Water shortage is a major issue in northern China. With the transfer of China＇s economic center from south to north, Circum-Bohai Economic Circle has gradually formed and developed as the third pole of China＇s econo...Water shortage is a major issue in northern China. With the transfer of China＇s economic center from south to north, Circum-Bohai Economic Circle has gradually formed and developed as the third pole of China＇s economy after Yangtze River Delta and Pearl River Delta, the problem of water has inevitably become more and more serious. South-to-North Water Diversion and Sea Water Desalination are helpful to solve this dilemma, but some difficulties appeared during the course of the two projects. By contrast, sea ice desalination can be considered as a third way to alleviate freshwater crisis in Bohai Rim. Firstly, the amount of sea ice in Bohai Sea is as much as 1.27 billion m3 even in normal years. Then the salinity of sea ice is only 1/4 to 1/7 as that of sea water. And furthermore, desalinized water of sea ice can meet national water quality standard for drinking. Purposely use the abundant sea ice resources as water source for industry, agriculture and living is very likely to open a new path for the solution of freshwater shortage, which can promote rapid and healthy development of Circum-Bohai Economic Circle.展开更多
Purpose CMOS pixel sensor has become extremely attractive for future high-performance tracking devices.It has been proposed for the vertex detector at the Circular Electron Positron Collider,which will allow precision...Purpose CMOS pixel sensor has become extremely attractive for future high-performance tracking devices.It has been proposed for the vertex detector at the Circular Electron Positron Collider,which will allow precision measurements of the properties of the Higgs boson.To meet the stringent requirements for low power consumption,it is necessary to optimize the pixel sensor diode geometry to reach a high charge-over-capacitance ratio that allows reduction in analog power consumption.Methods Collection electrode size and footprint are two critical elements in sensor diode geometry and have deciding impacts on the charge collection performance.A prototype CMOS pixel sensor,named JadePix-1,has been developed with pixel sectors implemented with different electrode sizes and footprints,and its charge collection performance has been characterized with radioactive sources.Results Charge-to-voltage conversion gains for pixel sectors under test have been calibrated with low-energy X-rays.Characterization results have been obtained for equivalent noise charge(below 10e−),charge collection efficiency(around 40%),charge-over-capacitance ratio(above 0.015 V)and signal-to-noise ratio(higher than 55).Conclusion Small collection electrode size and large footprint are preferred to achieve high charge-over-capacitance ratio that promises low analog power consumption.Ongoing studies on sensor performance before and after irradiation,combined with this work,will conclude the diode geometry optimization.展开更多
Purpose To complement and ensure redundancy in the endcap muon system of the Compact Muon Solenoid(CMS)detector and to extend the Resistive Plate Chamber(RPC)system coverage,improved RPCs(iRPCs)with either orthogonal ...Purpose To complement and ensure redundancy in the endcap muon system of the Compact Muon Solenoid(CMS)detector and to extend the Resistive Plate Chamber(RPC)system coverage,improved RPCs(iRPCs)with either orthogonal layer strips with one-end electronics or single layer strips with two-end electronics providing more precise time measurement will be installed in the very forward pseudorapidity region of|η|<2.4.The iRPC readout system needs to support twodimensional(2D)or two-end readout.In addition,it must combine detector data with Timing,Trigger and fast Control(TTC)and Slow Control(SC)into one data stream over a bi-directional optical link with a line rate of 4.8 Gb/s between the Front-End Electronics(FEE)and the Back-End Electronics(BEE).To fulfill these requirements,a prototype BEE for the iRPC 2D chamber has been researched and designed.Methods A Micro-Telecommunication and Computing Architecture(μTCA)-based processing card was designed in this study to establish a prototype system together with aμTCA crate.The Giga-Bit Transceiver(GBT)protocol is integrated to provide bi-directional communication between the FEE and BEE.A server is connected with the BEE by a Gigabit Ethernet(GbE)link for SC and a 10-GbE link for Data AcQuisition(DAQ).Results The Bit Error Rate(BER)test of the back-end board and a joint test with the iRPC 2D prototype chamber were performed.ABERof less than 1.331×10−16 was obtained.The timemeasurement with a resolution of 3.05 nswas successfully realized,and detector efficiencies of 97.7%for longitudinal strips and 96.0%for orthogonal strips were measured.Test results demonstrate the correctness and reliability of the prototype BEE.Conclusion The BEE prototype satisfies the requirements for the iRPC 2D chamber,and it worked stably and reliably during a long-term joint test run.展开更多
The mechanical behavior of seven different carbon nanotube(CNT)X-junctions with a varying number of bonds was investigated through molecular dynamics simulations.The X-junctions are composed of two(6,0)single-walled c...The mechanical behavior of seven different carbon nanotube(CNT)X-junctions with a varying number of bonds was investigated through molecular dynamics simulations.The X-junctions are composed of two(6,0)single-walled carbon nanotubes(SWNTs)created via vibration-assisted heat welding.The junctions,containing anywhere between one and seven bonds,are subject to uniaxial tensile,shear and torsional strain,and then the stiffness values are determined for each case.When subjected to tensile and shear strain,both the arrangement and orientation of bonds are found to affect the stiffness of junctions more substantially than the number of bonds,bond length or bond order.Surprisingly,anisotropic shear behavior is observed in the X-junctions,which can be attributed to the junction’s bond orientation.Also,the stiffness of X-junctions tested under an applied torque(torsion)differs from the stiffness under tensile and shear strain,however,in that it is more substantially affected by the number of bonds present in the junction than by any other property.展开更多
文摘Water shortage is a major issue in northern China. With the transfer of China＇s economic center from south to north, Circum-Bohai Economic Circle has gradually formed and developed as the third pole of China＇s economy after Yangtze River Delta and Pearl River Delta, the problem of water has inevitably become more and more serious. South-to-North Water Diversion and Sea Water Desalination are helpful to solve this dilemma, but some difficulties appeared during the course of the two projects. By contrast, sea ice desalination can be considered as a third way to alleviate freshwater crisis in Bohai Rim. Firstly, the amount of sea ice in Bohai Sea is as much as 1.27 billion m3 even in normal years. Then the salinity of sea ice is only 1/4 to 1/7 as that of sea water. And furthermore, desalinized water of sea ice can meet national water quality standard for drinking. Purposely use the abundant sea ice resources as water source for industry, agriculture and living is very likely to open a new path for the solution of freshwater shortage, which can promote rapid and healthy development of Circum-Bohai Economic Circle.
基金the National Natural Science Foundation of China(Nos.11505207,11573028)the State Key Laboratory of Particle Detection and Electronics,the CAS Center for Excellence in Particle Physics(CCEPP)and the IHEP Innovation Fund and the International Partnership Program of Chinese Academy of Sciences.
文摘Purpose CMOS pixel sensor has become extremely attractive for future high-performance tracking devices.It has been proposed for the vertex detector at the Circular Electron Positron Collider,which will allow precision measurements of the properties of the Higgs boson.To meet the stringent requirements for low power consumption,it is necessary to optimize the pixel sensor diode geometry to reach a high charge-over-capacitance ratio that allows reduction in analog power consumption.Methods Collection electrode size and footprint are two critical elements in sensor diode geometry and have deciding impacts on the charge collection performance.A prototype CMOS pixel sensor,named JadePix-1,has been developed with pixel sectors implemented with different electrode sizes and footprints,and its charge collection performance has been characterized with radioactive sources.Results Charge-to-voltage conversion gains for pixel sectors under test have been calibrated with low-energy X-rays.Characterization results have been obtained for equivalent noise charge(below 10e−),charge collection efficiency(around 40%),charge-over-capacitance ratio(above 0.015 V)and signal-to-noise ratio(higher than 55).Conclusion Small collection electrode size and large footprint are preferred to achieve high charge-over-capacitance ratio that promises low analog power consumption.Ongoing studies on sensor performance before and after irradiation,combined with this work,will conclude the diode geometry optimization.
基金the National Key Programme for S&T Research and Development(Grant NO.:2016YFA0400104)the National Natural Science Foundation of China(No.12035018)the IHEP Innovation Fund(Y9545150U2).
文摘Purpose To complement and ensure redundancy in the endcap muon system of the Compact Muon Solenoid(CMS)detector and to extend the Resistive Plate Chamber(RPC)system coverage,improved RPCs(iRPCs)with either orthogonal layer strips with one-end electronics or single layer strips with two-end electronics providing more precise time measurement will be installed in the very forward pseudorapidity region of|η|<2.4.The iRPC readout system needs to support twodimensional(2D)or two-end readout.In addition,it must combine detector data with Timing,Trigger and fast Control(TTC)and Slow Control(SC)into one data stream over a bi-directional optical link with a line rate of 4.8 Gb/s between the Front-End Electronics(FEE)and the Back-End Electronics(BEE).To fulfill these requirements,a prototype BEE for the iRPC 2D chamber has been researched and designed.Methods A Micro-Telecommunication and Computing Architecture(μTCA)-based processing card was designed in this study to establish a prototype system together with aμTCA crate.The Giga-Bit Transceiver(GBT)protocol is integrated to provide bi-directional communication between the FEE and BEE.A server is connected with the BEE by a Gigabit Ethernet(GbE)link for SC and a 10-GbE link for Data AcQuisition(DAQ).Results The Bit Error Rate(BER)test of the back-end board and a joint test with the iRPC 2D prototype chamber were performed.ABERof less than 1.331×10−16 was obtained.The timemeasurement with a resolution of 3.05 nswas successfully realized,and detector efficiencies of 97.7%for longitudinal strips and 96.0%for orthogonal strips were measured.Test results demonstrate the correctness and reliability of the prototype BEE.Conclusion The BEE prototype satisfies the requirements for the iRPC 2D chamber,and it worked stably and reliably during a long-term joint test run.
基金supported by NSF REU through grants(CMMI-0928094 and BRIGE-EEC-0926885)the Swanson School of Engineering at the University of Pittsburgh.
文摘The mechanical behavior of seven different carbon nanotube(CNT)X-junctions with a varying number of bonds was investigated through molecular dynamics simulations.The X-junctions are composed of two(6,0)single-walled carbon nanotubes(SWNTs)created via vibration-assisted heat welding.The junctions,containing anywhere between one and seven bonds,are subject to uniaxial tensile,shear and torsional strain,and then the stiffness values are determined for each case.When subjected to tensile and shear strain,both the arrangement and orientation of bonds are found to affect the stiffness of junctions more substantially than the number of bonds,bond length or bond order.Surprisingly,anisotropic shear behavior is observed in the X-junctions,which can be attributed to the junction’s bond orientation.Also,the stiffness of X-junctions tested under an applied torque(torsion)differs from the stiffness under tensile and shear strain,however,in that it is more substantially affected by the number of bonds present in the junction than by any other property.
