Variations and possible source of potentially available phosphorus in a Chinese shallow eutrophic lake

Surface, overlying, and interstitial waters were collected at monthly intervals at three experimental stations in a shallow Chinese eutrophic lake (Lake Donghu) to assess the occurrence, distribution, and status of UV-sensitive phosphorus compounds (UVSP) and phosphatase hydrolyzable phosphorus (PHP), coupled with kinetics of alkaline phosphatase activity (APA). Orthophosphate (o-P) concentrations were generally the highest at Station 1, where chlorophyll a (chl a) was a function of o-P at temporal scale. The V-max/K-m of APA obtained by Michaelis-Menten approach paralleled the chlorophyll data at two stations. These facts imply that the development of phytoplankton may be attributed to APA induced by PHP. The potentially available UVSP and PHP peaked in interstitial, overlying, and surface water simultaneously sometimes in 1995 to 1996 and 1997 to 1999. It is postulated that they may arise from the bottom. UVSP peaked in interstitial water at the 12-16 cm layers in sediment cores. Moreover, in interstitial water, UV irradiation resulted in an elevated o-P concentration and decreased APA in a timeseries analysis. Therefore, the mechanism that APA involved in the process of photorelease of o-P was not demonstrated. UVSP is most likely a functional group of labile phosphorus distinct from the enzymatic substrate in this shallow eutrophic lake.

Capillary array electrophoresis with confocal fluorescence rotary scanner

A capillary array electrophoresis system with rotary corifocal fluorescence scanner was reported. High speed direct current rotary motor combined with a rotary encoder and the reflection mirror has been designed to direct exactly the excitation laser beam. to the array of capillaries, which are symmetrically distributed around the motor. The rotary encoder is introduced to accurately orient the position of each capillary and its output signal triggers the data acquiring system to record. the fluorescence signal corresponding to each capillary. Separations of several amino acids are demonstrated by eight-channel capillary array electrophoresis built by ourselves.

高性能全流水线可控参数JPEG-LS编码器实现

提出了一种高性能的JPEG-LS无损/近无损图像压缩算法VLSI实现结构.通过对JPEG-LS算法瓶颈的分析,针对算法中不利于流水线实现的场景缓存部分,采用了一种信号量集机制避免流水线等待.全流水线结构保证了算法实现可以满足高速图像传感器系统的吞吐量需求.同时通过高度参数化的设计,系统可以动态调整和优化算法参数,使压缩效果和效率适应不同的运行环境.算法在FPGA平台通过验证,并得到了接近甚至超过其他A-SIC实现的性能.

电机转速自适应测量方法及其在DSP上的实现

本文在分析几种常用的基于编码器测速方法的基础上,提出了一种高性能的自适应速度测量方法。该方法选择一个可变的时间周期和编码器脉冲数来测量单位时间内的编码器脉冲数,再通过简单的计算得到转速的测量值。数字信号处理器(DSP)芯片集成有正交脉冲编码电路,并且数据处理速度快,实时性强。本文中提出的方法在电机控制专用DSP芯片TMS320 LF2407A上进行了实现。实验研究表明,可以在提高低速时的测速准确度的同时,提高系统的响应时间。该方法已经在自主研发的全数字伺服驱动系统中得到了成功应用。

一种FPGA的嵌入式可重构机器人控制系统

提出一种基于FPGA的可重构嵌入式微处理器控制系统.在FPGA中嵌入两个NiosⅡ软核,用VHDL语言编写用户自定义组件.在一个由NiosⅡ软核组成的处理器上实现PWM信号生成、编码器信号处理以及多电机同步伺服运算等,在另一个处理器实现机器人任务管理.该控制系统针对微小型爬壁机器人的控制系统设计,不仅具有良好的实时多任务处理能力,而且具有可重构的特点,因而可应用于一类微小型机器人控制系统以提高其设计的灵活性.

基于多传感器的可变形机器人自主控制方法研究

将GPS、电子罗盘、倾角仪、码盘传感器等应用到可变形机器人自主运动控制中.针对可变形机器人自身结构特点,提出了一种基于多传感器信息融合的可变形机器人在野外环境中自主控制的方法.该方法主要实现了在非结构环境中机器人的自主变形、自主避障和自主导航定位等功能.实验验证了该方法的有效性.

无锁存功能脉冲计数器的改进读取方法

在电机伺服控制系统中,需要一个脉冲计数器对电机码盘输出的脉冲进行计数。但是如果脉冲计数器没有数据锁存功能,单片机读出的数值可能不准确,进而影响伺服控制系统的性能。针对没有锁存功能的脉冲计数器,提出了一种改进的读取方法,有效的避免了在读取过程中由于计数器进位或借位造成的读数偏差。

无锁存功能脉冲计数器的改进读取方法

在电机伺服控制系统中,需要一个脉冲计数器对电机码盘输出的脉冲进行计数。单片机根据脉冲的个数和电机旋转方向计算出电机的转角,进而实现对电机的伺服控制。如果脉冲计数器没有数据锁存功能,且单片机读取数值时,脉冲计数器恰好发生了进位或者借位,则读取的数值可能不准确,进而影响伺服控制系统的性能。针对没有锁存功能的脉冲计数器,提出了一种改进的读取方法,有效地避免了在读取过程中由于计数器进位或借位造成的读数偏差。

神经网络用于多模式分类

本文叙述一种改进型HAMMING网在印刷汉字文本识别实用系统中作为粗分类的应用.给出了以3755印刷汉字为多模式分类对象的神经网络分类器的结构及其相应的算法.该方法在微型机上用软件仿真得以实现.取得令人满意的结果.

清江水库茅坪滑坡监测与发展趋势预测

茅坪滑坡位于清江隔河岩水库上游北岸、距水库坝址66km处。是隔河岩水库库区中最大的基岩古滑坡体，其体积约2．35×10^7m^3。自1993年4月10日水库下闸蓄水以来，该滑坡一直产生缓慢变形。滑坡发生整体失稳，则会截断清江，形成“库中坝”，并造成灾难性的恶果。为此，全面掌握该滑坡的变化发展趋势对今后进行防治决策具有十分重要的意义。掌握滑坡发展变化的关键就是对该滑坡进行现场监测。课题组多次现场踏勘，在原有8个地表监测点的基础上增设了29个监测点，使其布置更科学、合理；并对该滑坡进行了1个水文年的监测工作，获得了大量的笫一手资料，认为该滑坡正处于位移加速阶段。通过现场监测，不仅对滑坡体的现状有了新的认识。同时，预测了茅坪滑坡的变化发展趋势，可以为制定该滑坡的防治预案提供参考。

Evolution-induced catastrophe and its predictability

Both earthquake prediction and failure prediction of disordered brittle media are difficult and complicated problems and they might have something in common. In order to search for clues for earthquake prediction, the common features of failure in a simple nonlinear dynamical model resembling disordered brittle media are examined. It is found that the failure manifests evolution-induced catastrophe (EIC), i.e., the abrupt transition from globally stable (GS) accumulation of damage to catastrophic failure. A distinct feature is the significant uncertainty of catastrophe, called sample-specificity. Consequently, it is impossible to make a deterministic prediction macroscopically. This is similar to the question of predictability of earthquakes. However, our model shows that strong stress fluctuations may be an immediate precursor of catastrophic failure statistically. This might provide clues for earthquake forecasting.

Space experimental device on Marangoni drop migrations of large Reynolds numbers

The space experimental device for testing the Marangoni drop migrations has been discussed in the present paper. The experiment is one of the spaceship projects of China. In comparison with similar devices, it has the ability of completing all the scientific experiments by both auto controlling and telescience methods. It not only can perform drop migration experiments of large Reynolds numbers but also has an equi-thick interferential system.

Critical Sensitivity and Trans-Scale Fluctuations in Catastrophic Rupture

Rupture in the heterogeneous crust appears to be a catastrophe transition. Catastrophic rupture sensitively depends on the details of heterogeneity and stress transfer on multiple scales. These are difficult to identify and deal with. As a result, the threshold of earthquake-like rupture presents uncertainty. This may be the root of the difficulty of earthquake prediction. Based on a coupled pattern mapping model, we represent critical sensitivity and trans-scale fluctuations associated with catastrophic rupture. Critical sensitivity means that a system may become significantly sensitive near catastrophe transition. Trans-scale fluctuations mean that the level of stress fluctuations increases strongly and the spatial scale of stress and damage fluctuations evolves from the mesoscopic heterogeneity scale to the macroscopic scale as the catastrophe regime is approached. The underlying mechanism behind critical sensitivity and trans-scale fluctuations is the coupling effect between heterogeneity and dynamical nonlinearity. Such features may provide clues for prediction of catastrophic rupture, like material failure and great earthquakes. Critical sensitivity may be the physical mechanism underlying a promising earthquake forecasting method, the load-unload response ratio (LURR).