预制空心板受火后力学性能的试验研究

为比较不同受火时间后预制空心板剩余承载力、跨中挠度和破坏形态的异同,进行了6块预制空心板受火后力学性能的对比试验研究,其中3块为未受火的对比试件,另3块为板底分别受火23、38、53min的试件。受火试验结果表明,各试件在升温过程中的跨中挠度随受火时间增加而显著增加,熄火自然冷却后,跨中挠度大部分可恢复。加载试验结果表明,对比试件和受火试件的最终破坏模式均为弯曲破坏;随着受火时间延长,试件开裂荷载和破坏荷载均有所降低,且破坏荷载与受火时间大致呈线性关系;受火试件初始弯曲刚度较对比试件明显降低,相同荷载作用下,受火试件受拉边缘拉应变和受压边缘压应变,均明显大于对比试件。     

Environmental hazards and waste management in Nsukka urban metropolis in Enugu State of Nigeria: how much are people willing to pay?

Solid waste management in Nsukka town in Enugu state of Nigeria has remained a major challenge despite the efforts of the state government through the Enugu State Waste Management Agency (ESWAMA). The current method whereby households dump refuse at designated locations by the road side to be cleared later has not yielded much improved sanitation of the town. In this study we propose an alternative waste management method that is believed to be superior to the status quo if properly managed. This study applies Contingent Valuation Method (CVM) to estimate the households’ willingness to pay (WTP) for this new method in order to ascertain its applicability in Nsukka urban. Data were collected from a sample of 500 households stratified according to major streets in the town. The results show that the mean WTP using different specifications of the model varies from N527.50 (about 2.68) to N530.90 (about 2.68) per month. The policy implication is that if the waste management agency adopts the proposed scenario and manages it well the average revenue realizable per month would be about N13,750,516 (about $69,800). The authorities can compare this with the cost of providing the service and see if it is worth the effort.     

‘Natural’ disaster? A retrospect into the causes of the late-2004 typhoon disaster in Eastern Luzon,Philippines

Between 14 November and 4 December 2004, four successive tropical depressions and typhoons lashed the Eastern coast of Luzon in the Philippines. Heavy rainfall triggered massive landslides and devastating flash floods, which brought tremendous damage and killed more than 1600 people. Immediately after the disaster, there was a media and political consensus to incrimate ‘extraordinary’ natural phenomena and widespread deforestation as responsible for the catastrophe. We argue that the tragedy that befell the municipalities of General Nakar, Infanta and Real, among other devastated areas, is enmeshed in a deeper tangle of causal factors that are political, socio-economic and demographic in nature. These factors include unmanaged population growth, difficult access to land and resources, corruption within the government, and power of the elite.     

Looking forward: Disasters at 40

This paper reflects on contemporary studies of and responses to disasters, highlighting the importance of historical, spatial, and intersectional modes of analysis, and draws on the author's ongoing research on Southern‐led and local community responses to displacement in the Middle East. Acknowledging the plurality of ‘international communities of response’, it begins by critiquing the depiction of selected responses to disasters as ‘positive’ ‘paradigm shifts’, including in reference to the ‘localisation of aid, and the United Nations’ Regional Refugee and Resilience Plan for Syria. Next it turns to three key themes that are central to disasters studies: migration; forced displacement; and Southern‐led responses to disasters. Among other things, the paper argues that exploring the principles and modalities of South–South cooperation, rather than promoting the incorporation of Southern actors into the ‘international humanitarian system’ via the localisation agenda, presents a critical opportunity for studies of and responses to disasters.     

Ultrasensitive and selective 4-aminophenol chemical sensor development based on nickel oxide nanoparticles decorated carbon nanotube nanocomposites for green environment

Nickel oxide nanoparticles decorated carbon nanotube nanocomposites(Ni O·CNT NCs)were prepared in a basic medium by using facile wet-chemical routes. The optical,morphological, and structural properties of Ni O·CNT NCs were characterized using Fourier transformed infra-red(FT-IR), Ultra-violet visible(UV/Vis) spectroscopy, field-emission scanning electron microscopy(FESEM), X-ray energy dispersed spectroscopy(XEDS), X-ray photoelectron spectroscopy(XPS), and powder X-ray diffraction(XRD) methods. Selective4-aminophenol(4-AP) chemical sensor was developed by a flat glassy carbon electrode(GCE, surface area: 0.0316 cm~2) fabricated with a thin-layer of NCs. Electrochemical responses including higher sensitivity, large dynamic range(LDR), limit of detection(LOD), and long-term stability towards 4-AP were obtained using the fabricated chemical sensors. The calibration curve was found linear(R~2= 0.914) over a wide range of 4-AP concentration(0.1 nmol/L–0.1 mol/L). In perspective of slope(2 × 10~(-5)μA/μM), LOD and sensitivity were calculated as 15.0 ± 0.1 pM and ~ 6.33 × 10~(-4)μA/(μM·cm) respectively. The synthesized Ni O·CNT NCs using a wet-chemical method is a significant route for the development of ultrasensitive and selective phenolic sensor based on nano-materials for environmental toxic substances. It is suggested that a pioneer and selective development of 4-AP sensitive sensor using Ni O·CNT NCs by a facile and reliable current vs voltage(I–V)method for the major application of toxic agents in biological, green environmental, and health-care fields in near future.     

Sensitivity of species-distribution models to error,bias, and model design: An application to resource selection functions for woodland caribou

Models that predict distribution are now widely used to understand the patterns and processes of plant and animal occurrence as well as to guide conservation and management of rare or threatened species. Application of these methods has led to corresponding studies evaluating the sensitivity of model performance to requisite data and other factors that may lead to imprecise or false inferences. We expand upon these works by providing a relative measure of the sensitivity of model parameters and prediction to common sources of error, bias, and variability. We used a one-at-a-time sample design and GPS location data for woodland caribou (Rangifer tarandus caribou) to assess one common species-distribution model: a resource selection function. Our measures of sensitivity included change in coefficient values, prediction success, and the area of mapped habitats following the systematic introduction of geographic error and bias in occurrence data, thematic misclassification of resource maps, and variation in model design. Results suggested that error, bias and model variation have a large impact on the direct interpretation of coefficients. Prediction success and definition of important habitats were less responsive to the perturbations we introduced to the baseline model. Model coefficients, prediction success, and area of ranked habitats were most sensitive to positional error in species locations followed by sampling bias, misclassification of resources, and variation in model design. We recommend that researchers report, and practitioners consider, levels of error and bias introduced to predictive species-distribution models. Formal sensitivity and uncertainty analyses are the most effective means for evaluating and focusing improvements on input data and considering the range of values possible from imperfect models.     

2016—2019年汾渭平原城市空气质量状况分析

基于2016—2019年全国城市环境空气质量国控监测点位自动监测数据,分析了汾渭平原城市空气质量状况。结果表明：2019年,汾渭平原优良天数比例为61.7%,略高于"2+26"城市,明显低于全国及其他区域,空气污染较重。2016—2019年,汾渭平原超标天数中PM_2.5、PM₁₀、O₃作为首要污染物的占比较高,PM_2.5、PM₁₀仍是影响汾渭平原空气质量的最主要污染物,O₃和NO₂的影响逐年升高。汾渭平原PM_2.5浓度呈夏季低、秋冬季高的特点,2019年与2016—2018年PM_2.5均值比较,1、2、4月分别偏高7.5%、36.7%、6.8%,其他月份均偏低,表明1、2、4月空气质量总体恶化,其他月份有所改善。汾渭平原O₃浓度呈夏季高、秋冬季低的特点,O₃浓度总体呈升高趋势,年平均升高10.3 μg/m³,临汾市年平均升幅最显著（26.7 μg/m³）,不同百分位O₃浓度均呈升高趋势,且高百分位浓度升幅明显高于低百分位浓度,年平均升幅最高出现在第90百分位浓度。2016—2019年,O₃单项污染物超标导致优良天数比例损失分别为5.4个百分点、13.0个百分点、11.1个百分点和14.4个百分点,总体呈上升趋势,表明O₃超标对空气质量影响越来越显著。煤炭消耗量、生铁产量、粗钢产量的大幅升高对空气质量有一定影响,建议加大对相关企业污染物的排放量检查,确保超低排放或采取可行的清洁能源替代。温度与O₃浓度呈正相关,2017—2019年,温度大于25 ℃的天数中94.2%出现在6—8月,O₃-8h超标天数占全部超标天数的81.4%,因此应加强温度较高月份的O₃管控。     

水平搅拌下低高径比SBR中好氧活性污泥的颗粒化

在设有水平机械搅拌、高径比（H/D）为1.2的圆柱形鼓风曝气SBR中,考察了活性污泥的颗粒化情况,对成熟颗粒污泥表面所受水力剪切速率进行了定量研究,分析了水平搅拌在颗粒化过程中的作用.结果表明：有水平搅拌存在下污泥逐渐颗粒化,形成了均值粒径为1.12mm的好氧颗粒污泥,污泥沉降速度为21.41m/h;计算结果表明污泥表面所受的平均剪切速率为27.25s^-1,剪切应力为3.38×10^-2N/m²;污泥表面所受平均剪切速率与机械搅拌速率和表观气速均呈正相关关系;实验条件下机械搅拌对剪切速率的贡献要远大于表观气速的贡献,前者指数约为后者的37.48倍.研究认为水平搅拌在反应器中形成的具有足够剪切强度的旋涡二次流是促使低高径比反应器好氧污泥颗粒化的关键水力条件.     

钻井废水的生物强化处理简

从受钻井废水污染的土壤样品中筛选菌株进行生物处理实验,确定7株菌进行菌剂配伍。通过正交实验剔除可能有抑制作用的菌株,并确定菌剂各组成菌株的最佳配比,制成复合微生物菌剂。考察5种添加物对菌剂的影响,结果显示,当硫酸铵的添加量为20 mg/L时降解率为60%,高于其他添加物。生物强化实验结果显示,投加菌剂的反应器对钻井废水的平均降解率为42%,比未投加菌剂的对照实验的平均降解率（16%）高,而且耐冲击负荷性和降解性能稳定性优于对照实验。     

Incorporating detectability of threatened species into environmental impact assessment

Environmental impact assessment (EIA) is a key mechanism for protecting threatened plant and animal species. Many species are not perfectly detectable and, even when present, may remain undetected during EIA surveys, increasing the risk of site‐level loss or extinction of species. Numerous methods now exist for estimating detectability of plants and animals. Despite this, regulations concerning survey protocol and effort during EIAs fail to adequately address issues of detectability. Probability of detection is intrinsically linked to survey effort; thus, minimum survey effort requirements are a useful way to address the risks of false absences. We utilized 2 methods for determining appropriate survey effort requirements during EIA surveys. One method determined the survey effort required to achieve a probability of detection of 0.95 when the species is present. The second method estimated the survey effort required to either detect the species or reduce the probability of presence to 0.05. We applied these methods to Pimelea spinscens subsp. spinescens, a critically endangered grassland plant species in Melbourne, Australia. We detected P. spinescens in only half of the surveys undertaken at sites where it was known to exist. Estimates of the survey effort required to detect the species or demonstrate its absence with any confidence were much higher than the effort traditionally invested in EIA surveys for this species. We argue that minimum survey requirements be established for all species listed under threatened species legislation and hope that our findings will provide an impetus for collecting, compiling, and synthesizing quantitative detectability estimates for a broad range of plant and animal species. Incorporación de la Capacidad de Detectar una Especie Amenazada a la Evaluación de Impacto Ambiental