基于HMM方法的动态手势轨迹训练性能研究

基于HMM(Hidden Markov Model,隐形马尔可夫模型)对动态手势轨迹的训练是手势识别的关键技术之一。本文对HMM的模型训练采用Baum.Welch算法,并分别从迭代次数,样本个数选取,以及模型初值选取等方面对动态手势轨迹的训练性能进行了研究。实验结果表明HMM方法对具有时空特性的动态手势轨迹识别是非常有效的。     

基于多重示范的智能车辆运动基元表征与序列生成

为解决不同驾驶风格的类人驾驶轨迹生成问题,以包含同类型多重示范的真实行车轨迹数据集为依托,提出一种基于驾驶风格参量提取的运动基元表征及基元序列生成方法.单一运动基元以改进的动态运动基元方法进行表征,并引入奇异值分解实现同类型轨迹集合中主要形状表征参量与驾驶风格参量的分离;基元序列则是在关联各独立表征参量的基础上,利用准...     

A spatiotemporal super-resolution algorithm for a hybrid stereo video system

This paper presents a spatiotemporal super-resolution method to enhance both the spatial resolution and the frame rate in a hybrid stereo video system. In this system, a scene is captured by two cameras to form two videos, including a low spatial resolution with high-frame-rate video and a high spatial resolution with low-frame-rate video. For the low-spatial-resolution video, the low-resolution frames are spatially super-resolved by the high-resolution video via the stereo matching, the bilateral overlapped block motion estimation, and the adaptive overlapped block motion compensation algorithms, while for the low-frame-rate video, those missed frames are interpolated using the high-resolution frames obtained by fusing the disparity compensation and the motion compensation frame rate up-conversion. Experimental results demonstrate that the proposed mixed spatiotemporal super-resolution method has a more significant contribution to both the subjective and objective qualities than the pure spatial super-resolution or the frame rate up-conversion.     

旋转尾翼弹箭极限圆锥运动稳定判据

为获得旋转尾翼弹箭极限圆锥运动稳定判据,针对现有理论方法的不足,提出了改进理论模型。该模型通过对弹箭在准圆运动状态下的振幅平面方程进行泰勒展开,从而充分考虑幅值变化对振幅平面方程中根号项取值的影响;在此基础上,根据不同参数取值情况,对其非零奇点的存在性和稳定性进行分析,导出了弹箭在非线性静力矩和非线性马格努斯力矩作用下形成稳定极限圆锥运动的解析判据,并给出两条仅与攻角方程初始参数相关的综合判据条件J₁>0和J₂>0;以某型旋转尾翼弹箭气动及结构特征参数为例,对所得理论判据进行了验证。研究结果表明,给出的稳定极限圆锥运动形成判据,与现有理论结果相比,更为全面且明确,利用所得判据条件,可方便准确地对弹箭极限圆锥运动特性进行分析判断。     

工业带材速度检测系统设计

为了解决工业带材生产过程中带材速度实时精确检测这一问题,设计了一种基于纹理图像功率谱的非接触式工业带材速度检测系统。首先利用线阵CCD采集带材图像的纹理图;然后对纹理图像进行滤波、二值化、腐蚀等预处理;最后对图像进行功率谱分析,利用霍夫变换求得带材图像功率谱分布方向,从而间接得到带材的速度。实验结果表明该方法检测工业带材速度的误差可以缩减到±0.03 m/s之内,能够有效、实时地测得工业带材的运动速度。     

数字化转型背景下运营商的未来发展趋势

随着数字化技术的快速发展,运营商已进入数字化时代,数字化转型已成为未来发展的必由之路。数字化转型对运营商的影响主要体现在客户需求变化、业务变革、竞争环境变化等方面。运营商未来需要聚焦业务创新、数字化技术应用、营销创新等,以满足不断变化的市场需求。     

Graphene films with large domain size by a two-step chemical vapor deposition process

The fundamental properties of graphene are making it an attractive material for a wide variety of applications. Various techniques have been developed to produce graphene and recently we discovered the synthesis of large area graphene by chemical vapor deposition (CVD) of methane on Cu foils. We also showed that graphene growth on Cu is a surface-mediated process and the films were polycrystalline with domains having an area of tens of square micrometers. In this paper, we report on the effect of growth parameters such as temperature, and methane flow rate and partial pressure on the growth rate, domain size, and surface coverage of graphene as determined by Raman spectroscopy, and transmission and scanning electron microscopy. On the basis of the results, we developed a two-step CVD process to synthesize graphene films with domains having an area of hundreds of square micrometers. Scanning electron microscopy and Raman spectroscopy clearly show an increase in domain size by changing the growth parameters. Transmission electron microscopy further shows that the domains are crystallographically rotated with respect to each other with a range of angles from about 13 to nearly 30°. Electrical transport measurements performed on back-gated FETs show that overall films with larger domains tend to have higher carrier mobility up to about 16,000 cm(2) V(-1) s(-1) at room temperature.     

SK静态混合器对工业磷酸脱砷的过程强化研究

以五硫化二磷脱砷剂分别开展了搅拌混合及SK静态混合脱除工业磷酸中砷（As）的研究。利用单因素实验、正交实验和响应曲面实验设计,得到了最佳反应条件。结果表明：两种反应器最佳的脱砷剂用量均为理论用量的4倍,脱砷率大于99.8%,净化后的产品砷浓度小于0.5 mg·kg⁻¹,满足国家标准GB 1886.15-2015规定的食品级磷酸指标。搅拌反应器脱砷过程最佳反应温度65 ℃,反应时间70 min,搅拌速度300 r·min⁻¹;以SK静态混合器进行磷酸脱砷,最佳磷酸流速为0.66 m·s⁻¹,反应时间2.4 s,单位时间内处理的磷酸量是搅拌反应器的372倍。用SK静态混合器进行磷酸脱砷,具有工艺流程短、结构简单紧凑、可连续操作等优点,可以实现工业磷酸脱砷的过程强化。     

Life cycle assessment of HFC-134a production by calcium carbide acetylene route in China

HFC-134a is a widely used environment-friendly refrigerant. At present, China is the largest producer of HFC-134a in the world. The production of HFC-134a in China mainly adopts the calcium carbide acetylene route. However, the production route has high resource and energy consumption and large waste emission, and few of the studies addressed on the environmental performance of its production process. This study quantified the environmental performance of HFC-134a production by calcium carbide route via carrying out a life cycle assessment (LCA) using the CML 2001 method. And uncertainty analysis by Monte-Carlo simulation was also carried out. The results showed that electricity had the most impact on the environment, followed by steam, hydrogen fluoride and chlorine, and the impact of direct CO₂ emissions in calcium carbide production stage on the global warming effect also could not be ignored. Therefore, the clean energy (e.g., wind, solar, biomass, and natural gas) was used to replace coal-based electricity and coal-fired steam in this study, showing considerable environmental benefits. At the same time, the use of advanced production technologies could also improve environmental benefits, and the environmental impact of the global warming category could be reduced by 4.1% via using CO₂ capture and purification technology. The Chinese database of HFC-134a production established in this study provides convenience for the relevant study of scholars. For the production of HFC-134a, this study helps to better identify the specific environmental hotspots and proposes useful ways to improve the environmental benefits.     

醇基燃料应用发展分析

在能源日趋紧张的形势下,醇基燃料以其特有的可再生性有望成为替代石油的新型能源,但在实际应用过程中问题频发。通过剖析存在的实际问题,提出了发展建议。