污水处理厂污泥重金属含量及其浸出毒性分析——以上海某污水处理厂为例

为了评价污水处理厂污泥及其浸出液的潜在生态环境风险,以上海嘉定区某污水处理厂为例,采用硫酸/硝酸法和醋酸缓冲溶液法对污泥进行重金属总量和浸出毒性检测分析。同时,也研究了浸出液pH值、浸出时间及消解条件对浸出的影响。试验结果表明：1）污泥中Cu,Zn,Ni和Cr的含量分别是城市污泥中相应物质的平均含量的20,7.5,15和13倍,而Pb和Cd的含量与城市污泥的平均含量差不多;2）污泥中Cu与Cr主要以稳定形态存在,不同浸提方法下的浸出量相当,对于Zn和Ni,醋酸缓冲溶液的浸出量分别约为硫酸/硝酸溶液的22倍和18倍;3）浸出时间为20 h时浸出达到平衡,浸出液pH值对污泥重金属浸出能力的影响,因重金属元素种类的不同而存在较大差异,电热板消解和微波消解对浸出几乎没有影响;4）醋酸缓冲溶液制备的浸出液中,Ni的浸出质量浓度为16.3 mg/L,高于鉴别标准限值5 mg/L,而硫酸/硝酸浸提方法中重金属浸出浓度均未超过规定值。因此,该污水处理厂的污泥不适合卫生填埋,应积极寻求新技术对污泥进行合理处置并减少其潜在生态环境风险。     

质量流量计在原油集输系统中的应用

对油田企业分区块计量问题的现状进行了分析,指出了目前存在计量误差的主要原因,针对费希尔Ex8300质量流量计在使用中存在的缺陷,重新引进了新型CMF纯油质量流量计,报告了在多个原油集输站的试验情况,通过试验比对,找出了产生系统误差的根本原因,提出了在分队、分区块计量中质量流量计的应用是可行的,并告戒仪表管理人员对质量流量计的输入参数的动态变化要进行适时调整,以保证仪表的计量准确。     

随机正交变换法在隐私保持关联规则挖掘中的应用

隐私保护是当前数据挖掘领域中一个十分重要的研究方向。本文针对关联规则挖掘中如何保持隐私的问题,采用一种不依赖具体数据的随机正交变换方法,从而解决了在数据集容量很大的情况下,运算量大的问题,并使用传统隐私保护度评价方法与正交变换的方向隐私保护度相结合的方法评价变换的隐私保护度,进而使得结果更符合实际情况。理论分析和论证表明本文中的方法具有很好的隐私性、高效性和适用性。     

Sustaining cooperation in social dilemmas: Comparison of centralized punishment institutions

This study investigates two centralized punishment institutions for a linear public goods game. These institutions require a certain contribution level and sanction under-contributing players. The two differ in who, among those who do not meet this requirement, receive sanctions. In one institution, all violators are sanctioned, and in the other, only the worst violator(s) is sanctioned. Theoretically, the public goods game of the latter institution yields contributions equal to or greater than that of the former institution with the same requirement and sanction level. The results of an experiment support this theoretical prediction. However, there is a discrepancy between the theory and laboratory observations in that the institution with the theoretically optimal requirement did not yield the highest profit.     

Are impatient farmers more risk-averse? Evidence from a lab-in-the-field experiment in rural Uganda

Based on data from a field-experiment in rural Uganda, we show that impatient farmers are more risk-averse than patient farmers. We relied on a simplified version of the Convex Time Budget (CTB) method to elicit farmers’ time preferences and on an independent method for eliciting their risk-preferences. We report two important findings. First, we show that our simplified CTB method applied to farmers from Uganda replicates the key findings of Andreoni and Sprenger’s lab experiments that involved student subjects. Second, we establish the existence of a negative correlation between risk tolerance and impatience, based on two independent measures.     

Second-party and third-party punishment in a public goods experiment

We experimentally investigate whether third-party punishment is more effective than second-party punishment to increase public goods contribution. In our experiment, third parties first played the standard public goods game and then made punishment decisions as independent bystanders. We find that third parties punished more frequently, severely and less antisocially, resulting in a higher contribution level than that driven by second-party punishment. The third party’s exaggerated emotion towards free riders is proposed to explain their superior punishment effectiveness.     

基于计算实验的工程承发包模式选择机理分析

工程承发包模式是工程建设管理的重要组织方式，工程能否进行有效的目标控制及组织协调主要取决于承发包模式的选择。论文运用Multi-Agent方法建立了承发包模式选择的计算实验模型，通过具体数值算例分别分析了工程复杂度、业主能力及承包商水平对工程承发包模式选择路径的影响。研究结果表明：在工程复杂度越高、业主能力越弱情景下，业主选择DB模式的偏好就越大；提升承包商水平和培育有序的DB建设市场环境是提高业主选择DB模式偏好的重要途径。研究结论为业主的承发包模式选择、行业政策制订提供了参考依据。     

生物工程大实验课程改革与探讨

生物工程大实验是生物工程专业的一门重要的综合性实验课程,就当前生物工程大实验教学存在的几点问题,从实验内容、实验体系、实验方法、考核方式方面对生物工程大实验进行改革与探讨。