Nine pathogenic fungi of waterhyacinth isolated in China

The native pathogens of waterhyacinth in China, were studied and compared on pathogenicity by Koch＇s postulate. Nine pathogenic fungi, YBH, YBB, YB, YYX, YY, YBA1, YBA2, YBA3 and YYB12, were isolated from diseased waterhyacinth plants, and collected from Zhejiang province and Shanghai. According to cultural characteristics, the nine isolates were preliminarily identified. Isolates YBH and YBB were Collectotrichum sp.; YB, YYX and YY were placed in fungi imperfecti; the isolates YBA1, YBA2, YBA3 and YYB12 were Alternaria sp. The isolate YBH was the highly virulent with a disease index （DI） of 65.28% after one month inoculation. The isolate YBA3 was equily virulent, with the disease index of 6770 after 7 day introduction. These two pathogens appear to have the potential as biocontrol agents and they deserve further study.     

The linear position tracking servo system using a linear voice-coil motor

More and more linear servo systems have been used in servo applications. Direct drive technology can greatly increase the bandwidth and the tracking accuracy. A position servo-system based on linear voice-coil motor was designed for one linear oscillation movement application. Besides the conventional position, speed and current control loops, the speed and acceleration feed-forward control of command position signal were also used. The experimental test proved the correctness of the design, and the system can track the given periodic sinnsoid position command signal of 15Hz with high accuracy. The linear voice-coil motor is very suitable for short stroke position tracking application with high dynamic response.     

基于晶闸管串联的高压电机软起动

介绍了基于晶闸管串联的高压异步电动机软启动器,并推导出串联晶闸管的数学模型,应用该等效模型对高压电动机的软启动过程进行了仿真,为分析和设计基于晶闸管串联的高压异步电动机软启动器提供了一个有力的工具.     

Identification of vehicle sensor locations for link-based network traffic applications

Information on link flows in a vehicular traffic network is critical for developing long-term planning and/or short-term operational management strategies. In the literature, most studies to develop such strategies typically assume the availability of measured link traffic information on all network links, either through manual survey or advanced traffic sensor technologies. In practical applications, the assumption of installed sensors on all links is generally unrealistic due to budgetary constraints. It motivates the need to estimate flows on all links of a traffic network based on the measurement of link flows on a subset of links with suitably equipped sensors. This study, addressed from a budgetary planning perspective, seeks to identify the smallest subset of links in a network on which to locate sensors that enables the accurate estimation of traffic flows on all links of the network under steady-state conditions. Here, steady-state implies that the path flows are static. A “basis link” method is proposed to determine the locations of vehicle sensors, by using the link-path incidence matrix to express the network structure and then identifying its “basis” in a matrix algebra context. The theoretical background and mathematical properties of the proposed method are elaborated. The approach is useful for deploying long-term planning and link-based applications in traffic networks.     

Weathering sources in the Gaoping (Kaoping) river catchments, southwestern Taiwan: Insights from major elements, Sr isotopes, and rare earth elements

This study aims at quantifying the distribution of REEs associated with chemical weathering processes, as well as investigating weathering mechanisms and source regions of the Gaoping (formerly spelled Kaoping) River (KPR) catchment basin located at southwestern Taiwan. Spatial distributions of dissolved rare earth elements, as well as major ions, trace elements and Sr isotopes in river waters were analyzed using SF-ICPMS and TIMS. Our results indicate that REE concentrations and patterns predominantly reflect sources and intensity of chemical weathering along the river's catchment. Most specimens have high Na/Cl (4.2–30.1 mol/mol) ratios due to strong weathering intensity in the upper stream. The Na/Ca and Mg/Ca ratios suggest the main contribution is from weathering of silicates and carbonates. Total concentrations of REEs are rather low in the Gaoping (Kaoping) River (6.7–15.4 ng/L), possibly influenced by adsorption onto suspended particles. The REE patterns also reflect source heterogeneity in weathering minerals with large LREE depletion and MREE enrichment. Europium is strongly enriched in the Gaoping (Kaoping) River water, as a result of its preferential dissolution from suspended particles. Unique Gadolinium anomaly is present in all specimens, likely related to contamination due to clinic waste disposal. Small fractionations of LREE/HREE have occurred along the KPR and can be used as a distinct signature for source identification. The main stream samples exhibit a relatively wide range of ⁸⁷Sr/⁸⁶Sr, 0.71265–0.71360, with a systematical increase downstream due to source mixing of dissolved basalt (less radiogenic) and sedimentary rocks. Each tributary shows distinct Sr isotope signatures due to different rock types and ages. These isotopic and elemental compositions provide important information on weathering source and erosion budget.     

道路标志自动分类方法

为了对道路标志图像进行自动分类,通过图像颜色空间变换,将图像的RGB量值转换为H(色度)S(饱和度)I(亮度)量值,采用Sobel算子进行道路标志图像的边缘检测,利用行扫描法进行区域填充,以获取二值化的道路标志图像区域,提取道路标志二值化图像的不变矩与形状参数作为图像特征值,设计BP神经网络道路标志图像几何形状分类器,以道路标志图像的H、I为特征值,设计了欧式距离分类器,实现道路标志背景颜色的识别。融合道路标志图像几何形状和背景颜色的识别算法,并利用道路标志的分类知识和自动分类方法,能有效实现道路标志图像的自动识别。     

船舶舱室周期加筋板隔声性能数值分析

利用数值方法研究船舶舱室典型加筋壁板的隔声性能,将舱室壁板简化为单向周期加筋板进行考察,建立单向周期加筋板的有限元(FE)和统计能量(SEA)混合分析模型,以散射声场作为激励计算其隔声量。使用正交试验的方法,抽样计算不同结构参数的单向周期加筋板的隔声量,取其计算结果在倍频程中心频率处的平均值作为考虑吻合效应的船舶舱室典型加筋舱壁的隔声量,为总体设计阶段的舱室噪声预报提供更有力的数据支撑。     

上海轨道交通网络运营设备维护管理系统设计概述

从上海轨道交通全网络安全运营的实际需求出发,概述了网络化运营情况下设备维护管理系统的功能特点,详细分析和探讨了从城市轨道交通设备维护系统的应用及网络和软件架构的设计特点。     

Maneuvers of motorcycles in queues at signalized intersections

The maneuvering models of motorcycles in previous studies often considered motorcycles' traveling in terms of movements in a physical static lane and not in terms of dynamic virtual lane‐based movements. For that reason, these models are not able to imitate motorcyclists' behavior well. This paper proposes a maneuverability model framework for motorcycles in queues at signalized intersections with considering the dynamic motorcycle's lane. The model includes (i) a dynamic motorcycle's lane to identify the current, left, and right lanes of the subject motorcycle, (ii) a threshold distance to determine when a motorcyclist starts to consider maneuvering, (iii) a lane selection model to identify the lane preferred by a motorcyclist, and (iv) a gap acceptance model to describe whether or not the lead and lag gaps are acceptable for maneuvering. The model framework captures the variation across the motorcyclist population and over time observations. The models were applied to Hanoi and Hochiminh city, Vietnam, based on microscopic data collected from video images. All of the parameters were estimated using the maximum likelihood method with the statistical estimation software GAUSS. The results show that 77.88% of the observed maneuvers – either staying in the current lane or turning left or right – could be modeled correctly by the proposed models. Copyright © 2010 John Wiley & Sons, Ltd.     

用旁压剪切模量推算砂性土地基的变形模量

本文分析了砂性土地基变形模量和旁压测试结果凡/孙之间的关系,提出了a二 j(E-伽)两个连续渐变的关系式,并用15个测点资料、6个Cpq,换井资料和Menard 的阶梯式变化。一五./孙关系作了对比。