尼罗罗非鱼(Tilapia nilotica)视觉运动反应的特点

本文研究了不同体长组尼罗罗非鱼幼鱼的视觉运动反应,并着重探讨了该种鱼在不同环境照度和屏幕转速下的反应特点,结果表明。该种幼鱼在10~(-5)-10~4~4lx照度下具有典型的视觉运动反应,并限着环境照度提高而增强,但随屏幕转速加快和体长的增长而减弱,个体和群体反应无明显差别。     

鲤鱼幼鱼在色光场中的视觉运动反应

研究了鲤鱼幼鱼在6种波长单色光场中的视觉运动反应的速度和时间两方面特性。在可见光谱中间波段单色光场中鱼反应较强,520 nm 绿色光场中跟随速度最快,暗视等亮度条件下 453 nm 蓝色光场中反应潜伏期最短,时间跟随率最高,但在明视等亮度条件下反应的时间特性不随光波长而变化。提高各波长光强度,潜伏期均缩短,时间跟随率均提高,上述特点与水中光谱能量分布及鱼眼光潜光效率有关。     

基于色度学的人眼彩色探测特性分析

相对于黑白视觉的亮度对比度的探测特性，分析了人眼视觉对彩色条纹的探测特性．在分析前人研究和实验的基础上，根据色度学原理，研究了前人实验中所采用的红绿条纹和黄蓝条纹的亮度、主波长和色纯度变化．提出了用亮度对比度、主波长对比度和色纯度对比度描述人眼彩色对比度探测特性的概念，可初步定性解释部分前人的彩色视觉实验结果．为进一步评价彩色图像质量提供了一种可能的技术途径．     

基于机器视觉的LED大屏亮度一致性检测与矫正

LED屏幕在现代交通中应用十分广泛,但是随着使用时间的增加,每个LED灯的亮度会出现不同程度的衰减,从而导致整个LED屏幕整体亮度不一致.提出一种基于机器视觉技术的屏幕亮度不一致性的检测和矫正方法.实验中通过对采集的LED图片进行仿射变换、色彩空间转换和形态学滤波、单灯珠定位与亮度提取等操作,可以获得所有LED灯珠的相对位置信息与近似呈现正态分布的亮度信息.根据人眼对亮度的敏感程度选取出最佳亮度值,将高亮度灯珠抑制到最佳亮度值,实现对LED大屏亮度一致性的矫正.通过对72×384的LED屏幕测试,不仅能够100%获得所有LED灯珠的亮度信息、位置信息,而且系统的运行速度和稳定性明显优于已有测量方案.     

鲑点石斑鱼,大弹涂鱼在不同光照强度下网膜运动反应的比较

鲑点石斑鱼(■ )具网膜运动反应。引起鲑点石斑鱼视网膜黑色素颗粒明显迁移的照度阀值上限为10~(-1)1×,而视链细胞明显伸缩的照度阀值上限为10~(-2)l_x以上。大弹涂鱼(Boleophthalmus peetinirostris)视网膜在完全暗适应及不同照度(10~(-2)、10~(-1)、10~0、10~1、10~2、10~3lx)下明适应后,并不产生网膜运动反应,推测系通过瞳孔运动反应调节明暗视。     

量热法测定二氧化二聚环戊二烯合成反应的热效应与动力学参数

利用量热计测定了由二聚环戊二烯和过氧醋酸(各以B、A表示)合成二氧化二聚环戊二烯的反应热效应,同时测定了瞬时放热速度,得到热动力学曲线,经过数学处理,求得了该反应的反应级数、活化能和频率因子。二氧化二聚环戊二烯合成反应的速度为r_A=1.44×10~7exp(-49.8×10~3J/RT)C_A~(0.824)C_B~(1.69)。用所得的动力学方程式预测反应速度以及反应物浓度变化,并与实验值进行了比较,结果良好。     

鸟类离顶盖通路的结构和电生理特性

离顶盖通路是鸟类主要的视觉通路之一, 由视网膜、视顶盖、圆核和外纹体组成. 各结构之间具有区域性的对应投射;通路中的神经细胞具有不同的感受野特性, 对不同形式的刺激呈现出不同的反应模式. 参与物体运动方向和物体的朝向分析、运动物体的速度检测、颜色和物体轮廓处理、图象-背景识别、视觉指导定位、捕食和逃避反应等.离顶盖通路侧重于加工关于目标运动的特殊视觉信号,而对自身引起的视觉运动不敏感.     

有机硅——聚氨酯嵌段共聚物反应动力学研究

对端异氰酸酯基聚氨酯予聚体(PEU)分别与1,3—二(3—羟丙基)四甲基二硅氧烷(Ⅰ)和α,ω—二羟基聚二甲基硅氧烷齐聚物(Ⅱ)在THF/DOX中的反应动力学进行了研究。结果表明,反应程度直至6O％,这两种反应均为二级反应。PEU与Ⅰ对应于65、56和47℃三个温度的反应速度常数分别为6.3×10~(-2)、3.8×10~(-2)和1.68×10~(-2)1/mol·min, PEU与Ⅰ的反应活化能及频率因子分别为66,14kJ/mol和1.l×10~9;PEU与Ⅱ对应于65、56和47℃三个温度的反应速度常数分别为9.9×10~(-3)、2.4×10~(-3)和1.76×10~(-3)1/mol·min,PEU与Ⅱ的反应活化能及频率因子分别为85.81kJ/mol和1.43×10~(11)。     

计算机视觉系统的二步法颜色恒常性

理论研究表明 ,三色视觉系统在单视野条件下 ,三维颜色恒常性的计算问题只有在一些约束下才能解决。约束选择的合理与否和后续的任务密切相关。针对不同环境光照条件下的人体肤色分割的具体任务 ,提出了一个新的关于三色系统颜色恒常性问题的物理模型 :1 )将视觉系统所获得的原始信息分裂为亮度信息和颜色信息。 2 )将传统的颜色恒常性问题分解为基于亮度的亮度恒常性和基于颜色信息的颜色恒常性 ,并用二维描述子描述等亮度彩色图像中物理表面的颜色特征。该描述子具有颜色恒常的特性。基于颜色的图像分割实验结果表明 ,二步法颜色恒常性技术是一种非常有效的方法。     

人眼的色适应对荧光屏显示色貌的影响

用双眼不对称匹配法研究人眼在观察计算机视觉显示终端彩色监视器荧光屏时,视觉系统对复杂背景的色适应及其对荧光屏显示色貌的影响.研究结果表明,背景的平均颜色和目标与背景的色差及亮度差对色适应引起的色位移有显著的影响.在定量估计人眼对复杂背景的色适应引起的色貌变化时,可以把视觉系统看作一个积分响应灵敏度取决于背景颜色和亮度平均值的信息处理系统。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that