Research on Aircraft Cable Defects Locating Method Based on Time-Frequency Domain Reflection

AbstractThis paper presents an aircraft cable fault detection and location method based on TFDR in order to detect the intermittent faults effectively and to cope with the serial and after-connector faults being difficult to be detected in time domain reflection. In this method, the correlation function of reflected and reference signal is utilized to detect and locate the aircraft fault according to the characteristics of reflected and reference signal in time-frequency domain, so the hit rate of detecting and locating intermittent faults can be improved effectively. In the work process, the reflected signal is interfered by the noise and false alarm takes place frequently, so the threshold de-noising method based on wavelet decomposition is utilized to decrease the noise interference and reduce the fault alarm rate. Then the time-frequency cross correlation function of the reference signal and the reflected signal based on Wigner-Ville distribution is computed in order to locate the fault position. At last, LabVIEW is applied to implement operation and control interface, the main function of which is to link and control MATLAB and LABSQL. Utilizing the strong calculating capability and the abundant function library of MATLAB, the signal processing turn to be easily realized, moreover LabVIEW help the system to be more reliable and updated easily

Optical characterization of Bi2_2Se3_3 in a magnetic field: infrared evidence for magnetoelectric coupling in a topological insulator material

We present an infrared magneto-optical study of the highly thermoelectric narrow-gap semiconductor Bi$_2$Se$_3$. Far-infrared and mid-infrared (IR) reflectance and transmission measurements have been performed in magnetic fields oriented both parallel and perpendicular to the trigonal $c$ axis of this layered material, and supplemented with UV-visible ellipsometry to obtain the optical conductivity $\sigma_1(\omega)$. With lowering of temperature we observe narrowing of the Drude conductivity due to reduced quasiparticle scattering, as well as the increase in the absorption edge due to direct electronic transitions. Magnetic fields $H \parallel c$ dramatically renormalize and asymmetrically broaden the strongest far-IR optical phonon, indicating interaction of the phonon with the continuum free-carrier spectrum and significant magnetoelectric coupling. For the perpendicular field orientation, electronic absorption is enhanced, and the plasma edge is slightly shifted to higher energies. In both cases the direct transition energy is softened in magnetic field.Comment: Final versio

A Survey of Taxi Drivers’ Aberrant Driving Behavior in Beijing

This is the author's accepted manuscript. The original publication is available from http://www.tandfonline.com/doi/abs/10.1080/19439962.2013.799624#.VD_cxxYXNWs.Taxis are an important component in Beijing's urban integrated transport system. They provide passengers with convenient, comfortable, and efficient service. However, aberrant driving behaviors occur frequently among Beijing taxi drivers, leading to frequent violations and passenger complaints. This study explores Beijing taxi drivers’ aberrant driving behaviors and the factors influencing them. Questionnaires were designed to obtain different views of taxi drivers’ aberrant driving behaviors from taxi drivers, traffic police, and passengers, and to sample problems in the Beijing taxi industry. Responses from 52 professional taxi drivers, 40 traffic police officers, and more than 500 taxi passengers were obtained. The results show that taxi drivers generally under-report their own aberrant driving behaviors, whereas passengers and police appear to have a very negative impression of taxi drivers’ driving behaviors. Environmental influences such as economic pressure, ownership of taxi management, and the nature of the complaint system were found to contribute to taxi drivers’ aberrant driving behaviors. Some suggestions to increase the efficiency and safety of the taxi system in Beijing were proposed, such as improving drivers’ working and economic conditions, developing a better passenger loading system, establishing more effective license and termination policies for drivers, and improving the complaint system

THE INFLUENCE OF BACKPACK CARRIAGE ON TRUNK POSTURE IN CHILDREN DURING UNPLANNED GAIT TERMINATION

This study aimed to examine the trunk posture in children with different backpack loads during unplanned gait termination. Twelve school boys aged 9–10 years completed unplanned and planned gait termination with a backpack load of 0%, 10%, and 15% of their body weight (BW) while level walking. Trunk inclination angle and trunk range of motion at sagittal plane and spinal angle at frontal plane were examined. In comparison with 0% BW load condition, the spinal angle increased significantly at 10% and 15% BW load condition during gait termination (

Optical loss compensation in a bulk left-handed metamaterial by the gain in quantum dots

A bulk left-handed metamaterial with fishnet structure is investigated to show the optical loss compensation via surface plasmon amplification, with the assistance of a Gaussian gain in PbS quantum dots. The optical resonance enhancement around 200 THz is confirmed by the retrieval method. By exploring the dependence of propagation loss on the gain coefficient and metamaterial thickness, we verify numerically that the left-handed response can endure a large propagation thickness with ultralow and stable loss under a certain gain coefficient.Comment: 6 pages with 4 figure

Mirror symmetry decomposition in double-twisted multilayer graphene systems

Due to the observed superconductivity, the alternating twisted trilayer graphene (ATTLG) has drawn great research interest very recently, in which three monolayer graphene (MLG) are stacked in alternating twist way. If one or several of the MLG in ATTLG are replaced by a multilayer graphene, we get a double twisted multilayer graphene (DTMLG). In this work, we theoretically illustrate that, if the DTMLG has a mirror symmetry along z direction like the ATTLG, there exists a mirror symmetry decomposition (MSD), by which the DTMLG can be exactly decoupled into two subsystems with opposite parity. The two subsystems are either a twisted multilayer graphene (single twist) or a multilayer graphene, depending on the stacking configuration. Such MSD can give a clear interpretation about all the novel features of the moir\'{e} band structures of DTMLG, e.g. the fourfold degenerate flat bands and the enlarged magic angle. Meanwhile, in such DTMLG, the parity becomes a new degree of freedom of the electrons, so that we can define a parity resolved Chern number for the moir\'{e} flat bands. More importantly, the MSD implies that all the novel correlated phases in the twisted multilayer graphene should also exist in the corresponding DTMLGs, since they have the exact same Hamiltonian in form. Specifically, according to the MSD, we predict that the superconductivity should exist in the (1+3+1)-DTMLG.Comment: 12 pages, 6 figure