-
[show abstract]
[hide abstract]
ABSTRACT: Recently, many researchers had reported their work about sub- and superluminal propagation. And several experiments had demonstrated
the signal evolution of slow and fast light. In this letter, the authors described a simple experiment for the tracing of
the light signal in saturated absorption (SA) and reverse saturated absorption (RSA) media, firstly. We had, directly, observed
the evolution of slow and fast signals with different waveforms that traveled in a ruby crystal and C60. Through tracking the signal when slow light (v
g
≪
c) and fast light (v
g<0) was observed in a ruby crystal and C60, we concluded that asymmetrical absorption on the periodical signal could account for the generation of slow and fast light
in SA and RSA media.
Applied Physics B 04/2012; 92(4):487-491. · 2.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Under the generalized gradient approximation (GGA), the
electronic and magnetic properties are studied for H-terminated zigzag edge
Si nanoribbon (ZSiNR) decorated with a singleC chain by using the
first-principles projector augmented wave (PAW) potential within the density
function theory (DFT) framework. The results show that either a perfect
ZSiNR or a singleC chain decorated ZSiNR, the ferromagnetic state is
preferred over the antiferromagnetic state. But a singleC chain decorated
ZSiNR is more stable than the perfect one. Furthermore, the electronic and
magnetic properties of a ZSiNR can be modulated in detail by a singleC
chain at different positions.
Physics of Condensed Matter 04/2012; 79(2):197-202. · 1.53 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Emergency braking plays an important role in the safety of overhead crane systems; however, it has received little attention so far. Motivated by this fact, two practical guidelines for the emergency braking control of overhead crane systems are proposed, which are safety and efficiency in brief. Based on the guidelines, a novel two-stage switching control strategy is then presented to improve operation safety. Specifically, at the first stage, a braking controller is exerted on the trolley to prevent the payload from moving forward as soon as possible. At the second stage, an energy-based damping controller is adopted to stabilise the overall system rapidly. These two controllers are switched automatically and the switching time is selected carefully to ensure satisfactory control performance. Both simulation and experimental results are presented to demonstrate the effectiveness of the proposed braking control method.
IET Control Theory and Applications 10/2010; · 0.99 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In a recent quasi-elastic neutron scattering experiment on water confined in a Portland cement paste, we find that this 3D confined water shows a dynamic crossover phenomenon at T(L) = 227 ± 5 K. The DSC heat-flow scan upon cooling and an independent measurement of specific heat at constant pressure of confined water in silica gel show a prominent peak at the same temperature. We show in this paper that this type of behavior is common to many other glassy liquids, which also show the crossover temperature in coincidence with the temperature of a small specific heat peak. We also demonstrate with MD simulations that the dynamic crossover phenomenon in confined water is an intrinsic property of bulk water, and is not due to the confinement effect. Recently, an extended version of the mode coupling theory (MCT) including the hopping effect was developed. This theory shows that, instead of a structural arrest transition at T(C) predicted by the idealized MCT, a fragile-to-strong dynamic crossover phenomenon takes place instead at T(C), confirming both the experimental and the numerical results. The coherent and incoherent α relaxation times can be scaled with the calculated viscosity, showing the same crossover phenomenon. We thus demonstrated with experiments, simulations and theory that a genuine change of dynamical behavior of both water and many glassy liquids happens at the crossover temperature T(L), which is 10-30% higher than the calorimetric glass transition temperature T(g).
Journal of Physics Condensed Matter 12/2009; 21(50):504102. · 2.55 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Using data on age at 100 kg of three pig breeds (Large White, Landrace and Duroc) the connectedness between herds in China was evaluated by the connectedness rating (CR) method. The results show that most herds in China have low average CR (0-3.59%) with other herds. In Large White, of the 36 herds analyzed there are 20 herds, which are connected with at least one other herd. In Landrace and Duroc, of the 27 and 18 herds analyzed, only four and five herds, respectively, were found having connectedness with other herds. Generally, the connectedness exists only among two or few herds in the same region. A certain degree of connectedness between herds is a precondition for cross-herd genetic evaluation. A national or regional cross-herd genetic evaluation is not practicable at the present time in China. More intense efforts are needed to establish and enhance the connectedness between herds by means of extensively using artificial insemination (AI) in the swine industry in China.
animal 04/2009; 3(4):482-5. · 1.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bovine placental lactogen (bPL) is structurally related to prolactin (PRL) and growth hormone (GH). In synergism with steroid and thyroid hormones, bPL is crucial in stimulating the development of the mammary gland, mammary cell differentiation and function. To further explore whether bPL gene is associated with milk production traits, we herein analyzed single-nucleotide polymorphisms (SNPs) within eight regions of bPL gene, which are potentially associated with five milk production traits on 1028 Chinese Holstein cows. Among these, two SNPs, NT7409(T-C) and Nt11246(G-A), were identified. The former is within exon 2; it induces an alteration of amino acid from Val to Ala. The later is within exon 4. It is a synonymous mutation. We found that there were significant associations between NT7409(T-C) and milk and protein yield. Cows of the AA genotype yielded less milk (P = 0.001) and less protein (P = 0.003) than those of genotypes AB and BB. However, on the NT11246(G-A) locus, no significant association was observed in the five milk production traits studied. In addition, bPL has been localized near markers RM185 and CC549051 with a distance of 23.2 cR on BTA 23. It is at the same position as the region including quantitative trait loci (QTLs) affecting milk and protein yields by previous linkage analysis. In summary, our findings demonstrated that the SNP within exon 2 of bPL (NT7409(T-C)) is associated with two milk production traits, and this provided further evidence that bPL could be a major gene-controlling milk production trait in Holstein dairy cattle.
animal 01/2009; 3(1):1-5. · 1.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Ba0.6Sr0.4TiO3 (BST) thin films for the tunable microwave devices were grown using pulsed laser deposition (PLD) on Pt/Ti/SiO2/Si (Pt–Si) substrates with La0.5Sr0.5CoO3 (LSCO) buffer layers. For comparison, the films were also grown on Pi-Si substrates. X-ray diffraction results showed that
the BST films on Pt–Si displayed a highly (110) preferred orientation, while the films with the LSCO buffer layers were (100)-oriented.
Atomic force microscope (AFM) revealed that BST films with LSCO buffer layers had smoother surface and smaller grain size.
Compared with (110) BST films, the (100) BST thin films had the higher tunability and the better figure of merit (FOM). The
dielectric constant, the dielectric loss and the tunability of the BST thin films on LSCO/Pt–Si substrates measured at 10kHz
were 1010, 0.031 and 82.4%, respectively. Additionally, the current–voltage(I–V) measurement indicated that the leakage current density of (100) BST thin films on LSCO/Pt-Si substrates was reduced compared
with that of (110) BST thin films directly on Pt electrodes, due to the possible reduction of interface oxygen vacancies at
BST/LSCO interface and smaller grain size of the films. The enhancement in dielectric properties may be attributed to (100)
preferred orientation in the films.
Journal of Materials Science Materials in Electronics 04/2008; 19(5):429-433. · 1.08 Impact Factor
-
Sow‐Hsin Chen,
F. Mallamace,
L. Liu,
D. Z. Liu,
X. Q. Chu, Y. Zhang,
C. Kim,
A. Faraone,
C.‐Y. Mou,
E. Fratini,
P. Baglioni,
A. I. Kolesnikov,
V. Garcia‐Sakai
[show abstract]
[hide abstract]
ABSTRACT: We have observed a Fragile‐to‐Strong Dynamic Crossover (FSC) phenomenon of the α‐relaxation time and self‐diffusion constant in confined supercooled water. The α‐relaxation time is measured by Quasielastic Neutron Scattering (QENS) experiments and the self‐diffusion constant by Nuclear Magnetic Resonance (NMR) experiments. Water is confined in 1‐d geometry in cylindrical pores of nanoscale silica materials, MCM‐41‐S and in Double‐Wall Carbon Nanotubes (DWNT). The crossover phenomenon can also be observed from appearance of a Boson peak in Incoherent Inelastic Neutron Scattering experiments. We observe a pronounced violation of the Stokes‐Einstein Relation at and below the crossover temperature at ambient pressure. Upon applying pressure to the confined water, the crossover temperature is shown to track closely the Widom line emanating from the existence of a liquid‐liquid critical point in an unattainable deeply supercooled state of bulk water. Relation of the dynamic crossover phenomenon to the existence of a density minimum in supercooled confined water is discussed. Finally, we discuss a role of the FSC of the hydration water in a biopolymer that controls the biofunctionality of the biopolymer.
AIP Conference Proceedings. 02/2008; 982(1):39-52.
-
Journal of Physics Condensed Matter 01/2008; 20:502101. · 2.55 Impact Factor
-
Journal of Materials Science 12/2007; 43(1):409-412. · 2.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The microstructural properties of heteroepitaxial ZnO thin films prepared by laser molecular beam epitaxy (L-MBE) were investigated on SrTiO3 substrates and BaTiO3/SrTiO3 pseudo substrates with different orientations. The interface characteristics were in situ monitored by reflection high-energy electron diffraction (RHEED), and the epitaxial orientation relations were reconfirmed by ex situ x-ray diffraction (XRD) measurements. ZnO films grown on SrTiO3(0 0 1) and BaTiO3/SrTiO3(0 0 1) contained a poly-domain structure. For the former, the lattice mismatch was about −1.7% by four types of domain growth with the epitaxial relation of ZnO(1 1 0)||SrTiO3(0 0 1) and ZnO[−1 1 1]|| SrTiO3100. For the latter, twin domains would result in a smaller mismatch of −0.8% by the epitaxial relation of ZnO(0 0 1)||BaTiO3(0 0 1) and ZnO[1 1 0]|| BaTiO31 1 0. On SrTiO3(1 1 1) and BaTiO3/SrTiO3(1 1 1), single-domain films following the c-axial direction were observed with in-plane orientation ZnO[1 1 0]||SrTiO3[1 1 0] and ZnO[1 0 0]||BaTiO3[1 1 0], respectively. This 30° rotation in the in-plane direction of the ZnO epilayer with respect to the perovskite surfaces increased the lattice mismatch from about −2% to −14.5% after inserting BaTiO3 layers. The orientation of ZnO films could be attributed to the characteristic difference of the interface energy. It is determined entirely by interface stress and crystallographic symmetry for the growth on nonpolar (0 0 1)-orientated perovskite surfaces while the competition between elastic energy and chemical energy plays an important role for that on polar (1 1 1)-surfaces.
Journal of Physics D Applied Physics 11/2007; 40(23):7502. · 2.54 Impact Factor
-
Journal of Physics and Chenmistry of Solids. 01/2007; 68:503-510.
-
[show abstract]
[hide abstract]
ABSTRACT: Hole-doped double perovskite compounds (Sr,Na)2FeMoO6 with the Na content of x=0,0.02,0.03,0.07 and 0.17 have been synthesized by sol–gel method. Effects of hole doping on the crystal structure and magnetic properties of Sr2FeMoO6 have been investigated by means of X-ray powder diffraction (XRD) and magnetic measurements. The XRD pattern indicates that all the samples are of single phase and belong to the space group I4/m. Due to the smaller ionic radius of Na+ than that of Sr2+ ions, the lattice constants and unit cell volume of the compound decrease slightly with x. The degree of cation ordering in the Na-doped Sr2FeMoO6 compounds shows a non-monotonic variation with the doping level, increasing from x=0 to x=0.03 and decreasing slightly with further increase of the doping. In contrast to the composition dependence of the degree of ordering, the Curie temperature of the compound decreases at low doping level and increases at high doping level. The saturation magnetization of the compound increases with x for x<0.17. Similar to the electron-doped Sr2FeMoO6, provided that the doped hole enters selectively the spin-down band, the variation of the saturation magnetization can be explained in light of the ferrimagnetic model (FIM).
Applied Physics A 08/2006; 84(4):459-463. · 1.63 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Visible and infrared photoluminescence was observed from AlN:Er films grown by reactive radio-frequency magnetron sputtering under different powers. X-ray diffraction indicates that the films have a c-axis oriented hexagonal wurtzite structure with an average crystallite size of about 59–83 nm and a strain of about (1.12–1.69)×10−3. Green emissions ( ∼ 540 and 558 nm) from the AlN:Er films are due to the intra-4fn transition of Er3+ from and to , and infrared ( ∼ 1535 nm) emissions correspond to to transitions. Increasing the sputtering power results in larger grain size, lower strain, and enhancement of the luminescence intensity.
Journal of Applied Physics 03/2006; 99(5):053515-053515-5. · 2.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A theoretical model, based on the Fresnel diffraction integral, is developed to describe the thermal lens (TL) signal in a mode-mismatched collinear configuration, which is optimized for a near field detection scheme and excitation by a cw modulated laser beam with a top-hat profile. The TL amplitudes obtained with both top-hat and Gaussian beam excitations are numerically computed and compared, and the dependence of the TL amplitude on the experimental parameters is discussed. Numerical results show that the top-hat beam TL instrument is more sensitive than the Gaussian beam TL instrument, with a potential doubling of the sensitivity. The use of the top-hat beam excitation with TL detection is a significant improvement because a top-hat beam can be easily obtained with a low-cost, wide-spectral emission white-light source. The use of incoherent light sources as the excitation sources would substantially expand the applicability of the TL technique to the general area of chemical analysis.
Applied Physics B 03/2005; 80(4):527-534. · 2.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The crystal structure and magnetic properties of Sm Co <sub>7-x</sub> Hf <sub>x</sub> (x=0.05,0.1,0.2,0.3) compounds were studied by means of x-ray powder diffraction and magnetic measurements. The as-cast compounds Sm Co <sub>7-x</sub> Hf <sub>x</sub> with x=0.1 and 0.2 crystallize in the Tb Cu <sub>7</sub> -type structure with the space group P 6 /mmm . According to the structure refinement, the doping element Hf prefers to occupy the 2e site. The compounds have high Curie temperatures ( 1080 K for x=0.1 , 1075 K for x=0.2 ), large saturation magnetization ( 104 emu / g for x=0.1 , 102 emu / g for x=0.2 at 5 K ), and large magnetic anisotropy fields ( 244 kOe for x=0.1 , 282 kOe for x=0.2 at 5 K ) with strong uniaxial magnetocrystalline anisotropy.
Applied Physics Letters 12/2004; · 3.84 Impact Factor
-
Z. Iqbal, Y. Zhang,
H. Grebel,
S. Vijayalakshmi,
A. Lahamer,
G. Benedek,
M. Bernasconi,
J. Cariboni,
I. Spagnolatti,
R. Sharma,
F.J. Owens,
M.E. Kozlov,
K.V. Rao,
M. Muhammed
[show abstract]
[hide abstract]
ABSTRACT: Evidence is presented for the formation of a solid phase based on the smallest fullerene, C20, in thin diamond-like carbon films deposited by ultraviolet laser ablation from diamond onto nickel substrates at room temperature
in the presence of 10-4 torr of cyclohexane or benzene. Laser desorption mass spectrometry from the films shows the presence of C20, C21 and C22 species, while micro-Raman spectroscopy and electron diffraction from selected particles together with first principle density-functional
calculations, indicate a cubic solid with dodecahedral C20 cages as building blocks. Unlike solid C60 and fully protonated C20, which are bound by van der Waals forces, the proposed structure is stabilized by linking of the C20 dodecahedra with bridging carbon atoms at interstitial tetrahedral sites to form a face-centered-cubic lattice with 22 carbon
atoms per unit cell.
Physics of Condensed Matter 01/2003; 31(4):509-515. · 1.53 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The AlxGa1-xN alloy nanocrystalline solids with x=0-1 were successfully synthesized through ammono-thermal routes. The alloys were formed
only in the form of nanocrystalline solids, and not in other forms, i.e. of nano-powders or micro-crystals. The Raman scattering
spectra of the alloy solids within the whole range of x values were investigated. One-mode-type behavior of A1(LO) phonon and two-mode-type behavior of E2 phonon were clearly demonstrated. The intensity of E2(GaN) mode decreases as x increases up to x=0.8. For A1(TO), A1(LO), and E2(GaN) phonon modes, the linewidth behaviors follow a pattern that exhibits a maximum at composition x=0.5.
Applied Physics A 12/2000; 72(1):125-127. · 1.63 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A new model based on crystal–plasticity, crystallography, thermodynamics, kinetics and statistics is developed for stress–assisted martensitic transformation. The model includes the essential features of the stress–assisted martensitic transformation, such as: nuclei of progressively lower potency are activated in the course of transformation, the martensite phase appears in the form of thin plates, the parent phase exerts a higher resistance toward the growth of a plate in the thickness than in the radial direction, the average plate size decreases while the average plate aspect ratio increases with the extent of transformation, etc. The model is implemented in the commercial finite element code ABAQUS/Standard to analyze the evolution of martensite, materials texture and the resulting equivalent stress–equivalent strain curve during the stress–assisted martensitic transformation under different stress and strain states in a polycrystalline Ti–10V–2Fe–3Al (wt.%) alloy. The equivalent stress–equivalent strain curves and the volume fraction of martensite–equivalent strain curves are found to be mainly controlled by the applied stress state. Conversely, the texture observed in the transformed Ti–10V–2Fe–3Al is found to be primarily controlled by the imposed macroscopic strain state. The validity of the proposed materials constitutive model has been established by demonstrating a reasonable agreement between the model predictions and the available experimental data.
Journal of Materials Science 01/2000; 35(18):4635-4647. · 2.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Retinas are very important for human beings to get information about their environment. In this paper, we propose a new method
to build artificial retinas which have many features similar to real ones. We use evolutionary cellular automata to extract
some basic characteristics of objects, and use self-organizing neural networks to distinguish different objects. The results
indicate a way to get computer vision by artificial life.
Artificial Life and Robotics 05/1999; 3(2):61-64.
