Automated Target Detection and Discrimination Using Constrained Kurtosis Maximization

Exploiting hyperspectral imagery without prior information is a challenge. Under this circumstance, unsupervised target detection becomes an anomaly detection problem. We propose an effective algorithm for target detection and discrimination based on the normalized fourth central moment named kurtosis, which can measure the flatness of a distribution. Small targets in hyperspectral imagery contribute to the tail of a distribution, thus making it heavier. The Gaussian distribution is completely determined by the first two order statistics and has zero kurtosis. Consequently, kurtosis measures the deviation of a distribution from the background and is suitable for anomaly/target detection. When imposing appropriate inequality constraints on the kurtosis to be maximized, the resulting constrained kurtosis maximization (CKM) algorithm will be able to quickly detect small targets with several projections. Compared to the widely used unconstrained kurtosis maximization algorithm, i.e., fast independent component analysis, the CKM algorithm may detect small targets with fewer projections and yield a slightly higher detection rate.     

非量测数码影像在航测成图中的应用

如何加速成图周期,快速、高效地生产各种地理信息产品是摄影测量应用研究的主要内容.本文介绍了非量测数码航摄影像在全数字摄影测量工作站上进行地理信息产品生产的技术方法和工作流程,研究了关键技术环节.     

An essay on the interactions between climate and society

There has been increasing concern about the lack of involvement by social scientists and humanists in a global change program, although many social scientists are already directly involved in various aspects of research on environmental change, and their research interests are clearly central to a global change research agenda. Based on a historical review, the role of social science disciplines as well as social science institutes in an emerging multidecadal global change program is discussed. Both “plan of action” and “plan of inaction” are suggested to avoid potential pitfalls due to the rush development of a social science program into the existing global climate change problem.     

华北克拉通东部早白垩世伸展盆地的发育过程及其对克拉通的破坏

在晚侏罗世华北克拉通东部破坏之初出现了区域性隆起,全区缺失上侏罗统沉积。在早白垩世早期,出现了区域性的伸展活动,断陷盆地形成,克拉通南、北缘伸展活动最强,北部燕山构造带以出现变质核杂岩为特征,南部出现宽裂谷型盆地。早白垩世中期华北克拉通东部普遍出现了火山活动与岩浆侵入。早白垩世晚期克拉通上以出现窄裂谷型盆地为特征,沿北北东走向的郯庐断裂带断陷活动最强。这些断陷盆地的演化过程揭示,经历地表抬升后,克拉通破坏之初的岩石圈热而弱,从而形成变质核杂岩或宽裂谷型盆地。这期间的破坏强度在空间上具有不均匀分布的特征,受控于早期岩石圈地幔的结构。经过早白垩世中期的大量岩浆活动之后,早白垩世晚期克拉通岩石圈温度降低、强度变大,从而利用早期大型断裂构造形成窄裂谷型盆地。这现象支持华北克拉通东部晚中生代的岩石圈减薄是以逐渐拆沉机制为主。     

扬州市6－7月份天气预报服务业务化系统

从地（市）级气象台的业务工作出发,试图建立通过微机实现的对上接收信息、对外预报服务、对下预报指导的三位一体的天气预报服务业务化系统,以发挥地（市）级气象台在经济建设和防灾减灾中的作用,推动天气预报和服务的现代化建设,把基层气象工作推向一个新的台阶。     

Kinetics of peptide hydrolysis and amino acid decomposition at high temperature

Dipeptide hydrolysis and amino acid decomposition appear to follow a first-order rate law. The hydrolysis rate increases exponentially with increasing temperature in aqueous solution at both 265 atm and water steam pressures over the temperature range of 100 to 220 degrees C. Dipeptide hydrolysis has a lower apparent activation energy at 265 atm (44.1 KJ/mol) than at water steam pressure (98.9 KJ/mol). At lower temperatures (<200-220 degrees C), the rate of peptide bond hydrolysis is faster at 265 atm than at water steam pressure. At higher temperatures (>200-220 degrees C), however, peptide bond hydrolysis is slower at 265 atm than at water steam pressure. In aqueous solution, amino acid decomposition rates also increase exponentially with increasing temperature. Amino acid decomposition rates are much higher at 265 atm than at water steam pressure over the entire temperature range investigated.     

Threshold velocity for wind erosion: the effects of porous fences

Porous fence is a kind of artificial windbreak that has many practical applications. The threshold wind velocities at different distances downwind from porous fences were measured and the corresponding characteristics of particle movement observed to assess their shelter effect. It is found that the fence’s porosity is the key factor that determines the resulting shelter effect. The area near a fence can be typically classified into five regions, each with a different mode of particle movement. Dense fences, and especially solid fences, favor the accumulation of sand upwind of the fences. Fences with porosities of 0.3–0.4 produce the maximum threshold wind velocity; those with porosities of 0.3–0.6 (depending on the fence height) provide the maximum effective shelter distance. It is confirmed that the fence porosities of 0.3–0.4 that have been proposed for practical application in previous research are the most effective for abating wind erosion.     

Water–rock interaction during the process of steam stimulation exploitation of viscous crude oil in Liaohe Shuguang Oil Field, Liaoning, China

In the process of steam stimulation exploitation of viscous crude oil, the injected water, at high temperature and under high pressure, reacts intensively with the host rock. This kind of water–rock interaction in Liaohe Shuguang Oil Field was studied on the basis of analysis of water composition changes, laboratory experiments, mineral saturation indices analysis, and mass balance calculation. Compared with the injected water, the changes of the composition of discharged water are mainly the distinct decrease of pH, Na⁺, SiO₂ and Cl⁻, as well as the increase of K⁺, Ca²⁺, Mg²⁺, SO ₄ ²⁻ and HCO ₃ ⁻ . Laboratory experiments under field conditions showed: the dissolution sequence of minerals quantitatively is quartz>potassium feldspar>albite, and the main change of clay minerals is the conversion of kaolinite to analcime. Mass balance calculation indicated during the process of steam stimulation, large quantities of analcime are precipitated with the dissolution of large amounts of quartz, kaolinite, potassium feldspar, and CO₂. These results correlated very well with the experimental results. The calculated results of Liaohe Shuguang Oil Field showed that during the steam stimulation for viscous crude oil, the amounts of minerals dissolved (precipitated) are huge. To control the clogging of pore spaces of oil reservoirs, increased study of water–rock interaction is needed.     

REE characteristics of the Fanshan alunite deposit in Zhejiang Province, China

1 Introduction Alunite [KAl3(SO4)2(OH)6] is a very important non-ferrous metal resource, so many countries throughout the world have made great investments in research on the mechanism of its formation, its geological characteristics and applications. O…