An optimized device structure for reducing the RESET current of phase-change random access memory （PCRAM） with blade-type like （BTL） phase change layer is proposed. The electrical thermal analysis of the BTL cell ...An optimized device structure for reducing the RESET current of phase-change random access memory （PCRAM） with blade-type like （BTL） phase change layer is proposed. The electrical thermal analysis of the BTL cell and the blade heater contactor structure by three-dimensional finite element modeling are compared with each other during RESET operation. The simulation results show that the programming region of the phase change layer in the BTL cell is much smaller, and thermal electrical distributions of the BTL cell are more concentrated on the TiN/GST interface. The results indicate that the BTL cell has the superiorities of increasing the heating efficiency, decreasing the power consumption and reducing the RESET current from 0.67mA to 0.32mA. Therefore, the BTL cell will be appropriate for high performance PCRAM device with lower power consumption and lower RESET current.展开更多
The effect of the wave accessibility condition on the lower hybrid cm＇rent drive in the experimental advanced superconductor Tokamak （EAST） plasma with H-mode operation is studied. Based on a simplified model, a mo...The effect of the wave accessibility condition on the lower hybrid cm＇rent drive in the experimental advanced superconductor Tokamak （EAST） plasma with H-mode operation is studied. Based on a simplified model, a mode conversion layer of the lower hybrid wave between the fast wave branch and the slow wave branch is proved to exist in the plasma periphery for typical EAST H-mode parameters. Under the framework of the lower hybrid wave simulation code （LSC）, the wave ray trajectory and the associated current drive are calculated numerically. The results show that the wave accessibility condition plays an important role on the lower hybrid current drive in EAST plasma. For wave rays with parallel refractive index n｜｜= 2.1 or n｜｜ = 2.5 launched from the outside midplane, the wave rays may penetrate the core plasma due to the toroida] geometry effect, while numerous reflections of the wave ray trajectories in the plasma periphery occur. However, low current drive efficiency is obtained. Meanwhile, the wave accessibility condition is improved if a higher confined magnetic field is applied. The simulation results show that for plasma parameters under present EAST H-mode operation, a significant lower hybrid wave current drive could be obtained for the wave spectrum with peak value n｜｜ = 2.1 if a toroidal magnetic field BT =2.5 T is applied.展开更多
Amorphous NbS_(2)was proposed as the resistive switching(RS)layer for conductive-bridge random access memory(CBRAM)for the first time,with Cu and Au as the top and bottom electrodes,respectively.NbS_(2)films were prep...Amorphous NbS_(2)was proposed as the resistive switching(RS)layer for conductive-bridge random access memory(CBRAM)for the first time,with Cu and Au as the top and bottom electrodes,respectively.NbS_(2)films were prepared at room temperature,which exhibited an amorphous structure and did not crystalize even annealed at 500°C,showing good thermal stability.The amorphous NbS_(2)CBRAM devices present stable bipolar non-volatile RS characteristics.Repetitive RS behavior is demonstrated in amorphous NbS_(2)CBRAMs.The operating voltage during all RS cycles is less than 1 V,demonstrating that the NbS_(2)CBRAM is a low-operation voltage memory device.The distribution of the high and low resistive state resistance is relatively concentrated,and the on-off ratio has been kept above 100,offering a sufficient data read/write window.The formation and fracture of the Cu metal conductive filament is considered to be the RS mechanism by analyzing the dependence of current and voltage in logarithmic coordinates.Our study demonstrated that amorphous NbS_(2)is a promising material for lowoperation voltage CBRAM.展开更多
We analyze the connection between quantum operations and accessible information. And we find that the accessible information decreases under quantum operations. We show that it is impossible to perfectly manipulate an...We analyze the connection between quantum operations and accessible information. And we find that the accessible information decreases under quantum operations. We show that it is impossible to perfectly manipulate an unknown state in an open quantum system. That the accessible information decreases under quantum operations gives a fundamental limitation in the microscopic world.展开更多
Background:Access to surgical care in Low-and Middle-Income Countries(LMICs)such as Tanzania is extremely limited.Northern Tanzania is served by a single tertiary referral hospital,Kilimanjaro Christian Medical Centre...Background:Access to surgical care in Low-and Middle-Income Countries(LMICs)such as Tanzania is extremely limited.Northern Tanzania is served by a single tertiary referral hospital,Kilimanjaro Christian Medical Centre(KCMC).The surgical volumes,workflow,and payment mechanisms in this region have not been characterized.Understanding these factors is critical in expanding access to healthcare.The authors sought to evaluate the operations and financing of the main operating theaters at KCMC in Sub-Saharan Africa.Methods:The 2018 case volume and specialty distribution(general,orthopaedic,and gynecology)in the main operating theaters at KCMC was retrieved through retrospective review of operating report books.Detailed workflow(i.e.planned and cancelled cases,lengths of procedures,lengths of operating days)and financing data(patient payment methods)from the five KCMC operating theater logs were retrospectively reviewed for the available fivemonth period of March 2018 to July 2018.Descriptive statistics and statistical analysis were performed.Results:In 2018,the main operating theaters at KCMC performed 3817 total procedures,with elective procedures(2385)outnumbering emergency procedures(1432).General surgery(1927)was the most operated specialty,followed by orthopaedics(1371)and gynecology(519).In the five-month subset analysis period,just 54.6%of planned operating days were fully completed.There were 238 cancellations(20.8%of planned operations).Time constraints(31.1%,74 cases)was the largest reason;lack of patient payment accounted for as many cancellations as unavailable equipment(6.3%,15 cases each).Financing for elective theater cases included insurance 45.5%(418 patients),and cash 48.4%(445 patients).Conclusion:While surgical volume is high,there are non-physical inefficiencies in the system that can be addressed to reduce cancellations and improve capacity.Improving physical resources is not enough to improve access to care in this region,and likely in many LMIC settings.Patient financing and workflow will be critical considerations to truly improve access to surgical care.展开更多
由于Visual Fox Pro自身存在的一些缺陷,导致其安全性能不高,功能不强大,为弥补缺陷,本文对Visual FoxPro和ACCESS从包含的内容、数据类型、表记录的浏览、编程处理语句等方面进行一系列的对比分析,可以帮助熟练VF的用户更好地学习与掌...由于Visual Fox Pro自身存在的一些缺陷,导致其安全性能不高,功能不强大,为弥补缺陷,本文对Visual FoxPro和ACCESS从包含的内容、数据类型、表记录的浏览、编程处理语句等方面进行一系列的对比分析,可以帮助熟练VF的用户更好地学习与掌握ACCESS数据库。展开更多
Reducing the operation and maintenance (O & M) cost is one of the potential actions that could reduce the cost of energy produced by offshore wind farms. This article attempts to reduce O & M cost by improving...Reducing the operation and maintenance (O & M) cost is one of the potential actions that could reduce the cost of energy produced by offshore wind farms. This article attempts to reduce O & M cost by improving the utilization of the maintenance resources, specifically the efficient scheduling and routing of the maintenance fleet. Scheduling and routing of maintenance fleet is a non-linear optimization problem with high complexity and a number of constraints. A heuristic algorithm, Ant Colony Optimization (ACO), was modified as Multi-ACO to be used to find the optimal scheduling and routing of maintenance fleet. The numerical studies showed that the proposed methodology was effective and robust enough to find the optimal solution even if the number of offshore wind turbine increases. The suggested approaches are helpful to avoid a time-consuming process of manually planning the scheduling and routing with a presumably suboptimal outcome.展开更多
Femoral access is considered less safe for access site complications than the radial access. Cardiovascular procedures have not been studied taking operator experience, defined as American Board of Internal Medicine, ...Femoral access is considered less safe for access site complications than the radial access. Cardiovascular procedures have not been studied taking operator experience, defined as American Board of Internal Medicine, Interventional Cardiology certification or equivalent qualification in another country, into account. We hypothesize that the procedural results are operator dependent and excellent results are obtained when procedures are performed by experienced operators. Femoral access is higher risk than radial access based on American College of Cardiology (ACC) guidelines. Femoral access is less forgiving, as opposed to radial, as it is an end-artery, lacks easy compressibility and is more likely to cause morbidity when injured. Hence, radial is recommended over the femoral approach according to ACC practice guidelines. These guidelines are often based on the randomized studies from academic centers where trainees, with variable arterial access experience, perform the initial access stick and arterial closure device deployment. Methods: We performed a single center retrospective review of 32,446 consecutive patients undergoing invasive cardiovascular procedures done from the femoral approach using American College of Cardiology/National Cardiovascular Data Registry (ACC/NCDR) from January 1, 2006 to June 30, 2013. Only experienced operators performed the actual access site stick and the reminder of the invasive procedure. Results: Total bleeding and vascular complications were less than 1%. We define outcomes as excellent if the total bleeding and vascular complication risk is less than 1% based on previous studies discussed in the ACC guidelines. Conclusion: Excellent outcomes can be obtained from the femoral access if experienced cardiologists perform the procedure. Hence, radial arterial access over the femoral access may be selectively rather than universally recommended considering the possibility of varying level of femoral access expertise of different practices.展开更多
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No XDA09020402the National Integrate Circuit Research Program of China under Grant No 2009ZX02023-003+1 种基金the National Natural Science Foundation of China under Grant Nos 61261160500,61376006,61401444 and 61504157the Science and Technology Council of Shanghai under Grant Nos 14DZ2294900,15DZ2270900 and 14ZR1447500
文摘An optimized device structure for reducing the RESET current of phase-change random access memory （PCRAM） with blade-type like （BTL） phase change layer is proposed. The electrical thermal analysis of the BTL cell and the blade heater contactor structure by three-dimensional finite element modeling are compared with each other during RESET operation. The simulation results show that the programming region of the phase change layer in the BTL cell is much smaller, and thermal electrical distributions of the BTL cell are more concentrated on the TiN/GST interface. The results indicate that the BTL cell has the superiorities of increasing the heating efficiency, decreasing the power consumption and reducing the RESET current from 0.67mA to 0.32mA. Therefore, the BTL cell will be appropriate for high performance PCRAM device with lower power consumption and lower RESET current.
基金Supported by the National Natural Science Foundation of China under Grant No 11347002the National Magnetic Confinement Fusion Science Program of China under Grant No 2013GB111000+2 种基金the Outstanding Youth Fund of Hunan Province Education Department of China under Grant No 12B107the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics under Grant No 11261140328the National Research Foundation 2012K2A2A6000443
文摘The effect of the wave accessibility condition on the lower hybrid cm＇rent drive in the experimental advanced superconductor Tokamak （EAST） plasma with H-mode operation is studied. Based on a simplified model, a mode conversion layer of the lower hybrid wave between the fast wave branch and the slow wave branch is proved to exist in the plasma periphery for typical EAST H-mode parameters. Under the framework of the lower hybrid wave simulation code （LSC）, the wave ray trajectory and the associated current drive are calculated numerically. The results show that the wave accessibility condition plays an important role on the lower hybrid current drive in EAST plasma. For wave rays with parallel refractive index n｜｜= 2.1 or n｜｜ = 2.5 launched from the outside midplane, the wave rays may penetrate the core plasma due to the toroida] geometry effect, while numerous reflections of the wave ray trajectories in the plasma periphery occur. However, low current drive efficiency is obtained. Meanwhile, the wave accessibility condition is improved if a higher confined magnetic field is applied. The simulation results show that for plasma parameters under present EAST H-mode operation, a significant lower hybrid wave current drive could be obtained for the wave spectrum with peak value n｜｜ = 2.1 if a toroidal magnetic field BT =2.5 T is applied.
基金supported by“Pioneer”and“Leading Goose”R&D Program of Zhejiang Province(Nos.2021C01SA 301612 and 2023C01235).
文摘Amorphous NbS_(2)was proposed as the resistive switching(RS)layer for conductive-bridge random access memory(CBRAM)for the first time,with Cu and Au as the top and bottom electrodes,respectively.NbS_(2)films were prepared at room temperature,which exhibited an amorphous structure and did not crystalize even annealed at 500°C,showing good thermal stability.The amorphous NbS_(2)CBRAM devices present stable bipolar non-volatile RS characteristics.Repetitive RS behavior is demonstrated in amorphous NbS_(2)CBRAMs.The operating voltage during all RS cycles is less than 1 V,demonstrating that the NbS_(2)CBRAM is a low-operation voltage memory device.The distribution of the high and low resistive state resistance is relatively concentrated,and the on-off ratio has been kept above 100,offering a sufficient data read/write window.The formation and fracture of the Cu metal conductive filament is considered to be the RS mechanism by analyzing the dependence of current and voltage in logarithmic coordinates.Our study demonstrated that amorphous NbS_(2)is a promising material for lowoperation voltage CBRAM.
文摘We analyze the connection between quantum operations and accessible information. And we find that the accessible information decreases under quantum operations. We show that it is impossible to perfectly manipulate an unknown state in an open quantum system. That the accessible information decreases under quantum operations gives a fundamental limitation in the microscopic world.
文摘Background:Access to surgical care in Low-and Middle-Income Countries(LMICs)such as Tanzania is extremely limited.Northern Tanzania is served by a single tertiary referral hospital,Kilimanjaro Christian Medical Centre(KCMC).The surgical volumes,workflow,and payment mechanisms in this region have not been characterized.Understanding these factors is critical in expanding access to healthcare.The authors sought to evaluate the operations and financing of the main operating theaters at KCMC in Sub-Saharan Africa.Methods:The 2018 case volume and specialty distribution(general,orthopaedic,and gynecology)in the main operating theaters at KCMC was retrieved through retrospective review of operating report books.Detailed workflow(i.e.planned and cancelled cases,lengths of procedures,lengths of operating days)and financing data(patient payment methods)from the five KCMC operating theater logs were retrospectively reviewed for the available fivemonth period of March 2018 to July 2018.Descriptive statistics and statistical analysis were performed.Results:In 2018,the main operating theaters at KCMC performed 3817 total procedures,with elective procedures(2385)outnumbering emergency procedures(1432).General surgery(1927)was the most operated specialty,followed by orthopaedics(1371)and gynecology(519).In the five-month subset analysis period,just 54.6%of planned operating days were fully completed.There were 238 cancellations(20.8%of planned operations).Time constraints(31.1%,74 cases)was the largest reason;lack of patient payment accounted for as many cancellations as unavailable equipment(6.3%,15 cases each).Financing for elective theater cases included insurance 45.5%(418 patients),and cash 48.4%(445 patients).Conclusion:While surgical volume is high,there are non-physical inefficiencies in the system that can be addressed to reduce cancellations and improve capacity.Improving physical resources is not enough to improve access to care in this region,and likely in many LMIC settings.Patient financing and workflow will be critical considerations to truly improve access to surgical care.
文摘Reducing the operation and maintenance (O & M) cost is one of the potential actions that could reduce the cost of energy produced by offshore wind farms. This article attempts to reduce O & M cost by improving the utilization of the maintenance resources, specifically the efficient scheduling and routing of the maintenance fleet. Scheduling and routing of maintenance fleet is a non-linear optimization problem with high complexity and a number of constraints. A heuristic algorithm, Ant Colony Optimization (ACO), was modified as Multi-ACO to be used to find the optimal scheduling and routing of maintenance fleet. The numerical studies showed that the proposed methodology was effective and robust enough to find the optimal solution even if the number of offshore wind turbine increases. The suggested approaches are helpful to avoid a time-consuming process of manually planning the scheduling and routing with a presumably suboptimal outcome.
文摘Femoral access is considered less safe for access site complications than the radial access. Cardiovascular procedures have not been studied taking operator experience, defined as American Board of Internal Medicine, Interventional Cardiology certification or equivalent qualification in another country, into account. We hypothesize that the procedural results are operator dependent and excellent results are obtained when procedures are performed by experienced operators. Femoral access is higher risk than radial access based on American College of Cardiology (ACC) guidelines. Femoral access is less forgiving, as opposed to radial, as it is an end-artery, lacks easy compressibility and is more likely to cause morbidity when injured. Hence, radial is recommended over the femoral approach according to ACC practice guidelines. These guidelines are often based on the randomized studies from academic centers where trainees, with variable arterial access experience, perform the initial access stick and arterial closure device deployment. Methods: We performed a single center retrospective review of 32,446 consecutive patients undergoing invasive cardiovascular procedures done from the femoral approach using American College of Cardiology/National Cardiovascular Data Registry (ACC/NCDR) from January 1, 2006 to June 30, 2013. Only experienced operators performed the actual access site stick and the reminder of the invasive procedure. Results: Total bleeding and vascular complications were less than 1%. We define outcomes as excellent if the total bleeding and vascular complication risk is less than 1% based on previous studies discussed in the ACC guidelines. Conclusion: Excellent outcomes can be obtained from the femoral access if experienced cardiologists perform the procedure. Hence, radial arterial access over the femoral access may be selectively rather than universally recommended considering the possibility of varying level of femoral access expertise of different practices.
