Tuning thermal transport in nanotubes with topological defects

Using the atomistic nonequilibrium Green's function, we find that thermal conductance of carbon nanotubes with presence of topological lattice imperfects is remarkably reduced, due to the strong Rayleigh scattering of high-frequency phonons. Phonon transmission across multiple defects behaves as a cascade scattering based with the random phase approximation. We elucidate that phonon scattering by structural defects is related to the spatial fluctuations of local vibrational density of states (LVDOS). An effective method of tuning thermal transport in low-dimensional systems through the modulation of LVDOS has been proposed. Our findings provide insights into experimentally controlling thermal transport in nanoscale devicesComment: 10 pages, 3 figure

2-Methyl­anilinium 3,4,5,6-tetra­bromo-2-(meth­oxy­carbon­yl)benzoate methanol monosolvate

In the anion of the title compound, C7H10N+·C9H3Br4O4 −·CH3O, the dihedral angles formed by the benzene ring and the mean planes of the carboxyl­ate and meth­oxy­carbonyl groups are 74.8 (5) and 75.0 (5)°, respectively. In the crystal, inter­molecular N—H⋯O and O—H⋯O hydrogen bonds link the components into chains along [100]. Additional stabilization is provided by weak inter­molecular C—H⋯O hydrogen bonds

Fuzzy Adaptive PID Control of a New Hydraulic Erecting Mechanism

Conventional erecting mechanism is cumbersome and the erecting velocity is slow, so a new hydraulic erecting mechanism is introduced in this paper. But it has two problems. First is the cooperation problem between the erect cylinder and the horizontal cylinder. Second, the nonlinearities and uncertainties exist in the system make the control precision poor. So the combined simulation model is built based on the software AMESim and Simulink. And from this model, the best cooperation time is confirmed. Further, the fuzzy adaptive PID controller is introduced to improve the control performance aiming to the nonlinearities and uncertainties. The fuzzy inference rules and parameters of the controller are also presented in this paper. Experiment results show that the cooperation time which received from the simulation is correct, and the fuzzy adaptive PID controller has nice tracking performance compared to the conventional PID controller and fuzzy controller

2-Methyl­propan-2-aminium 3,4,5,6-tetra­bromo-2-(meth­oxy­carbon­yl)benzoate methanol monosolvate

In the crystal structure of the title compound, C4H12N+·C9H3Br4O4 −·CH4O, inter­molecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds link the components into columns stacked along the b axis. Between the columns, short Br⋯O contacts [3.122 (4) Å] and C—H⋯O hydrogen bonds are observed

2-Hy­droxy­ethanaminium 3,4,5,6-tetra­bromo-2-(meth­oxy­carbon­yl)benzoate methanol monosolvate

In the title compound, C2H8NO+·C9H3Br4O4 −·CH4O, inter­molecular N—H⋯O and O—H⋯O hydrogen bonds link the components into chains along [001]

Metascreen-Based Acoustic Passive Phased Array

Conventional phased arrays require a large number of sources in forming a complex wave front, resulting in complexity and a high cost to operate the individual sources. We present a passive phased array using an acoustic metascreen that transmits sound energy from a single source and steers the transmitted wave front to form the desired fields. The metascreen is composed of elements that have a discrete resolution along the screen at an order smaller than the wavelength, allowing for fine wave-front shaping beyond the paraxial approximation. The performance is verified in experiment by forming a self-bending beam. Our metascreen-based passive array with its simplicity and capability has applications in places where conventional active arrays are complex and have limitations.Acoustical Society of AmericaNational Basic Research Program of China (973 Program) 2010CB327803 2012CB921504National Natural Science Foundation of China 11174138 11174139 11222442 81127901 11274168Physic