A topic network analysis of the system turn in the environmental sciences

Scientometrics - The concept of Earth system science denotes a shift in the scientific discourse from disciplinary accounts of isolated components of the global environment towards the holistic and...     

Brominated flame retardants in Belgian home-produced eggs: levels and contamination sources

The extent and the sources of contamination with brominated flame retardants (BFRs), such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD), in home-produced eggs from free-foraging chicken of Belgian private owners were investigated. Various factors, such as seasonal variability, exposure of chickens through diet (kitchen waste) and soil, and elimination of BFRs through eggs and faeces were assessed. PBDEs were more important than HBCD in terms of concentrations and detection frequency. Concentrations of PBDEs and HBCD in Belgian home-produced eggs were relatively low and comparable with reported levels from other European countries and the US. The concentrations of PBDEs (sum of 13 congeners, including BDE 209) ranged between not detected and 32 ng/g lipid weight (lw), with medians of 3.0 and < 2.0 ng/g lw for the autumn 2006 and spring 2007 campaigns, respectively. When present, BDE 209 was the major PBDE congener (45% of sum PBDEs). When BDE 209 was not detected, the PBDE profile was composed of PentaBDE (BDE 99 and BDE 47), with, in some cases, higher contribution of OctaBDE (BDE 183 and BDE 153). HBCD was also detected (< 0.4 and 2.9 ng/g lw for the autumn 2006 and spring 2007 campaigns, respectively), but at lower detection frequency. The highest HBCD value was 62 ng/g lw. The similarity between profiles and seasonal variations in the concentrations of BFRs in soil and eggs indicate that soil is an important source, but not the sole source, for eggs laid by free-foraging chicken. The contamination of eggs with PBDEs and HBCD appears to be of low concern for public health and the contribution of eggs to the total daily intake of PBDEs appears to be limited (10% for chicken owners and 5% for the average Belgian consumer).     

激光跟踪仪在起落架收放型架研制中的应用

根据飞机起落架现代数字化工艺装备的研制需要,通过自主学习,掌握了激光跟踪仪测量技术及数字量传递法以及最大投影面原则、3-2-1原则等设计原则,顺利完成了某型飞机起落架收放型架研制。通过完成该型架安装检测,计量检测人员熟练掌握了激光测量技术在型架制造、检验中的应用技能,积累了飞机起落架型架研制经验。     

Progress and prospects of the human–robot collaboration

Recent technological advances in hardware design of the robotic platforms enabled the implementation of various control modalities for improved interactions with humans and unstructured environments. An important application area for the integration of robots with such advanced interaction capabilities is human–robot collaboration. This aspect represents high socio-economic impacts and maintains the sense of purpose of the involved people, as the robots do not completely replace the humans from the work process. The research community’s recent surge of interest in this area has been devoted to the implementation of various methodologies to achieve intuitive and seamless human–robot-environment interactions by incorporating the collaborative partners’ superior capabilities, e.g. human’s cognitive and robot’s physical power generation capacity. In fact, the main purpose of this paper is to review the state-of-the-art on intermediate human–robot interfaces (bi-directional), robot control modalities, system stability, benchmarking and relevant use cases, and to extend views on the required future developments in the realm of human–robot collaboration.     

Where does model-driven engineering help? Experiences from three industrial cases

There have been few experience reports from industry on how Model-Driven Engineering (MDE) is applied and what the benefits are. This paper summarizes the experiences of three large industrial participants in a European research project with the objective of developing techniques and tools for applying MDE on the development of large and complex software systems. The participants had varying degrees of previous experience with MDE. They found MDE to be particularly useful for providing abstractions of complex systems at multiple levels or from different viewpoints, for the development of domain-specific models that facilitate communication with non-technical experts, for the purposes of simulation and testing, and for the consumption of models for analysis, such as performance-related decision support and system design improvements. From the industrial perspective, a methodology is considered to be useful and cost-efficient if it is possible to reuse solutions in multiple projects or products. However, developing reusable solutions required extra effort and sometimes had a negative impact on the performance of tools. While the companies identified several benefits of MDE, merging different tools with one another in a seamless development environment required several transformations, which increased the required implementation effort and complexity. Additionally, user-friendliness of tools and the provision of features for managing models of complex systems were identified as crucial for a wider industrial adoption of MDE.     

城镇化过程中社会型中心镇的集约用地研究

城镇化是农村空间聚集整合并向城镇的转型。由于人口随经济要素分布的迁移．农村聚落出现人口聚集、重组与减少的空间分化．土地有向城市形态发展的集约利用趋势。然而。我国农村城镇化过程的村镇的土地利用却出现了极大的浪费。本文以平遥段村镇为例，采用实地调研、入户访谈的社会调查方法，在对数据进行空间分析的基础上剖析处于人口重组区域、以服务设施聚集人口的村镇在经济、社会发展和用地利用上的特征、问题与原因。针对“人口重组”发展社会活力的定位。提出产业结构调整、农地流转集中耕种与住房置换集中居住的集约用地方式．在人口聚集的同时引导中心镇向城市形态转化。     

基于XRF技术的大气重金属在线分析仪的研制

针对大气中铅、铬、镉等重金属在线监测的应用需求,研制了基于X射线荧光分析技术的大气重金属在线分析仪。该仪器具有可同时监测20多种元素、检出限低、无损快速、使用方便和维护成本低等优点。详细描述了仪器的总体设计及主要结构,展现了仪器性能特点;对仪器进行性能测试,结果显示该分析仪性能稳定,达到国际同类仪器水平。该分析仪监测大气中铅元素浓度结果与ICP-MS(inductively coupled plasma mass spectrometry)分析仪结果对比相对误差在4%以内。将该分析仪应用于杭州某大气监测站,连续监测大气重金属变化情况,实验结果表明该分析仪可靠性高、具有较强的现场应用能力,满足现场应用需求。     

基于长波近红外的便携式品质分析仪的研制及应用

针对野外和现场的产品品质分析应用,研制了一种基于长波近红外的便携式品质分析仪.该仪器具有结构紧凑、重量轻、体积小、响应速度快、携带方便、操作简单、环境适应性强等优点.从硬件与软件两方面详细描述了该分析仪的性能特点.对3台同型仪器进行性能测试,结果显示该型分析仪性能稳定,仪器一致性好,已经达到国际同类仪器水平.小麦和大豆的无损测定表明该分析仪可靠性高且模型传递效果好.性能测试及建模实验表明该分析仪具有较强的现场应用能力,能够满足各种野外检测需求.     

WJ5AI发动机中央传动锥齿轮组件故障分析及改进措施

通过对ＷＪ５ＡＩ发动机中央传动锥齿轮组件故障进行调查、分析，阐明了原中央传动锥齿轮组件结构设计存在不安全因素。中央传动锥齿轮与轴的配合紧度小，圆柱销在变化载荷作用下传递扭矩，与其孔的配合表面产生微动磨损，微动磨损进一步发展造成了中央传动锥齿轮组件传扭失效。