Sample records for aluminum honeycomb core

  1. An examination of impact damage in glass-phenolic and aluminum honeycomb core composite panels

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.; Lance, D. G.; Hodge, A. J.

    1990-01-01

    An examination of low velocity impact damage to glass-phenolic and aluminum core honeycomb sandwich panels with carbon-epoxy facesheets is presented. An instrumented drop weight impact test apparatus was utilized to inflict damage at energy ranges between 0.7 and 4.2 joules. Specimens were checked for extent of damage by cross sectional examination. The effect of core damage was assessed by subjecting impact-damaged beams to four-point bend tests. Skin-only specimens (facings not bonded to honeycomb) were also tested for comparison purposes. Results show that core buckling is the first damage mode, followed by delaminations in the facings, matrix cracking, and finally fiber breakage. The aluminum honeycomb panels exhibited a larger core damage zone and more facing delaminations than the glass-phenolic core, but could withstand more shear stress when damaged than the glass-phenolic core specimens.

  2. Aluminum Honeycomb Characteristics in Dynamic Crush Environments

    SciTech Connect

    Bateman, Vesta I.; Swanson, Lloyd H.

    1999-07-01

    Fifteen aluminum honeycomb cubes (3 in.) have been crushed in the Mechanical Shock Laboratory's drop table testing machines. This report summarizes shock experiments with honeycomb densities of 22.1 pcf and 38.0 pcf and with crush weights of 45 lb, 168 lb, and 268 lb. The honeycomb samples were crushed in all three orientations, W, L, and T. Most of the experiments were conducted at an impact velocity of {approx}40 fps, but higher velocities of up to 90 fps were used for selected experiments. Where possible, multiple experiments were conducted for a specific orientation and density of the honeycomb samples. All results are for Hexcel honeycomb except for one experiment with Alcore honeycomb and have been evaluated for validity. This report contains the raw acceleration data measured on the top of the drop table carriage, pictures of the crushed samples, and normalized force-displacement curves for all fifteen experiments. These data are not strictly valid for material characteristics in L and T orientations because the cross-sectional area of the honeycomb changed (split) during the crush. However, these are the best data available at this time. These dynamic crush data do suggest a significant increase in crush strength to 8000 psi ({approximately} 25-30% increase) over quasi-static values of {approximately}6000 psi for the 38.0 pcf Hexcel Honeycomb in the T-orientation. An uncertainty analysis is included and estimates the error in these data.

  3. Aluminum core structures brazed without use of flux

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Aluminum alloy face sheets are brazed to aluminum alloy honeycomb cores without using corrosive flux by means of one or three methods. The completed brazed structure has the high-strength characteristics of heat treated aluminum alloys.

  4. The total hemispheric emissivity of painted aluminum honeycomb at cryogenic temperatures

    SciTech Connect

    Tuttle, J.; Canavan, E.; DiPirro, M.; Li, X. [NASA Goddard Space Flight Center, Code 552 Greenbelt, Maryland, 20771 (United States); Knollenberg, P. [Northrop Grumman Aerospace Systems Redondo Beach, CA 90278 (United States)

    2014-01-29

    NASA uses high-emissivity surfaces on deep-space radiators and thermal radiation absorbers in test chambers. Aluminum honeycomb core material, when coated with a high-emissivity paint, provides a lightweight, mechanically robust, and relatively inexpensive black surface that retains its high emissivity down to low temperatures. At temperatures below about 100 Kelvin, this material performs much better than the paint itself. We measured the total hemispheric emissivity of various painted honeycomb configurations using an adaptation of an innovative technique developed for characterizing thin black coatings. These measurements were performed from room temperature down to 30 Kelvin. We describe the measurement technique and compare the results with predictions from a detailed thermal model of each honeycomb configuration.

  5. Characterizing Facesheet/Core Disbonding in Honeycomb Core Sandwich Structure

    NASA Technical Reports Server (NTRS)

    Rinker, Martin; Ratcliffe, James G.; Adams, Daniel O.; Krueger, Ronald

    2013-01-01

    Results are presented from an experimental investigation into facesheet core disbonding in carbon fiber reinforced plastic/Nomex honeycomb sandwich structures using a Single Cantilever Beam test. Specimens with three, six and twelve-ply facesheets were tested. Specimens with different honeycomb cores consisting of four different cell sizes were also tested, in addition to specimens with three different widths. Three different data reduction methods were employed for computing apparent fracture toughness values from the test data, namely an area method, a compliance calibration technique and a modified beam theory method. The compliance calibration and modified beam theory approaches yielded comparable apparent fracture toughness values, which were generally lower than those computed using the area method. Disbonding in the three-ply facesheet specimens took place at the facesheet/core interface and yielded the lowest apparent fracture toughness values. Disbonding in the six and twelve-ply facesheet specimens took place within the core, near to the facesheet/core interface. Specimen width was not found to have a significant effect on apparent fracture toughness. The amount of scatter in the apparent fracture toughness data was found to increase with honeycomb core cell size.

  6. An experimental investigation of aluminum honeycomb as an energy absorber 

    E-print Network

    Bland, William Joseph

    1964-01-01

    TESTING IV. DYNAMIC TESTING . V. RESULTS. VI. APPLICATION VII, CONCLUSIONS AND RECOMMENDATIONS 18 21 LITERATURE CITED 22 APPENDIX. 23 L IS T 0 F PLAT E 8 Plate Page 1. Aluminum Honeycomb Nomenclature 2. , Bare Compression Test before Crushing... 3. Bare Compression Test after Crushing 4. Square Head Producing Shear and Compression 5. Steel Shaft Used in Dynamic Testing for Head Attachments 12 6 . Dynamic Test with G ircula r Head 7. Static Specimen Illustrating Shear of Cell Walls 2 8...

  7. Evaluation of Ceramic Honeycomb Core Compression Behavior at Room Temperature

    NASA Technical Reports Server (NTRS)

    Bird, Richard K.; Lapointe, Thomas S.

    2013-01-01

    Room temperature flatwise compression tests were conducted on two varieties of ceramic honeycomb core specimens that have potential for high-temperature structural applications. One set of specimens was fabricated using strips of a commercially-available thin-gage "ceramic paper" sheet molded into a hexagonal core configuration. The other set was fabricated by machining honeycomb core directly from a commercially available rigid insulation tile material. This paper summarizes the results from these tests.

  8. Graphite\\/epoxy honeycomb core sandwich permeability under mechanical loads

    Microsoft Academic Search

    David E. Glass; V. V. Raman; Venki S. Venkat; Sankara N. Sankaran

    1999-01-01

    The air permeability of two honeycomb core sandwich materials as a function of applied shear stress was characterized. The honeycomb core sandwich specimens were provided to Analytical Services and Materials, Inc. by The Boeing Company for evaluation. The core material for the test specimens was either Hexcel HRP-3\\/16-8.0 or DuPont Korex-1\\/8-4.5 and was nominally 1.27 cm (0.5 in.) thick. The

  9. Double-Lap Shear Test For Honeycomb Core

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Hodge, Andrew J.

    1992-01-01

    Double-lap test measures shear strength of panel made of honeycomb core with 8-ply carbon-fiber/epoxy face sheets. Developed to overcome three principal disadvantages of prior standard single-lap shear test: specimen had to be more than 17 in. long; metal face sheets had to be used; and test introduced torque, with consequent bending and peeling of face sheets and spurious tensile or compressive loading of honeycomb.

  10. Probabilistic nondestructive evaluation of bonded aluminum honeycomb structures

    NASA Astrophysics Data System (ADS)

    Schaefer, Lloyd A.

    1995-07-01

    Aluminum honeycomb panels fabricated in accordance with spacecraft fracture control guidelines must be evaluated to a 90/95 POD/CL (probability of detection/confidence) level for detection of the critical initial flaw (CIF) size. Severe weight limitations can drive the CIF to a size of one cell diameter, or smaller. Additionally, producibility (low or no type II errors) must be maintained, and inspection costs minimized. To assure these goals, a reliability demonstration program was undertaken on thin skin panels for the Space Station Electric Power System ORU (orbital replacement unit) enclosures. This paper examines the probabilistic NDE process in detail, including: analysis of the manufacturing methodology, expected flaw types, construction of the disbond flaw data base, and the subsequent evaluations and results using laser shearography. The experimental data is then reduced utilizing the statistical methodology outlined in a proposed military standard for NDE reliability demonstrations, and contrasted against conventional through transmission ultrasonic inspection. The effort revealed that substantial gains in system reliability and flaw type discrimination are possible with laser shearography, along with a nearly order of magnitude reduction in inspection time.

  11. Honeycomb Core Permeability Under Mechanical Loads

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Raman, V. V.; Venkat, Venki S.; Sankaran, Sankara N.

    1997-01-01

    A method for characterizing the air permeability of sandwich core materials as a function of applied shear stress was developed. The core material for the test specimens was either Hexcel HRP-3/16-8.0 and or DuPont Korex-1/8-4.5 and was nominally one-half inch thick and six inches square. The facesheets where made of Hercules' AS4/8552 graphite/epoxy (Gr/Ep) composites and were nominally 0.059-in. thick. Cytec's Metalbond 1515-3M epoxy film adhesive was used for co-curing the facesheets to the core. The permeability of the specimens during both static (tension) and dynamic (reversed and non-reversed) shear loads were measured. The permeability was measured as the rate of air flow through the core from a circular 1-in2 area of the core exposed to an air pressure of 10.0 psig. In both the static and dynamic testing, the Korex core experienced sudden increases in core permeability corresponding to a core catastrophic failure, while the URP core experienced a gradual increase in the permeability prior to core failure. The Korex core failed at lower loads than the HRP core both in the transverse and ribbon directions.

  12. Heat Transfer in Adhesively Bonded Honeycomb Core Panels

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran

    2001-01-01

    The Swann and Pittman semi-empirical relationship has been used as a standard in aerospace industry to predict the effective thermal conductivity of honeycomb core panels. Recent measurements of the effective thermal conductivity of an adhesively bonded titanium honeycomb core panel using three different techniques, two steady-state and one transient radiant step heating method, at four laboratories varied significantly from each other and from the Swann and Pittman predictions. Average differences between the measurements and the predictions varied between 17 and 61% in the temperature range of 300 to 500 K. In order to determine the correct values of the effective thermal conductivity and determine which set of the measurements or predictions were most accurate, the combined radiation and conduction heat transfer in the honeycomb core panel was modeled using a finite volume numerical formulation. The transient radiant step heating measurements provided the best agreement with the numerical results. It was found that a modification of the Swann and Pittman semi-empirical relationship which incorporated the facesheets and adhesive layers in the thermal model provided satisfactory results. Finally, a parametric study was conducted to investigate the influence of adhesive thickness and thermal conductivity on the overall heat transfer through the panel.

  13. Large inelastic response of unbonded metallic foam and honeycomb core sandwich panels to blast loading

    Microsoft Academic Search

    M. D. Theobald; G. S. Langdon; G. N. Nurick; S. Pillay; A. Heyns; R. P. Merrett

    2010-01-01

    Sandwich panels constructed from metallic face sheets with the core composed of an energy absorbing material, have shown potential as an effective blast resistant structure. In the present study, air-blast tests are conducted on sandwich panels composed steel face sheets with unbonded aluminium foam (Alporas, Cymat) or hexagonal honeycomb cores. Honeycomb cores with small and large aspect ratios are investigated.

  14. Performance of metallic honeycomb-core sandwich beams under shock loading

    E-print Network

    Hutchinson, John W.

    Performance of metallic honeycomb-core sandwich beams under shock loading H.J. Rathbun a , D honeycomb core sandwich and solid monolithic beams have been subjected to high-pressure, short. The experiments have been designed to achieve two objectives: (i) to demonstrate the benefits of sandwich

  15. A Model for Simulating the Response of Aluminum Honeycomb Structure to Transverse Loading

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.; Czabaj, Michael W.; Jackson, Wade C.

    2012-01-01

    A 1-dimensional material model was developed for simulating the transverse (thickness-direction) loading and unloading response of aluminum honeycomb structure. The model was implemented as a user-defined material subroutine (UMAT) in the commercial finite element analysis code, ABAQUS(Registered TradeMark)/Standard. The UMAT has been applied to analyses for simulating quasi-static indentation tests on aluminum honeycomb-based sandwich plates. Comparison of analysis results with data from these experiments shows overall good agreement. Specifically, analyses of quasi-static indentation tests yielded accurate global specimen responses. Predicted residual indentation was also in reasonable agreement with measured values. Overall, this simple model does not involve a significant computational burden, which makes it more tractable to simulate other damage mechanisms in the same analysis.

  16. Dynamic Crush Behaviors Of Aluminum Honeycomb Specimens Under Compression Dominant Inclined Loads

    SciTech Connect

    Hong, Sung-tae; Pan, Jwo; Tyan, Tau; Prasad, Priya

    2008-01-01

    The quasi-static and dynamic crush behaviors of aluminum 5052-H38 honeycomb specimens under out-of-plane inclined loads are investigated by experiments. Different types of honeycomb specimens were designed for crush tests under pure compressive and inclined loads with respect to the out-of-plane direction. A test fixture was designed for both quasi-static and dynamic crush tests under inclined loads. The results of the quasi-static crush tests indicate that the normal crush and shear strengths under inclined loads are consistent with the corresponding results under combined loads. The results of the dynamic crush tests indicate that as the impact velocity increases, the normal crush strength increases and the shear strength remains nearly the same. The trends of the normalized normal crush strengths under inclined loads for specimens with different in-plane orientation angles as functions of the impact velocity are very similar to each other. Based on the experimental results, a macroscopic yield criterion as a function of the impact velocity is proposed. The experimental results suggest that as the impact velocity increases, the shape of the macroscopic yield surface changes, or more specifically, the curvature of the yield surface increases near the pure compression state. The experimental results also show similar microscopic progressive folding mechanisms in honeycomb specimens under pure compressive and inclined loads. However, honeycomb specimens under inclined loads show inclined stacking patterns of folds due to the asymmetric location of horizontal plastic hinge lines.

  17. Evaluation of a bi-directional aluminum honeycomb impact limiter design

    SciTech Connect

    Doman, M.J.

    1995-12-01

    A 120 Ton shipping cask is being developed for the on-site shipment of dry spent fuel at the Idaho National Engineering Laboratory. Impact limiters were incorporated in the cask design to limit the inertial load of the package and its contents during the hypothetical 9-meter (30-foot) drop accident required by 10CFR71. The design process included: (1) a series of static and dynamic tests to determine the crush characteristics of the bi-directional aluminum honeycomb impact limiter material, (2) the development of an analytical model to predict the cask deceleration force as a function of impact limiter crush, and (3) a series of quarter scale model drop tests to qualify the analytical model. The scale model testing, performed at Sandia National Laboratory in Albuquerque, New Mexico, revealed several design aspects which should be considered in developing bi-directional aluminum honeycomb impact limiters and several other design aspects which should be considered for impact limiter designs in general.

  18. Mode I Toughness Measurements of Core/Facesheet Bonds in Honeycomb Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Ratcliffe, James G.

    2006-01-01

    Composite sandwich structures will be used in many future applications in aerospace, marine and offshore industries due to the fact that the strength and stiffness to mass ratios surpass any other structural type. Sandwich structure also offers advantages over traditional stiffened panels such as ease of manufacturing and repair. During the last three decades, sandwich structure has been used extensively for secondary structure in aircraft (fuselage floors, rudders and radome structure). Sandwich structure is also used as primary structure in rotorcraft, the most common example being the trailing edge of rotor blades. As with other types of composite construction, sandwich structure exhibits several types of failure mode such as facesheet wrinkling, core crushing and sandwich buckling. Facesheet/core debonding has also been observed in the marine and aerospace industry. During this failure mode, peel stresses applied to an existing facesheet/core debond or an interface low in toughness, results in the facesheet being peeled from the core material, possibly leading to a significant loss in structural integrity of the sandwich panel. In an incident during a test on a liquid hydrogen fuel tank of the X-33 prototype vehicle, the outer graphite/epoxy facesheet and honeycomb core became debonded from the inner facesheet along significant areas, leading to failure of the tank. As a consequence of the accident; significant efforts were made to characterize the toughness of the facesheet/core bond. Currently, the only standardized method available for assessing the quality of the facesheet/core interface is the climbing drum peel test (ASTM D1781). During this test a sandwich beam is removed from a panel and the lip of one of the facesheets is attached to a drum, as shown in Fig. 1. The drum is then rotated along the sandwich beam, causing the facesheet to peel from the core. This method has two major drawbacks. First, it is not possible to obtain quantitative fracture data from the test and so the results can only be used in a qualitative manner. Second, only sandwich structure with thin facesheets can be tested (to facilitate wrapping of the facesheet around the climbing drum). In recognition of the need for a more quantitative facesheet/core fracture test, several workers have devised experimental techniques for characterizing the toughness of the facesheet/core interface. In all of these cases, the tests are designed to yield a mode I-dominated fracture toughness of the facesheet/core interface in a manner similar to that used to determine mode I fracture toughness of composite laminates. In the current work, a modified double cantilever beam is used to measure the mode I-dominated fracture toughness of the interface in a sandwich consisting of glass/phenolic honeycomb core reinforced with graphite epoxy facesheets. Two specimen configurations were tested as shown in Fig 2. The first configuration consisted of reinforcing the facesheets with aluminum blocks (Fig. 2a). In the second configuration unreinforced specimens were tested (Fig. 2b). Climbing drum peel tests were also conducted to compare the fracture behavior observed between this test and the modified double cantilever beam. This paper outlines the test procedures and data reduction strategies used to compute fracture toughness values from the tests. The effect of specimen reinforcement on fracture toughness of the facesheet/core interface is discussed.

  19. Development of Quiet Honeycomb Panels

    NASA Technical Reports Server (NTRS)

    Palumbo, Daniel L.; Klos, Jacob

    2009-01-01

    Sandwich honeycomb composite panels are lightweight and strong, and, therefore, provide a reasonable alternative to the aluminum ring framelstringer architecture currently used for most aircraft airframes. The drawback to honeycomb panels is that they radiate noise into the aircraft cabin very efficiently provoking the need for additional sound treatment which adds weight and reduces the material's cost advantage. A series of honeycomb panels were made which incorporated different design strategies aimed at reducing the honeycomb panels' radiation efficiency while at the same time maintaining its strength. The majority of the desi gns were centered around the concept of creatin g areas of reduced stiffness in the panel by adding voids and recesses to the core. The effort culminated with a reinforced./recessed panel which had 6 dB higher transmission loss than the baseline solid core panel while maintaining comparable strength.

  20. Impact response of fiber metal laminate sandwich composite structure with polypropylene honeycomb core

    Microsoft Academic Search

    C. Y. Tan

    Fiber metal laminates (FMLs) were used as skin on polypropylene honeycomb core to form a sandwich structure. Impact response was measured by conducting a series of low-velocity impact test. Impact force and the force time history were recorded and analyzed. It was found that the maximum impact load increased up to a threshold value at which it plateaus while the

  1. Modelling of composite sandwich structures with honeycomb core subjected to high-velocity impact

    Microsoft Academic Search

    Brenda L. Buitrago; Carlos Santiuste; Sonia Sánchez-Sáez; Enrique Barbero; Carlos Navarro

    2010-01-01

    In this study the perforation of composite sandwich structures subjected to high-velocity impact was analysed. Sandwich panels with carbon\\/epoxy skins and an aluminium honeycomb core were modelled by a three-dimensional finite element model implemented in ABAQUS\\/Explicit. The model was validated with experimental tests by comparing numerical and experimental residual velocity, ballistic limit, and contact time. By this model the influence

  2. Evaluation of the Transient Liquid Phase (TLP) Bonding Process for Ti3Al-Based Honeycomb Core Sandwich Structure

    NASA Technical Reports Server (NTRS)

    Bird, R. Keith; Hoffman, Eric K.

    1998-01-01

    The suitability of using transient liquid phase (TLP) bonding to fabricate honeycomb core sandwich panels with Ti-14Al-21Nb (wt%) titanium aluminide (T3Al) face sheets for high-temperature hypersonic vehicle applications was evaluated. Three titanium alloy honeycomb cores and one Ti3Al alloy honeycomb core were investigated. Edgewise compression (EWC) and flatwise tension (FWT) tests on honeycomb core sandwich specimens and tensile tests of the face sheet material were conducted at temperatures ranging from room temperature to 1500 F. EWC tests indicated that the honeycomb cores and diffusion bonded joints were able to stabilize the face sheets up to and beyond the face sheet compressive yield strength for all temperatures investigated. The specimens with the T3Al honeycomb core produced the highest FWT strengths at temperatures above 1000 F. Tensile tests indicated that TLP processing conditions resulted in decreases in ductility of the Ti-14Al-21Nb face sheets. Microstructural examination showed that the side of the face sheets to which the filler metals had been applied was transformed from equiaxed alpha2 grains to coarse plates of alpha2 with intergranular Beta. Fractographic examination of the tensile specimens showed that this transformed region was dominated by brittle fracture.

  3. Measuring Core/Facesheet Bond Toughness in Honeycomb Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.

    2006-01-01

    This study examines two test methods to evaluate the peel toughness of the skin to core debond of sandwich panels. The methods tested were the climbing drum (CD) peel test and the double cantilever beam (DCB) test. While the CD peel test is only intended for qualitative measurements, it is shown in this study that qualitative measurements can be performed and compare well with DCB test data. It is also shown that artificially stiffening the facesheets of a DCB specimen can cause the test to behave more like a flatwise tensile test than a peel test.

  4. Buckling tests of three 4.6 meter diameter aluminum honeycomb sandwich conical shells loaded under external pressure

    NASA Technical Reports Server (NTRS)

    Anderson, J. K.; Davis, R. C.

    1975-01-01

    Three aluminum honeycomb sandwich conical shells with a 120 apex angle and a 4.6-m (15.0-ft) base diameter were loaded to failure by a uniform external pressure. The cones differed from one another only in the thickness of their respective face sheets. Test specimen details, test procedure, and test results are discussed. Both buckling and prebuckling data are compared with appropriate theoretical predictions, and good agreement was obtained between test and theory. Extensive imperfection measurements were made and reported on the three cones in the as fabricated condition.

  5. Honeycomb-laminate composite structure

    NASA Technical Reports Server (NTRS)

    Gilwee, W. J., Jr.; Parker, J. A. (inventors)

    1977-01-01

    A honeycomb-laminate composite structure was comprised of: (1) a cellular core of a polyquinoxaline foam in a honeycomb structure, and (2) a layer of a noncombustible fibrous material impregnated with a polyimide resin laminated on the cellular core. A process for producing the honeycomb-laminate composite structure and articles containing the honeycomb-laminate composite structure is described.

  6. Fabrication and evaluation of enhanced diffusion bonded titanium honeycomb core sandwich panels with titanium aluminide face sheets

    NASA Technical Reports Server (NTRS)

    Hoffmann, E. K.; Bird, R. K.; Bales, T. T.

    1989-01-01

    A joining process was developed for fabricating lightweight, high temperature sandwich panels for aerospace applications using Ti-14Al-21Nb face sheets and Ti-3Al-2.5V honeycomb core. The process, termed Enhanced Diffusion Bonding (EDB), relies on the formation of a eutectic liquid through solid-state diffusion at elevated temperatures and isothermal solidification to produce joints in thin-gage titanium and titanium aluminide structural components. A technique employing a maskant on the honeycomb core was developed which permitted electroplating a controlled amount of EDB material only on the edges of the honeycomb core in order to minimize the structural weight and metallurgical interaction effects. Metallurgical analyses were conducted to determine the interaction effects between the EDB materials and the constituents of the sandwich structure following EDB processing. The initial mechanical evaluation was conducted with butt joint specimens tested at temperatures from 1400 - 1700 F. Further mechanical evaluation was conducted with EDB sandwich specimens using flatwise tension tests at temperatures from 70 - 1100 F and edgewise compression tests at ambient temperature.

  7. Analytical studies of a parabolic line concentrator utilizing an aluminum honeycomb support structure and a thin glass reflector laminate

    SciTech Connect

    Koteras, J.R.

    1981-03-01

    Results (stresses, displacements, and equivalent slope errors) are presented from finite element analyses made to evaluate a design for a parabolic trough solar concentrator. The concentrator consists of a reflector laminate (made of thin glass bonded to sheet metal backing) which is mechanically formed and bonded to a stiff parabolic support (made of aluminum honeycomb bonded to steel skins) with a 2 meter (6.6 foot) aperture. Analyses were first made to determine a length for the concentrator such that it would meet certain performance and survivability criteria under wind and gravity loadings. These studies were made with a model for the concentrator only. The concentrator model was then combined with a model for a support mechanism, and this combined structure was studied for several wind and gravity loadings. A design characterized by a six meter (twenty foot) long concentrator was found to meet performance criteria and had sufficiently low glass stresses in a 40.23 meter per second ((ninety mile per hour) wind.

  8. Wax Reinforces Honeycomb During Machining

    NASA Technical Reports Server (NTRS)

    Towell, Timothy W.; Fahringer, David T.; Vasquez, Peter; Scheidegger, Alan P.

    1995-01-01

    Method of machining on conventional metal lathe devised for precise cutting of axisymmetric contours on honeycomb cores made of composite (matrix/fiber) materials. Wax filling reinforces honeycomb walls against bending and tearing while honeycomb being contoured on lathe. Innovative method of machining on lathe involves preparation in which honeycomb is placed in appropriate fixture and the fixture is then filled with molten water-soluble wax. Number of different commercial waxes have been tried.

  9. REIS, ENGIN MURAT. Characteristics of Innovative 3-D FRP Sandwich Panels. Foam and honeycomb core sandwich composites are widely used in structural

    E-print Network

    ABSTRACT REIS, ENGIN MURAT. Characteristics of Innovative 3-D FRP Sandwich Panels. Foam and honeycomb core sandwich composites are widely used in structural applications. Nevertheless, possibilities encountered in traditional FRP panels. The panels consist of GFRP laminates and foam core sandwich where top

  10. Novel design of honeycombs using a seamless combination of auxetic and conventional cores toward phononic band gap engineering

    NASA Astrophysics Data System (ADS)

    Mukherjee, Sushovan; Scarpa, Fabrizio; Gopalakrishnan, S.

    2015-04-01

    A novel design for the geometric configuration of honeycombs using a seamless combination of auxetic and conventional cores-elements with negative and positive Possion ratios respectively, has been presented. The proposed design has been shown to generate a superior band gap property while retaining all major advantages of a purely conventional or purely auxetic honeycomb structure. Seamless combination ensures that joint cardinality is also retained. Several configurations involving different degree of auxeticity and different proportions auxetic and conventional elements have been analyzed. It has been shown that the preferred configurations open up wide and clean band gap at a significantly lower frequency ranges compared to their pure counterparts. In view of existence of band gaps being desired feature for the phononic applications, reported results might be appealing. Use of such design may enable superior vibration control as well. Proposed configurations can be made isovolumic and iso-weight giving designers a fairer ground of applying such configurations without significantly changing size and weight criteria.

  11. Prediction of dislocation cores in aluminum from density functional theory.

    PubMed

    Woodward, C; Trinkle, D R; Hector, L G; Olmsted, D L

    2008-02-01

    The strain field of isolated screw and edge dislocation cores in aluminum are calculated using density-functional theory and a flexible boundary condition method. Nye tensor density contours and differential displacement fields are used to accurately bound Shockley partial separation distances. Our results of 5-7.5 A (screw) and 7.0-9.5 A (edge) eliminate uncertainties resulting from the wide range of previous results based on Peierls-Nabarro and atomistic methods. Favorable agreement of the predicted cores with limited experimental measurements demonstrates the need for quantum mechanical treatment of dislocation cores. PMID:18352300

  12. Brazed Borsic/aluminum structural panels

    NASA Technical Reports Server (NTRS)

    Bales, T. T.; Wiant, H. R.; Royster, D. M.

    1977-01-01

    A fluxless brazing process has been developed that minimizes degradation of the mechanical properties of Borsic/aluminum composites. The process, which employs 718 aluminum alloy braze, is being used to fabricate full scale Borsic/aluminum-titanium honeycomb-core panels for Mach 3 flight testing on the YF-12 aircraft and ground testing in support of the Supersonic Cruise Aircraft Research (SCAR) Program. The manufacturing development and results of shear tests on full scale panels are presented.

  13. Analytical structural efficiency studies of borsic/aluminum compression panels

    NASA Technical Reports Server (NTRS)

    Mcwithey, R. R.

    1976-01-01

    Analytically determined mass-strength curves, strain-strength curves, and dimensions are presented for structurally efficient hat-stiffened panels, corrugation-stiffened panels, hat-stiffened honeycomb-core sandwich panels, open-section corrugation panels, and honeycomb-core sandwich panels. The panels were assumed to be fabricated from either titanium, borsic/aluminum, or a combination of these materials. Borsic/aluminum panels and titanium panels reinforced with borsic/aluminum were lighter and stiffer than comparably designed titanium panels. Reinforced titanium panels had the same extensional stiffness as comparably designed Borsic/aluminum panels. For a given load, the structural efficiency of the hat-stiffened honeycomb-core sandwich panel was higher than the structural efficiency of the other stiffened panels.

  14. Brazed boron-silicon carbide/aluminum structural panels

    NASA Technical Reports Server (NTRS)

    Arnold, W. E., Jr.; Bales, T. T.; Brooks, T. G.; Lawson, A. G.; Mitchell, P. D.; Royster, D. M.; Wiant, R.

    1978-01-01

    Fluxless brazing process minimizes degradation of mechanical properties composite material of silicon carbide coated boron fibers in an aluminum matrix. Process is being used to fabricate full-scale Boron-Silicon Carbide/Aluminum-Titanium honeycomb core panels for flight testing and ground testing.

  15. Design manufacture and test of a cryo-stable Offner relay using aluminum foam core optics

    Microsoft Academic Search

    Ryan S. McClelland

    2001-01-01

    Aluminum foam core optics have the desirable characteristics of being lightweight, cryo-stable, and low cost. The availability of high quality aluminum foam and a bare aluminum super-polishing process have allowed high performance foam core optics made entirely of aluminum to be produced. Mirrors with integral mounts were designed for minimum surface error induced by self-weight deflection, thermal gradients, and mounting

  16. Aerodynamic effect of a honeycomb rotor tip shroud on a 50.8-centimeter-tip-diameter core turbine

    NASA Technical Reports Server (NTRS)

    Moffitt, T. P.; Whitney, W. J.

    1983-01-01

    A 50.8-cm-tip-diameter turbine equipped with a rotor tip shroud of hexagonal cell (or honeycomb) cross section has been tested in warm air (416 K) for a range of shroud coolant to primary flow rates. Test results were also obtained for the same turbine operated with a solid shroud for comparison. The results showed that the combined effect of the honeycomb shroud and the coolant flow was to cause a reduction of 2.8 points in efficiency at design speed, pressure ratio, and coolant flow rate. With the coolant system inactivated, the honeycomb shroud caused a decrease in efficiency of 2.3 points. These results and those obtained from a small reference turbine indicate that the dominant factor governing honeycomb tip shroud loss is the ratio of honeycomb depth to blade span. The loss results of the two shrouds could be correlated on this basis. The same honeycomb and coolant effects are expected to occur for the hot (2200 K) version of this turbine.

  17. Deformation and failure mechanism of dynamically loaded sandwich beams with aluminum-foam core

    Microsoft Academic Search

    J. L Yu; X Wang; Z. G Wei; E. H Wang

    2003-01-01

    In this paper the response and failure of dynamically loaded sandwich beams with an aluminum-foam core is investigated experimentally. The dynamic compressive stress–strain curves of the core material, an open-cell aluminum foam, are obtained by an SHPB technique. No strain-rate sensitivity is found. Quasi-static and dynamic bending tests are carried out for sandwich beams made of aluminum skins with an

  18. Ballistic Resistance of Honeycomb Sandwich Panels under In-Plane High-Velocity Impact

    PubMed Central

    Yang, Shu; Wang, Dong; Yang, Li-Jun

    2013-01-01

    The dynamic responses of honeycomb sandwich panels (HSPs) subjected to in-plane projectile impact were studied by means of explicit nonlinear finite element simulations using LS-DYNA. The HSPs consisted of two identical aluminum alloy face-sheets and an aluminum honeycomb core featuring three types of unit cell configurations (regular, rectangular-shaped, and reentrant hexagons). The ballistic resistances of HSPs with the three core configurations were first analyzed. It was found that the HSP with the reentrant auxetic honeycomb core has the best ballistic resistance, due to the negative Poisson's ratio effect of the core. Parametric studies were then carried out to clarify the influences of both macroscopic (face-sheet and core thicknesses, core relative density) and mesoscopic (unit cell angle and size) parameters on the ballistic responses of the auxetic HSPs. Numerical results show that the perforation resistant capabilities of the auxetic HSPs increase as the values of the macroscopic parameters increase. However, the mesoscopic parameters show nonmonotonic effects on the panels' ballistic capacities. The empirical equations for projectile residual velocities were formulated in terms of impact velocity and the structural parameters. It was also found that the blunter projectiles result in higher ballistic limits of the auxetic HSPs. PMID:24187526

  19. Failure of sandwich beams consisting of alumina face sheet and aluminum foam core in bending

    Microsoft Academic Search

    Kapil Mohan; Yip Tick Hon; Sridhar Idapalapati; Hong Pheow Seow

    2005-01-01

    Applications of sandwich structures, comprising alumina face sheets and aluminum foam core, depend critically on their mechanical performance. Four point bend tests are performed on sandwich beams with varying geometries to identify competing failure modes, such as core indentation, face sheet cracking and core shear. Analytical formulae for the identified failure modes are obtained. A failure mode map was constructed

  20. The structural behavior of a graphite-polymide honeycomb sandwich panel with quasi-isotropic face sheets and an orthotropic core

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.; Hagaman, J. A.

    1979-01-01

    The results of a series of tests of graphite-polyimide honeycomb sandwich panels are presented. The panels were 1.22 m long, 0.508 m wide, and approximately 13.3 m thick. The face sheets were a T-300/PMR-15 fabric in a quasi-isotropic layup and were 0.279 mm thick. The core was Hexcel HRH 327-3/16 - 4.0 glass reinforced polyimide honeycomb, 12.7 mm thick. Three panels were used in the test: one was cut into smaller pieces for testing as beam, compression, and shear specimens; a second panel was used for plate bending tests; the third panel was used for in-plane stability tests. Presented are the experimental results of four point bending tests, short block compression tests, core transverse shear modulus, three point bending tests, vibration tests, plate bending tests, and panel stability tests. The results of the first three tests are used to predict the results of some of the other tests. The predictions and experimental results are compared, and the agreement is quite good.

  1. Probability of Detection Study on Impact Damage to Honeycomb Composite Structure using Thermographic Inspection

    NASA Technical Reports Server (NTRS)

    Hodge, Andrew J.; Walker, James L., II

    2008-01-01

    A probability of detection study was performed for the detection of impact damage using flash heating infrared thermography on a full scale honeycomb composite structure. The honeycomb structure was an intertank structure from a previous NASA technology demonstration program. The intertank was fabricated from IM7/8552 carbon fiber/epoxy facesheets and aluminum honeycomb core. The intertank was impacted in multiple locations with a range of impact energies utilizing a spherical indenter. In a single blind study, the intertank was inspected with thermography before and after impact damage was incurred. Following thermographic inspection several impact sites were sectioned from the intertank and cross-sectioned for microscopic comparisons of NDE detection and actual damage incurred. The study concluded that thermographic inspection was a good method of detecting delamination damage incurred by impact. The 90/95 confidence level on the probability of detection was close to the impact energy that delaminations were first observed through cross-sectional analysis.

  2. Aluminum foams produced by liquid-state processes

    Microsoft Academic Search

    A. E. Simone; L. J. Gibson

    1998-01-01

    Lightweight cellular materials can be used in the construction of composite plates, shells and tubes with high structural efficiency. Metallic sandwich construction with integrally bonded face-sheet\\/foam core configurations offer a cost-efficient alternative to conventional skin-stringer and honeycomb core components. The potential effectiveness of such constructions is dependent on the properties and performance of the core materials. In this study, aluminum

  3. SPERT Destructive Test - I on Aluminum, Highly Enriched Plate Type Core

    ScienceCinema

    None

    2014-05-07

    SPERT - Special Power Excursion Reactor Tests Destructive Test number 1 On Aluminum, Highly Enriched Plate Type Core. A test studying the behavior of the reactor under destructive conditions on a light water moderated pool-type reactor with a plate-type core.

  4. Honeycomb network

    NSDL National Science Digital Library

    Joydeep, Mukherjee

    2005-01-31

    Issue Date: 31-Jan-2005 Description: Simulation Software: Glotzer Group Code Simulation Method: Monte Carlo A system of 360 patchy particle nano building blocks was simulated at a concentration of 0.56 particles/surface area, starting from a disordered state then quenched to a temperature of 0.8. The building blocks have the following patch locations and patterning: 3 patches uniformly spaced on a sphere. The system was run for ~50e6 until arriving at the final structure (Honeycomb). Simulation Model: United Atom with Kern-Frenkel like potential

  5. Advanced radiator concepts utilizing honeycomb panel heat pipes

    NASA Technical Reports Server (NTRS)

    Fleischman, G. L.; Peck, S. J.; Tanzer, H. J.

    1987-01-01

    The feasibility of fabricating and processing moderate temperature range vapor chamber type heat pipes in a low mass honeycomb panel configuration for highly efficient radiator fins for potential use on the space station was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts were evaluated within constraints dictated by existing manufacturing technology and equipment. Concepts evaluated include type of material, material and panel thickness, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. A thin-wall all-welded stainless steel design with methanol as the working fluid was the initial prototype unit. It was found that an aluminum panel could not be fabricated in the same manner as a stainless steel panel due to diffusion bonding and resistance welding considerations. Therefore, a formed and welded design was developed. The prototype consists of ten panels welded together into a large panel 122 by 24 by 0.15 in., with a heat rejection capability of 1000 watts and a fin efficiency of essentially 1.0.

  6. The Electrical Properties of Single-Layer Aluminum Conductors, Steel Reinforced (ACSR), Having Single Steel Core Wires with Heavy Aluminum Coating

    Microsoft Academic Search

    C. H. Jensen; R. E. Demuth; R. W. Mowery

    1962-01-01

    This paper discusses electrical tests made on representative sizes of single layer alminum conductors, steel reinforced with galvanized and heavy aluminum coatings. Analysis of 60-cycle a-c (alternating current) test data indicates that the conductors with aluminum-clad core wires than the same sizes of ACSR conductors in which the core wires are of galvanized steel. The differences are in the order

  7. Bundled aluminum hollow-core fibers for delivery of ultraviolet laser beams

    Microsoft Academic Search

    Yilmaz Ozgur; Yuji Matsuura; Mitsunobu Miyagi

    2005-01-01

    A bundle of aluminum hollow-core fibers is used to deliver ArF-excimer-laser light. The hollow cores are purged by a simple gas injection system to prevent the generation of ozone gas. For a 1-m-long bundle that is composed of 40 fibers each with an inner diameter of 0.7 mm, the straight loss is about 1.2 dB. The bundle also offers advantages

  8. Effect of core topology on projectile penetration in hybrid aluminum/alumina sandwich structuresq

    E-print Network

    Wadley, Haydn

    Effect of core topology on projectile penetration in hybrid aluminum/alumina sandwich structuresq H 2013 Keywords: Sandwich panels Ballistics Cellular structures a b s t r a c t A series of hybrid sandwich structures were fabricated by shrink-fitting precision-ground prisms of alumina (CoorsTek grade AD

  9. The structural analysis of a light-weight aluminum foam core mirror

    Microsoft Academic Search

    W. Pollard; D. Vukobratovich; R. Richard

    1987-01-01

    A high sensitivity of optical performance to foam core mechanical properties is indicated by the results obtained by the present NASTRAN code FEM analysis of a novel, aluminum foamcore sandwich structure reflecting telescope mirror. The material properties of the foam are such that the conventional isotropic relationship between shear modulus, Young's modulus, and Poisson's ratio does not apply. Material testing

  10. Arc joining of aluminum alloy to stainless steel with flux-cored Zn-based filler metal

    Microsoft Academic Search

    Honggang Dong; Liqun Yang; Chuang Dong; Sindo Kou

    2010-01-01

    Aluminum alloy was arc welded to stainless steel with a flux-cored Zn-based filler wire. Annealing enhanced the tensile strength of the joints, and fracture occurred through the aluminum base metal during testing. The weld consisted of a ZnO-enhanced Zn–Al cermet, and Fe–Al–Zn intermetallic compounds were detected within the interfacial layer.

  11. Static and Low Velocity Impact Behavior of Composite Sandwich Panels with an Aluminum Foam Core

    Microsoft Academic Search

    German Reyes

    2008-01-01

    The static and low velocity impact response of aluminum foam based sandwich structures manufactured using thermoplastic composite skins has been studied. The three-point bend (3PB) test geometry was used to evaluate the static properties of the sandwich structures. An examination of the quasi-statically tested specimens revealed failure modes such as indentation, core yielding, and face wrinkling. The low velocity impact

  12. Advanced radiator concepts utilizing honeycomb panel heat pipes (stainless steel)

    NASA Technical Reports Server (NTRS)

    Fleischman, G. L.; Tanzer, H. J.

    1985-01-01

    The feasibility of fabricating and processing moderate temperature range heat pipes in a low mass honeycomb sandwich panel configuration for highly efficient radiator fins for the NASA space station was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts were evaluated within constraints dictated by existing manufacturing technology and equipment. Concepts evaluated include: type of material, material and panel thicknesses, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. In addition, the overall performance of the honeycomb panel heat pipe was evaluated analytically.

  13. Aluminum and copper plasmonics for enhancing internal quantum efficiency of core-shell and core-multishell nanowire photoelectrodes

    NASA Astrophysics Data System (ADS)

    Ramadurgam, Sarath; Yang, Chen

    2014-09-01

    One of the critical challenges for achieving solar-to-hydrogen efficiency greater than 10% (100 W/m2), especially in metal oxide photoelectrodes, is the poor internal quantum efficiency arising from high, bulk and surface, recombination and insufficient light absorption. Plasmonic light harvesting has emerged as a promising strategy to address this challenge. However, most designs are photocatalyst specific and employ precious metals, making large scale applications infeasible. We present metal-photocatalyst core-shell and semiconductor-metal-photocatalyst coremultishell nanowires as a novel class of multi-functional plasmonic photoelectrodes. By combining the optical resonances with the localized surface plasmon resonance within the proposed structures, we achieve extreme light absorption in the visible range within ultrathin photocatalyst layers. Such enhanced absorption ensures that the photocharges are preferentially generated very close to the photocatalyst-electrolyte interface and can effectively drive the reaction forward, thereby improving the internal quantum efficiency. Specifically, for nanowires in an aqueous electrolyte, we demonstrate the effectiveness of aluminum and copper to confine light and establish them as plasmonic alternatives to precious metal counterparts such as silver and gold therefore enabling cheap and scalable plasmonics. Further, we probe the absorption as a function of the permittivity of the electrolyte and show that the absorption in such nanowires is large even for high permittivity electrolytes. Hematite and copper(I) oxide have been chosen as the test materials to validate the generality of this approach. Notably, for hematite, we show that aluminum is more effective than copper, while for a broadband absorber such as copper(I) oxide, we show that both aluminum and copper are equally effective for plasmonic light harvesting.

  14. Honeycomb vs. Foam: Evaluating a Potential Upgrade to ISS Module Shielding for Micrometeoroids and Orbital Debris

    NASA Technical Reports Server (NTRS)

    Ryan, Shannon; Hedman, Troy; Christiansen, Eric L.

    2009-01-01

    The presence of a honeycomb core in a multi-wall shielding configuration for protection against micrometeoroid and orbital debris (MMOD) particle impacts at hypervelocity is generally considered to be detrimental as the cell walls act to restrict fragment cloud expansion, creating a more concentrated load on the shield rear wall. However, mission requirements often prevent the inclusion of a dedicated MMOD shield, and as such, structural honeycomb sandwich panels are amongst the most prevalent shield types. Open cell metallic foams are a relatively new material with novel mechanical and thermal properties that have shown promising results in preliminary hypervelocity impact shielding evaluations. In this study, an ISS-representative MMOD shielding configuration has been modified to evaluate the potential performance enhancement gained through the substitution of honeycomb for open cell foam. The baseline shielding configuration consists of a double mesh outer layer, two honeycomb sandwich panels, and an aluminum rear wall. In the modified configuration the two honeycomb cores are replaced by open-cell foam. To compensate for the heavier core material, facesheets have been removed from the second sandwich panel in the modified configuration. A total of 19 tests on the double layer honeycomb and double layer foam configurations are reported. For comparable mechanical and thermal performance, the foam modifications were shown to provide a 15% improvement in critical projectile diameter at low velocities (i.e. 3 km/s) and a 3% increase at high velocities (i.e. 7 km/s) for normal impact. With increasing obliquity, the performance enhancement was predicted to increase, up to a 29% improvement at 60 (low velocity). Ballistic limit equations have been developed for the new configuration, and consider the mass of each individual shield component in order to maintain validity in the event of minor configuration modifications. Previously identified weaknesses of open cell foams for hypervelocity impact shielding such as large projectile diameters, low velocities, and high degrees of impact obliquity have all been investigated, and found to be negligible for the double-layer configuration.

  15. Experiments and full-scale numerical simulations of in-plane crushing of a honeycomb

    Microsoft Academic Search

    S. D. Papka; S. Kyriakides

    1998-01-01

    The in-plane mechanical behavior of honeycombs has been widely used as a two-dimensional model of the behavior of more complicated space filling foams. This paper deals with the mechanisms governing in-plane crushing of hexagonal aluminum honeycombs. Finite size honeycomb specimens are crushed quasi-statically between parallel rigid surfaces. The force–displacement response is initially stiff and elastic but this is terminated by

  16. Pre-Stressing Micron-Scale Aluminum Core-Shell Particles to Improve Reactivity

    PubMed Central

    Levitas, Valery I.; McCollum, Jena; Pantoya, Michelle

    2015-01-01

    The main direction in increasing reactivity of aluminum (Al) particles for energetic applications is reduction in their size down to nanoscale. However, Al nanoparticles are 30–50 times more expensive than micron scale particles and possess safety and environmental issues. Here, we improved reactivity of Al micron scale particles by synthesizing pre-stressed core-shell structures. Al particles were annealed and quenched to induce compressive stresses in the alumina passivation shell surrounding Al core. This thermal treatment was designed based on predictions of the melt-dispersion mechanism (MDM); a theory describing Al particle reaction under high heating rate. For all anneal treatment temperatures, experimental flame propagation rates for Al combined with nanoscale copper oxide (CuO) are in quantitative agreement with the theoretical predictions based on the MDM. The best treatment increases flame rate by 36% and achieves 68% of that for the best Al nanoparticles. PMID:25597747

  17. Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys

    DOE PAGESBeta

    Jiang, Xingmao; Jiang, Ying-Bing; Liu, Nanguo; Xu, Huifang; Rathod, Shailendra; Shah, Pratik; Brinker, C. Jeffrey

    2011-01-01

    Cerium (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was1.0×10?14?m2s for Ce3+compared to2.5×10?13?m2s for NaCl. The pore size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition.

  18. Pre-stressing micron-scale aluminum core-shell particles to improve reactivity.

    PubMed

    Levitas, Valery I; McCollum, Jena; Pantoya, Michelle

    2015-01-01

    The main direction in increasing reactivity of aluminum (Al) particles for energetic applications is reduction in their size down to nanoscale. However, Al nanoparticles are 30-50 times more expensive than micron scale particles and possess safety and environmental issues. Here, we improved reactivity of Al micron scale particles by synthesizing pre-stressed core-shell structures. Al particles were annealed and quenched to induce compressive stresses in the alumina passivation shell surrounding Al core. This thermal treatment was designed based on predictions of the melt-dispersion mechanism (MDM); a theory describing Al particle reaction under high heating rate. For all anneal treatment temperatures, experimental flame propagation rates for Al combined with nanoscale copper oxide (CuO) are in quantitative agreement with the theoretical predictions based on the MDM. The best treatment increases flame rate by 36% and achieves 68% of that for the best Al nanoparticles. PMID:25597747

  19. The dynamic mechanical properties study on the sandwich panel of different thickness steel plate-foam aluminum core

    Microsoft Academic Search

    Zhongliang Chang; Guangping Zou; Weiling Zhao; Peixiu Xia

    2009-01-01

    The foam aluminum belongs to multi-cell materials, and it has good mechanical performance, such as large deformation capacity and good energy absorption, and usually used as core material of sandwich panel, now it is widely used in automotive, aviation, aerospace and other fields, particularly suitable for various anti-collision structure and buffer structure. In this article, based on an engineering background,

  20. Extruded ceramic honeycomb and method

    DOEpatents

    Day, J. Paul (Big Flats, NY)

    1995-04-04

    Extruded low-expansion ceramic honeycombs comprising beta-spodumene solid solution as the principal crystal phase and with less than 7 weight percent of included mullite are produced by compounding an extrusion batch comprising a lithium aluminosilicate glass powder and a clay additive, extruding a green honeycomb body from the batch, and drying and firing the green extruded cellular honeycomb to crystallize the glass and clay into a low-expansion spodumene ceramic honeycomb body.

  1. High-capacity honeycomb panel heat pipes for space radiators

    Microsoft Academic Search

    H. J. Tanzer

    1983-01-01

    The integral heat-pipe honeycomb panel structure is evaluated for application to future space platforms as lightweight, reliable, and highly efficient radiators. Performance predictions and structural development of a representative 120 by 24 by 0.25-in. depth segment of a full-sized modular radiator fin is presented. The panel design utilizes an all-welded stainless steel wickable honeycomb core and facesheet construction, and methanol

  2. Thermal Inspection of Composite Honeycomb Structures

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Parker, F. Raymond

    2014-01-01

    Composite honeycomb structures continue to be widely used in aerospace applications due to their low weight and high strength advantages. Developing nondestructive evaluation (NDE) inspection methods are essential for their safe performance. Pulsed thermography is a commonly used technique for composite honeycomb structure inspections due to its large area and rapid inspection capability. Pulsed thermography is shown to be sensitive for detection of face sheet impact damage and face sheet to core disbond. Data processing techniques, using principal component analysis to improve the defect contrast, are presented. In addition, limitations to the thermal detection of the core are investigated. Other NDE techniques, such as computed tomography X-ray and ultrasound, are used for comparison to the thermography results.

  3. Thermal inspection of composite honeycomb structures

    NASA Astrophysics Data System (ADS)

    Zalameda, Joseph N.; Parker, F. Raymond

    2014-05-01

    Composite honeycomb structures continue to be widely used in aerospace applications due to their low weight and high strength advantages. Developing nondestructive evaluation (NDE) inspection methods are essential for their safe performance. Pulsed thermography is a commonly used technique for composite honeycomb structure inspections due to its large area and rapid inspection capability. Pulsed thermography is shown to be sensitive for detection of face sheet impact damage and face sheet to core disbond. Data processing techniques, using principal component analysis to improve the defect contrast, are presented. In addition, limitations to the thermal detection of the core are investigated. Other NDE techniques, such as computed tomography X-ray and ultrasound, are used for comparison to the thermography results.

  4. The Honeycomb supernova remnant

    NASA Technical Reports Server (NTRS)

    Chu, You-Hua; Dickel, John R.; Staveley-Smith, Lister; Osterberg, Juergen; Smith, R. Chris

    1995-01-01

    At 2.5 min southeast of SN 1987A, the Honeycomb Nebula Supernova remnant (SNR) is named after its interesting morphology, which consists of over ten loops with sizes of 2-3 pc. High-dispersion spectra of these loops show hemispheres expanding toward the observer at 100-300 km/s. Using archival data X-ray data and a combination of new and archival radio data, we find bright X-ray and nonthermal radio emisssion associated with the Honeycomb Nebula. New CCD images further show enhanced (S II) H-alpha ratios. These results confirm a model in which the Honeycomb Nebula is due to a supernova shock front, traveling toward the observer, encountering an intervening sheet of dense, but porous, interstellar gas. The bulk of the supernova remnant resides in a low-density cavity, and is not otherwise visible. The situation is similar to the hidden supernova remnants postulated for the X-ray bright superbubbles. The Honeycomb Nebula has an unusually steep radio spectral index (S(sub nu) is proportional to nu(exp -1.2)), normally associated with young SNRs.

  5. The soft impact of composite sandwich beams with a square-honeycomb core B.P. Russell, T. Liu, N.A. Fleck, V.S. Deshpande*

    E-print Network

    Fleck, Norman A.

    in the sandwich beams including core fracture, plug-type shear failure of the core, debonding of the face sheets from glass-epoxy face sheets and a polymer foam core. Subse- quently, Tagarielli et al. [2 structure induces delamination and leads to a reduction of compressive strength, see for example Olsson et

  6. Flight service evaluation of two aluminum-brazed titanium spoilers

    NASA Technical Reports Server (NTRS)

    Boyer, R. R.

    1984-01-01

    The long-term service evaluation of two aluminum-brazed titanium (ABTi) honeycomb flight spoilers was concluded. The two spoilers had about 7.5 years of commercial flight experience on All Nippon Airways Model 737 aircraft. All Nippon Airways was selected because Japan has one of the most severe marine-industrial environments in the world. The results indicated that both flight spoilers still had the same load-carrying capability as when they were originally installed. No direct evidence of any corrosion was observed on either spoiler. Another significant accomplishment of this effort was the development of a braze design for efficiently distributing point loads from the fittings and skin into the honeycomb core.

  7. Static and low-velocity impact behavior of sandwich beams with closed-cell aluminum-foam core in three-point bending

    Microsoft Academic Search

    Jilin Yu; Erheng Wang; Jianrong Li; Zhijun Zheng

    2008-01-01

    In this paper, the response and failure of sandwich beams with aluminum-foam core are investigated. Quasi-static and low-velocity impact bending tests are carried out for sandwich beams with aluminum-foam core. The deformation and failure behavior is explored. It is found that the failure mode and the load history predicted by a modified Gibson's model agree well with the quasi-static experimental

  8. Titanium Honeycomb Panel Testing

    NASA Technical Reports Server (NTRS)

    Richards, W. Lance; Thompson, Randolph C.

    1996-01-01

    Thermal-mechanical tests were performed on a titanium honeycomb sandwich panel to experimentally validate the hypersonic wing panel concept and compare test data with analysis. Details of the test article, test fixture development, instrumentation, and test results are presented. After extensive testing to 900 deg. F, non-destructive evaluation of the panel has not detected any significant structural degradation caused by the applied thermal-mechanical loads.

  9. Experimental study of acoustical characteristics of honeycomb sandwich structures

    NASA Astrophysics Data System (ADS)

    Peters, Portia Renee

    Loss factor measurements were performed on sandwich panels to determine the effects of different skin and core materials on the acoustical properties. Results revealed inserting a viscoelastic material in the core's mid-plane resulted in the highest loss factor. Panels constructed with carbon-fiber skins exhibited larger loss factors than glass-fiber skins. Panels designed to achieve subsonic wave speed did not show a significant increase in loss factor above the coincidence frequency. The para-aramid core had a larger loss factor value than the meta-aramid core. Acoustic absorption coefficients were measured for honeycomb sandwiches designed to incorporate multiple sound-absorbing devices, including Helmholtz resonators and porous absorbers. The structures consisted of conventional honeycomb cores filled with closed-cell polyurethane foams of various densities and covered with perforated composite facesheets. Honeycomb cores filled with higher density foam resulted in higher absorption coefficients over the frequency range of 50 -- 1250 Hz. However, this trend was not observed at frequencies greater than 1250 Hz, where the honeycomb filled with the highest density foam yielded the lowest absorption coefficient among samples with foam-filled cores. The energy-recycling semi-active vibration suppression method (ERSA) was employed to determine the relationship between vibration suppression and acoustic damping for a honeycomb sandwich panel. Results indicated the ERSA method simultaneously reduced the sound transmitted through the panel and the panel vibration. The largest reduction in sound transmitted through the panel was 14.3% when the vibrations of the panel were reduced by 7.3%. The influence of different design parameters, such as core density, core material, and cell size on wave speeds of honeycomb sandwich structures was experimentally analyzed. Bending and shear wave speeds were measured and related to the transmission loss performance for various material configurations. The shear modulus of the core showed maximum influence on the wave speeds of the samples, while cell size did not have a significant influence on wave speeds or on transmission loss. Skin material affected wave speeds only in the pure bending regime. Honeycomb sandwich structures with a subsonic core and thus reduced wave speed showed increased transmission loss compared to samples without a subsonic core.

  10. Heat Shielding Characteristics and Thermostructural Performance of a Superalloy Honeycomb Sandwich Thermal Protection System (TPS)

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    2004-01-01

    Heat-transfer, thermal bending, and mechanical buckling analyses have been performed on a superalloy "honeycomb" thermal protection system (TPS) for future hypersonic flight vehicles. The studies focus on the effect of honeycomb cell geometry on the TPS heat-shielding performance, honeycomb cell wall buckling characteristics, and the effect of boundary conditions on the TPS thermal bending behavior. The results of the study show that the heat-shielding performance of a TPS panel is very sensitive to change in honeycomb core depth, but insensitive to change in honeycomb cell cross-sectional shape. The thermal deformations and thermal stresses in the TPS panel are found to be very sensitive to the edge support conditions. Slight corrugation of the honeycomb cell walls can greatly increase their buckling strength.

  11. Honeycomb chassis for electronic components

    NASA Technical Reports Server (NTRS)

    Read, W. S.; Stebbins, B. W.

    1977-01-01

    In new electronic chassis support, machined honeycomb members are used to change basic relationship between chassis and support structure. Improved chassis combines internal and external support and heat dissipation by altering chassis internal geometry. Honeycomb materials allow mechanical support and thermal load sharing to be combined at lower weight and lower cost than previous equipment.

  12. Bismaleimide resins for flame resistant honeycomb sandwich panels

    NASA Technical Reports Server (NTRS)

    Stenzenberger, H. D.

    1978-01-01

    Bismaleimide resins are prime candidates for nonflammable aircraft interior panels. Three resin types with different structures and processing characteristics were formulated. Resin M 751 was used to fabricate 100 kg of glass fabric prepregs which were used for the preparation of face sheets for honeycomb sandwich panels. Prepreg characteristics and curing cycles for laminate fabrication are provided. In order to advance beyond the current solvent resin technology for fibre and fabric impregnation, a hot melt solvent-less resin system was prepared and characterized. Preliminary tests were performed to develop a wet bonding process for the fabrication of advanced sandwich honeycomb panels by use of polybismaleimide glass fabric face sheets and polybismaleimide Nomex honeycomb core. B-stage material was used for both the core and the face sheet, providing flatwise tensile properties equivalent to those obtained by the state-of-the-art 3-step process which includes an epoxy adhesive resin.

  13. Design Optimization and Analysis of a Composite Honeycomb Intertank

    NASA Technical Reports Server (NTRS)

    Finckenor, Jeffrey; Spurrier, Mike

    1998-01-01

    Intertanks, the structure between tanks of launch vehicles, are prime candidates for weight reduction of rockets. This paper discusses the optimization and detailed analysis of a 96 in (2.44 m) diameter, 77 in (1.85 m) tall intertank. The structure has composite face sheets and an aluminum honeycomb core. The ends taper to a thick built up laminate for a double lap bolted shear joint. It is made in 8 full length panels joined with bonded double lap joints. The nominal load is 4000 lb/in (7 x 10(exp 5) N/m). Optimization is by Genetic Algorithm and minimizes weight by varying C, core thickness, number and orientation of acreage and buildup plies, and the size, number and spacing of bolts. A variety of cases were run with populations up to 2000 and chromosomes as long as 150 bits. Constraints were buckling, face stresses (normal, shear, wrinkling and dimpling, bolt stress, and bolt hole stresses (bearing, net tension, wedge splitting, shear out and tension/shear out). Analysis is by a combination of theoretical solutions and empirical data. After optimization, a series of coupon tests were performed in conjunction with a rigorous analysis involving a variety of finite element models. The analysis and test resulted in several small changes to the optimized design. The intertank has undergone a 250,000 lb (1.1 x 10(exp 6) N) limit load test and been mated with a composite liquid hydrogen tank. The tank/intertank unit is being installed in a test stand where it will see 200 thermal/load cycles. Afterwards the intertank will be demated and loaded in compression to failure.

  14. Finite Element Development of Honeycomb Panel Configurations with Improved Transmission Loss

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.; Palumbo, Daniel L.; Klos, Jacob; Castle, William D.

    2006-01-01

    The higher stiffness-to-mass ratio of a honeycomb panel compared to a homogeneous panel results in a lower acoustic critical frequency. Above the critical frequency the panel flexural wave speed is acoustically fast and the structure becomes a more efficient radiator with associated lower sound transmission loss. Finite element models of honeycomb sandwich structures are presented featuring areas where the core is removed from the radiating face sheet disrupting the supersonic flexural and shear wave speeds that exist in the baseline honeycomb panel. These modified honeycomb panel structures exhibit improved transmission loss for a pre-defined diffuse field sound excitation. The models were validated by the sound transmission loss of honeycomb panels measured in the Structural Acoustic Loads and Transmission (SALT) facility at the NASA Langley Research Center. A honeycomb core panel configuration is presented exhibiting a transmission loss improvement of 3-11 dB compared to a honeycomb baseline panel over a frequency range from 170 Hz to 1000 Hz. The improved transmission loss panel configuration had a 5.1% increase in mass over the baseline honeycomb panel, and approximately twice the deflection when excited by a static force.

  15. Honeycomb spacer crush stength test results

    SciTech Connect

    Leader, D.R.

    1993-09-15

    This report discusses aluminum honeycomb spacers, which are used as an energy absorbent material in shipping packages for off site shipment of radioactive materials and which were ordered in two crush strengths, 1,000 psi and 2,000 psi for use in drop tests requested by the Packaging and Transportation group as part of the shipping container rectification process. Both the group as part of the shipping container rectification process. Both the vendor and the SRTC Materials Laboratory performed crush strength measurements on test samples made from the material used to fabricate the actual spacers. The measurements of crush strength made in the SRTC Materials Laboratory are within 100 psi of the measurements made by the manufacturer for all samples tested and all test measurements are within 10% of the specified crush strength, which is acceptable to the P&T group for the planned tests.

  16. A lightweight yet sound-proof honeycomb acoustic metamaterial

    NASA Astrophysics Data System (ADS)

    Sui, Ni; Yan, Xiang; Huang, Tai-Yun; Xu, Jun; Yuan, Fuh-Gwo; Jing, Yun

    2015-04-01

    In this letter, a class of honeycomb acoustic metamaterial possessing lightweight and yet sound-proof properties is designed, theoretically proven, and then experimentally verified. It is here reported that the proposed metamaterial having a remarkably small mass per unit area at 1.3 kg/m2 can achieve low frequency (<500 Hz) sound transmission loss (STL) consistently greater than 45 dB. Furthermore, the sandwich panel which incorporates the honeycomb metamaterial as the core material yields a STL that is consistently greater than 50 dB at low frequencies. The proposed metamaterial is promising for constructing structures that are simultaneously strong, lightweight, and sound-proof.

  17. Honeycomb Weathering of Limestone Formations

    USGS Multimedia Gallery

    Honeycomb weathering of sandstone located on the shores of Puget Sound occurs when expanding salt crystals break fragments of rock, creating a small hole that becomes larger as the process repeats itself over time....

  18. Versatile honeycomb matrix heat shield

    NASA Technical Reports Server (NTRS)

    Zell, Peter T. (Inventor)

    2010-01-01

    A thermal protection system for atmospheric entry of a vehicle, the system including a honeycomb structure with selected cross sectional shapes that receives and holds thermally cured thermal protection (TP) blocks that have corresponding cross sectional shapes. Material composition for TP blocks in different locations can be varied to account for different atmospheric heating characteristics at the different locations. TP block side walls may be attached to all, or to less than all, the corresponding honeycomb structure side walls.

  19. Investigation of honeycomb structure using pulse infrared thermography method

    NASA Astrophysics Data System (ADS)

    Li, Huijuan

    2010-11-01

    To reduce weight and improve strength in the aerospace industry, composite structure has gained popularity as a replacement for conventional materials and structures, such as adhesive bonding and honeycomb structure. Honeycomb structures composed by a honeycomb core between two facesheets are very common on aerospace parts. However, the adhesive bonding process is more susceptible to quality variations during manufacturing than traditional joining methods. With the large increase in the use of composite materials and honeycomb structures, the need for high speed, large area inspection for fracture critical, sub-surface defects in aircraft, missiles and marine composites led to broad acceptance of infrared based NDT methods. Infrared thermography is one of several non-destructive testing techniques which can be used for defect detection in aircraft materials. Infrared thermography can be potentially useful, as it is quick, real time, non-contact and can examine over a relatively large area in one inspection procedure. In this paper, two kinds of defects which are of various size, shape and location below the test surface are planted in the honeycomb structure, they are all tested by pulsed thermography, analyze the thermal sequence and intensity graph got by this methods, it shows that pulsed thermography is an effective nondestructive technique for inspecting disbonding defect, can distinguish the location and the dimension of the defect exactly.

  20. Method of fabricating a honeycomb structure

    DOEpatents

    Holleran, Louis M. (Big Flats, NY); Lipp, G. Daniel (Fort Collins, CO)

    1999-01-01

    A method of fabricating a monolithic honeycomb structure product involves shaping a first mixture of raw materials and a binder into a green honeycomb, extruding a second mixture of raw materials and a binder into one or more green members that each define an opening extending longitudinally therethrough. The raw materials of the second mixture are compatible with the raw materials of the first mixture. The green honeycomb and member(s) are dried. The binders of the green honeycomb and member(s) are softened at the surfaces that are to be bonded. The green member(s) is inserted into the honeycomb and bonded to the honeycomb to form an assembly thereof, which is then dried and fired to form a unified monolithic honeycomb structure. The insertion is best carried out by mounting a member in the shape of a tube on a mandrel, and inserting the mandrel into the honeycomb opening to bond the tube to the honeycomb.

  1. Liquid ingress recognition in honeycomb structure by pulsed thermography

    NASA Astrophysics Data System (ADS)

    Chen, Dapeng; Zeng, Zhi; Tao, Ning; Zhang, Cunlin; Zhang, Zheng

    2013-05-01

    Pulsed thermography has been proven to be a fast and effective method to detect fluid ingress in aircraft honeycomb structure; however, water and hydraulic oil may have similar appearance in the thermal image sequence. It is meaningful to identify what kind of liquid ingress it is for aircraft maintenance. In this study, honeycomb specimens with glass fiber and aluminum skin are injected different kinds of liquids: water and oil. Pulsed thermography is adopted; a recognition method is proposed to first get the reference curve by linear fitting the beginning of the logarithmic curve, and then an algorithm based on the thermal contrast between liquid and reference is used to recognize what kind of fluid it is by calculating their thermal properties. It is verified with the results of theory and the finite element simulation.

  2. Millimeter Wave Holographical Inspection of Honeycomb Composites

    NASA Astrophysics Data System (ADS)

    Case, J. T.; Kharkovsky, S.; Zoughi, R.; Steffes, G.; Hepburn, F. L.

    2008-02-01

    Multi-layered composite structures manufactured with honeycomb, foam, or balsa wood cores are finding increasing utility in a variety of aerospace, transportation, and infrastructure applications. Due to the low conductivity and inhomogeneity associated with these composites, standard nondestructive testing (NDT) methods are not always capable of inspecting their interior for various defects caused during the manufacturing process or as a result of in-service loading. On the contrary, microwave and millimeter wave NDT methods are well-suited for inspecting these structures since signals at these frequencies readily penetrate through these structures and reflect from different interior boundaries revealing the presence of a wide range of defects such as isband, delamination, moisture and oil intrusion, impact damage, etc. Millimeter wave frequency spectrum spans 30 GHz-300 GHz with corresponding wavelengths of 10-1 mm. Due to the inherent short wavelengths at these frequencies, one can produce high spatial resolution images of these composites either using real-antenna focused or synthetic-aperture focused methods. In addition, incorporation of swept-frequency in the latter method (i.e., holography) results in high-resolution three-dimensional images. This paper presents the basic steps behind producing such images at millimeter wave frequencies and the results of two honeycomb composite panels are demonstrated at Q-band (33-50 GHz). In addition, these results are compared to previous results using X-ray computed tomography.

  3. Polymer optical waveguide composed of europium-aluminum-acrylate composite core for compact optical amplifier and laser

    NASA Astrophysics Data System (ADS)

    Mitani, Marina; Yamashita, Kenichi; Fukui, Toshimi; Ishigure, Takaaki

    2015-02-01

    We successfully fabricate polymer waveguides with Europium-Aluminum (Eu-Al) polymer composite core using the Mosquito method that utilizes a microdispenser for realizing a compact waveguide optical amplifiers and lasers. Rareearth (RE) ions are widely used as the gain medium for fiber lasers and optical fiber amplifiers. However, high concentration doping of rare-earth-ion leads to the concentration quenching resulting in observing less gain in optical amplification. For addressing the concentration quenching problem, a rare-earth metal (RE-M) polymer composite has been proposed by KRI, Inc. to be a waveguide core material. Actually, 10-wt% RE doping into organic polymer materials was already achieved. Hence, realization of compact and high-efficiency waveguide amplifiers and lasers have been anticipated using the RE-M polymer composite. In this paper, a microdispenser is adopted to fabricate a Eu-doped polymer waveguide. Then, it is experimentally confirmed that the low-loss waveguides are fabricated with a high reproducibility. Optical gain is estimated by measuring the amplified spontaneous emission using the variable stripe length method. The fabricated waveguide exhibits an optical gain as high as 7.1 dB/cm at 616-nm wavelength.

  4. Demonstration of aluminum in amyloid fibers in the cores of senile plaques in the brains of patients with Alzheimer's disease.

    PubMed

    Yumoto, Sakae; Kakimi, Shigeo; Ohsaki, Akihiro; Ishikawa, Akira

    2009-11-01

    Aluminum (Al) exposure has been reported to be a risk factor for Alzheimer's disease (senile dementia of Alzheimer type), although the role of Al in the etiology of Alzheimer's disease remains controversial. We examined the presence of Al in the Alzheimer's brain using energy-dispersive X-ray spectroscopy combined with transmission electron microscopy (TEM-EDX). TEM-EDX analysis allows simultaneous imaging of subcellular structures with high spatial resolution and analysis of small quantities of elements contained in the same subcellular structures. We identified senile plaques by observation using TEM and detected Al in amyloid fibers in the cores of senile plaques located in the hippocampus and the temporal lobe by EDX. Phosphorus and calcium were also present in the amyloid fibers. No Al could be detected in the extracellular space in senile plaques or in the cytoplasm of nerve cells. In this study, we demonstrated colocalization of Al and beta-amyloid (Abeta) peptides in amyloid fibers in the cores of senile plaques. The results support the following possibilities in the brains of patients with Alzheimer's disease: Al could be involved in the aggregation of Abeta peptides to form toxic fibrils; Al might induce Abeta peptides into the beta-sheet structure; and Al might facilitate iron-mediated oxidative reactions, which cause severe damage to brain tissues. PMID:19744735

  5. Properties of ceramic honeycomb cathodes

    NASA Astrophysics Data System (ADS)

    Friedman, M.; Myers, M. C.; Chan, Y.; Sethian, J. D.

    2008-04-01

    A high current electron beam was emitted from slabs of ceramic honeycomb that were placed 2mm in front of the primary electron emitters. Inside the ceramic honeycomb pores, the primary electrons are multiplied many folds by a secondary emission process creating plasma from which the electron beam was emitted. Measurements show that there was no anode-cathode gap closure during the pulse duration and a uniform current density distribution was observed on the anode. Contrary to the measurements of "conventional" large area field emission cathodes, no transit time instability was observed.

  6. Preparation and microwave absorption properties of foam-based honeycomb sandwich structures

    Microsoft Academic Search

    Yanfei He; Rongzhou Gong

    2009-01-01

    Radar-absorbing structures having foam-based honeycomb sandwich structures (FBHSS) were fabricated through a conventional foaming technique. Conductive fillers such as carbonyl iron\\/nickel fibers (CINF) and magnetic metal micropowder (MMP) were added to polyurethane foams so as to efficiently increase the absorbing capacity of FBHSS. A honeycomb sandwich structure, which was made of composite face sheets and foam cores, was used as

  7. A study of PV/T collector with honeycomb heat exchanger

    NASA Astrophysics Data System (ADS)

    Hussain, F.; Othman, M. Y. H.; Yatim, B.; Ruslan, H.; Sopian, K.; Ibarahim, Z.

    2013-11-01

    This paper present a study of a single pass photovoltaic/thermal (PV/T) solar collector combined with honeycomb heat exchanger. A PV/T system is a combination of photovoltaic panel and solar thermal components in one integrated system. In order to enhance the performance of the system, a honeycomb heat exchanger is installed horizontally into the channel located under the PV module. Air is used as the heat remover medium. The system is tested with and without the honeycomb at irradiance of 828 W/m2 and mass flow rate spanning from 0.02 kg/s to 0.13 kg/s. It is observed that the aluminum honeycomb is capable of enhancing the thermal efficiency of the system efficiently. At mass flow rate of 0.11 kg/s, the thermal efficiency of the system without honeycomb is 27% and with honeycomb is 87 %. Throughout the range of the mass flow rate, the electrical efficiency of the PV module improved by 0.1 %. The improved design is suitable to be further investigated as solar drying system and space heating.

  8. Processing and characterization of polycrystalline YAG (Yttrium Aluminum Garnet) core-clad fibers

    NASA Astrophysics Data System (ADS)

    Kim, Hyun Jun; Fair, Geoff E.; Potticary, Santeri A.; O'Malley, Matthew J.; Usechak, Nicholas G.

    2014-06-01

    Polycrystalline YAG fiber has recently attracted considerable attention for the role it could play as a fiber-laser gain media. This primarily due to its large surface-to-volume ratio, high stimulated Brillouin scattering threshold, and its high thermal conductivity; all of which are superior to that of silica-glass fibers. As a consequence, techniques which enable the fabrication of poly- and single-crystalline YAG fibers have recently been the focus of a number of efforts. In this work we have endeavored to reduce the scattering loss of polycrystalline-YAG-core fibers while simultaneously demonstrating optical gain by enhancing our processing techniques using feedback from mechanical testing and through the development of a technique to encase doped YAG-core fibers with un-doped YAG claddings. To this end we have recently fabricated fibers with both core and claddings made up of polycrystalline YAG and subsequently confirmed that they indeed guide light. In this paper, the processes leading to the fabrication of these fibers will be discussed along with their characterization.

  9. Prepreg effects on honeycomb composite manufacturing

    NASA Astrophysics Data System (ADS)

    Martin, Cary Joseph

    Fiber reinforced composites offer many advantages over traditional materials and are widely utilized in aerospace applications. Advantages include a high stiffness to weight ratio and excellent fatigue resistance. However, the pace of new implementation is slow. The manufacturing processes used to transform composite intermediates into final products are poorly understood and are a source of much variability. This limits new implementation and increases the manufacturing costs of existing designs. One such problem is honeycomb core crush, in which a core-stiffened structure collapses during autoclave manufacture, making the structure unusable and increasing the overall manufacturing cost through increased scrap rates. Consequently, the major goal of this research was to investigate the scaling of core crush from prepreg process-structure-property relations to commercial composite manufacture. The material dependent nature of this defect was of particular interest. A methodology and apparatus were developed to measure the frictional resistance of prepreg materials under typical processing conditions. Through a characterization of commercial and experimental prepregs, it was found that core crush behavior was the result of differences in prepreg frictional resistance. This frictional resistance was related to prepreg morphology and matrix rheology and elasticity. Resin composition and prepreg manufacturing conditions were also found to affect manufacturing behavior. Mechanical and dimensional models were developed and demonstrated utility for predicting this crushing behavior. Collectively, this work explored and identified the process-structure-property relations as they relate to the manufacture of composite materials and suggested several avenues by which manufacturing-robust materials may be developed.

  10. Impact-limiting materials characterization. [Structural and thermal testing of Al honeycombs and polyurethane foams

    SciTech Connect

    Glass, R. E. [Sandia National Labs., Albuquerque, NM (United States); Duffey, T. A. [Spectra Research Inst., Albuquerque, NM (United States); McConnell, P. [GRAM, Inc., Albuquerque, NM (United States)

    1991-01-01

    Goal in the design of an impact limiter (foams or honeycombs) for packaging of radioactive materials is to minimize the deceleration loads during a drop onto an unyielding target, and to reduce the effects of a fire. Methods are being developed for selecting impact-limiting materials. Figures of merit have been developed for screening both structural and thermal response; they have been applied to aluminum honeycombs and polyurethane foams. Three figures of merit are presented for the structural response, one figure for the thermal response (minimize the heat flux into the containment boundary). 11 figs., 6 refs. (DLC)

  11. High-Resolution Core Level Photoemission of Mg:Ag Deposited on Tris(8-hydroxyquinolato) Aluminum Probed by Synchrotron Radiation

    SciTech Connect

    Pi, T.-W. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Lin, H.-H.; Lee, H.-H.; Hwang, J. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2007-01-19

    Deposition of magnesium on tris(8-hydroxyquinolato) aluminum (Alq3) precovered with a thin silver dopant was investigated with high-resolution core-level photoemission via synchrotron radiation. First, the noble-metal dopant that make contact with the molecules reside at the vicinity of the pyridyl ring, similar to the case of the alkaline earth metals on Alq3. Further, a fit to this Alq3-derived Ag component delivers a non-zero Doniach-Sunjic singularity index of 0.061, suggesting that the incorporated Ag dopant behaves as a metallic cluster. Upon Mg adsorption on the Ag/Alq3 surface, the size of the Ag cluster remains intact, but its binding energy now appears lower than that of the bulk. The charge added onto the clusters comes from part of Mg which is mixed with Ag. As to the other part of the Mg atoms, they gather about the chelated oxygen. This is certainly in contrast to the case of Mg on Alq3 where Mg accumulates at the vicinity of the nitrogen atoms.

  12. Core polarization for the electric quadrupole moment of neutron-rich Aluminum isotopes

    E-print Network

    Kenichi Yoshida

    2009-02-18

    The core polarization effect for the electric quadrupole moment of the neutron-rich $^{31}$Al, $^{33}$Al and $^{35}$Al isotopes in the vicinity of the island of inversion are investigated by means of the microscopic particle-vibration coupling model in which the Skyrme Hartee-Fock-Bogoliubov and quasiparticle-random-phase approximation are used to calculate the single-quasiparticle wave functions and the excitation modes. It is found that the polarization charge for the proton $1d_{5/2}$ hole state in $^{33}$Al is quite sensitive to coupling to the neutrons in the $pf$-shell associated with the pairing correlations, and that the polarization charge in $^{35}$Al becomes larger due to the stronger collectivity of the low-lying quadrupole vibrational mode in the neighboring $^{36}$Si nucleus.

  13. Delamination buckling and propagation analysis of honeycomb panels using a cohesive element approach

    Microsoft Academic Search

    TONG-SEOK HAN; ANI URAL; CHUIN-SHAN CHEN; ALAN T. ZEHNDER; ANTHONY R. INGRAFFEA; SARAH L. BILLINGTON

    2002-01-01

    The cohesive element approach is proposed as a tool for simulating delamination propagation between a facesheet and a core in a honeycomb core composite panel. To determine the critical energy release rate (Gc) of the cohesive model, Double Cantilever Beam (DCB) fracture tests were performed. The peak strength (?c) of the cohesive model was determined from Flatwise Tension (FWT) tests.

  14. Update on the 6.5 meter Borosilicate Honeycomb Mirror

    NASA Astrophysics Data System (ADS)

    Angel, J. R. P.; Hill, J. M.; Woolf, N. J.

    1992-12-01

    In April 1992 the University of Arizona Mirror Lab successfully cast the first U.S. telescope mirror blank that exceeds in size the Hale telescope mirror cast in 1935. The new blank goes well beyond the simple ribbed form of the Hale casting in its use of a honeycomb sandwich structure to reduce weight, enhance stiffness and control thermal distortion. The blank weighs 10 tons, less than the 5 m and most 4 m blanks, despite its 72 cm edge thickness. Chunks of Ohara E6 borosilicate glass were melted at 1180 C over 1020 ceramic cores to form the internal honeycomb. Wind-induced distortion, a serious issue for large telescopes aiming at matching the best atmospheric seeing, is eliminated because of the high stiffness. The honeycomb blank is an order of magnitude stiffer than the same mass of glass in a meniscus blank. Similarly mirror seeing, often a limitation when seeing is half an arcsecond or better, is eliminated by ventilation of the very open structure. Ventilation of the honeycomb with ambient air allows the mirror to track the nighttime temperature with a time constant of 30 -- 40 minutes. After three months of cooling and annealing, the furnace was opened in June 1992. At the time of this writing, the blank is about to be lifted for removal of the internal mold parts that form the honeycomb structure in the one-piece casting. Optical finishing of the F/1.25 parabolic surface by diamond generating and stressed lap polishing will begin in 1993.

  15. Axial crush of metallic honeycombs

    Microsoft Academic Search

    Enboa Wu; Wu-Shung Jiang

    1997-01-01

    Experimental results for six types of honeycomb cellular structures under quasi-static and impact loads applied in the axial direction are reported. The specimens under both loading conditions were all back-supported with a steel block and were loaded by blunt impactors whose cross-sectional areas were larger than those of the specimens. In the impact test, the velocity history during impact was

  16. Structural Physics of Bee Honeycomb

    NASA Astrophysics Data System (ADS)

    Kaatz, Forrest; Bultheel, Adhemar; Egami, Takeshi

    2008-03-01

    Honeybee combs have aroused interest in the ability of honeybees to form regular hexagonal geometric constructs since ancient times. Here we use a real space technique based on the pair distribution function (PDF) and radial distribution function (RDF), and a reciprocal space method utilizing the Debye-Waller Factor (DWF) to quantify the order for a range of honeycombs made by Apis mellifera. The PDFs and RDFs are fit with a series of Gaussian curves. We characterize the order in the honeycomb using a real space order parameter, OP3, to describe the order in the combs and a two-dimensional Fourier transform from which a Debye-Waller order parameter, u, is derived. Both OP3 and u take values from [0, 1] where the value one represents perfect order. The analyzed combs have values of OP3 from 0.33 to 0.60 and values of u from 0.83 to 0.98. RDF fits of honeycomb histograms show that naturally made comb can be crystalline in a 2D ordered structural sense, yet is more `liquid-like' than cells made on `foundation' wax. We show that with the assistance of man-made foundation wax, honeybees can manufacture highly ordered arrays of hexagonal cells.

  17. Cellular Metal Truss Core Sandwich Structures**

    E-print Network

    Wadley, Haydn

    . Introduction Cellular metals have attracted interest as alternatives to honeycomb when used as the cores rigidity. Honeycomb core sandwich structures are the current state-of-the-art choice for weight sensitive of the porosity can trap moisture leading to corrosion. In space ap- plications, their skins are susceptible

  18. Edge states in honeycomb structures

    E-print Network

    Charles L. Fefferman; James P. Lee-Thorp; Michael I. Weinstein

    2015-06-28

    An edge state is a time-harmonic solution of a conservative wave system, e.g. Schr\\"odinger, Maxwell, which is propagating (plane-wave-like) parallel to, and localized transverse to, a line-defect or "edge." Topologically protected edge states are edge states which are stable against spatially localized (even strong) deformations of the edge. First studied in the context of the quantum Hall effect, protected edge states have attracted huge interest due to their role in the field of topological insulators. Theoretical understanding of topological protection has mainly come from discrete (tight-binding) models and direct numerical simulation. In this paper we consider a rich family of continuum PDE models for which we rigorously study regimes where topologically protected edge states exist. Our model is a class of Schroedinger operators on R^2 with a background two-dimensional honeycomb potential perturbed by an "edge-potential." The edge potential is a domain-wall interpolation, transverse to a prescribed "rational" edge, between two distinct periodic structures. General conditions are given for the bifurcation of a branch of topologically protected edge states from Dirac points of the background honeycomb structure. The bifurcation is seeded by the zero mode of a one-dimensional effective Dirac operator. A key condition is a spectral no-fold condition for the prescribed edge. We then use this result to prove the existence of topologically protected edge states along zigzag edges of certain honeycomb structures. Our results are consistent with the physics literature and appear to be the first rigorous results on the existence of topologically protected edge states for continuum 2D PDE systems. We also show that the family of Hamiltonians we study contains cases where zigzag edge states exist, but which are not topologically protected.

  19. Seal Leakages for Honeycomb or Smooth Configurations

    NASA Technical Reports Server (NTRS)

    Athavale, Mahesh M.; Hendricks, R. C.

    1997-01-01

    Three dimensional-CFD simulations were attempted to analyze the flow field in a honeycomb flat plate tester. This discussion reviews some of the numerical difficulties and relations, including those relating the honeycombs to labyrinth throttles and the consistency of selected seal and tester data sets.

  20. Fabrication and development of several heat pipe honeycomb sandwich panel concepts. Final report

    SciTech Connect

    Tanzer, H.J.

    1982-06-01

    The feasibility of fabricating and processing liquid metal heat pipes in a low mass honeycomb sandwich panel configuration for application on the NASA Langley airframe-integrated Scramjet engine was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts was evaluated within constraints dictated by existing manufacturing technology and equipment. The chosen design consists of an all-stainless steel structure, sintered screen facesheets, and two types of core-ribbon, a diffusion bonded wire mesh and a foil-screen composite. Cleaning, fluid charging, processing, and process port sealing techniques were established. The liquid metals, potassium, sodium and cesium were used as working fluids. Eleven honeycomb panels 15.24 cm X 15.24 cm X 2.94 cm were delivered to NASA Langley for extensive performance testing and evaluation, nine panels were processed as heat pipes, and two panels were left unprocessed.

  1. Acoustic scattering and radiation response of circular hexagonal and auxetic honeycomb shell structures

    NASA Astrophysics Data System (ADS)

    Iyer, Vaibhav Jagadeesan

    Sandwich panels with honeycomb cores are used in many engineering applications because of their high strength to weight ratio, vibration isolation and sound transmission loss characteristics. Previous studies indicate that such sandwich structures with auxetic honeycomb cores (negative in-plane Poisson's ratio) can have a higher sound transmission loss compared to a regular hexagonal honeycomb core structure. In this study, sound scattering and acoustic radiation characteristics of sandwich structures with hexagonal and auxetic cores arranged in a circular pattern interacting with exterior acoustic domains of both air and water have been investigated using finite element analysis. A novel in-plane honeycomb geometry is developed which provides for a gradual decrease in radial cell size and whole number of circumferential cells to generate a uniform distribution of cells in the circular shell. Adding more circumferential cells, enables outer honeycomb edges to approach a circular arc and provides a comparison between the circular honeycomb and a solid elastic cylinder shell with the same mass. Natural frequencies of the different shell structures in-vacuo have been extracted in the analysis range of 0-2000 Hz. It is observed that auxetic honeycomb has lower natural frequencies compared to regular honeycomb for the same mass indicating that the auxetic is more flexible. The acoustic scattering and radiation performance in terms of target strength (TS) defined as the magnitude of reflected/scattered wave pressure relative to the magnitude of the incident plane wave pressure is measured both on the scattering surface and far-field at both the back and front scattering point were studied in both air and water. In the case of interaction with air in the exterior acoustic region, the radiation response shows prominent resonance peaks at the in-vacuo natural frequencies of the elastic structures as expected. Results show that there are significant differences in target strength between the auxetic and regular honeycomb and elastic solid circular shell structures studied, with relative TS performance between the different shells depending on the frequency of the incident wave and the acoustic domain used.

  2. Constraints on formation processes of two coarse-grained calcium- aluminum-rich inclusions: a study of mantles, islands and cores

    USGS Publications Warehouse

    Meeker, G.P.

    1995-01-01

    Many coarse-grained calcium- aluminum-rich inclusions (CAIs) contain features that are inconsistent with equilibrium liquid crystallization models of origin. Spinel-free islands (SFIs) in spinel-rich cores of Type B CAIs are examples of such features. One model previously proposed for the origin of Allende 5241, a Type B1 CAI containing SFIs, involves the capture and assimilation of xenoliths by a liquid droplet in the solar nebula (El Goresy et al, 1985; MacPherson et al 1989). This study reports new textural and chemical zoning data from 5241 and identifies previously unrecognized chemical zoning patterns in the melilite mantle and in a SFI. -from Author

  3. Preparation of well-aligned carbon nanotubes\\/silicon nanowires core-sheath composite structure arrays in porous anodic aluminum oxide templates

    Microsoft Academic Search

    Mengke Li; Mei Lu; Chengwei Wang; Hulin Li

    2002-01-01

    The well-aligned carbon nanotubes (CNTs) arrays with opened ends were prepared in ordered pores of anodic aluminum oxide (AAO)\\u000a template by the chemical vapor deposition (CVD) method. After then, silicon nanowires (SiNWs) were deposited in the hollow\\u000a cavities of CNTs. By using this method, CNTs\\/SiNWs core-sheath composite structure arrays were synthesized successfully. Growing\\u000a structures and physical properties of the CNTs\\/SiNWs

  4. Honeycomb Mirrors for Large Telescopes

    NASA Astrophysics Data System (ADS)

    Hill, John; Martin, Hubert; Angel, Roger

    This chapter deals with the design, fabrication, and use of the borosilicateglass honeycomb mirrors which are being produced at the University ofArizona's Steward Observatory Mirror Laboratory. These mirrors are a coretechnology for the whole telescope, and a number of telescopes are nowoperational using these primary mirrors. The mirrors contribute to the telescopedesign because of their light weight, their high stiffness, and their shortthermal time constant. The light weight of the primary mirrors helps to keepthe weight of the entire telescope low and to maximize the structuralperformance. The ability to circulate air through the glass honeycombstructure allows control of local seeing in the telescope environment. Thehoneycomb sandwich is formed by spin casting borosilicate glass into aceramic fiber mold. The Mirror Lab has previously produced three 3.5-mmirrors, three 6.5-m mirrors, and two 8.4-m mirrors which are now operatingsuccessfully in telescopes. Results are highlighted from these telescopes withemphasis on the Large Binocular Telescope with two 8.4 m primaries.Excellent results have been obtained with adaptive secondary mirrorsin combination with the honeycomb primary mirrors. Two additional6.5-m mirrors and two additional 8.4-m mirrors have also been cast andare in various stages of production for other projects including the firstoff-axis segment for the future Giant Magellan Telescope. An additional keytechnology for large telescopes is the ability to fabricate high-precision primaryoptics with short focal lengths in order to keep the telescope structure andenclosure compact. The stressed lap allows efficient polishing of thesefast conic surfaces by actively adjusting its shape as it strokes across themirror.

  5. Viscoelastic Analysis of Sandwich Beams Having Aluminum and Fiber-reinforced Polymer Skins with a Polystyrene Foam Core

    E-print Network

    Roberts-Tompkins, Altramese L.

    2010-07-14

    . The stress, strain, and deformation fields during creep responses are analyzed. Parameters such as the viscosity of the foam core, the ratio of the skin and core thicknesses, the ratio of the skin and core moduli, and adhesive layers are varied...

  6. Vibration and acoustic properties of honeycomb sandwich structures subject to variable incident plane-wave angle pressure loads

    NASA Astrophysics Data System (ADS)

    Yan, Jiaxue

    Honeycomb structures are widely used in many areas for their material characteristics such as high strength-to-weight ratio, stiffness-to-weight, sound transmission, and other properties. Honeycomb structures are generally constructed from periodically spaced tessellations of unit cells. It can be shown that the effective stiffness and mass properties of honeycomb are controlled by the local geometry and wall thickness of the particular unit cells used. Of particular interest are regular hexagonal (6-sided) honeycomb unit cell geometries which exhibit positive effective Poisson's ratio, and modified 6-sided auxetic honeycomb unit cells with Poisson's ratio which is effectively negative; a property not found in natural materials. One important honeycomb meta-structure is sandwich composites designed with a honeycomb core bonded between two panel layers. By changing the geometry of the repetitive unit cell, and overall depth and material properties of the honeycomb core, sandwich panels with different vibration and acoustic properties can be designed to shift resonant frequencies and improve intensity and Sound Transmission Loss (STL). In the present work, a honeycomb finite element model based on beam elements is programmed in MATLAB and verified with the commercial finite element software ABAQUS for frequency extraction and direct frequency response analysis. The MATLAB program was used to study the vibration and acoustic properties of different kinds of honeycomb sandwich panels undergoing in-plane loading with different incident pressure wave angles and frequency. Results for the root mean square intensity IRMS based on normal velocity on the transmitted side of the panel measure vibration magnitude are reported for frequencies between 0 and 1000 Hz. The relationship between the sound transmission loss computed with ABAQUS and the inverse of the intensity of surface velocity is established. In the present work it is demonstrated that the general trend between the STL pressure response and the inverted intensity metric have similar response characteristics over both the stiffness frequency region and the resonance frequency region, showing that an increase in IRMS corresponds to a decrease in STL. The ABAQUS model was used to verify the MATLAB program for natural frequencies and mode shapes, and to compute the STL on the top surface of the honeycomb sandwich structure. Resonant peaks in the frequency response of intensity and STL are identified with natural frequencies and mode shapes of the honeycomb sandwich structure. A unique feature of this research is the ability to apply the time-harmonic acoustic pressure as a load on the transmitting surface of the honeycomb sandwich panel with variable incident angle ranging between 0° to 90°. When the incident angle is nonzero, the pressure load is complex valued, with sinusoidal distribution, and frequency dependent. The finite element implementation of the complex-valued variable incident pressure distribution is programmed in MATLAB to give complete control of the angle, frequency and distribution. Commercial finite element software such as ABAQUS has limited ability to directly apply frequency dependent and distributed real and imaginary pressure distributions in a direct steady state frequency analysis over a large number of frequency evaluations. In the present work, IRMS results for a family of honeycomb sandwich panels with systematic increment in internal cell wall angle, subject to incremental changes in incident angle pressure loads are studied and compared. Results show that for honeycomb sandwich panels with both positive and negative internal cell wall angle, on average, intensity for the nonzero incident angles is higher than the 0° normal incident angle. For the honeycomb sandwich panels with positive internal angle, the intensity consistently increases with larger nonzero incident angles. Furthermore, under the same incident angle pressure load, the intensity of honeycomb panel with positive internal angle is consistently larger than honeycomb panels with

  7. An experimental investigation of aluminum honeycomb as an energy absorber

    E-print Network

    Bland, William Joseph

    1964-01-01

    crushing force, respec- tively, for each specimen. Average crushing force for the square and circular head tests was determined using the trapezoidal rule for integra- tion of the curves in Figures 1 through 1V and dividing by the stroke distance...

  8. Fabrication and mechanical testing of glass fiber entangled sandwich beams: A comparison with honeycomb and foam sandwich beams

    Microsoft Academic Search

    Amir Shahdin; Laurent Mezeix; Christophe Bouvet; Joseph Morlier; Yves Gourinat

    2009-01-01

    The aim of this paper is the fabrication and mechanical testing of entangled sandwich beam specimens and the comparison of their results with standard sandwich specimens with honeycomb and foam as core materials. The entangled sandwich specimens have glass fiber cores and glass woven fabric as skin materials. The tested glass fiber entangled sandwich beams possess low compressive and shear

  9. Radiative heat transfer in honeycomb structures-New simple analytical and numerical approaches

    NASA Astrophysics Data System (ADS)

    Baillis, D.; Coquard, R.; Randrianalisoa, J.

    2012-06-01

    Porous Honeycomb Structures present the interest of combining, at the same time, high thermal insulating properties, low density and sufficient mechanical resistance. However, their thermal properties remain relatively unexplored. The aim of this study is the modelling of the combined heat transfer and especially radiative heat transfer through this type of anisotropic porous material. The equivalent radiative properties of the material are determined using ray-tracing procedures inside the honeycomb porous structure. From computational ray-tracing results, simple new analytical relations have been deduced. These useful analytical relations permit to determine radiative properties such as extinction, absorption and scattering coefficients and phase function functions of cell dimensions and optical properties of cell walls. The radiative properties of honeycomb material strongly depend on the direction of propagation. From the radiative properties computed, we have estimated the radiative heat flux passing through slabs of honeycomb core materials submitted to a 1-D temperature difference between a hot and a cold plate. We have compared numerical results obtained from Discrete Ordinate Method with analytical results obtained from Rosseland-Deissler approximation. This approximation is usually used in the case of isotropic materials. We have extended it to anisotropic honeycomb materials. Indeed a mean over incident directions of Rosseland extinction coefficient is proposed. Results tend to show that Rosseland-Deissler extended approximation can be used as a first approximation. Deviation on radiative conductivity obtained from Rosseland-Deissler approximation and from the Discrete Ordinated Method are lower than 6.7% for all the cases studied.

  10. Guided wave propagation in honeycomb sandwich structures using a piezoelectric actuator/sensor system

    NASA Astrophysics Data System (ADS)

    Song, F.; Huang, G. L.; Hudson, K.

    2009-12-01

    Due to the complex nature of such composite structures, an understanding of the guided wave propagation mechanism in honeycomb composite panels with different frequencies inherently imposes many challenges. In this paper, a numerical simulation is first conducted to investigate the wave propagation mechanism in honeycomb sandwich structures using piezoelectric actuators/sensors. In contrast to most of the previous work, elastic wave responses based on the real geometry of the honeycomb core are obtained by using the finite element method (FEM). Based on the simulation, the global guided waves in the composite can be observed when the loading frequency is low and the leaky guided waves in the skin panel are found when the loading frequency is sufficiently high. The applicability of the homogenization technique for a celled core is discussed. The effects of cell geometry on the wave propagation are also demonstrated. Experimental testing is finally conducted to validate the results of numerical simulation and very good agreement is observed. Specifically, some guided wave propagation characteristics such as group velocity dispersion and mode tuning capabilities with the presence of a honeycomb core are discussed.

  11. Ceramic honeycomb structures and the method thereof

    NASA Technical Reports Server (NTRS)

    Riccitiello, Salvatore R. (inventor); Cagliostro, Domenick E. (inventor)

    1987-01-01

    The subject invention pertains to a method of producing an improved composite-composite honeycomb structure for aircraft or aerospace use. Specifically, the subject invention relates to a method for the production of a lightweight ceramic-ceramic composite honeycomb structure, which method comprises: (1) pyrolyzing a loosely woven fabric/binder having a honeycomb shape and having a high char yield and geometric integrity after pyrolysis at between about 700 and 1,100 C; (2) substantially evenly depositing at least one layer of ceramic material on the pyrolyzed fabric/binder of step (1); (3) recovering the coated ceramic honeycomb structure; (4) removing the pyrolyzed fabric/binder of the structure of step (3) by slow pyrolysis at between 700 and 1000 C in between about a 2 to 5% by volume oxygen atmosphere for between about 0.5 and 5 hr.; and (5) substantially evenly depositing on and within the rigid hollow honeycomb structure at least one additional layer of the same or a different ceramic material by chemical vapor deposition and chemical vapor infiltration. The honeycomb shaped ceramic articles have enhanced physical properties and are useful in aircraft and aerospace uses.

  12. Perturbative approach to an exactly solved problem: Kitaev honeycomb model

    NASA Astrophysics Data System (ADS)

    Vidal, Julien; Schmidt, Kai Phillip; Dusuel, Sébastien

    2008-12-01

    We analyze the gapped phase of the Kitaev honeycomb model perturbatively in the isolated-dimer limit. Our analysis is based on the continuous unitary transformations method, which allows one to compute the spectrum as well as matrix elements of operators between eigenstates at high order. The starting point of our study consists of an exact mapping of the original honeycomb spin system onto a square-lattice model involving an effective spin and a hard-core boson. We then derive the low-energy effective Hamiltonian up to order 10 which is found to describe an interacting-anyon system, contrary to the order 4 result which predicts a free theory. These results give the ground-state energy in any vortex sector and thus also the vortex gap, which is relevant for experiments. Furthermore, we show that the elementary excitations are emerging free fermions composed of a hard-core boson with an attached spin- and phase-operator string. We also focus on observables and compute, in particular, the spin-spin correlation functions. We show that they admit a multiplaquette expansion that we derive up to order 6. Finally, we study the creation and manipulation of anyons with local operators, show that they also create fermions, and discuss the relevance of our findings for experiments in optical lattices.

  13. Thermographic nondestructive testing (TNDT) of honeycomb composite structural parts of Atlas space launch vehicles

    SciTech Connect

    Burleigh, D.D.; Kuhns, D.R.; Cowell, S.D.; Engel, J.E. [General Dynamics Space Systems Division, San Diego, CA (United States)

    1994-12-31

    Thermography is a means of recording the patterns of heat emission from a surface. Thermographic nondestructive testing (TNDT) uses this technology to detect sub-surface defects. Generally, a heat pulse is applied to a surface that is thermographically monitored. If a sub-surface defect exists that locally reduces or improves the thermal properties of the material, the surface thermal pattern will be perturbed over the defect. TNDT has been used successfully on a wide variety of composite laminates, filament-wound structures, sandwich structures, and foam-insulated cryogenic tanks. Both real structures with real delamination and impact damage, as well as test panels with simulated delaminations, face sheet disbonds, and interply implants have been tested. For some of these applications, TNDT is the best technique. The thrust structure at the aft end of the Atlas space launch vehicle is a composite sandwich comprised of aluminum honeycomb core with fiberglass/phenolic face sheets. The surface area of this structure is approximately 600 ft{sup 2}. In 1992, General Dynamics Space Systems Division (GDSS) began using TNDT for quality verification of these complex composite parts. TNDT has been used on these parts during manufacture and assembly, and on the launch pad at Cape Canaveral. The NDT technique previously used on these parts, since their design in 1957, was ``coin tap.`` Compared to this method, TNDT provides a greatly improved inspection in less time and at a lower cost. A heat gun with a diffuser attachment is used to heat the inspection area while the area is monitored thermographically. TNDT is a rapid, remote, non-contact, highly portable, real-time scanning technique that can provide a well-documented video record of subsurface structural details including facesheet disbonds and skin delaminations. A specification and test procedure has been written, equipment has been procured, and personnel have been trained and certified.

  14. Viscoelastic Analysis of Sandwich Beams Having Aluminum and Fiber-reinforced Polymer Skins with a Polystyrene Foam Core 

    E-print Network

    Roberts-Tompkins, Altramese L.

    2010-07-14

    material (UMAT) subroutine in ABAQUS FE code is utilized to incorporate the viscoelastic constitutive model for the foam core. Analytical models and experimental data available in the literature are used to verify the results obtained from the FE analysis...

  15. Synthetic magnetic fluxes on the honeycomb lattice

    SciTech Connect

    Gorecka, Agnieszka [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Gremaud, Benoit [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Laboratoire Kastler Brossel, Ecole Normale Superieure, CNRS, UPMC, 4 Place Jussieu, FR-75005 Paris (France); Miniatura, Christian [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Institut Non Lineaire de Nice, UMR 6618, UNS, CNRS, 1361 Route des Lucioles, FR-06560 Valbonne (France); Institute of Advanced Studies, Nanyang Technological university, 60 Nanyang View, Singapore 639673 (Singapore)

    2011-08-15

    We devise experimental schemes that are able to mimic uniform and staggered magnetic fluxes acting on ultracold two-electron atoms, such as ytterbium atoms, propagating in a honeycomb lattice. The atoms are first trapped into two independent state-selective triangular lattices and then further exposed to a suitable configuration of resonant Raman laser beams. These beams induce hops between the two triangular lattices and make atoms move in a honeycomb lattice. Atoms traveling around each unit cell of this honeycomb lattice pick up a nonzero phase. In the uniform case, the artificial magnetic flux sustained by each cell can reach about two flux quanta, thereby realizing a cold-atom analog of the Harper model with its notorious Hofstadter's butterfly structure. Different condensed-matter phenomena such as the relativistic integer and fractional quantum Hall effects, as observed in graphene samples, could be targeted with this scheme.

  16. CRUSHING BEHAVIOUR OF ALUMINIUM HONEYCOMBS UNDER IMPACT LOADING

    Microsoft Academic Search

    Han Zhao; G?rard Gary

    1998-01-01

    Understanding the crushing behaviour of honeycombs under dynamic loading is useful for crash simulations of vehicles and for design of impacting energy absorbers. Available experimental techniques, however, are not always able to provide satisfactory precision for tests on honeycombs under impact loading. This paper presents a new application of the Split Hopkinson Pressure Bar (SHPB) for testing honeycombs. Viscoelastic bars

  17. Experimental rotordynamic coefficient results for honeycomb seals

    NASA Technical Reports Server (NTRS)

    Elrod, David A.; Childs, Dara W.

    1988-01-01

    Test results (leakage and rotordynamic coefficients) are presented for seven honeycomb-stator smooth-rotor seals. Tests were carried out with air at rotor speeds up to 16,000 cpm and supply pressures up to 8.2 bars. Test results for the seven seals are compared, and the most stable configuration is identified based on the whirl frequency ratio. Results from tests of a smooth-rotor/smooth-stator seal, a teeth-on-stator labyrinth seal, and the most stable honeycomb seal are compared.

  18. Honeycomb artificial spin ice at low temperatures

    NASA Astrophysics Data System (ADS)

    Zeissler, Katharina; Chadha, Megha; Cohen, Lesley; Branford, Will

    2015-03-01

    Artificial spin ice is a macroscopic playground for magnetically frustrated systems. It consists of a geometrically ordered but magnetically frustrated arrangement of ferromagnetic macros spins, e.g. an arrangement of single domain ferromagnetic nanowires on a honeycomb lattice. Permalloy and cobalt which have critical temperature scales far above 290 K, are commonly used in the construction of such systems. Previous measurements have shown unusual features in the magnetotransport signature of cobalt honeycomb artificial spin ice at temperatures below 50 K which are due to changes in the artificial spin ice's magnetic reversal. In that case, the artificial spin ice bars were 1 micron long, 100 nm wide and 20 nm thick. Here we explore the low temperature magnetic behavior of honeycomb artificial spin ice structures with a variety of bar dimensions, indirectly via electrical transport, as well as, directly using low temperature magnetic imaging techniques. We discuss the extent to which this change in the magnetic reversal at low temperatures is generic to the honeycomb artificial spin ice geometry and whether the bar dimensions have an influence on its onset temperature. The EPSRC (Grant No. EP/G004765/1; Grant No. EP/L504786/1) and the Leverhulme Trust (Grant No. RPG 2012-692) funded this scientific work.

  19. Honeycomb Betavoltaic Battery for Space Applications

    Microsoft Academic Search

    Jin R. Lee; Ben Ulmen; George H. Miley

    2008-01-01

    Radioisotopic batteries offer advantages relative to conventional chemical batteries for applications requiring a long lifetime with minimum maintenance. Thus, thermoelectric type cells fueled with Pu have been used extensively on NASA space missions. The design for a small beta battery using nickel-63 (Ni-63) and a vacuum direct collection method is described here. A honeycomb nickel wire structure is employed to

  20. Aluminum: Reflective Aluminum Chips

    SciTech Connect

    Recca, L.

    1999-01-29

    This fact sheet reveals how the use of reflective aluminum chips on rooftops cuts down significantly on heat absorption, thus decreasing the need for air conditioning. The benefits, including energy savings that could reach the equivalent of 1.3 million barrels of oil annually for approximately 100,000 warehouses, are substantial.

  1. Titanium honeycomb acoustic lining structural and thermal test report. [for acoustic tailpipe for JT8D engine

    NASA Technical Reports Server (NTRS)

    Joynes, D.; Balut, J. P.

    1974-01-01

    The results are presented of static, fatigue and thermal testing of titanium honeycomb acoustic panels representing the acoustic tailpipe for the Pratt and Whitney Aircraft JT8D Refan engine which is being studied for use on the Boeing 727-200 airplane. Test specimens represented the engine and tailpipe flange joints, the rail to which the thrust reverser is attached and shear specimens of the tailpipe honeycomb. Specimens were made in four different batches with variations in configuration, materials and processes in each. Static strength of all test specimens exceeded the design ultimate load requirements. Fatigue test results confirmed that aluminum brazed titanium, as used in the Refan tailpipe design, meets the fatigue durability objectives. Quality of welding was found to be critical to life, with substandard welding failing prematurely, whereas welding within the process specification exceeded the panel skin life. Initial fatigue testing used short grip length bolts which failed prematurely. These were replaced with longer bolts and subsequent testing demonstrated the required life. Thermal tests indicate that perforated skin acoustic honeycomb has approximately twice the heat transfer of solid skin honeycomb.

  2. Radiated Sound Power from a Curved Honeycomb Panel

    NASA Technical Reports Server (NTRS)

    Robinson, Jay H.; Buehrle, Ralph D.; Klos, Jacob; Grosveld, Ferdinand W.

    2003-01-01

    The validation of finite element and boundary element model for the vibro-acoustic response of a curved honeycomb core composite aircraft panel is completed. The finite element and boundary element models were previously validated separately. This validation process was hampered significantly by the method in which the panel was installed in the test facility. The fixture used was made primarily of fiberboard and the panel was held in a groove in the fiberboard by a compression fitting made of plastic tubing. The validated model is intended to be used to evaluate noise reduction concepts from both an experimental and analytic basis simultaneously. An initial parametric study of the influence of core thickness on the radiated sound power from this panel, using this numerical model was subsequently conducted. This study was significantly influenced by the presence of strong boundary condition effects but indicated that the radiated sound power from this panel was insensitive to core thickness primarily due to the offsetting effects of added mass and added stiffness in the frequency range investigated.

  3. Engineering polar discontinuities in honeycomb lattices.

    PubMed

    Gibertini, Marco; Pizzi, Giovanni; Marzari, Nicola

    2014-01-01

    Unprecedented and fascinating phenomena have been recently observed at oxide interfaces between centrosymmetric cubic materials, where polar discontinuities can give rise to polarization charges and electric fields that drive a metal-insulator transition and the appearance of a two-dimensional electron gas. Lower-dimensional analogues are possible, and honeycomb lattices offer a fertile playground, thanks to their versatility and the extensive ongoing experimental efforts in graphene and related materials. Here we suggest different realistic pathways to engineer polar discontinuities in honeycomb lattices and support these suggestions with extensive first-principles calculations. Several approaches are discussed, based on (i) nanoribbons, where a polar discontinuity against the vacuum emerges, and (ii) functionalizations, where covalent ligands are used to engineer polar discontinuities by selective or total functionalization of the parent systems. All the cases considered have the potential to deliver innovative applications in ultra-thin and flexible solar-energy devices and in micro- and nano-electronics. PMID:25300521

  4. Thermographic Inspection of Metallic Honeycomb Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Taylor, John O.; Dupont, H. M.

    1998-01-01

    The X-33/VentureStar has a Thermal Protection System (TPS) consisting mainly of brazed metallic honeycomb sandwich structures. Inspection of these structures is changing as a result of the extremely thin (less than 200 microns) skins, the small critical defect size (less than 2 mm long by 100 microns wide) and the large number (more than 1000) of parts to be inspected. Pulsed Infrared Thermography has been determined to be the most appropriate inspection method for manufacturing inspection based on performance comparison with other methods, cost, schedule and other factors. The results of the assessment of the different methods will be summarized and data on the performance of the final production inspection system will be given. Finite difference thermal methods have been used to model the whole inspection process. Details of correlation between the models and experimental data will be given and data on the use of pulsed infrared thermography on other metallic honeycomb sandwich structures will be given.

  5. Microdischarges in ceramic foams and honeycombs

    NASA Astrophysics Data System (ADS)

    Hensel, K.

    2009-08-01

    Microdischarges in spatially confined geometries, such as microcavities and micropores of various materials, present a promising method for the generation and maintenance of stable discharges at atmospheric pressure. They have been successfully used in many biomedical, environmental and industrial applications. The paper presents two relatively new types of discharges in confined volumes - a capillary microdischarge in ceramic foams and a sliding discharge inside the capillaries of ceramic honeycombs - and describes their basic physical properties and mechanisms. Microdischarges inside the microporous ceramic foams develop from the surface barrier discharge if the amplitude of the applied voltage reaches given threshold, but only for a specific pore size. Sliding discharge inside the honeycomb capillaries is produced by a combination of AC barrier discharge inside catalytic pellet bed coupled in series with DC powered honeycomb monolith. Both discharges produce relatively cold microplasmas with high level of non-equilibrium. The basic characteristics of the microdischarges, addressing the effects of the applied voltage, discharge power, pore size, length and diameter of the capillaries are discussed.

  6. Mechanics and applications of pressure adaptive honeycomb

    NASA Astrophysics Data System (ADS)

    Vos, Roelof

    A novel adaptive aerostructure is presented that relies on certified aerospace materials and can therefore be applied in conventional passenger aircraft. This structure consists of a honeycomb material which' cells extend over a significant length perpendicular to the plane of the cells. Each of the cells contains an inelastic pouch (or bladder) that forms a circular tube when the cell forms a perfect hexagon. By changing the cell differential pressure (CDP) the stiffness of the honeycomb can be altered. Using an external force or the elastic force within the honeycomb material, the honeycomb can be deformed such that the cells deviate from their perfect-hexagonal shape. It can be shown that by increasing the CDP, the structure eventually returns to a perfect hexagon. By doing so, a fully embedded pneumatic actuator is created that can perform work and substitute conventional low-bandwidth flight control actuators. It is shown that two approaches can be taken to regulate the stiffness of this embedded actuator: (1) The first approach relies on the pouches having a fixed amount of air in them and stiffness is altered by a change in ambient pressure. Coupled to the ambient pressure-altitude cycle that aircraft encounter during each flight, this approach yields a true adaptive aerostructure that operates independently of pilot input and is controlled solely by the altitude the aircraft is flying at. (2) The second approach relies on a controlled constant CDP. This CDP could be supplied from one of the compressor stages of the engine as a form of bleed air. Because of the air-tight pouches there would essentially be no mass flow, meaning engine efficiency would not be significantly affected due to this application. By means of a valve system the pilot could have direct control over the pressure and, consequently, the stiffness of the structure. This allows for much higher CDPs (on the order of 1MPa) than could physically be achieved by relying on the ambient pressure decrease with altitude. This option does require more infrastructure like tubing, valves, and supporting electronics from the cockpit. Applications of pressure adaptive honeycomb are tailored primarily towards low-bandwidth applications like secondary flight control. The most profound application is the morphing of an entire wing section, from leading to trailing edge, due to the adaptive honeycomb. On a smaller scale, other examples include a solid state pressure adaptive flap, a pressure adaptive droop nose, a pressure adaptive Gurney flap and a pressure adaptive engine inlet. Each of these applications is based on the same principle of stiffness alteration with pressure and can be used with either actuation option (constant mass or constant pressure). A model that relates the volumetric change of the honeycomb cells to the external blocked stress was shown to correlate well to experiments that were carried out on several test articles. Based on this model it was estimated that pressure adaptive honeycomb has a maximum mass-specific energy density of 12.4J/g, for the case of an externally applied CDP of 0.9MPa (can be supplied from a high-pressure compressor stage of a gas turbine). In addition, it was shown that a maximum strain of 76% can be achieved and that the maximum blocked stress amounts to 0.82MPa. In the case of a 40kPa drop in atmospheric pressure and constant mass of air in the pouches, the maximum mass specific energy amounts to 1.1J/g and a maximum blocked force of 70kPa can be attained. Pressure adaptive honeycomb was embedded into a 25%c adaptive flap on a NACA2412 wing section with a chord of 1.08m. Wind tunnel tests at Reynolds number of 1 million demonstrated a shift in the cl -- alpha curve upwards by an average of 0.3, thereby increasing the maximum lift coefficient from 1.27 to 1.52. This successfully demonstrated the application of pressure adaptive honeycomb embedded in a morphing aircraft structure.

  7. Optimal Fractal-Like Hierarchical Honeycombs

    NASA Astrophysics Data System (ADS)

    Oftadeh, Ramin; Haghpanah, Babak; Vella, Dominic; Boudaoud, Arezki; Vaziri, Ashkan

    2014-09-01

    Hexagonal honeycomb structures are known for their high strength and low weight. We construct a new class of fractal-appearing cellular metamaterials by replacing each three-edge vertex of a base hexagonal network with a smaller hexagon and iterating this process. The mechanical properties of the structure after different orders of the iteration are optimized. We find that the optimal structure (with highest in-plane stiffness for a given weight ratio) is self-similar but requires higher order hierarchy as the density vanishes. These results offer insights into how incorporating hierarchy in the material structure can create low-density metamaterials with desired properties and function.

  8. Optimal fractal-like hierarchical honeycombs.

    PubMed

    Oftadeh, Ramin; Haghpanah, Babak; Vella, Dominic; Boudaoud, Arezki; Vaziri, Ashkan

    2014-09-01

    Hexagonal honeycomb structures are known for their high strength and low weight. We construct a new class of fractal-appearing cellular metamaterials by replacing each three-edge vertex of a base hexagonal network with a smaller hexagon and iterating this process. The mechanical properties of the structure after different orders of the iteration are optimized. We find that the optimal structure (with highest in-plane stiffness for a given weight ratio) is self-similar but requires higher order hierarchy as the density vanishes. These results offer insights into how incorporating hierarchy in the material structure can create low-density metamaterials with desired properties and function. PMID:25238362

  9. Honeycomb architecture of carbon quantum dots: a new efficient substrate to support gold for stronger SERS.

    PubMed

    Fan, Yueqiong; Cheng, Huhu; Zhou, Ce; Xie, Xuejun; Liu, Yong; Dai, Liming; Zhang, Jing; Qu, Liangti

    2012-03-01

    The rational assembly of quantum dots (QDs) in a geometrically well-defined fashion opens up the possibility of accessing the full potential of the material and allows new functions of the assembled QDs to be achieved. In this work, well-confined two-dimensional (2D) and 3D carbon quantum dot (CQD) honeycomb structures have been assembled by electrodeposition of oxygen-rich functional CQDs within the interstitial voids of assemblies of SiO(2) nanospheres, followed by extraction of the SiO(2) cores with HF treatment. Although made from quantum sized carbon dots, the CQD assemblies present a solid porous framework, which can be further used as a sacrificial template for the fabrication of new nanostructures made from other functional materials. Based on the unique honeycomb architecture of the CQDs, which allows the more efficient adsorption of molecules, the formed Au nanoparticles on the CQD honeycomb exhibit 8-11 times stronger surface enhanced Raman scattering (SERS) effect than the widely used Au nanoparticle SERS substrate for the highly sensitive detection of target molecules. This work provides a new approach for the design and fabrication of ultrasensitive SERS platforms for various applications. PMID:22297623

  10. Cryogenic performance of slotted brazed Rene 41 honeycomb panels

    NASA Technical Reports Server (NTRS)

    Hepler, A. K.; Swegle, A. R.

    1982-01-01

    Two brazed Rene 41 honeycomb panels that would incorporate a frame element were designed, fabricated and tested. The panels were representative of the lower surface of an advanced space transportation vehicle. The first panel was a two span panel supported by a center frame and on edges parallel to it. The second panel was a two span panel supported by a center frame and on edges parallel to it. The second panel was a three span panel supported on two frames and on edges parallel to the frames. Each panel had its outer skin slotted to reduce the thermal stresses of the panel skins. The first panel was tested under simulated boost conditions that included liquid hydrogen exposure of the frame and inner skin and radiant heat to 478K on the outer skins. The first panel was tested to investigate the effect of thermal stresses in skins and core caused by the panel being restrained by a cold integral frame and to observe the effects of frost formation and possible liquid air development in and around outer skin slots.

  11. Application of Air Coupled Acoustic Thermography (ACAT) for Inspection of Honeycomb Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Winfree, William P.; Zalameda, Joseph N.; Pergantis, Charles; Flanagan, David; Deschepper, Daniel

    2009-01-01

    The application of a noncontact air coupled acoustic heating technique is investigated for the inspection of advanced honeycomb composite structures. A weakness in the out of plane stiffness of the structure, caused by a delamination or core damage, allows for the coupling of acoustic energy and thus this area will have a higher temperature than the surrounding area. Air coupled acoustic thermography (ACAT) measurements were made on composite sandwich structures with damage and were compared to conventional flash thermography. A vibrating plate model is presented to predict the optimal acoustic source frequency. Improvements to the measurement technique are also discussed.

  12. Aluminum Boats

    NSDL National Science Digital Library

    2012-06-26

    Test the buoyancy of an aluminum foil boat and an aluminum foil ball. Why does the same material in different shapes sink or float? This activity explores the fact that the amount of water pushed aside by an object equals the force of water pushing upward on the object.

  13. Active inflatable auxetic honeycomb structural concept for morphing wingtips

    NASA Astrophysics Data System (ADS)

    Sun, Jian; Gao, Hongliang; Scarpa, Fabrizio; Lira, Cristian; Liu, Yanju; Leng, Jinsong

    2014-12-01

    This paper describes a new concept of an active honeycomb structure for morphing wingtip applications based on tubular inflatable systems and an auxetic cellular structure. A work-energy model to predict the output honeycomb displacement versus input pressure is developed together with a finite element formulation, and the results are compared with the data obtained from a small-scale example of an active honeycomb. An analysis of the hysteresis associated with multiple cyclic loading is also provided, and design considerations for a larger-scale wingtip demonstrator are made.

  14. Nuclear design analysis of square-lattice honeycomb space nuclear rocket engine

    NASA Astrophysics Data System (ADS)

    Widargo, Reza; Anghaie, Samim

    1999-01-01

    The square-lattice honeycomb reactor is designed based on a cylindrical core that is determined to have critical diameter and length of 0.50 m and 0.50 c, respectively. A 0.10-cm thick radial graphite reflector, in addition to a 0.20-m thick axial graphite reflector are used to reduce neutron leakage from the reactor. The core is fueled with solid solution of 93% enriched (U, Zr, Nb)C, which is one of several ternary uranium carbides that are considered for this concept. The fuel is to be fabricated as 2 mm grooved (U, Zr, Nb)C wafers. The fuel wafers are used to form square-lattice honeycomb fuel assemblies, 0.10 m in length with 30% cross-sectional flow area. Five fuel assemblies are stacked up axially to form the reactor core. Based on the 30% void fraction, the width of the square flow channel is about 1.3 mm. The hydrogen propellant is passed through these flow channels and removes the heat from the reactor core. To perform nuclear design analysis, a series of neutron transport and diffusion codes are used. The preliminary results are obtained using a simple four-group cross-section model. To optimize the nuclear design, the fuel densities are varied for each assembly. Tantalum, hafnium and tungsten are considered and used as a replacement for niobium in fuel material to provide water submersion sub-criticality for the reactor. Axial and radial neutron flux and power density distributions are calculated for the core. Results of the neutronic analysis indicate that the core has a relatively fast spectrum. From the results of the thermal hydraulic analyses, eight axial temperature zones are chosen for the calculation of group average cross-sections. An iterative process is conducted to couple the neutronic calculations with the thermal hydraulics calculations. Results of the nuclear design analysis indicate that a compact core can be designed based on ternary uranium carbide square-lattice honeycomb fuel. This design provides a relatively high thrust to weight ratio.

  15. Thermal hydraulic design analysis of ternary carbide fueled square-lattice honeycomb nuclear rocket engine

    NASA Astrophysics Data System (ADS)

    Furman, Eric M.; Anghaie, Samim

    1999-01-01

    A computational analysis is conducted to determine the optimum thermal-hydraulic design parameters for a square-lattice honeycomb nuclear rocket engine core that will incorporate ternary carbide based uranium fuels. Recent studies at the Innovative Nuclear Space Power and Propulsion Institute (INSPI) have demonstrated the feasibility of processing solid solution, ternary carbide fuels such as (U, Zr, Nb)C, (U, Zr, Ta)C, (U, Zr, Hf)C and (U, Zr, W)C. The square-lattice honeycomb design provides high strength and is amenable to the processing complexities of these ultrahigh temperature fuels. A parametric analysis is conducted to examine how core geometry, fuel thickness and the propellant flow area effect the thermal performance of the nuclear rocket engine. The principal variables include core size (length and diameter) and fuel element dimensions. The optimum core configuration requires a balance between high specific impulse and thrust level performance, and maintaining the temperature and strength limits of the fuel. A nuclear rocket engine simulation code is developed and used to examine the system performance as well as the performance of the main reactor core components. The system simulation code was originally developed for analysis of NERVA-Derivative and Pratt & Whitney XNR-2000 nuclear thermal rockets. The code is modified and adopted to the square-lattice geometry of the new fuel design. Thrust levels ranging from 44,500 to 222,400 N (10,000 to 50,000 lbf) are considered. The average hydrogen exit temperature is kept at 2800 K, which is well below the melting point of these fuels. For a nozzle area ratio of 300 and a thrust chamber pressure of 4.8 Mpa (700 psi), the specific impulse is 930 s. Hydrogen temperature and pressure distributions in the core and the fuel maximum temperatures are calculated.

  16. Solvent Tuned Azido-Bridged Co2+ Layers: Square, Honeycomb,

    E-print Network

    Gao, Song

    Solvent Tuned Azido-Bridged Co2+ Layers: Square, Honeycomb, and Kagomé Xin-Yi Wang, Lu Wang, Zhe-Ming Wang, Song Gao* College of Chemistry and Molecular Engineering, State Key Laboratory of Rare Earth

  17. Dynamics of artificial spin ice: a continuous honeycomb network

    E-print Network

    Shen, Yichen

    We model the dynamics of magnetization in an artificial analogue of spin ice specializing to the case of a honeycomb network of connected magnetic nanowires. The inherently dissipative dynamics is mediated by the emission ...

  18. Optimal Fractal-Like Hierarchical Honeycombs Ramin Oftadeh,1

    E-print Network

    Vaziri, Ashkan

    .e., zeroth) to fourth order hierarchical honeycombs fabricated using 3D printing. The physical thickness of the structures is constant, tn ¼ 2 mm, because of the limitations of the 3D printing. To maintain the structure

  19. Elastic constants for superplastically formed/diffusion-bonded corrugated sandwich core

    NASA Technical Reports Server (NTRS)

    Ko, W. L.

    1980-01-01

    Formulas and associated graphs for evaluating the effective elastic constants for a superplastically formed/diffusion bonded (SPF/DB) corrugated sandwich core, are presented. A comparison of structural stiffnesses of the sandwich core and a honeycomb core under conditions of equal sandwich core density was made. The stiffness in the thickness direction of the optimum SPF/DB corrugated core (that is, triangular truss core) is lower than that of the honeycomb core, and that the former has higher transverse shear stiffness than the latter.

  20. Aluminum Analysis.

    ERIC Educational Resources Information Center

    Sumrall, William J.

    1998-01-01

    Presents three problems based on the price of aluminum designed to encourage students to be cooperative and to use an investigative approach to learning. Students collect and synthesize information, analyze results, and draw conclusions. (AIM)

  1. New concept in brazing metallic honeycomb panels

    NASA Technical Reports Server (NTRS)

    Carter, P. D.; Layton, R. E.; Stratton, F. W.

    1973-01-01

    Aluminum oxide coating provides surface which will not be wetted by brazing alloy and which stops metallic diffusion welding of tooling materials to part being produced. This method eliminates loss of tooling materials and parts from braze wetting and allows fall-apart disassembly of tooling after brazing.

  2. Development of Rene' 41 honeycomb structure as an integral cryogenic tankage/fuselage concept for future space transportation systems

    NASA Technical Reports Server (NTRS)

    Shideler, J. J.; Swegle, A. R.; Fields, R. A.

    1982-01-01

    The status of the structural development of an integral cryogenic-tankage/hot-fuselage concept for future space transportation systems (STS) is discussed. The concept consists of a honeycomb sandwich structure which serves the combined functions of containment of cryogenic fuel, support of vehicle loads, and thermal protection from an entry heating environment. The inner face sheet is exposed to a cryogenic (LH2) temperature of -423 F during boost; and the outer face sheet, which is slotted to reduce thermal stress, is exposed to a maximum temperature of 1400 F during a high altitude, gliding entry. A fabrication process for a Rene' 41 honeycomb sandwich panel with a core density less than 1 percent was developed which is consistent with desirable heat treatment processes for high strength.

  3. Development of Rene 41 honeycomb structure as an integral cryogenic tankage/fuselage concept for future space transportation systems

    NASA Technical Reports Server (NTRS)

    Shideler, J. L.; Swegle, A. R.; Fields, R. A.

    1982-01-01

    The status of the structural development of an integral cryogenic-tankage/hot-fuselage concept for future space transportation systems is reviewed. The concept comprises a honeycomb sandwich structure that serves the combined functions of containing the cryogenic fuel, supporting the vehicle loads, and protecting the spacecraft from entry heating. The inner face sheet is exposed to cryogenic temperature of -423 F during boost; the outer face sheet, which is slotted to reduce thermal stress, is exposed to a maximum temperature of 1400 F during a high-altitude gliding entry. Attention is given to the development of a fabrication process for a Rene 41 honeycomb sandwich panel with a core density of less than 1 percent that is consistent with desirable heat treatment processes for high strength.

  4. Analysis of propagation characteristics of flexural wave in honeycomb sandwich panel and design of loudspeaker for radiating inclined sound

    NASA Astrophysics Data System (ADS)

    Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

    2015-07-01

    A loudspeaker for an auditory guiding system is proposed. This loudspeaker utilizes inclined sound transformed from a flexural wave in a honeycomb sandwich panel. We focused on the fact that the inclined sound propagates extensively with uniform level and direction. Furthermore, sound can be generated without group delay dispersion because the phase velocity of the flexural wave in the sandwich panel becomes constant with increasing frequency. These characteristics can be useful for an auditory guiding system in public spaces since voice-guiding navigation indicates the right direction regardless of position on a pathway. To design the proposed loudspeaker, the behavior of the sandwich panel is predicted using a theoretical equation in which the honeycomb core is assumed as an orthotropic continuum. We calculated the phase velocity dispersion of the flexural wave in the sandwich panel and compared the results obtained using the equation with those of a simulation based on the finite element method and an experiment in order to confirm the applicability of the theoretical equation. It was confirmed that the phase velocities obtained using the theoretical equation and by the simulation were in good agreement with that obtained experimentally. The obtained results suggest that the behavior of the sandwich panel can be predicted using the parameters of the panel. In addition, we designed an optimized honeycomb sandwich panel for radiating inclined sound by calculating the phase velocity characteristics of various panels that have different parameters of core height and cell size using the theoretical equation. Sound radiation from the optimized panel was simulated and compared with that of a homogeneous plate. It was clear that the variance of the radiation angle with varying frequency of the optimized panel was smaller than that of the homogeneous plate. This characteristic of sound radiation with a uniform angle is useful for indicating the destination direction. On the basis of this fact, we established a design method of the flat-panel loudspeaker for generating inclined sound using a honeycomb sandwich panel.

  5. Mesoporous aluminum phosphite

    SciTech Connect

    El Haskouri, Jamal, E-mail: haskouri@uv.e [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain); Perez-Cabero, Monica; Guillem, Carmen; Latorre, Julio; Beltran, Aurelio; Beltran, Daniel [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain); Amoros, Pedro, E-mail: pedro.amoros@uv.e [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain)

    2009-08-15

    High surface area pure mesoporous aluminum-phosphorus oxide-based derivatives have been synthesized through an S{sup +}I{sup -} surfactant-assisted cooperative mechanism by means of a one-pot preparative procedure from aqueous solution and starting from aluminum atrane complexes and phosphoric and/or phosphorous acids. A soft chemical extraction procedure allows opening the pore system of the parent as-prepared materials by exchanging the surfactant without mesostructure collapse. The nature of the pore wall can be modulated from mesoporous aluminum phosphate (ALPO) up to total incorporation of phosphite entities (mesoporous aluminum phosphite), which results in a gradual evolution of the acidic properties of the final materials. While phosphate groups in ALPO act as network building blocks (bridging Al atoms), the phosphite entities become basically attached to the pore surface, what gives practically empty channels. The mesoporous nature of the final materials is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N{sub 2} adsorption-desorption isotherms. The materials present regular unimodal pore systems whose order decreases as the phosphite content increases. NMR spectroscopic results confirm the incorporation of oxo-phosphorus entities to the framework of these materials and also provide us useful information concerning the mechanism through which they are formed. - Abstract: TEM image of the mesoporous aluminum phosphite showing the hexagonal disordered pore array that is generated by using surfactant micelles as template. Also a scheme emphasizing the presence of an alumina-rich core and an ALPO-like pore surface is presented.

  6. Steps Toward 8M Honeycomb Mirror Blanks: III. 1.8m Honeycomb Sandwich Blanks Cast From Borosilicate Glass

    NASA Astrophysics Data System (ADS)

    Angel, J. R. P.; Hill, J. M.

    1983-11-01

    As part of a program leading to the production of 8m honeycomb mirrors, we have recently made two 1.8m blanks. These have honeycomb sandwich form, with hexagonal honeycomb ribs sandwiched between front and back plates. Each is cast in one piece from borosilicate glass, using techniques that can be extended to larger sizes. Pieces of the glass are melted together in a circular container made of hard ceramic tiles, held together against hydrostatic pressure by bands of nickel alloy. Voids in the glass to give the honeycomb structure are formed by hexagonal blocks of ceramic fiber, held down against flotation with silicon carbide bolts. Liquid glass runs over the blocks to form the face sheet, and under the blocks, which are spaced above the base tiles, to form a back sheet with holes. After the casting has been annealed and cooled, the base tiles are unbolted and the ceramic fiber blocks removed from the glass honeycomb by water blasting. Both blanks are of high quality, free from cracks and voids, and with an adequately low bubble content. The second and better blank, made of Ohara's E6 glass, is now to be figured to high precision, 0.25 arcsecond images, and is to be tested for an extended period in the Multiple Mirror Telescope.

  7. Aluminum Pannier

    USGS Multimedia Gallery

    This aluminum pannier was made for the storage of meat, vegetables and other food products. The pannier could be buried in the ground or placed in water in order to keep the contents cool. It was designed by Dr. J. D. Love and made for him in 1945. For transportation, this pannier, along with two re...

  8. Mechanical analysis of confectioning flaw of refractory alloy honeycomb sandwich structure

    NASA Astrophysics Data System (ADS)

    He, Xiaodong; Kong, Xianghao; Shi, Liping; Li, Mingwei

    2009-03-01

    Thermal protection system is one of the key technology of reusable launch vehicle (RLV). After C/C and ceramic-matrix composite used in space orbiter, one new-typed thermal protection systems (TPS)-ARMOR TPS is coming forth. ARMOR TPS is means adaptable, robust, metallic, operable, reusable TPS. The ARMOR TPS has many advantages, for example: fixing easily, longer life, good properties, short time of maintenance and service. The ARMOR TPS is one of important candidate structure of RLV. ARMOR thermal protection system in foreign countries for reusable launch vehicle is used instead of the traditional ceramic-matrix composite thermal protection system and C/C thermal protection system. Also the constituent feature of ARMOR thermal protection system is much better than the traditional TPS. In comparison with traditional TPS, the ARMOR TPS will be the best selection for all kinds of RLV. So the ARMOR thermal protection system will be used in aviation and spaceflight field more and more widely because of its much better performance. ARMOR TPS panel is above the whole ARMOR TPS, and the metal honeycomb sandwich structure is the surface of the ARMOR TPS panel. So the metal honeycomb sandwich structure plays an important role in the ARMOR TPS, while it bears the flight dynamic pressure and stands against the flight dynamic calefaction. The metal honeycomb sandwich structure is made using the technique of the whole braze welding. In the course of the vacuum high temperature braze welding, its surface will appear concave. The reasons which lead to the shortage are summarized and discussed. The difference of thermal expansion coefficient and pressure between the core and the panels may be the chief reasons. This paper will analyze the mechanics behavior of metal honeycomb sandwich structure in the course of the vacuum high temperature braze welding, then make sure the reasons and get a way to solve it. Haynes214 is a good material of face sheet at present. ? - TiAl and microlaminate materials are the candidate materials in the future.

  9. Topology optimization of pressure adaptive honeycomb for a morphing flap

    NASA Astrophysics Data System (ADS)

    Vos, Roelof; Scheepstra, Jan; Barrett, Ron

    2011-03-01

    The paper begins with a brief historical overview of pressure adaptive materials and structures. By examining avian anatomy, it is seen that pressure-adaptive structures have been used successfully in the Natural world to hold structural positions for extended periods of time and yet allow for dynamic shape changes from one flight state to the next. More modern pneumatic actuators, including FAA certified autopilot servoactuators are frequently used by aircraft around the world. Pneumatic artificial muscles (PAM) show good promise as aircraft actuators, but follow the traditional model of load concentration and distribution commonly found in aircraft. A new system is proposed which leaves distributed loads distributed and manipulates structures through a distributed actuator. By using Pressure Adaptive Honeycomb (PAH), it is shown that large structural deformations in excess of 50% strains can be achieved while maintaining full structural integrity and enabling secondary flight control mechanisms like flaps. The successful implementation of pressure-adaptive honeycomb in the trailing edge of a wing section sparked the motivation for subsequent research into the optimal topology of the pressure adaptive honeycomb within the trailing edge of a morphing flap. As an input for the optimization two known shapes are required: a desired shape in cruise configuration and a desired shape in landing configuration. In addition, the boundary conditions and load cases (including aerodynamic loads and internal pressure loads) should be specified for each condition. Finally, a set of six design variables is specified relating to the honeycomb and upper skin topology of the morphing flap. A finite-element model of the pressure-adaptive honeycomb structure is developed specifically tailored to generate fast but reliable results for a given combination of external loading, input variables, and boundary conditions. Based on two bench tests it is shown that this model correlates well to experimental results. The optimization process finds the skin and honeycomb topology that minimizes the error between the acquired shape and the desired shape in each configuration.

  10. Unburned carbon removal effect on compressive strength development in a honeycomb briquette ash-based geopolymer

    Microsoft Academic Search

    Sujeong Lee; Myeong-Deok Seo; Yun-Jong Kim; Hyun-Hye Park; Taik-Nam Kim; Yeon Hwang; Sung-Baek Cho

    2010-01-01

    The potential of honeycomb briquette ash as a new source material for the manufacture of geopolymers was examined. The successful geopolymerization of honeycomb briquette ash was attained by means of NaOH treatment. The concentrations of the major and minor elements of honeycomb briquette ash are in the normal range of the chemical composition of fly ash and appropriate for the

  11. Effects of service environments on aluminum-brazed titanium (ABTi)

    NASA Technical Reports Server (NTRS)

    Cotton, W. L.

    1978-01-01

    Aluminum brazed titanium (ABTi) structures were evaluated during prolonged exposure to extreme environments: elevated temperature exposure to airline service fluids, hydraulic fluid, and seawater, followed by laboratory corrosion tests. Solid-face and perforated face honeycomb sandwich panel specimens, stressed panel assemblies, and faying surface brazed joints were tested. The corrosion resistance of ABTi is satisfactory for commercial airline service. Unprotected ABTi proved inherently resistant to attack by all of the extreme service aircraft environments except: seawater at 700 K (800 F) and above, dripping phosphate ester hydraulic fluid at 505 K (450 F), and a marine environment at ambient temperature. The natural oxides and deposits present on titanium surfaces in airline service provide protection against hot salt corrosion pitting. Coatings are required to protect titanium dripping phosphate ester fluid at elevated temperatures and to protect exposed acoustic honeycomb parts against corrosion in a marine environment.

  12. Ultrasonic waveguide transducer for high temperature testing of ceramic honeycomb

    NASA Astrophysics Data System (ADS)

    Wang, N.; An, C. P.; Nickerson, S. T.; Gunasekaran, N.; Shi, Z.

    2013-01-01

    This paper describes the development of a practical ultrasonic waveguide transducer designed for in situ material property characterization of ceramic honeycomb at high temperatures (>1200°C) and under fast thermal cycles (>1000°C/min). The low thermal conductivity MACOR waveguide allows the use of conventional transducer (max temp. 50°C) at one end and guides ultrasonic waves into the high temperature region where the characterization is carried out. The impact of time, temperature, and heating/cooling rates on the material behavior was studied. It was demonstrated that the same transducer could also be used for in-situ crack detection during the thermal shock testing of ceramic honeycomb.

  13. Adhesion characterization and defect sizing of sandwich honeycomb composites.

    PubMed

    Ndiaye, Elhadji Barra; Maréchal, Pierre; Duflo, Hugues

    2015-09-01

    Defects may appear in composite structures during their life cycle. A 10MHz 128 elements phased array transducer was investigated to characterize join bonds and defects in sandwich honeycomb composite structures. An adequate focal law throughout the composite skin gives the ultrasonic dispersive properties of the composite skin and glue layer behind. The resulting B-scan cartographies allow characterizing locally the honeycomb adhesion. Experimental measurements are compared in good agreement with the Debye Series Method (DSM). In the processed C-scan image, flaws are detectable and measurable, localized both in the scanning plane and in the thickness of the composite skin. PMID:26138595

  14. The actuated performance of multi-layer piezoelectric actuator in active vibration control of honeycomb sandwich panel

    NASA Astrophysics Data System (ADS)

    Luo, Yajun; Xie, Shilin; Zhang, Xinong

    2008-11-01

    This paper discusses the use of the multi-layer piezoelectric actuator (MPA) in the active vibration control of the honeycomb sandwich panel (HSP). A literature overview of the available works is first presented. And the main motivation using the MPA in the AVC of HSP is discussed. Then, the honeycomb core is in advance treated as an orthotropic plate. The governing equations of the system are derived by the Hamilton principle on the basis of both displacement and transverse tress assumptions. The formulations of the actuation force/moment are obtained and indicate that the actuation force/moment are two four-order polynomial function of the piezoelectric layers number. Finally, active control experiments of a cantilever honeycomb sandwich panel (CHSP) are performed using the MPA. The control law of proportional velocity feedback is adopted in the experiments. These experiments include the resonant vibration control and the sinusoidal swept of the control system at the case of different piezoelectric layers number. The results show that the MPA can effectively control the vibration of the high damping HSP, and the control performance per voltage by the proposed actuator can be improved significantly through increasing the piezoelectric patch number. Consequently, the MPA exhibits better actuation capability than that with only single layer.

  15. Metal honeycomb to porous wireform substrate diffusion bond evaluation

    NASA Technical Reports Server (NTRS)

    Vary, A.; Moorhead, P. E.; Hull, D. R.

    1982-01-01

    Two nondestructive techniques were used to evaluate diffusion bond quality between a metal foil honeycomb and porous wireform substrate. The two techniques, cryographics and acousto-ultrasonics, are complementary in revealing variations of bond integrity and quality in shroud segments from an experimental aircraft turbine engine.

  16. Lunar-related spawning in honeycomb grouper, Epinephelus merra

    Microsoft Academic Search

    K. Soyano; T. Masumoto; H. Tanaka; M. Takushima; M. Nakamura

    2003-01-01

    Lunar-related spawning in honeycomb grouper was investigated by histological and behavioral analyses. Ovarian development and spawning of the fish were related to lunar periodicity. And also the fish migrated to out side of the reef area and spawned for a few days after the full moon.

  17. Reinforced sand cores

    Microsoft Academic Search

    Martin Zoldan

    2005-01-01

    Engine blocks and cylinder heads (castings) are made of aluminum or cast iron. Molten metal, poured into molds, forms the shape of engine blocks and cylinder heads. Molds create the outside of the casting and sand cores create cavities within the casting. ^ Typically, sand cores must maintain small aspect ratios to preserve structural integrity during the casting process. The

  18. Recycling of automotive aluminum

    Microsoft Academic Search

    Jirang CUI; Hans J. ROVEN

    2010-01-01

    With the global warming of concern, the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits. In this work, recycling of automotive aluminum is reviewed to highlight environmental benefits of aluminum recycling, use of aluminum alloys in automotive applications, automotive recycling process, and new technologies in

  19. Failure Modes and Influence of the Quasi-static Deformation Rate on the Mechanical Behavior of Sandwich Panels with Aluminum Foam Cores

    Microsoft Academic Search

    Isabel Duarte; F. Teixeira-Dias; Ana Graça; António J. M. Ferreira

    2010-01-01

    The main purpose of this work is to study the bending behavior and deformation mechanisms of sandwich panels with AlSi7-alloy foam cores obtained by the powder metallurgy method. For this purpose, quasi-static three-point bending tests were performed on samples of AlSi7-alloy foam sandwich panels at different cross-head displacement rates: 1, 10, 20, 40 and 80 [mm\\/min]. Load-deflection values were registered

  20. Brazing dissimilar aluminum alloys

    NASA Technical Reports Server (NTRS)

    Dalalian, H.

    1979-01-01

    Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.

  1. Service evaluation of Aluminum-Brazed Titanium (ABTi) jet engine tailpipe extensions

    NASA Technical Reports Server (NTRS)

    Elrod, S. D.

    1982-01-01

    Aluminum-brazed titanium (ABTi) jet engine tailpipe extensions were evaluated in commercial service over a 3-year period. The purpose of the evaluation was to determine the corrosion resistance of ABTi in acoustic applications (i.e., honeycomb sandwich incorporating a perforated inner skin). The results showed that ABTi does not have acceptable corrosion resistance in acoustic applications under severe operating conditions, but may be acceptable for acoustic applications in less severe environments.

  2. Creep behavior of a closed-cell aluminum foam

    SciTech Connect

    Andrews, E.W.; Gibson, L.J. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering] [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering; Huang, J.S. [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Civil Engineering] [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Civil Engineering

    1999-08-10

    The results of creep tests on a closed-cell aluminum foam (Alporas) are reported. At low stresses and temperatures, the behavior is well described by existing models for foams. At high stresses and temperatures, the power law creep exponent increases from about 4 to 15 and the activation energy increases from about 100 to 450 kJ/mol. The increase in power law exponent may be related to damage; a finite element damage model of a two-dimensional honeycomb gives consistent results with the measured foam behavior.

  3. Aluminum extraction from aluminum industrial wastes

    NASA Astrophysics Data System (ADS)

    Amer, A. M.

    2010-05-01

    Aluminum dross tailings, an industrial waste from the Egyptian Aluminum Company (Egyptalum), was used to produce two types of alums: aluminum sulfate alum (Al2(SO4)3·12H2O) and ammonium aluminum alum {(NH4)2SO4AL2 (SO4)3·24H2O}. This was carried out in two processes. The first involves leaching the impurities using diluted H2SO4 with different solid/liquid ratios at different temperatures to dissolve the impurities present in the starting material in the form of aluminum sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purified aluminum dross tailings thus produced. This was carried out in an autoclave. The effects of temperature, time of reaction, and acid concentration on pressure leaching and extraction processes were studied in order to specify the optimum conditions to be applied in the bench scale production as well as the kinetics of leaching process.

  4. Solid oxide fuel cell stacks using extruded honeycomb type elements

    NASA Astrophysics Data System (ADS)

    Wetzko, M.; Belzner, A.; Rohr, F. J.; Harbach, F.

    A solid oxide fuel cell (SOFC) stack concept is described which comprises "condensed-tubes" like extruded honeycomb sections of ceramic electrolyte (ZrO 2-based) and interconnectors of nickel sheet as key elements. According to this concept, well known and extensively tested construction principles can be realised in a low-cost production. The cells are self-supported with in-plane conduction. A demonstrator model stack of five honeycomb elements and six nickel sheet seals/interconnectors was built and operated for 860 h at 1000°C. Volumetric power densities of 160 kW/m 3 were obtained with H 2 vs. air, of close to 200 kW/m 3 with H 2 vs. O 2.

  5. Shape memory polymer filled honeycomb model and experimental validation

    NASA Astrophysics Data System (ADS)

    Beblo, R. V.; Puttmann, J. P.; Joo, J. J.; Reich, G. W.

    2015-02-01

    An analytical model predicting the in-plane Young’s and shear moduli of a shape memory polymer filled honeycomb composite is presented. By modeling the composite as a series of rigidly attached beams, the mechanical advantage of the load distributed on each beam by the infill is accounted for. The model is compared to currently available analytical models as well as experimental data. The model correlates extremely well with experimental data for empty honeycomb and when the polymer is above its glass transition temperature. Below the glass transition temperature, rule of mixtures is shown to be more accurate as bending is no longer the dominant mode of deformation. The model is also derived for directions other than the typical x and y allowing interpolation of the stiffness of the composite in any direction.

  6. Spin-orbital quantum liquid on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Corboz, Philippe

    2013-03-01

    The symmetric Kugel-Khomskii can be seen as a minimal model describing the interactions between spin and orbital degrees of freedom in transition-metal oxides with orbital degeneracy, and it is equivalent to the SU(4) Heisenberg model of four-color fermionic atoms. We present simulation results for this model on various two-dimensional lattices obtained with infinite projected-entangled pair states (iPEPS), an efficient variational tensor-network ansatz for two dimensional wave functions in the thermodynamic limit. This approach can be seen as a two-dimensional generalization of matrix product states - the underlying ansatz of the density matrix renormalization group method. We find a rich variety of exotic phases: while on the square and checkerboard lattices the ground state exhibits dimer-Néel order and plaquette order, respectively, quantum fluctuations on the honeycomb lattice destroy any order, giving rise to a spin-orbital liquid. Our results are supported from flavor-wave theory and exact diagonalization. Furthermore, the properties of the spin-orbital liquid state on the honeycomb lattice are accurately accounted for by a projected variational wave-function based on the pi-flux state of fermions on the honeycomb lattice at 1/4-filling. In that state, correlations are algebraic because of the presence of a Dirac point at the Fermi level, suggesting that the ground state is an algebraic spin-orbital liquid. This model provides a good starting point to understand the recently discovered spin-orbital liquid behavior of Ba3CuSb2O9. The present results also suggest to choose optical lattices with honeycomb geometry in the search for quantum liquids in ultra-cold four-color fermionic atoms. The symmetric Kugel-Khomskii can be seen as a minimal model describing the interactions between spin and orbital degrees of freedom in transition-metal oxides with orbital degeneracy, and it is equivalent to the SU(4) Heisenberg model of four-color fermionic atoms. We present simulation results for this model on various two-dimensional lattices obtained with infinite projected-entangled pair states (iPEPS), an efficient variational tensor-network ansatz for two dimensional wave functions in the thermodynamic limit. This approach can be seen as a two-dimensional generalization of matrix product states - the underlying ansatz of the density matrix renormalization group method. We find a rich variety of exotic phases: while on the square and checkerboard lattices the ground state exhibits dimer-Néel order and plaquette order, respectively, quantum fluctuations on the honeycomb lattice destroy any order, giving rise to a spin-orbital liquid. Our results are supported from flavor-wave theory and exact diagonalization. Furthermore, the properties of the spin-orbital liquid state on the honeycomb lattice are accurately accounted for by a projected variational wave-function based on the pi-flux state of fermions on the honeycomb lattice at 1/4-filling. In that state, correlations are algebraic because of the presence of a Dirac point at the Fermi level, suggesting that the ground state is an algebraic spin-orbital liquid. This model provides a good starting point to understand the recently discovered spin-orbital liquid behavior of Ba3CuSb2O9. The present results also suggest to choose optical lattices with honeycomb geometry in the search for quantum liquids in ultra-cold four-color fermionic atoms. We acknowledge the financial support from the Swiss National Science Foundation.

  7. Commercial application of aluminum honeycomb and foam in load bearing tubular structures

    E-print Network

    Bartolucci, Stefano, 1976-

    2004-01-01

    Small dimension engineering tubular structures subjected to a complex load system are designed like hollow circular shells. For minimum weight design, the ratio between the shell radius and the thickness has to be as large ...

  8. Topological properties of the bond-modulated honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Grandi, F.; Manghi, F.; Corradini, O.; Bertoni, C. M.

    2015-03-01

    We study the combined effects of lattice deformation, e -e interaction, and spin-orbit coupling in a two-dimensional (2D) honeycomb lattice. We adopt different kinds of hopping modulation—generalized dimerization and a Kekulé distortion—and calculate topological invariants for the noninteracting system and for the interacting system. We identify the parameter range (Hubbard U , hopping modulation, spin-orbit coupling) where the 2D system behaves as a trivial insulator or quantum spin Hall insulator.

  9. Superelastic NiTi honeycombs: fabrication and experiments

    Microsoft Academic Search

    John A. Shaw; David S. Grummon; John Foltz

    2007-01-01

    In this paper we demonstrate a new class of superelastic NiTi honeycomb structures. We have developed a novel brazing technique that has allowed us to fabricate Nitinol-based cellular structures with relative densities near 5%. Commercially available nickel-rich Nitinol strips were shape-set into corrugated form, stacked, and bonded at high temperature by exploiting a contact eutectic melting reaction involving pure niobium.

  10. Order parameters from image analysis: a honeycomb example

    NASA Astrophysics Data System (ADS)

    Kaatz, Forrest H.; Bultheel, Adhemar; Egami, Takeshi

    2008-11-01

    Honeybee combs have aroused interest in the ability of honeybees to form regular hexagonal geometric constructs since ancient times. Here we use a real space technique based on the pair distribution function (PDF) and radial distribution function (RDF), and a reciprocal space method utilizing the Debye-Waller Factor (DWF) to quantify the order for a range of honeycombs made by Apis mellifera ligustica. The PDFs and RDFs are fit with a series of Gaussian curves. We characterize the order in the honeycomb using a real space order parameter, OP 3 , to describe the order in the combs and a two-dimensional Fourier transform from which a Debye-Waller order parameter, u, is derived. Both OP 3 and u take values from [0, 1] where the value one represents perfect order. The analyzed combs have values of OP 3 from 0.33 to 0.60 and values of u from 0.59 to 0.69. RDF fits of honeycomb histograms show that naturally made comb can be crystalline in a 2D ordered structural sense, yet is more ‘liquid-like’ than cells made on ‘foundation’ wax. We show that with the assistance of man-made foundation wax, honeybees can manufacture highly ordered arrays of hexagonal cells. This is the first description of honeycomb utilizing the Debye-Waller Factor, and provides a complete analysis of the order in comb from a real-space order parameter and a reciprocal space order parameter. It is noted that the techniques used are general in nature and could be applied to any digital photograph of an ordered array.

  11. In-plane crushing of a polycarbonate honeycomb

    Microsoft Academic Search

    Scott D. Papka; Stelios Kyriakides

    1998-01-01

    The in-plane compressive response and crushing of a polycarbonate honeycomb with circular close-packed cells is studied through combined experimental and analytical efforts. Under displacement controlled quasi-static loading the response is characterized by a relatively sharp rise to a load maximum followed by a drop down to an extended load plateau which is then terminated by a sharp rise in load.

  12. Half-filled Kondo lattice on the honeycomb lattice

    E-print Network

    Yin Zhong; Ke Liu; Yu-Feng Wang; Yong-Qiang Wang; Hong-Gang Luo

    2013-02-28

    The unique linear density of state around the Dirac points for the honeycomb lattice brings much novel features in strongly correlated models. Here we study the ground-state phase diagram of the Kondo lattice model on the honeycomb lattice at half-filling by using an extended mean-field theory. By treating magnetic interaction and Kondo screening on an equal footing, it is found that besides a trivial discontinuous first-order quantum phase transition between well-defined Kondo insulator and antiferromagnetic insulating state, there can exist a wide coexistence region with both Kondo screening and antiferromagnetic orders in the intermediate coupling regime. In addition, the stability of Kondo insulator requires a minimum strength of the Kondo coupling. These features are attributed to the linear density of state, which are absent in the square lattice. Furthermore, fluctuation effect beyond the mean-field decoupling is analyzed and the corresponding antiferromagnetic spin-density-wave transition falls into the O(3) universal class. Comparatively, we also discuss the Kondo necklace and the Kane-Mele-Kondo (KMK) lattice models on the same lattice. Interestingly, it is found that the topological insulating state is unstable to the usual antiferromagnetic ordered states at half-filling for the KMK model. The present work may be helpful for further studies on the interplay between conduction electrons and the densely localized spins on the honeycomb lattice.

  13. Generalized stacking fault energy surfaces and dislocation properties of aluminum

    Microsoft Academic Search

    Gang Lu; Nicholas Kioussis; Vasily V. Bulatov; Efthimios Kaxiras

    We have employed the semidiscrete variational generalized Peierls-Nabarro model to study the dislocation core properties of aluminum. The general- ized stacking fault energy surfaces entering the model are calculated by using first-principles Density Functional Theory (DFT) with pseudopotentials and the embedded atom method (EAM). Various core properties, including the core width, splitting behavior, energetics and Peierls stress for different dislo-

  14. Characterizatin of ultrafine aluminum nanoparticles

    SciTech Connect

    Sandstrom, M. M. (Mary M.); Jorgensen, B. S. (Betty S.); Mang, J. T. (Joseph T.); Smith, B. L. (Bettina L.); Son, S. F. (Steven F.)

    2004-01-01

    Aluminum nanopowders with particle sizes ranging from {approx}25 nm to 80 nm were characterized by a variety of methods. We present and compare the results from common powder characterization techniques including transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), BET gas adsorption surface area analysis, thermogravimetric analysis (TGA), photon correlation spectroscopy (PCS), and low angle laser light scattering (LALLS). Aluminum nanoparticles consist of an aluminum core with an aluminum oxide coating. HRTEM measurements of both the particle diameter and oxide layer thickness tend to be larger than those obtained from BET and TGA. LALLS measurements show a large degree of particle agglomeration in solution; therefore, primary particle sizes could not be determined. Furthermore, results from small-angle scattering techniques (SAS), including small-angle neutron (SANS) and x-ray (SAXS) scattering are presented and show excellent agreement with the BET, TGA, and HRTEM. The suite of analytical techniques presented in this paper can be used as a powerful tool in the characterization of many types of nanosized powders.

  15. Producing gapped-ferrite transformer cores

    NASA Technical Reports Server (NTRS)

    Mclyman, W. T.

    1980-01-01

    Improved manufacturing techniques make reproducible gaps and minimize cracking. Molded, unfired transformer cores are cut with thin saw and then fired. Hardened semicircular core sections are bonded together, placed in aluminum core box, and fluidized-coated. After winding is run over box, core is potted. Economical method significantly reduces number of rejects.

  16. Emission of an intense electron beam from a ceramic honeycomb

    NASA Astrophysics Data System (ADS)

    Friedman, M.; Myers, M.; Hegeler, F.; Swanekamp, S. B.; Sethian, J. D.; Ludeking, L.

    2003-01-01

    Inserting a slab of honeycomb ceramic in front of the emitting surface of a large-area cathode improves the electron beam emission uniformity, decreases the beam current rise and fall times, and maintains a more constant diode impedance. Moreover, changing the cathode material from velvet to carbon fiber achieved a more robust cathode that starts to emit at a higher electric field without a degradation in beam uniformity. In addition, an 80% reduction in the postshot diode pressure was also observed when gamma alumina was deposited on the ceramic. A possible explanation is that reabsorption and recycling of adsorbed gases takes place.

  17. Topological and magnetic phases in the honeycomb Iridates

    NASA Astrophysics Data System (ADS)

    Rachel, Stephan

    2014-03-01

    Iridates are amongst the most interesting complex oxide materials. The non-interacting band structure of the honeycomb Iridates has been claimed to feature the quantum spin Hall effect due to large spin orbit coupling. The true materials exhibit considerable Coulomb interactions leading to different types of magnetic order (e.g., zig-zag or spiral order). Here we show how one can obtain such magnetic phases by combining topological band structure and local Coulomb interactions into a topological Hubbard model which we analyze in detail.

  18. Water intrusion in thin-skinned composite honeycomb sandwich structures

    NASA Technical Reports Server (NTRS)

    Jackson, Wade C.; O'Brien, T. Kevin

    1988-01-01

    Thin-skinned composite honeycomb sandwich structures from the trailing edge of the U.S. Army's Apache and Chinook helicopters have been tested to ascertain their susceptibility to water intrusion as well as such intrusions' effects on impact damage and cyclic loading. Minimum-impact and fatigue conditions were determined which would create microcracks sufficiently large to allow the passage of water through the skins; damage sufficient for this to occur was for some skins undetectable under a 40X-magnification optical microscope. Flow rate was a function of moisture content, damage, applied strain, and pressure differences.

  19. Magnetic Anisotropy of a Three-Dimensional Honeycomb Iridate

    NASA Astrophysics Data System (ADS)

    Modic, Kimberly; McDonald, Ross; Shekter, Arkady; Analytis, James; Ramshaw, Brad

    2015-03-01

    We present the magnetic anisotropy of a 3-dimensional honeycomb iridate, where the large spin-orbit coupling of iridium provides the possibility for exotic magnetic ground states. A complete angular dependence of magnetic torque provides evidence for highly spin-anisotropic exchange interactions at low temperature. An extension of these measurements to high magnetic fields shows that the magnetic anisotropy switches sign at 50 T and becomes five times larger than the anisotropy at low fields. The anisotropy continues to increase up to the largest applied fields suggesting the presence of new magnetically ordered states.

  20. Structural Finite Element Analysis of Stiffened and Honeycomb Panels of the RASAT Satellite

    Microsoft Academic Search

    S. Ontac; S. Dag; M. I. Gokler

    2007-01-01

    This paper describes the structural analysis carried out on the main stiffened and honeycomb panels of the RASAT satellite. The analysis here supports the design process and aims to ensure that the panels survive structural qualification testing. This analysis therefore forms part of the overall qualification process. The stiffened and honeycomb panels being considered in this document form the outer

  1. Acoustic emission analysis of full-scale honeycomb sandwich composite curved fuselage panels

    Microsoft Academic Search

    Frank A. Leone Jr.; Didem Ozevin; Valery Godinez; Bao Mosinyi; John G. Bakuckas Jr.; Jonathan Awerbuch; Alan Lau; Tein-Min Tan

    2008-01-01

    Acoustic emission (AE) was monitored in notched full-scale honeycomb sandwich composite curved fuselage panels during loading. The purpose of the study was to evaluate the AE technique as a tool for detecting notch tip damage initiation and evaluating damage severity in such structures. This evaluation was a part of a more general study on the damage tolerance of six honeycomb

  2. The dynamic response of sandwich beams with open-cell metal foam cores

    Microsoft Academic Search

    Lin Jing; Zhihua Wang; Jianguo Ning; Longmao Zhao

    2011-01-01

    The deformation and failure modes of dynamically loaded sandwich beams made of aluminum skins with open-cell aluminum foam cores were investigated experimentally. The dynamic compressive stress–strain curves of core materials, open-cell aluminum foam, were obtained using Split Hopkinson Pressure Bar. And then the dynamic impact tests were conducted for sandwich beams with open-cell aluminum foam cores. The photographs showing the

  3. Computer simulation of screw dislocation in aluminum

    NASA Technical Reports Server (NTRS)

    Esterling, D. M.

    1976-01-01

    The atomic structure in a 110 screw dislocation core for aluminum is obtained by computer simulation. The lattice statics technique is employed since it entails no artificially imposed elastic boundary around the defect. The interatomic potential has no adjustable parameters and was derived from pseudopotential theory. The resulting atomic displacements were allowed to relax in all three dimensions.

  4. Topological states in multi-orbital HgTe honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Beugeling, W.; Kalesaki, E.; Delerue, C.; Niquet, Y.-M.; Vanmaekelbergh, D.; Smith, C. Morais

    2015-03-01

    Research on graphene has revealed remarkable phenomena arising in the honeycomb lattice. However, the quantum spin Hall effect predicted at the K point could not be observed in graphene and other honeycomb structures of light elements due to an insufficiently strong spin–orbit coupling. Here we show theoretically that 2D honeycomb lattices of HgTe can combine the effects of the honeycomb geometry and strong spin–orbit coupling. The conduction bands, experimentally accessible via doping, can be described by a tight-binding lattice model as in graphene, but including multi-orbital degrees of freedom and spin–orbit coupling. This results in very large topological gaps (up to 35?meV) and a flattened band detached from the others. Owing to this flat band and the sizable Coulomb interaction, honeycomb structures of HgTe constitute a promising platform for the observation of a fractional Chern insulator or a fractional quantum spin Hall phase.

  5. Topological states in multi-orbital HgTe honeycomb lattices.

    PubMed

    Beugeling, W; Kalesaki, E; Delerue, C; Niquet, Y-M; Vanmaekelbergh, D; Morais Smith, C

    2015-01-01

    Research on graphene has revealed remarkable phenomena arising in the honeycomb lattice. However, the quantum spin Hall effect predicted at the K point could not be observed in graphene and other honeycomb structures of light elements due to an insufficiently strong spin-orbit coupling. Here we show theoretically that 2D honeycomb lattices of HgTe can combine the effects of the honeycomb geometry and strong spin-orbit coupling. The conduction bands, experimentally accessible via doping, can be described by a tight-binding lattice model as in graphene, but including multi-orbital degrees of freedom and spin-orbit coupling. This results in very large topological gaps (up to 35?meV) and a flattened band detached from the others. Owing to this flat band and the sizable Coulomb interaction, honeycomb structures of HgTe constitute a promising platform for the observation of a fractional Chern insulator or a fractional quantum spin Hall phase. PMID:25754462

  6. Corrosion of aluminum and aluminum alloys

    SciTech Connect

    Davis, J.R. (ed.)

    1999-01-01

    This new handbook presents comprehensive coverage of the corrosion behavior of aluminum and aluminum alloys, with emphasis on practical information about how to select and process these materials in order to prevent corrosion attack. Described are the characteristics of these materials and the influences of composition, mechanical working, heat treatment, joining methods, microstructure, and environmental variables on their corrosion.

  7. Aluminum hydroxide production

    SciTech Connect

    Martin, E.S.; Weaver, M.L.

    1988-07-05

    A method is described for the production of aluminum hydroxide, comprising reacting water in the liquid phase and aluminum of surface area of at least 20 mm/sup 2/ per gram at a pH above about 12.4 for producing a reaction mixture containing aluminum hydroxide, and collecting solid aluminum hydroxide from the reaction mixture, the reaction being carried out in the presence of choline at a concentration of about 0.05 to 2 mols per liter.

  8. Aluminum and Young Artists.

    ERIC Educational Resources Information Center

    Anderson, Thomas

    1980-01-01

    The author suggests a variety of ways in which aluminum and aluminum foil can be used in elementary and junior high art classes: relief drawing and rubbing; printing; repousse; sculpture; mobiles; foil sculpture; and three dimensional design. Sources of aluminum supplies are suggested. (SJL)

  9. The Hamiltonian Laceability of some Generalized Honeycomb Tori

    SciTech Connect

    Hsu Liyen [Department of Aviation Management, China Institute of Technology. No. 200, Zhonghua St., Hengshan Shiang, Hsinchu County, Taiwan. 312 (China); Lin Tungyi; Kao Shinshin [Department of Applied Mathemetics, Chung Yuan Christian University. No. 200, Chung Pei Rd., Chung Li, Taiwan. 32023 (China)

    2008-11-06

    Assume that m, n and s are integers with m{>=}2, n{>=}4, 0{<=}s{<=}n and s is of the same parity of m. The generalized honeycomb torus GHT (m,n,s) is recognized as another attractive alternative to existing torus interconnection networks in parallel and distributed applications. It is known that any GHT (m,n,s) is 3-regular, hamiltonian, bipartite graph. We are interested in two special types of the generalized honeycomb torus, GHT (m,n,(n/2)) and GHT (m,n,0). Let G = GHT(m,n,s), where s(set-membership sign){l_brace}(n/2),0{r_brace}. We prove that any G is hamiltonian laceable. More precisely, given a pair of vertices P = {l_brace}u,v|u(set-membership sign)B,v(set-membership sign)W{r_brace} where B and W are the bipartition of V(G), there exists a path Q between u and v such that Q contains all vertices of G.

  10. Evolution of Magnetism in Single-Crystal Honeycomb Iridates

    NASA Astrophysics Data System (ADS)

    Terzic, Jasminka; Qi, T. F.; Li, L.; Cao, V. S.; Yuan, S. J.; Tovar, M.; Murthy, G.; Kaul, R. K.; Cao, G.

    2014-03-01

    We report the successful synthesis of single-crystals of the layered iridate, (Na1-xLix)2IrO3, 0 <= x <= 0.90, and a thorough study of its structural, magnetic, thermal and transport properties. The new compound allows a controlled interpolation between Na2IrO3andLi2IrO3, while maintaining the novel quantum magnetism of the honeycomb Ir4 + planes. The measured phase diagram demonstrates a suppression of the Neel temperature at an intermediate x indicating that the magnetic order in Na2IrO3andLi2IrO3 are distinct. X-ray data shows that for x =0.70 when the Neel temperature is suppressed the most, the honeycomb structure is least distorted, suggesting at this intermediate doping that the material is closest to the spin liquid that has been sought after in Na2IrO3andLi2IrO3. By analyzing our magnetic data with a single-ion theoretical model we also show that the trigonal splitting, on the Ir4 + ions changes sign from Na2IrO3toLi2IrO3. This work was supported by the US National Science Foundation via grants DMR-0856234, DMR-1265162 and DMR- NSF DMR-1056536 (RKK).

  11. 8m Borosilicate Honeycomb Spin Casting: Material Developments

    NASA Astrophysics Data System (ADS)

    Olbert, B. H.; Angel, J. R.; Goble, L. W.

    1989-01-01

    Creep and strength of candidate glass contact refractories for honeycomb casting molds were measured at 1200 C. Based on performance and cost, one material, Rex Roto Corp.'s R1162-17 speciality fiber mix, was chosen for the Steward's first 3.5m casting mold. More extensive measurements of firing shrinkage, thermal expansion, room temperature Young's Modulus, bulk density, and creep were carried out on R1162-17 samples cut from hexagonal box preforms. Test results indicate that R1162-17 hex boxes have acceptable creep resistance and the potential strength to withstand hydrostatic loading up to 66cm of borosilicate melt. In November of 1987, blocks of a low-expansion borosilicate glass, Corning Code 7761, was spin cast into a 1.2m honeycomb for the Smithsonian Astrophysical Observatory. The casting contained a relatively high density of small-scale striae and small bubbles along the remelted block surfaces. Origin of the small bubbles was traced to graphite particles imbedded in the glass surface during the forming operation. In spite of small-scale striae, the measured expansion coefficient variation over spacial scales greater than 1mm was less than t7x10-9/C.

  12. Material Model Evaluation of a Composite Honeycomb Energy Absorber

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Annett, Martin S.; Fasanella, Edwin L.; Polanco, Michael A.

    2012-01-01

    A study was conducted to evaluate four different material models in predicting the dynamic crushing response of solid-element-based models of a composite honeycomb energy absorber, designated the Deployable Energy Absorber (DEA). Dynamic crush tests of three DEA components were simulated using the nonlinear, explicit transient dynamic code, LS-DYNA . In addition, a full-scale crash test of an MD-500 helicopter, retrofitted with DEA blocks, was simulated. The four material models used to represent the DEA included: *MAT_CRUSHABLE_FOAM (Mat 63), *MAT_HONEYCOMB (Mat 26), *MAT_SIMPLIFIED_RUBBER/FOAM (Mat 181), and *MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM (Mat 142). Test-analysis calibration metrics included simple percentage error comparisons of initial peak acceleration, sustained crush stress, and peak compaction acceleration of the DEA components. In addition, the Roadside Safety Verification and Validation Program (RSVVP) was used to assess similarities and differences between the experimental and analytical curves for the full-scale crash test.

  13. The anisotropy of aluminum and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Hosford, William F.

    2006-05-01

    The anisotropy of textured aluminum is approximated by a yield criterion with an exponent of eight. The use of this criterion in metal-forming analyses has improved the understanding of the formability of aluminum and other metals. The effect of anisotropy on the limiting drawing ratio in cupping is less than that expected from the quadratic Hill yield criterion and the effect of texture on forming limit diagrams is negligible. A method of predicting the effect of strain-path changes on forming limit curves of aluminum alloy sheets has proven to agree with experiments.

  14. Directed Self-Assembly of Large Scaffold-free Multicellular Honeycomb Structures

    PubMed Central

    Tejavibulya, Nalin; Youssef, Jacquelyn; Bao, Brian; Ferruccio, Toni-Marie; Morgan, Jeffrey R.

    2011-01-01

    A significant challenge to the field of biofabrication is the rapid construction of large three dimensional (3D) living tissues and organs. Multi-cellular spheroids have been used as building blocks. In this paper, we create large multi-cellular honeycomb building blocks using directed self-assembly, whereby cell-to-cell adhesion, in the context of the shape and obstacles of a micromold, drives the formation of a 3D structure. Computer aided design, rapid prototyping and replica molding were used to fabricate honeycomb-shaped micro-molds. Nonadhesive hydrogels cast from these micro-molds were equilibrated in cell culture medium and seeded with two types of mammalian cells. The cells settled into the honeycomb recess, were unable to attach to the nonadhesive hydrogel and so cell-to-cell adhesion drove the self-assembly of a large multicellular honeycomb within 24 hours. Distinct morphological changes occurred to the honeycomb and its cells indicating the presence of significant cell-mediated tension. Unlike the spheroid, whose size is constrained by a critical diffusion distance needed to maintain cell viability, the overall size of the honeycomb is not limited. The rapid production of the honeycomb building unit, with its multiple rings of high density cells and open lumen spaces, offers interesting new possibilities for biofabrication strategies. PMID:21828905

  15. The Morphology and Functions of Articular Chondrocytes on a Honeycomb-Patterned Surface

    PubMed Central

    Eniwumide, Joshua O.; Tanaka, Masaru; Nagai, Nobuhiro; Morita, Yuka; de Bruijn, Joost; Yamamoto, Sadaaki; Onodera, Shin; Kondo, Eiji; Yasuda, Kazunori; Shimomura, Masatsugu

    2014-01-01

    The present study investigated the potential of a novel micropatterned substrate for neocartilage formation. Articular chondrocytes were cultured on poly(?-caprolactone) materials whose surfaces were either flat or honeycomb-patterned. The latter was prepared using a novel self-organization technique, while the former, was prepared by spin-coating. The chondrocytes attached and proliferated on both surfaces. On the honeycomb films, chondrocytes were found at the top surface and encased within the 10??m pores. Meanwhile, chondrocytes on the spin-coated surface flattened out. Accumulation of DNA and keratin sulphate was comparatively higher on the honeycomb films within the first 7 days. At their respective peaks, DNA concentration increased on the honeycomb and flat surfaces by approximately 210% and 400% of their day 1 values, respectively. However, cultures on the flat surface took longer to peak. Extracellular Matrix (ECM) concentrations peaked at 900% and 320% increases for the honeycomb and flat cultures. Type II collagen was upregulated on the honeycomb and flat surfaces by as much as 28% and 25% of their day 1 values, while aggrecan was downregulated with time, by 3.4% and 7.4%. These initial results demonstrate the potential usefulness of honeycomb-based scaffolds during early cultures neocartilage and soft tissue engineering. PMID:24804237

  16. Chiral spin liquid in the frustrated XY model on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Sedrakyan, Tigran

    2015-03-01

    A honeycomb lattice allowing hops between nearest- and next-nearest neighbors hosts ``moat'' bands with degenerate energy minima attained along closed lines in Brillouin zone. If populated with hard-core bosons, a variety of unconventional ground states stabilizes. We argue that the degeneracy prevents Bose condensation, stabilizing novel spin liquid phases including composite fermion state and a chiral spin liquid. The latter stabilizes at half-filling, when the system is equivalent to s = 1 / 2 XY model at zero magnetic field. Absence of condensation means no spontaneous polarization in XY plane, however our consideration indicates formation of a state spontaneously breaking the time-reversal symmetry. This state has a bulk gap and chiral gapless edge excitations, and is similar to the one in Haldane's ``quantum Hall effect without Landau levels'' in its topologically nontrivial sector with Chen number C = +/- 1 . The applications of the developed analytical theory include an explanation of recent unexpected numerical findings and a suggestion of a chiral spin liquid realization in experiments with cold atoms in optical lattices.

  17. Aluminum: Recycling of Aluminum Dross\\/Saltcake

    Microsoft Academic Search

    Blazek

    1999-01-01

    As this NICE3 publication details, the objective of this project is to commercialize the process technology to eliminate all landfill waste associated with black dross and saltcake generated from aluminum recycling in the United States.

  18. Quantum spin metal state on a decorated honeycomb lattice.

    PubMed

    Tikhonov, K S; Feigel'man, M V

    2010-08-01

    We present a modification of the exactly solvable spin-(1/)2 Kitaev model on the decorated honeycomb lattice, with a ground state of "spin metal" type. The model is diagonalized in terms of Majorana fermions; the latter form a 2D gapless state with a Fermi circle whose size depends on the ratio of exchange couplings. Low-temperature heat capacity C(T) and dynamic spin susceptibility ?(?,T) are calculated in the case of small Fermi circle. Whereas, C(T)?T at low temperatures as it is expected for a Fermi liquid, spin excitations are gapped and ?(?,T) demonstrates unusual behavior with a power-law peak near the resonance frequency. The corresponding exponent as well as the peak shape are calculated. PMID:20868007

  19. Friction-factor characteristics for narrow channels with honeycomb surfaces

    NASA Technical Reports Server (NTRS)

    Ha, T. W.; Morrison, G. L.; Childs, D. W.

    1992-01-01

    The experimental determination of friction-factors for the flow of air in a narrow channel lined with various honeycomb geometries has been carried out. Test results show that, generally, the friction-factor is nearly constant or slightly decreases as the Reynolds number increases, a characteristic common to turbulent flow in pipes. However, in some test geometries this trend is remarkably different. The friction factor dramatically drops and then rises as the Reynolds number increases. This phenomenon can be characterized as a 'friction-factor jump'. Further investigations of the acoustic spectrum and friction-factor measurements for a broad range of Reynolds numbers indicate that the 'friction-factor jump' phenomenon is accompanied by an onset of a normal mode resonance excited coherent flow fluctuation structure, which occurs at Reynolds number of the order of 10,000. The purpose of this paper is to explain the friction-factor-jump phenomenon and friction-factor characteristics.

  20. Projective symmetry of partons in Kitaev's honeycomb model

    NASA Astrophysics Data System (ADS)

    Mellado, Paula

    2015-03-01

    Low-energy states of quantum spin liquids are thought to involve partons living in a gauge-field background. We study the spectrum of Majorana fermions of Kitaev's honeycomb model on spherical clusters. The gauge field endows the partons with half-integer orbital angular momenta. As a consequence, the multiplicities reflect not the point-group symmetries of the cluster, but rather its projective symmetries, operations combining physical and gauge transformations. The projective symmetry group of the ground state is the double cover of the point group. We acknowledge Fondecyt under Grant No. 11121397, Conicyt under Grant No. 79112004, and the Simons Foundation (P.M.); the Max Planck Society and the Alexander von Humboldt Foundation (O.P.); and the US DOE Grant No. DE-FG02-08ER46544 (O.T.).

  1. Topological phase transition on honeycomb lattice with third neighbor hooping

    NASA Astrophysics Data System (ADS)

    Chen, Yao-Hua; Hung, Hsiang-Hsuan; Ting, C. S.

    2014-03-01

    The topological phases originating in spin-orbital coupling systems have attracted great attention in modern condensed matter physics. Many interesting phenomena have been found in recent theoretical and experimental works, such as the integer and fractional quantum Hall effect, topological band insulator, topological Mott insulator, and topological superconductor. We have investigated the topological phase transition on honeycomb lattice with third neighbor hooping by employing the cellular dynamical mean-field theory combining with the continuous-time Monte Carlo method. The non-trivial topological insulator can be found by observing the spin Chern number directly, and the effects of the third neighbor hopping and interaction are also discussed. Furthermore, we also provide the whole phase diagram for interaction, third neighbor hopping, and temperature. This work is supported by the Texas Center for Superconductivity at the University of Houston and by the Robert A. Welch Foundation under Grant No. E-1146.

  2. On the honeycomb conjecture and the Kepler problem

    E-print Network

    Fu-Gao Song; Francis Austin

    2009-07-25

    This paper views the honeycomb conjecture and the Kepler problem essentially as extreme value problems and solves them by partitioning 2-space and 3-space into building blocks and determining those blocks that have the universal extreme values that one needs. More precisely, we proved two results. First, we proved that the regular hexagons are the only 2-dim blocks that have unit area and the least perimeter (or contain a unit circle and have the least area) that tile the plane. Secondly, we proved that the rhombic dodecahedron and the rhombus-isosceles trapezoidal dodecahedron are the only two 3-dim blocks that contain a unit sphere and have the least volume that can fill 3-space without either overlapping or leaving gaps. Finally, the Kepler conjecture can also be proved to be true by introducing the concept of the minimum 2-dim and 3-dim Kepler building blocks.

  3. Porphyrin-based honeycomb films and their antibacterial activity.

    PubMed

    Wang, Yanran; Liu, Yan; Li, Guihua; Hao, Jingcheng

    2014-06-10

    Micrometer-sized porous honeycomb-patterned thin films based on hybrid complexes formed via electrostatic interaction between Mn(III) meso-tetra(4-sulfonatophenyl) porphine chloride (an acid form, {MnTPPS}) and dimethyldioctadecylammonium bromide (DODMABr). The morphology of the microporous thin films can be well regulated by controlling the concentration of MnTPPS-DODMA complexes, DODMABr, and polystyrene (PS), respectively. The formation of the microporous thin films was largely influenced by different solvents. The well-ordered microporous films of MnTPPS-DODMA complexes exhibit a more efficient antibacterial activity under visible light than those of hybrid complexes of nanoparticles modified with DODMABr, implying that well-ordered microporous films containing porphyrin composition can improve photochemical activity and more dominance in applications in biological medicine fields. PMID:24846091

  4. Topological Degeneracy and Vortex Manipulation in Kitaev's Honeycomb Model

    NASA Astrophysics Data System (ADS)

    Kells, G.; Bolukbasi, A. T.; Lahtinen, V.; Slingerland, J. K.; Pachos, J. K.; Vala, J.

    2008-12-01

    The classification of loop symmetries in Kitaev’s honeycomb lattice model provides a natural framework to study the Abelian topological degeneracy. We derive a perturbative low-energy effective Hamiltonian that is valid to all orders of the expansion and for all possible toroidal configurations. Using this form we demonstrate at what order the system’s topological degeneracy is lifted by finite size effects and note that in the thermodynamic limit it is robust to all orders. Further, we demonstrate that the loop symmetries themselves correspond to the creation, propagation, and annihilation of fermions. We note that these fermions, made from pairs of vortices, can be moved with no additional energy cost.

  5. Antiferromagnetism and Kondo screening on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Lin, Heng-Fu; Hong-Shuai, Tao; Guo, Wen-Xiang; Liu, Wu-Ming

    2015-05-01

    Magnetic adatoms in the honeycomb lattice have received tremendous attention due to the interplay between Ruderman–Kittel–Kasuya–Yosida interaction and Kondo coupling leading to very rich physics. Here we study the competition between the antiferromagnetism and Kondo screening of local moments by the conduction electrons on the honeycomb lattice using the determinant quantum Monte Carlo method. While changing the interband hybridization V, we systematically investigate the antiferromagnetic-order state and the Kondo singlet state transition, which is characterized by the behavior of the local moment, antiferromagnetic structure factor, and the short range spin-spin correlation. The evolution of the single particle spectrum are also calculated as a function of hybridization V, we find that the system presents a small gap in the antiferromagnetic-order region and a large gap in the Kondo singlet region in the Fermi level. We also find that the localized and itinerant electrons coupling leads to the midgap states in the conduction band in the Fermi level at very small V. Moreover, the formation of antiferromagnetic order and Kondo singlet are studied as on-site interaction U or temperature T increasing, we have derived the phase diagrams at on-site interaction U (or temperature T) and hybridization V plane. Project supported by the National Key Basic Research Special Foundation of China (Grants Nos. 2011CB921502 and 2012CB821305), the National Natural Science Foundation of China (Grants Nos. 61227902, 61378017, and 11434015), the State Key Laboratory for Quantum Optics and Quantum Optical Devices, China (Grant No. KF201403).

  6. Theoretical Predictions of Freestanding Honeycomb Sheets of Cadmium Chalcogenides

    SciTech Connect

    Zhou, Jia [ORNL] [ORNL; Huang, Jingsong [ORNL] [ORNL; Sumpter, Bobby G [ORNL] [ORNL; Kent, Paul R [ORNL] [ORNL; Xie, Yu [ORNL] [ORNL; Terrones Maldonado, Humberto [ORNL] [ORNL; Smith, Sean C [ORNL] [ORNL

    2014-01-01

    Two-dimensional (2D) nanocrystals of CdX (X = S, Se, Te) typically grown by colloidal synthesis are coated with organic ligands. Recent experimental work on ZnSe showed that the organic ligands can be removed at elevated temperature, giving a freestanding 2D sheet of ZnSe. In this theoretical work, freestanding single- to few-layer sheets of CdX, each possessing a pseudo honeycomb lattice, are considered by cutting along all possible lattice planes of the bulk zinc blende (ZB) and wurtzite (WZ) phases. Using density functional theory, we have systematically studied their geometric structures, energetics, and electronic properties. A strong surface distortion is found to occur for all of the layered sheets, and yet all of the pseudo honeycomb lattices are preserved, giving unique types of surface corrugations and different electronic properties. The energetics, in combination with phonon mode calculations and molecular dynamics simulations, indicate that the syntheses of these freestanding 2D sheets could be selective, with the single- to few-layer WZ110, WZ100, and ZB110 sheets being favored. Through the GW approximation, it is found that all single-layer sheets have large band gaps falling into the ultraviolet range, while thicker sheets in general have reduced band gaps in the visible and ultraviolet range. On the basis of the present work and the experimental studies on freestanding double-layer sheets of ZnSe, we envision that the freestanding 2D layered sheets of CdX predicted herein are potential synthesis targets, which may offer tunable band gaps depending on their structural features including surface corrugations, stacking motifs, and number of layers.

  7. Aspects of aluminum toxicity

    SciTech Connect

    Hewitt, C.D.; Savory, J.; Wills, M.R. (Univ. of Virginia Health Sciences Center, Charlottesville (USA))

    1990-06-01

    Aluminum is the most abundant metal in the earth's crust. The widespread occurrence of aluminum, both in the environment and in foodstuffs, makes it virtually impossible for man to avoid exposure to this metal ion. Attention was first drawn to the potential role of aluminum as a toxic metal over 50 years ago, but was dismissed as a toxic agent as recently as 15 years ago. The accumulation of aluminum, in some patients with chronic renal failure, is associated with the development of toxic phenomena; dialysis encephalopathy, osteomalacic dialysis osteodystrophy, and an anemia. Aluminum accumulation also occurs in patients who are not on dialysis, predominantly infants and children with immature or impaired renal function. Aluminum has also been implicated as a toxic agent in the etiology of Alzheimer's disease, Guamiam amyotrophic lateral sclerosis, and parkinsonism-dementia. 119 references.

  8. Aluminum powder metallurgy processing

    SciTech Connect

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  9. Aluminum in automobiles

    SciTech Connect

    Kasper, A.S.

    1983-11-01

    Automotive materials conversion to aluminum is increasing from 35 kgs in the 70's to more than 60 kgs average in the 1983 U.S. vehicles. To control mass, aluminum intensive vehicles with 180 kgs of aluminum are already in production for greater luxury, roominess, performance, and fuel efficiency. Optimization of aluminum designs and processing is achieved through the total design concept of ''Putting It All Together''. A total of 225 kgs improves performance and maximizes the benefits for upsized vehicles by using current production components, drive trains, power plants, and press plant equipment.

  10. Experimental investigation and constitutive modeling of metallic honeycombs in sandwich structures

    E-print Network

    Mohr, Dirk, 1976-

    2003-01-01

    Traditionally, honeycomb sandwich structures are designed in the elastic range, but recent studies on the crushing of sandwich profiles have shown their potential in crashworthiness applications. Thin sandwich sheets also ...

  11. A study of the effects of eccentricity on honeycomb annular gas seals 

    E-print Network

    Weatherwax, Mark

    2001-01-01

    Results are presented which show the effects of eccentricity on high pressure honeycomb and smooth annular gas seals. The results of the experiments indicate the ability to utilize centered seal solutions for rotordynamic coefficients and seal...

  12. Two-dimensional transition metal honeycomb realized: Hf on Ir(111).

    PubMed

    Li, Linfei; Wang, Yeliang; Xie, Shengyi; Li, Xian-Bin; Wang, Yu-Qi; Wu, Rongting; Sun, Hongbo; Zhang, Shengbai; Gao, Hong-Jun

    2013-10-01

    Two-dimensional (2D) honeycomb systems made of elements with d electrons are rare. Here, we report the fabrication of a transition metal (TM) 2D layer, namely, hafnium crystalline layers on Ir(111). Experimental characterization reveals that the Hf layer has its own honeycomb lattice, morphologically identical to graphene. First-principles calculations provide evidence for directional bonding between adjacent Hf atoms, analogous to carbon atoms in graphene. Calculations further suggest that the freestanding Hf honeycomb could be ferromagnetic with magnetic moment ?/Hf = 1.46 ?(B). The realization and investigation of TM honeycomb layers extend the scope of 2D structures and could bring about novel properties for technological applications. PMID:24016148

  13. Carbothermic Aluminum Production Using Scrap Aluminum As A Coolant

    DOEpatents

    LaCamera, Alfred F. (Trafford, PA)

    2002-11-05

    A process for producing aluminum metal by carbothermic reduction of alumina ore. Alumina ore is heated in the presence of carbon at an elevated temperature to produce an aluminum metal body contaminated with about 10-30% by wt. aluminum carbide. Aluminum metal or aluminum alloy scrap then is added to bring the temperature to about 900-1000.degree. C. and precipitate out aluminum carbide. The precipitated aluminum carbide is filtered, decanted, or fluxed with salt to form a molten body having reduced aluminum carbide content.

  14. A comparison of experimental and theoretical results for labyrinth gas seals with honeycomb stators 

    E-print Network

    Hawkins, Lawrence Allen

    1988-01-01

    are compared to the coefficients of a labyrinth-rotor/smooth-stator seal having the same geometry. The coefficients are also compared to analytical results from a two-control-volume compressible ffow model. The experimental results show that the honeycomb... stator conffguration is more stable than the smooth stator conffguration at low rotor speeds. At high rotor speeds and low clearance, the smooth stator seal is more stable. The theoretical model predicts the cross- coupled stiffness of the honeycomb...

  15. Honeycomb-panel spacecraft radiator with multichip module thermal analysis and vacuum-testing

    Microsoft Academic Search

    John Chapter

    1997-01-01

    This paper documents a thermal vacuum test and analysis of three small honeycomb panels for spacecraft application. The prime purpose of this test was to characterize the thermal performance of 24.1 cm×31.8 cm (9.5 in×12.5 in) honeycomb panels that use composite face-sheets with a power dissipating Multichip Module (MCM) mounted on one side. The test MCM simulates electronic circuits and

  16. Catalytic ozonation for the degradation of nitrobenzene in aqueous solution by ceramic honeycomb-supported manganese

    Microsoft Academic Search

    Lei Zhao; Jun Ma; Zhi-zhong Sun; Xue-dong Zhai

    2008-01-01

    Catalytic ozonation of nitrobenzene in aqueous solution has been carried out in a semi-continuous laboratory reactor where ceramic honeycomb and Mn–ceramic honeycomb have been used as the catalysts. The presences of the two catalysts significantly improve the degradation efficiency of nitrobenzene, the utilization efficiency of ozone and the production of oxidative intermediate species compared to the results from non-catalytic ozonation,

  17. Diffusion bonded boron/aluminum spar-shell fan blade

    NASA Technical Reports Server (NTRS)

    Carlson, C. E. K.; Cutler, J. L.; Fisher, W. J.; Memmott, J. V. W.

    1980-01-01

    Design and process development tasks intended to demonstrate composite blade application in large high by-pass ratio turbofan engines are described. Studies on a 3.0 aspect radio space and shell construction fan blade indicate a potential weight savings for a first stage fan rotor of 39% when a hollow titanium spar is employed. An alternate design which featured substantial blade internal volume filled with titanium honeycomb inserts achieved a 14% potential weight savings over the B/M rotor system. This second configuration requires a smaller development effort and entails less risk to translate a design into a successful product. The feasibility of metal joining large subsonic spar and shell fan blades was demonstrated. Initial aluminum alloy screening indicates a distinct preference for AA6061 aluminum alloy for use as a joint material. The simulated airfoil pressings established the necessity of rigid air surfaces when joining materials of different compressive rigidities. The two aluminum alloy matrix choices both were successfully formed into blade shells.

  18. Effect of honeycomb seals on loss characteristics in shroud cavities of an axial turbine

    NASA Astrophysics Data System (ADS)

    Gao, Jie; Zheng, Qun; Wang, Zheng

    2013-01-01

    The loss in efficiency due to shroud leakage or tip clearance flow accounts for a substantial part of the overall losses in turbomachinery. It is important to identify the leakage loss characteristics in order to optimize turbomachinery. At present, little information is available in the open literature concerning the effect of honeycomb seals on the loss characteristics in shroud cavities of an axial turbine, despite of the widespread use of the honeycomb seals. Therefore, interaction between rotor labyrinth seal leakage flow with and without honeycomb facings and main flow is investigated to provide the loss characteristics of the mixing process of the re-entering leakage flow into the main flow. The effects of honeycomb seals on the flow in shroud cavities and interaction with the main flow are analyzed. An additional study on the impact of subtle shroud cavity exit geometry is also presented. The investigation results indicate that the honeycomb seal affects the over tip leakage flow and reduces mixing losses when compared to the solid labyrinth seal. The leakage flow interactions with the main flow have considerably changed the flow fields in the endwall regions. The proposed research reveals the effects of honeycomb seals on the loss characteristics in shroud cavities and the impact of subtle shroud cavity exit geometry, and it is helpful for the design optimization of turbomachinery.

  19. Anodizing Aluminum with Frills.

    ERIC Educational Resources Information Center

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are also…

  20. Correlating Aluminum Burning Times

    Microsoft Academic Search

    M. W. Beckstead

    2005-01-01

    Characteristics of aluminum combustion are summarized in an overview of the subject, focusing on the burning time of individual particles. Combustion data from over ten different sources with almost 400 datum points have been cataloged and correlated. Available models have also been used to evaluate combustion trends with key environmental parameters. The fundamental concepts that control aluminum combustion are discussed,

  1. Formability of Aluminum 5182Polypropylene Sandwich Sheet for Automotive Application

    Microsoft Academic Search

    Kee Joo Kim; Cheol-Woong Kim; Byung-Ik Choi; Chang Won Sung; Heon Young Kim; Si-Tae Won; Ho-Yeun Ryu

    2008-01-01

    The AA5182\\/polypropylene\\/AA5182 (AA\\/PP\\/AA) sandwich sheet is the material fabricated by adhering two aluminum skins to one polypropylene core. When it has the same flexural rigidity as a steel sheet, it is 65% lighter than the steel sheet and 30% lighter than an aluminum alloy sheet. Therefore, it is notified exclusively as good substitutive materials for a steel body to improve

  2. The Aluminum Smelting Process

    PubMed Central

    2014-01-01

    This introduction to the industrial primary aluminum production process presents a short description of the electrolytic reduction technology, the history of aluminum, and the importance of this metal and its production process to modern society. Aluminum's special qualities have enabled advances in technologies coupled with energy and cost savings. Aircraft capabilities have been greatly enhanced, and increases in size and capacity are made possible by advances in aluminum technology. The metal's flexibility for shaping and extruding has led to architectural advances in energy-saving building construction. The high strength-to-weight ratio has meant a substantial reduction in energy consumption for trucks and other vehicles. The aluminum industry is therefore a pivotal one for ecological sustainability and strategic for technological development. PMID:24806722

  3. Aluminum structural applications

    SciTech Connect

    Lucas, G. [Alcan Rolled Products Co., Farmington Hills, MI (United States)

    1996-05-01

    Extensive research by aluminum producers and automakers in the 1980s resulted in the development of technologies that enable building of aluminum cars that meet and exceed all the expectations of today`s drivers and passengers, yet weigh several hundred pounds less than their steel counterparts. The Acura NSX sports car, the Audi A8, and the Jaguar XJ220 have all been introduced. Ford has built 40 aluminum-intensive automobiles based on the Taurus/Sable for test purposes, and General Motors recently announced an aluminum-structured electric vehicle. The design flexibility that aluminum allows is shown by these examples. Each uses a somewhat different technology that is particularly suited to the vehicle and its market.

  4. The aluminum smelting process.

    PubMed

    Kvande, Halvor

    2014-05-01

    This introduction to the industrial primary aluminum production process presents a short description of the electrolytic reduction technology, the history of aluminum, and the importance of this metal and its production process to modern society. Aluminum's special qualities have enabled advances in technologies coupled with energy and cost savings. Aircraft capabilities have been greatly enhanced, and increases in size and capacity are made possible by advances in aluminum technology. The metal's flexibility for shaping and extruding has led to architectural advances in energy-saving building construction. The high strength-to-weight ratio has meant a substantial reduction in energy consumption for trucks and other vehicles. The aluminum industry is therefore a pivotal one for ecological sustainability and strategic for technological development. PMID:24806722

  5. Degassing of Aluminum Alloys Using Ultrasonic Vibration

    SciTech Connect

    Meek, T. T.; Han, Q.; Xu, H.

    2006-06-01

    The research was intended to lead to a better fundamental understanding of the effect of ultrasonic energy on the degassing of liquid metals and to develop practical approaches for the ultrasonic degassing of alloys. The goals of the project described here were to evaluate core principles, establish a quantitative basis for the ultrasonic degassing of aluminum alloy melts, and demonstrate the application of ultrsaonic processing during ingot casting and foundry shape casting.

  6. Aluminum monocarbonyl and aluminum isocarbonyl Steve S. Wesolowski,a)

    E-print Network

    Crawford, T. Daniel

    Aluminum monocarbonyl and aluminum isocarbonyl Steve S. Wesolowski,a) T. Daniel Crawford,b) Justin of the aluminum monocarbonyl species AlCO and AlOC have been performed to predict the geometries, fragmentation, Ogden, and Oswald6 first isolated aluminum dicarbonyls in solid krypton and identified the species

  7. Competing topological and Kondo insulator phases on a honeycomb lattice.

    PubMed

    Feng, Xiao-Yong; Dai, Jianhui; Chung, Chung-Hou; Si, Qimiao

    2013-07-01

    We investigate the competition between the spin-orbit interaction of itinerant electrons and their Kondo coupling with local moments densely distributed on the honeycomb lattice. We find that the model at half-filling displays a quantum phase transition between topological and Kondo insulators at a nonzero Kondo coupling. In the Kondo-screened case, tuning the electron concentration can lead to a new topological insulator phase. The results suggest that the heavy-fermion phase diagram contains a new regime with a competition among topological, Kondo-coherent and magnetic states, and that the regime may be especially relevant to Kondo lattice systems with 5d-conduction electrons. Finally, we discuss the implications of our results in the context of the recent experiments on SmB(6) implicating the surface states of a topological insulator, as well as the existing experiments on the phase transitions in SmB(6) under pressure and in CeNiSn under chemical pressure. PMID:23863017

  8. Majorana edge modes in Kitaev model on honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Thakurathi, Manisha; Sengupta, Krishnendu; Sen, Diptiman

    2015-03-01

    We study the Majorana modes, both equilibrium and Floquet, which can appear at the edges of the Kitaev model on the honeycomb lattice. We first present the analytical solutions known for the equilibrium Majorana edge modes for both zigzag and armchair edges of a semi-infinite Kitaev model and chart the parameter regimes of the model in which they appear. We then examine how edge modes can be generated if the Kitaev coupling on the bonds perpendicular to the edge is varied periodically in time as periodic ?-function kicks. We derive a general condition for the appearance and disappearance of the Floquet edge modes as a function of the drive frequency for a generic d-dimensional integrable system. We confirm this general condition for the Kitaev model with a finite width by mapping it to a one-dimensional model. Our numerical and analytical study of this problem shows that Floquet Majorana modes can appear on some edges in the kicked system even when the corresponding equilibrium Hamiltonian has no Majorana mode solutions on those edges. We support our analytical studies by numerics for finite sized system which show that periodic kicks can generate modes at the edges and the corners of the lattice. We thank CSIR, India and DST, India for financial support.

  9. Safety Evaluation of Dietary Aluminum

    Microsoft Academic Search

    Madhusudan G. Soni; Susan M. White; W. Gary Flamm; George A. Burdock

    2001-01-01

    Aluminum is a nonessential metal to which humans are frequently exposed. Aluminum in the food supply comes from natural sources, water used in food preparation, food ingredients, and utensils used during food preparations. The amount of aluminum in the diet is small, compared with the amount of aluminum in antacids and some buffered analgesics. The healthy human body has effective

  10. Development of application technique of aluminum sandwich sheets for automotive hood

    Microsoft Academic Search

    Kee Joo Kim; Meung Ho Rhee; Byung-Ik Choi; Cheol-Woong Kim; Chang-Won Sung; Chang-Pyung Han; Ki-Weon Kang; Si-Tae Won

    2009-01-01

    Objective of this study was to develop basic techniques in order to apply aluminum sandwich sheets for an automotive hood\\u000a part. The aluminum sandwich sheet is the material fabricated by adhering two aluminum skins to one polypropylene core. When\\u000a it has the same bending stiffness as a steel sheet, it is 65% lighter than the steel sheet and 30% lighter

  11. Novel Aharonov-Bohm-like effect: Detectability of the vector potential in a solenoidal configuration with a ferromagnetic core covered by superconducting lead, and surrounded by a thin cylindrical shell of aluminum

    E-print Network

    R. Y. Chiao

    2012-06-23

    The flux as measured by the Josephson effect in a SQUID-like configuration with a ferromagnetic core inserted into its center, is shown to be sensitive to the vector potential arising from the central ferromagnetic core, even when the core is covered with a superconducting material that prevents any magnetic field lines from ever reaching the perimeter of the SQUID-like configuration. This leads to a macroscopic, Aharonov-Bohm-like effect that is observable in an asymmetric hysteresis loop in the response of the SQUID-like configuration to an externally applied magnetic field.

  12. Porous and Microporous Honeycomb Composites as Potential Boundary-Layer Bleed Materials

    NASA Technical Reports Server (NTRS)

    Davis, D. O.; Willis, B. P.; Schoenenberger, M.

    1997-01-01

    Results of an experimental investigation are presented in which the use of porous and microporous honeycomb composite materials is evaluated as an alternate to perforated solid plates for boundary-layer bleed in supersonic aircraft inlets. The terms "porous" and "microporous," respectively, refer to bleed orifice diameters roughly equal to and much less than the displacement thickness of the approach boundary-layer. A Baseline porous solid plate, two porous honeycomb, and three microporous honeycomb configurations are evaluated. The performance of the plates is characterized by the flow coefficient and relative change in boundary-layer profile parameters across the bleed region. The tests were conducted at Mach numbers of 1.27 and 1.98. The results show the porous honeycomb is not as efficient at removing mass compared to the baseline. The microporous plates were about equal to the baseline with one plate demonstrating a significantly higher efficiency. The microporous plates produced significantly fuller boundary-layer profiles downstream of the bleed region for a given mass flow removal rate than either the baseline or the porous honeycomb plates.

  13. Ferromagnetism and quantum anomalous Hall effect in one-side-saturated buckled honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Huang, Shin-Ming; Lee, Shi-Ting; Mou, Chung-Yu

    2014-05-01

    The recently synthesized silicene as well as theoretically discussed germanene are examples of buckled honeycomb structures. The buckled structures allow one to manipulate asymmetry between two underlying sublattices of honeycomb structures. Here by taking germanene as a prototype of buckled honeycomb lattices, we explore magnetism induced by breaking sublattice symmetry through saturating chemical bonds on one side of the buckled honeycomb lattice. It is shown that when fractions of chemical bonds on one side are saturated, two narrow bands always exist at half filling. Furthermore, the narrow bands generally support flat band ferromagnetism in the presence of the Hubbard U interaction. The induced magnetization is directly related to the saturation fraction and is thus controllable in magnitude through the saturation fraction. Most importantly, we find that depending on the saturation fraction, the ground state of a one-side-saturated germanene may become a quantum anomalous Hall (QAH) insulator characterized by a Chern number that vanishes for larger magnetization. The nonvanishing Chern number for smaller magnetization implies that the associated quantum Hall effect tends to survive at high temperatures. Our findings provide a potential method to engineer buckled honeycomb structures into high-temperature QAH insulators.

  14. Detection of disbonds in a honeycomb composite structure using guided waves

    NASA Astrophysics Data System (ADS)

    Baid, Harsh; Banerjee, Sauvik; Joshi, Shiv; Mal, Siddhartha

    2008-03-01

    Advanced composites are being used increasingly in state-of-the-art aircraft and aerospace structures. In spite of their many advantages composite materials are highly susceptible to hidden flaws that may occur at any time during the life cycle of a structure and if undetected, may cause sudden and catastrophic failure of the entire structure. An example of such a defects critical structural component is the "honeycomb composite" in which thin composite skins are bonded with adhesives to the two faces of extremely lightweight and relatively thick metallic honeycombs. These components are often used in aircraft and aerospace structures due to their high strength to weight ratio. Unfortunately, the bond between the honeycomb and the skin may degrade with age and service loads leading to separation of the load-bearing skin from the honeycomb (called "disbonds") and compromising the safety of the structure. This paper is concerned with the noninvasive detection of disbonds using ultrasonic guided waves. Laboratory experiments are carried out on a composite honeycomb specimen containing localized disbonded regions. Ultrasonic waves are launched into the specimen using a broadband PZT transducer and are detected by a distributed array of identical transducers located on the surface of the specimen. The guided wave components of the signals are shown to be very strongly influenced by the presence of a disbond. The experimentally observed results are being used to develop an autonomous scheme to locate the disbonds and to estimate their size.

  15. Advances in aluminum anodizing

    NASA Technical Reports Server (NTRS)

    Dale, K. H.

    1969-01-01

    White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.

  16. Corrosion Inhibitors for Aluminum.

    ERIC Educational Resources Information Center

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  17. Thermal insulation with paper honeycombs with solar gain

    SciTech Connect

    Hingerl, K.; Baumgartner, G.; Aschauer, H.

    1996-12-31

    In this contribution the authors describe the concept and the model for the heat flux and the effective U-value of paper honeycombs (PHC) used as efficient and cheap transparent insulation material. With this thermal-insulation-material static U-values of U = 0.25 W/(m{sup 2}K) are obtained due to the very low thermal conduction value {lambda} = 0.04 W/(mK), which is comparable to thermal insulators as PU-foam or mineral wool. Contrary to conventional insulation materials PHC also gathers solar radiation due to its geometry, thereby providing heat flux into the interior of the building. Because the angle of incidence of the sun in wintertime is low, the direct solar radiation is absorbed approximately within the outermost 3 centimeters of the PHC. Even at ambient temperatures below 0 C, this region is warmed up to 60 C. By conduction the heat is brought to the brick wall underneath, which acts as reservoir and gets to temperatures between 15 and 30 C. Calculated across the full heating period, it is shown, that effective U values of 0.14 W/(m{sup 2}K) are reached by using PHC, reducing the brick wall U value by a factor of 3/4. Contrary to other transparent thermal insulation systems, e.g. developed by the Fraunhofer Institute for Solar Energy Systems, this system does not overheat during summertime, because the capillary structure is shielding the solar rays. A Windows based program solves the heat conduction equation with finite element methods.

  18. Complete band gaps and deaf bands of triangular and honeycomb water-steel phononic crystals

    NASA Astrophysics Data System (ADS)

    Hsiao, Fu-Li; Khelif, Abdelkrim; Moubchir, Hanane; Choujaa, Abdelkrim; Chen, Chii-Chang; Laude, Vincent

    2007-02-01

    Phononic crystals with triangular and honeycomb lattices are investigated experimentally and theoretically. They are composed of arrays of steel cylinders immersed in water. The measured transmission spectra reveal the existence of complete band gaps but also of deaf bands. Band gaps and deaf bands are identified by comparing band structure computations, obtained by a periodic-boundary finite element method, with transmission simulations, obtained using the finite difference time domain method. The appearance of flat bands and the polarization of the associated eigenmodes is also discussed. Triangular and honeycomb phononic crystals with equal cylinder diameter and smallest spacing are compared. As previously obtained with air-solid phononic crystals, it is found that the first complete band gap opens for the honeycomb lattice but not for the triangular lattice, thanks to symmetry reduction.

  19. Realization of a three-dimensional spin-anisotropic harmonic honeycomb iridate.

    PubMed

    Modic, K A; Smidt, Tess E; Kimchi, Itamar; Breznay, Nicholas P; Biffin, Alun; Choi, Sungkyun; Johnson, Roger D; Coldea, Radu; Watkins-Curry, Pilanda; McCandless, Gregory T; Chan, Julia Y; Gandara, Felipe; Islam, Z; Vishwanath, Ashvin; Shekhter, Arkady; McDonald, Ross D; Analytis, James G

    2014-01-01

    Spin and orbital quantum numbers play a key role in the physics of Mott insulators, but in most systems they are connected only indirectly--via the Pauli exclusion principle and the Coulomb interaction. Iridium-based oxides (iridates) introduce strong spin-orbit coupling directly, such that these numbers become entwined together and the Mott physics attains a strong orbital character. In the layered honeycomb iridates this is thought to generate highly spin-anisotropic magnetic interactions, coupling the spin to a given spatial direction of exchange and leading to strongly frustrated magnetism. Here we report a new iridate structure that has the same local connectivity as the layered honeycomb and exhibits striking evidence for highly spin-anisotropic exchange. The basic structural units of this material suggest that a new family of three-dimensional structures could exist, the 'harmonic honeycomb' iridates, of which the present compound is the first example. PMID:24969742

  20. Monte Carlo study of degenerate ground states and residual entropy in a frustrated honeycomb lattice Ising model

    E-print Network

    De Sterck, Hans

    Monte Carlo study of degenerate ground states and residual entropy in a frustrated honeycomb a classical fully frustrated honeycomb lattice Ising model using Markov-chain Monte Carlo methods and exact that grows as the number of spins N. Traditional single-spin-flip Monte Carlo methods fail to sample all

  1. Enhanced Cell Survival and Yield of Rat Small Hepatocytes by Honeycomb-Patterned Films

    NASA Astrophysics Data System (ADS)

    Tsukiyama, Shusaku; Matsushita, Michiaki; Tanaka, Masaru; Tamura, Hitoshi; Todo, Satoru; Yamamoto, Sadaaki; Shimomura, Masatsugu

    2008-02-01

    Surface designing of substrate to regulate cell adhesion and function in nano and micro scale is a critical issue in biomaterial science. In this study, we describe the fabrication of highly regular patterned porous films (honeycomb-patterned film) formed by a simply casting technique, and the culture of mature hepatocytes and small hepatocytes on the films. The pore size of the honeycomb-patterned films used was 6, 12, and 16 µm. We evaluated the effect of the honeycomb-patterned films on the morphology, cell yield, survival and the differentiated hepatic function (albumin production) of the both hepatocytes. Both hepatocytes attached on the flat films appeared to spread well, showing a typical monolayer morphology. They peeled off from the films at 7 days in culture on the flat films. On the other hand, spreading of the each hepatocytes was restricted on the honeycomb-patterned films at 3 and 7 days in culture. The cell yield and survival of the each hepatocytes increased with increasing culture time. Small hepatocyte on the pore sizes of 16 µm showed the highest cell yield (approximately 3 times). Albumin production of mature hepatocyte on the pore sizes of 16 µm (224.1.3 ±157 ng ml-1 well-1 at 1 day in culture, 369.5 ±222 ng ml-1 well-1 at 3 days in culture) was higher than that of the hepatocytes on the flat films (119.3 ±9.3 ng ml-1 well-1 at 1 day in culture, 262.8 ±47.3 ng ml-1 well-1 at 3 days in culture), although that of small hepatocytes on the honeycomb-patterned films (pore size: 16 µm) was similar on the flat film. These results indicated that both the surface topography and the pore size of the honeycomb-patterned film affected the hepatic metabolic function.

  2. Aluminum, parathyroid hormone, and osteomalacia

    SciTech Connect

    Burnatowska-Hledin, M.A.; Kaiser, L.; Mayor, G.H.

    1983-01-01

    Aluminum exposure in man is unavoidable. The occurrence of dialysis dementia, vitamin D-resistant osteomalacia, and hypochromic microcytic anemia in dialysis patients underscores the potential for aluminum toxicity. Although exposure via dialysate and hyperalimentation leads to significant tissue aluminum accumulation, the ubiquitous occurrence of aluminum and the severe pathology associated with large aluminum burdens suggest that smaller exposures via the gastrointestinal tract and lungs could represent an important, though largely unrecognized, public health problem. It is clear that some aluminum absorption occurs with the ingestion of small amounts of aluminum in the diet and medicines, and even greater aluminum absorption is seen in individuals consuming large amounts of aluminum present in antacids. Aluminum absorption is enhanced in the presence of elevated circulating parathyroid hormone. In addition, elevated PTH leads to the preferential deposition of aluminum in brain and bone. Consequently, PTH is likely to be involved in the pathogenesis of toxicities in those organs. PTH excess also seems to lead to the deposition of aluminum in the parathyroid gland. The in vitro demonstration that aluminum inhibits parathyroid hormone release is consistent with the findings of a euparathyroid state in dialysis patients with aluminum related vitamin D-resistant osteomalacia. Nevertheless, it seems likely that hyperparathyroidism is at least initially involved in the pathogenesis of aluminum neurotoxicity and osteomalacia; the increases in tissue aluminum stores are followed by suppression of parathyroid hormone release, which is required for the evolution of osteomalacia. Impaired renal function is not a prerequisite for increased tissue aluminum burdens, nor for aluminum-related organ toxicity. Consequently, it is likely that these diseases will be observed in populations other than those with chronic renal disease.

  3. Flow past an array of catalyst blocks with a honeycomb structure

    SciTech Connect

    Bespalov, A.V.

    1992-07-10

    There is interest in an organized stationary catalyst beds consisting of block catalysts with a honeycomb structure: The flow is directed between vertically positioned blocks, in which the through channels are oriented perpendicularly to the direction of the incident flow ({alpha} = 90{degrees}). Calculations of the flow past a single block of honey comb structure were performed for this case, and it has been shown that the surface of the through channel is accessible to the reaction flow. The authors continued this effort to quantitate the flow with honeycomb catalysts. 9 refs., 2 figs.

  4. Non-affine fluctuations and the statistics of defect precursors in the planar honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Mitra, Amartya; Ganguly, Saswati; Sengupta, Surajit; Sollich, Peter

    2015-06-01

    Certain localised displacement fluctuations in the planar honeycomb lattice may be identified as precursors to topological defects. We show that these fluctuations are among the most pronounced non-affine distortions of an elemental coarse graining volume of the honeycomb structure at non zero temperatures. We obtain the statistics of these precursor modes in the canonical ensemble, evaluating exactly their single point and two-point spatio-temporal distributions, for a lattice with harmonic nearest neighbour and next near neighbour bonds. As the solid is destabilised by tuning interactions, the precursor fluctuations diverge and correlations become long-lived and long-ranged.

  5. Combination of plasma with a honeycomb-structured catalyst for automobile exhaust treatment.

    PubMed

    Kang, Woo Seok; Lee, Dae Hoon; Lee, Jae-Ok; Hur, Min; Song, Young-Hoon

    2013-10-01

    To activate a catalyst efficiently at low temperature by plasma for environmental control, we developed a hybrid reactor that combines plasma with a honeycomb-structured catalyst in a practical manner. The reactor developed generated stable cold plasma at atmospheric pressure because of the dielectric and conductive nature of the honeycomb catalyst by consuming low amounts of power. In this reactor, the applied voltage and temperature determined the balance between the oxidation and adsorption by the plasma and catalyst. The synergistic reaction of the plasma and catalyst was more effective at low temperatures, resulting in a reduction in a lowered light-off temperature. PMID:23991700

  6. Recycled Aluminum Ornaments

    NSDL National Science Digital Library

    Wishart, Ray

    This lesson plan from ATEEC will explain the principles of recycling. The activity would be most appropriate for technology studies or high school science classes. In all, it would require 2-5 hours of class time to complete. The purpose of the lesson is to demonstrate how aluminum is recycled. This laboratory activity does require some special equipment including a heat source capable of melting aluminum and an outdoor work area. Extension activities are also provided. The lesson plan is available for download as a PDF; users must create a free, quick login with ATEEC to access the materials.

  7. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan (Mastic, NY); Reilly, James J. (Bellport, NY)

    2009-04-21

    The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.

  8. Molecular Structure of Aluminum Fluoride

    NSDL National Science Digital Library

    2003-06-02

    Aluminum Fluoride is a solid, off-white, free-flowing granular material, insoluble in most organic and inorganic liquids at room temperatures. It is soluble in many fused salts. Aluminum Fluoride is used by aluminum producers to increase the conductivity of electrolytes in the smelting process. It is used as a flux ingredient for the removal of magnesium in refining aluminum scrap, by the ceramic industry for some body and glazing mixtures, and in the production of specialty refractory products.

  9. Possible use of honeycomb-type structures for high power batteries and fuel cells

    Microsoft Academic Search

    J. T. Kummer

    1980-01-01

    The paper describes a possible method for constructing a Kapitza-type battery that differs from the usual thin plate approach, and may be simpler to construct, as well as a possible method for constructing a fuel cell that may offer an economic advantage over present methods. Both experiments employ a honeycomb structure of the type used as a substrate for auto

  10. All-to-all Broadcasting Algorithms on Honeycomb Networks and Applications

    Microsoft Academic Search

    Jean Carle; Jean Frederic Myoupo; David Seme

    1999-01-01

    This paper presents two simple all-to-all broadcasting algorithms on honeycomb mesh. Consider a network with n processors, one has personalized routing strategy at each node and it requires a 3n communication time complexity. This communication time can be reduced to n because the computation time is always assumed to be much lower than the communication time. The other is based

  11. Honeycomb Layer of Cobalt(II) Azide Hydrazine Showing Weak Ferromagnetism

    E-print Network

    Gao, Song

    Honeycomb Layer of Cobalt(II) Azide Hydrazine Showing Weak Ferromagnetism Xiu-Teng Wang, Zhe-Ming Wang, and Song Gao* Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare. Chem. ReV. 1999, 193-195, 1027. (b) Zhang, Y.-Z.; Wei, H.-Y.; Pan, F.; Wang, Z.-M.; Chen, Z.-D.; Gao, S

  12. Study made to control depth of potting compound for honeycomb sandwich fasteners

    NASA Technical Reports Server (NTRS)

    Cushman, J.

    1966-01-01

    Study determines optimum fastener insert size and shape, type of embedding cement, diameter, undercut and depth control by fiber glass plug in a honeycomb structure for maximum tensile strength The best potting compound is 5-5-1 weight mixture of epoxy resin, curing agent, and milled glass fibers.

  13. Performance of a novel type of electrolyte-supported solid oxide fuel cell with honeycomb structure

    Microsoft Academic Search

    Juan Carlos Ruiz-Morales; David Marrero-López; Juan Peña-Martínez; Jesús Canales-Vázquez; Joan Josep Roa; Mercè Segarra; Stanislav N. Savvin; Pedro Núñez

    2010-01-01

    A novel design, alternative to the conventional electrolyte-supported solid oxide fuel cell (SOFC) is presented. In this new design, a honeycomb-electrolyte is fabricated from hexagonal cells, providing high mechanical strength to the whole structure and supporting the thin layer used as electrolyte of a SOFC. This new design allows a reduction of ?70% of the electrolyte material and it renders

  14. Dynamic and quasi-static mechanical properties of iron-nickel alloy honeycomb

    Microsoft Academic Search

    Justin L. Clark

    2004-01-01

    Several metal honeycombs, termed Linear Cellular Alloys (LCAs), were fabricated via a paste extrusion process and thermal treatment. Two Fe-Ni based alloy compositions were evaluated. Maraging steel and Super Invar were chosen for their compatibility with the process and the wide range of properties they afforded. Cell wall material was characterized and compared to wrought alloy specifications. The bulk alloy

  15. The Honeycomb Type of Reis-Bücklers’ Dystrophy of the Cornea: Biometrics and an Interpretation

    Microsoft Academic Search

    D. Wittebol-Post; O. P. van Bijsterveld; J. W. Delleman

    1987-01-01

    Corneal thickness increases with advancing age in patients with the honeycomb type of Reis-Bücklers’ dystrophy, affecting visual acuity. A linear relationship is found between these parameters. Also, corneal sensitivity decreases with increasing corneal thickness. The latter may be an import factor in the decrease of ocular irritation later in life in these patients.

  16. The Architecture The universe resembles an unfathomably large honeycomb. Gigantic galaxy clusters occupy

    E-print Network

    The Architecture of Space The universe resembles an unfathomably large honeycomb. Gigantic galaxy of galaxies, and in the process, encounters the invisible aspects of space. What the eye doesn't see: The Coma the individual galaxies (gray spots). X-ray scouts like the ROSAT satellite, on the other hand, reveal

  17. Relationship Between Honeycombing and Collagen Breakdown in Skipjack Tuna, Katsuwonus pelamis

    E-print Network

    , a spoilage condition that affects the connective tissue of tuna, appears after the fish have been given a low surface. In extreme cases the connective tissue appears vac- uolated and resembles a vacant hon- eycomb-Honeycombing, a condi- tion that affects the connective tissue, was studied in skipjack tuna under controlled conditions

  18. Laser-induced agitation and cavitation from proprietary honeycomb tips for endodontic applications.

    PubMed

    George, Roy; Chan, Keith; Walsh, Laurence James

    2015-05-01

    Cavitation and agitation generated by lasers in fluid-filled root canals create fluid movement and shear stresses along the root canals walls, enhancing removal of the smear layer and biofilm. When used with sodium hypochlorite and EDTA, laser activation of aqueous fluids can increase the efficiency of debridement and disinfection of root canals. However, the use of forward-firing laser fibers with such solutions poses a risk of driving fluid past the root apex, which could cause postoperative complications. The purpose of this study was to evaluate the mechanism of fluid agitation caused by a novel honeycomb tip. Glass capillary tubes filled with distilled water were used to replicate single-tooth root canals. A 980 nm pulsed diode laser was used with 200 ?m diameter plain tips, tube-etched conical tips, and honeycomb tips. To record fluid movements, the tubes were backlit and imaged using a digital camera attached to a microscope. The honeycomb tips generated agitation with fluid movement directed onto the walls, while both the conventional plain fibers and the conical tips created fluid movement largely in a forward direction. The use of honeycomb tips alters the pattern of fluid agitation, and this laterally directed effect might lower the risk of fluid extrusion beyond the apex. PMID:24647465

  19. Treatment with an aromatase inhibitor induces complete sex change in the protogynous honeycomb grouper ( Epinephelus merra )

    Microsoft Academic Search

    Ramji K. Bhandari; Mikihiko Higa; Hiroki Komuro; Shigeo Nakamura; Masaru Nakamura

    2003-01-01

    To study the mechanism of protogynous sex change in honeycomb grouper, the wild fish of both sexes and transitionals were collected for one year, and changes in gonadal structures and serum levels of sex hormones in each individual were examined. The onset of sex change was associated with low serum estradiol - 17ß (E2) levels. In order to clarify whether E2 deprivation

  20. Identification of honeycomb sandwich properties by high-resolution modal analysis

    E-print Network

    Paris-Sud XI, Université de

    Identification of honeycomb sandwich properties by high-resolution modal analysis M. R´ebillat X are estimated experimentally by means of a high-resolution modal analysis technique. An optimisation procedure by comparing simulated and measured characteristics (for example modal dampings Num n vs. XP n and frequencies

  1. The honeycomb type of Reis-Bücklers' dystrophy of the cornea: biometrics and an interpretation.

    PubMed

    Wittebol-Post, D; van Bijsterveld, O P; Delleman, J W

    1987-01-01

    Corneal thickness increases with advancing age in patients with the honeycomb type of Reis-Bücklers' dystrophy, affecting visual acuity. A linear relationship is found between these parameters. Also, corneal sensitivity decreases with increasing corneal thickness. The latter may be an import factor in the decrease of ocular irritation later in life in these patients. PMID:3497370

  2. RECLAMATION OF ALUMINUM FINISHING SLUDGES

    EPA Science Inventory

    The research study of the reclamation of aluminum-anodizing sludges was conducted in two sequential phases focused on enhanced dewatering of aluminum-anodizing sludges to produce commercial-strength solutions of aluminum sulfate, i.e., liquid alum. The use of high-pressure (14 to...

  3. Aluminum-lithium for aerospace

    Microsoft Academic Search

    P. S. Fielding; G. J. Wolf

    1996-01-01

    Aluminum-lithium alloys were developed primarily to reduce the weight of aircraft and aerospace structures. Lithium is the lightest metallic element, and each 1% of lithium added to aluminum reduces alloy density by about 3% and increases modulus by about 5%. Though lithium has a solubility limit of 4.2% in aluminum, the amount of lithium ranges between 1 and 3% in

  4. Nanostructured 2D Diporphyrin Honeycomb Film: Photoelectrochemistry, Photodegradation, and Antibacterial Activity.

    PubMed

    Zhao, Yuewu; Shang, Qiuwei; Yu, Jiachao; Zhang, Yuanjian; Liu, Songqin

    2015-06-10

    Surface patterns of well-defined nanostructures play important roles in fabrication of optoelectronic devices and applications in catalysis and biology. In this paper, the diporphyrin honeycomb film, composed of titanium dioxide, protoporphyrin IX, and hemin (TiO2/PPIX/Hem), was synthesized using a dewetting technique with the well-defined polystyrene (PS) monolayer as a template. The TiO2/PPIX/Hem honeycomb film exhibited a higher photoelectrochemical response than that of TiO2 or TiO2/PPIX, which implied a high photoelectric conversion efficiency and a synergistic effect between the two kinds of porphyrins. The TiO2/PPIX/Hem honeycomb film was also a good photosensitizer due to its ability to generate singlet oxygen ((1)O2) under irradiation by visible light. This led to the use of diporphyrin TiO2/PPIX/Hem honeycomb film for the photocatalytic inactivation of bacteria. In addition, the photocatalytic activities of other metal-diporphyrin-based honeycomb films, such as TiO2/MnPPIX/Hem, TiO2/CoPPIX/Hem, TiO2/NiPPIX/Hem, TiO2/CuPPIX/Hem, and TiO2/ZnPPIX/Hem, were investigated. The result demonstrated that the photoelectric properties of diporphyrin-based film could be effectively enhanced by further coupling of porphyrin with metal ions. Such enhanced performance of diporphyrin compounds opened a new way for potential applications in various photoelectrochemical devices and medical fields. PMID:25992484

  5. Towards a better understanding of honeycomb alternating magnetic networks.

    PubMed

    Marino, Nadia; Armentano, Donatella; De Munno, Giovanni; Lloret, Francesc; Cano, Joan; Julve, Miguel

    2015-06-28

    Two new two-dimensional homometallic compounds {[M2(bpm)(ox)2]n·5nH2O} with M = Co(ii) (1) and Zn(ii) (2) and the mononuclear nickel(ii) complex [Ni(bpm)2(ox)]·2H2O (3) [bpm = 2,2'-bipyrimidine and ox = oxalate] have been prepared and structurally characterized. 1 and 2 are isostructural compounds whose structures are made up of oxalate-bridged M(ii) cations cross-linked by bis-bidentate bpm molecules to afford a honeycomb layered network extending in the crystallographic ab plane. The layers are eclipsed along the crystallographic c axis and show graphitic-like interactions between the bpm rings. The three-dimensional supramolecular network deriving from such interactions is characterized by hexagonal-shaped channels extending in the same direction. Each M(ii) ion in 1 and 2 is tris-chelated with four oxygen atoms from two oxalate groups and two bpm-nitrogen atoms building a distorted octahedral surrounding. The reduced values of the angles subtended by the bis-chelating bpm [77.69(8) (1) and 76.59(8)° (2)] and oxalate [79.69(6) (1) and 80.01(5)° (2)] are the main factors accounting for this distortion. The values of the metal-metal separation through bridging bpm are 5.6956(7) (1) and 5.7572(9) Å (2), whereas those across the bis-bidentate oxalate are 5.4306(4) (1) and 5.4058(5) Å (2). 3 is a neutral mononuclear nickel(ii) complex where each metal ion is six-coordinate with four nitrogen atoms from two bpm ligands in a cis arrangement and two oxalate-oxygen atoms building a somewhat distorted octahedral surrounding. The values of the angles subtended at the nickel(ii) ion by bpm and oxalate are 78.14(4) and 80.95(5)°, respectively. The magnetic properties of 1 have been investigated in the temperature range 1.9-295 K. They are typical of an overall antiferromagnetic coupling with a maximum of the magnetic susceptibility at 22.0 K. The analysis of the susceptibility data of 1 through an effective spin Hamiltonian allowed a satisfactory simulation in the temperature range 10-295 K with the best-fit parameters ? = -110 cm(-1), ? = 1.1, |?| = 400 cm(-1), Jox = -11.1 cm(-1) and Jbpm = -5.0 cm(-1). The values of the antiferromagnetic coupling through bpm and ox in 1 have also been supported by electronic structure calculations based on Density Functional Theory (DFT) and they compare well with those reported in the literature for bpm-bridged dicobalt(ii) complexes and oxalate-bridged cobalt(ii) chains. PMID:25994291

  6. Building an aluminum car

    SciTech Connect

    Ashley, S.

    1994-05-01

    This article examines the increasing use of aluminum in automobiles to decrease weight and consequently increase fuel economy. The topics of the article include federal fuel economy goals, the development of optimum body structure and manufacturing techniques, comparison with steel, cost of materials, weight reduction and recycling of materials.

  7. Hydrogen diffusion in aluminum

    Microsoft Academic Search

    R MCLELLAN

    1983-01-01

    Although the diffusivity of hydrogen in aluminum has been measured by several different authors, there is essentially no mutual agreement and the sets of data are separated by orders of magnitude. There is little doubt these mass-flow determinations of the H-diffusivity are subject to great uncertainties connected with the presence of the surface oxide layer, as has been discussed recently

  8. Aluminum Sulfate 18 Hydrate

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

  9. Aluminum Coatings for Steel

    Microsoft Academic Search

    Aruna Bahadur

    1996-01-01

    Aluminum coated steel possesses excellent oxidation and corrosion resistance in sulfur and marine: environments and can substitute for expensive alloy of steels. Hot dip aluminizing (HAD) and pack cementation calorizing (CAL) are dealt with in detail. IN HDA coats, some alloying action takes place, when the substrate is dipped in molten Al at 973 K for 1-2 minutes. The coat

  10. Casting the first 8.4-m borosilicate honeycomb mirror for the Large Binocular Telescope

    NASA Astrophysics Data System (ADS)

    Hill, John M.; Angel, J. Roger P.; Lutz, Randall D.; Olbert, Blain H.; Strittmatter, Peter A.

    1998-08-01

    We report on the casting of the first 8.4 meter diameter borosilicate honeycomb mirror at the Steward Observatory Mirror Laboratory. This blank will become the world's largest monolithic glass telescope mirror, and is the first of two mirrors for the large Binocular Telescope Project. The honeycomb 8.4 meter mirror was cast from 21 tons of E6 borosilicate glass manufactured by Ohara. This glass is melted into a mold constructed of aluminosilicate fiber to produce a honeycomb structure with roughly 20% of solid density. The 1662 hexagonal voids that form the honeycomb structure are produced by ceramic fiber boxes bolted to the bottom of the mold with SiC bolts. The furnace rotates at 6.8 rpm during the casting process to produce the F/1.14 paraboloid on the front surface. This shaping minimizes the amount of glass which must be removed during the grinding process. The front faceplate of the mirror will be 28 mm thick after generating and the back faceplate will be 25 mm. The overall thickness of the finished honeycomb blank is 89 cm at the outer edge and 44 cm at the central hole. The first 8.4 meter mirror blank was cast in January 1997. During the casting, two tons of glass leaked from the mold inside the spinning furnace. After a three month annealing cycle the furnace was opened for inspection. As a result of the leakage about 2 square meters of the faceplate near one edge of the mirror was too thin to be polished. In April 1997, an additional two tons of glass was loaded on top of the intact honeycomb structure. In June 1997, after heating slowly back to the annealing temperature, this extra glass was flash melted onto the front of the blank to assure that the faceplate was of sufficient thickness. After a further three month annealing cycle, the furnace was re-opened to reveal a superb casting with low bubble content and little trace of the fusion boundary. The blank has been removed from the furnace using a fixture glued to the upper surface of the blank. It will soon be stripped of its mold material in preparation for polishing.

  11. Redox-responsive degradable honeycomb manganese oxide nanostructures as effective nanocarriers for intracellular glutathione-triggered drug release.

    PubMed

    He, Dinggeng; He, Xiaoxiao; Wang, Kemin; Yang, Xue; Yang, Xiaoxiao; Zou, Zhen; Li, Xuecai

    2015-01-14

    Redox-responsive degradable honeycomb manganese oxide (hMnO2) nanostructures consisting of some lamellar MnO2 platelets were established as a new class of drug carriers for intracellular glutathione-triggered drug release. PMID:25421350

  12. A comparison of rotordynamic-coefficient predictions for annular honeycomb gas seals using different friction-factor models

    E-print Network

    D'Sousa, Rohan Joseph

    2000-01-01

    Predictions of rotordynamic-coefficients for annular honeycomb gas seals are compared using different friction-factor models. Analysis shows that the fundamental improvement in predicting the rotordynamic-coefficients accurately is the two...

  13. Honeycomb-alumina supported garnet membrane: Composite electrolyte with low resistance and high strength for lithium metal batteries

    NASA Astrophysics Data System (ADS)

    Liu, Kai; Wang, Chang-An

    2015-05-01

    Li-ion ceramic electrolyte material is considered the key for advanced lithium metal batteries, and garnet-type oxides are promising ceramic electrolyte materials. To disentangle the thinness-strength dilemma in garnet-type Li6.4La3Zr1.4Ta0.6O12 (LLZTO) electrolyte, we designed and successfully synthesized a ceramic-ceramic composite electrolyte, i.e. a honeycomb-Al2O3 pellet supported LLZTO membrane. The honeycomb-Al2O3 pellet acts as a supporter to the thin LLZTO membrane and makes the whole composite electrolyte strong enough, while the straight holes in the Al2O3 supporter can be filled with liquid electrolyte and acts as channels for Li+ transportation. Such a composite design eliminates the concern over the LLZTO membrane's fragility, and keeps its good electrical property.

  14. Aluminum microstructures on anodic alumina for aluminum wiring boards.

    PubMed

    Jha, Himendra; Kikuchi, Tatsuya; Sakairi, Masatoshi; Takahashi, Hideaki

    2010-03-01

    The paper demonstrates simple methods for the fabrication of aluminum microstructures on the anodic oxide film of aluminum. The aluminum sheets were first engraved (patterned) either by laser beam or by embossing to form deep grooves on the surface. One side of the sheet was then anodized, blocking the other side by using polymer mask to form the anodic alumina. Because of the lower thickness at the bottom part of the grooves, the part was completely anodized before the complete oxidation of the other parts. Such selectively complete anodizing resulted in the patterns of metallic aluminum on anodic alumina. Using the technique, we fabricated microstructures such as line patterns and a simple wiring circuit-board-like structure on the anodic alumina. The aluminum microstructures fabricated by the techniques were embedded in anodic alumina/aluminum sheet, and this technique is promising for applications in electronic packaging and devices. PMID:20356280

  15. Aluminum toxicity and albumin.

    PubMed

    Kelly, A T; Short, B L; Rains, T C; May, J C; Progar, J J

    1989-01-01

    During a study of priming solutions for extracorporeal membrane oxygenation (ECMO) in the intensive care nursery, it was discovered that those solutions using certain brands of 25% albumin contained aluminum levels within the toxic range. When the brand was changed to a brand known to have a lower aluminum (Al) content, a marked drop in priming solution Al levels was measured. The heat exchanger was examined as a possible source of soluble Al. No evidence of elevated Al levels was found in fluids perfusing this heat exchanger when compared with a stainless steel heat exchanger. The Al content of various blood products was evaluated along with various brands of 5% albumin and 25% albumin. PMID:2597561

  16. Final Report on the Safety Assessment of Aluminum Silicate, Calcium Silicate, Magnesium Aluminum

    E-print Network

    Ahmad, Sajjad

    Final Report on the Safety Assessment of Aluminum Silicate, Calcium Silicate, Magnesium Aluminum Sodium Silicate, Montmorillonite, Pyrophyllite, and Zeolite1 This report reviews the safety of Aluminum, Calcium, Lithium Magnesium, Lithium Magnesium Sodium, Magnesium Aluminum, Magnesium, Sodium Magnesium

  17. Aluminum permanganate battery

    SciTech Connect

    Marsh, C.; Licht, S.L.

    1993-11-30

    A battery is provided comprising an aluminum anode, an aqueous solution of permanganate as the cathodic species and a second electrode capable of reducing permanganate. Such a battery system is characterized by its high energy density and low polarization losses when operating at high temperatures in a strong caustic electrolyte, i.e., high concentration of hydroxyl ions. A variety of anode and electrocatalyst materials are suitable for the efficient oxidation-reduction process and are elucidated.

  18. Choice of optimal properties of molding compounds for extrusion of block supports and catalysts with the honeycomb structure

    SciTech Connect

    Prokof`ev, V.Yu.; Il`in, A.P.; Shirokov, Yu.G.; Yurchenko, E.N. [Ivanovo State Chemical Engineering Academy, St. Petersburg (Russian Federation)

    1995-09-20

    Properties of compounds for molding of block supports and catalysts with the honeycomb structure have been studied. The examples studied include ultraporcelain, alumina, titanium dioxide, clays, and graphite. The molding properties of these compounds are characterized by such parameters as the relationship between deformations, relaxation time, power for destruction of the coagulation structure, and flow index. For molding of blocks with the honeycomb structure compounds with enhanced plastic properties and a stable coagulation structure are suggested.

  19. Oxidation products and pathway of ceramic honeycomb-catalyzed ozonation for the degradation of nitrobenzene in aqueous solution

    Microsoft Academic Search

    Lei Zhao; Jun Ma; Zhi-zhong Sun

    2008-01-01

    Semi-continuous experiments on catalytic ozonation of nitrobenzene (NB) in aqueous solution using ceramic honeycomb as catalyst have been investigated. Experimental results showed that the presence of ceramic honeycombs significantly increased the ozonation degradation rate of NB compared to the case of non-catalytic ozonation. With addition of the radical scavenger tert-butanol, the evident reduction of NB removal indicated that NB was

  20. Preliminary kinetic study on the degradation of nitrobenzene by modified ceramic honeycomb-catalytic ozonation in aqueous solution

    Microsoft Academic Search

    Lei Zhao; Jun Ma; Zhi-zhong Sun; Xue-dong Zhai

    2009-01-01

    The kinetics of degradation of nitrobenzene in aqueous solution was investigated in the processes of ozone alone, ozone\\/ceramic honeycomb (CH), ozone\\/modified ceramic honeycomb (MCH). The results indicated that all reactions followed the pseudo-first-order kinetic model, and the degradation rate of nitrobenzene was accelerated in the presence of CH or MCH catalyst, and the more pronounced degradation rate was achieved in

  1. Mechanism and kinetics of aluminum and iron leaching from coal fly ash by sulfuric acid

    Microsoft Academic Search

    A. Seidel; Y. Zimmels

    1998-01-01

    The mechanism and kinetics of leaching of aluminum and iron from Coal Fly Ash (CFA), by sulfuric acid, involves a rate controlling step of mass transfer. It is shown that, in the leaching process, particles follow the shrinking core model with respect to formation of unreacted core that is encapsulated by a leached, porous, layer. Formation of diffusion resistant calcium

  2. SCALE MODELING OF ALUMINUM MELTING FURNACE

    Microsoft Academic Search

    Sita rama raju S Penmetsa

    2004-01-01

    Secondary (recycled) aluminum constitutes around 48% of the total aluminum used in the United States. Secondary aluminum melting is accomplished in large reverberatory furnaces, and improving its energy efficiency has been one of the major interests to aluminum industries. To assist the industries in improving energy efficiency in aluminum melting, an experimental research furnace (ERF), with 907 kg (2000 lbs)

  3. High performing smart electrochromic device based on honeycomb nanostructured h-WO3 thin films: hydrothermal assisted synthesis.

    PubMed

    Kondalkar, Vijay V; Mali, Sawanta S; Kharade, Rohini R; Khot, Kishorkumar V; Patil, Pallavi B; Mane, Rahul M; Choudhury, Sipra; Patil, Pramod S; Hong, Chang K; Kim, Jin H; Bhosale, Popatrao N

    2015-02-14

    Herein, we report honeycomb nanostructured single crystalline hexagonal WO(3) (h-WO(3)) thin films in order to improve electrochromic performance. In the present investigation, honeycomb nanostructured WO(3) with different unit size and nanowire array with highly nanocrystalline frameworks have been synthesized via a hydrothermal technique. The influence of hydrothermal reaction time on the honeycomb unit cells, crystallite size, lithium ion diffusion coefficient and switching time for coloration/bleaching were studied systematically. The electrochromic study reveals that the honeycomb unit cell size has a significant impact on the electrochromic performance. Small unit cells in the honeycomb lead to large optical modulation and fast switching response. A large optical modulation in the visible spectral region (60.74% at ? = 630 nm) at a potential of -1.2 V with fast switching time (4.29 s for coloration and 3.38 s for bleaching) and high coloration efficiency (87.23 cm(2) C(-1)) is observed in the honeycomb WO(3) thin films with a unit cell diameter of 1.7 ?m. The variation in color on reduction of WO(3) with applied potential has been plotted on an xy-chromaticity diagram and the color space coordinate shows the transition from a colorless to deep blue state. PMID:25500946

  4. Aluminum Carbothermic Technology

    SciTech Connect

    Bruno, Marshall J.

    2005-03-31

    This report documents the non-proprietary research and development conducted on the Aluminum Carbothermic Technology (ACT) project from contract inception on July 01, 2000 to termination on December 31, 2004. The objectives of the program were to demonstrate the technical and economic feasibility of a new carbothermic process for producing commercial grade aluminum, designated as the ''Advanced Reactor Process'' (ARP). The scope of the program ranged from fundamental research through small scale laboratory experiments (65 kW power input) to larger scale test modules at up to 1600 kW power input. The tasks included work on four components of the process, Stages 1 and 2 of the reactor, vapor recovery and metal alloy decarbonization; development of computer models; and economic analyses of capital and operating costs. Justification for developing a new, carbothermic route to aluminum production is defined by the potential benefits in reduced energy, lower costs and more favorable environmental characteristics than the conventional Hall-Heroult process presently used by the industry. The estimated metrics for these advantages include energy rates at approximately 10 kWh/kg Al (versus over 13 kWh/kg Al for Hall-Heroult), capital costs as low as $1250 per MTY (versus 4,000 per MTY for Hall-Heroult), operating cost reductions of over 10%, and up to 37% reduction in CO2 emissions for fossil-fuel power plants. Realization of these benefits would be critical to sustaining the US aluminum industries position as a global leader in primary aluminum production. One very attractive incentive for ARP is its perceived ability to cost effectively produce metal over a range of smelter sizes, not feasible for Hall-Heroult plants which must be large, 240,000 TPY or more, to be economical. Lower capacity stand alone carbothermic smelters could be utilized to supply molten metal at fabrication facilities similar to the mini-mill concept employed by the steel industry. Major accomplishments for the program include definition of the system thermo-chemistry, demonstration of reactor stage 1, development of reactor stage 2 critical components in a 500 kW module, experimental determination of the vapor recovery reactor fundamentals, detailed design and installation of an advanced stage 1/vapor recovery reactor, feasibility of efficient separation of Al-C metal alloy product, updated capital and operating cost estimates, and development of computer models for all steps of the Advanced Reactor Process.

  5. Fabrication of robust honeycomb polymer films: a facile photochemical cross-linking process.

    PubMed

    Li, Lei; Chen, Caikang; Zhang, Aijuan; Liu, Xinyu; Cui, Kun; Huang, Jin; Ma, Zhi; Han, Zhaohui

    2009-03-15

    Highly ordered honeycomb films are prepared by breath-figure method using an amphiphilic diblock copolymer of polystyrene-block-polyacrylic acid (PS-b-PAA). By simply cross-linking PS matrix via deep ultraviolet (UV) irradiation, both the solvent and thermal stability of the porous films was significantly improved while retaining the three-dimensional (3D) structures. The film surface wettability was changed from hydrophobicity to hydrophilicity by the formed polar groups during the photochemical process. After 6 h UV cross-linking, the honeycomb structures could be preserved up to 320 degrees C, an increase of more than 200 K as compared to the non-cross-linked films. PMID:19100561

  6. Friction-factor data for flat-plate tests of smooth and honeycomb surfaces

    NASA Technical Reports Server (NTRS)

    Ha, T. W.; Childs, Dara W.

    1992-01-01

    Friction factors for honeycomb surfaces were measured with a flat plate tester. The flat plate test apparatus was described and a method was discussed for determining the friction factor experimentally. The friction factor model was developed for the flat plate test based on the Fanno Line Flow. The comparisons of the friction factor were plotted for smooth surfaces and six-honeycomb surfaces with three-clearances, 6.9 bar to 17.9 bar range of inlet pressures, and 5,000 to 100,000 range of the Reynolds number. The optimum geometries for the maximum friction factor were found as a function of cell width to cell depth and cell width to clearance ratios.

  7. Affleck-Kennedy-Lieb-Tasaki State on a Honeycomb Lattice from t2 g Orbitals

    NASA Astrophysics Data System (ADS)

    Koch-Janusz, Maciej; Khomskii, D. I.; Sela, Eran

    2015-06-01

    The two-dimensional Affeck-Kennedy-Lieb-Tasaki (AKLT) model on a honeycomb lattice has been shown to be a universal resource for quantum computation. In this valence bond solid, however, the spin interactions involve higher powers of the Heisenberg coupling (S?i.S?j)n, making these states seemingly unrealistic on bipartite lattices, where one expects a simple antiferromagnetic order. We show that those interactions can be generated by orbital physics in multiorbital Mott insulators. We focus on t2 g electrons on the honeycomb lattice and propose a physical realization of the spin-3 /2 AKLT state. We find a phase transition from the AKLT to the Néel state on increasing Hund's rule coupling, which is confirmed by density matrix renormalization group simulations. An experimental signature of the AKLT state consists of protected, free S =1 /2 spins on lattice vacancies, which may be detected in the spin susceptibility.

  8. Long-range orientation and atomic attachment of nanocrystals in 2D honeycomb superlattices.

    PubMed

    Boneschanscher, M P; Evers, W H; Geuchies, J J; Altantzis, T; Goris, B; Rabouw, F T; van Rossum, S A P; van der Zant, H S J; Siebbeles, L D A; Van Tendeloo, G; Swart, I; Hilhorst, J; Petukhov, A V; Bals, S; Vanmaekelbergh, D

    2014-06-20

    Oriented attachment of synthetic semiconductor nanocrystals is emerging as a route for obtaining new semiconductors that can have Dirac-type electronic bands such as graphene, but also strong spin-orbit coupling. The two-dimensional (2D) assembly geometry will require both atomic coherence and long-range periodicity of the superlattices. We show how the interfacial self-assembly and oriented attachment of nanocrystals results in 2D metal chalcogenide semiconductors with a honeycomb superlattice. We present an extensive atomic and nanoscale characterization of these systems using direct imaging and wave scattering methods. The honeycomb superlattices are atomically coherent and have an octahedral symmetry that is buckled; the nanocrystals occupy two parallel planes. Considerable necking and large-scale atomic motion occurred during the attachment process. PMID:24948734

  9. Recycling of aluminum salt cake

    Microsoft Academic Search

    B. J. Jody; E. J. Daniels; P. V. Bonsignore; D. E. Karvelas

    1991-01-01

    The secondary aluminum industry generates more than 110 à 10³ tons of salt-cake waste every year. This waste stream contains about 3--5% aluminum, 15--30% aluminum oxide, 30--40% sodium chloride, and 20--30% potassium chloride. As much as 50% of the content of this waste is combined salt (sodium and potassium chlorides). Salt-cake waste is currently disposed of in conventional landfills. In

  10. Molecular aspects of aluminum toxicity

    Microsoft Academic Search

    Alfred Haug; Charles E. Foy

    1984-01-01

    The focus in this review is directed to molecular aspects of aluminum toxicity in animal and plant cells. Unique thermodynamic features of Al(lII) ions impart biological specificity which may form the biochemical basis of aluminum interactions with cellular constituents. Current knowledge about aluminum?specific, molecular interactions is rather scanty. Al(III) ions may coordinate with nucleotides or complex to phospholipids resulting in

  11. Quasicrystalline particulate reinforced aluminum composite

    SciTech Connect

    Anderson, I.E.; Biner, S.B.; Sordelet, D.J.; Unal, O.

    1997-07-01

    Particulate reinforced aluminum and aluminum alloy composites are rapidly emerging as new commercial materials for aerospace, automotive, electronic packaging and other high performance applications. However, their low processing ductility and difficulty in recyclability have been the key concern. In this study, two composite systems having the same aluminum alloy matrix, one reinforced with quasicrystals and the other reinforced with the conventional SiC reinforcements were produced with identical processing routes. Their processing characteristics and tensile mechanical properties were compared.

  12. A ballistic limit equation for hypervelocity impacts on composite honeycomb sandwich panel satellite structures

    Microsoft Academic Search

    S. Ryan; F. Schaefer; R. Destefanis; M. Lambert

    2008-01-01

    During a recent experimental test campaign performed in the framework of ESA Contract 16721, the ballistic performance of multiple satellite-representative Carbon Fibre Reinforced Plastic (CFRP)\\/Aluminium honeycomb sandwich panel structural configurations (GOCE, Radarsat-2, Herschel\\/Planck, BeppoSax) was investigated using the two-stage light-gas guns at EMI. The experimental results were used to develop and validate a new empirical Ballistic Limit Equation (BLE), which

  13. Post-buckling analysis of elastic honeycombs subject to in-plane biaxial compression

    Microsoft Academic Search

    D. Okumura; N. Ohno; H. Noguchi

    2002-01-01

    In this paper, employing the homogenization theory and the microscopic bifurcation condition established by the authors, we discuss which microscopic buckling mode grows in elastic honeycombs subject to in-plane biaxial compression. First, we focus on equi-biaxial compression, under which uniaxial, biaxial and flower-like modes may develop as a result of triple bifurcation. By forcing each of the three modes to

  14. Affleck-Kennedy-Lieb-Tasaki State on a Honeycomb Lattice is a Universal Quantum Computational Resource

    E-print Network

    Tzu-Chieh Wei; Ian Affleck; Robert Raussendorf

    2011-02-24

    Universal quantum computation can be achieved by simply performing single-qubit measurements on a highly entangled resource state, such as cluster states. The family of Affleck-Kennedy-Lieb-Tasaki states has recently been intensively explored and shown to provide restricted computation. Here, we show that the two-dimensional Affleck-Kennedy-Lieb-Tasaki state on a honeycomb lattice is a universal resource for measurement-based quantum computation.

  15. Cobalt (II) chloride promoted formation of honeycomb patterned cellulose acetate films

    Microsoft Academic Search

    Olga Naboka; Anke Sanz-Velasco; Per Lundgren; Peter Enoksson; Paul Gatenholm

    CoCl2 containing honeycomb patterned films were prepared from cellulose acetate (CA)\\/CoCl2\\/acetone solutions by the breath figure method in a wide range of humidities. Size and pore regularity depend on the CA\\/CoCl2 molar ratio and humidity. When replacing CoCl2 with Co(NO3)2 or CoBr2, no formation of ordered porosity in the cellulose acetate films is observed. According to data from scanning electron

  16. Superelasticity and stability of a shape memory alloy hexagonal honeycomb under in-plane compression

    Microsoft Academic Search

    P. A. Michailidis; N. Triantafyllidis; J. A. Shaw; D. S. Grummon

    2009-01-01

    Nitinol (NiTi) shape memory alloy honeycombs, fabricated in low densities using a new brazing method [Grummon, D., Shaw, J., Foltz, J., 2006. Fabrication of cellular shape memory alloy materials by reactive eutectic brazing using niobium. Materials Science and Engineering A 438–440, 1113–1118], recently demonstrated enhanced shape memory and superelastic properties [Shaw, J. A., Grummon, D. S., Foltz, J., 2007b. Superelastic

  17. Refined genetic and physical positioning of the gene for Doyne honeycomb retinal dystrophy (DHRD)

    Microsoft Academic Search

    Sana Kermani; Kevin Gregory-Evans; E. E. Tarttelin; James Bellingham; Catherine Plant; Alan C. Bird; Margaret Fox; Shomi S. Bhattacharya; C. Y. Gregory-Evans

    1999-01-01

    Doyne honeycomb retinal dystrophy (DHRD) is a late-onset autosomal dominant disorder that causes degeneration of the retina\\u000a and can lead to blindness. We have previously assigned DHRD to a 5-cM region of chromosome 2p16 between marker loci D2S2739 and D2S378. Using sequence-tagged sites (STSs), expressed sequence tags (ESTs) and polymorphic markers within the DHRD region, we have identified 18 yeast

  18. A single EFEMP1 mutation associated with both Malattia Leventinese and Doyne honeycomb retinal dystrophy

    Microsoft Academic Search

    Andrew J. Lotery; Elise Héon; Bertrand Piguet; Robyn H. Guymer; Kimberlie Vandenburgh; Pascal Cousin; Darryl Nishimura; Ruth E. Swiderski; Giuliana Silvestri; David A. Mackey; Gregory S. Hageman; Alan C. Bird; Daniel F. Schorderet; Edwin M. Stone; Francis L. Munier; Val C. Sheffield

    1999-01-01

    Malattia Leventinese (ML) and Doyne honeycomb retinal dystrophy (DHRD) refer to two autosomal dominant diseases characterized by yellow-white deposits known as drusen that accumulate beneath the retinal pigment epithelium (RPE). Both loci were mapped to chromosome 2p16-21 (Refs 5,6) and this genetic interval has been subsequently narrowed. The importance of these diseases is due in large part to their close

  19. ROTOR BEARING LOADS WITH HONEYCOMB SEALS ANDVOLUTE FORCES IN REINJECTION COMPRESSORS

    Microsoft Academic Search

    Leonardo Baldassarre; John W. Fulton

    The calculation for unbalance response of a rotor starts by calculating the bearing load to provide the basis for the bearing stiffness and damping characteristics. Measurements in test rigs at a major Texas university laboratory have shown that honeycomb-stator\\/drum-rotor annular seals can produce negative stiffness, in particular at zero to low whirl frequencies, which tends to pull the rotor off-center.

  20. Laser welding of aluminum alloys

    SciTech Connect

    Leong, K.H.; Sabo, K.R.; Sanders, P.G. [Argonne National Lab., IL (United States). Technology Development Div.; Spawr, W.J.

    1997-03-01

    Recent interest in reducing the weight of automobiles to increase fuel mileage has focused attention on the use of aluminum and associated joining technologies. Laser beam welding is one of the more promising methods for high speed welding of aluminum. Consequently, substantial effort has been expended in attempting to develop a robust laser beam welding process. Early results have not been very consistent in the process requirements but more definitive data has been produced recently. This paper reviews the process parameters needed to obtain consistent laser welds on 5,000 series aluminum alloys and discusses the research necessary to make laser processing of aluminum a reality for automotive applications.

  1. Aluminum-lithium for aerospace

    SciTech Connect

    Fielding, P.S.; Wolf, G.J. [Reynolds Metals Co., Richmond, VA (United States)

    1996-10-01

    Aluminum-lithium alloys were developed primarily to reduce the weight of aircraft and aerospace structures. Lithium is the lightest metallic element, and each 1% of lithium added to aluminum reduces alloy density by about 3% and increases modulus by about 5%. Though lithium has a solubility limit of 4.2% in aluminum, the amount of lithium ranges between 1 and 3% in commercial alloys. Aluminum-lithium alloys are most often selected for aerospace components because of their low density, high strength, and high specific modulus. However, other applications now exploit their excellent fatigue resistance and cryogenic toughness.

  2. Theory of Magnetic Phases in Hyperhoneycomb and Harmonic-honeycomb Iridates

    NASA Astrophysics Data System (ADS)

    Lee, Eric Kin Ho; Kim, Yong Baek

    2015-03-01

    Motivated by recent experiments, we consider a generic spin model in the jeff = 1 / 2 basis for the hyperhoneycomb and harmonic-honeycomb iridates. Based on microscopic considerations, the effect of an additional bond-dependent anisotropic spin exchange interaction (?) beyond the Heisenberg-Kitaev model is investigated. We obtain the magnetic phase diagrams of the hyperhoneycomb and harmonic-honeycomb (H-1) lattices via a combination of the Luttinger-Tisza approximation, single-Q variational ansatz, and classical Monte Carlo simulated annealing. The resulting phase diagrams on both systems show the existence of incommensurate, non-coplanar spiral magnetic orders as well as other commensurate magnetic orders. The spiral orders show counter-propagating spiral patterns, which may be favorably compared to recent experimental results on both iridates. The parameter regime of various magnetic orders and ordering wavevectors are quite similar in both systems. We discuss the implications of our work to recent experiments and also compare our results to those of the two dimensional honeycomb iridate systems. Computations were performed on the GPC supercomputer at the SciNet HPC Consortium. This research was supported by the NSERC, CIFAR, and Centre for Quantum Materials at the University of Toronto.

  3. Magnetic Correlations in a Frustrated Ni3+ - Based Spin 1/2 Honeycomb Lattice

    NASA Astrophysics Data System (ADS)

    Ross, Kate; Roudebush, John; Pajerowski, Daniel; Brown, Craig; Rodriguez, Jose; Broholm, Collin; Cava, Robert

    2014-03-01

    We have studied the magnetic properties, via thermodynamic probes and inelastic neutron scattering, of the new spin-1/2 honeycomb material Na0.95Ni2SbO6 . 1.5D2O. This hydrated compound hosts well separated honeycomb layers of nickel ions in the unusual Ni3+ oxidation state, which produces S=1/2 magnetic moments. While a Curie-Weiss temperature of -13K indicates overall anti-ferromagnetic interactions, specific heat and neutron scattering reveal the presence of ferromagnetic correlations with coherent spin excitations that build up gradually upon cooling below 10K. No transition to long range order is observed down to 2 K, as evidenced by specific heat and neutron scattering, although AC susceptibility measurements indicate a dramatic change in dynamics near 4.2K. The results indicate the presence of frustration arising from competing interactions between ions in the layers. This compound, along with potential isostructural analogs, opens a new route to study the phase diagram of spin 1/2 honeycomb lattice models with competing interactions.

  4. External scaffold of spherical immature poxvirus particles is made of protein trimers, forming a honeycomb lattice.

    PubMed

    Szajner, Patricia; Weisberg, Andrea S; Lebowitz, Jacob; Heuser, John; Moss, Bernard

    2005-09-12

    During morphogenesis, poxviruses undergo a remarkable transition from spherical immature forms to brick-shaped infectious particles lacking helical or icosahedral symmetry. In this study, we show that the transitory honeycomb lattice coating the lipoprotein membrane of immature vaccinia virus particles is formed from trimers of a 62-kD protein encoded by the viral D13L gene. Deep-etch electron microscopy demonstrated that anti-D13 antibodies bound to the external protein coat and that lattice fragments were in affinity-purified D13 preparations. Soluble D13 appeared mostly trimeric by gel electrophoresis and ultracentrifugation, which is consistent with structural requirements for a honeycomb. In the presence or absence of other virion proteins, a mutated D13 with one amino acid substitution formed stacks of membrane-unassociated flat sheets that closely resembled the curved honeycombs of immature virions except for the absence of pentagonal facets. A homologous domain that is present in D13 and capsid proteins of certain other lipid-containing viruses support the idea that the developmental stages of poxviruses reflect their evolution from an icosahedral ancestor. PMID:16144903

  5. Metal Foam Shields

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L.

    2006-01-01

    This paper compares the ballistic performance of metallic foam sandwich structures with honeycomb structures. Honeycomb sandwich structures, consisting of metallic or composite facesheets and honeycomb cores, are often used in spacecraft construction due to their light-weight and structural stiffness. Honeycomb panels, however, are considered rather poor candidates for protection from micrometeoroid orbital debris (MMOD) particles because the honeycomb channels the debris cloud from MMOD impacts on outer facesheet causing a concentrated load on the second facesheet. Sandwich structures with light-weight, open-cell metallic cores and metal or composite facesheets provide improved MMOD protection because channeling does not occur and because the core is more effective at disrupting hypervelocity impacts then honeycomb. This paper describes hypervelocity impact tests on metallic foam sandwich structures (aluminum and titanium) with metallic facesheets, compare them to equivalent mass and thickness honeycomb panels, based on the results of hypervelocity impact tests.

  6. Modeling Texture Evolution during Recrystallization in Aluminum

    E-print Network

    Rollett, Anthony D.

    Modeling Texture Evolution during Recrystallization in Aluminum Abhijit Brahme1,2 , Joseph Fridy3, Aluminum, Grain Boundary Mobility, Nucleation, Oriented Growth, Oriented Nucleation, Stored Energy, Monte Carlo Modeling. #12;Modeling Texture Evolution during Recrystallization in Aluminum 2 1. Introduction

  7. 75 FR 80527 - Aluminum Extrusions From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-22

    ...Final) and 731-TA-1177 (Final)] Aluminum Extrusions From China AGENCY: United...less-than-fair-value imports from China of aluminum extrusions, primarily provided for in...these investigations is contained in Aluminum Extrusions From the People's...

  8. Mechanics of pressure-adaptive honeycomb and its application to wing morphing

    NASA Astrophysics Data System (ADS)

    Vos, Roelof; Barrett, Ron

    2011-09-01

    Current, highly active classes of adaptive materials have been considered for use in many different aerospace applications. From adaptive flight control surfaces to wing surfaces, shape-memory alloy (SMA), piezoelectric and electrorheological fluids are making their way into wings, stabilizers and rotor blades. Despite the benefits which can be seen in many classes of aircraft, some profound challenges are ever present, including low power and energy density, high power consumption, high development and installation costs and outright programmatic blockages due to a lack of a materials certification database on FAR 23/25 and 27/29 certified aircraft. Three years ago, a class of adaptive structure was developed to skirt these daunting challenges. This pressure-adaptive honeycomb (PAH) is capable of extremely high performance and is FAA/EASA certifiable because it employs well characterized materials arranged in ways that lend a high level of adaptivity to the structure. This study is centered on laying out the mechanics, analytical models and experimental test data describing this new form of adaptive material. A directionally biased PAH system using an external (spring) force acting on the PAH bending structure was examined. The paper discusses the mechanics of pressure adaptive honeycomb and describes a simple reduced order model that can be used to simplify the geometric model in a finite element environment. The model assumes that a variable stiffness honeycomb results in an overall deformation of the honeycomb. Strains in excess of 50% can be generated through this mechanism without encountering local material (yield) limits. It was also shown that the energy density of pressure-adaptive honeycomb is akin to that of shape-memory alloy, while exhibiting strains that are an order of magnitude greater with an energy efficiency close to 100%. Excellent correlation between theory and experiment is demonstrated in a number of tests. A proof-of-concept wing section test was conducted on a 12% thick wing section representative of a modern commercial aircraft winglet or flight control surface with a 35% PAH trailing edge. It was shown that camber variations in excess of 5% can be generated by a pressure differential of 40 kPa. Results of subsequent wind tunnel test show an increase in lift coefficient of 0.3 at 23 m s - 1 through an angle of attack from - 6° to + 20°. This paper was originally presented at the 2010 ASME SMASIS conference, as paper 'SMASIS 2010-3634'. Despite the substantial changes that have been made to the paper, there are still various figures and text stemming from the original.

  9. Characterization of ultradispersed aluminum

    SciTech Connect

    Simpson, R.L.; Maienschein, J.L.; Swansiger, R.W.; Garcia, F.; Darling, D.H.

    1994-12-08

    Samples of ultradispersed Al were received, which were produced by electrically exploding Al wires in argon. These samples comprised very small particles that were not significantly oxidized and that were stable in air. Particle morphology were studied with SE, micropycnometry, and gas adsorption surface area. Composition were determined using various techniques, as were thermal stability and reaction exotherms. The inexplicable reports of an Al-Ar compound and of an exothermic reaction were not confirmed. The material is a stable, nonoxidized, small-particle, highly reactive form of aluminum that is of interest in energetic materials formulations.

  10. Topological insulator in the core of the superconducting vortex in graphene

    E-print Network

    Igor F. Herbut

    2010-02-10

    The core of the vortex in a general superconducting order parameter in graphene is argued to be ordered, with the possible order parameters forming the algebra U(1) X Cl(3), where Cl(3) is the three dimensional Clifford algebra. A sufficiently strong Zeeman coupling of the magnetic field of the vortex to the electron spin breaks the degeneracy in the core in favor of the anomalous quantum Hall state. I consider a variety of superconducting condensates on the honeycomb lattice and demonstrate the surprising universality of this result. A way to experimentally determine the outcome of the possible competition between different types of orders in the core is proposed.

  11. The thermomechanical stability of micro-solid oxide fuel cells fabricated on anodized aluminum oxide membranes

    NASA Astrophysics Data System (ADS)

    Kwon, Chang-Woo; Lee, Jae-Il; Kim, Ki-Bum; Lee, Hae-Weon; Lee, Jong-Ho; Son, Ji-Won

    2012-07-01

    The thermomechanical stability of micro-solid oxide fuel cells (micro-SOFCs) fabricated on an anodized aluminum oxide (AAO) membrane template is investigated. The full structure consists of the following layers: AAO membrane (600 nm)/Pt anode/YSZ electrolyte (900 nm)/porous Pt cathode. The utilization of a 600-nm-thick AAO membrane significantly improves the thermomechanical stability due to its well-known honeycomb-shaped nanopore structure. Moreover, the Pt anode layer deposited in between the AAO membrane and the YSZ electrolyte preserves its integrity in terms of maintaining the triple-phase boundary (TPB) and electrical conductivity during high-temperature operation. Both of these results guarantee thermomechanical stability of the micro-SOFC and extend the cell lifetime, which is one of the most critical issues in the fabrication of freestanding membrane-type micro-SOFCs.

  12. Aluminum Nanoholes for Optical Biosensing.

    PubMed

    Barrios, Carlos Angulo; Canalejas-Tejero, Víctor; Herranz, Sonia; Urraca, Javier; Moreno-Bondi, María Cruz; Avella-Oliver, Miquel; Maquieira, Ángel; Puchades, Rosa

    2015-09-01

    Sub-wavelength diameter holes in thin metal layers can exhibit remarkable optical features that make them highly suitable for (bio)sensing applications. Either as efficient light scattering centers for surface plasmon excitation or metal-clad optical waveguides, they are able to form strongly localized optical fields that can effectively interact with biomolecules and/or nanoparticles on the nanoscale. As the metal of choice, aluminum exhibits good optical and electrical properties, is easy to manufacture and process and, unlike gold and silver, its low cost makes it very promising for commercial applications. However, aluminum has been scarcely used for biosensing purposes due to corrosion and pitting issues. In this short review, we show our recent achievements on aluminum nanohole platforms for (bio)sensing. These include a method to circumvent aluminum degradation-which has been successfully applied to the demonstration of aluminum nanohole array (NHA) immunosensors based on both, glass and polycarbonate compact discs supports-the use of aluminum nanoholes operating as optical waveguides for synthesizing submicron-sized molecularly imprinted polymers by local photopolymerization, and a technique for fabricating transferable aluminum NHAs onto flexible pressure-sensitive adhesive tapes, which could facilitate the development of a wearable technology based on aluminum NHAs. PMID:26184330

  13. Lost-Soap Aluminum Casting.

    ERIC Educational Resources Information Center

    Mihalow, Paula

    1980-01-01

    Lost-wax casting in sterling silver is a costly experience for the average high school student. However, this jewelry process can be learned at no cost if scrap aluminum is used instead of silver, and soap bars are used instead of wax. This lost-soap aluminum casting process is described. (Author/KC)

  14. The Benefits of Aluminum Windows.

    ERIC Educational Resources Information Center

    Goyal, R. C.

    2002-01-01

    Discusses benefits of aluminum windows for college construction and renovation projects, including that aluminum is the most successfully recycled material, that it meets architectural glass deflection standards, that it has positive thermal energy performance, and that it is a preferred exterior surface. (EV)

  15. Primary Aluminum Plants Worldwide - 1998

    USGS Publications Warehouse

    1999-01-01

    The 1990 U.S. Bureau of Mines publication, Primary Aluminum Plants Worldwide, has been updated and is now available. The 1998 USGS edition of Primary Aluminum Plants Worldwide is published in two parts. Part I—Detail contains information on individual primary smelter capacity, location, ownership, sources of energy, and other miscellaneous information. Part II—Summary summarizes the capacity data by country

  16. Deformation Twinning in Nanocrystalline Aluminum

    Microsoft Academic Search

    Mingwei Chen; En Ma; Kevin J. Hemker; Hongwei Sheng; Yinmin Wang; Xuemei Cheng

    2003-01-01

    We report transmission electron microscope observations that provide evidence of deformation twinning in plastically deformed nanocrystalline aluminum. The presence of these twins is directly related to the nanocrystalline structure, because they are not observed in coarse-grained pure aluminum. We propose a dislocation-based model to explain the preference for deformation twins and stacking faults in nanocrystalline materials. These results underscore a

  17. Aluminum vehicle breaks new ground

    SciTech Connect

    Ashley, S.

    1994-02-01

    This article examines the efforts of automobile manufacturers and aluminum producers to develop a light weight crash resistant automobile. The topics of the article include alloys used, production techniques, fastening and bonding techniques, rigidity and crush resistance, weight reduction, die-casting and extruding of aluminum, design and construction of space frame.

  18. NASA-UVA Light Aerospace Alloy and Structure Technology Program Supplement: Aluminum-Based Materials for High Speed Aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr.

    1997-01-01

    This is the final report of the study "Aluminum-Based Materials for High Speed Aircraft" which had the objectives (1) to identify the most promising aluminum-based materials with respect to major structural use on the HSCT and to further develop those materials and (2) to assess the materials through detailed trade and evaluation studies with respect to their structural efficiency on the HSCT. The research team consisted of ALCOA, Allied-Signal, Boeing, McDonnell Douglas, Reynolds Metals and the University of Virginia. Four classes of aluminum alloys were investigated: (1) I/M 2XXX containing Li and I/M 2XXX without Li, (2) I/M 6XXX, (3) two P/M 2XXX alloys, and (4) two different aluminum-based metal matrix composites (MMC). The I/M alloys were targeted for a Mach 2.0 aircraft and the P/M and MMC alloys were targeted for a Mach 2.4 aircraft. Design studies were conducted using several different concepts including skin/stiffener (baseline), honeycomb sandwich, integrally stiffened and hybrid adaptations (conventionally stiffened thin-sandwich skins). Alloy development included fundamental studies of coarsening behavior, the effect of stress on nucleation and growth of precipitates, and fracture toughness as a function of temperature were an integral part of this program. The details of all phases of the research are described in this final report.

  19. Aluminum Zintl anion moieties within sodium aluminum clusters

    SciTech Connect

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Grubisic, Andrej; Li, Xiang; Ganteför, Gerd; Bowen, Kit H., E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Schnöckel, Hansgeorg [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany)] [Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe (Germany); Eichhorn, Bryan W. [Department of Chemistry, University of Maryland at College Park, College Park, Maryland 20742 (United States)] [Department of Chemistry, University of Maryland at College Park, College Park, Maryland 20742 (United States); Lee, Mal-Soon; Jena, P. [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)] [Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Kandalam, Anil K., E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Physics, West Chester University of Pennsylvania, West Chester, Pennsylvania 19383 (United States); Kiran, Boggavarapu, E-mail: AKandalam@wcupa.edu, E-mail: kiran@mcneese.edu, E-mail: kbowen@jhu.edu [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States)] [Department of Chemistry, McNeese State University, Lake Charles, Louisiana 70609 (United States)

    2014-02-07

    Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have established that aluminum moieties within selected sodium-aluminum clusters are Zintl anions. Sodium–aluminum cluster anions, Na{sub m}Al{sub n}{sup ?}, were generated in a pulsed arc discharge source. After mass selection, their photoelectron spectra were measured by a magnetic bottle, electron energy analyzer. Calculations on a select sub-set of stoichiometries provided geometric structures and full charge analyses for both cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra), and fragment molecular orbital based correlation diagrams.

  20. EUROSPF Conference APPLICATION TECHNOLOGY OF ALUMINUM BLOW

    E-print Network

    Paris-Sud XI, Université de

    6th EUROSPF Conference APPLICATION TECHNOLOGY OF ALUMINUM BLOW FORMING FOR AUTOMOTIVE CLOSURE PANEL Replacement by aluminum for the closure panels is one of the common methods for lightening car body. However. As a solution to cover the low stamping formability of aluminum, Blow forming technology of aluminum which

  1. Subsurface Aluminum Nitride Formation in Iron-Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bott, June H.

    Transformation-induced plasticity (TRIP) steels containing higher amounts of aluminum than conventional steels are ideal for structural automotive parts due to their mechanical properties. However, the aluminum tends to react with any processing environment at high temperatures and therefore presents significant challenges during manufacturing. One such challenge occurs during secondary cooling, reheating, and hot-rolling and is caused by a reaction with nitrogen-rich atmospheres wherein subsurface aluminum nitride forms in addition to internal and external oxides. The nitrides are detrimental to mechanical properties and cause surface cracks. It is important to understand how these nitrides and oxides form and their consequences for the quality of steel products. This study looks at model iron-aluminum (up to 8 wt.% aluminum) alloys and uses confocal laser scanning microscopy, x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectrometry, and transmission electron microscopy to study the effect of various conditions on the growth and development of these precipitates in a subsurface oxygen-depleted region. By using model alloys and controlling the experimental atmosphere, this study is able to understand some of the more fundamental materials science behind aluminum nitride formation in aluminum-rich iron alloys and the relationship between internal nitride and oxide precipitation and external oxide scale morphology and composition. The iron-aluminum alloys were heated in N2 atmospheres containing oxygen impurities. It was found that nitrides formed when bulk aluminum content was below 8 wt.% when oxygen was sufficiently depleted due to the internal oxidation. In the samples containing 1 wt.% aluminum, the depth of the internal oxide and nitride zones were in agreement with a diffusion-based model. Increasing aluminum content to 3 and 5 wt% had the effects of modifying the surface-oxide scale composition and increasing its continuity, which gradually decreased the internal precipitation zones with increasing aluminum content. In samples containing 8 wt.% aluminum, a thick continuous oxide scale formed and prevented nitrogen and oxygen penetration into the bulk of the sample, thus preventing the formation of any internal precipitates. The effect of modifying the heating rate in pure N2 atmospheres was examined. Samples were heated over the course of 1, 10, or 100 minutes. Faster heating rates increased the aluminum content in the oxide scale on all samples. Additionally, these rapid heating rate samples had either had lower internal precipitation depths or no internal precipitates. Experiments were conducted in N2--2.5% H2/H 2O mixtures with varying dew points to lower the oxygen potential of the reaction gas and prevent the formation of external iron oxide scales. In the 3 and 5 wt.% Al alloys, this produced an internal aluminum-rich oxide band which inhibited further internal precipitation. Samples treated in atmospheres to simulate the reheat furnace combustion atmosphere experienced dramatically increased external oxidation in addition to inward growth of the oxide scale and internal precipitation of oxides and nitrides within the metal. The most important scientific findings of this dissertation are the dramatic effect of heating rate on modifying the external scale of the alloys presented and the presence of continuous internal oxide bands in several samples throughout the study. Oxidation studies typically occur for longer times and in higher oxygen contents than the present results, so the influence of heating rate is either largely unnoticed or is overcome by oxide growth at long times. Oxide bands have been observed in literature, but few aluminum oxide bands have been seen before this study. vi.

  2. Solidification behavior of undercooled liquid aluminum oxide

    SciTech Connect

    Weber, J.K.R.; Anderson, C.D.; Merkley, D.R.; Nordine, P.C. [Intersonics, Inc., Northbrook, IL (United States)

    1995-03-01

    Solidification of aluminum oxide from undercooled melts was investigated in containerless experiments. Specimens were levitated in a gas jet, stabilized with an acoustic positioning device, and melted with cw CO{sub 2} laser beams. Cooling curves were obtained by optical pyrometry when the laser intensity was reduced. The materials examined were high-purity Verneuil sapphire, 99.5% polycrystalline alumina, and oxide materials recovered from the effluent of an aluminum-fueled rocket motor. The degree of undercooling, the apparent temperature behavior during the thermal arrest on solidification, and the structure of the materials formed were different in argon and oxygen atmospheres. Undercooling of the sapphire and alumina materials was 360 {+-} 10 K in an oxygen atmosphere and approximately 450 K in argon. Melting and solidification of high-purity sapphire resulted in a dendritic and porous polycrystalline material in oxygen. Dense, larger crystals were obtained in argon. Products formed from 99.5% alumina were discolored and the cores were white, indicating impurity segregation effects. More reproducible behavior was observed for the sapphire and 99.5% alumina than for the tungsten-contaminated rocket motor effluent materials.

  3. Assembly of acid and sintering resistant honeycomb washcoat and catalytically active phase using sols of silica, zirconia, and platinum

    SciTech Connect

    Felthouse, T.R. [Monsanto Enviro-Chem Systems, Inc., St.Louis, MO (United States); [Huntsman Specialty Chemicals Corp., St. Louis, MO (United States); Berkel, D.A.; Jost, S.R. [Monsanto Enviro-Chem Systems, Inc., St. Louis, MO (United States)] [and others

    1995-12-01

    Development of high performance honeycomb catalysts containing platinum active phase for gas phase air oxidation of sulfur dioxide is described. Stepwise assembly of these washcoated honeycombs consists of: (1) selection of honeycomb composition (mullite substrate) and cell density based on pressure drop requirements; (2) identification of washcoat slurry composition (silica-precursor sol, silica powder, and surfactants if needed); (3) processing of the washcoat-substrate by dip coating, drying, and calcining; (4) loading of the platinum active phase through a facilitated adsorption technique followed by drying and activation steps; and (5) reactor loading and evaluation. Details of these steps will be presented that include thermal and chemical stability tests. Characterization by transmission electron microscopy of the final Pt/(ZrO{sub 2}-SiO{sub 2}) composite attached to the mullite substrate will be reported.

  4. A comparison of experimental and theoretical results for labyrinth gas seals with honeycomb stators. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Hawkins, Lawrence Allen

    1988-01-01

    Experimental results for the rotordynamic stiffness and damping coefficients of a labyrinth -rotor honeycomb-stator seal are presented. The coefficients are compared to the coefficients of a labyrinth-rotor smooth-stator seal having the same geometry. The coefficients are compared to analytical results from a two-control-volume compressible flow model. The experimental results show that the honeycomb stator configuration is more stable than the smooth stator configuration at low rotor speeds. At high rotor speeds and low clearance, the smooth stator seal is more stable. The theoretical model predicts the cross-coupled stiffness of the honeycomb stator seal correctly within 25 percent of measured values. The model provides accurate predictions of direct damping for large clearance seals. Overall, the model does not perform as well for low clearance seals as for high clearance seals.

  5. Ferrimagnetism and single-particle excitations in a periodic Anderson model on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Seki, Kazuhiro; Shirakawa, Tomonori; Zhang, Qinfang; Li, Tao; Yunoki, Seiji

    2015-04-01

    By using the variationalcluster approximation and cluster perturbation theory, we investigate the magnetism and single-particle excitations of a periodic Anderson model on the honeycomb lattice as an effective model for the single-side hydrogenated graphene, namely, graphone. We calculate the magnetic moment as a function of U (Coulomb interaction on impurity sites) with showing that the ground state is ferrimagneticfor any U > 0. We then calculate the single-particle excitations and show that the single-particle excitations are gapless and exhibit quadratic dispersion relation near the Fermi energy.

  6. Composite multi-vortex diffraction-free beams and van-Hove singularities in honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Paltoglou, Vassilis; Chen, Zhigang; Efremidis, Nikolaos K.

    2015-03-01

    We find diffraction-free beams for graphene and MoS$_2$-type honeycomb optical lattices. The resulting composite solutions have the form of multi-vortices, with spinor topological charges ($n$, $n\\pm1$). Exact solutions for the spinor components are obtained in the Dirac limit. The effects of the valley degree of freedom and the mass are analyzed. Passing through the van-Hove singularity the topological structure of the solutions is modified. Exactly at the singularity the diffraction-free beams take the form of strongly localized one-dimensional stripes.

  7. Temperature-Induced Spontaneous Time-Reversal Symmetry Breaking on the Honeycomb Lattice

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Punnoose, Alexander

    2015-05-01

    Phase transitions involving spontaneous time-reversal symmetry breaking are studied on the honeycomb lattice at finite hole doping with next-nearest-neighbor repulsion. We derive an exact expression for the mean-field equation of state in closed form, valid at temperatures much less than the Fermi energy. Contrary to standard expectations, we find that thermally induced intraband particle-hole excitations can create and stabilize a uniform metallic phase with broken time-reversal symmetry as the temperature is raised in a region where the ground state is a trivial metal.

  8. Quantum spin Hall effect in a two-orbital model on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Hayami, Satoru; Kusunose, Hiroaki; Motome, Yukitoshi

    2015-03-01

    The spin Hall effect is investigated in a two-orbital tight-binding model on a honeycomb lattice. We show that the model exhibits three topologically-different insulating phases at half filling, which are distinguished by different quantized values of the spin Hall conductivity. We analytically determine the phase boundaries, where the valence and conduction bands touch with each other with forming the Dirac nodes at the Fermi level. The results are discussed in terms of the effective antisymmetric spin-orbit coupling. The relation to the Kane- Mele model and implications for a magnetoelectric effect are also discussed.

  9. Variational cluster approach to the Hubbard model on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Seki, Kazuhiro; Ohta, Yukinori

    2013-06-01

    We study the ground-state properties of the Hubbard model on the honeycomb lattice at half filling. Using the variational cluster approximation, We study the semimetal-insulator transition and antiferromagnetism as functions of the on-site Coulomb interaction U. When U is switched on, a small, but finite, single-particle gap appears; thus, we conclude that a tiny gap appears with arbitrary small U > 0. With further increases in U, the system goes into the antiferromagnetic state. We find that the staggered magnetization increases continuously with increasing U and that the antiferromagnetic phase transition is of the second order.

  10. Friction factor data for flat plate tests of smooth and honeycomb surfaces 

    E-print Network

    Ha, Tae Woong

    1989-01-01

    the procedure of a test. Chapter IV shows the friction factor model for a one dimensional, steady, adiabatic flow of a perfect gas through a constant area duct. Exper imental data in chapter V and appendix A , B , and C are presented which depend on inlet...-honeycomb surfaces with three-clearances, 6.9 bar to 17.9 bar range of inlet pressure, and 5,000 to 100,000 range of the Reynolds number. The optimum geometries for the maximum friction factor are found as a function of cell width to cell depth and cell width...

  11. Optical properties of two-dimensional photonic lattices fabricated as honeycomb nanostructures in compound semiconductors

    NASA Astrophysics Data System (ADS)

    Gourley, P. L.; Wendt, J. R.; Vawter, G. A.; Brennan, T. M.; Hammons, B. E.

    1994-02-01

    We have experimentally studied two-dimensional photonic lattices, honeycomb nanostructures, fabricated by electron beam lithography with (Al,Ga)As materials. Surface normal optical properties were investigated by measuring reflectance to determine the effective index of refraction and lattice stability against degradation. Also, continuous wave and time-resolved luminescence spectroscopy was used to assess electron-hole recombination. Finally, light scattering was employed to study photon coupling and propagation through the lattice. These measurements show that the structures are stable, that nonradiative surface recombination is present, and that resonant coupling of light into/out of the lattice occurs at selected wavelengths satisfying a Bragg condition.

  12. Optical properties of two-dimensional photonic lattices fabricated as honeycomb nanostructures in compound semiconductors

    SciTech Connect

    Gourley, P.L.; Wendt, J.R.; Vawter, G.A.; Brennan, T.M.; Hammons, B.E. (Sandia National Laboratories Albuquerque, New Mexico 87185 (United States))

    1994-02-07

    We have experimentally studied two-dimensional photonic lattices, honeycomb nanostructures, fabricated by electron beam lithography with (Al,Ga)As materials. Surface normal optical properties were investigated by measuring reflectance to determine the effective index of refraction and lattice stability against degradation. Also, continuous wave and time-resolved luminescence spectroscopy was used to assess electron-hole recombination. Finally, light scattering was employed to study photon coupling and propagation through the lattice. These measurements show that the structures are stable, that nonradiative surface recombination is present, and that resonant coupling of light into/out of the lattice occurs at selected wavelengths satisfying a Bragg condition.

  13. Low-energy impact resistance of graphite-epoxy plates and ALS honeycomb sandwich panels

    NASA Technical Reports Server (NTRS)

    Hui, David

    1989-01-01

    Low energy impact may be potentially dangerous for many highly optimized stiff structures. Impact by foreign objects such as birds, ice, and runways stones or dropping of tools occur frequently and the resulting damage and stress concentrations may be unacceptable from a designer's standpoint. The barely visible, yet potentially dangerous dents due to impact of foreign objects on the Advanced Launch System (ALS) structure are studied. Of particular interest is the computation of the maximum peak impact force for a given impactor mass and initial velocity. The theoretical impact forces will be compared with the experimental dropweight results for the ALS face sheets alone as well as the ALS honeycomb sandwich panels.

  14. A comparison of the static and dynamic characteristics of straight-bore and convergent tapered-bore honeycomb annular gas seals 

    E-print Network

    Dawson, Matthew Peter

    2000-01-01

    Results are presented from tests conducted with straight-bore and convergent tapered-bore honeycomb annular gas seals. The test seals had a 114.3 mm bore with an L/D = 0.75 and a nominal radial clearance of 0.19 mm. The honeycomb cell depth for both...

  15. Simulation of cracking cores when molding piston components

    NASA Astrophysics Data System (ADS)

    Petrenko, Alena; Soukup, Josef

    2014-08-01

    The article deals with pistons casting made from aluminum alloy. Pistons are casting at steel mold with steel core. The casting is provided by gravity casting machine. The each machine is equipped by two metal molds, which are preheated above temperature 160 °C before use. The steel core is also preheated by flame. The metal molds and cores are heated up within the casting process. The temperature of the metal mold raise up to 200 °C and temperature of core is higher. The surface of the core is treated by nitration. The mold and core are cooled down by water during casting process. The core is overheated and its top part is finally cracked despite its intensive water-cooling. The life time cycle of the core is decreased to approximately 5 to 15 thousands casting, which is only 15 % of life time cycle of core for production of other pistons. The article presents the temperature analysis of the core.

  16. Creep of laminated aluminum composites

    Microsoft Academic Search

    W. Moore; T. J. Davies

    1980-01-01

    The creep behavior of a laminate system consisting of alternate layers of pure aluminum and SAP (sintered aluminum powder)\\u000a sheet has been examined in the temperature range 323 to 473 K and in the stress range 35 to 68 MN m?2. It was observed that secondary creep strain in the laminates was greater than in elemental SAP; the secondary creep

  17. Chrome - Free Aluminum Coating System

    NASA Technical Reports Server (NTRS)

    Bailey, John H.; Gugel, Jeffrey D.

    2010-01-01

    This slide presentation concerns the program to qualify a chrome free coating for aluminum. The program was required due to findings by OSHA and EPA, that hexavalent chromium, used to mitigate corrosion in aerospace aluminum alloys, poses hazards for personnel. This qualification consisted of over 4,000 tests. The tests revealed that a move away from Cr+6, required a system rather than individual components and that the maximum corrosion protection required pretreatment, primer and topcoat.

  18. Aluminum-air battery crystallizer

    Microsoft Academic Search

    A. Maimoni

    1987-01-01

    A prototype crystallizer system for the aluminum-air battery operated reliably through simulated startup and shutdown cycles and met its design objectives. The crystallizer system allows for crystallization and removal of the aluminium hydroxide reaction product; it is required to allow steady-state and long-term operation of the aluminum-air battery. The system has to minimize volume and maintain low turbulence and shear

  19. 75 FR 70689 - Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum-Greenwood Forge Division; Currently...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-18

    ...Administration [TA-W-70,376] Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum- Greenwood Forge Division; Currently Known...2, 2009, applicable to workers of Kaiser Aluminum Fabricated Products, LLC, Kaiser...

  20. PREFACE: Ultrathin layers of graphene, h-BN and other honeycomb structures Ultrathin layers of graphene, h-BN and other honeycomb structures

    NASA Astrophysics Data System (ADS)

    Geber, Thomas; Oshima, Chuhei

    2012-08-01

    Since ancient times, pure carbon materials have been familiar in human society—not only diamonds in jewellery and graphite in pencils, but also charcoal and coal which have been used for centuries as fuel for living and industry. Carbon fibers are stronger, tougher and lighter than steel and increase material efficiency because of their lower weight. Today, carbon fibers and related composite materials are used to make the frames of bicycles, cars and even airplane parts. The two-dimensional allotrope, now called graphene, is just a single layer of carbon atoms, locked together in a strongly bonded honeycomb lattice. In plane, graphene is stiffer than diamond, but out-of-plane it is soft, like rubber. It is virtually invisible, may conduct electricity (heat) better than copper and weighs next to nothing. Carbon compounds with two carbon atoms as a base, such as graphene, graphite or diamond, have isoelectronic sister compounds made of boron-nitrogen pairs: hexagonal and cubic boron nitride, with almost the same lattice constant. Although the two 2D sisters, graphene and h-BN, have the same number of valence electrons, their electronic properties are very different: freestanding h-BN is an insulator, while charge carriers in graphene are highly mobile. The past ten years have seen a great expansion in studies of single-layer and few-layer graphene. This activity has been concerned with the ? electron transport in graphene, in electric and magnetic fields. More than 30 years ago, however, single-layer graphene and h-BN on solid surfaces were widely investigated. It was noted that they drastically changed the chemical reactivity of surfaces, and they were known to 'poison' heterogeneous catalysts, to passivate surfaces, to prevent oxidation of surfaces and to act as surfactants. Also, it was realized that the controlled growth of h-BN and graphene on substrates yields the formation of mismatch driven superstructures with peculiar template functionality on the nanometer scale. This special section contains interesting papers on graphene, h-BN and related 'honeycomb' compounds on solid surfaces, which are currently in development. Interfacial interaction strongly modifies the electronic and atomic structures of these overlayer systems and substrate surfaces. In addition, one can recognize a variety of growth phenomena by changing the surface and growth conditions, which are promising as regards fabricating those noble nanosystems. We have great pleasure in acknowledging the enthusiastic response and participation of our invited authors and their diligent preparation of the manuscripts. Ultrathin layers of graphene, h-BN and other honeycomb structures contents Ultrathin layers of graphene, h-BN and other honeycomb structuresThomas Geber and Chuhei Oshima Templating of arrays of Ru nanoclusters by monolayer graphene/Ru Moirés with different periodicitiesEli Sutter, Bin Wang, Peter Albrecht, Jayeeta Lahiri, Marie-Laure Bocquet and Peter Sutter Controllable p-doping of graphene on Ir(111) by chlorination with FeCl3N A Vinogradov, K A Simonov, A V Generalov, A S Vinogradov, D V Vyalikh, C Laubschat, N Mårtensson and A B Preobrajenski Optimizing long-range order, band gap, and group velocities for graphene on close-packed metal surfacesF D Natterer, S Rusponi, M Papagno, C Carbone and H Brune Epitaxial growth of graphene on transition metal surfaces: chemical vapor deposition versus liquid phase depositionSamuel Grandthyll, Stefan Gsell, Michael Weinl, Matthias Schreck, Stefan Hüfner and Frank Müller High-yield boron nitride nanosheets from 'chemical blowing': towards practical applications in polymer compositesXuebin Wang, Amir Pakdel, Chunyi Zhi, Kentaro Watanabe, Takashi Sekiguchi, Dmitri Golberg and Yoshio Bando BCx layers with honeycomb lattices on an NbB2(0001) surfaceChuhei Oshima Epitaxial growth of boron-doped graphene by thermal decomposition of B4CWataru Norimatsu, Koichiro Hirata, Yuta Yamamoto, Shigeo Arai and Michiko Kusunoki Mechanical exfoliation of epitaxial graphene on Ir(111) enabled by Br2 intercalationCh

  1. Effects of load voltage on voltage breakdown modes of electrical exploding aluminum wires in air

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Li, Xingwen; Yang, Zefeng; Wang, Kun; Chao, Youchuang; Shi, Zongqian; Jia, Shenli; Qiu, Aici

    2015-06-01

    The effects of the load voltage on the breakdown modes are investigated in exploding aluminum wires driven by a 1 kA, 0.1 kA/ns pulsed current in air. From laser probing images taken by laser shadowgraphy, schlieren imaging, and interferometry, the position of the shockwave front, the plasma channel, and the wire core edge of the exploding product can be determined. The breakdown mode makes a transition from the internal mode, which involves breakdown inside the wire core, to the shunting mode, which involves breakdown in the compressed air, with decreasing charging voltage. The breakdown electrical field for a gaseous aluminum wire core of nearly solid density is estimated to be more than 20 kV/cm, while the value for gaseous aluminum of approximately 0.2% solid density decreases to 15-20 kV/cm. The breakdown field in shunting mode is less than 20 kV/cm and is strongly affected by the vaporized aluminum, the desorbed gas, and the electrons emitted from the wire core during the current pause. Ohmic heating during voltage collapses will induce further energy deposition in the current channel and thus will result in different expansion speeds for both the wire core and the shockwave front in the different modes.

  2. Cobalt (II) chloride promoted formation of honeycomb patterned cellulose acetate films.

    PubMed

    Naboka, Olga; Sanz-Velasco, Anke; Lundgren, Per; Enoksson, Peter; Gatenholm, Paul

    2012-02-01

    CoCl(2) containing honeycomb patterned films were prepared from cellulose acetate (CA)/CoCl(2)/acetone solutions by the breath figure method in a wide range of humidities. Size and pore regularity depend on the CA/CoCl(2) molar ratio and humidity. When replacing CoCl(2) with Co(NO(3))(2) or CoBr(2), no formation of ordered porosity in the cellulose acetate films is observed. According to data from scanning electron microscopy (SEM), Energy Dispersive X-ray Microanalysis (EDX), X-ray Diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, the key role in the formation of honeycomb structures can be attributed to the physical and chemical properties of CoCl(2) - hygroscopicity, low interaction with CA, and extraction from CA/CoCl(2)/acetone solution by water droplets condensed on the surface of the CA/CoCl(2) solution. Obtained films are prospective for using in catalysis, hydrogen fuel cells, and optical sensing materials. PMID:22074692

  3. Electrokinetic desalination using honeycomb carbon nanotubes (HC-CNTs): a conceptual study by molecular simulation.

    PubMed

    Chen, Qile; Kong, Xian; Li, Jipeng; Lu, Diannan; Liu, Zheng

    2014-09-21

    A new concept of electrokinetic desalination using a CNT honeycomb is presented through molecular dynamics simulation. The preferential translocation of ions towards the outlets near two electrodes was realized by applying an electric field perpendicular to bulk fluid flow in a CNT network, which, in the meantime, generated deionized water flux discharged from the central outlets. The effects of the major factors such as electric field strength, numbers of separation units, diameter of CNT, and ion concentration on the desalination were examined. It was shown that over 95% salt rejection and around 50% fresh water recovery were achieved by the presented module by applying an electric field of 0.8 V nm(-1). CNT diameter, which is critical to ion rejection without the electric field, had a marginal effect on the desalination of this new module when a strong electric field was applied. The desalination was also not sensitive to ion concentration, indicating its excellent workability for a wide range of water salinity, e.g. from brackish water to seawater. A potential of mean force profile revealed a free energy barrier as large as 2.0-6.0 kcal mol(-1) for ions to move opposite to the implemented electrical force. The simulation confirmed the high potential of the CNT honeycomb in water desalination. PMID:25092215

  4. CaMn2Sb2 : Spin waves on a frustrated antiferromagnetic honeycomb lattice

    NASA Astrophysics Data System (ADS)

    McNally, D. E.; Simonson, J. W.; Kistner-Morris, J. J.; Smith, G. J.; Hassinger, J. E.; DeBeer-Schmidt, L.; Kolesnikov, A. I.; Zaliznyak, I. A.; Aronson, M. C.

    2015-05-01

    We present inelastic neutron scattering measurements of the antiferromagnetic insulator CaMn2Sb2 , which consists of corrugated honeycomb layers of Mn. The dispersion of magnetic excitations has been measured along the H and L directions in reciprocal space, with a maximum excitation energy of ?24 meV. These excitations are well described by spin waves in a Heisenberg model, including first- and second-neighbor exchange interactions J1 and J2 in the Mn plane and also an exchange interaction between planes. The determined ratio J2/J1?1 /6 suggests that CaMn2Sb2 is an example of a compound that lies very close to the mean field tricritical point, known for the classical Heisenberg model on the honeycomb lattice, where the Néel phase and two different spiral phases coexist. The magnitude of the determined exchange interactions reveals a mean field ordering temperature ?4 times larger than the reported Néel temperature TN=85 K, suggesting significant frustration arising from proximity to the tricritical point.

  5. Quantum computational universality of Affleck-Kennedy-Lieb-Tasaki states beyond the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Wei, Tzu-Chieh

    2014-03-01

    Universal quantum computation can be achieved by simply performing single-spin measurements on a highly entangled resource state, such as cluster states. The family of Affleck-Kennedy-Lieb-Tasaki (AKLT) states has recently been explored; for example, the spin-1 AKLT chain can be used to simulate single-qubit gate operations on a single qubit, and the spin-3/2 two-dimensional AKLT state on the honeycomb lattice can be used as a universal resource. However, it is unclear whether such universality is a coincidence for the specific state or a shared feature in all two-dimensional AKLT states. Here we consider the family of spin-3/2 AKLT states on various trivalent Archimedean lattices and show that in addition to the honeycomb lattice, the spin-3/2 AKLT states on the square octagon (4 ,82) and the `cross' (4 , 6 , 12) lattices are also universal resources, whereas the AKLT state on the `star' (3 ,122) lattice is likely not due to geometric frustration. Ref. T.-C. Wei, arXiv:1306.1420.

  6. Electrochemical properties of honeycomb-like structured HFBI self-organized membranes on HOPG electrodes.

    PubMed

    Yamasaki, Ryota; Takatsuji, Yoshiyuki; Lienemann, Michael; Asakawa, Hitoshi; Fukuma, Takeshi; Linder, Markus; Haruyama, Tetsuya

    2014-11-01

    HFBI (derived from Trichoderma sp.) is a unique structural protein, which forms a self-organized monolayer at both air/water interface and water/solid interfaces in accurate two-dimensional ordered structures. We have taken advantage of the unique functionality of HFBI as a molecular carrier for preparation of ordered molecular phase on solid substrate surfaces. The HFBI molecular carrier can easily form ordered structures; however, the dense molecular layers form an electrochemical barrier between the electrode and solution phase. In this study, the electrochemical properties of HFBI self-organized membrane-covered electrodes were investigated. Wild-type HFBI has balanced positive and negative charges on its surface. Highly oriented pyrolytic graphite (HOPG) electrodes coated with HFBI molecules were investigated electrochemically. To improve the electrochemical properties of this HFBI-coated electrode, the two types of HFBI variants, with oppositely charged surfaces, were prepared genetically. All three types of HFBI-coated HOPG electrode perform electron transfer between the electrode and solution phase through the dense HFBI molecular layer. This is because the HFBI self-organized membrane has a honeycomb-like structure, with penetrating holes. In the cases of HFBI variants, the oppositely charged HFBI membrane phases shown opposite electrochemical behaviors in electrochemical impedance spectroscopy. HFBI is a molecule with a unique structure, and can easily form honeycomb-like structures on solid material surfaces such as electrodes. The molecular membrane phase can be used for electrochemical molecular interfaces. PMID:25454670

  7. Featureless and nonfractionalized Mott insulators on the honeycomb lattice at 1/2 site filling

    PubMed Central

    Kimchi, Itamar; Parameswaran, S. A.; Turner, Ari M.; Wang, Fa; Vishwanath, Ashvin

    2013-01-01

    Within the Landau paradigm, phases of matter are distinguished by spontaneous symmetry breaking. Implicit here is the assumption that a completely symmetric state exists: a paramagnet. At zero temperature such quantum featureless insulators may be forbidden, triggering either conventional order or topological order with fractionalized excitations. Such is the case for interacting particles when the particle number per unit cell, f, is not an integer. However, can lattice symmetries forbid featureless insulators even at integer f? An especially relevant case is the honeycomb (graphene) lattice—where free spinless fermions at (the two sites per unit cell mean is half-filling per site) are always metallic. Here we present wave functions for bosons, and a related spin-singlet wave function for spinful electrons, on the honeycomb lattice and demonstrate via quantum to classical mappings that they do form featureless Mott insulators. The construction generalizes to symmorphic lattices at integer f in any dimension. Our results explicitly demonstrate that in this case, despite the absence of a noninteracting insulator at the same filling, lack of order at zero temperature does not imply fractionalization.

  8. Experimental Investigation on Mechanical Properties of Magnetorheological Elastomer with Circular Honeycomb Holes

    NASA Astrophysics Data System (ADS)

    Yu, Miao; Xing, Zhiwei; Zheng, Xing; Fu, Jie; Choi, Seung-Bok

    2014-12-01

    In order to enhance adjustable mechanical properties of a specific magnetorheological elastomer (MRE), this study presents a new exterior structure of MRE by punching circular honeycomb holes on the MRE samples. Seven silicone rubber MRE samples with the same component are fabricated and then punched holes with different numbers and diameters. The influence of different porosities on the mechanical properties of MRE under various magnetic fields is experimentally investigated by using a rheometer with electromagnetic suite. It is shown from experimental investigation that the porosity of MRE samples has a significant impact on the performance of MRE; the shear storage modulus (MR effect) and the loss factor is greatly increased. It is also observed that all the field-induced mechanical properties of the samples attain their respective maximum performance when the porosity increases to a critical value. The experimental results presented in this work directly indicate that high performances of the field-dependent mechanical and rheological properties can be achieved by means of external alternative structures such as honeycomb holes.

  9. Moving vortex phases, dynamical symmetry breaking, and jamming for vortices in honeycomb pinning arrays

    SciTech Connect

    Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia [Los Alamos National Laboratory

    2008-01-01

    We show using numerical simulations that vortices in honeycomb pinning arrays can exhibit a remarkable variety of dynamical phases that are distinct from those found for triangular and square pinning arrays. In the honeycomb arrays, it is possible for the interstitial vortices to form dimer or higher n-mer states which have an additional orientational degree of freedom that can lead to the formation of vortex molecular crystals. For filling fractions where dimer states appear, a dynamical symmetry breaking can occur when the dimers flow in one of two possible alignment directions. This leads to transport in the direction transverse to the applied drive. We show that dimerization produces distinct types of moving phases which depend on the direction of the driving force with respect to the pinning lattice symmetry. When the dimers are driven along certain directions, a reorientation of the dimers can produce a jamming phenomenon which results in a strong enhancement in the critical depinning force. The jamming can also cause unusual effects such as an increase in the critical depinning force when the size of the pinning sites is reduced.

  10. Method for Selective Cleaning of Mold Release from Composite Honeycomb Surfaces

    NASA Technical Reports Server (NTRS)

    Pugel, Diane

    2011-01-01

    Honeycomb structures are commonly employed as load- and force-bearing structures as they are structurally strong and lightweight. Manufacturing processes for heat-molded composite honeycomb structures commence with the placement of pre-impregnated composite layups over metal mandrels. To prevent permanent bonding between the composite layup and the metal mandrels, an agent, known as a mold release agent, is used. Mold release agents allow the molded composite material to be removed from mandrels after a heat-forming process. Without a specific removal process, mold release agents may continue to adhere to the surface of the composite material, thereby affecting the bonding of other materials that may come into contact with the composite surface in later stages of processing A constituent common to commercially available household cleaning agents is employed for the removal of mold release agents common to the manufacturing of heat-formed composite materials. The reliability of the solvent has been proven by the longevity and reliability of commercial household cleaners. At the time of this reporting, no one has attempted using constituent for this purpose. The material to be cleaned is immersed in the solution, vertically removed so that the solution is allowed to drain along cell walls and into a solvent bath, and then placed on a compressed airflow table for drying.

  11. Removal of alachlor from water by catalyzed ozonation on Cu/Al2O3 honeycomb

    PubMed Central

    2013-01-01

    Background The herbicide alachlor (2-chloro-2?6?-diethyl-N-methoxymethylacetanilide) has been known as a probable human carcinogen, and the MCL (minimum contamination level) for drinking water has been set at 2 ?g L-1. Therefore, the advanced methods for effectively removing it from water are a matter of interest. Catalyzed ozonation is a promising method for refractory organics degradation. Cu/Al2O3 catalyzed ozonation for degrading an endocrine disruptor (alachlor) in water was investigated. Results Experimental results showed that the ozonation of alachlor can be effectively catalyzed and enhanced by Cu/Al2O3-honeycomb. The main intermediate products formed (aliphatic carboxylic acids) were mineralized to a large extent in the catalytic process. Conclusions This study has shown that Cu/Al2O3-honeycomb is a feasible and efficient catalyst in the ozonation of alachlor in water. Less intermediate oxidation product was produced in the catalytic process than in the uncatalytic one. Furthermore, the mineralization of alachlor could be enhanced by increasing the pH of the reaction solution. PMID:23977841

  12. Magnetism in spin models for depleted honeycomb-lattice iridates: Spin-glass order towards percolation

    NASA Astrophysics Data System (ADS)

    Andrade, Eric C.; Vojta, Matthias

    2014-11-01

    Iridates are characterized by a fascinating interplay of spin-orbit and electron-electron interactions. The honeycomb-lattice materials A2IrO3 (A =Na,Li ) have been proposed to realize pseudospin-1/2 Mott insulating states with strongly anisotropic exchange interactions, described by the Heisenberg-Kitaev model, but other scenarios involving longer-range exchange interactions or more delocalized electrons have been put forward as well. Here we study the influence of nonmagnetic doping, i.e., depleted moments, on the magnetic properties of experimentally relevant variants of the Heisenberg-Kitaev and Heisenberg J1-J2-J3 models. We generically find that the zigzag order of the clean system is replaced, upon doping, by a spin-glass state with short-ranged zigzag correlations. We determine the spin-glass temperature as a function of the doping level and show that this quantity allows one to assess the importance of longer-range exchange interactions when the doping is driven across the site-percolation threshold of the honeycomb lattice.

  13. Hall conductance, topological quantum phase transition, and the Diophantine equation on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Sato, Masatoshi; Tobe, Daijiro; Kohmoto, Mahito

    2008-12-01

    We consider a tight-binding model with the nearest-neighbor hopping integrals on the honeycomb lattice in a magnetic field. Assuming one of the three hopping integrals, which we denote by ta , can take a different value from the two others, we study quantum phase structures controlled by the anisotropy of the honeycomb lattice. For weak and strong ta regions, the Hall conductances are calculated algebraically by using the Diophantine equation. Except for a few specific gaps, we completely determine the Hall conductances in these two regions including those for subband gaps. In a weak magnetic field, it is found that the weak ta region shows the unconventional quantization of the Hall conductance, ?xy=-(e2/h)(2n+1) (n=0,±1,±2,…) , near the half filling, while the strong ta region shows only the conventional one, ?xy=-(e2/h)n (n=0,±1,±2,…) . From the topological nature of the Hall conductance, the existence of gap closing points and quantum phase transitions in the intermediate ta region is concluded. We also study numerically the quantum phase structure in detail and find that even when ta=1 , namely, in graphene case, the system is in the weak ta phase except when the Fermi energy is located near the Van Hove singularity or the lower and upper edges of the spectrum.

  14. Chemical Dynamics in Energetic Materials Incorporating Aluminum Nanoparticles

    NASA Astrophysics Data System (ADS)

    Lewis, William K.; Harruff, Barbara A.; Fernando, K. A. Shiral; Smith, Marcus J.; Guliants, Elena A.; Bunker, Christopher E.

    2010-06-01

    Aluminum nanoparticles are widely considered attractive as fuels due to the high heat of reaction associated with their oxidation, and the potential for fast reaction due to their small size. However, the reaction dynamics can also be strongly influenced by the passivation layer that coats the reactive metal surface. Typically, this takes the form of a naturally-occurring oxide shell on the nanoparticle, but other passivation schemes are now available. We have recently developed a sonochemical synthesis procedure to produce aluminum nanoparticles capped with oleic acid. These nanoparticles have an aluminum metal core, some organic-provided oxide, and an organic shell. To investigate the effect of the passivation method on the chemical dynamics in energetic materials, we have studied samples consisting of a mixture of a metal nanoparticle fuel and an ammonium nitrate or ammonium perchlorate oxidizer. The metal fuel is either commercially available oxide-coated aluminum nanoparticles, or the oleic acid-capped nanoparticles. The energetic samples are ignited with an IR laser pulse. Following ignition, the chemical dynamics are studied using visible emission spectroscopy and mass spectrometry. Preliminary results suggest that our Al-oleic acid nanoparticles are able to react more rapidly than those that are conventionally passivated with a naturally-occurring oxide shell. K. A. S. Fernando, M. J. Smith, B. A. Harruff, W. K. Lewis, E. A. Guliants and C. E. Bunker J. Phys. Chem. C, 113, 500 (2009).

  15. Commonwealth Aluminum: Manufacturer Conducts Plant-Wide Energy Assessments at Two Aluminum Sheet Production Operations;

    SciTech Connect

    Not Available

    2006-04-01

    DOE Industrial Technologies Program case study describes the savings possible if Commonwealth Aluminum (now Aleris Rolled Products) makes improvements noted in energy assessments at two aluminum mills.

  16. Bending behavior of lightweight sandwich-walled shells with pyramidal truss cores

    E-print Network

    Vaziri, Ashkan

    , three-point bending experiments and finite element (FE) based simulations. The aluminum pyramidal cores movement through them. This limit on flow circulation imposes significant restrictions in thermal and transport properties preventing their deployment as functional structures. Therefore, fabrication

  17. Modelling the fatigue behaviour of composites honeycomb materials (aluminium\\/aramide fibre core) using four-point bending tests

    Microsoft Academic Search

    A. Abbadi; Z. Azari; S. Belouettar; J. Gilgert; P. Freres

    2010-01-01

    Composite Sandwich Materials are being increasingly used in high-performance structural applications because of their high stiffness and low weight characteristics. Presently, the long-term performance of such structures, especially under fatigue loading, is not enough studied. The aim of this paper is to address such fatigue behaviour by using a fatigue model verified by experimentation. The fatigue model is based on

  18. Oxidation of ligand-protected aluminum clusters: An ab initio molecular dynamics study

    SciTech Connect

    Alnemrat, Sufian; Hooper, Joseph P., E-mail: jphooper@nps.edu [Department of Physics, Naval Postgraduate School, Monterey, California 93943 (United States)

    2014-03-14

    We report Car-Parrinello molecular dynamics simulations of the oxidation of ligand-protected aluminum clusters that form a prototypical cluster-assembled material. These clusters contain a small aluminum core surrounded by a monolayer of organic ligand. The aromatic cyclopentadienyl ligands form a strong bond with surface Al atoms, giving rise to an organometallic cluster that crystallizes into a low-symmetry solid and is briefly stable in air before oxidizing. Our calculations of isolated aluminum/cyclopentadienyl clusters reacting with oxygen show minimal reaction between the ligand and O{sub 2} molecules at simulation temperatures of 500 and 1000 K. In all cases, the reaction pathway involves O{sub 2} diffusing through the ligand barrier, splitting into atomic oxygen upon contact with the aluminum, and forming an oxide cluster with aluminum/ligand bonds still largely intact. Loss of individual aluminum-ligand units, as expected from unimolecular decomposition calculations, is not observed except following significant oxidation. These calculations highlight the role of the ligand in providing a steric barrier against oxidizers and in maintaining the large aluminum surface area of the solid-state cluster material.

  19. Weld Repair of Thin Aluminum Sheet

    NASA Technical Reports Server (NTRS)

    Beuyukian, C. S.; Mitchell, M. J.

    1986-01-01

    Weld repairing of thin aluminum sheets now possible, using niobium shield and copper heat sinks. Refractory niobium shield protects aluminum adjacent to hole, while copper heat sinks help conduct heat away from repair site. Technique limits tungsten/inert-gas (TIG) welding bombardment zone to melt area, leaving surrounding areas around weld unaffected. Used successfully to repair aluminum cold plates on Space Shuttle, Commercial applications, especially in sealing fractures, dents, and holes in thin aluminum face sheets or clad brazing sheet in cold plates, heat exchangers, coolers, and Solar panels. While particularly suited to thin aluminum sheet, this process also used in thicker aluminum material to prevent surface damage near weld area.

  20. * Please address all the correspondence to zhao@lmt.ens-cachan.fr 1 Impact behavior of honeycombs under combined

    E-print Network

    . Some previous works proposed the dynamic multiaxial testing methods using drop-weight or high speed Hopkinson bars with beveled ends to perform combined shear-compression test under impact loading. It permits* Please address all the correspondence to zhao@lmt.ens-cachan.fr 1 Impact behavior of honeycombs

  1. A novel isolation curtain to reduce turbine ingress heating and an advanced model for honeycomb labyrinth seals 

    E-print Network

    Choi, Dong Chun

    2006-08-16

    structure was modeled using the concept of the baffle (zero-thickness wall) and the simplified 2-D fin, respectively. The 3-D model showed that even a small axial change of the tooth (or honeycomb wall) location, or a small circumferential change...

  2. Comparison of X-Ray, Millimeter Wave, Shearography and Through-Transmission Ultrasonic Methods for Inspection of Honeycomb Composites

    NASA Astrophysics Data System (ADS)

    Abou-Khousa, M. A.; Ryley, A.; Kharkovsky, S.; Zoughi, R.; Daniels, D.; Kreitinger, N.; Steffes, G.

    2007-03-01

    Honeycomb composites are increasingly finding utility in a variety of environments and applications, such as aircraft structural components, flight control components, radomes, etc. In-service and environmental stresses can produce unwanted flaws that adversely affect the structural integrity and functionality of these composites. These flaws may be in the forms of disbonds, delaminations, impact damage, crushed honeycomb, moisture intrusion, internal cracks, etc. There are several nondestructive testing (NDT) methods that may be used to inspect these composites for the presence and evaluation of these flaws. Such NDT methods include X-ray computed tomography, near-field millimeter wave, shearography, and ultrasonic testing. To assess the capabilities of these methods for honeycomb composite inspection, two honeycomb composites panels were produced with several embedded flaws and missing material primarily representing planar disbonds at various levels within the thickness of the panels and with different shapes. Subsequently, the aforementioned NDT methods were used to produce images of the two panels. This paper presents the results of these investigations and a comparison among the capabilities of these methods.

  3. Induction of Female-to–male Sex Change in the Honeycomb Grouper (Epinephelus merra) by 11-ketotestosterone Treatments

    Microsoft Academic Search

    Ramji Kumar Bhandari; Mohammad Ashraful Alam; Kiyoshi Soyano; Masaru Nakamura

    2006-01-01

    The honeycomb grouper, Epinephelus merra , is a protogynous hermaphrodite fish. Sex steroid hor- mones play key roles in sex change of this species. A significant drop in endogenous estradiol- 17? ? ? ? (E2) levels alone triggers female-to-male sex change, and the subsequent elevation of 11- ketotestosterone (11KT) levels correlates with the progression of spermatogenesis. To elucidate the role

  4. Aluminum Metal Matrix Composites

    SciTech Connect

    Hunt, Warren; Herling, Darrell R.

    2004-02-01

    Metal matrix composites comprise a relatively wide range of materials defined by the metal matrix, reinforcement type, and reinforcement geometry. In the area of the matrix, most metallic systems have been explored for use in metal matrix composites, including Al, Be, Mg, Ti, Fe, Ni, Co, and Ag. By far, the largest usage is in aluminum matrix composites. From a reinforcement perspective, the materials used are typically ceramics since they provide a very desirable combination of stiffness, strength, and relatively low density. Candidate reinforcement materials include SiC, Al2O3, B4C, TiC, TiB2, graphite, and a number of other ceramics. In addition, there has been work on metallic materials as reinforcements, notably W and steel fibers. The morphology of the reinforcement material is another variable of importance in metal matrix composites. The three major classes of reinforcement morphology are continuous fiber, chopped fiber or whisker, and particulate. Typically, the selection of the reinforcement morphology is determined by the desired property/cost combination. Generally, continuous fiber reinforced MMCs provide the highest properties in the direction of the fiber orientation but are the most expensive. Chopped fiber and whisker reinforced materials can produce significant property improvements in the plane or direction of their orientation, at somewhat lower cost. Particulates provide a comparatively more moderate but isotropic increase in properties and are typically available at the lowest cost. By adding to the three variables of metallic matrix, reinforcement material, and reinforcement morphology the further options of reinforcement volume fraction, orientation, and matrix alloy composition and heat treatment, it is apparent that there is a very wide range of available material combinations and resultant properties. This paper will focus on how MMCs have been applied in specific application areas.

  5. Scaleable Clean Aluminum Melting Systems

    SciTech Connect

    Han, Q.; Das, S.K. (Secat, Inc.)

    2008-02-15

    The project entitled 'Scaleable Clean Aluminum Melting Systems' was a Cooperative Research and Development Agreements (CRADAs) between Oak Ridge National Laboratory (ORNL) and Secat Inc. The three-year project was initially funded for the first year and was then canceled due to funding cuts at the DOE headquarters. The limited funds allowed the research team to visit industrial sites and investigate the status of using immersion heaters for aluminum melting applications. Primary concepts were proposed on the design of furnaces using immersion heaters for melting. The proposed project can continue if the funding agency resumes the funds to this research. The objective of this project was to develop and demonstrate integrated, retrofitable technologies for clean melting systems for aluminum in both the Metal Casting and integrated aluminum processing industries. The scope focused on immersion heating coupled with metal circulation systems that provide significant opportunity for energy savings as well as reduction of melt loss in the form of dross. The project aimed at the development and integration of technologies that would enable significant reduction in the energy consumption and environmental impacts of melting aluminum through substitution of immersion heating for the conventional radiant burner methods used in reverberatory furnaces. Specifically, the program would couple heater improvements with furnace modeling that would enable cost-effective retrofits to a range of existing furnace sizes, reducing the economic barrier to application.

  6. Induction in an Aluminum Can

    NSDL National Science Digital Library

    This activity demonstrates Lenz's Law, which states that an induced electromotive force generates a current that induces a counter magnetic field that opposes the magnetic field generating the current. In the demonstration, an empty aluminum can floats on water in a tray, such as a Petri dish. Students spin a magnet just inside the can without touching the can. The can begins to spin. Understanding what happens can be explained in steps: first, the twirling magnet creates an alternating magnetic field. Students can use a nearby compass to observe that the magnetic field is really changing. Second, the changing magnetic field permeates most things around it, including the aluminum can itself. A changing magnetic field will cause an electric current to flow when there is a closed loop of an electrically conducting material. Even though the aluminum can is not magnetic, it is metal and will conduct electricity. So the twirling magnet causes an electrical current to flow in the aluminum can. This is called an "induced current." Third, all electric currents create magnetic fields. So, in essence, the induced electrical current running through the can creates its very own magnetic field, making the aluminum can magnetic. This is activity four of "Exploring Magnetism." The guide includes science background information, student worksheets, glossary and related resources.

  7. Aluminum Nanoarrays for Plasmon-Enhanced Light Harvesting.

    PubMed

    Lee, Minah; Kim, Jong Uk; Lee, Ki Joong; Ahn, SooHoon; Shin, Yong-Beom; Shin, Jonghwa; Park, Chan Beum

    2015-06-23

    The practical limits of coinage-metal-based plasmonic materials demand sustainable, abundant alternatives with a wide plasmonic range of the solar energy spectrum. Aluminum (Al) is an emerging alternative, but its instability in aqueous environments critically limits its applicability to various light-harvesting systems. Here, we report a design strategy to achieve a robust platform for plasmon-enhanced light harvesting using Al nanostructures. The incorporation of mussel-inspired polydopamine nanolayers in the Al nanoarrays allowed for the reliable use of Al plasmonic resonances in a highly corrosive photocatalytic redox solution and provided nanoscale arrangement of organic photosensitizers on Al surfaces. The Al-photosensitizer core-shell assemblies exhibited plasmon-enhanced light absorption, which resulted in a 300% efficiency increase in photo-to-chemical conversion. Our strategy enables stable and advanced use of aluminum for plasmonic light harvesting. PMID:26046384

  8. Influence of insulating coating on aluminum wire explosions

    NASA Astrophysics Data System (ADS)

    Li, Yang; Sheng, Liang; Wu, Jian; Li, Xingwen; Zhao, Jizhen; Zhang, Mei; Yuan, Yuan; Peng, Bodong

    2014-10-01

    Single wire explosions are widely used in understanding the early stages of z-pinch experiments. This paper presents a serial of experiments conducted on the pulse power generator with ˜1 kA peak current and ˜10 ns rising time in Xi'an Jiao Tong University. Polyimide coated aluminum wires and uncoated ones were tested under three different voltages to analyze the effect of insulating coating. Experimental results showed that insulating coating can increase the energy deposition 10%˜30% in aluminum wires by delaying the voltage collapse and raising the maximum load resistance. The substantial energy deposition resulted in about 20% faster expansion rates for coated wires. Experimental evidence that plasma channel shunts the current from the wire core was observed by streak camera and schlieren graphs. This paper also briefly discussed the influence of nonuniform coating on the morphology of wire expansion.

  9. Generalized-stacking-fault energy surface and dislocation properties of aluminum

    Microsoft Academic Search

    Gang Lu; Nicholas Kioussis; Vasily V. Bulatov; Efthimios Kaxiras

    2000-01-01

    We have employed the semidiscrete variational generalized Peierls-Nabarro model to study the dislocation properties of aluminum. The generalized-stacking-fault (GSF) energy surface entering the model is calculated by using first-principles density functional theory (DFT) and the embedded-atom method (EAM). Various core properties, including the core width, dissociation behavior, energetics, and Peierls stress for different dislocations have been investigated. The correlation between

  10. The structural response of clamped sandwich beams subjected to impact loading

    Microsoft Academic Search

    Zhihua Wang; Lin Jing; Jianguo Ning; Longmao Zhao

    2011-01-01

    The structural response of dynamically loaded monolithic and sandwich beams made of aluminum skins with different cores is determined by loading the end-clamped beams at mid-span with metal foam projectiles. The sandwich beams comprise aluminum honeycomb cores and closed-cell aluminum foam cores. Laser displacement transducer was used to measure the permanent transverse deflection of the back face mid-point of the

  11. Sound transmission loss of damped honeycomb sandwich Portia Peters and Steven Nutt

    E-print Network

    Southern California, University of

    the following panel/beam designs: glass-epoxy skin with Nomex® core, glass-epoxy skin with Kevlar® core, carbon relationship between TL and loss factor for subsonic panels, and (4) Both Kevlar® and Nomex® cores show insulation is called for without strong mechanical properties. Furthermore, the results of the Kevlar® core

  12. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...25 2012-07-01 2012-07-01 false Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement... Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary...

  13. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...23 2010-07-01 2010-07-01 false Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement... Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary...

  14. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...25 2013-07-01 2013-07-01 false Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement... Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary...

  15. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...24 2011-07-01 2011-07-01 false Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement... Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary...

  16. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...24 2014-07-01 2014-07-01 false Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement... Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary...

  17. 46 CFR 148.255 - Ferrosilicon, aluminum ferrosilicon, and aluminum silicon containing more than 30% but less than...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Ferrosilicon, aluminum ferrosilicon, and aluminum silicon containing more than 30% but less than 90% silicon. 148.255 Section 148.255 Shipping...Ferrosilicon, aluminum ferrosilicon, and aluminum silicon containing more than 30% but less than...

  18. Fabrication of mussel-inspired highly adhesive honeycomb films containing catechol groups and their applications for substrate-independent porous templates.

    PubMed

    Saito, Yuta; Kawano, Takahito; Shimomura, Masatsugu; Yabu, Hiroshi

    2013-04-25

    Porous surface patterns are used in a wide variety of practical applications. Honeycomb-patterned porous polymer films are good templates for preparing porous surfaces due to their simple fabrication and the arrangement of pores on the surface. Catechol groups include in adhesive protein of mussels have attracted much attention due to their highly and substrate-independent adhesive properties. In this paper, highly and substrate-independent adhesive honeycomb-patterned porous polymer films are prepared by using amphiphilic copolymer having catechol moieties. Furthermore, porous surface patterns are transferred on various organic or inorganic substrates by wet etching with using adhesive honeycomb films as templates. PMID:23508892

  19. Micro Joining of Aluminum Graphite Composites

    E-print Network

    Velamati, Manasa

    2012-07-16

    Advanced aluminum graphite composites have unique thermal properties due to opposing coefficients of thermal expansion of aluminum and graphite. The thermal and mechanical properties of such composites are anisotropic due to directional properties...

  20. Recycling of aluminum salt cake

    SciTech Connect

    Jody, B.J.; Daniels, E.J.; Bonsignore, P.V.; Karvelas, D.E.

    1991-12-01

    The secondary aluminum industry generates more than 110 {times} 10{sup 3} tons of salt-cake waste every year. This waste stream contains about 3--5% aluminum, 15--30% aluminum oxide, 30--40% sodium chloride, and 20--30% potassium chloride. As much as 50% of the content of this waste is combined salt (sodium and potassium chlorides). Salt-cake waste is currently disposed of in conventional landfills. In addition, over 50 {times} 10{sup 3} tons of black dross that is not economical to reprocess a rotary furnace for aluminum recovery ends up in landfills. The composition of the dross is similar to that of salt cake, except that it contains higher concentrations of aluminum (up to 20%) and correspondingly lower amounts of salts. Because of the high solubility of the salts in water, these residues, when put in landfills, represent a potential source of pollution to surface-water and groundwater supplies. The increasing number of environmental regulations on the generation and disposal of industrial wastes are likely to restrict the disposal of these salt-containing wastes in conventional landfills. Processes exist that employ the dissolution and recovery of the salts from the waste stream. These wet-processing methods are economical only when the aluminum concentration in that waste exceeds about 10%. Argonne National Laboratory (ANL) conducted a study in which existing technologies were reviewed and new concepts that are potentially more cost-effective than existing processes were developed and evaluated. These include freeze crystallization, solvent/antisolvent extraction, common-ion effect, high-pressure/high-temperature process, and capillary-effect systems. This paper presents some of the technical and economic results of the aforementioned ANL study.

  1. Nanotube Fabrication byNanotube Fabrication by Anodic Aluminum Oxide,Anodic Aluminum Oxide,

    E-print Network

    Rubloff, Gary W.

    Nanotube Fabrication byNanotube Fabrication by Anodic Aluminum Oxide,Anodic Aluminum Oxide, Self-regulating phenomena in materials science: Self-assembly of nanopores during anodic oxidation of aluminum (AAO) Self combined anodic aluminum oxide (AAO) nanostructures with atomic layer deposition (ALD) to fabricate

  2. Epidemic aluminum intoxication in hemodialysis patients traced to use of an aluminum pump

    Microsoft Academic Search

    Dale R Burwen; Steven M Olsen; Lee A Bland; Matthew J Arduino; Marie H Reid; William R Jarvis

    1995-01-01

    Epidemic aluminum intoxication in hemodialysis patients traced to use of an aluminum pump. This study was designed to identify the source, risk factors, and clinical consequences of an outbreak of aluminum intoxication in hemodialysis patients using case-control and cohort studies. In 1991, a dialysis center in Pennsylvania [Dialysis Center A (DCA)] identified a number of patients with elevated serum aluminum

  3. Laterally proximized aluminum tunnel junctions

    NASA Astrophysics Data System (ADS)

    Koski, J. V.; Peltonen, J. T.; Meschke, M.; Pekola, J. P.

    2011-05-01

    This letter presents experiments on junctions fabricated by a technique that enables the use of high-quality aluminum oxide tunnel barriers with normal metal electrodes at low temperatures. Inverse proximity effect is applied to diminish the superconductivity of an aluminum dot through a clean lateral connection to a normal metal electrode. To demonstrate the effectiveness of this method, fully normal-state single electron transistors (SETs) and normal metal-insulator-superconductor (NIS) junctions applying proximized Al junctions were fabricated. The transport characteristics of the junctions were similar to those obtained from standard theoretical models of regular SETs and NIS junctions.

  4. Aluminum-carbon composite electrode

    DOEpatents

    Farahmandi, C. Joseph (Auburn, AL); Dispennette, John M. (Auburn, AL)

    1998-07-07

    A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

  5. Aluminum-air battery crystallizer

    SciTech Connect

    Maimoni, A.

    1987-01-23

    A prototype crystallizer system for the aluminum-air battery operated reliably through simulated startup and shutdown cycles and met its design objectives. The crystallizer system allows for crystallization and removal of the aluminium hydroxide reaction product; it is required to allow steady-state and long-term operation of the aluminum-air battery. The system has to minimize volume and maintain low turbulence and shear to minimize secondary nucleation and energy consumption while enhancing agglomeration. A lamella crystallizer satisfies system constraints.

  6. Spiral order in the honeycomb iridate Li2IrO3

    NASA Astrophysics Data System (ADS)

    Reuther, Johannes; Thomale, Ronny; Rachel, Stephan

    2014-09-01

    The honeycomb iridates A2IrO3 (A = Na, Li) constitute promising candidate materials to realize the Heisenberg-Kitaev model (HKM) in nature, hosting unconventional magnetic as well as spin-liquid phases. Recent experiments suggest, however, that Li2IrO3 exhibits a magnetically ordered state of incommensurate spiral type which has not been identified in the HKM. We show that these findings can be understood in the context of an extended Heisenberg-Kitaev scenario satisfying all tentative experimental evidence: (i) the maximum of the magnetic susceptibility is located inside the first Brillouin zone, (ii) the Curie-Weiss temperature is negative relating to dominant antiferromagnetic fluctuations, and (iii) significant second-neighbor spin exchange is involved.

  7. Discovery of a honeycomb structure in the twisted plywood patterns of fibrous biological nanocomposite tissue

    NASA Astrophysics Data System (ADS)

    Raabe, D.; Romano, P.; Sachs, C.; Al-Sawalmih, A.; Brokmeier, H.-G.; Yi, S.-B.; Servos, G.; Hartwig, H. G.

    2005-09-01

    Electron microscopy and synchrotron Bragg diffraction were used for the investigation of the structure of the exoskeleton of the lobster Homarus americanus. The study reveals a pronounced microstructure hierarchy and a strong crystallographic and topological texture of the ?-chitin-protein network underlying the twisted plywood (Bouligand) structure. The results suggest that the classical picture of such structures must be refined. Instead of a smoothly misoriented stacking sequence of its constitutive nanofibrous chitin-protein planes, two major and two minor orientation branches of the fibers perpendicular to a common <0 2 0> crystallographic axis pointing towards the surface of the cuticle were found. This crystallographic texture confirms the microscopical observation that the chitin-protein arrays which form the structural subunits of plywood patterns assume the form of planar honeycombs.

  8. Strain-tunable band parameters of ZnO monolayer in graphene-like honeycomb structure

    NASA Astrophysics Data System (ADS)

    Behera, Harihar; Mukhopadhyay, Gautam

    2012-10-01

    We present ab initio calculations which show that the direct-band-gap, effective masses and Fermi velocities of charge carriers in ZnO monolayer (ML-ZnO) in graphene-like honeycomb structure are all tunable by application of in-plane homogeneous biaxial strain. Within our simulated strain limit of ±10%, the band gap remains direct and shows a strong non-linear variation with strain. Moreover, the average Fermi velocity of electrons in unstrained ML-ZnO is of the same order of magnitude as that in graphene. The results promise potential applications of ML-ZnO in mechatronics/straintronics and other nano-devices such as the nano-electromechanical systems (NEMS) and nano-optomechanical systems (NOMS).

  9. Zigzag order and phase competition in expanded Kitaev-Heisenberg model on honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Yao, Xiaoyan

    2015-07-01

    The Kitaev-Heisenberg model on the honeycomb lattice is investigated in two cases: (I) with the Kitaev interaction between the nearest neighbors, and (II) with the Kitaev interaction between the next nearest neighbors. In the full parameter range, the ground states are searched by Monte Carlo simulation and identified by evaluating the correlation functions. The energies of different phases are calculated and compared with the simulated result to show the phase competition. It is observed from both energy calculation and the density of states that the zigzag order shows a symmetric behavior to the stripy phase in the pure Kitaev-Heisenberg model. By considering more interactions in both cases, the energy of zigzag order can be reduced lower than the energies of other states. Thus the zigzag phase may be stabilized in more parameter region and even extended to the whole parameter range.

  10. Topological Fermi Liquids from Coulomb Interactions in the Doped Honeycomb Lattice

    SciTech Connect

    Castro, Eduardo V.; Grushin, Adolfo G.; Valenzuela, Belen; Vozmediano, Maria A. H.; Cortijo, Alberto; Juan, Fernando de [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid (Spain); Departamento de Fisica Teorica, Universidad Autonoma de Madrid, E-28049, Madrid (Spain); Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States)

    2011-09-02

    We propose a simple method for obtaining time reversal symmetry (T) broken phases in simple lattice models based on enlarging the unit cell. As an example we study the honeycomb lattice with nearest neighbor hopping and a local nearest neighbor Coulomb interaction V. We show that when the unit cell is enlarged to host six atoms that permits Kekule distortions, self-consistent currents spontaneously form creating nontrivial magnetic configurations with total zero flux at high electron densities. A very rich phase diagram is obtained within a variational mean field approach that includes metallic phases with broken time reversal symmetry (T). The predominant (T) breaking configuration is an anomalous Hall phase, a realization of a topological Fermi liquid.

  11. Nano-honeycomb structured transparent electrode for enhanced light extraction from organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Shi, Xiao-Bo; Qian, Min; Wang, Zhao-Kui; Liao, Liang-Sheng

    2015-06-01

    A universal nano-sphere lithography method has been developed to fabricate nano-structured transparent electrode, such as indium tin oxide (ITO), for light extraction from organic light-emitting diodes (OLEDs). Perforated SiO2 film made from a monolayer colloidal crystal of polystyrene spheres and tetraethyl orthosilicate sol-gel is used as a template. Ordered nano-honeycomb pits on the ITO electrode surface are obtained by chemical etching. The proposed method can be utilized to form large-area nano-structured ITO electrode. More than two folds' enhancement in both current efficiency and power efficiency has been achieved in a red phosphorescent OLED which was fabricated on the nano-structured ITO substrate.

  12. Critical surface of the Blume-Emery-Griffiths model on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Gwa, Leh-Hun; Wu, F. Y.

    1991-06-01

    We consider the Blume-Emergy-Griffiths (BEG) model on the honeycomb lattice and obtain a closed-form expression for the critical surface of second-order transitions. The BEG model is first formulated as a three-state vertex model. Using the fact that the BEG critical surface coincides with that of a general three-state vertex model, we construct critical surfaces by forming polynomial combinations of vertex weights that are invariant under an O(3) gauge transformation. We then carry out a finite-size analysis of the BEG model, and use data so obtained to determine coefficients appearing in the polynomial combination. This procedure leads to a closed-form expression of the critical surface which reproduces all numerical data accurately.

  13. Fermionic quantum critical point of spinless fermions on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Corboz, Philippe; Troyer, Matthias

    2014-10-01

    Spinless fermions on a honeycomb lattice provide a minimal realization of lattice Dirac fermions. Repulsive interactions between nearest neighbors drive a quantum phase transition from a Dirac semimetal to a charge-density-wave state through a fermionic quantum critical point, where the coupling of the Ising order parameter to the Dirac fermions at low energy drastically affects the quantum critical behavior. Encouraged by a recent discovery (Huffman and Chandrasekharan 2014 Phys. Rev. B 89 111101) of the absence of the fermion sign problem in this model, we study the fermionic quantum critical point using the continuous-time quantum Monte Carlo method with a worm-sampling technique. We estimate the transition point V/t=1.356(1) with the critical exponents ? =0.80(3) and ? =0.302(7). Compatible results for the transition point are also obtained with infinite projected entangled-pair states.

  14. Nine new phosphorene polymorphs with non-honeycomb structures: a much extended family.

    PubMed

    Wu, Menghao; Fu, Huahua; Zhou, Ling; Yao, Kailun; Zeng, Xiao Cheng

    2015-05-13

    We predict a new class of monolayer phosphorus allotropes, namely, ?-P, ?-P, ?-P, and ?-P. Distinctly different from the monolayer ?-P (black) and previously predicted ?-P (Phys. Rev. Lett. 2014, 112, 176802), ?-P, and ?-P (Phys. Rev. Lett. 2014, 113, 046804) with buckled honeycomb lattice, the new allotropes are composed of P4 square or P5 pentagon units that favor tricoordination for P atoms. The new four polymorphs, together with five additional hybrid polymorphs, greatly enrich the phosphorene structures, and their stabilities are confirmed by first-principles calculations. In particular, the ?-P is shown to be equally stable as the ?-P (black) and more stable than all previously reported phosphorene polymorphs. Prediction of nonvolatile ferroelastic switching and structural transformation among different polymorphs under strains points out their potential applications via strain engineering. PMID:25844524

  15. Growth of Si nanorods in honeycomb and hexagonal-closed-packed arrays using glancing angle deposition

    SciTech Connect

    Patzig, Christian; Rauschenbach, Bernd [Leibniz-Institut fuer Oberflaechenmodifizierung e.V., Permoserstrasse 15, 04318 Leipzig (Germany); Fuhrmann, Bodo; Leipner, Hartmut S. [Interdisziplinaeres Zentrum fuer Materialwissenschaften, Martin-Luther-Universitaet Halle, Heinrich-Damerow-Strasse 4, 06120 Halle (Germany)

    2008-01-15

    Regular arrays of Si nanorods with a circular cross section in hexagonal-closed-packed and triangular cross section in honeycomblike arrangements were grown using glancing angle deposition on Si(100) and fused silica substrates that were patterned with Au dots using self-assembled mono- and double layers of polystyrene nanospheres as an evaporation mask. The Au dots were used as an etching mask for the underlying silica substrates in a reactive ion beam etching process, which greatly enhanced the height of the seeding spaces for the subsequent glancing angle deposition. An elongated shadowing length l of the prepatterned nucleation sites and less growth of Si structures between the surface mounds could be achieved this way. Differences in form, height, and diameter of the Si nanorods grown on either hcp or honeycomb arrays are explained by purely geometrical arguments. Different seed heights and interseed distances are found to be the main reasons for the strong distinctions between the grown nanorod arrays.

  16. Quantum phases of the frustrated XY models on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Zhu, Zhenyue; White, Steven R.

    2014-12-01

    Searching for spin-liquid states has long been attracting both experimentalists and theorists. In this paper, we review recent density matrix renormalization group studies of the spin-½ XY model on the honeycomb lattice, with first-neighbor (J1 = 1) and frustrating second-neighbor (J2 > 0) interactions. For the intermediate frustration regime 0.22 ? J2 ? 0.36, there exists a surprising antiferromagnetic Ising phase, with ordered moments pointing along the z-axis, despite the absence of any SzSz interactions in the Hamiltonian. Surrounding this phase as a function of J2 are antiferromagnetic phases with the moments pointing in the xy-plane for small J2 and a close competition between an xy-plane magnetic collinear phase and a dimer phase for large values of J2. No spin-liquid phases was found in the XY model even with the third-neighbor (J3 > 0) interactions.

  17. Finite element analysis of an accordion-like honeycomb scaffold for cardiac tissue engineering

    PubMed Central

    Jean, Aurélie; Engelmayr, George C.

    2010-01-01

    Optimizing the function of tissue engineered cardiac muscle is becoming more feasible with the development of microfabricated scaffolds amenable to mathematical modeling. In the current study, the elastic behavior of a recently developed poly(glycerol sebacate) (PGS) accordion-like honeycomb (ALH) scaffold [Engelmayr et al., 2008. Nature Materials 7 (12), 1003–1010] was analyzed. Specifically, 2D finite element (FE) models of the ALH unit cell (periodic boundary conditions) and tessellations (kinematic uniform boundary conditions) were utilized to determine a representative volume element (RVE) and to retrospectively predict the elastic effective stiffnesses. An RVE of 90 ALH unit cells (?3:18×4:03mm) was found, indicating that previous experimental uni-axial test samples were mechanically representative. For ALH scaffolds microfabricated from PGS cured 7.5 h at 160 1°C, FE predicted effective stiffnesses in the two orthogonal material directions (0.081±0.012 and 0.033±0.005 MPa) matched published experimental data (0.083±0.004 and 0.031±0.002 MPa) within 2.4% and 6.4%. Of potential use as a design criterion, model predicted global strain amplifications were lower in ALH (0.54 and 0.34) versus rectangular honeycomb (1.19 and 0.74) scaffolds, appearing to be inversely correlated with previously measured strains-to-failure. Important in matching the anisotropic mechanical properties of native cardiac muscle, FE predicted ALH scaffolds with 50?m wide PGS struts to be maximally anisotropic. The FE model will thus be useful in designing future variants of the ALH pore geometry that simultaneously provide proper cardiac anisotropy and reduced stiffness to enhance heart cell-mediated contractility. PMID:20673666

  18. Acoustic emission analysis of full-scale honeycomb sandwich composite curved fuselage panels

    NASA Astrophysics Data System (ADS)

    Leone, Frank A., Jr.; Ozevin, Didem; Godinez, Valery; Mosinyi, Bao; Bakuckas, John G., Jr.; Awerbuch, Jonathan; Lau, Alan; Tan, Tein-Min

    2008-03-01

    Acoustic emission (AE) was monitored in notched full-scale honeycomb sandwich composite curved fuselage panels during loading. The purpose of the study was to evaluate the AE technique as a tool for detecting notch tip damage initiation and evaluating damage severity in such structures. This evaluation was a part of a more general study on the damage tolerance of six honeycomb sandwich composite curved panels, each containing a different damage scenario. The overall program objective was to investigate the effects of holes and notches on residual strength. The investigation was conducted using the Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility located at the Federal Aviation Administration William J. Hughes Technical Center, Atlantic City International Airport, NJ. This paper reports on the AE results recorded during the loading to failure of two selected panels. The results show that damage initiation at the tips of the notches, and its progression along the panel, could be detected and located. These AE results were correlated with the deformation and strain fields measured through strain photogrammetry, throughout loading, at the vicinity of these notches. This correlation aided in interpreting the AE results. While the fretting among the newly created fracture surfaces generated a large number of low-intensity AE signals, the high-intensity signals generated at high load levels provided a good measure for anticipating incipient fracture. Further, the AE results located internal disbonding caused during panel fabrication. The large number of low-intensity AE signals generated from the disbonded regions was associated with the fretting among the disbonded surfaces.

  19. NaOH-modified ceramic honeycomb with enhanced formaldehyde adsorption and removal performance.

    PubMed

    Yu, Jiaguo; Li, Xinyang; Xu, Zhihua; Xiao, Wei

    2013-09-01

    NaOH-modified ceramic honeycombs (Na-CH) were simply prepared by impregnating ceramic honeycombs (CH) into NaOH aqueous solution. It was clearly shown that the surface modification incurs higher specific surface area and smaller grain sizes of the CH without destruction of their integrity. Moreover, the introduced surface NaOH can trigger Cannizzaro disproportionation of surface-absorbed formaldehyde (HCHO) on Na-CH, resulting in catalytic transformation of HCHO into less-toxic formate and methoxy salts. The NaOH concentration during impregnating treatment has a great influence on HCHO adsorption and removal efficiency, while the impregnation time and temperature have little influence on the efficiency. When the CH was impregnated in 1 M NaOH aqueous solution for 0.5 h at room temperature, the HCHO removal efficiency at ambient temperature can reach about 80% with an initial HCHO concentration of 250 ppm. Moreover, the used Na-CH can be facilely regenerated via 1 min blow using a common electric hair dryer, with the generation of less toxic HCOOH and CH3OH and recovery of NaOH. Using such a mild, fast, and practical regeneration method, the regenerated Na-CH showed slight degradation in adsorption and removal capability toward HCHO. The enhanced performance of Na-CH obtained was attributed to the presence of NaOH and increase of specific surface area and surface hydroxyl groups. Considering no demand of noble metal for HCHO removal at ambient temperature and practical reusable capability of Na-CH under mild conditions, this work may provide some new insights into the design and fabrication of advanced catalysts for indoor air purification. PMID:23895134

  20. Chiral d-wave superconductivity on the honeycomb lattice close to the Mott state

    NASA Astrophysics Data System (ADS)

    Black-Schaffer, Annica M.; Wu, Wei; Le Hur, Karyn

    2014-08-01

    We study superconductivity on the honeycomb lattice close to the Mott state at half filling. Due to the sixfold lattice symmetry and disjoint Fermi surfaces at opposite momenta, we show that several different fully gapped superconducting states naturally exist on the honeycomb lattice, of which the chiral d +id'-wave state has previously been shown to appear when superconductivity appears close to the Mott state. Using renormalized mean-field theory to study the t-J model and quantum Monte Carlo calculations of the Hubbard-U model we show that the d +id'-wave state is the favored superconducting state for a wide range of on-site repulsion U, from the intermediate to the strong coupling regime. We also investigate the possibility of a mixed chirality d-wave state, where the overall chirality cancels. We find that a state with d +id'-wave symmetry in one valley but d -id'-wave symmetry in the other valley is not possible in the t-J model without reducing the translational symmetry, due to the zero-momentum and spin-singlet nature of the superconducting order parameter. Moreover, any extended unit cells result either in disjoint Dirac points, which cannot harbor this mixed chirality state, or the two valleys are degenerate at the zone center, where valley hybridization prevents different superconducting condensates. We also investigate extended unit cells where the overall chirality cancels in real space. For supercells containing up to eight sites, including the Kekulé distortion, we find no energetically favorable d-wave solution with an overall zero chirality within the restriction of the t-J model.

  1. Decontamination and reuse of ORGDP aluminum scrap

    Microsoft Academic Search

    A. L. Compere; W. L. Griffith; H. W. Hayden; D. F. Wilson

    1996-01-01

    The Gaseous Diffusion Plants, or GDPs, have significant amounts of a number of metals, including nickel, aluminum, copper, and steel. Aluminum was used extensively throughout the GDPs because of its excellent strength to weight ratios and good resistance to corrosion by UFâ. This report is concerned with the recycle of aluminum stator and rotor blades from axial compressors. Most of

  2. Aluminum: Principled Scenario Exploration through Minimality

    E-print Network

    Dougherty, Daniel J.

    Aluminum: Principled Scenario Exploration through Minimality Tim Nelson1, Salman Saghafi1, Daniel J. We present Aluminum, a modification of Alloy that presents only minimal scenarios: those that contain no more than is necessary. Aluminum lets users explore the scenario space by adding to scenarios

  3. ECONOMIC IMPACT OF CENTURY ALUMINUM OF

    E-print Network

    Mohaghegh, Shahab

    ECONOMIC IMPACT OF CENTURY ALUMINUM OF WEST VIRGINIA, INC. By Randall A represent those of the West Virginia University Board of Trustees. #12;2 OVERVIEW Century Aluminum of West Virginia, Inc. (Century) is located in Ravenswood, West Virginia and produces aluminum products

  4. Aluminum: Principled Scenario Exploration through Minimality

    E-print Network

    Krishnamurthi, Shriram

    Aluminum: Principled Scenario Exploration through Minimality Tim Nelson1, Salman Saghafi1, Daniel J Aluminum, a modification of Alloy that presents only minimal scenarios: those that contain no more than is necessary. Aluminum lets users explore the scenario space by adding to scenarios and backtracking. It also

  5. Aluminum in Superconducting Magnets Robert J. Weggel

    E-print Network

    McDonald, Kirk

    Aluminum in Superconducting Magnets Robert J. Weggel Magnet Optimization Research Engineering is aluminum, either ultrapure, as quenchstabilization matrix metal, and/or alloyed and coldworked and heat for magnets in which the stresses and strains are modest. The strongest aluminum alloy commercially available

  6. Aluminum--2004 5. Areferencethatincludesasectionmark()isfoundintheinternet

    E-print Network

    Aluminum--2004 5. Areferencethatincludesasectionmark(§)isfoundintheinternet ReferenceCitedsection. Aluminum ByPatriciaA.Plunkert Domestic survey data and tables were prepared by Benjamin S. Goff.S.GeologicalSurvey(uSGS)requestforproductiondata. CommercialDevelopmentCo.(CDC)ofSt.louis,mO, boughtKaiserAluminumCorp.'s200,000-metric-ton-per-year (t

  7. 76 FR 23490 - Aluminum tris (O

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-27

    ...aluminum tris (O-ethylphosphonate) on pineapple fodder and forage because they are not...aluminum tris (O-ethylphosphonate) on pineapple fodder and forage because they are...aluminum tris (O-ethylphosphonate) on pineapple fodder and forage because they...

  8. Aluminum in 2012 North American Light Vehicles

    NSDL National Science Digital Library

    2013-07-03

    This study was carried out by Ducker Worldwide and funded by The Aluminum Association to evaluate the aluminum content in 2012 model year vehicles and the projected aluminum content growth through 2025. To gather data and form projections, Ducker surveyed original equipment manufactures (OEMs) and The Aluminum Association to create a metallic materials database with 32,000 cells per light vehicle. Using their database and other information from OEMs, Ducker concluded in the 2012 model year the average weight of aluminum on light vehicles will be approximately 348lbs, 30% of hoods will be aluminum, and 50% of cast aluminum wheels will be sourced from China. To meet corporate average fuel economy (CAFE) standards in 2025 Ducker speculates vehicle aluminum content will grow by 80% (671lbs avg. truck and 451lbs avg. for cars), milled aluminum components will increase, 50% of hoods will be aluminum, and manifolds will be made from magnesium rather than aluminum. Based on this study’s conclusions, it’s clear that aluminum content in vehicles will continue to grow to meet CAFE standards by 2025. For more info on Ducker Worldwide, visit http://www.ducker.com/. Ducker has also performed studies for the Environmental Protection Agency (EPA) and the Department of Energy (DOE).

  9. MODELING OF ALUMINUM NANOPARTICLE FORMATION R. Schefflan

    E-print Network

    of the gaseous aluminum has solidified, a moment equation is employed to calculate the number of particles and data were collected so as to give direction to the modeling process. The lab-scale process is carried. At this point all of the aluminum has solidified into nanoparticles. The oxygen reacts with the surface aluminum

  10. Novel aqueous aluminum/sulfur batteries

    SciTech Connect

    Licht, S.; Peramunage, D. (Clark Univ., Worcester, MA (United States))

    1993-01-01

    Aluminum sulfur batteries based on concentrated polysulfide catholytes and an alkaline aluminum anode are introduced and investigated. The new battery is expressed by aluminum oxidation and aqueous sulfur reduction for an overall battery discharge consisting of 2Al + S[sub 4][sup 2[minus

  11. Core preservation with a laminated, heat-sealed package

    SciTech Connect

    Hunt, P.K.; Cobb, S.L.

    1988-12-01

    A core preservation package was developed to maintain the reservoir characteristics of core samples and consequently to improve the quality of data obtained through laboratory core analyses. The package is a heat-sealable plastic-aluminum laminate similar to those common in the food-packaging industry. The laminated core preservation package acts as an impermeable barrier to water vapor and gases, and is resistant to chemical alteration and degradation by core fluids. These performance characteristics result in effective core preservation by maintaining the fluid content of the core. Other advantages of the laminated package are that it is fast and simple to use and eliminates the cumbersome dip-coat step used in some core preservation methods.

  12. Recovering aluminum from aluminum dross in a DC electric-arc rotary furnace

    NASA Astrophysics Data System (ADS)

    Tzonev, Tz.; Lucheva, B.

    2007-11-01

    The recycling of aluminum scrap and dross yields significant economic and energy savings, as well environmental benefits. The recovery of aluminum depends on many factors. The aim of this work is to experimentally investigate aluminum recovery under different conditions. In this study, aluminum dross was processed in a direct-current electric-arc rotary furnace. The presence of crushing refractory bodies during processing was found to increase the degree of aluminum recovery by about ten percent.

  13. CHARACTERIZING AND MODELING FERRITE-CORE PROBES

    SciTech Connect

    Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H. [Victor Technologies LLC, Bloomington, IN 47401 (United States); Aldrin, John C. [Computational Tools, Gurnee, IL 60031 (United States)

    2010-02-22

    In this paper, we accurately and carefully characterize a ferrite-core probe that is widely used for aircraft inspections. The characterization starts with the development of a model that can be executed using the proprietary volume-integral code, VIC-3D(c), and then the model is fitted to measured multifrequency impedance data taken with the probe in freespace and over samples of a titanium alloy and aluminum. Excellent results are achieved, and will be discussed.

  14. Research on plasma core reactors

    NASA Technical Reports Server (NTRS)

    Jarvis, G. A.; Barton, D. M.; Helmick, H. H.; Bernard, W.; White, R. H.

    1976-01-01

    Experiments and theoretical studies are being conducted for NASA on critical assemblies with one-meter diameter by one-meter long low-density cores surrounded by a thick beryllium reflector. These assemblies make extensive use of existing nuclear propulsion reactor components, facilities, and instrumentation. Due to excessive porosity in the reflector, the initial critical mass was 19 kg U(93.2). Addition of a 17 cm thick by 89 cm diameter beryllium flux trap in the cavity reduced the critical mass to 7 kg when all the uranium was in the zone just outside the flux trap. A mockup aluminum UF6 container was placed inside the flux trap and fueled with uranium-graphite elements. Fission distributions and reactivity worths of fuel and structural materials were measured. Finally, an 85,000 cu cm aluminum canister in the central region was fueled with UF6 gas and fission density distributions determined. These results are to be used to guide the design of a prototype plasma core reactor which will test energy removal by optical radiation.

  15. Aluminum and its light alloys

    NASA Technical Reports Server (NTRS)

    Merica, Paul D

    1920-01-01

    Report is a summary of research work which has been done here and abroad on the constitution and mechanical properties of the various alloy systems with aluminum. The mechanical properties and compositions of commercial light alloys for casting, forging, or rolling, obtainable in this country are described.

  16. Reversible Twinning in Pure Aluminum

    Microsoft Academic Search

    B. Q. Li; M. L. Sui; E. Ma; S. X. Mao

    2009-01-01

    Twinning in metals is normally a permanent plastic deformation mechanism. Here we report reversible twinning in high stacking fault energy (SFE) aluminum. Twinning and spontaneous detwinning at the crack tip have been captured in situ during tensile straining under a transmission electron microscope. Both the in situ observation and the molecular dynamics simulations reveal a two-stage detwinning process. The high

  17. Alternating Current Corrosion of Aluminum

    Microsoft Academic Search

    William French

    1973-01-01

    A comprehensive study of ac corrosion of aluminum alloys has led to a proposed mechanism of attack based on local pH changes. A critical alternating current density of 0.5 ma\\/in2 has been defined below which no corrosion occurs. At higher current densities the corrosion is time dependent. Engineering design data is presented.

  18. Heat-dissipating aluminum wire

    NASA Technical Reports Server (NTRS)

    Doyle, J. D.; Stringer, E. J.

    1978-01-01

    Surface area, and consequently heat dissipation, is increased by using star-shaped, rather than round cross section, for aluminum wire. When used with modern high-temperature insulating materials, pointed-star wire is suitable for applications where low-cost light-weight wire is required.

  19. Solvent-Tuned Azido-Bridged Co2+ Layers: Square, Honeycomb, and Kagome Xin-Yi Wang, Lu Wang, Zhe-Ming Wang, and Song Gao*

    E-print Network

    Gao, Song

    Solvent-Tuned Azido-Bridged Co2+ Layers: Square, Honeycomb, and Kagome´ Xin-Yi Wang, Lu Wang, Zhe-Ming Wang, and Song Gao* College of Chemistry and Molecular Engineering, State Key Laboratory of Rare Earth

  20. Three-dimensional honeycomb-like networks of birnessite manganese oxide assembled by ultrathin two-dimensional nanosheets with enhanced Li-ion battery performances.

    PubMed

    Dang, Liyun; Wei, Chengzhen; Ma, Haifeng; Lu, Qingyi; Gao, Feng

    2015-04-24

    Three-dimensional (3D) honeycomb-like birnessite networks composed of ultrathin two-dimensional (2D) nanosheets were firstly synthesized through a facile and low-cost synthetic route. By using carbon microspheres as a template instead of graphene, hierarchical birnessite structures assembled by ultrathin nanosheets including york-shell and hollow structures were obtained besides the ultrathin birnessite nanosheets with a thickness of about 0.7 nm. By assembling carbon spheres into an ordered 3D array, novel 3D honeycomb-like birnessite structures assembled by ultrathin nanosheets were firstly prepared. When evaluated as an anode material for Li-ion batteries, the 3D honeycomb-like networks show enhanced electrochemical performances with high capacities, excellent cycling stability and good rate capability, which can be ascribed to the novel 3D honeycomb-like macroporous structure with a 3D inverse opal structure, well-ordered macropores, interconnected walls and a regular periodicity. PMID:25872988

  1. Schwinger boson mean field theories of spin liquid states on a honeycomb lattice: Projective symmetry group analysis and critical field theory

    E-print Network

    Wang, Fa

    Motivated by the recent numerical evidence [Z. Meng, T. Lang, S. Wessel, F. Assaad, and A. Muramatsu, Nature (London) 464, 847 (2010)] of a short-range resonating valence bond state in the honeycomb lattice Hubbard model, ...

  2. Paramagnetic ground states and field-driven N'eel order in S=3\\/2 Heisenberg antiferromagnets on a honeycomb lattice

    Microsoft Academic Search

    Ganesh Ramachandran; D. N. Sheng; Y. J. Kim; A. Paramekanti

    2011-01-01

    We study the spin-3\\/2 Heisenberg antiferromagnet on a honeycomb lattice with exchange interactions which frustrate N'eel order. Our motivation stems from the recent synthesis of Bi3Mn4O12(NO3), a spin-3\\/2 bilayer honeycomb lattice antiferromagnet which remains paramagnetic to the lowest temperature, but shows a field-induced N'eel transition. We use a combination of spin wave theory, exact diagonalization, and bond operator theory to

  3. Reactively Deposited Aluminum Oxide and Fluoropolymer Filled Aluminum Oxide Protective Coatings for Polymers

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Banks, Bruce A.; Hunt, Jason

    1995-01-01

    Reactive ion beam sputter deposition of aluminum simultaneous with low energy arrival of oxygen ions at the deposition surface enables the formation of highly transparent aluminum oxide films. Thick (12 200 A), adherent, low stress, reactively deposited aluminum oxide films were found to provide some abrasion resistance to polycarbonate substrates. The reactively deposited aluminum oxide films are also slightly more hydrophobic and more transmitting in the UV than aluminum oxide deposited from an aluminum oxide target. Simultaneous reactive sputter deposition of aluminum along with polytetrafluoroethylene (PTFE Teflon) produces fluoropolymer-filled aluminum oxide films which are lower in stress, about the same in transmittance, but more wetting than reactively deposited aluminum oxide films. Deposition properties, processes and potential applications for these coatings will be discussed.

  4. Generalized-stacking-fault energy surface and dislocation properties of aluminum

    NASA Astrophysics Data System (ADS)

    Lu, Gang; Kioussis, Nicholas; Bulatov, Vasily V.; Kaxiras, Efthimios

    2000-08-01

    We have employed the semidiscrete variational generalized Peierls-Nabarro model to study the dislocation properties of aluminum. The generalized-stacking-fault (GSF) energy surface entering the model is calculated by using first-principles density functional theory (DFT) and the embedded-atom method (EAM). Various core properties, including the core width, dissociation behavior, energetics, and Peierls stress for different dislocations have been investigated. The correlation between the core energetics and the Peierls stress with the dislocation character has been explored. Our results reveal a simple relationship between the Peierls stress and the ratio between the core width and the atomic spacing. The dependence of the core properties on the two methods for calculating the GSF energy (DFT vs EAM) has been examined. Although the EAM gives the general trend for various dislocation properties, it fails to predict the correct finer core structure, which in turn can affect the Peierls stress significantly (about one order of magnitude).

  5. Magnetic order in ? -RuCl3 : A honeycomb-lattice quantum magnet with strong spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Sears, J. A.; Songvilay, M.; Plumb, K. W.; Clancy, J. P.; Qiu, Y.; Zhao, Y.; Parshall, D.; Kim, Young-June

    2015-04-01

    We report magnetic and thermodynamic properties of single crystal ? -RuCl3 , in which the Ru3+(4 d5) ion is in its low spin state and forms a honeycomb lattice. Two features are observed in both magnetic susceptibility and specific heat data; a sharp peak at 7 K and a broad hump near 10-15 K. In addition, we observe a metamagnetic transition between 5 and 10 T. Our neutron diffraction study of single crystal samples confirms that the low temperature peak in the specific heat is associated with a magnetic order with unit cell doubling along the honeycomb (100) direction, which is consistent with zigzag order, one of the types of magnetic order predicted within the framework of the Kitaev-Heisenberg model.

  6. A New Decomposition System for Volatile Organic Compounds Using Combinations of Dielectric Barrier Discharges with Zeolite Honeycomb Sheets

    NASA Astrophysics Data System (ADS)

    Inoue, Koji; Furuki, Keimei; Okano, Hiroshi; Yamagata, Yukihiko; Muraoka, Katsunori

    A new decomposition system for volatile organic compounds (VOCs), based on dielectric barrier discharges combined with zeolite honeycomb sheets, has been developed. A discharge element was made of layered flat metal sheets covered with mica sheets separated by 2 mm, in which corrugated (honeycomb-shaped) ceramic sheets embedded with zeolites were inserted. This element was shown to satisfy the requirements of durability and flexibility to meet various sizes. Barrier discharges were investigated using this discharge element over wide ranges of operating conditions, in terms of the power consumption and decompositions of various types of VOCs. By selecting suitable operating scenarios, it was found that decomposition of more than 90 % of most VOCs were possible, at reasonable power consumption and without electrode contamination by decomposition products. Finally, areas of competitive applications of the present system against existing decomposition systems are also discussed.

  7. Optical fingerprints of Si honeycomb chains and atomic gold wires on the Si(111)-(5×2)-Au surface.

    PubMed

    Hogan, Conor; Ferraro, Elena; McAlinden, Niall; McGilp, John F

    2013-08-23

    The intensively studied Si(111)-(5×2)-Au surface is reexamined using reflectance anisotropy spectroscopy and density functional theory simulations. We identify distinctive spectral features relating directly to local structural motifs such as Si honeycomb chains and atomic gold wires that are commonly found on Au-reconstructed vicinal Si(111) surfaces. Optical signatures of chain dimerization, responsible for the observed (×2) periodicity, are identified. The optical response, together with STM simulations and first-principles total-energy calculations, exclude the new structure proposed very recently based on the reflection high-energy electron diffraction technique analysis of Abukawa and Nishigaya [Phys. Rev. Lett. 110, 036102 (2013)] and provide strong support for the Si honeycomb chain with the triple Au chain model of Erwin et al. [Phys. Rev. B 80, 155409 (2009)]. This is a promising approach for screening possible models of complex anisotropic surface structures. PMID:24010474

  8. Hydrophobic and high transparent honeycomb diamond-like carbon thin film fabricated by facile self-assembled nanosphere lithography

    NASA Astrophysics Data System (ADS)

    Peng, Kai-Yu; Wei, Da-Hua; Lin, Chii-Ruey; Yu, Yueh-Chung; Yao, Yeong-Der; Lin, Hong-Ming

    2014-01-01

    In this paper, we take advantage of a facile fabrication technique called self-assembled nanosphere lithography (SANSL) combining with proper two-step reactive ion etching (RIE) method and radio frequency (RF) sputtering deposition process for manufacturing honeycomb diamond-like carbon (DLC) thin film structures with hydrophobic and high transparent properties. It is found that the DLC thin films deposited on clean glass substrates at the RF power of 100 W with the surface roughness (Ra) of 2.08 nm and the ID/IG ratio of 1.96 are realized. With a fill-factor of 0.691, the honeycomb DLC patterned thin film shows the best transmittance performance of 87% in the wavelength of visible light, and the optimized contact angle measurement is ˜108°. Compared with the pure DLC thin film and original glass substrate, the hydrophobic property of the patterned DLC films is significantly improved by 80 and 160%, respectively.

  9. Parametric study of self-forming ZnO Nanowall network with honeycomb structure by Pulsed Laser Deposition

    NASA Astrophysics Data System (ADS)

    El Zein, B.; Boulfrad, S.; Jabbour, G. E.; Dogheche, E.

    2014-02-01

    The successful synthesis of catalyst free zinc oxide (ZnO) Nanowall networks with honeycomb like structure by Pulsed Laser Deposition (PLD) is demonstrated in this paper. The synthesis was conducted directly on Silicon (Si) (1 0 0) and Glass-ITO substrates without the intermediate of metal catalyst, template or chemical etching. Kinetic of growth and effects of gas pressure and substrate temperature were studied by depositing ZnO films on P type Si (1 0 0) substrates with different deposition parameters. The optimized growth parameters were found as: 10 mTorr oxygen pressure, 600 °C substrate temperature, and deposition duration equal or higher than 10 min. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Photoluminescence (PL) measurements were used to investigate structural, microstructural and optical properties of ZnO Nanowall networks produced. They exhibit a non-uniform size high quality honeycomb structure with low deep level defects.

  10. Crystal Structure of the Spin 1/2 Honeycomb-Lattice Antiferromagnet Cu2(pymca)3(ClO4)

    NASA Astrophysics Data System (ADS)

    Honda, Zentaro; Kodama, Takafumi; Kikukawa, Reo; Hagiwara, Masayuki; Kida, Takanori; Sakai, Masamichi; Fukuda, Takeshi; Fujihara, Takashi; Kamata, Norihiko

    2015-03-01

    Using X-ray diffraction techniques, we have studied the crystal structure of a copper polynuclear coordination polymer Cu2(pymca)3(ClO4) (pymca = pyrimidine-2-carboxylate), which is found to crystallize as a trigonal crystal system, space group P31m, with the lattice constants a = 9.5904(18) Å and c = 5.9000(11) Å, at temperature T = 150 K. Each pymca ligand connects to two Cu2+ ions, forming a honeycomb network in the ab plane. The T dependence of the magnetic susceptibility of Cu2(pymca)3(ClO4) shows a broad maximum near T = 26 K, indicating low-dimensional antiferromagnetic interactions. From the crystal structure and magnetic properties, we conclude that Cu2(pymca)3(ClO4) is a good realization of a spin-1/2 honeycomb lattice antiferromagnet.

  11. Oxidation of aluminum particles in the presence of water.

    PubMed

    Schoenitz, Mirko; Chen, Chi-Mon; Dreizin, Edward L

    2009-04-16

    Oxidation of spherical aluminum powder was investigated in mixed argon-oxygen-steam atmospheres by thermogravimetric measurements at heating rates between 1 and 20 K/min and up to 1100 degrees C. The observed oxidation behavior in the presence of steam differs markedly from oxidation in dry oxygen. Oxidation in steam is complete near 1000 degrees C vs 1500 degrees C in dry oxygen. Furthermore, in steam, a stepwise weight change is observed at the melting point of aluminum, while no such step can be distinguished in dry oxygen. The complete oxidation observed at a lower temperature in steam as compared to dry oxygen is explained by the stabilization of the gamma polymorph of the surface oxide in the presence of water so that a denser and slower growing alpha-alumina does not form until higher temperatures. Experiments in mixed oxygen/steam oxidizers showed that the size of the oxidation step observed upon aluminum melting only correlates with the concentration of steam in the atmosphere. This may be interpreted as the effect of transient porosity, the degree of which is controlled by the steam concentration, or the surface oxide stressed by the expanding melting metal core may behave as a semipermeable membrane where hydrous species have significantly higher diffusion rates than oxygen. A clear distinction cannot be drawn, and further research is warranted. Preliminary results on isoconversion processing of the oxidation kinetics are presented. PMID:19309144

  12. Metallography of pitted aluminum-clad, depleted uranium fuel

    SciTech Connect

    Nelson, D.Z.; Howell, J.P.

    1994-12-01

    The storage of aluminum-clad fuel and target materials in the L-Disassembly Basin at the Savannah River Site for more than 5 years has resulted in extensive pitting corrosion of these materials. In many cases the pitting corrosion of the aluminum clad has penetrated in the uranium metal core, resulting in the release of plutonium, uranium, cesium-137, and other fission product activity to the basin water. In an effort to characterize the extent of corrosion of the Mark 31A target slugs, two unirradiated slug assemblies were removed from basin storage and sent to the Savannah River Technology Center for evaluation. This paper presents the results of the metallography and photographic documentation of this evaluation. The metallography confirmed that pitting depths varied, with the deepest pit found to be about 0.12 inches (3.05 nun). Less than 2% of the aluminum cladding was found to be breached resulting in less than 5% of the uranium surface area being affected by corrosion. The overall integrity of the target slug remained intact.

  13. Dark-field illuminated fiber bundle endoscopy with iterative l1-min image reconstruction for honeycomb pattern removal

    NASA Astrophysics Data System (ADS)

    Liu, Xuan; Zhang, Lijun; Kirby, Mitchell; Raj, Divyaansh; Qi, Shaohai; Zhao, Feng

    2015-03-01

    In this study, we developed a dark-field illuminated reflectance fiber-optic microscope (DRFM) along with an algorithm for l1-norm minimization of fiber bundle image to provide intrinsic endoscopic imaging with cellular resolution. To suppress specular reflection from fiber bundle facets, we adopted a dark-field configuration. To remove the honeycomb pattern of fiber bundle while preserve image resolution and contrast, we chose to minimize the image l1 norm using iterative shrinkage thresholding (IST) algorithm.

  14. Evaluation of the manufacture of sound absorbent sandwich plank made of PET\\/TPU honeycomb grid\\/PU foam

    Microsoft Academic Search

    Jia-Horng Lin; Chin-Mei Lin; Chao-Chiung Huang; Chia-Chang Lin; Chien-Teng Hsieh; Yu-Chen Liao

    2011-01-01

    In this study, the sandwich plank consisted of 7D polyethylene teraphthalate (PET), thermoplastic polyurethane (TPU) honeycomb grid, and polyurethane (PU) foam; 7D PET and 4D low melting polyester fibers were needle-punched and thermal-treated so as to form the PET nonwoven layer. The PU foam was foamed with a different density in the mold so as to form the PU foam

  15. Direct Growth of Hydroxy Cupric Phosphate Heptahydrate Monocrystal with HoneycombLike Porous Structures on Copper Surface Mimicking Lotus Leaf

    Microsoft Academic Search

    Xin Hua Chen; Guang Bin Yang; Ling Hao Kong; Dong Dong; Lai Gui Yu; Jian Min Chen; Ping Yu Zhang

    2009-01-01

    Superhydrophobic surfaces were prepared on copper foils via a facile assistant surface oxidation technology and subsequent chemical modification with low free energy materials. The three-dimensional (3D) honeycomb-like porous structures made up of nanoslices of hydroxy cupric phosphate heptahydrate (Cu8(PO3OH)2(PO4)4 · 7H2O) single crystals were constructed by immersing copper foil in an aqueous solution of phosphoric acid and hydrogen peroxide. The

  16. Pulmonary fibrosis in aluminum oxide workers. Investigation of nine workers, with pathologic examination and microanalysis in three of them

    SciTech Connect

    Jederlinic, P.J.; Abraham, J.L.; Churg, A.; Himmelstein, J.S.; Epler, G.R.; Gaensler, E.A. (Univ. of Massachusetts Medical Center, Worcester (USA))

    1990-11-01

    Epidemiologic surveys have indicated an excess of nonmalignant respiratory disease in workers exposed to aluminum oxide (Al2O3) during abrasives production. However, clinical, roentgenographic, histologic, and microanalytic description of these workers are lacking. This is a report of nine Al2O3-exposed workers with abnormal chest roentgenograms (profusion greater than or equal to 1/0, ILO/UC) from a plant engaged in the production of Al2O3 abrasives from alundum ore. Mean duration of exposure was 25 yr, and time since first exposure was 28 yr. in a subgroup of three, the severity of symptoms, reduction in the forced vital capacity (67% predicted) and diffusing capacity (51% predicted), and progressive roentgenographic changes (profusion greater than or equal to 2/2) prompted open lung biopsy. Lung tissue was analyzed by scanning electron microscopy and electron microprobe analysis. In each of the three biopsies, interstitial fibrosis with honeycombing was seen on routine section. In one biopsy, silica and asbestos fiber counts were at the low end of the range seen with silicosis and asbestosis; however, the absence of asbestos bodies and silicotic nodules suggested that the fibrosis was due to another cause. Metals occurred in amounts several orders of magnitude above background, and the majority was aluminum as Al2O3 and aluminum alloys. The findings in these nine workers suggests a common exposure as the possible cause. The nonspecific pathologic findings, absence of asbestos bodies and silicotic nodules, and the striking number of aluminum-containing particles suggest that Al2O3 is that common exposure. The possibility of mixed dust fibrosis should also be considered.

  17. Debonding and Kinking in Foam-Core Sandwich Beams

    Microsoft Academic Search

    D. A. Zacharopoulos; V. D. Balopoulos; Z. S. Metaxa; P. A. Kalaitzidis; E. E. Gdoutos

    In this work we consider the effects of debonding in a double cantilever beam (DCB) specimen of aluminum faces and PVC-foam core (Divinycel H, see [DIAB International AB, Divinycell Grade H Technical Manual, Sweden, 2003.]), as shown in Figure 1 below. The configuration follows the one proposed by Prasad and Carlsson [5], which is similar to the standard ASTM D5528

  18. The Acoustic Influence of Cell Depth on the Rotordynamic Characteristics of Smooth-Rotor/Honeycomb-Stator Annular Gas Seals

    NASA Technical Reports Server (NTRS)

    Childs, Dara W.

    1996-01-01

    A two-control volume is employed for honeycomb-stator/smooth-rotor seals, with a conventional control-volume used for the through flow and a 'capacitance accumulator' model for the honeycomb cells. The control volume for the honeycomb cells is shown to cause a dramatic reduction in the effective acoustic velocity of the main flow, dropping the lowest acoustic frequency into the frequency range of interest for rotordynamics. In these circumstances, the impedance functions for the seals can not be modeled with conventional (frequency-independent) stiffness, damping, and mass coefficients. More general transfer functions are required to account for the reaction forces, and calculated here as a lead-lag term for the direct force function and a lag term for the cross-coupled function. These first order functions are simple compared to transfer functions for magnetic bearings or foundations, For synchronous response to imbalance, they can be approximated by running-speed-dependent stiffness and damping coefficients in conventional rotordynamic codes. Correct predictions for stability and transient response will require more general algorithms, pressumably using a state-space format.

  19. Numerical and Experimental Investigation for Assessing the High Strain Rate Response of Nickel Based Multi-Layered Honeycomb Sandwiches

    NASA Astrophysics Data System (ADS)

    Yang, Z. Q.; Pang, B. J.; Wang, L. W.

    2009-12-01

    The mechanical behaviors of a multi-layered nickel based honeycomb sandwich at quasi-static and high strain rate ranging from 800/s-6500/s were determined by a universal Instron and uniaxial dynamic compression SHPB experiment respectively. The results of experiment showed strain rate sensitivity at low strain rate portion (0-800/s) while by increasing the strain rate (3400/s-6500/s); the samples no longer showed noticeable rate sensitivity. Dynamic strain-stress curves showed clearly initial peak strength, flat flow potion and totally compressed ascending part process while a littler peak was appeared during the flat flow portion. Different folding process can be found during dynamic compression for one and two layered honeycomb cells by high speed camera. A numerical model was developed using LS-DYNA software, for investigating the different deformation modes under various strain rates. A bi-linear elastic-plastic constitutive model was utilized to simulate plastic deformation and in-stability status of multi-layered nickel based honeycomb under dynamic compression. In this work, different finite element models were used to investigate dynamic crushing strength as a function of cell wall thickness and the number of sandwich layers.

  20. CaMn2Sb2: Spin Waves Near a Tricritical Point of the Antiferromagnetic Honeycomb Lattice

    NASA Astrophysics Data System (ADS)

    McNally, Daniel; Simonson, Jack; Kistner-Morris, Jed; Smith, Greg; Hassinger, Julian; Debeer-Schmidt, Lisa; Kolesnikov, Alexander; Aronson, Meigan

    2015-03-01

    The classical Heisenberg model for a honeycomb lattice of spins predicts at least three tricritical points, where three different long range ordered magnetic phases co-exist, depending on the relative strength of the nearest and next-nearest exchange interactions J1,2. We performed inelastic neutron scattering at T = 5 K<honeycomb lattice. Spin wave excitations were observed up to E ~ 24 meV and these data were fit to the spin wave dispersion expected from the classical Heisenberg model to determine the individual exchange interactions SJ1 = 8.22 +/- 0.23 meV, SJ2 = 1.29 +/- 0.09 meV, SJc = -0.56 +/- 0.04 meV, where Jc is the exchange interaction between honeycomb planes. The quantum fluctuations resulting from proximity to the tricritical point at J2/J1 = 1/6 are responsible for the relatively low ordering temperature of CaMn2Sb2 , TN = 85 K, much reduced from the mean field ordering temperature TMFT = 2zJ1S(S+1)/3kB = 560 K. We acknowledge the Office of the Assistant Secretary of Defense for Research and Engineering for providing the NSSEFF funds that supported this research.

  1. Recycling of aluminum matrix composites

    Microsoft Academic Search

    Yoshinori Nishida; Norihisa Izawa; Yukio Kuramasu

    1999-01-01

    Separation of matrix metals in composites was tried on alumina short fiber-reinforced aluminum and 6061 alloy composites and\\u000a SiC whisker-reinforced 6061 alloy composite for recycling. It is possible to separate molten matrix metals from fibers in\\u000a the composites using fluxes that are used for melt treatment to remove inclusions. About 50 vol pct of the matrix metals was\\u000a separated from

  2. Recycling of aluminum matric composites

    Microsoft Academic Search

    Yoshinori Nishida; Norihisa Izawa; Yukio Kuramasu

    1999-01-01

    Separation of matrix metals in composites was tried on alumina short fiber-reinforced aluminum and 6061 alloy composites and\\u000a SiC whisker-reinforced 6061 alloy composite for recycling. It is possible to separate molten matrix metals from fibers in\\u000a the composites using fluxes that are used for melt treatment to remove inclusions. About 50 vol pct of the matrix metals was\\u000a separated from

  3. Electrically Conductive Anodized Aluminum Surfaces

    NASA Technical Reports Server (NTRS)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to < or = 10(exp 9) Omega-cm. The present treatment does this. The treatment is a direct electrodeposition process in which the outer anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In comparison with these competing finishes, the present nanocomposite finishes are expected to cost 50 to 20 percent less and to last longer.

  4. Aluminum geochemistry in peatland waters

    Microsoft Academic Search

    E. H. Helmer; N. R. Urban; S. J. Eisenreich

    1990-01-01

    The chemical speciation of aluminum was examined in surface water samples from Sphagnum peatlands in north-central Minnesota, from peatlands along the Canadian east coast, and from bogs in the Pennine Mountain area of England. In highly organic ([DOC]˜ 50 mg L-1 ), low pH waters, 80–90% of total dissolved Al was complexed with organic matter (OM), while in waters with

  5. Purification technology of molten aluminum

    Microsoft Academic Search

    Bao-de Sun; Wen-jiang Ding; Da Shu; Yao-he Zhou

    2004-01-01

    Various purification methods were explored to eliminate the dissolved hydrogen and nonmetallic inclusions from molten aluminum\\u000a alloys. A novel rotating impeller head with self-oscillation nozzles or an electromagnetic valve in the gas circuit was used\\u000a to produce pulse gas currents for the rotary impeller degassing method. Water simulation results show that the size of gas\\u000a bubbles can be decreased by

  6. Microbial corrosion of aluminum alloy.

    PubMed

    Yang, S S; Chen, C Y; Wei, C B; Lin, Y T

    1996-11-01

    Several microbes were isolated from the contaminated fuel-oil in Taiwan and the microbial corrosion of aluminum alloy A356-T6 was tested by MIL-STD-810E test method. Penicillium sp. AM-F5 and Cladosporium resinac ATCC 22712 had significant adsorption and pitting on the surface of aluminum alloy, Pseudomonas acruginosa AM-B5 had weak adsorption and some precipitation in the bottom, and Candida sp. AM-Y1 had the less adsorption and few cavities formation on the surface. pH of the aqueous phase decreased 0.3 to 0.7 unit for 4 months of incubation. The corrosion of aluminum alloy was very significant in the cultures of Penicillium sp. AM-F2, Penicillium sp. AM-F5 and C. resinac ATCC 22712. The major metabolites in the aqueous phase with the inoculation of C. resinac were citric acid and oxalic acid, while succinic acid and fumaric acid were the minors. PMID:10592801

  7. Aluminum-lithium target behavior

    SciTech Connect

    McDonell, W.R.

    1989-10-01

    Information on physical properties and irradiation behavior of aluminum-lithium target alloys employed for the production of tritium in Savannah River reactors has been reviewed to support development of technology for the New Production Reactor (NPR). Phase compositions and microstructures, thermal conductivity, mechanical properties, and constituent diffusion phenomena of the alloys, established in prior site studies, are presented. Irradiation behavior, including distributions of product tritium and helium and related exposure limits due to swelling and cracking of the target alloys is discussed, along with gas release processes occurring during subsequent product recovery operations. The property review supports designation of the aluminum-lithium alloys as ideally well-suited target materials for low-temperature, tritium-producing reactors, demonstrated over 35 years of Savannah River reactor operation. Low temperature irradiation and reaction with lithium in the alloy promotes tritium retention during reactor exposure, and the aluminum provides a matrix from which the product is readily recovered on heating following irradiation. 33 refs., 26 figs., 8 tabs.

  8. Aluminum Waste Reaction Indicators in a Municipal Solid Waste Landfill

    E-print Network

    Aluminum Waste Reaction Indicators in a Municipal Solid Waste Landfill Timothy D. Stark, F.ASCE1 landfills may contain aluminum from residential and commercial solid waste, industrial waste, and aluminum pro- duction wastes. Some aluminum-bearing waste materials, particularly aluminum production wastes

  9. ALUMINUM--1997 5.1 By Patricia A. Plunkert

    E-print Network

    ALUMINUM--1997 5.1 ALUMINUM By Patricia A. Plunkert Domestic primary aluminum production increased slightly in 1997 to just over 3.6 million metric tons. Thirteen companies operated 22 primary aluminum was estimated to be $6.1 billion. Aluminum recovered from purchased scrap increased to almost 3.7 million tons

  10. Excess Dietary Aluminum Increases Drosophila’sRate of Aging

    Microsoft Academic Search

    Harold R. Massie; Trevor R. Williams; Valerie R. Aiello

    1985-01-01

    Aluminum concentrations in the whole organism increased during development and aging of Drosophila melanogaster. The amount of aluminum in the flies was also reflected by the dietary content of aluminum. Additional dietary aluminum, in the form of aluminum salts, decreased the life span by as much as 20%. A significant reduction in life span was found for 1 × 10-4M

  11. Lightweight Composite Intertank Structure

    NASA Technical Reports Server (NTRS)

    Mehle, Greg V.

    1995-01-01

    Report presents results of study for proposed lightweight composite material alternative to present semimonocoque aluminum intertank structure for advanced launch vehicles. Proposed structure integrated assembly of sandwich panels made of laminated epoxy-matrix/carbon-fiber skins, and aluminum honeycomb core.

  12. Constructing honeycomb micropatterns on nonplanar substrates with high glass transition temperature polymers.

    PubMed

    Ding, Jianyun; Gong, Jianliang; Bai, Hua; Li, Lei; Zhong, Yawen; Ma, Zhi; Svrcek, Vladimir

    2012-08-15

    In Qiao's previous report, only star polymers with T(g) (glass transition temperature) below 48°C were found forming homogeneous honeycomb coatings on the nonplanar substrates. The polymers with high T(g) are believed not able to duplicate nonplanar substrate due to their brittleness. This article presents a comprehensive study on the construction of macroporous polymeric films on various nonplanar substrates with static breath figure (BF) technique, using linear polymers with high T(g). Two kinds of linear polymers with high T(g), polystyrene-b-poly(acrylic acid) and polystyrene without polar end groups, are employed to prepare 3-dimensional macroporous films on different nonplanar substrates. Scanning electronic microscopy views on the side wall in addition to views in-plane prove that polymer films with BF array perfectly replicated the surface features of these substrates. The formation processes of macropores on these substrates are analyzed in detail, and it demonstrates that neither molecular topography nor T(g) of polymers is the critical factor contouring nonplanar substrate. A new hypothesis involving polymer plasticization and conformation during the solvent evaporation is formulated. PMID:22677439

  13. The Critical Fugacity for Surface Adsorption of Self-Avoiding Walks on the Honeycomb Lattice is

    NASA Astrophysics Data System (ADS)

    Beaton, Nicholas R.; Bousquet-Mélou, Mireille; de Gier, Jan; Duminil-Copin, Hugo; Guttmann, Anthony J.

    2014-03-01

    In 2010, Duminil-Copin and Smirnov proved a long-standing conjecture of Nienhuis, made in 1982, that the growth constant of self-avoiding walks on the hexagonal (a.k.a. honeycomb) lattice is . A key identity used in that proof was later generalised by Smirnov so as to apply to a general O( n) loop model with (the case n = 0 corresponding to self-avoiding walks). We modify this model by restricting to a half-plane and introducing a surface fugacity y associated with boundary sites (also called surface sites), and obtain a generalisation of Smirnov's identity. The critical value of the surface fugacity was conjectured by Batchelor and Yung in 1995 to be . This value plays a crucial role in our generalized identity, just as the value of the growth constant did in Smirnov's identity. For the case n = 0, corresponding to self-avoiding walks interacting with a surface, we prove the conjectured value of the critical surface fugacity. A crucial part of the proof involves demonstrating that the generating function of self-avoiding bridges of height T, taken at its critical point 1/ ?, tends to 0 as T increases, as predicted from SLE theory.

  14. High temperature testing of TRUPACT-I materials: Kevlar, honeycomb, rigid polyurethane foam

    SciTech Connect

    Hudson, M.L.

    1985-12-01

    When the Transuranic Package Transporter Model-I (TRUPACT-I) failed to afford sufficient containment after a 35-minute JP-4 fueled open-pool fire, component tests were conducted, in conjunction with analyses, to guide and assess the redesign of TRUPACT-I. Since materials which change phase or combust are difficult to numerically analyze, the component tests determined the behavior of these materials in TRUPACT-I. The component tests approximated the behavior of Kevlar (registered trademark of DuPont), metal honeycomb, and rigid polyurethane foam, as they appear in TRUPACT-I, in an open-pool fire environment. Six series of tests were performed at Sandia's Radiant Heat Facility and one test at the wind-shielded fire test facility (LAARC Chimney). Each test facility was controlled to yield temperatures or heat fluxes equivalent to those measured in the TRUPACT-I, Unit 0, open-pool fire. This extensive series of component tests (34 runs total) provided information on the high-temperature behavior of unique materials which was not previously available or otherwise attainable. The component tests were a timely and cost-effective means of providing the data for the TRUPACT-I redesign.

  15. Origin of the Giant Honeycomb Network of Quinones on Cu(111)

    NASA Astrophysics Data System (ADS)

    Einstein, T. L.; Kim, Kwangmoo; Wyrick, Jon; Cheng, Zhihai; Bartels, Ludwig; Berland, Kristian; Hyldgaard, Per

    2011-03-01

    We discuss the factors that lead to the amazing regular giant honeycomb network formed by quinones on Cu(111). Using a related lattice gas model with many characteristic energies, we can reproduce many experimental features. These models require a long-range attraction, which can be attributed to indirect interactions mediated by the Shockley surface state of Cu(111). However, Wyrick's preceding talk gave evidence that the network self-selects for the size of the pore rather than for the periodicity of the superstructure, suggesting that confined states are the key ingredient. We discuss this phenomenon in terms of the magic numbers of 2D quantum dots. We also report calculations of the effects of anthraquinones (AQ) in modifying the surface states by considering a superlattice of AQ chains with various separations. We discuss implications of these results for tuning the electronic states and, thence, superstructures. Supported by (TLE) NSF CHE 07-50334 & UMD MRSEC DMR 05-20471, (JW & LB) NSF CHE NSF CHE 07-49949, (KB & PH) Swedish Vetenskapsrådet VR 621-2008-4346.

  16. Electronic and magnetic properties of honeycomb transition metal monolayers: first-principles insights.

    PubMed

    Li, Xinru; Dai, Ying; Ma, Yandong; Huang, Baibiao

    2014-07-14

    p-Electron-based monolayer materials have dominated the research of Dirac fermions since the first exfoliation of graphene. In the present work, the electronic and magnetic properties of d-electron-based Dirac systems are studied by combining first-principles with mean field theory and Monte Carlo approaches. From first-principles calculations, we demonstrate that transition-metal (TM) monolayers (TM = Ti, Zr, Hf, V, Nb, or Ta), d-electron-based materials, could also hold Dirac cones and not only p-electron-based materials as known before. This may shed light on the breakthrough of new nanomaterials with d-type Dirac points. Moreover, the carrier mobility near the Dirac points of these materials can be tuned regularly by isotropic strains from -5% to 5%, without breaking the Dirac cones. However, the Dirac points would disappear under anisotropic strains, indicating that a rigorous honeycomb lattice may be the main precondition for Dirac points in TM-monolayers. Furthermore, some TM-monolayers (TM = Ti, Zr, or Hf) exhibit ferromagnetic couplings simultaneously. In addition, by mean field theory and Monte Carlo methods, it is found that Curie temperatures of TM-monolayers can be higher than 580 K even to 1180 K. Our findings significantly expand the Dirac systems. PMID:24879520

  17. Rigorous calculations of non-Abelian statistics in the Kitaev honeycomb model

    NASA Astrophysics Data System (ADS)

    Tuna Bolukbasi, Ahmet; Vala, Jiri

    2012-04-01

    We develop a rigorous and highly accurate technique for the calculation of the Berry phase in systems with a quadratic Hamiltonian within the context of the Kitaev honeycomb lattice model. The method is based on the recently found solution of the model that uses the Jordan-Wigner-type fermionization in an exact effective spin-hardcore boson representation. We specifically simulate the braiding of two non-Abelian vortices (anyons) in a four-vortex system characterized by a twofold degenerate ground state. The result of the braiding is the non-Abelian Berry matrix, which is in excellent agreement with the predictions of the effective field theory. The most precise results of our simulation are characterized by an error of the order of 10-5 or lower. We observe exponential decay of the error with the distance between vortices, studied in the range of one to nine plaquettes. We also study its correlation with the involved energy gaps and provide a preliminary analysis of the relevant adiabaticity conditions. The work allows one to investigate the Berry phase in other lattice models including the Yao-Kivelson model and particularly the square-octagon model. It also opens up the possibility of studying the Berry phase under non-adiabatic and other effects that may constitute important sources of errors in topological quantum computation.

  18. Adsorption and desorption characteristics of semiconductor volatile organic compounds on the thermal swing honeycomb zeolite concentrator.

    PubMed

    Chang, Feng-Tang; Lin, Yu-Chih; Bai, Hsunling; Pei, Bau-Shei

    2003-11-01

    The use of a honeycomb zeolite concentrator and an oxidation process is one of the most popular methods demonstrated to control volatile organic compound (VOCs) emissions from waste gases in semiconductor manufacturing plants. This study attempts to characterize the performance of a concentrator in terms of the removal efficiencies of semiconductor VOCs (isopropyl alcohol [IPA], acetone, propylene glycol methyl ether [PGME], and propylene glycol monomethyl ether acetate [PGMEA]) under several parameters that govern the actual operations. Experimental results indicated that at inlet temperatures of under 40 degrees C and a relative humidity of under 80%, the removal efficiency of a zeolite concentrator can be maintained well over 90%. The optimal rotation speed of the concentrator is between 3 and 4.5 rph in this study. The optimal rotation speed increases with the VOCs inlet concentration. Furthermore, reducing the concentration ratio helps to increase the removal efficiency, but it also increases the incineration cost. With reference to competitive adsorption, PGMEA and PGME are more easily adsorbed on a zeolite concentrator than are IPA and acetone because of their high boiling points and molecular weights. PMID:14649758

  19. Honeycomb lattice with multiorbital structure: Topological and quantum anomalous Hall insulators with large gaps

    NASA Astrophysics Data System (ADS)

    Zhang, Gu-Feng; Li, Yi; Wu, Congjun

    2015-03-01

    We construct a minimal four-band model for the two-dimensional topological insulators and quantum anomalous Hall insulators based on the px- and py-orbital bands in the honeycomb lattice. The multiorbital structure allows the atomic spin-orbit coupling which lifts the degeneracy between two sets of on-site Kramers doublets jz = +/-3/2 and jz = +/-1/2 . Because of the orbital angular momentum structure of Bloch-wave states at ? and K (K') points, topological gaps are equal to the atomic spin-orbit coupling strengths, which are much larger than those based on the mechanism of the s - p band inversion.The energy spectra and eigen wave functions are solved analytically based on Clifford algebra. The competition among spin-orbit coupling ?, sublattice asymmetry m, and the Néel exchange field n results in band crossings at ? and K (K') points, which leads to various topological band structure transitions. The quantum anomalous Hall state is reached under the condition that three gap parameters ?, m, and n satisfy the triangle inequality. Flat bands also naturally arise which allow a local construction of eigenstates. The above mechanism is related to several classes of solid state semiconductor. G.F.Z. and C.W. are supported by the NSF DMR-1410375 and AFOSR FA9550-11-1-0067(YIP). Y.L. thanks the Inamori Fellowship and the support at the Princeton Center for Theoretical Science. C.W. acknowledges financial support from the National Natural Science.

  20. Honeycomb lattice with multiorbital structure: Topological and quantum anomalous Hall insulators with large gaps

    NASA Astrophysics Data System (ADS)

    Zhang, Gu-Feng; Li, Yi; Wu, Congjun

    2014-08-01

    We construct a minimal four-band model for the two-dimensional (2D) topological insulators and quantum anomalous Hall insulators based on the px- and py-orbital bands in the honeycomb lattice. The multiorbital structure allows the atomic spin-orbit coupling which lifts the degeneracy between two sets of on-site Kramers doublets jz=±3/2 and jz=±1/2. Because of the orbital angular momentum structure of Bloch-wave states at ? and K(K') points, topological gaps are equal to the atomic spin-orbit coupling strengths, which are much larger than those based on the mechanism of the s-p band inversion. In the weak and intermediate regime of spin-orbit coupling strength, topological gaps are the global gap. The energy spectra and eigen wave functions are solved analytically based on Clifford algebra. The competition among spin-orbit coupling ?, sublattice asymmetry m, and the Néel exchange field n results in band crossings at ? and K(K ') points, which leads to various topological band structure transitions. The quantum anomalous Hall state is reached under the condition that three gap parameters ?, m, and n satisfy the triangle inequality. Flat bands also naturally arise which allow a local construction of eigenstates. The above mechanism is related to several classes of solid state semiconducting materials.

  1. Square lattice honeycomb tri-carbide fuels for 50 to 250 KN variable thrust NTP design

    NASA Astrophysics Data System (ADS)

    Anghaie, Samim; Knight, Travis; Gouw, Reza; Furman, Eric

    2001-02-01

    Ultrahigh temperature solid solution of tri-carbide fuels are used to design an ultracompact nuclear thermal rocket generating 950 seconds of specific impulse with scalable thrust level in range of 50 to 250 kilo Newtons. Solid solutions of tri-carbide nuclear fuels such as uranium-zirconium-niobium carbide. UZrNbC, are processed to contain certain mixing ratio between uranium carbide and two stabilizing carbides. Zirconium or niobium in the tri-carbide could be replaced by tantalum or hafnium to provide higher chemical stability in hot hydrogen environment or to provide different nuclear design characteristics. Recent studies have demonstrated the chemical compatibility of tri-carbide fuels with hydrogen propellant for a few to tens of hours of operation at temperatures ranging from 2800 K to 3300 K, respectively. Fuel elements are fabricated from thin tri-carbide wafers that are grooved and locked into a square-lattice honeycomb (SLHC) shape. The hockey puck shaped SLHC fuel elements are stacked up in a grooved graphite tube to form a SLHC fuel assembly. A total of 18 fuel assemblies are arranged circumferentially to form two concentric rings of fuel assemblies with zirconium hydride filling the space between assemblies. For 50 to 250 kilo Newtons thrust operations, the reactor diameter and length including reflectors are 57 cm and 60 cm, respectively. Results of the nuclear design and thermal fluid analyses of the SLHC nuclear thermal propulsion system are presented. .

  2. Evolution of Bloch-mode envelopes in two-dimensional generalized honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Ablowitz, Mark J.; Zhu, Yi

    2010-07-01

    Wave propagation in two-dimensional generalized honeycomb lattices is studied. By employing the tight-binding (TB) approximation, the linear dispersion relation and associated discrete envelope equations are derived for the lowest band. In the TB limit, the Bloch modes are localized at the minima of the potential wells and can analytically be constructed in terms of local orbitals. Bloch-mode relations are converted into integrals over orbitals. With this methodology, the linear dispersion relation is derived analytically in the TB limit. The nonlinear envelope dynamics are found to be governed by a unified nonlinear discrete wave system. The lowest Bloch band has two branches that touch at the Dirac points. In the neighborhood of these points, the unified system leads to a coupled nonlinear discrete Dirac system. In the continuous limit, the leading-order evolution is governed by a continuous nonlinear Dirac system. This system exhibits conical diffraction, a phenomenon observed in experiments. Coupled nonlinear Dirac systems are also obtained. Away from the Dirac points, the continuous limit of the discrete equation leads to coupled nonlinear Schrödinger equations when the underlying group velocities are nearly zero. With semiclassical approximations, all the parameters are estimated analytically.

  3. Removal of indoor ?-pinene with a fiber optic illuminated honeycomb monolith photocatalytic reactor.

    PubMed

    Yu, Kuo-Pin; Lee, Grace Whei-May; Hung, An-Jie

    2014-01-01

    This study was undertaken to investigate the influencing factors including gas flow rate, inlet ?-pinene concentration and relative humidity on the removal of ?-pinene in a Degussa P25 supported honeycomb monolith reactor. We used the fiber optic illumination to enhance the intensity of UV-light irradiating on the Degussa P25 photocatalyst. The ?-pinene conversion increased with the increase of gas flow rate indicating that the reaction rate was associated with the gaseous phase mass transfer. The ?-pinene conversion varied between 91% and 96% in the range of inlet ?-pinene concentration (400-2400 ppb) and relative humidity (30-70%) examined. The kinetics fits the Langmuir-Hinshelwood model. The rate coefficient (k) of ?-pinene under RH30%, 50% and 70% was 0.82, 0.24, and 0.18 ?mol m(-2)s(-1), respectively. The competitive Langmuir adsorption constants for ?-pinene under RH30%, 50% and 70% were 0.17, 0.56 and 1.74 ppm(-1), respectively. The effect of relative humidity on ?-pinene conversion depends on the inlet ?-pinene concentration and raising relative humidity in sum has a positive effect on the reduction of partially oxidized intermediates within the range investigated. PMID:24844891

  4. Toward automatic evaluation of defect detectability in infrared images of composites and honeycomb structures

    NASA Astrophysics Data System (ADS)

    Florez-Ospina, Juan F.; Benitez-Restrepo, H. D.

    2015-07-01

    Non-destructive testing (NDT) refers to inspection methods employed to assess a material specimen without impairing its future usefulness. An important type of these methods is infrared (IR) for NDT (IRNDT), which employs the heat emitted by bodies/objects to rapidly and noninvasively inspect wide surfaces and to find specific defects such as delaminations, cracks, voids, and discontinuities in materials. Current advancements in sensor technology for IRNDT generate great amounts of image sequences. These data require further processing to determine the integrity of objects. Processing techniques for IRNDT data implicitly looks for defect visibility enhancement. Commonly, IRNDT community employs signal to noise ratio (SNR) to measure defect visibility. Nonetheless, current applications of SNR are local, thereby overseeing spatial information, and depend on a-priori knowledge of defect's location. In this paper, we present a general framework to assess defect detectability based on SNR maps derived from processed IR images. The joint use of image segmentation procedures along with algorithms for filling regions of interest (ROI) estimates a reference background to compute SNR maps. Our main contributions are: (i) a method to compute SNR maps that takes into account spatial variation and are independent of a-priori knowledge of defect location in the sample, (ii) spatial background analysis in processed images, and (iii) semi-automatic calculation of segmentation algorithm parameters. We test our approach in carbon fiber and honeycomb samples with complex geometries and defects with different sizes and depths.

  5. Quantum anomalous Hall states in the p-orbital honeycomb optical lattices

    SciTech Connect

    Zhang Machi [Department of Physics, University of California, San Diego, California 92093 (United States); Department of Physics, Tsinghua University, Beijing 100084 (China); Hung Hsianghsuan; Wu Congjun [Department of Physics, University of California, San Diego, California 92093 (United States); Zhang Chuanwei [Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164 (United States)

    2011-02-15

    We study the quantum anomalous Hall states in the p-orbital bands of the honeycomb optical lattices loaded with single-component fermions. Such an effect has not yet been realized in both condensed-matter and cold-atom systems. By applying the available experimental techniques to rotate each lattice site around its own center, the band structures become topologically nontrivial. At a certain rotation angular velocity {Omega}, a flat band structure appears with localized eigenstates carrying chiral current moments. By imposing the soft confining potential, the density profile exhibits a wedding-cake-shaped distribution with insulating plateaus at commensurate fillings. Moreover, the inhomogeneous confining potential induces dissipationless circulation currents, the magnitudes and chiralities of which vary with the distance from the trap center. In the insulating regions, the Hall conductances are quantized, and in the metallic regions, the directions and magnitudes of chiral currents can not be described by the usual local-density approximation. The quantum anomalous Hall effects are robust at temperature scales that are small compared to band gaps, which increase the feasibility of experimental realizations.

  6. Modeling of a honeycomb-shaped pyroelectric energy harvester for human body heat harvesting

    NASA Astrophysics Data System (ADS)

    Kim, Myoung-Soo; Jo, Sung-Eun; Ahn, Hye-Rin; Kim, Yong-Jun

    2015-06-01

    Pyroelectric conversion can be used for thermal energy harvesting in lieu of thermoelectric conversion. In the case of human body energy harvesting, the general pyroelectric energy harvester (PEH) cannot be applied because the weak body heat can hardly penetrate the protecting layer to reach the pyroelectric material. This paper presents the realization of a honeycomb-shaped PEH (H-PEH) and a modeling method of the electrode and hole areas. The fabricated H-PEH successfully generated electrical energy using human body heat. The H-PEH with a 1:1.5 electrode-and-hole area ratio showed the best performance. To verify the human energy harvesting, we evaluated the characteristics of conventional PEH and H-PEH when body heat was used as a heat source. The maximum power of the H-PEH was 0.06 and 0.16 ?W at wind velocities of 2 and 4 m s?1, respectively. These output power values of the H-PEH were 200 and 224% larger than those of the PEH, respectively, according to the wind velocity.

  7. Antiferromagnetic critical point on graphene's honeycomb lattice: A functional renormalization group approach

    NASA Astrophysics Data System (ADS)

    Janssen, Lukas; Herbut, Igor F.

    2014-05-01

    Electrons on the half-filled honeycomb lattice are expected to undergo a direct continuous transition from the semimetallic into the antiferromagnetic insulating phase with increase of onsite Hubbard repulsion. We attempt to further quantify the critical behavior at this quantum phase transition by means of functional renormalization group (RG), within an effective Gross-Neveu-Yukawa theory for an SO (3) order parameter ("chiral Heisenberg universality class"). Our calculation yields an estimate of the critical exponents ? ?1.31, ???1.01, and ???0.08, in reasonable agreement with the second-order expansion around the upper critical dimension. To test the validity of the present method, we use the conventional Gross-Neveu-Yukawa theory with Z2 order parameter ("chiral Ising universality class") as a benchmark system. We explicitly show that our functional RG approximation in the sharp-cutoff scheme becomes one-loop exact both near the upper as well as the lower critical dimension. Directly in 2+1 dimensions, our chiral Ising results agree with the best available predictions from other methods within the single-digit percent range for ? and ?? and the double-digit percent range for ??. While one would expect a similar performance of our approximation in the chiral Heisenberg universality class, discrepancies with the results of other calculations here are more significant. Discussion and summary of various approaches is presented.

  8. Dynamical polarization function, plasmons, and screening in silicene and other buckled honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Tabert, C. J.; Nicol, E. J.

    2014-05-01

    We explore the dielectric properties of graphene-like two-dimensional Kane-Mele topological insulators manifest in buckled honeycomb lattices (such as silicene and germanene). The effect of an on-site potential difference (?z) between sublattices is given particular attention. We present the results for the real and imaginary parts of the dynamical polarization function. We show that these results display features of three regimes (topological insulator, valley-spin polarized metal, and trivial band insulator) and may be used to extract information on the strength of the intrinsic spin-orbit coupling. We study the inverse dielectric function and provide numerical results for the plasmon branch. We discuss the behavior of the plasmon as a function of sublattice potential difference and show that the behavior of the plasmon branch as ?z is varied is dependent on the location of the chemical potential with respect to the gaps. The static polarization is discussed and numerical results for the screening of a charged impurity are provided. We observe a beating phenomenon in the effective potential which is dependent on ?z.

  9. Honeycomb-like porous gel polymer electrolyte membrane for lithium ion batteries with enhanced safety

    PubMed Central

    Zhang, Jinqiang; Sun, Bing; Huang, Xiaodan; Chen, Shuangqiang; Wang, Guoxiu

    2014-01-01

    Lithium ion batteries have shown great potential in applications as power sources for electric vehicles and large-scale energy storage. However, the direct uses of flammable organic liquid electrolyte with commercial separator induce serious safety problems including the risk of fire and explosion. Herein, we report the development of poly(vinylidene difluoride-co-hexafluoropropylene) polymer membranes with multi-sized honeycomb-like porous architectures. The as-prepared polymer electrolyte membranes contain porosity as high as 78%, which leads to the high electrolyte uptake of 86.2?wt%. The PVDF-HFP gel polymer electrolyte membranes exhibited a high ionic conductivity of 1.03?mS cm?1 at room temperature, which is much higher than that of commercial polymer membranes. Moreover, the as-obtained gel polymer membranes are also thermally stable up to 350°C and non-combustible in fire (fire-proof). When applied in lithium ion batteries with LiFePO4 as cathode materials, the gel polymer electrolyte demonstrated excellent electrochemical performances. This investigation indicates that PVDF-HFP gel polymer membranes could be potentially applicable for high power lithium ion batteries with the features of high safety, low cost and good performance. PMID:25168687

  10. Honeycomb-like porous gel polymer electrolyte membrane for lithium ion batteries with enhanced safety

    NASA Astrophysics Data System (ADS)

    Zhang, Jinqiang; Sun, Bing; Huang, Xiaodan; Chen, Shuangqiang; Wang, Guoxiu

    2014-08-01

    Lithium ion batteries have shown great potential in applications as power sources for electric vehicles and large-scale energy storage. However, the direct uses of flammable organic liquid electrolyte with commercial separator induce serious safety problems including the risk of fire and explosion. Herein, we report the development of poly(vinylidene difluoride-co-hexafluoropropylene) polymer membranes with multi-sized honeycomb-like porous architectures. The as-prepared polymer electrolyte membranes contain porosity as high as 78%, which leads to the high electrolyte uptake of 86.2 wt%. The PVDF-HFP gel polymer electrolyte membranes exhibited a high ionic conductivity of 1.03 mS cm-1 at room temperature, which is much higher than that of commercial polymer membranes. Moreover, the as-obtained gel polymer membranes are also thermally stable up to 350°C and non-combustible in fire (fire-proof). When applied in lithium ion batteries with LiFePO4 as cathode materials, the gel polymer electrolyte demonstrated excellent electrochemical performances. This investigation indicates that PVDF-HFP gel polymer membranes could be potentially applicable for high power lithium ion batteries with the features of high safety, low cost and good performance.

  11. Enhanced xylene removal by photocatalytic oxidation using fiber-illuminated honeycomb reactor at ppb level.

    PubMed

    Wu, Yi-Ting; Yu, Yi-Hui; Nguyen, Van-Huy; Lu, Kung-Te; Wu, Jeffrey Chi-Sheng; Chang, Luh-Maan; Kuo, Chi-Wen

    2013-11-15

    The removal of volatile organic compounds (VOCs) at ppb level is one of the most critical challenges in clean rooms for the semiconductor industry. Photocatalytic oxidation is an innovative and promising technology for ppb-level VOCs degradation. We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. Using the FIHR with Mn-TiO2 photocatalyst not only increased the m-xylene removal efficiency, but also increased the CO2 selectivity. Interestingly, Mn-TiO2 in FIHR also showed a very good reusability, 93% removal efficiency was still achieved in 72-h in reaction. Thus, the FIHR gave very high removal efficiency for xylene at ppb level under room temperature. The FIHR has great potential application in the clean room for the air purification system in the future. PMID:24140520

  12. Quantum oscillations of magnetization in tight-binding electrons on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Kishigi, Keita; Hasegawa, Yasumasa

    2014-08-01

    We show that quantum oscillations of the magnetization can occur when the Fermi surface consists of points (massless Dirac points) or even when the chemical potential is in an energy gap by studying tight-binding electrons on a honeycomb lattice in a uniform magnetic field. The quantum oscillations of the magnetization as a function of the inverse magnetic field are known as de Haas-van Alphen (dHvA) oscillations and the frequency is proportional to the area of the Fermi surface. The dominant period of the oscillations shown in this paper corresponds to the area of the first Brillouin zone and its phase is zero. The origin of these quantum oscillations is the characteristic magnetic field dependence of the energy known as the Hofstadter butterfly and the Harper broadening of Landau levels. These oscillations are not caused by the crossing of the chemical potential and Landau levels, which is the case in dHvA oscillations. These oscillations can be observed experimentally in systems with a large supercell such as a graphene antidot lattice or ultracold atoms in an optical lattice at an external magnetic field of a few Tesla when the area of the supercell is 104 times larger than that of graphene.

  13. Discrete solitons and vortices in hexagonal and honeycomb lattices: Existence, stability, and dynamics

    NASA Astrophysics Data System (ADS)

    Law, K. J. H.; Kevrekidis, P. G.; Koukouloyannis, V.; Kourakis, I.; Frantzeskakis, D. J.; Bishop, A. R.

    2008-12-01

    We consider a prototypical dynamical lattice model, namely, the discrete nonlinear Schrödinger equation on nonsquare lattice geometries. We present a systematic classification of the solutions that arise in principal six-lattice-site and three-lattice-site contours in the form of both discrete multipole solitons and discrete vortices. Additionally to identifying the possible states, we analytically track their linear stability both qualitatively and quantitatively. We find that among the six-site configurations, the “hexapole” of alternating phases (0-?) , as well as the vortex of topological charge S=2 have intervals of stability; among three-site states, only the vortex of topological charge S=1 may be stable in the case of focusing nonlinearity. These conclusions are confirmed both for hexagonal and for honeycomb lattices by means of detailed numerical bifurcation analysis of the stationary states from the anticontinuum limit, and by direct simulations to monitor the dynamical instabilities, when the latter arise. The dynamics reveal a wealth of nonlinear behavior resulting not only in single-site solitary wave forms, but also in robust multisite breathing structures.

  14. Importance of anisotropic exchange interactions in honeycomb iridates. New phenomena due to Kitaev interactions.

    NASA Astrophysics Data System (ADS)

    Perkins, Natalia

    2015-03-01

    We investigate the microscopic nature of the magnetism in honeycomb iridium-based systems. We show that the minimal model describing the magnetism in A2IrO3 includes both isotropic and anisotropic Kitaev-type spin-exchange interactions between nearest and next-nearest neighbor Ir ions, and that the magnitude of the Kitaev interaction between next-nearest neighbor Ir magnetic moments is comparable with nearest neighbor interactions. We computed the low temperature phase diagram of the effective model with classical Monte Carlo simulations. Due to the presence of the anisotropic Kitaev interactions and the frustration introduced by the competition of the spin couplings between nearest and next-nearest neighbors, the resulting phase diagram is very rich. It contains both various commensurate states and incommensurate single-Q and multi-Q phases, whose regions of stability are controlled by the ratios between competing exchange constants. We showed that the second neighbor Kitaev term plays an important role in the stabilization of the commensurate antiferromagnetic zigzag phase which has been experimentally observed in Na2IrO3. In our simulations, we found this phase to be the ground state for parameters of the model of both the correct signs and magnitudes. NSF Grant DMR-1255544.

  15. Pairing in doped Hubbard model on a honeycomb lattice: A quantum Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Ma, Tianxing

    2015-03-01

    Inspired by the recent discovered graphene, we performed a systematic QMC study of the magnetic and pairing correlation in the t-U-V Hubbard model on a honeycomb lattice. Close to half filling, we find that pairing with d +id symmetry dominates over pairing with extended-s symmetry. As the doping increases, the next-nearest-neighbor t' tends to be important and when t'<-t/6, the single-particle spectrum is featured by the continuously distributed Van-Hove saddle points at the band bottom, where the density of states diverges in power-law. We investigate possible unconventional superconductivity in such system with Fermi level close to the band bottom, and our studies reveal a possible triplet p + ip superconductivity with appropriate interactions. By including the spin-orbit coupling, it is shown that the d +id pairing is enhanced while the p +ip pairing is decreased by increasing spin-obit coupling. Our results might provide a possible route to look for triplet superconductivity with relatively-high transition temperature in a doped graphene and other similar systems.

  16. Selective recovery of catalyst layer from supporting matrix of ceramic-honeycomb-type automobile catalyst.

    PubMed

    Kim, Wantae; Kim, Boungyoung; Choi, Doyoung; Oki, Tatsuya; Kim, Sangbae

    2010-11-15

    Natural resources of platinum group metals (PGMs) are limited and their demand is increasing because of their extensive uses in industrial applications. The low rate of production of PGMs due to low concentration in the related natural ores and high cost of production have made the recovery of PGMs from previously discarded catalytic converters a viable proposition. The ceramic-honeycomb-type automobile catalytic converter contains appreciable amount of PGMs. These valuable substances, which are embedded in the catalyst layer and covered on the surface of the supporting matrix, were selectively recovered by attrition scrubbing. The attrition scrubbing was effective for the selective recovery of catalyst layer. The process was convinced as the comminution and separation process by physical impact and shearing action between particles in the scrubbing vessel. The catalyst layer was dislodged from the surface of the supporting matrix into fine particles by attrition scrubbing. The recovery of Al(2)O(3) and total PGMs in the fraction less than 300 ?m increased with the residence time whereas their contents in the recovered materials slightly decreased. The interparticle scrubbing became favorable when the initial input size increased. However, the solid/liquid ratio in the mixing vessel was slightly affected by the low density of converter particles. PMID:20728274

  17. Recovering aluminum from aluminum dross in a DC electric-arc rotary furnace

    Microsoft Academic Search

    Tz. Tzonev; B. Lucheva

    2007-01-01

    The recycling of aluminum scrap and dross yields significant economic and energy savings, as well environmental benefits.\\u000a The recovery of aluminum depends on many factors. The aim of this work is to experimentally investigate aluminum recovery\\u000a under different conditions. In this study, aluminum dross was processed in a direct-current electric-arc rotary furnace. The\\u000a presence of crushing refractory bodies during processing

  18. Inducible aluminum resistance of Acidiphilium cryptum and aluminum tolerance of other acidophilic bacteria

    Microsoft Academic Search

    Jörg Fischer; Armin Quentmeier; Sven Gansel; Vera Sabados; Cornelius G. Friedrich

    2002-01-01

    Aluminum ions are highly soluble in acidic environments. Toxicity of aluminum ions for heterotrophic, facultatively and obligately chemolithoautotrophic acidophilic bacteria was examined. Acidiphilium cryptum grew in glucose-mineral medium, pH 3, containing 300 mM aluminum sulfate [Al2(SO4)3] after a lag phase of about 120 h with a doubling time of 7.6 h, as compared to 5.2 h of growth without aluminum.

  19. Pilot-Scale Preparation of Nanometer Photocatalytic Film for Air Purification by Loading Commercial Nanometer Titanium Oxide Powder on Honeycomb Aluminum

    Microsoft Academic Search

    Hongyou Hu; Xuemei Li

    2011-01-01

    How to reduce the industrial preparation cost of thin film photocatalyst is very important to promote the application of nanometer photocatalyst technology in industrial production. This paper mainly focused on coating nanometer TiO2 (dioxide titanium) particles on solid substrates for air cleaning. The results revealed that the film could be prepared as following: The catalyst agent of complex crystal phase

  20. Boron aluminum crippling strength shows improvement

    NASA Technical Reports Server (NTRS)

    Otto, O. R.; Bohlmann, R. E.

    1974-01-01

    Results are presented from an experimental program directed toward improving boron aluminum crippling strength. Laminate changes evaluated were larger filament diameter, improved processing, shape changes, adding steel-aluminum cross plies, reduced filament volume in corners, adding boron aluminum angle plies, and using titanium interleaves. Filament diameter and steel-aluminum cross plies have little effect on crippling. It is shown that better processing combined with appropriate shape changes improved crippling over 50 percent at both room temperature and 600 F. Tests also show that crippling improvements ranging from 20 to 40 percent are achieved using angle plies and titanium interleaves.

  1. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2009-04-01 true Aluminum calcium silicate. 182.2122 Section 182.2122...Anticaking Agents § 182.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  2. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122...Anticaking Agents § 182.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  3. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122...Anticaking Agents § 582.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  4. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122...Anticaking Agents § 182.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  5. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122...Anticaking Agents § 582.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  6. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122...Anticaking Agents § 182.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  7. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122...Anticaking Agents § 582.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  8. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122...Anticaking Agents § 582.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  9. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122...Anticaking Agents § 582.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  10. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122...Anticaking Agents § 182.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  11. 21 CFR 182.1781 - Sodium aluminum phosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Sodium aluminum phosphate. 182.1781 Section 182...GRAS Food Substances § 182.1781 Sodium aluminum phosphate. (a) Product. Sodium aluminum phosphate. (b) Conditions of...

  12. 49 CFR 229.51 - Aluminum main reservoirs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 2012-10-01 2012-10-01 false Aluminum main reservoirs. 229.51 Section 229...Safety Requirements Brake System § 229.51 Aluminum main reservoirs. (a) Aluminum main reservoirs used on locomotives shall...

  13. 21 CFR 582.1127 - Aluminum ammonium sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Aluminum ammonium sulfate. 582.1127 Section...General Purpose Food Additives § 582.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

  14. 21 CFR 582.1781 - Sodium aluminum phosphate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Sodium aluminum phosphate. 582.1781 Section 582...Purpose Food Additives § 582.1781 Sodium aluminum phosphate. (a) Product. Sodium aluminum phosphate. (b) Conditions of...

  15. 21 CFR 582.1131 - Aluminum sodium sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Aluminum sodium sulfate. 582.1131 Section 582...General Purpose Food Additives § 582.1131 Aluminum sodium sulfate. (a) Product. Aluminum sodium sulfate. (b) Conditions of...

  16. 21 CFR 582.1127 - Aluminum ammonium sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Aluminum ammonium sulfate. 582.1127 Section...General Purpose Food Additives § 582.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

  17. 49 CFR 229.51 - Aluminum main reservoirs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 2011-10-01 false Aluminum main reservoirs. 229.51 Section 229...Safety Requirements Brake System § 229.51 Aluminum main reservoirs. (a) Aluminum main reservoirs used on locomotives shall...

  18. 21 CFR 582.1127 - Aluminum ammonium sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Aluminum ammonium sulfate. 582.1127 Section...General Purpose Food Additives § 582.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

  19. 21 CFR 182.1127 - Aluminum ammonium sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Aluminum ammonium sulfate. 182.1127 Section...Purpose GRAS Food Substances § 182.1127 Aluminum ammonium sulfate. (a) Product. Aluminum ammonium sulfate. (b) Conditions...

  20. 49 CFR 229.51 - Aluminum main reservoirs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 2013-10-01 2013-10-01 false Aluminum main reservoirs. 229.51 Section 229...Safety Requirements Brake System § 229.51 Aluminum main reservoirs. (a) Aluminum main reservoirs used on locomotives shall...