This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance senso...This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance sensor(ATCS)and a cross-correlation flow meter(CFM)with a center body is proposed and experimentally evaluated.The ATCS is designed for water holdup measurement,whereas the CFM with a center body is proposed to obtain the mixture velocity.Then,a drift-flux model based on flow patterns is established to predict the individual-phase superficial velocity of oil-in-water flows.Results show that the ATCS possesses high resolution in water holdup measurement and that flow pattern information can be deduced from its signal through nonlinear time series analysis.The CFM can enhance the correlation of upstream and downstream signals and simplify the relationship between the cross-correlation velocity and mixture velocity.On the basis of the drift-flux model,individual-phase superficial velocities can be predicted with high accuracy for different flow patterns.展开更多
This paper reviews programs and projects that are elements of the strategy to boost crop production in general and grain legumes in particular in Nigeria. The objective is to bring to fore the neglect of grain legumes...This paper reviews programs and projects that are elements of the strategy to boost crop production in general and grain legumes in particular in Nigeria. The objective is to bring to fore the neglect of grain legumes production in such strategies and for improved understanding of the need to implement grain legumes specific programs for enhanced food security in the country. The paper reiterates that grain legumes were neglected in most of the strategies for increased crop production which presented enormous challenges and reflects largely the inbalance in the policies for the attainment of food self-sufficiency and food security in the country The paper gives an overview of the programs and projects, and reviews the output of grain legumes during the period （1970-2007）. It submits that the activities of some research institutes and the presidential initiative on vegetable oil development program had positive impact on the output of legumes which is an added impetus for the need to establish grain legumes specific research institutes and programs for further productivity increases. Constraints identified by the paper include： poverty, storage systems, among others. It itemizes prospects and current challenges for grain legume crop sub-sector in Nigeria.展开更多
A tide of innovation is sweeping across China.For three years China has led the world in patent applications,carving a foothold in modern fields like high-speed trains,machinery exports and technical standards.
Harvesting mechanical energy from our surroundings to acquire a steady and high power output has attracted intensive interest due to the fast development of portable electronics. In this work the disk-structured tribo...Harvesting mechanical energy from our surroundings to acquire a steady and high power output has attracted intensive interest due to the fast development of portable electronics. In this work the disk-structured triboelectric nanogenerator （TENG） was prepared based on the mature printed drcuit board （PCB） technology and the composite structure for effectively improving the utilization in space. A narrow grating of 1~ was designed to produce high output. Operated at a rotation rate of 1,000 rpm, the TENG produces a high output power density of 267 mW/cm2 （total power output of 25.7 W） at a matched load of 0.93 MfZ After introducing a transformer, the output power can be managed so that it can be directly used to charge a battery for a smart phone. With the PCB production technology, fabrication of high performance TENG at low cost and large-scale becomes feasible.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51527805 and 11572220)
文摘This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance sensor(ATCS)and a cross-correlation flow meter(CFM)with a center body is proposed and experimentally evaluated.The ATCS is designed for water holdup measurement,whereas the CFM with a center body is proposed to obtain the mixture velocity.Then,a drift-flux model based on flow patterns is established to predict the individual-phase superficial velocity of oil-in-water flows.Results show that the ATCS possesses high resolution in water holdup measurement and that flow pattern information can be deduced from its signal through nonlinear time series analysis.The CFM can enhance the correlation of upstream and downstream signals and simplify the relationship between the cross-correlation velocity and mixture velocity.On the basis of the drift-flux model,individual-phase superficial velocities can be predicted with high accuracy for different flow patterns.
文摘This paper reviews programs and projects that are elements of the strategy to boost crop production in general and grain legumes in particular in Nigeria. The objective is to bring to fore the neglect of grain legumes production in such strategies and for improved understanding of the need to implement grain legumes specific programs for enhanced food security in the country. The paper reiterates that grain legumes were neglected in most of the strategies for increased crop production which presented enormous challenges and reflects largely the inbalance in the policies for the attainment of food self-sufficiency and food security in the country The paper gives an overview of the programs and projects, and reviews the output of grain legumes during the period （1970-2007）. It submits that the activities of some research institutes and the presidential initiative on vegetable oil development program had positive impact on the output of legumes which is an added impetus for the need to establish grain legumes specific research institutes and programs for further productivity increases. Constraints identified by the paper include： poverty, storage systems, among others. It itemizes prospects and current challenges for grain legume crop sub-sector in Nigeria.
文摘A tide of innovation is sweeping across China.For three years China has led the world in patent applications,carving a foothold in modern fields like high-speed trains,machinery exports and technical standards.
文摘Harvesting mechanical energy from our surroundings to acquire a steady and high power output has attracted intensive interest due to the fast development of portable electronics. In this work the disk-structured triboelectric nanogenerator （TENG） was prepared based on the mature printed drcuit board （PCB） technology and the composite structure for effectively improving the utilization in space. A narrow grating of 1~ was designed to produce high output. Operated at a rotation rate of 1,000 rpm, the TENG produces a high output power density of 267 mW/cm2 （total power output of 25.7 W） at a matched load of 0.93 MfZ After introducing a transformer, the output power can be managed so that it can be directly used to charge a battery for a smart phone. With the PCB production technology, fabrication of high performance TENG at low cost and large-scale becomes feasible.
