Y Huang

Publications (39)7.4 Total impact

• Dataset: Electron field emission for ultrananocrystalline diamond films

  A R Krauss, O Auciello, M Q Ding, D M Gruen, Y Huang, V V Zhirnov, A Breskin, R Chechen, E Shefer, V Konov, S Pimenov, A Karabutov, A Rakhimov, N Suetin
• Source

  Available from: George Labahn

  Article: Iterative methods for the solution of the singular control formulation of a GMWB pricing problem

  Y Huang, P A Forsyth, G Labahn
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  ABSTRACT: Discretized singular control problems in finance result in highly nonlinear algebraic equations which must be solved at each timestep. We consider a singular stochastic control problem arising in pricing a Guaranteed Minimum Withdrawal Benefit (GMWB), where the underlying asset is assumed to follow a jump diffusion process. We use a scaled direct control formulation of the singular control problem and examine the conditions required to ensure that a fast fixed point policy iteration scheme converges. Our methods take advantage of the special structure of the GMWB problem in order to obtain a rapidly convergent iteration. The direct control method has a scaling parameter which must be set by the user. We give estimates for bounds on the scaling parameter so that convergence can be expected in the presence of round-off error. Example computations verify that these estimates are of the correct order. Finally, we compare the scaled direct control formulation to a formulation based on an improved version of the penalty method. We show that the scaled direct control method has some advantages over the penalty method.
  03/2011;
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  Available from: jpier.org

  Article: FMCW based MIMO imaging radar for maritime navigation

  Y Huang, P V Brennan, D Patrick, I Weller, P Roberts, K Hughes
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  ABSTRACT: The berthing of large ships in inclement weather with frequently poor visibility presents a challenge. To assist with this application, it may be beneficial to utilise standard radar imaging. Whilst this may be achieved using a mechanically-scanned system, reliability, cost and weight issues, coupled with the need to primarily image only a 120 • sector on the port and starboard of the ship, make phased array radar an attractive possibility. Multiple-Input Multiple-Output (MIMO) radar, with its ability to enhance the resolution available from a given number of elements, is particularly suited to a short-range application such as this in which there is sufficient time to switch between antenna elements as an alternative to more complex implementations. This paper describes a system of this nature from its basic architecture to development and validation, including some artefacts of the particular topology employed.
  Progress In Electromagnetics Research. 01/2011; 115:327-342.
• Article: Turbulence and zonal flows in edge plasmas of the HL-2A tokamak

  K J Zhao, J Q Dong, L W Yan, W Y Hong, A Fujisawa, C X Yu, Q Li, J Qian, J Cheng, T Lan, A D Liu, H L Zhao, D F Kong, Y Huang, Yi Liu, X M Song, Q W Yang, X T Ding, X R Duan, Yong Liu
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  ABSTRACT: Measurements with a toroidally and poloidally displaced three-dimensional set of Langmuir probe arrays have revealed details of turbulence, geodesic acoustic modes (GAMs), zonal flows and their interactions in the edge region of HL-2A tokamak plasmas. The coexistence of intensive low frequency zonal flows (LFZFs) of f < 4 kHz and the GAMs of 7 kHz < fGAM < 20 kHz has been unambiguously demonstrated. The poloidal and toroidal symmetries of the flows, including the GAMs, are verified experimentally. In particular, the coherency of the flows over a large toroidal scale of 2100 mm at a magnetic flux surface is emphasized. The LFZF packets are shown to propagate outward and inward as equally likely events, whereas the predominantly outward propagation of the GAM packets is analyzed. The nonlinear three-wave coupling of the flows with ambient turbulence is shown with a bicoherency analysis and an envelope modulation of the latter by the former. The intensity of the LFZFs is observed to increase and decrease with increases in ECRH power (~300–700 kW) and safety factor q ~ (3.5–6.2), respectively, whereas the intensity of the GAMs increases with increases in both ECRH power and q.
  Plasma Physics and Controlled Fusion 11/2010; 52(12):124008. · 2.42 Impact Factor
• Source

  Available from: David McILveen-Wright

  Article: A Techno-economic assessment of the reduction of carbon dioxide emissions through the use of biomass co-combustion

  D R Mcilveen-Wright, Y Huang, S Rezvani, J D Mondol, D Redpath, M Anderson, N J Hewitt, B C Williams
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  ABSTRACT: a b s t r a c t Using sustainably-grown biomass as the sole fuel, or co-fired with coal, is an effective way of reducing the net CO 2 emissions from a combustion power plant. There may be a reduction in efficiency from the use of biomass, mainly as a result of its relatively high moisture content, and the system economics may also be adversely affected. The economic cost of reducing CO 2 emissions through the replacement of coal with biomass can be identified by analysing the system when fuelled solely by biomass, solely by coal and when a coal-bio-mass mixture is used. The technical feasibility of burning biomass or certain wastes with pulverised coal in utility boilers has been well established. Cofiring had also been found to have little effect on efficiency or flame stability, and pilot plant studies had shown that cofiring could reduce NO x and SO x emissions. Several technologies could be applied to the co-combustion of biomass or waste and coal. The assess-ment studies here examine the potential for co-combustion of (a) a 600 MWe pulverised fuel (PF) power plant, (i) cofiring coal with straw and sewage sludge and (ii) using straw derived fuel gas as return fuel; (b) a 350 MWe pressurised fluidised bed combustion (PFBC) system cofiring coal with sewage sludge; (c) 250 and 125 MWe circulating fluidised bed combustion (CFBC) plants cofiring coal with straw and sew-age sludge; (d) 25 MWe CFBC systems cofiring low and high sulphur content coal with straw, wood and woody matter pressed from olive stones (WPOS); and (e) 12 MWe CFBC cofiring low and high sulphur content coal with straw. The technical, environmental and economic analysis of such technologies, using the ECLIPSE suite of pro-cess simulation software, is the subject of this study. System efficiencies for generating electricity are eval-uated and compared for the different technologies and system scales. The capital costs of systems are estimated for coal-firing and also any additional costs introduced when biomass is used. The Break-even electricity selling price is calculated for each technology, taking into account the system scale and fuel used. Since net CO 2 emissions are reduced when biomass is used, the effect of the use of biomass on the elec-tricity selling price can be found and the premium required for emissions reduction assessed. Consideration is also given to the level of subvention required, either as a Carbon dioxide Credit or as a Renewable Credit, to make the systems using biomass competitive with those fuelled only with coal. It would appear that a Renewable Credit (RC) is a more transparent and cost-effective mechanism to sup-port the use of biomass in such power plants than a Carbon dioxide Credit (CC).
  10/2010;
• Source

  Available from: univagora.ro

  Article: Implementation of the Timetable Problem Using Self-assembly of DNA Tiles

  Z Cheng, Z Chen, Y Huang, X Zhang, J Xu, Zhen Cheng, Zhihua Chen, Yufang Huang, Xuncai Zhang, Jin Xu
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  ABSTRACT: DNA self-assembly is a promising paradigm for nanotechnology. Re-cently, many researches demonstrate that computation by self-assembly of DNA tiles may be scalable. In this paper, we show how the tile self-assembly process can be used for implementing the timetable problem. First the timetable problem can be con-verted into the graph edge coloring problem with some constraints, then we give the tile self-assembly model by constructing three small systems including nondetermin-istic assigning system, copy system and detection system to perform the graph edge coloring problem, thus the algorithm is proposed which can be successfully solved the timetable problem with the computation time complexity of Θ (mn), parallely and at very low cost.
  Int. J. of Computers. 01/2010; V:490-505.
• Source

  Available from: cigrjournal.org

  Article: Low-Level Atmospheric Temperature Inversions and Atmospheric Stability: Characteristics and Impacts on Agricultural Applications

  B K Fritz, W C Hoffmann, Y Lan, S J Thomson, Y Huang
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  ABSTRACT: Drift from aerial application of crop protection and production materials is influenced by many factors. The applicator is responsible for considering these factors and adjusting application techniques, where applicable, to reduce the potential for drift as much as possible. In an effort to study the uncontrollable factors and provide guidance for agricultural applicators, this study monitored and documented atmospheric conditions at two locations. The measured meteorological data was used to assess how atmospheric stability varied as a function of time of day, location, and other meteorological conditions. Additionally, inversion periods were examined for strength, time of occurrence, and duration. Stable and very stable atmospheric conditions, which would tend to produce the most drift, primarily occurred between the hours of 6 p.m. and 6 a.m., with a few occurrences between 6 a.m. and 6 p.m. Between the hours of 6 a.m. and 6 p.m., unstable atmospheric conditions tended to dominate. Of the days monitored, however, almost half experienced inversion periods between the hours of 6 a.m. and 6 p.m., with more than half of these inversion periods being after 4 p.m. and having durations an order of magnitude greater than periods of inversions seen between 6 a.m. and 4 p.m. Generally, these late afternoon periods are of most concern as the probability of experiencing increasingly stable conditions or long inversion periods increases. Based on these results, agricultural applicators should take caution when spraying in the morning or, most particularly, evenings, especially when wind speeds are below 2 m/s.
  04/2008;
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  Available from: asu.edu

  Article: Buckling of a stiff thin film on a compliant substrate in large deformation

  J Song, H Jiang, Z J Liu, D Y Khang, Y Huang, J A Rogers, C Lu, C G Koh
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  ABSTRACT: A finite-deformation theory is developed to study the mechanics of thin buckled films on compliant substrates. Pertur-bation analysis is performed for this highly nonlinear system to obtain the analytical solution. The results agree well with experiments and finite element analysis in wavelength and amplitude. In particular, it is found that the wavelength depends on the strain. Based on the accurate wavelength and amplitude, the membrane and peak strains in thin films, and stretch-ability and compressibility of the system are also obtained analytically.
  03/2008;
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  Available from: asu.edu

  Article: Bending buckling of single-walled carbon nanotubes by atomic-scale finite element

  X Guo, A Y T Leung, X Q He, H Jiang, Y Huang
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  ABSTRACT: This paper employs the atomic-scale finite element method to study bending buckling of single-walled carbon nanotubes (SWNTs). As the bending angle increases, kinks will appear and the morphology of the SWNT will change abruptly. The (15, 0) SWNT changes into a one-kinked structure, and finally contains two kinks; while the (10, 0) SWNT changes into a one-kinked structure, then into a two-kinked one, and finally contains three kinks. Strain energy grows initially as a quadratic function of bending angle, then increases gradually slowly, and finally changes approximately linearly. The energy releases suddenly at morphology bifurcations and the amount depends on degree of morphology change. The simulation shows that the appearance of kinks associated with the large deformation nearby reduces the slope of the strain energy curve in the post-buckling stages and hence increases the flexibility of the SWNTs.
  04/2007;
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  Available from: Jos A.A.J. Perenboom

  Article: High field magnetisation measurements on UIr in the ferromagnetic state

  S Sakarya, N H Van Dijk, A De Visser, E Bruk, Y Huang, J A A J Perenboom, H Rakoto, J.-M Broto
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  ABSTRACT: We have performed high field magnetisation measurements on the ferromagnetic order (T C ¼ 46 K) in single-crystalline UIr. The magnetisation along the easy axis shows a field saturation towards a moment of about 1 m B /U atom at T ¼ 4.2 K. No field-induced magnetic transition was observed for magnetic fields up to 52 T.
  Journal of Magnetism and Magnetic Materials30.Gw. 01/2007; 31050(75).
• Source

  Available from: Longwen Yan

  Article: Three-dimensional features of GAM zonal flows in the HL-2A tokamak

  L W Yan, J Cheng, W Y Hong, K J Zhao, T Lan, J Q Dong, A D Liu, C X Yu, D L Yu, J Qian, Y Huang, Q W Yang, X T Ding, Y Liu, C H Pan
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  ABSTRACT: A novel design of the three-step Langmuir probe (TSLP) array has been developed to investigate the zonal flow (ZF) physics in the HL-2A tokamak. Three TSLP arrays are applied to measure the three-dimensional (3D) features of ZFs. They are separated by 65 mm in the poloidal and 800 mm in the toroidal directions, respectively. The 3D properties of the geodesic acoustic mode (GAM) ZFs are presented. The poloidal and toroidal modes of the radial electric fields of the GAM perturbations are simultaneously determined in the HL-2A tokamak for the first time. The modes have narrow radial wave numbers (k r ρ i = 0.03–0.07) and short radial scale lengths (2.4–4.2 cm). High coherence of both the GAM and the ambient turbulence separated by toroidal 22.5 • along a magnetic field line is observed, which contrasts with the high coherence of the GAM and the low coherence of the ambient turbulence apart from the field line. The nonlinear three wave coupling between the turbulent fluctuations and the ZFs is a plausible mechanism for flow generation. The skewness and kurtosis spectra of the probability distribution function of the potential perturbations are contrasted with the corresponding bicoherence for the first time, which support the three wave coupling mechanism.
  Nucl. Fusion. 01/2007; 4735(52).
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  Available from: illinois.edu

  Article: The uniaxial tension of particulate composite materials with nonlinear interface debonding

  H Tan, Y Huang, C Liu, G Ravichandran, H M Inglis, P H Geubelle
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  ABSTRACT: Debonding of particle/matrix interfaces can significantly affect the macroscopic behavior of composite material. We have used a nonlinear cohesive law for particle/matrix interfaces to study interface debonding and its effect on particulate composite materials subject to uniaxial tension. The dilute solution shows that, at a fixed particle volume fraction, small particles lead to hardening behavior of the composite while large particles yield softening behavior. Interface debonding of large particles is unstable since the interface opening (and sliding) displacement(s) may have a sudden jump as the applied strain increases, which is called the catastrophic debonding. A simple estimate is given for the critical particle radius that separates the hardening and softening behavior of the composite.
  10/2006;
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  Available from: public.asu.edu

  Article: Postbuckling of carbon nanotubes by atomic-scale finite element

  A. Y. T. Leung, X. Guo, X. Q. He, H. Jiang, Y. Huang
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  ABSTRACT: This paper employs an atomic-scale finite element method (AFEM) to study the postbuckling behavior of carbon nanotubes (CNTs). The computed energy curves and critical strain for the (8, 0) single-walled CNT (SWNT) agree well with atomistic simulations. The AFEM is very fast and versatile owing to the efficiency of the finite element method. For the SWNT, the strain energy curves have obvious jumps at morphology changes, and during the smooth continuation stages of postbuckling, the strain energy varies approximately linearly with the strain. For the double-walled CNT, there are only small strain energy releases, and the strain energy also changes approximately piecewise linearly with the strain. The morphologies are obtained in detail. AFEM is computationally fast and is an alternative efficient way to study the postbuckling of CNTs.
  Journal of Applied Physics 06/2006; 99(12):124308-124308-5. · 2.17 Impact Factor
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  Available from: François Le Pennec

  Article: Antenna coupling in ray tracing based MIMO channel model

  Y Huang, S Saadaoui, Y Chartois, F Le Pennec, Ph Rostaing, R Vauzelle, Y Pousset
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  ABSTRACT: In this s ummary, we focus on the effect of mutual coupling between antennas in modelling MIMO in-door channel, for WLAN 5.4 GHz applications. Mutual coupling is derived from the rigorous electromagnetic analysis taking into account the specific dimensions and material constituting the antennas. Implementation of coupled antenna model is carried out within the Advanced Design System (ADS) of Agilent Electronic Design Automation (EDA) software. It enables one to analyse the effect of mutual coupling on the modulated s ignal flowing through the in-door MIMO channel under consideration. 1 INTRODUCTION Because of some compromise between performances and cost, processing and hardware have to be optimised. Hence, modelling accurately the overall communication path in modern wireless systems has become a strategic challenge. Electronic Design Automation (EDA) frameworks offer to designers more and more powerful software tools for achieving such goals. They provide mixed simulation of digital data and analogue signals up to the radio frequency. However, during the modelling stage, a designer has to implement the appropriate model to include all relevant effects. Different modelling levels may have some great impact on the simulation time and accuracy. In Multiple Input Multiple Output (MIMO) wireless systems, with the use of multiple antennas, the performance and the capacity of wireless systems are substantially improved. This is based on the assumption that the parallel subchannels are independent or uncorrelated. However, the physical limitations in portable devices imposes that multiple antennas to be closely spaced. This generates some considerable amount of mutual coupling between antenna elements. The mutual coupling i s significant and it may increase or decrease the correlation between individual subchannels, thus degrade or improve the MIMO system performances [1-4]. As a result, antennas should be carefully modelled in order to include these significant effects when considering the MIMO radio propagation channel. The present paper focuses on modelling the mutual coupling between antennas in a MIMO 2X2 in-door configuration.
  04/2005;
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  Available from: hku.hk

  Article: The depth-profiled carrier concentration and scattering mechanism in undoped GaN film grown on sapphire

  Y Huang, X D Chen, S Fung, C D Beling, C C Ling, Z F Wei, S J Xu, C Y Zhi
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  ABSTRACT: Temperature-dependent Hall TDH measurements and confocal micro-Raman spectroscopy have been used to study the free carrier spatial distribution and scattering mechanism in unintentionally doped GaN film grown on the sapphire substrate with the method of metalorganic chemical vapor deposition. Both the TDH data and the depth-profiled Raman spectra agreed with the existence of a nonuniform spatial distribution of free carriers in the GaN film with a highly conductive layer of 1 m thickness near the GaN sapphire boundary. With the consideration of this parallel conduction channel adjacent to GaN sapphire boundary, detailed analysis of the TDH mobility data suggests that a relatively high concentration of nitrogen vacancies exists and nitrogen vacancy scattering has an important influence on limiting the electron mobility in the bulk film of the present GaN sample. © 2004 American Institute of Physics.
  Citation Journal of Applied Physics. 01/2004; 96(2):1120-1126.
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  Available from: illinois.edu

  Article: An atomistic-based continuum theory for carbon nanotubes: analysis of fracture nucleation

  P Zhang, H Jiang, Y Huang, P H Geubelle, K C Hwang
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  ABSTRACT: Carbon nanotubes (CNTs) display unique properties and have many potential applications. Prior theoretical studies on CNTs are based on atomistic models such as empirical poten-tial molecular dynamics (MD), tight-binding methods, or ÿrst-principles calculations. Here we develop an atomistic-based continuum theory for CNTs. The interatomic potential is directly incorporated into the continuum analysis through constitutive models. Such an approach in-volves no additional parameter ÿtting beyond those introduced in the interatomic potential. The atomistic-based continuum theory is then applied to study fracture nucleation in CNTs by mod-elling it as a bifurcation problem. The results agree well with the MD simulations.
  Journal of the Mechanics and Physics of Solids 01/2004; 52:977-998. · 2.81 Impact Factor
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  Available from: asu.edu

  Article: Fracture analysis in the conventional theory of mechanism-based strain gradient (CMSG) plasticity

  S Qu, Y Huang, H Jiang, C Liu, P D Wu, K C Hwang
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  ABSTRACT: In a remarkable series of experiments, Elssner et al. (1994) and Korn et al. (2002) observed cleavage cracking along a bimaterial interface between Nb and sapphire. The stress required for cleavage cracking is around the theoretical strength of the material. Classical plasticity models fall short to reach such a high stress level. We use the conventional theory of mechanism-based strain gradient plasticity (Huang et al., 2004) to investigate the stress field around the tip of an interface crack between Nb and sapphire. The tensile stress at a distance of 0.1 µm to the interface crack tip reaches 13.3σ Y , where σ Y is the yield stress of Nb. This stress is nearly 4 times of that predicted by classical plasticity theory (3.6σ Y) at the same distance to the crack tip, and is high enough to trigger cleavage cracking in materials and interfaces. This is consistent with Elssner et al.'s (1994) and Korn et al.'s (2002) experimental observations.
  International Journal of Fracture. 01/2004; 129:199-220.
• Article: [Cases-Control association study and transmission disequilibrium test of T102C polymorphism in 5HT2A and Tourette syndrome].

  Y Huang, X Liu, T Li, L Guo, X Sun, X Xiao, X Ma, Y Wang, D A Collier
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  ABSTRACT: To investigate whether T102C polymorphism in 5HT2A (serotonin receptor 2A) is associated with Tourette syndrome. Both case-control association analysis and Transmission Disequilibrium Test(TDT), in addition to polymerase chain reaction and RFLP technique were used in 157 trios with Tourette syndrome (TS) and 120 controls. A semi-structured "Schedule for Tourette and other behavioral syndrome" was used in family history-collecting. Both the criteria of "Diagnostic and Statistical Manual of Mental Disorders"(DSM-IV) and that of Tourette syndrome association (TSA) were used in the diagnosis of Tourette syndrome and related disorders. The association between T102C polymorphism in 5HT2A and Tourette syndrome comorbided with obsessive compulsive disorder (OCD) was found by genotype-wise analysis (chi(2)=8.38,P=0.004) and allele-wise analysis (chi(2)=4.84,P=0.028), which was further confirmed by TDT analysis (chi(2)=5.12,P=0.02). No evidence of association or transmission disequilibrium between 102T/C polymorphism in 5HT2A and this disease in pure TS and total TS sample was found. 102T/C polymorphism in 5HT2A is exclusively associated with Tourette syndrome comorbided with DSM-IV OCD, which may constitute an independent subtype of Tourette syndrome.
  Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 03/2001; 18(1):11-3.
• Source

  Available from: Gina H. Clarke

  Article: Abrupt climatic events during the last glacial-interglacial transition in Alaska

  Feng Sheng Hu, David M Nelson, Gina H Clarke, Kathleen M Rühland, Yongsong Huang, Darrell S Kaufman, John P Smol, Citation : Hu, D M Nelson, G H Clarke, K M Rühland, Y Huang, D S Kaufman, J P Smol
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  ABSTRACT: 1] Evidence is mounting that abrupt climatic shifts occurred during the last glacial-interglacial transition (LGIT) in the North Atlantic and other regions. However, few high-resolution climatic records of the LGIT exist from the high latitudes of the North Pacific rim. We analyzed lake sediments from southwestern Alaska for biogenic silica, organic carbon, organic nitrogen, diatom assemblages, and compound-specific hydrogen isotopes. Results reveal climatic changes coincident with the Younger Dryas, Intra-Allerød Cold Period, and Pre-Boreal Oscillation. However, major discrepancies exist in the paleoclimate patterns of the Bølling-Allerød interstadial between our data and the GISP2 18 O record from Greenland, and causes are uncertain. These data suggest that the North Pacific and North Atlantic experienced similar reversals during climatic warming of the LGIT but that the Bølling-Allerød cooling trend in the GISP2 18 O record is probably not a hemispheric or global pattern. (2006), Abrupt climatic events during the last glacial-interglacial transition in Alaska, Geophys. Res. Lett., 33, L18708, doi:10.1029/2006GL027261.
• Source

  Available from: illinois.edu

  Article: The elastic modulus of single-wall carbon nanotubes: a continuum analysis incorporating interatomic potentials

  P Zhang, Y Huang, P H Geubelle, P A Klein, K C Hwang
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  ABSTRACT: A nanoscale continuum theory is established to directly incorporate interatomic potentials into a continuum analysis without any parameter fitting. The theory links interatomic potentials and atomic structure of a material to a con-stitutive model on the continuum level. The theory is applied to study the linear elastic modulus of a single-wall carbon nanotube. The Young's modulus predicted by this nanoscale continuum theory agrees well with prior experimental results and atomistic studies.