The thermal properties of single-walled boron nitride nanotubes are calculated. It is found that have a larger specific heat than carbon nanotubes. fitting formulas for diameter and chirality dependence at 300 K given. Moreover, conductance exhibits universal quantization low temperature, which independent the

Considering the three-phonon process, we calculate thermal conductivity of zigzag tubes. It is found that an isolated (6, 0) single-walled carbon nanotube increases with increase temperature at low temperature, and would show a peak behavior about 85 K before falling off high temperature. Moreover, for nanotubes small diameters as compared to tubes large diameters. The 300 approximately inversely proportional tube's diameter.

Aesthetics primarily focuses on the study of art, encompassing aesthetic categories beauty and ugliness, as well human activities. Image Assessment (IAA) seeks to automatically evaluate quality images by mimicking perceptual mechanisms humans. Recently, researchers have increasingly explored using user comments assist in IAA tasks. However, aesthetics are subjective, individuals may varying preferences for same image, leading diverse that can influence model decisions. Moreover, practical...

The atomic structures and electronic properties of small TiN (N=2–10) clusters have been studied by using the density-functional theory with a local spin density approximation. We find that inner-shells (3s3p) titanium atom plays an important role in formation clusters. obtained ground state clusters, Ti7 is found to be magic cluster, which good agreement experimental results. Starting Ti8 cluster some features structure bulk developed. ionization potentials magnetic moments for these are...

To describe accurately the electronic structures of carbon nanotubes, a semi-empirical tight-binding approach is presented in which main intrinsic curvatures have been fully taken into account. The calculated and band gaps are consistent with experimental measurements. Studies relative importance various show that each curvature has contribution varying to curvature-induced gap. Additionally, under both uniaxial torsional strain, semiconductor–metal–semiconductor phase transitions observed...

Based on a force constant model, we have calculated the phonon spectrum and specific heat of single-walled boron nitride nanotubes. Compared with carbon nanotubes, nanotubes larger heat. The fitting formulas for diameter chirality dependence at 300 K are given.

Using first-principles calculations, we investigate the comparative stability of sub-0.4 nm carbon nanotubes. Compared to fullerenes C20 and C60, it is found that most likely nanotubes with a small diameter 0.3 are (2,2),(3,1) (4,0) The spontaneous symmetry breaking an isolated (2,2) nanotube produces energy gap at Fermi level converting into semiconductor. curvature effects lowered π* band cross energy, leading being metallic.

The rate of relaxation zigzag single-walled carbon nanotubes is calculated by consideration three-phonon Umklapp process. results show that the increases exponentially with phonon frequency at low frequency. linear dependence on temperature obtained. It shown value mean free path reaches a few micrometres, which consistent estimated experimental result.

Abstract Accurate prediction of shield attitude deviation is essential to ensure safe and efficient tunneling. However, previous studies have predominantly emphasized temporal correlation, which has limitations in engineering guidance accuracy. This research proposes a hybrid deep learning approach considering feature attention (FTA-N-GRU) for prediction. To elucidate the contributions each parameter, Integrated Gradients algorithm leveraged parameter sensitivity analysis. The results from...

We present a simple sp3s* tight-binding model for use in calculating the band structures of single-walled carbon nanotubes. The 2s, 2px, 2py, 2pz, and s* orbitals each atom are used as basis set expressing model, interatom interaction between neighbouring sites is fully taken into account. elements Hamiltonian matrix related parameters obtained by adjusting to fit primary reflectivity photoemission band-structure data. have employed this investigating [n,0] (n = 6,7,8,9) Our band-gap results...

Based on the energy of a relaxed carbon nanotube relative to graphite sheet (graphene), we construct an analytical correction carbon-carbon force constants. Then, radial breathing modes (RBM) number single-walled nanotubes (SWNTs) are calculated. It is found that for small diameter SWNTs, curvature effect becomes significant and chirality dependent. Our calculated RBMs in very good agreement with experimental measurements, especially ultrasmall SWNTs.

The candidate structures for the ground-state geometry of Al(7)M (M = Li, Cu, Ag, and Au) clusters are obtained within spin-polarized density functional theory. Absorption energy, vertical ionization potential, electron affinity, energy gap between highest occupied molecular orbital (HOMO) level lowest unoccupied (LUMO) have been calculated to investigate effects doping. Doping with Ag or Au can lead a large HOMO-LUMO gap, low increased potential Al(7) cluster. In lowest-energy structure...

The phonon dispersion relation and specific heat of single-walled ${\mathrm{BC}}_{3}$ nanotubes have been investigated using a force constant model. obtained sheet reproduces well the experimental data. tube-diameter dependent frequencies both radial breathing mode lowest ${E}_{2\mathrm{g}}$ can be fitted by power law $\ensuremath{\omega}=C∕{R}^{\ensuremath{\alpha}}$ with tube radius $R$, where scaling exponent $\ensuremath{\alpha}=1$ proportional...

The design and image reconstruction aspects of a head SPECT (single photon-emission computerized tomography), body SPECT, PET (photon emission tomography) system, all based on 13-cm-diameter position-sensitive photomultiplier tubes (PSPMTs) have been investigated. Wobbling is introduced to improve the resolution from 1.2 cm 0.9 at 10 cm. By combining data adjacent tubes, ring improved 2.1 1.7 20 Sampling gaps are reduced in after one rotational increment. Results computer simulation studies...

By using the first-principles method, authors study strain effects on hydrogen desorption surface of single-walled carbon nanotubes (SWCNTs). It is found that chemisorbed doped with Pd can be released under large radial strain, for desorbed atoms are molecularly bound by several tenths an eV. The method expected to release residual SWCNTs.

The authors present a maximum posteriori (MAP) estimation algorithm that includes prior information, derived from registered magnetic resonance (MR) scans of the subject, in reconstruction process. PET images are modeled as number homogeneous activity regions with abrupt changes at boundaries between these regions. These likely to have close correspondence anatomical MR images. Thus, extracted segmented constitute source information. searches for smoothed discontinuities favored by both data...

The design and image reconstruction aspects of dynamic SPECT (single-photon-emission computed tomography) instrumentation utilizing multiple rings position-sensitive photomultiplier tubes (PSPMTs) are reported. A diverging cone-beam collimator is attached to each PSPMT achieve a 22-cm-diameter spherical field view in system designed for head imaging. resolution with the estimated be approximately 20% worse than parallel hold collimator. Iterative direct algorithms have been investigated...

Equilibrium geometries, stabilities, electronic and magnetic properties of Ti n Al (n=1–8) clusters have been studied by using density-functional theory (DFT). The ground-state structures obtained. resulting geometries show that the aluminum atom remains on surface clusters. evolution energy difference gap (HOMO–LUMO) with size cluster shows 4 to be endowed special stability. average moments density states (DOS) are also presented.