A 1×8 multimode interference power splitter with multimode input/output waveguides in SOI material is designed by the beam propagation method and fabricated by the inductive coupled plasma etching technology for...A 1×8 multimode interference power splitter with multimode input/output waveguides in SOI material is designed by the beam propagation method and fabricated by the inductive coupled plasma etching technology for use in fiber optics communication systems.The fabricated device exhibits low loss and good coupling uniformity.The excess loss is lower than 0 8dB,and the uniformity is 0 45dB at the wavelength of 1550nm.Moreover,the polarization dependent loss is lower than 0 7dB at 1550nm.The device size is only 2mm×10mm.展开更多
A novel framework of which combines smart antennas multiple antenna systems, （SA） with multiple-input multiple-output （MIMO） at the receiver, is proposed. The uplink SA-MIMO system is investigated. The joint optim...A novel framework of which combines smart antennas multiple antenna systems, （SA） with multiple-input multiple-output （MIMO） at the receiver, is proposed. The uplink SA-MIMO system is investigated. The joint optimization problem corresponding to the uplink capacity of the single-user SA-MIMO system is deduced. Then the closedform expression of the capacity is obtained in the case of equal power allocation and the same direction-of-arrivals （DOAs） from different transmit antennas at the same antenna array, and an upper bound of the capacity is also given in the case of different DOAs at the same antenna array. After that, for the general case, a suboptimal method for the capacity optimization problem is presented. Some numerical results are also given to compare the capacities of conventional MIMO and SA-MIMO systems and show that the proposed method is viable.展开更多
The secrecy rate of limited feedback beamforming is studied for a Multiple-Input Single-Output(MISO) wiretap channel with a multi-antenna eavesdropper.We first obtain the secrecy rate of limited feedback beamforming a...The secrecy rate of limited feedback beamforming is studied for a Multiple-Input Single-Output(MISO) wiretap channel with a multi-antenna eavesdropper.We first obtain the secrecy rate of limited feedback beamforming achieved at the legitimate receiver.We then derive a lower bound for the asymptotic secrecy rate in the large system limit.From this bound,we observe a threshold for the ratio of eavesdrop antennas to transmit antennas to obtain a positive secrecy rate.We further show that the secrecy rate loss due to limited feedback decays with the number of feedback bits per transmit antenna.展开更多
According to the formation of shock wave resulting from coal and gas outburst, the gas flow of coal and gas outburst was transformed from an unsteady flow to a steady one based on selected appropriate reference coordi...According to the formation of shock wave resulting from coal and gas outburst, the gas flow of coal and gas outburst was transformed from an unsteady flow to a steady one based on selected appropriate reference coordinates, and the mathematical expressions were then established by applying mass conservation, momentum conservation equation, and energy conservation equation. On this basis, analyzed gas flow mitigation of variable cross-section area and the outburst intensity, and the relations between cross-section area, velocity, and density; the relations between overpressures and outburst intensity were deduced. Furthermore, shock waves resulting from coal and gas outburst and outburst intensity were measured by experimental setup, the overpressure and outburst intensity of different gas pressures were obtained, and the similar conditions of the experiment were numerically simulated. The averaged overpressure and gas flow velocity of variable cross-section under different gas pressures were numerically derived. The results show that the averaged overpressure and outburst intensity obtained from simulation are in good agreement with the experimental results. Moreover, the gas flow velocity of variable cross-sections approximates to the theoretical analysis.展开更多
Leaching of blended slag(BS)was investigated in a microwave oven using hydrogen peroxide and acetic acid.The BSwas a mixture of converter and flash furnace slag containing51%Fe2O3,3.8%CuO,and3.2%ZnO.The important vari...Leaching of blended slag(BS)was investigated in a microwave oven using hydrogen peroxide and acetic acid.The BSwas a mixture of converter and flash furnace slag containing51%Fe2O3,3.8%CuO,and3.2%ZnO.The important variables thatinfluence the metal extraction yield were leaching time,liquid-solid ratio,H2O2and CH3COOH concentrations.The preferredleaching conditions were as follows:CH3COOH concentration4mol/L;H2O2concentration4mol/L;microwave power900W;leaching time30min;liquid-solid ratio25mL/g BS;leaching temperature100°C.Under these conditions,the metal extractions of95%Cu,1.6%Fe,and30%Zn were obtained.The results were compared with the traditional leaching results.It is evident thatmicrowave heating causes a reduction in the leaching time.Also,the extraction yield results indicate that selective leaching of BS canbe achieved under the preferred conditions.The dissolution kinetic of BS in hydrogen peroxide with acetic acid is controlled by ashrinking unreacted core model equation.The apparent activation energy and reaction order were found to be16.64kJ/mol and1.09,respectively.展开更多
AIM: To investigate the rate of complications of endoscopic retrograde cholangio-pancreatography (ERCP) performed immediately after endoscopic ultrasound fine needle aspiration (EUS-FNA) in a large series of patients....AIM: To investigate the rate of complications of endoscopic retrograde cholangio-pancreatography (ERCP) performed immediately after endoscopic ultrasound fine needle aspiration (EUS-FNA) in a large series of patients. METHODS: Patients with the following conditions were considered candidates for EUS-FNA and ERCP: diagnosis of locally advanced or metastatic pancreatic lesion not eligible for surgery, and patients with pancreatic lesion of unknown nature causing jaundice. Data were prospectively collected on the following parameters: indication for FNA, EUS findings, pathological diagnosis, procedure duration of EUS-FNA and combined EUS-FNA and ERCP, and immediate and late complications. RESULTS: From January 2004 to October 2006, 72 patients were deemed eligible for combined EUS and ERCP. In 25/72 EUS-FNA was performed to obtain a pathology diagnosis of lesions causing biliary obstruction, and ERCP sequentially performed to drain the biliary system. No immediate complications occurred except for two mild bleeding episodes post sphincterotomy. No late complications were recorded except for one patient who experienced fever, promptly recovered with antibiotic therapy. CONCLUSION: Simultaneous approach appears to be feasible and safe. When possible, this can be considered the reference standard to avoid double sedation and reduce duration of the procedure and hospital stay.展开更多
The feasibility of oxidation leaching process of nickel from nickel sulfide ore and the form of different components in the lixivium has been studied at first. The method of leaching nickel sulfide concentration direc...The feasibility of oxidation leaching process of nickel from nickel sulfide ore and the form of different components in the lixivium has been studied at first. The method of leaching nickel sulfide concentration directly by oxidants with existence of ultrasonic has been advanced. The process of leaching nickel from nickel sulfide concentration by using the system of persulfate and silver has been determined. The influence of different factors on the leaching rates of nickel,such as with and without ultrasonic,the concentration of Na2S2O8,liquid-solid ratio and the concentration of AgNO3 have been explored. The results show that:(1) in the oxidative leaching system,nickel can be leached completely as Ni2+ or NiSO4(aq.) from nickel sulfide concentration in theory;(2) the nicopyrite can not exist steadily in the persulfate acid leaching system,but Ni2+can. Meanwhile,sulfur may be existed steadily in the leaching process;(3) nicopyrite with much lower electrostatic potential may be leached earlier than chalcopyrite and sideropyrite;and(4) the overall reaction rate of the leaching process can be enhanced with ultrasonic radiation,but it does not change the mechanism of leaching. The more oxidant concentration or higher liquid-solid ratio is,the higher leaching percentage of nickel. The leaching percentage of nickel can be increased significantly by adding a small amount of AgNO3 during the leaching processes. Under the same conditions,the higher concentration of AgNO3 is,the higher leaching yields of nickel will be obtained.展开更多
文摘A 1×8 multimode interference power splitter with multimode input/output waveguides in SOI material is designed by the beam propagation method and fabricated by the inductive coupled plasma etching technology for use in fiber optics communication systems.The fabricated device exhibits low loss and good coupling uniformity.The excess loss is lower than 0 8dB,and the uniformity is 0 45dB at the wavelength of 1550nm.Moreover,the polarization dependent loss is lower than 0 7dB at 1550nm.The device size is only 2mm×10mm.
基金The National Science and Technology Major Projects(No.2010ZX03003-002,2010ZX03003-004)the National Natural Science Foundation of China(No.60972023)+1 种基金Research Fund of National Mobile Communications Research Laboratory of Southeast University(No.2011A06)the Fund of UK-China Science Bridge
文摘A novel framework of which combines smart antennas multiple antenna systems, （SA） with multiple-input multiple-output （MIMO） at the receiver, is proposed. The uplink SA-MIMO system is investigated. The joint optimization problem corresponding to the uplink capacity of the single-user SA-MIMO system is deduced. Then the closedform expression of the capacity is obtained in the case of equal power allocation and the same direction-of-arrivals （DOAs） from different transmit antennas at the same antenna array, and an upper bound of the capacity is also given in the case of different DOAs at the same antenna array. After that, for the general case, a suboptimal method for the capacity optimization problem is presented. Some numerical results are also given to compare the capacities of conventional MIMO and SA-MIMO systems and show that the proposed method is viable.
基金This work was supported in part by the National Natural Science Foundation of China under Grants No.61372099,and No.61302140
文摘The secrecy rate of limited feedback beamforming is studied for a Multiple-Input Single-Output(MISO) wiretap channel with a multi-antenna eavesdropper.We first obtain the secrecy rate of limited feedback beamforming achieved at the legitimate receiver.We then derive a lower bound for the asymptotic secrecy rate in the large system limit.From this bound,we observe a threshold for the ratio of eavesdrop antennas to transmit antennas to obtain a positive secrecy rate.We further show that the secrecy rate loss due to limited feedback decays with the number of feedback bits per transmit antenna.
基金Supported by the National Natural Science Foundation of China （50874111） the National High Technology Research and Development Program （2009AA063201）+2 种基金 the Program for New Century Excellent Talents in University of China （NCET-10-0724） the Fundamental Research Funds for Central Universities（2010QZ05） SRF for ROCS, SEM
文摘According to the formation of shock wave resulting from coal and gas outburst, the gas flow of coal and gas outburst was transformed from an unsteady flow to a steady one based on selected appropriate reference coordinates, and the mathematical expressions were then established by applying mass conservation, momentum conservation equation, and energy conservation equation. On this basis, analyzed gas flow mitigation of variable cross-section area and the outburst intensity, and the relations between cross-section area, velocity, and density; the relations between overpressures and outburst intensity were deduced. Furthermore, shock waves resulting from coal and gas outburst and outburst intensity were measured by experimental setup, the overpressure and outburst intensity of different gas pressures were obtained, and the similar conditions of the experiment were numerically simulated. The averaged overpressure and gas flow velocity of variable cross-section under different gas pressures were numerically derived. The results show that the averaged overpressure and outburst intensity obtained from simulation are in good agreement with the experimental results. Moreover, the gas flow velocity of variable cross-sections approximates to the theoretical analysis.
文摘Leaching of blended slag(BS)was investigated in a microwave oven using hydrogen peroxide and acetic acid.The BSwas a mixture of converter and flash furnace slag containing51%Fe2O3,3.8%CuO,and3.2%ZnO.The important variables thatinfluence the metal extraction yield were leaching time,liquid-solid ratio,H2O2and CH3COOH concentrations.The preferredleaching conditions were as follows:CH3COOH concentration4mol/L;H2O2concentration4mol/L;microwave power900W;leaching time30min;liquid-solid ratio25mL/g BS;leaching temperature100°C.Under these conditions,the metal extractions of95%Cu,1.6%Fe,and30%Zn were obtained.The results were compared with the traditional leaching results.It is evident thatmicrowave heating causes a reduction in the leaching time.Also,the extraction yield results indicate that selective leaching of BS canbe achieved under the preferred conditions.The dissolution kinetic of BS in hydrogen peroxide with acetic acid is controlled by ashrinking unreacted core model equation.The apparent activation energy and reaction order were found to be16.64kJ/mol and1.09,respectively.
文摘AIM: To investigate the rate of complications of endoscopic retrograde cholangio-pancreatography (ERCP) performed immediately after endoscopic ultrasound fine needle aspiration (EUS-FNA) in a large series of patients. METHODS: Patients with the following conditions were considered candidates for EUS-FNA and ERCP: diagnosis of locally advanced or metastatic pancreatic lesion not eligible for surgery, and patients with pancreatic lesion of unknown nature causing jaundice. Data were prospectively collected on the following parameters: indication for FNA, EUS findings, pathological diagnosis, procedure duration of EUS-FNA and combined EUS-FNA and ERCP, and immediate and late complications. RESULTS: From January 2004 to October 2006, 72 patients were deemed eligible for combined EUS and ERCP. In 25/72 EUS-FNA was performed to obtain a pathology diagnosis of lesions causing biliary obstruction, and ERCP sequentially performed to drain the biliary system. No immediate complications occurred except for two mild bleeding episodes post sphincterotomy. No late complications were recorded except for one patient who experienced fever, promptly recovered with antibiotic therapy. CONCLUSION: Simultaneous approach appears to be feasible and safe. When possible, this can be considered the reference standard to avoid double sedation and reduce duration of the procedure and hospital stay.
基金Supported by the National Natural Science Foundation of China （50874087 50978212） the Key Projects in the National Science and Technology Pillar Program （2009BAA20B02）
文摘The feasibility of oxidation leaching process of nickel from nickel sulfide ore and the form of different components in the lixivium has been studied at first. The method of leaching nickel sulfide concentration directly by oxidants with existence of ultrasonic has been advanced. The process of leaching nickel from nickel sulfide concentration by using the system of persulfate and silver has been determined. The influence of different factors on the leaching rates of nickel,such as with and without ultrasonic,the concentration of Na2S2O8,liquid-solid ratio and the concentration of AgNO3 have been explored. The results show that:(1) in the oxidative leaching system,nickel can be leached completely as Ni2+ or NiSO4(aq.) from nickel sulfide concentration in theory;(2) the nicopyrite can not exist steadily in the persulfate acid leaching system,but Ni2+can. Meanwhile,sulfur may be existed steadily in the leaching process;(3) nicopyrite with much lower electrostatic potential may be leached earlier than chalcopyrite and sideropyrite;and(4) the overall reaction rate of the leaching process can be enhanced with ultrasonic radiation,but it does not change the mechanism of leaching. The more oxidant concentration or higher liquid-solid ratio is,the higher leaching percentage of nickel. The leaching percentage of nickel can be increased significantly by adding a small amount of AgNO3 during the leaching processes. Under the same conditions,the higher concentration of AgNO3 is,the higher leaching yields of nickel will be obtained.
