Perceiving distance accurately by a directional process of integrating ground information

By itself, the absolute distance of an object cannot be accurately judged beyond 2-3 m (refs 1-3). Yet, when it is viewed with reference to a flat terrain, humans accurately judge the absolute distance of the object up to 20 m, an ability that is important for various actions. Here we provide evidence that this is accomplished by integrating local patches of ground information into a global surface reference frame. We first show that restricting an observer's visual field of view to the local ground area around the target leads to distance underestimation, indicating that a relatively wide expanse of the ground surface is required for accurate distance judgement. Second, as proof of surface integration, we show that even with the restricted view, the observer can accurately judge absolute distance by scanning local patches of the ground surface, bit by bit, from near to far, but not in the reverse direction. This finding also reveals that the surface integration process uses the near-ground-surface information as a foundation for surface representation, and extrapolation to the far ground surface around the target for accurate absolute distance computation.     

区域前兆台网的管理

简要介绍了广东前兆台网“十五“项目的部署情况。根据国家地震前兆台网中心的工作要求,制定了相应的区域前兆台网中心和台站的规章制度,对中心和台站进行规范化管理。该工作仍在不断改进和完善中,目的是要按质、按量、按时地提供前兆数据。     

Study on crustal, lithospheric and asthenospheric thickness beneath the Qinghai-Tibet Plateau and its adjacent areas

Based on the results of pure dispersions of Rayleigh wave tomography in the Qinghai-Tlbet Plateau and its adjacent areas, tsklng S wave velocities from previous linear inversion as the initial model, using the simulated annealing algorithm, a nonlinear simultaneous inversion has been carried out for S wave velocity and thickness of different layers, including the crust, the lithosphere and the asthenosphere. The results indicate： The crustal thickness shows strong correlation with geology structures sketched by the sutures and major faults. The crust is very thick in the Qinghal-Tibet Plateau, varying from 60 km to 80 kin. The Ilthospherlc thickness in the Qinghai-Tibet Plateau Is thinner （130-160 kin） than Its adjacent areas. And two blocks can be recognized, divided by an NNE strike boundary running between 90°E-92°E inside the plateau. Its asthenosphere is relatively thick, varies from 150 km to 230 kin, and the thickest area is located in the western Qiangtsng. India has a thinner crust （32-38 kin）, a thicker lithosphere of 190 km and a rather thin asthenosphere of only 60 kin. Sichuan and Tarlm basins have the crust thickness less than 50 kin. Their Iithospheres are thicker than the Qinghai-Tibet Plateau, and their asthenospheres are thinner. A discussion has been made on the character and formation mechanism of the typical crust-mantle transition zone in the western Qiangtsng block.     

陕西长青自然保护区春季大熊猫取食微生境特征研究

通过对陕西长青自然保护区春末熊猫取食点7条样线36个样方的调查,对收集的22种生态因子进行频次分析,并将所有数据数字化后使用SPSS13.0软件进行主成分分析,得出大熊猫对取食点的微生境选择特点:坡度平缓;有少量乔木或大块石头;灌木密度适中,合0.1～0.6株/m2;距离水源地100m以内,靠近兽径;隐蔽度高,能见距离低于10m;竹子粗细合适,大部分竹子离地1m高处直径在10～14mm的阳坡或半阴半阳坡竹林地带。影响大熊猫对取食点的选择的主要因素为食物质量、综合隐蔽条件、穿行便利度及卧穴3类。     

基于显微聚焦的磨头表面测量与三维重构

为定量分析磨头表面磨粒形状、尺寸和分布状态,提出一种基于显微聚焦原理的表面测量与重构方法。首先给出了根据显微聚焦原理的定焦准平面测量和三维重构策略。然后针对测量策略中关键的聚焦或离焦程度分析,推导构建了背景差、灰度差和梯度差相结合的聚焦锐度函数。并采用正态高斯插值方法解决了图像离散采集存在错失最佳聚焦位置或焦准平面的问题,给出了任意像素位置对应点的空间坐标。最后通过电子金相显微镜上进行的磨头表面图像采集和三维重构实验表明,该方法重构表面磨粒的形状、尺寸、分布均与实际磨头基本一致,磨粒最大特征尺寸误差可控制在2 μm以内,最大分布误差在3 μm以内,具有较好的准确性和可靠性。     

挠性转子动不平衡量的极大似然估计

本文提出利用模态参数识别技术进行挠性转子动平衡的方法。为了计及平衡过程中测试数据的误差,对动不平衡量采用极大似然估计。本文给出计算机模拟的几个实例以论证此种方法,并提出加速收敛的措施。计算结果表明此法效果是鸿意的。     

成膜助剂对核壳结构乳胶粒子成膜过程的影响

以核壳结构丙烯酸酯乳液为研究对象,采用扩散波光谱技术(diffusing-wave spectroscopy, DWS)对成膜助剂二丙二醇丁醚(DPNB)在乳液成膜过程的作用机理进行了研究。通过获取乳胶粒子在成膜过程中多级动态散射光的散斑干涉波动频率随时间的变化规律,确定DPNB在粒子相互排列阶段就开始起作用,且随着DPNB用量的增加,谱图由多峰变为双峰,最终呈现单峰;结合最低成膜温度(MFFT)、动态光散射(DLS)、原子力显微镜(AFM)等仪器分析发现,得到适用于本体系成膜助剂的最佳使用量为7%~8%（质量分数）,在该成膜助剂用量下粒子边界融合充分,从宏观上表现为连续漆膜。     

A SERS SPECTRA STUDY OF N-HETEROCYCLE INHIBITOR ON NON-SERS ACTIVE METAL IRON

This paper presents the SERS spectra of quinoline adsorbed on iron deposited on the silver electrode by the cathodic reaction of ferrousion. Adsorption and inhibition mechanism of quinoline were discussed by means of the SERS spectra.     

基于Apache+PHP+MySQL框架的网络报名系统开发

以Apache+PHP+mySQL为框架,在Web Service基础上,为了处理繁琐的用户报名信息,开发一种B/S结构的等级考试报名系统。本文介绍了系统开发的设计思想及模式,基于Apache服务器的系统构架设计;阐述了系统中用户信息的注册、查询、修改和管理等关键技术,实现了计算机等级考试报名的信息化和网络化。