UAV flight control method based on deep reinforcement learning

Aiming at the intelligent perception and obstacle avoidance of UAV for the environment, an obstacle-avoidance flight decision method of UAV based on image information is proposed in this paper. Add Gate Recurrent Unit (GRU) to the neural network, and use the deep reinforcement learning algorithm DDPG to train the model. The special gates structure of GRU is utilized to memorize historical information, and acquire the variation law of the environment of UAV from the time sequential data including image information and UAV position and speed information to realize the dynamic perception of obstacles. Moreover, the basic framework and training method of the model are introduced, and the generalization ability of the model is tested. The experimental results show that the proposed method has better generalization ability and better adaptability to the environment

Effect of aging on the reinforcement efficiency of carbon nanotubes in epoxy matrix

The reinforcement efficiency of carbon nanotubes (CNTs) in epoxy matrix was investigated in the elastic regime. Cyclic uniaxial tensile tests were performed at constant strain amplitude and increasing maximum strain. Post-curing of the epoxy and its composite at a temperature close to the glass transition temperature allowed us to explore the effect of aging on the reinforcement efficiency of CNT. It is found that the reinforcement efficiency is compatible with a mean field mixture rule of stress reinforcement by random inclusions. It also diminishes when the maximum strain increased and this effect is amplified by aging. The decrease of elastic modulus with increasing cyclic maximum strain is quite similar to the one observed for filled elastomers with increasing strain amplitude, a phenomenon often referred as the Payne effect

Precoded turbo code within 0.1dB of Shannon limit

The application of the precoding technique to turbo codes is investigated, resulting in a new class of turbo-like codes named precoded turbo codes. The introduction of a precoder provides a degree of freedom for code optimisation. As a result, an optimised rate-1/2 precoded turbo code with a threshold of 0.28 dB is designed using the EXIT chart

Quantum memory for non-stationary light fields based on controlled reversible inhomogeneous broadening

We propose a new method for efficient storage and recall of non-stationary light fields, e.g. single photon time-bin qubits, in optically dense atomic ensembles. Our approach to quantum memory is based on controlled, reversible, inhomogeneous broadening. We briefly discuss experimental realizations of our proposal.Comment: 4 page

Simulation of Multiknobs Correction at ATF2

THPD096International audienceThe ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. During initial commissioning, we started with larger than nominal ?-functions at the IP, to reduce the effects from higher-order optical aberrations and thereby simplify the optical corrections needed. We report on simulation studies at two different IP locations developed based on waist scan, dispersion, coupling and ? function multiknobs correction in the large ? optics of ATF2, in the presence of two kinds of magnet inaccuracies (quadrupole gradient and roll errors) to generate all possible linear optics distortions at the IP. A vertical beam size which is very close to the nominal beam size is obtained based on the simulation study

Interference through quantum dots

We discuss the effect of quantum interference on transport through a quantum dot system. We introduce an indirect coherent coupling parameter alpha, which provides constructive/destructive interference in the transport current depending on its phase and the magnetic flux. We estimate the current through the quantum dot system using the non-equilibrium Green's function method as well as the master equation method in the sequential tunneling regime. The visibility of the Aharonov-Bohm oscillation is evaluated. For a large inter-dot Coulomb interaction, the current is strongly suppressed by the quantum interference effect, while the current is restored by applying an oscillating resonance field with the frequency of twice the inter-dot tunneling energy.Comment: 10 pages, 3 figure

Persistent Hypertension is Associated with Low Hdl in Young Adults: an Evidence from Taiwan Five Years Population Based Cohort Study

Background: Hypertension (HT) is one of major risk factor for cardiovascular disease (CVD) and its combination with other risk factors, i.e. dyslipidemia, could worsen the health. The burden of CVD is now shifting to younger age, and its development is even in the earlier life period. Young adults with rare health check and lack of awareness in CVD risk factor may result in suboptimal management. This study aimed to investigate the association of persistent HT and low HDL level in 5 years follow up among young adults aged 15-25 years. Subjects and Methods: This study was done using Tw3SHH, a Taiwan population based cohort study (2002 to 2007), among young adults 15-25 years of age. HT was defined as the SBP>120mmHg and/or DBP>80 mmHg and/or respondent was told of having HT by medical personnel. HT development was classified based on their HT status in 2002 and 2007: “Non-HT (no HT both in 2002 and 2007)”, “Improved HT (HT in 2002 and no HT in 2007)”, ”Worsened HT (no HT in 2002 and HT in 2007)”, and “Persistent HT (HT both in 2002 and 2007)”. HDL was grouped based on NCEP-ATP III, and the low HDL defined as HDL<40mg/dl. Exercise, fatty food consumption and smoking status were based in self-reported questions. The data were analyzed by a multiple logistic reg¬res¬sion model to estimate the association of persistent HT and low HDL level in 5-years. Covariates were sex, age, smoking habit, exercise habit, fatty food con¬sump¬tion, and HbA1C. Results: About 9.35% of 727 study subjects had persistent HT. Compared to non-HT group, persistent HT group had higher risk of having low HDL level (crude OR= 3.70; CI 95%= 1.90 to 7.2; p<0.001; adjusted OR= 2.44; CI 95%= 1.18 to 5.03; p= 0.015). This association persisted (crude OR= 4.90; CI 95% 2.29 to 10.49; p<0.001; adjusted OR= 2.89; CI 95%= 1.34 to 6.24; p= 0.007) in sub¬group analysis among study subjects without low baseline HDL. Conclusion: Persistent HT is associated with low HDL level in 5 years follow up among young adults 15-25 years of age. Although universal screening in lipid profile among children and youth is still controversial, awareness to this condition should be raised. Keywords: cardiovascular, hypertension, dyslipidemia, HDL, young adul

Spin and lattice excitations of a BiFeO3 thin film and ceramics

We present a comprehensive study of polar and magnetic excitations in BiFeO3 ceramics and a thin film epitaxially grown on an orthorhombic (110) TbScO3 substrate. Infrared reflectivity spectroscopy was performed at temperatures from 5 to 900 K for the ceramics and below room temperature for the thin film. All 13 polar phonons allowed by the factor-group analysis were observed in theceramic samples. The thin-film spectra revealed 12 phonon modes only and an additional weak excitation, probably of spin origin. On heating towards the ferroelectric phase transition near 1100 K, some phonons soften, leading to an increase in the static permittivity. In the ceramics, terahertz transmission spectra show five low-energy magnetic excitations including two which were not previously known to be infrared active; at 5 K, their frequencies are 53 and 56 cm-1. Heating induces softening of all magnetic modes. At a temperature of 5 K, applying an external magnetic field of up to 7 T irreversibly alters the intensities of some of these modes. The frequencies of the observed spin excitations provide support for the recently developed complex model of magnetic interactions in BiFeO3 (R.S. Fishman, Phys. Rev. B 87, 224419 (2013)). The simultaneous infrared and Raman activity of the spin excitations is consistent with their assignment to electromagnons