跨漂时间对空气自动监测站二氧化硫准确度的影响

利用国家环保部标准样品研究所已知标准气体,选取绵阳市的三个城市空气自动监测站进行二氧化硫实验分析。结果表明,EC9850B二氧化硫监测仪跨漂后仪器响应快速升至最高值然后逐渐升高趋向稳定,通过连续跨漂的监测数据与已知标准气体的符合性确定仪器跨漂35min后基本稳定,并在标准气体中值附近波动,据此开始记录数据,准确度高,数据有效且质量可控。     

Preserving Population Allele Frequencies in Ex Situ Conservation Programs

Abstract: Optimization of contributions of parents to progeny by minimizing the average coancestry of the progeny is an effective strategy for maintaining genetic diversity in ex situ conservation programs, but its application on the basis of molecular markers has the negative collateral effect of homogenizing the allelic frequencies at each locus. Because one of the objectives of a conservation program is to preserve the genetic composition of the original endangered population, we devised a method in which markers are used to maintain the allele frequency distribution at each locus as closely as possible to that of the native population. Contributions of parents were obtained so as to minimize changes in allele frequency for a set of molecular markers in a population of reduced size. We used computer simulations, under a range of scenarios, to assess the effectiveness of the method in comparison with methods in which contributions of minimum coancestry are sought, either making use of molecular markers or genealogical information. Our simulations indicated that the proposed method effectively maintained the original distribution of allele frequencies, particularly under strong linkage, and maintained acceptable levels of genetic diversity in the population. Nevertheless, contributions of minimum coancestry determined from pedigree information but ignoring the genealogy previous to the conservation program, was the most effective method for maintaining allelic frequencies in realistic situations.     

钉螺的水力输送

血吸虫病是中国和其它许多国家的一种地方性流行病,钉螺是血吸虫唯一的中国宿主,钉螺运移是血吸虫病蔓延的主要原因。研究钉螺在河道中的输移规律,对控制血吸虫病流行十分重要。野外观测和实验研究表明、钉螺输移、尤其是大量钉螺的远距离输移,是借助于水流完成的,河流中钉螺的水力输送主要是以悬移质和移质的形式,以及被漂的挟带。     

STREAM TYPES IN THE DES MOINES RIVER BASIN1

Stream tributaries in the Des Moines River basin have been classified according to the glacial terrain through which they flow. Three stream types were categorized as follows: (1) streams that flow entirely on Wisconsin drift, (2) streams that flow entirely on Kansan drift, and (3) streams that have their headwaters located on new drift but have their lower reaches flowing on older drift. Selected channel and valley characteristics were measured and used to verify the stream type classification. Five variables were chosen for use in a multiple linear discriminatory analysis, which is a statistical technique developed for the purpose of classifying observations into one of several categories which have been predetermined. The streams in each group were verified with the exception of three anomalies based on the probability associated with the largest linear discriminant function. The rationale for the three anomalous streams is not easily determined. But, they are considered to be associated with pre-glacial drainage or at least pre-Wisconsin age drainage. Otherwise, the analysis shows that the major channels and valleys in the Des Moines River basin tend to reflect the glaciated upland surface.     

可适应环境温度变化的GaAs霍尔传感器及其放大器的温漂补偿方法

研究了ＧａＡｓ霍尔传感器及其放大器的温漂的相关因素，提出了整体补偿思想，经实验验证，其最大相对误差小于０．１％。     

Empirical Research on Factors Influencing Level of Environmental Protection Information Disclosure in Annual Reports by Listed Companies

Taking 248 A-share manufacturing listed companies in 2006 Shanghai Stock Exchange as example, using ＂index method＂ to measure level of environmental protection information disclosure, this paper examines the factors influencing level of environmental protection information disclosure. The findings show that the disclosure level has improved, but the overall level is still low and unable to satisfy information users; there is positive correlation between corporate size, industry type, accounting firm＇s type and corporate environmental disclosure index. The companies of large scale and heavy pollution and those audited by international ＂Big 4＂ and domestic ＂Big 10＂ accounting firms have a high level of environmental disclosure, while the profitability and financial leverage has no impact on the disclosure level. Finally some suggestions are put forward to establish environmental information disclosure system in China.     

我国道路交通信号控制机认证框架体系探讨

针对目前我国道路交通信号控制机产品存在的质量问题,对信号机生产企业进行深入调研,详细分析信号机发展现状、国内外产品认证制度及信号机强制检测制度等,并结合我国交通信号机产品自身的特点和实际,参考国外产品认证模式、认证流程,提出我国信号机产品以型式试验、初始工厂检查和获证后监督为模式的认证框架体系。信号机产品质量认证框架体系的建立,对提高产品质量,规范行业生产,将发挥积极的促进作用,同时也为我国交通安全产品的质量控制提供了新思路。     

Importance of dispersal routes that minimize open‐ocean movement to the genetic structure of island populations

Islands present a unique scenario in conservation biology, offering refuge yet imposing limitations on insular populations. The Kimberley region of northwestern Australia has more than 2500 islands that have recently come into focus as substantial conservation resources. It is therefore of great interest for managers to understand the driving forces of genetic structure of species within these island archipelagos. We used the ubiquitous bar‐shouldered skink (Ctenotus inornatus) as a model species to represent the influence of landscape factors on genetic structure across the Kimberley islands. On 41 islands and 4 mainland locations in a remote area of Australia, we genotyped individuals across 18 nuclear (microsatellite) markers. Measures of genetic differentiation and diversity were used in two complementary analyses. We used circuit theory and Mantel tests to examine the influence of the landscape matrix on population connectivity and linear regression and model selection based on Akaike's information criterion to investigate landscape controls on genetic diversity. Genetic differentiation between islands was best predicted with circuit‐theory models that accounted for the large difference in resistance to dispersal between land and ocean. In contrast, straight‐line distances were unrelated to either resistance distances or genetic differentiation. Instead, connectivity was determined by island‐hopping routes that allow organisms to minimize the distance of difficult ocean passages. Island populations of C. inornatus retained varying degrees of genetic diversity (N_A = 1.83 – 7.39), but it was greatest on islands closer to the mainland, in terms of resistance‐distance units. In contrast, genetic diversity was unrelated to island size. Our results highlight the potential for islands to contribute to both theoretical and applied conservation, provide strong evidence of the driving forces of population structure within undisturbed landscapes, and identify the islands most valuable for conservation based on their contributions to gene flow and genetic diversity.     

Fish forewarning of comprehensive toxicity in water environment based on Bayesian sequential method

Environmental impact of pollutants can be analyzed effectively by acquiring fish behavioral signals in water with biological behavior sensors. However, a variety of factors, such as the complexity of biological organisms themselves, the device error and the environmental noise, may compromise the accuracy and timeliness of model predictions. The current methods lack prior knowledge about the fish behavioral signals corresponding to characteristic pollutants, and in the event of a pollutant invasion, the fish behavioral signals are poorly discriminated. Therefore, we propose a novel method based on Bayesian sequential, which utilizes multi-channel prior knowledge to calculate the outlier sequence based on wavelet feature followed by calculating the anomaly probability of observed values. Furthermore, the relationship between the anomaly probability and toxicity is analyzed in order to achieve forewarning effectively. At last, our algorithm for fish toxicity detection is verified by integrating the data on laboratory acceptance of characteristic pollutants. The results show that only one false positive occurred in the six experiments, the present algorithm is effective in suppressing false positives and negatives, which increases the reliability of toxicity detections, and thereby has certain applicability and universality in engineering applications.     

基于无线通讯技术的起重机抬吊同步控制系统改进

本文介绍了基于无线工业以太网通讯的可编程同步检测系统结构和设计方法、同步功能的检测原理及实现方法、调试和操作方法。通过在控制系统中加入信号反馈,将两台起重机的控制执行器信号和末端机械传动的差异值进行反馈跟踪,组成具有反馈功能的抬吊控制系统,在监測到执行器异步或末端传动异步现象时及时控制两车同步停止,从而避免吊物坠落等吊运事故的发生。