Investigations on residues of organochlorine pesticides(OCPs) in soils in Huizhou,China were conducted.A total of 42 soil samples were collected from sites representative of the region for analysis of contents of OCPs.And with the aid of multi-variate geostatistics and GIS,residue and spatial distribution of 17 types of OCPs were analyzed.Results show that the 17 OCPs were detected,various in content in all the soil samples.HCHs and DDTs residues were detected,but below the criteria of the national standards for soil environment quality.Residue content of beta-HCH was the highest among HCHs,which implied some recent input of HCH to soils,while for DDT,no sign of new input was found.Compared with other regions in the country,Huizhou city was lower in soil HCH and DDT content.Principal component analysis demonstrated that the above-said 17 OCPs in the soil may have 5 major contributors,corresponding respectively to industrial use of HCH,natural factors,use of lindane,use of heptamul and use of Drinox.By means of ordinary Kriging interpolation,spatial distribution of OCPs was studied with results indicating that the 17 OCPs variaed greatly in spatial distribution between types选取位于珠江三角洲的惠州市为研究区域,对该市土壤进行了系统采样分析,测定了42个表层土壤样品中的17种有机氯农药的含量.利用多元地统计和GIS相 结合的方法,研究了17种有机氯农药的残留状况及空间分布情况.结果表明,17种有机氯农药在42个土壤样品中均有不同程度的检出,其中p,p′-DDE 检出率为100%,3种有机氯农药检出率在90%以上,6种有机氯农药的检出率在80%以上.其中六六六和滴滴涕残留较普遍,但并未达到污染水平.分析显 示,近期可能仍有新的六六六输入土壤环境,而滴滴涕则主要来自过去施用农药的残留.与国内其他地区比较,惠州市土壤HCH和DDT含量处于较低水平.主成 分分析显示上述17种有机氯农药可以由5个主成分反映,分别对应于工业HCH的使用,自然因素,林丹的使用以及七氯和艾氏剂等农药的使用.采用克里格插值 法对有机氯农药在研究区的空间分布进行了研究,结果表明不同有机氯农药在研究区分布存在很大差异
Hwang C, Christianson AD, Lawrence JM, Bauer ED, Goremychkin EA, Kolesnikov AI, Trouw F, Ronning F, Thompson JD, Lumsden MD, et al.Neutron scattering and scaling behavior in URu2 Zn20 and YbFe2 Zn20. Physical Review B - Condensed Matter and Materials Physics. 2010;(18).
In this paper, we revisit the point-in-polyhedron problem. After reviewing previous work, we develop further insight into the problem. We then claim that, for a given testing point and a three-dimensional polyhedron, a single determining triangle can be found which suffices to determine whether the point is inside or outside the polyhedron.This work can be considered to be an extension and implementation of Horn's work, which inspired us to propose a theorem for obtaining determining triangles. Building upon this theorem, algorithms are then presented, implemented, and tested. The results show that although our code has the same asymptotic time efficiency as commonly used octree-based ray crossing methods, in practice it is usually several times and sometimes more than ten times faster, while other costs such as preprocessing time and memory requirements remain the same.The ideas proposed in this paper are simple and general. They thus extend naturally to multi-material models, i.e., polyhedrons subdivided into smaller regions by internal boundaries. (C) 2010 Elsevier Ltd. All rights reserved.
In this paper, we revisit the point-in-polyhedron problem. After reviewing previous work, we develop further insight into the problem. We then claim that, for a given testing point and a three-dimensional polyhedron, a single determining triangle can be found which suffices to determine whether the point is inside or outside the polyhedron.This work can be considered to be an extension and implementation of Horn's work, which inspired us to propose a theorem for obtaining determining triangles. Building upon this theorem, algorithms are then presented, implemented, and tested. The results show that although our code has the same asymptotic time efficiency as commonly used octree-based ray crossing methods, in practice it is usually several times and sometimes more than ten times faster, while other costs such as preprocessing time and memory requirements remain the same.The ideas proposed in this paper are simple and general. They thus extend naturally to multi-material models, i.e., polyhedrons subdivided into smaller regions by internal boundaries. (C) 2010 Elsevier Ltd. All rights reserved.
Applications using simulation-optimization approaches are often limited in practice because of the high computational cost associated with executing the simulation-optimization analysis. This research proposes a nonlinearity interval mapping scheme (NIMS) to overcome the computational barrier of applying the simulation-optimization approach for a waste load allocation analysis. Unlike the traditional response surface methods that use response surface functions to approximate the functional form of the original simulation model, the NIMS approach involves mapping the nonlinear input-output response relationship of a simulation model into an interval matrix, thereby converting the original simulation-optimization model into an interval linear programming model. By using the risk explicit interval linear programming algorithm and an inverse mapping scheme to implicitly resolve nonlinearity in the interval linear programming model, the NIMS approach efficiently obtained near-optimal solutions of the original simulation-optimization problem. The NIMS approach was applied to a case study on Wissahickon Creek in Pennsylvania, with the objective of finding optimal carbonaceous biological oxygen demand and ammonia (NH4) point source waste load allocations, subject to daily average and minimum dissolved oxygen compliance constraints at multiple points along the stream. First, a simulation-optimization model was formulated for this case study. Next, a genetic algorithm was used to solve the problem to produce reference optimal solutions. Finally, the simulation-optimization model was solved using the proposed NIMS, and the obtained solutions were compared with the reference solutions to demonstrate the superior computational efficiency and solution quality of the NIMS.
A facile way to fabricate highly efficient organic light emitting devices (OLEDs) with insulator MnO as an electron injecting and transporting material was devised, which eliminates the problem of the oxidation of reactive dopants. The power efficiency of 1.1 lm/W by inserting 3-nm-thick MnO as the electron injecting layer was obtained, higher than the 0.8 lm/W efficiency for the reference device with 0.5-nm-thick LiF. A thermal co-evaporation layer containing 10% weight of MnO and tris(8-hydroxyquinolato) aluminum (Alq(3)) as the electron transporting layer showed more efficient electron transport ability, with turn-on voltage of 3.8 V, lower than 7.4 V for the intrinsic Alq3. Meanwhile, the insertion of thin MnO layer between organic photoactive layer and inorganic metal electrode significantly improved performance and stability of organic solar cell compared to device without it. The power conversion efficiency (PCE) of 2.91% by inserting 3-nm-thick MnO was obtained, higher than the 0.91% efficiency for the device without it, and 2.59% for the device with 0.5-nm-thick LiF. Charge transport of rhenium trioxide (ReO(3)) in organic electronic devices was investigated. The hole injection/transport was blocked and the electron injection/transport was enhanced with doping of ReO(3) in organic electronic devices. Thus the charge balance and efficiency of the OLED were improved, 2.7 cd/A of current efficiency (CE) at 20 mA/cm(2) for the device with ReO(3) was higher than 1.5 cd/A for the device without it. In the case of organic photovoltaic cells (OPV), the open-circuit voltage (V(oc)), 0.58 V, was higher compared to the device without ReO(3) (0.44 V) due to the improvement of interface properties. The PCE was increased to 2.27% by the combination of ReO(3) (increasing V(oc)) with poly(3,4-ethylene dioxythiophene): poly(styrene-sulfonate) (PEDOT:PSS) (improve hole transport to increase J(sc)) on the modification of the anode, higher than 1.85% for the device without ReO(3).
Researches on HO(x) radical chemistry would provide theoretical support for understanding the global climate change and regional air pollution control. At present stage, comprehensive field campaign including HO(x) radial measurements is one of the critical approaches to advance it. However, due to the very short lifetime and extremely low concentration of HO(x) in the atmosphere, direct measurement of HO(x) radical is one of most challenged works in atmospheric chemistry. This paper reviews the direct measurement techniques of the HO(x) radical, summarizes the observed dynamics range of its concentrations, introduces the current schematic diagram of the HO(x) radical chemistry and the important contributions from previous field studies, and discusses the main scientific questions that need further researches. Besides, the progress of the HO(x) radical chemistry in China is reviewed, and several potentially important research directions are pointed out.