PCA of the fingerprint spectral region showed distinct separation of Saccharomyces strains from non-Saccharomyces species; furthermore, industrial wine yeast strains separated from laboratory strains. PCA loading plots and the use of OPLS-DA to the data sets suggested that industrial strains were enriched with cell wall proteins (e.g., mannoproteins), whereas laboratory strains were composed mainly of mannan and glucan polymers.

Effects of functionalization on thermal properties of single-wall and multi-wall carbon nanotube-polymer nanocomposites.

PubMed

Gulotty, Richard; Castellino, Micaela; Jagdale, Pravin; Tagliaferro, Alberto; Balandin, Alexander A

2013-06-25

Carboxylic functionalization (-COOH groups) of carbon nanotubes is known to improve their dispersion properties and increase the electrical conductivity of carbon-nanotube-polymer nanocomposites. We have studied experimentally the effects of this type of functionalization on the thermal conductivity of the nanocomposites. It was found that while even small quantities of carbon nanotubes (~1 wt %) can increase the electrical conductivity, a larger loading fraction (~3 wt %) is required to enhance the thermal conductivity of nanocomposites. Functionalized multi-wall carbon nanotubes performed the best as filler material leading to a simultaneous improvement of the electrical and thermal properties of the composites. Functionalization of the single-wall carbon nanotubes reduced the thermal conductivity enhancement. The observed trends were explained by the fact that while surface functionalization increases the coupling between carbon nanotube and polymer matrix, it also leads to formation of defects, which impede the acoustic phonon transport in the single-wall carbon nanotubes. The obtained results are important for applications of carbon nanotubes and graphene flakes as fillers for improving thermal, electrical and mechanical properties of composites.

Sectoral combustor for burning low-BTU fuel gas

DOEpatents

Vogt, Robert L.

1980-01-01

A high-temperature combustor for burning low-BTU coal gas in a gas turbine is disclosed. The combustor includes several separately removable combustion chambers each having an annular sectoral cross section and a double-walled construction permitting separation of stresses due to pressure forces and stresses due to thermal effects. Arrangements are described for air-cooling each combustion chamber using countercurrent convective cooling flow between an outer shell wall and an inner liner wall and using film cooling flow through liner panel grooves and along the inner liner wall surface, and for admitting all coolant flow to the gas path within the inner liner wall. Also described are systems for supplying coal gas, combustion air, and dilution air to the combustion zone, and a liquid fuel nozzle for use during low-load operation. The disclosed combustor is fully air-cooled, requires no transition section to interface with a turbine nozzle, and is operable at firing temperatures of up to 3000.degree. F. or within approximately 300.degree. F. of the adiabatic stoichiometric limit of the coal gas used as fuel.

Moisture Performance of High-R Wall Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shah, Nay B.; Kochkin, Vladimir

High-performance homes offer improved comfort, lower utility bills, and assured durability. The next generation of building enclosures is a key step toward achieving high-performance goals through decreasing energy load demand and enabling advanced space-conditioning systems. Yet the adoption of high-R enclosures and particularly high-R walls has been a slow-growing trend because mainstream builders are hesitant to make the transition. In a survey of builders on this topic, one of the challenges identifi ed is an industry-wide concern about the long-term moisture performance of energy-effi cient walls. This study takes a step toward addressing this concern through direct monitoring of themore » moisture performance of high-R walls in occupied homes in several climate zones. In addition, the robustness of the design and modeling tools for selecting high-R wall solutions is evaluated using the monitored data from the field. The information and knowledge gained through this research will provide an objective basis for decision-making so that builders can implement advanced designs with confidence.« less

Haemodynamic predictors of a penetrating atherosclerotic ulcer rupture using fluid–structure interaction analysis

PubMed Central

D'Ancona, Giuseppe; Amaducci, Andrea; Rinaudo, Antonino; Pasta, Salvatore; Follis, Fabrizio; Pilato, Michele; Baglini, Roberto

2013-01-01

We present preliminary data on the flow-induced haemodynamic and structural loads exerted on a penetrating atherosclerotic aortic ulcer (PAU). Specifically, one-way fluid–structure interaction analysis was performed on the aortic model reconstructed from a 66-year-old male patient with a PAU that evolved into an intramural haematoma and rupture of the thoracic aorta. The results show that elevated blood pressure (117 mmHg) and low flow velocity at the aortic wall (0.15 m/s2) occurred in the region of the PAU. We also found a low value of time-averaged wall shear stress (1.24 N/m2) and a high value of the temporal oscillation in the wall shear stress (oscillatory shear index = 0.13) in the region of the PAU. After endovascular treatment, these haemodynamic parameters were distributed uniformly on the luminal surface of the stent graft. These findings suggest that wall shear stress could be considered one of the major haemodynamic factors indicating the structural fragility of the PAU wall, which ultimately lead to PAU growth and rupture. PMID:23736658

Experimental and numerical analysis of pre-compressed masonry walls in two-way-bending with second order effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milani, Gabriele, E-mail: milani@stru.polimi.it; Olivito, Renato S.; Tralli, Antonio

2014-10-06

The buckling behavior of slender unreinforced masonry (URM) walls subjected to axial compression and out-of-plane lateral loads is investigated through a combined experimental and numerical homogenizedapproach. After a preliminary analysis performed on a unit cell meshed by means of elastic FEs and non-linear interfaces, macroscopic moment-curvature diagrams so obtained are implemented at a structural level, discretizing masonry by means of rigid triangular elements and non-linear interfaces. The non-linear incremental response of the structure is accounted for a specific quadratic programming routine. In parallel, a wide experimental campaign is conducted on walls in two way bending, with the double aim ofmore » both validating the numerical model and investigating the behavior of walls that may not be reduced to simple cantilevers or simply supported beams. Panels investigated are dry-joint in scale square walls simply supported at the base and on a vertical edge, exhibiting the classical Rondelet’s mechanism. The results obtained are compared with those provided by the numerical model.« less

High-Power Piezoelectric Acoustic-Electric Power Feedthru for Metal Walls

NASA Technical Reports Server (NTRS)

Bao, Xiaoqi; Biederman, Will; Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph; Jones, Christopher; Aldrich, Jack; Chang, Zensheu

2008-01-01

Piezoelectric acoustic-electric power feed-through devices transfer electric power wirelessly through a solid wall by using acoustic waves. This approach allows for the removal of holes through structures. The technology is applicable to power supply for electric equipment inside sealed containers, vacuum or pressure vessels, etc where the holes on the wall are prohibitive or result in significant performance degrade or complex designs. In the author's previous work, 100-W electric power was transferred through a metal wall by a small, simple-structure piezoelectric device. To meet requirements of higher power applications, the feasibility to transfer kilowatts level power was investigated. Pre-stressed longitudinal piezoelectric feedthru devices were analyzed by finite element model. An equivalent circuit model was developed to predict the power transfer characteristics to different electric loads. Based on the analysis results, a prototype device was designed, fabricated and a demonstration of the transmission of electric power up to 1-kW was successfully conducted. The methods to minimize the plate wave excitation on the wall were also analyzed. Both model analysis and experimental results are presented in detail in this presentation.

Cellulose-hemicellulose interaction in wood secondary cell-wall

NASA Astrophysics Data System (ADS)

Zhang, Ning; Li, Shi; Xiong, Liming; Hong, Yu; Chen, Youping

2015-12-01

The wood cell wall features a tough and relatively rigid fiber reinforced composite structure. It acts as a pressure vessel, offering protection against mechanical stress. Cellulose microfibrils, hemicellulose and amorphous lignin are the three major components of wood. The structure of secondary cell wall could be imagined as the same as reinforced concrete, in which cellulose microfibrils acts as reinforcing steel bar and hemicellulose-lignin matrices act as the concrete. Therefore, the interface between cellulose and hemicellulose/lignin plays a significant role in determine the mechanical behavior of wood secondary cell wall. To this end, we present a molecular dynamics (MD) simulation study attempting to quantify the strength of the interface between cellulose microfibrils and hemicellulose. Since hemicellulose binds with adjacent cellulose microfibrils in various patterns, the atomistic models of hemicellulose-cellulose composites with three typical binding modes, i.e. bridge, loop and random binding modes are constructed. The effect of the shape of hemicellulose chain on the strength of hemicellulose-cellulose composites under shear loadings is investigated. The contact area as well as hydrogen bonds between cellulose and hemicellulose, together with the covalent bonds in backbone of hemicellulose chain are found to be the controlling parameters which determine the strength of the interfaces in the composite system. For the bridge binding model, the effect of shear loading direction on the strength of the cellulose material is also studied. The obtained results suggest that the shear strength of wood-inspired engineering composites can be optimized through maximizing the formations of the contributing hydrogen bonds between cellulose and hemicellulose.

The Effects of Geometric and Loading Imperfections on the Response and Lower-Bound Buckling Load of a Compression-Loaded Cylindrical Shell

NASA Technical Reports Server (NTRS)

Kriegesmann, Benedikt; Hilburger, Mark W.; Rolfes, Raimund

2012-01-01

Results from a numerical study of the buckling response of a thin-walled compressionloaded isotropic circular cylindrical shell with initial geometric and loading imperfections are used to determine a lower bound buckling load estimate suitable for preliminary design. The lower bound prediction techniques presented herein include an imperfection caused by a lateral perturbation load, an imperfection in the shape of a single stress-free dimple (similar to the lateral pertubation imperfection), and a distributed load imperfection that induces a nonuniform load in the shell. The ABAQUS finite element code is used for the analyses. Responses of the cylinders for selected imperfection amplitudes and imperfection types are considered, and the effect of each imperfection is compared to the response of a geometrically perfect cylinder. The results indicate that compression-loaded shells subjected to a lateral perturbation load or a single dimple imperfection, and a nonuniform load imperfection, exhibit similar buckling behavior and lower bound trends and the predicted lower bounds are much less conservative than the corresponding design recommendation NASA SP-8007 for the design of buckling-critical shells. In addition, the lateral perturbation technique and the distributed load imperfection produce response characteristics that are physically meaningful and can be validated via laboratory testing.

Structural analysis and testing of a carbon-composite wing using fiber Bragg gratings

NASA Astrophysics Data System (ADS)

Nicolas, Matthew James

The objective of this study was to determine the deflected wing shape and the out-of-plane loads of a large-scale carbon-composite wing of an ultralight aerial vehicle using Fiber Bragg Grating (FBG) technology. The composite wing was instrumented with an optical fiber on its top and bottom surfaces positioned over the main spar, resulting in approximately 780 strain sensors bonded to the wings. The strain data from the FBGs was compared to that obtained from four conventional strain gages, and was used to obtain the out-of-plane loads as well as the wing shape at various load levels using NASA-developed real-time load and displacement algorithms. The composite wing measured 5.5 meters and was fabricated from laminated carbon uniaxial and biaxial prepreg fabric with varying laminate ply patterns and wall thickness dimensions. A three-tier whiffletree system was used to load the wing in a manner consistent with an in-flight loading condition.

Failure strength of the bovine caudal disc under internal hydrostatic pressure.

PubMed

Schechtman, Helio; Robertson, Peter A; Broom, Neil D

2006-01-01

The structure of the disc is both complex and inhomogeneous, and it functions as a successful load-bearing organ by virtue of the integration of its various structural regions. These same features also render it impossible to assess the failure strength of the disc from isolated tissue samples, which at best can only yield material properties. This study investigated the intrinsic failure strength of the intact bovine caudal disc under a simple mode of internal hydrostatic pressure. Using a hydraulic actuator, coloured hydrogel was injected under monitored pressure into the nucleus through a hollow screw insert which passed longitudinally through one of the attached vertebrae. Failure did not involve vertebra/endplate structures. Rather, failure of the disc annulus was indicated by the simultaneous manifestation of a sudden loss of gel pressure, a flood of gel colouration appearing in the outer annulus and audible fibrous tearing. A mean hydrostatic failure pressure of 18+/-3 MPa was observed which was approximated as a thick-wall hoop stress of 45+/-7 MPa. The experiment provides a measurement of the intrinsic strength of the disc using a method of internal hydrostatic loading which avoids any disruption of the complex architecture of the annular wall. Although the disc in vivo is subjected to a much more complex pattern of loading than is achieved using simple hydrostatic pressurization, this latter mode provides a useful tool for investigating alterations in intrinsic disc strength associated with prior loading history or degeneration.

Cellular growth in plants requires regulation of cell wall biochemistry.

PubMed

Chebli, Youssef; Geitmann, Anja

2017-02-01

Cell and organ morphogenesis in plants are regulated by the chemical structure and mechanical properties of the extracellular matrix, the cell wall. The two primary load bearing components in the plant cell wall, the pectin matrix and the cellulose/xyloglucan network, are constantly remodelled to generate the morphological changes required during plant development. This remodelling is regulated by a plethora of loosening and stiffening agents such as pectin methyl-esterases, calcium ions, expansins, and glucanases. The tight spatio-temporal regulation of the activities of these agents is a sine qua non condition for proper morphogenesis at cell and tissue levels. The pectin matrix and the cellulose-xyloglucan network operate in concert and their behaviour is mutually dependent on their chemical, structural and mechanical modifications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Refilling of carbon nanotube cartridges for 3D nanomanufacturing

NASA Astrophysics Data System (ADS)

Bekarevich, Raman; Toyoda, Masami; Baba, Shuichi; Nakata, Toshihiko; Hirahara, Kaori

2016-03-01

Metal-filled carbon nanotubes (CNTs) are known to be used as pen-tip injectors for 3D manufacturing on the nanoscale. However, the CNT interior cannot accumulate enough material to fabricate complex metallic nanostructures. Therefore a method for refilling the CNT cartridge needs to be developed. The strategy for refilling of CNT cartridges is suggested in this study. Controlled growth of gold nanowires in the interior of isolated CNTs using a real-time manipulator installed in a transmission electron microscope is reported herein. The encapsulation process of discrete gold nanoparticles in the hollow spaces of open-ended multi-wall CNTs was evaluated in detail. The experimental results reveal that the serial loading of isolated gold nanoparticles allows the control of the length of the loaded nanowires with nanometer accuracy. Thermophoresis and the coalescence of gold nanoparticles are assumed to be the primary mechanisms responsible for gold loading into a CNT cartridge.Metal-filled carbon nanotubes (CNTs) are known to be used as pen-tip injectors for 3D manufacturing on the nanoscale. However, the CNT interior cannot accumulate enough material to fabricate complex metallic nanostructures. Therefore a method for refilling the CNT cartridge needs to be developed. The strategy for refilling of CNT cartridges is suggested in this study. Controlled growth of gold nanowires in the interior of isolated CNTs using a real-time manipulator installed in a transmission electron microscope is reported herein. The encapsulation process of discrete gold nanoparticles in the hollow spaces of open-ended multi-wall CNTs was evaluated in detail. The experimental results reveal that the serial loading of isolated gold nanoparticles allows the control of the length of the loaded nanowires with nanometer accuracy. Thermophoresis and the coalescence of gold nanoparticles are assumed to be the primary mechanisms responsible for gold loading into a CNT cartridge. Electronic supplementary information (ESI) available: Variations of loading of the initial nanoparticle into the CNT, movies demonstrating the processes of the loading of the initial nanoparticle and elongation of encapsulated nanowire. See DOI: 10.1039/c5nr08712k

Electromagnetic Analysis of ITER Diagnostic Equatorial Port Plugs During Plasma Disruptions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Y. Zhai, R. Feder, A. Brooks, M. Ulrickson, C.S. Pitcher and G.D. Loesser

2012-08-27

ITER diagnostic port plugs perform many functionsincluding structural support of diagnostic systems under high electromagnetic loads while allowing for diagnostic access to the plasma. The design of diagnostic equatorial port plugs (EPP) are largely driven by electromagnetic loads and associate responses of EPP structure during plasma disruptions and VDEs. This paper summarizes results of transient electromagnetic analysis using Opera 3d in support of the design activities for ITER diagnostic EPP. A complete distribution of disruption loads on the Diagnostic First Walls (DFWs), Diagnostic Shield Modules (DSMs) and the EPP structure, as well as impact on the system design integration duemore » to electrical contact among various EPP structural components are discussed.« less

Displacement coefficients along the inner boundaries of radially cracked ring segments subject to forces and couples

NASA Technical Reports Server (NTRS)

Gross, B.

1977-01-01

Displacement results of plane boundary collocation analysis are given for various locations on the inner boundaries of radially cracked ring segments (C-shaped specimens) subject to two complementary types of loading. Results are presented for ratios of outer to inner radius R sub o/R sub i in the range of 1.1 to 2.5, and ratios a/W in the range 0.1 to 0.8 where a is the crack length for a specimen of wall thickness W. By combination of these results the resultant displacement coefficient delta or the corresponding influence coefficient, can be obtained for any practical load line location of a pin loaded specimen.

Peg supported thermal insulation panel

DOEpatents

Nowobilski, J.J.; Owens, W.J.

1985-04-30

A thermal insulation panel which is lightweight, load bearing, accommodates thermal stress, and has excellent high temperature insulation capability comprises high performance insulation between thin metal walls supported by high density, high strength glass pegs made in compliance with specified conditions of time, temperature and pressure. 2 figs.

18 CFR 1307.1 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... condition, cosmetic disfigurement, or anatomical loss affecting one or more of the following body systems...; reproductive; digestive; genitourinary; hemic and lymphatic; skin; and endocrine; or (ii) any mental or... building, including but not limited to its load bearing walls and all types of post and beam systems in...

18 CFR 1307.1 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... condition, cosmetic disfigurement, or anatomical loss affecting one or more of the following body systems...; reproductive; digestive; genitourinary; hemic and lymphatic; skin; and endocrine; or (ii) any mental or... building, including but not limited to its load bearing walls and all types of post and beam systems in...

18 CFR 1307.1 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... condition, cosmetic disfigurement, or anatomical loss affecting one or more of the following body systems...; reproductive; digestive; genitourinary; hemic and lymphatic; skin; and endocrine; or (ii) any mental or... building, including but not limited to its load bearing walls and all types of post and beam systems in...

Lipid accumulation in smooth muscle cells under LDL loading is independent of LDL receptor pathway and enhanced by hypoxic conditions.

PubMed

Wada, Youichiro; Sugiyama, Akira; Yamamoto, Takashi; Naito, Makoto; Noguchi, Noriko; Yokoyama, Shinji; Tsujita, Maki; Kawabe, Yoshiki; Kobayashi, Mika; Izumi, Akashi; Kohro, Takahide; Tanaka, Toshiya; Taniguchi, Hirokazu; Koyama, Hidenori; Hirano, Ken-ichi; Yamashita, Shizuya; Matsuzawa, Yuji; Niki, Etsuo; Hamakubo, Takao; Kodama, Tatsuhiko

2002-10-01

The effect of a variety of hypoxic conditions on lipid accumulation in smooth muscle cells (SMCs) was studied in an arterial wall coculture and monocultivation model. Low density lipoprotein (LDL) was loaded under various levels of oxygen tension. Oil red O staining of rabbit and human SMCs revealed that lipid accumulation was greater under lower oxygen tension. Cholesterol esters were shown to accumulate in an oxygen tension-dependent manner by high-performance liquid chromatographic analysis. Autoradiograms using radiolabeled LDL indicated that LDL uptake was more pronounced under hypoxia. This result holds in the case of LDL receptor-deficient rabbit SMCs. However, cholesterol biosynthesis and cellular cholesterol release were unaffected by oxygen tension. Hypoxia significantly increases LDL uptake and enhances lipid accumulation in arterial SMCs, exclusive of LDL receptor activity. Although the molecular mechanism is not clear, the model is useful for studying lipid accumulation in arterial wall cells and the difficult-to-elucidate events in the initial stage of atherogenesis.

Investigation of Mild Steel Thin-Wall Tubes in Unfilled and Foam-Filled Triangle, Square, and Hexagonal Cross Sections Under Compression Load

NASA Astrophysics Data System (ADS)

Rajak, Dipen Kumar; Kumaraswamidhas, L. A.; Das, S.

2018-02-01

This study has examined proposed structures with mild steel-reinforced LM30 aluminum (Al) alloy having diversely unfilled and 10 wt.% SiCp composite foam-filled tubes for improving axial compression performance. This class of material has novel physical, mechanical, and electrical properties along with low density. In the present experiment, Al alloy foams were prepared by the melt route technique using metal hydride powder as a foaming agent. Crash energy phenomena for diverse unfilled and foam-filled in mild steel thin-wall tubes (triangular, square and hexagonal) were studied as well. Compression deformation investigation was conducted at strain rates of 0.001-0.1/s for evaluating specific energy absorption (SEA) under axial loading conditions. The results were examined to measure plateau stress, maximum densification strain, and deformation mechanism of the materials. Specific energy absorption and total energy absorption capacities of the unfilled and filled sections were determined from the compressive stress-strain curves, which were then compared with each other.

3D printed hierarchical honeycombs with shape integrity under large compressive deformations

DOE PAGES

Chen, Yanyu; Li, Tiantian; Jia, Zian; ...

2017-10-12

Here, we describe the in-plane compressive performance of a new type of hierarchical cellular structure created by replacing cell walls in regular honeycombs with triangular lattice configurations. The fabrication of this relatively complex material architecture with size features spanning from micrometer to centimeter is facilitated by the availability of commercial 3D printers. We apply to these hierarchical honeycombs a thermal treatment that facilitates the shape preservation and structural integrity of the structures under large compressive loading. The proposed hierarchical honeycombs exhibit a progressive failure mode, along with improved stiffness and energy absorption under uniaxial compression. High energy dissipation and shapemore » integrity at large imposed strains (up to 60%) have also been observed in these hierarchical honeycombs under cyclic loading. Experimental and numerical studies suggest that these anomalous mechanical behaviors are attributed to the introduction of a structural hierarchy, intrinsically controlled by the cell wall slenderness of the triangular lattice and by the shape memory effect induced by the thermal and mechanical compressive treatment.« less

3D printed hierarchical honeycombs with shape integrity under large compressive deformations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yanyu; Li, Tiantian; Jia, Zian

Here, we describe the in-plane compressive performance of a new type of hierarchical cellular structure created by replacing cell walls in regular honeycombs with triangular lattice configurations. The fabrication of this relatively complex material architecture with size features spanning from micrometer to centimeter is facilitated by the availability of commercial 3D printers. We apply to these hierarchical honeycombs a thermal treatment that facilitates the shape preservation and structural integrity of the structures under large compressive loading. The proposed hierarchical honeycombs exhibit a progressive failure mode, along with improved stiffness and energy absorption under uniaxial compression. High energy dissipation and shapemore » integrity at large imposed strains (up to 60%) have also been observed in these hierarchical honeycombs under cyclic loading. Experimental and numerical studies suggest that these anomalous mechanical behaviors are attributed to the introduction of a structural hierarchy, intrinsically controlled by the cell wall slenderness of the triangular lattice and by the shape memory effect induced by the thermal and mechanical compressive treatment.« less

Encapsulation of an adamantane-doxorubicin prodrug in pH-responsive polysaccharide capsules for controlled release.

PubMed

Luo, Guo-Feng; Xu, Xiao-Ding; Zhang, Jing; Yang, Juan; Gong, Yu-Hui; Lei, Qi; Jia, Hui-Zhen; Li, Cao; Zhuo, Ren-Xi; Zhang, Xian-Zheng

2012-10-24

Supramolecular microcapsules (SMCs) with the drug-loaded wall layers for pH-controlled drug delivery were designed and prepared. By using layer-by-layer (LbL) technique, the SMCs were constructed based on the self-assembly between polyaldenhyde dextran-graft-adamantane (PAD-g-AD) and carboxymethyl dextran-graft-β-CD (CMD-g-β-CD) on CaCO(3) particles via host-guest interaction. Simultaneously, adamantine-modified doxorubicin (AD-Dox) was also loaded on the LbL wall via host-guest interaction. The in vitro drug release study was carried out at different pHs. Because the AD groups were linked with PAD (PAD-g-AD) or Dox (AD-Dox) by pH-cleavable hydrazone bonds, AD moieties can be removed under the weak acidic condition, leading to destruction of SMCs and release of Dox. The pH-controlled drug release can enhance the uptake by tumor cells and thus achieve improved cancer therapy efficiency.

Physical consequences of the mitochondrial targeting of single-walled carbon nanotubes probed computationally

NASA Astrophysics Data System (ADS)

Chistyakov, V. A.; Zolotukhin, P. V.; Prazdnova, E. V.; Alperovich, I.; Soldatov, A. V.

2015-06-01

Experiments by F. Zhou and coworkers (2010) [16] showed that mitochondria are the main target of the cellular accumulation of single-walled carbon nanotubes (SWCNTs). Our in silico experiments, based on geometrical optimization of the system consisting of SWCNT+proton within Density Functional Theory, revealed that protons can bind to the outer side of SWCNT so generating a positive charge. Calculation results allow one to propose the following mechanism of SWCNTs mitochondrial targeting. SWCNTs enter the space between inner and outer membranes of mitochondria, where the excess of protons has been formed by diffusion. In this compartment SWCNTs are loaded with protons and acquire positive charges distributed over their surface. Protonation of hydrophobic SWCNTs can also be carried out within the mitochondrial membrane through interaction with the protonated ubiquinone. Such "charge loaded" particles can be transferred as "Sculachev ions" through the inner membrane of the mitochondria due to the potential difference generated by the inner membrane. Physiological consequences of the described mechanism are discussed.

An automated spring-loaded needle for endoscopic ultrasound-guided abdominal paracentesis in cancer patients

PubMed Central

Suzuki, Rei; Irisawa, Atsushi; Bhutani, Manoop S; Hikichi, Takuto; Takagi, Tadayuki; Shibukawa, Goro; Sato, Ai; Sato, Masaki; Ikeda, Tsunehiko; Watanabe, Ko; Nakamura, Jun; Annangi, Srinadh; Tasaki, Kazuhiro; Obara, Katsutoshi; Ohira, Hiromasa

2014-01-01

AIM: To evaluate the feasibility of using an automated spring-loaded needle device for endoscopic ultrasound (EUS)-guided abdominal paracentesis (EUS-P) to see if this would make it easier to puncture the mobile and lax gastric wall for EUS-P. METHODS: The EUS database and electronic medical records at Fukushima Medical University Hospital were searched from January 2001 to April 2011. Patients with a history of cancer and who underwent EUS-P using an automated spring-loaded needle device with a 22-gauge puncture needle were included. The needle was passed through the instrument channel and advanced through the gastrointestinal wall under EUS guidance into the echo-free space in the abdominal cavity and ascitic fluid was collected. The confirmed diagnosis of malignant ascites included positive cytology and results from careful clinical observation for at least 6 mo in patients with negative cytology. The technical success rate, cytology results and complications were evaluated. RESULTS: We found 11 patients who underwent EUS-P with an automated spring-loaded needle device. In 4 cases, ascites was revealed only with EUS but not in other imaging modalities. EUS-P was done in 7 other cases because there was minimal ascitic fluid and no safe window for percutaneous abdominal aspiration. Ascitic fluid was obtained in all cases by EUS-P. The average amount aspirated was 14.1 mL (range 0.5-38 mL) and that was sent for cytological exam. The etiology of ascitic fluid was benign in 5 patients and malignant in 6. In all cases, ascitic fluid was obtained with the first needle pass. No procedure-related adverse effects occurred. CONCLUSION: EUS-P with an automated spring-loaded needle device is a feasible and safe method for ascites evaluation. PMID:24567793

Effect of resin coating and occlusal loading on microleakage of Class II computer-aided design/computer-aided manufacturing fabricated ceramic restorations: a confocal microscopic study.

PubMed

Kitayama, Shuzo; Nasser, Nasser A; Pilecki, Peter; Wilson, Ron F; Nikaido, Toru; Tagami, Junji; Watson, Timothy F; Foxton, Richard M

2011-05-01

To evaluate the effect of resin coating and occlusal loading on microleakage of class II computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic restorations. Molars were prepared for an mesio-occlusal-distal (MOD) inlay and were divided into two groups: non-coated (controls); and resin-coated, in which the cavity was coated with a combination of a dentin bonding system (Clearfil Protect Bond) and a flowable resin composite (Clearfil Majesty Flow). Ceramic inlays were fabricated using the CAD/CAM technique (CEREC 3) and cemented with resin cement (Clearfil Esthetic Cement). After 24 h of water storage, the restored teeth in each group were divided into two subgroups: unloaded or loaded with an axial force of 80 N at a rate of 2.5 cycles/s for 250,000 cycles while stored in water. After immersion in 0.25% Rhodamine B solution, the teeth were sectioned bucco-lingually at the mesial and distal boxes. Tandem scanning confocal microscopy (TSM) was used for evaluation of microleakage. The locations of the measurements were assigned to the cavity walls and floor. Loading did not have a significant effect on microleakage in either the resin-coated or non-coated group. Resin coating significantly reduced microleakage regardless of loading. The cavity floor exhibited greater microleakage compared to the cavity wall. TSM observation also revealed that microleakage at the enamel surface was minimal regardless of resin coating. In contrast, non-coated dentin showed extensive leakage, whereas resin-coated dentin showed decreased leakage. Resin coating with a combination of a dentin-bonding system and a flowable resin composite may be indicated prior to impression-taking when restoring teeth with CAD/CAM ceramic inlays in order to reduce microleakage at the tooth-resin interface.

Full-scale S-76 rotor performance and loads at low speeds in the NASA Ames 80- by 120-Foot Wind Tunnel. Vol. 1

NASA Technical Reports Server (NTRS)

Shinoda, Patrick M.

1996-01-01

A full-scale helicopter rotor test was conducted in the NASA Ames 80- by 120-Foot Wind Tunnel with a four-bladed S-76 rotor system. Rotor performance and loads data were obtained over a wide range of rotor shaft angles-of-attack and thrust conditions at tunnel speeds ranging from 0 to 100 kt. The primary objectives of this test were (1) to acquire forward flight rotor performance and loads data for comparison with analytical results; (2) to acquire S-76 forward flight rotor performance data in the 80- by 120-Foot Wind Tunnel to compare with existing full-scale 40- by 80-Foot Wind Tunnel test data that were acquired in 1977; (3) to evaluate the acoustic capability of the 80- by 120- Foot Wind Tunnel for acquiring blade vortex interaction (BVI) noise in the low speed range and compare BVI noise with in-flight test data; and (4) to evaluate the capability of the 80- by 120-Foot Wind Tunnel test section as a hover facility. The secondary objectives were (1) to evaluate rotor inflow and wake effects (variations in tunnel speed, shaft angle, and thrust condition) on wind tunnel test section wall and floor pressures; (2) to establish the criteria for the definition of flow breakdown (condition where wall corrections are no longer valid) for this size rotor and wind tunnel cross-sectional area; and (3) to evaluate the wide-field shadowgraph technique for visualizing full-scale rotor wakes. This data base of rotor performance and loads can be used for analytical and experimental comparison studies for full-scale, four-bladed, fully articulated rotor systems. Rotor performance and structural loads data are presented in this report.

Cavitation erosion prediction based on analysis of flow dynamics and impact load spectra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mihatsch, Michael S., E-mail: michael.mihatsch@aer.mw.tum.de; Schmidt, Steffen J.; Adams, Nikolaus A.

2015-10-15

Cavitation erosion is the consequence of repeated collapse-induced high pressure-loads on a material surface. The present paper assesses the prediction of impact load spectra of cavitating flows, i.e., the rate and intensity distribution of collapse events based on a detailed analysis of flow dynamics. Data are obtained from a numerical simulation which employs a density-based finite volume method, taking into account the compressibility of both phases, and resolves collapse-induced pressure waves. To determine the spectrum of collapse events in the fluid domain, we detect and quantify the collapse of isolated vapor structures. As reference configuration we consider the expansion ofmore » a liquid into a radially divergent gap which exhibits unsteady sheet and cloud cavitation. Analysis of simulation data shows that global cavitation dynamics and dominant flow events are well resolved, even though the spatial resolution is too coarse to resolve individual vapor bubbles. The inviscid flow model recovers increasingly fine-scale vapor structures and collapses with increasing resolution. We demonstrate that frequency and intensity of these collapse events scale with grid resolution. Scaling laws based on two reference lengths are introduced for this purpose. We show that upon applying these laws impact load spectra recorded on experimental and numerical pressure sensors agree with each other. Furthermore, correlation between experimental pitting rates and collapse-event rates is found. Locations of high maximum wall pressures and high densities of collapse events near walls obtained numerically agree well with areas of erosion damage in the experiment. The investigation shows that impact load spectra of cavitating flows can be inferred from flow data that captures the main vapor structures and wave dynamics without the need for resolving all flow scales.« less

Single Additive Enables 3D Printing of Highly Loaded Iron Oxide Suspensions.

PubMed

Hodaei, Amin; Akhlaghi, Omid; Khani, Navid; Aytas, Tunahan; Sezer, Dilek; Tatli, Buse; Menceloglu, Yusuf Z; Koc, Bahattin; Akbulut, Ozge

2018-03-21

A single additive, a grafted copolymer, is designed to ensure the stability of suspensions of highly loaded iron oxide nanoparticles (IOPs) and to facilitate three-dimensional (3D) printing of these suspensions in the filament form. This poly (ethylene glycol)-grafted copolymer of N-[3(dimethylamino)propyl]methacrylamide and acrylic acid harnesses both electrostatic and steric repulsion to realize an optimum formulation for 3D printing. When used at 1.15 wt % (by the weight of IOPs), the suspension attains ∼81 wt % solid loading-96% of the theoretical limit as calculated by the Krieger-Dougherty equation. Rectangular, thick-walled toroidal, and thin-walled toroidal magnetic cores and a porous lattice structure are fabricated to demonstrate the utilization of this suspension as an ink for 3D printing. The electrical and magnetic properties of the magnetic cores are characterized through impedance spectroscopy (IS) and vibrating sample magnetometry (VSM), respectively. The IS indicates the possibility of utilizing wire-wound 3D printed cores as the inductive coils. The VSM verifies that the magnetic properties of IOPs before and after the ink formulation are kept almost unchanged because of the low dosage of the additive. This particle-targeted approach for the formulation of 3D printing inks allows embodiment of a fully aqueous system with utmost target material content.

On the evolutionary advantage of multi-cusped teeth

PubMed Central

Bush, Mark B.; Barani, Amir; Lawn, Brian R.

2016-01-01

A hallmark of mammalian evolution is a progressive complexity in postcanine tooth morphology. However, the driving force for this complexity remains unclear: whether to expand the versatility in diet source, or to bolster tooth structural integrity. In this study, we take a quantitative approach to this question by examining the roles of number, position and height of multiple cusps in determining sustainable bite forces. Our approach is to use an extended finite-element methodology with due provision for step-by-step growth of an embedded crack to determine how fracture progresses with increasing occlusal load. We argue that multi-cusp postcanine teeth are well configured to withstand high bite forces provided that multiple cusps are contacted simultaneously to share the load. However, contact on a single near-wall cusp diminishes the strength. Location of the load points and cusp height, rather than cusp number or radius, are principal governing factors. Given these findings, we conclude that while complex tooth structures can enhance durability, increases in cusp number are more likely to be driven by the demands of food manipulation. Structural integrity of complex teeth is maintained when individual cusps remain sufficiently distant from the side walls and do not become excessively tall relative to tooth width. PMID:27558851

Stress-intensity factors for circumferential surface cracks in pipes and rods under tension and bending loads

NASA Technical Reports Server (NTRS)

Raju, I. S.; Newman, J. C., Jr.

1985-01-01

The purpose of this paper is to present stress-intensity factors for a wide range of nearly semi-elliptical surface cracks in pipes and rods. The configurations were subjected to either remote tension or bending loads. For pipes, the ratio of crack depth to crack length (a/c) ranged from 0.6 to 1; the ratio of crack depth to wall thickness (a/t) ranged from 0.2 to 0.8; and the ratio of internal radius to wall thickness (R/t) ranged from 1 to 10. For rods, the ratio of crack depth to crack length also ranged from 0.6 to 1; and the ratio of crack depth to rod diameter (a/D) ranged from 0.05 to 0.35. These particular crack configurations were chosen to cover the range of crack shapes (a/c) that have been observed in experiments conducted on pipes and rods under tension and bending fatigue loads. The stress-intensity factors were calculated by a three-dimensional finite-element method. The finite-element models employed singularity elements along the crack front and linear-strain elements elsewhere. The models had about 6500 degrees of freedom. The stress-intensity factors were evaluated using a nodal-force method.

Synergistic Enhancement of Antitumor Efficacy by PEGylated Multi-walled Carbon Nanotubes Modified with Cell-Penetrating Peptide TAT

NASA Astrophysics Data System (ADS)

Hu, Shanshan; Wang, Tong; Pei, Xibo; Cai, He; Chen, Junyu; Zhang, Xin; Wan, Qianbing; Wang, Jian

2016-10-01

In the present study, a cell-penetrating peptide, the transactivating transcriptional factor (TAT) domain from HIV, was linked to PEGylated multi-walled carbon nanotubes (MWCNTs) to develop a highly effective antitumor drug delivery system. FITC was conjugated on MWCNTs-polyethylene glycol (PEG) and MWCNTs-PEG-TAT to provide fluorescence signal for tracing the cellular uptake of the nanocarrier. After loaded with an anticancer agent, doxorubicin (DOX) via π - π stacking interaction, the physicochemical characteristics, release profile and biological evaluation of the obtained nano-sized drug carrier were investigated. The DOX loaded MWCNTs-PEG and MWCNTs-PEG-TAT drug carriers both displayed appropriate particle size, excellent stability, high drug loading, and pH-dependent drug release profile. Nevertheless, compared with DOX-MWCNTs-PEG, DOX-MWCNTs-PEG-TAT showed improved cell internalization, intracellular distribution and potentiated anticancer efficacy due to the TAT-mediated membrane translocation, endosomal escape and nuclear targeting. Furthermore, the therapeutic efficacy of DOX was not compromised after being conjugated with MWCNTs-PEG-TAT and the proposed nanocarrier was also confirmed to have a good biocompatibility. In conclusion, our results suggested that the unique combination of TAT and MWCNTs as a multifunctional drug delivery system might be a powerful tool for improved anticancer drug development.

Pharmacokinetic Evaluation of Two Paclitaxel-Coated Balloons with Different Drug Load in a Short-Term Porcine Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abadal, J. M., E-mail: jmabadal@yahoo.es; Vazquez, Esther, E-mail: esva9999@gmail.com; Morales, Miguel, E-mail: miguel.moralesg@gmail.com

PurposeThe aim of the study was to evaluate the pharmacokinetics and tissue absorption of 2 paclitaxel (PTX) drug-coated balloons (DCB) using different drug loads in a porcine-injured iliac artery model.Materials and MethodsTwenty-eight pigs were randomized into 2 groups. In group B1, angioplasty was performed with a 1.0 µg/mm{sup 2} DCB with PTX and in group B3, with a 3.0 µg/mm{sup 2} DCB with PTX. An overstretched model of the iliac artery was used for angioplasty under fluoroscopy. Blood and vessel wall PTX were measured with liquid-chromatography mass spectrometry at 1, 5, 30 min, 1, 7, and 28 days. Remaining drug in the balloon wasmore » analyzed.ResultsMean PTX in blood was significantly higher in the group B3 0.269 ± 0.085 µg/ml compared with the B1 0.218 ± 0.085 µg/ml; p = 0.01. Peak blood PTX concentration was detected at 1 min, and PTX was undetectable 24 h post-angioplasty. There were no statistically significant differences in the mean arterial wall concentration from the treated iliac artery between group-B1 (15.24 ± 21.29 ng/mg) and B3 (15.68 ± 16.33 ng/mg), or in the PTX wall concentration measured at different time points. Mean remaining drug in assayed balloons was lower for group-B1 and represented 8 % of the initial dose.ConclusionsBlood PTX was higher when using 3.0 µg/mm{sup 2} DCB, with a peak drug concentration at 1-min, although the drug was undetectable at 24 h, independently of the loading dose. This study demonstrates no difference in arterial wall uptake of a low dose DCB (1.0 µg/mm{sup 2}), when compared to a common dose DCB (3.0 µg/mm{sup 2}) suggesting that the dose of drug in the DCB could be reduced obtaining a similar clinical effect.« less

Load transfer of nanocomposite film on aluminum substrate.

PubMed

Her, Shiuh-Chuan; Chien, Pao-Chu

2018-01-01

Nanocomposite films have attracted much attention in recent years. Depending on the composition of the film and fabrication method, a large range of applications has been employed for nanocomposite films. In this study, nanocomposite films reinforced with multi-walled carbon nanotubes (MWCNTs) were deposited on the aluminum substrate through hot press processing. A shear lag model and Euler beam theory were employed to evaluate the stress distribution and load carrying capability of the nanocomposite film subjected to tensile load and bending moment. The influence of MWCNT on the Young's modulus and load carrying capability of the nanocomposite film was investigated through a parametric study. The theoretical predictions were verified by comparison with experimental tests. A close agreement with difference less than 6% was achieved between the theoretical prediction and experimental measurements. The Young's modulus and load transfer of the nanocomposite film reinforced with MWCNTs increases with the increase of the MWCNT loading. Compared to the neat epoxy film, nanocomposite film with 1 wt % of MWCNT exhibits an increase of 20% in both the Young's modulus and load carrying capability.

Microwave fidelity studies by varying antenna coupling

NASA Astrophysics Data System (ADS)

Köber, B.; Kuhl, U.; Stöckmann, H.-J.; Gorin, T.; Savin, D. V.; Seligman, T. H.

2010-09-01

The fidelity decay in a microwave billiard is considered, where the coupling to an attached antenna is varied. The resulting quantity, coupling fidelity, is experimentally studied for three different terminators of the varied antenna: a hard-wall reflection, an open wall reflection, and a 50Ω load, corresponding to a totally open channel. The model description in terms of an effective Hamiltonian with a complex coupling constant is given. Quantitative agreement is found with the theory obtained from a modified VWZ approach [J. J. M. Verbaarschot , Phys. Rep. 129, 367 (1985)10.1016/0370-1573(85)90070-5].

Nanofilter platform based on functionalized carbon nanotubes for adsorption and elimination of Acrolein, a toxicant in cigarette smoke

NASA Astrophysics Data System (ADS)

Yoosefian, Mehdi; Pakpour, Atef; Etminan, Nazanin

2018-06-01

This paper discusses the use of carboxylated single-walled carbon nanotube as a general nanofilter platform for the removal of acrolein carcinogen from cigarette smoke. The analyses carried out in the detailed study of the electronic and structural effects of the adsorption of acrolein onto COOH loaded on single-walled carbon nanotube under the density functional theory framework. The results of Bader theory of atoms in molecules, natural bond orbital, molecular potential electron surface and density of state confirm the potential application of the suggested nanofilter platform.

Foam rigidized inflatable structural assemblies

NASA Technical Reports Server (NTRS)

Tinker, Michael L. (Inventor); Schnell, Andrew R. (Inventor)

2010-01-01

An inflatable and rigidizable structure for use as a habitat or a load bearing structure is disclosed. The structure consists of an outer wall and an inner wall defining a containment member and a bladder. The bladder is pressurized to erect the structure from an initially collapsed state. The containment member is subsequently injected with rigidizable fluid through an arrangement of injection ports. Exhaust gases from the curing rigidizable fluid are vented through an arrangement of exhaust ports. The rate of erection can be controlled by frictional engagement with a container or by using a tether. A method for fabricating a tubular structure is disclosed.

User’s Guide: Computer Program for Design or Investigation of Orthogonal Culverts (CORTCUL).

DTIC Science & Technology

1981-03-01

Groundwater level, GWATEL (Figure 1), may be at any elevation. Groundwater has the dual effect of altering the effective unit weight of submerged soil...vicii . ,t the joints. I txible and rinid m- mbr ri ,r.s tat I, ; .-i i I l;!t tt, I J!, | II "I C’ C’ 0 C’ C) _______ I 0 31 Figure 12. The lengths of...exterior walls 5. A trapezoidal variation of horizontal distributed load is pro- duced on vertical exterior walls by moist soil, submerged soil, and wate

Development of sensitized pick coal interface detector system

NASA Technical Reports Server (NTRS)

Burchill, R. F.

1982-01-01

One approach for detection of the coal interface is measurement of pick cutting loads and shock through the use of pick strain gage load cells and accelerometers. The cutting drum of a long wall mining machine contains a number of cutting picks. In order to measure pick loads and shocks, one pick was instrumented and telemetry used to transmit the signals from the drum to an instrument-type tape recorder. A data system using FM telemetry was designed to transfer cutting bit load and shock information from the drum of a longwall shearer coal mining machine to a chassis mounted data recorder. The design of components in the test data system were finalized, the required instruments were assembled, the instrument system was evaluated in an above-ground simulation test, and an underground test series to obtain tape recorded sensor data was conducted.

Failure Investigation & Design Optimization of a Photo-Multiplier Tube Assembly Under Thermal Loading

NASA Technical Reports Server (NTRS)

Dahya, Kevin

2004-01-01

Analysis of GLAST ACD Photo-Multiplier Tube (PMT) assembly under thermal loading demonstrates that the glass tube experiences high stresses due to Coefficient of Thermal Expansion mismatch, as well as increased stress due to high stiffness and incompressibility of potting compound. Further investigation shows adverse loading effects due to the magnetic shield, a thin piece of steel wrapped around the PMT. This steel, Mu Metal, contained an overlap region that directly attributed to crack propagation in the outside surface of the tube. Sensitivities to different configurations were studied to reduce the stress and provide a more uniform loading throughout the PMT to ensure mission success. Studies indicate substituting a softer and more compressible potting compound and moving the Mu metal from the glass tube to the outside wall of the aluminum housing yields lower stress.

Deep drawing of 304 L Steel Sheet using Vegetable oils as Forming Lubricants

NASA Astrophysics Data System (ADS)

Shashidhara, Y. M.; Jayaram, S. R.

2012-12-01

The study involves the evaluation of deep drawing process using two non edible oils, Pongam (Pongammia pinnata) and Jatropha (Jatropha carcass) as metal forming lubricants. Experiments are conducted on 304L steel sheets under the raw and modified oils with suitable punch and die on a hydraulic press of 200 ton capacity. The punch load, draw-in-length and wall thickness distribution for deep drawn cups are observed. The drawn cups are scanned using laser scanning technique and 3D models are generated using modeling package. The wall thickness profiles of cups at different sections (or height) are measured using CAD package. Among the two raw oils, the drawn cups under Jatropha oil, have uniform wall thickness profile compared to Pongam oil. Uneven flow of material and cup rupturing is observed under methyl esters of Pongam and Jatropha oil lubricated conditions. However, the results are observed under epoxidised Jatropha oil with uniform metal flow and wall thicknesses compared to mineral and other versions of vegetable oils.

Electric field mediated loading of macromolecules in intact yeast cells is critically controlled at the wall level.

PubMed

Ganeva, V; Galutzov, B; Teissié, J

1995-12-13

The mechanism of electric field mediated macromolecule transfer inside an intact yeast cell was investigated by observing, under a microscope, the fluorescence associated to cells after pulsation in a buffer containing two different hydrophilic fluorescent dyes. In the case of a small probe such as propidium iodide, a long lived permeabilized state was induced by the field as classically observed on wall free systems. Penetration of a 70 kDa FITC dextran was obtained only by using drastic conditions and only a very limited number of yeast cells which took up macromolecules remained viable. Most dextrans were trapped in the wall. A dramatic improvement in transfer of dextrans was observed when the cells were treated by dithiothreitol before pulsation. A cytoplasmic protein leakage was detected after the electric treatment suggesting that an irreversible damage took place in the walls of many pulsed cells. Electroloading of macromolecules in intact yeast cells appears to be controlled by a field induced short lived alteration of the envelope organization.

Cellulose-pectin composite hydrogels: Intermolecular interactions and material properties depend on order of assembly.

PubMed

Lopez-Sanchez, Patricia; Martinez-Sanz, Marta; Bonilla, Mauricio R; Wang, Dongjie; Gilbert, Elliot P; Stokes, Jason R; Gidley, Michael J

2017-04-15

Plant cell walls have a unique combination of strength and flexibility however, further investigations are required to understand how those properties arise from the assembly of the relevant biopolymers. Recent studies indicate that Ca 2+ -pectates can act as load-bearing components in cell walls. To investigate this proposed role of pectins, bioinspired wall models were synthesised based on bacterial cellulose containing pectin-calcium gels by varying the order of assembly of cellulose/pectin networks, pectin degree of methylesterification and calcium concentration. Hydrogels in which pectin-calcium assembly occurred prior to cellulose synthesis showed evidence for direct cellulose/pectin interactions from small-angle scattering (SAXS and SANS), had the densest networks and the lowest normal stress. The strength of the pectin-calcium gel affected cellulose structure, crystallinity and material properties. The results highlight the importance of the order of assembly on the properties of cellulose composite networks and support the role of pectin in the mechanics of cell walls. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exterior Insulation Implications for Heating and Cooling Systems in Cold Climates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herk, Anastasia; Poerschke, Andrew

The New York State Energy Research and Development Authority (NYSERDA) is interested in finding cost-effective solutions for deep energy retrofits (DERs) related to exterior wall insulation in a cold climate, with targets of 50% peak load reduction and 50% space conditioning energy savings. The U.S. Department of Energy Building America team, IBACOS, in collaboration with GreenHomes America, Inc. (GHA), was contracted by NYSERDA to research exterior wall insulation solutions. In addition to exterior wall insulation, the strategies included energy upgrades where needed in the attic, mechanical and ventilation systems, basement, band joist, walls, and floors. Under Building America, IBACOS ismore » studying the impact of a “thermal enclosure” DER on the sizing of the space conditioning system and the occupant comfort if the thermal capacity of the heating and cooling system is dramatically downsized without any change in the existing heating and cooling distribution system (e.g., size, tightness and supply outlet configurations).« less

Structural and oxidative stabilization of spray dried fish oil microencapsulates with gum arabic and sage polyphenols: Characterization and release kinetics.

PubMed

Binsi, P K; Nayak, Natasha; Sarkar, P C; Jeyakumari, A; Muhamed Ashraf, P; Ninan, George; Ravishankar, C N

2017-03-15

The synergistic efficacy of gum arabic and sage polyphenols in stabilising capsule wall and protecting fish oil encapsulates from heat induced disruption and oxidative deterioration during spray drying was assessed. The emulsions prepared with sodium caseinate as wall polymer, gum arabic as wall co-polymer and sage extract as wall stabiliser was spray dried using a single fluid nozzle. Fish oil encapsulates stabilised with gum arabic and sage extract (SOE) exhibited significantly higher encapsulation efficiency compared to encapsulates containing gum arabic alone (FOE). Scanning electron microscopic and atomic force microscopic images revealed uniform encapsulates with good sphericity and smooth surface for SOE, compared to FOE powder. In vitro oil release of microencapsulates indicated negligible oil release in buffered saline whereas more than 80% of the oil loaded in encapsulates were released in simulated GI fluids. The encapsulates containing sage extract showed a lower rate of lipid oxidation during storage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dissecting the molecular mechanism underlying the intimate relationship between cellulose microfibrils and cortical microtubules.

PubMed

Lei, Lei; Li, Shundai; Bashline, Logan; Gu, Ying

2014-01-01

A central question in plant cell development is how the cell wall determines directional cell expansion and therefore the final shape of the cell. As the major load-bearing component of the cell wall, cellulose microfibrils are laid down transversely to the axis of elongation, thus forming a spring-like structure that reinforces the cell laterally and while favoring longitudinal expansion in most growing cells. Mounting evidence suggests that cortical microtubules organize the deposition of cellulose microfibrils, but the precise molecular mechanisms linking microtubules to cellulose organization have remained unclear until the recent discovery of cellulose synthase interactive protein 1 , a linker protein between the cortical microtubules and the cellulose biosynthesizing machinery. In this review, we will focus on the intimate relationship between cellulose microfibrils and cortical microtubules, in particular, we will discuss microtubule arrangement and cell wall architecture, the linkage between cellulose synthase complexes and microtubules, and the feedback mechanisms between cell wall and microtubules.

Energy Control Systems: Energy Savings.

ERIC Educational Resources Information Center

School Business Affairs, 1980

1980-01-01

The installation of proper control systems is estimated as saving up to 25 percent of the energy used in schools. Other potential energy-saving areas are transmission (heat loss or gain through walls, especially ceilings); internal load (heat from students, lights, and machinery); ventilation; and equipment maintenance. (Author/MLF)

Automatic Test, Configuration, and Repair of Cellular Arrays

DTIC Science & Technology

1975-06-01

one cell to loed any good cell that is not walled off by flawed cells. The loading Information which the computer sends to the array may select one...to loed that cell’s loader and function-specificatioi state bits. After the cell is loaded» it« loader state bits may specify which of the cell’s...Mechanism With Options FUNCTION-SPEC, STATE BITS D.OUT INO INI OUTO 0UT1 LOO LO PAGE 99 LOADER TIP BITS CHANGER ill LSTA S.U.IN S.R.IN

Simple quasi-analytical holonomic homogenization model for the non-linear analysis of in-plane loaded masonry panels: Part 1, meso-scale

NASA Astrophysics Data System (ADS)

Milani, G.; Bertolesi, E.

2017-07-01

A simple quasi analytical holonomic homogenization approach for the non-linear analysis of masonry walls in-plane loaded is presented. The elementary cell (REV) is discretized with 24 triangular elastic constant stress elements (bricks) and non-linear interfaces (mortar). A holonomic behavior with softening is assumed for mortar. It is shown how the mechanical problem in the unit cell is characterized by very few displacement variables and how homogenized stress-strain behavior can be evaluated semi-analytically.

The Strength of Thin-wall Cylinders of D Cross Section in Combined Pure Bending and Torsion

NASA Technical Reports Server (NTRS)

Sherwood, A W

1943-01-01

The results of tests of 56 cylinders of D cross section conducted in the Aeronautical Laboratory of the University of Maryland are presented in this report. These cylinders were subjected to pure bending and torsional moments of varying proportions to give the strength under combined loading conditions. The average buckling stress of these cylinders has been related to that of circumscribing circular cylinders for conditions of pure torsion and pure bending and the equation of the interaction curve has been determined for conditions of combined loading.

Recent radial turbine research at the NASA Lewis Research Center

NASA Technical Reports Server (NTRS)

Rohlik, H. E.; Kofskey, M. G.

1971-01-01

The high efficiencies of small radial turbines led to their application in space power systems and numerous APU and shaft power engines. Experimental and analytical work associated with these systems included examination of blade-shroud clearance, blade loading, and exit diffuser design. Results indicate high efficiency over a wide range of specific speed and also insensitivity to clearance and blade loading in the radial part of the rotor. The exit diffuser investigation indicated that a conventional conical outer wall may not provide the velocity variation consistent with minimum overall diffuser loss.

Large-deflection-theory Analysis of the Effect of Web Initial Curvature on the Ultimate Strength of Steel Plate Girder

NASA Astrophysics Data System (ADS)

Kala, Jiří; Kala, Zdeněk

2011-09-01

The objective of the paper is to analyze the influence of initial imperfections on the behaviour of thin-walled girders welded of slender plate elements. In parallel with experiments, one of the ultimate load tests was computer modelled. In so doing, the girder was modelled, using the geometrically and materially non-linear variant of the shell finite element method, by the ANSYS program. The shape changing during loading process is often accompanying with sudden "snap-through" i. e. rapid curvature change.

Mechanical signals in plant development: a new method for single cell studies

NASA Technical Reports Server (NTRS)

Lynch, T. M.; Lintilhac, P. M.

1997-01-01

Cell division, which is critical to plant development and morphology, requires the orchestration of hundreds of intracellular processes. In the end, however, cells must make critical decisions, based on a discrete set of mechanical signals such as stress, strain, and shear, to divide in such a way that they will survive the mechanical loads generated by turgor pressure and cell enlargement within the growing tissues. Here we report on a method whereby tobacco protoplasts swirled into a 1.5% agarose entrapment medium will survive and divide. The application of a controlled mechanical load to agarose blocks containing protoplasts orients the primary division plane of the embedded cells. Photoelastic analysis of the agarose entrapment medium can identify the lines of principal stress within the agarose, confirming the hypothesis that cells divide either parallel or perpendicular to the principal stress tensors. The coincidence between the orientation of the new division wall and the orientation of the principal stress tensors suggests that the perception of mechanical stress is a characteristic of individual plant cells. The ability of a cell to determine a shear-free orientation for a new partition wall may be related to the applied load through the deformation of the matrix material. In an isotropic matrix a uniaxial load will produce a rotationally symmetric strain field, which will define a shear-free plane. Where high stress intensities combine with the loading geometry to produce multiaxial loads there will be no axis of rotational symmetry and hence no shear free plane. This suggests that two mechanisms may be orienting the division plane, one a mechanism that works in rotationally symmetrical fields, yielding divisions perpendicular to the compressive tensor, parallel to the long axis of the cell, and one in asymmetric fields, yielding divisions parallel to the short axis of the cell and the compressive tensor.

Study on influence of three kinds of stress on crack propagation in butt welds of spiral coil waterwall for ultra supercritical boiler

NASA Astrophysics Data System (ADS)

Yan, Zhenrong; Si, Jun

2017-09-01

The spiral coil waterwall is the main pressure parts and the core functional components of Ultra Supercritical Boiler. In the process of operation, the spiral coil waterwall is under the combined action of welding residual stress, installation defects stress and working fluid stress, Cracks and crack propagation are easy to occur in butt welds with defects. In view of the early cracks in the butt welds of more T23 water cooled walls, in this paper, the influence of various stresses on the crack propagation in the butt welds of spiral coil waterwall was studied by numerical simulation. Firstly, the welding process of T23 water cooled wall tube was simulated, and the welding residual stress field was obtained. Then,on the basis, put the working medium load on the spiral coil waterwall, the supercoated stress distribution of the welding residual stress and the stress of the working medium is obtained. Considering the bending moment formed by stagger joint which is the most common installation defects, the stress field distribution of butt welds in T23 water-cooled wall tubes was obtained by applying bending moment on the basis of the stress field of the welding residual stress and the working medium stress. The results show that, the welding residual stress is small, the effect of T23 heat treatment after welding to improve the weld quality is not obvious; The working medium load plays a great role in the hoop stress of the water cooled wall tube, and promotes the cracks in the butt welds; The axial stress on the water cooled wall tube produced by the installation defect stress is obvious, the stagger joint, and other installation defects are the main reason of crack propagation of spiral coil waterwall. It is recommended that the control the bending moment resulting from the stagger joint not exceed 756.5 NM.

Evaluation of Terrestrial Laser Scanner Accuracy in the Control of Hydrotechnical Structures

NASA Astrophysics Data System (ADS)

Muszyński, Zbigniew; Rybak, Jarosław

2017-12-01

In many cases of monitoring or load testing of hydrotechnical structures, the measurement results obtained from dial gauges may be affected by random or systematic errors resulting from the instability of the reference beam. For example, the measurement of wall displacement or pile settlement may be increased (or decreased) by displacements of the reference beam due to ground movement. The application of surveying methods such as high-precision levelling, motorized tacheometry or even terrestrial laser scanning makes it possible to provide an independent reference measurement free from systematic errors. It is very important in the case of walls and piles embedded in the rivers, where the construction of reference structure is even more difficult than usually. Construction of an independent reference system is also complicated when horizontal testing of sheet piles or diaphragm walls are considered. In this case, any underestimation of the horizontal displacement of an anchored or strutted construction leads to an understated value of the strut's load. These measurements are even more important during modernization works and repairs of the hydrotechnical structures. The purpose of this paper is to discuss the possibilities of using modern measurement methods for monitoring of horizontal displacements of an excavation wall. The methods under scrutiny (motorized tacheometry and terrestrial laser scanning) have been compared to classical techniques and described in the context of their practical use on the example hydrotechnical structure. This structure was a temporary cofferdam made from sheet pile wall. The research continuously conducted at Wroclaw University of Science and Technology made it possible to collect and summarize measurement results and practical experience. This paper identifies advantages and disadvantages of both analysed methods and presents a comparison of obtained measurement results of horizontal displacements. In conclusion, some recommendations have been formulated, which are relevant from the point of view of engineering practice.

Quantification of the relative contribution of the different right ventricular wall motion components to right ventricular ejection fraction: the ReVISION method.

PubMed

Lakatos, Bálint; Tősér, Zoltán; Tokodi, Márton; Doronina, Alexandra; Kosztin, Annamária; Muraru, Denisa; Badano, Luigi P; Kovács, Attila; Merkely, Béla

2017-03-27

Three major mechanisms contribute to right ventricular (RV) pump function: (i) shortening of the longitudinal axis with traction of the tricuspid annulus towards the apex; (ii) inward movement of the RV free wall; (iii) bulging of the interventricular septum into the RV and stretching the free wall over the septum. The relative contribution of the aforementioned mechanisms to RV pump function may change in different pathological conditions.Our aim was to develop a custom method to separately assess the extent of longitudinal, radial and anteroposterior displacement of the RV walls and to quantify their relative contribution to global RV ejection fraction using 3D data sets obtained by echocardiography.Accordingly, we decomposed the movement of the exported RV beutel wall in a vertex based manner. The volumes of the beutels accounting for the RV wall motion in only one direction (either longitudinal, radial, or anteroposterior) were calculated at each time frame using the signed tetrahedron method. Then, the relative contribution of the RV wall motion along the three different directions to global RV ejection fraction was calculated either as the ratio of the given direction's ejection fraction to global ejection fraction and as the frame-by-frame RV volume change (∆V/∆t) along the three motion directions.The ReVISION (Right VentrIcular Separate wall motIon quantificatiON) method may contribute to a better understanding of the pathophysiology of RV mechanical adaptations to different loading conditions and diseases.

Effect of topography on wind turbine power and load fluctuations

NASA Astrophysics Data System (ADS)

Santoni, Christian; Ciri, Umberto; Leonardi, Stefano

2015-11-01

Onshore wind turbines produce more than 17 GW in the US, which constitutes 4 . 4 % of all the energy produced. Sites selection is mostly determined by the atmospheric conditions and the topographical characteristics of the region. While the effect of the atmospheric boundary layer had been widely studied, less attention has been given to the effect of the topography on the wind turbine aerodynamics. To address how the topography affects the flow, Large Eddy Simulations of the flow over a wind turbine placed over wavy wall are performed. The wavelength of the wavy terrain, λ, is 1 . 7 D where D is the turbine rotor diameter. Two different values of the height of the wavy wall, a / D = 0 . 05 and a / D = 0 . 10 have been considered. In addition, two positions of the turbine with respect to the wavy wall had been studied, on the crest and trough of the wavy wall and compared with a wind turbine over a flat wall. For the turbine located at the crest, the pressure gradient due to the wavy wall caused a recirculation behind the wind tower 2 . 5 D larger than that of the smooth wall. When placed at the trough of the wavy terrain, the favorable pressure gradient increases the wake velocity near the wall and promotes entrainment into the turbine wake. Numerical simulations were performed on XSEDE TACC, Grant CTS070066. This work was supported by the NSF, grant IIA-1243482 (WINDINSPIRE).

Wave trapping by dual porous barriers near a wall in the presence of bottom undulation

NASA Astrophysics Data System (ADS)

Kaligatla, R. B.; Manisha; Sahoo, T.

2017-09-01

Trapping of oblique surface gravity waves by dual porous barriers near a wall is studied in the presence of step type varying bottom bed that is connected on both sides by water of uniform depths. The porous barriers are assumed to be fixed at a certain distance in front of a vertical rigid wall. Using linear water wave theory and Darcy's law for flow past porous structure, the physical problem is converted into a boundary value problem. Using eigenfunction expansion in the uniform bottom bed region and modified mild-slope equation in the varying bottom bed region, the mathematical problem is handled for solution. Moreover, certain jump conditions are used to account for mass conservation at slope discontinuities in the bottom bed profile. To understand the effect of dual porous barriers in creating tranquility zone and minimum load on the sea wall, reflection coefficient, wave forces acting on the barrier and the wall, and surface wave elevation are computed and analyzed for different values of depth ratio, porous-effect parameter, incident wave angle, gap between the barriers and wall and slope length of undulated bottom. The study reveals that with moderate porosity and suitable gap between barriers and sea wall, using dual barriers an effective wave trapping system can be developed which will exert less wave force on the barriers and the rigid wall. The proposed wave trapping system is likely to be of immense help for protecting various facilities/ infrastructures in coastal environment.