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1

Preparation and properties of thermoplastic honeycomb core sandwich structure with aluminum skin  

Microsoft Academic Search

The low-velocity impact response of thermoplastic honeycomb core sandwich structure with aluminum skin has been investigated by conducting drop-weight impact tests using an instrumented drop-weight impact tower. At first, the shear modulus of the thermoplastic honeycomb core and flexural modulus of the skin were investigated through a series of flexural test. Later in the study, the indentation test was conducted

S. Nurashikin; Akil Hazizan

2012-01-01

2

CONTINUOUSLY PRODUCED HONEYCOMB CORES  

Microsoft Academic Search

Today mechanical requirements and weight targets demand a lightweight sandwich design in many non-aerospace application areas. The large production cost of honeycomb core materials often prevents their use in low cost sandwich constructions. Other sandwich core materials however provide lower mechanical properties. The currently employed concepts for the production of honeycomb cores are reviewed to evaluate their potential for a

Jochen Pflug; Bart Vangrimde; Ignaas Verpoest

3

The strength characteristics of aluminum honeycomb sandwich panels  

Microsoft Academic Search

Aluminum sandwich construction has been recognized as a promising concept for structural design of lightweight transportation systems such as aircraft, high-speed trains and fast ships. The aim of the present study is to investigate the strength characteristics of aluminum sandwich panels with aluminum honeycomb core theoretically and experimentally. A series of strength tests are carried out on aluminum honeycomb-cored sandwich

Jeom Kee Paik; Anil K Thayamballi; Gyu Sung Kim

1999-01-01

4

An analytical model for composite sandwich panels with honeycomb core subjected to high-velocity impact  

Microsoft Academic Search

In this paper, an analytical model for perforation of composite sandwich panels with honeycomb core subjected to high-velocity impact has been developed. The sandwich panel consists of a aluminum honeycomb core sandwiched between two thin composite skins. The solution involves a three-stage, perforation process including perforation of the front composite skin, honeycomb core, and bottom composite skin. The strain and

S. Feli; M. H. Namdari Pour

5

Axial perforation of aluminum honeycombs by projectiles  

Microsoft Academic Search

Deformation and energy absorption characteristics of aluminum honeycomb when penetrated or perforated in the axial direction by spheres and cylinders with diameters of the order of and twice the cell size have been observed experimentally. The work of static penetration using a standard test machine was obtained from measured force histories when hard-steel spheres with three different diameters were pushed

Werner Goldsmith; Dell L. Louie

1995-01-01

6

Experimental Analysis and Modeling of the Crushing of Honeycomb Cores  

NASA Astrophysics Data System (ADS)

In the aeronautical field, sandwich structures are widely used for secondary structures like flaps or landing gear doors. The modeling of low velocity/low energy impact, which can lead to a decrease of the structure strength by 50%, remains a designer’s main problem. Since this type of impact has the same effect as quasi-static indentation, the study focuses on the behavior of honeycomb cores under compression. The crushing phenomenon has been well identified for years but its mechanism is not described explicitly and the model proposed may not satisfy industrial purposes. To understand the crushing mechanism, honeycomb test specimens made of Nomex™, aluminum alloy and paper were tested. During the crushing, a CCD camera showed that the cell walls buckled very quickly. The peak load recorded during tests corresponded to the buckling of the common edge of three honeycomb cells. Further tests on corner structures to simulate only one vertical edge of a honeycomb cell show a similar behavior. The different specimens exhibited similar load/displacement curves and the differences observed were only due to the behavior of the different materials. As a conclusion of this phenomenological study, the hypothesis that loads are mainly taken by the vertical edge can be made. So, a honeycomb core subjected to compression can be modeled by a grid of nonlinear springs. A simple analytical model was then developed and validated by tests on Nomex™ honeycomb core indented by different sized spherical indenters. A good correlation between theory and experiment was found. This result can be used to satisfactorily model using finite elements the indentation on a sandwich structure with a metallic or composite skin and honeycomb core.

Aminanda, Y.; Castanié, B.; Barrau, J.-J.; Thevenet, P.

2005-05-01

7

49 CFR 587.15 - Verification of aluminum honeycomb crush strength.  

Code of Federal Regulations, 2010 CFR

... 2012-10-01 2012-10-01 false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15 ...Offset Deformable Barrier § 587.15 Verification of aluminum honeycomb crush strength. The following procedure is...

2012-10-01

8

Crash behavior of box columns filled with aluminum honeycomb or foam  

Microsoft Academic Search

The effect of low density filler material, such as aluminum honeycomb or foam, on the axial crushing resistance of a square box column under quasi-static loading conditions is studied. Numerical simulation shows that in terms of achieving maximum energy absorption, filling the box column with aluminum honeycomb can be preferable to thickening the column wall. Superior specific energy absorption is

S. Santosa; T. Wierzbicki

1998-01-01

9

Crushing Strength of Aluminum Honeycomb with Thinning Cell Wall  

NASA Astrophysics Data System (ADS)

To evaluate the crash safety of automobiles, various collision tests are performed by the auto industry. In the offset frontal collision test and the side collision test, the target is an aluminum honeycomb material which has thinning cell walls. In this study, based on the analyses of the shock absorption mechanism, a new crushing strength formula is proposed. First, load-displacement curves obtained from compression tests in quasi-static condition showed an almost linear relation between a thinning rate of cell walls and a crushing strength. Second, based on Wierzbicki's theory, a new formula was proposed, which can estimate a crushing strength of a honeycomb material with thinning wall. In addition, a correcting equation which considered an elastic deformation was also proposed. Third, parametric analyses were carried out with a FE model which can simulate a delamination between cell walls. The results obtained from the theory and FEM almost corresponded to each other for a wide range of the thinning rate. Fourth, impact tests were carried out, in which the weight was dropped freely at the speed used for the automobile tests. Those results almost agreed well with the sum of the theoretical crush strength and the inside air pressure.

Ogasawara, Nagahisa; Chiba, Norimasa; Kobayashi, Eiji; Kikuchi, Yuji

10

Probabilistic nondestructive evaluation of bonded aluminum honeycomb structures  

NASA Astrophysics Data System (ADS)

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.

Schaefer, Lloyd A.

1995-07-01

11

Modeling of Heat Conduction in Thermoplastic Honeycomb Core\\/Face Sheet Fusion Bonding  

Microsoft Academic Search

Honeycomb sandwich materials have been widely used in aerospace industry as secondary structural materials or interior panels. Recently the research of full thermoplastic honeycomb sandwich materials has been of interest due to their recyclability. In their production, they usually demand an adhesive-free process, namely fusion bonding, to connect thermoplastic honeycomb core and face sheets. It is a heat induced process

Fan Xinyu; Li Yubin; Li Juan; Yan Chun; Li Ke

2009-01-01

12

Influence of Cell Size on the Core Shear Properties of FRP Honeycomb Sandwich Panels  

Microsoft Academic Search

This paper deals with the influence of cell size on the core shear modulus and shear strength of fiber reinforced plastic (FRP) honeycomb core sandwich panels. A relationship between the cell size and core density has been established for the honeycomb core made by matching the mold method. The cell size ranges from 8 to 25 mm, with the cell height

M. D. Antony Arul Prakash; V. L. Jagannatha Guptha; Ramesh S. Sharma; B. Mohan

2011-01-01

13

Influence of Cell Size on the Core Shear Properties of FRP Honeycomb Sandwich Panels  

Microsoft Academic Search

This article deals with the influence of cell size on the core shear modulus and shear strength of fiber-reinforced plastic (FRP) honeycomb core sandwich panels. A relationship between the cell size and core density has been established for the honeycomb core made by matching the mold method. The cell size ranges from 8 to 25 mm, with the cell height kept

M. D. Antony Arul Prakash; V. L. Jagannatha Guptha; Ramesh S. Sharma; B. Mohan

2012-01-01

14

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

Microsoft Academic Search

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.

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

2010-01-01

15

Numerical modeling and analysis of the damage characteristics of a honeycomb core within a sandwich panel  

Microsoft Academic Search

Sandwich panels increasingly replace metallic components in the aerospace industry. The sandwich panel configuration that is being considered in this research project is composed of carbon fiber composite facesheets encasing a honeycomb core. The honeycomb core is made from a fibrous sheet of material constructed into hexagonal cells. The core is relatively compliant compared to the composite facesheet, but together

Brandon M Wilkins

2009-01-01

16

Smart impact management devices: experimental validation of impact triggered rapid expansion of aluminum honeycomb  

NASA Astrophysics Data System (ADS)

A major limitation of current dedicated impact energy management structures and passive devices used in the transportation industry is that their starting volume is their maximum volume, i.e. they dissipate energy by crushing or stroking from a larger to a smaller volume. This space so occupied is not available for other uses, including such necessary/desirable functions as vehicle serviceability and repair, operational clearances, and interior spaciousness. This limitation has led to the proposal of a class of "smart" impact energy management devices, based on unexpanded aluminum honeycomb (HOBE), that initially occupy a small volume and based on sensor input are rapidly expanded to a much larger crushable volume (nominally 75 times greater) just prior to or in response to an impact. This paper documents the first portion of an experimental exploration of the viability of this technology. Specific goals of the herein documented test program were the demonstration, starting from blocks of unexpanded aluminum honeycomb, a) of the feasibility (and robustness) of sensor triggered rapid expansion both in terms of the integrity and uniformity of the resulting expanded honeycomb, and b) that expansion mechanisms that were required could be simple and have low energy/force requirements. The test program documented here was successful in both respects, demonstrating and thus validating the feasibility and robustness of low energy rapid expansion of aluminum honeycomb.

Browne, Alan L.; Johnson, Nancy L.; Webb, Scott R.

2006-04-01

17

Optimum design of a lightweight mirror using aluminum foam or honeycomb sandwich construction: a case study for the GLAS telescope  

NASA Astrophysics Data System (ADS)

A simple closed form solution was derived for the optimum weight design of a cylindrical sandwich mirror for a given self-weight deflection and mirror radius. This optimum solution is based on the generalized deflection equation for an axisymmetrically supported thick circular plate. This two parameter equation of deflection captures the deflection of the plate caused by bending and transverse shear. The solution yields the optimum facesheet thickness, core thickness, and core density. The derived optimum solution was used in a case stud for the GLAS (Geoscience Laser Altimeter System) primary mirror. This Beryllium mirror is manufactured with an open back isogrid pattern. The objective of this study is to determine a lightweight mirror design using Aluminum sandwich construction that can meet the performances of the current mirror and reduce fabrication costs. With the optimum solution several first order approximations using Aluminum honeycomb or foam core were determined. The performance, 1 g deflection, and wave front error of these designs was determined from Finite Element Analysis. The results conclude that sandwich construction outperforms the isogrid design by significant margins on both weight and distortion if the same material is used. Because of its superior specific stiffness the Beryllium isogrid design still marginally outperforms the optimum Aluminum sandwich design. However, the Aluminum sandwich design should provide significant advantages on cost and ease of fabrication over Beryllium isogrid designs.

Conkey, Shelly B.; Lee, Chiachung; Chaykovsky, Stephen P.; Content, David A.; Morrell, Armando; Budinoff, Jason G.

2000-10-01

18

Prospects and limitations of digital Shearography and Active Thermography in finding and rating flaws in CFRP sandwich parts with honeycomb core  

NASA Astrophysics Data System (ADS)

This work shows the prospects and limitations of the non-destructive testing methods Digital Shearography and Active Thermography when applied to CFRP sandwich parts with honeycomb cores. Two specimens with different core materials (aluminum, NOMEX) and artificial flaws such as delaminations, disbonds and inclusions of foreign material, are tested with Digital Shearography and Pulse Thermography including Pulse Phase Thermography. Both methods provide a good ability for finding and rating the flaws.

Gruber, J.; Mayr, G.; Hendorfer, G.

2012-05-01

19

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

SciTech Connect

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.

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

2008-01-01

20

Mean in-plane plateau stresses of hexagonal honeycomb cores under impact loadings  

Microsoft Academic Search

Double-walled hexagonal honeycomb cores (DHHCs) are important cushioning materials and their configuration parameters and impact velocities have effects on their impact properties. In this paper, the finite element (FE) model by using ANSYS\\/LS-DYNA was to investigate the relations between configuration parameters of DHHCs and their mean in-plane plateau stresses at impact velocities from 3 to 250m\\/s. When all configuration parameters

Sun Deqiang; Zhang Weihong

2009-01-01

21

Mean out-of-plane dynamic plateau stresses of hexagonal honeycomb cores under impact loadings  

Microsoft Academic Search

Double-walled hexagonal honeycomb cores (DHHCs) are important cushioning materials and their out-of-plane impact properties depend upon their configuration parameters and impact velocities. In this paper, the reliable finite element (FE) model by using ANSYS\\/LS-DYNA was designed to investigate the relations between configuration parameters of DHHCs and their out-of-plane dynamic plateau stresses at the impact velocities from 3 to 350m\\/s. FE

Sun Deqiang; Zhang Weihong; Wei Yanbin

2010-01-01

22

The soft impact of composite sandwich beams with a square-honeycomb core  

Microsoft Academic Search

The dynamic response of end-clamped monolithic beams and sandwich beams of equal areal mass have been measured by loading the beams at mid-span with metal foam projectiles to simulate localised blast loading. The sandwich beams were made from carbon fibre laminate and comprised identical face sheets and a square-honeycomb core. The transient deflection of the beams was determined as a

B. P. Russell; T. Liu; N. A. Fleck; V. S. Deshpande

23

Correlation of combined radiation and conduction in evacuated honeycomb-cored panels  

SciTech Connect

Hollands et al. (1984), Platzer (1992), and Hollands and Iynkaran (1993) have posed radiation and conduction heat transfer through honeycomb-cored panels rigorously as a combined mode problem, finding results which compare well with experiments. However, these analyses and their validating experiments are suited only to conditions of constant temperature on the front and backplates of the cored panel. Further, results of these studies are given only as heat transfer coefficients in specific cases, and are not fit into correlations. In this paper a new and fully numerical treatment of combined radiation and conduction through honeycomb-cored panels subject to radiative flux boundary conditions is offered. The effects of front and backplate temperature gradients are included, and are shown to be significant. Through-panel heat flux is correlated with a simple combined mode index, modified by a correction factor. This factor is unity in both radiation and conduction dominated cases, and rises to no more than 1.15 in combined mode cases. The setting addressed in this paper concerns a solar concentrator for use in a space-based power system (Campbell and Jensen, 1994). The concentrator surface is divided into many triangular segments, held together in an overall paraboloid shape by a framework. There are very many of these triangular segments, with the result that the curvature of any one individual segment is slight. Each segment is constructed of honeycomb-cored panel. Temperature differences through the panel resulting from solar incidence on one side and essentially darkness on the other side lead to thermal strains which tend to reduce the curvature of the panel and diffuse the focus of the whole concentrator. This effect is known as thermal defocusing, and the motivation for the present analysis is to identify through-panel temperature differences for use in quantifying the defocusing thermal strains.

Jones, P.D. [Auburn Univ., AL (United States). Mechanical Engineering Dept.

1996-05-01

24

Antivibration analysis of anomalistic honeycomb paperboard  

Microsoft Academic Search

Honeycomb paperboard has developed rapidly because of its hexagon core structure in casing area. One of the reasons is that honeycomb paper can prevent or lighten the vibration and concussion in the process of transportation. Existent anomalistic hexagon structure of the honeycomb paperboard has an impact on its antivibration characteristics. The antivibration effect of different anomalistic honeycomb paperboards are studied,

Jian Liu; Yuan-jun Lv

2009-01-01

25

Debris Impact on CFRP-AL Honeycomb Sandwich Structure  

NASA Astrophysics Data System (ADS)

In order to do risk assessments of debris impacts on unmanned spacecraft, it is necessary to investigate damage of honeycomb sandwich structures caused by debris impacts. However, the study of the honeycomb sandwich panel with CFRP face sheets has not been sufficiently performed. The purpose of this study is to investigate hypervelocity impact phenomena of CFRP-AL honeycomb sandwich structure. Hypervelocity impact tests were performed with a two-stage light gas gun at University of Padova. Three kinds of CFRP-AL honeycomb sandwich panels which are frequently used as a material of a spacecraft structure were tested. The cell size and the core thickness were varied. Aluminum spheres, 0.8 mm in diameter, were used as projectiles. The tests were performed at a velocity range between 2 and 5 km/sec. After the tests, the projectiles perforated all targets. The perforation holes on the panels were measured, and ultrasonic inspection was performed. The area of the perforation holes of the panel were increased with the impact velocity. The core size of the honeycomb core did not influence the relationship between the hole and the impact velocity. Impacts of the projectile on the foil of honeycomb cell caused heavy damage to a face sheet of the opposite side of the impact surface.

Higashide, Masumi; Nagao, Yosuke; Kibe, Seishiro; Francesconi, Alessandro; Paverin, Daniele

26

Failure mode maps for honeycomb sandwich panels  

Microsoft Academic Search

Failure modes for sandwich beams of GFRP laminate skins and Nomex honeycomb core are investigated. Theoretical models using honeycomb mechanics and classical beam theory are described. A failure mode map for loading under 3-point bending is constructed, showing the dependence of failure mode and load on the ratio of skin thickness to span length and honeycomb relative density. Beam specimens

A. Petras; M. P. F. Sutcliffe

1999-01-01

27

Honeycomb core material for sandwich construction - with common hexagonal walls bonded by thermoplastic resin and free walls carrying layer of resin and masking agent  

Microsoft Academic Search

Abstract:of NL 8902116 (A) \\u000aIn a honeycomb core material for a sandwich construction, the common hexagonal walls are bonded together by a thermoplastic resin, and the free hexagonal walls carry a layer of the same resin and also a masking agent. - A number of plates of raw material are given strips of glue, are laid on one another, and

1991-01-01

28

Honeycomb pattern array of vertically standing core-shell nanorods: Its application to Li energy electrodes  

SciTech Connect

An energy storage electrode system is fabricated via a template method with one-dimensional nanostructures that are hexagonally patterned in a honeycomblike fashion and vertically standing nanorods made of a gold-coated carbon nanotube core and a V{sub 2}O{sub 5} shell layer. The performance of this system for Li insertion and extraction shows an increased capacity along with an enhanced rate performance, which could be attributed to the aligned nanostructures having increased reaction sites, facilitated charge transport, and improved stability in the face of mechanical stress.

Kim, Youn-Su; Nam, Sang Hoon; Lee, Sang Ho; Shim, Hee-Sang; Kim, Won Bae [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712 (Korea, Republic of); Ahn, Hyo-Jin [Max Planck Institute of Colloids and Interfaces, D-14424 Potsdam (Germany)

2008-09-08

29

Continuously Produced Paper Honeycomb Sandwich Panels for Furniture Applications  

Microsoft Academic Search

Today mechanical requirements and weight targets demand a lightweight sandwich design in many application areas. The potential of honeycomb sandwich construction in furniture applications is, like in many other application areas mainly determined by the production cost of cores and panels. In the last decade the traditional honeycomb production processes for low cost paper honeycomb cores have been optimised towards

J. Pflug; B. Vangrimde; I. Verpoest; D. Vandepitte

30

Aerodynamic Effect of a Honeycomb Rotor Tip Shroud on a 50.8-Centimeter-Tip-Diameter Core Turbine.  

National Technical Information Service (NTIS)

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 op...

T. P. Moffitt W. J. Whitney

1983-01-01

31

Piezoelectrically-induced guided wave propagation for health monitoring of honeycomb sandwich structures  

NASA Astrophysics Data System (ADS)

Honeycomb sandwich structures have been widely used in marine and aerospace applications due to their high strength/stiffness-to-weight ratio. However, an excessive load or repeated loading in the core tends to induce debonding along the skin-core interface, threatening the integrity and safety of the whole structure. This dissertation focuses on development of guided wave strategies for health monitoring of honeycomb sandwich structures, based on a piezoelectric actuator/sensor network. The honeycomb sandwich panels, which are composed of aluminum alloy (T6061) skins and hexagonal-celled Nomex core, are specifically considered in the study. First, elastic wave propagation mechanism in honeycomb sandwich structures is numerically and experimentally investigated, based on a piezoelectric actuator/sensor system. Influences of cell geometry parameters upon wave propagation are also discussed. Some wave propagation characteristics, such as wave group velocity dispersion relation and mode tuning capabilities, in the honeycomb composite panels are experimentally characterized. Secondly, effects of skin-core debonding upon the leaky guided wave propagation in honeycomb sandwich structures are studied by the finite element simulation. An appropriate signal difference coefficient is defined to represent the differential features caused by debonding. By means of probability analysis of differential features of transmitted guided waves and the image fusion, the final image of the structure is constructed with improved detection precision. A multilevel sensor network strategy is proposed to detect multiple debondings in the honeycomb sandwich structure. Thirdly, an analytical model considering coupled piezo-elastodynamics is developed to quantitatively describe dynamic load transfer between a surface-bonded piezoelectric wafer actuator and a prestressed plate. The finite element method is used to evaluate the accuracy of the analytical prediction. Effects of prestresses on the characteristics of guided wave generation and propagation, such as time-of-flight, amplitude and wave tuning properties of guided wave modes, are analyzed, based on the developed model. Finally, to overcome the limitations of conventional guided wave methods, a baseline-free detection technique by using nonlinear acoustics is developed for debonding identification in honeycomb sandwich structures. The finite element analysis is performed to understand effects of the interaction of two debonded interfaces upon dynamic behavior of the sandwich structure. Specific experimental study is also conducted on the honeycomb sandwich panel to validate the concept. This dissertation study aims to broaden the scope of existing guided wave methods for debonding detection in honeycomb sandwich structures, and provide some insights for health monitoring of in-service structures.

Song, Fei

32

Perforation of honeycomb sandwich plates by projectiles  

Microsoft Academic Search

An analytical solution for the ballistic limit of a honeycomb plate subjected to normal impact by blunt and spherical projectiles is presented. The solution involves a three-stage, perforation process that results in complete perforation of the sandwich. Stages 1–3 describe perforation of the top facesheet, honeycomb core, and bottom facesheet, respectively. Residual velocities in Stages 1 and 2 are found

M. S. Hoo Fatt; K. S. Park

2000-01-01

33

Nonlinear acoustics and honeycomb materials  

NASA Astrophysics Data System (ADS)

The scope of research activity that Bruce Thompson embraced was very large. In this talk three different research topics that the author shared with Bruce are reviewed. They represent Bruce's introduction to NDE and include nonlinear acoustics, nondestructive measurements of adhesive bond strengths in honeycomb panels, and studies of flexural wave dispersion in honeycomb materials. In the first of these, four harmonics of a 30 Mhz finite amplitude wave were measured for both fused silica and aluminum single crystals with varying lengths and amounts of cold work using a capacity microphone with heterodyne receiver with a flat frequency response from 30 to 250 Mhz. The results for fused silica with no dislocation structure could be described by a model due to Fubini, originally developed for gases, that depends upon only the second and third order elastic constants and not the fourth and higher order constants. The same was not true for the aluminum with dislocation structures. These results raised some questions about models for harmonic generation in materials with dislocations. In the second topic, experiments were made to determine the adhesive bond strengths of honeycomb panels using the vibrational response of the panels (Chladni figures). The results showed that both the damping characteristics of panel vibrations as a whole and velocity of propagation of elastic waves that travel along the surface and sample the bondline can be correlated with destructively determined bond strengths. Finally, the phase velocity of flexural waves traveling along a 1-inch honeycomb sandwich panel was determined from 170 Hz to 50 Khz, ranging from 2.2×104 cm/sec at the low end to 1.18×105 cm/sec at 40 Khz. The dispersion arises from the finite thickness of the panel and agreed with the results of continuum models for the honeycomb. Above 40 Khz, this was not the case. The paper concludes with a tribute to Bruce for his many wonderful contributions and lessons beyond his technical legacy for all of us.

Thompson, D. O.

2012-05-01

34

Aluminum foams produced by liquid-state processes  

Microsoft Academic Search

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

A. E. Simone; L. J. Gibson

1998-01-01

35

Modelling of the Indentation Behaviour of Thermoplastic Honeycomb Sandwich Panels  

Microsoft Academic Search

Thermoplastic honeycombs based on polypropylene are one of the latest types of cores used in sand- wich structures. Up to now there have been few experimental and modelling studies on the mechani- cal behaviour of sandwich structures with thermoplastic cores. In this paper, by considering the sim- ilar properties of foams and thermoplastic honeycombs, attempts are made to model the

V. Khalili Moghamir; H. Rahimi; M. H. R. Ghoreishy; A. M. Rezadoust; M. Esfandeh

2008-01-01

36

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

NASA Astrophysics Data System (ADS)

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.

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

1985-08-01

37

Impact analysis of fiber reinforced polymer honeycomb composite sandwich beams  

Microsoft Academic Search

Large scale fiber reinforced polymer (FRP) composite structures have been used in highway bridge and building construction. Recent applications have demonstrated that FRP honeycomb sandwich panels can be effectively and economically applied for both new construction and rehabilitation and replacement of existing structures. This paper is concerned with impact analysis of an as-manufactured FRP honeycomb sandwich system with sinusoidal core

Pizhong Qiao; Mijia Yang

2007-01-01

38

Static and dynamic properties of high-density metal honeycombs  

Microsoft Academic Search

Metal honeycombs are commonly used to absorb energy in applications involving impact because of their high-energy capacity to weight ratio. The energy capacity of a material will be affected by any strain-rate effect in the material; thus knowledge of this property is necessary for design purposes. The materials studied in this work were a thick-walled aluminum and stainless-steel honeycomb. A

W. E. Baker; T. C. Togami; J. C. Weydert

1998-01-01

39

The Definition of Quality of Honeycomb Structures  

NASA Astrophysics Data System (ADS)

In the represented report the comprehensive approach to quality inspection of honeycomb structures is considered and substantiated to provide their high structural characteristics. The structures are intended for manufacturing micro satellite solar arrays. The investigated structures involve two skins of composite materials by a thickness from 0,1 to 0,3 mm and a filler by hexagonal honeycomb cells of aluminum alloy. It may be glued in a variety of ways: with a film glue or a glue deposited on end faces of cells. Variants and possibilities of nondestructive methods for quality inspection - holographic interferometer and infrared testing ones - are considered for various materials of skins and used glues. The various methods of loading the constructions is appreciated in order to get the required sensitivity of nondestructive besting methods. To provide the required structural properties in addition to the nondestructive testing the application of mechanical tests of honeycomb structure samples is substantiated. The kinds of mechanical tests are described and the results are given. The indicated approach provides the asked level of characteristics for honeycomb structures.

Sitalo, V. G.; Tykhyy, V. G.; Primakov, V. D.

2002-01-01

40

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

Microsoft Academic Search

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

German Reyes

2008-01-01

41

Extruded ceramic honeycomb and method  

DOEpatents

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.

Day, J. Paul (Big Flats, NY)

1995-04-04

42

Numerical simulation of temperature field in horizontal core-filling continuous casting for copper cladding aluminum rods  

NASA Astrophysics Data System (ADS)

The steady-state temperature field of horizontal core-filling continuous casting (HCFC) for producing copper cladding aluminum rods was simulated by finite element method to investigate the effects of key processing parameters on the positions of solid-liquid interfaces (SLIs) of copper and aluminum. It is found that mandrel tube length and mean withdrawing speed have significant effects on the SLI positions of both copper and aluminum. Aluminum casting temperature ( T Al) (1003-1123 K) and secondary cooling water flux (600-900 L·h-1) have little effect on the SLI of copper but cause the SLI of aluminum to move 2-4 mm. When T Al is in a range of 1043-1123 K, the liquid aluminum can fill continuously into the pre-solidified copper tube. Based on the numerical simulation, reasonable processing parameters were determined.

Su, Ya-jun; Liu, Xin-hua; Wu, Yong-fu; Huang, Hai-you; Xie, Jian-xin

2013-07-01

43

High-capacity honeycomb panel heat pipes for space radiators  

Microsoft Academic Search

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

H. J. Tanzer

1983-01-01

44

The Honeycomb supernova remnant  

NASA Astrophysics Data System (ADS)

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 (Snu is proportional to nu-1.2), normally associated with young SNRs.

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

1995-04-01

45

Microstructural control in an aluminum core alloy for brazing sheet applications  

NASA Astrophysics Data System (ADS)

The use of aluminum alloys for automotive heat exchangers has increased considerably in the last 15 to 20 years, and in parallel, new alloys have been developed to meet the increased demand for higher strengths and improved corrosion resistance. An Al-Mn alloy, X800, has been developed by Alcan to significantly increase the corrosion resistance of radiator tubes when subjected to typical service environments. Conventional alloy tubes, 3xxx or 6xxx, fail by intergranular attack, whereas X800 utilizes the diffusion of Si during brazing to form a sacrificial layer between core and cladding and thus prevent penetration through the core. The Si penetrates up to a depth of 70 µm into the core alloy and combines with both the Mn in solid solution and the coarse constituent particles to form the ?-AlMnSi phase. In contrast to the core, the interface layer exhibits a high dispersoid density, a modified coarse particle chemistry, and a lower Mn level in solid solution after brazing. Three layers remain after brazing; an ?-Al residual cladding, the interface layer with a band of dense precipitates (BDP), and the X800 core. Free corrosion potential measurements confirmed the lowering of the potential within the BDP by about 30 mV compared to —710 mV for the brazed X800 core.

Marshall, G. J.; Bolingbroke, R. K.; Gray, A.

1993-09-01

46

Novel Switched Reluctance Motor with Segment Core Embedded in Aluminum Rotor Block  

NASA Astrophysics Data System (ADS)

A novel segment type switched reluctance motor (SRM) is proposed, in which the segment core is embedded in aluminum (conductive metal) rotor block in order to increase the mechanical strength and easy manufacturing as well as to improve the performance characteristics and reduce the vibration and acoustic noise. The effect of design parameters on the average torque is investigated using the finite element method. Comparison with conventional VR type SRMs and segment type SRMs without conductive metal construction rotor show the proposed segment type SRM has advantages in the torque performances and the vibration and noise characteristics. The performance is also investigated by experiment.

Oyama, Jun; Higuchi, Tsuyoshi; Abe, Takashi; Kifuji, Nobuyuki

47

Effects of Processing Parameters on the Fabrication of Copper Cladding Aluminum Rods by Horizontal Core-Filling Continuous Casting  

NASA Astrophysics Data System (ADS)

Copper cladding aluminum (CCA) rods with a diameter of 30 mm and a sheath thickness of 3 mm were fabricated by horizontal core-filling continuous casting (HCFC) technology. The effects of key processing parameters, such as the length of the mandrel tube of composite mold, aluminum casting temperature, flux of the secondary cooling water, and mean withdrawing speed were optimized based on some quality criteria, including the uniformity of the sheath thickness, integrality of the rods, and thickness of the interface. The causes of internal flaws formation of CCA rods were also discussed. The results showed that the continuity of the liquid aluminum core-filling process and the interface reaction control between solid copper and liquid aluminum were two key problems that strongly affected the stability of the casting process and the product quality. Our research indicated that for the CCA rod with the previously mentioned size, the optimal length of mandrel tube was 210 mm. A shorter mandrel tube allowed of easier erosion at the interface, which led to a nonuniform sheath thickness. Conversely, it tended to result in a discontinuous filling process of liquid aluminum, which causes shrinkage or cold shuts. The optimal casting temperatures of copper and aluminum were 1503 K (1230 °C) and 1043 K to 1123 K (770 °C to 850 °C), respectively. When the casting temperature of aluminum was below 1043 K (770 °C), the casting process would be discontinuous, resulting in shrinkages or cold shuts. Nevertheless, when the casting temperature of aluminum was higher than 1123 K (850 °C), a severe interface reaction between solid copper and liquid aluminum would occur. The proper flux of the secondary cooling water and the mean withdrawing speed were determined as 600 to 800 L/h and 60 to 87 mm/min, respectively. In the previously mentioned proper ranges of processing parameters, the interfacial shear strengths of CCA rods were 40.5 to 67.9 MPa.

Su, Ya-Jun; Liu, Xin-Hua; Huang, Hai-You; Wu, Chun-Jing; Liu, Xue-Feng; Xie, Jian-Xin

2011-02-01

48

Experimental study of acoustical characteristics of honeycomb sandwich structures  

NASA Astrophysics Data System (ADS)

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.

Peters, Portia Renee

49

In-plane Tensile Behavior of Shape Memory Alloy Honeycombs with Positive and Negative Poisson's Ratio  

Microsoft Academic Search

This work illustrates the manufacturing and tensile testing of a novel concept of honeycomb structures with hexagonal and auxetic (negative Poisson's ratio) topology, made of shape memory alloy core material. The honeycombs are manufactured using Nitinol ribbons having 6.40 mm of width and 0.2 mm of thickness. The ribbons were inserted in a special dye using cyanoacrilate to bond the

M. R. Hassan; F. Scarpa; N. A. Mohamed

2009-01-01

50

Impact Response of Laminate Metal Honeycomb Sandwich Structure  

NASA Astrophysics Data System (ADS)

The ARMOR TPS is one of important candidate structure of RLV. It 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. 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 and impact load. The metal honeycomb sandwich structure is made of upper faceplate, lower faceplate and honeycomb core. In the course of the reusable launch vehicle working, it is possible that the space chips impact its outer surface. The main problem is what impact the metal honeycomb sandwich structure can stand and how many times it can stand. In the high speed impact experiment we choose different quality and velocity to simulate real space environment. This paper will analyze the mechanics behaviour of metal honeycomb sandwich structure in the course of impact, then we make sure the limit impact load and get the effect of impact flaw.

He, Xiaodong; Kong, Xianghao; Shi, Liping

2009-06-01

51

Bending Response of Sandwiched Double Tube Structures with Aluminum Foam Core  

NASA Astrophysics Data System (ADS)

Three point bending response of sandwiched double cylindrical tube structures with aluminum foam core was studied numerically using the explicit finite element method. The numerical results are in good agreement with the corresponding experimental results and display the advantage of this new structure in load carrying capacity and energy absorption efficiency over the traditional foam-filled single tube structure. The deformation and failure mechanism is revealed by comparisons of the strain and stress distributions and the history of the maximum strain. The influence of the inner tube diameter for the structure was explored. It is found that increasing the inner tube diameter enhances the maximum deflection at failure of the foam-filled double tube within the diameter range considered. With a proper inner tube diameter, a steady load carrying capacity of the foam-filled double tube structure can be achieved, which shows an excellent crashworthiness with high energy absorption efficiency.

Guo, L. W.; Yu, J. L.

2010-05-01

52

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

Microsoft Academic Search

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,

Zhongliang Chang; Guangping Zou; Weiling Zhao; Peixiu Xia

2009-01-01

53

Effect of geometric parameters on the in-plane crushing behavior of honeycombs and honeycombs with facesheets  

NASA Astrophysics Data System (ADS)

In aerospace field, use of honeycombs in energy absorbing applications is a very attractive concept since they are relatively low weight structures and their crushing behavior satisfies the requirements of ideal energy absorbing applications. This dissertation is about the utilization of honeycomb crushing in energy absorbing applications and maximizing their specific energy absorption (SEA) capacity by modifying their geometry. In-plane direction crushing of honeycombs is investigated with the help of simulations conducted with ABAQUS. Due to the nonlinearity of the problem an optimization technique could not be implemented; however, the results of the trend studies lead to geometries with improved SEA. This study has two objectives; the first is to obtain modified cell geometry for a hexagonal honeycomb cell in order to provide higher energy absorption for minimum weight relative to the regular hexagonal cell geometry which has 30° cell angle and walls at equal length. The results of the first objective show that by increasing the cell angle, increasing wall thickness and reducing vertical wall length it is possible to increase the SEA 4.8 times; where the honeycomb with modified geometry provided 3.3 kJ/kg SEA and with regular geometry 0.68 kJ/kg SEA. The second objective considers integration of the energy absorbing honeycombs into the helicopter subfloor, possibly as the web section of a keel beam. In-plane direction crushing of a honeycomb core sandwiched between two facesheets is simulated. Effects of core and facesheet geometric parameters on the energy absorption are investigated, and modified geometries are suggested. For the sandwich structure with thin facesheets increasing cell angle, increasing wall thicknesses and decreasing the cell depth increase the SEA. For the ones with thick facesheet reducing vertical wall length, increasing wall thicknesses and reducing the cell depth increase the SEA. The results show that regular honeycomb geometry with thin facesheets has SEA of 7.24 kJ/kg and with thick facesheets 13.16 kJ/kg. When the geometries are modified the SEA increases to 20.5 kJ/kg for the core with thin facesheets and 53.47 kJ/kg for the core with thick facesheets. The key finding of the dissertation is that the in-plane direction crushing of the honeycombs with facesheets has great potential to be used for the energy absorbing applications since their SEA levels are high enough to make them attractive for applications where high crash loads need to be absorbed such as helicopter crash.

Atli-Veltin, Bilim

54

Adhesive Bond Failures in Aircraft Honeycomb Sandwich Composites.  

National Technical Information Service (NTIS)

A number of approaches were initiated to improve bond strength and durability of honeycomb core-sandwich structures, some of which are described in the report. The overall objective was to determine why and how these composites fail and then determine wha...

T. R. Walton J. E. Cowling

1970-01-01

55

Experimental study on mechanical properties of aircraft honeycomb sandwich structures  

Microsoft Academic Search

Mechanical behaviour of sandwich panels under different conditions have been exprimentally studied in this research to increase the knowledge of aircraft sandwich panel structures and facilitate design criteria for aircraft structures. Tests were concentrated on the honeycomb sandwich structures under different loads including flexural, insert shear, flat wise tension and compression loads. Furthermore, effect of core density and face material

A. A. Zakeri; H. Talebi Mazraehshahi

2010-01-01

56

Performance Investigation of a Fiber Reinforced Composite Honeycomb Deck for Bridge Applications.  

National Technical Information Service (NTIS)

This report focuses mainly on the evaluation of stiffness and ultimate load-carrying capacity of Glass Fiber Reinforced Polymer (GFRP) honeycomb sandwich panels, with a sinusoidal core, used in bridge applications. Evaluation of fatigue performance is als...

O. Kalny R. J. Peterman

2005-01-01

57

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....

2010-08-16

58

Ply drop-off effects in CFRP\\/honeycomb sandwich panels—theory  

Microsoft Academic Search

This paper introduces a simple method for engineering analysis of ply drop-off induced local bending effects in CFRP\\/honeycomb sandwich panels. The model constituent parts are the base-line face laminate of a CFRP\\/sandwich panel, a dropped sub-laminate, a supporting honeycomb core material, and an adhesive\\/resin layer interfacing the laminates. The interaction between the core material and the face laminates is modelled

O. T. Thomsen; W. Rits; D. C. G. Eaton; S. Brown

1996-01-01

59

Honeycomb spacer crush stength test results  

SciTech Connect

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.

Leader, D.R.

1993-09-15

60

In situ core-level and valence-band photoelectron spectroscopy of reactively sputtered titanium aluminum nitride films  

Microsoft Academic Search

Titanium aluminum nitride (Ti-Al-N) films were deposited by reactive magnetron cosputtering. Core-level photoelectron spectroscopy and valence-band photoelectron spectroscopy served to characterize these films. Samples can consist of one single nanocrystalline phase, the substitutional solid solution (Ti, Al)N. There exist also ranges of compositions where a nanocomposite material is formed. This inhomogeneous film structure is indicated by shifts of the Fermi

Andreas Schüler; Peter Oelhafen

2001-01-01

61

Mathematical Model of Honeycomb Construction,  

National Technical Information Service (NTIS)

We developed a mathematical model and an algorithm for numerical treatment of a model of honeycomb construction in a beehive. The model contains essential features of the bee bee and bee wax interactions, and in a qualitative way captures the dynamics of ...

M. R. Belic V. Skarka J. L. Deneubourg M. Lax

1986-01-01

62

Structural Physics of Bee Honeycomb  

Microsoft Academic Search

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

Forrest Kaatz; Adhemar Bultheel; Takeshi Egami

2008-01-01

63

Unconventional superconductivity in honeycomb lattice  

NASA Astrophysics Data System (ADS)

Motivated by results of DMRG and tensor network simulations on doped t-J model on honeycomb lattice, we study superconductivity of singlet and triplet pairing in this model. We show that a coexistence of singlet and triplet pairing superconductivity is induced by antiferromagnetic order near half-filling. The superconducting state we obtain is a topological superconductor.

Qi, Yang; Sun, Kai; Gu, Zhengcheng; Fu, Liang

2011-03-01

64

Experimental and computational study of hypervelocity impact on spacecraft honeycomb  

NASA Astrophysics Data System (ADS)

Spacecraft honeycomb provides the primary line of defence against meteoroid and debris impact in orbit. This paper presents the results of experimental tests on honeycomb structures with core depths between 10 and 20 mm and facesheet thicknesses of 0.2 to 0.4 mm. The experimental data are used to identify damage morphologies near to target perforation and, for targets beyond the ballistic limit, the damage recorded on the witness plate. The process of impact and damage is evaluated using SPH hydrocode simulations for a target with 10 mm core depth and 0.2 mm thick facesheet over a velocity range of 3 to 13 km/s. Due to the limitations in the material models and resolution available, only broad trends are drawn from the results. The influence of the honeycomb core in channelling the debris cloud is clearly seen. The experimental and simulation data are compared with the Whipple bumper shield design and damage equation predictions. The smaller dp/T (particle diameter: bumper) ratios lead to non-optimum fragmentation of the debris cloud, compared with a Whipple bumper. The small separation between the facesheet means that, for some particle diameters and impact velocities, the projectile disruption is still ongoing when it impacts the rear facesheet.

Taylor, Emma

2001-06-01

65

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

NASA Astrophysics Data System (ADS)

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, the INSTRON4505 electronic universal testing machine and split Hopkinson pressure bar (SHPB) were used for testing the static and dynamic mechanical properties of sandwich panel with different thickness steel plate- foam aluminum core, from the results we can see that the steel plate thickness has big influence on the stress-strain curve of the sandwich panel, and also takes the sandwich panel with 1mm steel panel to study the material strain rate dependence which under different high shock wave stress loaded, the results show that the sandwich panel is strain rate dependence material. And also, in order to get good waveforms in the SHPB experiment, the waveform shaped technique is used in the dynamic experiments, and the study of this paper will good to sandwich panel used in the engineering.

Chang, Zhongliang; Zou, Guangping; Zhao, Weiling; Xia, Peixiu

2009-12-01

66

Development of NDE to monitor bond degradation in aircraft honeycomb components  

SciTech Connect

This paper presents results of recent research at DSTO Aeronautical and Maritime Research Laboratory to develop NDE techniques to assess bond degradation in metal-skin honeycomb and composite skin honeycomb control surfaces. In particular, it covers the detection of fillet bond failure where the honeycomb core and adhesive separate. Realistic fillet bond failure specimens, one of which had only 20% of the good bond strength, were generated by the application of spray-release agent to the honeycomb. 20MHz ultrasonic pulse-echo imaging was successfully used to detect fillet bond failure in these specimens. This technique was successful in detecting defined areas of fillet bond failure for a range of skin type and thickness Promising results were also obtained for the application to actual components, whilst also highlighting effects due to the presence of repairs. Further work will involve the evaluation of a range of other NDE methods to the detection and sizing of fillet bond failure.

Bowles, Susan J.; Scala, Christine M. [Aeronautical and Maritime Research Laboratory, DSTO, GPO Box 4331, Melbourne, Victoria 3001 (Australia)

1999-12-02

67

Integrated spatio-spectral method for efficiently suppressing honeycomb pattern artifact in imaging fiber bundle microscopy  

NASA Astrophysics Data System (ADS)

In a fiber bundle, spots of varying intensity occur throughout the fiber structure, and the ensemble of these spots creates the honeycomb pattern image, called a pixelated image. The spatio-spectral method, an integrated suppression method for the honeycomb pattern in the spatial and Fourier (spectral) domains, has demonstrated efficient restoration of microscopic images based on the fiber bundle. The morphological processing in the spatial domain partially interpolated the gaps between the circular patterns of fiber cores, and the selective band-reject filter in the Fourier domain was applied to reduce the honeycomb-shaped artifact. The auto-corrective search for the global peaks in the localized region was employed to apply the notch filter to the exact position of the individual periodic component in the Fourier domain. We found that a closing preprocessing in the spatial domain, combined with a Gaussian notch Fourier domain filter, yields the optimum image quality when eliminating the honeycomb pattern.

Lee, Cheon-Yang; Han, Jae-Ho

2013-10-01

68

Development of honeycomb impact limiters  

Microsoft Academic Search

General Atomics (GA), has a contract with DOE's Office of Civilian Radioactive Waste Management (OCRWM) to develop two legal weight truck casks to transport spent fuel. The GA-4 and GA-9 Casks transport four pressurized-water-reactor (PWR) and nine boiling-water-reactor spent fuel assemblies respectively. The GA-4 and GA-9 Casks preliminary designs include honeycomb impact limiters on the top and bottom of the

M. A. Koploy; C. Taylor

1989-01-01

69

Structural Physics of Bee Honeycomb  

NASA Astrophysics Data System (ADS)

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.

Kaatz, Forrest; Bultheel, Adhemar; Egami, Takeshi

2008-03-01

70

Honeycomb Sandwich Material Modeling for Dynamic Simulations of Aircraft Interior Components  

Microsoft Academic Search

An approach for modeling sandwich structures with a Nomex ® honeycomb core and phenolic composite faces in the commercial finite element code LS-DYNA with solid elements for the core and shell elements for the thin faces is presented, which accounts for the major sandwich failure modes. Extensive material testing was conducted to determine the parameters for the composite face material

S. Heimbs; P. Middendorf; M. Maier

71

Study on the cell size effect of steady state thermal performance of metallic honeycomb sandwich panels  

NASA Astrophysics Data System (ADS)

In this paper, numerical study is performed to reveal the influences of the cell size on the steady state thermal performance of hexagonal metallic honeycomb sandwich panel, by using the semi-empirical Swann and Pittman formula and the Finite Element Method (FEM), respectively. Based on the same material volume of honeycomb core, two types of hexagonal honeycomb core, i.e., size variation of core cell with a constant core height and height variation of core with a constant side length of hexagonal cell, are considered to establish the panel's thermal analysis model, which including the conduction and radiation coupling. Comparisons between the temperature distribution results from both methods show that FEM can reveal the size effect of the honeycomb cell on the thermal performances of sandwich panel while the Swann and Pittman formula can not. At the same time, numerical results show that for the core with constant height, the panel thermal performance analyzed by FEM has a tendency of being close to the results obtained from Swann and Pittman formula as the core cell size decreases; whereas, if the hexagonal cell with constant side length is concerned, the greater the core height, the worse the thermal conductive performance of sandwich panel. Besides, analyses based on both methods also show that the temperature distribution of the lower surface of panel becomes gradually uniform when the wall thickness of hexagonal cell decreases.

Lai, Yu-dong; Sun, Shi-ping

2011-11-01

72

Atomistic simulation of the atomic structure and diffusion within the core region of an edge dislocation in aluminum  

NASA Astrophysics Data System (ADS)

The core structure of an edge dislocation in aluminum is studied by molecular dynamics simulation with the glue potential. The edge dislocation of the 12[1¯10](111) type is observed to dissociate into two partials separating from each other by a distance of 9 Å. The half width of the two partial dislocations is deduced to be 6.5 Å, giving a half width of the whole dislocation of 12 Å. Dislocation mobility is studied by applying a shear stress on the crystal and by observing the corresponding shift of the Burgers vector density. After considering the mirror force on the dislocation exerted by the fixed boundaries, a Peierls stress of 0.75×10-4 ? (? is the shear modulus) for the motion of the whole dislocation is obtained. Atomic diffusion in the core region of the edge dislocation is simulated by hyper molecular dynamics method and the migration energy for vacancy diffusing in the dislocation core is calculated to approximate 0.5 eV.

Fang, Q. F.; Wang, R.

2000-10-01

73

Hot/Wet Environmental Degradation of Honeycomb Sandwich Structure Representative of F/A-18: Discolouration of Cytec FM-300 Adhesive.  

National Technical Information Service (NTIS)

Bonded honeycomb sandwich panels, consisting of graphite-epoxy face- sheets adhesively bonded to a honeycomb core, are used on military aircraft such as the F/A-18 due to their high stiffness and low weight Cytec FM-300 is the adhesive extensively used in...

A. Charon

2000-01-01

74

Dynamic response of metal honeycomb sandwich structure under high-speed impact  

NASA Astrophysics Data System (ADS)

The ARMOR TPS is one of important candidate structure of RLV. It 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. 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 and impact load. The metal honeycomb sandwich structure is made of upper faceplate, lower faceplate and honeycomb core. In the course of the reusable launch vehicle working, it is possible that the space chips impact its outer surface. The main problem is what impact the metal honeycomb sandwich structure can stand and how many times it can stand. In the high speed impact experiment we choose different quality and velocity to simulate real space environment. This paper will analyze the mechanics behaviour of metal honeycomb sandwich structure in the course of impact, and then we make sure the limit impact load and get the effect of impact flaw.

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

2009-12-01

75

The Soudan 2 honeycomb calorimeter  

NASA Astrophysics Data System (ADS)

Soudan 2 is an 1100-ton honeycomb tracking calorimeter which is being constructed to search for nucleon decay. The detector consists of finely segmented iron instrumented with long drift tubes, and records three spatial coordinates and dE/dx for every gas crossing. Excellent event reconstruction capability, particle identification and muon sign and direction determination give superior rejection of the neutrino background to nucleon decay in many modes. The first 620 tons of Soudan 2 are now in steady operation, with completion planned for 1992. Detector performance has been studied using cosmic ray tracks and a charged test beam calibration. Results on detector performance and detector response are described.

Garcia-Garcia, C.

1990-12-01

76

Interfacial Microstructure and Bonding Strength of Copper Cladding Aluminum Rods Fabricated by Horizontal Core-Filling Continuous Casting  

NASA Astrophysics Data System (ADS)

Copper cladding aluminum (CCA) rods with a diameter of 30 mm and a sheath thickness of 3 mm were fabricated by horizontal core-filling continuous casting (HCFC) technology. The microstructure and morphology, distribution of chemical components, and phase composition of the interface between Cu and Al were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), and energy dispersive spectrometer (EDS). The formation mechanism of the interface and the effects of key processing parameters, e.g., aluminum casting temperature, secondary cooling intensity, and mean withdrawing speed on the interfacial microstructure and bonding strength were investigated. The results show that the CCA rod has a multilayered interface, which is composed of three sublayers—sublayer I is Cu9Al4 layer, sublayer II is CuAl2 layer, and sublayer III is composed of ?-Al/CuAl2 pseudo eutectic. The thickness of sublayer III, which occupies 92 to 99 pct of the total thickness of the interface, is much larger than the thicknesses of sublayers I and II. However, the interfacial bonding strength is dominated by the thicknesses of sublayers I and II; i.e., the bonding strength decreases with the rise of the thicknesses of sublayers I and II. When raising the aluminum casting temperature, the total thickness of the interface increases while the thicknesses of sublayers I and II decrease and the bonding strength increases. Either augmenting the secondary cooling intensity or increasing the mean withdrawing speed results in the decrease in both total thickness of the interface and the thicknesses of sublayers I and II, and an increase in the interfacial bonding strength. The CCA rod with the largest interfacial bonding strength of 67.9 ± 0.5 MPa was fabricated under such processing parameters as copper casting temperature 1503 K (1230 °C), aluminum casting temperature 1063 K (790 °C), primary cooling water flux 600 L/h, secondary cooling water flux 700 L/h, and mean withdrawing speed 87 mm/min. The total thickness of the interface of the CCA rod fabricated under the preceding processing parameters is about 75 ?m, while the thicknesses of sublayers I and II are about 1.1 and 0.1 ?m, respectively.

Su, Ya-Jun; Liu, Xin-Hua; Huang, Hai-You; Liu, Xue-Feng; Xie, Jian-Xin

2011-12-01

77

Experimental study of acoustical behavior of flat honeycomb sandwich panel  

NASA Astrophysics Data System (ADS)

Honeycomb (HC) sandwich composites have lightweight and excellent mechanical properties, but have poor acoustic properties. This work was done to improve the acoustical performance of HC sandwich composites used in airplane floors. Transmission loss (TL) is one of the metrics used to assess acoustical performance of HC sandwiches and requires a TL suite. A small-scale sound transmission loss (TL) test facility was designed, constructed and qualified to conduct the experiments. TL measurements were made using the sound intensity technique based on ASTM. The small-scale facility was qualified between 315 Hz and 10 KHz, and the results of test panels were compared to results from two full-scale accredited labs. TL measured at the small-scale facility yielded reliable, relative comparisons for flat, HC panels. HC panel bending waves are characterized by three frequency regimes---total panel bending, core shear, and individual skin bending---that are controlled by panel geometry, panel mass and elastic properties of the core and the skins. Superior TL performance can be achieved by designing HC panels with significantly subsonic shear wave speed that delays the onset of coincidence frequency. The influence of different commercial HC sandwich design parameters, such as core density, core material, cell size, and cell structure, on TL was investigated. Frequency responses of TL for these panels were inferior. Supersonic core shear wave speed was identified as the reason for inferior acoustic performance. So three classes of panels with different core shear wave speeds---subsonic, transonic, and supersonic---were fabricated and compared for TL. Panels with subsonic and transonic core shear wave speeds showed improved acoustic performance than their supersonic counterparts. Also, optimization studies on panels with subsonic wave speeds showed that the mechanical performance of subsonic and transonic panel designs is generally low, but can be improved when accompanied by weight increase. Comparison of TL performance was made between panels with honeycomb cores made of p-aramid and m-aramid. The stiffer p-aramid HC cores improved the TL above coincidence frequency compared to m-aramid cores. The reason for improved TL at higher frequencies was the lowering of modal density for p-aramid HC cores. Lightweight noise control treatments for honeycomb sandwich panels were explored by adding a gas barrier layer to the panel on the incident side. (Abstract shortened by UMI.)

Rajaram, Shankar

78

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

NASA Astrophysics Data System (ADS)

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 ft2. In 1992, General Dynamics Space Systems Division (GDSS) began using thermographic nondestructive testing (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 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. TNDT is a production test method at GDSS.

Burleigh, Douglas D.; Kuhns, David R.; Cowell, Scott D.; Engel, James E.

1994-03-01

79

Aluminum/uranium fuel foaming/recriticality considerations for production reactor core-melt accidents  

SciTech Connect

Severe accident studies for the Savannah River production reactors indicate that if coherent fuel melting and relocation occur in the absence of target melting, in-vessel recriticality may be achieved. In this paper, fuel-melt/target interaction potential is assessed where fission gas-induced fuel foaming and melt attack on target material are evaluated and compared with available data. Models are developed to characterize foams for irradiated aluminum-based fuel. Predictions indicate transient foaming, the extent of which is governed by fission gas inventory, heating transient conditions, and bubble coalescence behavior. The model also indicates that metallic foams are basically unstable and will collapse, which largely depends on film tenacity and melt viscosity considerations. For high-burnup fuel, extensive foaming lasting tens of seconds is predicted, allowing molten fuel to contact and cause melt ablation of concentric targets. For low-burnup fuel, contact can not be assured. 9 refs., 4 figs., 4 tabs.

Hyder, M.L.; Ellison, P.G. (Westinghouse Savannah River Co., Aiken, SC (USA)); Cronenberg, A.W. (Engineering Science and Analysis, Albuquerque, NM (USA))

1990-01-01

80

Test and evaluation of aluminum drill pipe for deep-water coring: design and use of heavy-wall drilling joints for bending stress reduction. Technical report  

SciTech Connect

The report includes two papers dealing with means of extending the drill string depth capability and lowering stresses at the top of the drill string. The first paper reports on the operational use of a 2000 foot section of aluminum drill pipe in a mixed aluminum/steel drill string. The report also discusses metallurgical laboratory tests and assesses the potential of mixed strings for use in wireline coring operations to 30,000 feet. The second deals with the development and test of drilling joints used to reduce stresses at the upper end of the drill string.

Peterson, M.N.A.

1984-02-01

81

The Soudan 2 honeycomb calorimeter  

SciTech Connect

Soudan 2 is an 1100-ton honeycomb tracking calorimeter which is being constructed to search for nucleon decay. The detector consists of finely segmented iron instrumented with long drift tubes, and records three spatial coordinates and dE/dx for every gas crossing. Excellent event reconstruction capability, particle identification and muon sign and direction determination give superior rejection of the neutrino background to nucleon decay in many modes. The first 620 tons of Soudan 2 are now in steady operation, with completion planned for 1992. Detector performance has been studied using cosmic ray tracks and a charged test beam calibration. Results on detector performance and detector response are described in this paper. 2 refs. , 11 figs.

Garcia-Garcia, C.

1990-12-01

82

Reduction of Shear and Flatwise Tension Strength in F-111 Honeycomb Panels Exposed to Moisture  

Microsoft Academic Search

Many of the fuselage panels and control surfaces on the Royal Australian Air Force (RAAF) F- 111 aircraft are made up of bonded sandwich panels. These panels are made up of thin facings of metallic sheet that are bonded to aluminium honeycomb core. A survey of RAAF aircraft showed that these panels are susceptable to damage and deterioration through exposure

Richard A. Bartholomeusz

83

High-capacity honeycomb panel heat pipes for space radiators  

NASA Astrophysics Data System (ADS)

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 working fluid for the operating temperature range of -20 to 65 C. Critical parameters affecting heat-pipe thermal transport capacity are isolated, and current fabrication constraints are identified. In addition, several new concepts for an alternative high peformance mode of radiator operation using heat-pipe panel structures are described. Based on work presented in previous development, and the performance predictions and hardware design described herein, the internally wickable core panel appears to be a viable concept for highly efficient space radiators; however, additional in-depth hardware development and testing will determine the optimum combination of materials, core configuration, and manufacturing technique.

Tanzer, H. J.

1983-06-01

84

Sensing and actuation of smart chiral honeycombs  

NASA Astrophysics Data System (ADS)

A chiral honeycomb configuration is developed with embedded piezosensors and actuators for smart sandwich panel applications. The chiral honeycomb concept is made of repeating units of cylinders and plates (ligaments), featuring an in-plane negative Poisson's ratio. Rapid Prototyping vacuum-cast and FDM (Fusion Deposition Moulding) techniques are developed to embed micro fibres composites to be used for potential structural health monitoring (SHM) applications, and microwave absorption screens for electromagnetic compatibility. Finite Element models are also developed to prototype and simulate the response, sensing and actuation capability of the honeycombs for design purposes. Dynamic tests using scanning laser vibrometers and acoustic wave propagation are carried out to assess the feasibility of the concept.

Abramovitch, H.; Burgard, M.; Edery-Azulay, Lucy; Evans, K. E.; Hoffmeister, M.; Miller, W.; Scarpa, F.; Smith, C. W.; Tee, K. F.; Schönecker, A.; Seffner, L.

2008-05-01

85

Fatigue of honeycombs under in-plane multiaxial loads  

Microsoft Academic Search

Modeling for fatigue of honeycombs under in-plane multiaxial loads is proposed and presented here. Paris law for microcrack propagation, Basquin law for high cycle fatigue and Coffin–Manson law for low cycle fatigue are employed to describe the fatigue of solid cell walls within honeycombs, respectively. As a result, the number of cycles to failure of honeycombs can be obtained by

Jong-Shin Huang; Shi-Yi Liu

2001-01-01

86

Monolithic ceramics and heterogeneous catalysts: honeycombs and foams  

Microsoft Academic Search

Recent advances have been made in research on ceramic monolithic catalyst supports, particularly on honeycombs and ceramic foams. In the case of honeycombs, cordierite is the most commonly applied composition, but alternative materials, such as SiC, are beginning to be used for demanding conditions. Typical catalytic applications of honeycombs include use as catalyst supports for the removal of gaseous or

William M Carty; Peter W Lednor

1996-01-01

87

Reduced fidelity in the Kitaev honeycomb model  

SciTech Connect

We study reduced fidelity and reduced fidelity susceptibility in the Kitaev honeycomb model. It is shown that the nearest-two-site reduced fidelity susceptibility manifests itself as a peak at the quantum phase transition point, although the one-site reduced fidelity susceptibility vanishes. Our results directly reveal that the reduced fidelity susceptibility can be used to characterize the quantum phase transition in the Kitaev honeycomb model, which suggests that, despite its local nature, the reduced fidelity susceptibility is an accurate marker of the topological phase transition when it is properly chosen.

Wang, Zhi; Ma, Tianxing [Department of Physics and ITP, The Chinese University of Hong Kong (Hong Kong); Department of Physics, Beijing Normal University, Beijing 100875 (China); Gu, Shi-Jian; Lin, Hai-Qing [Department of Physics and ITP, The Chinese University of Hong Kong (Hong Kong)

2010-06-15

88

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

USGS Publications Warehouse

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

Meeker, G. P.

1995-01-01

89

Designing with advanced composites; Report on the European Core Conference, 1st, Zurich, Switzerland, Oct. 20, 21, 1988, Conference Papers  

SciTech Connect

The present conference discusses the development history of sandwich panel construction, production methods and quality assurance for Nomex sandwich panel core papers, the manufacture of honeycomb cores, state-of-the-art design methods for honeycomb-core panels, the Airbus A320 airliner's CFRP rudder structure, and the design tradeoffs encountered in honeycomb-core structures' design. Also discussed are sandwich-construction aircraft cabin interiors meeting new FAA regulations, the use of Nomex honeycomb cores in composite structures, a low-cost manufacturing technique for sandwich structures, and the Starship sandwich panel-incorporating airframe primary structure.

Not Available

1988-01-01

90

Simulation of the honeycomb construction process  

Microsoft Academic Search

The construction process of the honeycomb by bees is an astonishing process. The original structure which the bees built is nothing more than a lot of rough cylinders. But keeping the beeswax semi-flow for a certain time, those rough structures become perfect hexahedral columns. A modified, simplified particle method was used here to simulate the semi-flow state of the material.

Zhang Yuanzhang

2010-01-01

91

Localized nonlinear edge states in honeycomb lattices  

NASA Astrophysics Data System (ADS)

Two-dimensional localized edge modes in optical honeycomb lattices are found and analyzed analytically and computationally. Weak nonlinearity and transverse modulation are found to introduce self-phase modulation in the phase and create internal nonlinear interactions as the electromagnetic field propagates through the lattice. Even with relatively strong nonlinearity localization and persistence of modes along the edge are found.

Ablowitz, Mark J.; Curtis, Christopher W.; Zhu, Yi

2013-07-01

92

Honeycomb toroidal graphs are Cayley graphs  

Microsoft Academic Search

There is a particular family of trivalent vertex-transitive graphs that have been called generalized honeycomb tori by some and brick products by others. They have been studied as hexagonal embeddings on the torus as well. We show that all these graphs are Cayley graphs on generalized dihedral groups.

Brian Alspach; Matthew Dean

2009-01-01

93

PT-symmetry in honeycomb photonic lattices  

SciTech Connect

We apply gain and loss to honeycomb photonic lattices and show that the dispersion relation is identical to tachyons--particles with imaginary mass that travel faster than the speed of light. This is accompanied by -symmetry breaking in this structure. We further show that the -symmetry can be restored by deforming the lattice.

Szameit, Alexander; Rechtsman, Mikael C.; Bahat-Treidel, Omri; Segev, Mordechai [Physics Department and Solid State Institute, Technion, 32000 Haifa (Israel)

2011-08-15

94

PT-symmetry in honeycomb photonic lattices  

NASA Astrophysics Data System (ADS)

We apply gain and loss to honeycomb photonic lattices and show that the dispersion relation is identical to tachyons—particles with imaginary mass that travel faster than the speed of light. This is accompanied by -symmetry breaking in this structure. We further show that the -symmetry can be restored by deforming the lattice.

Szameit, Alexander; Rechtsman, Mikael C.; Bahat-Treidel, Omri; Segev, Mordechai

2011-08-01

95

Honeycomb Geometry: Applied Mathematics in Nature.  

ERIC Educational Resources Information Center

|Study and exploration of the hexagonal shapes found in honeycombs is suggested as an interesting topic for geometry classes. Students learn that the hexagonal pattern maximizes the enclosed region and minimizes the wax needed for construction, while satisfying the bees' cell-size constraint. (MNS)|

Roberts, William J.

1984-01-01

96

Honeycomb Geometry: Applied Mathematics in Nature.  

ERIC Educational Resources Information Center

Study and exploration of the hexagonal shapes found in honeycombs is suggested as an interesting topic for geometry classes. Students learn that the hexagonal pattern maximizes the enclosed region and minimizes the wax needed for construction, while satisfying the bees' cell-size constraint. (MNS)

Roberts, William J.

1984-01-01

97

OPTIMIZATION OF BOLTED JOINTS CONNECTING HONEYCOMB PANELS  

Microsoft Academic Search

The paper examines the range of issues associated with the optimization of bolted joint connections between honeycomb panels, representative of spacecraft structures. The first part of a large body of work, involving the application of experimental, finite element and analytical methods, has been carried out. A procedure has been developed to maximize the load carrying capability per unit mass of

G. Bianchi; G. S. Aglietti; G. Richardson

98

Mechanics and applications of pressure adaptive honeycomb  

Microsoft Academic Search

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

Roelof Vos

2009-01-01

99

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

Microsoft Academic Search

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,

Eric M. Furman; Samim Anghaie

1999-01-01

100

An analysis of corrosive species ingress into IM7\\/PETI-5 Ti honeycomb composites  

Microsoft Academic Search

The ability of the graphite fiber-reinforced thermoplastic polyimide composite IM7\\/LaRC-PETI-5 to trap species known to cause corrosion was investigated using a solution analysis technique that identifies and quantifies ionic species. The hydrated contents of individual titanium honeycomb cells comprising the core of the structure were accessed through the polymer–matrix composite (PMC) facesheets with syringes. Capillary electrophoresis (CE) was used to

Jackie M Williams; Robert G Kelly

2004-01-01

101

Off-Line Computation System for Supervising Performance of JOYO--JOYPAC System. Part 2. The Detailed Calculation Subsystem Predicting the JOYO Nuclear and Thermo-Hydraulic Characteristics: HONEYCOMB, FDCAL, And FATEC Codes.  

National Technical Information Service (NTIS)

The calculation codes HONEYCOMB, FDCAL-2 and FATEC-3 have been programmed for the purpose of developing a series of computer programs to be capable of predicting the detailed and fundamental informations about the core characteristics indispensable for su...

T. Suzuki A. Hasegawa M. Akimoto Y. Miyamoto S. Katsuragi

1976-01-01

102

Performance of sandwich plates with truss cores  

Microsoft Academic Search

Sandwich plates with truss cores fashioned from straight struts have distinct advantages relative to other constructions, including those with honeycomb cores. In addition to opportunities afforded by their open architecture, the truss core sandwich plates meet or exceed the load carrying capacity of other competitive constructions. The weight of truss core sandwich plates subject to a crushing stress and arbitrary

Nathan Wicks; John W. Hutchinson

2004-01-01

103

Study of the core-corona structure formed during the explosion of an aluminum wire in vacuum  

SciTech Connect

The time evolution of the matter parameters and current distribution in the discharge channel formed during a nanosecond explosion of a 25-{mu}m-diameter 12-mm-long aluminum wire was studied in a series of experiments with the following parameters: the discharge voltage was U{sub 0} = 20 kV, the current amplitude was I{sub max} {approx} 8 kA, and the current rise rate was dI/dt {approx} 40 A/ns. Optical shadow and schlieren images of the discharge channel were obtained using the second harmonic of a YAG: Nd{sup +3} laser, and UV images of the discharge channel self-radiation were recorded using a four-frame camera with a microchannel plate. The process of aluminum wire explosion was simulated numerically (including simulations performed from the 'cold start'). The numerical results were compared with the experimental data.

Tkachenko, S. I. [Moscow Institute of Physics and Technology (Russian Federation); Mingaleev, A. R. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Pikuz, S. A.; Romanova, V. M. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Khattatov, T. A. [Moscow Institute of Physics and Technology (Russian Federation); Shelkovenko, T. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Ol'khovskaya, O. G.; Gasilov, V. A. [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Kalinin, Yu. G. [National Research Centre Kurchatov Institute (Russian Federation)

2012-01-15

104

Interacting electrons on trilayer honeycomb lattices  

NASA Astrophysics Data System (ADS)

Few-layer graphene systems come in various stacking orders. Considering tight-binding models for electrons on stacked honeycomb layers, this gives rise to a variety of low-energy band structures near the charge neutrality point. Depending on the stacking order, these band structures enhance or reduce the role of electron-electron interactions. Here, we investigate the instabilities of interacting electrons on honeycomb multilayers with a focus on trilayers with ABA and ABC stackings theoretically by means of the functional renormalization group. We find different types of competing instabilities and identify the leading ordering tendencies in the different regions of the phase diagram for a range of local and no-local short-ranged interactions. The dominant instabilities turn out to be toward an antiferromagnetic spin-density wave (SDW), a charge density wave, and quantum spin Hall (QSH) order. Ab initio values for the interaction parameters put the systems at the border between SDW and QSH regimes. Furthermore, we discuss the energy scales for the interaction-induced gaps in this model study and put them into context with the scales for single-layer and Bernal-stacked bilayer honeycomb lattices. This yields a comprehensive picture of the possible interaction-induced ground states of few-layer graphene.

Scherer, Michael M.; Uebelacker, Stefan; Scherer, Daniel D.; Honerkamp, Carsten

2012-10-01

105

Mass transfer characteristics of wire-mesh honeycomb reactors  

Microsoft Academic Search

The mass transfer characteristics in honeycombs made of catalyst-deposited metal wire meshes (wire-mesh honeycomb; WMH) were studied to test the prediction that WMH has better flow distribution and a higher rate of interphase mass transfer than the conventional ceramic type of honeycomb module. The WMH module was constructed from alternating layers of flat and corrugated wire-mesh sheets packed within a

Zhidong Jiang; Ki-Suk Chung; Gun-Rae Kim; Jong-Shik Chung

2003-01-01

106

Development of a smart-skin phased array system with a honeycomb sandwich microstrip antenna  

NASA Astrophysics Data System (ADS)

We develop a smart-skin phased array antenna (PAA) with a scanning beam and cover the design, fabrication and testing of the smart-skin antenna structure, the phase shifter and electronic beam scanning. The smart skin is an organic honeycomb sandwich structure in which microstrip antennas are embedded that radiate a radio-frequency (RF) signal. The structure has excellent structural performance as a result of sandwich effects by facesheets and a honeycomb core. For ease of array feeding, the antenna element is excited by means of a coaxial probe. A stacked patch is used in order to increase the bandwidth. Electronic beam scanning is accomplished with a 4-bit digital phase shifter. The PAA design is processed at a center frequency of 7.5 GHz, a bandwidth exceeding 500 MHz, linear polarization and a scanning range of ± 45°. Performance is confirmed from experimental measurements made on a fabricated test model.

Son, Seong Ho; Eom, Soon Young; Hwang, Woonbong

2008-06-01

107

Studies on the mechanism of hydrolysis and polymerization of aluminum salts in aqueous solution: correlations between the “Core-links” model and “Cage-like” Keggin-Al 13 model  

Microsoft Academic Search

Two conflicting models describe the mechanism of aluminum (Al) hydrolysis and polymerization in aqueous solution, namely, the “Core-links” model and the “Cage-like” Keggin-Al13 model. For the sake of simplicity, the expressions of Al13 in the “Core-links” model and the “Cage-like” model are termed as C-Al13 and K-Al13, respectively. The two models have co-existed for almost 50 years, but describe differences

Shuping Bi; Chenyi Wang; Qing Cao; Caihua Zhang

2004-01-01

108

Nonlinear wave dynamics in honeycomb lattices  

SciTech Connect

We study the nonlinear dynamics of wave packets in honeycomb lattices and show that, in quasi-one-dimensional configurations, the waves propagating in the lattice can be separated into left-moving and right-moving waves, and any wave packet composed of only left (or only right) movers does not change its intensity structure in spite of the nonlinear evolution of its phase. We show that the propagation of a general wave packet can be described, within a good approximation, as a superposition of left- and right-moving self-similar (nonlinear) wave packets. Finally, we find that Klein tunneling is not suppressed by nonlinearity.

Bahat-Treidel, Omri; Segev, Mordechai [Department of Physics, Technion-Israel Institute of Technology, Technion City, Haifa 32000 (Israel)

2011-08-15

109

Orthogonal Dirac Semimetal on Honeycomb Lattice  

NASA Astrophysics Data System (ADS)

Recently, a concept of orthogonal metal has been introduced to reinterpret the disordered state of slave-spin representation in the Hubbard model as an exotic gapped metallic state. We have extended this concept to study the slave-spin representation of Hubbard model on the honeycomb lattice. It is found that a novel gapped metallic state coined orthogonal Dirac semimetal is identified. Such state corresponds to the disordered phase of slave-spin and has the same thermal-dynamical and transport properties as Dirac semimetal but its singe-particle excitation is gapped.

Zhong, Yin; Luo, Hong-Gang

2013-03-01

110

Photochromic, metal-absorbing honeycomb structures.  

PubMed

We demonstrate the synthesis and use of a spiropyran functional polymer to form highly ordered honeycomb materials by the breath figure technique, which is based on the self-assembly of water droplets. These materials undergo rapid and intense color changes both in solution and as porous films by irradiation with light (UV or visible). We also demonstrate the metal binding ability of these polymers ultimately to create hybrid organic-inorganic porous structures. Furthermore, by reduction of the metal and calcination of the organic materials, unique palladium microrings can be prepared. The methods described are general techniques that may be applied to a range of heavy metals. PMID:20524646

Connal, Luke A; Franks, George V; Qiao, Greg G

2010-07-01

111

Novel lithium-containing honeycomb structures.  

PubMed

Rock-salt-based honeycomb structures containing Te(VI) and Sb(V) with innumerable prospects of properties and applications were realized in the two new series of mixed-metal oxides of lithium, Li(8)M(2)Te(2)O(12) (M(II) = Co, Ni, Cu, Zn) and Li(8)M(2)Sb(2)O(12) (M(III) = Cr, Fe, Al, Ga). The structures of Li(8)Co(2)Te(2)O(12) and Li(8)Cu(2)Te(2)O(12) were determined by single-crystal X-ray diffraction for the first time, and mixed-occupancy Li/M was identified. PMID:23035961

Kumar, Vinod; Bhardwaj, Neha; Tomar, Nobel; Thakral, Vaishali; Uma, S

2012-10-04

112

A study on composite honeycomb sandwich panel structure  

Microsoft Academic Search

Honeycomb sandwich structure combines high flexural rigidity and bending strength with low weight. Sandwich construction plays an increasing role in industry, and sandwich structural designing is an available method for sandwich structures. However, the absence of the design variable is the principal problem of composite sandwich construction. In this paper, the structure and mechanical properties of honeycomb sandwich panels are

Meifeng He; Wenbin Hu

2008-01-01

113

Honeycomb Films of Biodegradable Polymers for Tissue Engineering.  

National Technical Information Service (NTIS)

We report that microporous films (honeycomb films) can lead various types of cells to tissue formation. The honeycomb films were fabricated by applying a moist air to a spread polymer solution containing biodegradable polymers poly(L-lactic acid) (PLLA) a...

J. Hayashi K. Arai M. Hara M. Shimomura T. Nishikawa

2003-01-01

114

Experimental Analysis and Modeling of the Crushing of Honeycomb Cores  

Microsoft Academic Search

In the aeronautical field, sandwich structures are widely used for secondary structures like flaps or landing gear doors. The modeling of low velocity\\/low energy impact, which can lead to a decrease of the structure strength by 50%, remains a designers main problem. Since this type of impact has the same effect as quasi-static indentation, the study focuses on the behavior

Y. Aminanda; B. Castanié; J.-J. Barrau; P. Thevenet

2005-01-01

115

Forming Process Simulation of Truss Core Panel  

NASA Astrophysics Data System (ADS)

Honeycomb panel is widely used as flooring or wall material in various structure including buildings, aircraft, train and so on due to high stiffness and lightness at present. Honeycomb panel, however, has a disadvantage that adhesive used to glue honeycomb core and top plate may burn by fire. On the other hand truss core panel has equivalent stiffness as honeycomb panel and is expected to be an alternative to honeycomb panel as it is safer for fire. However, in general, difficulty exists to form truss core and forming techniques should be developed for practice use of truss core panel. In this paper, firstly theoretical forming limitation is discussed for tetrahedral truss core . Secondly single stage forming simulation of truss core panel using explicit FEM technique was performed for preliminary investigation to estimate formability and thickness distribution. Finally multi-stage forming simulation was presented and possibility to apply press forming for truss core panel production through the simulation. In addition some results of the simulation was compared with the experiment and good agreement of both results was shown.

Tokura, Sunao; Hagiwara, Ichiro

116

Effect of geometric parameters on the in-plane crushing behavior of honeycombs and honeycombs with facesheets  

Microsoft Academic Search

In aerospace field, use of honeycombs in energy absorbing applications is a very attractive concept since they are relatively low weight structures and their crushing behavior satisfies the requirements of ideal energy absorbing applications. This dissertation is about the utilization of honeycomb crushing in energy absorbing applications and maximizing their specific energy absorption (SEA) capacity by modifying their geometry. In-plane

Bilim Atli-Veltin

2009-01-01

117

Aluminum-Induced Photoluminescence Red Shifts in Core-Shell GaAs/AlxGa1-xAs Nanowires.  

PubMed

We report a new phenomenon related to Al-induced carrier confinement at the interface in core-shell GaAs/AlxGa1-xAs nanowires grown using metal-organic vapor phase epitaxy with Au as catalyst. All AlxGa1-xAs shells strongly passivated the GaAs nanowires, but surprisingly the peak photoluminescence (PL) position and the intensity from the core were found to be a strong function of Al composition in the shell at low temperatures. Large and systematic red shifts of up to ?66 nm and broadening in the PL emission from the GaAs core were observed when the Al composition in the shell exceeded 3%. On the contrary, the phenomenon was observed to be considerably weaker at the room temperature. Cross-sectional transmission electron microscopy reveals Al segregation in the shell along six Al-rich radial bands displaying a 3-fold symmetry. Time-resolved PL measurements suggest the presence of indirect electron-hole transitions at the interface at higher Al composition. We discuss all possibilities including a simple shell-core-shell model using simulations where the density of interface traps increases with the Al content, thus creating a strong local electron confinement. The carrier confinement at the interface is most likely related to Al inhomogeneity and/or Al-induced traps. Our results suggest that a low Al composition in the shell is desirable in order to achieve ideal passivation in GaAs nanowires. PMID:23898926

Dhaka, Veer; Oksanen, Jani; Jiang, Hua; Haggren, Tuomas; Nykänen, Antti; Sanatinia, Reza; Kakko, Joona-Pekko; Huhtio, Teppo; Mattila, Marco; Ruokolainen, Janne; Anand, Srinivasan; Kauppinen, Esko; Lipsanen, Harri

2013-08-06

118

Electrochemical characterization of the nanoporous honeycomb diamond electrode as an electrical double-layer capacitor  

Microsoft Academic Search

Electrochemical properties of nanoporous honeycomb diamond electrodes in an aqueous electrolyte were investigated. Highly ordered honeycomb diamond structures were fabricated by etching the microwave plasma-deposited diamond films using an oxygen plasma. The diamond honeycomb exhibited a wide electrochemical potential window (ca. 2.5 V), similar to the unetched diamond film. From impedance measurements, the capacitance of the diamond honeycomb film was

K. Honda; Tata N. Rao; D. A. Tryk; A. Fujishima; M. Watanabe; K. Yasui; H. Masuda

2000-01-01

119

Spherical particles of intermetallic compounds of a large radius with a core-shell structure in aluminum alloys with scandium  

NASA Astrophysics Data System (ADS)

The structures of two-phase alloys that form upon slow solidification of a dilute Al-Sc melt containing a small amount of titanium additives (0.06 wt %) are studied. Near-spherical scandium trialuminide particles having a considerable linear size (up to 10-20 ?m) are found to grow. The study of the inner structure of the particles (dispersoids) reveals titanium impurities in the intermetallic structure. In addition, the following specific features of the structure are elucidated: a core-shell structure with a variation in the scandium and titanium content over the spheroid volume.

Shubin, A. B.; Popova, E. A.; Shunyaev, K. Yu.; Pastukhov, E. A.

2010-08-01

120

Damping capacity in shape memory alloy honeycomb structures  

NASA Astrophysics Data System (ADS)

SMA honeycombs have been recently developed by several Authors [1, 2] as innovative cellular structures with selfhealing capability following mechanical indentation, unusual deformation (negative Poisson's ratio [3]), and possible enhanced damping capacity due to the natural vibration dissipation characteristics of SMAs under pseudoelastic and superelastic regime. In this work we describe the nonlinear damping effects of novel shape memory alloy honeycomb assemblies subjected to combine mechanical sinusoidal and thermal loading. The SMA honeycomb structures made with Ni48Ti46Cu6 are designed with single and two-phase polymeric components (epoxy), to enhance the damping characteristics of the base SMA for broadband frequency vibration.

Boucher, M.-A.; Smith, C. W.; Scarpa, F.; Miller, W.; Hassan, M. R.

2010-03-01

121

Crystallography of rare galactic honeycomb structure near supernova 1987a  

NASA Astrophysics Data System (ADS)

Near supernova 1987a, the rare honeycomb structure of 20-30 galactic bubbles measures 30 x 90 light years. Its remarkable regularity in bubble size suggests a single-event origin which may correlate with the nearby supernova. To test the honeycomb's regularity in shape and size, the formalism of statistical crystallography is developed here for bubble sideness. The standard size-shape relations (Lewis's law, Desch's law, and Aboav-Weaire's law) govern area, perimeter and nearest neighbor shapes. Taken together, they predict a highly non-equilibrium structure for the galactic honeycomb which evolves as a bimodal shape distribution without dominant bubble perimeter energy.

Noever, David A.

1994-10-01

122

Dislocations in the Kitaev honeycomb model  

NASA Astrophysics Data System (ADS)

We study the effects of introducing dislocations into the Kitaev honeycomb model [1]. In the gapped phase, dislocations are Z2 ``twist defects'' associated with the transmutation of electric and magnetic excitations, studied previously in the context of ZN rotor models [2,3]. We show that each dislocation hosts one unpaired Majorana mode. As a consequence, twist defects have the statistics of Ising anyons. Because dislocations are confined, an additional phase is accumulated due to the change in system's energy during the braiding process. This means that the result of braiding can only be defined up to a phase. Therefore, twists are said to have projective non-Abelian statistics. [4pt][1] Alexei Kitaev, Annals of Physics 321, 2 (2006) [0pt][2] Hector Bombin, Phys. Rev. Lett. 105, 030403 (2010) [0pt][3] Yi-Zhuang You and Xiao-Gang Wen, Phys. Rev. B 86, 161107 (2012)

Petrova, Olga; Tchernyshyov, Oleg

2013-03-01

123

Interacting Electrons on the Honeycomb Lattice  

NASA Astrophysics Data System (ADS)

In this talk I review recent advances on the understanding of the ground state properties of interacting electrons on the honeycomb lattice. In the case of weak short range interactions, renormalization group methods allowed us to give a complete construction of the ground state of the half-filled system and to prove analyticity in the coupling constant of the thermodynamic functions and of the equilibrium correlations. In the case that the electrons interact with a three-dimensional quantum electromagnetic field, the ground state can be constructed order by order in renormalized perturbation theory, with the n-th order admitting n!-bounds. Ward Identities are needed in order to control the flow of the effective charges. Lorentz invariance is dynamically restored, thanks to lattice gauge invariance. This talk is based on joint work with V. Mastropietro and M. Porta.

Giuliani, Alessandro

2011-04-01

124

Magnetic impurities in the honeycomb Kitaev model.  

PubMed

We study the effect of coupling magnetic impurities to the honeycomb lattice spin-1/2 Kitaev model in its spin-liquid phase. We show that a spin-S impurity coupled to the Kitaev model is associated with an unusual Kondo effect with an intermediate coupling unstable fixed point Kc?J/S separating topologically distinct sectors of the Kitaev model. We also show that the massless spinons in the spin-liquid mediate an interaction of the form Si?2Sj?2/Rij3 between distant impurities unlike the usual dipolar RKKY interaction Si?Sj?/Rij3 noted in various 2D impurity problems with a pseudogapped density of states of the spin bath. Furthermore, this long-range interaction is possible only if the impurities (a) couple to more than one neighboring spin on the host lattice and (b) the impurity spin S?1/2. PMID:20867601

Dhochak, Kusum; Shankar, R; Tripathi, V

2010-09-07

125

Simulation of the honeycomb construction process  

NASA Astrophysics Data System (ADS)

The construction process of the honeycomb by bees is an astonishing process. The original structure which the bees built is nothing more than a lot of rough cylinders. But keeping the beeswax semi-flow for a certain time, those rough structures become perfect hexahedral columns. A modified, simplified particle method was used here to simulate the semi-flow state of the material. Although the parameters used here were still rather subjective, the simulation still could demonstrate some behavior of that sort of material like beeswax. And the method that the bees used to build their honey comb, could be an efficient method to imitate when we are trying to manufacture cellular materials.

Yuanzhang, Zhang

2010-06-01

126

Conduction of Heat in Lightweight Composite Honeycomb Structures.  

National Technical Information Service (NTIS)

This report contains comparisons of experimentally measured and theoretically calculated temperature distributions in honeycomb structural panels filled with a low diffusivity foam. The theoretical method involves the use of the three-dimensional Thermal ...

M. W. Goodwin

1965-01-01

127

Structural Testing and Analysis of Honeycomb Sandwich Composite Fuselage Panels.  

National Technical Information Service (NTIS)

This study investigated the damage tolerance characteristics and failure mechanisms of six honeycomb sandwich composite fuselage panels subjected to quasi-static pressurization and axial loading using the Full-Scale Aircraft Structural Test Evaluation and...

C. Davies F. A. Leone J. G. Bakuckas P. Shyprykevich

2008-01-01

128

Material Model Evaluation of a Composite Honeycomb Energy Absorber.  

National Technical Information Service (NTIS)

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 th...

E. L. Fasanella K. E. Jackson M. A. Polanco M. S. Annett

2012-01-01

129

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

SciTech Connect

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.

Widargo, Reza; Anghaie, Samim [Innovative Nuclear Space Power and Propulsion Institute, University of Florida, 202 NSC, Gainesville, Florida 32611-8300 (United States)

1999-01-22

130

Differentiating Honeycombed Images from Normal HRCT Lung Images  

NASA Astrophysics Data System (ADS)

A classification method is presented for differentiating honeycombed High Resolution Computed Tomographic (HRCT) images from normal HRCT images. For successful classification of honeycombed HRCT images, a complete set of methods and algorithms is described from segmentation to extraction to feature selection to classification. Wavelet energy is selected as a feature for classification using K-means clustering. Test data of 20 patients are used to validate the method.

Malik, Aamir Saeed; Choi, Tae-Sun

131

Facile synthesis of biomimetic honeycomb material with biological functionality.  

PubMed

A microfluidic approach to a honeycomb-structure material based on the synergistic effects of polymer rapid precipitation, double emulsion templating, and internal effervescent salt decomposition is reported. The delicate honeycomb structure exhibits unique characteristics with an external nanopore membrane and internal multiple cavities. The biological functionality of the artificial structure is explored to serve as microcarriers for cell culture and drug release, indicating their attractive properties for potential biomedical applications. PMID:23047525

Ma, Jingyun; Hui, Yu Sanna; Zhang, Min; Yu, Yue; Wen, Weijia; Qin, Jianhua

2012-10-09

132

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

SciTech Connect

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 and 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.

Furman, Eric M.; Anghaie, Samim [Innovative Nuclear Space Power and Propulsion Institute, University of Florida, Gainesville, Florida 32611 (United States)

1999-01-22

133

Honeycomb lattice spin-orbit Mott insulators  

NASA Astrophysics Data System (ADS)

Iridates displaying a Mott insulating state caused by the interplay of electronic correlations and strong spin-orbit coupling have recently attracted considerable attention. We focus on the honeycomb material A2IrO3 (A=Na, Li), in which the topology of the underlying lattice leads to interesting magnetic properties [1]. The strong spin-orbit coupling in this 5d transition metal system is expected to result in orbital-dependent highly anisotropic magnetic in-plane exchange [2]. The combination of Jeff = 1/2 and the underlying honeycomb lattice makes A2IrO3 a promising candidate for the Kitaev model, which is exactly solvable and has a spin-liquid ground state. Our experimental data on Na2IrO3 prove a Mott insulating state of effective J=1/2 moments with predominant antiferromagnetic coupling, indicated by a Weiss temperature of ?=-120 K. A bulk antiferromagnetic transition occurs at a much reduced temperature of TN = 15 K and the reduced magnetic entropy suggests strong magnetic frustration and/or low-dimensional magnetic interactions. The nature of the ordered phase has also been studied by resonant x-ray spectroscopy near the Ir-L3 edge, providing evidence for an unconventional, most-likely zig-zag-type spin ordering [3]. The latter may be related to next-nearest neighbour exchange and/or a substantial Kitaev contribution in the Heisenberg-Kitaev model [2]. Upon replacing Na with the smaller Li, one may enhance the relative importance of the Kitaev contribution. For Mott insulating Li2IrO3 we observe a similar ordering temperature of 15 K, while the negative Weiss temperature is drastically reduced. These observations are compatible with an enhancement of the Kitaev contribution compared to the Na-system, suggesting that Li2IrO3 could be located close to the Kitaev limit [5]. [4pt] [1] Yogesh Singh and P. Gegenwart, Phys. Rev. B. 82, 064412 (2010). [0pt] [2] G. Jackeli and G. Khaliullin, Phys. Rev. Lett. 102, 017205, (2009). [0pt] [3] X. Liu et al., Phys. Rev. B 83, 220403(R) (2011). [0pt] [4] Yogesh Singh, S. Manni, P. Gegenwart, arXiv:1106.0429v1. [0pt] [5] J. Reuther, R. Thomale, S. Trebst, Phys. Rev. B 84, 100406 (2011).

Gegenwart, Philipp

2012-02-01

134

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

NASA Astrophysics Data System (ADS)

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 a supporter to enhance mechanical strength. A matching layer made of nanotitanium powder and hydrogenation acrylonitrile-butadiene rubber composites was used for the face sheet, which allows the incident electromagnetic wave to enter and largely get attenuated through the absorbing system. Polyurethane foams containing CINFs and MMP of which a suitable content contributing to a broad bandwidth and high loss, were used as the core material. The measurement results show reflection loss was less than -10 dB over the frequency range of 3-18 GHz, which has a minimum value of - 26 dB at 14.2 GHz.

He, Yanfei; Gong, Rongzhou

2009-03-01

135

Test and evaluation of aluminum drill pipe for deep-water coring: design and use of heavy-wall drilling joints for bending stress reduction. Technical report  

Microsoft Academic Search

The report includes two papers dealing with means of extending the drill string depth capability and lowering stresses at the top of the drill string. The first paper reports on the operational use of a 2000 foot section of aluminum drill pipe in a mixed aluminum\\/steel drill string. The report also discusses metallurgical laboratory tests and assesses the potential of

1984-01-01

136

Mechanical behaviour of cellular core for structural sandwich panels  

Microsoft Academic Search

This paper deals with the analysis of the mechanical properties of the core materials for sandwich panels. In this work, the core is firstly a honeycomb and secondly tubular structure. This kind of core materials are extensively used, notably in automotive construction (structural components, load floors...). For this study, three approaches are developed: a finite element analysis, an analytical study

F. Meraghni; F. Desrumaux; M. L. Benzeggagh

1999-01-01

137

Singular stress fields in cellular cores for structural sandwich panels  

Microsoft Academic Search

The present study is concerned with the singularity of the stress fields in the cell walls of hexagonal honeycomb cores used in sandwich construction. The stress singularity under consideration occurs at the intersections of the cell walls at the core face sheet interface due to incompatibilities in the modes of deformation associated with the unconstrained cellular core and the face

Jörg Hohe; Wilfried Becker; Sanjib Goswami

2001-01-01

138

Low velocity impact response of novel fiber-reinforced aluminum foam sandwich structures  

Microsoft Academic Search

Sandwich structures based on high performance skins are currently finding widespread use in a number of aerospace, marine and automotive applications, where low weight, high strength and high stiffness are important design requirements. Many sandwich structures are based on polymeric foams such as PUR, PEI and PVC and aluminum honeycomb. Currently, most of such structures are manufactured using low curing

G. Reyes Villanueva; W. J. Cantwell

2003-01-01

139

Aluminum Hydroxide  

MedlinePLUS

Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

140

Modeling and structural analysis of honeycomb structure mirror  

NASA Astrophysics Data System (ADS)

In development of large-scale astronomical telescopes, some promising new technology and method such as honeycomb structure mirrors and silicon carbide mirrors are applied for primary mirrors. Especially in space telescopes, the mirror lightweight design is becoming the key technology and honeycomb structure mirrors are normally required more and more to reduce the cost and increase the feasibility of the telescopes system. In this paper, a parameter FEA model of a two meters honeycomb structure mirror has been built, by using the engineering analysis software ANSYS. Through this model, the structural analysis, thermal deformation analysis and the simulation active correction of low-order frequency aberration by the finite element method have been presented.

Li, Yeping

2012-09-01

141

Crushing analysis and multiobjective crashworthiness optimization of honeycomb-filled single and bitubular polygonal tubes  

Microsoft Academic Search

Honeycomb-filled tubes have recently gained attention for their enhanced energy absorption capacity. This paper firstly investigates the energy absorption characteristics of honeycomb-filled single and bitubular polygonal tubes (HSBPT) by nonlinear finite element analysis through LS-DYNA. By employing a six-level judgement method, we find that both of the honeycomb-filled single and honeycomb-filled bitubular tubes with enneagonal configuration have very excellent energy

Hanfeng Yin; Guilin Wen; Shujuan Hou; Kai Chen

2011-01-01

142

Topology optimization of pressure adaptive honeycomb for a morphing flap  

NASA Astrophysics Data System (ADS)

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.

Vos, Roelof; Scheepstra, Jan; Barrett, Ron

2011-03-01

143

Effect of inclusions and holes on the stiffness and strength of honeycombs  

Microsoft Academic Search

A finite element study has been performed on the effects of holes and rigid inclusions on the elastic modulus and yield strength of regular honeycombs under biaxial loading. The focus is on honeycombs that have already been weakened by a small degree of geometrical imperfection, such as a random distribution of fractured cell walls, as these imperfect honeycombs resemble commercially

C. Chen; T. J. Lu; N. A. Fleck

2001-01-01

144

Mechanical analysis of confectioning flaw of refractory alloy honeycomb sandwich structure  

NASA Astrophysics Data System (ADS)

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.

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

2009-03-01

145

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

NASA Astrophysics Data System (ADS)

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.

Luo, Yajun; Xie, Shilin; Zhang, Xinong

2008-11-01

146

Colonization with Schizophyllum commune of Localized Honeycomb Lung with Mucus  

Microsoft Academic Search

We report a surgical case involving localized honeycomb lung with mucus, caused by colonization of a Schizophyllum commune, which displayed a tumorous shadow in the right upper mediastinum. A 74-year-old male with a history of tuberculosis in the 1970s was referred to Chiba University Hospital (Chiba, Japan) with an abnormal shadow evident in the chest roentgenogram. A transbronchial biopsy failed

Toshihiko Iizasa; Katsuhiko Kamei; Masako Chiyo; Makoto Suzuki; Masayuki Baba; Tetsuya Toyosaki; Kenzo Hiroshima; Hidemi Ohwada; Shigeharu Kanno; Kazuko Nishimura; Takehiko Fujisawa

2001-01-01

147

Microstrip base station antenna made of honeycomb composites  

Microsoft Academic Search

This paper describes the advantages of using honeycomb composite technology in the design of cheap, flat-panel base station antennas. To demonstrate this technology, antenna elements with dual polarization for use in the in the 890 to 960 MHz frequency band are designed and manufactured. CAD and CAM techniques are used to achieve the design objectives. The antenna has a strong

P. Kabacik; M. Bialkowski

1998-01-01

148

Failure initiation and propagation characteristics of honeycomb sandwich composites  

Microsoft Academic Search

The energy absorbed during the failure of a variety of structural shapes is influenced by material, geometry and the failure mode. Failure initiation and propagation of the honeycomb sandwich under loading involves not only non-linear behavior of the constituent materials, but also complex interactions between various failure mechanisms. Therefore, there is a need for an improved understanding of the material

A. R. Othman; D. C. Barton

2008-01-01

149

Experimental study of acoustical behavior of flat honeycomb sandwich panel  

Microsoft Academic Search

Honeycomb (HC) sandwich composites have lightweight and excellent mechanical properties, but have poor acoustic properties. This work was done to improve the acoustical performance of HC sandwich composites used in airplane floors. Transmission loss (TL) is one of the metrics used to assess acoustical performance of HC sandwiches and requires a TL suite. A small-scale sound transmission loss (TL) test

Shankar Rajaram

2005-01-01

150

Planar classical dipolar system on a honeycomb lattice  

Microsoft Academic Search

The behavior of a system of dipoles is presented. Here we study a system of dipoles located on a honeycomb lattice under the mean-field approximation with dipoles confined to rotate in the plane of the lattice. It is found that, in zero external field, the system has a ground state which is continuously degenerate, and the degeneracy persists to T!=0.

George O. Zimmerman; A. K. Ibrahim; F. Y. Wu

1988-01-01

151

Titanium Honeycomb Acoustic Lining Structural and Thermal Test Report.  

National Technical Information Service (NTIS)

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. T...

D. Joynes J. P. Balut

1974-01-01

152

Exact spin liquid ground states of the quantum dimer model on the square and honeycomb lattices.  

PubMed

We study a generalized quantum hard-core dimer model on the square and honeycomb lattices, allowing for first and second neighbor dimers. At generalized Rokhsar-Kivelson points, the exact ground states can be constructed, and ground-state correlation functions can be equated to those of interacting (1+1)-dimensional Grassmann fields. When the concentration of second neighbor dimers is small, the ground-state correlations are shown to be short ranged corresponding to a (gaped) spin liquid phase. On a 2-torus, the ground states exhibit fourfold topological degeneracy. On a finite cylinder we have found a dramatic even-odd effect depending on the circumference and propose that this can be used as a numerical diagnostic of gapped spin-liquid phases, more generally. PMID:23004318

Yao, Hong; Kivelson, Steven A

2012-06-13

153

Test and Evaluation of Aluminum Drill Pipe for Deep Water Coring: Design and Use of Heavy Wall Drilling Joints for Bending Stress Reduction.  

National Technical Information Service (NTIS)

The report includes two papers dealing with means of extending the drill string depth capability and lowering stresses at the top of the drill string. The first paper reports on the operational use of a 2000 foot section of aluminum drill pipe in a mixed ...

M. N. A. Peterson

1984-01-01

154

Athermal lightweight aluminum mirrors and structures  

NASA Astrophysics Data System (ADS)

Aluminum foam core optics can be lightweight, cryo-stable, and low cost. The optimal design of a lightweight mirror is a sandwich with very thin, closely spaced support ribs. Open cell foams, used in sandwich mirrors, approach this optimum design. The availability of high quality aluminum foam and a bare aluminum polishing process have allowed high performance foam core optics made entirely of aluminum to be produced. The long history of aluminum space structures makes all aluminum optical systems attractive for many applications. We report on fabrication and testing of foam core and solid aluminum mirrors. Mirrors with integral mounts were designed for minimum surface error induced by self-weight deflection, thermal gradients, and mounting stresses. Previous work demonstrated the superiority of foam sandwich mirror construction over isogrid lightweighting, and finite element modeling to optimize the mirror design. Recent progress includes: (1) delivery of a lightweight aluminum foam core scan mirror for the Compact Visible-Infrared Radiometer, (2) cryo-stability tests on lightweight foam core spherical mirrors, and (3) an interferometric test of the ‘align warm, use cold" concept using a simulated instrument, the Offner Relay. The ‘align warm, use cold" concept eliminates the iterative process of misalignment compensation for CTE mismatch as well as figure changing due to CTE mismatch.

Hadjimichael, Theo; Content, David A.; Frohlich, Charles

2002-12-01

155

Aluminum Boats  

NSDL National Science Digital Library

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.

Center, Reuben H.

1999-01-01

156

Bioinspired design of honeycomb structure interfaces with controllable water adhesion.  

PubMed

Inspired by biological attachment systems, we fabricated the honeycomb structural films with different diameters by breath figure (BF) method, which were similar to the patterned octopus suckers. The experimental results showed, besides different van der Waals forces between the polystyrene (PS) surfaces and water, another important factor; that is, different negative pressures produced by different volumes of sealed air could be a crucial factor for the different adhesions. So the water adhesive forces of the as-prepared films can be effectively controlled from relative high to relative low adhesion by varying the pore diameters, which effectively adjusted the negative pressures produced by the pores. This unique adhesive phenomenon of honeycomb structure will be very useful for manipulating water droplet behaviors, as well as controlling liquid collection and transportation. These findings are interesting and helpful for us to further understand the biological attachment systems and to optimize the design of artificial analogues. PMID:23834708

Heng, Liping; Meng, Xiangfu; Wang, Bin; Jiang, Lei

2013-07-19

157

Fatigue and impact properties of metal honeycomb sandwich panel  

NASA Astrophysics Data System (ADS)

Honeycomb sandwich structures are significant to be used as applied to thermal protection system on reusable launch vehicle. In this paper the fatigue and impact properties of a novel metallic thermal protection material have been investigated and predicted at room temperature. A series of strength tests are carried out to obtain parameters firstly for further experiments. A set of tension-tension stress fatigue tests and impact tests based on split-Hopkinson pressure bar are carried out. Different high strain rate impact experiments are accomplished. The curves of dynamical stress, strain and strain rate are obtained. Also the cell units images after impact are presented. The results show the fatigue properties of honeycomb sandwich panels are comparatively better. And it has the advantages of anti-impact resistance and high, energy absorption capability.

Zou, Guang Ping; Lu, Jie; Liang, Jun; Chang, Zhong Liang

2008-11-01

158

Nanoclustered gold honeycombs for surface-enhanced Raman scattering.  

PubMed

A honeycomb-shaped gold substrate was developed for surface-enhanced Raman imaging (SERI). The honeycombs are composed of clusters of 50-70 nm gold nanoparticles and exhibit high Raman enhancement efficiency. An average surface enhancement factor (ASEF) of 1.7 × 10(6) was estimated for a monolayer of L-cysteine molecules adsorbed to gold via a thiol linkage. The presence of a linear relationship in the low concentration region was observed in SERI detection of malachite green isothiocyanate (MGITC). These results together with the high reproducibility and simple and cost-effective fabrication of this substrate suggest that it has utility for applications of surface-enhanced Raman scattering (SERS) in quantitative diagnoses and analyte detection. PMID:23210677

Leng, Weinan; Vikesland, Peter J

2013-01-09

159

Superelastic NiTi honeycombs: fabrication and experiments  

Microsoft Academic Search

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.

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

2007-01-01

160

Thermal insulation with paper honeycombs with solar gain  

Microsoft Academic Search

In this contribution we 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\\/(m2K) are obtained due to the very low thermal conduction value ?=0.04 W\\/(mK), which is comparable to thermal insulators as PU-foam or mineral

Kurt Hingerl; Gunther Baumgartner; Hans Aschauer

1996-01-01

161

The Abelian sandpile model on the honeycomb lattice  

NASA Astrophysics Data System (ADS)

We check the universality properties of the two-dimensional Abelian sandpile model by computing some of its properties on the honeycomb lattice. Exact expressions for unit-height correlation functions in the presence of boundaries and for different boundary conditions are derived. Also, we study the statistics of the boundaries of avalanche waves by using the theory of SLE and suggest that these curves are conformally invariant and described by SLE2.

Azimi-Tafreshi, N.; Dashti-Naserabadi, H.; Moghimi-Araghi, S.; Ruelle, P.

2010-02-01

162

Spin-Orbital Quantum Liquid on the Honeycomb Lattice  

NASA Astrophysics Data System (ADS)

The main characteristic of Mott insulators, as compared to band insulators, is to host low-energy spin fluctuations. In addition, Mott insulators often possess orbital degrees of freedom when crystal-field levels are partially filled. While in the majority of Mott insulators, spins and orbitals develop long-range order, the possibility for the ground state to be a quantum liquid opens new perspectives. In this paper, we provide clear evidence that the spin-orbital SU(4) symmetric Kugel-Khomskii model of Mott insulators on the honeycomb lattice is a quantum spin-orbital liquid. The absence of any form of symmetry breaking—lattice or SU(N)—is supported by a combination of semiclassical and numerical approaches: flavor-wave theory, tensor network algorithm, and exact diagonalizations. In addition, all properties revealed by these methods are very accurately accounted for by a projected variational wave function based on the ?-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 symmetric Kugel-Khomskii model on the honeycomb lattice is an algebraic quantum spin-orbital liquid. This model provides an interesting starting point to understanding the recently discovered spin-orbital-liquid behavior of Ba3CuSb2O9. The present results also suggest the choice of optical lattices with honeycomb geometry in the search for quantum liquids in ultracold four-color fermionic atoms.

Corboz, Philippe; Lajkó, Miklós; Läuchli, Andreas M.; Penc, Karlo; Mila, Frédéric

2012-10-01

163

Spin-orbital quantum liquid on the honeycomb lattice  

NASA Astrophysics Data System (ADS)

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.

Corboz, Philippe

2013-03-01

164

Order parameters from image analysis: a honeycomb example.  

PubMed

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. PMID:18633584

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

2008-07-17

165

Order parameters from image analysis: a honeycomb example  

NASA Astrophysics Data System (ADS)

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.

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

2008-11-01

166

Evaluation of thermal shock resistance of cordierite honeycombs  

Microsoft Academic Search

A comparative study on thermal shock resistance (TSR) of extruded cordierite honeycombs is presented. TSR is an important\\u000a property that predicts the life of these products in thermal environments used for automobile pollution control as catalytic\\u000a converter or as diesel particulate filter. TSR was experimentally studied by quenching (descending test) the heated samples\\u000a to water or by heating (ascending test)

Rathindra Nath Das; C. D. Madhusoodana; P. K. Panda; Kiyoshi Okada

2002-01-01

167

Accordion-Like Honeycombs for Tissue Engineering of Cardiac Anisotropy  

PubMed Central

Tissue engineered grafts may be useful in myocardial repair, however previous scaffolds have been structurally incompatible with recapitulating cardiac anisotropy. Utilizing microfabrication techniques, a novel accordion-like honeycomb microstructure was rendered in poly(glycerol sebacate) to yield porous, elastomeric 3-D scaffolds with controllable stiffness and anisotropy. Accordion-like honeycomb scaffolds with cultured neonatal rat heart cells demonstrated utility via: (1) closely matched mechanical properties compared to native adult rat right ventricular myocardium, with stiffnesses controlled by polymer curing time; (2) heart cell contractility inducible by electric field stimulation with directionally-dependent electrical excitation thresholds (p<0.05); and (3) greater heart cell alignment (p<0.0001) than isotropic control scaffolds. Prototype bilaminar scaffolds with 3-D interconnected pore networks yielded electrically excitable grafts with multi-layered neonatal rat heart cells. Accordion-like honeycombs can thus overcome principal structural-mechanical limitations of previous scaffolds, promoting the formation of grafts with aligned heart cells and mechanical properties more closely resembling native myocardium.

Engelmayr, George C.; Cheng, Mingyu; Bettinger, Christopher J.; Borenstein, Jeffrey T.; Langer, Robert; Freed, Lisa E.

2008-01-01

168

Water ingress detection in honeycomb sandwich panels by passive infrared thermography using a high-resolution thermal imaging camera  

NASA Astrophysics Data System (ADS)

Water ingress in honeycomb structures is of great concern for the civil and military aerospace industries. Pressure and temperature variations during take-off and landing produce considerable stress on aircraft structures, promoting moisture ingress (by diffusion through fibers or by direct ingress through voids, cracks or unsealed joints) into the core. The presence of water (or other fluids such as kerosene, hydraulic fluid and de-icing agents) in any of its forms (gas vapor, liquid or ice) promotes corrosion, cell breakage, and induce composite layer delaminations and skin disbonds. In this study, testing specimens were produced from unserviceable parts from military aircraft. In order to simulate atmospheric conditions during landing, selected core areas were filled with measured quantities of water and then frozen in a cold chamber. The specimens were then removed from the chamber and monitored for over 20 minutes as they warm up using a cooled high-resolution infrared camera. Results have shown that detection and quantification of water ingress on honeycomb sandwich structures by passive infrared thermography is possible using a HD mid-wave infrared cameras for volumes of water as low as 0.2 ml and from a distance as far as 20 m from the target.

Ibarra-Castanedo, C.; Brault, L.; Marcotte, F.; Genest, M.; Farley, V.; Maldague, X.

2012-05-01

169

Aluminum doped core-shell ZnO/ZnS nanowires: Doping and shell layer induced modification on structural and photoluminescence properties  

NASA Astrophysics Data System (ADS)

In this work, we investigated the combined effects of Al doping and surface modification on the fabrication of a core-shell type ZnO/ZnS nanowires (NWs) and its structural, electrical, and photoluminescence (PL) properties. A systematic investigation for different concentrations of Al doping followed by surface modification with different thicknesses of ZnS layer was performed. Significant changes in the nature of PL spectra and electronic conductivity are observed and insight discussions are present. Structural characterization on the core-shell NWs reveals the successful fabrication of Al doped highly single crystalline ZnO core and polycrystalline ZnS shell with both ZnO and ZnS are of hexagonal wurtzite structure. Compared with the bare undoped ZnO NWs, Al doped core-shell ZnO/ZnS NWs exhibit two orders of magnitude improvement in the electronic conductivity and fivefold enhancement in the UV PL intensity. The Al doped core-shell ZnO/ZnS NWs shows an efficient improvement in the UV PL intensity than the undoped core-shell ZnO NWs. The obtained improvement in the PL result is explained on the basis of interfacial transfer of photogenerated charge carriers and modification of defects.

Dhara, Soumen; Imakita, Kenji; Giri, P. K.; Mizuhata, Minoru; Fujii, Minoru

2013-10-01

170

Aluminum Analysis.  

ERIC Educational Resources Information Center

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)

Sumrall, William J.

1998-01-01

171

Analysis and control of vibrations of honeycomb plates by parametric stiffness modulations  

NASA Astrophysics Data System (ADS)

This paper addresses an active control of the resonant vibrations of a sandwich plate with the honeycomb composition of a core ply performed by a parametric stiffness modulation. The controlled vibrations are those of the dominantly flexural type excited by a transverse force acting at a low resonant frequency. The stiffness modulation is introduced by some fairly small changes in an orientation of plates composing cell elements of a core ply. It is performed at a comparatively high frequency identified by the resonance of a mode of the dominantly shear type. The method of direct partition of motions is used that predicts an existence of the modal interaction between the low-frequency and the high-frequency motions. It is shown that such a parametric control can provide a significant favourable shift of the first eigenfrequency of a controlled beam (the one subjected to the stiffness modulation) from its nominal value for an uncontrolled beam. Asymptotic results are checked by direct time-marching integration. The energy of the `micro-motions' is calculated and it is compared with the energies of flexural vibrations of a plate with and without control. Heavy fluid loading conditions are accounted for as well as material losses in a structure. It is demonstrated that although heavy fluid loading reduces the resonant frequencies of forced vibrations, the suggested mechanism of control remains valid in these cases.

Sorokin, S. V.; Grishina, S. V.; Ershova, O. A.

2001-10-01

172

High temperature effects of aluminum-coated fiber  

Microsoft Academic Search

High-temperature characteristics of aluminum-coated fibers have been investigated. The fibers studied are silica core fiber and germanium-doped cored fiber. it has been found that the silica core fiber is suitable for high-temperature application, although micro-bending loss change is dominant in all aluminum-coated fiber under 100°C. Germanium-doped core fiber has shown a loss increase at high temperature due to the increase

Takaoeru Shiota; Hiroshi Hidaka; Osamu Fukuda; Koichi Inada

1986-01-01

173

Interactions and phase transitions on graphene's honeycomb lattice.  

PubMed

The low-energy theory of interacting electrons on graphene's two-dimensional honeycomb lattice is derived and discussed. In particular, the Hubbard model in the large-N limit is shown to have a semimetal-antiferromagnetic insulator quantum critical point in the universality class of the Gross-Neveu model. The same equivalence is conjectured to hold in the physical case N=2, and its consequences for various physical quantities are examined. The effects of the long-range Coulomb interaction and the magnetic field are discussed. PMID:17155272

Herbut, Igor F

2006-10-02

174

Artificial honeycomb lattices for electrons, atoms and photons.  

PubMed

Artificial honeycomb lattices offer a tunable platform for studying massless Dirac quasiparticles and their topological and correlated phases. Here we review recent progress in the design and fabrication of such synthetic structures focusing on nanopatterning of two-dimensional electron gases in semiconductors, molecule-by-molecule assembly by scanning probe methods and optical trapping of ultracold atoms in crystals of light. We also discuss photonic crystals with Dirac cone dispersion and topologically protected edge states. We emphasize how the interplay between single-particle band-structure engineering and cooperative effects leads to spectacular manifestations in tunnelling and optical spectroscopies. PMID:24002076

Polini, Marco; Guinea, Francisco; Lewenstein, Maciej; Manoharan, Hari C; Pellegrini, Vittorio

2013-09-01

175

The physics of nanoscopic metal rings and honeycombs  

NASA Astrophysics Data System (ADS)

Both magnetic and superconducting systems exhibit long range order physics. In the magnetic case, long range order is described by the exchange length of the magnetic material while superconducting long range order is defined by its coherence length. If the dimensional length scales of the physical systems become comparable to the long range length scale of the parent material then interesting physical phenomena are observed. This thesis is mainly about the study of physical systems whose dimensional length scales are comparable to the long range length scales of the parent materials. It is mainly divided into three groups: ferromagnetic rings, superconducting honeycomb films and ultrasmall rings on thin Nb film. Chapter 1 and 2 provide an introduction and overview. Chapter 3 discusses the fabrication techniques used for this research. It is relevant to note that a new fabrication technique is revealed, which results in the fabrication of metal rings of unprecedented small size and also small symmetric and asymmetric rings. Chapters 4 discuss the experiments on ferromagnetic ultrasmall rings (diameter 13 nm) and asymmetric small rings (diameter 150 nm). Magnetic measurements and analytical investigations indicate that magnetic transition process is simple and occurs via the formation of vortex state in the case of ultra-small rings. It is also shown that by creating asymmetry in the ring's width, the direction of vortex magnetic circulation can be controlled by simple application of magnetic field. A related structure is a honeycomb film where hole sizes are of the order of 13 nm and center-to-center distance between neighboring holes are 28 nm. Chapters 5 discuss the physics of honeycomb films made of superconducting niobium. It is found that as the dimension scale becomes comparable to the coherence length of the superconductor, interesting physical behavior is observed, which includes: Unusual suppression of transition temperature for thin honeycomb films as compared to plain films, change in dimensionality of the films and a jump in resistivity for a sample etched for a particular amount of time. Chapter 6 discusses the electrical transport measurements of ultrasmall magnetic rings on a metal film.

Singh, Deepak-Kumar

176

Artificial honeycomb lattices for electrons, atoms and photons  

NASA Astrophysics Data System (ADS)

Artificial honeycomb lattices offer a tunable platform for studying massless Dirac quasiparticles and their topological and correlated phases. Here we review recent progress in the design and fabrication of such synthetic structures focusing on nanopatterning of two-dimensional electron gases in semiconductors, molecule-by-molecule assembly by scanning probe methods and optical trapping of ultracold atoms in crystals of light. We also discuss photonic crystals with Dirac cone dispersion and topologically protected edge states. We emphasize how the interplay between single-particle band-structure engineering and cooperative effects leads to spectacular manifestations in tunnelling and optical spectroscopies.

Polini, Marco; Guinea, Francisco; Lewenstein, Maciej; Manoharan, Hari C.; Pellegrini, Vittorio

2013-09-01

177

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

Microsoft Academic Search

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

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

2007-01-01

178

In-plane dynamic crushing of honeycomb. Part I: crush band initiation and wave trapping  

Microsoft Academic Search

In this paper the dynamics of crush band initiation and wave trapping that result from in-plane impact on a honeycomb are analysed using finite element simulations. The honeycomb structures were loaded in compression at the top surface with a prescribed velocity. Two different boundary conditions were considered; these produced an approximation to a state of uniaxial stress or uniaxial strain

A Hönig; W. J Stronge

2002-01-01

179

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

Microsoft Academic Search

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

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

2008-01-01

180

Dynamic Energy Absorption of Circular Honeycomb Under In-plane Impact Loading  

Microsoft Academic Search

To effectively control the dynamic energy absorption, a density graded circular honeycomb model is proposed, based on the concept of functionally graded materials. The influences of density gradient and impact velocity on the dynamic energy absorption ability of circular honeycomb are investigated by adopting explicit dynamic finite element method. Numerical results show that the density gradient affects greatly in the

Fan Weili; Zhang Xinchun

2010-01-01

181

Mesoporous aluminum phosphite  

SciTech Connect

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.

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

182

Impact response of integrated hollow core sandwich composite panels  

Microsoft Academic Search

This paper deals with an innovative integrated hollow (space) E-glass\\/epoxy core sandwich composite construction that possesses several multi-functional benefits in addition to the providing lightweight and bending stiffness advantages. In comparison with traditional foam and honeycomb cores, the integrated space core provides a means to route wires\\/rods, embed electronic assemblies, and store fuel and fire-retardant foam, among other conceivable benefits.

U. K Vaidya; M. V Hosur; D Earl; S Jeelani

2000-01-01

183

Smart impact management devices: experimental validation of impact triggered rapid expansion of aluminum honeycomb  

Microsoft Academic Search

A major limitation of current dedicated impact energy management structures and passive devices used in the transportation industry is that their starting volume is their maximum volume, i.e. they dissipate energy by crushing or stroking from a larger to a smaller volume. This space so occupied is not available for other uses, including such necessary\\/desirable functions as vehicle serviceability and

Alan L. Browne; Nancy L. Johnson; Scott R. Webb

2006-01-01

184

Relationship between adsorbed fibronectin and cell adhesion on a honeycomb-patterned film  

NASA Astrophysics Data System (ADS)

Substratum surface morphology plays a vital roles in cellular behavior. Here, we characterized adsorption of fibronectin (Fn) as a typical cell adhesion protein onto honeycomb-patterned films made of poly(?-caprolactone) (PCL) by using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). In order to determine how cells adhere to a honeycomb-patterned film, focal adhesion of cardiac myocytes (CMYs) and endothelial cells (ECs) on the films were studied by using fluorescence labeling of vinculin. Fn adsorbs around the pore edges to form ring-shaped structures. CMYs and ECs adhere onto the honeycomb-patterned films at focal contact points localized around pore edges distributed over the entire cellular surface. The focal contact points on the honeycomb-patterned films correspond well with the adsorption sites of Fn. We suggest that the cell response to honeycomb-patterned films is associated with the adsorption pattern of Fn on the film.

Yamamoto, Sadaaki; Tanaka, Masaru; Sunami, Hiroshi; Arai, Keiko; Takayama, Aiko; Yamashita, Shigeko; Morita, Yuka; Shimomura, Masatsugu

2006-09-01

185

The Hamiltonian Laceability of some Generalized Honeycomb Tori  

SciTech Connect

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.

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

186

Thermodynamics of the two-dimensional Heisenberg classical honeycomb lattice  

NASA Astrophysics Data System (ADS)

In this article we adapt a previous work concerning the two-dimensional (2D) Heisenberg classical square lattice [Physica B 245, 263 (1998)] to the case of a honeycomb lattice. Closed-form expressions of the main thermodynamic functions of interest are derived in the zero-field limit. Notably, near absolute zero (i.e., the critical temperature), we derive the values of the critical exponents ?=0, ?=-1, ?=3, and ?=1, as for the square lattice, thus proving their universal character. A very simple model allows one to give a good description of the low-temperature behaviors of the product ?T. For a 2D-compensated antiferromagnet, we derive simple relations between the characteristics of the maximum of the susceptibility curve T(?max) and ?max and the involved exchange energies. Therefore, owing to the knowledge of T(?max) and ?max, one can directly obtain the respective values of these energies. Finally, we show that the theoretical model allows one to fit correctly experimental susceptibility data of the recently synthetized compound Mn2(bpm)(ox)2.6H2O characterized by a 2D classical honeycomb lattice (where ``bpm'' and ``ox'' are the abbreviations for the ligands bipyrimidine and oxalate, respectively).

Curély, Jacques; Lloret, Francesc; Julve, Miguel

1998-11-01

187

Netlike knitting of polyelectrolyte multilayers on honeycomb-patterned substrate.  

PubMed

The pH-amplified exponential growth layer-by-layer (LBL) self-assembly process was directly performed on honeycomb-patterned substrate for achievement of "guided patterning" of polyelectrolyte multilayers. Polyethylenimine (PEI) and poly(acrylic acid) (PAA) were used as polyanions, and their pH were carefully tuned to achieve pH-enhanced exponential growth. Guided by underlying hexagonally patterned islandlike poly(dimethylsiloxane) (PDMS) arrays, the diffusive polyelectrolytes rapidly interweaved into linear, multilayered structures distributed along the grooves between the patterned protuberate and formed a regular network of multilayered film with uniform mesh size. Netlike "knitting" of polyelectrolyte multilayers on honeycomb-patterned substrate has been realized by following this procedure. Superhydrophobic surfaces could be readily obtained after several bilayers of LBL assembly (with thermal cross-linking and surface fluorination by chemical vapor deposition), indicating that successful fabrication of functional micro- and nanoscale hierarchical structures can be achieved. Both high- and low-adhesion superhydrophobic surfaces ("petal effect" and "lotus effect") can be obtained with different bilayers of assembly, proving that different levels of nano- to microstructural hierarchy can be realized using this method. Furthermore, we were able to get topographically asymmetric, free-standing, polyelectrolyte multilayer films in the case that we performed more than eight bilayers of assembly. This research reported template-directed LBL patterning assembly for the first time. It provides a beneficial exploration for the surface patterning technique for the LBL assembly process. PMID:20684559

Sun, Wei; Shen, Liyan; Wang, Jiaming; Fu, Ke; Ji, Jian

2010-09-01

188

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...

2009-07-22

189

Exact Solutions for Localized Correlations of S = 1/2 Ising Models on the Square, Triangular, Honeycomb, Decorated-Honeycomb and Kagome Lattices.  

NASA Astrophysics Data System (ADS)

This investigation involves obtaining and analyzing exact solutions for the even- and odd-number localized correlations of various planar Ising ferromagnets at all temperatures. In particular, the presently studied lattices are the square, triangular, honeycomb, kagome and decorated -honeycomb. Three different theoretical methods were used in the present calculations: (1) linear algebraic correlation identities having interaction-dependent coefficients, (2) extended star-triangle and decoration-iteration transformation theorems, and (3) traditional Pfaffian techniques. The square lattice even-number correlations on two eight-site clusters were calculated by linear algebraic methods supplemented by relatively few correlations evaluated by Pfaffian techniques, and the odd-number correlations and their critical ampli - tudes were calculated on a five-site cluster by similar linear algebraic methods with only a priori knowledge of the spontaneous magneti- zation. The even-number correlation calculations upon a seven-site cluster of the triangular lattice were also found using the same above methods. Along the periphery and within this seven-site cluster of the triangular lattice, a ten-site cluster of the honeycomb lattice, a nine-site cluster of the kagome lattice and a nineteen-site cluster of the decorated-honeycomb lattice were studied for their correlations. For the honeycomb calculations, the linear algebraic methods and the knowledge of the triangular lattice correlation solutions were suffi - cient. Utilizing the extended transformation theorems, the kagome lattice correlations were then found through knowledge of the honeycomb lattice correlations while the decorated-honeycomb correlations were found through knowledge of both honeycomb and kagome correlations. As principal results, exact solutions are obtained at all tempera- tures for sixty (five) even- (odd-) number correlations on the square lattice and eleven even-number correlations on the triangular lattice. Almost eighty -five even-number correlations on the honeycomb lattice, forty-eight (thirteen) even- (odd-) number correlations on the kagome lattice, and all even- (odd-) number correlations on the nineteen- (eleven-) site cluster of the decorated -honeycomb lattice are found at all temperatures.

Khatun, Mahfuza

190

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

PubMed Central

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.

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

2011-01-01

191

Aluminum chlorohydrate III: Conversion to aluminum hydroxide.  

PubMed

Bayerite, an aluminum hydroxide polymorph, readily forms when the hydroxyl to aluminum ratio of aluminum chlorohydrate is raised to 3 by titration with sodium hydroxide. Dilution of aluminum chlorhydrate solutions with water leads to the formation of gibbsite, another aluminum hydroxide polymorph. The mechanism of conversion in each instance is related to the structure of the Al13O4(OH)24(H2O)7+(12) complex. PMID:7264935

Teagarden, D L; White, J L; Hem, S L

1981-07-01

192

Optimization of cylindrical shells with compliant cores  

Microsoft Academic Search

Thin-walled, cylindrical structures are found extensively in both engineering components and in nature. The weight to load bearing ratio is a critical element of design of such structures in a variety of engineering applications, including space shuttle fuel tanks, aircraft fuselages, and offshore oil platforms. In nature, thin-walled cylindrical structures are often supported by a honeycomb- or foam-like cellular core,

Matthew A. Dawson; Lorna J. Gibson

2007-01-01

193

Broken discrete symmetries in a frustrated honeycomb antiferromagnet  

NASA Astrophysics Data System (ADS)

We study the magnetic phase diagram of the J1-J2 Heisenberg antiferromagnet on a honeycomb lattice at the strongly frustrated point J2/J1=1/2 using large-scale Monte Carlo simulations. At low temperatures we find three different field regimes, each characterized by different broken discrete symmetries. In low magnetic fields up to hc1/J1?2.9 the Z3 rotational lattice symmetry is spontaneously broken while a 1/2-magnetization plateau is stabilized around hc2/J1=4. The collinear plateau state and the coplanar state in higher fields break the Z4 translational symmetry and correspond to triple-q magnetic structures. The intermediate phase hc1

Rosales, H. D.; Cabra, D. C.; Lamas, C. A.; Pujol, P.; Zhitomirsky, M. E.

2013-03-01

194

Flat Bands and Wigner Crystallization in the Honeycomb Optical Lattice  

SciTech Connect

We study the ground states of cold atoms in the tight-binding bands built from p orbitals on a two dimensional honeycomb optical lattice. The band structure includes two completely flat bands. Exact many-body ground states with on-site repulsion can be found at low particle densities, for both fermions and bosons. We find crystalline order at n=(1/6) with a {radical}(3)x{radical}(3) structure breaking a number of discrete lattice symmetries. In fermionic systems, if the repulsion is strong enough, we find the bonding strength becomes dimerized at n=(1/2). Experimental signatures of crystalline order can be detected through the noise correlations in time of flight experiments.

Wu Congjun [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); Department of Physics, University of California, San Diego, California 92093 (United States); Bergman, Doron; Balents, Leon [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Das Sarma, S. [Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

2007-08-17

195

Recycling of automotive aluminum  

Microsoft Academic Search

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

Jirang CUI; Hans J. ROVEN

2010-01-01

196

Experimental and Analytical Evaluation of a Composite Honeycomb Deployable Energy Absorber.  

National Technical Information Service (NTIS)

In 2006, the NASA Subsonic Rotary Wing Aeronautics Program sponsored the experimental and analytical evaluation of an externally deployable composite honeycomb structure that is designed to attenuate impact energy during helicopter crashes. The concept, w...

E. L. Fasanella J. D. Littell K. E. Jackson L. G. Horta M. A. Polanco M. S. Annett S. Kellas

2011-01-01

197

Simulating the Response of a Composite Honeycomb Energy Absorber, Part 2.  

National Technical Information Service (NTIS)

NASA has sponsored research to evaluate an externally deployable composite honeycomb designed to attenuate loads in the event of a helicopter crash. The concept, designated the Deployable Energy Absorber (DEA), is an expandable Kevlar(Registered TradeMark...

E. L. Fasanella K. E. Jackson M. A. Polanco M. S. Annett

2012-01-01

198

Development of Beryllium Honeycomb Sandwich Composite for Structural and Other Related Applications.  

National Technical Information Service (NTIS)

The feasibility of fabricating large beryllium honeycomb panels was demonstrated. Both flat and curved sandwich structures were manufactured using practical, braze bonding techniques. The processes developed prove that metallurgically assembled beryllium ...

J. W. Vogan L. A. Grant

1972-01-01

199

Two-dimensional transition metal honeycomb realized: hf on ir(111).  

PubMed

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

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

2013-09-10

200

Band Structure Calculations for Two-Dimensional Plasma Photonic Crystals in Honeycomb Lattice Arrangement  

Microsoft Academic Search

We propose an approach originating from plane wave expansion method to calculate band structure for two types of honeycomb lattice two-dimensional plasma photonic crystals. The eigenvalue equations of E-polarization for two types of structures, which depend on the honeycomb lattice realization(plasma rods immersed in dielectric background or vice versa), are derived respectively. A standard linearization technique which solves the general

Xiang-Kun Kong; Shao-Bin Liu; Hai-Feng Zhang; Liang Zhou; Chun-Zao Li

2011-01-01

201

Flexural rigidity of a three-layer cylindrical shell with a honeycomb filler  

SciTech Connect

Relationships are obtained for determining the reduced flexural rigidity of three-layer cylindrical shells with a honeycomb filler of various geometrical structures. Numerical calculations are provided for determining the flexural rigidity of a cylindrical shell with different geometric parameters and a honeycomb filler. As a special case numerical values are compared for the flexural rigidity of a plate stiffened by two cross ribs by the procedure and theory suggested by S.P. Timoshenko.

Nemish, Yu.N.; Sagalyuk, I.S.; Chernopiskii, D.I. [Institute of Mechanics, Kiev (Ukraine)

1995-05-01

202

Effect of honeycomb-patterned structure on chondrocyte behavior in vitro  

Microsoft Academic Search

Chondrocytes were cultured on a honeycomb-patterned poly(lactic acid) (PLA) film in order to evaluate the effects of the honeycomb structure on chondrocytes with regard to cell proliferation, the production of sulphated glycosaminoglycans (sGAG), and morphological behavior. Cell proliferation was evaluated using the alamar blue assay, and sGAG production was spectrophotometrically quantified. Cell morphology was observed by means of optical microscopy

Yukako Fukuhira; Hiroaki Kaneko; Mika Yamaga; Masaru Tanaka; Sadaaki Yamamoto; Masatsugu Shimomura

2008-01-01

203

Relationship between adsorbed fibronectin and cell adhesion on a honeycomb-patterned film  

Microsoft Academic Search

Substratum surface morphology plays a vital roles in cellular behavior. Here, we characterized adsorption of fibronectin (Fn) as a typical cell adhesion protein onto honeycomb-patterned films made of poly(?-caprolactone) (PCL) by using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). In order to determine how cells adhere to a honeycomb-patterned film, focal adhesion of cardiac myocytes (CMYs) and

Sadaaki Yamamoto; Masaru Tanaka; Hiroshi Sunami; Keiko Arai; Aiko Takayama; Shigeko Yamashita; Yuka Morita; Masatsugu Shimomura

2006-01-01

204

Engineering the broadband spectrum of close-packed plasmonic honeycomb array surfaces  

NASA Astrophysics Data System (ADS)

Plasmonic nanostructures operating over a wide spectrum are promising candidates for broadband spectroscopic applications. While promising, spectral engineering of close-packed plasmonic honeycomb nanoantenna arrays is challenging due to the strong correlation between the particle geometry and hexagonal grid, particle coupling within unit cells, and interaction between neighboring unit cells. In this study, we demonstrate that the spectral distribution of large scale surfaces can be effectively tailored over a wideband spectral range using close-packed plasmonic honeycomb array surfaces. We discuss coupling-mechanisms responsible for the spectral response of honeycomb arrays and discuss the geometrical restrictions limiting the bandwidth of the spectral response. These limitations can be overcome with a more general honeycomb structure by introducing additional morphological parameters within the Wigner-Seitz unit cell. The proposed morphological parameters provide additional flexibility for manipulating the spectrum by relaxing geometrical restrictions due to a strong correlation between the unit-cell and nanoparticle morphology. Furthermore, we achieve spectral broadening by breaking the symmetry within a Wigner-Seitz unit cell on a hexagonal grid, rather than breaking the symmetry of the hexagonal grid itself via generalized honeycomb arrays. Additionally, we demonstrate the advantages of close-packed arrays in terms of spectral response and electric field enhancement over large surfaces. Finally, radiative far-field properties, absorptance, transmittance, and reflectance of honeycomb structures are investigated.

Tok, Rü?tü Umut; ?endur, Kür?at

2013-05-01

205

Aluminum extraction from aluminum industrial wastes  

NASA Astrophysics Data System (ADS)

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.

Amer, A. M.

2010-05-01

206

Synthesis of aluminum isopropoxide from aluminum dross  

Microsoft Academic Search

Synthetic reaction of aluminum isopropoxide, which is used as a starting material for catalytic-grade alumina, has been studied\\u000a in the presence of a small amount of HgI2, HgCl2, I2 or FeCl3 from aluminum dross. It was synthesized by solid-liquid reaction between the aluminum metal and isopropyl alcohol, using\\u000a vacuum distillation process. The purity of the synthesized aluminum isopropoxide was obtained

Seung-Joon Yoo; Ho-Sung Yoon; Hee Dong Jang; Jung-Woon Lee; Seung-Tae Hong; Min-Jae Lee; Se-Il Lee; Ki-Won Jun

2006-01-01

207

Theory of interacting electrons on the honeycomb lattice  

NASA Astrophysics Data System (ADS)

The general low-energy theory of electrons interacting via repulsive short-range interactions on graphene’s honeycomb lattice at half-filling is presented. The exact symmetry of the Lagrangian with local quartic terms for the Dirac four-component field dictated by the lattice is identified as D2×Uc(1)×time reversal, where D2 is the dihedral group, and Uc(1) is a subgroup of the SUc(2) “chiral” group of the noninteracting Lagrangian that represents translations in Dirac language. The Lagrangian describing spinless particles respecting this symmetry is parametrized by six independent coupling constants. We show how first imposing the rotational, then Lorentz, and finally chiral symmetry to the quartic terms—in conjunction with the Fierz transformations—eventually reduces the set of couplings to just two, in the “maximally symmetric” local interacting theory. We identify the two critical points in such a Lorentz and chirally symmetric theory as describing metal-insulator transitions into the states with either time reversal or chiral symmetry being broken. The latter is proposed to govern the continuous transition in both the Thirring and Nambu-Jona-Lasinio models in 2+1 dimensions and with a single Dirac field. In the site-localized “atomic” limit of the interacting Hamiltonian, under the assumption of emergent Lorentz invariance, the low-energy theory describes the continuous transitions into the insulator with either a finite Haldane’s (circulating currents) or Semenoff’s (staggered density) masses, both in the universality class of the Gross-Neveu model. The simple picture of the metal-insulator transition on a honeycomb lattice emerges at which the residue of the quasiparticle pole at the metallic and the mass gap in the insulating phase both vanish continuously as the critical point is approached. In contrast to these two critical quantities, we argue that the Fermi velocity is noncritical as a consequence of the dynamical exponent being fixed to unity by the emergent Lorentz invariance near criticality. Possible effects of the long-range Coulomb interaction and the critical behavior of the specific heat and conductivity are discussed.

Herbut, Igor F.; Juri?i?, Vladimir; Roy, Bitan

2009-02-01

208

Generalized stacking fault energy surfaces and dislocation properties of aluminum  

Microsoft Academic Search

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-

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

209

Dirac-like plasmons in honeycomb lattices of metallic nanoparticles.  

PubMed

We consider a two-dimensional honeycomb lattice of metallic nanoparticles, each supporting a localized surface plasmon, and study the quantum properties of the collective plasmons resulting from the near-field dipolar interaction between the nanoparticles. We analytically investigate the dispersion, the effective Hamiltonian, and the eigenstates of the collective plasmons for an arbitrary orientation of the individual dipole moments. When the polarization points close to the normal to the plane, the spectrum presents Dirac cones, similar to those present in the electronic band structure of graphene. We derive the effective Dirac Hamiltonian for the collective plasmons and show that the corresponding spinor eigenstates represent Dirac-like massless bosonic excitations that present similar effects to electrons in graphene, such as a nontrivial Berry phase and the absence of backscattering off smooth inhomogeneities. We further discuss how one can manipulate the Dirac points in the Brillouin zone and open a gap in the collective plasmon dispersion by modifying the polarization of the localized surface plasmons, paving the way for a fully tunable plasmonic analogue of graphene. PMID:23521276

Weick, Guillaume; Woollacott, Claire; Barnes, William L; Hess, Ortwin; Mariani, Eros

2013-03-05

210

Competing topological and Kondo insulator phases on a honeycomb lattice.  

PubMed

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

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

2013-07-03

211

Aluminum applications expand  

Microsoft Academic Search

The transportation industry has increased its demands for extruded, cast, and sheet aluminum products, while the building and construction industries have demonstrated increased interest in new aluminum applications. The unique combination of properties provided by aluminum and its alloys make aluminum one of the most versatile, economical, and attractive materials for a wide range of applications. The low density and

Lichter

1996-01-01

212

Differentiation of mesenchymal stem cells into osteoblasts on honeycomb collagen scaffolds.  

PubMed

Tissue engineering using living cells is emerging as an alternative to tissue or organ transplantation. The adult mesenchymal stem cells can be differentiated into multilineage cells, such as adipocytes, chondrocytes, or osteoblasts when cultured with specific growth factors. In the present investigation, we have studied the effect of honeycomb collagen scaffolds for the adhesion, differentiation and proliferation of bone marrow-derived mesenchymal stem cells into osteoblasts. Mesenchymal stem cells were isolated from 6-week old albino rat femur bone marrow, and cultured in alpha-MEM medium without beta-glycerophosphate and dexamethasone. Honeycomb collagen discs were prepared from bovine dermal atelocollagen, cross-linked by UV-irradiation and sterilized by heat. The honeycomb discs were placed on the culture dishes before seeding the stem cells. The cells attached quickly to the honeycomb collagen scaffold, differentiated and proliferated into osteoblasts. The differentiated osteoblasts were characterized by morphological examination and alkaline phosphatase activity. The osteoblasts also synthesized calcium-deficient hydroxyapatite (pseudo-hydroxyapatite) crystals in the culture. The mineralization was confirmed by Von Kossa staining and the crystals were analyzed by X-ray diffraction. Light microscopy and DNA measurements showed that the differentiated osteoblasts multiplied into several layers on the honeycomb collagen scaffold. The results demonstrated that the honeycomb collagen sponge is an excellent scaffold for the differentiation and proliferation of mesenchymal stem cells into osteoblasts. The data further proved that honeycomb collagen is an effective substrate for tissue engineering applications, and is very useful in the advancing field of stem cell technology and cell-based therapy. PMID:16572435

George, Joseph; Kuboki, Yoshinori; Miyata, Teruo

2006-10-20

213

The fate of aluminum in Cochnewagan Lake, Monmouth, Maine  

SciTech Connect

Aluminum salts are commonly used to improve lake water quality. The primary goal of this study is to determine the fate of the aluminum in a lake system. In June, 1986, Cochnewagan Lake was treated with aluminum sulfate and sodium aluminate to remove phosphorus from the water. As a result of this treatment, phosphorus concentrations in the lake decreased from about 20[mu]g/1 to about 10[mu]g/1, algal blooms were eliminated and the water clarity improved. Water and sediment samples were taken in the fall of 1992. The water was analyzed for pH, dissolved oxygen, alkalinity, aluminum, and total phosphate. Only trace amounts of aluminum and phosphate were found in the water column. The sediment samples that were recovered by box coring were highly bioturbated and dark brown-gray in color. After the removal of water and total organic matter, the cores showed a color gradation from light red-gray at the surface to dark gray at 8 cm. depth. The lack of aluminum in the water column and the color gradation in the cores indicates that aluminum concentrations in the sediments have increased. SEM-EDX studies will be performed on the cores to verify the presence of aluminum in the sediments.

Talbot, M. (Bates Coll., Lewiston, ME (United States). Geology Dept.)

1993-03-01

214

Strength evaluations of sinusoidal core for FRP sandwich bridge deck panels  

Microsoft Academic Search

Fiber-reinforced polymer (FRP) sandwich deck panels with sinusoidal core geometry have shown to be successful both in new construction and the rehabilitation of existing bridge decks. This paper is focused on an experimental study of the strength evaluations of a honeycomb sandwich core under out-of-plane compression and transverse shear. The sinusoidal core is made of E-glass Chopped Strand Mat (ChSM)

An Chen; Julio F. Davalos

2010-01-01

215

Detection of disbonds in a honeycomb composite structure using guided waves  

NASA Astrophysics Data System (ADS)

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.

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

2008-05-01

216

Electrochemical characterization of the nanoporous honeycomb diamond electrode as an electrical double-layer capacitor  

SciTech Connect

Electrochemical properties of nanoporous honeycomb diamond electrodes in an aqueous electrolyte were investigated. Highly ordered honeycomb diamond structures were fabricated by etching the microwave plasma-deposited diamond films using an oxygen plasma. The diamond honeycomb exhibited a wide electrochemical potential window (ca. 2.5 V), similar to the unetched diamond film. From impedance measurements, the capacitance of the diamond honeycomb film was found to be 1.97 x 10{sup {minus}3} F/cm (geometric area), which is ca. 200 times greater than that for the unetched, as-deposited surface. The results obtained with galvanostatic measurements were consistent with this value. The formation of the highly ordered porous structure, together with surface oxidation, was found to be responsible for the observed enhancement in the capacitance. The transmission line model for cylindrically porous electrodes was successfully applied to the present honeycomb structure. Based on an estimation of the capacitance of a hypothetical through-hole diamond membrane, the specific capacitance is ca. 16 F/g, which is within an order of magnitude of the range for activated carbon capacitors (100 to 400 F/g).

Honda, K.; Rao, T.N.; Tryk, D.A.; Fujishima, A.; Watanabe, M.; Yasui, K.; Masuda, H.

2000-02-01

217

A theoretical investigation on the honeycomb potential fluid.  

PubMed

A local self-consistent Ornstein-Zernike (OZ) integral equation theory (IET) is proposed to provide a rapid route for obtaining thermodynamic and structural information for any thermodynamically stable or metastable state points in the bulk phase diagram without recourse to traditional thermodynamic integration, and extensive NVT-Monte Carlo simulations are performed on a recently proposed honeycomb potential in three dimensions to test the theory's reliability. The simulated quantities include radial distribution function (rdf) and excess internal energy, pressure, excess chemical potential, and excess Helmholtz free energy. It is demonstrated that (i) the theory reproduces the rdf very satisfactorily only if the bulk state does not enter deep into a two phases coexistence region; (ii) the excess internal energy is the only one of the four thermodynamic quantities investigated amenable to the most accurate prediction by the present theory, and the simulated pressure is somewhat overestimated by the theoretical calculations, but the deviation tends to vanish along with rising of the temperature; (iii) using the structural functions from the present local self-consistent OZ IET, a previously derived local expression, due to the present author, achieves even a higher accuracy in calculating for the excess chemical potential than the exact virial pressure formula for the pressure, and the resulting excess Helmholtz free energy is in surprisingly same with the simulation results due to offset of the errors. Based on the above observations, it is suggested that it may be a good procedure to integrate the theoretical excess internal energy along the isochors to get the excess Helmholtz free energy, which is then fitted to a polynomial to be used for calculation of all of other thermodynamic quantities in the framework of the OZ IET. PMID:20942523

Zhou, Shiqi

2010-10-01

218

Suitability of lost cores in rheocasting process  

Microsoft Academic Search

When treated in pressure die casting processes the semi-solid aluminum alloys demand resilient cores which can bear the stress occurring during filling and the final pressure phase. The design of permanent cores is highly restricted in order to maintain removability. Lost cores provide the possibility of complex, undercut geometrical shapes which is mandatory for a variety of casting components. However,

H. MICHELS; M. BÜNCK; A. BÜHRIG-POLACZEK

2010-01-01

219

PROCESS FOR JACKETING A CORE  

DOEpatents

A process is given for enclosing the uranium core of a nuclear fuel element by placing the core in an aluminum cup and closing the open end of the cup over the core. As the metal of the cup is brought together in a weld over the center of the end of the core, it is extruded inwardly as internal projection into a central recess in the core and outwardly as an external projection. Thus oxide inclusions in the weld of the cup are spread out into the internal and external projections and do not interfere with the integrity of the weld.

Last, G.A.

1960-07-19

220

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

NASA Astrophysics Data System (ADS)

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.

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

2007-02-01

221

Preparation and microwave absorption properties of metal magnetic micropowder-coated honeycomb sandwich structures  

NASA Astrophysics Data System (ADS)

Radar absorbing materials with metal magnetic micropowder-coated honeycomb sandwich structures are prepared by a spray process. Metal magnetic micropowder is applied as an absorber which maintains a high absorption, and a honeycomb sandwich structure as a supporter enhancing mechanical strength. The microwave absorption properties are measured by a network analyzer system in the frequency range of 2.6-18 GHz. The concentration of the MMP and the coating thickness of the absorber affect the attenuation properties, a suitable value of them contributing to a broad bandwidth and high loss. A matching layer is introduced to the honeycomb sandwich structure on top, which allows the incident electromagnetic wave to enter and largely get attenuated through the absorbing system, increasing the microwave absorption.

He, Yanfei; Gong, Rongzhou; Cao, Heng; Wang, Xian; Zheng, Yi

2007-10-01

222

Study of the bilinear biquadratic Heisenberg model on a honeycomb lattice via Schwinger bosons  

NASA Astrophysics Data System (ADS)

We analyze the biquadratic bilinear Heisenberg magnet on a honeycomb lattice via Schwinger boson formalism. Due to their vulnerability to quantum fluctuations, non-conventional lattices (kagome, triangular and honeycomb for example) have been cited as candidates to support spin liquid states. Such states without long range order at zero temperature are known in one-dimensional spin models but their existence in higher dimensional systems is still under debate. Biquadratic interaction is responsible for various possibilities and phases as it is well-founded for one-dimensional systems. Here we have used a bosonic representation to study the properties at zero and finite low temperatures of the biquadratic term in the two-dimensional hexagonal honeycomb lattice. The results show an ordered state at zero temperature but much more fragile than that of a square lattice; the behavior at finite low temperatures is in accordance with expectations.

Moura, Antônio R.; Pereira, Afrânio R.

2013-09-01

223

Nanomechanics of Graphene, Silicene and Boron Nitride ribbons: From honeycomb structure to atomic chains  

NASA Astrophysics Data System (ADS)

This first-principles study of elastic and plastic deformation of graphene, silicene and boron nitride (BN) honeycomb nanoribbons under uniaxial tension reveals interesting features. In the course of stretching, the electronic and magnetic properties can be strongly modified. Under plastic deformation, the honeycomb structure changes irreversibly and offers a number of new structures and functionalities. Interesting cage like structures, even suspended atomic chains, a truly one-dimensional system offering unique mechanical, electronic and transport properties, can be derived between two honeycomb flakes. Present work elaborates on the recent experiments by Jin et al., Phys. Rev. Lett. 102, 205501 (2009) deriving carbon chains from graphene and furthermore predicts the similar formation of BN and Si atomic chains.

Topsakal, Mehmet; Ciraci, Salim

2010-03-01

224

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

NASA Astrophysics Data System (ADS)

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 ?m. 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 ?m showed the highest cell yield (approximately 3 times). Albumin production of mature hepatocyte on the pore sizes of 16 ?m (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 ?m) 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.

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

2008-02-01

225

Aluminum and renal osteodystrophy.  

PubMed

Evidence has emerged over the last several years indicating that aluminum accumulation in patients with chronic renal failure can cause certain forms of renal osteodystrophy, in particular osteomalacia and an aplastic lesion. The lines of evidence include epidemiological associations, chemical measurement and histological staining of bone aluminum, animal models of aluminum loading, and a favorable response to the removal of aluminum by chelation therapy. The primary sources of aluminum are dialysate solutions prepared from water with a high aluminum content and the oral ingestion of aluminum-containing phosphate binders. Desferrioxamine, a chelating agent with a high affinity for aluminum, can be used to remove aluminum during dialysis by increasing ultrafilterable plasma aluminum; preliminary results show that symptomatic patients markedly improve, both clinically and in their bone histology, after long-term chelation therapy with desferrioxamine. Treating water to ensure that aluminum levels are appropriately reduced in dialysate and the development of non-aluminum-containing phosphate binders are necessary to prevent aluminum-related osteodystrophy. PMID:3085581

Nebeker, H G; Coburn, J W

1986-01-01

226

Mechanical regulation of cellular adhesion onto honeycomb-patterned porous scaffolds by altering the elasticity of material surfaces.  

PubMed

In this report, we show the preparation of honeycomb scaffolds for cell culturing by using "breath figure" method, and we found that their mechanical and topographical properties strongly affect the adhesion of fibroblasts. By photo-cross-linking of the poly(1,2-butadiene), the hardness of the honeycomb scaffold can be successfully controlled without any surface chemical changes, and detail modulus values of scaffolds were measured by atomic force microscopy. We found that only small numbers of the cells adhered on the softer honeycomb scaffolds, which has even higher modulus value than conventional gels, comparing with flat films and a hard honeycomb scaffold. These results indicate that the elastomeric honeycomb substrates are useful for evaluating the effect of the mechanical signal-derived geometry on the transduction system of cells. PMID:23510479

Kawano, Takahito; Nakamichi, Yuki; Fujinami, So; Nakajima, Ken; Yabu, Hiroshi; Shimomura, Masatsugu

2013-03-28

227

Experimental investigation of static and thermal-mechanical bending fatigue strength of steel honeycomb sandwich beams  

NASA Astrophysics Data System (ADS)

The aim of this work is to investigate static and thermal-mechanical strength and fatigue behaviors of steel honeycomb sandwich beams through three-point bending. The bending strength limits at different experimental temperatures (room temperature, 200, 300 and 400°C, respectively) are obtained. The bending fatigue behaviors at high temperature are discussed and the fatigue test results are presented in standard S/N diagrams. Meanwhile damage and failure modes are reported and analyzed. Effects of the honeycomb cell orientation (L or W) on the maximum load and on the damage processes are also investigated.

Lu, Jie; Zou, Guang-Ping

2009-12-01

228

Coupled radiative and conductive heat transfer across honeycomb panels and through single cells  

NASA Astrophysics Data System (ADS)

In the absence of natural convection, heat flows through a gas-filled honeycomb by conduction and radiation. For the parameter ranges of interest in a plastic honeycomb inside a flat plate solar collector, the conduction and radiation are strongly coupled. The total heat transfer across the panel was studied experimentally and theoretically. The experimental approach precisely measured the total heat transfer under varying conditions. The theoretical approach proposed several models, established their governing equations, and solved the equations by either numerical or analytical methods. A model based on grey surfaces, specular sidewalls, and one-dimensional conduction yielded results within 6 percent of measurements.

Hollands, K. G. T.; Raithby, G. D.; Russell, F. B.; Wilkinson, R. G.

1984-11-01

229

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

PubMed

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

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

2013-09-13

230

Short-range correlations and cooling of ultracold fermions in the honeycomb lattice.  

PubMed

We use determinantal quantum Monte Carlo simulations and numerical linked-cluster expansions to study thermodynamic properties and short-range spin correlations of fermions in the honeycomb lattice. We find that, at half filling and finite temperatures, nearest-neighbor spin correlations can be stronger in this lattice than in the square lattice, even in regimes where the ground state in the former is a semimetal or a spin liquid. The honeycomb lattice also exhibits a more pronounced anomalous region in the double occupancy that leads to stronger adiabatic cooling than in the square lattice. We discuss the implications of these findings for optical lattice experiments. PMID:23215498

Tang, Baoming; Paiva, Thereza; Khatami, Ehsan; Rigol, Marcos

2012-11-12

231

Pattern formation in the dipolar Ising model on a two-dimensional honeycomb lattice  

NASA Astrophysics Data System (ADS)

We present Monte Carlo simulation results for a two-dimensional Ising model with ferromagnetic nearest-neighbor couplings and a competing long-range dipolar interaction on a honeycomb lattice. Both structural and thermodynamic properties are very similar to the case of a square lattice, with the exception that structures reflect the sixfold rotational symmetry of the underlying honeycomb lattice. To deal with the long-range nature of the dipolar interaction we also present a simple method of evaluating effective interaction coefficients, which can be regarded as a more straightforward alternative to the prevalent Ewald summation techniques.

Rüger, Robert; Valentí, Roser

2012-07-01

232

Flow past an array of catalyst blocks with a honeycomb structure  

SciTech Connect

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.

Bespalov, A.V.

1992-07-10

233

Huge gastric bezoar caused by honeycomb, an unusual complication of health faddism: a case report  

PubMed Central

We report a young healthy woman, who believed that the consumption of large amounts of honeycomb would lead to good health and who finally developed a huge gastric bezoar of hard consistency. The conventional endoscopic techniques failed to manage the bezoar. Using the combination of injection of hydrogen peroxide 3% solution inside the bezoar to induce disintegration and a special designed needle-knife sphincterotome (bezotome) we managed to remove the bezoar in fragments. To the best of our knowledge this is the first reported bezoar caused by honeycomb.

Katsinelos, Panagiotis; Pilpilidis, Ioannis; Katsinelos, Taxiarchis; Lazaraki, Georgia; Fasoulas, Kostas; Zavos, Christos; Kountouras, Jannis

2009-01-01

234

Electrorefining of Aluminum.  

National Technical Information Service (NTIS)

A novel inexpensive, energy-efficient approach to the electrorefining of contaminated aluminum scrap to a product suitable for recycle to wrought alloys has been investigated. The method uses a low temperature aluminum-chloride, sodium-chloride electrolyt...

J. P. Pemsler M. Dempsey

1981-01-01

235

Aluminum and Young Artists.  

ERIC Educational Resources Information Center

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)

Anderson, Thomas

1980-01-01

236

Aluminum reference electrode  

DOEpatents

A stable reference electrode for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na.sub.3 AlF.sub.6, wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution.

Sadoway, Donald R. (Belmont, MA)

1988-01-01

237

Aluminum reference electrode  

DOEpatents

A stable reference electrode is described for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na[sub 3]AlF[sub 6], wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution. 1 fig.

Sadoway, D.R.

1988-08-16

238

Honeycomb-patterned phthalocyanine films with photo-active antibacterial activities.  

PubMed

We report honeycomb-patterned phthalocyanine (Pc) films fabricated by self-assembly of dodecyloxy-azo-Zinc phthalocyanine (daZnPc) using the breath figure (BF) technique. These ultrathin Pc films exhibit a robust photo-dependent antibacterial effect against Escherichia coli (E. coli). PMID:24098884

Zhou, Xinyu; Chen, Zihui; Wang, Yuzhen; Guo, Yi; Tung, Chen-Ho; Zhang, Fushi; Liu, Xuewu

2013-10-17

239

Doubly degenerate orbital system in honeycomb lattice: Implication of orbital state in layered iron oxide  

Microsoft Academic Search

We study a doubly degenerate orbital model on a honeycomb lattice. This is a model for orbital states in multiferroic layered iron oxides. The classical and quantum models are analyzed by spin-wave approximation, Monte Carlo simulation, and Lanczos method. A macroscopic number of degeneracy exists in the classical ground state. In the classical model, a peak in the specific heat

J. Nasu; A. Nagano; M. Naka; S. Ishihara

2008-01-01

240

Effects of Defects on the In-plane Dynamic Energy Absorption of Metal Honeycombs  

Microsoft Academic Search

The in-plane dynamic energy absorption of metal honeycombs with defects consisting of missing cells are analyzed using explicit dynamic finite element method. Two types of structural defects (a single defect located in the center of the model and a double defect) are firstly introduced. Then the influence of the defects and the impact velocities on the energy absorption abilities of

Fan Weili; Zhang Xinchun

2010-01-01

241

Loading, Degradation and Repair of F-111 Bonded Honeycomb Sandwich Panels - Preliminary Study  

Microsoft Academic Search

Many of the fixed and removable panels on the RAAF F-111 aircraft are made up of bonded honeycomb sandwich panels. Experience with the RAAF fleet has shown that a serious problem exists with degradation and damage of these panels. A review of the literature was undertaken to gain an understanding of the extent of this problem. It was found that

S. Whitehead; M. McDonald; R. A. Bartholomeusz

242

Loading, Degradation and Repair of F-111 Bonded Honeycomb Sandwich Panels - Preliminary Study.  

National Technical Information Service (NTIS)

Many of the fixed and removable panels on the RAAF F-111 aircraft are made up of bonded honeycomb sandwich panels. Experience with the RAAF fleet has shown that a serious problem exists with degradation and damage of these panels. A review of the literatu...

S. Whitehead M. McDonald R. A. Bartholomeusz

2000-01-01

243

Aircraft Metal Skin Repair and Honeycomb Structure Repair; Sheet Metal Work 3: 9857.02.  

ERIC Educational Resources Information Center

|The course helps students determine types of repairs, compute repair sizes, and complete the repair through surface protection. Course content includes goals, specific objectives, protection of metals, repairs to metal skin, and honeycomb structure repair. A bibliography and post-test are appended. A prerequisite for this course is mastery of the…

Dade County Public Schools, Miami, FL.

244

Near-zero modes in condensate phases of the Dirac theory on the honeycomb lattice  

Microsoft Academic Search

We investigate a number of fermionic condensate phases on the honeycomb lattice to determine whether topological defects (vortices and edges) in these phases can support bound states with zero energy. We argue that topological zero modes bound to vortices and at edges are not only connected, but should in fact be identified. Recently, it has been shown that the simplest

Doron L. Bergman; Karyn Le Hur

2009-01-01

245

A 19.8% efficient honeycomb multicrystalline silicon solar cell with improved light trapping  

Microsoft Academic Search

This paper reports a substantially improved efficiency for a multicrystalline silicon solar cell of 19.8%. This is the highest ever reported efficiency for a multicrystalline silicon cell. The improved multicrystalline cell performance results from enshrouding cell surfaces in thermally grown oxide to reduce their detrimental electronic activity and from isotropic etching to form a hexagonally-symmetric “honeycomb” surface texture. This texture,

Jianhua Zhao; Aihua Wang; Patrick Campbell; Martin A. Green

1999-01-01

246

Evaluation of the in-service performance behavior of honeycomb composite sandwich structures  

SciTech Connect

When honeycomb composite structures are fabricated for the aerospace industry, they are designed to be closed to their operating environment for the life of the composite structure. However, once in service, this design can break down. Damage can set in motion a chain reaction of events that will ultimately degrade the mechanical integrity of the composite structure. Through thermographic analysis, the tendency of honeycomb composite structures to absorb and retain water was investigated, and an attempt was made to quantify the extent of water ingression in the Boeing 767 aircraft. Through thermographic analysis, the exterior honeycomb composite structures were found to contain less than 50 kg of water per plane. On average, over 90% of the water found on an aircraft was contained in five problematic parts, which included the outboard flap wedge, the nose landing gear doors, the main landing gear doors, the fixed upper wing panels, and the escape slide door. Kevlar lamina induced microcracking, skin porosity problems, and cracked potting compound were the root causes of water ingression and migration in these structures. Ultimately, this research will aid in the fundamental understanding and design of future honeycomb composite sandwich structures.

Shafizadeh, J.E.; Seferis, J.C.; Chesmar, E.F.; Geyer, R.

1999-12-01

247

New simple mathematical model of a honeycomb rotary absorption-type dehumidifier  

Microsoft Academic Search

A simplified mathematical model consisting of ordinary differential equations has been proposed and found to accurately predict the dynamic performance of a honeycomb rotary absorption-type dehumidifier in a beverage factory. The model was validated experimentally using the transient measurement data on the air properties at the outlets of both the dehumidification and regeneration sections. Good agreement between the predicted and

Wiwut Tanthapanichakoon; Anawut Prawarnpit

2002-01-01

248

Design for manufacture of optimal compliant topologies with honeycomb continuum representation  

Microsoft Academic Search

We present and compare two approaches to obtain optimal binary designs of compliant mechanisms that can be manufactured as is. Honeycomb representation is used to avoid singularities due to checkerboard and point flexure pathologies that appear in square cell based discretization of the domain. A Hex cell accurately models displacement and stress fields especially when approaching its non-existing state which

Anupam Saxena; Nilesh D. Mankame

2007-01-01

249

Ply drop-off effects in CFRP\\/honeycomb sandwich panels—experimental results  

Microsoft Academic Search

The results of a combined experimental and theoretical investigation of local bending effects induced by ply drop-off in CFRP\\/honeycomb sandwich panels are presented. The objective of the investigation was to validate a simple model for engineering analysis of sandwich panels with tapered face laminates presented in a previous paper. The experimental investigation was conducted by using electronic speckle pattern interferometry

O. T. Thomson; W. Rits; D. C. G. Eaton; O. Dupont; P. Queekers

1996-01-01

250

Aluminum applications expand  

SciTech Connect

The transportation industry has increased its demands for extruded, cast, and sheet aluminum products, while the building and construction industries have demonstrated increased interest in new aluminum applications. The unique combination of properties provided by aluminum and its alloys make aluminum one of the most versatile, economical, and attractive materials for a wide range of applications. The low density and high strength of some alloys permit design and construction of strong, lightweight structures that are especially beneficial for bridges, buildings, and vehicles of all kinds. Aluminum is easily cast by all foundry processes, and can be readily worked into any needed form. Furthermore, increasing production efficiencies are making aluminum more cost-competitive with other materials. This article focuses on aluminum applications in automobiles, bridges, and housing.

Lichter, J. [Aluminum Association, Washington, DC (United States)

1996-10-01

251

The response of clamped sandwich plates with lattice cores subjected to shock loading  

Microsoft Academic Search

The dynamic response of clamped circular monolithic and sandwich plates of equal areal mass and thickness has been measured by loading the plates at mid-span with metal foam projectiles. The sandwich plates comprise AISI 304 stainless steel face sheets and either AL-6XN stainless steel pyramidal core or AISI 304 stainless steel square-honeycomb lattice core. The resistance to shock loading is

G. J. McShane; D. D. Radford; V. S. Deshpande; N. A. Fleck

2006-01-01

252

Aluminum: Recycling of Aluminum Dross/Saltcake  

SciTech Connect

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.

Blazek, S.

1999-01-29

253

BONDING ALUMINUM METALS  

DOEpatents

A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

Noland, R.A.; Walker, D.E.

1961-06-13

254

Aerodynamic Performance of Conventional and Advanced Design Labyrinth Seals with Solid-Smooth Abradable, and Honeycomb Lands.  

National Technical Information Service (NTIS)

Labyrinth air seal static and dynamic performance was evaluated using solid, abradable, and honeycomb lands with standard and advanced seal designs. The effects on leakage of land surface roughness, abradable land porosity, rub grooves in abradable lands,...

D. M. Cox G. F. Holle H. L. Stocker

1977-01-01

255

Elimination of aluminum adjuvants.  

PubMed

In vitro dissolution experiments although perhaps not at typical body concentrations and temperatures demonstrated that the alpha-hydroxycarboxylic acids present in interstitial fluid (citric acid, lactic acid, and malic acid) are capable of dissolving aluminum-containing adjuvants. Amorphous aluminum phosphate adjuvant dissolved more rapidly than crystalline aluminum hydroxide adjuvant. Intramuscular administration in New Zealand White rabbits of aluminum phosphate and aluminum hydroxide adjuvants, which were labelled with 26Al, revealed that 26Al was present in the first blood sample (1 h) for both adjuvants. The area under the blood level curve for 28 days indicated that three times more aluminum was absorbed from aluminum phosphate adjuvant than aluminum hydroxide adjuvant. In vivo studies using 26Al-labelled adjuvants are relatively safe because accelerator mass spectrometry (AMS) can quantify quantities of 26Al as small as 10(-17) g. A similar study in humans would require a whole-body exposure of 0.7 microSv per year compared to the natural background exposure of 3000 microSv per year. The in vitro dissolution and in vivo absorption studies indicate that aluminum-containing adjuvants which are administered intramuscularly are dissolved by alpha-hydroxycarboxylic acids in interstitial fluid, absorbed into the blood, distributed to tissues, and eliminated in the urine. PMID:12184363

Hem, Stanley L

2002-05-31

256

A Technique to Determine Billet Core Charge Weight for P/M Fuel Tubes  

SciTech Connect

The core length in an extruded tube depends on the weight of powder in the billet core. In the past, the amount of aluminum powder needed to give a specified core length was determined empirically. This report gives a technique for calculating the weight of aluminum powder for the P/M core. An equation has been derived which can be used to determine the amount of aluminum needed for P/M billet core charge weights. Good agreement was obtained when compared to Mark 22 tube extrusion data. From the calculated charge weight, the elastomeric bag can be designed and made to compact the U3O8-Al core.

Peacock, H.B.

2001-07-02

257

Effect of pore size of honeycomb films on the morphology, adhesion and cytoskeletal organization of cardiac myocytes  

Microsoft Academic Search

Cells respond to the circumstances such as structures and chemical composition of scaffolds and cytokine. In this report, the responses of cytoskeleton and spreading of cardiac myocytes to the self-organized honeycomb-patterned films (honeycomb films) of biodegradable poly(?-caprolactone) (PCL) with several pore sizes were investigated. The expression of actin filament of cardiac myocytes was strongly dependent on the pore size ranging

Keiko Arai; Masaru Tanaka; Sadaaki Yamamoto; Masatsugu Shimomura

2008-01-01

258

Carbothermic Aluminum Production Using Scrap Aluminum As A Coolant  

DOEpatents

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.

LaCamera, Alfred F. (Trafford, PA)

2002-11-05

259

Absorption efficiency enhancement in inorganic and organic thin film solar cells via plasmonic honeycomb nanoantenna arrays.  

PubMed

We demonstrate theoretically that by embedding plasmonic honeycomb nanoantenna arrays into the active layers of inorganic (c-Si) and organic (P3HT:PCBM/PEDOT:PSS) thin film solar cells, absorption efficiency can be improved. To obtain the solar cell absorption spectrum that conforms to the solar radiation, spectral broadening is achieved by breaking the symmetry within the Wigner-Seitz unit cell on a uniform hexagonal grid. For optimized honeycomb designs, absorption efficiency enhancements of 106.2% and 20.8% are achieved for c-Si and P3HT:PCBM/PEDOT:PSS thin film solar cells, respectively. We have demonstrated that the transverse modes are responsible for the enhancement in c-Si solar cells, whereas both the longitudinal and transverse modes, albeit weaker, are the main enhancement mechanisms for P3HT:PCBM/PEDOT:PSS solar cells. For both inorganic and organic solar cells, the absorption enhancement is independent of polarization. PMID:24104664

Tok, Rü?tü Umut; Sendur, Kür?at

2013-08-15

260

Biomimetic surface modification of honeycomb films via a "grafting from" approach.  

PubMed

Hydrophobic isoporous membranes were fabricated using the "breath figure" method from polystyrene stars synthesized via ATRP. The living polymer chain ends at the surface of the films were then used, without further modification, in a "grafting-from" approach to grow surface-linked polyglycidyl methacrylate chains under conditions that maintained the regular honeycomb structure. This versatile functional surface was then used as a platform to build a small library of surfaces using a variety of simple chemistries: (i) the acid hydrolysis of the epoxide to form bis-alcohol groups and (ii) utilizing the "click-like" epoxide-amine reaction to functionalize the surface with a model biomolecule-(biotinamido)pentylamine. The successful modifications were confirmed by a combination of spectroscopic and biological means. Changes in the growth characteristics of nonmotile Psychrobacter sp. strain, SW5, on the honeycomb films, provided further evidence confirming changes in the hydrophobicity of the surface upon grafting. PMID:20597547

Nyström, Daniel; Malmström, Eva; Hult, Anders; Blakey, Idriss; Boyer, Cyrille; Davis, Thomas P; Whittaker, Michael R

2010-08-01

261

Nature of the spin liquid state of the Hubbard model on a honeycomb lattice.  

PubMed

Recent numerical work [Z. Y. Meng et al., Nature (London) 464, 847 (2010)] indicates the existence of a spin liquid (SL) phase that intervenes between the antiferromagnetic and semimetallic phases of the half filled Hubbard model on a honeycomb lattice. To better understand the nature of this exotic phase, we study the quantum J(1)-J(2) spin model on the honeycomb lattice, which provides an effective description of the Mott insulating region of the Hubbard model. Employing the variational Monte Carlo approach, we analyze the phase diagram of the model. We find three phases-antiferromagnetic, an unusual Z(2) SL state, and a dimerized state with spontaneously broken rotational symmetry. We identify the Z(2) SL state as the likely candidate for the SL phase of the Hubbard model. PMID:21929202

Clark, B K; Abanin, D A; Sondhi, S L

2011-08-17

262

Specific lipid-protein interactions in a novel honeycomb lattice structure of bacteriorhodopsin.  

PubMed

In the purple membrane of Halobacterium salinarium, bacteriorhodopsin trimers are arranged in a hexagonal lattice. When purple membrane sheets are incubated at high temperature with neutral detergent, membrane vesicularization takes place, yielding inside-out vesicles with a diameter of 50 nm. The vesicular structure becomes unstable at low temperature, where successive fusion of the vesicles yields a crystal which is composed of stacked planar membranes. X-ray crystallographic analysis reveals that the bacteriorhodopsin trimers are arranged in a honeycomb lattice in each membrane layer and that neighbouring membranes orient in opposite directions. The native structure of the trimeric unit is preserved in the honeycomb lattice, irrespective of alterations in the in-plane orientation of the trimer. One phospholipid tightly bound to a crevice between monomers in the trimeric unit is suggested to act as a glue in the formation of the trimer. PMID:10393291

Sato, H; Takeda, K; Tani, K; Hino, T; Okada, T; Nakasako, M; Kamiya, N; Kouyama, T

1999-07-01

263

Study of Band Structure of Two-Dimensional Anisotropic Honeycomb Photonic Crystals  

NASA Astrophysics Data System (ADS)

Using the plane wave expansion method, we have calculated, for both E and H polarizations, the band structure of 2D anisotropic photonic crystals with honeycomb lattice composed of anisotropic tellurium (Te) rods embedded in air background. The two rods in the unit cell are chosen square and circular in shape. Here, from a practical point of view, in order to obtain maximum band gaps, we have also studied the band structure as a function of size of rods.

Sedghi, A.; Soufiani, A. Rounaghi

2013-10-01

264

Observations on cathode aging (Malter effect) in honeycomb drift chambers under high irradiation load  

Microsoft Academic Search

The Outer Tracking (OTR) system for the HERA-B detector at DESY consists of honeycomb drift tubes with cathodes folded from Pokalon-C foil, a soot-containing polycarbonate, operating with CF4-containing drift gas. The first prototypes, exposed to radiation in HERA-B, suffered radiation damage ascribed to the Malter effect (ignition of self-sustaining discharges). We present the results of investigations of cathode surface properties

K. Berkhan; G. Bohm; H. Kolanoski; A. Schreiner; U. Schwanke; V. Souvorov; C. Stegmann; U. Uwer; M. Walter

2003-01-01

265

Detecting damage in full-scale honeycomb sandwich composite curved fuselage panels through frequency response  

Microsoft Academic Search

Preliminary tests were conducted using frequency response (FR) characteristics to determine damage initiation and growth in a honeycomb sandwich graphite\\/epoxy curved panel. This investigation was part of a more general study investigating the damage tolerance characteristics of several such panels subjected to quasi-static internal pressurization combined with hoop and axial loading. The panels were tested at the Full-Scale Aircraft Structural

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

2008-01-01

266

Critical surface of the Blume-Emery-Griffiths model on the honeycomb lattice  

Microsoft Academic Search

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

Leh-Hun Gwa; F. Y. Wu

1991-01-01

267

Glass fiber-reinforced polymer\\/steel hybrid honeycomb sandwich concept for bridge deck applications  

Microsoft Academic Search

Glass fiber-reinforced polymer (GFRP) bridge decks possess inherently high strength-to-weight ratios, but relatively low effective elastic moduli. As a result, serviceability issues govern GFRP bridge deck design. Therefore, the objective of this study was to increase the stiffness of a commercial GFRP honeycomb sandwich panel through the inclusion of steel within the cross section.GFRP-steel hybrid parametric studies were conducted to

Nicolas J. Lombardi; Judy Liu

2011-01-01

268

Glass fiber-reinforced polymer\\/steel hybrid honeycomb sandwich concept for bridge deck applications  

Microsoft Academic Search

Glass fiber-reinforced polymer (GFRP) materials possess inherently high strength-to-weight ratios, but their elastic moduli are low relative to civil engineering (CE) construction materials. As a result, serviceability issues are what govern GFRP material design in the CE bridge industry. Therefore, the study objective was to increase the stiffness of a commercial GFRP honeycomb sandwich panel through the inclusion of steel

Nicolas J Lombardi

2008-01-01

269

NON-DESTRUCTIVE TESTING OF HONEYCOMB SANDWICH STRUCTURES USING ELASTIC WAVES  

Microsoft Academic Search

A new method for accurately measuring localized phase velocities in reverberant panels in the frequency range 5–50 kHz is applied to the problem of the non-destructive testing of honeycomb sandwich structures. First, a brief description of the elastic and vibration properties of these materials is given. With access to only one side of the panel, the method is shown to

S. Thwaites; N. H. Clark

1995-01-01

270

Iron oxide-based honeycomb catalysts for the dehydrogenation of ethylbenzene to styrene  

Microsoft Academic Search

Corning has recently developed a novel extrusion method to make bulk transition metal oxide honeycomb catalysts. One area of effort has been iron oxide-based catalysts for the dehydrogenation of ethylbenzene to styrene, a major chemical process that yields worldwide 20MM tons\\/yr. In industry, the monomer is synthesized mostly in radial-flow fixed-bed reactors. Because of the high cross-sectional area for flow

William P Addiego; Wei Liu; Thorsten Boger

2001-01-01

271

Experimental Investigation on the Co-Cure Processing of Honeycomb Structure with Self-Adhesive Prepreg  

Microsoft Academic Search

To optimize the co-cure processing of honeycomb sandwich composites, three parameters, namely the ramp rate, pressure and\\u000a application time of pressure were varied. Meanwhile, the inner pressure profile was on-line monitored to reveal the influence\\u000a mechanism the final quality of the samples. Fillet size, resin content and porosity were used to characterize the bonding\\u000a performance and panel quality. In addition,

Chongxin Yuan; Min Li; Zuoguang Zhang; Yizhuo Gu

2008-01-01

272

Influence of polymer elasticity on the formation of non-cracking honeycomb films.  

PubMed

Non-planar non-cracking honeycomb (HC) structures are prepared from star polymers with high glass transition temperatures (T(g) ) and relatively low Young's moduli (E). This study demonstrates that the Young's modulus of a polymer is a more important factor than the glass transition temperature for determining the occurrence of cracking during HC film formation on non-planar surfaces. PMID:22729948

Zhang, Zhou; Hughes, Timothy C; Gurr, Paul A; Blencowe, Anton; Hao, Xiaojuan; Qiao, Greg G

2012-06-22

273

Design and experimental test of a novel surface blackbody with honeycombs  

Microsoft Academic Search

With the development of IR technology, there are increasing needs for surface BB. A novel surface blackbody (BB) with honeycombs for calibrating infrared (IR) imaging ranging 240~450K in the long IR wavelength bands of 3~15?m is developed and its features are experimental tested. Traditional radiant source of BB cavities are often with simple axisymmetrical structure, such as cylinder, cone, cylinder-cone,

Hong Zhang; Hui Zhu

2010-01-01

274

Multi-spin exchange model for a quantum spin liquid on the honeycomb lattice  

Microsoft Academic Search

Recently, a possible quantum spin liquid (QSL) state has been found through quantum Monte Carlo studies of Hubbard model on the honeycomb lattice. The obtained QSL does not show long range correlation of any known type, which has a finite spin gap and a short range dimer-dimer correlation pattern resembling the short range resonant-valence-bond (RVB) state. Given the intensive current

Yi-Fei Wang; Donna Sheng; Chang-De Gong

2011-01-01

275

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

Microsoft Academic Search

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

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

2008-01-01

276

Near-zero modes in condensate phases of the Dirac theory on the honeycomb lattice  

Microsoft Academic Search

We investigate a number of fermionic condensate phases on the honeycomb\\u000alattice, to determine whether topological defects (vortices and edges) in these\\u000aphases can support bound states with zero energy. We argue that topological\\u000azero modes bound to vortices and at edges are not only connected, but should in\\u000afact be \\\\emph{identified}. Recently, it has been shown that the simplest

Doron L. Bergman; Karyn Le Hur

2009-01-01

277

Development of a smart-skin phased array system with a honeycomb sandwich microstrip antenna  

Microsoft Academic Search

We develop a smart-skin phased array antenna (PAA) with a scanning beam and cover the design, fabrication and testing of the smart-skin antenna structure, the phase shifter and electronic beam scanning. The smart skin is an organic honeycomb sandwich structure in which microstrip antennas are embedded that radiate a radio-frequency (RF) signal. The structure has excellent structural performance as a

Seong Ho Son; Soon Young Eom; Woonbong Hwang

2008-01-01

278

Degassing of Aluminum Alloys Using Ultrasonic Vibration  

Microsoft Academic Search

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. ;\\u000a;\\u000aThe goals of the project described here were to evaluate core principles, establish a quantitative basis for the ultrasonic degassing of aluminum alloy melts,

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

2006-01-01

279

Aluminum: Reducing chloride emissions from aluminum production  

SciTech Connect

Reynolds Metals Company (RMC), with assistance from a NICE{sup 3} grant, is developing for commercialization a closed-loop control process that greatly reduces chlorine emissions and increases plant efficiency while maintaining metal quality. The process still utilizes chlorine to remove impurities during aluminum processing, but is more effective than current methods. With the new technology chlorine in the stack is monitored and input chlorine is adjusted continuously. This optimization of chlorine use results in substantially less waste because less chlorine has to be bought or produced by aluminum manufacturers. This innovation is a significant improvement over conventional aluminum treatments, in which chlorine is injected in a more costly and wasteful manner. By the year 2010, the new technology has the potential to reduce the energy it takes to create chlorine by 8.4 billion Btu per year and to cut greenhouse gas emissions by 1,377 tons per year.

Simon, P.

1999-09-29

280

Chemistry of soil aluminum  

Microsoft Academic Search

Better understanding of soil aluminum has had dramatic effects on the interpretation of many aspects of soil chemistry. Aluminum is a Group III element, metallic in nature, and exhibits both ionic and cuvaient bonding. It is the most plentiful of all metallic cations of the earth's crust. It is released from octahedral coordination with oxygen in minerals by weathering processes.

E. O. McLean

1976-01-01

281

Aluminum-Air Battery.  

National Technical Information Service (NTIS)

An investigation of aluminum alloyed with small amounts (less than 0.1%) of In, Ga, and Tl in an aluminum-air battery with 2M NaCl as the electrolyte is reported. The tested laboratory model of the battery with a total weight of about 500 g operated at a ...

A. Despic D. Drazic S. Zecevic

1979-01-01

282

Anodizing Aluminum with Frills.  

ERIC Educational Resources Information Center

|"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…

Doeltz, Anne E.; And Others

1983-01-01

283

Anodizing Aluminum with Frills.  

ERIC Educational Resources Information Center

"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…

Doeltz, Anne E.; And Others

1983-01-01

284

Voluntary Aluminum Industrial Partnership  

Microsoft Academic Search

A very successful record of emissions reduction has been achieved through a voluntary program developed between U.S. primary aluminum producers and the U.S. Environmental Protection Agency (EPA). The program is currently in the final year of the first agreement period, and work is under way to develop a new memorandum of understanding to achieve future reductions. Primary aluminum producers working

Jerry Y. Marks

285

Nonstoichiometric Dislocation Cores in a-Alumina  

SciTech Connect

Little is known about dislocation core structures in oxides, despite their central importance in controlling electrical, optical, and mechanical properties. It has often been assumed, on the basis of charge considerations, that a nonstoichiometric core structure could not exist. We report atomic-resolution images that directly resolve the cation and anion sublattices in alumina (a-Al2O3). A dissociated basal edge dislocation is seen to consist of two cores; an aluminum column terminates one partial, and an oxygen column terminates the second partial. Each partial core is locally nonstoichiometric due to the excess of aluminum or oxygen at the core. The implication for mechanical properties is that the mobile high-temperature dislocation core structure consists of two closely spaced partial dislocations. For basal slip to occur, synchronized motion of the partials on adjacent planes is required.

Shibata, Naoya [University of Tokyo, Tokyo, Japan

2007-01-01

286

Oxidative decomposition of o-dichlorobenzene over V 2O 5\\/TiO 2 catalyst washcoated onto wire-mesh honeycombs  

Microsoft Academic Search

A novel wire-mesh (WM) honeycomb reactor was developed and tested for the oxidative decomposition of 1,2-dichlorobenzene (o-DCB) in air over V2O5\\/TiO2 catalyst. The WM-honeycomb substrate had triangle-shaped channels and was fabricated from flat and corrugated carbon steel wire-meshes (20 Taylor mesh). The geometric surface area of the substrate is similar to that of a ceramic honeycomb module with square channels

Ki-Suk Chung; Zhidong Jiang; Bong-Seok Gill; Jong-Shik Chung

2002-01-01

287

Plasma etch chemistry of aluminum and aluminum alloy films  

Microsoft Academic Search

The chemistry occurring in glow discharges used to etch aluminum and aluminum alloy films is examined and is related to recurring problms such as initiation and reproducibility of etching, polymer or residue formation, photoresist degradation, aluminum corrosion, and safety aspects. The relative effects of different etch gases on these problems is discussed in light of aluminum surface chemistry and gas-phase

Dennis W. Hess

1982-01-01

288

The application of neutron radioscopy to aluminum-lithium alloy target elements  

Microsoft Academic Search

A mutual interest in the characterization and use of aluminum-lithium alloys within the Department of Army and the Department of Energy has led to research in the use of neutron radioscopy for rapid assessment of the extent of aluminum-lithium-6 alloy in core ends of aluminum-clad alloy target tubes. The Army's low-flux mobile neutron radioscopy system was employed in studies of

J. J. Antal; A. S. Marotta; S. R. Salaymeh; T. P. Vasrallo

1988-01-01

289

Environmental deterioration of aluminum-aluminum connections  

Microsoft Academic Search

Wire splice connections are investigated for deterioration due to environmental factors. The tested splices of solid aluminum and copper wires are made using twist-on connectors. Some specimen groups are exposed in a chamber at 35°C and 90% relative humidity. Additional groups are exposed for ten years to a normal application environment. There is no current flow except when potential drop

Jesse Aronstein

1992-01-01

290

Oxidation of Aluminum Nitride.  

National Technical Information Service (NTIS)

The oxidation characteristics of hot-pressed aluminum nitride were investigated. Three materials were studied in the temperature range 1100 to 1400 C in 15, 150, and 400 torr oxygen environments. The oxidation process was evaluated using thermogravimetric...

B. A. Rasmussen

1973-01-01

291

Fractography of Aluminum 7075.  

National Technical Information Service (NTIS)

The fractography of aluminum 7075, fractured in a 3% NaCl aqueous solution was characterized. Stress-corrosion cracking was found to occur through intermetallic precipitates present along the grain boundaries.

G. H. Koch

1977-01-01

292

Corrosion Inhibitors for Aluminum.  

ERIC Educational Resources Information Center

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)

Muller, Bodo

1995-01-01

293

Aluminum powder metallurgy processing.  

National Technical Information Service (NTIS)

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 a...

J. F. Flumerfelt

1999-01-01

294

Aluminum-air battery  

Microsoft Academic Search

Aluminum alloyed with small amounts (less than 0.1%) of In, Ga, and Tl in an aluminum air battery with 2M NaCl as the electrolyte is reported. The tested laboratory model of the battery with a total weight of about 500 g operated at a total current of 8 A (j = 30 mA\\/cu cm) and a voltage of about 1

A. R. Despic; D. Drazic; S. Zecevic

1979-01-01

295

Aluminum Fluidity in Casting  

NASA Astrophysics Data System (ADS)

The understanding and control of fluidity is, and has been, a major aspect of foundry technology development. This paper reviews the progress made in this area over the years as it applies to aluminum castings. As a result of this development, thin-wall, high-integrity aluminum castings which were previously not thought possible have been produced. Further work in this area is expected to allow metal-matrix composites to fulfill their technical and economic promise.

Mollard, Francois R.; Flemings, Merton C.; Niyama, Eisuke F.

1987-11-01

296

CORROSION PROTECTION OF ALUMINUM  

DOEpatents

Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred.

Dalrymple, R.S.; Nelson, W.B.

1963-07-01

297

CORROSION PROTECTION OF ALUMINUM  

DOEpatents

Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred. (D.C.W.)

Dalrymple, R.S.; Nelson, W.B.

1963-07-01

298

Cast Tenzaloy aluminum optics  

NASA Astrophysics Data System (ADS)

Since the early sixties, cast aluminum optics has held out a promise of low cost, durability, lightweight, ease of manufacture, the possibility of welding together sections to form large optics and a good match of some astronomical programs such as photometry. Needless to say, this rosy future has been fraught with difficulties. Poor short-term stability, sensitivity to temperature, porosity, bimetallic warping, soft optical surface, poor specularity, nickel adhesion problems, poor image quality, and the inability to generate aspherics, have all contributed to the bad name cast aluminum optics has acquired over the years. With the advent of improved aluminum alloys, long-term dimensional stability data, advances in adaptive optics and the need for very large monolithic mirrors with a relatively low handling risk, aluminum optics deserve another look. This paper is a collection of some of the early attempts to build cast aluminum mirrors using the stable alloy, Tenzaloy. The results of those efforts are discussed together with recommendations for future aluminum metal mirror work.

Forbes, Fred F.

1993-10-01

299

Sex inversion of sexually immature honeycomb grouper (Epinephelus merra) by aromatase inhibitor.  

PubMed

Previous studies have shown that estrogen plays an important role in sex change of protogynous honeycomb grouper, and that the treatments with aromatase inhibitor (AI) cause estrogen depletion and complete sex inversion of pre-spawning females into functional males. In the present study, we examined whether AI causes sex inversion of sexually immature females. Female honeycomb groupers were implanted with various doses of Fadrozole (0, 100, 500 and 1000 microg/fish) in the non-breeding season, and resultant changes in the gonadal structures and the plasma levels of sex steroid hormones (estradiol-17 beta, E2; testosterone, T; 11-ketotestosterone, 11-KT) were examined three months after implantation. Vehicle-implanted groups did not change sex, while 100 and 500 microg AI-implanted groups had turned into transitionals with intersex gonad. In contrast, the highest dose receiving group exhibited both transitional and male phases. Transitional phase gonad had atretic oocytes and spermatogenic germ cells at the late stages of spermatogenesis, while male phase testis contained spermatozoa accumulated in the seminiferous tubules. All males released sperm upon slight pressure on the abdomen. In the AI-implanted fish, plasma levels of E2 decreased in a dose-dependent manner, while the levels of 11-KT were high in the highest dose receiving group. Present results suggest that estrogen plays an important role in sex change of protogynous honeycomb grouper, and that treatments with AI potentially inhibits endogenous E2 production in vivo, causing oocyte degeneration and subsequently the sex inversion from female to male. The Fadrozole could be an important tool for manipulating the sex of hermaphrodite fishes. PMID:15056925

Bhandari, Ramji Kumar; Komuro, Hiroki; Higa, Mikihiko; Nakamura, Masaru

2004-03-01

300

Unpaired Majorana modes in the gapped phase of Kitaev's honeycomb model  

NASA Astrophysics Data System (ADS)

We study the gapped phase of Kitaev's honeycomb model (a Z2 spin liquid) in the presence of lattice defects. We find that some dislocations and bond defects carry unpaired Majorana fermions. Physical excitations associated with these defects are (complex) fermion modes made out of two (real) Majorana fermions connected by a Z2 gauge string. The quantum state of these modes is robust against local noise and can be changed by winding a Z2 vortex around a dislocation. The exact solution respects gauge invariance and reveals a crucial role of the gauge field in the physics of Majorana modes.

Petrova, Olga; Mellado, Paula; Tchernyshyov, Oleg

2013-10-01

301

Energy gap of tight-binding electrons on generalized honeycomb lattice  

NASA Astrophysics Data System (ADS)

So as to clearly understand the energy band gap of graphene, we study the energy band of tight-binding electrons on a honeycomb lattice with on-site potentials ?A and ?B on sublattices A and B, nearest-neighbor transfer integrals ta, tb and tc, and next-nearest-neighbor transfer integrals t2a, t2b, t2c, t2d, t2e and t2f, where t2a, t2b and t2C are transfer integrals between sublattice A, and t2d, t2e and t2f are transfer integrals between sublattice B.

Kishigi, Keita; Takeda, Ryuichi; Hasegawa, Yasumasa

2008-10-01

302

Quantum Monte Carlo study of the half-filled Hubbard model on the honeycomb lattice  

NASA Astrophysics Data System (ADS)

The half-filled Hubbard model on the honeycomb lattice is investigated by numerically exact large-scale quantum Monte Carlo simulations for lattice sizes up to 2592 sites. By performing careful finite-size scaling for the spin-spin correlation functions, calculated with a high degree of accuracy, we find that the ground state is antiferromagnetically long-range ordered at U/t = 4, where U is the on-site Hubbard interaction and t is the nearest neighbor hopping. Our result is in sharp contrast to a recent report [Meng et al., Nature 464, 847 (2010)], where instead strong evidence of spin liquid behavior is found.

Otsuka, Yuichi; Yunoki, Seiji; Sorella, Sandro

2013-08-01

303

Critical behavior of self-assembled rigid rods on triangular and honeycomb lattices.  

PubMed

Using Monte Carlo simulations and finite-size scaling analysis, the critical behavior of self-assembled rigid rods on triangular and honeycomb lattices at intermediate density has been studied. The system is composed of monomers with two attractive (sticky) poles that, by decreasing temperature or increasing density, polymerize reversibly into chains with three allowed directions and, at the same time, undergo a continuous isotropic-nematic (IN) transition. The determination of the critical exponents, along with the behavior of Binder cumulants, indicate that the IN transition belongs to the q=1 Potts universality class. PMID:20942550

López, L G; Linares, D H; Ramirez-Pastor, A J

2010-10-01

304

Spectroscopic and vibronic properties of dehydrogenated polycyclic aromatic hydrocarbons and honeycomb carbon clusters  

NASA Astrophysics Data System (ADS)

Spectroscopic and vibronic properties of dehydrogenated polycyclic aromatic hydrocarbons and hexagonal carbon clusters have been calculated and compared on the basis of the MO/8E method which has been developed as a convenient technique for vibrational and vibronic properties of benzenoid polycyclic hydrocarbons with honeycomb carbon network. IR spectra of C6Hx (x=0-6) crucially depend on the structures, whereas vibronic spectra are rather similar between an aromatic hydrocarbon such as C6H6 and C24H12 and their dehydrogenated species or the corresponding carbon cluster.

Yamada, Megumi; Ohno, Koichi

2006-09-01

305

A honeycomb lattice model simulating the surface states of topological insulators.  

PubMed

A honeycomb lattice model exhibiting the quantum spin-Hall effect is proposed, where the low-energy properties of the electrons are mainly determined by the energy spectrum in the vicinity of the ? point, for suitable parameters. The nontrivial topology of the energy bands is revealed by calculating the Chern numbers, Berry curvature distribution, and edge state spectrum. We further show that in the continuum limit, the model Hamiltonian is equivalent to the effective model for the surface states in thin films of three-dimensional topological insulators. As a consequence, this lattice model provides a useful tool for numerical simulation of the physical properties of the surface states. PMID:22481025

Xu, Zhong; Yang, Yunyou; Sheng, L; Xing, D Y

2012-04-05

306

Honeycomb pattern formation by laser-beam filamentation in atomic sodium vapor.  

PubMed

We have observed transverse pattern formation leading to highly regular structures in both the near and far fields when a near-resonant laser beam propagates without feedback through an atomic sodium vapor. One example is a regular far-field honeycomb pattern, which results from the transformation of the laser beam within the vapor into a stable three-lobed structure with a uniform phase distribution and highly correlated power fluctuations. The predictions of a theoretical model of the filamentation process are in good agreement with these observations. PMID:11909401

Bennink, Ryan S; Wong, Vincent; Marino, Alberto M; Aronstein, David L; Boyd, Robert W; Stroud, C R; Lukishova, Svetlana; Gauthier, Daniel J

2002-02-27

307

Rotordynamic analysis of annular honeycomb-stator turbulent gas seals using a new friction-factor model based on flat plate tests  

NASA Astrophysics Data System (ADS)

A flat plate tester with various honeycomb geometries has been extended to develop a better understanding of the friction-factor behavior of honeycomb surfaces. The friction-factor-jump phenomenon, which is characterized by the dramatic drop and then rise of the friction-factor with increasing Reynolds number, has been explained by acoustic excitation of a large scale coherent flow structure from pressure fluctuation measurements inside the honeycomb cavities. A new friction-factor model based on the flat-plate-test results has been developed as a function of Mach number, dimensionless pressure, and honeycomb geometry variables. A rotordynamic analysis has been developed for centered, turbulent-annular honeycomb-stator seals incorporating the new empirical friction-factor model for honeycomb-stator surfaces. The validity of the new analysis in predicting the rotordynamic and leakage characteristics has been compared to Moody's friction-factor model analysis and experimental data for a short (L/D = 1/6, 25.4 mm long) seal and a longer (L/D = 1/3, 50.8 mm long) seal. The comparisons show that the new honeycomb friction-factor model greatly improves the predictions of leakage and rotordynamic coefficients compared to Moody's friction-factor model for both the short and longer seal, especially, for direct stiffness and cross-coupled stiffness. The new honeycomb friction-factor model predicts leakage and rotordynamic coefficients better for the short than the longer seals.

Ha, Tae Woong

1992-01-01

308

Aluminum/Magnesium 3D-Printing Rapid Prototyping.  

National Technical Information Service (NTIS)

A 3D Printing Rapid Prototyping process using Al/Mg particles coated with a metal (i.e. copper, nickel, zinc, or tin) that (1) prevents oxidation of the Al/Mg particles, and (2) either alone, or when alloyed with the aluminum or magnesium core metal, melt...

J. E. Hetzner W. F. Jandeska

2004-01-01

309

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)

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

Geber, Thomas; Oshima, Chuhei

2012-08-01

310

Aluminum automotive space frames  

SciTech Connect

Design of aluminum structures is to a new topic. Aircraft makers have successfully solved difficult structural problems with a high degree of understanding and reliability. Other transportation modes such as trucks, trailers, and railcars have faced structural problems with some emphasis on high- and low-cycle fatigue of welded aluminum structures. However, the automotive market places stringent engineering demands on materials and superimposes demanding cost constraints. A project was instituted at Reynolds Metals Co. to investigate the opportunities for the cost-effective application of aluminum to automotive spaceframes. Several areas were recognized as key to the success of this application. They were: equivalent or superior structural stiffness of the assembly to existing steel unibody and/or steel spaceframe vehicles; effective joining of spaceframe members; equivalent or superior crashworthiness of the assembly; weight savings; flexibility; and low-cost approach aimed at effective manufacturing. To gain experience with the key aspects in a practical environment, the experience of current builders of steel tube frame chassis was explored. These chassis are typically used in low-volume vehicles requiring torsional stiffness, excellent crashworthiness, and exterior body-style flexibility. A model was developed using finite element methods that accurately predicts mass and stiffness of frames. An effective aluminum space frame was generated which was 7.5% stiffer and more than 20% lighter than the steel frame, with stresses kept below the fatigue limit for aluminum welds.

NONE

1995-08-01

311

Safety evaluation of dietary aluminum.  

PubMed

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 barriers (skin, lungs, gastrointestinal tract) to reduce the systemic absorption of aluminum ingested from water, foods, drugs, and air. The small amount of aluminum (<1%) that is systemically absorbed is excreted principally in the urine and, to a lesser extent, in the feces. No reports of dietary aluminum toxicity to healthy individuals exist in the literature. Aluminum can be neurotoxic, when injected directly into the brains of animals and when accidentally introduced into human brains (by dialysis or shrapnel). A study from Canada reports cognitive and other neurological deficits among groups of workers occupationally exposed to dust containing high levels of aluminum. While the precise pathogenic role of aluminum in Alzheimer's disease (AD) remains to be defined, present data do not support a causative role for aluminum in AD. High intake of aluminum from antacid for gastrointestinal ailments has not been reported to cause any adverse effects and has not been correlated with neurotoxicity or AD. Foods and food ingredients are generally the major dietary sources of aluminum in the United States. Cooking in aluminum utensils often results in statistically significant, but relatively small, increases in aluminum content of food. Common aluminum-containing food ingredients are used mainly as preservatives, coloring agents, leavening agents, anticaking agents, etc. Safety evaluation and approval of these ingredients by the Food and Drug Administration indicate that these aluminum-containing compounds are safe for use in foods. PMID:11259180

Soni, M G; White, S M; Flamm, W G; Burdock, G A

2001-02-01

312

Spin-orbital locking, emergent pseudo-spin and magnetic order in honeycomb lattice iridates  

NASA Astrophysics Data System (ADS)

The nature of the effective spin Hamiltonian and magnetic order in the honeycomb iridates is explored by considering a trigonal crystal field effect and spin-orbit (SO) coupling. Starting from a Hubbard model, an effective spin Hamiltonian is derived in terms of an emergent pseudo-spin-1/2 moment in the limit of large trigonal distortions and SO coupling. The present pseudo-spins arise from a spin-orbital locking and are different from the jeff = 1/2 moments that are obtained when the SO coupling dominates and trigonal distortions are neglected. The resulting spin Hamiltonian is anisotropic and frustrated by further neighbour interactions. Mean-field theory suggests a ground state with four-sublattice zigzag magnetic order in a parameter regime that can be relevant to the honeycomb iridate compound Na2IrO3, where a similar magnetic ground state has recently been observed. Various properties of the phase, the spin-wave spectrum and experimental consequences are discussed. The present approach contrasts with the recent proposals to understand iridate compounds starting from the strong SO coupling limit and neglecting non-cubic lattice distortions.

Bhattacharjee, Subhro; Lee, Sung-Sik; Kim, Yong Baek

2012-07-01

313

Doubly degenerate orbital system in honeycomb lattice: Implication of orbital state in layered iron oxide  

NASA Astrophysics Data System (ADS)

We study a doubly degenerate orbital model on a honeycomb lattice. This is a model for orbital states in multiferroic layered iron oxides. The classical and quantum models are analyzed by spin-wave approximation, Monte Carlo simulation, and Lanczos method. A macroscopic number of degeneracy exists in the classical ground state. In the classical model, a peak in the specific heat appears at a temperature which is much lower than the mean-field ordering one. Below this temperature, the angle of orbital pseudospin is fixed, but conventional orbital orders are not suggested. The degeneracy in the ground state is partially lifted by thermal fluctuation. We suggest a role of zero-dimensional fluctuation in hexagons on a low-temperature orbital structure. Lifting of the degeneracy also occurs at zero temperature due to the quantum zero-point fluctuation. We show that the ground-state wave function is well represented by a linear combination of the states where a honeycomb lattice is covered by nearest-neighboring pairs of orbitals with the minimum bond energy.

Nasu, J.; Nagano, A.; Naka, M.; Ishihara, S.

2008-07-01

314

Aromatase inhibitor induces complete sex change in the protogynous honeycomb grouper (Epinephelus merra).  

PubMed

The protogynous hermaphrodite fish change sex from female to male at the certain stages of life cycle. The endocrine mechanisms involved in gonadal restructuring throughout protogynous sex change are not clearly understood. In the present study, we implanted maturing female honeycomb groupers with nonsteroidal aromatase inhibitor (AI), Fadrozole (0, 1, and 10 mg/fish) and examined changes in gonadal structures and serum levels of sex steroid hormones 2(1/2) months after implantation. The ovaries of control females had oocytes undergoing active vitellogenesis, whereas AI caused females to develop into functional males. These males had testes, which were indistinguishable in structure from those of normal males, but bigger in size, and completed all stages of spermatogenesis including accumulation of large amount of sperm in the seminiferous tubules. AI significantly reduced the serum levels of estradiol-17beta (E2) and increased levels of testosterone (T), 11-ketotestosterone (11-KT), and 17alpha, 20beta-dihydroxy-4-pregnen-3-one (DHP). Further, AI suppressed in vitro production of E2, and stimulated the production of T and 11-KT in the ovarian fragments of mature female. In the honeycomb grouper, suppression of both in vitro and in vivo production of E2 and degeneration of oocytes by AI suggests that AI induces complete sex change through inhibition of estrogen biosynthesis, and perhaps, subsequent induction of androgen function. PMID:14735491

Bhandari, Ramji Kumar; Higa, Mikihiko; Nakamura, Shigeo; Nakamura, Masaru

2004-03-01

315

Anomalous refractive effects in honeycomb lattice photonic crystals formed by holographic lithography.  

PubMed

We have investigated for the first time the anomalous refractive effects of a photonic crystal (PhC) formed by holographic lithography (HL) with triangular rods arranged in a honeycomb lattice in air. Possibilities of left-handed negative refraction and superlens are discussed for the case of TM2 band with the index contrast n = 3.4:1. In contrast to the conventional honeycomb PhC made of regular rods in air, the HL PhCs show left-handed negative refraction over a wider and higher frequency range with high transmissivity (>90%), and the effective indices quite close to -1 for a wide range of incident angles with a larger all-angle left-handed negative refraction (AALNR) frequency range (Deltaomega/omega approximately 14.8%). Calculations and FDTD simulations demonstrate the high-performance negative refraction properties can happen in the holographic structures for a wide filling ratio and can be modulated by changing the filling ratio easily. PMID:20721016

Dong, G Y; Yang, X L; Cai, L Z

2010-08-01

316

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

PubMed

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

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

2011-10-20

317

Mott-Hubbard Physics in a Patterned GaAs Heterostructure with Honeycomb Topology  

NASA Astrophysics Data System (ADS)

This talk considers efforts directed towards the design and exploration of novel collective electron states in artificial lattice structures that are realized in semiconductor heterostructures by nanofabrication methods. These studies reveal striking interplays between electron interactions and geometrical constraints (topology). We focus on the honeycomb topology, or ``artificial graphene'' (AG) [1,2], that supports Dirac fermions. Dirac fermions and the emergence of quantum phases, such as spin liquids and topologically protected states, can be studied by highly demanding inelastic light scattering methods and by electrical transport at low temperatures [3,4]. In particular, we probed the excitation spectrum of electrons in the honeycomb lattice in a magnetic field identifying collective modes that emerged from the Coulomb interaction [4], as predicted by the Mott-Hubbard model [5]. These observations allow us to determine the Hubbard gap and suggest the existence of a Coulomb-driven ground state [4]. Studies of electrons confined to artificial lattices should provide key perspectives on strong electron correlation in condensed matter science. [4pt] [1] M. Gibertini et al. Phys. Rev. B RC 79, 241406 (2009)[0pt] [2] C.H. Park and S.G. Louie, Nano Lett. 9, 1793 (2009).[0pt] [3] G. De Simoni et al. Appl. Phys. Lett. 97, 132113 (2010)[0pt] [4] A. Singha et al. Science 332, 1176 (2011)[0pt] [5] J. Hubbard. Proc. R. Soc. Lond. A 281, 401 (1964)

Pellegrini, Vittorio

2013-03-01

318

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

PubMed

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. PMID:24062449

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

2013-09-23

319

Rabbit Neurobehavioral Toxicity from Aluminum.  

National Technical Information Service (NTIS)

A model for the production of neurobehavioral toxicity induced by systemic aluminum exposure was developed. Nictitating membrane extension conditioning was used to assess the influence of the aluminum treatment on learning (acquisition and conditioned res...

R. A. Yokel

1983-01-01

320

Particulates in aluminum sputtering discharges  

Microsoft Academic Search

Plasma-generated particulates are receiving increasing attention as a possible source of device yield reduction in plasma-assisted etching and deposition processes. We have investigated aluminum sputtering in argon discharges between parallel-plate aluminum electrodes under both direct current and radio frequency excitation. Pulsed laser-induced fluorescence experiments indicate that particulates containing aluminum form in these discharges under conditions in which aluminum sputtering takes

G. M. Jellum; D. B. Graves

1990-01-01

321

Molecular Structure of Aluminum Fluoride  

NSDL National Science Digital Library

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.

2003-06-02

322

PROCESS FOR REMOVING ALUMINUM COATINGS  

DOEpatents

A process is presented for removing aluminum jackets or cans from uranium slugs. This is accomplished by immersing the aluminum coated uranium slugs in an aqueous solution of 9 to 20% sodium hydroxide and 35 to 12% sodium nitrate to selectively dissolve the aluminum coating, the amount of solution being such as to obtain a molar ratio of sodium hydroxide to aluminum of at least

Flox, J.

1959-07-01

323

Aluminum compounds as vaccine adjuvants.  

PubMed

Aluminum compounds are the only adjuvants used widely with routine human vaccines and are the most common adjuvants in veterinary vaccines also. Though there has been a search for alternate adjuvants, aluminum adjuvants will continue to be used for many years due to their good track record of safety, low cost and adjuvanticity with a variety of antigens. For infections that can be prevented by induction of serum antibodies, aluminum adjuvants formulated under optimal conditions are the adjuvants of choice. It is important to select carefully the type of aluminum adjuvant and optimize the conditions of adsorption for every antigen since this process is dependent upon the physico-chemical characteristics of both the antigens and aluminum adjuvants. Adsorption of antigens onto aluminum compounds depends heavily on electrostatic forces between adjuvant and antigen. Two commonly used aluminum adjuvants, aluminum hydroxide and aluminum phosphate have opposite charge at a neutral pH. The mechanism of adjuvanticity of aluminum compounds includes formation of a depot; efficient uptake of aluminum adsorbed antigen particles by antigen presenting cells due their particulate nature and optimal size (<10 µm); and stimulation of immune competent cells of the body through activation of complement, induction of eosinophilia and activation of macrophages. Limitations of aluminum adjuvants include local reactions, augmentation of IgE antibody responses, ineffectiveness for some antigens and inability to augment cell-mediated immune responses, especially cytotoxic T-cell responses. PMID:10837642

Gupta

1998-07-01

324

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...

325

Recycling of aluminum salt cake.  

National Technical Information Service (NTIS)

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% ...

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

1991-01-01

326

Honeycombed Asteroids  

NASA Astrophysics Data System (ADS)

Asteroids seem to have lower densities than the rocks scientists believe compose them. This implies that there is quite a bit of empty space inside the typical asteroid or small moon. Lionel Wilson (Lancaster University, UK), Klaus Keil (University of Hawaii), and Stanley Love (astronaut candidate, Johnson Space Center) investigated two possibilities for producing the high percentage of pore space. In one case they calculated that if an asteroid were broken apart and then reassembled, the resulting rubble pile would have a porosity of 20 to 40%, hence a density 20 to 40% lower than it had to begin with. They also calculated how fractures would form on bodies that contained water ice that was heated to steam, concluding that the fractures would be pervasive and, hence, decrease the density of the object.

Taylor, G. J.

1999-08-01

327

A comparison of experimental rotordynamic coefficients and leakage characteristics between hole-pattern gas damper seals and a honeycomb seal  

Microsoft Academic Search

Honeycomb annular seals are an attractive design alternative due to their superior static and dynamic performance. However, their implementation in industrial practice has been delayed by the following characteristics: (a) manufacturing time can be appreciable, and (b) they can seriously damage the shaft if rubbing occurs. To minimize these problems, hole-pattern gas damper seals, which are formed by simply drilling

Z. Yu; D. W. Childs

1998-01-01

328

Dynamic impact response of high-density square honeycombs made of TRIP steel and TRIP matrix composite material  

NASA Astrophysics Data System (ADS)

Two designs of square-celled metallic honeycomb structures fabricated by a modified extrusion technology based on a powder feedstock were investigated. The strength and ductility of these cellular materials are achieved by an austenitic CrNi (AISI 304) steel matrix particle reinforced by an MgO partially-stabilized zirconia building up their cell wall microstructure. Similar to the mechanical behaviour of the bulk materials, the strengthening mechanism and the martensitic phase transformations in the cell walls are affected by the deformation temperature and the nominal strain rate. The microstructure evolution during quasi-static and dynamic impact compression up to high strain rates of 103 1/s influences the buckling and failure behaviour of the honeycomb structures. In contrast to bending-dominated quasi-isotropic networks like open-celled metal foams, axial compressive loading to the honeycomb's channels causes membrane stretching as well as crushing of the vertical cell node elements and cell walls. The presented honeycomb materials differ geometrically in their cell wall thickness-to-cell size-ratio. Therefore, the failure behaviour is predominantly controlled by global buckling and torsional-flexural buckling, respectively, accompanied by plastic matrix flow and strengthening of the cell wall microstructure.

Ehinger, D.; Krüger, L.; Krause, S.; Martin, U.; Weigelt, C.; Aneziris, C. G.

2012-08-01

329

The numerical simulation of laser-generated ultrasound to detect the debonding in the honeycomb sandwich board  

Microsoft Academic Search

Among complex materials, honeycomb sandwich structure has a lot of advantages. However, it is usually found poor bonding or even debonding. Some convenient nondestructive methods should be found to measure the defect efficiently. Laser-generated ultrasound detection is a new nondestructive method with a bright future. Compared with traditional methods, the advantages of non-contact and high resolution in spatial and temporal

Ling Yuan; Yi-Ping Cui; Zhujun Gu; Zhong-Hua Shen; Xiao-Wu Ni

2011-01-01

330

Damage Tolerance Comparison of Composite Hat-Stiffened and Honeycomb Sandwich Structure for Launch Vehicle Interstage Applications.  

National Technical Information Service (NTIS)

In this study, a direct comparison of the compression-after-impact (CAI) strength of impact-damaged, hat-stiffened and honeycomb sandwich structure for launch vehicle use was made. The specimens used consisted of small substructure designed to carry a lin...

A. T. Nettles

2011-01-01

331

Aluminum-ferricyanide battery  

NASA Astrophysics Data System (ADS)

A battery capable of producing high current densities with high charge capacity is described which includes an aluminum anode, a ferricyanide electrolyte and a second electrode capable of reducing ferricyanide electrolyte which is either dissolved in an alkaline solution or alkaline seawater solution. The performance of the battery is enhanced by high temperature and high electrolyte flow rates.

Marsh, Catherine; Licht, Stuart L.

1993-11-01

332

Aluminum Sulfate 18 Hydrate  

ERIC Educational Resources Information Center

|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.|

Young, Jay A.

2004-01-01

333

Aluminum Coatings for Steel  

Microsoft Academic Search

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

Aruna Bahadur

1996-01-01

334

Foamed Aluminum Propellant Study.  

National Technical Information Service (NTIS)

This report summarizes the results of an AFRPL feasibility study on the use of a new experimental material, foam aluminum. The chief areas of interest center around the value of this material in high-burn-rate, pulse or end-burning motors and high acceler...

B. R. Warren C. G. Bacon

1968-01-01

335

Pitting corrosion of aluminum  

Microsoft Academic Search

This review describes the experiments performed during the last few decades which enhance knowledge of the pitting of aluminum. Specifically, metastable and stable pits, pit chemistry and the effect of intermetallics on pitting are discussed. The properties of metastable alloys and inhibition of Al are also discussed.

Z Szklarska-Smialowska

1999-01-01

336

REMOVAL OF ALUMINUM COATINGS  

DOEpatents

A process is presented for dissolving aluminum jackets from uranium fuel elements without attack of the uranium in a boiling nitric acid-mercuric nitrate solution containing up to 50% by weight of nitrtc acid and mercuric nitrate in a concentration of between 0.05 and 1% by weight.

Peterson, J.H.

1959-08-25

337

Aluminum Sulfate 18 Hydrate  

ERIC Educational Resources Information Center

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.

Young, Jay A.

2004-01-01

338

Serum Aluminum Transport and Aluminum Uptake in Chronic Renal Failure: Role of Iron and Aluminum Metabolism  

Microsoft Academic Search

Several factors have been blamed for increasing gastrointestinal absorption of aluminum. The likely role of iron metabolism was suggested some years ago. As iron and aluminum share many chemical properties, it is reasonable to think they also share biological pathways. The aim of this study was: (a) to evaluate serum aluminum transport and its relationship with iron-binding capacity, and (b)

Jorge B. Cannata; Ines R. Olaizola; Carlos Gomez-Alonso; Pilar Menéndez-Fraga; Mario Alonso-Suarez; Bernardino Diaz-Lopez

1993-01-01

339

SOLDERING OF ALUMINUM BASE METALS  

DOEpatents

This patent deals with the soldering of aluminum to metals of different types, such as copper, brass, and iron. This is accomplished by heating the aluminum metal to be soldered to slightly above 30 deg C, rubbing a small amount of metallic gallium into the part of the surface to be soldered, whereby an aluminum--gallium alloy forms on the surface, and then heating the aluminum piece to the melting point of lead--tin soft solder, applying lead--tin soft solder to this alloyed surface, and combining the aluminum with the other metal to which it is to be soldered.

Erickson, G.F.

1958-02-25

340

Structure, thermodynamics, and energy content of aluminum-cyclopentadienyl clusters.  

PubMed

We present quantum chemistry simulations of aluminum clusters surrounded by a surface layer of cyclopentadiene-type ligands to evaluate the potential of such complexes as novel fuels or energetic materials. Density functional theory simulations are used to examine the aluminum-ligand bonding and its variation as the size of the aluminum cluster increases. The organometallic bond at the surface layer arises mainly from ligand charge donation into the Al p orbitals balanced with repulsive polarization effects. Functionalization of the ligand and changes in Al cluster size are found to alter the relative balance of these effects, but the surface organometallic bond generally remains stronger than Al-Al bonds elsewhere in the cluster. In large clusters, such as the experimentally observed Al(50)Cp(12)*, this suggests that unimolecular thermal decomposition likely proceeds through loss of surface AlCp* units, exposing the strained interior aluminum core. The calculated heats of combustion per unit volume for these systems are high, approaching 60% that of pure aluminum. We discuss the possibility of using organometallic aluminum clusters as a means of achieving rapid combustion in propellants and fuels. PMID:22007955

Williams, Kristen S; Hooper, Joseph P

2011-11-11

341

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

Microsoft Academic Search

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

A. Seidel; Y. Zimmels

1998-01-01

342

Light scattering in disordered honeycomb photonic lattices near the Dirac points  

NASA Astrophysics Data System (ADS)

We address Anderson localization in disordered honeycomb photonic lattices and show that the localization process is strongly affected by the spectral position of the input wavepacket within the first Brillouin zone of the lattice. In spite of the fact that in regular lattice the expansion of the beam is much stronger for the excitation near the Dirac points, where light exhibits conical diffraction, than for the excitation at the center of the Brillouin zone, where the beam exhibits normal diffraction, we found that disorder leads to pronounced Anderson localization even around the Dirac points. We found that for the same disorder level the width of the averaged output intensity distribution for excitations around the Dirac points may be substantially larger than that for excitations at the center of the Brillouin zone.

Kartashov, Yaroslav V.; Zeuner, Julia M.; Szameit, Alexander; Vysloukh, Victor A.; Torner, Lluis

2013-10-01

343

Resistive transition in frustrated Josephson-junction arrays on a honeycomb lattice  

NASA Astrophysics Data System (ADS)

We use driven Monte Carlo dynamics to study the resistive behavior of superconducting Josephson-junction arrays on a honeycomb lattice in a magnetic field corresponding to f flux quantum per plaquette. While for f=1/3 the onset of zero resistance is found at nonzero temperature; for f=1/2 the results are consistent with a transition scenario where the critical temperature vanishes and the linear resistivity shows thermally activated behavior. We determine the thermal critical exponent of the zero-temperature transition for f=1/2 from a dynamic scaling analysis of the nonlinear resistivity. The resistive behavior agrees with recent results obtained for the phase-coherence transition from correlation-length calculations and with experimental observations on ultrathin superconducting films with a triangular pattern of nanoholes.

Granato, Enzo

2013-03-01

344

Finite-temperature properties of strongly correlated fermions in the honeycomb lattice  

NASA Astrophysics Data System (ADS)

We study finite-temperature properties of strongly interacting fermions in the honeycomb lattice using numerical linked-cluster expansions and determinantal quantum Monte Carlo simulations. We analyze a number of thermodynamic quantities, including the entropy, the specific heat, uniform and staggered spin susceptibilities, short-range spin correlations, and the double occupancy at and away from half filling. We examine the viability of adiabatic cooling by increasing the interaction strength for homogeneous as well as for trapped systems. For the homogeneous case, this process is found to be more efficient at finite doping than at half filling. That, in turn, leads to an efficient adiabatic cooling in the presence of a trap, which, starting with even relatively high entropies, can drive the system to have a Mott insulating phase with substantial antiferromagnetic correlations.

Tang, Baoming; Paiva, Thereza; Khatami, Ehsan; Rigol, Marcos

2013-09-01

345

Ni3TeO6--a collinear antiferromagnet with ferromagnetic honeycomb planes.  

PubMed

We report a comprehensive study of magnetic properties of Ni(3)TeO(6). The system crystallizes in a noncentrosymmetric rhombohedral lattice, space group R3. There are three differently coordinated Ni atoms in the unit cell. Two of them form an almost planar honeycomb lattice, while the third one is placed between the layers. Magnetization and specific heat measurements revealed a single magnetic ordering at T(N) = 52 K. Below T(N) the susceptibility with the magnetic field parallel to the c axis drops towards zero while the perpendicular susceptibility remains constant, a characteristic of antiferromagnetic materials. Neutron diffraction confirmed that the system is antiferromagnet below T(N) with ferromagnetic ab planes stacked antiferromagnetically along the c axis. All Ni moments are in the S = 1 spin state and point along the c axis. PMID:21386354

Zivkovi?, I; Prša, K; Zaharko, O; Berger, H

2010-01-15

346

Ni3TeO6—a collinear antiferromagnet with ferromagnetic honeycomb planes  

NASA Astrophysics Data System (ADS)

We report a comprehensive study of magnetic properties of Ni3TeO6. The system crystallizes in a noncentrosymmetric rhombohedral lattice, space group R3. There are three differently coordinated Ni atoms in the unit cell. Two of them form an almost planar honeycomb lattice, while the third one is placed between the layers. Magnetization and specific heat measurements revealed a single magnetic ordering at TN = 52 K. Below TN the susceptibility with the magnetic field parallel to the c axis drops towards zero while the perpendicular susceptibility remains constant, a characteristic of antiferromagnetic materials. Neutron diffraction confirmed that the system is antiferromagnet below TN with ferromagnetic ab planes stacked antiferromagnetically along the c axis. All Ni moments are in the S = 1 spin state and point along the c axis.

Živkovi?, I.; Prša, K.; Zaharko, O.; Berger, H.

2010-02-01

347

Self-assembled carbon nanotube honeycomb networks using a butterfly wing template as a multifunctional nanobiohybrid.  

PubMed

Insect wings have many unique and complex nano/microstructures that are presently beyond the capabilities of any current technology to reproduce them artificially. In particular, Morpho butterflies are an attractive type of insect because their multifunctional wings are composed of nano/microstructures. In this paper, we show that carbon nanotube-containing composite adopts honeycomb-shaped networks when simply self-assembled on Morpho butterfly wings used as a template. The unique nano/microstructure of the composites exhibits multifunctionalities such as laser-triggered remote-heating, high electrical conductivity, and repetitive DNA amplification. Our present study highlights the important progress that has been made toward the development of smart nanobiomaterials for various applications such as digital diagnosis, soft wearable electronic devices, photosensors, and photovoltaic cells. PMID:23952240

Miyako, Eijiro; Sugino, Takushi; Okazaki, Toshiya; Bianco, Alberto; Yudasaka, Masako; Iijima, Sumio

2013-08-22

348

Spin waves and revised crystal structure of honeycomb iridate Na2IrO3.  

PubMed

We report inelastic neutron scattering measurements on Na2IrO3, a candidate for the Kitaev spin model on the honeycomb lattice. We observe spin-wave excitations below 5 meV with a dispersion that can be accounted for by including substantial further-neighbor exchanges that stabilize zigzag magnetic order. The onset of long-range magnetic order below T(N)=15.3??K is confirmed via the observation of oscillations in zero-field muon-spin rotation experiments. Combining single-crystal diffraction and density functional calculations we propose a revised crystal structure model with significant departures from the ideal 90° Ir-O-Ir bonds required for dominant Kitaev exchange. PMID:22540621

Choi, S K; Coldea, R; Kolmogorov, A N; Lancaster, T; Mazin, I I; Blundell, S J; Radaelli, P G; Singh, Yogesh; Gegenwart, P; Choi, K R; Cheong, S-W; Baker, P J; Stock, C; Taylor, J

2012-03-20

349

Absence of a Spin Liquid Phase in the Hubbard Model on the Honeycomb Lattice  

NASA Astrophysics Data System (ADS)

A spin liquid is a novel quantum state of matter with no conventional order parameter where a finite charge gap exists even though the band theory would predict metallic behavior. Finding a stable spin liquid in two or higher spatial dimensions is one of the most challenging and debated issues in condensed matter physics. Very recently, it has been reported that a model of graphene, i.e., the Hubbard model on the honeycomb lattice, can show a spin liquid ground state in a wide region of the phase diagram, between a semi-metal (SM) and an antiferromagnetic insulator (AFMI). Here, by performing numerically exact quantum Monte Carlo simulations, we extend the previous study to much larger clusters (containing up to 2592 sites), and find, if any, a very weak evidence of this spin liquid region. Instead, our calculations strongly indicate a direct and continuous quantum phase transition between SM and AFMI.

Sorella, Sandro; Otsuka, Yuichi; Yunoki, Seiji

2012-12-01

350

Magnetic dipole configurations on honeycomb lattices: effect of finite size and boundaries.  

PubMed

Artificial dipolar spin-ice patterns have attracted much attention recently because of their rich configurations and excitations in the form of Dirac strings connecting magnetic monopoles. We have analysed the distribution of excitations in the form of strings and vertices carrying magnetic charges Q=±3q in honeycomb artificial spin-ice patterns. Two types of patterns are compared, those that terminate with open hexagons and those with closed hexagons. The dipole configurations and the frequency of spin-ice rule-violating Q=±3q vertices depend slightly on the boundary conditions of the pattern. Upon rotation of the patterns by 2? in a coercive magnetic field of 500 Oe, complete reversibility of the charge and string configuration is observed. PMID:23166380

Schumann, Alexandra; Zabel, Hartmut

2012-12-28

351

Upstanding Rashba spin in honeycomb lattices: Electrically reversible surface spin polarization  

NASA Astrophysics Data System (ADS)

The spin-split states subject to Rashba spin-orbit coupling in two-dimensional systems have long been accepted as pointing inplane and perpendicular to the corresponding wave vectors. This is in general true for free-electron model, but exceptions do exist elsewhere. Within the tight-binding model, we unveil the unusual upstanding behavior of those Rashba spins around K¯ and K¯' points in honeycomb lattices. Our calculation (i) explains the recent experiment of the Tl/Si(111)-(1×1) surface alloy [K. Sakamoto , Phys. Rev. Lett. 102, 096805 (2009)], where abrupt upstanding spin states near K¯ are observed and (ii) predicts an electrically reversible out-of-plane surface spin polarization.

Liu, Ming-Hao; Chang, Ching-Ray

2009-12-01

352

Absence of a Spin Liquid Phase in the Hubbard Model on the Honeycomb Lattice  

PubMed Central

A spin liquid is a novel quantum state of matter with no conventional order parameter where a finite charge gap exists even though the band theory would predict metallic behavior. Finding a stable spin liquid in two or higher spatial dimensions is one of the most challenging and debated issues in condensed matter physics. Very recently, it has been reported that a model of graphene, i.e., the Hubbard model on the honeycomb lattice, can show a spin liquid ground state in a wide region of the phase diagram, between a semi-metal (SM) and an antiferromagnetic insulator (AFMI). Here, by performing numerically exact quantum Monte Carlo simulations, we extend the previous study to much larger clusters (containing up to 2592 sites), and find, if any, a very weak evidence of this spin liquid region. Instead, our calculations strongly indicate a direct and continuous quantum phase transition between SM and AFMI.

Sorella, Sandro; Yunoki, Seiji

2012-01-01

353

Absence of a spin liquid phase in the Hubbard model on the honeycomb lattice.  

PubMed

A spin liquid is a novel quantum state of matter with no conventional order parameter where a finite charge gap exists even though the band theory would predict metallic behavior. Finding a stable spin liquid in two or higher spatial dimensions is one of the most challenging and debated issues in condensed matter physics. Very recently, it has been reported that a model of graphene, i.e., the Hubbard model on the honeycomb lattice, can show a spin liquid ground state in a wide region of the phase diagram, between a semi-metal (SM) and an antiferromagnetic insulator (AFMI). Here, by performing numerically exact quantum Monte Carlo simulations, we extend the previous study to much larger clusters (containing up to 2592 sites), and find, if any, a very weak evidence of this spin liquid region. Instead, our calculations strongly indicate a direct and continuous quantum phase transition between SM and AFMI. PMID:23251778

Sorella, Sandro; Otsuka, Yuichi; Yunoki, Seiji

2012-12-18

354

Active supports and force optimization for a 3.5-m honeycomb sandwich mirror  

NASA Astrophysics Data System (ADS)

We describe the active support system and optimization of support forces for a 3.5-m honeycomb sandwich mirror. The optimization was based on interferometric figure measurements made in a vibration-isolated test tower. We obtained actuator influence functions by measurement and by finite-element analysis. The two sets of influence functions are similar in shape, but the computed figure changes are 25% smaller in magnitude than the measured figure changes. We achieved a figure accuracy of 25 nm rms surface error with the computed influence functions and only slightly worse with the measured influence functions, but were unable to reproduce the 21-nm rms surface error obtained on the passive polishing support. This implies that subtle differences between the polishing support and operational support caused small, uncorrectable figure changes. The optimization was performed by singular-value decomposition of the influence functions into normal modes. The best results were obtained using 20 - 30 out of a possible 37 modes.

Martin, Hubert M.; Davison, Warren B.; Derigne, S. T.; Hill, John M.; Hille, B. B.; Meeks, R. L.; Trebisky, T. J.

1994-06-01

355

3D Weyl Semimetal in a Honeycomb Array of Topological Nano-wires  

NASA Astrophysics Data System (ADS)

The Weyl semimetal phase has been recently introduced and suggested to exist in strongly correlated pyrochlore iridates as well as in the non-interacting layered Normal/Topological band insulator systems. This unusual phase has a number of interesting properties in the bulk and at the surface arising from the appearance of isolated point-like hedge-hog topological defects (known as Weyl-Dirac points) in the Bloch-state manifold. Here we discuss the possible emergence of this phase in a honeycomb arrangement of the parallel topological insulator nano-rods each exposed to a half-integer multiple of magnetic flux quantum. We consider direct hoping between rods as well as the electron-electron interaction between them. We discuss how the initially degenerate Weyl points can be separated in the Brillouin zone by various perturbations breaking either inversion or time-reversal symmetry.

Vazifeh, Mohammad; Franz, Marcel

2012-02-01

356

Time resolved shearographic and thermographic NDE methods for graphite epoxy/honeycomb composite  

SciTech Connect

Results are presented showing the application of both time resolved thermography and time resolved shearography to specimens of graphite epoxy/honeycomb composites containing delaminations. Of particular importance is the demonstration that the depth of a defect can be determined by measuring the time dependence of the shearographic fringe development during heating. Upon application of a noncontacting heating source, large thermoelastic deformation in the heated region occurs over delamination regions in a specimen. The bending stresses in the material above the delamination decrease characteristically when the diffusing temperature field interacts with the delamination and the temperature gradient through the intact material decreases. As a result, both the presence of the delamination and its depth can be measured simultaneously.

Spicer, J.B.; Champion, J.L. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Materials Science and Engineering; Osiander, R.; Spicer, J.W.M. [Johns Hopkins Univ., Laurel, MD (United States). Applied Physics Lab.

1996-10-01

357

Topological Fermi Liquids from Coulomb Interactions in the Doped Honeycomb Lattice  

SciTech Connect

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.

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

358

Superhydrophobic and lipophobic properties of self-organized honeycomb and pincushion structures.  

PubMed

This report describes the simple preparation of superhydrophobic and lipophobic surfaces by self-organization. Microporous polymer films of a fluorinated polymer with hexagonally arranged pores were prepared by casting from solution under humid conditions. Hexagonally packed water microdroplets were formed by evaporative cooling on the surface of the casting solution. After solvent evaporation, a honeycomb-patterned polymer film was formed with the water droplet array acting as a template; the water droplets themselves evaporated soon after the solvent. Two porous polymer layers were stacked vertically, separated by pillars at the hexagon vertexes. After peeling off the top layer using adhesive tape, a pincushion-like structure was obtained. Here, we show that superhydrophobic behavior was achieved, with the maximum contact angle, 170 degrees, observed using these pincushion structures. Theoretical calculations fit the experimental results well. The lipophobic properties of the films are also discussed. PMID:15807559

Yabu, Hiroshi; Takebayashi, Masafumi; Tanaka, Masaru; Shimomura, Masatsugu

2005-04-12

359

The Idiopathic Pulmonary Fibrosis Honeycomb Cyst Contains A Mucocilary Pseudostratified Epithelium  

PubMed Central

Background We previously identified a MUC5B gene promoter-variant that is a risk allele for sporadic and familial Idiopathic Pulmonary Fibrosis/Usual Interstitial Pneumonia (IPF/UIP). This allele was strongly associated with increased MUC5B gene expression in lung tissue from unaffected subjects. Despite the strong association of this airway epithelial marker with disease, little is known of mucin expressing structures or of airway involvement in IPF/UIP. Methods Immunofluorescence was used to subtype mucus cells according to MUC5B and MUC5AC expression and to identify ciliated, basal, and alveolar type II (ATII) cells in tissue sections from control and IPF/UIP subjects. Staining patterns were quantified for distal airways (Control and IPF/UIP) and in honeycomb cysts (HC). Results MUC5B-expressing cells (EC) were detected in the majority of control distal airways. MUC5AC-EC were identified in half of these airways and only in airways that contained MUC5B-EC. The frequency of MUC5B+ and MUC5AC+ distal airways was increased in IPF/UIP subjects. MUC5B-EC were the dominant mucus cell type in the HC epithelium. The distal airway epithelium from control and IPF/UIP subjects and HC was populated by basal and ciliated cells. Most honeycombing regions were distinct from ATII hyperplasic regions. ATII cells were undetectable in the overwhelming majority of HC. Conclusions The distal airway contains a pseudostratified mucocilary epithelium that is defined by basal epithelial cells and mucus cells that express MUC5B predominantly. These data suggest that the HC is derived from the distal airway.

Seibold, Max A.; Smith, Russell W.; Urbanek, Cydney; Groshong, Steve D.; Cosgrove, Gregory P.; Brown, Kevin K.; Schwarz, Marvin I.

2013-01-01

360

First-principles study of two- and one-dimensional honeycomb structures of boron nitride  

NASA Astrophysics Data System (ADS)

This paper presents a systematic study of two- and one-dimensional honeycomb structures of boron nitride (BN) using first-principles plane-wave method. In order to reveal dimensionality effects, a brief study of all allotropic forms of three-dimensional (3D) BN crystals and truly one-dimensional atomic BN chains are also included. Two-dimensional (2D) graphenelike BN is a wide band-gap semiconductor with ionic bonding through significant charge transfer from B to N. Phonon-dispersion curves demonstrate the stability of 2D BN flakes. Quasi-one-dimensional (1D) armchair BN nanoribbons are nonmagnetic semiconductors with edge states. Upon passivation of B and N with hydrogen atoms these edge states disappear and the band gap increases. Bare zigzag BN nanoribbons are metallic but become a ferromagnetic semiconductor when both their edges are passivated with hydrogen. However, their magnetic ground state, electronic band structure, and band gap are found to be strongly dependent on whether B or N edge of the ribbon is saturated with hydrogen. Vacancy defects in armchair and zigzag nanoribbons affect also the magnetic state and electronic structure. Harmonic, anharmonic, and plastic regions are deduced in the variation in the total energy of armchair and zigzag nanoribbons as a function of strain. The calculated force constants display a Hookian behavior. In the plastic region the nanoribbon is stretched, whereby the honeycomb structure of hexagons change into different polygons through sequential structural transformations. In order to reveal dimensionality effects these properties are contrasted with those of various 3D BN crystals and 1D BN atomic chain.

Topsakal, M.; Aktürk, E.; Ciraci, S.

2009-03-01

361

Control of vibration and wave propagation in sandwich plates with periodic auxetic core  

NASA Astrophysics Data System (ADS)

The wave propagation in and the vibration of sandwich plates with cellular core are analyzed and controlled. Negative Poisson's ratio (auxetic) core materials of different geometry placed periodically in the plate introduce the proper impedance mismatch necessary to obstruct the propagation of waves over specified frequency bands (stop bands) and in particular directions. The location and the extension of the stop bands and the directions of wave propagation can be modified by proper selection of the periodicity and of the geometrical and physical properties of the core. A Finite Element model is developed to predict the dynamic response of three-layered sandwich panels with honeycomb core. The Finite Element model along with the theory of periodic structures is used to evaluate the influence of core materials of different geometry placed periodically along the two dimensions of the structure. This combined analysis yields the phase constant surfaces for the considered sandwich plates, which define location and extension of the stop bands, as well as the directions of wave propagation at assigned frequency values. The analysis of the phase constant surfaces and the evaluation of the harmonic response at specified frequencies indicate that the plates are characterized by dynamic behaviors with directional properties, with spatial patterns strongly dependent on the configuration of the periodic core and on the excitation frequency. Auxetic honeycombs are considered as core materials in order to obtain maximum design flexibility. The elastic and inertial characteristics of auxetic honeycombs in fact vary substantially with their internal geometry and for given configurations outcast up to five times the corresponding properties of traditional hexagonal honeycombs. The presented numerical results demonstrate the unique characteristics of this class of two-dimensional periodic structures, which behave as directional mechanical filters. The findings of this study suggest that optimal configurations for the periodic cellular core can be identified in order to design passive composite panels, which are stable and quiet over desired frequency bands and which fit desired transmissibility levels in particular directions. Such unique filtering capabilities are achieved without requiring additional passive or active control devices and therefore without compromising the size and the weight of the layered structure.

Scarpa, Fabrizio L.; Ruzzene, Massimo; Mazzarella, Luca; Tsopelas, Panagiotis

2002-06-01

362

Aluminum microstructures on anodic alumina for aluminum wiring boards.  

PubMed

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

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

2010-03-01

363

Aluminum permanganate battery  

NASA Astrophysics Data System (ADS)

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.

Marsh, Catherine; Licht, Stuart L.

1993-11-01

364

Mechanisms of Aluminum Tolerance  

Microsoft Academic Search

\\u000a Aluminum (Al) toxicity limits agricultural productivity over much of the world’s arable land by inhibiting root growth and\\u000a development. Affected plants have difficulty in acquiring adequate water and nutrition from their soil environments and thus\\u000a have stunted shoot development and diminished yield. Al toxicity is due to soil acidity and is largely a natural problem;\\u000a however, it can also result

Owen A. Hoekenga; Jurandir V. Magalhaes

365

Predicting the Dynamic Crushing Response of a Composite Honeycomb Energy Absorber Using Solid-Element-Based Models in LS-DYNA.  

National Technical Information Service (NTIS)

This paper describes an analytical study that was performed as part of the development of an externally deployable energy absorber (DEA) concept. The concept consists of a composite honeycomb structure that can be stowed until needed to provide energy att...

K. E. Jackson

2010-01-01

366

Extracting aluminum from dross tailings  

NASA Astrophysics Data System (ADS)

Aluminum dross tailings, an industrial waste, from the Egyptian Aluminium Company (Egyptalum) was used to produce two types of alums: aluminum-sulfate alum [itAl2(SO4)3.12H2O] and ammonium-aluminum alum [ (NH 4)2SO4AL2(SO4)3.24H2O]. This was carried out in two processes. The first process is 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 solute sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purifi ed aluminum dross tailings thus produced. The effects of temperature, time of reaction, and acid concentration on leaching and extraction processes were studied. The product alums were analyzed using x-ray diffraction and thermal analysis techniques.

Amer, A. M.

2002-11-01

367

Aluminum Carbothermic Technology  

SciTech Connect

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.

Bruno, Marshall J.

2005-03-31

368

Design, fabrication and test of a liquid hydrogen titanium honeycomb cryogenic test tank for use as a reusable launch vehicle main propellant tank  

Microsoft Academic Search

Reusable Launch Vehicles (RLV's) utilizing LOX\\\\LH2 as the propellant require lightweight durable structural systems to meet mass fraction goals and to reduce overall systems operating costs. Titanium honeycomb sandwich with flexible blanket TPS on the windward surface is potentially the lightest-weight and most operable option. Light weight is achieved in part because the honeycomb sandwich tank provides insulation to its

Patrick B. Stickler; Peter C. Keller

1998-01-01

369

Design, fabrication and test of a liquid hydrogen titanium honeycomb cryogenic test tank for use as a reusable launch vehicle main propellant tank  

Microsoft Academic Search

Reusable Launch Vehicles (RLV’s) utilizing LOX\LH2 as the propellant require lightweight durable structural systems to meet mass fraction goals and to reduce overall systems operating costs. Titanium honeycomb sandwich with flexible blanket TPS on the windward surface is potentially the lightest-weight and most operable option. Light weight is achieved in part because the honeycomb sandwich tank provides insulation to its

Patrick B. Stickler; Peter C. Keller

1998-01-01

370

Preparation of SiC-based cellular substrate by pressure-pulsed chemical vapor infiltration into honeycomb-shaped paper preforms  

Microsoft Academic Search

Using a pressure-pulsed chemical vapor infiltration technique, SiC was infiltrated from a SiCl4 (4%)–CH4 (4%)–H2 gas phase into carbonized paper preforms at 1100°C. SiC-based cellular substrates with cell wall thicknesses of 25, 50 and 100 µm were obtained by using honeycomb-shaped paper preforms as the templates. The reduction of both wall thickness t and cell pitch d of SiC-based honeycomb

Y. Ohzawa; K. Nakane; V. Gupta; T. Nakajima

2002-01-01

371

Cathodic phenomena in aluminum electrowinning  

NASA Astrophysics Data System (ADS)

Although aluminum is one of the world's highest production-volume primary metals, it is particularly costly to produce for a variety of factors, not the least of which are the expenses associated with electrolytic reduction. Based on the scale of global aluminum processing, even minor improvements in the electrowinning technology can result in significant savings of resources. Thus, from this perspective, the following reviews recent studies of cathodic phenomena in aluminum electrowinning.

Bouteillon, J.; Poignet, J. C.; Rameau, J. J.

1993-02-01

372

Recycling of aluminum salt cake  

Microsoft Academic Search

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

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

1991-01-01

373

Molecular aspects of aluminum toxicity  

Microsoft Academic Search

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

Alfred Haug; Charles E. Foy

1984-01-01

374

DUBLIN CORE  

EPA Science Inventory

The Dublin Core is a metadata element set intended to facilitate discovery of electronic resources. It was originally conceived for author-generated descriptions of Web resources, and the Dublin Core has attracted broad ranging international and interdisciplinary support. The cha...

375

Aluminum-lithium for aerospace  

SciTech Connect

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.

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

1996-10-01

376

Laser welding of aluminum alloys  

SciTech Connect

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.

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

1997-03-01

377

Mineral of the month: aluminum  

USGS Publications Warehouse

Aluminum is the second most abundant metallic element in Earth’s crust after silicon. Even so, it is a comparatively new industrial metal that has been produced in commercial quantities for little more than 100 years. Aluminum is lightweight, ductile, malleable and corrosion resistant, and is a good conductor of heat and electricity. Weighing about one-third as much as steel or copper per unit of volume, aluminum is used more than any other metal except iron. Aluminum can be fabricated into desired forms and shapes by every major metalworking technique to add to its versatility.

Plunkert, Patricia A.

2005-01-01

378

Optical Fingerprints of Si Honeycomb Chains and Atomic Gold Wires on the Si(111)-(5×2)-Au Surface  

NASA Astrophysics Data System (ADS)

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.

Hogan, Conor; Ferraro, Elena; McAlinden, Niall; McGilp, John F.

2013-08-01

379

Damping Studies of Ceramic Reinforced Aluminum.  

National Technical Information Service (NTIS)

Ceramic reinforced aluminum alloys exhibit a unique combination of mechanical properties not found in monolithic aluminum alloys. The addition of high modulus ceramic particles to conventional aluminum alloys results in increased strength, elastic modulus...

C. R. Wong S. Holcomb

1991-01-01

380

21 CFR 73.1645 - Aluminum powder.  

Code of Federal Regulations, 2012 CFR

...2013-04-01 2013-04-01 false Aluminum powder. 73.1645 Section 73.1645...CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely...

2013-04-01

381

21 CFR 73.2645 - Aluminum powder.  

Code of Federal Regulations, 2012 CFR

...2013-04-01 2013-04-01 false Aluminum powder. 73.2645 Section 73...CERTIFICATION Cosmetics § 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in...

2013-04-01

382

21 CFR 172.310 - Aluminum nicotinate.  

Code of Federal Regulations, 2012 CFR

... 3 2013-04-01 2013-04-01 false Aluminum nicotinate. 172.310 Section 172.310 ...Dietary and Nutritional Additives § 172.310 Aluminum nicotinate. Aluminum nicotinate may be safely used as a source of...

2013-04-01

383

75 FR 80527 - Aluminum Extrusions From China  

Federal Register 2010, 2011, 2012, 2013

...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...

2010-12-22

384

Ceramic honeycomb as support for covalent immobilization of laccase from Trametes versicolor and transformation of nuclear fast red  

Microsoft Academic Search

The covalent immobilization of laccase on an inorganic ceramic support was investigated. The intention was to find a system\\u000a of enzyme and reactor for a universal immobilization procedure. Laccase from Trametes versicolor as model enzyme was chosen. The special honeycomb structure of the monolith can be applied for intensive mixing of the reaction\\u000a compounds. An appropriate reactor with ceramic material

Regina Plagemann; Ludwig Jonas; Udo Kragl

2011-01-01

385

Effective Electromagnetic Parameters and Absorbing Properties for Honeycomb Sandwich Structures with a Consideration of the Disturbing Term  

NASA Astrophysics Data System (ADS)

The interaction between particles cannot be ignored when a high frequency electromagnetic wave is incident on a mixed media. Strong fluctuation theory with correlation function is a suitable method to describe the problem. Materials with honeycomb sandwich structures with an absorber included are investigated. The effective electromagnetic parameters and reflection coefficient of these materials are deduced and numerical results are given. Compared with the method with a disturbing term not considered, this method shows better absorbing properties.

Hu, Ji-Wei; He, Si-Yuan; Rao, Zhen-Min; Zhu, Guo-Qiang; Yin, Hong-Cheng

2013-10-01

386

Evaluation of the manufacture of sound absorbent sandwich plank made of PET\\/TPU honeycomb grid\\/PU foam  

Microsoft Academic Search

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

Jia-Horng Lin; Chin-Mei Lin; Chao-Chiung Huang; Chia-Chang Lin; Chien-Teng Hsieh; Yu-Chen Liao

2011-01-01

387

Wettability of carbon by aluminum and aluminum alloys  

Microsoft Academic Search

Wetting (both equilibrium contact angle and spreading kinetics) of aluminum and aluminum alloys with silicon and titanium on carbon substrates is investigated as a function of temperature and carbon microstructure. Experiments are carried out by the sessile drop technique under high vacuum, in the range from 1023 to 1250K. Three different types of carbon substrates are examined: vitreous carbon, pyrolytic

K. Landry; S. Kalogeropoulou; N. Eustathopoulos

1998-01-01

388

Thermoelastic ratcheting effect in bolted aluminum-to-aluminum connections  

Microsoft Academic Search

The effect of thermoelastic ratcheting on the mechanical integrity of bolted aluminum-to-aluminum connections using different mechanical contact devices was studied. Thermoelastic ratcheting was studied under current cycling conditions using currents 800 to 2000 A. The results show that the mechanical integrity of the connections is strongly affected by the joint configuration, which differs according to the mechanical devices used. To

MILENKO BRAUNOVIC; MILUTIN MARJANOV

1988-01-01

389

Some Fundamental Properties of Aluminum-Aluminum Electrical Contacts  

Microsoft Academic Search

The results of a fundamental Investigation of the properties of stationary aluminum-aluminum (AA1350) electrical contacts at room temperature both in an ultrahigh vacuum and in an oxygen atmosphere are reported. The contact couples consist of two polished spherical surfaces held together under constant load over a small area; the work was carried out in an environmental chamber which allows manipulation

R. S. TIMSIT

1980-01-01

390

Solid Aluminum Electrolytic Capacitors with Etched Aluminum Foil  

Microsoft Academic Search

Some suggestions are made for further developments in the field of electrolytic capacitors using etched aluminum foils and solid electrolytes. Various laboratory-tested construction procedures are discussed in detail. The behavior of capacity, dissipation factor, and leakage is illustrated as the function of temperature and frequency during storage with and without current. It is shown that the production of aluminum electrolytic

W. Post

1962-01-01

391

Production of aluminum metal by electrolysis of aluminum sulfide  

DOEpatents

Production of metallic aluminum by the electrolysis of Al.sub.2 S.sub.3 at 700.degree.-800.degree. C. in a chloride melt composed of one or more alkali metal chlorides, and one or more alkaline earth metal chlorides and/or aluminum chloride to provide improved operating characteristics of the process.

Minh, Nguyen Q. (Woodridge, IL); Loutfy, Raouf O. (Tucson, AZ); Yao, Neng-Ping (Clarendon Hills, IL)

1984-01-01

392

Partition function zeros of the honeycomb-lattice Ising antiferromagnet in the complex magnetic-field plane.  

PubMed

The microcanonical transfer matrix is used to evaluate the exact integer values for the number of states ?(E,M), as a function of energy E and magnetization M, of the Ising model in an external magnetic field H on L×2L honeycomb lattices (L=6,8,…,14) and (due to memory limitations) the exact real values for ?(a,M)=?(E)?(E,M)a(E) (L=16,…,22) , where a=e(2?J). Given ?(E,M) or ?(a,M) , the exact partition functions Z(a,x)=?(E,M)?(E,M)a(E)x(M)=?(M)?(a,M)x(M), where x=e(-2?H), are obtained. From the exact partition functions, the precise distributions of the partition function zeros in the complex x plane of the honeycomb-lattice Ising antiferromagnet in a uniform external magnetic field, where the famous circle theorem for the partition function zeros of the Ising ferromagnet is not applicable, are determined. In addition, the critical points x(cp)(a) and the magnetic scaling exponents y(h)(a) of the honeycomb-lattice Ising antiferromagnet in a uniform magnetic field are estimated using its partition function zeros in the complex x plane. Our results for the critical points are also compared to those of the two different closed-form approximations. PMID:21230238

Kim, Seung-Yeon

2010-10-11

393

Gonadal restructuring and correlative steroid hormone profiles during natural sex change in protogynous honeycomb grouper (Epinephelus merra).  

PubMed

The honeycomb grouper shows protogynous hermaphroditism. The endocrine mechanisms involved in gonadal restructuring throughout protogynous sex change are largely unknown. In the present study, we investigated changes in the gonadal structures and levels of serum sex steroid hormones during female to male sex change in the honeycomb grouper. On the basis of histological changes, entire process of sex change was assigned into four developmental phases: female, early transition (ET), late transition (LT), and male phase. At the female phase, the oocytes of several developmental stages were observed including gonial germ cells in the periphery of ovigerous lamellae. At the beginning of ET phase, perinucleolar and previtellogenic oocytes began degenerating, followed by proliferation of spermatogonia toward the center of lamella. The LT phase was characterized by further degeneration of oocytes and rapid proliferation of spermatogenic germ cells throughout the gonad. At the male phase, no ovarian cells were observed and testis had germ cells undergoing active spermatogenesis. Serum levels of estradiol-17beta (E2) were high in females in the breeding season, but low in the non-breeding female, transitional and male phase, and those of 11-ketotestosterone (11-KT) and testosterone (T) were low in females and gradually increased in the transitional and male phase. The present results suggest that low serum E2 levels and degeneration of oocytes accompanied by concomitant increase in the 11-KT levels and proliferation of spermatogenic germ cells are probably the events mediating protogynous sex change in the honeycomb grouper. PMID:14624040

Bhandari, Ramji Kumar; Komuro, Hiroki; Nakamura, Shigeo; Higa, Mikihiko; Nakamura, Masaru

2003-11-01

394

Characterization of ultradispersed aluminum  

SciTech Connect

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.

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

1994-12-08

395

Selective Adsorption of Sodium Aluminum Fluoride Salts from Molten Aluminum  

SciTech Connect

Aluminum is produced in electrolytic reduction cells where alumina feedstock is dissolved in molten cryolite (sodium aluminum fluoride) along with aluminum and calcium fluorides. The dissolved alumina is then reduced by electrolysis and the molten aluminum separates to the bottom of the cell. The reduction cell is periodically tapped to remove the molten aluminum. During the tapping process, some of the molten electrolyte (commonly referred as “bath” in the aluminum industry) is carried over with the molten aluminum and into the transfer crucible. The carryover of molten bath into the holding furnace can create significant operational problems in aluminum cast houses. Bath carryover can result in several problems. The most troublesome problem is sodium and calcium pickup in magnesium-bearing alloys. Magnesium alloying additions can result in Mg-Na and Mg-Ca exchange reactions with the molten bath, which results in the undesirable pickup of elemental sodium and calcium. This final report presents the findings of a project to evaluate removal of molten bath using a new and novel micro-porous filter media. The theory of selective adsorption or removal is based on interfacial surface energy differences of molten aluminum and bath on the micro-porous filter structure. This report describes the theory of the selective adsorption-filtration process, the development of suitable micro-porous filter media, and the operational results obtained with a micro-porous bed filtration system. The micro-porous filter media was found to very effectively remove molten sodium aluminum fluoride bath by the selective adsorption-filtration mechanism.

Leonard S. Aubrey; Christine A. Boyle; Eddie M. Williams; David H. DeYoung; Dawid D. Smith; Feng Chi

2007-08-16

396

24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES ...  

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

24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES FOR A BRASS GATE VALVE BODY MADE ON A CORE BOX, CA. 1950. - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

397

Self-repairing coating for corrosion protection of aluminum alloys  

Microsoft Academic Search

The development of effective anticorrosion pre-treatments for metallic substrates is an issue of great importance for durability of metal structures and components. In this work, we proposed and demonstrated the concept of self-repairing coating for corrosion protection of aluminum alloys, using cagelike oil core\\/silica gel shell particles. These micron-scale, cagelike smart microspheres with opened and closed pores were successfully fabricated,

Xiaodong He; Xianming Shi

2009-01-01

398

NEUTRONIC REACTOR CORE  

DOEpatents

An improved core for a gas-cooled power reactor which admits gas coolant at high temperatures while affording strong integral supporting structure and efficient moderation of neutrons is described. The multiplicities of fuel elements constituting the critical amassment of fissionable material are supported and confined by a matrix of metallic structure which is interspersed therebetween. Thermal insulation is interposed between substantially all of the metallic matrix and the fuel elements; the insulation then defines the principal conduit system for conducting the coolant gas in heat-transfer relationship with the fuel elements. The metallic matrix itseif comprises a system of ducts through which an externally-cooled hydrogeneous liquid, such as water, is circulated to serve as the principal neutron moderant for the core and conjointly as the principal coolant for the insulated metallic structure. In this way, use of substantially neutron transparent metals, such as aluminum, becomes possible for the supporting structure, despite the high temperatures of the proximate gas. The Aircraft Nuclear Propulsion program's "R-1" reactor design is a preferred embodiment.

Thomson, W.B.; Corbin, A. Jr.

1961-07-18

399

Aluminum-Lithium Alloy Research.  

National Technical Information Service (NTIS)

A recent Air Force program was focused on developing an isotropic aluminum-lithium alloy, having greater than two weight percent lithium. The addition of two weight percent lithium can reduce the density of aluminum by six percent and increase the modulus...

E. A. Starke A. A. Csontos

1997-01-01

400

Precipitation hardening of aluminum alloys  

Microsoft Academic Search

The author's charge was to discuss recent trends in research and development on precipitation hardened aluminum alloys and to indicate where research is needed. This will be done for three areas: fatigue, properties of grain boundaries and interfaces, and stability of precipitates at elevated temperatures. Present strong precipitation hardened aluminum alloys do not have high endurance limits. One problem is

Morris E. Fine

1975-01-01

401

Aluminum vehicle breaks new ground  

SciTech Connect

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.

Ashley, S.

1994-02-01

402

Laser welding of aluminum alloys  

Microsoft Academic Search

Recent interest in reducing the weight of automobiles to increase fuel milage 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

Keng H. Leong; Kenneth R. Sabo; Paul G. Sanders; Walter J. Spawr

1997-01-01

403

Laser welding of aluminum alloys.  

National Technical Information Service (NTIS)

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. Co...

K. H. Leong K. R. Sabo P. G. Sanders W. J. Spawr

1997-01-01

404

Lost-Soap Aluminum Casting.  

ERIC Educational Resources Information Center

|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)|

Mihalow, Paula

1980-01-01

405

Primary Aluminum Plants Worldwide - 1998  

USGS Publications Warehouse

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

1999-01-01

406

The Benefits of Aluminum Windows.  

ERIC Educational Resources Information Center

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)

Goyal, R. C.

2002-01-01

407

Lost-Soap Aluminum Casting.  

ERIC Educational Resources Information Center

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)

Mihalow, Paula

1980-01-01

408

The Benefits of Aluminum Windows.  

ERIC Educational Resources Information Center

|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)|

Goyal, R. C.

2002-01-01

409

Aluminum inhibits erythropoiesis in vitro.  

PubMed Central

Anemia has been associated with aluminum intoxication in patients on chronic dialysis and in animals. In studies presented here, in vitro human erythroid culture was used to delineate the effects of aluminum on normal hematopoiesis. Aluminum by itself in routine culture, even at very high levels (1,035 ng/ml), did not significantly affect erythroid colony growth. The addition of human transferrin to the culture, however, resulted in a marked dose-dependent inhibition of erythroid, but not myeloid colony growth. At all doses, CFU-E progenitors showed greater inhibition than burst-forming units (BFU-E). Aluminum inhibition was not overcome by increasing the dose of erythropoietin or adding additional burst-promoting activity to the culture. Inhibition by aluminum was directly related to the number of binding sites on transferrin in the culture, and was not observed in the presence of fully iron-saturated transferrin. Images

Mladenovic, J

1988-01-01

410

Channeling of aluminum in silicon  

SciTech Connect

A systematic study of channeling of aluminum in the silicon crystal is reported. Depth distributions measured by secondary ion mass spectrometry are reported for 40-, 75-, and 150-keV aluminum channeled in the <100> and <110> directions of silicon. The profile dependence on alignment angle is shown for 150-keV aluminum in the <110> of silicon. Aluminum has low electronic stopping in silicon and corresponding deep channeled profiles are observed for aligned implants and deep channeling tails are observed on random implants. The maximum channeling range for 150-keV Al in <100> silicon is about 2.8 ..mu..m and is about 6.4 ..mu..m in <110> silicon. Some ions will reach the maximum channeling range even for 2/sup 0/ misalignment. Many of the deep channeling tails and ''supertails'' reported in earlier literature can be explained by the normal channeling of aluminum in silicon.

Wilson, R.G.; Hopkins, C.G.

1985-05-15

411

Recovering aluminum via plasma processing  

NASA Astrophysics Data System (ADS)

A process based on the use of a plasma system for recovering aluminum from dross, beverage cans, and aluminum scrap has been developed. The plasma process is clean, and there is no need for the addition of any compound, such as salt. In principle, a higher recovery rate of aluminum is attainable, since no oxidation of the aluminum occurs during the process. An economic analysis shows that the operating costs for the plasma system are at least 23% cheaper than for the traditional process using air/gas or ail/oil burners; the plasma process also does not generate either of the common residues produced by the burners. The maintenance costs of the plasma process are also lower than that of the traditional process. Overall, the plasma system is cheaper, cleaner, and easier than the oil/gas burner technology when recovering aluminum from dross, beverage cans, and scrap.

Szente, R. N.; Schroeter, R. A.; Garcia, M. G.; Bender, O. W.

1997-11-01

412

Anodic Aluminum Oxide Diodes  

NASA Astrophysics Data System (ADS)

During anodic oxidation of aluminum, the incorporated anion species from the electrolyte are drawn into the growing barrier layer at the pore base by the high electric field and, afterward, migrate inward. The barrier layer consists of acid anion-contaminated regions adjacent to the oxide/electrolyte interface and relatively pure alumina further away from it. It can be presumed that there is a depletion layer region in between the acid anion-contaminated material and the pure alumina material. This study investigates the diode characteristics of the anodic aluminum oxide (AAO) film based on the depletion layer region presumption. Different electrolyte acids are employed to fabricate AAO diodes which possess different electrical properties. The current--voltage (I--V) characteristic curves indicate that the AAO devices possess the electrical property of a diode, especially the sulfuric acid processed AAO. It was observed that the threshold voltages for the sulfuric acid, oxalic acid, and phosphoric acid are 3.3, 8, and 16 V, respectively. This fits in with the sequential order presumption of the p, n depletion layer thicknesses for these three electrolyte acids.

Chang, Cheng-Yao; Wang, Gou-Jen

2011-07-01

413

Pinning the Order: The Nature of Quantum Criticality in the Hubbard Model on Honeycomb Lattice  

NASA Astrophysics Data System (ADS)

In numerical simulations, spontaneously broken symmetry is often detected by computing two-point correlation functions of the appropriate local order parameter. This approach, however, computes the square of the local order parameter, and so when it is small, very large system sizes at high precisions are required to obtain reliable results. Alternatively, one can pin the order by introducing a local symmetry-breaking field and then measure the induced local order parameter infinitely far from the pinning center. The method is tested here at length for the Hubbard model on honeycomb lattice, within the realm of the projective auxiliary-field quantum Monte Carlo algorithm. With our enhanced resolution, we find a direct and continuous quantum phase transition between the semimetallic and the insulating antiferromagnetic states with increase of the interaction. The single-particle gap, measured in units of Hubbard U, tracks the staggered magnetization. An excellent data collapse is obtained by finite-size scaling, with the values of the critical exponents in accord with the Gross-Neveu universality class of the transition.

Assaad, Fakher F.; Herbut, Igor F.

2013-07-01

414

Adsorption and desorption characteristics of semiconductor volatile organic compounds on the thermal swing honeycomb zeolite concentrator.  

PubMed

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

Chang, Feng-Tang; Lin, Yu-Chih; Bai, Hsunling; Pei, Bau-Shei

2003-11-01

415

Detecting damage in full-scale honeycomb sandwich composite curved fuselage panels through frequency response  

NASA Astrophysics Data System (ADS)

Preliminary tests were conducted using frequency response (FR) characteristics to determine damage initiation and growth in a honeycomb sandwich graphite/epoxy curved panel. This investigation was part of a more general study investigating the damage tolerance characteristics of several such panels subjected to quasi-static internal pressurization combined with hoop and axial loading. The panels were tested at the Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility located at the Federal Aviation Administration William J. Hughes Technical Center in Atlantic City, NJ. The overall program objective was to investigate the damage tolerance characteristics of full-scale composite curved aircraft fuselage panels and the evolution of damage under quasi-static loading up to failure. This paper focuses on one aspect of this comprehensive investigation: the effect of state-of-damage on the characteristics of the frequency response of the subject material. The results presented herein show that recording the frequency response could be used for real-time monitoring of damage growth and in determining damage severity in full-scale composites fuselage aircraft structures.

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

2008-04-01

416

Energy Gap and Averaged Inversion Symmetry of Tight-Binding Electrons on Generalized Honeycomb Lattice  

NASA Astrophysics Data System (ADS)

We study the condition to open a finite gap in tight-binding electrons on an extended honeycomb lattice with the next-nearest-neighbor transfer integrals t2a, t2b, t2c, t2d, t2e, and t2f, where t2a, t2b, and t2c are transfer integrals between the sublattice A and t2d, t2e, and t2f are transfer integrals between the sublattice B. If the system has the inversion symmetry in this model, i.e., the sublattices A and B have the same on-site potential (?A=?B), the gap is zero. We find that although the finite gap is generally opened by inversion-symmetry breaking, the gap remains zero if the averaged inversion symmetry, which is defined as the sum of the transfer integrals and the on-site potentials of the sublattices are the same (t2a+t2b+t2c+?A=t2d+t2e+t2f+?B), is conserved.

Kishigi, Keita; Hanada, Hirotoshi; Hasegawa, Yasumasa

2008-07-01

417

Sensory-organ-like response determines the magnetism of zigzag-edged honeycomb nanoribbons  

NASA Astrophysics Data System (ADS)

We present an analytical effective theory for the magnetic phase diagram for zigzag-edge terminated honeycomb nanoribbons described by a Hubbard model with an interaction parameter U. We show that the edge magnetic moment varies as lnU and uncover its dependence on the width W of the ribbon. The physics of this owes its origin to the sensory-organ-like response of the nanoribbons, demonstrating that considerations beyond the usual Stoner-Landau theory are necessary to understand the magnetism of these systems. A first-order magnetic transition from an antiparallel orientation of the moments on opposite edges to a parallel orientation occurs upon doping with holes or electrons. The critical doping for this transition is shown to depend inversely on the width of the ribbon. Using variational Monte Carlo calculations, we show that magnetism is robust to fluctuations. Additionally, we show that the magnetic phase diagram is generic to zigzag-edge terminated nanostructures such as nanodots. Furthermore, we perform first-principles modeling to show how such magnetic transitions can be realized in substituted graphene nanoribbons.

Bhowmick, Somnath; Medhi, Amal; Shenoy, Vijay B.

2013-02-01

418

Spectrum of the non-abelian phase in Kitaev's honeycomb lattice model  

SciTech Connect

The spectral properties of Kitaev's honeycomb lattice model are investigated both analytically and numerically with the focus on the non-abelian phase of the model. After summarizing the fermionization technique which maps spins into free Majorana fermions, we evaluate the spectrum of sparse vortex configurations and derive the interaction between two vortices as a function of their separation. We consider the effect vortices can have on the fermionic spectrum as well as on the phase transition between the abelian and non-abelian phases. We explicitly demonstrate the 2{sup n}-fold ground state degeneracy in the presence of 2n well separated vortices and the lifting of the degeneracy due to their short-range interactions. The calculations are performed on an infinite lattice. In addition to the analytic treatment, a numerical study of finite size systems is performed which is in exact agreement with the theoretical considerations. The general spectral properties of the non-abelian phase are considered for various finite toroidal systems.

Lahtinen, Ville [Quantum Information Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)], E-mail: ville.lahtinen@quantuminfo.org; Kells, Graham [Department of Mathematical Physics, National University of Ireland, Maynooth (Ireland); Carollo, Angelo [Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck (Austria); Stitt, Tim [Irish Centre for High-End Computing, National University of Ireland, Galway (Ireland); Vala, Jiri [Department of Mathematical Physics, National University of Ireland, Maynooth (Ireland); Pachos, Jiannis K. [Quantum Information Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom)], E-mail: j.k.pachos@leeds.ac.uk

2008-09-15

419

Selective recovery of catalyst layer from supporting matrix of ceramic-honeycomb-type automobile catalyst.  

PubMed

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

Kim, Wantae; Kim, Boungyoung; Choi, Doyoung; Oki, Tatsuya; Kim, Sangbae

2010-06-16

420

Evidence that estrogen regulates the sex change of honeycomb grouper (Epinephelus merra), a protogynous hermaphrodite fish.  

PubMed

Circulating estradiol-17beta (E2) levels decrease precipitously during female to male (protogynous) sex change in fish. Whether this drop in E2 levels is a cause or consequence of sex change is still largely unknown. The present study treated adult female honeycomb groupers (Epinephelus merra) with aromatase inhibitor (AI, Fadrozole), either alone or in combination with E2, to investigate the role of estrogen in protogynous sex change. Control fish had ovaries undergoing active vitellogenesis; the gonads of AI-treated fish had already developed into testes, which produced sperm capable of fertilization. In contrast, co-treatment of fish with E2 completely blocked AI-induced sex reversal. AI treatment significantly reduced circulating levels of E2, whereas the addition of E2 to AI prevented the loss. The plasma androgen (testosterone and 11-ketotestosterone) levels were increased in the AI-treated fish, while the levels in the E2-supplemented fish were low compared to controls. Present results show that E2 plays an important role in maintaining female sex of hermaphrodite fishes, and that the inhibition of E2 synthesis causes oocyte degeneration leading to testicular differentiation in the ovary. PMID:15880758

Bhandari, Ramji Kumar; Alam, Mohammad Ashraful; Higa, Mikihiko; Soyano, Kiyoshi; Nakamura, Masaru

2005-06-01

421

Multi-spin exchange model for a quantum spin liquid on the honeycomb lattice  

NASA Astrophysics Data System (ADS)

Recently, a possible quantum spin liquid (QSL) state has been found through quantum Monte Carlo studies of Hubbard model on the honeycomb lattice. The obtained QSL does not show long range correlation of any known type, which has a finite spin gap and a short range dimer-dimer correlation pattern resembling the short range resonant-valence-bond (RVB) state. Given the intensive current interest in such an exotic QSL, it is natural and timely to ask a question: what is the effective spin model to capture the essential low-energy physics near this QSL region? We report here a comparative numerical study based on finite-size exact diagonalizations (ED) of the Hubbard model, and a multi-spin exchange model with two-, four- and six-spin exchange terms. The latter model is derived from the strong coupling expansion of the former one. Through extensive ED calculations of low-energy spectra and ground-state correlation functions of both models, we try to establish connections between them, especially near the QSL region. Furthermore, the phase diagram of the multi-spin exchange model is explored in details.

Wang, Yi-Fei; Sheng, Donna; Gong, Chang-De

2011-03-01

422

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

NASA Astrophysics Data System (ADS)

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 was derived from an existing Whipple-shield BLE. This new BLE provided a good level of accuracy in predicting the ballistic performance of stand-alone sandwich panel structures. Additionally, the equation is capable of predicting the ballistic limit of a thin Al plate located at a standoff behind the sandwich panel structure. This thin plate is the representative of internal satellite systems, e.g. an Al electronic box cover, a wall of a metallic vessel, etc. Good agreement was achieved with both the experimental test campaign results and additional test data from the literature for the vast majority of set-ups investigated. For some experiments, the ballistic limit was conservatively predicted, a result attributed to shortcomings in correctly accounting for the presence of high surface density multi-layer insulation on the outer facesheet. Four existing BLEs commonly applied for application with stand-alone sandwich panels were reviewed using the new impact test data. It was found that a number of these common approaches provided non-conservative predictions for sandwich panels with CFRP facesheets.

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

423

Spectral radiant heat emitted by honeycomb-type solar collector covers  

NASA Astrophysics Data System (ADS)

A new type of transparent insulation with glass capillaries allows the construction of high temperature flat-plate solar collectors reaching stagnation temperatures of 260 degree(s)C and more. In the temperature range above 100 degree(s)C, the radiant heat is the dominant heat loss mechanism. For the plastic honeycomb materials used up to now, the heat losses were described adequately with a non-spectral `grey' model. To describe the radiant heat losses for the new glass capillary collector covers, a spectral analysis is necessary, due to the strong spectral dependence of the absorptance in glass. A new experimental set-up allows the measurements of the spectral radiant heat emitted by large samples, not only integrated over a hemisphere but also with angular resolution. A theoretical model for the calculation of the spectral, angle-dependent total emission of a Tl/absorber construction has been developed. The presented results of the calculations for glass capillaries show good agreement with the measurements.

Zipfel, Andreas; Dengler, Joerg J.; Platzer, Werner J.

1994-09-01

424

Quantum anomalous Hall states in the p-orbital honeycomb optical lattices  

SciTech Connect

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.

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

425

Quantum anomalous Hall states in the p-orbital honeycomb optical lattices  

NASA Astrophysics Data System (ADS)

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 ?, 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.

Zhang, Machi; Hung, Hsiang-Hsuan; Zhang, Chuanwei; Wu, Congjun

2011-02-01

426

Thermal decomposition of a honeycomb-network sheet: A molecular dynamics simulation study  

NASA Astrophysics Data System (ADS)

The thermal degradation of a graphene-like two-dimensional honeycomb membrane with bonds undergoing temperature-induced scission is studied by means of Molecular Dynamics simulation using Langevin thermostat. We demonstrate that at lower temperature the probability distribution of breaking bonds is highly peaked at the rim of the membrane sheet whereas at higher temperature bonds break at random everywhere in the hexagonal flake. The mean breakage time ? is found to decrease with the total number of network nodes N by a power law ? ~ N-0.5 and reveals an Arrhenian dependence on temperature T. Scission times are themselves exponentially distributed. The fragmentation kinetics of the average number of clusters can be described by first-order chemical reactions between network nodes ni of different coordination. The distribution of fragments sizes evolves with time elapsed from initially a ?-function through a bimodal one into a single-peaked again at late times. Our simulation results are complemented by a set of 1st-order kinetic differential equations for ni which can be solved exactly and compared to data derived from the computer experiment, providing deeper insight into the thermolysis mechanism.

Paturej, J.; Popova, H.; Milchev, A.; Vilgis, T. A.

2012-08-01

427

Evolution of Bloch-mode envelopes in two-dimensional generalized honeycomb lattices  

SciTech Connect

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 Schroedinger equations when the underlying group velocities are nearly zero. With semiclassical approximations, all the parameters are estimated analytically.

Ablowitz, Mark J.; Zhu Yi [Department of Applied Mathematics, University of Colorado, 526 UCB, Boulder, Colorado 80309-0526 (United States)

2010-07-15

428

High temperature testing of TRUPACT-I materials: Kevlar, honeycomb, rigid polyurethane foam  

SciTech Connect

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.

Hudson, M.L.

1985-12-01

429

Position actuators of the 6.5-m borosilicate honeycomb primary mirrors  

NASA Astrophysics Data System (ADS)

In order to collect as much information as possible from the universe, the latest generation of astronomical telescopes have exceptionally large diameter primary mirrors. This dramatic increase in mirror diameter, and corresponding increase in weight, has placed ever increasing demands on the technical performance of the mirror support system. In this paper the authors discuss the mechanical design, fabrication, and testing of the six servo controlled position-actuators that mechanically link the 6.5 m honeycomb mirror to six rigidly reinforced locations in the multiple mirror telescope conversion mirror cell. During telescope operation, these adjustable length actuators assure that the natural frequency of the mirror does not degrade the optical performance of the telescope. Flexures are provided on each end of the actuators to minimize any moments applied to the attachment of the actuator to the mirror. These actuators provide a precise measurement of the external forces applied to the mirror, such as wind loads, for the control of the pneumatic force system that supports the weight of the mirror. The total length of each actuator can be measured to sub-micron resolution upon request. Each actuator has a reliable fail-safe system that limits the compressive and tensile forces that can be applied to the mirror. The position-actuators meet all of the above technical specifications in both tension and compression.

Miglietta, Luciano; Callahan, Shawn

1996-11-01

430

Solidification behavior of undercooled liquid aluminum oxide  

SciTech Connect

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.

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

1995-03-01

431

Aluminum: Industry of the future  

SciTech Connect

For over a century, the US aluminum industry has led the global market with advances in technology, product development, and marketing. Industry leaders recognize both the opportunities and challenges they face as they head into the 21st century, and that cooperative R and D is key to their success. In a unique partnership, aluminum industry leaders have teamed with the US Department of Energy`s Office of Industrial Technologies (OIT) to focus on innovative technologies that will help to strengthen the competitive position of the US aluminum industry and, at the same time, further important national goals. This industry-led partnership, the Aluminum Industry of the Future, promotes technologies that optimize the use of energy and materials in operations and reduce wastes and energy-related emissions. Led by The Aluminum Association, industry leaders began by developing a unified vision of future market, business, energy, and environmental goals. Their vision document, Partnerships for the Future, articulates a compelling vision for the next 20 years: to maintain and grow the aluminum industry through the manufacture and sale of competitively priced, socially desirable, and ecologically sustainable products. Continued global leadership in materials markets will require the combined resources of industry, universities, and government laboratories. By developing a unified vision, the aluminum industry has provided a framework for the next step in the Industries of the Future process, the development of a technology roadmap designed to facilitate cooperative R and D.

NONE

1998-11-01

432

Aluminum chlorohydrate II: Physicochemical properties.  

PubMed

Determination of the chloride content of aluminum chlorohydrate by a chloride-selective indicated that gamma Cl leads to 1. IR analysis demonstrated that chloride was exchanged readily by nitrate and that the IR bands of the anion were not perturbed significantly. Thus, chloride is believed to act as a counterion. A high positive charge is predicted based o the critical coagulation concentration of aluminum chlorohydrate and the stability of aluminum chlorohydrate to attack by protons, as demonstrated by pH-stat titration Potentiometric titration with sodium hydroxide showed adsorption of hydroxyl anions initially, but a higher pH than expected was observed at the end-point. This behavior is consistent with the Al13O4(OH)24(H2O)7+12 complex, which would adsorb hydroxyl anions initially and in which the central tetrahedral aluminum is shielded from the added hydroxyl anions. The reaction rate with ferron (8-hydroxy-7-iodo-5-quinolinesulfonic acid) suggests that the major species in aluminum chlorohydrate is a large aluminum poly-cation. A platey morphology for lyophilized, air-dried, and spray-dried aluminum chlorohydrate was observed by scanning electron microscopy. The platey appearance is consistent with the structure of Al13O4(OH)24(H2O)7+12 since the spherical nature and high uneven charge of the complex make stacking difficult. PMID:7264922

Teagarden, D L; Radavich, J F; White, J L; Hem, S L

1981-07-01

433

Study of aluminum nitride formation by superfine aluminum powder combustion in air  

Microsoft Academic Search

An experimental study on the combustion of superfine aluminum powders (average particle diameter as?0.1 ?m) in air is reported. Formation of aluminum nitride during combustion of aluminum in air is focused in this study. Superfine aluminum powders were produced by wire electrical explosion (WEE) method. Such superfine aluminum powder is stable in air but, if ignited, it can burn in

Alexander Gromov; Vladimir Vereshchagin

2004-01-01

434

Stainable aluminum and not aluminum content reflects bone histology in dialyzed patients  

Microsoft Academic Search

Stainable aluminum and not aluminum content reflects bone histology in dialyzed patients. Quantitative evaluation of stainable bone aluminum and measurement of bone aluminum content were done in 55 patients on chronic maintenance dialysis. All patients underwent bone biopsies. Histomorphometry of static and dynamic parameters of bone structure, bone formation and resorption, and quantitation of stainable bone aluminum at the osteoid–bone

Hartmut H Malluche

1986-01-01

435

PREPARATION OF URANIUM-ALUMINUM ALLOYS  

DOEpatents

A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)

Moore, R.H.

1962-09-01

436

Aluminum Plasmonic Nanoantennas  

NASA Astrophysics Data System (ADS)

We have explored the plasmonic properties of individual Al nanorod antennas fabricated by planar lithography on lightly doped n-type silicon. Energy-resolved cathodoluminescence was used to image the local density of optical states with a spatial resolution of ˜ 20 nm and thereby identify the radiative modes of these nanostructures. Al nanoantenna emission exhibited highly tunable plasmonic resonances from the deep UV through the visible region of the spectrum. The dependence of the radiative dipolar and quadrupolar plasmon modes on antenna length and photon energy agreed well with finite difference time domain-based analysis of these nanostructures. The results herald nano-structured aluminum as a practical and highly promising material system for the design and implementation of UV and visible frequency plasmonics, broadening the range of potential applications of plasmonics into areas where complementary metal-oxide-semiconductor (CMOS) compatibility or low-cost, mass producibility are desired.

Everitt, Henry; Knight, Mark; Liu, Lifei; Yang, Yumin; Brown, Lisa; Mukherjee, Shaunak; King, Nicholas; Nordlander, Peter; Halas, Naomi

2013-03-01

437

Spray Rolling Aluminum Strip  

SciTech Connect

Spray forming is a competitive low-cost alternative to ingot metallurgy for manufacturing ferrous and non-ferrous alloy shapes. It produces materials with a reduced number of processing steps, while maintaining materials properties, with the possibility of near-net-shape manufacturing. However, there are several hurdles to large-scale commercial adoption of spray forming: 1) ensuring strip is consistently flat, 2) eliminating porosity, particularly at the deposit/substrate interface, and 3) improving material yield. Through this program, a new strip/sheet casting process, termed spray rolling, has been developed, which is an innovative manufacturing technique to produce aluminum net-shape products. Spray rolling combines the benefits of twin-roll casting and conventional spray forming, showing a promising potential to overcome the above hurdles associated with spray forming. Spray rolling requires less energy and generates less scrap than conventional processes and, consequently, enables the development of materials with lower environmental impacts in both processing and final products. Spray Rolling was developed as a collaborative project between the University of California-Davis, the Colorado School of Mines, the Idaho National Engineering and Environmental Laboratory, and an industry team. The following objectives of this project were achieved: (1) Demonstration of the feasibility of the spray rolling process at the bench-scale level and evaluation of the materials properties of spray rolled aluminum strip alloys; and (2) Demonstration of 2X scalability of the process and documentation of technical hurdles to further scale up and initiate technology transfer to industry for eventual commercialization of the process.

Lavernia, E.J.; Delplanque, J-P; McHugh, K.M.

2006-05-10

438

Plasmasynthesized nano-aluminum powders  

Microsoft Academic Search

The plasma electro-condensation\\u000a process was used to synthesize nano-sized aluminum powders. Adding different\\u000a chemicals modified the physical and chemical properties of these powders.\\u000a To characterize the nano-sized powders, X-ray diffraction, TEM, BET analyses,\\u000a and simultaneous TG\\/DSC analyses were performed. TG\\/DSC analyses revealed\\u000a a dramatic degradation of the aluminum oxide layer after storage of the aluminum\\u000a powder in air for a

Alla Pivkina; D. Ivanov; Yu. Frolov; Svetlana Mudretsova; Anna Nickolskaya; J. Schoonman

2006-01-01

439

Extracting aluminum from dross tailings  

Microsoft Academic Search

Aluminum dross tailings, an industrial waste, from the Egyptian Aluminium Company (Egyptalum) was used to produce two types\\u000a of alums: aluminum-sulfate alum [itAl2(SO4)3.12H2O]and ammonium-aluminum alum [(NH\\u000a 4)2SO4AL2(SO4)3.24H2O]. This was carried out in two processes. The first process is leaching the impurities using diluted H2SO4 with different solid\\/liquid ratios at different temperatures to dissolve the impurities present in the starting material

A. M. Amer

2002-01-01

440

Extracting aluminum from dross tailings  

Microsoft Academic Search

Aluminum dross tailings, an industrial waste, from the Egyptian Aluminium Company (Egyptalum) was used to produce two types of alums: aluminum-sulfate alum [itAl2(SO4)3.12H2O] and ammonium-aluminum alum [ (NH 4)2SO4AL2(SO4)3.24H2O]. This was carried out in two processes. The first process is leaching the impurities using diluted H2SO4 with different solid\\/liquid ratios at different temperatures to dissolve the impurities present in the

A. M. Amer

2002-01-01

441

Aluminum hydroxide issue closure package  

SciTech Connect

Aluminum hydroxide coatings on fuel elements stored in aluminum canisters in K West Basin were measured in July and August 1998. Good quality data was produced that enabled statistical analysis to determine a bounding value for aluminum hydroxide at a 99% confidence level. The updated bounding value is 10.6 kg per Multi-Canister Overpack (MCO), compared to the previously estimated bounding value of 8 kg/MCO. Thermal analysis using the updated bounding value, shows that the MCO generates oxygen concentrate that are below the lower flammability limits during the 40-year interim storage period and are, therefore, acceptable.

Bergman, T.B.

1998-08-26

442

Aluminum chlorohydrate I: Structure studies.  

PubMed

X-ray diffraction and IR and 27AI-NMR spectroscopy indicate that aluminum chlorohydrate is composed of a central aluminum in a tetrahedral configuration surrounded by 12 aluminum atoms in octahedral configuration. The complex, AI13O4(OH)24(H2O)7+12, is essentially spherical, with the +7 charge equally distributed on the surface. Seven chloride ions are associated with the complex as counterions. This structure is consistent with both the method of synthesis and the proposed mechanism of antiperspirant activity. PMID:7264921

Teagarden, D L; Kozlowski, J F; White, J L; Hem, S L

1981-07-01

443

Failure Properties of Aluminum and Aluminum Alloys under Impact Conditions.  

National Technical Information Service (NTIS)

Research under this grant was directed to two distinct tasks. First was study of the kinetics of shock-induced phase transitions in solids; second was measurement of precursor amplitudes in aluminum under carefully controlled conditions. Shock-induced str...

G. E. Duvall G. R. Fowles

1976-01-01

444

Molecular cluster models of aluminum oxide and aluminum hydroxide surfaces  

Microsoft Academic Search

Ab initio, molecular orbital calculations for two different Hartree-Fock basis levels were performed on clusters in the system Al-O-H, and tested by comparing derived vibrational frequencies to the measured values for aluminum oxides and aluminum oxyhydroxide minerals. Models were chosen to reflect surface groups that may be present on aluminous minerals such as a-Al2O3 (corundum) and Al(OH)3 (gibbsite). Protonation and

J. D. KUBICKI; S. E. APITZ

1998-01-01

445

An experimental investigation into the energy absorption and force\\/displacement characteristics of aluminum foam filled braided stainless steel tubes under quasistatic tensile loading conditions  

Microsoft Academic Search

Experimental tensile testing of aluminum foam filled braided stainless steel tubes was completed in this research investigation. The kinematic constraints imposed on the individual tows of the braided tube provided for a reduction in tube diameter under axial elongation of the tube ends. Encasing an aluminum foam core within the tube and deforming the structure under tensile loading was completed

W. Altenhof; C. Powell; Anne-Marie Harte; R. Gaspar

2005-01-01

446

CHARACTERIZING AND MODELING FERRITE-CORE PROBES  

SciTech Connect

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.

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

447

Quantum critical transport at a semimetal-to-insulator transition on the honeycomb lattice  

NASA Astrophysics Data System (ADS)

In this paper, we study transport properties of electrons on the two-dimensional honeycomb lattice. We consider a half-filled system in the vicinity of a symmetry-breaking transition from a semimetallic phase toward an insulating phase with either charge-density- or spin-density-wave order. The effect of either order is to break the sublattice inversion symmetry, which induces a finite gap for the electronic single-particle excitations. Phenomenologically, such a scenario is described in the framework of a Gross-Neveu theory. We analyze two related formulations of the model by means of (i) a controlled renormalization-group calculation and (ii) the large-N method, both of which in combination with a Boltzmann transport equation. We determine the quantum critical conductivity and also discuss crossover behavior from quantum critical behavior into the insulating and/or the semimetallic phases. We find that at asymptotically low temperatures, the quantum critical conductivity is given by a temperature-independent universal number. Over a large temperature window, the temperature-independent quantum-critical conductivity is masked by a logarithmically temperature-dependent contribution due to the marginally irrelevant long-range Coulomb interaction. We discuss possible origins of this peculiarity in the two complementary formulations of the model. Furthermore, we consider possible relations of our findings to recent experiments, with a special emphasis on the quantum-critical-to-insulator crossover. We find that our results are in remarkably good qualitative and quantitative agreement with a recent analysis of the data sets under the hypothesis of an underlying gap in the single-particle spectrum.

Fritz, Lars

2011-01-01

448

Aluminum-Air Battery Crystallizer.  

National Technical Information Service (NTIS)

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 ...

A. Maimoni

1987-01-01

449

Aluminum Castings for Anodic Oxidation.  

National Technical Information Service (NTIS)

The significance of the manufacture of decorative anodically oxidized aluminum castings is demonstrated by means of examples, and alloys suitable for this are enumerated. Then dealt with are errors of casting and melting technique which become apparent wi...

A. A. Bloch

1966-01-01

450

Aluminum-Lithium Target Behavior.  

National Technical Information Service (NTIS)

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). Ph...

W. R. McDonell

1989-01-01

451

Transparent, Polycrystalline Cubic Aluminum Oxide.  

National Technical Information Service (NTIS)

The stringent mechanical/thermal and broadband electromagnetic wave transmission requirements for sensing mechanisms of the future require optimized and new material concepts. Aluminum oxide-based ceramics and single crystals are strong contenders for the...

J. W. McCauley N. D. Corbin

1980-01-01

452

Electrolyte treatment for aluminum reduction  

DOEpatents

A method of treating an electrolyte for use in the electrolytic reduction of alumina to aluminum employing an anode and a cathode, the alumina dissolved in the electrolyte, the treating improving wetting of the cathode with molten aluminum during electrolysis. The method comprises the steps of providing a molten electrolyte comprised of ALF.sub.3 and at least one salt selected from the group consisting of NaF, KF and LiF, and treating the electrolyte by providing therein 0.004 to 0.2 wt. % of a transition metal or transition metal compound for improved wettability of the cathode with molten aluminum during subsequent electrolysis to reduce alumina to aluminum.

Brown, Craig W. (Seattle, WA); Brooks, Richard J. (Seattle, WA); Frizzle, Patrick B. (Seattle, WA); Juric, Drago D. (Bulleen, AU)

2002-01-01

453

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

Federal Register 2010, 2011, 2012, 2013

...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...

2010-11-18

454

Precipitation hardening of aluminum alloys  

Microsoft Academic Search

The author’s charge was to discuss recent trends in research and development on precipitation hardened aluminum alloys and\\u000a to indicate where research is needed. This will be done for three areas: fatigue, properties of grain boundaries and interfaces,\\u000a and stability of precipitates at elevated temperatures. Present strong precipitation hardened aluminum alloys do not have\\u000a high endurance limits. One problem is

Morris E. Fine

1975-01-01

455

Aluminum-air battery crystallizer  

Microsoft Academic Search

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

A. Maimoni

1987-01-01

456

Creep of laminated aluminum composites  

Microsoft Academic Search

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

W. Moore; T. J. Davies

1980-01-01

457

Effect of short-range interactions on the quantum critical behavior of spinless fermions on the honeycomb lattice  

NASA Astrophysics Data System (ADS)

We present a functional renormalization group investigation of an Euclidean three-dimensional matrix Yukawa model with U(N) symmetry, which describes N=2 Weyl fermions that effectively interact via a short-range repulsive interaction. This system relates to an effective low-energy theory of spinless electrons on the honeycomb lattice and can be seen as a simple model for suspended graphene. We find a continuous phase transition characterized by large anomalous dimensions for the fermions and composite degrees of freedom. The critical exponents define a new universality class distinct from Gross-Neveu type models, typically considered in this context.

Mesterházy, D.; Berges, J.; von Smekal, L.

2012-12-01

458

Fundamental Differences between Quantum Spin Hall Edge States at Zigzag and Armchair Terminations of Honeycomb and Ruby Nets.  

PubMed

Combining an analytical and numerical approach we investigate the dispersion of the topologically protected spin-filtered edge states of the quantum spin Hall state on honeycomb and ruby nets with zigzag (ZZ) and armchair (AC) edges. We show that the Fermi velocity of the helical edge states on ZZ edges increases linearly with the strength of the spin-orbit coupling (SOC) whereas for AC edges the Fermi velocity is independent of the SOC. Also the decay length of edge states into the bulk is dramatically different for AC and ZZ edges, displaying an inverse functional dependence on the SOC. PMID:24138261

Cano-Cortés, Laura; Ortix, Carmine; van den Brink, Jeroen

2013-10-02

459

Kitaev-Heisenberg Model on a Honeycomb Lattice: Possible Exotic Phases in Iridium Oxides A2IrO3  

NASA Astrophysics Data System (ADS)

We derive and study a spin one-half Hamiltonian on a honeycomb lattice describing the exchange interactions between Ir4+ ions in a family of layered iridates A2IrO3 (A=Li,Na). Depending on the microscopic parameters, the Hamiltonian interpolates between the Heisenberg and exactly solvable Kitaev models. Exact diagonalization and a complementary spin-wave analysis reveal the presence of an extended spin-liquid phase near the Kitaev limit and a conventional Néel state close to the Heisenberg limit. The two phases are separated by an unusual stripy antiferromagnetic state, which is the exact ground state of the model at the midpoint between two limits.

Chaloupka, Ji?í; Jackeli, George; Khaliullin, Giniyat

2010-07-01

460

Vortex interaction enhanced saturation number and caging effect in a superconducting film with a honeycomb array of nanoscale holes.  

SciTech Connect

The electrical transport properties of a MoGe thin film with a honeycomb array of nanoscale holes are investigated. The critical current of the system shows nonmatching anomalies as a function of applied magnetic field, enabling us to distinguish between multiquanta vortices trapped in the holes and interstitial vortices located between the holes. The number of vortices trapped in each hole is found to be larger than the saturation number predicted for an isolated hole and shows a nonlinear field dependence, leading to the caging effect as predicted from the Ginzburg-Landau (GL) theory. Our experimental results are supplemented by numerical simulations based on the GL theory.

Latimer, M. L.; Berdiyorov, G. R.; Xiao, Z. L.; Kwok, W. K.; Peeters, F. M. (Materials Science Division); (Northern Illinois Univ.); (Universiteit Antwerpen)

2012-01-01

461

Time-reversal symmetry breaking superconducting ground state in the doped Mott insulator on the honeycomb lattice  

NASA Astrophysics Data System (ADS)

The emergence of superconductivity in doped Mott insulators has been debated for decades. In this paper, we report the theoretical discovery of a time-reversal symmetry breaking superconducting ground state in the doped Mott insulator (described by the well known t-J model) on honeycomb lattice, based on a recently developed variational method: the Grassmann tensor product state approach. As a benchmark, we use exact diagonalization and density-matrix renormalization methods to check our results on small clusters. We find systematic consistency for the ground-state energy as well as other physical quantities, such as the staggered magnetization. At low doping, the superconductivity coexists with antiferromagnetic ordering.

Gu, Zheng-Cheng; Jiang, Hong-Chen; Sheng, D. N.; Yao, Hong; Balents, Leon; Wen, Xiao-Gang

2013-10-01

462

Magnetic study under external high pressure and magnetic field in low dimensional honeycomb lattice In3Cu2VO9  

NASA Astrophysics Data System (ADS)

Low dimensional In3Cu2VO9 system, consisting of honeycomb lattice structure of magnetic Cu+2, is reported to be a two dimensional (2D) frustrated system. The doping of magnetic Co+2 at Cu site destroys the 2D magnetic frustration gradually driving it to antiferromagnetically long range ordered state. The nonmagnetic Zn doping at Cu site has been known to reduce the Neel temperature, eventually become paramagnetic for further doping. It is not clear whether the lattice parameter is playing any major role in the modification of magnetic interactions. This has motivated us to investigate the effect of hydrostatic pressure on the magnetic properties of this compound.

Iyer, Kartik K.; Basu, Tathamay; Singh, A. K.; Mukherjee, K.; Paulose, P. L.; Sampathkumaran, Echur V.

2013-06-01

463

Fundamental Differences between Quantum Spin Hall Edge States at Zigzag and Armchair Terminations of Honeycomb and Ruby Nets  

NASA Astrophysics Data System (ADS)

Combining an analytical and numerical approach we investigate the dispersion of the topologically protected spin-filtered edge states of the quantum spin Hall state on honeycomb and ruby nets with zigzag (ZZ) and armchair (AC) edges. We show that the Fermi velocity of the helical edge states on ZZ edges increases linearly with the strength of the spin-orbit coupling (SOC) whereas for AC edges the Fermi velocity is independent of the SOC. Also the decay length of edge states into the bulk is dramatically different for AC and ZZ edges, displaying an inverse functional dependence on the SOC.

Cano-Cortés, Laura; Ortix, Carmine; van den Brink, Jeroen

2013-10-01

464

Topological properties of bulk and edge states in honeycomb lattice photonic crystals: the case of TE polarization.  

PubMed

Topological properties of bulk and edge states in honeycomb lattice photonic crystals are investigated theoretically for transverse-electric (TE) polarization. Breaking of space-inversion and time-reversal symmetries is considered at optical frequencies. The bulk band structure exhibits a topological phase transition by changing the degree of the broken symmetries. The resulting phase diagram correlates with zigzag and armchair edge states, and the so-called bulk-edge correspondence is verified. The effects of flat interfaces near the edges are also discussed. PMID:21393746

Ochiai, Tetsuyuki

2010-05-21

465

Preparation and Functions of Hybrid Membranes with Rings of Ag NPs Anchored at the Edges of Highly Ordered Honeycomb-Patterned Pores.  

PubMed

We report a new, simple strategy to apply honeycomb films for the patterning of colloidal particles. By combination of a "bottom-up" breath figure method and the electrochemical properties of the honeycomb films of ferrocenyl-based oligomers, highly ordered hybrid membranes coated with ring-like patterning of 0D- and 1D-Ag nanoparticles (NPs) have been fabricated. One interesting phenomenon is that the nucleation and adsorption of Ag dots occurred preferentially at the edges of the micropores. The hybrid membranes exhibited richly electrochemical activities towards reduction of iodate and enhanced effectively catalytic reduction of organic dyes. We believe that this method can be used to decorate and/or assemble functional metal NPs such as Au, Pd, and Cu on honeycomb-patterned materials for the further applications of photonics, sensors, and catalysis. PMID:23939752

Dong, Renhao; Xu, Jiaheng; Yang, Zhefei; Wei, Guangcheng; Zhao, Wenrong; Yan, Junlin; Fang, Yu; Hao, Jingcheng

2013-08-12

466

Negative magnetization of Li2Ni2Mo3O12: A spin system composed of distorted honeycomb lattices and linear chains  

NASA Astrophysics Data System (ADS)

We study the magnetism of a spin-1 substance Li2Ni2Mo3O12. The spin system consists of distorted honeycomb lattices and linear chains of Ni2+ spins. Li+ ions enter about 25% and 50% of the honeycomb and chain Ni sites, respectively, creating disorder in both spin subsystems. A magnetic phase transition occurs at Tc=8.0 K in the zero magnetic field. In low magnetic fields, the magnetization increases rapidly below Tc, decreases below 7 K, and finally becomes negative at low temperatures. We determine the magnetic structure using neutron-powder-diffraction results. The honeycomb lattices and linear chains show antiferromagnetic and ferromagnetic long-range order, respectively. We investigate static and dynamic magnetic properties using the local probe technique of muon spin relaxation. We discuss the origin of the negative magnetization.

Hase, Masashi; Pomjakushin, Vladimir Yu.; Sikolenko, Vadim; Keller, Lukas; Luetkens, Hubertus; Dönni, Andreas; Kitazawa, Hideaki

2011-09-01

467

NASA-UVA Light Aerospace Alloy and Structure Technology Program Supplement: Aluminum-Based Materials for High Speed Aircraft. Final report, 1 December 1991-31 March 1996  

SciTech Connect

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 with 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.

Starke, E.A. Jr.

1996-05-01

468

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

SciTech Connect

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.

Not Available

2006-04-01

469

Lowering of Initial Anodizing Current Density due to Thin Aluminum Oxide Film on Evaporated Aluminum  

NASA Astrophysics Data System (ADS)

Initial current densities under constant voltage anodic oxidation are measured to estimate aluminum oxide film thickness on aluminum. It is shown that the logarithm of initial current density ratio with and without a thin aluminum oxide on aluminum is proportional to the logarithm of the exposure time to dry air. Auger electron spectroscopy measurements show that the surface of aluminum exposed to dry air is covered with a thicker aluminum oxide film than an aluminum surface just after aluminum oxide etching by an aqueous 5% sulfamic acid.

Kikuchi, Akira

1985-01-01

470

Core breaker  

SciTech Connect

This patent describes a continuous mining machine having at least a pair of horizontally spaced and aligned rotatable cutter drums, an improved core breaker operatively associated with the cutter drums and comprising: an arcuate fixed support disposed between the drums; an elongated bit holder fixed to and extending outwardly from the support; the holder structure having a series of longitudinally spaced, core breaker bit accommodating apertures extending therethrough; each aperture being defined by a smaller diameter outer bore, a larger diameter inner bore and a shoulder extending generally normal to the aperture axis separating the bores; and a bit element and expansion ring assembly disposed in operative association with the cutter drums, accommodated in each aperture.

Morgan, V.B.; Mc Kinney, J.F.

1987-06-02

471

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

NASA Astrophysics Data System (ADS)

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

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

472

Aluminum laser welding optimization  

NASA Astrophysics Data System (ADS)

Pulsed Nd:YAG laser with maximal power 150 W is used in our laboratory to cut, drill and weld metal and non-metal thin materials to thickness 2 mm. Welding is realized by fixed processing head or movable fiber one with beam diameter 0,6 mm in focus plane. Welding of stainless and low-carbon steel was tested before and results are publicized and used in practice. Now the goal of our experiment was optimization of process parameters for aluminum that has other physical properties than steels, lower density, higher heat conductivity and surface reflexivity. Pure alumina specimen 0,8 mm and Al-Mg-Si alloy 0,5 mm prepared for butt welds. Problem with surface layer of Al2O3 was overcome by sanding and chemical cleaning with grinding paste. Critical parameters for good weld shape are specimen position from beam focus plane, pulse length and energy, pulse frequency and the motion velocity that determines percentage of pulse overlap. Argon as protective gas was used with speed 6 liters per second. Thermal distribution in material can be modeled by numerical simulation. Software tool SYSWELD makes possible to fit laser as surface heat source, define weld geometry, and make meshing of specimen to finite elements and compute heat conduction during process. Color isotherms, vectors, mechanical deformations and others results can be study in post-processing.

Chmelí?ková, Hana; Halenka, Viktor; Lapšanská, Hana; Havelková, Martina

2007-05-01

473

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

Microsoft Academic Search

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

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

2000-01-01

474

Pilot-Scale Preparation of Nanometer Photocatalytic Film for Air Purification by Loading Commercial Nanometer Titanium Oxide Powder on Honeycomb Aluminum  

Microsoft Academic Search

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

Hongyou Hu; Xuemei Li

2011-01-01

475

Heterogeneous nucleation of sigma' on dislocations in a dilute aluminum-lithium alloy  

Microsoft Academic Search

The nucleation of S on dislocations with small undercooling in binary aluminum-lithium alloys has been examined. The study of related microstructures was performed using transmission electron microscopy (TEM), which demonstrates that sigma' preferentially nucleates on dislocations with a strong edge character and locates at the side where the stress field is compressive without destroying the dislocation core structure. This qualitatively

Z. M. Wang; G. J. Shiflet

1996-01-01

476

Induction of female-to-male sex change in the honeycomb grouper (Epinephelus merra) by 11-ketotestosterone treatments.  

PubMed

The honeycomb grouper, Epinephelus merra, is a protogynous hermaphrodite fish. Sex steroid hormones play key roles in sex change of this species. A significant drop in endogenous estradiol-17beta (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 of an androgen in sex change, we attempted to induce female-to-male sex change by exogenous 11KT treatments. The 75-day 11KT treatment caused 100% masculinization of pre-spawning females. Ovaries of the control (vehicle-treated) fish had oocytes at various stages of oogenesis, while the gonads of the 11KT-treated fish had transformed into testes; these contained spermatogenic germ cells at various stages, including an accumulation of spermatozoa in the sperm duct. In the sex-changed fish, plasma levels of E2 were significantly low, while both testosterone (T) and 11KT were significantly increased. Our results suggest that 11KT plays an important role in sex change in the honeycomb grouper. Whether the mechanism of 11KT-induced female-to-male sex change acts through direct stimulation of spermatogenesis in the ovary or via the inhibition of estrogen synthesis remains to be clarified. PMID:16547407

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

2006-01-01

477

Clay honeycomb monoliths for water purification: Modulating methylene blue adsorption through controlled activation via natural coal templating  

NASA Astrophysics Data System (ADS)

Texturally modified clay honeycomb monoliths were prepared for use as filters to remove pollutants from water solutions. An easy, economical, "green chemistry" activation route was employed during the preparation to enhance the adsorption capacity of the honeycombs. The method involves mixing the clay before its extrusion with a natural coal that is subsequently eliminated from the monolith by heating it under air at the lowest possible temperature (440 °C according to a thermogravimetric study). The size of the coal particles used as a template was intentionally modified by adjusting the milling process (dry or wet) and its duration (1–120 min) to modulate the porosity induced in the clay monoliths after their further burning. N2 physisorption, mercury porosimetry, granulometry and SEM were used to investigate the influence of the above preparative variables on the textural properties of the clay, significant effects being found in the macropore range. Methylene blue adsorption tests under dynamic conditions suggest that there is a correlation between pollutant removal and the macropore structure generated. FTIR spectroscopy indicates that the differences observed in cationic dye adsorption over the monoliths must be related to their different texture rather than to differences in the nature of their surface hydroxyl groups.

Gatica, José M.; Gómez, Diana M.; Harti, Sanae; Vidal, Hilario

2013-07-01