预制式柔性电缆终端弯曲运行电场特性研究

针对目前预制式柔性电缆终端弯曲运行引起的闪络、电腐蚀性击穿及绝缘屏蔽层断口处击穿三种故障,基于有限元数值仿真对工频电压下预制式柔性电缆终端弯曲角度与弯曲位置的电场分布进行模拟计算,找出了不同弯曲位置引发故障类型的机理,确定了弯曲角度对电场分布不均匀度的影响。结果表明:预制式柔性电缆终端故障类型与弯曲位置密切相关,当弯曲角度低于 30°时,电场分布变化较小,可保证预制式柔性电缆终端安全、稳定运行。     

北江流域抗生素污染水平和来源初探

北江是发源于湖南(武水)和江西(浈水),汇于广东韶关,流经广东全境并入海的三大河流之一。为了解整个北江抗生素污染情况,共设置44个采样点,并采集了河水及部分沉积物样品,较全面地分析了各样品中12种典型抗生素含量并初步探究了其污染来源。研究发现,包括北江源头在内的全河段均有抗生素的检出,5类抗生素在表层水和沉积物中的平均浓度分别为77.8 ng·L~(-1)和3.6 ng·g~(-1)。其中,大环内酯类污染最为严重,其含量范围为11.7~114.6 ng·L~(-1)和0~435.3 ng·g~(-1),远高于其他类抗生素。表层水中磺胺类的磺胺甲恶唑和氯霉素类的检出率达100%,其中以磺胺甲恶唑(14.7 ng·L~(-1))和阿奇霉素(25.0 ng·L~(-1))为主,而沉积物中以阿奇霉素(35.9 ng·g~(-1))、氧氟沙星(5.4 ng·g~(-1))和四环素(3.3 ng·g~(-1))为主。由于流域污染源种类和数量不同,各抗生素在北江中的分布也存在差异。表层水中抗生素含量水平表现为下游高于上中游,在沉积物中则主要集中于中、下游之间河段。这反映了人类活动强度对北江抗生素污染的直接影响。     

Nitrogen to phosphorus ratios of two understory plant species in response to nitrogen and phosphorus addition in tropical forest of southern China北大核心CSCD

The secondary tropical forests in southern China have suffered from frequent human disturbance and increasing high N deposition. In order to explore the nutrient limitation status in secondary tropical forests of South China, this 3-year field experiment of nitrogen (+N) and phosphorus (+P) addition investigated nitrogen (N) and phosphorus (P) concentrations of the aboveground tissue (leaf and branch) of two widely distributed understory native species Clerodendrum cyrtophyllum and Uvaria microcarpa in a secondary tropical forest of South China. The results showed that: 1) the N and P concentrations of the two species were significantly different (P < 0.001); N and P concentrations of different tissues in the same species were different; N&P addition greatly affected N and P concentrations in branch rather than new leaf and older leaf. 2) +N treatment had no significant effect on N or P concentrations of either species, but significantly decreased N:P ratios (P = 0.001), at the level of 9% for C. cyrtophyllum and 50% for U. microcarpa, respectively. 3) +P treatment had no significant effect on tissue N concentrations, but significantly increased plant P concentrations (P < 0.001), at 54% for C. cyrtophyllum and 88% for U. microcarpa, respectively; +P treatment significantly decreased plant N:P ratios (P < 0.001), at 28% and 60%, respectively. 4) The alterations of P concentrations of two species had significantly negative correlations with N:P alterations under +N/+P treatment (P < 0.001), suggesting that the alteration of P concentrations in plant tissue was the major driver for N:P alteration. Our results show that N and P addition would affect tissue N and P concentrations of the two species, with +P treatment having relatively greater effect on nutrient concentrations than +N treatment; the branch is more sensitive than new or older leaf in response to nutrient addition. Therefore, P availability may be the limiting factor for plant growth in the tropical forests.     

多相混输管道内水合物形成过程研究进展

针对由水合物造成的管道堵塞,特别是油-气-水多相混输领域水合物堵塞尤为严重的问题,系统调研了水合物在多相混输管道内形成机理的研究进展,着重介绍了富油相/富水相和富气相两个体系;基于水合物颗粒微观作用机理,详细阐述了水合物颗粒间的黏聚和水合物颗粒与管壁间的黏附作用;指出了多相混输管道内水合物形成过程的未来研究方向.     

黑碳气溶胶的测量方法对比研究

大气黑碳气溶胶主要有光学分析法、热学分析法以及热光结合分析法。利用苏州南门国控子站的碳分析数据,对三种黑碳浓度测量方法进行对比并分析其差异来源。主要得出以下结论:黑碳仪衰减系数无普适标准,热学分析法使有机碳碳化、元素碳不完全分离,TOT法协议设置存在争议是三种方法存在差异的主要原因。     

Forecasting of dissolved oxygen in the Guanting reservoir using an optimized NGBM (1,1) model

An optimized nonlinear grey Bernoulli model was proposed by using a particle swarm optimization algorithm to solve the parameter optimization problem. In addition, each item in the first-order accumulated generating sequence was set in turn as an initial condition to determine which alternative would yield the highest forecasting accuracy. To test the forecasting performance, the optimized models with different initial conditions were then used to simulate dissolved oxygen concentrations in the Guanting reservoir inlet and outlet (China). The empirical results show that the optimized model can remarkably improve forecasting accuracy, and the particle swarm optimization technique is a good tool to solve parameter optimization problems. What's more, the optimized model with an initial condition that performs well in in-sample simulation may not do as well as in out-of-sample forecasting.     

Forecasting of dissolved oxygen in the Guanting reservoir using an optimized NGBM (1,1) model

An optimized nonlinear grey Bernoulli model was proposed by using a particle swarm optimization algorithm to solve the parameter optimization problem. In addition, each item in the first-order accumulated generating sequence was set in turn as an initial condition to determine which alternative would yield the highest forecasting accuracy. To test the forecasting performance, the optimized models with different initial conditions were then used to simulate dissolved oxygen concentrations in the Guanting reservoir inlet and outlet (China). The empirical results show that the optimized model can remarkably improve forecasting accuracy, and the particle swarm optimization technique is a good tool to solve parameter optimization problems. What's more, the optimized model with an initial condition that performs well in in-sample simulation may not do as well as in out-of-sample forecasting.     

Phosphate removal from domestic wastewater using thermally modified steel slag

This study was performed to investigate the removal of phosphate from domestic wastewater using a modified steel slag as the adsorbent. The adsorption effects of alkalinity, salt, water,and thermal modification were investigated. The results showed that thermal activation at 800℃ for 1 hr was the optimum operation to improve the adsorption capacity. The adsorption process of the thermally modified slag was well described by the Elovich kinetic model and the Langmuir isotherm model. The maximum adsorption capacity calculated from the Langmuir model reached 13.62 mg/g. Scanning electron microscopy indicated that the surface of the modified slag was cracked and that the texture became loose after heating. The surface area and pore volume did not change after thermal modification. In the treatment of domestic wastewater, the modified slag bed(35.5 kg) removed phosphate effectively and operated for 158 days until the effluent P rose above the limit concentration of 0.5 mg/L. The phosphate fractionation method, which is often applied in soil research, was used to analyze the phosphate adsorption behavior in the slag bed. The analysis revealed that the total contents of various Ca–P forms accounted for 81.4%–91.1%, i.e., Ca10–P 50.6%–65.1%, Ca8–P 17.8%–25.0%,and Ca2–P 4.66%–9.20%. The forms of Al–P, Fe–P, and O–P accounted for only 8.9%–18.6%. The formation of Ca10–P precipitates was considered to be the main mechanism of phosphate removal in the thermally modified slag bed.     

不同土地利用方式下土壤重金属污染修复技术研究

土壤重金属污染的修复问题备受人们的关注,而在不同土地利用方式下受污染的土壤能够通过不同途径对人群健康构成威胁.国内外有关土壤重金属污染修复方法可分为生物修复、化学修复、物理修复以及联合修复,各修复方法适用范围差异较大.结合农业土壤、城市土壤以及矿区土壤中重金属的污染特征能够提出相应的更加合理的修复措施,最终为相关部门环境污染治理的决策提供理论依据.     

浙江省核电建设与环境安全的协调性分析

浙江省缺乏常规能源,在能源结构中,火电比重已经过大,加快核电发展,是我省电力发展的必然选择。继中国第一座自行设计、建造的核电站--秦山核电站之后,浙江省第二座核电站三门核电站的两台目前国内最先进的百万千瓦级压水堆技术机组也即将在2015年投入运营。加速核电建设不仅保证能源安全、调整能源结构,而且能实现节能减排、减少环境污染,建设环境友好型、资源节约型社会、推动经济社会又好又快发展。我省核电建设应通过加强核电站的安全检查、设计建设中安全措施保障、解决核电建设存在的相关问题和加强监测网络的建设等,促进浙江省的核电建设与环境安全协调发展。