为解决传统粉尘监测设备的监测点少、维护成本高等问题,基于3G网络,提出一种分布式粉尘浓度监测系统。采用依据微电荷监测原理实现的粉尘检测器作为前端探头,将被测区域内的粉尘量转化为4 m A^20 m A的电流信号。通过高精度模数转换器...为解决传统粉尘监测设备的监测点少、维护成本高等问题,基于3G网络,提出一种分布式粉尘浓度监测系统。采用依据微电荷监测原理实现的粉尘检测器作为前端探头,将被测区域内的粉尘量转化为4 m A^20 m A的电流信号。通过高精度模数转换器将电流信号转换成数字信号,再利用现场可编程门阵列模块将采集的粉尘浓度值、继电器开关信号等数据组成协议帧,通过3G网络将数据传送至数据中心。应用结果表明,该系统能够实现粉尘浓度实时显示、采集数据保存及历史数据回放功能,具有监测精度高、维护成本低、操作安全等特点。展开更多
Bacterial community structure and iron corrosion were investigated for simulated drinking water distribution systems（DWDSs） composed of annular reactors incorporating three different treatments： ozone, biologically...Bacterial community structure and iron corrosion were investigated for simulated drinking water distribution systems（DWDSs） composed of annular reactors incorporating three different treatments： ozone, biologically activated carbon and chlorination（O3-BAC-Cl2）;ozone and chlorination（O3-Cl2）; or chlorination alone（Cl2）. The lowest corrosion rate and iron release, along with more Fe3O4 formation, occurred in DWDSs with O3-BAC-Cl2 compared to those without a BAC filter. It was verified that O3-BAC influenced the bacterial community greatly to promote the relative advantage of nitrate-reducing bacteria（NRB）in DWDSs. Moreover, the advantaged NRB induced active Fe（III） reduction coupled to Fe（II） oxidation, enhancing Fe3O4 formation and inhibiting corrosion. In addition, O3-BAC pretreatment could reduce high-molecular-weight fractions of dissolved organic carbon effectively to promote iron particle aggregation and inhibit further iron release. Our findings indicated that the O3-BAC treatment, besides removing organic pollutants in water, was also a good approach for controlling cast iron corrosion and iron release in DWDSs.展开更多
A novel distributed weak fiber Bragg gratings （FBGs） vibration sensing system has been designed to overcome the disadvantages of the conventional methods for optical fiber sensing networking, which are： low signal ...A novel distributed weak fiber Bragg gratings （FBGs） vibration sensing system has been designed to overcome the disadvantages of the conventional methods for optical fiber sensing networking, which are： low signal intensity in the usually adopted time-division multiplexing （TDM） technology, insufficient quantity of multiplexed FBGs in the wavelength-division multiplexing （WDM） technology, and that the mixed WDM/TDM technology measures only the physical parameters of the FBG locations but cannot perform distributed measurement over the whole optical fiber. This novel system determines vibration events in the optical fiber line according to the intensity variation of the interference signals between the adjacent weak FBG reflected signals and locates the vibration points accurately using the TDM technology. It has been proven by tests that this system performs vibration signal detection and demodulation in a way more convenient than the conventional methods for the optical fiber sensing system. It also measures over the whole optical fiber, therefore, distributed measurement is fulfilled, and the system locating accuracy is up to 20m, capable of detecting any signals of whose drive signals lower limit voltage is 0.2 V while the frequency range is 3 Hz - 1 000 Hz. The system has the great practical significance and application value for perimeter surveillance systems.展开更多
文摘为解决传统粉尘监测设备的监测点少、维护成本高等问题,基于3G网络,提出一种分布式粉尘浓度监测系统。采用依据微电荷监测原理实现的粉尘检测器作为前端探头,将被测区域内的粉尘量转化为4 m A^20 m A的电流信号。通过高精度模数转换器将电流信号转换成数字信号,再利用现场可编程门阵列模块将采集的粉尘浓度值、继电器开关信号等数据组成协议帧,通过3G网络将数据传送至数据中心。应用结果表明,该系统能够实现粉尘浓度实时显示、采集数据保存及历史数据回放功能,具有监测精度高、维护成本低、操作安全等特点。
基金supported by the National Natural Science Foundation of China(Nos.51308529,51290281)
文摘Bacterial community structure and iron corrosion were investigated for simulated drinking water distribution systems（DWDSs） composed of annular reactors incorporating three different treatments： ozone, biologically activated carbon and chlorination（O3-BAC-Cl2）;ozone and chlorination（O3-Cl2）; or chlorination alone（Cl2）. The lowest corrosion rate and iron release, along with more Fe3O4 formation, occurred in DWDSs with O3-BAC-Cl2 compared to those without a BAC filter. It was verified that O3-BAC influenced the bacterial community greatly to promote the relative advantage of nitrate-reducing bacteria（NRB）in DWDSs. Moreover, the advantaged NRB induced active Fe（III） reduction coupled to Fe（II） oxidation, enhancing Fe3O4 formation and inhibiting corrosion. In addition, O3-BAC pretreatment could reduce high-molecular-weight fractions of dissolved organic carbon effectively to promote iron particle aggregation and inhibit further iron release. Our findings indicated that the O3-BAC treatment, besides removing organic pollutants in water, was also a good approach for controlling cast iron corrosion and iron release in DWDSs.
基金This work is supported by the Major Program of the National Natural Science Foundation of China （Grant No. 61290311）.
文摘A novel distributed weak fiber Bragg gratings （FBGs） vibration sensing system has been designed to overcome the disadvantages of the conventional methods for optical fiber sensing networking, which are： low signal intensity in the usually adopted time-division multiplexing （TDM） technology, insufficient quantity of multiplexed FBGs in the wavelength-division multiplexing （WDM） technology, and that the mixed WDM/TDM technology measures only the physical parameters of the FBG locations but cannot perform distributed measurement over the whole optical fiber. This novel system determines vibration events in the optical fiber line according to the intensity variation of the interference signals between the adjacent weak FBG reflected signals and locates the vibration points accurately using the TDM technology. It has been proven by tests that this system performs vibration signal detection and demodulation in a way more convenient than the conventional methods for the optical fiber sensing system. It also measures over the whole optical fiber, therefore, distributed measurement is fulfilled, and the system locating accuracy is up to 20m, capable of detecting any signals of whose drive signals lower limit voltage is 0.2 V while the frequency range is 3 Hz - 1 000 Hz. The system has the great practical significance and application value for perimeter surveillance systems.
