【摘 要】
:
Naturally complete mixing promotes the spontaneous redistribution of dissolved oxygen(DO),representing an ideal state for maintaining good water quality,and conducive to the biomineralization of organic matter.Water lifting aerators (WLAs) can extend the
【机 构】
:
Key Laboratory of Northwest Water Resource,Environment and Ecology,MOE,Xi’an University of Architect
论文部分内容阅读
Naturally complete mixing promotes the spontaneous redistribution of dissolved oxygen(DO),representing an ideal state for maintaining good water quality,and conducive to the biomineralization of organic matter.Water lifting aerators (WLAs) can extend the periods of complete mixing and increase the initial mixing temperature.To evaluate the influence of artificial-induced continuously mixing on dissolved organic matter (DOM) removal per-formance,the variations of DOM concentrations,optical characteristic,environmental fac-tors were studied after approaching the total mixing status via WLAs operation.During this process,the dissolved organic carbon reduced by 39.18%,whereas the permanganate index decreased by 20.47%.The optical properties indicate that the DOM became more endoge-nous and its molecular weight decreased.Based on the results of the Biolog EcoPlates,the microorganisms were maintained at a relatively high metabolic activity in the early stage of induced mixing when the mixing temperature was relatively high,whereas DOM declined at a high rate.With the continuous decrease in the water temperature,both the metabolic capacity and the diversity of aerobic microorganisms significantly decreased,and the rate of organic matter mineralization slowed down.The results of this study demonstrate that the artificial induced mixing largely enhanced the removal DOM performance by providing a long period of aerobic conditions and higher initial temperature.
其他文献
针对传统检测方法对低对比度和低信噪比弱小目标检测难度大的问题,提出一种基于梯度特征提取的弱小目标检测方法.首先利用弱小目标的各向同性及在梯度空间中的正负分布特性,提取两个方向梯度特征;然后通过改进的局部对比度算法分别抑制两个方向梯度特征的相似性,融合两个抑制相似性的方向梯度特征,增强目标同时抑制背景;最后通过自适应阈值对结果图进行分割,得到最终检测结果.实验结果表明,该算法不仅能够有效检测极低信噪比与对比度的目标,而且对复杂边缘场景具有很好的抑制效果,在信噪比、背景抑制因子以及检测率方面优于其他算法.
针对目前高速科研相机的常用Cameralink视频信号传输接口需专用数据采集卡连接到计算机导致系统灵活性不够的问题,提出一种基于FPGA的Cameralink接口Deca模式下高通量数据实时交互处理方案.硬件上利用编解码芯片完成Cameralink接口的数字图像采集和转换,输出LVDS信号.软件设计采用异步FIFO完成数据缓存及转换,解决跨时钟域的时序匹配疑难.FPGA设计结合Cameralink接口最大通量数据传输协议80 bits模式10 tap/8bit格式准确数据交互.通过Modelsim仿真验证
舰载激光武器将成为海上舰艇编队未来反导作战的利器.针对舰载激光武器反导作战问题,研究了典型反舰导弹特性以及激光反导作战的毁伤机理,并以仿真的方法对武器系统毁伤导弹的能力进行了定量分析.基于此,构建航母编队反导作战的典型场景,通过模拟仿真,进一步验证了舰载激光武器在不同状态下应对反舰导弹饱和攻击时的综合抗击能力,为实战条件下舰载激光武器的反导作战运用提供了参考.
针对高精度红外遥感成像的应用需求,提出了高空间分辨率、高噪声等效温差和大幅宽的中波/长波红外双谱段遥感成像技术方案,在太阳同步轨道获取地面目标的中波和长波红外辐射信息,谱段范围分别为3~5μm和8~12μm,中波红外谱段空间分辨率优于5 m,长波红外谱段空间分辨率优于10 m,幅宽大于20 km,噪声等效温差优于60 mK.根据噪声等效温差和光学传递函数等要求优化了光学系统指标参数,分析了二次成像同轴三反光学系统的冷光阑匹配原理,计算了光学系统初始结构参数,设计了光阑匹配型和出瞳匹配型中波/长波红外双谱段
针对秸秆焚烧区分布广且分散的特点,采用远程监控可为科学管理和安全生产提供极大帮助,可在发生火警、污染物排放等情况发生时,实时高效地处理突发事件并降低损失.基于上述需求,本文采用红外变焦距光学系统对焚烧区异常情况进行监视,变焦范围为34.5~77.5 mm,变焦系统基于库克三片式光学结构进行优化,优化后光学系统在成像距离为100~2000 m时地面景物分辨率优于1 m,系统信噪比(SNR)为34.53~70.34,变焦过程光学传递函数在奈奎斯特频率下均在0.4以上,实现了100~2000 m距离范围清晰成像
针对脉冲激光引信易受战场烟尘粒子后向散射回波干扰的问题,提出了一种基于小波分析的激光回波信号分离方法.通过Mie散射理论和蒙特卡洛方法,建立烟尘环境脉冲激光传输与接收理论模型,模拟含有噪声的激光回波信号.在回波信号分离过程中,首先通过基于阈值的小波去噪方法,去除激光回波信号噪声.再采用峰锐化算法提高回波信号的峰分辨率,解决波峰重叠度过高的问题.最后,对锐化后的回波信号进行连续小波变换,得到波峰峰位参数,并根据峰位值求解出最佳高斯拟合波形,得到峰强及峰宽信息.实验结果表明,利用连续小波变换求解出的回波峰位值
大容量FBG传感网络解调系统中,信号去噪是影响FBG传感系统精确解调的重要因素.为了提高解调精度,本文提出一种以改进变分模态分解结合可调节半软阈值方法用于处理光纤信号.变分模态分解(VMD)将输入的信号分解为给定数量K个固有模态数(IMF),设置错误的K值会导致性能下降.本文在VMD的基础上添加4条约束条件,使其自适应的选取K值并减少了VMD的计算量,然后用新阈值函数进行去噪处理,最后通过温度测试实验,得到波长与温度的线性相关系数,评估性能与应用价值.实验结果表明,本文函数在连续性以及信号还原度均取得良好
Polycyclic aromatic hydrocarbons (PAHs),as persistent toxic substances (PTS),have been widely monitored in coastal environment,including seawater and sediment.However,sci-entific monitoring methods,like ecological risk assessment and integrated biomarker
The greatest problem in conventional Fenton reaction is the slow production of ROS (reactive oxygen species) because of the inefficient Fe3+/Fe2+ conversion.Based on the extraordinary photo-response property of two-dimensional molybdenite (2DM),photogener
Nowadays,more people tend to spend their recreational time in large national parks,and trace metal(loid)s in soils have attracted long-term attention due to their possible harm to human health.To investigate the pollution levels,potential sources and heal