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1

Design and applications of negative index metamaterials  

Microsoft Academic Search

Electromagnetic Negative Index Metamaterials (NIM) exhibit many novel phenomena such as negative Snell's law, backward wave propagation, reverse Cerenkov radiation, and reverse Doppler effect. Predicted theoretically by Veselago in 1968 and experimentally demonstrated and verified barely a decade ago, it has enabled many proof-of-concept applications not achievable with ordinary materials. However, from a practical perspective, synthesis issues such as material

Tai Anh Lam

2010-01-01

2

The Science of Negative Index Materials  

SciTech Connect

Metamaterials are designed to have structures that make available properties not found in Nature. Their unique properties (such as negative index of refraction, n) can be extended from GHz all the way to optical frequencies. We review the scaling properties of metamaterials that have been fabricated and give negative n and negative permeability, {mu}. It is found that most of the experimentally realized metamaterials have {lambda}/{alpha} between 2 (THz and optical region) and 12 (GHz region), where {lambda} is the operation wavelength and {alpha} is the size of the unit cell. The transmission losses for the experimental structures and the ratio {lambda}/{alpha} for the simulated structures are presented. Finally, a comparison of the different metamaterial designs (fishnet, cut and/or continuous wires, and split-ring resonators and wires) is given.

Costas M. Soukoulis; Jiangfeng Zhou; Thomas Koschny; Maria Kafesaki; Eleftherios N. Economou

2008-07-08

3

Modulation instability in nonlinear negative-index material.  

PubMed

We investigate modulation instability (MI) in negative-index material (NIM) with a Kerr nonlinear polarization based on a derived (3+1)-dimensional nonlinear Schrödinger equation for ultrashort pulse propagation. By a standard linear stability analysis, we obtain the expression for instability gain, which unifies the temporal, spatial, and spatiotemporal MI. It is shown that negative refraction not only brings some new features to MI, but also makes MI possible in ordinary material in which it is otherwise impossible. For example, spatial MI can occur in the defocusing regime, while it only occurs in the focusing regime in ordinary material. Spatiotemporal MI can appear in NIM in the case of anomalous dispersion and defocusing nonlinearity, while it cannot appear in ordinary material in the same case. We believe that the difference between the MI in NIM and in ordinary material is due to the fact that negative refraction reverses the sign of the diffraction term, with the signs of dispersion and nonlinearity unchanged. The most notable property of MI in NIM is that it can be manipulated by engineering the self-steepening effect by choosing the size of split-ring resonator circuit elements. To sum up the MI in ordinary material and in NIM, MI may occur for all the combinations of dispersion and nonlinearity. PMID:16605687

Wen, Shuangchun; Wang, Youwen; Su, Wenhua; Xiang, Yuanjiang; Fu, Xiquan; Fan, Dianyuan

2006-03-01

4

Stability criterion for Gaussian pulse propagation through negative index materials  

SciTech Connect

We analyze the dynamics of propagation of a Gaussian light pulse through a medium having a negative index of refraction employing the recently reported projection operator technique. The governing modified nonlinear Schroedinger equation, obtained by taking into account the Drude dispersive model, is expressed in terms of the parameters of Gaussian pulse, called collective variables, such as width, amplitude, chirp, and phase. This approach yields a system of ordinary differential equations for the evolution of all the pulse parameters. We demonstrate the dependence of stability of the fixed-point solutions of these ordinary differential equations on the linear and nonlinear dispersion parameters. In addition, we validate the analytical approach numerically utilizing the method of split-step Fourier transform.

Joseph, Ancemma; Porsezian, K. [Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, Pondicherry 605 014 (India)

2010-02-15

5

Frequency-domain simulations of a negative-index material with embedded gain.  

PubMed

We solve the equations governing light propagation in a negative-index material with embedded nonlinearly saturable gain material using a frequency-domain model. We show that available gain materials can lead to complete loss compensation only if they are located in the regions where the field enhancement is maximal. We study the increased enhancement of the fields in the gain composite as well as in the metal inclusions and show analytically that the effective gain is determined by the average near-field enhancement. PMID:20052118

Sivan, Yonatan; Xiao, Shumin; Chettiar, Uday K; Kildishev, Alexander V; Shalaev, Vladimir M

2009-12-21

6

Modulational instability of coupled nonlinear field equations for pulse propagation in a negative index material embedded into a Kerr medium  

Microsoft Academic Search

We have investigated the modulational instability (MI) in a negative index media (NIM) using a new generalized model describing the pulse propagation in a negative index material embedded into a Kerr medium. We have found that one could control the gain of MI in a NIM by tuning the initial electric or magnetic field amplitudes . Our model successfully recovers

Amarendra K. Sarma; Manirupa Saha

2011-01-01

7

Soliton propagation in negative-index materials with self-steepening effect  

NASA Astrophysics Data System (ADS)

In this paper, nonlinear Schrödinger equation (NLSE) with self-steepening term for dispersive permittivity and permeability which governs the ultrashort pulse propagation through negative-index materials (NIMs) is studied. The Lax pair is constructed for this model by employing AKNS procedure. The soliton solutions are generated with symbolic computation through Darboux transformation and the frequency regimes for their existence have been worked out. Through the graphical analysis of the soliton solutions, the propagation features of optical pulses and their interaction behaviours in NIMs are investigated.

Loomba, Shally; Senthil Mani Rajan, Murugan; Gupta, Rama; Mahalingam, Arumugam

2014-05-01

8

Antisymmetric PT-photonic structures with balanced positive- and negative-index materials  

NASA Astrophysics Data System (ADS)

We propose a class of synthetic optical materials in which the refractive index satisfies n(-x)=-n*(x). We term such systems antisymmetric parity-time (APT) structures. Unlike PT-symmetric systems, which require balanced gain and loss, i.e., n(-x)=n*(x), APT systems consist of balanced positive- and negative-index materials. Despite the seemingly PT-symmetric optical potential V(x)?n(x)2?2/c2, APT systems are not invariant under combined PT operations due to the discontinuity of the spatial derivative of the wave function. We show that APT systems can display intriguing properties, such as spontaneous phase transition of the scattering matrix, a flat total transmission band, and a continuous lasing spectrum.

Ge, Li; Türeci, Hakan E.

2013-11-01

9

Role of the anomalous self-steepening effect in modulation instability in negative-index material.  

PubMed

In negative-index materials (NIMs), the self-steepening (SS) effect is proven to be anomalous in two aspects: First, it can be either positive or negative, with the zero SS point determined by the size of split-ring resonator circuit elements. Second, the negative SS parameter can have a very large value compared to an ordinary positive-index material. We present a theoretical investigation on modulation instability (MI) to identify the role of the anomalous SS effect in NIM. We find that the first anomaly of SS doesn't influence MI, yet the controllable zero SS point can be used to manipulate MI, and thus manipulate the generation of solitons. The second anomaly, however, leads to significant changes in the MI condition and property, compared with the case of an ordinary positive-index material. Numerical simulations confirm the theoretical results and show that negative SS moves the center of generated pulse toward the leading side, and shifts a part of energy of the generated pulse toward the red side, opposite to the case of positive SS. PMID:19503483

Wen, Shuangchun; Xiang, Yuanjiang; Su, Wenhua; Hu, Yonghua; Fu, Xiquan; Fan, Dianyuan

2006-02-20

10

Modulational instability of coupled nonlinear field equations for pulse propagation in a negative index material embedded into a Kerr medium  

Microsoft Academic Search

We have investigated the modulational instability (MI) in a negative index\\u000amedia (NIM) using a new generalized model describing the pulse propagation in a\\u000anegative index material embedded into a Kerr medium. We have found that one\\u000acould control the gain of MI in a NIM by tuning the initial electric or\\u000amagnetic field amplitudes . Our model successfully recovers

Amarendra K. Sarma; Manirupa Saha

2010-01-01

11

Negative-Index Metamaterials: Going Optical  

Microsoft Academic Search

The race toward engineering metamaterials comprising of negative refractive indexes in the optical range started with the realization of negative-index materials for gigahertz frequencies six years ago. Sheer miniaturization of the gigahertz resonant structures is one approach. Alternative designs make use of localized plasmon resonant metal nanoparticles or nanoholes in metal films. Following this approach, a negative refractive index has

Thomas A. Klar; Alexander V. Kildishev; Vladimir P. Drachev; Vladimir M. Shalaev

2006-01-01

12

Superconducting artificial materials with a negative permittivity, a negative permeability, or a negative index of refraction  

NASA Astrophysics Data System (ADS)

Artificial materials are media made of inclusions such that the sizes and spacing of the inclusions is much smaller than the incident electromagnetic radiation. This allows a medium to act as an effective bulk medium to electromagnetic radiation. Artificial materials can be tailored to produce desired values of the permittivity, permeability, and index of refraction at specific frequencies. The applications of this tailoring include electromagnetic cloaking, and, theoretically, subwavelength imaging resolution. However, the success of these applications depends on their sensitivity to loss. This research uses superconducting niobium (Nb) metals to create arrays of wires, split-ring resonators, and a combination of wires and split-ring resonators, with very low loss. These arrays are used to investigate properties of a medium with an index of refraction that contains a bandwidth of frequency where the real part is negative. The Nb wire arrays produce a frequency bandwidth with a negative real part of the permittivity, while the Nb split-ring resonators produce a frequency bandwidth with a negative real part of the permeability. The combination of Nb wires and Nb split-ring resonators creates an artificial medium with a negative real part of the index of refraction. The electromagnetic transmission of the wires, split-ring resonators, and combination medium is measured in a waveguide as a function of frequency, and models of the permittivity and permeability are used to fit this data. For a single Nb split-ring resonator, the change in the resonant frequency and quality factor with temperature is measured and fit with a two-fluid model of superconductivity. The change in the resonant frequency and quality factor with an applied dc H field and applied power is also measured and compared to, respectively, magneto-optical imaging and laser scanning photoresponse measurements. Bianisotropy and perturbations in the resonant frequency are investigated, and simulated with commercial electromagnetic modeling software. The electromagnetic transmission of a single Nb split-ring resonator is compared to resonators made of YBa2Cu3O7-delta, Copper, and a Nb closed-ring resonator. Similar measurements are made with the single resonators embedded in a metallic wire array.

Ricci, Michael Christopher

13

Polarization- and direction-independent defect modes in a wide incident-angle range within Bragg gaps by photonic heterostructures containing negative-index materials  

NASA Astrophysics Data System (ADS)

We propose a type of photonic heterostructure by combining dielectric one-dimensional (1D) defective photonic crystals (PCs) and magnetic 1D defective PCs. Both of the two PCs consist of alternating positive-index-material (PIM) layers with a negative-index-material (NIM) defect layer. It is demonstrated by transfer matrix method that there is a polarization- and direction-independent defect mode in a wide incident-angle range within Bragg gaps in the heterostructure. The field distributions prove that the dielectric 1D defective PC benefits to achieve the approximately omnidirectional defect mode for TE waves while the magnetic 1D defective PC benefits for TM waves. Such a structure is useful for designing polarization-independent and omnidirectional or large incident angle narrow-passband filters in optical devices.

Lin, M.; Xu, J.; Fang, Y.; Qiu, G.; Ouyang, Z.

2010-03-01

14

Optical negative-index metamaterials  

Microsoft Academic Search

Artificially engineered metamaterials are now demonstrating unprecedented electromagnetic properties that cannot be obtained with naturally occurring materials. In particular, they provide a route to creating materials that possess a negative refractive index and offer exciting new prospects for manipulating light. This review describes the recent progress made in creating nanostructured metamaterials with a negative index at optical wavelengths, and discusses

Vladimir M. Shalaev

2006-01-01

15

Enlargement of the omnidirectional reflectance gap in one-dimensional photonic crystal heterostructure containing double negative index material  

NASA Astrophysics Data System (ADS)

In this paper, we investigate by theoretical analysis a way to enlarge the frequency range of band gap in one-dimensional heterostructure photonic crystal (PC) made of two PCs alternate stacked by conventional and double negative index material. The numerical results by scattering matrix method (SMM) show that, for the proposed PC with appropriate parameters, there is an omnidirectional photonic band gap (OBG), which is insensitive to incident angle and polarization. The thickness ratio of layers in the second PC is the inverse and identical of that in the first PC, respectively. Two PCs form the PC heterostructures. Moreover, we demonstrate the existence of OBG and notable enlargement of the frequency range of the OBG in proposed PC heterostructure. The reason is that the pass band of one of the two PCs falls into the forbidden band of another PC. Decreasing the thickness of layers but not changing the thickness ratio of layers in the second PC, the frequency range of OBG keeps invariant. However, with the increasing of thickness of layers, the frequency range of OBG gets narrow.

Feng, Xi; Li, Hu

2013-11-01

16

Negative index lens aberrations  

NASA Astrophysics Data System (ADS)

We examine the Seidel aberrations of thin spherical lenses composed of media with refractive index not restricted to be positive. We find that consideration of this expanded parameter space allows for the reduction or elimination of more aberrations than is possible with only positive index media. In particular, we find that spherical lenses possessing real aplanatic focal points are possible only with a negative index. We perform ray tracing, using a custom code that relies only on Maxwell’s equations and conservation of energy, that confirms the results of the aberration calculations. This research was supported by DARPA (Contract No. MDA972-01-2- 0016) and a Multiple University Research Initiative (MURI), sponsored by ONR (Contract No. N00014-01-1-0803).

Schurig, David

2005-03-01

17

Negative index metamaterial combining magnetic resonators with metal films  

Microsoft Academic Search

We present simulation results of a design for negative index materials that\\u000auses magnetic resonators to provide negative permeability and metal film for\\u000anegative permittivity. We also discuss the possibility of using semicontinuous\\u000ametal films to achieve better manufacturability and enhanced impedance\\u000amatching.

Uday K. Chettiar; Alexander V. Kildishev; Thomas A. Klar; Vladimir M. Shalaev

2006-01-01

18

Cover Picture: Rapid Research Letter - Focusing slabs made of negative index materials based on inhomogeneous dielectric rods  

NASA Astrophysics Data System (ADS)

In the Rapid Research Letter [1] it is shown that a flat array of dielectric rods can act as a focusing lens of good quality - provided the rods have specified gradients of the dielectric constant. This design is superior to conventional photonic crystals (PC) utilizing homogeneous rods since the lens can be smaller and has better properties in a broader wavelength range.The cover picture is an artist's view of the PC lens made from dielectric rods consisting of three layers with the refractive index increasing from the margin to the center of the rod, focusing a light beam into a small spot. The focusing spot is controlled by the parameters of the rods and their arrangement in the PC slab.The first author, Dr. Vladimir Sergentu, is a senior researcher of the Laboratory of Low Dimensional Semiconductor Structures in Chisinau, Moldova, which works on the design of PC based optical elements in collaboration with the Universities of Kiel and Rochester.

Sergentu, V. V.; Ursaki, V. V.; Tiginyanu, I. M.; Foca, E.; Föll, H.; Boyd, Robert W.

2006-05-01

19

Robust wedge demonstration to optical negative index metamaterials  

NASA Astrophysics Data System (ADS)

A robust wedge setup is proposed to unambiguously demonstrate negative refraction for negative index metamaterials. We applied our setup to several optical metamaterials from the literature and distinctly observed the phenomena of negative refraction. This further consolidates the reported negative-index property. It is found that there generally exists a lateral shift for the outgoing beam through the wedge. We derived a simple expression for calculating this beam shift and interestingly, it provides us a strategy to quantitatively estimate the loss of the wedge material (Im[n]). Additionally, we offered a design of metamaterials, compatible with nano-imprinting-lithography, showing negative refractive index in the visible regime (around yellow-light wavelengths). The multi-layer-system retrieval was utilized to extract the effective refractive index of the metamaterial. It was also intuitively characterized through our wedge setup to demonstrate corresponding phenomena of refraction.

Shen, Nian-Hai; Koschny, Thomas; Kafesaki, Maria; Soukoulis, Costas M.

2013-06-01

20

"Perfect lens" Imaging by Negative Index Media  

NASA Astrophysics Data System (ADS)

We study analytically and numerically imaging by Â"perfect lensÂ" made of negative index medium (NIM) (or left-handed meta-material (LHM)). For far field, the perfect lens is only perfect for n=-1. Away from this value, aberration and caustics will be present. For near field imaging with Re ?=-1, the consequences of departure from dielectric matching and losses are discussed. Work supported by NSF-0098801 and AFRL, Hanscom.

Lu, W. T.; Sokoloff, J. B.; Sridhar, S.

2003-03-01

21

Photorealistic rendering of a graded negative-index metamaterial magnifier  

NASA Astrophysics Data System (ADS)

A novel reverse design schematic for designing a metamaterial magnifier with graded negative refractive index for both the two-dimensional and three-dimensional cases has been proposed. Photorealistic rendering is integrated with trace ray trajectories in example designs to visualize the scattering magnification as well as imaging of the proposed graded-index magnifier with negative-index metamaterials. The material of the magnifying shell can be uniquely and independently determined without knowing beforehand the corresponding domain deformation. This reverse recipe and photorealistic rendering directly tackles the significance of all possible parametric profiles and demonstrates the performance of the device in a realistic scene, which provides a scheme to design, select and evaluate a metamaterial magnifier.

Qiu, Cheng-Wei; Akbarzadeh, Alireza; Han, Tiancheng; Danner, Aaron J.

2012-03-01

22

Structures with negative index of refraction  

DOEpatents

The invention provides simplified negative index materials (NIMs) using wire-pair structures, 4-gap single ring split-ring resonator (SRR), fishnet structures and overleaf capacitor SRR. In the wire-pair arrangement, a pair of short parallel wires and continuous wires are used. In the 4-gap single-ring SRR, the SRRs are centered on the faces of a cubic unit cell combined with a continuous wire type resonator. Combining both elements creates a frequency band where the metamaterial is transparent with simultaneously negative .di-elect cons. and .mu.. In the fishnet structure, a metallic mesh on both sides of the dielectric spacer is used. The overleaf capacitor SRR changes the gap capacities to small plate capacitors by making the sections of the SRR ring overlap at the gaps separated by a thin dielectric film. This technique is applicable to conventional SRR gaps but it best deploys for the 4-gap single-ring structures.

Soukoulis, Costas M. (Ames, IA); Zhou, Jiangfeng (Ames, IA); Koschny, Thomas (Ames, IA); Zhang, Lei (Ames, IA); Tuttle, Gary (Ames, IA)

2011-11-08

23

Nanoimprinting techniques for large-area three-dimensional negative index metamaterials with operation in the visible and telecom bands.  

PubMed

We report advances in materials, designs, and fabrication schemes for large-area negative index metamaterials (NIMs) in multilayer "fishnet" layouts that offer negative index behavior at wavelengths into the visible regime. A simple nanoimprinting scheme capable of implementation using standard, widely available tools followed by a subtractive, physical liftoff step provides an enabling route for the fabrication. Computational analysis of reflection and transmission measurements suggests that the resulting structures offer negative index of refraction that spans both the visible wavelength range (529-720 nm) and the telecommunication band (1.35-1.6 ?m). The data reveal that these large (>75 cm(2)) imprinted NIMs have predictable behaviors, good spatial uniformity in properties, and figures of merit as high as 4.3 in the visible range. PMID:24730614

Gao, Li; Shigeta, Kazuki; Vazquez-Guardado, Abraham; Progler, Christopher J; Bogart, Gregory R; Rogers, John A; Chanda, Debashis

2014-06-24

24

Low-loss negative-index metamaterial at telecommunication wavelengths  

Microsoft Academic Search

We fabricate and characterize a low-loss silver-based negative-index metamaterial based on the design of a recent theoretical proposal. Comparing the measured transmittance and reflectance spectra with theory reveals good agreement. We retrieve a real part of the refractive index of Re(n)=-2 around 1.5 mum wavelength. The maximum of the ratio of the real to the imaginary part of the refractive

Gunnar Dolling; Christian Enkrich; Martin Wegener; Costas M. Soukoulis; Stefan Linden

2006-01-01

25

Effect of an optical negative index thin film on optical bistability.  

PubMed

We investigate nonlinear transmission in a layered structure consisting of a slab of positive index material with Kerr-type nonlinearity and a subwavelength layer of linear negative index material (NIM) sandwiched between semi-infinite linear dielectrics. We find that a thin layer of NIM leads to significant changes in the hysteresis width when the nonlinear slab is illuminated at an angle near that of total internal reflection. Unidirectional diodelike transmission with enhanced operational range is demonstrated. These results may be useful for NIMs characterization and for designing novel NIMs-based devices. PMID:17186047

Litchinitser, N M; Gabitov, I R; Maimistov, A I; Shalaev, V M

2007-01-15

26

Gap solitons in a nonlinear quadratic negative-index cavity.  

PubMed

We predict the existence of gap solitons in a nonlinear, quadratic Fabry-Pérot negative index cavity. A peculiarity of a single negative index layer is that if magnetic and electric plasma frequencies are different it forms a photonic band structure similar to that of a multilayer stack composed of ordinary, positive index materials. This similarity also results in comparable field localization and enhancement properties that under appropriate conditions may be used to either dynamically shift the band edge, or for efficient energy conversion. We thus report that an intense, fundamental pump pulse is able to shift the band edge of a negative index cavity, and make it possible for a weak second harmonic pulse initially tuned inside the gap to be transmitted, giving rise to a gap soliton. The process is due to cascading, a well-known phenomenon that occurs far from phase matching conditions that limits energy conversion rates, it resembles a nonlinear third-order process, and causes pulse compression due to self-phase modulation. The symmetry of the equations of motion under the action of either an electric or a magnetic nonlinearity suggests that both nonlinear polarization and magnetization, or a combination of both, can lead to solitonlike pulses. More specifically, the antisymmetric localization properties of the electric and magnetic fields cause a nonlinear polarization to generate a dark soliton, while a nonlinear magnetization spawns a bright soliton. PMID:17677375

Scalora, Michael; de Ceglia, Domenico; D'Aguanno, Giuseppe; Mattiucci, Nadia; Akozbek, Neset; Centini, Marco; Bloemer, Mark J

2007-06-01

27

Interferometric characterization of a sub-wavelength near-infrared negative index metamaterial.  

PubMed

Negative phase advance through a single layer of near-IR negative index metamaterial (NIM) is identified through interferometric measurements. The NIM unit cell, sub-wavelength in both the lateral and light propagation directions, is comprised of a pair of Au strips separated by two dielectric and one Au film. Numerical simulations show that the negative phase advance through the single-layer sample is consistent with the negative index exhibited by a bulk material comprised of multiple layers of the same structure. We also numerically demonstrate that the negative index band persists in the lossless limit. PMID:20721166

Zhang, Xuhuai; Davanço, Marcelo; Maller, Kara; Jarvis, Thomas W; Wu, Chihhui; Fietz, Chris; Korobkin, Dmitriy; Li, Xiaoqin; Shvets, Gennady; Forrest, Stephen R

2010-08-16

28

A single-layer wide-angle negative-index metamaterial at visible freque  

SciTech Connect

Metamaterials are materials with artificial electromagnetic properties defined by their sub-wavelength structure rather than their chemical composition. Negative-index materials (NIMs) are a special class of metamaterials characterized by an effective negative index that gives rise to such unusual wave behaviour as backwards phase propagation and negative refraction. These extraordinary properties lead to many interesting functions such as sub-diffraction imaging1, 2 and invisibility cloaking3, 4, 5, 6. So far, NIMs have been realized through layering of resonant structures, such as split-ring resonators, and have been demonstrated at microwave7, 8 to infrared9, 10, 11, 12, 13 frequencies over a narrow range of angles-of-incidence and polarization. However, resonant-element NIM designs suffer from the limitations of not being scalable to operate at visible frequencies because of intrinsic fabrication limitations14, require multiple functional layers to achieve strong scattering13, 14 and have refractive indices that are highly dependent on angle of incidence and polarization. Here we report a metamaterial composed of a single layer of coupled plasmonic coaxial waveguides that exhibits an effective refractive index of ?2 in the blue spectral region with a figure-of-merit larger than 8. The resulting NIM refractive index is insensitive to both polarization and angle-of-incidence over a ±50° angular range, yielding a wide-angle NIM at visible frequencies.

Burgos, Stanley P.; de Waele, Rene; Polman, Albert; Atwater, Harry A.

2010-01-01

29

Globally enhanced chiral field generation by negative-index metamaterials  

NASA Astrophysics Data System (ADS)

We show that negative-index metamaterials can generate chiral electromagnetic fields, which can be used to enhance molecular chiroptical signals by inducing strong local magnetic fields. Compared to circularly polarized light (CPL), the enhanced chiral field generated by a double-fishnet negative-index metamaterial shows a 3.5-fold enhancement of the volume-averaged optical chirality and possesses the same handedness as that of incident CPL, thereby forming a globally enhanced chiral field. By analyzing near-field configurations, the mechanism of the optical chirality enhancement by double-fishnet negative-index metamaterial is elucidated. We thus anticipate that these metamaterials have potential applications in chiroptical spectroscopy.

Yoo, SeokJae; Cho, Minhaeng; Park, Q.-Han

2014-04-01

30

Microwave Propagation in Negative Index and Artificial Dielectric Media  

NASA Astrophysics Data System (ADS)

Negative index media (NIM) are fabricated by interleaving arrays of split ring resonators and wire strips. Microwave (X-band) waveguide measurements on the NIM yield quantitative information on the material parameters, % tilden(?)=n^' +in^' ', tilde\\varepsilon% (? )=\\varepsilon ^' +i\\varepsilon ^' ' and tilde% ?(? )=? ^' +i? ^' ' . Typical NIM features such as passband in the NIM region expected from the theoretical analysis are observed in the measured data. The n^'(?) determined from the waveguide transmission parameters (tildeS_11,tildeS_21) is found to vary from -4.8 to-0.3 in the passband region 9.6-10.5GHz. The results show that transmission is optimized for n^' (? ) -1 and low n^' ' . A detailed investigation of several NIM materials suggests that the characteristic properties of the NIM are dependent on the length of the material, choice of the substrate material, and continuity in the wire strips. Artificial dielectric media fabricated with arrays of wire strips exhibit a characteristic microwave plasmon mode in the X-band region, below which \\varepsilon ^' (? )<0. Work supported by the National Science Foundation and the Air Force Research Labs, Hanscom.

Parimi, Patanjali; Vodo, Plarenta; Lu, Wentao; Sridhar, Srinivas

2003-03-01

31

Bianisotropic Negative-Index Metamaterial Embedded in a Symmetric Medium.  

National Technical Information Service (NTIS)

In order to more clearly observe the bianisotropic effects due to fabrication-induced structural asymmetries in negative-index metamaterials based on a fishnet structure, it is necessary to measure the optical properties with symmetric substrate and super...

K. M. Dani P. C. Upadhya S. R. Brueck Z. Ku

2009-01-01

32

Sub-picosecond optical switching with a negative index metamaterial  

SciTech Connect

Development of all-optical signal processing, eliminating the performance and cost penalties of optical-electrical-optical conversion, is important for continu,ing advances in Terabits/sec (Tb/s) communications.' Optical nonlinearities are generally weak, traditionally requiring long-path, large-area devicesl,2 or very high-Q, narrow-band resonator structures.3 Optical metamaterials offer unique capabilities for optical-optical interactions. Here we report 600 femtosecond (fs) all-optical modulation using a fIShnet (2D-perforated metallamorphous-Si (a-Si)/metal film stack) negative-index meta material with a structurally tunable broad-band response near 1.2 {micro}m. Over 20% modulation (experimentally limited) is achieved in a path length of only 116 nm by photo-excitation of carriers in the a-Si layer. This has the potential for Tb/s aU-optical communication and will lead to other novel, compact, tunable sub-picosecond (ps) photonic devices.

Dani, Keshav M [Los Alamos National Laboratory; Upadhya, Prashant C [Los Alamos National Laboratory; Zahyum, Ku [CHTM-UNM

2009-01-01

33

Negative Index Metamaterials at Optical Frequencies: Theory and Experiment  

NASA Astrophysics Data System (ADS)

Pafomov and Veselago showed in 1950-60s that negative refraction should occur in homogeneous media with simultaneously negative dielectric permittivity and magnetic permeability, ?<0, ?<0. Pendry (2000) speculated that the ideal Veselago lens can produce sub- wavelength resolution. We find a strong effect of surfaces on resolution limit and nontrivial relation of subwavelength imaging to EM ``softness'' of the lens [1]. We have designed the metamaterial by means of FDTD modeling, which is a stack of metallic films with periodic hole arrays separated by dielectric layers (called ``fishnet'', FN) to work at IR wavelengths ?=1.5- 1.6 ?m. The FN samples have been fabricated by nanoimprint lithography[2]. The transmission and reflectance characteristics of the samples have been measured by laser spectroscopic ellipsometry and showed unambiguously that the FN supports the ``backward'' waves and have overall negative index of refraction at IR frequencies. We also show that single layers of FN structure have positive index. We also address the questions of countering losses by using gain medium, limits sub-wavelength resolution, and focusing. 1. A.M. Bratkovsky, A.Cano, and A.P. Levanyuk, Appl. Phys. Lett. 87, 103507 (2005). 2. W. Wu et al., cond-mat/0610352.

Ponizovskaya, E.; Bratkovsky, A. M.

2007-03-01

34

Symmetry breaking and optical negative index of closed nanorings  

NASA Astrophysics Data System (ADS)

Metamaterials have extraordinary abilities, such as imaging beyond the diffraction limit and invisibility. Many metamaterials are based on split-ring structures, however, like atomic orbital currents, it has long been believed that closed rings cannot produce negative refractive index. Here we report a low-loss and polarization-independent negative-index metamaterial made solely of closed metallic nanorings. Using symmetry breaking that negatively couples the discrete nanorings, we measured negative phase delay in our composite ‘chess metamaterial’. The formation of an ultra-broad Fano-resonance-induced optical negative-index band, spanning wavelengths from 1.3 to 2.3??m, is experimentally observed in this structure. This discrete and mono-particle negative-index approach opens exciting avenues towards symmetry-controlled topological nanophotonics with on-demand linear and nonlinear responses.

Kanté, Boubacar; Park, Yong-Shik; O'Brien, Kevin; Shuldman, Daniel; Lanzillotti-Kimura, Norberto D.; Jing Wong, Zi; Yin, Xiaobo; Zhang, Xiang

2012-11-01

35

Symmetry breaking and optical negative index of closed nanorings.  

PubMed

Metamaterials have extraordinary abilities, such as imaging beyond the diffraction limit and invisibility. Many metamaterials are based on split-ring structures, however, like atomic orbital currents, it has long been believed that closed rings cannot produce negative refractive index. Here we report a low-loss and polarization-independent negative-index metamaterial made solely of closed metallic nanorings. Using symmetry breaking that negatively couples the discrete nanorings, we measured negative phase delay in our composite 'chess metamaterial'. The formation of an ultra-broad Fano-resonance-induced optical negative-index band, spanning wavelengths from 1.3 to 2.3??m, is experimentally observed in this structure. This discrete and mono-particle negative-index approach opens exciting avenues towards symmetry-controlled topological nanophotonics with on-demand linear and nonlinear responses. PMID:23149726

Kanté, Boubacar; Park, Yong-Shik; O'Brien, Kevin; Shuldman, Daniel; Lanzillotti-Kimura, Norberto D; Jing Wong, Zi; Yin, Xiaobo; Zhang, Xiang

2012-01-01

36

Symmetry Breaking and Optical Negative Index of Closed Nanorings  

NASA Astrophysics Data System (ADS)

We report the first experimental demonstration of broadband negative-index metamaterial made solely of closed metallic nanorings. Using symmetry breaking that negatively couples the discrete nanorings, we measured negative phase delay in our composite chess metamaterial. Our approach open avenues towards topological nanophotonics with on demand linear and non-linear responses.

Kante, Boubacar; Park, Yong-Shik; O'Brien, Kevin; Shuldman, Daniel; Lanzillotti-Kimura, Norberto Daniel; Wong, Zi Jing; Yin, Xiaobo; Zhang, Xiang

2013-03-01

37

Reverse optical forces in negative index dielectric waveguide arrays.  

PubMed

Nonconservative optical forces acting on dipolar particles are considered in longitudinally invariant optical fields. We demonstrate that the orientation of these forces is strictly dictated by the propagation vector associated with such field configurations. As a direct consequence of this, it is impossible to achieve a reversal of optical forces in homogeneous media. We show instead that translation invariant optical tractor fields can in fact be generated in the negative index environment produced in a special class of fully dielectric waveguide arrays. PMID:21847174

Salandrino, Alessandro; Christodoulides, Demetrios N

2011-08-15

38

A power combiner and multisource co-beam reflector based on virtual shifting of the sources using negative index media  

NASA Astrophysics Data System (ADS)

Recent study has shown that an image of an object can be focused with a negative index material without a conventional lens. Based on this, we propose a scheme in which a given microwave source can be shifted a virtual distance by using a properly designed perfect lens. Two typical systems are studied in detail. One is a power combiner, by which several distributed sources can be combined as a single source at a required location. When the sources have the same initial phase, the system will perform as a perfect power combiner. The second is a multisource co-beam reflector, in which the offset sources generate beams that propagate back along the axis of the reflector; this has not been satisfactorily solved by any traditional methods.

Luo, Yang; Zhu, Shou-Zheng

2012-10-01

39

Intra-connected three-dimensionally isotropic bulk negative index photonic metamaterial  

SciTech Connect

Isotropic negative index metamaterials (NIMs) are highly desired, particularly for the realization of ultra-high resolution lenses. However, existing isotropic NIMs function only two-dimensionally and cannot be miniaturized beyond microwaves. Direct laser writing processes can be a paradigm shift toward the fabrication of three-dimensionally (3D) isotropic bulk optical metamaterials, but only at the expense of an additional design constraint, namely connectivity. Here, we demonstrate with a proof-of-principle design that the requirement connectivity does not preclude fully isotropic left-handed behavior. This is an important step towards the realization of bulk 3D isotropic NIMs at optical wavelengths.

Guney, Durdu; Koschny, Thomas; Soukoulis, Costas

2010-05-26

40

Designing Printed Instructional Materials.  

ERIC Educational Resources Information Center

Discusses the importance of identifying the audience and determining specific objectives when designing printed instructional materials that will communicate effectively and provides detailed guidelines for dealing with such design factors as content, writing style, typography, illustrations, and page organization. (MBR)

Burbank, Lucille; Pett, Dennis

1986-01-01

41

Metallo-dielectric core-shell nanospheres as building blocks for optical three-dimensional isotropic negative-index metamaterials  

NASA Astrophysics Data System (ADS)

Materials showing electromagnetic properties that are not attainable in naturally occurring media, so-called metamaterials, have been lately, and still are, among the most active topics in optical and materials physics and engineering. Among these properties, one of the most attractive ones is the sub-diffraction resolving capability predicted for media having an index of refraction of -1. Here, we propose a fully three-dimensional, isotropic metamaterial with strong electric and magnetic responses in the optical regime, based on spherical metallo-dielectric core-shell nanospheres. The magnetic response stems from the lowest, magnetic-dipole resonance of the dielectric shell with a high refractive index, and can be tuned to coincide with the plasmon resonance of the metal core, responsible for the electric response. Since the response does not originate from coupling between structures, no particular periodic arrangement needs to be imposed. Moreover, due to the geometry of the constituents, the metamaterial is intrinsically isotropic and polarization independent. It could be realized with current fabrication techniques with materials such as silver (core) and silicon or germanium (shell). For these particular realistic designs, the metamaterials present a negative index in the range of 1.2-1.55 ?m.

Paniagua-Domínguez, R.; López-Tejeira, F.; Marqués, R.; Sánchez-Gil, J. A.

2011-12-01

42

Optical waves in a gradient negative-index lens of a half-infinite length  

NASA Astrophysics Data System (ADS)

Materials with negative permittivity and permeability can overcome the diffraction limit, thereby making the sub-wavelength imaging possible. In this study, we analyze the effects of gradient index on a half-infinite perfect lens. We assume that the sharp interface between the vacuum and the negative-index material is replaced by a smooth transition profile such that the index gradually changing from positive to negative. Interestingly, we find that if the graded index profile is modeled by a tanh function, we can have closed-form analytical solutions for this problem, which is a distinct advantage as numerical solutions are not accurate for evanescent waves with large transverse wave vectors. By analyzing the analytical formulas we confirm that a nonzero total absorption can occur even for a near-zero absorption coefficient in the steady-state limit and the image plane contains multiple sub-wavelength images of an object.

Ding, Yi S.; Chan, C. T.; Wang, R. P.

2013-10-01

43

Experimental Verification of a Negative Index of Refraction  

Microsoft Academic Search

We present experimental scattering data at microwave frequencies on a structured metamaterial that exhibits a frequency band where the effective index of refraction (n) is negative. The material consists of a two-dimensional array of repeated unit cells of copper strips and split ring resonators on interlocking strips of standard circuit board material. By measuring the scattering angle of the transmitted

R. A. Shelby; D. R. Smith; S. Schultz

2001-01-01

44

Three-Dimensional Approaches to Assembling Negative Index Metamedia.  

National Technical Information Service (NTIS)

This report describes progress accomplished in the past 5 years in the areas of (i) the design of plasmonic near-field plates for visible operation and corrugated near-field plates for point focusing; (ii) synthesis of gold nanoparticle patterns; (iii) pe...

R. D. Merlin

2012-01-01

45

Demonstration of metal-dielectric negative-index metamaterials with improved performance at optical frequencies  

Microsoft Academic Search

We experimentally demonstrate a comparatively low-loss negative-index metamaterial with the magnitude of the real part of the index comparable with the imaginary part. Over 40% transmission is achieved in the negative-index region by structural adjustment of the impedance matching between the metamaterial and the air-substrate claddings. This structure has the potential of achieving high transmission and small loss in the

Shuang Zhang; Wenjun Fan; Kevin J. Malloy; Steven R. J. Brueck; Nicolae C. Panoiu; Richard M. Osgood

2006-01-01

46

Designer quantum materials  

NASA Astrophysics Data System (ADS)

Spin-based quantum information processing relies on the ability to identify and coherently manipulate quantum bits (qubits) existing in nature in the form of spin-½ particles such as electrons. The work described in this thesis is based on an alternative perspective: that these spin-½ objects, together with their interactions, can be regarded as building blocks of a variety of "designer quantum materials" with features not present for isolated single spins. Theoretical proposals are presented for two classes of spin-based designer quantum materials relevant for quantum information transport and manipulation. The first class of materials involves spin-½ networks coupled by spatially-varying exchange interactions, in which moving domain walls can produce topologically-stable "flying spin qubits," and pairs of domain walls can be used to generate and transport Einstein-Podolsky-Rosen pairs of entangled qubits. The effective exchange between two domain-wall qubits can be tuned by adjusting the positions of the domain walls and can be ferromagnetic even when all spin-spin couplings are antiferromagnetic. The second class of designer quantum materials consists of electron spins in quantum wires with spatially-varying spin-orbit coupling. The presence of the spin-orbit interaction introduces pseudo-Zeeman couplings of the electron spins to effective magnetic fields and further enhances the building-block toolset: by periodically modulating this spin-orbit coupling in space, it is possible to create the spatial analogue of spin resonance, without the need for any real magnetic fields. The mapping of time-dependent operations onto a spatial axis suggests a new mode for quantum information processing in which gate operations are encoded into the band structure of the material.

Srinivasa, Vanita

47

Extended slow-light field enhancement in positive-index/negative-index heterostructures  

NASA Astrophysics Data System (ADS)

We present a biwaveguide paradigm composed of joined positive-index-material (PIM)/negative-index-material (NIM) slabs, demonstrating ultraslow-light propagation stemming from the competing propagation disposition in the PIM and NIM regions. We report for the first time a mesoscopic extended electromagnetic (EM) enhancement covering regions of the order of the free-space wavelength, enabled by the slow-light mode in our system. Our dynamic numerical results are consistent with our developed theoretical model, predicting an EM energy accumulation reminiscent of a charging capacitor. Our analysis reveals that spatial compression is not a requirement for EM enhancement in slow-light systems and stresses the merits of a high coupling efficiency, strong temporal compression, monomodality, and modal index bandwidth—all present in our proposed paradigm. Furthermore, we show that the heterostructure waveguide mode is an extraordinary entity with a unique energy velocity, which is opposite to the Poynting vector in one of the participant waveguides. We believe that these results will inspire new slow-light platforms relevant to the collective harvesting of strong light-matter interactions.

Foteinopoulou, S.; Vigneron, J. P.

2013-11-01

48

Negative index fishnet structures with nanopillars formed by nanoimprint lithography  

NASA Astrophysics Data System (ADS)

Since their inception, metamaterial fishnet structures have frequently been used to exhibit a negative refractive index. Their shape and structure make it possible to independently produce both a negative permeability (?) and a negative permittivity (?). Fishnets that display this characteristic can be referred to as a double negative metamaterial. Although other techniques have been demonstrated, fishnets are commonly fabricated using electron-beam lithography (EBL) or focused ion-beam (FIB) milling. In this paper we demonstrate the fabrication of fishnets using nano-imprint lithography (NIL). Advantages associated with NIL include a shorter fabrication time, a larger feasible pattern area and reduced costs. In addition to these advantages, the quality of the fabricated structures is excellent. We imprint a stamp directly into a metal-dielectric-metal stack which creates the fishnet and, as an artifact of the technique, a periodic array of nanopillars. Two different designs of the fishnet and nanopillar structure have been fabricated and optical measurements have been taken from both. In addition to the experimental measurements the structures have also been extensively simulated, suggesting a negative refractive index with a real part as large in magnitude as five can be achieved.

Sharp, Graham J.; Khan, Saima I.; Khokhar, Ali Z.; De La Rue, Richard M.; Johnson, Nigel P.

2014-05-01

49

Multiresolution analysis for material design  

Microsoft Academic Search

The relationship between material microstructure and properties is the key to optimization and design of lightweight, strong, tough materials. Material properties are inherently a function of the microscale interactions at each distinct scale of deformation in a material. Currently, we rely on empirical data to define the structure–property link in the material design chain. A model is proposed here in

Cahal McVeigh; Franck Vernerey; L. Cate Brinson

2006-01-01

50

Negative-index gratings formed by a 193-nm excimer laser  

NASA Astrophysics Data System (ADS)

We have demonstrated fast formation [ \\similar 1500 pulses at \\similar 1( J/cm 2)/pulse ] of fiber gratings with highly negative index modulations ( \\similar -3 \\times 10-4 ) . We have found that the maximum negative index modulations that are achieved do not depend on the pulse intensities, although the inverse of the time taken to reach the negative index-modulation maximum varies linearly with the pulse intensities. This prompts us to use a three-energy-level system to model the photosensitivity in boron-doped germanosilicate fiber. All the necessary parameters of the model can be determined from a single growth measurement of the average index change, and the model's prediction fits well the measured index-modulation growth.

Dong, L.; Liu, W. F.; Reekie, L.

1996-12-01

51

Radar Absorbing Material Design.  

National Technical Information Service (NTIS)

Low observable platforms have extremely low radar cross section specifications that cannot be achieved by shaping alone. The application of radar absorbing material is necessary, in which case the appropriate constitutive parameters and thickness must be ...

C. K. Yuzcelik

2003-01-01

52

Ensembles of plasmonic nanospheres at optical frequencies and a problem of negative index behavior  

Microsoft Academic Search

Arrays of metallic nanoparticles support individual and collective plasmonic excitations that contribute to unusual phenomena\\u000a like surface-enhanced Raman scattering, anomalous transparency, negative index, and subwavelength resolution in various metamaterials.\\u000a We examined the electromagnetic response of dual Kron’s lattice and films containing up to three monolayers of metallic nanospheres.\\u000a It appears that open cubic Kron’s lattice exhibits ‘soft’ electromagnetic response but

E. V. Ponizovskaya; A. M. Bratkovsky

2007-01-01

53

Optimizing low loss negative index metamaterial for visible spectrum using differential evolution: comment.  

PubMed

In a recent paper, Zhao et al. [Opt. Express 19(12), 11605 (2011)], proposed the use of differential evolution technique to optimize figure of merit of a negative index metamaterial (NIM) for the visible spectrum. In this comment, we argue that certain ambiguities associated with the effective parameter retrieval should be also addressed in the paper for the accurate implementation of the technique for NIMs. Furthermore, the figure of merit reported in the paper is unrealistically large. PMID:24663696

Aslam, Muhammad I; Güney, Durdu Ö

2014-02-24

54

Ensembles of plasmonic nanoparticles at optical frequencies for negative index media  

NASA Astrophysics Data System (ADS)

Metamaterials in a form of an array of metallic nanoparticles support collective plasmonic excitations that are believed to be responsible for various unusual phenomena, like surface enhanced Raman scattering (SERS). The array is analogous to a dual structure for a metal film with periodic array of holes, which can provide an extraordinary transmission. We have investigated the electromagnetic response of ordered films of metallic nanoparticles. In particular, we looked at various cubic, close- packed, and columnar structures. This included the nanoparticle realization of G.Eleftheriades' structure that was speculated by N.Engheta et al. to produce negative index medium (NIM). It appears that open- and close-packed arrays behave similarly: there are plasmon resonances and high transmission of certain wavelength that is considerably larger than the separation between the particles, yet no negative index behavior, unlike in e.g. ``fishnet'' metal-dielectric heterostructures that are NIM[1]. We discuss a realization of ``transparent metal'' metamaterial with emphasis on ``channeling'' of radiation in columnar structures. [1] W. Wu et al., cond-mat/0610352, to appear in Appl. Phys. A, Special Issue on Negative Index Metamaterials.

Bratkovsky, A. M.; Ponizovskaya, E.

2007-03-01

55

Deep-subwavelength negative-index waveguiding enabled by coupled conformal surface plasmons.  

PubMed

In this Letter we introduce a novel route for achieving negative-group-velocity waveguiding at deep-subwavelength scales. Our scheme is based on the strong electromagnetic coupling between two conformal surface plasmon structures. Using symmetry arguments and detailed numerical simulations, we show that the coupled system can be geometrically tailored to yield negative-index dispersion. A high degree of subwavelength modal confinement, of ?/10 in the transversal dimensions, is also demonstrated. These results can assist in the development of ultrathin surface circuitry for the low-frequency region (microwave and terahertz regimes) of the electromagnetic spectrum. PMID:24978255

Quesada, R; Martín-Cano, D; García-Vidal, F J; Bravo-Abad, J

2014-05-15

56

Advanced Aerospace Materials by Design  

NASA Technical Reports Server (NTRS)

The advances in the emerging field of nanophase thermal and structural composite materials; materials with embedded sensors and actuators for morphing structures; light-weight composite materials for energy and power storage; and large surface area materials for in-situ resource generation and waste recycling, are expected to :revolutionize the capabilities of virtually every system comprising of future robotic and :human moon and mars exploration missions. A high-performance multiscale simulation platform, including the computational capabilities and resources of Columbia - the new supercomputer, is being developed to discover, validate, and prototype next generation (of such advanced materials. This exhibit will describe the porting and scaling of multiscale 'physics based core computer simulation codes for discovering and designing carbon nanotube-polymer composite materials for light-weight load bearing structural and 'thermal protection applications.

Srivastava, Deepak; Djomehri, Jahed; Wei, Chen-Yu

2004-01-01

57

Materials design - An undergraduate course  

NASA Technical Reports Server (NTRS)

General principles of systems engineering are applied to the design of materials to meet specific performance objectives. Results of ongoing reseach on processing/structure and structure/property relations in ultrahigh-strength steels are used to illustrate the formulation of quantitative microstructural objectives to achieve required property combinations, and the computer thermodynamics-based design of compositions responding to prescribed processing conditions. A class project addresses the conceptual design of a 7-component stainless bearing steel for a critical Space Shuttle application.

Olson, G. B.

1991-01-01

58

Designed materials: what and how  

NASA Astrophysics Data System (ADS)

Quest for a material to suit the service performance is almost as old as human civilization. So far materials engineers have developed a series of alloys, polymers, ceramics, and composites to serve many of the performance requirements in a modern society. However, challenges appear when one needs to satisfy more than one boundary condition. For example, a component with negative Coefficient of Thermal Expansion (CTE) using a ductile metal was almost impossible until recently. Synthesis of various technologies such as Direct Metal Deposition (DMD) Homogenization Design Method (HDM) and mutli material Computer Aided Design (CAD) was necessary to achieve this goal. Rapid fabrication of three-dimensional shapes of engineering materials such as H13 tool steel and nickel super alloys are now possible using Direct Materials Deposition (DMD) technique as well as similar techniques such as Light Engineered New Shaping (LENS) or Directed Light Fabrication (DLF). However, DMD has closed loop capability that enables better dimension and thermal cycle control. This enables one to deposit different material at different pixels with a given height directly from a CAD drawing. The feedback loop also controls the thermal cycle. H13 tool steel is one of the difficult alloys for deposition due to residual stress accumulation from martensitic transformation. However, it is the material of choice for the die and tool industry. DMD has demonstrated successful fabrication of complicated shapes and dies and tools, even with H13 alloys. This process also offers copper chill blocks and water-cooling channels as the integral part of the tool. On the other hand ZrO2 was co-deposited with nickel super alloys using DMD. Flexibility of the process is enormous and essentially it is an enabling technology to marterialize many a design. Using DMD in conjunction with HDM and multi-material CAD, one can produce components with predetermined performance such as negative co-efficient of expansion, by synthesis of designed microstructure. This paper briefly reviews the state of the art of DMD and describes the synthesis of three core technologies to produce designed materials with desired performance.

Mazumder, Jyotirmoy; Dutta, Debasish; Ghosh, Amit K.; Kikuchi, Noboru

2003-03-01

59

Refraction of Electromagnetic Energy for Wave Packets Incident on a Negative Index Medium: Always Negative  

NASA Astrophysics Data System (ADS)

Since all physical radiation sources admit their radiation in the form of wave packets, we analyze refraction of electromagnetic wave packets on passing from an isotropic positive (PIM) to an isotropic negative index medium (NIM). We definitively show that in all cases the energy is always refracted negatively. For localized waves, the group refraction is always negative. We accomplish this by treating comprehensively group refraction at a PIM-NIM interface by analytical and numerical treatment of several exhaustive examples: localized wave packets, beams, and also a finite number of plane waves. We focus on physically important quantities such as the energy flow and momentum. In all of the cases we show that the energy and momentum refract negatively. We show that in all cases where the wave group does not extend to infinity in the perpendicular direction of the wave vector, the interference pattern also refracts negatively. Work supported by NSF-0098801 and AFRL, Hanscom.

Sokoloff, J. B.; Lu, W. T.; Sridhar, S.

2003-03-01

60

Materials Design of Ferromagnetic Diamond  

NASA Astrophysics Data System (ADS)

We propose materials design of ferromagnetic diamond without any transition metal elements based on first principles calculations. The electronic structure and the magnetic properties of impurities-doped diamond are calculated by using the Korringa-Kohn-Rostoker method within the local spin density approximation with taking into account disorder using coherent potential approximation. It is found that H atoms which are doped into tetrahedral interstitial sites show finite local magnetic moments. Moreover, the impurities-doped diamond show ferromagnetism with half-metallic density of states.

Kenmochi, Kazuhide; Sato, Kazunori; Yanase, Akira; Katayama-Yoshida, Hiroshi

2005-02-01

61

NWTS waste package design and materials testing  

Microsoft Academic Search

The package materials test program has progressed naturally from materials screening activities during the conceptual design phase to detailed testing of selected materials during the preliminary design phase. The screening activities have been largely completed and recently reviewed. The program is currently moving into the detailed testing phase. Consistent with current conceptual designs, emphasis in waste form studies is on

J. F. Kircher; D. J. Bradley

1983-01-01

62

ALTERNATE MATERIALS IN DESIGN OF RADIOACTIVE MATERIAL PACKAGES  

Microsoft Academic Search

This paper presents a summary of design and testing of material and composites for use in radioactive material packages. These materials provide thermal protection and provide structural integrity and energy absorption to the package during normal and hypothetical accident condition events as required by Title 10 Part 71 of the Code of Federal Regulations. Testing of packages comprising these materials

P. Blanton; K. Eberl

2010-01-01

63

Design considerations for mirror materials  

Microsoft Academic Search

The key requirements for an optical mirror material include low density, high Young's modulus, low coefficient of thermal expansion, high thermal conductivity, and high diffusivity. Not included among these are fracture toughness and stress corrosion constant, which control slow crack growth and long-term reliability under static or dynamic loads during manufacturing and in-service. The reliability requirement becomes crucial as the

Suresh T. Gulati

1996-01-01

64

A model for instructional design case materials  

Microsoft Academic Search

A conceptual model for focused, fictional instructional design and development case materials is presented in this article. The author suggests that the scarcity of suitable case materials for use in instructional design and development courses may be due to the lack of a suitable model for their construction. After presenting a definition of the case method of instruction and an

David Graf

1991-01-01

65

Integrative materials design: Achievements and opportunities  

NASA Astrophysics Data System (ADS)

The future of sustainable design and manufacturing relies on successful material-process-component integration across all manufacturing sectors. This requires defining, disseminating, and implementing a new design approach and supporting tools and strategies for failure prevention and enhanced performance, reliability, and recyclability. This paper provides an overview of these concepts and their interrelations. A general perspective on design integration is first given, followed by an example of materials-process design integration for fatigue failure prevention, and a prospective view on research opportunities in these areas. The importance of consolidating the integration elements into a platform for the emerging discipline of Integrated Computational Materials Engineering is also discussed.

Lados, Diana A.

2009-02-01

66

Atomistic material design by optimization  

NASA Astrophysics Data System (ADS)

We cast the problem of discovering atomic configurations with desired properties as a constrained global optimization problem. Here the free variables are the location and identity of every atom in a material and the objective function is built from the desired electronic properties. For example, we can minimize the bandgap or we can optimize for a target of combined bandgap and effective mass. We present two evolutionary optimization methods (a genetic algorithm [1] and a scatter search algorithm [2]), and two applications (semiconductor alloys and quantum dots). We describe the application specific mutation and crossover operation necessary, as well as the constraints and how they are maintained during the search of the space of atomic configurations. We highlight past successes, current challenges, and future prospects for this novel method. [1] D. Levine, PGAPack: Parallel Genetic Algorithm Library (1998). [2] M. Laguna and R. Marti, Scatter Search, Methodology and Implementation in C, Kluwer, Boston (2003).

Kim, Kwiseon

2005-03-01

67

Design and Manufacture of Energy Absorbing Materials  

ScienceCinema

Learn about an ordered cellular material that has been designed and manufactured using direct ink writing (DIW), a 3-D printing technology being developed at LLNL. The new material is a patterned cellular material that can absorb mechanical energy-a cushion-while also providing protection against sheering. This material is expected to find utility in application spaces that currently use unordered foams, such as sporting and consumer goods as well as defense and aerospace.

Duoss, Eric

2014-05-30

68

Integrated design of structures, controls, and materials  

NASA Technical Reports Server (NTRS)

In this talk we shall discuss algorithms and CAD tools for the design and analysis of structures for high performance applications using advanced composite materials. An extensive mathematical theory for optimal structural (e.g., shape) design was developed over the past thirty years. Aspects of this theory have been used in the design of components for hypersonic vehicles and thermal diffusion systems based on homogeneous materials. Enhancement of the design methods to include optimization of the microstructure of the component is a significant innovation which can lead to major enhancements in component performance. Our work is focused on the adaptation of existing theories of optimal structural design (e.g., optimal shape design) to treat the design of structures using advanced composite materials (e.g., fiber reinforced, resin matrix materials). In this talk we shall discuss models and algorithms for the design of simple structures from composite materials, focussing on a problem in thermal management. We shall also discuss methods for the integration of active structural controls into the design process.

Blankenship, G. L.

1994-01-01

69

Computationally Designed Molecularly Imprinted Materials  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations were carried out for different molecular systems in order to predict the binding affinities, binding energies, binding distances and the active site groups between the simulated molecular systems and different bio-ligands (theophylline and its derivatives), which have been designed and minimized using molecular simulation techniques. The first simulated molecular systems consisted of a ligand and functional monomer, such as methacrylic acid and its derivatives. For each pair of molecular systems, (10 monomers with a ligand and 10 monomers without a ligand) a total energy difference was calculated in order to estimate the binding energy between a ligand and the corresponding monomers. The analysis of the simulated functional monomers with ligands indicates that the functional group of monomers interacting with ligands tends to be either COOH or CH2=CH. The distances between the ligand and monomer, in the most stable cases as indicated above, are between 2.0-4.5 Å. The second simulated molecular systems consisted of a ligand and a polymer. The polymers were obtained from monomers that were simulated above. And similar to monomer study, for each pair of molecular systems, (polymer with a ligand and polymer without a ligand) a total energy difference was calculated in order to estimate the binding energy between ligand and the corresponding polymer. The binding distance between the active site of a polymer and a ligand will also be discussed.

Pavel, Dumitru; Lagowski, Jolanta; Faid, Karim

2004-03-01

70

Design, discovery and growth of novel materials  

SciTech Connect

This editorial introduces the special issue on design, discovery, and growth of novel materials. The papers of this special issue review and reveal technical details of of how specific growths are developed and implemented.

Canfield, Paul

2012-06-07

71

MATERIAL KNOWLEDGE FOR DESIGN - THE ARCHITECT'S VOCABULARY  

Microsoft Academic Search

This paper investigates how architects select materials during the design process. It argues that not only performance aspects are factored in, but also aspects related to the experience or sensorial stimulation take part in this choice. The argument starts by constructing a hierarchy in the vocabulary that is used to discuss spaces, elements and materials. This hierarchy is derived from

Lisa Wastiels; Ine Wouters; Jonas Lindekens

72

Functionally graded materials: Design, processing and applications  

SciTech Connect

In a Functionally Graded Material (FGM), the composition and structure gradually change over volume, resulting in corresponding changes in the properties of the material. By applying the many possibilities inherent in the FGM concept, it is anticipated that materials will be improved and new functions for them created. A comprehensive description of design, modeling, processing, and evaluation of FGMs as well as their applications is covered in this book. The contents include: lessons from nature; graded microstructures; modeling and design; characterization of properties; processing and fabrication; applications; and summary and outlook.

Miyamoto, Y. [ed.] [Osaka Univ. (JP); Kaysser, W.A.; Rabin, B.H.; Kawasaki, A.; Ford, R.G. [eds.

1999-09-01

73

Optimizing low loss negative index metamaterial for visible spectrum using differential evolution: reply.  

PubMed

We reply to the comment written by Aslam and Güney on our previous paper, Zhao et al. [Opt. Express 19(12), 11605-11614 (2011)]. We maintain that the proposed implementation of the DE algorithm for NIMs optimization in our work is correct, and the mentioned ambiguities in the comment due to the existence of multiple branches for n' in the retrieval procedure have been considered and eliminated by using the proposed robust retrieval method. Furthermore, the FOM of 15.2 for the DE-designed optimal fishnet structure reported in our work is reasonable for ideal fabrication conditions. PMID:24663697

Zhao, Yongxiang; Chen, Fei; Shen, Qiang; Zhang, Lianmeng

2014-02-24

74

Materials And Estimating: Building Design Research Assignment  

NSDL National Science Digital Library

This research assignment asks building design students to research manufacturers and companies that produce kitchen and bath design materials. The assignment is intended to be done throughout an entire semester. Students will compare a traditional product used in kitchen or bath design to a similar "green" or sustainable product. A large component of the project asks the students to research the products and create a resource directory for their future use. This document may be downloaded in Microsoft Word Doc file format.

Wolf, Arlynne

2011-12-05

75

Mimicry of natural material designs and processes  

SciTech Connect

Biological structural materials, although composed of unremarkable substances synthesized at low temperatures, often exhibit superior mechanical properties. In particular, the quality in which nearly all biologically derived materials excel is toughness. The advantageous mechanical properties are attributable to the hierarchical, composite, structural arrangements common to biological systems. Materials scientists and engineers have increasingly recognized that biological designs or processing approaches applied to man-made materials (biomimesis) may offer improvements in performance over conventional designs and fabrication methods. In this survey, the structures and processing routes of marine shells, avian eggshells, wood, bone, and insect cuticle are briefly reviewed, and biomimesis research inspired by these materials is discussed. In addition, this paper describes and summarizes the applications of biomineralization, self-assembly, and templating with proteins to the fabrication of thin ceramic films and nanostructure devices.

Bond, G.M. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States); Richman, R.H. [Daedalus Associates, Inc., Mountain View, CA (United States); McNaughton, W.P. [Cornice Engineering, Durango, CO (United States)

1995-06-01

76

Method of designing layered sound absorbing materials  

NASA Astrophysics Data System (ADS)

A widely used model for describing sound propagation in porous materials is the Johnson-Champoux-Allard model. This rigid frame model is based on five geometrical properties of the porous medium: resistivity, porosity, tortuosity, and viscous and thermal characteristic lengths. Using this model and with the knowledge of such properties for different absorbing materials, the design of a multiple layered system can be optimized efficiently and rapidly. The overall impedance of the layered systems can be calculated by the repeated application of single layer impedance equation. The knowledge of the properties of the materials involved in the layered system and their physical meaning, allows to perform by computer a systematic evaluation of potential layer combinations rather than do it experimentally which is time consuming and always not efficient. The final design of layered materials can then be confirmed by suitable measurements. A method of designing the overall acoustic absorption of multiple layered porous materials is presented. Some aspects based on the material properties, for designing a flat layered absorbing system are considered. Good agreement between measured and computed sound absorption coefficients has been obtained for the studied configurations. [Work supported by N.S.E.R.C. Canada, F.C.A.R. Quebec, and Bombardier Aerospace.

Atalla, Youssef; Panneton, Raymond

2002-11-01

77

Hybrid materials design for SOFC interconnect applications  

NASA Astrophysics Data System (ADS)

Solid oxide fuel cells (SOFCs) offer distinct advantages when compared with alternative energy conversion techniques; however, problems with degradation, particularly interconnect degradation, are currently hindering adoption. One potential solution to minimize interconnect degradation is the use of novel hybrid materials which leverage the composite properties of well characterized, commercially available materials to create a new superior material. A model hybrid material has been developed based on functional laminate construction. A corrosion resistant Ni-200 layer was roll clad onto an inexpensive, low CTE 430 SS Core material. Finally, a conductivity boosting manganese cobalt spinel coating was applied using wet powder spray to the surface. This model material allows us to explore the orthogonal nature of different interconnect functions and their related properties and performance by utilizing our comprehensive screening procedure. Utilizing a factorial design experiment, the effects of simulated SOFC conditions on a model material was investigated through a series of tests. Oxide structure and morphology were investigated using XRD and SEM analysis, respectively, followed by high temperature conductivity testing. Cross sectional composition analysis was performed utilizing AES and optical microscopy evaluated using reflected light optical microscopy. Finally, elevated tensile testing and dilatometry provided mechanical data throughout the temperature range of interest. This broad screening process allows us to elucidate previously unknown connections between materials properties, operational parameters, and system performance. Interconnect resistance was demonstrated to be chiefly a function of surface resistance, more specifically surface chemistry, and operation temperature reductions could cause order of magnitude increases in resistance. Corrosion resistance, as expected, proved to be most closely dependent on laminate composition, although surface chemistry did affect oxidation rate. Surprisingly, thermal expansion was equally a function of laminate composition and surface oxidation rate. Ideally, the conclusions and design recommendations provided by this work will enable a new approach to functional design hybrid material interconnects.

Casteel, Micah

78

Negative index lens aberrations  

Microsoft Academic Search

We examine the Seidel aberrations of thin spherical lenses composed of media with refractive index not restricted to be positive. We find that consideration of this expanded parameter space allows for the reduction or elimination of more aberrations than is possible with only positive index media. In particular, we find that spherical lenses possessing real aplanatic focal points are possible

David Schurig

2005-01-01

79

Nanocomposites—a new material design concept  

Microsoft Academic Search

Ceramic-based nanocomposites were reviewed, emphasizing the newly developed concept of material design for ceramics. First, characteristics of the nanocomposites observed by previous researchers were summarized as, significant or moderate improvement in strength, drastic change of the fracture mode from intergranular fracture of monolithic ceramics to transgranular fracture of nanocomposites, moderate enhancement of fracture toughness, improvement of other mechanical properties, and

Seong-Min Choi; Hideo Awaji

2006-01-01

80

Nanocomposites—a new material design concept  

Microsoft Academic Search

Ceramic-based nanocomposites were reviewed, emphasizing the newly developed concept of material design for ceramics. First, characteristics of the nanocomposites observed by previous researchers were summarized as, significant or moderate improvement in strength, drastic change of the fracture mode from intergranular fracture of monolithic ceramics to transgranular fracture of nanocomposites, moderate enhancement of fracture toughness, improvement of other mechanical properties, and

Seong-Min Choi; Hideo Awaji

2005-01-01

81

Microstructural design of materials for aerostatic bearings  

Microsoft Academic Search

The aim of this work is to investigate the development of a high strength porous cementitious composite manufactured via cold-pressed compaction for use as the restrictor in aerostatic bearings for high precision applications since they provide a number of advantages over conventional orifice restrictors. The selection of suitable materials and microstructural design of composites phases is essential to the development

T. H. Panzera; J. C. Rubio; C. R. Bowen; P. J. Walker

2008-01-01

82

Concurrent design of hierarchical materials and structures  

Microsoft Academic Search

\\u000a Significant achievements have been demonstrated in computational materials design and its broadening application in concurrent\\u000a engineering. Best practices are assessed and opportunities for improvement identified, with implications for modeling and\\u000a simulation in science and engineering. Successful examples of integration in undergraduate education await broader dissemination.

D. L. McDowell; G. B. Olson

83

Concurrent design of hierarchical materials and structures  

Microsoft Academic Search

Significant achievements have been demonstrated in computational materials design and its broadening application in concurrent\\u000a engineering. Best practices are assessed and opportunities for improvement identified, with implications for modeling and\\u000a simulation in science and engineering. Successful examples of integration in undergraduate education await broader dissemination.

D. L. McDowell; G. B. Olson

2008-01-01

84

46 CFR 58.05-1 - Material, design and construction.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Material, design and construction. 58...58.05-1 Material, design and construction. (a) The material, design, construction, workmanship...Bureau of Shipping Rules for Building and Classing Steel...

2013-10-01

85

Saving Material with Systematic Process Designs  

NASA Astrophysics Data System (ADS)

Global competition is forcing the stamping industry to further increase quality, to shorten time-to-market and to reduce total cost. Continuous balancing between these classical time-cost-quality targets throughout the product development cycle is required to ensure future economical success. In today's industrial practice, die layout standards are typically assumed to implicitly ensure the balancing of company specific time-cost-quality targets. Although die layout standards are a very successful approach, there are two methodical disadvantages. First, the capabilities for tool design have to be continuously adapted to technological innovations; e.g. to take advantage of the full forming capability of new materials. Secondly, the great variety of die design aspects have to be reduced to a generic rule or guideline; e.g. binder shape, draw-in conditions or the use of drawbeads. Therefore, it is important to not overlook cost or quality opportunities when applying die design standards. This paper describes a systematic workflow with focus on minimizing material consumption. The starting point of the investigation is a full process plan for a typical structural part. All requirements are definedaccording to a predefined set of die design standards with industrial relevance are fulfilled. In a first step binder and addendum geometry is systematically checked for material saving potentials. In a second step, blank shape and draw-in are adjusted to meet thinning, wrinkling and springback targets for a minimum blank solution. Finally the identified die layout is validated with respect to production robustness versus splits, wrinkles and springback. For all three steps the applied methodology is based on finite element simulation combined with a stochastical variation of input variables. With the proposed workflow a well-balanced (time-cost-quality) production process assuring minimal material consumption can be achieved.

Kerausch, M.

2011-08-01

86

Computational Materials Program for Alloy Design  

NASA Technical Reports Server (NTRS)

The research program sponsored by this grant, "Computational Materials Program for Alloy Design", covers a period of time of enormous change in the emerging field of computational materials science. The computational materials program started with the development of the BFS method for alloys, a quantum approximate method for atomistic analysis of alloys specifically tailored to effectively deal with the current challenges in the area of atomistic modeling and to support modern experimental programs. During the grant period, the program benefited from steady growth which, as detailed below, far exceeds its original set of goals and objectives. Not surprisingly, by the end of this grant, the methodology and the computational materials program became an established force in the materials communitiy, with substantial impact in several areas. Major achievements during the duration of the grant include the completion of a Level 1 Milestone for the HITEMP program at NASA Glenn, consisting of the planning, development and organization of an international conference held at the Ohio Aerospace Institute in August of 2002, finalizing a period of rapid insertion of the methodology in the research community worlwide. The conference, attended by citizens of 17 countries representing various fields of the research community, resulted in a special issue of the leading journal in the area of applied surface science. Another element of the Level 1 Milestone was the presentation of the first version of the Alloy Design Workbench software package, currently known as "adwTools". This software package constitutes the first PC-based piece of software for atomistic simulations for both solid alloys and surfaces in the market.Dissemination of results and insertion in the materials community worldwide was a primary focus during this period. As a result, the P.I. was responsible for presenting 37 contributed talks, 19 invited talks, and publishing 71 articles in peer-reviewed journals, as detailed later in this Report.

Bozzolo, Guillermo

2005-01-01

87

Peptoid polymers: a highly designable bioinspired material.  

PubMed

Bioinspired polymeric materials are attracting increasing attention due to significant advantages over their natural counterparts: the ability to precisely tune their structures over a broad range of chemical and physical properties, increased stability, and improved processability. Polypeptoids, a promising class of bioinspired polymer based on a N-substituted glycine backbone, have a number of unique properties that bridge the material gap between proteins and bulk polymers. Peptoids combine the sequence specificity of biopolymers with the simpler intra/intermolecular interactions and robustness of traditional synthetic polymers. They are highly designable because hundreds of chemically diverse side chains can be introduced from simple building blocks. Peptoid polymers can be prepared by two distinct synthetic techniques offering access to two material subclasses: (1) automated solid-phase synthesis which enables precision sequence control and near absolute monodispersity up to chain lengths of ~50 monomers, and (2) a classical polymerization approach which allows access to higher molecular weights and larger-scale yields, but with less control over length and sequence. This combination of facile synthetic approaches makes polypeptoids a highly tunable, rapid polymer prototyping platform to investigate new materials that are intermediate between proteins and bulk polymers, in both their structure and their properties. In this paper, we review the methods to synthesize peptoid polymers and their applications in biomedicine and nanoscience, as both sequence-specific materials and as bulk polymers. PMID:23721608

Sun, Jing; Zuckermann, Ronald N

2013-06-25

88

Materials by Design: Merging Proteins and Music  

PubMed Central

Tailored materials with tunable properties are crucial for applications as biomaterials, for drug delivery, as functional coatings, or as lightweight composites. An emerging paradigm in designing such materials is the construction of hierarchical assemblies of simple building blocks into complex architectures with superior properties. We review this approach in a case study of silk, a genetically programmable and processable biomaterial, which, in its natural role serves as a versatile protein fiber with hierarchical organization to provide structural support, prey procurement or protection of eggs. Through an abstraction of knowledge from the physical system, silk, to a mathematical model using category theory, we describe how the mechanism of spinning fibers from proteins can be translated into music through a process that assigns a set of rules that governs the construction of the system. This technique allows one to express the structure, mechanisms and properties of the ‘material’ in a very different domain, ‘music’. The integration of science and art through categorization of structure-property relationships presents a novel paradigm to create new bioinspired materials, through the translation of structures and mechanisms from distinct hierarchical systems and in the context of the limited number of building blocks that universally governs these systems.

Wong, Joyce Y.; McDonald, John; Taylor-Pinney, Micki; Spivak, David I.; Kaplan, David L.; Buehler, Markus J.

2013-01-01

89

Computational design of microvascular biomimetic materials  

NASA Astrophysics Data System (ADS)

Biomimetic microvascular materials are increasingly considered for a variety of autonomic healing, cooling and sensing applications. The microvascular material of interest in this work consists of a network of hollow microchannels, with diameters as small as 10 mum, embedded in a polymeric matrix. Recent advances in the manufacturing of this new class of materials have allowed for the creation of very complex 2D and 3D structures. The computational design of such network structures, which is the focus of this work, involves a set of particular challenges, including a large number of design variables (e.g., topology of the network, number of diameters to consider and their sizes) that define the network, and a large number of multidisciplinary objective functions and constraints that drive the optimization process. The computational design tool to be developed must be capable of capturing the trade-off between the different objective and constraint functions, as, for example, networks designed for flow efficiency are likely to have a topology that is very different from those designed for structural integrity or thermal control. In this work, we propose to design these materials using Genetic Algorithms (GAs), the most common methodology within a broader category of Evolutionary Algorithms (EAs). GAs can be combined with a Pareto-selection mechanism to create Multi-Objective Genetic Algorithms (MOGAs), which enable the optimization of an arbitrary number of objective functions. As a result, a Pareto-optimal front is obtained, where all candidates are optimal solutions to the optimization problem. Adding a procedure to deal with constraints results in a powerful tool for multi-objective constrained optimization. The method allows the use of discrete variable problems and it does not require any a priori knowledge of the optimal solution. Furthermore, GAs search the entire decision space so the optimal solutions found are likely to be global. TheMOGAoptimization framework is also combined with a physical solver based on advanced finite element methods to study the thermal behavior of these materials. Because the MOGA requires a vast number of individual evaluations, emphasis is placed on the computational efficiency of the solver. Thus, a simplified formulation is used to take into account the cooling effect of the fluid, instead of solving the conjugate heat transfer problem for obtaining the temperature field in both solid and fluid domains. The Generalized Finite Element Method (GFEM) is adopted because accurate finite element approximations of the temperature field can be obtained on finite element meshes that are independent of the geometry of the embedded network. Numerical experiments of multi-physics optimization involving flow efficiency, void volume fraction and thermal control are presented. Results show that the tradeoffs between conflicting objectives is well captured so that the optimal design is readily available to the analyst.

Aragon, Alejandro Marcos

90

Design of organic nonlinear optical materials  

NASA Astrophysics Data System (ADS)

This project deals with a new approach to designing organic nonlinear optical materials for second harmonic generation based on the use of hydrogen bonding to organize molecules into acentric arrays. Since crystal engineering is not a well developed science, crystal packing patterns can not yet be predicted for even simple organic molecules. For organic nonlinear optical materials this dilemma means that even the most promising organic molecule may have poor to nonexistent nonlinear optical properties because it forms centric crystals or crystals with unfavorable molecular dipole alignments. The work is aimed at gaining control over the crystal growth process by understanding the molecular basic for aggregation and nucleation. Using hydrogen bonds as one of the strongest, most prevalent, and most easily identified intermolecular interactions, it was found that the primary structure of hydrogen bonded aggregates can be predicted based on functional group complementarity and stereoelectronic considerations. This information is used to choose (or synthesize) molecules with hydrogen bonding groups positioned on the molecules so that acentric hydrogen bonded aggregates must necessarily form.

Etter, Margaret C.

1990-06-01

91

Haptic Aided Soft-touch Multi-material Product Design  

Microsoft Academic Search

In recent years, thermoplastic elastomers (TPE) based multi-material molded products have found wide spread uses in various industries and every-day life. Today's computer-aided design (CAD) tools are very cumbersome in designing multi-material parts. This paper proposes a top-down design methodology to facilitate the design of multi-material products. Haptic technology is employed to enhance efficiency and intuitiveness of the designing process.

Zhan Gao; Yonghua Chen; Lili Lian

2006-01-01

92

Design concepts for pressurized lunar shelters utilizing indigenous materials  

NASA Technical Reports Server (NTRS)

The objective is to design a pressurized shelter build of indigenous lunar material. The topics are presented in viewgraph form and include the following: lunar conditions which impact design; secondary factors; review of previously proposed concepts; cross section of assembly facility; rationale for indigenous materials; indigenous material choices; cast basalt properties; design variables; design 1, cylindrical segments; construction sequence; design 2, arch-slabs with post-tensioned ring girders; and future research.

Happel, John Amin; Willam, Kaspar; Shing, Benson

1991-01-01

93

Learning from systems biology: An ``Omics'' approach to materials design  

NASA Astrophysics Data System (ADS)

An understanding of systems biology provides an excellent paradigm for the materials scientist. Ultimately one would like to take an “atoms-applications” approach to materials design. This paper describes how the concepts of genomics, proteomics, and other biological behavior which form the foundations of modern biology can be applied to materials design through materials informatics.

Rajan, Krishna

2008-03-01

94

Mass of materials: the impact of designers on construction ergonomics.  

PubMed

Many construction injuries are musculoskeletal related in the form of sprains and strains arising from the handling of materials, which are specified by designers. The paper presents the results of a study conducted among delegates attending two 'designing for H&S' (DfH&S) seminars using a questionnaire. The salient findings include: the level of knowledge relative to the mass and density of materials is limited; designers generally do not consider the mass and density of materials when designing structures and elements and specifying materials; to a degree designers appreciate that the mass and density of materials impact on construction ergonomics; designers rate their knowledge of the mass and density of materials as limited, and designers appreciate the potential of the consideration of the mass and density of materials to contribute to an improvement in construction ergonomics. Conclusions include: designers lack the requisite knowledge relative to the mass and density of materials; designers are thus precluded from conducting optimum design hazard identification and risk assessments, and tertiary built environment designer education does not enlighten designers relative to construction ergonomics. Recommendations include: tertiary built environment designer education should construction ergonomics; professional associations should raise the level of awareness relative to construction ergonomics, and design practices should include a category 'mass and density of materials' in their practice libraries. PMID:22317574

Smallwood, John

2012-01-01

95

Materials by computational design -- High performance thermoelectric materials  

Microsoft Academic Search

The objective of the project was to utilize advanced computing techniques to guide the development of new material systems that significantly improve the performance of thermoelectric devices for solid state refrigeration. Lockheed Martin Energy Systems, Inc. (LMES) was to develop computational approaches to refine the theory of the thermoelectric effect, establish physical limits, and motivate new materials development. Prior to

B. Sales; H. Lyon

1997-01-01

96

Designing Spider Silk Proteins for Materials Applications.  

National Technical Information Service (NTIS)

Spider silks have the potential to provide new bio-based materials for numerous military applications ranging from protective clothing to parachute cords to composite materials in aircraft. Specific amino acid motifs have been identified which have been c...

R. V. Lewis

2009-01-01

97

Acquisition of Instructional Material Information as a Function of Manual Design and Material Complexity.  

ERIC Educational Resources Information Center

The study, with 52 preservice special education teachers, focused on effects of two types of teacher manual design and two levels of material complexity on comprehension of instructional materials utilization. Two materials were selected from an instructional materials collection for less complex material and for more complex material,…

Altman, Reuben; And Others

98

FOREWORD: Computational methodologies for designing materials Computational methodologies for designing materials  

NASA Astrophysics Data System (ADS)

It would be fair to say that in the past few decades, theory and computer modeling have played a major role in elucidating the microscopic factors that dictate the properties of functional novel materials. Together with advances in experimental techniques, theoretical methods are becoming increasingly capable of predicting properties of materials at different length scales, thereby bringing in sight the long-sought goal of designing material properties according to need. Advances in computer technology and their availability at a reasonable cost around the world have made tit all the more urgent to disseminate what is now known about these modern computational techniques. In this special issue on computational methodologies for materials by design we have tried to solicit articles from authors whose works collectively represent the microcosm of developments in the area. This turned out to be a difficult task for a variety of reasons, not the least of which is space limitation in this special issue. Nevertheless, we gathered twenty articles that represent some of the important directions in which theory and modeling are proceeding in the general effort to capture the ability to produce materials by design. The majority of papers presented here focus on technique developments that are expected to uncover further the fundamental processes responsible for material properties, and for their growth modes and morphological evolutions. As for material properties, some of the articles here address the challenges that continue to emerge from attempts at accurate descriptions of magnetic properties, of electronically excited states, and of sparse matter, all of which demand new looks at density functional theory (DFT). I should hasten to add that much of the success in accurate computational modeling of materials emanates from the remarkable predictive power of DFT, without which we would not be able to place the subject on firm theoretical grounds. As we know and will also see from the collection of works here, DFT also provides a platform for testing, improving, and evaluating the feasibility of more approximate methods whose need has become even more urgent. This is understandable since functional materials, given their limited translational symmetry, necessitate the usage of unit cells with a large number of atoms (sometimes in hundreds). Even if DFT codes were efficient enough to handle several hundred atoms in the calculational super-cell, the extraction of equilibrium geometry for such systems requires injection of more efficient methodology, as geometry is the input and not the output of a DFT calculation. Equally important is the need to calculate the temperature dependencies of material properties and for simulations to be carried out at length scales suitable for incorporating kinetic effects from competing processes and cooperative effects from constituting entities. It is true that codes based on DFT are becoming increasingly efficient and that methods such as ab initio molecular dynamics simulations are available for simulations of systems at temperatures above 0 K. However, such approaches still have a way to go before they can be readily applied to materials with complex geometries and composition, and for time and length scales that are relevant to realistic environments in the laboratory. Several articles here represent some of the recent advances towards 'multi-scale' modeling of materials. Among the articles that focus exclusively on DFT, the contribution by Weinert et al [1] summarizes some of the advances made to better describe magnetic properties and entropic effects. The article by Kyrychenko and Ullrich [2] discusses recent developments in time dependent DFT to describe transport properties and absorption spectra of solids. Their model allows for a comprehensive treatment of electron--electron interaction, screening and correlation effects which are necessary for proper description of properties of the excited state. The contribution by Langreth and co-workers [3] summarizes their recent efforts at incorpo

Rahman, Talat S.

2009-02-01

99

Printed circuit board material and design considerations for wireless applications  

Microsoft Academic Search

Designers are moving towards material systems which can be fabricated using conventional epoxy\\/glass printed circuit board (PCB) processes. This allows microwave circuits to be built using the vast fabrication infrastructure available for digital circuits. This paper provides basic background information about substrate material characteristics and design considerations, which are critical for wireless applications. Material characteristics discussed include dissipation factor, dielectric

Bob Daigle

1996-01-01

100

Application of modern new materials in product design  

Microsoft Academic Search

Material technology is one of the most important fields in the development of science technology. With the development of science technology, new materials appear and are widely used all over the world, and they give tremendous impetus to product design. At first, the paper describes how these new materials affect the product design. Then the paper discusses about the development

Hongyun Xiong; Surong Sun; Yan Jiang

2008-01-01

101

Writing and designing readable patient education materials.  

PubMed

Functional illiteracy is a problem often overlooked by nurses. Although the average adult in the United States cannot read above the eighth-grade level, most patient education materials are written on a high-school or college reading level. If patients cannot read educational materials, then there is little hope of them using or understanding the information. Strategies for improving the readability of education materials specific to the needs of nephrology patients are discussed in this article. PMID:15453229

Aldridge, Michael D

2004-01-01

102

Design and analysis of novel photocatalytic materials  

NASA Astrophysics Data System (ADS)

The development of sustainable sources of energy to decrease our dependence on non-renewable fossil fuels and the reduction of emissions causing global warming are important technological challenges of the 21st century. Production of solar fuels by photocatalysis is one potential route to reduce the impact of those problems. The most widely applied photocatalyst is TiO2 because it is stable, non-toxic and inexpensive. Still, it cannot utilize the solar spectrum efficiently as its band gap is 3.2 eV thus able to absorb only 3% of sun light. This thesis therefore explores multiple avenues towards improving the light absorption capability of semiconductor materials without loss in activity. To achieve this objective, the valence band hybridization method of band gap reduction was utilized. This technique is based on introducing new orbitals at the top of valence band of the semiconductor that can then hybridize with existing orbitals. The hybridization then raises the maximum of the valence band thereby reducing the band gap. This technique has the added advantage of increasing the mobility of oxidizing holes in the now dispersed valence band. In practice, this can be achieved by introducing N 2p or Sn 5s orbitals in the valence band of an oxide. We initially designed novel zinc gallium oxy-nitrides, with the spinel structure and band gaps in the visible region of the solar spectrum, by nitridation of a zinc gallate precursor produced by sol-gel synthesis. These spinel oxy-nitrides have band gaps of 2.5 to 2.7 eV, surface areas of 16 to 36 m 2/g, and nitrogen content less than 1.5%. They are active towards degradation of organic molecules in visible light. Density functional theory calculations show that this band gap reduction in part is associated with hybridization between the dopant N 2p states with Zn 3d orbitals at the top of the valence band. While spinel oxy-nitrides are produced under nitridation at 550°C, at higher temperatures they are consumed to form wurzitic oxy-nitrides. The wurzite materials also have band gaps less than 3 eV but their surface areas are 2 to 5 m2/g. The thesis explores in detail the changes associated with the gallium coordination as the spinel zinc gallate precursor transforms into the spinel oxy-nitride at 550°C, and further changes into the wurzite oxy-nitride at 850°C are studied through X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, neutron powder diffraction, X-ray absorption spectroscopy and other techniques. We believe that the protocol developed in this thesis opens an avenue for the synthesis of semiconductors having the spinel crystal structure and band gaps engineered to the visible region with potential applications for opto-electronic devices and photocatalytic processes. Though these spinel oxynitrides are interesting, they suffer from vacancies and low surface areas from the high temperature nitridation step. This could be overcome by synthesizing photocatalysts hydrothermally. We proceeded to explore the interactions of Sn2+ 5s orbitals with O 2p orbitals towards hybridizing the valence band. This led to the development of novel visible-light-active Sn2+ - TiO2 and SnOx -- ZnGa2O4 materials. The former catalysts are prepared from the reaction of titanium butoxide and several tin precursors at 80°C in aqueous solutions. Samples synthesized with SnCl2 have lower band gaps (red-shifted to the visible region) with respect to anatase TiO2. The catalysts are isostructural with anatase TiO2 even at the highest loadings of Sn2+. When the precursor is changed to SnCl4, rutile is the predominant phase obtained but no reduction in the band gap is observed. The experiments also indicate the presence of chlorine in the samples, also influencing the optical and catalytic properties as confirmed by comparison to materials prepared using bromide precursors. These catalysts are photocatalytically active for the degradation of organic molecules with rates higher than the standard (P25 TiO2) and also evidenced from the generation of hydroxyl radicals using visible

Boppana, Venkata Bharat Ram

103

Materials 4: Design Strategies for Transformative Innovation  

NSDL National Science Digital Library

What can we learn from nature's designs for sustainability? This video compares nature's methods with the industrial era methods of design. It recommends a design strategy based on the connection or relationship between things as a means to achieve transformative innovation for sustainability. This video is part of the Sustainability Learning Suites, made possible in part by a grant from the National Science Foundation. See 'Learn more about this resource' for Learning Objectives and Activities.

Vanasupa, Linda

104

Material, process, and product design of thermoplastic composite materials  

Microsoft Academic Search

Thermoplastic composites made of polypropylene (PP) and E-glass fibers were investigated experimentally as well as theoretically for two new classes of product designs. The first application was for reinforcement of wood. Commingled PP\\/glass yarn was consolidated and bonded on wood panel using a tie layer. The processing parameters, including temperature, pressure, heating time, cooling time, bonding strength, and bending strength

Heming Dai

2001-01-01

105

COMPUTATIONAL DESIGN OF MULTIPHASE MATERIALS AT THE MESOLEVEL  

Microsoft Academic Search

A concept of optimal design of multiphase materials on the basis of numerical simulation of damage and fracture growth in real and artificial microstructures of the materials is formulated. The suggested procedure includes the following steps: image analysis of the material structure; determination of properties of constituents of the materials; search for regularities or periodicity in the microstructure; simulation of

Leon Mishnaevsky Jr; Nils Lippmann; Siegfried Schmauder

2001-01-01

106

Synthesis and design of silicide intermetallic materials  

SciTech Connect

The overall objective of this program is to develop structural silicide-based materials with optimum combinations of elevated temperature strength/creep resistance, low temperature fracture toughness, and high temperature oxidation and corrosion resistance for applications of importance to the U.S. processing industry. A further objective is to develop silicide-based prototype industrial components. The ultimate aim of the program is to work with industry to transfer the structural silicide materials technology to the private sector in order to promote international competitiveness in the area of advanced high temperature materials and important applications in major energy-intensive U.S. processing industries.

Petrovic, J.J.; Castro, R.G.; Butt, D.P.; Park, Y.; Hollis, K.J.; Kung, H.H.

1998-11-01

107

Materials developments for advanced reactor designs  

Microsoft Academic Search

Progressing technological demands of advanced reactor development require that the designer have at his disposal quick-responding analytical support as well as immediate access to experimental facilities. The close cooperation between design office, research and development department, and trial manufacturing provides the necessary short iteration loops when developing new methods and products. Over the last two decades, many research programs were

P. Burgsmueller; H. Charles; H. Fricker

1988-01-01

108

Design for containment of hazardous materials  

SciTech Connect

Department of Energy, (DOE), facilities across the United States, use wind and tornado design and evaluation criteria based on probabilistic performance goals. In addition, other programs such as Advanced Light Water Reactors, New Production Reactors, and Individual Plant Examinations for External Events for commercial nuclear power plants utilize design and evaluation criteria based on probabilistic performance goals. The use of probabilistic performance goals is a departure from design practice for commercial nuclear power plants which have traditionally been designed utilizing a conservative specification of wind and tornado loading combined with deterministic response evaluation methods and permissible behavior limits. Approaches which utilize probabilistic wind and tornado hazard curves for specification of loading and deterministic response evaluation methods and permissible behavior limits are discussed in this paper. Through the use of such design/evaluation approaches, it may be demonstrated that there is high likelihood that probabilistic performance goals can be achieved. 14 refs., 1 fig., 5 tabs.

Murray, R.C. (Lawrence Livermore National Lab., CA (United States)); McDonald, J.R. (Texas Tech Univ., Lubbock, TX (United States))

1991-03-01

109

Material, process, and product design of thermoplastic composite materials  

NASA Astrophysics Data System (ADS)

Thermoplastic composites made of polypropylene (PP) and E-glass fibers were investigated experimentally as well as theoretically for two new classes of product designs. The first application was for reinforcement of wood. Commingled PP/glass yarn was consolidated and bonded on wood panel using a tie layer. The processing parameters, including temperature, pressure, heating time, cooling time, bonding strength, and bending strength were tested experimentally and evaluated analytically. The thermoplastic adhesive interface was investigated with environmental scanning electron microscopy. The wood/composite structural design was optimized and evaluated using a Graphic Method. In the second application, we evaluated use of thermoplastic composites for explosion containment in an arrester. PP/glass yarn was fabricated in a sleeve form and wrapped around the arrester. After consolidation, the flexible composite sleeve forms a solid composite shell. The composite shell acts as a protection layer in a surge test to contain the fragments of the arrester. The manufacturing process for forming the composite shell was designed. Woven, knitted, and braided textile composite shells made of commingled PP/glass yarn were tested and evaluated. Mechanical performance of the woven, knitted, and braided composite shells was examined analytically. The theoretical predictions were used to verify the experimental results.

Dai, Heming

110

Radioactive material transportation package design using numerical optimization techniques.  

National Technical Information Service (NTIS)

Increasing computational speed has led to the development and use of sophisticated numerical methods in radioactive material (RAM) transportation container design. The design of a RAM container often involves a complex coupling of structural, thermal, and...

D. C. Harding M. S. Eldred

1995-01-01

111

Thermal Characterization of Functionally Graded Materials: Design of Optimum Experiments  

NASA Technical Reports Server (NTRS)

This paper is a study of optimal experiment design applied to the measure of thermal properties in functionally graded materials. As a first step, a material with linearly-varying thermal properties is analyzed, and several different tran- sient experimental designs are discussed. An optimality criterion, based on sen- sitivity coefficients, is used to identify the best experimental design. Simulated experimental results are analyzed to verify that the identified best experiment design has the smallest errors in the estimated parameters. This procedure is general and can be applied to design of experiments for a variety of materials.

Cole, Kevin D.

2003-01-01

112

Photonic bandgap materials: Design, fabrication, and characterization  

NASA Astrophysics Data System (ADS)

The last few decades have seen a tremendous explosion in the area of new synthetic materials. As we begin to better understand the nature of the atomic and molecular bonds it has been possible to systematically search for materials with specific properties thanks to the availability of powerful supercomputers. Due to significant advances in materials synthesis a rich variety of artificial materials whose mechanical, chemical, electronic and optical properties can be suitably tailored can now be produced. Some of the materials (plastics, synthetic fibers, ceramics, alloys etc.) can replace or substitute traditional materials; some others have managed to create new applications themselves (semiconductors, superconductors, optical fibers etc.). Over the last decade there has been a growing interest in a new material called "photonic bandgap structures" which can manipulate light in an extraordinary way opening up new possibilities in the area of optics and optoelectronics, eventually paving the way for optical computing. Proof of principle structures that demonstrates the expected property has been successfully fabricated for low frequency electromagnetic waves. However, making photonic bandgap structures that can operate at visible frequency is quite challenging. This is because photonic bandgap material are essentially periodic dielectric structures where the periodicity is on the order of the wavelength of light. The goal of this dissertation is to develop a technique for the fabrication inverse FCC photonic crystals that can operate at the visible and near infrared frequencies. The technique essentially focuses on employing self organizing systems such as monodisperse colloidal systems of polystyrene microspheres as a basis for forming periodic structure at submicron dimensions. The main aspects are first to show that the experimental procedure for fabrication developed in this dissertation actually has the desired structural property. Demonstration of structural properties is done by means of optical microscopy and scanning electron microscopy. The other aspect is to demonstrate that the photonic structure so produced indeed shows effects due to photonic bandgap. Optical spectroscopy of the samples is used to show that these samples indeed show the pseudogap that has been theoretically predicted for photonic crystals made with the materials used.

Subramania, Ganapathi S.

113

The design of exotic superhard materials  

Microsoft Academic Search

Diamond has the highest bond energy per unit volume of all known materials, and hence it is assumed to possess the highest hardness. Diamond’s hardness comes from its small atoms that each of them forms four covalent bonds. To make a structure harder than diamond, its atoms must be smaller than carbon, and\\/or these atoms form at least four covalent

James Sung

2001-01-01

114

Center for Intelligent Fuel Cell Materials Design  

Microsoft Academic Search

The goal of this work was to develop a composite proton exchange membrane utilizing 1) readily available, low cost materials 2) readily modified and 3) easily processed to meet the chemical, mechanical and electrical requirements of high temperature PEM fuel cells. One of the primary goals was to produce a conducting polymer that met the criteria for strength, binding capability

P. R. Santurri; C. Hartmann-Thompson; S. E. Keinath

2008-01-01

115

Computational materials design for energy applications  

NASA Astrophysics Data System (ADS)

General adoption of sustainable energy technologies depends on the discovery and development of new high-performance materials. For instance, waste heat recovery and electricity generation via the solar thermal route require bulk thermoelectrics with a high figure of merit (ZT) and thermal stability at high-temperatures. Energy recovery applications (e.g., regenerative braking) call for the development of rapidly chargeable systems for electrical energy storage, such as electrochemical supercapacitors. Similarly, use of hydrogen as vehicular fuel depends on the ability to store hydrogen at high volumetric and gravimetric densities, as well as on the ability to extract it at ambient temperatures at sufficiently rapid rates. We will discuss how first-principles computational methods based on quantum mechanics and statistical physics can drive the understanding, improvement and prediction of new energy materials. We will cover prediction and experimental verification of new earth-abundant thermoelectrics, transition metal oxides for electrochemical supercapacitors, and kinetics of mass transport in complex metal hydrides.

Ozolins, Vidvuds

2013-03-01

116

Design for a fusion materials irradiation facility  

SciTech Connect

A fusion materials irradiation facility is required for the timely and cost-effective development of economical fusion power. Our conceptual machine provides sufficient neutron fluence for accelerated lifetime material tests in a time span of 1--2 y while producing less than 1 MW of fusion power. Neutral deuterium beams at 150 keV are injected into the center of a high-density warm tritium plasma housed in a 12-m-long cylindrical vessel. Superconducting magnets hold the plasma, which transfers the power to each end of the solenoid. The stainless steel end sections absorb the beam power and are externally cooled by high-pressure water to maintain the plasma-side wall temperature below 740 K. A service loop separates tritium from deuterium in the plasma effluent. Tritium is reinjected at each end. 9 refs., 2 figs., 2 tabs.

Walter, C.E.; Coensgen, F.H.

1988-09-02

117

Design of Polysiloxane Materials for Electronic Applications  

Microsoft Academic Search

Dehydrocoupling reaction catalyzed by palladium was used to synthesize aromatic-substituted poly(carbosiloxane)s having potentiality to be used as thermo-resistant insulating materials. Well-defined transmission holographic gratings with high diffraction efficiency were fabricated by the introduction of siloxane components: 1) to mesogenic compounds, 2) to bifunctional epoxides as cationically polymerizable monomers, which polymerize slower than radically polymerizable multi-functional acrylate.

Yusuke Kawakami; Yeong Hee Cho; Man He; Lei Xue

2006-01-01

118

Designing ultrastrong materials for space applications  

NASA Astrophysics Data System (ADS)

The mass-strength ratio is of exceptional importance for space application. The critical parts of both shuttle vehicles and satellites depends on strength and toughness of the materials they are made of, while strict limitations on the weight of the different components are placed by the launch technology. Single wall carbon nanotubes (SWNT) present significant potential as the basic material for the space applications. Exceptional mechanical properties of single wall carbon nanotubes (SWNT) have prompted intensive studies of SWNT composites. These qualities can also be used in a variety of other technologies from automotive to military and medical. However, the present composites have shown only a moderate strength enhancement when compared to other hybrid materials. Although substantial advances have been made, mechanical characteristics of SWNT-doped polymers are noticeably below their highly anticipated potential. Pristine SWNTs are well known for poor solubilization, which leads to phase segregation of composites. Severe structural inhomogeneities result in the premature failure of the hybrid SWNT/polymer materials. The connectivity with and uniform distribution within the matrix are essential structural requirements for the strong SWNT composites. Here we show that a new processing approach based on sequential layering of chemically-modified nanotubes and polyelectrolytes can greatly diminish the phase segregation and render SWNT composite highly homogeneous. Combined with chemical cross-linking, this processing leads to drastically improved mechanical properties. Tensile strength of the composites is several times higher than that of SWNT composites made via mixing; it approaches values seen for hard ceramics. The universality of the layering approach applicable to a wide range of functional materials makes possible successful incorporation of SWNT into a variety of composites imparting them required mechanical properties. The thin film membranes that are obtained in the result of the layer-by-layer process can be used as an intermediate or as a component of ultrastrong laminates. At the same time, the prepared membranes can also be utilized in the as-prepared form for the large area space telescopes (both radio and optical) because the combine the strength and multiple functionality of the SWNT membranes with the ease of deployment.

Kotov, Nicholas A.; Mamedov, Arif A.; Prato, Maurizio; Guldi, Dirk M.; Wicksted, James P.; Hirsch, Andreas

2004-02-01

119

Concurrent materials and process selection in conceptual design  

SciTech Connect

The sequential manner in which materials and processes for a manufactured product are selected is inherently less than optimal. Designers` tendency to choose processes and materials with which they are familiar exacerbate this problem. A method for concurrent selection of materials and a joining process based on product requirements using a knowledge-based, constraint satisfaction approach is presented.

Kleban, S.D.

1998-07-01

120

Designing Teaching Materials for Learning Problem Solving in Technology Education  

Microsoft Academic Search

In the process of designing teaching materials for learning problem solving in technology education, domain-specific design specifications are considered important elements to raise learning outcomes with these materials. Two domain-specific design specifications were drawn up using a four-step procedure and were applied to improve existing teaching-learning packages. The study focused on a construction problem (open-ended) and an explanation problem (constrained).

B. G. Doornekamp

2001-01-01

121

Material Compatibility with Space Storable Propellants. Design Guidebook  

NASA Technical Reports Server (NTRS)

An important consideration in the design of spacecraft for interplanetary missions is the compatibility of storage materials with the propellants. Serious problems can arise because many propellants are either extremely reactive or subject to catalytic decomposition, making the selection of proper materials of construction for propellant containment and control a critical requirement for the long-life applications. To aid in selecting materials and designing and evaluating various propulsion subsystems, available information on the compatibility of spacecraft materials with propellants of interest was compiled from literature searches and personal contacts. The compatibility of both metals and nonmetals with hydrazine, monomethyl hydrazine, nitrated hydrazine, and diborance fuels and nitrogen tetroxide, fluorine, oxygen difluoride, and Flox oxidizers was surveyed. These fuels and oxidizers encompass the wide variety of problems encountered in propellant storage. As such, they present worst case situations of the propellant affecting the material and the material affecting the propellant. This includes material attack, propellant decomposition, and the formation of clogging materials.

Uney, P. E.; Fester, D. A.

1972-01-01

122

Design with brittle materials - An interdisciplinary educational program  

NASA Technical Reports Server (NTRS)

A series of interdisciplinary design courses being offered to senior and graduate engineering students at the University of Washington is described. Attention is given to the concepts and some of the details on group design projects that have been undertaken during the past two years. It is noted that ceramic materials normally demonstrate a large scatter in strength properties. As a consequence, when designing with these materials, the conventional 'mil standards' design stresses with acceptable margins of safety cannot by employed and the designer is forced to accept a probable number of failures in structures of a given brittle material. It is this prediction of the probability of failure for structures of given, well-characterized materials that forms the basis for this series of courses.

Mueller, J. I.; Bollard, R. J. H.; Hartz, B. J.; Kobayashi, A. S.; Love, W. J.; Scott, W. D.; Taggart, R.; Whittemore, O. J.

1980-01-01

123

Center for Intelligent Fuel Cell Materials Design  

SciTech Connect

The goal of this work was to develop a composite proton exchange membrane utilizing 1) readily available, low cost materials 2) readily modified and 3) easily processed to meet the chemical, mechanical and electrical requirements of high temperature PEM fuel cells. One of the primary goals was to produce a conducting polymer that met the criteria for strength, binding capability for additives, chemical stability, dimensional stability and good conductivity. In addition compatible, specialty nanoparticles were synthesized to provide water management and enhanced conductivity. The combination of these components in a multilayered, composite PEM has demonstrated improved conductivity at high temperatures and low humidity over commercially available polymers. The research reported in this final document has greatly increased the knowledge base related to post sulfonation of chemically and mechanically stable engineered polymers (Radel). Both electrical and strength factors for the degree of post sulfonation far exceed previous data, indicating the potential use of these materials in suitable proton exchange membrane architectures for the development of fuel cells. In addition compatible, hydrophilic, conductive nano-structures have been synthesized and incorporated into unique proton exchange membrane architectures. The use of post sulfonation for the engineered polymer and nano-particle provide cost effective techniques to produce the required components of a proton exchange membrane. The development of a multilayer proton exchange membrane as described in our work has produced a highly stable membrane at 170°C with conductivities exceeding commercially available proton exchange membranes at high temperatures and low humidity. The components and architecture of the proton exchange membrane discussed will provide low cost components for the portable market and potentially the transportation market. The development of unique components and membrane architecture provides a key element for the United States: 1) to transition the country from a fossil fuel based energy economy to a renewable energy based economy, and 2) to reduce our dependence on foreign oil. Developments of this program will serve as an important step toward continuing PEMFC technology and ultimately the broad-based commercial availability of this technology and its benefits.

Santurri, P.R., (Chemsultants International); Hartmann-Thompson, C.; Keinath, S.E. (Michigan Molecular Inst.)

2008-08-26

124

Photovoltaic-module encapsulation design and materials selection: Volume 1  

SciTech Connect

Encapsulation-material system requirements, material-selection criteria, and the status and properties of encapsulation materials and processes available to the module manufacturer are presented in detail. Technical and economic goals established for photovoltaic modules and encapsulation systems and their status are described for material suppliers to assist them in assessing the suitability of materials in their product lines and the potential of new-material products. A comprehensive discussion of available encapsulation technology and data is presented to facilitate design and material selection for silicon flat-plate photovoltaic modules, using the best materials available and processes optimized for specific power applications and geographic sites. A basis is provided for specifying the operational and environmental loads that encapsulation material systems must resist. Potential deployment sites for which cost effectiveness may be achieved at a module price much greater than $0.70/W/sub p/, are also considered; data on higher-cost encapsulant materials and processes that may be in use and other material candidates that may be justified for special application are discussed. Described are encapsulation-system functional requirements and candidate design concepts and materials that have been identified and analyzed as having the best potential to meet the cost and performance goals for the Flat-Plate Solar Array Project. The available data on encapsulant material properties, fabrication processing, and module life and durability characteristics are presented.

Cuddihy, E.; Carroll, W.; Coulbert, C.; Gupta, A.; Liang, R.

1982-06-01

125

Technology update: Tethered aerostat structural design and material developments  

NASA Technical Reports Server (NTRS)

Requirements exist for an extremely stable, high performance, all-weather tethered aerostat system. This requirement has been satisfied by a 250,000 cubic foot captive buoyant vehicle as demonstrated by over a year of successful field operations. This achievement required significant advancements in several technology areas including composite materials design, aerostatics and aerodynamics, structural design, electro-mechanical design, vehicle fabrication and mooring operations. This paper specifically addresses the materials and structural design aspects of pressurized buoyant vehicles as related to the general class of Lighter Than Air vehicles.

Witherow, R. G.

1975-01-01

126

Evaluation of materials and design modifications for aircraft brakes  

NASA Technical Reports Server (NTRS)

A test program is described which was carried out to evaluate several proposed design modifications and several high-temperature friction materials for use in aircraft disk brakes. The evaluation program was carried out on a specially built test apparatus utilizing a disk brake and wheel half from a small het aircraft. The apparatus enabled control of brake pressure, velocity, and braking time. Tests were run under both constant and variable velocity conditions and covered a kinetic energy range similar to that encountered in aircraft brake service. The results of the design evaluation program showed that some improvement in brake performance can be realized by making design changes in the components of the brake containing friction material. The materials evaluation showed that two friction materials show potential for use in aircraft disk brakes. One of the materials is a nickel-based sintered composite, while the other is a molybdenum-based material. Both materials show much lower wear rates than conventional copper-based materials and are better able to withstand the high temperatures encountered during braking. Additional materials improvement is necessary since both materials show a significant negative slope of the friction-velocity curve at low velocities.

Ho, T. L.; Kennedy, F. E.; Peterson, M. B.

1975-01-01

127

The International Thermonuclear Experimental Reactor (ITER): Design and materials selection  

SciTech Connect

The success of ITER relies on aggressive design of the superconducting magnet systems. This design emphasized high radiation-damage tolerance, acceptance of high nuclear heat loads, and high operational stresses in the Toroidal Field (TF) magnets. The design of the Central Solenoid (CS) magnets, although they will be well shielded from the plasma, is equally aggressive due to the need for very high magnetic fields (14 T) and long term operation at high cyclic stresses. Success of these magnet designs depends, in part, on sound selection and fabrication of materials for structural, superconducting, and insulating components. Here we review the design of ITER and the selection of structural materials for some of the systems that will operate at cryogenic temperatures. In addition we will introduce some of the data that the materials selection is based on and suggest opportunities for future research in support of ITER. 10 refs., 1 fig., 4 tabs.

Summers, L.T.; Miller, J.R.; Heim, J.R.

1989-08-08

128

Designing Radiation Resistance in Materials for Fusion Energy  

SciTech Connect

Proposed fusion and advanced (Generation IV) fission energy systems require high performance materials capable of satisfactory operation up to neutron damage levels approaching 200 atomic displacements per atom with large amounts of transmutant hydrogen and helium isotopes. After a brief overview of fusion reactor concepts and radiation effects phenomena in structural and functional (non-structural) materials, three fundamental options for designing radiation resistance are outlined: Utilize matrix phases with inherent radiation tolerance, select materials where vacancies are immobile at the design operating temperatures, or construct high densities of point defect recombination sinks. Environmental and safety considerations impose several additional restrictions on potential materials systems, but reduced activation ferritic/martensitic steels (including thermomechanically treated and oxide dispersion strengthened options) and silicon carbide ceramic composites emerge as robust structural materials options. Materials modeling (including computational thermodynamics) and advanced manufacturing methods are poised to exert a major impact in the next ten years.

Zinkle, Steven J [University of Tennessee (UT)] [University of Tennessee (UT); Snead, Lance Lewis [ORNL] [ORNL

2014-01-01

129

Unravelling Porous Asphalt Concrete towards a Mechanistic Material Design Tool  

Microsoft Academic Search

PA (Porous Asphalt Concrete) is the standard surfacing material for the Dutch primary road network. Approximately 80% of this network is surfaced with PA. Ravelling, the loss of stone from the road surface, is in most cases by far decisive for PA service life. Ravelling resistance is mainly generated by PA material performance and not by the pavement's structural design.

Rien M. Huurman; Liantong Mo; Milliyon F. Woldekidan

2010-01-01

130

Construction of irradiated material examination facility-basic design.  

National Technical Information Service (NTIS)

The basic design of the hot cell facility which has the main purpose of doing mechanical and physical property tests of irradiated materials, the examination process, and the annexed facility has been made. Also basic and detall designs for the undergroun...

S. G. Ro E. K. Kim G. W. Hong Y. H. Herr K. P. Hong

1989-01-01

131

Materials and design of the European DEMO blankets  

Microsoft Academic Search

The Helium Cooled Lithium Lead (HCLL) and the Helium Cooled Pebble Bed (HCPB) Blanket are the reference concepts in the European Breeding Blanket Programme for the DEMO design and for the related long term R&D. Recently, a similar design for both concepts has been developed, in particular both concepts use helium coolant and RAFM steel EUROFER as structural material. In

L. V. Boccaccini; L. Giancarli; G. Janeschitz; S. Hermsmeyer; Y. Poitevin; A. Cardella; E. Diegele

2004-01-01

132

Designing optical elements from isotropic materials by using transformation optics  

SciTech Connect

By taking advantage of a conformal mapping technique, we propose designs for various optical elements such as directional antennas, flat lenses, or bends. In contrast to most of the existing design approaches, the elements can be implemented with isotropic materials, thus strongly facilitating their fabrication. We furthermore generalize the concept and show that under certain conditions previously suggested devices consisting of anisotropic materials may be replaced by isotropic ones using an appropriate transformation. The designs are double-checked by full-wave simulations. A comparison with their anisotropic counterparts reveals a similar performance.

Schmiele, Martin; Varma, Vineeth S.; Rockstuhl, Carsten; Lederer, Falk [Institute of Solid State Theory and Optics, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany)

2010-03-15

133

Designing Advanced Materials As Simple As Assembling Lego® Blocks!  

NASA Astrophysics Data System (ADS)

Crystal engineering is a rapidly developing interdisciplinary field. As the name implies, it is primarily concerned with the systematic study of crystalline architectures and thereby controlling functional properties of solids. Recent conceptual advances have simplified the complex problem of crystal structure prediction into a mere topological organization of molecular building blocks. Accordingly, crystal structures can be viewed as networks where molecules, metals, ions, etc. are considered as nodes and intermolecular interactions/coordination bonds between the molecules as node connections. In this context, attempts have been made to highlight the striking parallels between current strategies for materials design and the construction of architectures using Lego building blocks, for an understanding of the principles and problems associated with predicting crystal structure. How the rational designing strategies can be effectively applied for the design of a variety of advanced materials such as porous solids, ion exchange materials, molecular metals, conductors, and optical materials is also discussed.

Krishnamohan Sharma, C. V.

2001-05-01

134

Designing Teaching Materials for Learning Problem Solving in Technology Education  

NASA Astrophysics Data System (ADS)

In the process of designing teaching materials for learning problem solving in technology education, domain-specific design specifications are considered important elements to raise learning outcomes with these materials. Two domain-specific design specifications were drawn up using a four-step procedure and were applied to improve existing teaching-learning packages. The study focused on a construction problem (open-ended) and an explanation problem (constrained). Construction material (fischertechnik) was used to solve the problems. In two experiments, these newly designed teaching materials were compared with the existing teaching materials. In all, 600 pupils participated in these experiments. In the experiment with the construction problem, no learning gains were made at all: the small gain in quality of the product made by the pupils cost too much time. In the experiment with the explanation problem, the quality of the pupils' product was significantly better in less time. It is argued that strongly structured teaching materials for constrained problems are more suitable for learners with little experience with construction material.

Doornekamp, B. G.

2001-01-01

135

Structural and Machine Design Using Piezoceramic Materials: A Guide for Structural Design Engineers  

NASA Technical Reports Server (NTRS)

Using piezoceramic materials is one way the design engineer can create structures which have an ability to both sense and respond to their environment. Piezoceramic materials can be used to create structural sensors and structural actuators. Because piezoceramic materials have transduction as a material property, their sensing or actuation functions are a result of what happens to the material. This is different than discrete devices we might attach to the structure. For example, attaching an accelerometer to a structure will yield an electrical signal proportional to the acceleration at the attachment point on the structure. Using a electromagnetic shaker as an actuator will create an applied force at the attachment point. Active material elements in a structural design are not easily modeled as providing transduction at a point, but rather they change the physics of the structure in the areas where they are used. Hence, a designer must not think of adding discrete devices to a structure to obtain an effect, but rather must design a structural system which accounts for the physical principles of all the elements in the structure. The purpose of this manual is to provide practicing engineers the information necessary to incorporate piezoelectric materials in structural design and machine design. First, we will review the solid-state physics of piezoelectric materials. Then we will discuss the physical characteristics of the electrical-active material-structural system. We will present the elements of this system which must be considered as part of the design task for a structural engineer. We will cover simple modeling techniques and review the features and capabilities of commercial design tools that are available. We will then cover practical how-to elements of working with piezoceramic materials. We will review sources of piezoceramic materials and built-up devices, and their characteristics. Finally, we will provide two design examples using piezoceramic materials, first as discrete actuators for vibration isolation, and second as structurally-distributed sensor/actuators for active acoustic control.

Inman, Daniel J.; Cudney, Harley H.

2000-01-01

136

Effective Materials Properties of Interconnections in Industrial Microprocessor Designs  

NASA Astrophysics Data System (ADS)

This talk presents a methodology to evaluate tradeoffs between technology and design to obtain the highest performance in industrial VLSI designs [1]. It is well known that the most significant circuitry constraint is that signals must arrive on time. Since the design cycle is time-consuming and complex, there is a need to migrate designs to future technology nodes to amortize design cost. However, models do not exist [1] to guide designers in their evaluation of whether migrated designs will operate successfully in a future technology or whether migrated designs will cause chip failure. There is therefore a need to evaluate the impact of design changes on performance. This talk evaluates this impact and describes it as an effective change in material properties of the design interconnections. Model estimates are compared with industrial microprocessor design data [1]. References [1] M. Y. Lanzerotti, G. Fiorenza, R. Rand, "Impact of interconnect length changes on effective materials properties (dielectric constant)," Proc. Ninth International ACM Workshop on System-Level Interconnect Prediction (SLIP 2007), Austin, TX, USA, March 17-18, 2007. Online: http://www.informatik.uni-trier.de/˜ley/db/conf/slip/slip2007.html, current as of 11-16-2010.

Lanzerotti, Mary; Fiorenza, Giovanni; Rand, Rick

2011-03-01

137

Physics towards next generation Li secondary batteries materials: A short review from computational materials design perspective  

NASA Astrophysics Data System (ADS)

The physics that associated with the performance of lithium secondary batteries (LSB) are reviewed. The key physical problems in LSB include the electronic conduction mechanism, kinetics and thermodynamics of lithium ion migration, electrode/ electrolyte surface/interface, structural (phase) and thermodynamics stability of the electrode materials, physics of intercalation and deintercalation. The relationship between the physical/chemical nature of the LSB materials and the batteries performance is summarized and discussed. A general thread of computational materials design for LSB materials is emphasized concerning all the discussed physics problems. In order to fasten the progress of the new materials discovery and design for the next generation LSB, the Materials Genome Initiative (MGI) for LSB materials is a promising strategy and the related requirements are highlighted.

Ouyang, ChuYing; Chen, LiQuan

2013-12-01

138

Making the mid-infrared nano with designer plasmonic materials  

NASA Astrophysics Data System (ADS)

Here we demonstrate a new class of designer plasmonic materials for use in the mid-infrared (mid-IR) region of the electromagnetic spectrum. By heavily doping epitaxially-grown semiconductor materials, we are able to grow single-crystal materials whose optical properties in the mid-IR mimic those of metals at shorter wavelengths. We demonstrate materials with plasma frequencies from 5.5-15?m and low losses, compared to their shortwavelength counterparts. In addition, we demonstrate the ability of subwavelength particles formed from our materials to support localized surface plasmon resonances, and measure the near-field absorption of these structures using a novel nanoscale infrared spectroscopy technique. Finally, we show good agreement between our observed results and analytical and finite-element models of our materials and structures. The results presented offer a path towards nanoscale confinement of light with micron-scale wavelengths.

Law, S.; Felts, J.; Roberts, C.; Podolskiy, V. A.; King, W. P.; Wasserman, D.

2012-11-01

139

Optimal Experiment Design for Thermal Characterization of Functionally Graded Materials  

NASA Technical Reports Server (NTRS)

The purpose of the project was to investigate methods to accurately verify that designed , materials meet thermal specifications. The project involved heat transfer calculations and optimization studies, and no laboratory experiments were performed. One part of the research involved study of materials in which conduction heat transfer predominates. Results include techniques to choose among several experimental designs, and protocols for determining the optimum experimental conditions for determination of thermal properties. Metal foam materials were also studied in which both conduction and radiation heat transfer are present. Results of this work include procedures to optimize the design of experiments to accurately measure both conductive and radiative thermal properties. Detailed results in the form of three journal papers have been appended to this report.

Cole, Kevin D.

2003-01-01

140

Modular design in natural and biomimetic soft materials.  

PubMed

Under eons of evolutionary and environmental pressure, biological systems have developed strong and lightweight peptide-based polymeric materials by using the 20 naturally occurring amino acids as principal monomeric units. These materials outperform their man-made counterparts in the following ways: 1) multifunctionality/tunability, 2) adaptability/stimuli-responsiveness, 3) synthesis and processing under ambient and aqueous conditions, and 4) recyclability and biodegradability. The universal design strategy that affords these advanced properties involves "bottom-up" synthesis and modular, hierarchical organization both within and across multiple length-scales. The field of "biomimicry"-elucidating and co-opting nature's basic material design principles and molecular building blocks-is rapidly evolving. This Review describes what has been discovered about the structure and molecular mechanisms of natural polymeric materials, as well as the progress towards synthetic "mimics" of these remarkable systems. PMID:21898722

Kushner, Aaron M; Guan, Zhibin

2011-09-19

141

LUTE primary mirror materials and design study report  

NASA Technical Reports Server (NTRS)

The major objective of the Lunar Ultraviolet Telescope Experiment (LUTE) Primary Mirror Materials and Design Study is to investigate the feasibility of the LUTE telescope primary mirror. A systematic approach to accomplish this key goal was taken by first understanding the optical, thermal, and structural requirements and then deriving the critical primary mirror-level requirements for ground testing, launch, and lunar operations. After summarizing the results in those requirements which drove the selection of material and the design for the primary mirror are discussed. Most important of these are the optical design which was assumed to be the MSFC baseline (i.e. 3 mirror optical system), telescope wavefront error (WFE) allocations, the telescope weight budget, and the LUTE operational temperature ranges. Mechanical load levels, reflectance and microroughness issues, and options for the LUTE metering structure were discussed and an outline for the LUTE telescope sub-system design specification was initiated. The primary mirror analysis and results are presented. The six material substrate candidates are discussed and four distinct mirror geometries which are considered are shown. With these materials and configurations together with varying the location of the mirror support points, a total of 42 possible primary mirror designs resulted. The polishability of each substrate candidate was investigated and a usage history of 0.5 meter and larger precision cryogenic mirrors (the operational low end LUTE temperature of 60 K is the reason we feel a survey of cryogenic mirrors is appropriate) that were flown or tested are presented.

Ruthven, Greg

1993-01-01

142

The Cam Shell: An Innovative Design With Materials and Manufacturing  

NASA Technical Reports Server (NTRS)

Most of the personal audio and video recording devices currently sold on the open market all require hands to operate. Little consideration was given to designing a hands-free unit. Such a system once designed and made available to the public could greatly benefit mobile police officers, bicyclists, adventurers, street and dirt motorcyclists, horseback riders and many others. With a few design changes water sports and skiing activities could be another large area of application. The cam shell is an innovative design in which an audio and video recording device (such as palm camcorder) is housed in a body-mounted protection system. This system is based on the concept of viewing and recording at the same time. A view cam is attached to a helmet wired to a recording unit encased in a transparent body-mounted protection system. The helmet can also be controlled by remote. The operator will have full control in recording everything. However, the recording unit will be operated completely hands-free. This project will address the design considerations and their effects on material selection and manufacturing. It will enhance the understanding of the structure of materials, and how the structure affects the behavior of the material, and the role that processing play in linking the relationship between structure and properties. A systematic approach to design feasibility study, cost analysis and problem solving will also be discussed.

Chung, W. Richard; Larsen, Frank M.; Kornienko, Rob

2003-01-01

143

Accelerating the design of biomimetic materials by integrating RNA-seq with proteomics and materials science.  

PubMed

Efforts to engineer new materials inspired by biological structures are hampered by the lack of genomic data from many model organisms studied in biomimetic research. Here we show that biomimetic engineering can be accelerated by integrating high-throughput RNA-seq with proteomics and advanced materials characterization. This approach can be applied to a broad range of systems, as we illustrate by investigating diverse high-performance biological materials involved in embryo protection, adhesion and predation. In one example, we rapidly engineer recombinant squid sucker ring teeth proteins into a range of structural and functional materials, including nanopatterned surfaces and photo-cross-linked films that exceed the mechanical properties of most natural and synthetic polymers. Integrating RNA-seq with proteomics and materials science facilitates the molecular characterization of natural materials and the effective translation of their molecular designs into a wide range of bio-inspired materials. PMID:24013196

Guerette, Paul A; Hoon, Shawn; Seow, Yiqi; Raida, Manfred; Masic, Admir; Wong, Fong T; Ho, Vincent H B; Kong, Kiat Whye; Demirel, Melik C; Pena-Francesch, Abdon; Amini, Shahrouz; Tay, Gavin Z; Ding, Dawei; Miserez, Ali

2013-10-01

144

Advanced High Temperature Turbine Seals Materials and Designs  

Microsoft Academic Search

Advanced turbine seal materials and designs are under development to achieve higher temperature capability, extended lifetime and reliability than the state of the art technology. Cooling air consumption, inspection cycles interval and repair costs of aero engines have to be reduced. In the following, results of a program funded by the European Community under the \\

W. Smarsly; N. Zheng; C. S. Buchheim; C. Nindel; C. Silvestro; D. Sporer; M. Tuffs; K. Schreiber; C. Langlade-Bomba; Olaf Andersen; H. Goehler; N. J. Simms; Gordon M. McColvin

2005-01-01

145

AFFORDANCES FOR INTERACTION: THE SOCIAL IS MATERIAL FOR DESIGN  

Microsoft Academic Search

In this article, I explore an ecological approach to social interaction, using the concept of affordances to describe material properties of the environment that affect how people interact. My examples come mainly from the design of technologies that support collaboration. The physical properties of paper and electronic media—for instance electronic mail or video communication system—affects how they can be used

William W. Gaver

1996-01-01

146

Topology design with optimized, self-adaptive materials  

Microsoft Academic Search

Significant performance improvements can be obtained if the topology of an elastic structure is allowed to vary in shape optimization problems. We study the optimal shape design of a two-dimensional elastic continuum for minimum compliance subject to a constraint on the total volume of material. The macroscopic version of this problem is not well-posed if no restrictions are placed on

C. S. Jog; B. Haber; M. P. Bendsoe

1994-01-01

147

Size effect of lattice material and minimum weight design  

NASA Astrophysics Data System (ADS)

The size effects of microstructure of lattice materials on structural analysis and minimum weight design are studied with extented multiscale finite element method (EMsFEM) in the paper. With the same volume of base material and configuration, the structural displacement and maximum axial stress of micro-rod of lattice structures with different sizes of microstructure are analyzed and compared. It is pointed out that different from the traditional mathematical homogenization method, EMsFEM is suitable for analyzing the structures which is constituted with lattice materials and composed of quantities of finite-sized micro-rods. The minimum weight design of structures composed of lattice material is studied with downscaling calculation of EMs-FEM under stress constraints of micro-rods. The optimal design results show that the weight of the structure increases with the decrease of the size of basic sub-unit cells. The paper presents a new approach for analysis and optimization of lattice materials in complex engineering constructions. [Figure not available: see fulltext.

Yan, Jun; Hu, Wen-Bo; Wang, Zhen-Hua; Duan, Zun-Yi

2014-04-01

148

Designing ECM-mimetic materials using protein engineering.  

PubMed

The natural extracellular matrix (ECM), with its multitude of evolved cell-instructive and cell-responsive properties, provides inspiration and guidelines for the design of engineered biomaterials. One strategy to create ECM-mimetic materials is the modular design of protein-based engineered ECM (eECM) scaffolds. This modular design strategy involves combining multiple protein domains with different functionalities into a single, modular polymer sequence, resulting in a multifunctional matrix with independent tunability of the individual domain functions. These eECMs often enable decoupled control over multiple material properties for fundamental studies of cell-matrix interactions. In addition, since the eECMs are frequently composed entirely of bioresorbable amino acids, these matrices have immense clinical potential for a variety of regenerative medicine applications. This brief review demonstrates how fundamental knowledge gained from structure-function studies of native proteins can be exploited in the design of novel protein-engineered biomaterials. While the field of protein-engineered biomaterials has existed for over 20years, the community is only now beginning to fully explore the diversity of functional peptide modules that can be incorporated into these materials. We have chosen to highlight recent examples that either (i) demonstrate exemplary use as matrices with cell-instructive and cell-responsive properties or (ii) demonstrate outstanding creativity in terms of novel molecular-level design and macro-level functionality. PMID:24365704

Cai, Lei; Heilshorn, Sarah C

2014-04-01

149

Optimized Double-Shell Ignition Designs for Various Pusher Materials  

NASA Astrophysics Data System (ADS)

The Lawrence Livermore National Laboratory (LLNL) is pursuing double-shell capsules as a non-cryogenic alternative path to ignition at the National Ignition Facility (NIF). Double-shell capsules consist of high pressure DT gas contained within a small metal pusher or inner shell with an inner radius of 300 to 400 microns. The pusher is supported by low density foam which is held within the ablator or outer shell. There are a number of materials that could be chosen for the pusher shell. It is important to determine which material will lead to the most robust ignition characteristics. It is also important to determine which materials will be easiest to fabricate and to fill with DT fuel. In order to address the issue of which pusher material offers the most robust ignition characteristics, a series of one dimensional numerical optimizations was done. For each choice of pusher material a configuration was found which maximized the calculated yield using the CALEICF code. The calculated yield was not the so-called clean yield but included the negative effects of a one dimensional mix model. This paper presents the results of these optimized double-shell ignition designs for pushers made out of: gold-copper, tungsten, tantalum, platinum-iridium, molybdenum, copper and titanium. Also presented is an analysis of the highest gas pressure that can be safely contained by each pusher material which is then compared with the required DT gas pressure for the double-shell design.

Tipton, Robert; Amendt, Peter; Milovich, Jose

2003-10-01

150

CubeSat Material Limits For Design for Demise  

NASA Technical Reports Server (NTRS)

The CubeSat form factor of nano-satellite (a satellite with a mass between one and ten kilograms) has grown in popularity due to their ease of construction and low development and launch costs. In particular, their use as student led payload design projects has increased due to the growing number of launch opportunities. CubeSats are often deployed as secondary or tertiary payloads on most US launch vehicles or they may be deployed from the ISS. The focus of this study will be on CubeSats launched from the ISS. From a space safety standpoint, the development and deployment processes for CubeSats differ significantly from that of most satellites. For large satellites, extensive design reviews and documentation are completed, including assessing requirements associated with reentry survivability. Typical CubeSat missions selected for ISS deployment have a less rigorous review process that may not evaluate aspects beyond overall design feasibility. CubeSat design teams often do not have the resources to ensure their design is compliant with reentry risk requirements. A study was conducted to examine methods to easily identify the maximum amount of a given material that can be used in the construction of a CubeSats without posing harm to persons on the ground. The results demonstrate that there is not a general equation or relationship that can be used for all materials; instead a limiting value must be defined for each unique material. In addition, the specific limits found for a number of generic materials that have been previously used as benchmarking materials for reentry survivability analysis tool comparison will be discussed.

Kelley, R. L.; Jarkey, D. R.

2014-01-01

151

Design of electro-active polymer gels as actuator materials  

NASA Astrophysics Data System (ADS)

Smart materials, alternatively called active or adaptive, differ from passive materials in their sensing and activation capability. These materials can sense changes in environment such as: electric field, magnetic field, UV light, pH, temperature. They are capable of responding in numerous ways. Some change their stiffness properties (electro-rheological fluids), other deform (piezos, shape memory alloys, electrostrictive materials) or change optic properties (electrochromic polymers). Polymer gels are one of such materials which can change the shape, volume and even optical properties upon different applied stimuli. Due to their low stiffness property they are capable of having up to 100% of strain in a short time, order of seconds. Their motion resembles the one of biosystems, and they are often seen as possible artificial muscle materials. Despite their delicate nature, appropriate design can make them being used as actuator materials which can form controllable surfaces and mechanical switches. In this study several different groups of polymer gel material were investigated: (a) acrylamide based gels are sensitive to pH and electric field and respond in volume change, (b) polyacrylonitrile (PAN) gel is sensitive to pH and electric field and responds in axial strain and bending, (c) polyvinylalcohol (PVA) gel is sensitive to electric field and responds in axial strain and bending and (d) perfluorinated sulfonic acid membrane, Nafion RTM, is sensitive to electric field and responds in bending. Electro-mechanical and chemo-mechanical behavior of these materials is a function of a variety of phenomena: polymer structure, affinity of polymer to the solvent, charge distribution within material, type of solvent, elasticity of polymer matrix, etc. Modeling of this behavior is a task aimed to identify what is driving mechanism for activation and express it in a quantitative way in terms of deformation of material. In this work behavior of the most promising material as an actuator material, Nafion 117, was simulated. It was suggested that dominant phenomenon causing the material deformation is non-uniform water distribution within a material, that causes it to expand on one side and shrink on the other, macroscopically inducing bending of membrane. Uneven distribution of water is believed to be under the influence of two processes, electroosmosis and self-diffusion of free water.

Popovic, Suzana

152

Bioinspiration from fish for smart material design and function  

NASA Astrophysics Data System (ADS)

Fish are a potentially rich source of inspiration for the design of smart materials. Fish exemplify the use of flexible materials to generate forces during locomotion, and a hallmark of fish functional design is the use of body and fin deformation to power propulsion and maneuvering. As a result of nearly 500 million years of evolutionary experimentation, fish design has a number of interesting features of note to materials engineers. In this paper we first provide a brief general overview of some key features of the mechanical design of fish, and then focus on two key properties of fish: the bilaminar mechanical design of bony fish fin rays that allows active muscular control of curvature, and the role of body flexibility in propulsion. After describing the anatomy of bony fish fin rays, we provide new data on their mechanical properties. Three-point bending tests and measurement of force inputs to and outputs from the fin rays show that these fin rays are effective displacement transducers. Fin rays in different regions of the fin differ considerably in their material properties, and in the curvature produced by displacement of one of the two fin ray halves. The mean modulus for the proximal (basal) region of the fin rays was 1.34 GPa, but this varied from 0.24 to 3.7 GPa for different fin rays. The distal fin region was less stiff, and moduli for the different fin rays measured varied from 0.11 to 0.67 GPa. These data are similar to those for human tendons (modulus around 0.5 GPa). Analysis of propulsion using flexible foils controlled using a robotic flapping device allows investigation of the effect of altering flexural stiffness on swimming speed. Flexible foils with the leading edge moved in a heave show a distinct peak in propulsive performance, while the addition of pitch input produces a broad plateau where the swimming speed is relatively unaffected by the flexural stiffness. Our understanding of the material design of fish and the control of tissue stiffness is still in its infancy, and the development of smart materials to assist in investigating the active control of stiffness and in the construction of robotic fish-like devices is a key challenge for the near future.

Lauder, G. V.; Madden, P. G. A.; Tangorra, J. L.; Anderson, E.; Baker, T. V.

2011-09-01

153

Designed amyloid fibers as materials for selective carbon dioxide capture  

PubMed Central

New materials capable of binding carbon dioxide are essential for addressing climate change. Here, we demonstrate that amyloids, self-assembling protein fibers, are effective for selective carbon dioxide capture. Solid-state NMR proves that amyloid fibers containing alkylamine groups reversibly bind carbon dioxide via carbamate formation. Thermodynamic and kinetic capture-and-release tests show the carbamate formation rate is fast enough to capture carbon dioxide by dynamic separation, undiminished by the presence of water, in both a natural amyloid and designed amyloids having increased carbon dioxide capacity. Heating to 100 °C regenerates the material. These results demonstrate the potential of amyloid fibers for environmental carbon dioxide capture.

Li, Dan; Furukawa, Hiroyasu; Deng, Hexiang; Liu, Cong; Yaghi, Omar M.; Eisenberg, David S.

2014-01-01

154

A model for designing functionally gradient material joints  

SciTech Connect

An analytical, thin-plate layer model was developed to assist research and development engineers in the design of functionally gradient material (FGM) joints consisting of discrete steps between end elements of dissimilar materials. Such joints have long been produced by diffusion bonding using intermediates or multiple interlayers; welding, brazing or soldering using multiple transition pieces; and glass-to-glass or glass-to-metal bonding using multiple layers to produce matched seals. More recently, FGM joints produced by self-propagating high-temperature synthesis (SHS) are attracting the attention of researchers. The model calculates temperature distributions and associated thermally induced stresses, assuming elastic behavior, for any number of layers of any thickness or composition, accounting for critically important thermophysical properties in each layer as functions of temperature. It is useful for assuring that cured-in fabrication stresses from thermal expansion mismatches will not prevent quality joint production. The model`s utility is demonstrated with general design cases.

Messler, R.W. Jr.; Jou, M.; Orling, T.T. [Rensselaer Polytechnic Inst., Troy, NY (United States)

1995-05-01

155

Mechanical Design and Material Characterization of the Piezoelectric Energy Harvestor  

NASA Astrophysics Data System (ADS)

This paper is on the proposal of the methodology for the design and fabrication of the piezoelectric energy harvesting devices in viewpoint of the justification both structural and material properties. There has been developing various kinds of energy harvesting techniques using piezoelectric films. Most of them are for the justification of the design or the circuit. The output of the piezoelectric harvester is the product of the material and structural parts. It is, therefore, necessary to justify both of them simultaneously. In this paper cantilever structure was fabricated for the improvement of the power generation in the low frequency region. The resonant frequency and output voltage and charge from the following theory formula were calculated in this study.

Ichiki, M.; Komine, E.; Sueshige, K.; Iimura, K.; Kobayashi, T.; Kitahara, T.; Fujimoto, S.

2013-12-01

156

Rational Design of Pathogen-Mimicking Amphiphilic Materials as Nanoadjuvants  

NASA Astrophysics Data System (ADS)

An opportunity exists today for cross-cutting research utilizing advances in materials science, immunology, microbial pathogenesis, and computational analysis to effectively design the next generation of adjuvants and vaccines. This study integrates these advances into a bottom-up approach for the molecular design of nanoadjuvants capable of mimicking the immune response induced by a natural infection but without the toxic side effects. Biodegradable amphiphilic polyanhydrides possess the unique ability to mimic pathogens and pathogen associated molecular patterns with respect to persisting within and activating immune cells, respectively. The molecular properties responsible for the pathogen-mimicking abilities of these materials have been identified. The value of using polyanhydride nanovaccines was demonstrated by the induction of long-lived protection against a lethal challenge of Yersinia pestis following a single administration ten months earlier. This approach has the tantalizing potential to catalyze the development of next generation vaccines against diseases caused by emerging and re-emerging pathogens.

Ulery, Bret D.; Petersen, Latrisha K.; Phanse, Yashdeep; Kong, Chang Sun; Broderick, Scott R.; Kumar, Devender; Ramer-Tait, Amanda E.; Carrillo-Conde, Brenda; Rajan, Krishna; Wannemuehler, Michael J.; Bellaire, Bryan H.; Metzger, Dennis W.; Narasimhan, Balaji

2011-12-01

157

Rational Design of Pathogen-Mimicking Amphiphilic Materials as Nanoadjuvants  

PubMed Central

An opportunity exists today for cross-cutting research utilizing advances in materials science, immunology, microbial pathogenesis, and computational analysis to effectively design the next generation of adjuvants and vaccines. This study integrates these advances into a bottom-up approach for the molecular design of nanoadjuvants capable of mimicking the immune response induced by a natural infection but without the toxic side effects. Biodegradable amphiphilic polyanhydrides possess the unique ability to mimic pathogens and pathogen associated molecular patterns with respect to persisting within and activating immune cells, respectively. The molecular properties responsible for the pathogen-mimicking abilities of these materials have been identified. The value of using polyanhydride nanovaccines was demonstrated by the induction of long-lived protection against a lethal challenge of Yersinia pestis following a single administration ten months earlier. This approach has the tantalizing potential to catalyze the development of next generation vaccines against diseases caused by emerging and re-emerging pathogens.

Ulery, Bret D.; Petersen, Latrisha K.; Phanse, Yashdeep; Kong, Chang Sun; Broderick, Scott R.; Kumar, Devender; Ramer-Tait, Amanda E.; Carrillo-Conde, Brenda; Rajan, Krishna; Wannemuehler, Michael J.; Bellaire, Bryan H.; Metzger, Dennis W.; Narasimhan, Balaji

2011-01-01

158

Design and engineering analysis of material procurement mobile operation platform  

NASA Astrophysics Data System (ADS)

The material procurement mobile operation platform (MPMOP) consists of six modules, including network operation, truck transportation, remote communication, satellite positioning, power supply and environment regulation. The MPMOP is designed to have six major functions, including online procurement, command control, remote communication, satellite positioning, information management and auxiliary decision. The paper implements an engineering analysis on the MPMOP from three aspects, including transportation transfinite, centroid, and power dissipation.

Ding, H.; Li, J.

2014-03-01

159

Design of nanoscaled materials based on tetraoxa[8]circulene.  

PubMed

Nanotubes and two-dimensional sheet-like compounds containing tetraoxa[8]circulene core units are theoretically predicted. The large cavities with a diameter of 6 Å in the 2D sheets could be useful for hydrogen storage. The designed compounds are predicted to adsorb strongly in the visible region and to be a promising material for nanophotonics because of their electron-donor properties (p-type semiconductors). PMID:24595458

Baryshnikov, Gleb V; Minaev, Boris F; Karaush, Nataliya N; Minaeva, Valentina A

2014-04-14

160

Module Design, Materials, and Packaging Research Team: Activities and Capabilities  

SciTech Connect

Our team activities are directed at improving PV module reliability by incorporating new, more effective, and less expensive packaging materials and techniques. New and existing materials or designs are evaluated before and during accelerated environmental exposure for the following properties: (1) Adhesion and cohesion: peel strength and lap shear. (2) Electrical conductivity: surface, bulk, interface and transients. (3) Water vapor transmission: solubility and diffusivity. (4) Accelerated weathering: ultraviolet, temperature, and damp heat tests. (5) Module and cell failure diagnostics: infrared imaging, individual cell shunt characterization, coring. (6) Fabrication improvements: SiOxNy barrier coatings and enhanced wet adhesion. (7) Numerical modeling: Moisture ingress/egress, module and cell performance, and cell-to-frame leakage current. (8) Rheological properties of polymer encapsulant and sheeting materials. Specific examples will be described.

McMahon, T. J.; del Cueto, J.; Glick, S.; Jorgensen, G.; Kempe, M.; Kennedy, C.; Pern, J.; Terwilliger, K

2005-01-01

161

Design of standards for nondestructive assay of special nuclear material  

SciTech Connect

Nondestructive assay (NDA) of special nuclear material (SNM) involves a variety of measurement techniques, instruments, and nuclear materials. High-quality measurements require well-characterized SNM standards that represent the expected range of mass, chemical composition, and physical properties of the SNM to be measured. Due to the very limited commercial availability of NDA standards, facilities must usually produce their own standards, both to meet their specific measurement needs and to comply with existing regulations. This paper will describe the current extent to which NDA standards are commercially available. The authors will further describe the types of NDA standards used to calibrate and verify the measurement techniques commonly used in the safeguards of SNM. Several types of NDA standards will be discussed in detail to illustrate the considerations that go into specifying and designing traceable, representative standards for materials accounting measurements.

Smith, H.A. Jr.; Stewart, J.E. [Los Alamos National Lab., NM (United States); Ruhter W. [Lawrence Livermore National Lab., CA (United States)

1997-05-01

162

Textile Materials for the Design of Wearable Antennas: A Survey  

PubMed Central

In the broad context of Wireless Body Sensor Networks for healthcare and pervasive applications, the design of wearable antennas offers the possibility of ubiquitous monitoring, communication and energy harvesting and storage. Specific requirements for wearable antennas are a planar structure and flexible construction materials. Several properties of the materials influence the behaviour of the antenna. For instance, the bandwidth and the efficiency of a planar microstrip antenna are mainly determined by the permittivity and the thickness of the substrate. The use of textiles in wearable antennas requires the characterization of their properties. Specific electrical conductive textiles are available on the market and have been successfully used. Ordinary textile fabrics have been used as substrates. However, little information can be found on the electromagnetic properties of regular textiles. Therefore this paper is mainly focused on the analysis of the dielectric properties of normal fabrics. In general, textiles present a very low dielectric constant that reduces the surface wave losses and increases the impedance bandwidth of the antenna. However, textile materials are constantly exchanging water molecules with the surroundings, which affects their electromagnetic properties. In addition, textile fabrics are porous, anisotropic and compressible materials whose thickness and density might change with low pressures. Therefore it is important to know how these characteristics influence the behaviour of the antenna in order to minimize unwanted effects. This paper presents a survey of the key points for the design and development of textile antennas, from the choice of the textile materials to the framing of the antenna. An analysis of the textile materials that have been used is also presented.

Salvado, Rita; Loss, Caroline; Goncalves, Ricardo; Pinho, Pedro

2012-01-01

163

Chalcogenide Glass Radiation Sensor; Materials Development, Design and Device Testing  

SciTech Connect

For many decades, various radiation detecting material have been extensively researched, to find a better material or mechanism for radiation sensing. Recently, there is a growing need for a smaller and effective material or device that can perform similar functions of bulkier Geiger counters and other measurement options, which fail the requirement for easy, cheap and accurate radiation dose measurement. Here arises the use of thin film chalcogenide glass, which has unique properties of high thermal stability along with high sensitivity towards short wavelength radiation. The unique properties of chalcogenide glasses are attributed to the lone pair p-shell electrons, which provide some distinctive optical properties when compared to crystalline material. These qualities are derived from the energy band diagram and the presence of localized states in the band gap. Chalcogenide glasses have band tail states and localized states, along with the two band states. These extra states are primarily due to the lone pair electrons as well as the amorphous structure of the glasses. The localized states between the conductance band (CB) and valence band (VB) are primarily due to the presence of the lone pair electrons, while the band tail states are attributed to the Van der Waalâ??s forces between layers of atoms [1]. Localized states are trap locations within the band gap where electrons from the valence band can hop into, in their path towards the conduction band. Tail states on the other hand are locations near the band gap edges and are known as Urbach tail states (Eu). These states are occupied with many electrons that can participate in the various transformations due to interaction with photons. According to Y. Utsugi et. al.[2], the electron-phonon interactions are responsible for the generation of the Urbach tails. These states are responsible for setting the absorption edge for these glasses and photons with energy near the band gap affect these states. We have studied the effect of x-rays and γ-rays, on thin film chalcogenide glasses and applied them in conjunction with film incorporating a silver source in a new type of radiation sensor for which we have an US patent application [3]. In this report, we give data about our studies regarding our designed radiation sensor along with the testing and performance at various radiation doses. These studies have been preceded by materials characterization research related to the compositional and structural characteristics of the active materials used in the radiation sensor design. During the work on the project, we collected a large volume of material since every experiment was repeated many times to verify the results. We conducted a comprehensive material research, analysis and discussion with the aim to understand the nature of the occurring effects, design different structures to harness these effects, generated models to aid in the understanding the effects, built different device structures and collected data to quantify device performance. These various aspects of our investigation have been detailed in previous quarterly reports. In this report, we present our main results and emphasize on the results pertaining to the core project goals â?? materials development, sensor design and testing and with an emphasis on classifying the appropriate material and design for the optimal application. The report has three main parts: (i) Presentation of the main data; (ii) Bulleted summary of the most important results; (iii) List of the patent, journal publications, conference proceedings and conferences participation, occurring as a result of working on the project.

Mitkova, Maria; Butt, Darryl; Kozicki, Michael; Barnaby, Hugo

2013-04-30

164

TFTR materials issues and problems during design and construction  

NASA Astrophysics Data System (ADS)

TFTR as well as its contemporaries, T15, JT60 and JET, have important contributions to make towards our understanding of plasma conditions In the thermonuclear regime. One of the main objectives of TFTR is to produce fusion power densities approaching those in a fusion reactor, ˜1 Wcm -3, at Q ˜1 - 2. TFTR will be the first tokamak to routinely use deuterium tritium, and produce ˜10 19 fusion neutrons per pulse. With startup of TFTR on December 24, 1982, the demonstration of physics feasibility of "breakeven" is close at hand. Since TFTR performance will be reactor relevant, the capability of materials/components to withstand the hostile effects of a plasma environment will be presented. It is Intended that designers of future fusion devices benefit from the materials technology developments and applications on TFTR. In an attempt to comply with this mandate, this paper will describe TFTR issues on materials, their developments, selections, problems and solutions. Special emphasis will be given, in particular, to the impurity control devices in TFTR, namely, the limiter and surface pumping system located inside the vacuum vessel. The plasma will interact with these components and they will be subjected to disruptions, a vacuum of 10 -6 to 10 -8 torr and a nominal temperatures of <250°C. "Painful" materials development problems encountered will be reviewed, as well as important "lessons learned." A briefing on the materials of construction will be given, with some comments on the problems that developed and their solutions.

Sabado, M.; Little, R.

1984-05-01

165

46 CFR 160.133-23 - Procedure for approval of design, material, or construction change.  

Code of Federal Regulations, 2013 CFR

...for approval of design, material, or construction change. 160.133-23 Section...SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND...for approval of design, material, or construction change. (a) Each change in...

2013-10-01

166

46 CFR 160.156-23 - Procedure for approval of design, material, or construction change.  

Code of Federal Regulations, 2013 CFR

...for approval of design, material, or construction change. 160.156-23 Section...SECURITY (CONTINUED) EQUIPMENT, CONSTRUCTION, AND MATERIALS: SPECIFICATIONS AND...for approval of design, material, or construction change. (a) Each change in...

2013-10-01

167

Design Molecular Recognition Materials for Chiral Sensors, Separtations and Catalytic Materials  

SciTech Connect

The goal is the development of materials that are highly sensitive and selective for chid chemicals and biochemical (such as insecticides, herbicides, proteins, and nerve agents) to be used as sensors, catalysts and separations membranes. Molecular modeling methods are being used to tailor chiral molecular recognition sites with high affinity and selectivity for specified agents. The work focuses on both silicate and non-silicate materials modified with chirally-pure fictional groups for the catalysis or separations of enantiomerically-pure molecules. Surfactant and quaternary amine templating is being used to synthesize porous frameworks, containing mesopores of 30 to 100 angstroms. Computer molecukw modeling methods are being used in the design of these materials, especially in the chid surface- modi~ing agents. Molecular modeling is also being used to predict the catalytic and separations selectivities of the modified mesoporous materials. The ability to design and synthesize tailored asymmetric molecular recognition sites for sensor coatings allows a broader range of chemicals to be sensed with the desired high sensitivity and selectivity. Initial experiments target the selective sensing of small molecule gases and non-toxic model neural compounds. Further efforts will address designing sensors that greatly extend the variety of resolvable chemical species and forming a predictive, model-based method for developing advanced sensors.

Jia, S.; Nenoff, T.M.; Provencio, P.; Qiu, Y.; Shelnutt, J.A.; Thoma, S.G.; Zhang, J.

1998-11-01

168

System design for safe robotic handling of nuclear materials  

SciTech Connect

Robotic systems are being developed by the Intelligent Systems and Robotics Center at Sandia National Laboratories to perform automated handling tasks with radioactive nuclear materials. These systems will reduce the occupational radiation exposure to workers by automating operations which are currently performed manually. Because the robotic systems will handle material that is both hazardous and valuable, the safety of the operations is of utmost importance; assurance must be given that personnel will not be harmed and that the materials and environment will be protected. These safety requirements are met by designing safety features into the system using a layered approach. Several levels of mechanical, electrical and software safety prevent unsafe conditions from generating a hazard, and bring the system to a safe state should an unexpected situation arise. The system safety features include the use of industrial robot standards, commercial robot systems, commercial and custom tooling, mechanical safety interlocks, advanced sensor systems, control and configuration checks, and redundant control schemes. The effectiveness of the safety features in satisfying the safety requirements is verified using a Failure Modes and Effects Analysis. This technique can point out areas of weakness in the safety design as well as areas where unnecessary redundancy may reduce the system reliability.

Drotning, W.; Wapman, W.; Fahrenholtz, J.; Kimberly, H.; Kuhlmann, J.

1996-03-01

169

Material challenges for transducer designers in the 21st century  

NASA Astrophysics Data System (ADS)

The modern U.S. Navy is rapidly evolving to meet the challenges of operating in the littorals. This focus changes the rules, especially to the designers of sonar systems that now need to aggressively engage quiet diesel electric submarine threats and neutralize sophisticated underwater mines. These new responsibilities dictate that new concepts be developed. To meet these new demands on the sonar system, transducer designers are being tasked to design transducers and to utilize new materials to address performance requirements that were never even imagined a decade ago. Sensor needs are no longer limited to pressure types but now have to sense velocity or acceleration. Sources are challenged to both frequency extent and power levels. The need to physically move sources off of submarines and surface combatants and onto vehicles with limited energy capabilities prompt the challenge of efficient bandwidth and high coupling. These are the needs of the 'next Navy'; the needs of the 'Navy after next' will present an even more demanding scenario. The future will demand revolutionary technology at the micro level with devices utilizing new power sources and new materials.

Lindberg, Jan F.

2002-07-01

170

Test model designs for advanced refractory ceramic materials  

NASA Technical Reports Server (NTRS)

The next generation of space vehicles will be subjected to severe aerothermal loads and will require an improved thermal protection system (TPS) and other advanced vehicle components. In order to ensure the satisfactory performance system (TPS) and other advanced vehicle materials and components, testing is to be performed in environments similar to space flight. The design and fabrication of the test models should be fairly simple but still accomplish test objectives. In the Advanced Refractory Ceramic Materials test series, the models and model holders will need to withstand the required heat fluxes of 340 to 817 W/sq cm or surface temperatures in the range of 2700 K to 3000 K. The model holders should provide one dimensional (1-D) heat transfer to the samples and the appropriate flow field without compromising the primary test objectives. The optical properties such as the effective emissivity, catalytic efficiency coefficients, thermal properties, and mass loss measurements are also taken into consideration in the design process. Therefore, it is the intent of this paper to demonstrate the design schemes for different models and model holders that would accommodate these test requirements and ensure the safe operation in a typical arc jet facility.

Tran, Huy Kim

1993-01-01

171

30 CFR 36.20 - Quality of material, workmanship, and design.  

Code of Federal Regulations, 2013 CFR

...Quality of material, workmanship, and design. 36.20 Section 36.20 Mineral...TRANSPORTATION EQUIPMENT Construction and Design Requirements § 36.20 Quality of material, workmanship, and design. (a) MSHA will test only...

2013-07-01

172

46 CFR 128.230 - Penetrations of hulls and watertight bulkheads-materials and pressure design.  

Code of Federal Regulations, 2013 CFR

...watertight bulkheads-materials and pressure design. 128.230 Section 128.230 Shipping...EQUIPMENT AND SYSTEMS Materials and Pressure Design § 128.230 Penetrations of hulls...watertight bulkheadsâmaterials and pressure design. (a) Each piping...

2013-10-01

173

30 CFR 27.20 - Quality of material, workmanship, and design.  

Code of Federal Regulations, 2013 CFR

...Quality of material, workmanship, and design. 27.20 Section 27.20 Mineral...METHANE-MONITORING SYSTEMS Construction and Design Requirements § 27.20 Quality of material, workmanship, and design. (a) MSHA will test only...

2013-07-01

174

46 CFR 128.220 - Class II non-vital systems-materials and pressure design.  

Code of Federal Regulations, 2013 CFR

...non-vital systems-materials and pressure design. 128.220 Section 128.220 ...AND SYSTEMS Materials and Pressure Design § 128.220 Class II non-vital systemsâmaterials and pressure design. (a) Except as provided...

2013-10-01

175

36 CFR 401.5 - Control and supervision of materials, design, and building.  

Code of Federal Regulations, 2013 CFR

...Control and supervision of materials, design, and building. 401.5 Section 401.5 Parks...Control and supervision of materials, design, and building. The Commission controls the design and prescribes regulations for the...

2013-07-01

176

Testing and design life analysis of polyurea liner materials  

NASA Astrophysics Data System (ADS)

Certainly, water pipes, as part of an underground infrastructure system, play a key role in maintaining quality of life, health, and wellbeing of human kind. As these potable water pipes reach the end of their useful life, they create high maintenance costs, loss of flow capacity, decreased water quality, and increased dissatisfaction. There are several different pipeline renewal techniques available for different applications, among which linings are most commonly used for the renewal of water pipes. Polyurea is a lining material applied to the interior surface of the deteriorated host pipe using spray-on technique. It is applied to structurally enhance the host pipe and provide a barrier coating against further corrosion or deterioration. The purpose of this study was to establish a relationship between stress, strain and time. The results obtained from these tests were used in predicting the strength of the polyurea material during its planned 50-year design life. In addition to this, based on the 10,000 hours experimental data, curve fitting and Findley power law models were employed to predict long-term behavior of the material. Experimental results indicated that the tested polyurea material offers a good balance of strength and stiffness and can be utilized in structural enhancement applications of potable water pipes.

Ghasemi Motlagh, Siavash

177

Functional graded material design in PCVD single-mode fiber  

NASA Astrophysics Data System (ADS)

Quartz optical fiber or preform is composed of core and cladding with different refractive index (RI). Their compositions are different from the core to cladding in order to acquire desired RI profile. The physical properties from core to cladding are different, such as thermal expansion coefficients, thermal capacity and glass transition temperatures, which have much effect on the properties of optical fiber. The material composition and structure in PCVD single mode (SM) fiber was introduced in this paper. The composition of PCVD SM fiber was SiO2-GeO2-F-(Cl). F acted as a water-getter to reduce water peak besides lowering the RI of quartz glass and GeO2-F co-deposition was adopted in PCVD fiber. The functional graded material (FGM) design in PCVD SM fiber, which can reduce the attenuation, PMD, splicing loss and improve microbending resistance, was analyzed and discussed.

Han, Qingrong; Zhao, Xiujian; Zhang, Shuqiang; Luo, Jie

2005-11-01

178

Computational materials design for bulk heterojunction solar cells  

NASA Astrophysics Data System (ADS)

The adapted Su-Schrieffer-Heeger Hamiltonian is further developed in this work to predict the optical bandgaps of more than 200 different ?-conjugated systems. Insights on the structure-property relationship of these ?-conjugated systems lead to guiding rules for new photovoltaic materials design. A copolymer of parallel and perpendicular benzodithiophenes, differing only in sulfur atom locations, is proposed as a candidate to achieve the optimal 1.2 eV donor optical gap for organic photovoltaics. The charge transfer mechanisms and the exciton and charge carrier mobilities are computed and compared for various bulk-heterojunction structures to improve the overall power convention efficiency.

Lin, Xi; Shin, Yongwoo

2013-03-01

179

Taguchi method of experimental design in materials education  

NASA Technical Reports Server (NTRS)

Some of the advantages and disadvantages of the Taguchi Method of experimental design as applied to Materials Science will be discussed. This is a fractional factorial method that employs the minimum number of experimental trials for the information obtained. The analysis is also very simple to use and teach, which is quite advantageous in the classroom. In addition, the Taguchi loss function can be easily incorporated to emphasize that improvements in reproducibility are often at least as important as optimization of the response. The disadvantages of the Taguchi Method include the fact that factor interactions are normally not accounted for, there are zero degrees of freedom if all of the possible factors are used, and randomization is normally not used to prevent environmental biasing. In spite of these disadvantages it is felt that the Taguchi Method is extremely useful for both teaching experimental design and as a research tool, as will be shown with a number of brief examples.

Weiser, Martin W.

1993-01-01

180

Connecting drug delivery reality to smart materials design.  

PubMed

Inflated claims to both design and mechanistic novelty in drug delivery and imaging systems, including most nanotechnologies, are not supported by the generally poor translation of these systems to clinical efficacy. The "form begets function" design paradigm is seductive but perhaps over-simplistic in translation to pharmaceutical efficacy. Most innovations show few clinically important distinctions in their therapeutic benefits in relevant preclinical disease and delivery models, despite frequent claims to the contrary. Long-standing challenges in drug delivery issues must enlist more realistic, back-to-basics approaches to address fundamental materials properties in complex biological systems, preclinical test beds, and analytical methods to more reliably determine fundamental pharmaceutical figures of merit, including drug carrier purity and batch-batch variability, agent biodistribution, therapeutic index (safety), and efficacy. PMID:23624177

Grainger, David W

2013-09-15

181

Hybrid materials science: a promised land for the integrative design of multifunctional materials.  

PubMed

For more than 5000 years, organic-inorganic composite materials created by men via skill and serendipity have been part of human culture and customs. The concept of "hybrid organic-inorganic" nanocomposites exploded in the second half of the 20th century with the expansion of the so-called "chimie douce" which led to many collaborations between a large set of chemists, physicists and biologists. Consequently, the scientific melting pot of these very different scientific communities created a new pluridisciplinary school of thought. Today, the tremendous effort of basic research performed in the last twenty years allows tailor-made multifunctional hybrid materials with perfect control over composition, structure and shape. Some of these hybrid materials have already entered the industrial market. Many tailor-made multiscale hybrids are increasingly impacting numerous fields of applications: optics, catalysis, energy, environment, nanomedicine, etc. In the present feature article, we emphasize several fundamental and applied aspects of the hybrid materials field: bioreplication, mesostructured thin films, Lego-like chemistry designed hybrid nanocomposites, and advanced hybrid materials for energy. Finally, a few commercial applications of hybrid materials will be presented. PMID:24866174

Nicole, Lionel; Laberty-Robert, Christel; Rozes, Laurence; Sanchez, Clément

2014-06-21

182

Hybrid materials science: a promised land for the integrative design of multifunctional materials  

NASA Astrophysics Data System (ADS)

For more than 5000 years, organic-inorganic composite materials created by men via skill and serendipity have been part of human culture and customs. The concept of ``hybrid organic-inorganic'' nanocomposites exploded in the second half of the 20th century with the expansion of the so-called ``chimie douce'' which led to many collaborations between a large set of chemists, physicists and biologists. Consequently, the scientific melting pot of these very different scientific communities created a new pluridisciplinary school of thought. Today, the tremendous effort of basic research performed in the last twenty years allows tailor-made multifunctional hybrid materials with perfect control over composition, structure and shape. Some of these hybrid materials have already entered the industrial market. Many tailor-made multiscale hybrids are increasingly impacting numerous fields of applications: optics, catalysis, energy, environment, nanomedicine, etc. In the present feature article, we emphasize several fundamental and applied aspects of the hybrid materials field: bioreplication, mesostructured thin films, Lego-like chemistry designed hybrid nanocomposites, and advanced hybrid materials for energy. Finally, a few commercial applications of hybrid materials will be presented.

Nicole, Lionel; Laberty-Robert, Christel; Rozes, Laurence; Sanchez, Clément

2014-05-01

183

Materials Design for Joinable, High Performance Aluminum Alloys  

NASA Astrophysics Data System (ADS)

An aluminum alloy compatible with friction stir welding is designed for automotive and aerospace structural applications. Current weldable automotive aluminum alloys do not possess the necessary strength to meet safety standards and therefore are not able to replace steel in the automotive body. Significant weight savings could be achieved if steel components are replaced with aluminum. Current aerospace alloys are not weldable, requiring machining of large pieces that are then riveted together. If an aerospace alloy could be friction stir welded, smaller pieces could be welded, reducing material waste. Using a systems approach for materials design, property goals are set from performance objectives. From previous research and computational predictions, a structure is designed for a prototype alloy containing dynamic precipitates to readily dissolve and re-precipitate and high stability precipitates to resist dissolution and coarsening in the weld region. It is found that a Ag modified Al-3.9Mg-0.04Cu (at. %) alloy enhanced the rate and magnitude of hardening during ageing, both beneficial effects for dynamic precipitation. In the same alloy, ageing at 350°C results in hardening from Al 3(Sc,Zr) precipitates. Efforts to effectively precipitate both populations simultaneously are unsuccessful. The Al3(Sc,Zr) precipitation hardened prototype is friction stir processed and no weak zones are found in the weld hardness profile. An aerospace alloy design is proposed, utilizing the dual precipitate structure shown in the prototype. The automotive alloy is designed using a basic strength model with parameters determined from the initial prototype alloy analysis. After ageing to different conditions, the alloy is put through a simulated heat affected zone thermal cycle with a computer controlled induction heater. The aged samples lose hardness from the weld cycle but recover hardness from a post weld heat treatment. Atom probe tomography and transmission electron microscopy are used to characterize the composition, size, and phase fraction evolution for the automotive alloy strengthening precipitates. It is determined that the dominant precipitate at peak hardness is a metastable T' phase. The automotive alloy is friction stir processed and found to lose hardness in the heat affected zones surrounding the nugget. A post weld heat treatment nearly recovers the heat affected zones to base hardness. The post weld heat treatment is compatible with the current automotive paint bake step, showing design for processability. Tensile tests confirm the base alloy strength meets the automotive strength goal.

Glamm, Ryan James

184

Designing intermediate-range order in amorphous materials.  

PubMed

Amorphous materials are commonly understood to consist of random organizations of molecular-type structural units. However, it has long been known that structural organizations intermediate between discrete chemical bonds and periodic crystalline lattices are present even in liquids. Numerous models--including random networks and crystalline-type structures with networks composed of clusters and voids--have been proposed to account for this intermediate-range order. Nevertheless, understanding and controlling structural features that determine intermediate-range order in amorphous materials remain fundamental, yet presently unresolved, issues. The most characteristic signature of such order is the first peak in the total structure factor, referred to as the first sharp diffraction peak or 'low Q' structure. These features correspond to large real-space distances in the materials, and understanding their origin is key to unravelling details of intermediate-range order. Here we employ principles of crystal engineering to design specific patterns of intermediate-range order within amorphous zinc-chloride networks. Using crystalline models, we demonstrate the impact of various structural features on diffraction at low values of Q. Such amorphous network engineering is anticipated to provide the structure/property relationships necessary to tailor specific optical, electronic and mechanical properties. PMID:12353031

Martin, James D; Goettler, Stephen J; Fossé, Nathalie; Iton, Lennox

2002-09-26

185

Optimal Design of Honeycomb Material Used to Mitigate Head Impact  

PubMed Central

This paper presents a study of the impact resistance of honeycomb structure with the purpose to mitigate impact forces. The objective is to aid in the choice of optimal parameters to minimize the thickness of the honeycomb structure while providing adequate protection to prevent injury due to head impact. Studies are presented using explicit finite element analysis representing the case of an unprotected drop of a rigid impactor onto a simulated floor consisting of vinyl composition tile and concrete. Analysis of honeycomb material to reduce resulting accelerations is also presented where parameters such as honeycomb material modulus, wall thickness, cell geometry and structure depth are compared to the unprotected case. A simplified analysis technique using a genetic algorithm is presented to demonstrate the use of this method to select a minimum honeycomb depth to achieve a desired acceleration level at a given level of input energy. It is important to select a minimum material depth in that smaller dimensions lead toward more aesthetic design that increase the likelihood of that the device is used.

Caccese, Vincent; Ferguson, James R.; Edgecomb, Michael

2013-01-01

186

Designing functionally graded materials with superior load-bearing properties  

PubMed Central

Ceramic prostheses often fail from fracture and wear. We hypothesize that these failures may be substantially mitigated by an appropriate grading of elastic modulus at the ceramic surface. In this study, we elucidate the effect of elastic modulus profile on the flexural damage resistance of functionally graded materials (FGMs), providing theoretical guidlines for designing FGM with superior load-bearing property. The Young's modulus of the graded structure is assumed to vary in a power-law relation with a scaling exponent n; this is in accordance with experimental observations from our laboratory and elsewhere. Based on the theory for bending of graded beams, we examine the effect of n value and bulk-to-surface modulus ratio (Eb/Es) on stress distribution through the graded layer. Theory predicts that a low exponent (0.15 < n < 0.5), coupled with a relatively small modulus ratio (3 < Eb/Es < 6), is most desirable for reducing the maximum stress and transferring it into the interior, while keeping the surface stress low. Experimentally, we demonstrate that elastically graded materials with various n values and Eb/Es ratios can be fabricated by infiltrating alumina and zirconia with a low-modulus glass. Flexural tests show that graded alumina and zirconia with suitable values of these parameters exhibit superior load-bearing capacity, 20% to 50% higher than their homogeneous counterparts. Improving load-bearing capacity of ceramic materials could have broad impacts on biomedical, civil, structural, and an array of other engineering applications.

Zhang, Yu; Sun, Ming-jie; Zhang, Denzil

2011-01-01

187

Process design of press hardening with gradient material property influence  

NASA Astrophysics Data System (ADS)

Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

Neugebauer, R.; Schieck, F.; Rautenstrauch, A.

2011-05-01

188

Process design of press hardening with gradient material property influence  

SciTech Connect

Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

Neugebauer, R. [Fraunhofer Institute for Machine Tools and Forming Technology IWU, Chemnitz (Germany); Professorship for Machine Tools and Forming Technology, TU Chemnitz (Germany); Schieck, F. [Fraunhofer Institute for Machine Tools and Forming Technology IWU, Chemnitz (Germany); Rautenstrauch, A. [Professorship for Machine Tools and Forming Technology, TU Chemnitz (Germany)

2011-05-04

189

Representing product personality in relation to materials in a product design problem  

Microsoft Academic Search

The materials a product is made of play a major role in the user's product experiences. In design research nowadays more attention is given to these qualities of materials, besides the ongoing research on technical aspects of materials. How product designers take decisions about materials is one of the topics of research in this field. Decisions on materials play a

Ilse van Kesteren

190

Design and synthesis of novel resist materials for EUVL  

NASA Astrophysics Data System (ADS)

The design, synthesis and characterization of non-chemically amplified negative tone electron-beam and EUV resists based on the inclusion of a radiation sensitive sulfonium functional group are outlined.. MAPDST (4-(methacryloyloxy phenyldimethylsulfoniumtriflate) and MANTMS (1-(4-(methacryloyloxy)naphthalen-1-yl)tetrahydro-1H thiopheniumtrifluoromethane sulfonate) monomers each containing the sulfonium group underwent homo- and copolymerizations using free radical polymerization with 2,2'-azobisisobutyronitrile (AIBN) initiator. These resist materials were evaluated by EB lithography using 20 keV electron beam and EUV lithography to obtain sub-20 nm line patterns. These features were optimized ranging from resist coating, pre-exposure bake, exposure to e-beam, postexposure bake, development and imaging. Our investigation showed that these newly synthesized resists are potential viable candidates for EUV lithography based on their ability to form flaw free thin films < 50nm, sensitivity, resolution and LER control.

Satyanarayana, V. S. V.; Singh, Vikram; Ghosh, Subrata; Sharma, Satinder; Gonsalves, Kenneth E.

2014-04-01

191

Interfacial Properties and Design of Functional Energy Materials  

SciTech Connect

The vital importance of energy to society continues to demand a relentless pursuit of energy responsive materials that can bridge fundamental chemical structures at the molecular level and achieve improved functionality, such as efficient energy conversion/storage/transmission, over multiple length scales. This demand can potentially be realized by harnessing the power of self-assembly a spontaneous process where molecules or much larger entities form ordered aggregates as a consequence of predominately non-covalent (weak) interactions. Self-assembly is the key to bottom-up design of molecular devices, because the nearly atomic-level control is very difficult to realize in a top-down, e.g., lithographic approach. However, while function (e.g., charge mobility) in simple systems such as single crystals can often be predicted, predicting the function of the great variety of self-assembled molecular architectures is complicated by the lack of understanding and control over nanoscale interactions, mesoscale architectures, and macroscale (long-range) order. To establish a foundation toward delivering practical solutions, it is critical to develop an understanding of the chemical and physical mechanisms responsible for the self-assembly of molecular and hybrid materials on various substrates. Typically molecular self-assembly involves poorly understood non-covalent intermolecular and substrate-molecule interactions compounded by local and/or collective influences from the substrate atomic lattice (symmetry and/or topological features) and electronic structure. Thus, progress towards unraveling the underlying physicochemical processes that control the structure and macroscopic physical, mechanical, electrical, and transport properties of materials increasingly requires tight integration of theory, modeling and simulation with precision synthesis, advanced experimental characterization, and device measurements. In this mode, theory and simulation can greatly accelerate the process of materials discovery by providing atomic level understanding of physicochemical phenomena and for making predictions of trends. In particular, this approach can provide understanding, prediction and exploration of new materials and conditions before they are realized in the lab, to illuminate connections between experimental observations, and help identify new materials for targeted synthesis. Toward this end, Density Functional Theory (DFT) can provide a suitable computational framework for investigating the inter- and intramolecular bonding, molecular conformation, charge and spin configurations that are intrinsic to self-assembly of molecules on substrates. This Account highlights recent advances in using an integrated approach based on DFT and scanning probe microscopy [STM(s), AFM] to study/develop electronic materials formed from the self-assembly of molecules into supramolecular or polymeric architectures on substrates. Here it is the interplay between molecular interactions and surface electrons that is used to control the final architecture and subsequent bulk properties of the two-dimensional patterns/assemblies. Indeed a rich variety of functional energy materials become possible.

Sumpter, Bobby G [ORNL] [ORNL; Liang, Liangbo [ORNL] [ORNL; Nicolai, Adrien [Rensselaer Polytechnic Institute (RPI)] [Rensselaer Polytechnic Institute (RPI); Meunier, V. [Rensselaer Polytechnic Institute (RPI)] [Rensselaer Polytechnic Institute (RPI)

2014-01-01

192

Materials Design based on Predictive Ab Initio Thermodynamics  

NASA Astrophysics Data System (ADS)

A key requirement in developing predictive multi-scale modeling is the availability of accurate computational tools determining energies not only at T = 0 K but also under realistic conditions, i.e., at finite temperature. Combining accurate first principles calculations with mesoscopic/macroscopic thermodynamic and/or kinetic concepts allows now to address this issue and to determine free energies and derived thermodynamic quantities such as heat capacity, thermal expansion coefficients, and elastic constants with an accuracy that matches and often even rivals available experimental data. In the talk a brief overview of the fundamentals and recent developments of combining modern fully parameter-free ab initio methods with thermodynamic concepts will be given with special emphasize on structural materials. The flexibility and the predictive power of these approaches and the impact they can have in developing new strategies in materials design will be discussed e.g. for modern high strength TWIP/TRIP steels, for understanding failure mechanisms such as hydrogen embrittlement, or for identifying chemical trends in the performance of light weight metallic alloys. Work has been done in collaboration with Fritz Kormann, Blazej Grabowski, and Tilmann Hickel.

Neugebauer, Joerg

2013-03-01

193

Designing functionally graded materials with superior load-bearing properties.  

PubMed

Ceramic prostheses often fail from fracture and wear. We hypothesize that these failures may be substantially mitigated by an appropriate grading of elastic modulus at the ceramic surface. In this study, we elucidate the effect of elastic modulus profile on the flexural damage resistance of functionally graded materials (FGMs), providing theoretical guidelines for designing FGMs with superior load-bearing property. The Young's modulus of the graded structure is assumed to vary in a power-law relation with a scaling exponent n; this is in accordance with experimental observations from our laboratory and elsewhere. Based on the theory for bending of graded beams, we examine the effect of n value and bulk-to-surface modulus ratio (E(b)/E(s)) on stress distribution through the graded layer. Theory predicts that a low exponent (0.15materials with various n values and E(b)/E(s) ratios can be fabricated by infiltrating alumina and zirconia with a low-modulus glass. Flexural tests show that graded alumina and zirconia with suitable values of these parameters exhibit superior load-bearing capacity, 20-50% higher than their homogeneous counterparts. Improving load-bearing capacity of ceramic materials could have broad impacts on biomedical, civil, structural, and an array of other engineering applications. PMID:22178651

Zhang, Yu; Sun, Ming-Jie; Zhang, Denzil

2012-03-01

194

Mechanical design of mussel byssus: material yield enhances attachment strength  

PubMed

The competitive dominance of mussels in the wave-swept rocky intertidal zone is in part due to their ability to maintain a secure attachment. Mussels are tethered to the substratum by a byssus composed of numerous extracellular, collagenous threads secreted by the foot. Each byssal thread has three serially arranged parts: a corrugated proximal region, a smooth distal region and an adhesive plaque. This study examines the material and structural properties of the byssal threads of three mussel species: Mytilus californianus, M. trossulus, and M. galloprovincialis. Tensile tests in general reveal similar material properties among species: the proximal region has a lower initial modulus, a lower ultimate stress and a higher ultimate strain than the distal region. The distal region also yields at a stress well below its ultimate value. In whole thread tests, the proximal region and adhesive plaque are common sites of structural failure and are closely matched in strength, while the distal region appears to be excessively strong. We propose that the high strength of the distal region is the byproduct of a material designed to yield and extend before structural failure occurs. Experimental and theoretical evidence is presented suggesting that thread yield and extensibility provide two important mechanisms for increasing the overall attachment strength of the mussel: (1) the reorientation of threads towards the direction of applied load, and (2) the 'recruitment' of more threads into tension and the consequent distribution of applied load over a larger cross-sectional area, thereby reducing the stress on each thread. This distal region yield behavior is most striking for M. californianus and may be a key to its success in extreme wave-swept environments. PMID:9318809

Bell; Gosline

1996-01-01

195

Conceptual design report: Nuclear materials storage facility renovation. Part 1, Design concept. Part 2, Project management  

SciTech Connect

The Nuclear Materials Storage Facility (NMSF) at the Los Alamos National Laboratory (LANL) was a Fiscal Year (FY) 1984 line-item project completed in 1987 that has never been operated because of major design and construction deficiencies. This renovation project, which will correct those deficiencies and allow operation of the facility, is proposed as an FY 97 line item. The mission of the project is to provide centralized intermediate and long-term storage of special nuclear materials (SNM) associated with defined LANL programmatic missions and to establish a centralized SNM shipping and receiving location for Technical Area (TA)-55 at LANL. Based on current projections, existing storage space for SNM at other locations at LANL will be loaded to capacity by approximately 2002. This will adversely affect LANUs ability to meet its mission requirements in the future. The affected missions include LANL`s weapons research, development, and testing (WRD&T) program; special materials recovery; stockpile survelliance/evaluation; advanced fuels and heat sources development and production; and safe, secure storage of existing nuclear materials inventories. The problem is further exacerbated by LANL`s inability to ship any materials offsite because of the lack of receiver sites for mate rial and regulatory issues. Correction of the current deficiencies and enhancement of the facility will provide centralized storage close to a nuclear materials processing facility. The project will enable long-term, cost-effective storage in a secure environment with reduced radiation exposure to workers, and eliminate potential exposures to the public. This document provides Part I - Design Concept which describes the selected solution, and Part II - Project Management which describes the management system organization, the elements that make up the system, and the control and reporting system.

NONE

1995-07-14

196

EXPERIMENTAL STUDIES ON PARTICLE IMPACTION AND BOUNCE: EFFECTS OF SUBSTRATE DESIGN AND MATERIAL. (R825270)  

EPA Science Inventory

This paper presents an experimental investigation of the effects of impaction substrate designs and material in reducing particle bounce and reentrainment. Particle collection without coating by using combinations of different impaction substrate designs and surface materials was...

197

Eutectics as improved pharmaceutical materials: design, properties and characterization.  

PubMed

Eutectics are a long known class of multi-component solids with important and useful applications in daily life. In comparison to other multi-component crystalline solids, such as salts, solid solutions, molecular complexes and cocrystals, eutectics are less studied in terms of molecular structure organization and bonding interactions. Classically, a eutectic is defined based on its low melting point compared to the individual components. In this article, we attempt to define eutectics not just based on thermal methods but from a structural organization view point, and discuss their microstructures and properties as organic materials vis-a-vis solid solutions and cocrystals. The X-ray crystal structure of a cocrystal is different from that of the individual components whereas the unit cell of a solid solution is similar to that of one of the components. Eutectics are closer to the latter species in that their crystalline arrangement is similar to the parent components but they are different with respect to the structural integrity. A solid solution possesses structural homogeneity throughout the structure (single phase) but a eutectic is a heterogeneous ensemble of individual components whose crystal structures are like discontinuous solid solutions (phase separated). Thus, a eutectic may be better defined as a conglomerate of solid solutions. A structural analysis of cocrystals, solid solutions and eutectics has led to an understanding that materials with strong adhesive (hetero) interactions between the unlike components will lead to cocrystals whereas those having stronger cohesive (homo/self) interactions will more often give rise to solid solutions (for similar structures of components) and eutectics (for different structures of components). We demonstrate that the same crystal engineering principles which have been profitably utilized for cocrystal design in the past decade can now be applied to make eutectics as novel composite materials, illustrated by stable eutectics of the hygroscopic salt of the anti-tuberculosis drug ethambutol as a case study. A current gap in the characterization of eutectic microstructure may be fulfilled through pair distribution function (PDF) analysis of X-ray diffraction data, which could be a rapid signature technique to differentiate eutectics from their components. PMID:24322207

Cherukuvada, Suryanarayan; Nangia, Ashwini

2014-01-28

198

Design and characterization of novel ?-cyclodextrin based copolymer materials.  

PubMed

Reported herein are the systematic design and characterization of several novel polyurethane (PU) copolymers containing a macrocyclic porogen (?-cyclodextrin; ?-CD). These copolymers were synthesized from the reaction between ?-CD with different types of diisocyanate linker molecules (e.g., 1,6-hexamethylene diisocyanate (HDI), 4,4'-dicyclohexylmethane diisocyanate (CDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,4-phenylene diisocyanate (PDI) and 1,5-naphthalene diisocyanate (NDI)) at variable synthetic conditions. The copolymers were characterized using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), solid state (13)C CP-MAS NMR, (1)H/(13)C solution NMR spectroscopy, thermogravimetric analysis (TGA) and elemental analyses (CHN). The PU copolymers were generally insoluble in water and the optimal preparation of copolymer materials for sorption-based applications is for ?-CD/linker synthetic mole ratios from 1:1 to 1:3. The practical upper limit of the crosslink density (approximately 1:7, ?-CD/linker) depends on the steric bulk of the cross linker units. PMID:21172695

Mohamed, Mohamed H; Wilson, Lee D; Headley, John V

2011-02-01

199

Design of liquid-crystalline electronic functional materials through nanosegregation  

NASA Astrophysics Data System (ADS)

Conventional liquid-crystalline (LC) semiconductors have been molecules consisting of a ?-conjugated moiety and alkyl chains. For example, phenylterthiophene derivatives bearing alkyl chains exhibit ordered smectic phase at room temperature and are applied to field-effect transistors. In this paper, we report a molecular designs of LC electronic materials based on nanosegregation. Terthiophene derivatives bearing an imdazolium moiety exhibit supremolecular smectic phases, in which hole- and ion-conductive layers are formed separately. In the LC phase, electrochrmism is observed under the application of a DC bias without any electrolyte solutions. In simple side-chain LC polysiloxanes bearing terthiophene pendant groups, suprastructures based on nanosegregation are observed. The presence of flexible sublayers consisting of the polysiloxane backbones can relax the applied strain and decrease defect density, resulting in high hole mobility on the order of 10-2 cm2/Vs. For perylene tetracarboxylic bisimide (PTCBI) derivatives bearing oligosiloxane chains, nanosegregation between the rigid aromatic cores and flexible oligosiloxane chains promotes the formation of columnar and layer structures, in which efficient electron transport is observed. The electron mobility in the columnar phase of the PTCBI derivative bearing four trisiloxane chains exceeds 10-3 cm2/Vs at room temperature.

Funahashi, Masahiro

2012-10-01

200

Materials design of substrates for gas adsorption and storage  

NASA Astrophysics Data System (ADS)

All the three chapters in the thesis are originated from the efforts of hydrogen storage, although the metal stabilization can be beyond that. It is well known that hydrogen storage is the bottleneck problem of a grand hydrogen economy, but its notorious low volumetric density creates an overwhelming challenge in storage. Materials-based storage might make it possible to store large quantities of hydrogen in small volume at practical temperature and pressure. However, the actual experiments are hard to perform and even to explain the results, which gives computer simulations a big chance to investigate the storage. In this thesis, I use the Density Functional Theory based software to explore the new materials. A brief introduction of DFT theoretical background is given in the first chapter. In Chapter 2, we study how to prevent the metal atoms from aggregating. In nature, low-coordinated metal atoms can provide new opportunities for gas storage and catalysis when they are exposed to their environment. But unfortunately, they are generally unstable against aggregation. We demonstrate that electron deficiency in an sp2 carbon layer, induced by heavy (but realistic) boron doping, can stabilize sparse metal layers (Be, Mg, Sc and Ti) against aggregation thermodynamically. If the atomically dispersed metals are not thermodynamically favored, take Pd as an example, local inhomogeneities in boron density will create large kinetic barriers against aggregation, so Pd layer can be kinetically stable. In Chapter 3, we first introduce the two new classes of materials. The compelling Ammonia Boron based materials used for chemical storage attract interests because of their high hydrogen content, but the overly stable products seriously eliminate any possibility of reversible storage. On the other hand, the organic frameworks exhibit strong structural stability and accessibility. Almost all of the atoms are on the surface. These amazing properties look like exclusively being tailored for the hydrogen release in one of the products, PAB polymer. We combine the advantages of the polymer and framework, then design four series of frame-works. They are proven stable through molecular dynamics simulations. Chapter 4 is focused on the essential issue of hydrogen applications: the release kinetics. We present a novel idea to tune the activation barrier by coupling the polymer with an external framework spring, and then apply it to the simple PAB -- PAB/H2 transformation. Our results for planar polymer transformations show that this coupling indeed change both the hydrogen binding energy EB and its release barrier DeltaEK, although the lowest barrier by this tuning is still too large. When the polymer is compressed, the EB and DeltaEK are lowered; when the polymer is stretched, the EB and DeltaEK are raised. Finally, we test a non-planar transformation and achieve a great improvement in DeltaEK, so the non-planar polymer transformation might be an much more effective way in hydrogen release.

Huang, Zhaohui

201

Trade Designations of Plastics and Related Materials (Revised).  

National Technical Information Service (NTIS)

A compilation of approximately 9000 trademarks and brand names of plastics, elastomers, adhesives and related materials together with a short description of the material and the name of the manufacturer are presented for identification purposes. Omitted f...

J. B. Titus

1978-01-01

202

New Generation Photonics Materials: Design, Development, Characterization, and Applications.  

National Technical Information Service (NTIS)

Significant research achievements have been accomplished in development of multi-photon active materials and applications as well as of novel nanocomposites materials for opt-electronic technology. The specific research progress achieved by this grant sup...

G. S. He P. N. Prasad

2007-01-01

203

A Web-based Computer-Aided Material-Selection System for Aircraft Design  

Microsoft Academic Search

A web-based computer-aided material-selection system for aircraft design, together with its architecture and implementation details, is put forward. Furthermore, a prototype of this system is developed and the prototype's effectiveness is demonstrated by an aircraft-design material-selection case in actual applications. This system can help designer select suitable materials for airframe, provide knowledge for inexperienced engineer and accumulate enterprise-level material-selection expertise.

Yuanpei Lan; Zhidong Guan; Qixiang Jiao; Guangxing Xu

2010-01-01

204

Materials design for sustainability through life cycle modeling of engineered cementitious composites  

Microsoft Academic Search

Evaluating and enhancing construction material sustainability requires a life cycle perspective of the structures in which\\u000a they are used, since material properties and durability can have a profound effect on overall infrastructure performance.\\u000a A framework is proposed to evaluate and enhance the design of “greener” materials that integrates material design, structural\\u000a design, and life cycle modeling of the built system.

Alissa Kendall; Gregory A. Keoleian; Michael D. Lepech

2008-01-01

205

A demonstration of simple airfoils: Structural design and materials choices  

SciTech Connect

An educational unit is presented for building and evaluating simple wing structures, in order to learn about materials choice and lightweight construction. This unit is appropriate for a high school materials science class or lower-division college courses in structural engineering, materials science, or aeronautical engineering.

Bunnell, L.R. (Pacific Northwest Lab., Richland, WA (United States)); Piippo, S.W. (Richland School District, WA (United States))

1993-01-01

206

DESIGNING FOR MATERIAL SEPARATION: LESSONS FROM AUTOMOTIVE RECYCLING  

Microsoft Academic Search

Virtually all of the material in today's automobiles can technically be recycled. The challenge facing engineers is making this recycling process economical, especially for materials in such components as seats and instrument panels. Recycling these components requires the different materials to be separated so that each can be recycled individually. This separation can be accomplished either manually, where workers disassembly

Stewart Coulter; Bert Bras; Gerald Winslow; Susan Yester

1996-01-01

207

Material design of ceramic coating by plasma spray method  

Microsoft Academic Search

In the ceramic coating on substrate, cracking and peeling occur due to the difference of thermal expansion between substrate material and coating material. For evaluation of peeling property of plasma sprayed coating, it is demanded that thermal properties of plasma sprayed coating are estimated in detail. In this study, the results of comparison of thermal properties between bulk material and

Masaru Nakamichi; Takeshi Takabatake; Hiroshi Kawamura

1998-01-01

208

Designing metallic materials from abundant resources for more efficient utilization  

Microsoft Academic Search

Metallic materials are a good example of what might be termed a demand driven technology. Less frequently, materials with unusual properties provide an opportunity for new applications, e.g., an opportunity seeking technology. High performance fiber composites are the most recent example. The recent threats of materials shortages, particularly chromium, nickel and cobalt, have prompted consideration of substitutions and alloys based

Robert I. Jaffee

1976-01-01

209

Design and evaluation of lost circulation materials for severe environments  

SciTech Connect

An independent analysis of lost circulation materials for geothermal applications has been completed using unique laboratory tools developed for the purpose. Test results of commercial materials as well as mathematical models for evaluating their performance are presented. Physical attributes that govern the performance of lost circulation materials are identified and correlated with test results. 9 refs., 27 figs., 4 tabs.

Loeppke, G.E.; Glowka, D.A.; Wright, E.K.

1988-01-01

210

Design of activating digital learning material for food chemistry education  

Microsoft Academic Search

A complete set of digital exercises for introductory Food Chemistry has been developed. The major function of the exercises is to promote active acquisition of food chemistry knowledge. This paper describes the design process and the result of the design process. Design guidelines and requirements were derived, based on theories about cognitive load, motivation and active learning. The digital exercises

Julia DIEDEREN; Harry GRUPPEN; R. J. M. Hartog; Gerard MOERLAND; Alphons G. J. VORAGEN

2003-01-01

211

Optimal design: Theory and applications to materials and structures  

Microsoft Academic Search

This all new book presents cutting edge technical information on latest advances in the field of optimal design. The book provides invaluable information from Russian activity in the field of optimal structural design. It covers the relatively recent topic of developing a consistent theory of optimal design. The maturity of modern composite technology has led, in part, to this development,

V. V. Vasiliev; Z. Guerdal

1998-01-01

212

Design of materials with extreme thermal expansion using a three-phase topology optimization method  

Microsoft Academic Search

We show how composites with extremal or unusual thermal expansion coefficients can be designed using a numerical topology optimization method. The composites are composed of two different material phases and void. The optimization method is illustrated by designing materials having maximum thermal expansion, zero thermal expansion, and negative thermal expansion. Assuming linear elasticity, it is shown that materials with effective

Ole Sigmund; Salvatore Torquato

1997-01-01

213

Functionally Graded Designer Viscoelastic Materials Tailored to Perform Prescribed Tasks with Probabilistic Failures and Lifetimes  

SciTech Connect

Protocols are developed for formulating optimal viscoelastic designer functionally graded materials tailored to best respond to prescribed loading and boundary conditions. In essence, an inverse approach is adopted where material properties instead of structures per se are designed and then distributed throughout structural elements. The final measure of viscoelastic material efficacy is expressed in terms of failure probabilities vs. survival time000.

Hilton, Harry H. [Aerospace Engineering Department, Technology Research, Education and Commercialization Center, National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, 104 South Wright Street, MC-236 Urbana, IL 61801-2935 (United States)

2008-02-15

214

Manufacturing process and material selection in concurrent collaborative design of MEMS devices  

Microsoft Academic Search

In this paper we present knowledge of an intensive approach and system for selecting suitable manufacturing processes and materials for microelectromechanical systems (MEMS) devices in concurrent collaborative design environment. In the paper, fundamental issues on MEMS manufacturing process and material selection such as concurrent design framework, manufacturing process and material hierarchies, and selection strategy are first addressed. Then, a fuzzy

Xuan F. Zha; H. Du

2003-01-01

215

Role of dislocation theory in the design of engineering materials  

SciTech Connect

The science of materials development has progressed to a stage in which it is possible to compose a recipe for new materials. The recipe has three steps: given a desirable set of properties and material constraints, one identifies a composition and microstructure to achieve them; given a desirable composition and microstructure, one identifies a processing sequence to achieve them; given a trial alloy, one conducts analytical testing to identify its shortcomings and overcomes them. In effecting each stage of this recipe, it is usually necessary to be aware of and understand the role of the dislocations which determine material properties, define material microstructure, and control its evolution. The role of dislocations is discussed. The text contains examples of particular alloy development efforts, and suggestions for research in dislocation theory which might contribute to the solution of significant problems in materials development.

Morris, J.W. Jr.

1980-06-01

216

[Molecular design of polymeric materials for biotechnology and medicine].  

PubMed

This review describes new polymer materials for biomedical applications developed in the Polymers for Biology Laboratory of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences. These include composite rigid sorbents for biochromatography, polymer dispersions for immunoassay, polymer hydrogels for immobilization of enzymes and cells, and polymer ultra thin films as biomembrane models and materials for biosensors. Some general and specific properties of these new materials and models as well as examples of their applications are discussed. PMID:10645492

Zubov, V P; Ivanov, A E; Zhigis, L S; Rapoport, E M; Markvicheva, E A; Lukin, Iu V; Za?tsev, S Iu

1999-11-01

217

Technologists Talk: Making the Links between Design, Problem-Solving and Experiences with Hard Materials  

ERIC Educational Resources Information Center

Design and problem-solving is a key learning focus in technology education and remains a distinguishing factor that separates it from other subject areas. This research investigated how two expert designers considered experiences with hard materials contributed to their learning design and problem-solving with these materials. The research project…

Potter, Patricia

2013-01-01

218

Integrated Facility Layout And Material Handling System Design In Semiconductor Fabrication Facilities  

Microsoft Academic Search

Semiconductor manufacturing is an important component of the US manufacturing industry. Most oftoday's fabrication facilities and those being designed for the near future use a bay layout configuration andan overhead monorail system for moving material between bays. These material handling systems areusually designed with a spine or perimeter type of configuration. This paper investigates the layout andmaterial handling system design

Brett A. Peters; Taho Yang

1995-01-01

219

MODELLING, DESIGN AND ANALYSIS OF A TESTING RIG FOR COMPOSITE MATERIALS  

Microsoft Academic Search

Composite materials are increasingly utilized in many conventional and unconventional applications in mechanical and industrial fields. Extensive research is performed in this area, especially at international level (§ 1). Both design of component and design of material develop in a parallel way, so reliable composite characterisation represents a fundamental objective to be achieved. Aims of this paper are design, modelling,

Gianni Caligiana; Alfredo Liverani; Stefano Pippa

220

46 CFR 128.240 - Hydraulic or pneumatic power and control-materials and pressure design.  

Code of Federal Regulations, 2013 CFR

...power and control-materials and pressure design. 128.240 Section 128.240 Shipping...EQUIPMENT AND SYSTEMS Materials and Pressure Design § 128.240 Hydraulic or pneumatic power and controlâmaterials and pressure design. (a) Each standard piping...

2013-10-01

221

Enclosed mechanical seal face design for brittle materials{copyright}  

Microsoft Academic Search

Metal carbides are widely used as seal face material due to their hardness and wear resistance. Silicon carbide (SiC) has excellent performance as a seal face material, but it is relatively brittle and may break due to accidental overloads outside the boundary of normal operating conditions. In mechanical seals for nuclear primary coolant pumps, the shattered SiC pieces can get

Marsi

1994-01-01

222

Optimal shape design as a material distribution problem  

Microsoft Academic Search

Shape optimization in a general setting requires the determination of the optimal spatial material distribution for given loads and boundary conditions. Every point in space is thus a material point or a void and the optimization problem is a discrete variable one. This paper describes various ways of removing this discrete nature of the problem by the introduction of a

M. P. Bendsøe

1989-01-01

223

Material and design considerations for the carbon armored ITER divertor  

NASA Astrophysics Data System (ADS)

The properties of materials for the carbon armored ITER divertor were evaluated from literature and manufacturers' documentation. Most of these data, however, have been not known or not published yet. We have evaluated an optimum data set of the candidate materials of the ITER divertor, which were needed for finite element analyses (FEM). The materials evaluated are as follows; MFC-1, CX2002U, SEP-N112, P-130, IG-430U for the carbon based materials, and Oxygen Free Copper (OFCu), Dispersion Strengthened Copper (DSCu), TZM, W5Re and W-Cu as a heat sink material. It should be noted that W-Cu is first proposed for a heat sink application of the ITER divertor plate. The finite element analyses were performed for the residual stress induced by brazing, thermal response and thermal stresses under a uniform heat flux of 15 MW/sq m to the plasma facing surface. The stress free temperature of 750 C is assumed for the residual stress by brazing. Ten different geometries of the divertor were considered in the analyses including possible material combinations. The FEM results show that the material combinations of MFC-1 and W-30Cu or DSUc in the flat-plate geometry satisfy the presently accepted ITER requirements. The combinations of CX2002U and TZM or W5Re is considered a good choice in terms of residual and thermal stresses, whereas the surface temperature exceeds the ITER requirements.

Smid, I.; Akiba, Masato; Araki, Masanori; Suzuki, Satoshi; Satoh, Kazuyoshi

1993-07-01

224

Engineer Design Tests of Modified Dust-Control Materials and Prototype Equipment.  

National Technical Information Service (NTIS)

Engineer design tests were performed on a dust-control system, i.e. materials and prototype emplacement equipment. The performance of the dust-control material exceeded the criteria of the currently existent Qualitative Materiel Requirement. The liquid di...

M. M. Culpepper R. Osmond

1973-01-01

225

Preliminary Design of a Galactic Cosmic Ray Shielding Materials Testbed for the International Space Station.  

National Technical Information Service (NTIS)

The preliminary design of a testbed to evaluate the effectiveness of galactic cosmic ray (GCR) shielding materials, the MISSE Radiation Shielding Testbed (MRSMAT) is presented. The intent is to mount the testbed on the Materials International Space Statio...

E. A. Sechkar J. R. Gaier S. Berkebile S. R. Panko

2012-01-01

226

Non-Destructive Inspection and Relationships to Aircraft Design and Materials.  

National Technical Information Service (NTIS)

Because the existence of poor communications and limited rate of integration among materials technologists, design engineers and NDI experts was realized by AGARD, the Structures and Materials Panel took the initiative of organizing a Specialists Meeting ...

1978-01-01

227

System Design for a Continuous Progress School: Part III the Instructional Materials Center.  

National Technical Information Service (NTIS)

This document presents a design for the Instructional Materials Center (IMC) for a Continuous Progress School. The IMC, as conceived, combines the functions of the library, bookstore, audiovisual center, and materials development. (Author)

R. L. Egbert J. F. Cogswell D. G. Ryans

1964-01-01

228

Mechanical design engineering. NASA/university advanced design program: Lunar Bulk Material Transport Vehicle  

NASA Astrophysics Data System (ADS)

The design of a Lunar Bulk Material Transport Vehicle (LBMTV) is discussed. Goals set in the project include a payload of 50 cubic feet of lunar soil with a lunar of approximately 800 moon-pounds, a speed of 15 mph, and the ability to handle a grade of 20 percent. Thermal control, an articulated steering mechanism, a dump mechanism, a self-righting mechanism, viable power sources, and a probable control panel are analyzed. The thermal control system involves the use of small strip heaters to heat the housing of electronic equipment in the absence of sufficient solar radiation and multi-layer insulation during periods of intense solar radiation. The entire system uses only 10 W and weighs about 60 pounds, or 10 moon-pounds. The steering mechanism is an articulated steering joint at the center of the vehicle. It utilizes two actuators and yields a turning radius of 10.3 feet. The dump mechanism rotates the bulk material container through an angle of 100 degree using one actuator. The self-righting mechanism consists of two four bar linkages, each of which is powered by the same size actuator as the other linkages. The LBMTV is powered by rechargeable batteries. A running time of at least two hours is attained under a worst case analysis. The weight of the batteries is 100 pounds. A control panel consisting of feedback and control instruments is described. The panel includes all critical information necessary to control the vehicle remotely. The LBMTV is capable of handling many types of cargo. It is able to interface with many types of removable bulk material containers. These containers are made to interface with the three-legged walker, SKITTER. The overall vehicle is about 15 feet in length and has a weight of about 1000 pounds, or 170 lunar pounds.

Daugherty, Paul; Griner, Stewart; Hendrix, Alan; Makarov, Chris; Martiny, Stephen; Meyhoefer, Douglas Ralph; Platt, Cody Claxton; Sivak, John; Wheeler, Elizabeth Fitch

1988-06-01

229

Design of Meta-Materials Outside the Homogenization Limit Using Multiscale Analysis and Topology Optimization  

NASA Astrophysics Data System (ADS)

The field of meta-materials engineering has largely expanded mechanical design possibilities over the last two decades; some notable design advances include the systematic engineering of negative Poisson's ratio materials and functionally graded materials, materials designed for optimal electronic and thermo-mechanical performances, and the design of materials under uncertainty. With these innovations, the systematic engineering of materials for design-specific uses is becoming more common in industrial and military uses. The motivation for this body of research is the design of the shear beam for a non-pneumatic wheel. Previously, a design optimization of a finite element model of the non-pneumatic wheel was completed, where a linear elastic material was simulated in the shear beam to reduce hysteretic energy losses. As part of the optimization, a set of optimal orthotropic material properties and other geometric properties were identified for the shear beam. Given that no such natural linear elastic material exists, a meta-material can be engineered that meets these properties using the aforementioned tools. However, manufacturing constraints prevent the use of standard homogenization analysis and optimization tools in the engineering of the shear beam due to limitations in the accuracy of the homogenization process for thin materials. In this research, the more general volume averaging analysis is shown to be an accurate tool for meta-material analysis for engineering thin-layered materials. Given an accurate analysis method, several optimization formulations are proposed, and optimality conditions are derived to determine the most mathematically feasible and numerically reliable formulation for topology optimization of a material design problem using a continuous material interpolation over the design domain. This formulation is implemented to engineer meta-materials for problems using the volume averaging analysis, which includes the use of variable linking and the derivation of first-order design sensitivities to increase computational efficiency. Inspired by honeycomb materials, a new method of discretizing the material design domain into unit cells with non-simple connectivity is proposed as a way of increasing the solution space of the topology optimization problem. Finally, these methods are used in the meta-material design process to identify several candidate meta-material geometries from a polycarbonate base material for the shear layer of the non-pneumatic wheel; notable geometries include an 'x'-like geometry, a bent column-like geometry identified previously as a bristle, and, remarkably, an auxetic honeycomb geometry. This is the first reported result demonstrating the auxetic honeycomb geometry to be a minimum weight structure in shear loading where a general topology optimization method was used.

Czech, Christopher

230

Using Results from Performance-Based Test Methods for Material Flammability in Fire Safety Engineering Design  

Microsoft Academic Search

In order to be able to apply performance design procedures with regard to material flammability in building design, a comprehensive and coherent philosophy on material reaction-to-fire must be developed. This paper gives a general discussion on performance-based design and performance-based test methods for material flammability. A number of end-use scenarios and critical conditions are discussed. The dominant physical mechanisms leading

Bjorn Karlsson; Greg North; Daniel Gojkovic

2002-01-01

231

MINIMIZING THE ENVIRONMENTAL IMPACT OF CONSTRUCTION MATERIALS IN PLAYGROUND DESIGN  

EPA Science Inventory

We are a playground design team at Louisiana State University that has been involved with playground design projects for the past seven years. Playgrounds are extremely important to society because they promote the physical, mental, and social well being of children. ...

232

Curriculum Development, Design, Specification and Assessment and Supplemental Materials.  

ERIC Educational Resources Information Center

This document consists of a workshop presentation on curriculum development, design, specification, and assessment in the engineering classroom. Ten sessions focus on: (1) the format and purpose of the workshop, which is designed to help instructors develop an understanding of the basic principles of curriculum and instruction and the ability to…

McNeill, Barry W.; Bellamy, Lynn

233

Evaluation of Material Design Limits for TBM Applications  

Microsoft Academic Search

The aim of the work presented is, firstly, an evaluation of existing design rules considered for austenitic steels exhibiting hardening cycle by cycle contrary to the reduced activation ferritic-martensitic steels (RAFM), which soften under cyclic loading. Secondly, it is a definition of the range of operation temperatures and loads for the current design of the test blanket module (TBM). Results

R. Sunyk; J. Aktaa

2005-01-01

234

Packaging Materials and Design for Improved PV Module Reliability.  

National Technical Information Service (NTIS)

A number of candidate alternative encapsulant and soft backsheet materials have been evaluated in terms of their suitability for photovoltaic (PV) module packaging applications. Relevant properties, including peel strength as a function of damp heat expos...

G. Jorgensen K. Terwilliger M. Kempe J. Perm S. Glick

2005-01-01

235

First Materials Science Research Rack Capabilities and Design Features  

NASA Technical Reports Server (NTRS)

The first Materials Science Research Rack (MSRR-1) will accommodate dual Experiment Modules (EM's) and provide simultaneous on-orbit processing operations capability. The first international Materials Science Experiment Module for the MSRR-1 is an international cooperative research activity between NASA's Marshall Space Flight Center (MSFC) and the European Space Agency's (ESA) European Space Research and Technology Center. (ESTEC). This International Standard Payload Rack (ISPR) will contain the Materials Science Laboratory (MSL) developed by ESA as an Experiment Module. The MSL Experiment Module will accommodate several on-orbit exchangeable experiment-specific Module Inserts. Module Inserts currently planned are a Quench Module Insert, Low Gradient Furnace, Solidification with Quench Furnace, and Diffusion Module Insert. The second Experiment Module for the MSRR-1 configuration is a commercial device supplied by MSFC's Space Products Department (SPD). It includes capabilities for vapor transport processes and liquid metal sintering. This Experiment Module will be replaced on-orbit with other NASA Materials Science EMs.

Schaefer, D.; King, R.; Cobb, S.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

236

Thermoelectric Materials Evaluation Program Spring Design to Minimize Load Relaxation.  

National Technical Information Service (NTIS)

The recommended spring material for use in thermoelectric modules is either Inconel x or Elgiloy based on their excellent performance and availability. The stress level for generator applications is 75,000 psi. (ERA citation 05:027470)

F. R. Grimm

1980-01-01

237

Trade Designations of Plastics and Related Materials (Revised).  

National Technical Information Service (NTIS)

A compilation of approximately 5100 trademarks and brand names of plastics and related materials together with a short description of the item and the name of the manufacturer are presented for identification purposes. Omitted from the listing are trade d...

J. B. Titus

1970-01-01

238

Design of Geopolymeric Materials Based on Nanostructural Characterization and Modeling.  

National Technical Information Service (NTIS)

Geopolymers, a class of largely X-ray amorphous aluminosilicate binder materials, have been studied extensively over the past several decades, but largely from an empirical standpoint. The primary aim of this investigation has been to apply a more science...

G. C. Lukey J. S. van Deventer J. L. Provis P. Duxson

2006-01-01

239

First Materials Science Research Facility Rack Capabilities and Design Features  

Microsoft Academic Search

The first Materials Science Research Rack (MSRR-1) is the primary facility for U.S. sponsored materials science research on the International Space Station. MSRR-1 is contained in an International Standard Payload Rack (ISPR) equipped with the Active Rack Isolation System (ARIS) for the best possible microgravity environment. MSRR-1 will accommodate dual Experiment Modules and provide simultaneous on-orbit processing operations capability. The

S. D. Cobb; D. B. Higgins; L. Kitchens

2002-01-01

240

Design, synthesis, and characterization of new materials for thermoelectric applications  

Microsoft Academic Search

Currently, the best known material for thermoelectric refrigeration at room temperature is and alloy of Bi2Te3 and Sb 2Te3. This material has been the basis for room temperature thermoelectric cooling for over 40 years, but its low cooling efficiency (≈10% of Carnot Efficiency) has limited its adaptation to small-market specialty applications. Since Bi2Te3 and its alloys have been studied so

Thomas Kent Reynolds

2003-01-01

241

Advanced computational research in materials processing for design and manufacturing  

NASA Astrophysics Data System (ADS)

Advanced mathematical techniques and computer simulation play a major role in providing enhanced understanding of conventional and advanced materials processing operations. Development and application of mathematical models and computer simulation techniques can provide a quantitative understanding of materials processes and will minimize the need for expensive and time consuming trial- and error-based product development. As computer simulations and materials databases grow in complexity, high performance computing and simulation are expected to play a key role in supporting the improvements required in advanced material syntheses and processing by lessening the dependence on expensive prototyping and re-tooling. Many of these numerical models are highly compute-intensive. It is not unusual for an analysis to require several hours of computational time on current supercomputers despite the simplicity of the models being studied. For example, to accurately simulate the heat transfer in a 1-cu m block using a simple computational method requires 10(exp 12) arithmetic operations per second of simulated time. For a computer to do the simulation in real time would require a sustained computation rate 1000 times faster than that achievable by current supercomputers. Massively parallel computer systems, which combine several thousand processors able to operate concurrently on a problem are expected to provide orders of magnitude increase in performance. This paper briefly describes advanced computational research in materials processing at ORNL. Continued development of computational techniques and algorithms utilizing the massively parallel computers will allow the simulation of conventional and advanced materials processes in sufficient generality.

Zacharia, T.

242

Bioreceptivity evaluation of cementitious materials designed to stimulate biological growth.  

PubMed

Ordinary Portland cement (OPC), the most used binder in construction, presents some disadvantages in terms of pollution (CO2 emissions) and visual impact. For this reason, green roofs and façades have gain considerable attention in the last decade as a way to integrate nature in cities. These systems, however, suffer from high initial and maintenance costs. An alternative strategy to obtain green facades is the direct natural colonisation of the cementitious construction materials constituting the wall, a phenomenon governed by the bioreceptivity of such material. This work aims at assessing the suitability of magnesium phosphate cement (MPC) materials to allow a rapid natural colonisation taking carbonated OPC samples as a reference material. For that, the aggregate size, the w/c ratio and the amount of cement paste of mortars made of both binders were modified. The assessment of the different bioreceptivities was conducted by means of an accelerated algal fouling test. MPC samples exhibited a faster fouling compared to OPC samples, which could be mainly attributed to the lower pH of the MPC binder. In addition to the binder, the fouling rate was governed by the roughness and the porosity of the material. MPC mortar with moderate porosity and roughness appears to be the most feasible material to be used for the development of green concrete walls. PMID:24602907

Manso, Sandra; De Muynck, Willem; Segura, Ignacio; Aguado, Antonio; Steppe, Kathy; Boon, Nico; De Belie, Nele

2014-05-15

243

Design and Construction of Aquaculture Facilities in Dredged Material Containment Areas.  

National Technical Information Service (NTIS)

Aquaculture as a multiple use of dredged material containment areas (DMCA) has been investigated by the Containment Area Aquaculture Program (CAAP). This report describes design and construction of aquaculture pond facilities in DMCA, reviews design, cons...

J. Homziak C. D. Veal

1993-01-01

244

Report on the Possible Benefits of Using High-Temperature Superconductor Materials in Particle Accelerator Design.  

National Technical Information Service (NTIS)

This report discusses different design concepts for particle beam accelerators. It demonstrates that with the use of high temperature superconducting materials, a more compact, lighter, and more robust accelerator design can be realized for the space base...

B. Balko L. Cohen R. Collins

1988-01-01

245

Application of interactive design as teaching materials for learning disabled students  

Microsoft Academic Search

This study focuses on how to design teaching materials for learning disabled students. User-friendly and user-centred interface design are the basic rules. In this study, we understand different needs from different learning disabled students, then design and made customer-made teaching materials, it is discussed to explicate why the design worked well and how it can be improved on different case

Chien-Yu Lin; Chih-feng Lee; E. Chang; Jie-Ying Chen; Rain Chen; Yin-Yin Chang; Kai-Ping Yang

2010-01-01

246

New Materials Design Through Friction Stir Processing Techniques  

SciTech Connect

Friction Stir Welding (FSW) has reached a large interest in the scientific community and in the last years also in the industrial environment, due to the advantages of such solid state welding process with respect to the classic ones. The complex material flow occurring during the process plays a fundamental role in such solid state welding process, since it determines dramatic changes in the material microstructure of the so called weld nugget, which affects the effectiveness of the joints. What is more, Friction Stir Processing (FSP) is mainly being considered for producing high-strain-rate-superplastic (HSRS) microstructure in commercial aluminum alloys. The aim of the present research is the development of a locally composite material through the Friction Stir Processing (FSP) of two AA7075-T6 blanks and a different material insert. The results of a preliminary experimental campaign, carried out at the varying of the additional material placed at the sheets interface under different conditions, are presented. Micro and macro observation of the such obtained joints permitted to investigate the effects of such process on the overall joint performance.

Buffa, G.; Fratini, L. [Dipartimento di Tecnologia Meccanica, Produzione e Ingegneria Gestionale, Universita di Palermo, Viale delle Scienze 90128 Palermo (Italy); Shivpuri, R. [Ohio State University, Department of Industrial, Welding and Systems Engineering, 1971 Neil Avenue, 210 Baker Systems, Columbus, Ohio 43210 (United States)

2007-04-07

247

New Materials Design Through Friction Stir Processing Techniques  

NASA Astrophysics Data System (ADS)

Friction Stir Welding (FSW) has reached a large interest in the scientific community and in the last years also in the industrial environment, due to the advantages of such solid state welding process with respect to the classic ones. The complex material flow occurring during the process plays a fundamental role in such solid state welding process, since it determines dramatic changes in the material microstructure of the so called weld nugget, which affects the effectiveness of the joints. What is more, Friction Stir Processing (FSP) is mainly being considered for producing high-strain-rate-superplastic (HSRS) microstructure in commercial aluminum alloys. The aim of the present research is the development of a locally composite material through the Friction Stir Processing (FSP) of two AA7075-T6 blanks and a different material insert. The results of a preliminary experimental campaign, carried out at the varying of the additional material placed at the sheets interface under different conditions, are presented. Micro and macro observation of the such obtained joints permitted to investigate the effects of such process on the overall joint performance.

Buffa, G.; Fratini, L.; Shivpuri, R.

2007-04-01

248

Microstructure Optimization in Fuel Cell Electrodes using Materials Design  

SciTech Connect

Abstract A multiscale model based on statistical continuum mechanics is proposed to predict the mechanical and electrical properties of heterogeneous porous media. This model is applied within the framework of microstructure sensitive design (MSD) to guide the design of the microstructure in porous lanthanum strontium manganite (LSM) fuel cell electrode. To satisfy the property requirement and compatibility, porosity and its distribution can be adjusted under the guidance of MSD to achieve optimized microstructure.

Li, Dongsheng; Saheli, Ghazal; Khaleel, Mohammad A.; Garmestani, Hamid

2006-08-01

249

Thermoelectric Materials Evaluation Program Spring Design to Minimize Load Relaxation.  

National Technical Information Service (NTIS)

The objective of the spring relaxation study was to find a spring material whose fabrication technique and operating stress level would limit the spring relaxation to an acceptable amount over a period of 50,000 hours in a thermoelectric generator environ...

1980-01-01

250

Fissile material storage vaults: Designing to enhance safety and efficiency  

Microsoft Academic Search

There are several, sometimes conflicting, interests which must be accommodated in fissile material, storage vaults. These include criticality safety, radiation safety, fire protection, accountability, and safeguards in addition to the operational requirements of efficiency and, for automated vaults, reliability. A combination of these factors coupled with increasing demands on available vault space and the desire to minimize on-site transportation of

1987-01-01

251

Unravelling Porous Asphalt Concrete, Towards a Mechanistic Material Design Tool  

Microsoft Academic Search

PA (Porous Asphalt Concrete) is the standard surfacing material for the Dutch primary road network. More than 70% of this network is surfaced with PA. Ravelling, the loss of stone from the road surface, is in most cases by far decisive for PA service life. Ravelling resistance is mainly generated by the PA mixture performance and not by the pavement's

M. Huurman; L. T. Mo; M. F. Woldekidan

2009-01-01

252

Design of new frictional testing machine for shallow fault materials  

Microsoft Academic Search

Subduction thrust faults at shallow depth mainly consist of granular and clay-rich materials which strengths are influenced by the presence of pore water. Dilatation and pore pressure generation of fault zones by the dynamic friction will increase the volumetric water content in fault zone, which can assist the fault weakening by acoustic fluidization or hydrodynamic lubrication mechanism. Therefore the evaluation

O. Tadai; W. Tanikawa; T. Hirose; M. Sakaguchi; W. Lin

2009-01-01

253

Photovoltaic module encapsulation design and materials section, volume 2  

NASA Technical Reports Server (NTRS)

Tests for chemical structure, material properties, water absorption, aging and curing agent of Ethylene Vinyl Acetate (EVA) and UV absorption studies are carried out. A computer model was developed for thermal optical modeling, to investigate dependence between module operating temperature and solar insolation, and heat dissapation behavior. Structural analyses were performed in order to determine the stress distribution under wind and heat conditions. Curves are shown for thermal loading conditions. An electrical isolation was carried out to investigate electrical stress aging of non-metallic encapsulation materials and limiting material flaws, and to develop a computer model of electrical fields and stresses in encapsulation materials. In addition, a mathematical model was developed and tests were conducted to predict hygroscopic and thermal expansion and contraction on a plastic coated wooden substrate. Thermal cycle and humidity freezing cycle tests, partial discharge tests, and hail impact tests were also carried out. Finally, the effects of soiling on the surface of photovoltaic modules were investigated. Two antisoiling coatings, a fluorinated silane and perflourodecanoic acid were considered.

Cuddihy, E. F.

1984-01-01

254

NANOSTRUCTURED MATERIAL DESIGN FOR HG, AS, AND SE CAPTURE  

EPA Science Inventory

The goal of this research project is to identify potential materials that can be used as multipollutant sorbents using a hierarchy of computational modeling approaches. Palladium (Pd) and gold (Au) alloys were investigated and the results show that the addition of a small amou...

255

Design of a scientific probe for obtaining Mars surface material  

NASA Technical Reports Server (NTRS)

With the recent renewed interest in interplanetary and deep space exploratory missions, the Red Planet, Mars, which has captured people's imagination for centuries, has again become a center of attention. In the late 1960s and early 1970s, a series of Mariner missions performed fly-by investigations of the Mars surface and atmosphere. Later, in the mid 1970s, the data gathered by these earlier Mariner missions provided the basis of the much-publicized Viking missions, whose main objective was to determine the possibility of extraterrestrial life on Mars. More recently, with the dramatic changes in international politics, ambitious joint manned missions between the United States and the Soviet Union have been proposed to be launched in the early 21st century. In light of these exciting developments, the Spacecraft Design course, which was newly established at UCLA under NASA/USRA sponsorship, has developed its curriculum around a design project: the synthesis of an unmanned Martian landing probe. The students are required to conceive a preliminary design of a small spacecraft that is capable of landing at a designated site, collecting soil samples, and then returning the samples to orbit. The goal of the project is to demonstrate the feasibility of such a mission. This preliminary study of an interplanetary exploration mission has shown the feasibility of such a mission. The students have learned valuable lessons about the complexity of spacecraft design, even though the mission is relatively simple.

1990-01-01

256

Designing for time-dependent material response in spacecraft structures  

NASA Technical Reports Server (NTRS)

To study the influence on overall deformations of the time-dependent constitutive properties of fiber-reinforced polymeric matrix composite materials being considered for use in orbiting precision segmented reflectors, simple sandwich beam models are developed. The beam models include layers representing the face sheets, the core, and the adhesive bonding of the face sheets to the core. A three-layer model lumps the adhesive layers with the face sheets or core, while a five-layer model considers the adhesive layers explicitly. The deformation response of the three-layer and five-layer sandwich beam models to a midspan point load is studied. This elementary loading leads to a simple analysis, and it is easy to create this loading in the laboratory. Using the correspondence principle of viscoelasticity, the models representing the elastic behavior of the two beams are transformed into time-dependent models. Representative cases of time-dependent material behavior for the facesheet material, the core material, and the adhesive are used to evaluate the influence of these constituents being time-dependent on the deformations of the beam. As an example of the results presented, if it assumed that, as a worst case, the polymer-dominated shear properties of the core behave as a Maxwell fluid such that under constant shear stress the shear strain increases by a factor of 10 in 20 years, then it is shown that the beam deflection increases by a factor of 1.4 during that time. In addition to quantitative conclusions, several assumptions are discussed which simplify the analyses for use with more complicated material models. Finally, it is shown that the simpler three-layer model suffices in many situations.

Hyer, M. W.; Oleksuk, Lynda L. S.; Bowles, D. E.

1992-01-01

257

Designing for time-dependent material response in spacecraft structures  

NASA Astrophysics Data System (ADS)

To study the influence on overall deformations of the time-dependent constitutive properties of fiber-reinforced polymeric matrix composite materials being considered for use in orbiting precision segmented reflectors, simple sandwich beam models are developed. The beam models include layers representing the face sheets, the core, and the adhesive bonding of the face sheets to the core. A three-layer model lumps the adhesive layers with the face sheets or core, while a five-layer model considers the adhesive layers explicitly. The deformation response of the three-layer and five-layer sandwich beam models to a midspan point load is studied. This elementary loading leads to a simple analysis, and it is easy to create this loading in the laboratory. Using the correspondence principle of viscoelasticity, the models representing the elastic behavior of the two beams are transformed into time-dependent models. Representative cases of time-dependent material behavior for the facesheet material, the core material, and the adhesive are used to evaluate the influence of these constituents being time-dependent on the deformations of the beam. As an example of the results presented, if it assumed that, as a worst case, the polymer-dominated shear properties of the core behave as a Maxwell fluid such that under constant shear stress the shear strain increases by a factor of 10 in 20 years, then it is shown that the beam deflection increases by a factor of 1.4 during that time. In addition to quantitative conclusions, several assumptions are discussed which simplify the analyses for use with more complicated material models. Finally, it is shown that the simpler three-layer model suffices in many situations.

Hyer, M. W.; Oleksuk, Lynda L. S.; Bowles, D. E.

1992-09-01

258

Structural design methodologies for ceramic-based material systems  

NASA Technical Reports Server (NTRS)

One of the primary pacing items for realizing the full potential of ceramic-based structural components is the development of new design methods and protocols. The focus here is on low temperature, fast-fracture analysis of monolithic, whisker-toughened, laminated, and woven ceramic composites. A number of design models and criteria are highlighted. Public domain computer algorithms, which aid engineers in predicting the fast-fracture reliability of structural components, are mentioned. Emphasis is not placed on evaluating the models, but instead is focused on the issues relevant to the current state of the art.

Duffy, Stephen F.; Chulya, Abhisak; Gyekenyesi, John P.

1991-01-01

259

Nonstoichiometric Laser Materials: Designer Wavelengths in Neodymium Doped Garnets  

NASA Technical Reports Server (NTRS)

The tunable nature of lasers provides for a wide range of applications. Most applications rely on finding available laser wavelengths to meet the needs of the research. This article presents the concept of compositional tuning, whereby the laser wavelength is designed by exploiting nonstoichiometry. For research where precise wavelengths are required, such as remote sensing, this is highly advantageous. A theoretical basis for the concept is presented and experimental results in spectroscopic measurements support the theoretical basis. Laser operation nicely demonstrates the validity of the concept of designer lasers.

Walsh, Brian M.; Barnes, Norman P.

2008-01-01

260

The impact of computer-based support on product designers' search for inspirational materials  

Microsoft Academic Search

This paper considers the impact of computer-based support on the task of identifying inspirational materials as part of the process of creative product\\/commercial design. A model of creative design is presented. Using this as a basis, implications for the location of inspirational materials are examined. In particular, the value of structure and diversity in the organisation of retrieved information is

S. J. Westerman; S. Kaur; C. Mougenot; L. Sourbe; C. Bouchard

2006-01-01

261

Interface study and boundary smoothing on designed composite material microstructures for manufacturing purposes  

Microsoft Academic Search

The manufacturability of composite material microstructures designed by the homogenized topology optimization method has to be considered when bringing the design into reality. In this paper, numerical studies are conducted on multiphase material microstructures that have negative coefficients of thermal expansion, for the purpose of improving manufacturability. Realistic manufacturing factors are considered, including the diffusion interface between two constituent phases

H. Qi; N. Kikuchi; J. Mazumder

2004-01-01

262

Designing Web-Based Educative Curriculum Materials for the Social Studies  

ERIC Educational Resources Information Center

This paper reports on a design experiment of web-based curriculum materials explicitly created to help social studies teachers develop their professional teaching knowledge. Web-based social studies curriculum reform efforts, human-centered interface design, and investigations into educative curriculum materials are reviewed, as well as…

Callahan, Cory; Saye, John; Brush, Thomas

2013-01-01

263

Evolutionary Design of a Robotic Material Defect Detection System  

NASA Technical Reports Server (NTRS)

During the post-flight inspection of SSME engines, several inaccessible regions must be disassembled to inspect for defects such as cracks, scratches, gouges, etc. An improvement to the inspection process would be the design and development of very small robots capable of penetrating these inaccessible regions and detecting the defects. The goal of this research was to utilize an evolutionary design approach for the robotic detection of these types of defects. A simulation and visualization tool was developed prior to receiving the hardware as a development test bed. A small, commercial off-the-shelf (COTS) robot was selected from several candidates as the proof of concept robot. The basic approach to detect the defects was to utilize Cadmium Sulfide (CdS) sensors to detect changes in contrast of an illuminated surface. A neural network, optimally designed utilizing a genetic algorithm, was employed to detect the presence of the defects (cracks). By utilization of the COTS robot and US sensors, the research successfully demonstrated that an evolutionarily designed neural network can detect the presence of surface defects.

Ballard, Gary; Howsman, Tom; Craft, Mike; ONeil, Daniel; Steincamp, Jim; Howell, Joe T. (Technical Monitor)

2002-01-01

264

Analysis and Design Tools for Structures Damped by Viscoelastic Materials  

Microsoft Academic Search

Constrained viscoelastic layers have traditionally been consid- ered as damping enhancement mechanisms. More recently bonding has appeared as an alternative to traditional welding strategies and sandwich shells with thick plastic cores have been considered to provide high flexural stiffness for a low overall weight. The present study focuses on computational strategies that can be used to analyze and design the

Adrien Bobillot

265

Design, synthesis and properties of polyimide alignment materials  

Microsoft Academic Search

Polyimide has been applied to the alignment of liquid crystals (LCs) since 1970. It is desirable that polyimide has a stable conformation for control of the pretilt angle of LCs. Low pretilt angle (1-2 degrees) of LCs is the key issue for high duty TN-LCDs. In this paper we report the design, synthesis and properties of a series of polyimide

Fu-Lung Chen; Ted-Horng Shinn; Chein-Dhau Lee; Wen-Shiang Wang

1999-01-01

266

Design of a scientific probe for obtaining Mars surface material  

NASA Technical Reports Server (NTRS)

The objective is to return a 1 Kg Martian soil sample from the surface of Mars to a mothership in a 60 km Mars orbit. Given here is information on the mission profile, the structural design and component placement, thermal control and guidance, propulsion systems, orbital mechanics, and specialized structures.

Baker, Miles; Deyerl, Eric; Gibson, Tim; Langberg, Bob; Yee, Terrance (editor)

1990-01-01

267

Layered zeolitic materials: an approach to designing versatile functional solids.  

PubMed

Relevant layered zeolites have been considered in this perspective article from the point of view of the synthesis methodologies, materials characterization and catalytic implications, considering the unique physico-chemical characteristics of lamellar materials. The potential of layered zeolitic precursors to generate novel lamellar accessible zeolites through swelling, intercalation, pillarization, delamination and/or exfoliation treatments is studied, showing the chemical, functional and structural versatility exhibited by layered zeolites. Recent approaches based on the assembly of zeolitic nanosheets which act as inorganic structural units through the use of dual structural directing agents, the selective modification of germanosilicates and the direct generation of lamellar hybrid organic-inorganic aluminosilicates are also considered to obtain layered solids with well-defined functionalities. The catalytic applications of the layered zeolites are also highlighted, pointing out the high accessibility and reactivity of active sites present in the lamellar framework. PMID:24457617

Díaz, Urbano; Corma, Avelino

2014-07-21

268

DESIGNING OF COURSE MATERIAL FOR E-LEARNING IN PHOTOGRAMMETRY  

Microsoft Academic Search

Distance learning via the Internet (e-learning) requires good course material and a high degree of interactivity. On the basis of an e- learning course of the European Organisation for Spatial Data Research (EuroSDR, formerly OEEPE) about a photogrammetric research topic various tools for producing the user interface, the knowledge pages, multiple-choice quizzes, and interactive learning programs are described. The applied

J. Höhle

269

Self-expanding nitinol stents: material and design considerations  

Microsoft Academic Search

Nitinol (nickel–titanium) alloys exhibit a combination of properties which make these alloys particularly suited for self-expanding stents. Some of these properties cannot be found in engineering materials used for stents presently. This article explains the fundamental mechanism of shape memory and superelasticity, and how they relate to the characteristic performance of self-expanding stents. Nitinol stents are manufactured to a size

Dieter Stoeckel; Alan Pelton; Tom Duerig

2004-01-01

270

Theory based design and optimization of materials for spintronics applications  

NASA Astrophysics Data System (ADS)

The Spintronics industry has developed rapidly in the past decade. Finding the right material is very important for Spintronics applications, which requires good understanding of the physics behind specific phenomena. In this dissertation, we will focus on two types of perpendicular transport phenomena, the current-perpendicular-to-plane giant-magneto-resistance (CPP-GMR) phenomenon and the tunneling phenomenon in the magnetic tunnel junctions. The Valet-Fert model is a very useful semi-classical approach for understanding the transport and spin-flip process in CPP-GMR. We will present a finite element based implementation for the Valet-Fert model which enables a practical way to calculate the electron transport in real CPP-GMR spin valves. It is very important to find high spin polarized materials for CPP-GMR spin valves. The half-metal, due to its full spin polarization, is of interest. We will propose a rational way to find half-metals based on the gap theorem. Then we will focus on the high-MR TMR phenomenon. The tunneling theory of electron transport in mesoscopic systems will be covered. Then we will calculate the transport properties of certain junctions with the help of Green's function under the Landauer-Buttiker formalism, also known as the scattering formalism. The damping constant determines the switching rate of a device. We can calculate it using a method based on the Extended Huckel Tight-Binding theory (EHTB). The symmetry filtering effect is very helpful for finding materials for TMR junctions. Based upon which, we find a good candidate material, MnAl, for TMR applications.

Xu, Tianyi

271

First Materials Science Research Facility Rack Capabilities and Design Features  

NASA Technical Reports Server (NTRS)

The first Materials Science Research Rack (MSRR-1) is the primary facility for U.S. sponsored materials science research on the International Space Station. MSRR-1 is contained in an International Standard Payload Rack (ISPR) equipped with the Active Rack Isolation System (ARIS) for the best possible microgravity environment. MSRR-1 will accommodate dual Experiment Modules and provide simultaneous on-orbit processing operations capability. The first Experiment Module for the MSRR-1, the Materials Science Laboratory (MSL), is an international cooperative activity between NASA's Marshall Space Flight Center (MSFC) and the European Space Agency's (ESA) European Space Research and Technology Center (ESTEC). The MSL Experiment Module will accommodate several on-orbit exchangeable experiment-specific Module Inserts which provide distinct thermal processing capabilities. Module Inserts currently planned for the MSL are a Quench Module Insert, Low Gradient Furnace, and a Solidification with Quench Furnace. The second Experiment Module for the MSRR-1 configuration is a commercial device supplied by MSFC's Space Products Development (SPD) Group. Transparent furnace assemblies include capabilities for vapor transport processes and annealing of glass fiber preforms. This Experiment Module is replaceable on-orbit. This paper will describe facility capabilities, schedule to flight and research opportunities.

Cobb, S.; Higgins, D.; Kitchens, L.; Curreri, Peter (Technical Monitor)

2002-01-01

272

Design and processing of porous materials for electronic applications.  

PubMed

The use of porosity, either unintentionally or intentionally, in the fabrication of materials for electronic and optoelectronic applications is introduced. Unintentional uses include the fabrication of ceramic magnets, where high electrical resistivities are required to reduce eddy currents at high frequency, and the powder technology, often used, inevitably results in porosity. The generation of light from porous silicon created a huge impact in the early 1990s, followed by extensive work on the mechanism responsible, and has now been followed by a more balanced evaluation of its potential. Porous ferroelectrics have shown significant advantages over dense materials for positive temperature coefficient of resistance applications, and for sensors such as hydrophones, and these will be discussed. Low dielectric constant materials are required for the next generation of silicon integrated circuits, where a reduction compared with silicon dioxide is required, and here porosity is a convenient strategy. Finally, the use of deliberately engineered porous nanostructures, with dimensions in the range of the wavelength of light, are discussed for applications in optical processing. PMID:18272459

Willoughby, A F W

2006-01-15

273

Design elements for the development of cancer education print materials for a Latina/o audience.  

PubMed

Health educators can help reduce cancer disparities in Latino populations through the creation of effective print materials. In this effort, the National Cancer Institute conducted a comprehensive needs assessment to identify key design elements of cancer education programs and create a cost-effective process that would ensure consistency in the development of materials. This article introduces the Checklist of Design Elements for the Development of Cancer Education Print Materials for Latina/o Audiences (CEMLA), which includes a total of 10 design elements related to the process of developing materials and content. Using social learning theory as a theoretical framework, design elements are included that reflect cultural sensitivity at the surface and deep structure levels. This is the most comprehensive effort to date to integrate and synthesize theory and application in the design of materials for this audience. PMID:19098265

Buki, Lydia P; Salazar, Silvia I; Pitton, Viviana O

2009-10-01

274

Design, synthesis, and characterization of new materials for thermoelectric applications  

NASA Astrophysics Data System (ADS)

Currently, the best known material for thermoelectric refrigeration at room temperature is and alloy of Bi2Te3 and Sb 2Te3. This material has been the basis for room temperature thermoelectric cooling for over 40 years, but its low cooling efficiency (?10% of Carnot Efficiency) has limited its adaptation to small-market specialty applications. Since Bi2Te3 and its alloys have been studied so extensively, it is doubtful that large improvements in efficiency can be made by further modifications of Bi2Te3 (ie. by changing doping or processing of the material). Therefore, this dissertation deals with the discovery and exploration of completely new systems of compounds. The most important parameter for characterizing the efficiency of a thermoelectric material is the dimensionless quantity ZT, where ZT = S2T/rhokappa. Here, S is the thermopower, T is the temperature, kappa is the thermal conductivity, and rho is the electrical resistivity. These variables are not independent of each other, and usually if one of the values is altered by changing composition or doping, the others change as well. Understanding these parameters in depth leads us to several guidelines for searching for better thermoelectric materials and these are discussed in the dissertation. The concept of obtaining highly symmetric crystal structures and also its relation to increasing the value of ZT is discussed. The synthesis of several new quaternary compounds by starting with highly symmetric tetrahedral anion building blocks is presented. While some of these compounds did in fact have high symmetry structures, none were suitable for further studies because they all had large bandgaps. Further systems we explored include heavy metal telluride compounds and compounds that have multiple ordered anions. These systems were chosen based on the concept of minimizing thermal conductivity. A brief chapter on skutterudite materials explores a few new compounds discovered in this highly researched area. The skutterudites are potentially good thermoelectric materials at temperatures above room temperature, however, the compounds discovered were metals and unsuitable for thermoelectric applications. Perhaps the most promising area of research in thermoelectrics presented in this dissertation involves the use of thallium as an alkali metal-like cation. It is shown here that thallium chalcogenides form a wide variety of structures that in many ways mimic the chemistry of alkali metal chalcogenides, yet often form different structures. We present 18 new compounds in that chapter, one of which (Tl1-xSn3+2 xBi7-xSe 14) has an estimated ZT of 0.2--0.3 at room temperature. Since this is not an optimized value, the value of ZT may be able to be increased considerably by carefully adjusting the carrier density. Finally, we present a chapter on measuring the various important thermoelectric parameters (S, rho, and kappa). The construction of a new apparatus for such measurements is presented, along with a new method for measuring kappa, which is much more rapid than steady-state methods.

Reynolds, Thomas Kent

275

Catalytic converter design and materials. (Bibliography from the global mobility database). Published Search  

SciTech Connect

The bibliography contains citations concerning the various designs, configurations, and materials used in catalytic converters to diminish emissions from automotive, truck, diesel, and off-highway vehicles. Citations examine designs using internal flows and diffuser-monolith flows; the effects of flow maldistribution and steady state heat transfer; and materials, including platinum-palladium, urea-SCR, and copper-zeolite. Light-off and three-way catalysts and those designed for natural gas are emphasized. References also cite air/fuel tests, Taguchi techniques, and European and American standards affecting design and materials. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1996-03-01

276

Catalytic converter design and materials. (Bibliography from the Global Mobility database). Published Search  

SciTech Connect

The bibliography contains citations concerning the various designs, configurations, and materials used in catalytic converters to diminish emissions from automotive, truck, diesel, and off-highway vehicles. Citations examine designs using internal flows and diffuser-monolith flows; the effects of flow maldistribution and steady state heat transfer; and materials, including platinum-palladium, urea-SCR, and copper-zeolite. Light-off and three-way catalysts and those designed for natural gas are emphasized. References also cite air/fuel tests, Taguchi techniques, and European and American standards affecting design and materials. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1997-06-01

277

Catalytic converter design and materials. (A bibliography from the Global Mobility database). Published Search  

SciTech Connect

The bibliography contains citations concerning the various designs, configurations, and materials used in catalytic converters to diminish emissions from automotive, truck, diesel, and off-highway vehicles. Citations examine designs using internal flows and diffuser-monolith flows; the effects of flow maldistribution and steady state heat transfer; and materials, including platinum-palladium, urea-SCR, and copper-zeolite. Light-off and three-way catalysts and those designed for natural gas are emphasized. References also cite air/fuel tests, Taguchi techniques, and European and American standards affecting design and materials. (Contains a minimum of 220 citations and includes a subject term index and title list.)

Not Available

1993-12-01

278

MATERIALS DESIGN CONSIDERATIONS AND SELECTION FOR A LARGE RAD WASTE INCINERATOR  

Microsoft Academic Search

A new incinerator has been built to process self-generated, low level radioactive wastes at the Department of Energy`s Savannah River Site. Wastes include protective clothing and other solid materials used during the handling of radioactive materials, and liquid chemical wastes resulting from chemical and waste management operations. The basic design and materials of construction selected to solve the anticipated corrosion

P. R. Vormelker; C. F. Jenkins; H. H. Burns

1997-01-01

279

Elementary Students' Learning of Materials Science Practices through Instruction Based on Engineering Design Tasks  

ERIC Educational Resources Information Center

Materials science, which entails the practices of selecting, testing, and characterizing materials, is an important discipline within the study of matter. This paper examines how third grade students' materials science performance changes over the course of instruction based on an engineering design challenge. We conducted a case study of nine…

Wendell, Kristen Bethke; Lee, Hee-Sun

2010-01-01

280

Virtual Welded - Joint Design Integrating Advanced Materials and Processing Technology  

SciTech Connect

Virtual Welede-Joint Design, a systematic modeling approach, has been developed in this project to predict the relationship of welding process, microstructure, properties, residual stress, and the ultimate weld fatique strength. This systematic modeling approach was applied in the welding of high strength steel. A special welding wire was developed in this project to introduce compressive residual stress at weld toe. The results from both modeling and experiments demonstrated that more than 10x fatique life improvement can be acheived in high strength steel welds by the combination of compressive residual stress from the special welding wire and the desired weld bead shape from a unique welding process. The results indicate a technology breakthrough in the design of lightweight and high fatique performance welded structures using high strength steels.

Yang, Zhishang; Ludewig, Howard W.; Babu, S. Suresh

2005-06-30

281

Optimized Design of Radar Absorbing Materials for Complex Targets  

Microsoft Academic Search

Abstract—In this paper, we present a hybrid technique for designing RAM optimally to reduce the RCS of complex targets in a wide-band frequency range. The technique combines a high-frequency method and a genetic algorithm (GA) to obtain an optimal RAM in complex targets. By the virtue of the high-frequency method, such as the physical optics (PO) method and the method,of

H.-S. Park; I.-S. Choi; J.-K. Bang; S.-H. Suk; S.-S. Lee; H.-T. Kim

2004-01-01

282

Decoupling interrelated parameters for designing high performance thermoelectric materials.  

PubMed

The world's supply of fossil fuels is quickly being exhausted, and the impact of their overuse is contributing to both climate change and global political unrest. In order to help solve these escalating problems, scientists must find a way to either replace combustion engines or reduce their use. Thermoelectric materials have attracted widespread research interest because of their potential applications as clean and renewable energy sources. They are reliable, lightweight, robust, and environmentally friendly and can reversibly convert between heat and electricity. However, after decades of development, the energy conversion efficiency of thermoelectric devices has been hovering around 10%. This is far below the theoretical predictions, mainly due to the interdependence and coupling between electrical and thermal parameters, which are strongly interrelated through the electronic structure of the materials. Therefore, any strategy that balances or decouples these parameters, in addition to optimizing the materials' intrinsic electronic structure, should be critical to the development of thermoelectric technology. In this Account, we discuss our recently developed strategies to decouple thermoelectric parameters for the synergistic optimization of electrical and thermal transport. We first highlight the phase transition, which is accompanied by an abrupt change of electrical transport, such as with a metal-insulator and semiconductor-superionic conductor transition. This should be a universal and effective strategy to optimize the thermoelectric performance, which takes advantage of modulated electronic structure and critical scattering across phase transitions to decouple the power factor and thermal conductivity. We propose that solid-solution homojunction nanoplates with disordered lattices are promising thermoelectric materials to meet the "phonon glass electron crystal" approach. The formation of a solid solution, coupled with homojunctions, allows for synergistically enhanced thermoelectric properties. This occurs through a significant reduction of thermal conductivity, without the deterioration of thermopower and electrical conductivity. In addition, we introduce the concept of spin entropy in wide band gap semiconductor nanocrystals, which acts to fully disentangle the otherwise interconnected quantities for synergistically optimized thermoelectric performance. Finally, we discuss a new concept we developed that is based on an ultrathin-nanosheet composite that we fabricated from ultrathin nanosheets of atomic thickness. These retain the original strong two-dimensional electron gas (2DEG) and allow for decoupled optimization of the three thermoelectric parameters, which improves thermoelectric performance. PMID:24517646

Xiao, Chong; Li, Zhou; Li, Kun; Huang, Pengcheng; Xie, Yi

2014-04-15

283

Photovoltaic Module Encapsulation Design and Materials Selection, Volume 1, Abridged  

NASA Technical Reports Server (NTRS)

A summary version of Volume 1, presenting the basic encapsulation systems, their purposes and requirements, and the characteristics of the most promising candidate systems and materials, as identified and evaluated by the Flat-Plate Solar Array Project is presented. In this summary version considerable detail and much supporting and experimental information has necessarily been omitted. A reader interested in references and literature citations, and in more detailed information on specific topics, should consult Reference 1, JPL Document No. 5101-177, JPL Publication 81-102, DOE/JPL-1012-60 (JPL), June 1, 1982.

Cuddihy, E. F.

1982-01-01

284

Design of new frictional testing machine for shallow fault materials  

NASA Astrophysics Data System (ADS)

Subduction thrust faults at shallow depth mainly consist of granular and clay-rich materials which strengths are influenced by the presence of pore water. Dilatation and pore pressure generation of fault zones by the dynamic friction will increase the volumetric water content in fault zone, which can assist the fault weakening by acoustic fluidization or hydrodynamic lubrication mechanism. Therefore the evaluation of rheology for clay minerals rich in pore water is critical for understanding of seismic behaviors at shallow depth. Here, we introduce a new testing apparatus for the purpose of accurate evaluation of friction behavior for incohesive fault rock materials. Our machine can shear granular materials up to 80 mm of outer diameter and maximum thickness of 40 mm. The capacities of axial load, torque, and motor are 100kN, 500Nm and 30kW, respectively, and pore pressure is increased up to 50 MPa. Maximum rotation speed is 660 rpm, which is equivalent to 1 m/s of the average slip velocity when sample diameter is 60 mm. We can monitor the dynamic changes of pore pressure and temperature at sliding surface during the friction tests. We can also control the pore pressure, axial load, pore pressure and temperature independently. All parameters can be held at targeted values and be generated at constant incremental velocity. We can control the rotation more sensitively to program the complicated rotation history that slip velocity and acceleration change during the rotation. We used powdered smectite and illite in our friction tests. We measured normal stress dependence on shear stress at normal stress up to 25 MPa with a constant rotation speed from 0.01 to 1 rpm. Normal stress is proportional to shear stress for dry clay minerals, and the friction coefficients are from 0.3 to 0.5. On the other hand, very low friction is observed in clay minerals saturated by water, and shear strength is nearly constant at various normal stresses. Our results suggest that clay minerals will lose their strength when clay minerals contain water at a certain ratio, and clay minerals behave as viscous fluid. The transition process from Amonton’s law of friction to viscous flow is important for understanding of friction behavior at shallow depth. (a) Frictional strength for a variety of rocks plotted as a function of normal stress. (b) Enlargement of figure (a) at a low stress regime.

Tadai, O.; Tanikawa, W.; Hirose, T.; Sakaguchi, M.; Lin, W.

2009-12-01

285

EDITORIAL: Photonic materials on demand Photonic materials on demand  

NASA Astrophysics Data System (ADS)

As David Payne famously said, 'we never have a photonic material that we want...'. This has changed with the proliferation of nanotechnology. Metamaterials—artificial media structured on a sub-wavelength scale—offer a radical paradigm for the engineering of optical properties. Some remarkable advances have been possible with metamaterials. These include, for instance, negative-index media that refract light in the opposite direction from that of conventional materials, chiral materials that rotate the polarization state of light hundreds of thousands of times more strongly than natural optical crystals, and structured thin films with remarkably strong dispersion that can slow light in much the same way as resonant atomic systems with electromagnetically induced transparency. The research agenda is now shifting towards achieving tunable and switchable functionalities with metamaterials [1] where the goal is, paraphrasing Dave Payne, 'to have on demand the photonic material that we want'. The papers in this Journal of Optics special issue explore and review the different approaches to both switching and tuning of metamaterial properties through exploiting effects such as phase conjugation, intense photo-excitation and photoconductivity, the use of electro-optical effects in conductive oxides, the exploitation global quantum coherency and resonantly coupled classical resonator and quantum structures, hybridization with gain media and the manipulation with shapes and constitution of the complex metamolecules and metamaterial reliefs by design, or using MEMS actuation. References [1] Zheludev N I and Kivshar Y 2012 From metamaterials to metadevices Nature Mater.11 917

Zheludev, Nikolay; Padilla, Willie J.; Brener, Igal

2012-11-01

286

Comparison of gap frame designs and materials for precision cathode strip chambers  

SciTech Connect

Precision cathode strip chamber perimeter designs that incorporate either continuous or discrete-post gap frames are analyzed. The effects of ten design and material combinations on gravity sag, mass, stress, and deflected shape are evaluated. Procedures are recommended for minimizing mass in the chamber perimeter region while retaining structural integrity and electrical design latitude.

Horvath, J.A.; Pratuch, S.M.; Belser, F.C. [Lawrence Livermore National Lab., CA (United States)

1993-09-16

287

n-Channel semiconductor materials design for organic complementary circuits.  

PubMed

Organic semiconductors have unique properties compared to traditional inorganic materials such as amorphous or crystalline silicon. Some important advantages include their adaptability to low-temperature processing on flexible substrates, low cost, amenability to high-speed fabrication, and tunable electronic properties. These features are essential for a variety of next-generation electronic products, including low-power flexible displays, inexpensive radio frequency identification (RFID) tags, and printable sensors, among many other applications. Accordingly, the preparation of new materials based on ?-conjugated organic molecules or polymers has been a central scientific and technological research focus over the past decade. Currently, p-channel (hole-transporting) materials are the leading class of organic semiconductors. In contrast, high-performance n-channel (electron-transporting) semiconductors are relatively rare, but they are of great significance for the development of plastic electronic devices such as organic field-effect transistors (OFETs). In this Account, we highlight the advances our team has made toward realizing moderately and highly electron-deficient n-channel oligomers and polymers based on oligothiophene, arylenediimide, and (bis)indenofluorene skeletons. We have synthesized and characterized a "library" of structurally related semiconductors, and we have investigated detailed structure-property relationships through optical, electrochemical, thermal, microstructural (both single-crystal and thin-film), and electrical measurements. Our results reveal highly informative correlations between structural parameters at various length scales and charge transport properties. We first discuss oligothiophenes functionalized with perfluoroalkyl and perfluoroarene substituents, which represent the initial examples of high-performance n-channel semiconductors developed in this project. The OFET characteristics of these compounds are presented with an emphasis on structure-property relationships. We then examine the synthesis and properties of carbonyl-functionalized oligomers, which constitute second-generation n-channel oligothiophenes, in both vacuum- and solution-processed FETs. These materials have high carrier mobilities and good air stability. In parallel, exceptionally electron-deficient cyano-functionalized arylenediimide derivatives are discussed as early examples of thermodynamically air-stable, high-performance n-channel semiconductors; they exhibit record electron mobilities of up to 0.64 cm(2)/V·s. Furthermore, we provide an overview of highly soluble ladder-type macromolecular semiconductors as OFET components, which combine ambient stability with solution processibility. A high electron mobility of 0.16 cm(2)/V·s is obtained under ambient conditions for solution-processed films. Finally, examples of polymeric n-channel semiconductors with electron mobilities as high as 0.85 cm(2)/V·s are discussed; these constitute an important advance toward fully printed polymeric electronic circuitry. Density functional theory (DFT) computations reveal important trends in molecular physicochemical and semiconducting properties, which, when combined with experimental data, shed new light on molecular charge transport characteristics. Our data provide the basis for a fundamental understanding of charge transport in high-performance n-channel organic semiconductors. Moreover, our results provide a road map for developing functional, complementary organic circuitry, which requires combining p- and n-channel transistors. PMID:21615105

Usta, Hakan; Facchetti, Antonio; Marks, Tobin J

2011-07-19

288

Negative index of refraction in optical metamaterials  

Microsoft Academic Search

A double-periodic array of pairs of parallel gold nanorods is shown to have a negative refractive index in the optical range. Such behavior results from the plasmon resonance in the pairs of nanorods for both the electric and the magnetic components of light. The refractive index is retrieved from direct phase and amplitude measurements for transmission and reflection, which are

Vladimir M. Shalaev; Wenshan Cai; Uday K. Chettiar; Hsiao-Kuan Yuan; Andrey K. Sarychev; Vladimir P. Drachev; Alexander V. Kildishev

2005-01-01

289

High-temperature mechanical and material design for SiC composites  

Microsoft Academic Search

Silicon carbide (SIC) fiber reinforced composites (FRCs) are strong potential candidate structural and high heat flux materials for fusion reactors. A concise discussion of the main material and design issues related to the use of SiC FRCs as structural materials in future fusion systems is given in this paper. The status of material processing of SiC\\/SiC composites is first reviewed.

Nasr M. Ghoniem

1992-01-01

290

Material property for designing, analyzing, and fabricating space structures  

NASA Technical Reports Server (NTRS)

An analytical study was made of plasma assisted bullet projectile. The finite element analysis and the micro-macromechanic analysis was applied to an optimum design technique for the multilayered graphite-epoxy composite projectile that will achieve hypervelocity of 6 to 10 Km/s. The feasibility was determined of dialectics to monitor cure of graphite-epoxies. Several panels were fabricated, cured, and tested with encouraging results of monitoring the cure of graphite-epoxies. The optimum cure process for large structures was determined. Different orientation were used and three different curing cycles were employed. A uniaxial tensile test was performed on all specimens. The optimum orientation with the optimum cure cycle were concluded.

Kolkailah, Faysal A.

1991-01-01

291

Ionomer Design Principles for Single Ion-Conducting Energy Materials  

NASA Astrophysics Data System (ADS)

Single-ion conducting ionomers with low glass transition temperature, high dielectric constant and containing bulky ions with diffuse charge, are needed for polymer membranes that transport small counterions. Overarching design principles emerging from quantum chemistry calculations suggest that diffuse charge can be attained from simple considerations of atomic electronegativity. For lithium or sodium batteries, perfluorinated tetraphenyl borate ionomers with solvating polar comonomers are proposed. For fluoride or hydroxide batteries and for iodide transporting solar cells, tetra-alkyl phosphonium ionomers with anion receptors are proposed. First attempts to construct such ionomers to test these ideas will be discussed, with results from dielectric spectroscopy to measure conductivity, dielectric constant and number density of simultaneously conducting ions.

Colby, Ralph; Liang, Siwei; Liu, Wenjuan; Hyeok Choi, U.; Runt, James; Shiau, Huai-Suen; Janik, Michael

2012-02-01

292

Effects of Buckling Knockdown Factor, Internal Pressure and Material on the Design of Stiffened Cylinders  

NASA Technical Reports Server (NTRS)

A design study was conducted to investigate the effect shell buckling knockdown factor (SBKF), internal pressure and aluminum alloy material selection on the structural weight of stiffened cylindrical shells. Two structural optimization codes were used for the design study to determine the optimum minimum-weight design for a series of design cases, and included an in-house developed genetic algorithm (GA) code and PANDA2. Each design case specified a unique set of geometry, material, knockdown factor combinations and loads. The resulting designs were examined and compared to determine the effects of SBKF, internal pressure and material selection on the acreage design weight and controlling failure mode. This design study shows that use of less conservative SBKF values, including internal pressure, and proper selection of material alloy can result in significant weight savings for stiffened cylinders. In particular, buckling-critical cylinders with integrally machined stiffener construction can benefit from the use of thicker plate material that enables taller stiffeners, even when the stiffness, strength and density properties of these materials appear to be inferior.

Lovejoy, Andrew E.; Hilburger, Mark W.; Chunchu, Prasad B.

2010-01-01

293

Computational Design of Photovoltaic Materials with Self Organized Nano Structures  

NASA Astrophysics Data System (ADS)

Chalcopyrite and II-VI semiconductors, such as Cu(In, Ga)Se2, Cu2ZnSn(S, Se)4 and Cd(S, Te), are one of the most promising materials for low cost photovoltaic solar-cells. In this paper, based on first-principles calculations, we propose that self-organized nano-structures in these compounds will enhance the conversion efficiency. Our calculations are based on the KKR-CPA-LDA [1] with the self-interaction correction [2]. We also use VASP package [3] for calculating mixing energy and effective interactions of the systems by using the cluster expansion method [4]. For phase separating systems, we simulate nano-structure formation by using the Monte Carlo method. It is expected that the photo-generated electron-hole pairs are efficiently separated by the type-II interface and then effectively transferred along the quasi-one-dimensional structures. Moreover, we can expect multiplication of generated carriers due to the multi-exciton effects in nano-structures [5]. [4pt] [1] H. Akai, http://sham.phys.sci.osaka-u.ac.jp/kkr/[0pt] [2] A. Filippetti and N. A. Spaldin, PRB 67 (2003) 125109.[0pt] [3] G. Kresse and J. Hafner, PRB 47 (1993) 558.[0pt] [4] A. Zunger, NATO ASI B 319 (1994) 361.[0pt] [5] Y. Tani et al., APEX 3 (2010) 101201, 4 (2011) 021201, JJAP 51 (2012) 050202.

Sato, Kazunori; Katayama-Yoshida, Hiroshi

2013-03-01

294

The influence of material and design on total knee replacement wear.  

PubMed

It is difficult for surgeons to make the decision on which design or material to use given the different options available. Marketing claims and direct-to-consumer advertising certainly complicate this further. One company may claim a higher percentage of wear reduction with their bearing surfaces compared with those of another manufacturer. If the percentage of wear reduction is lower, it is unclear as to whether this creates a more effective technology for reducing wear in the clinical situation. The relative contribution and relationship of design and materials to wear performance must be considered before making that important judgment. To examine the overall influence of implant design on wear reduction, a knee simulator study was undertaken. This simulator study compared the Oxinium Genesis II system with the Triathlon Conventional and Triathlon X3 knee systems under physiologic stair-climb loading and motion profiles. This allows a similar comparison of material effect within one design but also a global comparison across designs. Test results show the Triathlon Conventional and Triathlon X3 knee systems have superior wear resistance compared with that of the Genesis II Oxinium system under stair-climbing simulation. This finding indicates that implant design plays a more significant role in knee wear reduction than material. Although material technology may improve a given knee system's ability to wear, design geometry has a first-order effect and should be addressed before materials. This study represents an effort to differentiate design effect from two different approaches to material enhancement. The results of this study support the predominance of design in knee replacement wear performance. Ultimately, only clinical evidence such as published studies or outcomes reported in the available joint registries will establish whether any material or design can achieve a 30-year outcome. PMID:21618933

Essner, Aaron; Herrera, Lizeth; Hughes, Phillip; Kester, Mark

2011-03-01

295

Structural materials for ITER in-vessel component design  

NASA Astrophysics Data System (ADS)

The materials proposed for ITER in-vessel components have to exhibit adequate performance for the operating lifetime of the reactor or for specified replacement intervals. Estimates show that maximum irradiation dose to be up to 5-7 dpa (for 1 MWa/m 2 in the basic performance phase (BPP)) within a temperature range from 20 to 300°C. Austenitic SS 316LN-ITER Grade was defined as a reference option for the vacuum vessel, blanket, primary wall, pipe lines and divertor body. Conventional technologies and mill products are proposed for blanket, back plate and manifold manufacturing. HIPing is proposed as a reference manufacturing method for the primary wall and blanket and as an option for the divertor body. The existing data show that mechanical properties of HIPed SS are no worse than those of forged 316LN SS. Irradiation will result in property changes. Minimum ductility has been observed after irradiation in an approximate temperature range between 250 and 350°C, for doses of 5-10 dpa. In spite of radiation-induced changes in tensile deformation behavior, the fracture remains ductile. Irradiation assisted corrosion cracking is a concern for high doses of irradiation and at high temperatures. Re-welding is one of the critical issues because of the need to replace failed components. It is also being considered for the replacement of shielding blanket modules by breeding modules after the BPP. Estimates of radiation damage at the locations for re-welding show that the dose will not exceed 0.05 dpa (with He generation of 1 appm) for the manifold and 0.01 dpa (with He generation 0.1 appm) for the back plate for the BPP of ITER operation. Existing experimental data show that these levels will not result in property changes for SS; however, neutron irradiation and He generation promote crack formation in the heat affected zone during welding. Cu based alloys, DS-Cu (Glidcop A125) and PH?Cu Cu?Cr?Zr bronze) are proposed as a structural materials for high heat flux components of limiter, baffle, divertor and primary wall. Irradiation significantly changes the mechanical properties, and the electrical and thermal conductivity of these alloys. The ductibility of high strength Cu alloys is reduced at relatively low doses (< 0.2 dpa) for irradiation temperature ˜ < 150°C. For higher doses of irradiation it remains at the low (saturated) level. This effect is exhibited by both DS-Cu and PH-Cu alloys. For higher temperatures of irradiation, an increase of ductility and decrease of strength are observed resulting from radiation-induced microstructural instabilities. The 'softening' temperatures for Cu?Cr?Zr alloys is ca. 300-400°C.

Kalinin, G.; Gauster, W.; Matera, R.; Tavassoli, A.-A. F.; Rowcliffe, A.; Fabritsiev, S.; Kawamura, H.

1996-10-01

296

Materials study supporting thermochemical hydrogen cycle sulfuric acid decomposer design  

NASA Astrophysics Data System (ADS)

Increasing global climate change has been driven by greenhouse gases emissions originating from the combustion of fossil fuels. Clean burning hydrogen has the potential to replace much of the fossil fuels used today reducing the amount of greenhouse gases released into the atmosphere. The sulfur iodine and hybrid sulfur thermochemical cycles coupled with high temperature heat from advanced nuclear reactors have shown promise for economical large-scale hydrogen fuel stock production. Both of these cycles employ a step to decompose sulfuric acid to sulfur dioxide. This decomposition step occurs at high temperatures in the range of 825°C to 926°C dependent on the catalysis used. Successful commercial implementation of these technologies is dependent upon the development of suitable materials for use in the highly corrosive environments created by the decomposition products. Boron treated diamond film was a potential candidate for use in decomposer process equipment based on earlier studies concluding good oxidation resistance at elevated temperatures. However, little information was available relating the interactions of diamond and diamond films with sulfuric acid at temperatures greater than 350°C. A laboratory scale sulfuric acid decomposer simulator was constructed at the Nuclear Science and Engineering Institute at the University of Missouri-Columbia. The simulator was capable of producing the temperatures and corrosive environments that process equipment would be exposed to for industrialization of the sulfur iodide or hybrid sulfur thermochemical cycles. A series of boron treated synthetic diamonds were tested in the simulator to determine corrosion resistances and suitability for use in thermochemical process equipment. These studies were performed at twenty four hour durations at temperatures between 600°C to 926°C. Other materials, including natural diamond, synthetic diamond treated with titanium, silicon carbide, quartz, aluminum nitride, and Inconel were also tested in the simulator to determine corrosion resistances. The study concluded that boron treated diamonds were not suitable for use in decomposer process equipment. Unacceptable corrosion rates were observed at 600°C and increased linearly with temperature up to 700°C. The boron treated diamonds completely disassociated at temperatures above 700°C. The researcher postulated that the high corrosion rates resulted from diamond carbon having a higher preference for oxygen free radicals formed during the decomposition process. Oxygen free radical concentration also increased as a function of increasing temperature. The study also concluded that natural diamond and synthetic titanium treated diamond were unsuitable for use in decomposer process equipment. The corrosion results were similar to that of the boron treated diamonds. Silicon carbide may have potential for used in decomposer process equipment. No appreciable silicon carbide corrosion was observed and more study is warranted. Small amounts of quartz and aluminum nitride corrosion was observed. Inconel corrosion rates were very high at all temperatures tested.

Peck, Michael S.

297

Polyoxometalate clusters, nanostructures and materials: From self assembly to designer materials and devices  

Microsoft Academic Search

Polyoxometalates represent a diverse range of molecular clusters with an almost unmatched range of physical properties and the ability to form structures that can bridge several length scales. The new building block principles that have been discovered are beginning to allow the design of complex clusters with desired properties and structures and several structural types and novel physical properties are

De-Liang Long; Eric Burkholder; Leroy Cronin

2007-01-01

298

Design of Materials with Extreme Thermal Expansion Using a Three-Phase Topology Optimization Method.  

National Technical Information Service (NTIS)

Composites with extremal or unusual thermal expansion coefficients are designed using a three-phase topology optimization method. The composites are made of two different material phases and a void phase. The topology optimization method finds the distrib...

O. Sigmund S. Torquato

1996-01-01

299

Design features and capabilities of the First Materials Science Research Rack (MSRR-1)  

Microsoft Academic Search

The First Material Science Research Rack (MSRR-1) aboard the International Space Station (ISS) will offer many unique capabilities and design features to facilitate a wide range of materials science investigations. The initial configuration of MSRR-1 will accommodate two independent Experiment Modules (EMs) and provide the capability for simultaneous on-orbit processing. The facility will provide the common subsystems and interfaces required

P. J. Pettigrew; L. Kitchen; C. Darby; S. D. Cobb; S. Lehoczky

2003-01-01

300

Curriculum Design for Inquiry: Preservice Elementary Teachers' Mobilization and Adaptation of Science Curriculum Materials  

ERIC Educational Resources Information Center

Curriculum materials are crucial tools with which teachers engage students in science as inquiry. In order to use curriculum materials effectively, however, teachers must develop a robust capacity for pedagogical design, or the ability to mobilize a variety of personal and curricular resources to promote student learning. The purpose of this study…

Forbes, Cory T.; Davis, Elizabeth A.

2010-01-01

301

Multimedia and Cognition: Examining the Effect of Applying Cognitive Principles to the Design of Instructional Materials  

ERIC Educational Resources Information Center

The human cognitive system possesses a finite processing capacity, which is split into channels for various modalities, and learning can be inhibited if any of the cognitive channels is overloaded. However, although the amount of e-learning materials is increasing steadily, the design of instructional material has been largely based on intuition…

Thompson, Nik; McGill, Tanya Jane

2008-01-01

302

Materials Design and Discovery: Catalysis and Energy Storage (Mira Early Science Program Final Technical Report).  

National Technical Information Service (NTIS)

The investigation and design of new classes of materials for energy and catalysis requires a multi-facetted approach to simulation. Multiple methods are needed to study materials on the length scale 0.1 nm - 10 nm. For simulations where the atomic (and el...

A. Benali N. A. Romero

2013-01-01

303

Design and fabrication of narrow band radar absorbing materials at terahertz frequencies  

Microsoft Academic Search

The technique of tailoring the complex refractive index of an artificial dielectric material has been developed at the University of Lowell Research Foundation (ULRF). Low reflection coatings, generally referred to as Dällenbach layers, have been designed for metal substrates using the artificial dielectric. The method of characterizing materials for the purpose of tailoring their dielectric properties at terahertz frequencies will

R. H. Giles; A. J. Gatesman; A. P. Ferdinand; J. Waldman

1990-01-01

304

Design of engineering materials using hybrid neural-networks and evolutionary algorithms  

Microsoft Academic Search

The design of engineering materials satisfying different performance criteria is an important problem spanning such varied areas as solvents, polymers, additives, and pharmaceuticals. The problem comprises of a forward phase of performance prediction of the engineering material and an inverse problem of construction of the product from desired performance requirements. Real-life industrial problems are characterized by uncertainty in knowledge underlying

Ananthapadmanaban Sundaram

1999-01-01

305

Materials design data for reduced activation martensitic steel type F82H  

Microsoft Academic Search

This paper presents materials data for design of ITER test blanket modules with the reduced activation ferritic martensitic steel type F82H as structural material. From the physical properties databases, variations of modulus of elasticity, density, thermal conductivity, thermal diffusivity, specific heat, mean and instantaneous linear coefficients of thermal expansion versus temperature are derived. Also reported are Poisson's ratio and magnetic

A.-A. F Tavassoli; J.-W Rensman; M Schirra; K Shiba

2002-01-01

306

A Simple Guide for Design, Use, and Evaluation of Educational Materials.  

ERIC Educational Resources Information Center

Because few health workers in Latin America are trained in how to produce effective and appropriate health education materials, the Pan American Health Organization developed a method to teach the design, use, and evaluation of health education materials. This article describes the development of the methodology, the basic operating principles,…

Rice, Marilyn; Valdivia, Leonel

1991-01-01

307

The Design and Production of Self-Instructional Materials. Open and Distance Learning Series.  

ERIC Educational Resources Information Center

This book is based on training sessions conducted by the author that focused on key issues in the design of self-instructional materials, including an awareness of the distinctive features of self-instructional materials, characteristics of the target audience, and coming to grips with the resources and constraints within which one must work.…

Lockwood, Fred

308

Preparation of Silicon Nitride Multilayer Ceramic Radome Material and Optimal Design of the Wall Structure  

Microsoft Academic Search

A study of silicon nitride ceramic radomes, which includes preparation of the material and optimal design of the radome wall structure, is presented in this paper. Multilayer radome wall structure with high dielectric constant skins and a low dielectric constant core layer is used for broadband application. As a candidate material for both the skins and core layer, silicon nitride

Chen Fei; Shen Qiang; Zhang Lianmeng

2008-01-01

309

Design of materials with extreme thermal expansion using a three-phase topology optimization method  

Microsoft Academic Search

Composites with extremal or unusual thermal expansion coefficients are designed using a three-phase topology optimization method. The composites are made of two different material phases and a void phase. The topology optimization method consists in finding the distribution of material phases that optimizes an objective function (e.g. thermoelastic properties) subject to certain constraints, such as elastic symmetry or volume fractions

O. Sigmund; S. Torquato

1997-01-01

310

Design and Evaluation of Online Courses Containing Media-Enhanced Learning Materials  

ERIC Educational Resources Information Center

With the current state of web technology, multimedia materials are readily accessible by students. This paper reports on the design and evaluation of three online courses from a university in Hong Kong which incorporate media-enhanced learning materials. These cases are at different positions with respect to the types of knowledge and levels of…

Lam, Paul; McNaught, Carmel

2006-01-01

311

Design, fabrication, and evaluation of high frequency, single-element transducers incorporating different materials  

Microsoft Academic Search

The performance of high frequency, single-element transducers depends greatly on the mechanical and electrical properties of the piezoelectric materials used. This study compares the design and performance of transducers incorporating different materials. The materials investigated include 1-3 lead zirconate titanate (PZT) fiber composite, lead titanate (PbTiO 3) ceramic, poly(vinylidene fluoride) (PVDF) film, and lithium niobate (LiNbO 3) single crystal. All

Kevin A. Snook; Jian-Zhong Zhao; Carlos H. F. Alves; Jonathan M. Cannata; Wo-Hsing Chen; T. A. Ritter; K. K. Shung

2002-01-01

312

Materials for MW sized aerogenerators. I - The influence of design on operating parameters  

Microsoft Academic Search

Materials and fatigue design deficiencies in the development and production of MW-scale wind turbines with 30-yr, reliable, cost-effective lifetimes are surveyed. Attention is given to existing wind turbines, the performance of materials to date, and fundamental materials properties. Failures thus far have arisen from the coincidence of fundamental vibration frequency or a low order harmonic of components with an exciting

L. M. Wyatt

1983-01-01

313

Materials design considerations and selection for a large rad waste incinerator  

SciTech Connect

A new incinerator has been built to process self-generated, low level radioactive wastes at the Department of Energy`s Savannah River Site. Wastes include protective clothing and other solid materials used during the handling of radioactive materials, and liquid chemical wastes resulting from chemical and waste management operations. The basic design and materials of construction selected to solve the anticipated corrosion problems from hot acidic gases are reviewed. Problems surfacing during trial runs prior to radioactive operations are discussed.

Vormelker, P.R.; Jenkins, C.F.; Burns, H.H.

1997-01-01

314

Representing Clarity: Using Universal Design Principles to Create Effective Hybrid Course Learning Materials  

ERIC Educational Resources Information Center

This article describes how the author applied principles of universal design to hybrid course materials to increase student understanding and, ultimately, success. Pulling the three principles of universal design--consistency, color, and icon representation--into the author's Blackboard course allowed her to change the types of reading skills…

Spiegel, Cheri Lemieux

2012-01-01

315

On the Design of Radar Absorbing Materials Using Left-Handed Transmission Line  

Microsoft Academic Search

A novel radar absorbing material is designed by combining a high impedance surface and a transitional structure. The high impedance surface consists of a two-dimensional periodic array of unit cells that are implemented using a left-handed transmission line printed on a dielectric substrate with lumped elements. A transition between free space and the vertically placed microstrip line is designed using

Hang Wang; Wei Tang; Zhongxiang Shen

2007-01-01

316

Application of an energy-based model for the optimal design of structural materials and topology  

Microsoft Academic Search

This paper describes an implementation of recent developments in modelling for the design of continuum structures into a general program for computational solution of such problems. In the basic model, the unrestricted material tensor appears as the design variable. The algorithm for this program is presented and the method of solution is described. The approach is applicable to predict both

J. Du; J. E. Taylor

2002-01-01

317

The synergistic effects of slip ring-brush design and materials  

NASA Technical Reports Server (NTRS)

The design, fabrication, and subsequent testing of four power slip rings for synchronous orbit application are described. The synergistic effects of contact materials and slip ring-brush design are studied by means of frequent and simultaneous recording of friction, wear, and electrical noise. Data generated during the test period are presented along with post test analysis data.

Lewis, N. E.; Cole, S. R.; Glossbrenner, E. W.

1974-01-01

318

Site layout and balance of plant design for an accelerator-driven materials processing complex  

NASA Astrophysics Data System (ADS)

High energy proton beam accelerators are under consideration for use in radioisotope production, surplus weapons material destruction, radioactive waste transmutation, and thorium-based energy conversion cycles. While there are unique aspects to each of these applications that must be accommodated in the design of the associated facility, all share a set of fundamental characteristics that in large measure dictate the site layout features and many balance-of-plant (BOP) design requirements found to be common to all. This paper defines these key design determinants and goes on to discuss the manner in which they have been accommodated in the pre-conceptual design for a particular materials production application. An estimate of the costs associated with this BOP design is also presented with the aim of guiding future evaluations where the basic plant designs are similar to that of this specific case.

Cunliffe, John; Taussig, Robert; Ghose, Sunil; Guillebaud, Louis

1995-09-01

319

Design of materials with extreme thermal expansion using a three-phase topology optimization method  

NASA Astrophysics Data System (ADS)

We show how composites with extremal or unusual thermal expansion coefficients can be designed using a numerical topology optimization method. The composites are composed of two different material phases and void. The optimization method is illustrated by designing materials having maximum thermal expansion, zero thermal expansion, and negative thermal expansion. Assuming linear elasticity, it is shown that materials with effective negative thermal expansion coefficients can be obtained by mixing two phases with positive thermal expansion coefficients and void. We also show that there is no mechanistic relationship between negative thermal expansion and negative Poisson's ratio.

Sigmund, Ole; Torquato, Salvatore

1997-02-01

320

Effects of Materials Parameters and Design Details on the Fatigue of Composite Materials for Wind Turbine Blades  

SciTech Connect

This paper presents an analysis of the results of nine years of fatigue testing represented in the USDOE/Montana State University (DOE/MSU) Composite Materials Fatigue Database. The focus of the program has been to explore a broad range of glass-fiber-based materials parameters encompassing over 4500 data points for 130 materials systems. Significant trends and transitions in fatigue resistance are shown as the fiber content and fabric architecture are varied. The effects of structural details including ply drops, bonded stiffeners, and other geometries that produce local variations in fiber packing and geometry are also described. Fatigue tests on composite beam structures are then discussed; these show generally good correlation with coupon fatigue data in the database. Goodman diagrams for fatigue design are presented, and their application to predicting the service lifetime of blades is described.

Mandell, J.F.; Samborsky, D.D.; Sutherland, H.J.

1999-03-04

321

On the design of structural components using materials with time-dependent properties  

NASA Technical Reports Server (NTRS)

The application of the elastic-viscoelastic correspondence principle is presented as a design tool for structural design engineers for composite material applications. The classical problem of cantilever beams is used as the illustration problem. Both closed-form and approximate numerical solutions are presented for several different problems. The application of the collocation method is presented as a viable and simple design tool to determine the time-dependent behavior and response of viscoelastic composite beams under load.

Rodriguez, Pedro I.

1993-01-01

322

High-temperature mechanical and material design for SiC composites  

NASA Astrophysics Data System (ADS)

Silicon carbide (SiC) fiber reinforced composites (FRCs) are strong potential candidate structural and high heat flux materials for fusion reactors. A concise discussion of the main material and design issues related to the use of SiC FRCs as structural materials in future fusion systems is given in this paper. The status of material processing of SiC/SiC composites is first reviewed. The advantages and shortcomings of the leading processing technology, known as chemical vapor infiltration are particularly highlighted. A brief outline of the design-relevant physical, mechanical, and radiation data base is then presented. SiC/SiC FRCs possess the advantage of increased apparent toughness under mechanical loading conditions. This increased toughness, however, is associated with the nucleation and propagation of small crack patterns in the structure. Design approaches and failure criteria under these conditions are discussed.

Ghoniem, Nasr M.

1992-09-01

323

Materials, Processes and Manufacturing in Ares 1 Upper Stage: Integration with Systems Design and Development  

NASA Technical Reports Server (NTRS)

Ares I Crew Launch Vehicle Upper Stage is designed and developed based on sound systems engineering principles. Systems Engineering starts with Concept of Operations and Mission requirements, which in turn determine the launch system architecture and its performance requirements. The Ares I-Upper Stage is designed and developed to meet these requirements. Designers depend on the support from materials, processes and manufacturing during the design, development and verification of subsystems and components. The requirements relative to reliability, safety, operability and availability are also dependent on materials availability, characterization, process maturation and vendor support. This paper discusses the roles and responsibilities of materials and manufacturing engineering during the various phases of Ares IUS development, including design and analysis, hardware development, test and verification. Emphasis is placed how materials, processes and manufacturing support is integrated over the Upper Stage Project, both horizontally and vertically. In addition, the paper describes the approach used to ensure compliance with materials, processes, and manufacturing requirements during the project cycle, with focus on hardware systems design and development.

Bhat, Biliyar N.

2008-01-01

324

The halogen bond in the design of functional supramolecular materials: recent advances.  

PubMed

Halogen bonding is an emerging noncovalent interaction for constructing supramolecular assemblies. Though similar to the more familiar hydrogen bonding, four primary differences between these two interactions make halogen bonding a unique tool for molecular recognition and the design of functional materials. First, halogen bonds tend to be much more directional than (single) hydrogen bonds. Second, the interaction strength scales with the polarizability of the bond-donor atom, a feature that researchers can tune through single-atom mutation. In addition, halogen bonds are hydrophobic whereas hydrogen bonds are hydrophilic. Lastly, the size of the bond-donor atom (halogen) is significantly larger than hydrogen. As a result, halogen bonding provides supramolecular chemists with design tools that cannot be easily met with other types of noncovalent interactions and opens up unprecedented possibilities in the design of smart functional materials. This Account highlights the recent advances in the design of halogen-bond-based functional materials. Each of the unique features of halogen bonding, directionality, tunable interaction strength, hydrophobicity, and large donor atom size, makes a difference. Taking advantage of the hydrophobicity, researchers have designed small-size ion transporters. The large halogen atom size provided a platform for constructing all-organic light-emitting crystals that efficiently generate triplet electrons and have a high phosphorescence quantum yield. The tunable interaction strengths provide tools for understanding light-induced macroscopic motions in photoresponsive azobenzene-containing polymers, and the directionality renders halogen bonding useful in the design on functional supramolecular liquid crystals and gel-phase materials. Although halogen bond based functional materials design is still in its infancy, we foresee a bright future for this field. We expect that materials designed based on halogen bonding could lead to applications in biomimetics, optics/photonics, functional surfaces, and photoswitchable supramolecules. PMID:23805801

Priimagi, Arri; Cavallo, Gabriella; Metrangolo, Pierangelo; Resnati, Giuseppe

2013-11-19

325

The Halogen Bond in the Design of Functional Supramolecular Materials: Recent Advances  

PubMed Central

Halogen bonding is an emerging noncovalent interaction for constructing supramolecular assemblies. Though similar to the more familiar hydrogen bonding, four primary differences between these two interactions make halogen bonding a unique tool for molecular recognition and the design of functional materials. First, halogen bonds tend to be much more directional than (single) hydrogen bonds. Second, the interaction strength scales with the polarizability of the bond-donor atom, a feature that researchers can tune through single-atom mutation. In addition, halogen bonds are hydrophobic whereas hydrogen bonds are hydrophilic. Lastly, the size of the bond-donor atom (halogen) is significantly larger than hydrogen. As a result, halogen bonding provides supramolecular chemists with design tools that cannot be easily met with other types of noncovalent interactions and opens up unprecedented possibilities in the design of smart functional materials. This Account highlights the recent advances in the design of halogen-bond-based functional materials. Each of the unique features of halogen bonding, directionality, tunable interaction strength, hydrophobicity, and large donor atom size, makes a difference. Taking advantage of the hydrophobicity, researchers have designed small-size ion transporters. The large halogen atom size provided a platform for constructing all-organic light-emitting crystals that efficiently generate triplet electrons and have a high phosphorescence quantum yield. The tunable interaction strengths provide tools for understanding light-induced macroscopic motions in photoresponsive azobenzene-containing polymers, and the directionality renders halogen bonding useful in the design on functional supramolecular liquid crystals and gel-phase materials. Although halogen bond based functional materials design is still in its infancy, we foresee a bright future for this field. We expect that materials designed based on halogen bonding could lead to applications in biomimetics, optics/photonics, functional surfaces, and photoswitchable supramolecules.

2013-01-01

326

Elementary Students' Learning of Materials Science Practices Through Instruction Based on Engineering Design Tasks  

NASA Astrophysics Data System (ADS)

Materials science, which entails the practices of selecting, testing, and characterizing materials, is an important discipline within the study of matter. This paper examines how third grade students' materials science performance changes over the course of instruction based on an engineering design challenge. We conducted a case study of nine students who participated in engineering design-based science instruction with the goal of constructing a stable, quiet, thermally comfortable model house. The learning outcome of materials science practices was assessed by clinical interviews conducted before and after the instruction, and the learning process was assessed by students' workbooks completed during the instruction. The interviews included two materials selection tasks for designing a sturdy stepstool and an insulated pet habitat. Results indicate that: (1) students significantly improved on both materials selection tasks, (2) their gains were significantly positively associated with the degree of completion of their workbooks, and (3) students who were highly engaged with the workbook's reflective record-keeping tasks showed the greatest improvement on the interviews. These findings suggest the important role workbooks can play in facilitating elementary students' learning of science through authentic activity such as engineering design.

Wendell, Kristen Bethke; Lee, Hee-Sun

2010-12-01

327

The effect of new priorities and new materials on residential refrigerator design  

SciTech Connect

Increasing energy-efficiency requirements, combined with environmental considerations, have resulted in designs for domestic refrigerators that incorporate new thermal insulating materials. The first series of tests of these materials have been sufficiently promising that incorporation of vacuum insulations if likely within the next several years. Initial designs will probably use a combination of vacuum insulations and foam; in future designs, major parts consolidation will be possible using structural and other characteristics of the new panel assemblies. Given optimization of the refrigerator thermal envelope according to life-cycle costs, energy use by refrigerators could be greatly reduced; refrigerators could lose their significance as a major component in residential energy-use. Possible forms in which these new materials will be used are discussed, including alternatives for composite assembly and requirements for reliability and durability.

Benson, D.K.; Potter, T.F.

1992-08-01

328

Designing and Developing Online Materials for Molecular Biology: Building Online Programs for Science  

PubMed Central

A well-accepted form of educational training offered in molecular biology is internships in research laboratories. However, the number of available research laboratories severely limits access by most students. Addressing this need, the University of Hawaii launched a project to expand this model to include newly developed online training materials in addition to a hands-on laboratory experience. This paper explores the design and development process of the online learning materials. This case study looks at the roles of the instructional designer, multimedia specialist, and research faculty who were the subject matter experts. The experiences of the design teams are shared in an effort to gain insight on how the collaborative efforts of the project group led to a successful deployment of the online learning materials.

Boulay, Rachel

2013-01-01

329

Design of advanced porous graphene materials: from graphene nanomesh to 3D architectures.  

PubMed

In order to make full utilization of the high intrinsic surface area of graphene, recently, porous graphene materials including graphene nanomesh, crumpled graphene and graphene foam, have attracted tremendous attention and research interest, owing to their exceptional porous structure (high surface area, and high pore volume) in combination with the inherent properties of graphene, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Interestingly, porous graphene materials and their derivatives have been explored in a wide range of applications in the fields of electronic and photonic devices, energy storage, gas separation/storage, oil absorption and sensors. This article reviews recent progress in the synthesis, characterization, properties, and applications of porous graphene materials. We aim to highlight the importance of designing different porous structures of graphene to meet future challenges, and the trend on future design of porous graphene materials is analyzed. PMID:24301688

Jiang, Lili; Fan, Zhuangjun

2014-02-21

330

Bioactive ceramic-based materials with designed reactivity for bone tissue regeneration  

PubMed Central

Bioactive ceramics have been used clinically to repair bone defects owing to their biological affinity to living bone; i.e. the capability of direct bonding to living bone, their so-called bioactivity. However, currently available bioactive ceramics do not satisfy every clinical application. Therefore, the development of novel design of bioactive materials is necessary. Bioactive ceramics show osteoconduction by formation of biologically active bone-like apatite through chemical reaction of the ceramic surface with surrounding body fluid. Hence, the control of their chemical reactivity in body fluid is essential to developing novel bioactive materials as well as biodegradable materials. This paper reviews novel bioactive materials designed based on chemical reactivity in body fluid.

Ohtsuki, Chikara; Kamitakahara, Masanobu; Miyazaki, Toshiki

2009-01-01

331

Materials and mechanical design analysis of boron carbide reactor safety rods. Final report  

SciTech Connect

The purpose of this task was to analyze the materials and mechanical design bases for the new boron carbide safety rod. These analyses included examination of the irradiation response of the materials, chemical compatibility of component materials, moisture considerations for the boron carbide pellets and susceptibility of the rod to corrosion under reactor environmental conditions. A number of issues concerning the mechanical behavior were also addressed. These included: safety rod dynamic response in scram scenarios, flexibility and mishandling behavior, and response to thermal excursions associated with gamma heating. A surveillance program aimed at evaluating the integrity of the safety rods following actual operating conditions and justifying life extension for the rods was also proposed. Based on the experimental testing and analyses associated with this task, it is concluded that the boron carbide safety rod design meets the materials and mechanical criteria for successful operational performance.

Marra, J.C.

1992-04-01

332

Materials and mechanical design analysis of boron carbide reactor safety rods  

SciTech Connect

The purpose of this task was to analyze the materials and mechanical design bases for the new boron carbide safety rod. These analyses included examination of the irradiation response of the materials, chemical compatibility of component materials, moisture considerations for the boron carbide pellets and susceptibility of the rod to corrosion under reactor environmental conditions. A number of issues concerning the mechanical behavior were also addressed. These included: safety rod dynamic response in scram scenarios, flexibility and mishandling behavior, and response to thermal excursions associated with gamma heating. A surveillance program aimed at evaluating the integrity of the safety rods following actual operating conditions and justifying life extension for the rods was also proposed. Based on the experimental testing and analyses associated with this task, it is concluded that the boron carbide safety rod design meets the materials and mechanical criteria for successful operational performance.

Marra, J.C.

1992-04-01

333

Virtual Welded-Joint Design Integrating Advanced Materials and Processing Technologies  

SciTech Connect

The primary goal of this project is to increase the fatigue life of a welded-joint by 10 times and to reduce energy use by 25% through product performance and productivity improvements using an integrated modeling approach. The fatigue strength of a welded-joint is currently the bottleneck to design high performance and lightweight welded structures using advanced materials such as high strength steels. In order to achieve high fatigue strength in a welded-joint it is necessary to manage the weld bead shape for lower stress concentration, produce preferable residual stress distribution, and obtain the desired microstructure for improved material toughness and strength. This is a systems challenge that requires the optimization of the welding process, the welding consumable, the base material, as well as the structure design. The concept of virtual welded-joint design has been proposed and established in this project. The goal of virtual welded-joint design is to develop a thorough procedure to predict the relationship of welding process, microstructure, property, residual stress, and the ultimate weld fatigue strength by a systematic modeling approach. The systematic approach combines five sub-models: weld thermal-fluid model, weld microstructure model, weld material property model, weld residual stress model, and weld fatigue model. The systematic approach is thus based on interdisciplinary applied sciences including heat transfer, computational fluid dynamics, materials science, engineering mechanics, and material fracture mechanics. The sub-models are based on existing models with further development. The results from modeling have been validated with critical experiments. The systematic modeling approach has been used to design high fatigue resistant welds considering the combined effects of weld bead geometry, residual stress, microstructure, and material property. In particular, a special welding wire has been developed in this project to introduce compressive residual stress at weld toe for weld fatigue resistance.

Yang, Z.; Dong, P.; Liu, S.; Babu, S.; Olson, G.; DebRoy, T.

2005-04-15

334

Computer-aided design of nanostructured materials containing trisaza-bridged [60]fullerene  

NASA Astrophysics Data System (ADS)

A novel fullerene-based building block for the synthesis of nanostructured materials has been designed with the aid of electronic structure theory calculations and molecular modeling. The building block consists of four trisaza-bridged C 60 fullerene molecules linked to a central cubane (C 8) unit. Each C 60 unit is located on the vertex of a tetrahedron with edge of 2.2 nm. One possible packing mode of the building blocks to yield the nanostructured material is suggested.

Pichierri, Fabio

2005-11-01

335

Micro\\/nano materials testing for reliable design of MEMS\\/NEMS  

Microsoft Academic Search

This paper describes evaluation techniques of mechanical properties for MEMS\\/NEMS materials. Micro\\/Nano Mechanics Laboratory (MNML) in Ritsumeikan, have so far been established several kinds of micro\\/nano material testing methods for structural design of MEMS\\/NEMS. Nanoscale bending testing based on an AFM technique was developed to reveal specimen size and temperature effects on elastic-inelastic properties of self-supported single crystal silicon (SCS)

Y. Isono

2004-01-01

336

Materials and design experience in a slurry-fed electric glass melter  

SciTech Connect

The design of a slurry-fed electric gas melter and an examination of the performance and condition of the construction materials were completed. The joule-heated, ceramic-lined melter was constructed to test the applicability of materials and processes for high-level waste vitrification. The developmental Liquid-Fed Ceramic Melter (LFCM) was operated for three years with simulated high-level waste and was subjected to conditions more severe than those expected for a nuclear waste vitrification plant.

Barnes, S.M.; Larson, D.E.

1981-08-01

337

Sustainable manufacturing: Effect of material selection and design on the environmental impact in the manufacturing process  

NASA Astrophysics Data System (ADS)

The environmental impact of a manufacturing process is also dependent on the selection of the material and design of a product. This is because the manufacturing of a product is directly connected to the amount of carbon emitted in consuming the electrical energy for that manufacturing process. The difference in the general properties of materials such as strength, hardness and impact will have significant effect on the power consumption of the machine used to complete the product. In addition the environmental impact can also be reduced if the proposed designs use less material. In this study, an LCA tool called Eco-It is used. Evaluate the environmental impact caused by manufacturing simple jig. A simple jig with 4 parts was used as a case study. Two experiments were carried out. The first experiment was to study the environmental effects of different material, and the second experiment was to study the environmental impact of different design. The materials used for the jig are Aluminium and mild steel. The results showed a decrease in the rate of carbon emissions by 60% when Aluminium is use instead from mild steel, and a decrease of 26% when the-design is modified.

Hazwan Syafiq Harun, Mohd; Taha, Zahari; Salaam, Hadi Abdul

2013-12-01

338

Stress distributions in maxillary central incisors restored with various types of post materials and designs.  

PubMed

Different dental post designs and materials affect the stability of restoration of a tooth. This study aimed to analyse and compare the stability of two shapes of dental posts (parallel-sided and tapered) made of five different materials (titanium, zirconia, carbon fibre and glass fibre) by investigating their stress transfer through the finite element (FE) method. Ten three-dimensional (3D) FE models of a maxillary central incisor restored with two different designs and five different materials were constructed. An oblique loading of 100N was applied to each 3D model. Analyses along the centre of the post, the crown-cement/core and the post-cement/dentine interfaces were computed, and the means were calculated. One-way ANOVAs followed by post hoc tests were used to evaluate the effectiveness of the post materials and designs (p=0.05). For post designs, the tapered posts introduced significantly higher stress compared with the parallel-sided post (p<0.05), especially along the centre of the post. Of the materials, the highest level of stress was found for stainless steel, followed by zirconia, titanium, glass fibre and carbon fibre posts (p<0.05). The carbon and glass fibre posts reduced the stress distribution at the middle and apical part of the posts compared with the stainless steel, zirconia and titanium posts. The opposite results were observed at the crown-cement/core interface. PMID:24834856

Madfa, A A; Kadir, M R Abdul; Kashani, J; Saidin, S; Sulaiman, E; Marhazlinda, J; Rahbari, R; Abdullah, B J J; Abdullah, H; Abu Kasim, N H

2014-07-01

339

Hierarchical bioactive materials for tissue reconstruction: Integrated design and manufacturing challenges  

NASA Astrophysics Data System (ADS)

Although the paradigm shift from synthetic implants and tissue grafts to regenerative-medicine-based tissue reconstruction has been promised for well over a decade, the reality has yet to emerge. A significant reason for this delay is that regenerative medicine reconstruction solutions involve complex systems in which bioresorbable materials are integrated with surface modifications delivering cells and growth factors. These systems must not only fill complex shapes and provide temporary mechanical function; they must deliver biologic factors that stimulate tissue growth in a controlled, safe, yet rapid manner. Finally, the materials should degrade on a timeline matched to the time it takes to grow tissues. As such, these material device systems are multifunctional and require design techniques that can address multifunctionality, coupled with multiple material manufacturing processes that can be integrated to achieve the design. In this paper, we review these design and manufacturing processes as well as the challenges to integrate these multiple design and manufacturing processes to engineer bioactive material devices.

Hollister, Scott J.

2011-04-01

340

Fundamentals of macro axial gradient index material engineering and optical design  

NASA Astrophysics Data System (ADS)

Homogeneous lens materials is characterized by an index of refraction and a point on the glass map nd equals f(vd). Gradient refractive index (GRIN) lenses have a spatially varying index and dispersion and are represented by a line on the glass map. GRIN lenses open the door to a wide variety of optical design applications incorporating entire lenses of axial gradient refractive material. Axial gradient materials essentially gives biaspheric behavior to lenses with spherical surfaces and exhibits a controlled gradient in both index and dispersion. Thus, the applications for this material range from simple singlet lens used for imaging laser light, in which spherical aberration is eliminated, to complex multielement lens systems, where improved overall performance is desired. The fusion/diffusion process that produces this material is surprisingly simple, repeatable, and applicable to mass production. The advantages of a GRIN technology coupled with the recent advances in material development and its accessibility in commercially available lens design programs provides optical designers with the opportunity to push the performance of optical systems farther than with conventional optics.

Manhart, Paul K.; Blankenbecler, Richard

1997-06-01

341

Corrosion performance of alternative steam-generator materials and designs. Volume 1. Summary of corrosion tests of alternative materials and designs in two model steam generators. Final report  

SciTech Connect

Corrosion results obtained from the post-test non-destructive and destructive examinations of two alternative-materials model steam generators are summarized and compared in this final report. The models operated under representative thermal and hydraulic and accelerated (high contaminant concentration) steam generator secondary water-chemistry conditions. One model was faulted with seawater to a level of 30 ppM chloride for 282 steaming days; the other model was faulted with concentrated, acidified (H/sub 2/SO/sub 4/) fresh water to a level of 40 ppM sulfate for 358 steaming days. Various support-plate and lattice-strip-support designs incorporated Types 347, 405, 409, and SCR-3 stainless steels; Alloys 600 and 690; and carbon steel. Heat-transfer-tube materials included Alloy 600 in various heat treated conditions, Alloy 690, and Alloy 800.

Krupowicz, J.J.; Rentler, R.M.

1983-07-01

342

Design and testing criteria for bipolar plate materials for PEM fuel cell applications  

SciTech Connect

Bipolar plates for proton exchange membrane (PEM) fuel cells are currently under development. These plates separate individual cells of the fuel cell stack, and thus must be sufficiently strong to support clamping forces, be electrically conducting, be fitted with flow channels for stack thermal control, be of a low permeability material to separate safely hydrogen and oxygen feed streams, be corrosion resistant, and be fitted with distribution channels to transfer the feed streams over the plate surface. To date, bipolar plate costs dominate stack costs, and therefore future materials need to meet strict cost targets. A first step in the bipolar plate development program is an assessment of design constraints. Such constraints have been estimated and evaluated and are discussed here. Conclusions point to promising advanced materials, such as conductive, corrosion resistant coatings on metal substrates, as candidates for mass production of fuel cell bipolar plates. Possible candidate materials are identified, and testing procedures developed to determine suitability of various materials.

Borup, R.L.; Vanderborgh, N.E.

1995-05-01

343

Analysis of Photothermal Characterization of Layered Materials: Design of Optimal Experiments  

NASA Technical Reports Server (NTRS)

In this paper numerical calculations are presented for the steady-periodic temperature in layered materials and functionally-graded materials to simulate photothermal methods for the measurement of thermal properties. No laboratory experiments were performed. The temperature is found from a new Green s function formulation which is particularly well-suited to machine calculation. The simulation method is verified by comparison with literature data for a layered material. The method is applied to a class of two-component functionally-graded materials and results for temperature and sensitivity coefficients are presented. An optimality criterion, based on the sensitivity coefficients, is used for choosing what experimental conditions will be needed for photothermal measurements to determine the spatial distribution of thermal properties. This method for optimal experiment design is completely general and may be applied to any photothermal technique and to any functionally-graded material.

Cole, Kevin D.

2003-01-01

344

Design and measurement of a thin and light absorbing material for space applications  

NASA Astrophysics Data System (ADS)

This paper presents the design, realization and measurement of a thin lightweight absorbing material for space applications. Absorber design is based on high impedance surfaces loaded with resistors and known as a resistive high impedance surface (RHIS). The behavior of RHIS is analyzed at normal and oblique incidences for TE and TM polarizations. Prototypes have been realized and measured. Final design has a reflection coefficient less than 15 dB in S-Band (2-2.3 GHz) at normal incidence and till an angular dispersion of 40 for waves in TE polarization, and 35 for waves in TM polarization. Simulation results are validated by measurement.

Pinto, Yenny; Sarrazin, Julien; Lepage, Anne Claire; Begaud, Xavier; Capet, Nicolas

2014-05-01

345

Advanced composites structural concepts and materials technologies for primary aircraft structures: Design/manufacturing concept assessment  

NASA Technical Reports Server (NTRS)

Composite Wing and Fuselage Structural Design/Manufacturing Concepts have been developed and evaluated. Trade studies were performed to determine how well the concepts satisfy the program goals of 25 percent cost savings, 40 percent weight savings with aircraft resizing, and 50 percent part count reduction as compared to the aluminum Lockheed L-1011 baseline. The concepts developed using emerging technologies such as large scale resin transfer molding (RTM), automatic tow placed (ATP), braiding, out-of-autoclave and automated manufacturing processes for both thermoset and thermoplastic materials were evaluated for possible application in the design concepts. Trade studies were used to determine which concepts carry into the detailed design development subtask.

Chu, Robert L.; Bayha, Tom D.; Davis, HU; Ingram, J. ED; Shukla, Jay G.

1992-01-01

346

A new approach for optimizing the mechanical behavior of porous microstructures for porous materials by design  

Microsoft Academic Search

A high-fidelity generalized method of cells (HFGMC) model for the micromechanical behavior of porous and composite microstructures has been previously developed. Based on this model, a new approach has been developed to optimize porous microstructures for ‘porous materials by design’. This approach uses a combination of genetic algorithms (GA) (stochastic), coarse (periodic) and Newton–Raphson (gradient) optimization methods. In order to

Hugh A Bruck; Rivka Gilat; Jacob Aboudi; Alan L Gershon

2007-01-01

347

Design of advanced beams considering elasto-plastic behaviour of material  

NASA Astrophysics Data System (ADS)

The paper proposes a computational procedure for precise calculation of limit and ultimate or design loads, which must be carried by an advanced aviation beam, without permanent distortion and without rupture. Among several stress-strain curve representations, one that is suitable for a particular material is chosen for applied loads, yield, and failure load calculations, and then nonlinear analysis is performed.

Tolun, S.

1992-10-01

348

Color Research and Its Application to the Design of Instructional Materials.  

ERIC Educational Resources Information Center

Reviews color research and considers its implications for the design of instructional materials. Topics include physiological and psychological effects; color and learning, including attention, search tasks, retention and other objective measures, and non-objective measures; color and the cathode ray tube (CRT); and further research needs.…

Pett, Dennis; Wilson, Trudy

1996-01-01

349

The polymer blend technique as a method for designing fine carbon materials  

Microsoft Academic Search

The polymer blend technique is proposed as a method for designing fine carbon materials. In principle a blend consisting of polymers with and without carbon residue after heating is subjected to melt-spinning, stabilization and finally carbonization. A combination of two polymers and control of the blend texture are important for using the technique successfully. In this paper, three prepared fine

Denisa Hulicova; Asao Oya

2003-01-01

350

Design of broad-band radar-absorbing materials for large angles of incidence  

Microsoft Academic Search

A numerical technique, called the (modified) Powell method, is used to design radar-absorbing materials (RAMs) made up of several dielectric layers, usually on top of a conducting (ground) plane. The absorption of RF energy occurs mostly in the last layer. The other layers are used to match the wave impedance of the RAM to that of the medium on which

J. Perini; Lawrence S. Cohen

1993-01-01

351

Design of high performance missile structures utilizing advanced composite material technologies  

Microsoft Academic Search

The U.S. Army Aviation and Missile Command (AMCOM) has demonstrated the ability to develop and utilize advanced composite material technologies for the design and fabrication of hypervelocity kinetic energy missiles for the next generation of Army air defense and anti-tank applications. Future kinetic energy missiles must be small, fast, lethal, and maneuverable, which requires the delivery vehicles to operate in

J. R. Esslinger; R. N. Evans; G. W. Snyder

1999-01-01

352

Design parameters for the treatment of phenolic wastes by carbon columns (obtained from fertilizer waste material)  

Microsoft Academic Search

The waste slurry generated in fertilizer plants in India has been converted into a cheap carbonaceous adsorbent material. The practical applicability of this product has been investigated in the column operations and the mass transfer kinetic approach has been successfully used for the determination of various parameters necessary for designing a fixed bed adsorber. The value of breakthrough capacity is

Vinod K. Gupta; S. K. Srivastava; Renu Tyagi

2000-01-01

353

Facilities layout design optimization with single loop material flow path configuration  

Microsoft Academic Search

Here we formulate the facilities layout design optimization problem for a single loop material flow path configuration. Because of the NP-bard nature of the overall search space, we employ a genetic approach to sample the decomposed search spaces. In addition we analyse the following features of the problem: (1) we estimate lower bounds for the unidirectional flow problem along the

P. BANERJEE; Y. ZHOU

1995-01-01

354

Revised Procedural Guide For Designation Surveys of Ocean Dredged Material Disposal Sites  

National Technical Information Service (NTIS)

This procedural guide is a revision of that issued in 1981 and has been prepared to meet the needs of the Corps of Engineers in conducting surveys for the designation of ocean disposal sites for dredged material. Basic purposes of the guide are to provide...

B. J. Gallaway T. D. Wright W. E. Pequegnat

1990-01-01

355

Precision resistors: a review of material characteristics, resistor design, and construction practices  

Microsoft Academic Search

An understanding of the properties of resistance materials and of the effects on resistor characteristics of construction practice is necessary to assure optimum application. Reviewed are some of the characteristics of moderate-precision film resistors, the nature of the principal high performance resistance alloys and the design and construction of high-precision resistors. The effects of resistor termination and terminals are also

David W. Braudaway

1999-01-01

356

Incorporating 4MAT Model in Distance Instructional Material--An Innovative Design  

ERIC Educational Resources Information Center

In an attempt to improve the effectiveness of distance learning, the present study aims to introduce an innovative way of creating and designing distance learning instructional material incorporating Bernice McCarthy's 4MAT Model based on learning styles. According to McCarthy's theory, all students can learn effectively in a cycle of learning…

Nikolaou, Alexandra; Koutsouba, Maria

2012-01-01

357

Site layout and balance of plant design for an accelerator-driven materials processing complex  

Microsoft Academic Search

High energy proton beam accelerators are under consideration for use in radioisotope production, surplus weapons material destruction, radioactive waste transmutation, and thorium-based energy conversion cycles. While there are unique aspects to each of these applications that must be accommodated in the design of the associated facility, all share a set of fundamental characteristics that in large measure dictate the site

John Cunliffe; Robert Taussig; Sunil Ghose; Louis Guillebaud

1995-01-01

358

Design, Implementation, and Evaluation of GIS-Based Learning Materials in an Introductory Geoscience Course.  

ERIC Educational Resources Information Center

Investigates student learning that occurred with a Geographic Information Systems (GIS) based module on plate tectonics and geologic hazards. Examines factors in the design and implementation of the materials that impacted student learning. Reports positive correlations between student' spatial ability and performance. Includes 17 references.…

Hall-Wallace, Michelle K.; McAuliffe, Carla M.

2002-01-01

359

Optimal nondestructive test design for maximum sensitivity and minimal redundancy for applications in material characterization  

NASA Astrophysics Data System (ADS)

An approach to nondestructive test (NDT) design for material characterization and damage identification in structural components, and more generally in solid continua, is presented and numerically tested. The proposed NDT design approach is based on maximizing a measure of the sensitivity of the test responses to changes in the material properties of the structure while also maximizing a measure of the difference in the response components. As such, the optimally designed NDT provides significant improvement in the ability to solve subsequent inverse characterization problems by extracting the maximum amount of non-redundant information from the system to increase the inverse solution observability. The NDT design approach is theoretically able to include any and all possible design aspects, such as the placement of sensors and actuators and determination of actuation frequency, among others. Through simulated test problems based on the characterization of damage in aluminum structural components utilizing steady-state dynamic surface excitation and localized measurements of displacement, the proposed NDT design approach is shown to provide NDT designs with significantly higher measurement sensitivity as well as lower information redundancy when compared to alternate test approaches. More importantly, the optimized NDT methods are shown to provide consistent and significant improvement in the ability to accurately inversely characterize variations in the Young’s modulus distributions for the simulated test cases considered.

Notghi, Bahram; Brigham, John C.

2013-12-01

360

Design length scales for carbon nanotube photoabsorber based photovoltaic materials and devices  

NASA Astrophysics Data System (ADS)

Semiconducting carbon nanotubes are attractive materials for harvesting light in photovoltaic solar cells and photodetectors. A crucial aspect of designing efficient photovoltaic devices using nanotubes is minimizing the length scale for the absorption of light (LA) and maximizing the length scale across which excitons diffuse (LD) in fibers and films of these materials. In order to facilitate the optimization of these parameters, here we model how LA and LD are affected by nanotube bandgap polydispersity, inter-nanotube coupling, film disorder, orientation, and defects. Our models are guided by previous experimental measurements of optical absorption spectra and exciton inter-nanotube transfer rates made on isolated and bundled nanotubes in conjunction with kinetic Monte Carlo simulations. Our results provide criteria for materials selection and the design of efficient carbon nanotube-based light harvesting devices, in various architectures.

Wu, Meng-Yin; Jacobberger, Robert M.; Arnold, Michael S.

2013-05-01

361

Design, fabrication, and modification of nanostructured semiconductor materials for environmental and energy applications.  

PubMed

Considerable effort has been made to design, fabricate, and manipulate nanostructured materials by innovative approaches. The precise control of nanoscale structures will pave the way not only for elucidating unique size/shape-dependent physicochemical properties but also for realizing new applications in science and technology. Nanotechnology offers unprecedented opportunities for improving our daily lives and the environment in which we live. This review mainly describes our recent progress in the design, fabrication, and modification of nanostructured semiconductor materials for environmental applications. Their potential applications in the field of energy are briefly introduced. The scope of this article covers a variety of semiconductor materials, focusing particularly on TiO(2)-based nanostructures (e.g., pure, doped, coupled, nanoporous, mesoporous, hierarchically porous, and ordered mesoporous TiO(2)). The preparation of nanoparticles, hierarchical nanoarchitectures, thin films, and single crystals by sol-gel, microemulsion, hydrothermal, sonochemical, microwave, photochemical, and nanocasting methods is discussed. PMID:19736984

Hu, Xianluo; Li, Guisheng; Yu, Jimmy C

2010-03-01

362

Computer simulations of realistic microstructures: Implications for simulation-based materials design  

NASA Astrophysics Data System (ADS)

The conventional route of materials development typically involves fabrication of numerous batches of specimens having a range of different microstructures generated via variations of process parameters and measurements of relevant properties of these microstructures to identify the combination of processing conditions that yield the material having desired properties. Clearly, such a trial and error based materials development methodology is expensive, time consuming, and inefficient. Consequently, it is of interest to explore alternate strategies that can lead to a decrease in the cost and time required for development of advanced materials such as composites. Availability of powerful and inexpensive computational power and progress in computational materials science permits advancement of modeling and simulations assisted materials design methodology that may require fewer experiments, and therefore, lower cost and time for materials development. The key facets of such a technology would be computational tools for (i) creating models to generate computer simulated realistic microstructures; (ii) capturing the process-microstructure relationship using these models; and (iii) implementation of simulated microstructures in the computational models for materials behavior. Therefore, development of a general and flexible methodology for simulations of realistic microstructures is crucial for the development of simulations based materials design and development technology. Accordingly, this research concerns development of such a methodology for simulations of realistic microstructures based on experimental quantitative stereological data on few microstructures that can capture relevant details of microstructural geometry (including spatial clustering and second phase particle orientations) and its variations with process parameters in terms of a set of simulation parameters. The interpolation and extrapolation of the simulation parameters can then permit generation of atlas of "virtual" microstructures that covers the complete range of variations of processing conditions of interest. These simulated and "virtual" microstructures can then be used in the micromechanical models such as FEM to analyze their constitutive properties.

Singh, Harpreet

363

Space shuttle seal material and design development for earth storable propellant systems  

NASA Technical Reports Server (NTRS)

The results of a program to investigate and characterize seal materials suitable for space shuttle storable propellant systems are given. Two new elastomeric materials were identified as being potentially superior to existing state-of-the art materials for specific sealing applications. These materials were AF-E-124D and AF-E-411. AF-E-124D is a cured perfluorinated polymer suitable for use with dinitrogen tetroxide oxidizer, and hydrazine base fuels. AF-E-411 is an ethylene propylene terpolymer material for hydrazine base fuel service. Data are presented relative to low and high temperature characteristics as well as propellant exposure effects. Types of data included are: mechanical properties, stress strain curves, friction and wear characteristics, compression set and permeability. Sealing tests with a flat poppet-seal valve were conducted for verification of sealing capability. A bibliography includes over 200 references relating to seal design or materials and presents a concise tabulation of the more useful seal design data sources.

1973-01-01

364

Specimen Designs for Testing Advanced Aeropropulsion Materials Under In-Plane Biaxial Loading  

NASA Technical Reports Server (NTRS)

A design study was undertaken to develop specimen designs for testing advanced aeropropulsion materials under in-plane biaxial loading. The focus of initial work was on developing a specimen design suitable for deformation and strength tests to be conducted under monotonic loading. The type of loading initially assumed in this study was the special case of equibiaxial, tensile loading. A specimen design was successfully developed after a lengthy design and optimization process with overall dimensions of 12 by 12 by 0.625 in., and a gage area of 3.875 by 3.875 by 0.080 in. Subsequently, the scope of the work was extended to include the development of a second design tailored for tests involving cyclic loading. A specimen design suitably tailored to meet these requirements was successfully developed with overall dimensions of 12 by 12 by 0.500 in. and a gage area of 2.375 by 2.375 by 0.050 in. Finally, an investigation was made to determine whether the specimen designs developed in this study for equibiaxial, tensile loading could be used without modification to investigate general forms of biaxial loading. For best results, it was concluded that specimen designs need to be optimized and tailored to meet the specific loading requirements of individual research programs.

Ellis, John R.; Abul-Aziz, Ali

2003-01-01

365

A new design of cemented stem using functionally graded materials (FGM).  

PubMed

One of the most frequent complications of total hip replacement (THR) is aseptic loosening of femoral component which is primarily due to changes of post-operative stress distribution pattern with respect to intact femur. Stress shielding of the femur is known to be a principal factor in aseptic loosening of hip replacements. Many designers show that a stiff stem shields the surrounding bone from mechanical loading causing stress shielding. Others show that reducing stem stiffness promotes higher proximal interface shear stress which increases the risk of proximal interface failure. Therefore, the task of this investigation is to solve these conflicting problems appeared in the cemented total hip replacement. The finite element method and optimization technique are used in order to find the optimal stem material which gives the optimal available stress distribution between the proximal medial femoral bone and the cement mantle interfaces. The stem is designed using the concept of functionally graded material (FGM) instead of using the conventional most common used stem material. The results showed that there are four feasible solutions from the optimization runs. The best of these designs is to use a cemented stem graded from titanium at the upper stem layer to collagen at the lower stem layer. This new cemented stem design completely eliminates the stress shielding problem at the proximal medial femoral region. The stress shielding using the cemented functionally graded stem is reduced by 98% compared to titanium stem. PMID:24840196

Hedia, H S; Aldousari, S M; Abdellatif, A K; Fouda, N

2014-01-01

366

An Analysis of Teaching Competence in Science Teachers Involved in the Design of Context-based Curriculum Materials  

Microsoft Academic Search

The committees for the current Dutch context-based innovation in secondary science education employed teachers to design context-based curriculum materials. A study on the learning of science teachers in design teams for context-based curriculum materials is presented in this paper. In a correlation study, teachers with (n?=?25 and 840 students) and without (n?=?8 and 184 students) context-based curriculum material design experience

Lesley G. A. de Putter-Smits; Ruurd Taconis; Wim Jochems; Jan Van Driel

2012-01-01

367

Design, fabrication, and evaluation of high frequency, single-element transducers incorporating different materials.  

PubMed

The performance of high frequency, single-element transducers depends greatly on the mechanical and electrical properties of the piezoelectric materials used. This study compares the design and performance of transducers incorporating different materials. The materials investigated include 1-3 lead zirconate titanate (PZT) fiber composite, lead titanate (PbTiO3) ceramic, poly(vinylidene fluoride) (PVDF) film, and lithium niobate (LiNbO3) single crystal. All transducers were constructed with a 3-mm aperture size and an f-number between 2 and 3. Backing and matching materials were selected based on design goals and fabrication limitations. A simplified coaxial cable tuning method was employed to match the transducer impedance to 50 ohms for the PZT fiber composite and PbTiO3 ceramic transducers. Transducers were tested for two-way loss and -6 dB bandwidth using the pulse/echo response from a flat quartz target. Two-way loss varied from 21 to 46 dB, and bandwidths measured were in the range from 47 to 118%. In vitro ultrasonic backscatter microscope (UBM) images of an excised human eye were obtained for each device and used to compare imaging performance. Both press-focusing and application of a lens proved to be useful beam focusing methods for high frequency. Under equal gain schemes, the LiNbO3 and PbTiO3 transducers provided better image contrast than the other materials. PMID:11887795

Snook, Kevin A; Zhao, Jian-Zhong; Alves, Carlos H F; Cannata, Jonathan M; Chen, Wo-Hsing; Meyer, Richard J; Ritter, Timothy A; Shung, K Kirk

2002-02-01

368

THE IMPACT OF MATERIAL AND DESIGN CRITERIA ON THE ASSESSMENT OF NEGLIGIBLE CREEP  

SciTech Connect

Two of the proposed High Temperature Gas Reactors (HTGRs) under consideration for a demonstration plant have the design object of avoiding creep effects during normal operation. The goal of negligible creep could have different interpretations depending upon what failure modes are considered and associated criteria for avoiding the effects of creep. This paper addresses the criteria for negligible creep in Subsection NH of Section III of the ASME B&PV Code, other international design codes and some currently suggested criteria modifications and their impact on permissible operating temperatures for various reactor pressure vessel materials. There are a number of other considerations for the selection of vessel material besides avoiding creep effects. Of particular interest for this review are (1) the material s allowable stress level and impact on wall thickness (the goal being to minimize required wall thickness) and (2) ASME Code approval (inclusion as a permitted material in the relevant Section and Subsection of interest) to expedite regulatory review and approval. The application of negligible creep criteria to two of the candidate materials, SA533 and Mod 9Cr-1Mo, and to a potential alternate, normalized and tempered 2 Cr-1Mo, are illustrated and the relative advantages and disadvantages are discussed.

Sham, Sam [ORNL; Jetter, Robert I [Consultant; Swindeman, Robert W [Consultant

2009-01-01

369

Improved design of cementless hip stems using two-dimensional functionally graded materials.  

PubMed

Increasingly, it is acknowledged that bone resorption around cementless hip implants may cause future problems. The solution is frequently sought in reducing implant stiffness. However, this confronts the designer with a true design conflict: how to reduce the stiffness without excessively loading the proximal bone/prosthesis interface? The aim of this work is to improve the design of cementless hip stem material, using two-dimensional (2D) functionally graded material (FGM) concept in order to solve the above problems. Two models were used in this analysis, using three materials with different elastic moduli, E(1), E(2), and E(3). In model I, the elastic moduli E(1) and E(2) gradually change along the upper stem surface, while E(3) is maintained constant along all the lower surface of the stem. However, in model II, the elastic moduli E(1) and E(2) gradually change along the lower stem surface, while E(3) is maintained constant all along the upper stem surface. It is found that the recommended model is model I, which has three distinct materials of hydroxyapatite, Bioglass, and collagen. The recommended design of 2D FGM is expected to reduce the stress shielding by 91% and 12%, respectively, compared with titanium stem and model II of FGM. It is found that this new design reduces the maximum interface shear stress at the lateral and medial sides of the femur by about 50%, compared with titanium stem. Furthermore, the maximum interface shear stress is reduced by about 17% and 11% at the lateral and medial sides of the femur, respectively, compared with that of model II of FGM. PMID:16506171

Hedia, H S; Shabara, M A N; El-Midany, T T; Fouda, N

2006-10-01

370

In-Vessel Coil Material Failure Rate Estimates for ITER Design Use  

SciTech Connect

The ITER international project design teams are working to produce an engineering design for construction of this large tokamak fusion experiment. One of the design issues is ensuring proper control of the fusion plasma. In-vessel magnet coils may be needed for plasma control, especially the control of edge localized modes (ELMs) and plasma vertical stabilization (VS). These coils will be lifetime components that reside inside the ITER vacuum vessel behind the blanket modules. As such, their reliability is an important design issue since access will be time consuming if any type of repair were necessary. The following chapters give the research results and estimates of failure rates for the coil conductor and jacket materials to be used for the in-vessel coils. Copper and CuCrZr conductors, and stainless steel and Inconel jackets are examined.

L. C. Cadwallader

2013-01-01

371

Los Alamos National Laboratory new generation standard nuclear material storage container - the SAVY4000 design  

SciTech Connect

Incidents involving release of nuclear materials stored in containers of convenience such as food pack cans, slip lid taped cans, paint cans, etc. has resulted in defense board concerns over the lack of prescriptive performance requirements for interim storage of nuclear materials. Los Alamos National Laboratory (LANL) has shared in these incidents and in response proactively moved into developing a performance based standard involving storage of nuclear material (RD003). This RD003 requirements document has sense been updated to reflect requirements as identified with recently issued DOE M 441.1-1 'Nuclear Material Packaging Manual'. The new packaging manual was issued at the encouragement of the Defense Nuclear Facilities Safety Board with a clear directive for protecting the worker from exposure due to loss of containment of stored materials. The Manual specifies a detailed and all inclusive approach to achieve a high level of protection; from package design & performance requirements, design life determinations of limited life components, authorized contents evaluations, and surveillance/maintenance to ensure in use package integrity over time. Materials in scope involve those stored outside an approved engineered-contamination barrier that would result in a worker exposure of in excess of 5 rem Committed Effective Does Equivalent (CEDE). Key aspects of meeting the challenge as developed around the SAVY-3000 vented storage container design will be discussed. Design performance and acceptance criteria against the manual, bounding conditions as established that the user must ensure are met to authorize contents in the package (based upon the activity of heat-source plutonium (90% Pu-238) oxide, which bounds the requirements for weapons-grade plutonium oxide), interface as a safety class system within the facility under the LANL plutonium facility DSA, design life determinations for limited life components, and a sense of design specific surveillance program implementation as LANL moves forward into production and use of the SAVY-3000 will all be addressed. The SAVY-3000 is intended as a work horse package for the DOE complex as a vented storage container primarily for plutonium in solid form.

Stone, Timothy Amos [Los Alamos National Laboratory

2010-01-01

372

Design Features and Capabilities of the First Materials Science Research Rack  

NASA Technical Reports Server (NTRS)

The First Materials Science Research Rack (MSRR-1) aboard the International Space Station (ISS) will offer many unique capabilities and design features to facilitate a wide range of materials science investigations. The initial configuration of MSRR-1 will accommodate two independent Experiment Modules (EMS) and provide the capability for simultaneous on-orbit processing. The facility will provide the common subsystems and interfaces required for the operation of experiment hardware and accommodate telescience capabilities. MSRR1 will utilize an International Standard Payload Rack (ISPR) equipped with an Active Rack Isolation System (ARIS) for vibration isolation of the facility.

Pettigrew, P. J.; Lehoczky, S. L.; Cobb, S. D.; Holloway, T.; Kitchens, L.

2003-01-01

373

Constrained self-consistent field method revisited toward theoretical designs of functional materials under external field  

NASA Astrophysics Data System (ADS)

This Letter explores the potential utility of the constrained self-consistent field (CSCF) method as an efficient methodology for estimating the external fields that reproduce desired physical quantities. Using the fact that a Lagrange multiplier introduced in CSCF corresponds to an external field (perturbation), numerical assessments of CSCF were carried out on the benzene molecule. The activation energies and critical electric fields that reverse the polarizations of the ferroelectric material tetrathiafulvalene-p-chloranil (TTF-CA) were efficiently estimated. The numerical assessments demonstrate the potential applicability of CSCF for the practical designs of materials possessing certain desired physical quantities induced by external fields.

Yamagata, Yuya; Imamura, Yutaka; Nakai, Hiromi

2012-03-01

374

Design and "As Flown" Radiation Environments for Materials in Low Earth Orbits  

NASA Technical Reports Server (NTRS)

The design estimate for the materials for the International Space Station (ISS) specified in SSP 30512 was a conservative estimate. The environment dose was over estimated. The materials originally qualified for approximately 10-15 years are anticipated to be acceptable for periods of up to 20-30 years based on SSP-30512 or 40-60 years based on 2x SSP-30512. This viewgraph presentation shows charts and graphs that review the altitude, the solar minimum and maximum, and the radiation exposure of other satellite, among other graphics.

Minow, Joseph I.; Altstatt, Richard L.; McWilliams, Brett; Koontz, Steven L.

2006-01-01

375

New Lithium Solid Electrolytes, Thio-Lisicon Materials Design Concept and Application to Solid State Battery  

NASA Astrophysics Data System (ADS)

Materials design concept of the new crystalline 'thio-LlSICON' (LIthium Superlonic CONductor) family was discussed. The thio-LISICON was found in the ternary systems, Li2S-MS2-M'xSy (M=Si, Ge, M'=P, Sb, Al, Zn, etc), and showed the highest conductivity of 2.2 × 10-3 Scm-1 at 25°C of any sintered ceramic, together with negligible electronic conductivity, high electrochemical stability, no reaction with lithium metal, and no phase transition up to 300°C. The advantage and disadvantage of the crystalline materials were discussed based on the ionic conduction, chemical stability and electrochemical potential window.

Kanno, Ryoji; Murayama, Masahiro; Sakamoto, Kazuyuki

2002-12-01

376

Material Control and Accounting Design Considerations for High-Temperature Gas Reactors  

SciTech Connect

The subject of this report is domestic safeguards and security by design (2SBD) for high-temperature gas reactors, focusing on material control and accountability (MC&A). The motivation for the report is to provide 2SBD support to the Next Generation Nuclear Plant (NGNP) project, which was launched by Congress in 2005. This introductory section will provide some background on the NGNP project and an overview of the 2SBD concept. The remaining chapters focus specifically on design aspects of the candidate high-temperature gas reactors (HTGRs) relevant to MC&A, Nuclear Regulatory Commission (NRC) requirements, and proposed MC&A approaches for the two major HTGR reactor types: pebble bed and prismatic. Of the prismatic type, two candidates are under consideration: (1) GA's GT-MHR (Gas Turbine-Modular Helium Reactor), and (2) the Modular High-Temperature Reactor (M-HTR), a derivative of Areva's Antares reactor. The future of the pebble-bed modular reactor (PBMR) for NGNP is uncertain, as the PBMR consortium partners (Westinghouse, PBMR [Pty] and The Shaw Group) were unable to agree on the path forward for NGNP during 2010. However, during the technology assessment of the conceptual design phase (Phase 1) of the NGNP project, AREVA provided design information and technology assessment of their pebble bed fueled plant design called the HTR-Module concept. AREVA does not intend to pursue this design for NGNP, preferring instead a modular reactor based on the prismatic Antares concept. Since MC&A relevant design information is available for both pebble concepts, the pebble-bed HTGRs considered in this report are: (1) Westinghouse PBMR; and (2) AREVA HTR-Module. The DOE Office of Nuclear Energy (DOE-NE) sponsors the Fuel Cycle Research and Development program (FCR&D), which contains an element specifically focused on the domestic (or state) aspects of SBD. This Material Protection, Control and Accountancy Technology (MPACT) program supports the present work summarized in this report, namely the development of guidance to support the consideration of MC&A in the design of both pebble-bed and prismatic-fueled HTGRs. The objective is to identify and incorporate design features into the facility design that will cost effectively aid in making MC&A more effective and efficient, with minimum impact on operations. The theft of nuclear material is addressed through both MC&A and physical protection, while the threat of sabotage is addressed principally through physical protection.

Trond Bjornard; John Hockert

2011-08-01

377

COMPARISON OF THE TRADITIONAL STRENGTH OF MATERIALS APPROACH TO DESIGN WITH THE FRACTURE MECHANICS APPROACH  

SciTech Connect

The objective of this activity is to show that the use of the traditional strength of materials approach to the drip shield and the waste package (WP) designs is bounding and appropriate when compared to the fracture mechanics approach. The scope of this activity is limited to determining the failure assessment diagrams for the two materials at issue: Ti-7 and Alloy 22. This calculation is intended for use in support of the license application design of the drip shield and the WP. This activity is associated with the drip shield and the WP designs. The activity evaluation for work package number P32 12234F2, included in ''Technical Work Plan for: Waste Package Design Description for LA'' (Ref. 1, p. A-6), has determined that the development of this document is subject to ''Quality Assurance Requirements and Description'' requirements. The control of the electronic management of data is accomplished in accordance with the methods specified in Reference 1, Section 10. AP-3.124, ''Design Calculations and Analysis'' (Ref. 2), is used to develop and document the calculation.

Z. Ceylan

2002-04-30

378

Computational Design of Solar Energy Harvesting Materials Made of Earth-Abundant Elements  

NASA Astrophysics Data System (ADS)

Very large-scale deployment of photovoltaic (PV) technology based on both the first and second generation solar cells posts serious questions on the materials supply as they rely on either high-purity and high-quality silicon crystals or rare elements such as indium and tellurium. ``Ancient'' PV materials made of earth-abundant elements, such as oxides and sulfides of copper and iron, have attracted resurgent interests. There is also intensive research devoted to the search for ``modern'' earth-abundant PV materials, with a recent promising example being Cu2ZnSnSe4. Computational approaches play a key role in this endeavor by guiding the screening and optimization of the materials toward high device performance. In this paper, I will focus on two aspects of computational design of earth-abundant PV materials. First, I will discuss the methods for accurately predicting band gaps of semiconductor materials. The emphasis will be on the performance of hybrid functional method on different classes of materials. Based on these understandings, I will discuss how to tune the band gap of a material to match the solar spectrum. For example, one could reduce of the band gap of anatase to 1.5 eV by the chemical codoping approach. Second, I will discuss the methods for accurate computation of defect properties, which is important as the defectiveness is intrinsic to the low-cost synthesized materials. I will introduce a method for calculation of defect formation energies by minimizing the error due to the ``band-gap problem'' of the density functional theory. I will also discuss approaches to mitigating the effects of defects, e.g., by passivation.

Sun, Yiyang

2012-02-01

379

Design and "As Flown" Radiation Environments for Materials in Low Earth Orbit  

NASA Technical Reports Server (NTRS)

A conservative design approach was adopted by the International Space Station Program for specifying total ionizing radiation dose requirements for use in selecting and qualifying materials for construction of the International Space Station. The total ionizing dose design environment included in SSP 30512 Space Station Ionizing Radiation Design Environment is based on trapped proton and electron fluence derived from the solar maximum versions of the AE-8 and AP-8 models, respectively, specified for a circular orbit at 500 km altitude and 51.7 degree inclination. Since launch, the range of altitudes utilized for Space Station operations vary from a minimum of approximately 330 km to a maximum of approximately 405 km with a mean operational altitude less than 400 km. The design environment, therefore, overestimates the radiation environment because the particle flux in the South Atlantic Anomaly is the primary contributor to radiation dose in low Earth orbit and flux within the Anomaly is altitude dependent. In addition, a 2X multiplier is often applied to the design environment to cover effects from the contributions of galactic cosmic rays, solar energetic particle events, geomagnetic storms, and uncertainties in the trapped radiation models which are not explicitly included in the design environment. Application of this environment may give radiation dose overestimates on the order of 1OX to 30X for materials exposed to the space environment, suggesting that materials originally qualified for ten year exposures on orbit may be used for longer periods without replacement. In this paper we evaluate the "as flown" radiation environments derived from historical records of the ISS flight trajectory since launch and compare the results with the SSP 30512 design environment to document the magnitude of the radiation dose overestimate provided by the design environment. "As flown" environments are obtained from application of the AE-8/AP-8 trapped particle models along the ISS flight trajectory including variations in altitude due to decay of the vehicle orbit and periodic reboosts to higher altitudes. In addition, an estimate of the AE-8 model to predict low Earth orbit electron flux (because the radiation dose for thin materials is dominated by the electron component of the radiation environment) is presented based on comparisons of the AE-8 model to measurements of electron integral flux at approximately 850 km from the Medium Energy Proton and Electron Detector on board the NOAA Polar Operational Environmental Satellite.

Minow, Joseph; McWilliams, Brett; Altstatt, Richard; Koontz, Steven

2006-01-01

380

Structural material, manufacture, and design requirements for high-temperature fasteners for space plane technologies  

NASA Astrophysics Data System (ADS)

The design of high temperature refractory alloy fasteners for Hermes is addressed. Principles of fastener design, implications of material selection and processing, and requirements for coating selection are reviewed. Methods for calculation of fastener preload and the possible sources of preload loss (including thermal expansion mismatch) are discussed. In particular, the need for a systems approach to the development of the whole joint concept is stressed, and the potential of numerical analysis techniques, such as finite elements, to support such an approach is illustrated.

Agatanovic, P.; Dogigli, M.

1992-10-01

381

The SNL100-02 blade : advanced core material design studies for the Sandia 100-meter blade.  

SciTech Connect

A series of design studies are performed to investigate the effects of advanced core materials and a new core material strategy on blade weight and performance for large blades using the Sandia 100-meter blade designs as a starting point. The initial core material design studies were based on the SNL100-01 100- meter carbon spar design. Advanced core material with improved performance to weight was investigated with the goal to reduce core material content in the design and reduce blade weight. A secondary element of the core study was to evaluate the suitability of core materials from natural, regrowable sources such as balsa and recyclable foam materials. The new core strategy for the SNL100-02 design resulted in a design mass of 59 tons, which is a 20% reduction from the most recent SNL100-01 carbon spar design and over 48% reduction from the initial SNL100-00 all-glass baseline blade. This document provides a description of the final SNL100-02 design, includes a description of the major design modifications, and summarizes the pertinent blade design information. This document is also intended to be a companion document to the distribution of the NuMAD blade model files for SNL100-02 that are made publicly available.

Griffith, Daniel Todd

2013-11-01

382

Non-equilibrium materials design: a case study of nanostructured soft magnets for cryogenic applications  

NASA Astrophysics Data System (ADS)

Nanocrystalline soft magnetic materials are the latest and most promising of the soft magnetic materials that were developed at the end of the 20th century. They have since been studied extensively, and various alloy compositions have been developed and optimized for ambient and extreme (cryogenic and elevated temperature) applications. Their advantage lies in the unique combination of fine microstructure, crystal structure and composition, which can be achieved by rapid solidification and subsequent controlled annealing. In this article, we discuss the requirements and the challenges of the alloy designing these alloys and how it affects the crystal structure, microstructure and eventually the magnetic performance of new alloys designed for use at temperatures below 150 K in applications as varied as cryo-power electronics and magnetic shielding. The results from our latest studied alloy series are mentioned as an example.

Daniil, Maria; Knipling, Keith E.; Fonda, Helen M.; Willard, Matthew A.

2014-05-01

383

A method for developing design diagrams for ceramic and glass materials using fatigue data  

NASA Technical Reports Server (NTRS)

The service lifetime of glass and ceramic materials can be expressed as a plot of time-to-failure versus applied stress whose plot is parametric in percent probability of failure. This type of plot is called a design diagram. Confidence interval estimates for such plots depend on the type of test that is used to generate the data, on assumptions made concerning the statistical distribution of the test results, and on the type of analysis used. This report outlines the development of design diagrams for glass and ceramic materials in engineering terms using static or dynamic fatigue tests, assuming either no particular statistical distribution of test results or a Weibull distribution and using either median value or homologous ratio analysis of the test results.

Heslin, T. M.; Magida, M. B.; Forrest, K. A.

1986-01-01

384

Space Shuttle Orbiter - Leading edge structural design/analysis and material allowables  

NASA Technical Reports Server (NTRS)

Reinforced Carbon-Carbon (RCC), a structural composite whose development was targeted for the high temperature reentry environments of reusable space vehicles, has successfully demonstrated that capability on the Space Shuttle Orbiter. Unique mechanical properties, particularly at elevated temperatures up to 3000 F, make this material ideally suited for the 'hot' regions of multimission space vehicles. Design allowable characterization testing, full-scale development and qualification testing, and structural analysis techniques will be presented herein that briefly chart the history of the RCC material from infancy to eventual multimission certification for the Orbiter. Included are discussions pertaining to the development of the design allowable data base, manipulation of the test data into usable forms, and the analytical verification process.

Johnson, D. W.; Curry, D. M.; Kelly, R. E.

1986-01-01

385

Designing and Evaluating a Scientific Training Program and Virtual Learning Materials  

PubMed Central

The University of Hawaii's John A. Burns School of Medicine developed a professional development program and virtual learning materials to assist high school science teachers become familiar with laboratory techniques prior to engaging in authentic molecular biology research. The purpose of this paper is to provide an evaluative overview of the program with emphasis on the virtual materials that were designed to employ a blended learning approach to augment offline classroom learning. The virtual learning materials provide a unique sphere for scientific learning in which skills can be reproduced in an offline environment. Twelve high school science teachers participated in the training program and were given full access to the online materials. After participation in the program, teachers filled out a final survey and completed a final written reflective statement as a form of evaluating the program and online materials. Thematic analysis was used to code participants' responses. Results showed that teachers recounted meeting the scientists as a valuable experience, teachers were grateful to learn real-world application of current research, and teachers described the importance of learning skills to prepare students to succeed in higher education. Additionally, results showed teacher's intent to use the virtual learning materials as homework tools and in classroom lessons.

van Raalte, Lisa; Boulay, Rachel

2014-01-01

386

Design and evaluation of carbon nanotube based optical power limiting materials.  

PubMed

Optical power limiters (OPLs) are "smart materials" that follow passive approaches to provide laser protection. They have the potential for protecting optical sensors and possibly even human eyes from laser-pulse damage. Optical power limiting has been a subject of increasing interest for more than two decades now. The interest is due to the increasingly large number of applications based on lasers that are currently available. Several research groups have been attempting to develop novel OPL materials based on nonlinear optical (NLO) chromophores. As a result, there are a large number of publications and patents on this subject. To date, however, there is not a single OPL material available which, taken individually, can provide ideal and smooth attenuation of an output beam. Therefore, the design and development of radically new types of materials for OPL is urgently required. During the last few years, materials containing carbon nanotubes (CNTs) have established themselves as some of the best-performing optical limiters; however, such materials are difficult to prepare and have issues with stability. In this review, the origin of OPL as well as the mechanisms of OPL are discussed. Ways to modify CNTs to make them suitable for OPL applications is also discussed. PMID:21125817

Rahman, Salma; Mirza, Shamim; Sarkar, Abhijit; Rayfield, George W

2010-08-01

387

Peridynamics as a rigorous coarse-graining of atomistics for multiscale materials design  

Microsoft Academic Search

This report summarizes activities undertaken during FY08-FY10 for the LDRD Peridynamics as a Rigorous Coarse-Graining of Atomistics for Multiscale Materials Design. The goal of our project was to develop a coarse-graining of finite temperature molecular dynamics (MD) that successfully transitions from statistical mechanics to continuum mechanics. The goal of our project is to develop a coarse-graining of finite temperature molecular

Richard B. Lehoucq; John Bahram Aidun; Stewart Andrew Silling; Mark P. Sears; James R. Kamm; Michael L. Parks

2010-01-01

388

Materials compatibility considerations for a fusion-fission hybrid reactor design  

SciTech Connect

The Tandem Mirror Hybrid Reactor is a fusion reactor concept that incorporates a fission-suppressed breeding blanket for the production of /sup 233/U to be used in conventional fission power reactors. The present paper reports on compatibility considerations related to the blanket design. These considerations include solid-solid interactions and liquid metal corrosion. Potential problems are discussed relative to the reference blanket operating temperature (490/sup 0/C) and the recycling time of breeding materials (<1 year).

DeVan, J.H.; Tortorelli, P.F.

1983-01-01

389

Materials compatibility considerations for a fusion-fission hybrid reactor design  

SciTech Connect

The Tandem Mirror Hybrid Reactor is a fusion reactor concept that incorporates a fissionsuppressed breeding blanket for the production of /sup 233/U to be used in conventional fission power reactors. The present paper reports on compatibility considerations related to the blanket design. These considerations include solid-solid interactions and liquid metal corrosion. Potential problems are discussed relative to the reference blanket operating temperature (490/sup 0/C) and the recycling time of fissile materials (<1 year).

DeVan, J.H.; Tortorelli, P.F.

1983-09-01

390

Design and performance of a vacuum-UV simulator for material testing under space conditions  

NASA Astrophysics Data System (ADS)

This paper describes the construction and performance of a VUV-simulator that has been designed to study degradation of materials under space conditions. It is part of the Complex Irradiation Facility at DLR in Bremen, Germany, that has been built for testing of material under irradiation in the complete UV-range as well as under proton and electron irradiation. Presently available UV-sources used for material tests do not allow the irradiation with wavelengths smaller than about 115 nm where common Deuterium lamps show an intensity cut-off. The VUV-simulator generates radiation by excitation of a gas-flow with an electron beam. The intensity of the radiation can be varied by manipulating the gas-flow and/or the electron beam.

Sznajder, M.; Renger, T.; Witzke, A.; Geppert, U.; Thornagel, R.

2013-12-01

391

Information management in the design of materials control and accountability systems  

SciTech Connect

This paper presents information management methods for materials accounting systems based on experience in systems development at DOE facilities. We describe principles for the acquistion and organization of data for a materials control and accountability (MC and A) system. Many of these principles are drawn from software engineering. These include the preparation of a requirements document, a functional specification, and the application of structured analysis and design. Insufficient effort and detail to these early fundamental activities for identifying and acquiring the appropriate data cause many problems later. Failure to provide for complete acquisition of all required information leads to potentially costly revisions to the data acquisition system or to a materials accounting system that cannot complete its intended functions. Likewise, unrealistic analyses requirements can cause catastrophic problems later on. 16 refs.

Whitty, W.J.; Markin, J.T.; Strittmatter, R.B.

1988-01-01

392

Standardization Efforts for Mechanical Testing and Design of Advanced Ceramic Materials and Components  

NASA Technical Reports Server (NTRS)

Advanced aerospace systems occasionally require the use of very brittle materials such as sapphire and ultra-high temperature ceramics. Although great progress has been made in the development of methods and standards for machining, testing and design of component from these materials, additional development and dissemination of standard practices is needed. ASTM Committee C28 on Advanced Ceramics and ISO TC 206 have taken a lead role in the standardization of testing for ceramics, and recent efforts and needs in standards development by Committee C28 on Advanced Ceramics will be summarized. In some cases, the engineers, etc. involved are unaware of the latest developments, and traditional approaches applicable to other material systems are applied. Two examples of flight hardware failures that might have been prevented via education and standardization will be presented.

Salem, Jonathan A.; Jenkins, Michael G.

2003-01-01

393

Design, fabrication and characterization of a monolithic focusing piezoceramic transducer for an anisotropic material  

NASA Astrophysics Data System (ADS)

Piezoceramic transducers shaped as spherical caps are widely used to focus ultrasound waves in isotropic materials. For anisotropic materials, the sound wave surface is not spherical and the transducer surface should be adjusted to reproduce a portion of this wave surface to focus the emitted sound properly. In this article, we show how to design such a transducer and how to fabricate it in lab on a standard machine from a rod of raw piezo ceramic material. The main features of its electrical impedance response are well reproduced by a numerical model, allowing the identification of most of its vibrational modes. We finally measured the sound field emitted by such a transducer and found its focusing efficiency similar to that of spherical caps in isotropic media.

Souris, Fabien; Grucker, Jules; Garroum, Nabil; Leclercq, Arnaud; Isac, Jean-Michel; Dupont-Roc, Jacques; Jacquier, Philippe

2014-06-01

394

Preliminary Design of a Galactic Cosmic Ray Shielding Materials Testbed for the International Space Station  

NASA Technical Reports Server (NTRS)

The preliminary design of a testbed to evaluate the effectiveness of galactic cosmic ray (GCR) shielding materials, the MISSE Radiation Shielding Testbed (MRSMAT) is presented. The intent is to mount the testbed on the Materials International Space Station Experiment-X (MISSE-X) which is to be mounted on the International Space Station (ISS) in 2016. A key feature is the ability to simultaneously test nine samples, including standards, which are 5.25 cm thick. This thickness will enable most samples to have an areal density greater than 5 g/sq cm. It features a novel and compact GCR telescope which will be able to distinguish which cosmic rays have penetrated which shielding material, and will be able to evaluate the dose transmitted through the shield. The testbed could play a pivotal role in the development and qualification of new cosmic ray shielding technologies.

Gaier, James R.; Berkebile, Stephen; Sechkar, Edward A.; Panko, Scott R.

2012-01-01

395

Mobile Pit verification system design based on passive special nuclear material verification in weapons storage facilities  

SciTech Connect

A mobile 'drive by' passive radiation detection system to be applied in special nuclear materials (SNM) storage facilities for validation and compliance purposes has been designed through the use of computational modeling and new radiation detection methods. This project was the result of work over a 1 year period to create optimal design specifications to include creation of 3D models using both Monte Carlo and deterministic codes to characterize the gamma and neutron leakage out each surface of SNM-bearing canisters. Results were compared and agreement was demonstrated between both models. Container leakages were then used to determine the expected reaction rates using transport theory in the detectors when placed at varying distances from the can. A 'typical' background signature was incorporated to determine the minimum signatures versus the probability of detection to evaluate moving source protocols with collimation. This established the criteria for verification of source presence and time gating at a given vehicle speed. New methods for the passive detection of SNM were employed and shown to give reliable identification of age and material for highly enriched uranium (HEU) and weapons grade plutonium (WGPu). The finalized 'Mobile Pit Verification System' (MPVS) design demonstrated that a 'drive-by' detection system, collimated and operating at nominally 2 mph, is capable of rapidly verifying each and every weapon pit stored in regularly spaced, shelved storage containers, using completely passive gamma and neutron signatures for HEU and WGPu. This system is ready for real evaluation to demonstrate passive total material accountability in storage facilities. (authors)

Paul, J. N.; Chin, M. R.; Sjoden, G. E. [Nuclear and Radiological Engineering Program, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 770 State St, Atlanta, GA 30332-0745 (United States)] [Nuclear and Radiological Engineering Program, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 770 State St, Atlanta, GA 30332-0745 (United States)

2013-07-01

396

Materials and design development for bipolar/end plates in fuel cells  

NASA Astrophysics Data System (ADS)

Bipolar/end plate is one of the most important and costliest components of the fuel cell stack and accounts to more than 80% of the total weight of the stack. In the present work, we focus on the development of alternative materials and design concepts for these plates. A prototype one-cell polymer electrolyte membrane (PEM) fuel cell stack made out of SS-316 bipolar/end plate was fabricated and assembled. The use of porous material in the gas flow-field of bipolar/end plates was proposed, and the performance of these was compared to the conventional channel type of design. Three different porous materials were investigated, viz. Ni-Cr metal foam (50 PPI), SS-316 metal foam (20 PPI), and the carbon cloth. It was seen that the performance of fuel cell with Ni-Cr metal foam was highest, and decreased in the order SS-316 metal foam, conventional multi-parallel flow-field channel design and carbon cloth. This trend was explained based on the effective permeability of the gas flow-field in the bipolar/end plates. The use of metal foams with low permeability values resulted in an increased pressure drop across the flow-field which enhanced the cell performance.

Kumar, Atul; Reddy, Ramana G.

397

Material scarcity: a reason for responsibility in technology development and product design.  

PubMed

There are warning signs for impending scarcity of certain technology metals that play a critical role in high-tech products. The scarce elements are indispensable for the design of modern technologies with superior performance. Material scarcity can restrain future innovations and presents therefore a serious risk that must be counteracted. However, the risk is often underrated in the pursuit of technological progress. Many innovators seem to be inattentive to the limitations in availability of critical resources and the possible implications thereof. The present shortages in industrial supply with technology metals may be interpreted as a wake-up call for technology developers to tackle the issue with due consideration. The article reviews the materials scarcity phenomenon from the viewpoint of sustainable development ethics. The following questions are discussed: 'Should preventative actions be taken today in order to mitigate resource scarcity in future?' and 'Should technology developers feel responsible to do this?' The discussion presents arguments for industrial designers and engineers to create a sense of responsibility for the proactive mitigation of material scarcity. Being protagonists of the innovation system, they have the opportunity to lead change towards resource-aware technology development. The paper concludes by outlining ideas on how they can pioneer sustainable management of critical materials. PMID:23054676

Köhler, Andreas R

2013-09-01

398

Materials for MW sized aerogenerators. I - The influence of design on operating parameters  

NASA Astrophysics Data System (ADS)

Materials and fatigue design deficiencies in the development and production of MW-scale wind turbines with 30-yr, reliable, cost-effective lifetimes are surveyed. Attention is given to existing wind turbines, the performance of materials to date, and fundamental materials properties. Failures thus far have arisen from the coincidence of fundamental vibration frequency or a low order harmonic of components with an exciting frequency, malfunction of control mechanisms, and inadequate engineering. All the failures can be avoided, and most occur in the rotor. Two-bladed horizontal configurations permit use of a through-center section while requiring teetering to reduce stresses; three-bladed designs offer higher output for the same diameter and less of a stress moment on the tower and yaw components. Hydraulic components have caused trouble, which could be eliminated with redundancy. The torsional vibrations to which a Darrieus wind turbine is subject in every revolution can be ameliorated with three blades and eradicated with four. The Musgrove wind turbine requires thin blades to maintain a high aspect ratio, but simultaneously introduces buckling stresses. Blade materials used or proposed are carbon steel, GFRP, wood, stainless steel, CFRP, aluminum, titanium, and prestressed concrete.

Wyatt, L. M.

1983-09-01

399

Engineering and materials issues in designing a cold-gas divertor*1  

NASA Astrophysics Data System (ADS)

One of the key challenges facing the International Thermonuclear Experimental Reactor (ITER) Project is the development of plasma-facing components (PFCs) that can withstand the severe environmental conditions at the plasma edge. The most intensely loaded element of the PFCs is the divertor. The divertor must handle high fluxes of energetic plasma particles and electromagnetic radiation without excessive impurity buildup in the plasma core. The "cold-plasma-target" mode of divertor operation proposed for ITER expands the divertor design window to include several alternate heat sink and armor materials that were not available for the previous "high recycling divertor" approach. In particular, beryllium armor can now be considered with copper, niobium and vanadium heat sink materials; and helium or liquid metal coolants are feasible in addition to water. This paper presents material properties and compatability assessments for these materials and coolants along with parametric studies of thermal and mechanical performance. A viable design window is found for copper and niobium heat sinks with beryllium armor, but not for vanadium unless thin (˜ 1 mm) coolant structures can be accomodated mechanically.

Davis, J. W.; Driemeyer, D. E.; Haines, J. R.; McGrath, R. T.

1994-09-01

400

General design of the International Fusion Materials Irradiation Facility deuteron injector: Source and beam line  

NASA Astrophysics Data System (ADS)

In the framework of the International Fusion Materials Irradiation Facility-Engineering Validation and Engineering Design Activities (IFMIF-EVEDA) project, CEA/IRFU is in charge of the design and realization of the 140 mA cw deuteron Injector. The electron cyclotron resonance ion source operates at 2.45 GHz and a 4 electrode extraction system has been chosen. A 2 solenoid beam line, together with a high space charge compensation have been optimized for a proper beam injection in the 175 MHz radio frequency quadrupole. The injector will be tested with proton and deuteron beam production either in pulsed mode or in cw mode on the CEA-Saclay site before to be shipped to Japan. Special attention was paid to neutron emission due to (d,D) reaction. In this paper, the general IFMIF Injector design is reported, pointing out beam dynamics, radioprotection, diagnostics, and mechanical aspects.

Gobin, R.; Blideanu, V.; Bogard, D.; Bourdelle, G.; Chauvin, N.; Delferrière, O.; Girardot, P.; Jannin, J. L.; Langlois, S.; Loiseau, D.; Pottin, B.; Rousse, J.-Y.; Senée, F.

2010-02-01

401

PREFACE: International Conference on Advanced Structural and Functional Materials Design 2008  

NASA Astrophysics Data System (ADS)

The Ministry of Education, Culture, Sports, Science and Technology of Japan started the Priority Assistance for the Formation of Worldwide Renowned Centers of Research - Global COE Program. This program is based on the competitive principle where a third party evaluation decides which program to support and to give priority support to the formation of world-class centers of research. Our program Center of Excellence for Advanced Structural and Functional Materials Design was selected as one of 13 programs in the field of Chemistry and Materials Science. This center is composed of two materials-related Departments in the Graduate School of Engineering: Materials and Manufacturing Science and Adaptive Machine Systems, and 4 Research Institutes: Center for Atomic and Molecular Technologies, Welding and Joining Research Institute, Institute of Scientific and Industrial Research and Research Center for Ultra-High Voltage Electron Microscopy. Recently, materials research, particularly that of metallic materials, has specialized only in individual elemental characteristics and narrow specialty fields, and there is a feeling that the original role of materials research has been forgotten. The 6 educational and research organizations which make up the COE program cooperatively try to develop new advanced structural and functional materials and achieve technological breakthrough for their fabrication processes from electronic, atomic, microstructural and morphological standpoints, focusing on their design and application: development of high performance structural materials such as space plane and turbine blades operating under a severe environment, new fabrication and assembling methods for electronic devices, development of evaluation technique for materials reliability, and development of new biomaterials for regeneration of biological hard tissues. The aim of this international conference was to report the scientific progress in our Global COE program and also to discuss related research topics. The organizing committee gratefully thanks participants for presenting their recent results and for discussions with our COE members and international attendees. November 2008 Professor Tomoyuki Kakeshita Chairman of the Conference Vice Dean, Graduate School of Engineering, Osaka University, Division of Materials and Manufacturing Science, Graduate School of Engineering Leader of Global COE Program, Osaka University, ''Center of Excellence for Advanced Structural and Functional Materials Design'' Organization Chairman: T Kakeshita (Osaka University) Advisory Board:H Mehrer (University Münster, Germany), E K H Salje (University of Cambridge, United Kingdom), H-E Schaefer (University of Stuttgart, Germany), P Veyssiere (CNRS-ONERA, France) Organizing Committee: T Kakeshita, H Araki, H Fujii, S Fujimoto, Y Fujiwara, A Hirose, S Kirihara, M Mochizuki, H Mori, T Nagase, H Nakajima, T Nakano, R Nakatani, K Nogi, Y Setsuhara, Y Shiratsuchi, T Tanaka, T Terai, H Tsuchiya, N Tsuji, H Utsunomiya, H Yasuda, H Yasuda (Osaka University) Executive Committee: T Kakeshita, S Fujimoto, Y Fujiwara, A Hirose, T Tanaka, H Yasuda (Osaka University) Conference Secretariat: Y Fujiwara (Osaka University) Proceedings Editors: T Kakeshita and Y Fujiwara (Osaka University) Conference photograph

Kakeshita, Tomoyuki

2009-07-01

402

An Analysis of Teaching Competence in Science Teachers Involved in the Design of Context-Based Curriculum Materials  

ERIC Educational Resources Information Center

The committees for the current Dutch context-based innovation in secondary science education employed teachers to design context-based curriculum materials. A study on the learning of science teachers in design teams for context-based curriculum materials is presented in this paper. In a correlation study, teachers with (n = 5 and 840 students)…

De Putter-Smits, Lesley G. A.; Taconis, Ruurd; Jochems, Wim; Van Driel, Jan

2012-01-01

403

Pre-Service Science and Technology Teachers' Efficacy Beliefs about Information and Communication Technologies (ICT) Usage and Material Design  

ERIC Educational Resources Information Center

In this study, a scale entitled "Information and Communication Technologies Usage and Material Design Efficacy [ICT_MDE]" is developed to investigate pre-service science and technology teachers' efficacy beliefs regarding ICT usage and Material Design and the factors impacting these beliefs. By using the validity and reliability data from 310…

Bursal, Murat; Yigit, Nevzat

2012-01-01

404

Design, materials and R&D issues of innovative thermal contact joints for high heat flux applications  

Microsoft Academic Search

Plasma facing components in fusion machines are designed with a layer of sacrificial armour material facing the plasma and a high-conductivity material in contact with the coolant. One of the most critical issues associated with making the proposed design concept work, from a power handling point of view, is achieving the necessary contact conductance between the armour and the heat

G Federici; R Matera; S Chiocchio; J Dietz; G Janeschitz; D Driemeyer; J Haines; M. S Tillack; M Ulrickson

1995-01-01

405

Square pulse thermography system design considerations for detection of voids inside of the material with different properties and finite differences  

Microsoft Academic Search

This paper gives some practical, simulated and calculated design parameters for the detection of voids inside the material with active thermography for different void geometry, orientation and depths. The main goal is to find the limitations of detectivity for different materials and voids, to help designers for test systems with: a quick estimation of the feasibility and to find the

Gerhard Traxler; Michael Scheerer; Christoph Steiger

2005-01-01

406

Materials selection in the Life-Cycle Design process: a method to integrate mechanical and environmental performances in optimal choice  

Microsoft Academic Search

The choice of materials takes on strategic importance in design aimed at harmonising the performance characteristics and eco-compatibility of products in line with the Life-Cycle Design approach. The objective of the present study is the development of a systematic method which introduces environmental considerations in the selection of the materials used in components, meeting functional and performance requirements while minimising

F. Giudice; G. La Rosa; A. Risitano

2005-01-01

407

Special optical fiber design to reduce reflection peak distortion of a FBG embedded in inhomogeneous material  

NASA Astrophysics Data System (ADS)

During the last decades, the use of optical fiber for sensing applications has gained increasing acceptance because of its unique properties of being intrinsically safe, unsusceptible to EMI, potentially lightweight and having a large operational temperature range. Among the different Fiber Optic sensor types, Fiber Bragg Grating (FBG) is most widely used for its unique multiplexing potential and the possibility of embedding in composite material for Structural Health Monitoring. When the fiber is embedded in an inhomogeneous environment, typically a material composed of filler and base material of different stiffness, local stiff material will generate extra lateral load to the fiber. Via the Poisson effect, this will be converted to a local axial strain. The narrow and sharp peak in the reflection spectrum of an FBG sensor relies on the constant periodicity of the grating. An inhomogeneous axial strain distribution will result in distortion or broadening of the FBG reflection spectrum. For the FBG strain sensitivity of about 1.2pm/??, the spectral distortion can be disastrous for strain measurements. A fiber design to tackle this critical problem is presented. Finite Element Modeling is performed to demonstrate the effectiveness of the solution. Modeling with different configurations has been performed to verify the influence of the design. The deformation of the core in the special fiber depends on the design. For a particular configuration, the core deformation in the axial direction is calculated to be a factor of 10 lower than that of a standard fiber. The first prototype fiber samples were drawn and the manufacturing of FBG in this special fiber using the phase mask method was demonstrated successfully.

Cheng, Lun-Kai; Toet, Peter; de Vreugd, Jan; Nieuwland, Remco; Tse, Ming-Leung Vincent; Tam, Hwayaw

2014-03-01

408

Conceptual design report: Nuclear materials storage facility renovation. Part 6, Alternatives study  

SciTech Connect

The Nuclear Materials Storage Facility (NMSF) at the Los Alamos National Laboratory (LANL) was a Fiscal Year (FY) 1984 line-item project completed in 1987 that has never been operated because of major design and construction deficiencies. This renovation project, which will correct those deficiencies and allow operation of the facility, is proposed as an FY 97 line item. The mission of the project is to provide centralized intermediate and long-term storage of special nuclear materials (SNM) associated with defined LANL programmatic missions and to establish a centralized SNM shipping and receiving location for Technical Area (TA)-55 at LANL. Based on current projections, existing storage space for SNM at other locations at LANL will be loaded to capacity by approximately 2002. This will adversely affect LANUs ability to meet its mission requirements in the future. The affected missions include LANL`s weapons research, development, and testing (WRD&T) program; special materials recovery; stockpile survelliance/evaluation; advanced fuels and heat sources development and production; and safe, secure storage of existing nuclear materials inventories. The problem is further exacerbated by LANL`s inability to ship any materials offsite because of the lack of receiver sites for material and regulatory issues. Correction of the current deficiencies and enhancement of the facility will provide centralized storage close to a nuclear materials processing facility. The project will enable long-term, cost-effective storage in a secure environment with reduced radiation exposure to workers, and eliminate potential exposures to the public. This report is organized according to the sections and subsections outlined by Attachment 111-2 of DOE Document AL 4700.1, Project Management System. It is organized into seven parts. This document, Part VI - Alternatives Study, presents a study of the different storage/containment options considered for NMSF.

NONE

1995-07-14

409

Quantum Dot Intermediate Band Solar Cells: Design Criteria and Optimal Materials  

NASA Astrophysics Data System (ADS)

The main limitation of the conventional solar conversion device is that low energy photons cannot. excite charge carriers to the conduction band, therefore do not contribute to the devices's current, and high energy photons are not efficiently used due to a poor match of the solar spectrum to the energy gap. However, if intermediate levels are introduced into the energy gap of a conventional device, then low energy photons can be used to promote charge carriers in a stepwise mariner to the conduction band thereby enhancing the current while maintaining a large open-circuit voltage. This concept is called the intermediate band solar cell and increases the efficiency beyond the thermodynamic limits of the conventional device. A device based on the confined electron levels of quantum dots called the quantum dot intermediate band solar cell is a physical realization of the intermediate band solar cell. In this work, we propose design criteria and optimal material systems that are considered candidates for the quantum dot intermediate band solar cell. To search for optimal materials. the finite element method is developed and MATLAB code is designed in the context of quantum and continuum mechanics with the sophistication necessary to allow for three dimensional numerical simulations that incorporate realistic assumptions about the quantum dot. The materials considered in this work are the technologically important III-V compound semiconductors and their alloys. Numerical simulations are carried out on quantum dot geometries that have been experimentally observed during self-assembled growth, the technology proposed to achieve the quantum dot intermediate band solar cell, and those material systems that have properties that match those of the intermediate band solar cell with efficiency greater than 46% for unconcentrated light and greater than 62% for fully concentrated light are identified as optimal materials for the quantum dot intermediate band solar cell.

Jenks, Steven Evans

410

Optimizing Material Use in Blade Design by Improving Failure Prediction Methodology and Introducing Damage Tolerant Concepts in FRP Composites  

Microsoft Academic Search

Preliminary results are presented in this work, concerning the validation of a reliable FEM tool under development, featuring damage tolerant concepts, to enhance design capabilities and optimize material use in large composite structures. User defined material constitutive equations concerning anisotropic non- linearity and material stiffness degradation as a result of damage accumulation, are implemented to model inherent damage tolerance of

A. E. Antoniou; T. P. Philippidis

411

Design optimization of cementless metal-backed cup prostheses using the concept of functionally graded material.  

PubMed

Metal backing has been widely used in acetabular cup design. A stiff backing for a polyethylene liner was initially believed to be mechanically favourable. Yet, recent studies of the load transfer around acetabular cups have shown that a stiff backing causes two problems. It generates higher stress peaks around the acetabular rim than those caused by full polyethylene cups and reduces the stresses transferred to the dome of the acetabulum causing stress shielding. The aim of this study is to overcome these two problems by improving the design of cementless metal-backed acetabular cups using the two-dimensional functionally graded material (FGM) concept through finite-element analysis and optimization techniques. It is found that the optimal 2D FGM model must have three bioactive materials of hydroxyapatite, Bioglass and collagen. This optimal material reduces the stress shielding at the dome of the acetabulum by 40% and 37% compared with stainless steel and titanium metal backing shells, respectively. In addition, using the 2D FGM model reduces the maximum interface shear stress in the bone by 31% compared to the titanium metal backing shell. PMID:18458393

Hedia, H S; El-Midany, T T; Shabara, M A N; Fouda, N

2006-09-01

412

Preparation of Silicon Nitride Multilayer Ceramic Radome Material and Optimal Design of the Wall Structure  

SciTech Connect

A study of silicon nitride ceramic radomes, which includes preparation of the material and optimal design of the radome wall structure, is presented in this paper. Multilayer radome wall structure with high dielectric constant skins and a low dielectric constant core layer is used for broadband application. As a candidate material for both the skins and core layer, silicon nitride ceramics of controlled dielectric constant in the range 3.0{approx}7.5 were prepared by adding different content of sintering aids such as magnesia, alumina, silica and zirconium phosphate binder and choosing suitable sintering methods. A computer aided design (CAD) for the wall structure of silicon nitride multilayer ceramic radome based on microwave equivalent network method is carried out according to design requirements. By optimizing the thickness of skins and core layer, the power transmission efficiency of such a multilayer Si{sub 3}N{sub 4} ceramic radome is calculated. The calculated results suggest that when the dielectric constant of skins lies in the range 6{approx}7.5 and core layer in the range 3.5{approx}4, the power transmission efficiency is above 85% with frequency of 2{approx}18 GHz while the thickness of skins is less than 0.03{lambda} and the thickness ratio of skins to core layer is less than 1:15.

Chen Fei; Shen Qiang; Zhang Lianmeng [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

2008-02-15

413

Synthetic mammalian gene networks as a blueprint for the design of interactive biohybrid materials.  

PubMed

Synthetic biology aims at the rational design and construction of devices, systems and organisms with desired functionality based on modular well-characterized biological building blocks. Based on first proof-of-concept studies in bacteria a decade ago, synthetic biology strategies have rapidly entered mammalian cell technology providing novel therapeutic solutions. Here we review how biological building blocks can be rewired to interactive regulatory genetic networks in mammalian cells and how these networks can be transformed into open- and closed-loop control configurations for autonomously managing disease phenotypes. In the second part of this tutorial review we describe how the regulatory biological sensors and switches can be transferred from mammalian cell synthetic biology to materials sciences in order to develop interactive biohybrid materials with similar (therapeutic) functionality as their synthetic biological archetypes. We develop a perspective of how the convergence of synthetic biology with materials sciences might contribute to the development of truly interactive and adaptive materials for autonomous operation in a complex environment. PMID:21894343

Jakobus, Kathrin; Wend, Sabrina; Weber, Wilfried

2012-02-01

414

Design of self-growing, self-sensing, and self-repairing materials for engineering applications  

NASA Astrophysics Data System (ADS)

Like natural biological building systems these materials are inexpensive, and self-form through interaction of the materials. They sense and self-repair, respond to changes in the environment. The volume and scale, cost and end use are all considered from the start. The purpose of the particular system we will describe is an engineered bridge. The materials form as bone does from the innate attributes of the material without much labor. They sense the environment, respond to it, and repair any damage. This composite bridge is designed from a self-forming polymer and concrete system. Internal release of chemicals, their properties and location account for responsiveness to change and for repair. The choice of matrix additives also allow for the responsiveness. Bridge frames were fabricated for dynamic testing. The results showed that self repair and response to loads could be accomplished by careful placement of chemicals for later release and by use of chemicals which could alter such attributes as stiffness, flexure and permanent deformation. Internal viewing sensors could determine the state of the frames after testing.

Dry, Carolyn M.

2001-04-01

415

Materials design concepts for efficient blue OLEDs: A joint theoretical and experimental study  

SciTech Connect

Since their discovery, organic light emitting devices have evolved from a scientific curiosity into a technology with applications in flat panel displays and the potential to revolutionize the lighting market. During their relatively short history, the technology incorporated into OLEDs has rapidly advanced. Device quantum efficiencies have increased more than 20-fold since the first OLEDs, approaching the theoretical limit for internal quantum efficiencies. , , At this point, OLED research moves towards optimization of manufacturing processes, drive circuitry, light extraction, and overall cost reduction. However, finding the organic materials that provide both operational stability and high efficiency for the devices still remains one of the biggest challenges, particularly for blue emission. In this presentation, we will describe our approach to design functional OLED materials to meet the complex criteria set forth by device efficiency and stability goals.

Polikarpov, Evgueni; Padmaperuma, Asanga B.

2012-04-01

416

Corrosion test plan to guide canister material selection and design for a tuff repository  

SciTech Connect

Corrosion rates and the mode of corrosion attack form a most important basis for selection of canister materials and design of a nuclear waste package. Type 304L stainless steel was selected as the reference material for canister fabrication because of its generally excellent corrosion resistance in water, steam and air. However, 304L may be susceptible to localized and stress-assisted forms of corrosion under certain conditions. Alternative alloys are also investigated; these alloys were chosen because of their improved resistance to these forms of corrosion. The fabrication and welding processes, as well as the glass pouring operation for defense and commercial high-level wastes, may influence the susceptibility of the canister to localized and stress forms of corrosion. 12 references, 2 figures, 4 tables.

McCright, R.D.; van Konynenburg, R.A.; Ballou, L.B.

1983-11-01

417

STRUCTURAL DESIGN CRITERIA FOR TARGET\\/BLANKET SYSTEM COMPONENT MATERIALS FOR THE ACCELERATOR PRODUCTION OF TRITIUM PROJECT  

Microsoft Academic Search

The design of target\\/blanket system components for the Accelerator Production of Tritium (APT) plant is dependent on the development of materials properties data specified by the designer. These data are needed to verify that component designs are adequate. The adequacy of the data will be related to safety, performance, and economic considerations, and to other requirements that may be deemed

W. JOHNSON; R. RYDER; P. RITTENHOUSE

2001-01-01

418

Design and Implementation of a Facility for Discovering New Scintillator Materials  

SciTech Connect

We describe the design and operation of a high-throughput facility for synthesizing thousands of inorganic crystalline samples per year and evaluating them as potential scintillation detector materials. This facility includes a robotic dispenser, arrays of automated furnaces, a dual-beam X-ray generator for diffractometery and luminescence spectroscopy, a pulsed X-ray generator for time response measurements, computer-controlled sample changers, an optical spectrometer, and a network-accessible database management system that captures all synthesis and measurement data.

Derenzo, Stephen; Derenzo, Stephen E; Boswell, Martin S.; Bourret-Courchesne, Edith; Boutchko, Rostyslav; Budinger, Thomas F.; Canning, Andrew; Hanrahan, Stephen M.; Janecek, Martin; Peng, Qiyu; Porter-Chapman, Yetta; Powell, James; Ramsey, Christopher A.; Taylor, Scott E.; Wang, Lin-Wang; Weber, Marvin J.; Wilson, David S.

2008-04-25

419

Design of new quantum dot materials for deep tissue infrared imaging.  

PubMed

Near infrared fluorescence offers several advantages for tissue and in vivo imaging thanks to deeper photon penetration. In this article, we review a promising class of near infrared emitting probes based on semiconductor quantum dots (QDs), which have the potential to considerably improve in vivo fluorescence imaging thanks to their high brightness and stability. We discuss in particular the different criteria to optimize the design of near infrared QDs. We present the recent developments in the synthesis of novel QD materials and their different in vivo imaging applications, including lymph node localization, vasculature imaging, tumor localization, as well as cell tracking and QD-based multimodal probes. PMID:22981756

Cassette, Elsa; Helle, Marion; Bezdetnaya, Lina; Marchal, Frédéric; Dubertret, Benoit; Pons, Thomas

2013-05-01

420

Silicon-based elementary particle tracking system: Materials science and mechanical engineering design  

SciTech Connect

Research and development of the mechanical, cooling, and structural design aspects of a silicon detector-based elementary particle tracking system has been performed. Achieving stringent system precision, stability, and mass requirements necessitated the use of graphite fiber-reinforced cyanate-ester (C-E) resins. Mechanical test results of the effects of butane, ionizing radiation, and a combination of both on the mechanical properties of these materials are presented, as well as progress on developing compression molding of an ultralightweight graphite composite ring structure and TV holography-based noninvasive evaluation.

Miller, W.O.; Gamble, M.T.; Thompson, T.C.; Hanlon, J.A.

1993-01-01

421

Combinatorial design of copolymer donor materials for bulk heterojunction solar cells.  

PubMed

Seeking ?-conjugated polymers with targeted optical band gaps is not only a grand scientific challenge but also in great practical need for systematically improving the performance of organic optoelectronic devices. This work presents a generic combinatorial band-gap design strategy over 780 different copolymer donor materials for bulk heterojunction solar cell applications. Predicted optical band gaps effectively cover the entire solar spectrum from infrared, to visible, to ultraviolet. Combined with empirical arguments widely acknowledged in the literature, the optimal copolymer structures are identified for both single and tandem cells with the optimal power conversion efficiencies. PMID:24835665

Shin, Yongwoo; Liu, Jaikai; Quigley, Joseph J; Luo, Heng; Lin, Xi

2014-06-24

422

A Multiscale, Nonlinear, Modeling Framework Enabling the Design and Analysis of Composite Materials and Structures  

NASA Technical Reports Server (NTRS)

A framework for the multiscale design and analysis of composite materials and structures is presented. The ImMAC software suite, developed at NASA Glenn Research Center, embeds efficient, nonlinear micromechanics capabilities within higher scale structural analysis methods such as finite element analysis. The result is an integrated, multiscale tool that relates global loading to the constituent scale, captures nonlinearities at this scale, and homogenizes local nonlinearities to predict their effects at the structural scale. Example applications of the multiscale framework are presented for the stochastic progressive failure of a SiC/Ti composite tensile specimen and the effects of microstructural variations on the nonlinear response of woven polymer matrix composites.

Bednarcyk, Brett A.; Arnold, Steven M.

2012-01-01

423

Design and optical characterization of photonic crystal lasers with organic gain material  

NASA Astrophysics Data System (ADS)

We present a design concept for an optimized surface-emitting laser with two-dimensional feedback structure and organic gain material. The basic laser structure consists of an array of holes within a thin film of Ta2O5. The optical properties of such feedback structures are investigated theoretically and experimentally. Combining first-order with second-order photonic structures leads to a higher quality factor of the feedback structure, resulting in a lower laser threshold and/or a much smaller footprint of the laser.

Baumann, K.; Stöferle, T.; Moll, N.; Raino, G.; Mahrt, R. F.; Wahlbrink, T.; Bolten, J.; Scherf, U.

2010-06-01

424

Simulation tool for optical design of PET detector modules including scintillator material and sensor array  

SciTech Connect

The appearance of single photon avalanche diodes (SPADs) in the field of PET detector modules made it necessary to apply more complex optical design methods to refine the performance of such assemblies. We developed a combined simulation tool that is capable to model complex detector structures including scintillation material, light guide, light collection optics and sensor, correctly taking into account the statistical behavior of emission of scintillation light and its absorbance in SPADs. As a validation we compared simulation results obtained by our software and another optical design program. Calculations were performed for a simple PET detector arrangement used for testing purposes. According to the results, deviation of center of gravity coordinates between the two simulations is 0.0195 mm, the average ratio of total counts 1.0052. We investigated the error resulting from finite sampling in wavelength space and we found that 20 nm pitch is sufficient for the simulation in case of the given spectral dependencies. (authors)

Jatekos, B.; Erdei, G.; Lorincz, E. [Budapest Univ. of Technology and Economics, Dept. of Atomic Physics, Budafoki ut 8, H-1111 Budapest (Hungary)

2011-07-01

425

Applications of molecular modeling to the design and characterization of materials  

SciTech Connect

A variety of new molecular modeling tools are now available for studying molecular structures and molecular interactions, for building molecular structures from simple components using analytical data, and for studying the relationship of molecular structure to the energy of bonding and non-bonding interactions. These are proving quite valuable in characterizing molecular structures and intermolecular interactions and in designing new molecules. This paper describes the application of molecular modeling techniques to a variety of materials problems, including the probable modecular structures of coals, lignins, and hybrid inorganic-organic-organic systems (silsesquioxanes), the intercalation of small gas molecules in fullerene crystals, the diffusion of gas molecules through membranes, and the design, structure and function of biomimetic and nanocluster catalysts.

Carlson, G.A.; Faulon, J.L.; Pohl, P.I.; Shelnutt, J.A.

1994-06-01

426

Integrating Materials, Manufacturing, Design and Validation for Sustainability in Future Transport Systems  

SciTech Connect

The predictive methods currently used for material specification, component design and the development of manufacturing processes, need to evolve beyond the current 'metal centric' state of the art, if advanced composites are to realise their potential in delivering sustainable transport solutions. There are however, significant technical challenges associated with this process. Deteriorating environmental, political, economic and social conditions across the globe have resulted in unprecedented pressures to improve the operational efficiency of the manufacturing sector generally and to change perceptions regarding the environmental credentials of transport systems in particular. There is a need to apply new technologies and develop new capabilities to ensure commercial sustainability in the face of twenty first century economic and climatic conditions as well as transport market demands. A major technology gap exists between design, analysis and manufacturing processes in both the OEMs, and the smaller companies that make up the SME based supply chain. As regulatory requirements align with environmental needs, manufacturers are increasingly responsible for the broader lifecycle aspects of vehicle performance. These include not only manufacture and supply but disposal and re-use or re-cycling. In order to make advances in the reduction of emissions coupled with improved economic efficiency through the provision of advanced lightweight vehicles, four key challenges are identified as follows: Material systems, Manufacturing systems, Integrated design methods using digital manufacturing tools and Validation systems. This paper presents a project which has been designed to address these four key issues, using at its core, a digital framework for the creation and management of key parameters related to the lifecycle performance of thermoplastic composite parts and structures. It aims to provide capability for the proposition, definition, evaluation and demonstration of advanced lightweight structures for new generation vehicles in the context of whole life performance parameters.

Price, M. A.; Murphy, A.; Butterfield, J.; McCool, R.; Fleck, R. [CEIAT, School of Mechanical and Aerospace Engineering, Queens University, Belfast (United Kingdom)

2011-05-04

427