DT-X回声探测仪在太湖沉水植物调查中的应用

沉水植物是湖泊生态系统的重要组成部分,掌握沉水植物分布及变化对于湖泊水环境综合治理及生态修复具有重要意义。在分析现有沉水植物调查方法的不足和介绍DT-X多功能回声探测仪的相关功能及国外应用情况的基础上,分析了在太湖应用该仪器开展沉水植物调查可能需要克服的技术难题,并选择断面对该仪器开展了试验性应用。结果表明,仪器调查结果与人工样方调查结果基本一致,应用DT-X回声探测仪在太湖开展沉水植物调查具有一定的前景。     

A systems approach to organizational error

Abstract

The past two decades have seen a significant number of large-scale disasters in a wide range of hazardous, well-defended technologies. Despite their differences, the root causes of these accidents have been traced to latent failures and organizational errors arising in the upper echelons of the system in question. A model of the aetiology of these organizational accidents is outlined. The model describes two interrelated causal sequences: (a) an active failure pathway that originates in top-level decisions and proceeds via error-producing and violation-promoting conditions in the various workplaces to unsafe acts committed by those at the immediate human-system interface and (b) a latent failure pathway that runs directly from the organizational processes to deficiencies in the system's defences. The paper goes on to identify two sets of dependencies associated with latent failures and violations. Organizational errors increase the likelihood of operator error through the active failure pathway and, at the same time, enhance the possibility of adverse outcomes through defensive weaknesses. Violations have a narrower range of consequences. Non-compliance with safe operating procedures increases the likelihood of error by taking perpetrators into regions of operation in which neither the physical regime nor the hazards are well understood. Violations, by definition, also take perpetrators ‘closer to the edge,’ and thus increase the chance that subsequent errors will have damaging outcomes. The paper concludes by indicating two ways in which the model has been applied in industrial settings: (a) through the development of proactive measures for diagnosing and remedying organizational processes known to be implicated in accident causation, and (b) an accident investigation technique that guides investigators and analysts to the organizational root causes of past accidents.     

甘肃省清水县白驼镇土地利用潜力分析

本文介绍了清水县白驼镇试点项目,总结出目前小城镇建设中土地综合利用情况和潜力发掘的方向。     

Thermodynamic screening of suitable oxygen carriers for a three reactor chemical looping reforming system

Hydrogen (H₂) production by using a three reactor chemical looping reforming (TRCLR) technology is an innovative process which utilizes fossil fuels as feed stocks. This process occurs in three steps by employing an oxygen carrier (OC), which is generally a transition metal. As the OC plays an important role, its selection should be done after carefully considering the chemical and physical properties of the material. In this study, various candidate materials for use in a TRCLR process, with methane (CH₄) as a fuel stock, were investigated. The results show that the iron (Fe)- and molybdenum (Mo)-based OCs oxidize CH₄ completely in the FR at low temperatures. In terms of H₂ yield, tungsten (W)-based OCs produce the highest yield, ～3.9 mol-H₂/mol-CH₄. The equilibrium oxygen partial pressures and the solid circulation rates are the highest for Fe-based OCs. The oxygen carrying capacity of Fe-based OCs is relatively high while its price is low. Therefore, among the OCs investigated, Fe-based OCs were identified as the preferred OC option for a TRCLR process.     

水-甲醇混合工质振荡热管温度振荡及传热特性研究

通过实验研究了水-甲醇混合工质振荡热管充液率分别为55%、62%、70%、90%下,体积比分别为13∶1、4∶1、1∶1、1∶4、1∶13时的温度振荡以及热阻特性,并与水、甲醇纯工质振荡热管进行了对比。研究表明,混合工质振荡热管的振幅较纯工质大且较为均匀;较大充液率时(62%及以上),大多数混合工质振荡热管热阻大于两种纯工质;中等充液率时,部分振荡热管出现烧干现象,受黏度影响,大多数混合工质振荡热管出现烧干现象时的功率较小,热阻较纯工质大。但是,在水中加入少量甲醇(13:1)做工质的振荡热管在充液率为55%下不易发生烧干,且热阻较其他工质低。振荡热管的热阻特性受工质黏度、气液相平衡等因素的共同作用,在不同工况下,各因素作用效果不同。     

重探试验锤击数的杆径换算研究

目前,国内绝大多数规范规定重探试验应采用Φ42 mm钻杆,但从施工方便等因素的考虑,很多工程勘察单位趋向于采用Φ50 mm的钻杆进行重探试验。通过分析重探试验要点及其影响因素,基于重探试验锤击数修正系数表,推导出杆径换算系数为0.89,并以海南省某岛礁水运工程实例加以验证。结果表明,同一地貌单元,埋深12 m以浅的珊瑚碎屑层,采用Φ42 mm钻杆进行重探试验的击数与采用Φ50 mm钻杆进行重探试验的击数之比值为0.875,与推导结果基本一致。     

给水管道顶管工程岩土勘察及其施工工艺分析评价

本文介绍了给水管道顶管工程的相关特点和要素,并以相关的工程案例为基础,着重分析了顶管工程的应用和作用;同时,研究施工现场的岩土性质和地质勘查工作的应用和作用,以此评价给水管道工程是否稳定、符合工程要求。     

高校工科类专业实践教学存在问题的调查与分析

实践教学是高校工科类专业完成知识传授和技能培养的关键环节.文章对课内实验、专业认识实习、生产实习、毕业实习、毕业设计等实践教学环节的模式、效果、存在的困难等情况进行了详细的调查、归纳与分析.得出的主要结论是：目前高校工科类专业实践教学中专业认识实习和生产实习所需校外现场难以满足要求、毕业实习逐步流于形式、毕业设计与学生就业工作严重冲突、创新设计性实验严重缺乏.这些结论为研究高校工科类专业实践教学模式的可替代方案奠定了基础.     

基于实地调研的南京市公租房空间可变性研究及应对策略分析

公租房是我国当代社会发展阶段的必然产物.文章依托南京市公租房“民心公寓”实地调研成果,介绍了公租房相关概念及南京市公租房建设概况,并以公租房空间可变性的视角切入,从非承重结构可变性、家具模块化、整体卫生间装配式生产等三个方面探讨公租房设计的应对策略,期望达到在保证公租房使用方便舒适的同时提高空间利用效益的目的.     

基于新风阀和回风阀分段调节的新风量控制方法

本文基于全空气空调系统风量与压差平衡关系式,提出了一种分段调节新风阀和回风阀的新风量控制方法,并与传统压差控制法进行对比试验研究.结果表明该新风量控制方法比传统的压差控制法能够实现更好的控制效果,同时降低了送风机能耗.