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401.
灰色系统理论在城市交通噪声预测和绝对关联度分析中的应用 总被引:18,自引:0,他引:18
运用灰色系统理论的动态建模方法,根据最近7年的时间序列数据,建立了城市道路交通噪声的灰色预测模型。本模型经检验为一极模型,进行中、短期预测精度高,残差仅±0.7%。对某市未来几年交通噪声变化的趋势进行了预测。同时对影响城市交通噪声变化的8个相关因素进行了绝对关联度分析,确定了城市人口、车流量及机动车数量变化为影响交通噪声变化的优势因素。为交通噪声污染防治提供了科学依据。 相似文献
402.
废水中乙醛的化学发光法测定 总被引:3,自引:0,他引:3
乙醛发光分析法的检出限为8×10~(-11)g/ml,线性范围为5×10~(-10)g/ml-1×10~(-6)g/ml.对近30种常见无机物和有机物对乙醛测定的影响进行了试验,表明该方法具有良好的选择性.用于有机化工和印染废水中乙醛的测定,其回收率为94%~100%,变异系数为1.6%—6.4%。 相似文献
403.
This paper focuses on changing patterns of substance use among low income, African American drug users evacuated from New Orleans, Louisiana, during Hurricane Katrina of August 2005. It examines the relationship between increases and decreases in alcohol and tobacco (AT) use and illicit drug (ID) use after Katrina and pre‐disaster and within‐disaster factors. Data from structured interviews with 200 Katrina evacuees currently living in Houston were collected 8–14 months after the disaster. Multivariate analysis revealed that rises in AT use were positively associated with education. Females and younger evacuees were more likely to have increased AT use. ID use increase was positively associated with resource loss and leaving the city before Katrina. Decreases in AT and ID use were found to be associated with disaster‐related exposure. The paper discusses the specific consequences of disasters on disadvantaged minority substance users and the importance of developing public health disaster policies that target this population. 相似文献
404.
Dyer SD Sanderson H Waite SW Van Compernolle R Price B Nielsen AM Evans A Decarvalho AJ Hooton DJ Sherren AJ 《Environmental monitoring and assessment》2006,120(1-3):45-63
A feasible and relatively readily available analytical method was adapted for the assessment of alcohol ethoxylates (AE) and fatty alcohols (FA) in sediments. This study illustrates the simultaneous measurement of 38 of 114 possible alcohol ethoxylate ethoxymers (AE) and fatty alcohols (FA) found in commercially important AE products. We predicted toxicity for all identified fractions, as well as the total mixture toxicity, relative to three exposure scenarios via sewage treatment plants (STP) for these widely used chemicals in consumer products and hence generate a preliminary environmental risk screening for AE and FA in sediments. The method is based on derivatization of solvent or solid-phase extracts with 2-fluoro-N-methylpyridinium p-toluenesulfonate (Pyr+). The derivatized extracts were analyzed with liquid chromatography/mass spectrometry (LC/MS) operating in the positive ion electrospray mode. The extraction efficiency of AE and FA in three different sediments of varying composition was evaluated with spike-recovery studies, ranging from 64% to 80%. The detection limits for individual ethoxymers typically ranged from 1 to 5ngg−1on a dry weight basis. The mean limit of detection (LOD) was 6ngg−1and the median LOD was 3ngg−1. AE and FA in sediments were found to be stable for two weeks if preserved with 3% (v/v) formalin and stored at 4–6∘C. Based on equilibrium partitioning, background concentrations of AE and FA were predicted to be below concentrations known to elicit chronically toxic effects. Total worst case mixture toxicities for all AE ethoxymers combined with FA were predicted to result in a risk quotient less than 0.6. Activated sludge treatment (STP) significantly reduced the release of total AE and FA by four-fold, suggesting that the total mixture risk quotient would be < 0.15 for sediment dependent organisms. 相似文献
405.
406.
在磷酸介质中,利用铬(Ⅵ)对溴酸钾氧化乙基紫褪色反应有灵敏的催化作用,建立了测定痕量铬(Ⅵ)的新型催化光度法,考察了该褪色反应的最佳条件。在反应温度85℃、反应时间5m in、以醋酸钠作抑制剂的条件下,体系可稳定60m in以上,测定波长为600nm,方法的检出限为1×10-9g/mL,线性范围为0.004~0.094μg/mL,相对标准偏差小于2.5%,加标回收率为97.0%~101.5%。该法简便、灵敏、选择性好,用于水样中痕量铬(Ⅵ)的测定,结果令人满意。 相似文献
407.
高效液相色谱-电感耦合等离子体质谱联用测水中有机汞 总被引:1,自引:1,他引:0
建立了高效液相色谱-电感耦合等离子体质谱联用技术(HPLC-ICP-MS)测定水样中甲基汞、乙基汞、苯基汞等3种有机汞的分析方法。采用醋酸铵-L-半胱氨酸缓冲盐及甲醇体系组成的流动相按一定比例进行梯度洗脱,Agilent Zorbax Plus C18柱分离,经前处理的水样在液相色谱中分离后,进入电感耦合等离子体质谱检测其甲基汞、乙基汞、苯基汞的浓度。3种有机汞化合物均在0.50~50.0μg/L范围内呈良好的线性关系,线性相关系数均大于0.999 5。仪器检出限为0.09~0.12μg/L,方法检出限为0.4×10-6~0.6×10-6mg/L,3种有机汞样品加标的RSD均小于11.3%,2个水平的加标回收率为74.4%~83.2%。 相似文献
408.
Identification of the leakage of hazardous gases plays an important role in the environment protection, human health and safety of industry production. However, lots of current optimization algorithms, such as particle swarm optimization (PSO) and Grey Wolf Optimizer (GWO), suffer from poor global optimization capability and estimation accuracy. In this work, a hybrid differential evolutionary and GWO (DE-GWO) algorithm is proposed. Tested by simulation cases and Prairie Grass emission experimental data, DE-GWO shows higher estimation accuracy than GWO. Compared with the other four optimization algorithms, DE-GWO exhibits finer robust stability under different population sizes, fewer iterations, as well as higher estimation accuracy with fewer search agents. Importantly, simulation results demonstrate that DE-GWO is more suitable to apply in the scene with a small number of sensors. Therefore, the proposed in this paper outperforms other optimization algorithms for the gas emission inverse problem. DE-GWO can provide reliable estimation towards gas emission identification and positioning, which shows huge potential as the data analysis module of real-time monitoring and early warning system. 相似文献
409.
Simplified creation of polyester fabric supported Fe-based MOFs by an industrialized dyeing process: Conditions optimization, photocatalytics activity and polyvinyl alcohol removal 下载免费PDF全文
MIL-53(Fe) was successfully prepared and deposited on the surface carboxylated polyester (PET) fiber by an optimized conventional solvothermal or industrialized high temperature pressure exhaustion (HTPE) process to develop a PET fiber supported MIL-53(Fe) photocatalyst ([email protected]) for the degradation of polyvinyl alcohol (PVA) in water under light emitting diode (LED) visible irradiation. On the basis of several characterizations, [email protected] was tested for the photocalytic ability and degradation mechanism. It was found that temperature elevation significantly enhanced the formation and deposition of MIL-53(Fe) with better photocatalytic activity. However, higher temperature than 130°C was not in favor of its photocatalytic activity. Increasing the number of surface carboxyl groups of the modified PET fiber could cause a liner improvement in MIL-53(Fe) loading content and photocatalytic ability. High visible irradiation intensity also dramatically increased photocatalytic ability and PVA degradation efficiency of [email protected] Na2S2O8 was used to replace H2O2 as electron acceptor for further promoting PVA degradation in this system. [email protected] prepared by HTPE process showed higher MIL-53(Fe) loading content and slightly lower PVA degradation efficiency than that prepared by solvothermal process at the same conditions. These findings provided a practical strategy for the large-scale production of the supported MIL-53(Fe) as a photocatalyst in the future. 相似文献
410.
对拟负刚度阻尼减振结构的动力特性与减振效果进行了研究。首先,证明了采用拟负刚度控制方法时,结构响应与外荷载之间满足齐次性;其次,对拟负刚度阻尼减振结构的加速度放大系数和位移放大系数进行了研究,并与粘滞阻尼减振结构的加速度放大系数和位移放大系数进行了比较;最后,对地震荷载作用下拟负刚度阻尼减振结构的减振效果进行了分析。研究结果表明:当外荷载与结构的频率比大于1或结构的周期较长时,拟负刚度控制对结构绝对加速度的控制效果要好于粘滞阻尼减振结构的控制效果,对结构位移的控制效果要差于粘滞阻尼减振结构的控制效果。 相似文献