PSA中人因失误模型化研究

主要研究PSA模型如何考虑人因失误的影响,系统地提出如何在电厂系统模型中建立相对应的人因失误分析模型。利用事件树把系统故障和人因失误相结合的方法,探讨如何最大可能地真实描述事故后的操纵员行为,确定重要人因事件发展序列以及根据系统响应确定合理可分析的人因题头,建立完整的人因失误模型化的体系,并以实例说明具体分析过程。此项研究能够较好地描述硬件可靠性和人因可靠性之间的关联关系,降低HRA出力并满足PSA对于事故后人员行为的概率分析需求。     

加载条件下原水管道受力特征模型试验研究

为研究堆载大小对原水管道受力变形的影响,采用量纲分析法得出模型试验相似比,并根据相似比进行模型箱的设计、管道材料的选取和重塑土的配制,研究不同工况下管道的受力特征。试验结果表明:整体上管道端部应力大于管中央应力,管轴向应力大于管环向应力。在中心加载下,管端应力值较管中央处大,前者增长速度更快,而后者增长速度较慢。在偏心荷载作用下,靠近荷载的管端应力最大,而管中央应力最小;尤其在偏载6 kPa作用下,管端下表面轴向应力达到595 kPa,而管中央处仅有64 kPa,管端受边界约束作用明显,管道呈弯曲变形。     

Long‐Term Trends of Nutrients and Sediment from the Nontidal Chesapeake Watershed: An Assessment of Progress by River and Season

To assess historical loads of nitrogen (N), phosphorus (P), and suspended sediment (SS) from the nontidal Chesapeake Bay watershed (NTCBW), we analyzed decadal seasonal trends of flow‐normalized loads at the fall‐line of nine major rivers that account for >90% of NTCBW flow. Evaluations of loads by season revealed N, P, and SS load magnitudes have been highest in January‐March and lowest in July‐September, but the temporal trends have followed similar decadal‐scale patterns in all seasons, with notable exceptions. Generally, total N (TN) load has dropped since the late 1980s, but particulate nutrients and SS have risen since the mid‐1990s. The majority of these rises were from Susquehanna River and relate to diminished net trapping at the Conowingo Reservoir. Substantial rises in SS were also observed, however, in other rivers. Moreover, the summed rise in particulate P load from other rivers is of similar magnitude as from Susquehanna. Dissolved nutrient loads have dropped in the upland (Piedmont and above) rivers, but risen in two small rivers in the Coastal Plain affected by lagged groundwater input. In addition, analysis of fractional contributions revealed consistent N trends across the upland watersheds. Finally, total N:total P ratios have declined in most rivers, suggesting the potential for changes in nutrient limitation. Overall, this integrated study of historical data highlights the value of maintaining long‐term monitoring at multiple watershed locations.     

Biohythane production from pineapple peel using Methanosarcina mazei enhanced with palm oil mill effluent (POME) sludge in single-stage anaerobic digestion

Biohythane production via single-stage anaerobic digestion (AD) is an effective way for sustainable energy recovery from lignocellulosic biomass. In this paper, biohythane was produced through the AD process from pineapple peel waste substrate using purely cultured Methanosarcina mazei with the enhancement of palm oil mill effluent (POME) sludge as the inoculum. This study focuses on the effects of the lignocellulosic pre-treatment method, the addition of POME sludge into M. mazei culture medium as inoculum, and various operational conditions (food to microorganisms (F/M) ratios, temperature, pH) on gas production performances. The experimental results indicate that these parameters influenced the efficiency of biohythane production by producing the peak maximum biohythane production rate values (HPR_max) and (MPR_max), H₂:CH₄ = 1.93:0.67 L/L-d, and biohythane yield (HY) and (MY), H₂:CH₄ = 1.18:0.55 mL/L-substrate. This study demonstrates that biohythane gas (H₂ + CH₄ + CO₂) production from pineapple waste can be accelerated by M. mazei only with the enhancement of POME sludge through single-stage AD system under mesophilic batch process conditions.     

Assessing the Effectiveness of Winter Cover Crops for Controlling Agricultural Nutrient Losses

A nutrient loss reduction strategy is necessary to guide the efforts of improving water quality downstream of an agricultural watershed. In this study, the effectiveness of two winter cover crops, namely cereal rye and annual ryegrass, is explored as a loss reduction strategy in a watershed that ultimately drains into a water supply reservoir. Using a coupled optimization-watershed model, optimal placements of the cover crops were identified that would result in the tradeoffs between nitrate-N losses reduction and adoption levels. Analysis of the 10%, 25%, 50%, and 75% adoption levels extracted from the optimal tradeoffs showed that the cover crop placements would provide annual nitrate-N loss reductions of 3.0%–3.7%, 7.8%–8.8%, 15%–17.5%, and 20.9%–24.3%, respectively. In addition, for the same adoption levels (i.e., 10%–75%), sediment (1.8%–17.7%), and total phosphorus losses (0.8%–8.6%) could be achieved. Results also indicate that implementing each cover crop on all croplands of the watershed could cause annual water yield reduction of at least 4.8%, with greater than 28% in the months of October and November. This could potentially be detrimental to the storage volume of the downstream reservoir, especially in drought years, if cover crops are adopted in most of the reservoir's drainage area. Evaluating water yield impacts, particularly in periods of low flows, is thus critical if cover crops are to be considered as best management practices in water supply watersheds.     

Developing shared qualitative models for complex systems

Understanding complex systems is essential to ensure their conservation and effective management. Models commonly support understanding of complex ecological systems and, by extension, their conservation. Modeling, however, is largely a social process constrained by individuals’ mental models (i.e., a small-scale internal model of how a part of the world works based on knowledge, experience, values, beliefs, and assumptions) and system complexity. To account for both system complexity and the diversity of knowledge of complex systems, we devised a novel way to develop a shared qualitative complex system model. We disaggregated a system (carbonate coral reefs) into smaller subsystem modules that each represented a functioning unit, about which an individual is likely to have more comprehensive knowledge. This modular approach allowed us to elicit an individual mental model of a defined subsystem for which the individuals had a higher level of confidence in their knowledge of the relationships between variables. The challenge then was to bring these subsystem models together to form a complete, shared model of the entire system, which we attempted through 4 phases: develop the system framework and subsystem modules; develop the individual mental model elicitation methods; elicit the mental models; and identify and isolate differences for exploration and identify similarities to cocreate a shared qualitative model. The shared qualitative model provides opportunities to develop a quantitative model to understand and predict complex system change.     

麻黄碱在斑马鱼体内的器官特异性蓄积及毒代动力学

麻黄碱（ephedrine,EPH）是一种生物碱,用于减轻感冒、过敏性鼻炎、鼻炎及鼻窦炎引起的鼻充血症状,控制支气管哮喘等,同时还是制造毒品冰毒的原料.EPH已经在地表水中广泛检出,并可能对水生生物甚至生态系统产生不利影响.但目前,EPH在水生生物中的摄取、器官分配和毒代动力学过程还没有受到关注.本研究中将斑马鱼（Danio rerio）在半静态系统中暴露于EPH,研究斑马鱼的不同器官对EPH的吸收、蓄积以及EPH在斑马鱼体内的毒物代动力学.暴露浓度分别为0.01、1.00和100.00 μg·L^-1,暴露14 d后,在斑马鱼脑、肝、肠、卵巢及肌肉中均检测到EPH,高浓度组斑马鱼脑中EPH最高达到84.97 ng·g^-1;EPH的平均含量的相对大小遵循以下顺序：脑 > 卵巢 > 肝 >肠 > 肌肉.斑马鱼器官中的麻黄碱的摄取速率常数（K_u）为0.23~570.31 L·（kg·d）^-1,消除速率常数（K_e）为1.22~6.11 d^-1,半衰期为0.12~0.57 d.观察到的生物富集系数（BCF_o）和动力学来源的生物富集系数（BCF_k）范围分别为0.24~337.33 L·kg^-1和0.13~316.43 L·kg^-1,处于相同的水平.     

领导行为、安全文化与矿工安全行为的结构方程模型

为了提高矿工的安全行为,在相关研究基础上,提出领导行为、安全文化与矿工安全行为之间的理论假设模型。依据436份来自矿工的有效问卷,利用结构方程模型方法验证假设。结果表明:领导行为、安全文化对于安全行为具有一定的预测力和影响力,领导行为不仅对安全文化有直接影响,也通过安全文化间接影响安全行为;交易型领导对安全行为的整体影响强度高于变革型领导;变革型领导和交易型领导对安全文化各维度均有显著的正向影响关系;安全文化中除安全规程和安全培训对安全参与行为预测力不足外,其余维度均对安全遵守行为和安全参与行为有显著的正向影响关系。     

组织管理失误对操作人员行为安全影响分析

为使操作人员行为更安全,对组织管理失误进行分析,归纳为管理控制失误、组 织规程失误、组织安全管理失误、安全监督失误、教育培训不足5个方面,运用结构方 程模型（SEM）分析对操作人员行为安全的影响,使用AMOS软件对模型求解。运用直觉 三角模糊数对模型中指标进行评价并采用TOPSIS法对不安全行为进行排序。研究表明: 管理控制和组织规程对建立安全监督体系有正向作用;管理控制和组织规程对组织安全 管理实施有正向作用;管理控制和组织规程对有教育培训正向作用;建立安全监督体系 、组织安全管理实施和教育培训对操作人员安全行为有正向作用。进行风险排序有利于 企业对关键工种提出改进措施,提高企业效益。     

Warm glow from green power: Evidence from Australian electricity consumers

Green electricity products are increasingly made available to consumers in many countries in order to address a number of environmental and social concerns. Most of the literature on this green electricity market focuses on consumers’ characteristics and product attributes that could affect participation. However, the contribution of this environmental consumerism to the overall environmental good does not depend on participation alone. The real impact relies on market participation for green consumers (the proportion of green consumers) combined with the level of green consumption intensity – the commitment levels, or proportion of consumption that is green. We design an online interface that closely mimics the real market decision environment for electricity consumers in Western Australia and use an error component model to analyze consumers’ choice of green electricity products and their commitment levels. We show that product attributes have limited impact on the choice of green products; however, there is still great potential for better participation by improving the design of green electricity programs. When green products are selected, most respondents select the minimum commitment possible, and this is insensitive to the premium being charged on green power, suggesting that we are largely observing a buy-in ‘warm glow’ for carbon mitigation.