基于标志点识别的自主车视觉导航

提出了一种基于室内标志点识别的单目视觉导航的方法。在地面上有规律地旋转一些标志点,采用辅助先验知识对标志点进行识别和分割,利用透视投影变换得到标志点与摄像机之间的相对距离,达到通过单目摄像机获得景物深度信息的目的。整个算法结构简单,易于实现,对由照明不均匀和地面反光所引起的各种干扰有较好地抑制作用。     

虚拟现实中基于图像的三维空间漫游方法

最近几年基于图像的虚拟现实技术渐渐引起人们的兴趣。它是一种通过实景拍摄获取图像来表示虚拟场景的技术。提出了一种基于图像的三维空间漫游方法 ,它是基于视图变形技术的原理 ,在三维空间中选定三幅视图构成一组图像基 ,再由这组基插值中间任何姿态视图 ,最后这些视图以视频方式显示出来。它避免了 3D重建问题 ,人们可以从任何视点或视向来观赏对象。     

一种基于单目视觉的移动机器人室内导航方法

针对室内导航的环境特点,提出了一种简单快速的、以踢脚线为参考目标的移动机器人室内导航方法。该方法从图像中提取踢脚线作为参考直线,通过两条直线在图像中的成像特征,提取角度和横向偏离距离作为移动机器人的状态控制输入,从而实现移动机器人的横向运动控制。该方法无需进行摄像机的外部参数标定,大大简化了计算过程,提高了视觉导航的实时性。     

System for neuromorphic estimation of rotation of a mobile technological platform

A model of an astroinertial system with a correction algorithm is suggested. This algorithm is an extended interpretation of a Kalman-type algorithm. The results of computational experiment are reported.     

Intra-prosthetic breast MR virtual navigation: A preliminary study for a new evaluation of silicone breast implants

ObjectivesTo assess the contribute of intra-prosthetic MRI virtual navigation for evaluating breast implants and detecting implant ruptures.MethodsForty-five breast implants were evaluated by MR examination. Only patients with a clinical indication were assessed. A 1.5-T device equipped with a 4-channel breast coil was used by performing axial TSE-T2, axial silicone-only, axial silicone suppression and sagittal STIR images. The obtained dicom files were also analyzed by using virtual navigation software. Two blinded radiologists evaluated all MR and virtual images. Eight patients for a total of 13 implants underwent surgical replacement. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated for both imaging strategies.ResultsIntra-capsular rupture was diagnosed in 13 out of 45 (29%) implants by using MRI. Basing on virtual navigation, 9 (20%) cases of intra-capsular rupture were diagnosed. Sensitivity, specificity, accuracy, PPV and NPV values of 100%, 86%, 89%, 62% and 100%, respectively, were found for MRI. Virtual navigation increased the previous values up to 100%, 97%, 98%, 89% and 100%.ConclusionIntra-prosthetic breast MR virtual navigation can represent an additional promising tool for the evaluation of breast implants being able to reduce false positives and to provide a more accurate detection of intra-capsular implant rupture signs.     

基于忆容器件的神经形态计算研究进展

人工智能的快速发展需要人工智能专用硬件的快速发展,受人脑存算一体、并行处理启发而构建的包含突触与神经元的神经形态计算架构,可以有效地降低人工智能中计算工作的能耗.记忆元件在神经形态计算的硬件实现中展现出巨大的应用价值;相比传统器件,用忆阻器构建突触、神经元能极大地降低计算能耗,然而在基于忆阻器构建的神经网络中,更新、读...     

Inertial satellite neuromorphic system for estimation of the rotation parameters of a mobile technological platform

A system is discussed including an on-board set of GLONASS receivers and gyroscopic sensors of angular velocities, which are integrated into a neural computer network implementing a Kalman-type multimodel dynamic pseudoinversion algorithm. The results of a computational experiment are presented.     

Deeply virtual Compton scattering on a virtual pion target

We study deeply virtual Compton scattering on a virtual pion that is emitted by a proton. Using a range of models for the generalized parton distributions of the pion, we evaluate the cross section, as well as the beam spin and beam charge asymmetries in the leading-twist approximation. Studying Compton scattering on the pion in suitable kinematics puts high demands on both beam energy and luminosity, and we find that the corresponding requirements will first be met after the energy upgrade at Jefferson Laboratory. As a by-product of our study, we construct a parameterization of pion generalized parton distributions that has a non-trivial interplay between the x and t dependence and is in good agreement with form factor data and lattice calculations.     

Neural network correction of a vector gravitoinertial navigation system

The concept and model of correction of a 3D inertial navigation system capable of estimating earth’s gravitational field anomalies are suggested. The results of the computational experiment are presented.     

Logic design for a self-contained diver navigation system

A major criterion in the design of a diver-held acoustic navigation system we are developing is that it must be very compact so that a diver can operate it easily and safely. With space at a premium, a logic circuit has been designed as a convenient way of measuring and storing the relative distances of the diver from up to four fixed transponders. A battery-powered microprocessor allows the diver's location to be computed. With one of the logic circuits the location can be found in two-dimensional space in the plane of three transponders; with two or three logic circuits the location can be found in three-dimensional space using four transponders. The circuit could be used in any other application which involves measuring the relative arrival times of acoustic pulses at a receiver.     

X射线脉冲星导航系统导航精度的研究

为提高X射线脉冲星导航系统的导航精度,提出了一种基于低通滤波器的恒比定时方法,以提高X射线脉冲星导航系统中X射线脉冲到达时间的测量精度.通过设计测量方案,对原有的峰值定时方法和改进后的恒比定时系统的定时精度和死时间进行测量.测量结果表明,峰值定时系统的定时精度和死时间分别为18和4750 ns,恒比定时系统的定时精度和死时间分别为0.78和105 ns,与原有的峰值定时系统相比,采用恒比定时系统的定时精度和死时间均得到明显的提高.在X射线脉冲星导航系统中,通过利用这两种不同定时系统来测量X射线光子的到达时间以构造累积脉冲轮廓.实验结果表明,与峰值定时系统相比,采用改进的恒比定时系统获得的累积脉冲轮廓的信噪比得到明显改善,因此,采用恒比定时系统的导航精度可得到提高.     

Development and use of a virtual NMR facility

We have developed a "virtual NMR facility" (VNMRF) to enhance access to the NMR spectrometers in Pacific Northwest National Laboratory's Environmental Molecular Sciences Laboratory (EMSL). We use the term virtual facility to describe a real NMR facility made accessible via the Internet. The VNMRF combines secure remote operation of the EMSL's NMR spectrometers over the Internet with real-time videoconferencing, remotely controlled laboratory cameras, real-time computer display sharing, a Web-based electronic laboratory notebook, and other capabilities. Remote VNMRF users can see and converse with EMSL researchers, directly and securely control the EMSL spectrometers, and collaboratively analyze results. A customized Electronic Laboratory Notebook allows interactive Web-based access to group notes, experimental parameters, proposed molecular structures, and other aspects of a research project. This paper describes our experience developing a VNMRF and details the specific capabilities available through the EMSL VNMRF. We show how the VNMRF has evolved during a test project and present an evaluation of its impact in the EMSL and its potential as a model for other scientific facilities. All Collaboratory software used in the VNMRF is freely available from www.emsl.pnl.gov:2080/docs/collab.     

On the current through a virtual cathode

Two existing opinions about the current passing through a virtual cathode in a closed equipotential cavity are considered: (i) the current is always smaller than half the limiting current (as follows from the steady-state consideration) and (ii) the current oscillates in time about the mean value that is exactly equal to the limiting current (as follows from the non-steady-state self-consistent simulation by the coarse particle method). The history of this issue is described. The invalidity of the former opinion is shown.     

Impact of Ta/Ti electrodes on linearities of TaO_x-based resistive random-access memories for neuromorphic computing

In this work, by incorporating different electrodes(Ta/Ti) onto TaOxdielectric layer, we studied both the conductance reading and conductance updating(long term potentiation and depression) linearities in the two RRAM devices. Owing to the composition modulation(CM) mechanism, the Ta-electrode device shows better conductance reading and updating linearities. The RRAM device linearities directly influence the performance of the neural network when the devices are used as synapses. System evaluation of a two-layer neural network considering the conductance reading and updating linearity factors further confirm that both the training and inference accuracies of Ta electrode device are better than those of the Ti electrode one. We believe that this work could serve as a powerful reference for engineering synaptic devices with good linearity for neuromorphic computing applications.     

Fidelity of three-dimensional-sound reproduction using a virtual auditory display

The fidelity of reproducing free-field sounds using a virtual auditory display was investigated in two experiments. In the first experiment, listeners directly compared stimuli from an actual loudspeaker in the free field with those from small headphones placed in front of the ears. Headphone stimuli were filtered using head-related transfer functions (HRTFs), recorded while listeners were wearing the headphones, in order to reproduce the pressure signatures of the free-field sounds at the eardrum. Discriminability was investigated for six sound-source positions using broadband noise as a stimulus. The results show that the acoustic percepts of real and virtual sounds were identical. In the second experiment, discrimination between virtual sounds generated with measured and interpolated HRTFs was investigated. Interpolation was performed using HRTFs measured for loudspeaker positions with different spatial resolutions. Broadband noise bursts with flat and scrambled spectra were used as stimuli. The results indicate that, for a spatial resolution of about 6 degrees, the interpolation does not introduce audible cues. For resolutions of 20 degrees or more, the interpolation introduces audible cues related to timbre and position. For intermediate resolutions (10 degrees - 15 degrees) the data suggest that only timbre cues were used.     

Efficiency and stability enhancement of a virtual cathode oscillator

A virtual cathode oscillator(VCO) with a resonant cavity is presented and investigated numerically and theoretically,and its efficiency and stability are enhanced. An equivalent circuit method is introduced to analyze the resonant cavity composed of anode foil and feedback annulus, and a theoretical expression for the fundamental mode frequency of the resonant cavity is given. The VCO is investigated in detail with a particle-in-cell method. We obtain the microwave frequencies from simulation, theoretical expression, and relative references, and draw three important conclusions. First, the microwave frequency is a constant when the diode voltage is changed from 588 kV to 717 kV. Second, the fluctuation of the microwave frequency is very small when the AK gap is changed from 1.2 cm to 1.6 cm. Third, the microwave frequency agrees with the theoretical result. The relative error, which is calculated according to the theoretical and simulation frequencies, is only1.7%.     

Oscillations of an electron stream with a virtual cathode

The results of an investigation of the oscillations of a virtual cathode and the hysteresis of the state for a one-dimensional electron stream in a flat drift space are given. It is shown that in the case of a given mean space charge density and a given injection current different oscillatory regimes can exist in a stream with a virtual cathode.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 74–77, October, 1987.In conclusion, the authors thank L. V. Shelomentsev for carrying out the numerical calculations for the nonrelativistic stream on the computer.