1,302 research outputs found
1,5-Bis[1-(2,4-dihyÂdroxyÂphenÂyl)ethylÂidene]carbonohydrazide dimethylÂformamide disolvate
In the title compound, C17H18N4O5·2C3H7NO, two solvent molÂecules are linked to the main molÂecule via N—H⋯O and O—H⋯O hydrogen bonds, forming a hydrogen-bonded trimer. IntraÂmolecular O—H⋯N hydrogen bonds influence the molÂecular conformation of the main molÂecule, and the two benzene rings form a dihedral angle of 10.55 (18)°. In the crystal, interÂmolecular O—H⋯O hydrogen bonds link hydrogen-bonded trimers into ribbons extending along the b axis
Simple approach to estimating the van der Waals interaction between carbon nanotubes
The van der Waals (vdW) interactions between carbon nanotubes (CNTs) were studied based on the continuum Lennard-Jones model. It was found that all the vdW potentials between two arbitrary CNTs fall on the same curve when plotted in terms of certain reduced parameters, the well depth, and the equilibrium vdW gap. Based on this observation, an approximate approach is developed to obtain the vdW potential between two CNTs without time-consuming computations. The vdW potential estimated by this approach is close to that obtained from complex integrations. Therefore, the developed approach can greatly simplify the calculation of vdW interactions between CNTs
Design and implementation of wire tension measurement system for MWPCs used in the STAR iTPC upgrade
The STAR experiment at RHIC is planning to upgrade the Time Projection
Chamber which lies at the heart of the detector. We have designed an instrument
to measure the tension of the wires in the multi-wire proportional chambers
(MWPCs) which will be used in the TPC upgrade. The wire tension measurement
system causes the wires to vibrate and then it measures the fundamental
frequency of the oscillation via a laser based optical platform. The platform
can scan the entire wire plane, automatically, in a single run and obtain the
wire tension on each wire with high precision. In this paper, the details about
the measurement method and the system setup will be described. In addition, the
test results for a prototype MWPC to be used in the STAR-iTPC upgrade will be
presented.Comment: 6 pages, 10 figues, to appear in NIM
Vibration and post-buckling of a functionally graded beam subjected to non-conservative forces
Vibration and post-buckling of beams made from functionally graded materials (FGM) subjected to uniformly and tangentially compressing follower forces are studied in this paper. Based on the accurately and geometrically nonlinear theory for extensible beams, the dynamic governing equations for FGM beams under non-conservative load are formulated. By using a shooting method to solve the non-linearly differential equations numerically, the responses of post-buckling and free vibration in the vicinity of post-buckling configuration are obtained, in which the hinged-fixed boundary conditions of beam are considered. Effects of material gradient parameter on the critical buckling, post-buckling and lower frequencies of the FGM beam are discussed in details
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