Adaptive beamforming of massive MIMO based on DoA in high mobility scenarios

A direction of arrival based (DoA-based) beamforming of massive MIMO was proposed for high-speed railway scenarios.In order to guarantee that the optimal system capacity can be obtained during traveling,an iterative multi-beams scheme was proposed.It aimed to design different beams for different mobile carriage terminals (MCT) respectively.The proposal adaptively selected the number of antennas for each beam,and adaptively designed the number of beams according to system capacity.Moreover,the scheme didn’t need channel state information (CSI) that can reduce system implementation complexity and cost.Numerical results indicate that the proposed scheme is suitable for high-speed scenarios,the system performance can be improved more efficiently compared to conventional methods.     

高速电梯补偿绳张紧装置设计中的两个问题

针对高速电梯补偿绳张紧装置，提出了补偿绳张紧重量的计算和选取方法。详细分析了电梯紧急制动状态下补偿绳张紧装置及防跳装置的工作状态，并建立了相应的动力学方程，通过相关数学推导和分析得出了防跳装置动作反力的计算方法。     

中国轨道铁路建设及其对铝材需求(2)

主要介绍中国可制造铝合金轨道车辆企业生产的动车组列车的性能特点,以及中国轨道车辆、城市轨道建设等对铝材的需求.在铝合金机车车辆制造中,单车的平均用铝量约10.3 t.其中挤压铝材约占78％,其他铝材占22％左右.     

Analysing observer preferences when presenting a product in a rendered scene: 2D vs. autostereoscopic 3D displays

ABSTRACT

This research compares the way the image of a product included within a rendered scene shown on an autostereoscopic 3D display is rated versus the same image shown in a 2D display. The purpose is to understand the observer's preferences and to determine the features that a composition should have to highlight the product and to make its presentation more attractive to observers, thereby helping designers and advertisers who use both displays to prepare images to make them more effective when visually presenting a product.

The results show that observers like the images on autostereoscopic 3D displays slightly more than those presented by means of 2D displays. On both displays the product is perceived more quickly when it is larger than the other elements and is shown with greater chromatic contrast, but a composition is seen as more attractive when the chromatic relationship between all the elements is more harmonious.     

Passenger comfort on high-speed trains: effect of tunnel noise on the subjective assessment of pressure variations

When passing through a tunnel, aerodynamic effects on high-speed trains may impair passenger comfort. These variations in atmospheric pressure are accompanied by transient increases in sound pressure level. To date, it is unclear whether the latter influences the perceived discomfort associated with the variations in atmospheric pressure. In a pressure chamber of the DLR-Institute of Aerospace Medicine, 71 participants (M = 28.3 years ± 8.1 SD) rated randomised pressure changes during two conditions according to a crossover design. The pressure changes were presented together with tunnel noise such that the sound pressure level was transiently elevated by either +6 dB (low noise condition) or +12 dB (high noise condition) above background noise level (65 dB(A)). Data were combined with those of a recent study, in which identical pressure changes were presented without tunnel noise (Schwanitz et al., 2013, ‘Pressure Variations on a Train – Where is the Threshold to Railway Passenger Discomfort?’ Applied Ergonomics 44 (2): 200-209). Exposure-response relationships for the combined data set comprising all three noise conditions show that pressure discomfort increases with the magnitude and speed of the pressure changes but decreases with increasing tunnel noise.

Practitioner Summary: In a pressure chamber, we systematically examined how pressure discomfort, as it may be experienced by railway passengers, is affected by the presence of tunnel noise during pressure changes. It is shown that across three conditions (no noise, low noise (+6 dB), high noise (+12 dB)) pressure discomfort decreases with increasing tunnel noise.     

一种新的低渗透气藏产能方程

综合分析滑脱效应、启动压力梯度效应和高速非达西效应,依据渗流力学原理建立稳定渗流条件下综合考虑三种效应影响的低渗透气藏产能方程.应用该方程对不同滑脱系数和不同启动压力梯度下的流入动态曲线进行比较.在相同井底流压下,随着滑脱效应影响因子的增大,气井产能逐渐增大；随着启动压力梯度的增大,气井产能逐渐减小.     

A study on sensitivity correction factor of gamma camera in whole body bone image

The aim of this study was to calculate a reasonable correction factor that could be corrected when the sensitivity of each gamma camera is measured and a whole body bone scan is performed as a follow-up examination. Seven pieces of equipment were used to analyse the sensitivity measurements of each gamma camera based on the source sensitivity measurement method recommended by the IAEA. These were BRIGHTVIEW, PRECEDENCE, ECAM, ECAM signature, ECAM Plus, SYMBIA T2 and INFINIA. The ^99mTc line source for the sensitivity measurement was generated in 4–7 kcps, which are the common values in a whole body bone scan. All the cameras were equipped with a low-energy and high-resolution parallel multi-hole collimator and set at a window width and photo peak of 15% and 140 keV, respectively. After placing the ^99mTc source as closely as possible to the collimator, the count was measured for 60 and 120 seconds to calculate correction factor. To determine if the correction factor calculated using the ^99mTc line source could be applied to a whole body bone scan of a real patient, a whole body bone scan was performed on 27 patients before applying the correction factor for comparative analysis. According to the experimental results using the ^99mTc line source, the gamma camera sensitivity was the highest for ECAM plus, followed in order by the gamma cameras, ECAM signature, SYMBIA T2, ECAM, BRIGHTVIEW, INFINIA and PRECEDENCE. When the results were used to calculate the correction factor based on the ECAM gamma camera, which had a medium-degree of sensitivity, the respective correction factors were 1·07, 1·05, 1·03, 1·00, 0·90, 0·83 and 0·72. The correction factors calculated based on the experiment using a ^99mTc line source were similar to those calculated based on the whole body bone scan. Clinical application of correction factor for measured sensitivity enables estimation of factor correction depending on difference in equipment when image is read, which improves accuracy and reliability of examination, and is expected to be used especially for continuous follow-up examination.     

New trends on moving object detection in video images captured by a moving camera: A survey

This paper presents a survey on the latest methods of moving object detection in video sequences captured by a moving camera. Although many researches and excellent works have reviewed the methods of object detection and background subtraction for a fixed camera, there is no survey which presents a complete review of the existing different methods in the case of moving camera. Most methods in this field can be classified into four categories; modeling based background subtraction, trajectory classification, low rank and sparse matrix decomposition, and object tracking. We discuss in details each category and present the main methods which proposed improvements in the general concept of the techniques. We also present challenges and main concerns in this field as well as performance metrics and some benchmark databases available to evaluate the performance of different moving object detection algorithms.     

基于摄像机的交互技术在展演建筑中的应用

本文主要讲述何为基于摄像机的交互技术以及如何在展演建筑中使用该交互技术，使展项更富有感染力和趣味性，使参观者更容易融入其中。     

Irradiance‐independent camera color calibration

For a digital color camera to represent the colors in the environment accurately, it is necessary to calibrate the camera RGB outputs in terms of a colorimetric space such as the CIEXYZ or sRGB. Assuming that the camera response is a linear function of scene luminance, the main step in the calibration is to determine a transformation matrix M mapping data from linear camera RGB to XYZ. Determining M is usually done by photographing a calibrated target, often a color checker, and then performing a least‐squares regression on the difference between the camera's RGB digital counts from each color checker patch and their corresponding true XYZ values. To measure accurately the XYZ coordinates for each patch, either a completely uniform lighting field is required, which can be hard to accomplish, or a measurement of the illuminant irradiance at each patch is needed. In this article, two computational methods are presented for camera color calibration that require only that the relative spectral power distribution of the illumination be constant across the color checker, while its irradiance may vary, and yet resolve for a color correction matrix that remains unaffected by any irradiance variation that may be present. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 540–548, 2014