基于非凸log模型的脑电时-频-空特征选择方法

针对运动想象脑电时-频-空特征选择问题,提出了基于非凸log模型的稀疏特征选择方法(LOG方法)。首先,对原始脑电信号进行时-频分解,得到多个时-频段;其次,针对每个时-频段使用共空域模式(CSP)提取特征,得到时-频-空特征集合;最后,通过提出的基于log函数的非凸稀疏优化模型进行特征选择和分类,该模型可有效缓解L1范数正则化的有偏估计。为验证本方法的有效性,用3个公开的运动想象脑电数据集进行实验,相比现有的凸稀疏优化模型,非凸log模型取得了82.5%的平均分类准确率。实验结果表明,LOG方法不仅分类准确率高,且模型具有较好的稳定性和鲁棒性。

急倾斜巨厚煤层矿震诱冲机制及时-空特征

针对急倾斜巨厚煤层赋存环境复杂,开采过程矿震频发,冲击危险性高的问题,通过构建岩柱力学模型及数值模型、统计分析现场矿震事件,掌握急倾斜巨厚煤层开采的煤岩灾变规律,形成基于动静载理论的急倾斜巨厚煤层矿震诱冲机制。选取5个微震指标深入分析矿震发生的异常前兆及时间跨度特征,预警冲击危险并把握补强卸压时机;通过微震事件定位掌握矿震发生的空间特征,明确卸压关键区域,基于矿震发生的时空特征提出防冲策略。研究结果表明:急倾斜巨厚煤层岩柱在直立极限长度范围内其弯曲变形效应随采深增大愈加明显,岩柱内部能量积聚随采深增加也愈高,岩柱及煤层内高能量积聚区域受开采扰动发生大尺度破裂产生矿震,形成动载震动波,动静载叠加易诱发冲击;矿震发生前日总能量-频次、A(b)、S均出现低值异常,b、P(b)均出现高值异常,异常跨度即表示矿震孕育过程。矿震发生时日总能量-频次、A(b)、S均快速跃升至高值,b值、P(b)值均快速降低至低值;矿震事件发生前在空间上某区域出现明显的缺震现象,缺震程度越高矿震能量越大,据此可对缺震区域采取补强卸压措施,从源头降低冲击危险性。防冲策略包括对岩柱及煤层充分卸压,弱化冲击源头及路径,加强采场与巷道支护,使其具有一定的抗冲能力。但不能保障开采时没有冲击危险,因此需对开采过程煤岩活动密切监测,识别高能矿震发生的时空异常前兆,以便及时精准的采取补强卸压及支护、撤人等安全防护措施。

一种基于空-时快速鲁棒特征的视频词汇的人行为识别方法

提出了一种空-时快速鲁棒特征(SURF)描述子,并且结合视频词汇概念,应用于人行为识别.这种新的描述子在行为识别应用中能很好地体现视频的时空本质,通过词袋(Bag of Words)模型来表征视频,且在表征过程使用了非硬性权重.实验以瑞典皇家理工学院的行为识别数据集作为测试对象,使用了相关领域传统的分类策略,同时引入了包含二次判断的投票系统.实验结果证明,结合特征描述子和视频词汇的行为识别框架在速度和准确率上均优于已有的一些方法,同时该分类策略在某些行为类型上优于传统的分类方法,能有效地应用于行为识别领域.

小分子糖时-空特征及在高糖食品加工保藏中应用的研究进展

单糖和寡糖等小分子糖不同时-空层面的物性转变是决定高糖食品加工保藏性能、安全性和营养价值体现的重要因素。时-空特征,作为描述不同相态下小分子糖分子或基团运动状态的全新参量,已被证实与高糖食品加工保藏过程中的品质劣变及受扩散限制反应的速率间存在明显因果关系。因此针对小分子糖时-空特征规律的深入认识,是保障小分子糖精深加工及研发和构筑功能性高糖食品结构的一种全新思路和技术手段。本文综述了小分子糖时-空特征理论的发展进程,重点介绍了基于热力学方法的时-空特征表征量—Strength值。同时,针对该参量在高糖食品防潮、抗结晶及受扩散限制反应速率调控方面的应用潜力展开了论述。旨在为推动时-空特征规律调控这一全新方法在高糖食品加工保藏性能改善中的应用提供理论储备和技术参考。

基于人体姿态空时特征的驾驶员疲劳检测

为减少疲劳驾驶给道路交通带来的安全隐患,本文以驾驶员人体姿态为研究对象,分析驾驶动作变化与驾驶员疲劳状态之间的联系,提出基于空时特征与人体姿态的驾驶员疲劳检测模型。首先,以改进的Simple Baselines网络定位驾驶员骨架关键点(空间特征);其次,分析驾驶过程中人体姿态的变化特点,依据“高内聚、低耦合”的原则将人体关键点模块化,以此为基础设计多个与驾驶员疲劳驾驶相关的特征表示;最后,引入滑动窗口计算各疲劳特征的离散程度,将其作为长短时记忆网络(时间特征)的输入,从而实现对驾驶员疲劳状态的预测。通过13位被试驾驶人的驾驶行为数据实验结果表明:使用本文提出的基于空-时特征和人体姿态的驾驶员疲劳检测模型可达到97.73%的检测精确率,98.95%的召回率以及98.35%的准确率,表明该检测模型具有可行性。

云南地区各类前震序列时—空—强特征和地震波特征

在清理了云南地区１９６５年以来１１６个地震序列的基础上，研究了表明震源区进入失稳状态的前震序列，它们在主震前１０天在震源区发生，同时比较了早期前震序列和近场前震序列，发现前震序列的频率随时间增加或不衰减、空间展布范围小、强度变化起伏大、地震波振幅比稳定；早期前震序列的频率随时间衰减、空间展布范围大、后期强度变化平缓、地震波振幅比在后期稳定、比值下降；近场前震序列的频度首先出现平静。

基于遥感时-空-谱特征及随机森林模型的土壤重金属空间分布预测

获取土壤重金属的含量特征及空间分布是预防土壤污染和制定环保政策的关键.选取济南市长清区为研究区,系统采集304处表层土壤样品(0~20 cm),利用多源遥感数据构建土壤重金属的光谱特征、时间特征和空间特征;进一步采用相关分析法选择出与土壤重金属密切相关的时-空-谱特征,并将其作为输入自变量,实测土壤砷(As)含量值为因变量,建立基于随机森林(RF)算法的空间预测模型,完成土壤重金属的含量估算和空间分布预测.结果表明:(1)As含量均值超出背景值43.17%,低于农用地土壤污染风险规定的筛选值和管控值,表明As在土壤中出现富集,但处于可管控范围内.(2)在单个遥感特征构建的土壤重金属空间预测模型中,精度由高到低依次为:空间特征(RPIQ=3.87)>时间特征(RPIQ=2.57)>光谱特征(RPIQ=2.50),空间特征对土壤重金属空间预测最为重要.(3)基于“时间-空间”、“时间-光谱”和“空间-光谱”组合特征的土壤重金属空间预测模型均优于单个特征构建的模型,其精度系数RPIQ值分别为4.81、 4.21和4.70.(4)利用“时间-空间-光谱”特征组合输入的随机森林模型达到最佳的空间预测精度(R^(2)=0.90;RMSE=0.77;RPIQ=5.68).(5)As在空间分布上从西北到东南含量逐步降低,主要受到黄河冲淤积和工业活动影响.研究采用的遥感时-空-谱特征结合随机森林算法的土壤重金属空间预测技术,可为土壤污染防治及环境风险管控提供有效的方法支持.

Spatio-temporal Characteristics of Disturbance of Land Use Change on Major Ecosystem Function Zones in China

In recent years, because of increasing human activities, ecosystems have been substantially disturbed and their service functions have been greatly compromised. Based on the effect of land use changes on the major ecosystem services, we estimated the ecosystem comprehensive anthropogenic disturbance index(ECADI) and analyzed the spatio-temporal characteristics of changes in the ECADI in China from 1990 to 2010. The average ECADI of the major ecosystem function zones in China in 2010 is approximately 0.382. The ECADI of Northeast China and North China is slightly higher than that of Northwest China and Southwest China. Most zones have slight changes in the ECADI. The average increases of ECADI in the major ecosystem function zones in China from 1990 to 2000 and from 2000 to 2010 are 0.0024 and 0.0002, respectively. The increase is mainly due to reclamation and urbanization, whereas the decrease is due to the implementation of ecosystem protection policies. During the last 20 years, the ECADI of water resources conservation zones increased first, and then stopped. The ECADI of soil conservation zones increased first, and then declined. The ECADI of sandstorm prevention zones, biodiversity conservation zones and flooding mitigation zones increased continuously. Our results may provide proposals to the government regarding land use planning and ecosystem protection plans in the major ecosystem zones. The major ecosystem function zones in the western part of China have been protected effectively. However, the major ecosystem function zones in the eastern part of China require more protection in the future.

Spatial-temporal Characteristics of Land Subsidence Corresponding to Dynamic Groundwater Funnel in Beijing Municipality,China

Due to long-term over-exploitation of groundwater in Beijing Municipality, regional groundwater funnels have formed and land subsidence has been induced. By combining a groundwater monitoring network, GPS monitor- ing network data, radar satellite SAR data, GIS and other new technologies, a coupled process model based on the dy- namic variation of groundwater and the deformation response of land subsidence has been established. The dynamic variation of groundwater fimnels and the land subsidence response process were analyzed systematically in Beijing. Study results indicate that current groundwater funnel areas are distributed mainly in the southwest of Shunyi District, the northeast of Chaoyang District and the northwest of Tongzhou District, with an average decline rate of groundwa- ter level of 2.66 rn/yr and a maximum of 3.82 m/yr in the center of the funnels. Seasonal and interannual differences exist in the response model of land subsidence to groundwater funnels with uneven spatial and temporal distribution, where the maximum land subsidence rate was about --41.08 mm/yr and the area with a subsidence rate greater than 30 mm/yr was about 1637.29 km2. Although a consistency was revealed to exist between a groundwater funnel and the spatial distribution characteristics of the corresponding land subsidence funnel, this consistency was not perfect. The results showed that the response model of land subsidence to the dynamic variation of groundwater was more revealing when combining conventional technologies with InSAR, GIS, GPS, providing a new strategy for environmental and hydrogeological research and a scientific basis for regional land subsidence control.

Measuring Spatio-temporal Characteristics of City Expansion and Its Driving Forces in Shanghai from 1990 to 2015

Urbanization has both direct and indirect impacts on land use change, and analyzing spatio-temporal characteristics of land use change is essential for understanding these impacts. By comparing Landsat TM images, this paper examines the changes of land use structure and landscape patterns in Shanghai from 1990 to 2015. It finds that the city doubled in size, with the growth of isolated construction land being most significant among eight land use types. A land use change matrix was established and landscape indices were selected to evaluate the change of spatial structure in Shanghai. In order to identify the main driving forces of city expansion in Shanghai, this research ran partial least square regression models to assess the impact of 10 social-economic factors on land use change of Shanghai from 1990 to 2015. It then conducted bivariate correlation analysis to explore the drivers of change of various land use types: urban settlement, rural settlement and isolated construction land. Besides quantitative analysis, this paper analyzes the influence of policy-dimensional factors in land use change. It concludes with future potential research topics on land use change in a rapidly urbanizing context.

Tourism Competitiveness Evaluation and Spatio-temporal Characteristics of Chinese Border Counties

Under the current government strategy of building a Silk Road economic belt, tourism in Chinese border counties has becoming increasingly popular. Studying tourism competitiveness in Chinese border counties is of sizable theoretical and practical importance, as there are several notable factors involved. In this study, we constructed a tourism competitiveness evaluation model based on eight factors: natural environment, tourism resource, location and transportation, social environment, tourism service facility, border port, tourism industrial cluster and tourism market. We then analyzed the spatial characteristics of tourism competitiveness in border counties and identified five types of border counties: resource advantage type(RA), border-port advantage type(PA), location advantage type(LA), agglomeration advantage type(AA), and relative balance type(RB), and examined the correlation between tourism market competitiveness and interior competitiveness factors in the counties from 2006 to 2011. Results showed that tourism resource, location and transportation, and tourism service facility are the most important competition factors for RA border counties during the study period. Competition factors in PA counties transferred from tourism resource, social environment and tourism service facility to border port and tourism industrial cluster; competition factors in LA counties transferred from natural environment and tourism resource to tourism service facility and tourism industrial cluster and border port. Competition factors in AA counties transferred from tourism service facility to tourism resource. Tourism industrial cluster, tourism service facility and tourism resource proved to be important competition factors in RB counties. The findings of this study can be used to target tourism strategies according to different county types.

Space-Time Characteristic Analysis of Wind Field over the South Indian Ocean

According to the ship observation data over the South Indian Ocean during 1950 1995, taking 1°× 1° and 5°× 5°grid, the characteristics and variation rule of wind are analyzed. Through analyzing the chart of isopleths of the monthly elements, the conclusion that the seasonal variation of the wind field over the South Indian Ocean is less remarkable than that in the oceans of the Northern Hemisphere is got. The seasonal variation of the wind field is also obvious in this region, but the seasonal difference is little. The wind in winter is stronger than in summer, correspondingly, the average wind speed is higher, and the frequencies of gale of forces ≥ 6 and 8 are also higher. The north of 10°S is a monsoon area; Southeast wind prevails all over the year in the rest of the trade wind area; Westerly wind dominates in the south of 40°S. This paper provides specific data of wind field and variation for ship ocean transportation, ocean-going visits and scientific experiment.

Spatial-temporal Characteristics and Factors Influencing Commuting Activities of Middle-class Residents in Guangzhou City, China

The middle class in metropolitan Chinese cities has become an important social group. With the rapid development of urbanization and constant advancement of suburbanization, the middle class has increasingly come to influence city traffic. Research into middle-class commuting activities thus has practical significance for improving traffic congestion and reducing the commuting burden in metropolitan cities. Based on a dataset formed by 816 completed surveys, this paper analyzes the commuting mode, time and distance of middle-class residents in Guangzhou City using the descriptive statistical method. The results indicate that private cars are the main commuting mode, followed by public transport. Meanwhile, middle-class residents mainly undertake medium-short time and medium-short distance commuting. The study subsequently uses multilevel logistic regression and multiple linear regression models to analyze the factors that influence commuting mode choice, time and distance. The gender, age, number of family cars, housing source and jobs-housing balance are the most important factors influencing commuting mode choice; housing, population density, jobs-housing balance and commuting mode significantly affect commuting time; and transport accessibility, jobs-housing balance and commuting mode are the notable factors affecting commuting distance. Finally, this paper analyzes what is affecting the commuting activities of middle-class residents and determines the differences in commuting activity characteristics and influence factors between middle-class and ordinary residents. Policy suggestions to improve urban planning and urban management are also proposed.

Spatial-Temporal Characteristics of Regional Extreme Low Temperature Events in China during 1960-2009

An objective identification technique is used to detect regional extreme low temperature events （RELTE） in China during 1960-2009. Their spatial-temporal characteristics are analyzed. The results indicate that the lowest temperatures of RELTE, together with the frequency distribution of the geometric latitude center, exhibit a double-peak feature. The RELTE frequently happen near the geometric area of 30°N and 42°N before the mid-1980s, but shifted afterwards to 30°N. During 1960-2009, the frequency~ intensity, and the maximum impacted area of RELTE show overall decreasing trends. Due to the contribution of RELTE, with long duratioh and large spatial range, which account for 10% of the total RELTE, there is a significant turning point in the late 1980s. A change to a much more steady state after the late 1990s is identified. In addition, the integrated indices of RELTE are classified and analyzed.

SPATIO-TEMPORAL VARIATION CHARACTERISTICS OF EXTREMELY HEAVY PRECIPITATION FREQUENCY OVER SOUTH CHINA IN THE LAST 50 YEARS

This paper comprehensively studies the spatio-temporal characteristics of the frequency of extremely heavy precipitation events over South China by using the daily precipitation data of 110 stations during 1961 to 2008 and the extremely heavy precipitation thresholds determined for different stations by REOF, trend coefficients, linear trend, Mann-Kendall test and variance analysis. The results are shown as follows. The frequency distribution of extremely heavy precipitation is high in the middle of South China and low in the Guangdong coast and western Guangxi. There are three spatial distribution types of extremely heavy precipitation in South China. The consistent anomaly distribution is the main type. Distribution reversed between the east and the west and between the south and the north is also an important type. Extremely heavy precipitation events in South China mainly occurred in the summer-half of the year. Their frequency during this time accounts for 83.7% of the total frequency. In the 1960 s and 1980 s, extremely heavy precipitation events were less frequent while having an increasing trend from the late 1980 s. Their climatological tendency rates decrease in the central and rise in the other areas of South China, and on average the mean series also shows an upward but insignificant trend at all of the stations. South China's frequency of extremely heavy precipitation events can be divided into six major areas and each of them shows a different inter-annual trend and three of the representative stations experience abrupt changes by showing remarkable increases in terms of Mann-Kendall tests.

基于多域特征的滚动轴承故障检测和状态识别方法

为提高滚动轴承故障检测与识别效果,提出一种基于局部均值分解(LMD)和共空间模式(CSP)的时-频-空多域特征提取方法。首先采用LMD将滚动轴承信号分解为多个乘积分量(PF)并提取时-频熵特征,基于支持向量数据描述(SVDD)分类器实现正常和故障轴承的分类;然后利用CSP对故障轴承信号进行分解并提取空域熵特征;最后利用K-均值聚类算法进行聚类,实现对外圈故障、内圈故障和滚柱故障的区分。实验结果表明,所提方法可以获得优于80%的正确分类性能,明显优于传统单一维度特征。

State Space-Time and Four States of Universe

All things in the universe possess a state and characteristics of state, resultantly in presence of space-time, which is perceived by human beings. An outlook of space-time is shaped in human by perceiving the existence and change of objects. The state space is all state characteristics exhibited in objects whilst the state time refers to the duration of an object＇s state. The time is a spatial property and not an independent dimension. The state space-time is a unity of internal and external space-time. The internal space-time is stemmed from the overall internal forces and internal energies and is a covert space-time. The external space-time refers to a space-time manifested by the external characteristics and movement of an object and is an overt space-time. In physics, there are four kinds of forces and four state space-times： bonding force and three-dimensional space-time; strong interaction of exchangeable n meson and two-dimensional space-time; quark confinement and one-dimensional space-time; and weak interaction and zero-dimensional space-time. The universe is constituted by dissimilar state space-times. Newton space-time is a three-dimensional state space-time; Einstein＇s theory of relativity is a two-dimensional state space-time. Newton and Einstein were different observers. Temporal and spatial perception of human is dependent upon human＇s intemal energy and quality. Through Qigong exercises, the human is able to enter the three-dimensional, two-dimensional, one-dimensional and zero-dimensional space-times. The relativity theory of human body will solve the time problems at the interplanetary voyage of astronauts.

Temporal and spatial variations in extreme temperatures in the Qilian Mountains-Hexi Corridor over the period 1960-2013

Based on daily maximum and minimum temperatures at 18 meteorological stations in the Qilian Mountains and Hexi Corridor between 1960 and 2013,temporal and spatial variations in extreme temperatures were analysed using linear trends,tenpoint moving averages and the Mann-Kendall test.The results are as follows:The trends in the majority of the extreme temperature indices were statistically significant,and the changes in the extreme temperatures were more obvious than the changes in the extreme values.The trends were different for each season,and the changes in rates and intensities in summer and autumn were larger than those in spring and winter.Unlike the cold indices,the magnitudes and trends of the changes in the warm indices were larger and more significant in the Hexi Corridor than in the Qilian Mountains.Abrupt changes were detected in the majority of the extreme temperature indices,and the extreme cold indices usually occurred earlier than the changes in the extreme warm indices.The abrupt changes in the extreme temperatures in winter were the earliest among the four seasons,indicating that these temperature changes were the most sensitive to global climate change.The timing of the abrupt changes in certain indices was consistent throughout the study area,but the changes in the cold indices in the Hexi Corridor occurred approximately four years before those in the Qilian Mountains.Similarly,the changes in the warm indices in the western Hexi Corridor preceded those of the other regions.

Temporal Characteristics of the Queueing Process ot 3uffer-aided Wireless Communications

Due to the fading property of wireless channels, the instant transmission capability of a fading channel, i.e., the instantaneous channel capacity, will change randomly along time. Usually, a finite size buffer is needed at the transmitter to match instant channel capacity with the source data stream. This paper is focused on the queuing process in the buffer. The temporal characteristics of the queueing process in the buffer are investigated, for a buffer-aided communication over block Rayleigh fading channel, in the low signal- to-noise ratio regime. Particularly, the average absorbing time for the buffer to transfer from empty state to overflow sate and from overflow state to empty state, as well as the stable working time in which neither buffer empty nor buffer overflow happens are derived. Theoretical and numerical results show that increasing the buffer size and traffic load properly will improve the efficiency of the transmission.

Temporal and spatial profiling of nuclei-associated proteins upon TNF-α/NF-kB signaling

The tumor necrosis factor （TNF）-α/NF-kB-signaling pathway plays a pivotal role in various processes including apoptosis, cellular differentiation, host defense, inflammation, autoimmunity and organogenesis. The complexity of the TNF-α/NF-kB signaling is in part due to the dynamic protein behaviors of key players in this pathway. In this present work, a dynamic and global view of the signaling components in the nucleus at the early stages of TNF-a/ NF-KB signaling was obtained in HEK293 cells, by a combination of subcellular fractionation and stable isotope la- beling by amino acids in cell culture （SILAC）. The dynamic profile patterns of 547 TNF-α-induced nuclei-associated proteins were quantified in our studies. The functional characters of all the profiles were further analyzed using that Kyoto Encyclopedia of Genes and Genomes （KEGG） pathway annotation. Additionally, many previously unknown effectors of TNF-α/NF-kB signaling were identified, quantified and clustered into differential activation profiles. In- terestingly, levels of Fanconi anemia group D2 protein （FANCD2）, one of the Fanconi anemia family proteins, was found to be increased in the nucleus by SILAC quantitation upon TNF-α stimulation, which was further verified by western blotting and immunofluorescence analysis. This indicates that FANCD2 might be involved in TNF-α/NF-kB signaling through its accumulation in the nucleus. In summary, the combination of subcellular proteomics with quan- titative analysis not only allowed for a dissection of the nuclear TNF-α/NF-kB-signaling pathway, but also provided a systematic strategy for monitoring temporal and spatial changes in cell signaling.