Experimental study on the synergistic inhibition effect of nitrogen and ultrafine water mist on gas explosion in a vented duct

In this study, in order to research the synergistic inhibition effect of nitrogen and ultrafine water mist on gas explosion in a vented duct, a semi-confined transparent chamber was designed with the size of 120 × 120 × 840 mm, and the experiments were carried out with stoichiometric methane/air premixed mixture (fraction of methane: 9.5%), adding different fractions of nitrogen and ultrafine water mist. The experimental results showed the following: The combination of nitrogen and ultrafine water mist had a synergistic inhibiting effect on methane/air explosion, which was preferable to the single use of any kind. With the increase of spraying time of water mist and fraction of nitrogen, the initial shape of the explosion flame became snakelike, and at the same time the peak flame propagation speed and peak overpressure decreased significantly. When the nitrogen fraction was increased to 10% and the mist spraying time was increased to 2min, synergistic inhibiting effect on overpressure was high efficient. However, with the increase of spraying time of water mist and fraction of nitrogen going on, the amount of increase of explosion inhibition efficiency was gradually reduced.     

“十三五”期间中国生态环境质量变化特征

以国家生态环境监测网监测结果为基础,总结归纳了"十三五"时期中国生态环境质量变化特征和主要环境问题。结果表明:"十三五"期间,全国生态环境质量全面好转,2020年环境空气优良天数比例比"十二五"末期上升5.8个百分点;地表水总体水质由轻度污染转为良好,Ⅰ～Ⅲ类水质断面比例上升17.4个百分点,劣V类断面比例下降9.0个百分点;酸雨污染程度减轻,海洋等环境要素质量稳中向好。但与此同时,后续改善难度加大,全国仍有40%地级及以上城市空气质量超标,4.8%的国土面积发生酸雨,辽河和海河流域仍是轻度污染,部分河流污染较重,地下水以IV类水质为主,农村饮用水源地和地表水水质均受到不同程度污染,近三分之一国土面积县域生态质量为较差和差。总体来看,当前生态环境质量与人民对美好生态环境的需求和美丽中国目标的实现还有较大差距。逐年上升的能源消费总量和不断增长的汽车保有量,增加了生态环境质量继续改善的压力。     

Conservation implications of anthropogenic impacts on visual communication and camouflage

Anthropogenic environmental impacts can disrupt the sensory environment of animals and affect important processes from mate choice to predator avoidance. Currently, these effects are best understood for auditory and chemosensory modalities, and recent reviews highlight their importance for conservation. We examined how anthropogenic changes to the visual environment (ambient light, transmission, and backgrounds) affect visual communication and camouflage and considered the implications of these effects for conservation. Human changes to the visual environment can increase predation risk by affecting camouflage effectiveness, lead to maladaptive patterns of mate choice, and disrupt mutualistic interactions between pollinators and plants. Implications for conservation are particularly evident for disrupted camouflage due to its tight links with survival. The conservation importance of impaired visual communication is less documented. The effects of anthropogenic changes on visual communication and camouflage may be severe when they affect critical processes such as pollination or species recognition. However, when impaired mate choice does not lead to hybridization, the conservation consequences are less clear. We suggest that the demographic effects of human impacts on visual communication and camouflage will be particularly strong when human‐induced modifications to the visual environment are evolutionarily novel (i.e., very different from natural variation); affected species and populations have low levels of intraspecific (genotypic and phenotypic) variation and behavioral, sensory, or physiological plasticity; and the processes affected are directly related to survival (camouflage), species recognition, or number of offspring produced, rather than offspring quality or attractiveness. Our findings suggest that anthropogenic effects on the visual environment may be of similar importance relative to conservation as anthropogenic effects on other sensory modalities.     

The city as a refuge for insect pollinators

Research on urban insect pollinators is changing views on the biological value and ecological importance of cities. The abundance and diversity of native bee species in urban landscapes that are absent in nearby rural lands evidence the biological value and ecological importance of cities and have implications for biodiversity conservation. Lagging behind this revised image of the city are urban conservation programs that historically have invested in education and outreach rather than programs designed to achieve high‐priority species conservation results. We synthesized research on urban bee species diversity and abundance to determine how urban conservation could be repositioned to better align with new views on the ecological importance of urban landscapes. Due to insect pollinators’ relatively small functional requirements—habitat range, life cycle, and nesting behavior—relative to larger mammals, we argue that pollinators put high‐priority and high‐impact urban conservation within reach. In a rapidly urbanizing world, transforming how environmental managers view the city can improve citizen engagement and contribute to the development of more sustainable urbanization.     

Experimental and theoretical investigation of dry-water containing phosphoric acid for new fire suppressant

To overcome the shortcomings of phosphorus-containing compounds (PCCs, not widely used) in fire suppression, the dry water powder containing phosphoric acid was analyzed for a new fire suppressant (SiO₂-P). First, the fine conditions (solid-to-liquid ratio, stirring time and stirring speed) were determined to prepare the new powder. The particle size distributions and XPS of SiO₂-P powder were analyzed. The TG tests were conducted to study the decomposition of powder, and there was a major decomposition peak. Second, the extinguishing time of SiO₂-P powder was tested, which showed that the SiO₂-P powder containing phosphorus species could significantly improve the fire suppression ability. In addition, the kinetic parameters of powder decomposition reaction were determined by genetic algorithm based on TG results. Last, based on the decomposition products and kinetic parameters, the burning velocity and mass fraction of free radicals of CH₄/air flame with SiO₂-P powder addition were studied theoretically. The results indicated that SiO₂-P powder had great ability of reducing the burning velocity and scavenging free radicals. Furthermore, the suppression effects were analyzed, which indicated that the cooperation of H₂O and P suppression effect dominated the suppression mechanism and resulted in the good suppression efficiency.     

When and how to use Q methodology to understand perspectives in conservation research

Understanding human perspectives is critical in a range of conservation contexts, for example, in overcoming conflicts or developing projects that are acceptable to relevant stakeholders. The Q methodology is a unique semiquantitative technique used to explore human perspectives. It has been applied for decades in other disciplines and recently gained traction in conservation. This paper helps researchers assess when Q is useful for a given conservation question and what its use involves. To do so, we explained the steps necessary to conduct a Q study, from the research design to the interpretation of results. We provided recommendations to minimize biases in conducting a Q study, which can affect mostly when designing the study and collecting the data. We conducted a structured literature review of 52 studies to examine in what empirical conservation contexts Q has been used. Most studies were subnational or national cases, but some also address multinational or global questions. We found that Q has been applied to 4 broad types of conservation goals: addressing conflict, devising management alternatives, understanding policy acceptability, and critically reflecting on the values that implicitly influence research and practice. Through these applications, researchers found hidden views, understood opinions in depth and discovered points of consensus that facilitated unlocking difficult disagreements. The Q methodology has a clear procedure but is also flexible, allowing researchers explore long‐term views, or views about items other than statements, such as landscape images. We also found some inconsistencies in applying and, mainly, in reporting Q studies, whereby it was not possible to fully understand how the research was conducted or why some atypical research decisions had been taken in some studies. Accordingly, we suggest a reporting checklist.     

CO2浓度升高对半干旱区春小麦光合作用及水分生理生态特性的影响

大气CO₂浓度升高已成为世界范围内重要环境问题。为了解大气CO₂浓度升高对春小麦光合作用及水分生理生态特性的影响,在典型半干旱区定西利用开顶式气室(OTC)试验平台,以春小麦“定西24号”为供试品种,开展了CO₂浓度增加模拟试验。试验设对照(390μmol·mol^?1)、480μmol·mol^?1和570μmol·mol^?1等3个CO₂浓度(摩尔分数)梯度。结果表明:在对照和增加CO₂浓度条件下,春小麦叶片净光合速率和蒸腾速率日变化均呈“双峰型”分布,出现明显的“午休”现象;胞间CO₂浓度的日变化表现为斜“V”字型曲线;叶水势日变化呈现反抛物线曲线走向,在中午后出现水势曲线拐点。在不同生育时期内,净光合速率、气孔导度和胞间CO₂浓度均表现为开花期最大,乳熟期最小。而蒸腾速率表现为开花期最大,拔节期最小,叶片水平水分利用效率表现为孕穗期最大,乳熟期最小。随着CO₂浓度升高,春小麦叶片净光合速率、胞间CO₂浓度、水分利用效率和水势提高,气孔导度和蒸腾速率降低。与对照大气CO₂浓度相比,在480μmol·mol^?1浓度和570μmol·mol^?1浓度下,整个生育期净光合速率平均分别提高了14.68%和28.20%,气孔导度平均降低了15.29%和24.83%,胞间CO₂浓度平均提高了10.38%和26.15%,蒸腾速率平均减小了6.63%和12.41%,WUE平均增加了22.9%和46.9%。随着CO₂浓度升高,蒸腾失水减少,叶片水势不断增加,从而增强了春小麦对干旱胁迫的抵御能力。研究结果为我国半干旱区春小麦对全球气候变化下的敏感性及适应性提供理论参考。     

Water saving effect on integrated water resource management

This study proposes an improved integrated water resource management (IWRM), in which water conservation was analyzed for the entire water use process. A multi-objective optimization method was applied to optimize the IWRM, which investigated the reduction of freshwater consumption and the total water supply cost. Customer's preference for saving water and an end use analysis (EUA) was applied in the water conservation analysis. Taking Tianjin as the study area, a reduction in customer's economic pressure (EP) was utilized to evaluate the degree of the customer's preference for saving water. The results revealed that agriculture had a greater preference for saving water than other sectors, where as the public had the weakest motivation for saving water. Improving the transportation method could contribute 62.1% of the total water savings in the agriculture sector. The optimization of the IWRM demonstrated that the local freshwater savings would be 21.5%, and the total cost for water supplies would decrease by 13%. However, a government subsidy of 87.5 million Yuan would be needed. Additionally, by analyzing the change in the amount of water savings affected by water price, the appropriate water price increase range was suggested to be 1.5–1.7 times the original price.     

Targeted Application of Seasonal Load Duration Curves Using Multivariate Analysis in Two Watersheds Flowing Into Lake Houston1

Teague, Aarin, Philip B. Bedient, and Birnur Guven, 2011. Targeted Application of Seasonal Load Duration Curves Using Multivariate Analysis in Two Watersheds Flowing Into Lake Houston. Journal of the American Water Resources Association (JAWRA) 47(3):620‐634. DOI: 10.1111/j.1752‐1688.2011.00529.x Abstract: Water quality is a problem in Lake Houston, the primary source of drinking water for the City of Houston, Texas, due to pollutant loads coming from the influent watersheds, including Spring Creek and Cypress Creek. Statistical analysis of the historic water quality data was developed to understand the source characterization and seasonality of the watershed. Multivariate analysis including principal component, cluster, and discriminant analysis provided a custom seasonal assessment of the watersheds so that loading curves may be targeted for season specific pollutant source characterization. The load duration curves have been analyzed using data collected by the U.S. Geologic Survey with corresponding City of Houston water quality data at the sites to characterize the behavior of the pollutant sources and watersheds. Custom seasons were determined for Spring Creek and Cypress Creek watersheds and pollutant source characterization compared between the seasons and watersheds.     

PLC控制系统在钢渣热焖工艺中的应用

利用PLC控制系统,实现在钢渣热焖工艺中的恒压供水和钢渣热焖定时定量喷水的自动控制要求,具有国际先进水平,取得了良好的经济效益、社会效益和环境效益.