硝基苯类污染物还原分析的系统误差

硝基苯类项目分析过程中,经过锌粉还原、过滤等重要环节．能吸附分析组分,引起分析结果偏低．通过理论计算和分析标样对比．找出硝基苯类还原偶氮比色法主要的系统误差。     

D-P准则的性能评估及其在强度折减分析中的适用性研究

将D-P准则对M-C准则的近似视为连续函数逼近问题,据此建立了最佳平方逼近的误差解析表达式,并提出了一个最佳D-P准则。同时,利用该误差表达式分析了各种常用D-P准则对于M-C准则的最佳平方逼近误差。分析结果表明,在所有的D-P准则中,采用大外接圆的D-P准则误差最大,等面积圆准则与本文所提出的最佳准则的误差相近,内切圆、小外接圆和中径圆的误差基本上处于同一水准。同时,通过利用强度折减分析方法对各准则的适用性作了进一步的研究,结果表明,在系统处于相对稳定状态时等面积准则和最佳准则与M-C准则具有较好的接近程度,但当系统将进入不稳定状态时M-C准则却与内切圆准则接近。     

灰色预测在平朔煤炭工业公司安全生产中的应用

利用灰色系统理论,建立了平朔煤炭工业公司事故伤亡率的GM(1,1)动态预测模型,并采用残差修正方法,提高了预测精度.对于该矿山有效地控制安全事故的发生,减少其造成的经济损失起到了重要的作用.     

从语言输入输出理论谈互动式课堂教学

通过对语言输入与输出理论以及互动式教学法的分析,作者认为把前者融入到后者之中来进行英语教学可取得更好的效果,还强调既要重视语言输入,又要强调语言的输出。     

Mapping Stream Habitats with a Global Positioning System: Accuracy,Precision, and Comparison with Traditional Methods

We tested the precision and accuracy of the Trimble GeoXT™ global positioning system (GPS) handheld receiver on point and area features and compared estimates of stream habitat dimensions (e.g., lengths and areas of riffles and pools) that were made in three different Oklahoma streams using the GPS receiver and a tape measure. The precision of differentially corrected GPS (DGPS) points was not affected by the number of GPS position fixes (i.e., geographic location estimates) averaged per DGPS point. Horizontal error of points ranged from 0.03 to 2.77 m and did not differ with the number of position fixes per point. The error of area measurements ranged from 0.1% to 110.1% but decreased as the area increased. Again, error was independent of the number of position fixes averaged per polygon corner. The estimates of habitat lengths, widths, and areas did not differ when measured using two methods of data collection (GPS and a tape measure), nor did the differences among methods change at three stream sites with contrasting morphologies. Measuring features with a GPS receiver was up to 3.3 times faster on average than using a tape measure, although signal interference from high streambanks or overhanging vegetation occasionally limited satellite signal availability and prolonged measurements with a GPS receiver. There were also no differences in precision of habitat dimensions when mapped using a continuous versus a position fix average GPS data collection method. Despite there being some disadvantages to using the GPS in stream habitat studies, measuring stream habitats with a GPS resulted in spatially referenced data that allowed the assessment of relative habitat position and changes in habitats over time, and was often faster than using a tape measure. For most spatial scales of interest, the precision and accuracy of DGPS data are adequate and have logistical advantages when compared to traditional methods of measurement.     

组织错误研究中存在问题的思考

组织错误研究是人误研究的新方向.在综述组织错误理论研究现状的基础上,论述了组织错误分析在理论和应用方面面临的4大问题,即:组织错误的定义及特征界定存在的问题,组织错误分类标准和方法存在的问题,组织错误的形成及演变机理以及组织错误评价、预测的技术方法,讨论了组织错误理论的发展趋势.     

A methodology to model causal relationships on offshore safety assessment focusing on human and organizational factors

INTRODUCTION: Focusing on people and organizations, this paper aims to contribute to offshore safety assessment by proposing a methodology to model causal relationships. METHOD: The methodology is proposed in a general sense that it will be capable of accommodating modeling of multiple risk factors considered in offshore operations and will have the ability to deal with different types of data that may come from different resources. Reason's "Swiss cheese" model is used to form a generic offshore safety assessment framework, and Bayesian Network (BN) is tailored to fit into the framework to construct a causal relationship model. The proposed framework uses a five-level-structure model to address latent failures within the causal sequence of events. The five levels include Root causes level, Trigger events level, Incidents level, Accidents level, and Consequences level. To analyze and model a specified offshore installation safety, a BN model was established following the guideline of the proposed five-level framework. A range of events was specified, and the related prior and conditional probabilities regarding the BN model were assigned based on the inherent characteristics of each event. RESULTS: This paper shows that Reason's "Swiss cheese" model and BN can be jointly used in offshore safety assessment. On the one hand, the five-level conceptual model is enhanced by BNs that are capable of providing graphical demonstration of inter-relationships as well as calculating numerical values of occurrence likelihood for each failure event. Bayesian inference mechanism also makes it possible to monitor how a safety situation changes when information flow travel forwards and backwards within the networks. On the other hand, BN modeling relies heavily on experts' personal experiences and is therefore highly domain specific. IMPACT ON INDUSTRY: "Swiss cheese" model is such a theoretic framework that it is based on solid behavioral theory and therefore can be used to provide industry with a roadmap for BN modeling and implications. A case study of the collision risk between a Floating Production, Storage and Offloading (FPSO) unit and authorized vessels caused by human and organizational factors (HOFs) during operations is used to illustrate an industrial application of the proposed methodology.     

高喷插芯组合桩极限承载力的灰色预测

高喷插芯组合桩(JPP)是一种新的桩型,具有承载力高、造价低等优点。许多工程单桩的静载荷试验只能加到两倍设计荷载,无法达到试桩的极限或破坏荷载,因此利用有限的实测数据比较准确地预测高喷插芯组合桩的极限承载力具有一定的现实意义。根据灰色理论,介绍了预测单桩竖向极限承载力的自调整非等步长GM(1,1)模型,讨论了三种不同的灰色模型在有限的实测数据条件下预测单桩极限承载力以及荷载—沉降关系的方法。通过对达到破坏和未达到破坏的工程实例的分析计算,证明三种模型的预测精度是令人满意的,其中等维新息模型预测精度最高。     

南京台数字水准仪往返观测误差分析

2006年初,省局给台站更换了DiNi12数字化水准仪,通过近几个月观测,观测数据测线观测数据上午往测观测高差偏大,下午返测观测高差偏小的现象,经分析认为:造成这种现象的主要原因与仪器受温度、太阳光照射影响有关.     

通信基站电磁辐射信访的情况分析和处理对策——以深圳市为例

根据深圳市近年来通信基站电磁辐射信访投诉的情况,结合马斯洛需求层次理论对通信基站信访投诉情况进行分析,将通信基站信访投诉抱怨等级划分为3类。再引入世界卫生组织关于电磁场风险沟通的建议和对电磁辐射风险沟通4要素的研究讨论,为3类通信基站信访投诉提供科学有效的处理对策。