增强图像平滑度的可逆信息隐藏方案

随着互联网技术的发展和社交网络的普及,可逆信息隐藏技术因其具有无损恢复载体信息的特性而被广泛应用于医疗、军事等领域的隐蔽信息传输。传统的可逆信息隐藏方案大多聚焦于嵌入容量提升和载密图像失真率降低,并未过多关注人们对图像视觉细节的要求,难以抵抗隐藏信息检测方法。针对上述挑战,从增强图像视觉平滑度方面入手,提出了一种增强图像平滑度的可逆信息隐藏方案,在嵌入隐蔽信息的同时提升载密图像最终的视觉质量。具体来说,所提方案将目标图像分为参考区域与非参考区域,利用非参考区域的图像像素预测值与原始像素值的差值作为信息嵌入的判断依据,通过差值平移来嵌入信息;进而构造图像平滑机制,采用高斯滤波作为秘密信息嵌入时像素值修改的模板,对预测值进行滤波计算,将滤波差值无损地加入载体图像中,以达到图像平滑的效果;同时将参考区域的像素值作为边信息,用于实现信息提取方对原始载体图像和秘密信息的无损恢复和提取;并以高斯函数中的滤波系数作为预置秘密信息对嵌入信息进行加密处理以保证嵌入信息的机密性。大量经典图像数据集的测试与分析结果表明,所提方案处理过的载密图像视觉平滑度得到了显著增强,具有较低的失真率、较高的嵌入率和较高的嵌入提取效率。在典型环境下,其生成的载密图像与高斯滤波后的图像相似度可达0.996 3,且可获得37.346的峰值信噪比和0.328 9的嵌入容量。     

The influence of technology innovation on SME performance through environmental sustainability practices in Kenya

This paper evaluates the association between technology innovation, environmental sustainability and its impact on small business performance. Samples of 204 small businesses and hierarchical regression models were used in the analysis. The results of the survey show that technological innovation affects environmentally friendly owners who have a positive impact on the performance of the company. Successful companies that support environmental community projects and social well-being beyond their economic responsibilities can bring greater financial success. Innovation from management and employee participation in environmental protection practices can improve the company's performance and enhance its image to stakeholders. The findings of this paper enhance existing theories and contribute to the establishment of sustainable practices in developed and developing countries.     

社会媒体短文本内容的语义概念关联和扩展

随着微博、照片分享等社会化媒体的快速发展,每天产生了大量的短文本内容如评论、微博等,对其进行深入挖掘有重大的应用价值和学术意义。该文选取微博作为例子,详细阐述我们提出的方法。微博信息流因其简短和实时的特性而具有非常大的价值,已经成为市场营销,股票预测、舆情监控等应用的重要信息源。尽管如此,微博内容特征极其稀疏、上下文语境提取困难,使得微博信息的挖掘面临着很大挑战。因此,我们提出一种基于Wikipedia的微博语义概念扩展方法,通过自动识别那些与微博信息语义相关的Wikipedia概念来丰富它的内容特征,从而有效提高微博信息数据挖掘和分析的效果。该文工作首先通过可链接性剪枝、概念关联和消歧,发现微博信息中重要的n-gram所对应的Wikipedia概念;其次,采用基于概念-文档关联矩阵的NMF分解(非负矩阵分解)方法获取Wikipedia概念之间的语义近邻,为微博信息扩展相关的语义概念。基于TREC 2011的微博数据集和Wikipedia 2011数据集进行实验,与已有两个相关研究工作比较,该文提出的方法取得了较好的效果。     

Face detection and recognition in an unconstrained environment for mobile visual assistive system

We present a visual assistive system that features mobile face detection and recognition in an unconstrained environment from a mobile source using convolutional neural networks. The goal of the system is to effectively detect individuals that approach facing towards the person equipped with the system. We find that face detection and recognition becomes a very difficult task due to the movement of the user which causes camera shakes resulting in motion blur and noise in the input for the visual assistive system. Due to the shortage of related datasets, we create a dataset of videos captured from a mobile source that features motion blur and noise from camera shakes. This makes the application a very challenging aspect of face detection and recognition in unconstrained environments. The performance of the convolutional neural network is further compared with a cascade classifier. The results show promising performance in daylight and artificial lighting conditions while the challenges lie for moonlight conditions with the need for reduction of false positives in order to develop a robust system. We also provide a framework for implementation of the system with smartphones and wearable devices for video input and auditory notification from the system to guide the visually impaired.     

交错阵列甚低频信号产生方法研究

10 kHz量级甚低频电磁波信号具有较强的地物穿透能力,可用于地质勘探。由于其天线尺寸在10 km量级,其应用场合受到限制,研究基于适当尺寸高频雷达天线的甚低频电磁波信号产生方法具有重要意义。该文提出基于高频阵列天线产生甚低频信号的概念,利用阵列天线合成产生近光速远离运动雷达多普勒信号,实现信号频率的大幅降低。给出了发射波形、交错阵列设计和阵列参数选择方法。将周期脉冲串信号作为辐射单元信号,增大合成信号脉宽。利用阵列产生的脉宽展宽量填补脉冲信号的休止期,在目标区合成时间连续的甚低频信号。采用峰值旁瓣比(PSLR)、积分旁瓣比(ISLR)、阵列发射信号与合成信号的频谱对比评价合成低频信号的性能和发射信号的能量利用率。该文仿真了百米量级阵列100 MHz辐射单元信号在目标区合成10 kHz甚低频信号的情况:9行阵列构成交错阵列、辐射单元信号脉宽设置为0.115 μs时,合成信号频谱的峰值旁瓣比和积分旁瓣比分别为–13.34 dB和–9.44 dB, 10 kHz低频信号在合成信号中的能量占比为89.79%。该文分析了辐射单元间距误差、辐射单元信号时间、相位与幅度误差以及目标偏离预定位置的影响。仿真结果表明了该文方法的有效性。      

移动平台典型应用的身份认证问题研究

近年来的研究表明,针对USIM卡的攻击手段日益增多,在5G环境下攻击者也能使用复制的USIM卡绕过某些正常应用的身份认证,进而获取用户信息。在USIM可被复制的条件下,研究了移动平台上典型应用的身份认证流程,通过分析用户登录、重置密码、执行敏感操作的应用行为给出身份认证树。在此基础上,测试了社交通信、个人健康等7类58款典型应用,发现有29款认证时仅需USIM卡接收的SMS验证码便可通过认证。针对该问题,建议应用开启两步验证,并结合USIM防伪等手段完成认证。     

DSIM: dynamic and static interest mining for sequential recommendation

Knowledge and Information Systems - Sequential recommendation aims to predict the next interaction by mining users’ evolving interest from their historical behaviors. Through comprehensive...     

Research and application of 3D visualization and Internet of Things technology in urban land use efficiency management

Land is the basis for human beings to engage in economic and social activities, but the continuous acceleration of the process of economic development and urban expansion has brought about a series of ecological and urban problems. Therefore, the simulation of urban spatial expansion is very important for the rational planning of urban land and the promotion of sustainable urban development. The three-dimensional visualization of urban land allows users to have a perceptual understanding of urban construction, and enables decision makers, designers and users to have a more vivid and rational understanding of the current state of urban construction and planning and design blueprints. Based on this, this article combines three-dimensional imaging and Internet of Things technology to carry out the research on urban land utilization. First of all, this article discusses image modeling techniques such as texture mapping and panoramas, and applies these techniques to the model reconstruction of complex urban land. The model effectively combines graphics-based and image-based model reconstruction technology to construct a highly realistic three-dimensional urban landscape. Secondly, this article combines the Internet of Things and wavelet analysis to design an Internet of Things architecture for urban land use efficiency management. Finally, on the premise of taking into account the important results and the status quo of urban development, the countermeasures and suggestions for increasing the urban land use rate are put forward.     

How do app icon color and border shape influence visual search efficiency and user experience? Evidence from an eye-tracking study

Icon color and icon border shape are two key factors that affect search efficiency and user experience but have previously been studied separately. This study aimed to ascertain their separate and combined effects on smartphone interfaces. We conducted an experiment using eye tracking in addition to performance and experience measures to understand the effects of app icon color and border shape on visual efficiency and user experience. The results identified both features as essential attributes with interactive effects in the process of searching app icons on a smartphone interface. The study confirmed that varied colors across icons and a rounded square border shape helped to improve search efficiency, decrease cognitive effort, and lead to a more positive user experience.Relevance to industryUsers of smartphones are often confronted with the problem of selecting a single app from a great number of apps. Visual design of app icons plays a key role in influencing visual search efficiency and user experience. The results of this study have implications for designing app icons on the interface of smartphones to improve search efficiency and elicit positive user experience.     

基于ATmega16L的电液伺服控制系统设计

针对电液伺服闭环控制过程中,设定信号不断发生变化,电液阀门位置定位精确度较低的难题.采用AT-mega16L作为核心控制器,并配有高精度A/D、D/A转换器,通过对阀门开度控制信号和位置反馈信号进行采集、转换、计算和比较,发出控制信号决定并执行换向阀的换向、交流伺服电动机的起停运转,推动液压缸推杆的伸缩,进而对阀门转角大小、开度百分比进行精确定位.