Herein the recent experiments performed by the authors on fabricated multi walled BN nanotubes and monoatomic BN graphene like nanosheets are reviewed The re suits are presented in several sections namely (i) method for high yield synthesis of thin, defect free BN nanotubes of only a few layers, with external diameters below 10 nm, (ii) verification of BN nanotube piezoelectrical behavior and its electrically induced thermal decomposition under combined resistive heating and electrical charging in a transmission electron microscope, (iii) the first direct measurements of the true tensile strength and Young's modulus of BN nanotubes, using newly developed nanotensile tests inside an electron microscope, the measured values were found to be similar to 30 GPa and similar to 900 GPa, respectively, and (iv) diverse kinetic processes taking place within the prepared monoatomic BN sheets (so called "white graphenes") affiliated with intensive knock on B and N atom displacements under high energy electron beam irradiation in an aberration corrected medium voltage high resolution transmission electron microscope
The civil and environmental decision-making processes are plagued with uncertain, vague, and incomplete information. Interval linear programming (ILP) is a widely applied mathematical programming method in assisting civil and environmental decision making under uncertainty. However, the existing ILP decision approach is found to be ineffective in generating operational schemes for practical decision support due to a lack of linkage between decision risk and system return. In addition, the interpretation of the ILP solutions represented as the lower and upper bounds of decision variables can cause problems of infeasibility and nonoptimality in the resulted implementation schemes. This study proposed a risk explicit ILP (REILP) approach to overcome the limitations of existing ILP approaches. The REILP explicitly reflects the tradeoffs between risk and system return for a decision-making problem under an interval-type uncertainty environment. A risk function was defined to enable finding solutions which maximize system return while minimizing system risk, hence leading to crisp solutions that are feasible and optimal for practical decision making. A numerical experiment on land-use decision making under total maximum daily load was conducted to illustrate the REILP approach. The model results show that the REILP approach is able to efficiently explore the interval uncertainty space and generate an optimal decision front that directly reflects the tradeoff between decision risks and system return, allowing decision makers to make effective decision based on the risk-reward information generated by the REILP modeling analysis.
In this study,investigations were conducted on residues of organochlorine pesticides(OCPs)in soils in Zhanjiang city,China.A total of 61 soil samples were collected from sites which were representative of the region for analysis of contents of OCPs.And with the aid of multi-variate geostatistics and GIS,residues and spatial distributions of 17 types of OCPs were analyzed.Results show that the 17 OCPs were detected.various in contents of allthe soil samples.HCHs and DDTs residues were below the criteria of the national standards for soil environment quality.Residue content of 13-HCH was the highest among HCHs,indicating some recent input of HCH to soils,while for DD T,no sign of new input was found.Principal component analysis demonstrated that the 17 OCPs in the soil may have 6 major contributors,corresponding respectively to the use of industrial HCH and lindane,plant diseases and insect pests and the pesticide use,etc.By means of ordinary Kriging interpolation,studies on spatial distribution of OCPs showed that the 17 OCPs varied greatly in spatial distribution between types.选取位于中国大陆最南端的湛江市为研究区域,对该市土壤进行了系统采样分析,测定了61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GI S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'-D DE检出率为100%,3种有机氯农药检出率在90%以上.其中六六六和滴滴涕残留较普遍,六六六未达到污染水平,有一个土壤样品滴滴涕超过国家土壤环境 质量一级标准.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.主成分分析显示17种有机氯农药町以由6个主成分 反映,分别对应于工业HCH和林丹的使用、农药使用习惯以及当地病虫害特点等.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.