A spatial sampling optimization package using MSN theory

The density and distribution of spatial samples heavily affect the precision and reliability of estimated population attributes. An optimization method based on Mean of Surface with Nonhomogeneity (MSN) theory has been developed into a computer package with the purpose of improving accuracy in the global estimation of some spatial properties, given a spatial sample distributed over a heterogeneous surface; and in return, for a given variance of estimation, the program can export both the optimal number of sample units needed and their appropriate distribution within a specified research area. (C) 2010 Elsevier Ltd. All rights reserved.

Third-order Stokes wave solutions for interfacial internal waves in a three-layer density-stratified fluid

Interfacial internal waves in a three-layer density-stratified fluid are investigated using a singular method, and third-order asymptotic solutions of the velocity potentials and third-order Stokes wave solutions of the associated elevations of the interfacial waves are presented based on the small amplitude wave theory. as expected, the third-order solutions describe the third-order nonlinear modification and the third-order nonlinear interactions between the interfacial waves. The wave velocity depends on not only the wave number and the depth of each layer but also on the wave amplitude.

Second-order Stokes solutions for internal waves in three-layer density-stratified fluid

In this paper, internal waves in three-layer stratified fluid are investigated by using a perturbation method, and the second-order asymptotic solutions of the velocity potentials and the second-order Stokes solutions of the associated elevations of the interfacial waves are presented based on the small amplitude wave theory. As expected, the first-order solutions are consistent with ordinary linear theoretical results, and the second-order solutions describe the second-order modification on the linear theory and the interactions between the two interfacial waves. Both the first-order and second-order solutions derived depend on the depths and densities of the three-layer fluid. It is also noted that the solutions obtained from the present work include the theoretical results derived by Umeyama as special cases.

Second-order Stokes wave solutions for intefacial waves in three-layer stratified fluid with background current

In this paper, interfacial waves in three-layer stratified fluid with background current are investigated using a perturbation method, and the second-order asymptotic solutions of the velocity potentials and the second-order Stokes wave solutions of the associated elevations of the interfacial waves are presented based on the small amplitude wave theory, and the Kelvin-Helmholtz instability of interfacial waves is studied. As expected, for three-layer stratified fluid with background current, the first-order asymptotic solutions (linear wave solutions), dispersion relation and the second-order asymptotic solutions derived depend on not only the depths and densities of the three-layer fluid but also the background current of the fluids, and the second-order Stokes wave solutions of the associated elevations of the interfacial waves describe not only the second-order nonlinear wave-wave interactions between the interfacial waves but also the second-order nonlinear interactions between the interfacial waves and currents. It is also noted that the solutions obtained from the present work include the theoretical results derived by Chen et al (2005) as a special case. It also shows that with the given wave number k (real number) the interfacial waves may show Kelvin-Helmholtz instability.

胶州湾及其邻近海域的浮游植物－种类组成与数量变化

研究胶州湾浮游植物的物种组成与时空分布的特点，对于了解该湾生态系统的现状与历史变化趋势以及生态系统对自然条件变化和人类干扰的响应具有重要意义。 本文根据2004年每月一次采集的浮游植物样品，分析了胶州湾浮游植物的物种组成和优势种的时空分布情况。调查发现浮游植物共142种，分属于6门53属，其中硅藻门40属113种，占总物种数的79.6%；甲藻门10属24种，占总物种数的16.9%；其它为金藻门1属2种，裸藻1属1种，绿藻1属2种。浮游植物丰度周年波动范围为11.12－14602.39×104cells/m3，全年平均为1857.55×104cells/m3。全年丰度最高的藻为环纹劳德藻(Lauderia annulata)，出现在2月份，而全年的丰度最高值也出现在2月份。在胶州湾中，硅藻所占比例最大，平均为97.44%，最高为99.95%，最低为82.55%。浮游植物的丰度的周年变化：有两个高峰，分别出现在2月份和10月份，是典型的温带海域双高峰的分布形式。 胶州湾浮游植物的优势种分析，采用Kikvidze等（2002）提出的确定优势种数量的计算方法，再依据各物种的优势度排序最终确定优势种。其中在多样性最低的6月和10月，优势种数目均为1种，分别为丹麦细柱藻（Leptocylindrus danicus）和中肋骨条藻（Skeletonema costatum）。而在多样性指数较低的1月、2月，优势种数目分别为2和3；而在物种多样性比较高的5月、7月、11月，由于分布相对比较分散，所以优势种数量较多。这说明这个方法可以较好地完成对胶州湾浮游植物群落分析时确定优势种的目标。优势种出现频率较多的种类为中肋骨条藻（1、3、4、5、8、10、11、12月）、洛氏角毛藻(Chaetoceros lorenzianus)（7、8、9、11、12月）、尖刺拟菱形藻(Pseudonitzschia pungens)（2、3、5、7月）、加拉星杆藻(Asteronella kariana)（1、2、3、5月）、密联角毛藻(Chaetoceros densus)（5、11、12月）、扭鞘藻(Streptothece thamesis)（7、8、9月）、夜光藻(Noctiluca scintillancs)（4、5、7月）、奇异菱形藻(Nitzschia paradoxa)（5、11、12月）,对这些种的时空分布进行了分析。 对2004年胶州湾的浮游植物数据进行分层聚类分析后，发现可以将胶州湾划分为三个海区：湾南与湾外海区、湾中西部海区、湾东海区。

基于解耦控制的SCARA机器人轨迹跟踪控制器设计

SCARA型机器人的控制问题由于其动力学模型中没有重力矩项的作用而得以简化,由于在实际应用中经常要求其高速运动,则对具有强耦合的哥氏力与向心力的控制就成为制约其系统性能的重要问题。提出通过线性变换对机器人系统解耦,将高阶系统转化为解耦的低阶系统进行控制的方法,并且应用极点配置对解耦的系统求解机器人控制器。该方法无需测量关节速度和加速度,只需要测量关节位置信号。所提出的控制器既能保证闭环系统全局渐进稳定,又能通过对线性化系统闭环极点的配置来获得期望的闭环系统响应性能。仿真实验证明了所提出的控制器设计方法的可行性。

Global Translation Preferred Active Contour

具有全局平移优先属性的主动轮廓更适于目标跟踪。演化轮廓具有的全局平移优先性可以理解为沿轮廓的速度场具有相等的倾向。根据此思想,通过定义在曲线扰动集合上的新内积空间导出了一种简单,具有平移优先的梯度流。新的内积空间由于是通过向H0主动轮廓对应的內积空间引入曲线扰动的方差获得,所以此主动轮廓称为方差主动轮廓。方差主动轮廓是将H0主动轮廓与其对应的平均梯度流通过加权求和获得,而H1主动轮廓则是通过H0主动轮廓与特定类型的核函数进行卷积得到。因此方差主动轮廓实现时更简单和快速。最后给出了H0,H1和方差主动轮廓在频域与时域的分析。

中国西部大气和雪冰黑碳及其传输过程研究

Glaciers in west China are the sources of the major great rivers in Asia, and the solid water resources are crucial to China and South Asia. Black carbon (BC) results in very complex climate effects not only in the atmosphere, but accelerates the melting after its deposit on the surface of snow/ice. As the main distributed area of glaciers in China, the Tibetan Plateau (TP) and Xinjiang region are abutted by South Asia, Central Asia, and Russia, and east China, and the atmospheric environment would be influenced by the BC emitted from these regions. Whereas, the BC’s temporal and spatial distributions for concentration in the mid and top troposphere in west China, its transport, and its radiative forcing after deposited on the snow/ice surface are not well understood at the present. In the field, we collected samples from surface snow, snow pits, ice core, and aerosol in the glaciers, analyzed BC content mainly by the thermo-oxidized method in the laboratory, and discussed temporal and spatial distributions for BC concentrations in glaciers, the transport, and its impacts on the environment. Several conclusions were derived as follows: 1_Spatial distribution and the impact on albedos for BC concentrations in snow/ice: the BC concentrations in the surface snow for the investigated glaciers could be placed in areas, the Tianshan Mountains ＞ the central TP ＞ the Pamirs ＞ the Qilian Mountians ＞ the Himalayas. This distribution could be attributed to the elevation of the glaciers, the topography of the TP, and more regional emissions. Probably significant impacts on the albedos of the glacier surface could be caused by BC deposits, and the estimated reduced albedos on the glaciers are 9.8% (the Zhadang glacier), 8.7% (the Miao’ergou Riverhead No.3 glacier), and 6.8% (the Kuitun River Haxilegen No.48 glacier), and 6.2% (the Dongkemadi glacier), and 5.3% (the La’nong glacier), and 4.2% (the Muztagata glacier), etc. 2_The temporal variance of BC concentrations in ice of the East Rongbuk Glacier (ERG) and its climatic implications: major cations and anions (e.g., SO42- and Ca2+) concentrations in aerosols during summer monsoon seasons showed their close relationships with the sources of air masses, in which the variance of SO42- concentrations suggested the atmospheric environment over the ERG was significantly influenced by the aerosols from South Asia. BC record based on an ice core suggested its deposit was dominantly transported by monsoons in summers and by westerlies in other seasons, and the BC from South Asia in summers dominated the varying trend of its concentrations in the ice core and caused higher concentrations in summers than those in other seasons. In the past 50 yrs, BC concentrations showed fluctuations, whereas showed an increasing tread in the most recent decade, and exceeded 50 μg kg-1 in the summer of 2001; correspondingly, the radiative forcing caused by BC showed an increasing trend since 1990s, and exceeded 4.5 W m-2 in the summer of 2001. 3_Cabonaceous aerosols in the Nam Co region: organic carbon (OC) concentration accounted for ～95% and BC for ～5% in the total carbonaceous aerosol concentration, which was significantly influenced by summer precipitations. OC was dominantly derived from fossil fuel burning and BC from both fossil fuel and biomass burning. Trajectory analysis and aerosol optical depth suggested the atmospheric environment in the Nam Co region was most probably influenced by the emissions from South Asia. The potential source regions of air pollutants in the Nam Co regions in summers might be Bangladesh and east India, and in winters might be the Indo-gangetic basin. The scavenging ratio of atmospheric BC by rainfalls was less than those at other sites. West China is a less-developed region for industry, where BC concentrations in the atmosphere and snow/ice could be significantly influenced by the emissions from the abutted regions with rising industries (South Asia, Central Asia, and Russia). For example, snow/ice BC concentrations in the glaciers of the Parmirs, the Tianshan Mountains, and the Qilian Mountains in the northeast margin of the TP might be more influenced by the emissions from Centrial Asia (transported by the westerlies), those in the glaciers of the Himalayas might be more influenced by the emissions from South Asia (transported by the monsoons and the westerlies), and atmospheric carbonaceous aerosols might also be more influenced by the emissions from South Asia (transported by the monsoons and the westerlies). The BC concentrations in some glaciers might cause significant impacts on the albedos for the glaciers, and therefore enhanced the radiative forcings, for example, the ERG. The research on the relationships among atmospheric and snow/ice BC and its radiative forcing, variance of snow cover, mass balance of glaciers, and climate forcing would be needed in future.

电离层参量M(3000)F2和hmF2的经验正交函数方法建模研究

The ionospheric parameter M(3000)F2 (the so-called transmission factor or the propagation factor) is important not only in practical applications such as frequency planning for radio-communication but also in ionospheric modeling. This parameter is strongly anti-correlated with the ionospheric F2-layer peak height hmF2，a parameter often used as a key anchor point in some widely used empirical models of the ionospheric electron density profile (e.g., in IRI and NeQuick models). Since hmF2 is not easy to obtain from measurements and M(3000)F2 can be routinely scaled from ionograms recorded by ionosonde/digisonde stations distributed globally and its data has been accumulated for a long history, usually the value of hmF2 is calculated from M(3000)F2 using the empirical formula connecting them. In practice, CCIR M(3000)F2 model is widely used to obtain M(3000)F2 value. However, recently some authors found that the CCIR M(3000)F2 model has remarkable discrepancies with the measured M(3000)F2, especially in low-latitude and equatorial regions. For this reason, the International Reference Ionosphere (IRI) research community proposes to improve or update the currently used CCIR M(3000)F2 model. Any efforts toward the improvement and updating of the current M(3000)F2 model or newly development of a global hmF2 model are encouraged. In this dissertation, an effort is made to construct the empirical models of M(3000)F2 and hmF2 based on the empirical orthogonal function (EOF) analysis combined with regression analysis method. The main results are as follows: 1. A single station model is constructed using monthly median hourly values of M(3000)F2 data observed at Wuhan Ionospheric Observatory during the years of 1957–1991 and compared with the IRI model. The result shows that EOF method is possible to use only a few orders of EOF components to represent most of the variance of the original data set. It is a powerful method for ionospheric modeling. 2. Using the values of M(3000)F2 observed by ionosondes distributed globally, data at grids uniformly distributed globally were obtained by using the Kriging interpolation method. Then the gridded data were decomposed into EOF components using two different coordinates: (1) geographical longitude and latitude; (2) modified dip (Modip) and local time. Based on the EOF decompositions of the gridded data under these two coordinates systems, two types of the global M(3000)F2 model are constructed. Statistical analysis showed that the two types of the constructed M(3000)F2 model have better agreement with the observational M(3000)F2 than the M(3000)F2 model currently used by IRI. The constructed models can represent the global variations of M(3000)F2 better. 3. The hmF2 data used to construct the hmF2 model were converted from the observed M(3000)F2 based on the empirical formula connecting them. We also constructed two types of the global hmF2 model using the similar method of modeling M(3000)F2. Statistical analysis showed that the prediction of our models is more accurate than the model of IRI. This demonstrated that using EOF analysis method to construct global model of hmF2 directly is feasible. The results in this thesis indicate that the modeling technique based on EOF expansion combined with regression analysis is very promising when used to construct the global models of M(3000)F2 and hmF2. It is worthwhile to investigate further and has the potential to be used to the global modeling of other ionospheric parameters.

高斯束偏移的方法及应用

Gaussian beam is the asymptotic solution of wave equation concentred at the central ray. The Gaussian beam ray tracing method has many advantages over ray tracing method. Because of the prevalence of multipath and caustics in complex media, Kirchhoff migration usually can not get satisfactory images, but Gaussian beam migration can get better results.The Runge-Kutta method is used to carry out the raytracing, and the wavefront construction method is used to calculate the multipath wavefield. In this thesis, a new method to determine the starting point and initial direction of a new ray is proposed take advantage of the radius of curvature calculated by dynamic ray tracing method.The propagation characters of Gaussian beam in complex media are investigated. When Gaussian beam is used to calculate the Green function, the wave field near the source was decomposed in Gaussian beam in different direction, then the wave field at a point is the superposition of individual Gaussian beams.Migration aperture is the key factor for Kirchhoff migration. In this thesis, the criterion for the choice of optimum aperture is discussed taking advantage of stationary phase analysis. Two equivalent methods are proposed, but the second is more preferable.Gaussian beam migration based on dip scanning and its procedure are developed. Take advantage of the travel time, amplitude, and takeoff angle calculated by Gaussian beam method, the migration is accomplished.Using the proposed migration method, I carry out the numerical calculation of simple theoretical model, Marmousi model and field data, and compare the results with that of Kirchhoff migration. The comparison shows that the new Gaussian beam migration method can get a better result over Kirchhoff migration, with fewer migration noise and clearer image at complex structures.

序列视觉信息整合的特性与机制

One of the great puzzles in the psychology of visual perception is that the visual world appears to be a coherent whole despite our viewing it through temporally discontinuous series of eye fixations. The investigators attempted to explain this puzzle from the perspective of sequential visual information integration. In recent years, investigators hypothesized that information maintained in the visual short-term memory (VSTM) could become visual mental images gradually during time delay in visual buffer and integrated with information perceived currently. Some elementary studies had been carried out to investigate the integration between VSTM and visual percepts, but further research is required to account for several questions on the spatial-temporal characteristics, information representation and mechanism of integrating sequential visual information. Based on the theory of similarity between visual mental image and visual perception, this research (including three studies) employed the temporal integration paradigm and empty cell localization task to further explore the spatial-temporal characteristics, information representation and mechanism of integrating sequential visual information (sequential arrays). The purpose of study 1 was to further explore the temporal characteristics of sequential visual information integration by examining the effects of encoding time of sequential stimuli on the integration of sequential visual information. The purpose of study 2 was to further explore the spatial characteristics of sequential visual information integration by investigating the effects of spatial characteristics change on the integration of sequential visual information. The purpose of study 3 was to explore the information representation of information maintained in the VSTM and integration mechanism in the process of integrating sequential visual information by employing the behavioral experiments and eye tracking technology. The results indicated that: (1) Sequential arrays could be integrated without strategic instruction. Increasing the duration of the first array could cause improvement in performance and increasing the duration of the second array could not improve the performance. Temporal correlation model was not fit to explain the sequential array integration under long-ISI conditions. (2) Stimuli complexity influenced not only the overall performance of sequential arrays but also the values of ISI at asymptotic level of performance. Sequential arrays still could be integrated when the spatial characteristics of sequential arrays changed. During ISI, constructing and manipulating of visual mental image of array 1 were two separate processing phases. (3) During integrating sequential arrays, people represented the pattern constituted by the objects' image maintained in the VSTM and the topological characteristics of the objects' image had some impact on fixation location. The image-perception integration hypothesis was supported when the number of dots in array 1 was less than empty cells, and the convert-and-compare hypothesis was supported when the number of the dot in array 1 was equal to or more than empty cells. These findings not only contribute to make people understand the process of sequential visual information integration better, but also have significant practical application in the design of visual interface.

影响汉语阅读能力发展的相关认知因素及其作用的发展变化

The present cross-sectional study paid attention to Chinese reading acquisition of 391 children from preschool to grade 3 in two elementary schools, and investigated the relationship between orthographic processing skills, morphological awareness, phonological awareness, naming, phonological memory, visual processing skill and reading skills, after controlling the variance of age, nonverbal intelligence and pinyin knowledge. The main results are as follows: Firstly, there are many different language skills as the predictors of Chinese reading success. Orthographic processing skills, morphological awareness, phonological awareness and naming are important in single-character recognition and comprehension. Beside them, the effect of visual processing skill and phonological memory for comprehension are also significant. Among them, the role of orthographic processing skills is the most important, whatever in single-character recognition or in comprehension. Secondly, orthographic processing skills are the most important factors in reading acquisition at low grade and its effect drops obviously after grade 2. Thirdly, morphological awareness is also the factor that cannot be ignored whatever for single-character recognition or for comprehension. Its influence appears in preschool and becomes the only significant predictor of character recognition in grade 3. Furthermore, morphological awareness is more relevant with the development of comprehension. Fourthly, phonological awareness plays the secondary role in Chinese reading acquisition except in grade 2 when its contribution is most of all. And compare with morphological awareness, the effect of phonological awareness is relative low. Fifthly, naming is important through preschool to grade 2. The contribution of phonological memory increases from preschool to grade 3 in comprehension.

中学生抑郁和素质、压力、环境因素的关系及其整合模型研究

As a kind of mood, depression is one of the emotions which people experienced usually. Depressive disorder is one of the common mental diseases. There are about 100 million people in the world be disturbed by depression every year. So it is long history that depression is investigated widely in medicine, psychology, and sociology. There are many theorial problems remain to be solved. Viewed from latest vocuments, the development of depression theory is tending to become more complicated. Most of the prior depression theory focused on relation between one factor and depression. Because depressed individuls have various characteristics and factors that cause depression are different, and each factor can explain only part of depression variance, these prior depression theories are defected. As the knowledge about depression accumulated, the view that depression be caused by multifactor is clearer. There is tendency to integrate these cooperational factor into a model while developing a depression theory. In the present study, depression status of 1625 middle school students from junior 1 to senior 3 are measured using Depression Scale of Middle-school Student which is developed by ourselves. From approach of depressive mood, the present study explored depressive diathesis including attributional style, personality, coping style, and self. The relation among depressive diathesis, stress and depression is analysed. The relation between depression and school life adaptation, depression and cohesion, adaptation in family are also analysed from environmental view. At last, relation among environment, stress, depressive diathesis is examined by using covariance structure modelling. Synthesizing the results from the present study, the following conclusions were drawn: (1) There is grade-characteristics in development of depression in middle school students. Depression degree increased with grade. The main reason may be that the stress middle-school students experience increase and self-acceptance decrease with grade; (2) High depressive diathesis is different from low depressive diathesis. the features of high depressive diathesis are that attributing failure to ability or background, low capacity for status, low sociability, low independence, low self-blame, more illusion. The features of low depressive diathesis are that not attributing failure to ability or background, high capacity for status, high sociability, high independence, high self-acceptance, while facing difficulties, using problem-resolving coping strategy, less self-blame, less illusion. Individuals who have high depressive diathesis showed serious depression, and individuals who have low depressive diathesis showed light depression; (3) Depressive diathesis had accumulative effect on depression. More low depressive diathesis, more light is depression. More high depressive diathesis, more serious is depression; (4) Depressive diathesis can predict present depression and future depression. Predicting present depression is more effective than predicting future depression; (5) Individual who has different depressive diathesis experiences different level of stress. Higher the depressive diathesis individual has, higher stress he will experience. Lower the depressive diathesis individual has, lower stress will he experience; (6) There is correlation between life event pressure and depression. Life event pressure can predict a part of variance of depression. Life event pressure has accumulative effect on depression. More life event and higher life event pressure, more serious depression individual will experience; (7) There exits high correlation between depression and school life adaptation which can predict depression; (8) There is high correlative relation between depression and cohesion, adaptation in family which can predict depression; and (9) Environment have more effect on diathesis than on stress. Diathesis has more effect on depression than stress does. The past depression can predict future depression. This study had enlarged the domain of depressive diathesis such as attributional style, personality, coping style, and self, which are analysed wholly. This study had also enriched the connotation of diathesis=stress theory. Above two aspects are theoretical significance of the study. This study provide a framework of mental health educational curriculum in high school and provide the guideline for prevention and cure of depression. It is the practical significance of this study.