A new scheduling algorithm called deferrable scheduling with time slice exchange (DS-EXC) was proposed to maintain the temporal validity of real-time data. In DS-EXC, the time slice exchange method was designed to fur...A new scheduling algorithm called deferrable scheduling with time slice exchange (DS-EXC) was proposed to maintain the temporal validity of real-time data. In DS-EXC, the time slice exchange method was designed to further defer the release time of transaction instances derived by the deferrable scheduling algorithm (DS-FP). In this way, more CPU time would be left for lower priority transactions and other transactions. In order to minimize the scheduling overhead, an off-line scheme was designed. In particular, the schedule for a transaction set is generated off-line until a repeating pattern is found, and then the pattern is used to construct the schedule on-line. The performance of DS-EXC was evaluated by sets of experiments. The results show that DS-EXC outperforms DS-FP in terms of increasing schedulable ratio. It also provides better performance under mixed workloads.展开更多
To evaluate the temporal patterns of N deficiencies in corn and assess the ability of remote sensing to diagnose N deficiencies during the vegetative growth of corn, three field-scale experiments were conducted with v...To evaluate the temporal patterns of N deficiencies in corn and assess the ability of remote sensing to diagnose N deficiencies during the vegetative growth of corn, three field-scale experiments were conducted with various rates (56, 112, and 168 kg N ha-1 ), timing (early and late applications) and placement (injected into soil and dribbled on soil surface) of N fertilization in a split-plot design. Relationships between canopy reflectance during the growing season and yield data at the end of growing season were studied for different treatments. Results showed significant variation in both grain yields and canopy reflectance among the three cornfields. The N fertilization made in early June resulted in low canopy reflectance in early July, but the differences disappeared as the season progressed. The effect of N rates on canopy reflectance was not significant in early July but it gradually became detectable in mid-July and thereafter. The fertilizer placement had a significant effect on grain yields only in one field but not on canopy reflectance in all three fields. These observations suggest that the deficiency of N developed under field conditions is a dynamic phenomenon, which adds complexity for accurately defining "N deficiency" and effectively developing management strategies for in-season correction. Remote sensing throughout the season helps collect information about important interactions that have not been given enough attention in the past.展开更多
The wireless sensor network (WSN) plays an important role in monitoring the environment near the harbor in order to make the ships nearby out of dangers and to optimize the utilization of limited sea routes. Based o...The wireless sensor network (WSN) plays an important role in monitoring the environment near the harbor in order to make the ships nearby out of dangers and to optimize the utilization of limited sea routes. Based on the historical data collected by the buoys with sensing capacities, a novel data compression algorithm called adaptive time piecewise constant vector quantization (ATPCVQ) is proposed to utilize the principal components. The proposed system is capable of lowering the budget of wireless communication and enhancing the lifetime of sensor nodes subject to the constrain of data precision. Furthermore, the proposed algorithm is verified by using the practical data in Qinhuangdao Port of China.展开更多
To the existing spectrum sharing schemes in wireless-powered cognitive wireless sensor networks,the protocols are limited to either separate the primary and the secondary transmission or allow the secondary user to tr...To the existing spectrum sharing schemes in wireless-powered cognitive wireless sensor networks,the protocols are limited to either separate the primary and the secondary transmission or allow the secondary user to transmit signals in a time slot when it forwards the primary signal.In order to address this limitation,a novel cooperative spectrum sharing scheme is proposed,where the secondary transmission is multiplexed with both the primary transmission and the relay transmission.Specifically,the process of transmission is on a three-phase time-switching relaying basis.In the first phase,a cognitive sensor node SU1 scavenges energy from the primary transmission.In the second phase,another sensor node SU2 and primary transmitter simultaneously transmit signals to the SU1.In the third phase,the node SU1 can assist the primary transmission to acquire the opportunity of spectrum sharing.Joint decoding and interference cancellation technique is adopted at the receivers to retrieve the desired signals.We further derive the closed-form expressions for the outage probabilities of both the primary and secondary systems.Moreover,we address optimization of energy harvesting duration and power allocation coefficient strategy under performance criteria.An effective algorithm is then presented to solve the optimization problem.Simulation results demonstrate that with the optimized solutions,the sensor nodes with the proposed cooperative spectrum sharing scheme can utilize the spectrum in a more efficient manner without deteriorating the performance of the primary transmission,as compared with the existing one-directional scheme in the literature.展开更多
For the discrete-time system which is subjected to uncoupled actuator faults and sensor faults simultaneously,a robust fault diagnosis method based on a proportional integral observer (PIO) is presented.The proposed P...For the discrete-time system which is subjected to uncoupled actuator faults and sensor faults simultaneously,a robust fault diagnosis method based on a proportional integral observer (PIO) is presented.The proposed PIO uses an additionally introduced integral term of the output errors to obtain the estimationof actuator faults. Besides, the sensor faults are regarded as the augment states so that the PIO cantrace them. Moreover, the convergence of the PIO is proved. A variable speed wind turbine(VWT) exampleis given to demonstrate the fast convergence and diagnosis precision of the proposed PIO.展开更多
According to the characteristic of the sensor inertia, the dynamic prediction to improve the system dynamic precision is presented in this paper. With the recurrence calculation of time constant of the sensor, the sys...According to the characteristic of the sensor inertia, the dynamic prediction to improve the system dynamic precision is presented in this paper. With the recurrence calculation of time constant of the sensor, the system dynamic precision is greatly improved. The example using this method is given.展开更多
The key of speed sensorless vector control system lies in the accurate orientation of magnetic field. In some field-oriented algorithms, the integrator of observers and the dead-time effect bring in system errors duri...The key of speed sensorless vector control system lies in the accurate orientation of magnetic field. In some field-oriented algorithms, the integrator of observers and the dead-time effect bring in system errors during the estimation of field position. In this paper, a saturated feedback integrator is used, and the dead-time effect is compen- sated by current positive feedback. Experiments were carried out on the hardware platform of MCK2407, with chip TMS320LF2407 from TI Company. The results show that the prooosed method is simole and effective, and the accuracy of field position is improved.展开更多
A traffic sensitive spectrum access scheme is proposed to satisfy the traffic load requirement of secondary users (SUs). In the proposed design, SU only accesses available channels which can meet the traffic demand....A traffic sensitive spectrum access scheme is proposed to satisfy the traffic load requirement of secondary users (SUs). In the proposed design, SU only accesses available channels which can meet the traffic demand. To achieve this, the expected transmission time (E3W) of the SU is calcu- lated first based on the delivery ratio. Then, the channel idle time is estimated based on the activity of primary users (PUs). Therefore, available channels with estimated idle time longer than ETr could be chosen. With high probability, the SU can finish transmission on these channels without disruption, thereby satisfying the traffic load demand of the SU. Finally, our method is extended to the multi-channel scenario where each SU can access multiple channels simultaneously. Performance analysis shows that our method satisfies the requirement of SUs while effectively improving the throughput.展开更多
The time-frequency analysis of the signal acquired by a single ground-based microphone shows a two-dimensional interference pattern in the time-frequency plane,which is caused by the time delay of the received signal ...The time-frequency analysis of the signal acquired by a single ground-based microphone shows a two-dimensional interference pattern in the time-frequency plane,which is caused by the time delay of the received signal emitted from a low flying aircraft via the direct path and the ground-re-flected path. A model is developed for estimating the motion parameters of an aircraft flying along a straight line at a constant height and with a constant speed. Monte Carlo simulation results and ex-perimental results are presented to validate the model,and an error analysis of the model is presented to verify the effectiveness of the estimation scheme advocated.展开更多
Due to the difficulty and weakness of current stress measurement methods in deep soft rock, a new rheological stress recovery method of the determination of the three-dimensional(3D) stress tensor is proposed. It is s...Due to the difficulty and weakness of current stress measurement methods in deep soft rock, a new rheological stress recovery method of the determination of the three-dimensional(3D) stress tensor is proposed. It is supposed that rock stresses will recovery gradually with time and can be measured by embedding transducers into the borehole. In order to explore the applicability and accuracy of this method, analytical solutions are developed for stress measurement with the rheological stress recovery method in a viscoelastic surrounding rock, the rheological properties of which are depicted as both the Burger's model and a 3-parameter solid model. In such conditions, explicit analytical expressions for predicting time-dependent pressures on the transducer are derived. A parametric analysis is then adopted to investigate the influences of the grout solidification time and the mechanical properties of the grout layer. The results indicate that this method is suitable for stress measurement in deep soft rock, the characteristics of which are soft, fractured and subjected to high geo-stress.展开更多
The field test of a typical Tibetan ancient structure instrumented with displacement and acceleration transducers was conducted to measure time histories due to crowd walking and running. The test case is introduced f...The field test of a typical Tibetan ancient structure instrumented with displacement and acceleration transducers was conducted to measure time histories due to crowd walking and running. The test case is introduced firstly. The displacement time histories are then used to analyze the dynamic property such as fundamental frequency of vertical vibration and damping ratio of the test structure, and the acceleration time histories are applied to evaluate the floor vibration serviceability. The floor interaction and comparison of human walking and running are also discussed. Some valuable conclusions are given.展开更多
Recent remote monitoring surveys of smoke produced by burning and forest fires using weather radar equipment showed excellent preliminary results, but their progress is hindered due to the high operating cost of radar...Recent remote monitoring surveys of smoke produced by burning and forest fires using weather radar equipment showed excellent preliminary results, but their progress is hindered due to the high operating cost of radar systems. The fire danger rating index is a good indicator of the event occurrence probability, what contributes to the monitoring areas and adds value to the alert degree information. The application of FMA fire danger index "Formula de Monte Alegre" for areas in radar coverage radius of the S-band weather radar operated by the Meteorological Research Institute, IPMet, S^fo Paulo State University, efficiently optimize the use of the radar equipment, significantly reduce operational costs, enable new research and promise results which have already reduced the average response time between ignition and detection for less than 5 minutes. It reduces more than 50% response time considered optimal for conventional detection systems. Thus, the "FMA" values act as a trigger (on-off) in the remote monitoring system of forest fires, optimizing its use at low cost, avoiding the possible stress of equipment and enabling the advance of research monitoring, detection of burnings and forest fires using weather radar.展开更多
OBJECTIVE:H1N1 was a new and potentially serious infectious disease,in human,the severity of influenza can vary from mild to severe,thus to find an effective and safety way to control the influenza pandemic is of cruc...OBJECTIVE:H1N1 was a new and potentially serious infectious disease,in human,the severity of influenza can vary from mild to severe,thus to find an effective and safety way to control the influenza pandemic is of crucial importance.This retrospective study describes the duration of viral shedding in H1N1 patients that were hospitalized and treated in China.METHODS:Clinical data were collected from May to July,2009 in China for 963 patients with influenza A(H1N1) virus infection.Patients were treated based on the guidelines issued by the Chinese Ministry of Health.The primary outcome was duration of viral shedding and statistical comparisons were performed.RESULTS:In the patients with body temperature greater than 38.0℃,there were no differences in virus shedding duration among the patients taking oseltamivir within two days,patients undergoing Traditional Chinese Medicine(TCM) therapy or those receiving no drug therapy.In patients with body temperature 338.1℃,TCM therapy reduced the viral shedding duration(P<0.05,vs.oseltamivir therapy).Furthermore,taking oseltamivir two days after onset of symptoms might prolong the virus shedding duration(P<0.05,vs.taking oseltamivir less than 2 days of onset).CONCLUSION:TCM therapy is effective for reducing the length of virus shedding in patients with body temperature 338.0℃.Oseltamivir used for reducing virus shedding duration should be taken within two days of onset.展开更多
Schottky-contacted sensors have been demonstrated to show high sensitivity and fast response time in various sensing systems.In order to improve their sensing performance,the Schottky barriers height(SBH)at the interf...Schottky-contacted sensors have been demonstrated to show high sensitivity and fast response time in various sensing systems.In order to improve their sensing performance,the Schottky barriers height(SBH)at the interface of semiconductor and metal electrode should be adjusted to appropriate range to avoid low output or low sensitivity,which was induced by excessively high or low SBH,respectively.In this work,a simple and effective SBH tuning method by triboelectric generator(TENG)is proposed,the SBH can be effectively lowered by voltage pulses generated by TENG and gradually recover over time after withdrawing the TENG.Through combining the TENG treatment with piezotronic effect,a synergistic effect on lowering SBH was achieved.The change of SBH is increased by 3.8 to 12.8 times,compared with dependent TENG treatment and piezotronic effect,respectively.Furthermore,the recovery time of the TENG-lowered SBH can be greatly shortened from 1.5 h to 40 s by piezotronic effect.This work demonstrated a flexible and feasible SBH tuning method,which can be used to effectively improve the sensitivity of Schottky-contact sensor and sensing system.Our study also shows great potential in broadening the application scenarios of Schottky-contacted electronic devices.展开更多
The key factor of the sensitivity in the FBG-based pH sensor is analyzed in detail. A multi-thin-layer structure of the gel coated cover was proposed and implemented with a special process. The sensors with the coated...The key factor of the sensitivity in the FBG-based pH sensor is analyzed in detail. A multi-thin-layer structure of the gel coated cover was proposed and implemented with a special process. The sensors with the coated thickness of 420 ~m, 500 ~m, and 580 ~m were built up, respectively. The corresponding spectral shifts of 0.08nm, 0.13nm, and 0.22nm were detected when the pH sensors were soaked in the pH value of 3-9. Meanwhile, the sensor with the gel layer thickness of 580 ~tm was measured in the optimum measurement time period with the pH value changing from 3-12, in which the detected sensitivity of 52pm/pH was achieved in the pH range of 6-12.展开更多
When an aircraft moves under a low carrier-to-noise ratio (CNR) or at a high speed, increasing the sensitivity of global navigation satellite system (GNSS) receiver is a goal quite hard to achieve. A novel acquisi...When an aircraft moves under a low carrier-to-noise ratio (CNR) or at a high speed, increasing the sensitivity of global navigation satellite system (GNSS) receiver is a goal quite hard to achieve. A novel acquisition scheme assisted with micro-electro-mechanical-sensor (MEMS) inertial navigation system (INS) is presented to estimate the Doppler caused by user dynamics relative to each satellite ahead of time. Based on tightly coupled GNSS/INS estimation algorithm, MEMS INS Doppler error that can be achieved is first described. Then, by analyzing the mean acquisition time and signal detection probability, the MEMS INS-assisted acquisition capabilities in cold, warm and hot starts are quantitatively determined and compared with the standard GNSS acquisition capability. The simulations and comparisons have shown that: the acquisition time in cold start can be shortened by at least 23 s, the time in warm start can be shortened to i s and the acquisition capability is improved 95%, and the reaequisition time in hot start can be shortened by around 0.090 s and the capability can be enhanced 40%. The results demonstrate the validity of the novel method.展开更多
基金Project(60873030) supported by the National Natural Science Foundation of China
文摘A new scheduling algorithm called deferrable scheduling with time slice exchange (DS-EXC) was proposed to maintain the temporal validity of real-time data. In DS-EXC, the time slice exchange method was designed to further defer the release time of transaction instances derived by the deferrable scheduling algorithm (DS-FP). In this way, more CPU time would be left for lower priority transactions and other transactions. In order to minimize the scheduling overhead, an off-line scheme was designed. In particular, the schedule for a transaction set is generated off-line until a repeating pattern is found, and then the pattern is used to construct the schedule on-line. The performance of DS-EXC was evaluated by sets of experiments. The results show that DS-EXC outperforms DS-FP in terms of increasing schedulable ratio. It also provides better performance under mixed workloads.
基金Project supported by the Iowa Soybean Association On-Farm Network R, USA
文摘To evaluate the temporal patterns of N deficiencies in corn and assess the ability of remote sensing to diagnose N deficiencies during the vegetative growth of corn, three field-scale experiments were conducted with various rates (56, 112, and 168 kg N ha-1 ), timing (early and late applications) and placement (injected into soil and dribbled on soil surface) of N fertilization in a split-plot design. Relationships between canopy reflectance during the growing season and yield data at the end of growing season were studied for different treatments. Results showed significant variation in both grain yields and canopy reflectance among the three cornfields. The N fertilization made in early June resulted in low canopy reflectance in early July, but the differences disappeared as the season progressed. The effect of N rates on canopy reflectance was not significant in early July but it gradually became detectable in mid-July and thereafter. The fertilizer placement had a significant effect on grain yields only in one field but not on canopy reflectance in all three fields. These observations suggest that the deficiency of N developed under field conditions is a dynamic phenomenon, which adds complexity for accurately defining "N deficiency" and effectively developing management strategies for in-season correction. Remote sensing throughout the season helps collect information about important interactions that have not been given enough attention in the past.
基金key project of the National Natural Science Foundation of China,Information Acquirement and Publish System of Shipping Lane in Harbor,the fund of Beijing Science and Technology Commission Network Monitoring and Application Demonstration in Food Security,the Program for New Century Excellent Talents in University,National Natural Science Foundation of ChinaProject,Fundamental Research Funds for the Central Universities
文摘The wireless sensor network (WSN) plays an important role in monitoring the environment near the harbor in order to make the ships nearby out of dangers and to optimize the utilization of limited sea routes. Based on the historical data collected by the buoys with sensing capacities, a novel data compression algorithm called adaptive time piecewise constant vector quantization (ATPCVQ) is proposed to utilize the principal components. The proposed system is capable of lowering the budget of wireless communication and enhancing the lifetime of sensor nodes subject to the constrain of data precision. Furthermore, the proposed algorithm is verified by using the practical data in Qinhuangdao Port of China.
基金Project (61201086) supported by the National Natural Science Foundation of ChinaProject (201506375060) supported by the China Scholarship Council+2 种基金Project (2013B090500007) supported by Guangdong Provincial Science and Technology Project,ChinaProject (2014509102205) supported by the Dongguan Municipal Project on the Integration of Industry,Education and Research,ChinaProject (2017GK5019) supported by 2017 Hunan-Tech&Innovation Investment Project,China
文摘To the existing spectrum sharing schemes in wireless-powered cognitive wireless sensor networks,the protocols are limited to either separate the primary and the secondary transmission or allow the secondary user to transmit signals in a time slot when it forwards the primary signal.In order to address this limitation,a novel cooperative spectrum sharing scheme is proposed,where the secondary transmission is multiplexed with both the primary transmission and the relay transmission.Specifically,the process of transmission is on a three-phase time-switching relaying basis.In the first phase,a cognitive sensor node SU1 scavenges energy from the primary transmission.In the second phase,another sensor node SU2 and primary transmitter simultaneously transmit signals to the SU1.In the third phase,the node SU1 can assist the primary transmission to acquire the opportunity of spectrum sharing.Joint decoding and interference cancellation technique is adopted at the receivers to retrieve the desired signals.We further derive the closed-form expressions for the outage probabilities of both the primary and secondary systems.Moreover,we address optimization of energy harvesting duration and power allocation coefficient strategy under performance criteria.An effective algorithm is then presented to solve the optimization problem.Simulation results demonstrate that with the optimized solutions,the sensor nodes with the proposed cooperative spectrum sharing scheme can utilize the spectrum in a more efficient manner without deteriorating the performance of the primary transmission,as compared with the existing one-directional scheme in the literature.
基金Supported by the National Science & Technology Pillar Program in the Eleventh Five-year Plan Period (No. 2007BAF10B00).
文摘For the discrete-time system which is subjected to uncoupled actuator faults and sensor faults simultaneously,a robust fault diagnosis method based on a proportional integral observer (PIO) is presented.The proposed PIO uses an additionally introduced integral term of the output errors to obtain the estimationof actuator faults. Besides, the sensor faults are regarded as the augment states so that the PIO cantrace them. Moreover, the convergence of the PIO is proved. A variable speed wind turbine(VWT) exampleis given to demonstrate the fast convergence and diagnosis precision of the proposed PIO.
文摘According to the characteristic of the sensor inertia, the dynamic prediction to improve the system dynamic precision is presented in this paper. With the recurrence calculation of time constant of the sensor, the system dynamic precision is greatly improved. The example using this method is given.
文摘The key of speed sensorless vector control system lies in the accurate orientation of magnetic field. In some field-oriented algorithms, the integrator of observers and the dead-time effect bring in system errors during the estimation of field position. In this paper, a saturated feedback integrator is used, and the dead-time effect is compen- sated by current positive feedback. Experiments were carried out on the hardware platform of MCK2407, with chip TMS320LF2407 from TI Company. The results show that the prooosed method is simole and effective, and the accuracy of field position is improved.
基金Supported by the National High Technology Research and Development Programme of China(No.2011AA010503)the National Natural Science Foundation of China(No.60903192)
文摘A traffic sensitive spectrum access scheme is proposed to satisfy the traffic load requirement of secondary users (SUs). In the proposed design, SU only accesses available channels which can meet the traffic demand. To achieve this, the expected transmission time (E3W) of the SU is calcu- lated first based on the delivery ratio. Then, the channel idle time is estimated based on the activity of primary users (PUs). Therefore, available channels with estimated idle time longer than ETr could be chosen. With high probability, the SU can finish transmission on these channels without disruption, thereby satisfying the traffic load demand of the SU. Finally, our method is extended to the multi-channel scenario where each SU can access multiple channels simultaneously. Performance analysis shows that our method satisfies the requirement of SUs while effectively improving the throughput.
文摘The time-frequency analysis of the signal acquired by a single ground-based microphone shows a two-dimensional interference pattern in the time-frequency plane,which is caused by the time delay of the received signal emitted from a low flying aircraft via the direct path and the ground-re-flected path. A model is developed for estimating the motion parameters of an aircraft flying along a straight line at a constant height and with a constant speed. Monte Carlo simulation results and ex-perimental results are presented to validate the model,and an error analysis of the model is presented to verify the effectiveness of the estimation scheme advocated.
基金supported by the National Basic Research Program of China (No.2014CB046904)the National Natural Science Foundation of China (Nos.41130742 and 11302242)
文摘Due to the difficulty and weakness of current stress measurement methods in deep soft rock, a new rheological stress recovery method of the determination of the three-dimensional(3D) stress tensor is proposed. It is supposed that rock stresses will recovery gradually with time and can be measured by embedding transducers into the borehole. In order to explore the applicability and accuracy of this method, analytical solutions are developed for stress measurement with the rheological stress recovery method in a viscoelastic surrounding rock, the rheological properties of which are depicted as both the Burger's model and a 3-parameter solid model. In such conditions, explicit analytical expressions for predicting time-dependent pressures on the transducer are derived. A parametric analysis is then adopted to investigate the influences of the grout solidification time and the mechanical properties of the grout layer. The results indicate that this method is suitable for stress measurement in deep soft rock, the characteristics of which are soft, fractured and subjected to high geo-stress.
基金Acknowledgements The supports provided for the paper by the National Natural Science Foundation of China (Grant No. 50778019) and the Natural Science Foundation of Beijing (Grant No. 8092024) are gratefully appreciated.
文摘The field test of a typical Tibetan ancient structure instrumented with displacement and acceleration transducers was conducted to measure time histories due to crowd walking and running. The test case is introduced firstly. The displacement time histories are then used to analyze the dynamic property such as fundamental frequency of vertical vibration and damping ratio of the test structure, and the acceleration time histories are applied to evaluate the floor vibration serviceability. The floor interaction and comparison of human walking and running are also discussed. Some valuable conclusions are given.
文摘Recent remote monitoring surveys of smoke produced by burning and forest fires using weather radar equipment showed excellent preliminary results, but their progress is hindered due to the high operating cost of radar systems. The fire danger rating index is a good indicator of the event occurrence probability, what contributes to the monitoring areas and adds value to the alert degree information. The application of FMA fire danger index "Formula de Monte Alegre" for areas in radar coverage radius of the S-band weather radar operated by the Meteorological Research Institute, IPMet, S^fo Paulo State University, efficiently optimize the use of the radar equipment, significantly reduce operational costs, enable new research and promise results which have already reduced the average response time between ignition and detection for less than 5 minutes. It reduces more than 50% response time considered optimal for conventional detection systems. Thus, the "FMA" values act as a trigger (on-off) in the remote monitoring system of forest fires, optimizing its use at low cost, avoiding the possible stress of equipment and enabling the advance of research monitoring, detection of burnings and forest fires using weather radar.
基金Supported by the projects from the State Administration of Traditional Chinese Medicine (200907001)National Science Foundation of China (No. 30825047 and 90709007)
文摘OBJECTIVE:H1N1 was a new and potentially serious infectious disease,in human,the severity of influenza can vary from mild to severe,thus to find an effective and safety way to control the influenza pandemic is of crucial importance.This retrospective study describes the duration of viral shedding in H1N1 patients that were hospitalized and treated in China.METHODS:Clinical data were collected from May to July,2009 in China for 963 patients with influenza A(H1N1) virus infection.Patients were treated based on the guidelines issued by the Chinese Ministry of Health.The primary outcome was duration of viral shedding and statistical comparisons were performed.RESULTS:In the patients with body temperature greater than 38.0℃,there were no differences in virus shedding duration among the patients taking oseltamivir within two days,patients undergoing Traditional Chinese Medicine(TCM) therapy or those receiving no drug therapy.In patients with body temperature 338.1℃,TCM therapy reduced the viral shedding duration(P<0.05,vs.oseltamivir therapy).Furthermore,taking oseltamivir two days after onset of symptoms might prolong the virus shedding duration(P<0.05,vs.taking oseltamivir less than 2 days of onset).CONCLUSION:TCM therapy is effective for reducing the length of virus shedding in patients with body temperature 338.0℃.Oseltamivir used for reducing virus shedding duration should be taken within two days of onset.
基金the National Key R&D Program of China(2016YFA0202703)Key-Area Research and Development Program of Guangdong Province(2018B030331001)+3 种基金the National Natural Science Foundation of China(61875015,81971770,52002027,and 82071970)Beijing Natural Science Foundation(JQ20038,2214083)China National Postdoctoral Program for Innovative Talent(BX20200380)the Fundamental Research Funds for the Central Universities。
文摘Schottky-contacted sensors have been demonstrated to show high sensitivity and fast response time in various sensing systems.In order to improve their sensing performance,the Schottky barriers height(SBH)at the interface of semiconductor and metal electrode should be adjusted to appropriate range to avoid low output or low sensitivity,which was induced by excessively high or low SBH,respectively.In this work,a simple and effective SBH tuning method by triboelectric generator(TENG)is proposed,the SBH can be effectively lowered by voltage pulses generated by TENG and gradually recover over time after withdrawing the TENG.Through combining the TENG treatment with piezotronic effect,a synergistic effect on lowering SBH was achieved.The change of SBH is increased by 3.8 to 12.8 times,compared with dependent TENG treatment and piezotronic effect,respectively.Furthermore,the recovery time of the TENG-lowered SBH can be greatly shortened from 1.5 h to 40 s by piezotronic effect.This work demonstrated a flexible and feasible SBH tuning method,which can be used to effectively improve the sensitivity of Schottky-contact sensor and sensing system.Our study also shows great potential in broadening the application scenarios of Schottky-contacted electronic devices.
文摘The key factor of the sensitivity in the FBG-based pH sensor is analyzed in detail. A multi-thin-layer structure of the gel coated cover was proposed and implemented with a special process. The sensors with the coated thickness of 420 ~m, 500 ~m, and 580 ~m were built up, respectively. The corresponding spectral shifts of 0.08nm, 0.13nm, and 0.22nm were detected when the pH sensors were soaked in the pH value of 3-9. Meanwhile, the sensor with the gel layer thickness of 580 ~tm was measured in the optimum measurement time period with the pH value changing from 3-12, in which the detected sensitivity of 52pm/pH was achieved in the pH range of 6-12.
基金the National High Technology Research and Development Program (863) of China(No.2009AA12Z322)
文摘When an aircraft moves under a low carrier-to-noise ratio (CNR) or at a high speed, increasing the sensitivity of global navigation satellite system (GNSS) receiver is a goal quite hard to achieve. A novel acquisition scheme assisted with micro-electro-mechanical-sensor (MEMS) inertial navigation system (INS) is presented to estimate the Doppler caused by user dynamics relative to each satellite ahead of time. Based on tightly coupled GNSS/INS estimation algorithm, MEMS INS Doppler error that can be achieved is first described. Then, by analyzing the mean acquisition time and signal detection probability, the MEMS INS-assisted acquisition capabilities in cold, warm and hot starts are quantitatively determined and compared with the standard GNSS acquisition capability. The simulations and comparisons have shown that: the acquisition time in cold start can be shortened by at least 23 s, the time in warm start can be shortened to i s and the acquisition capability is improved 95%, and the reaequisition time in hot start can be shortened by around 0.090 s and the capability can be enhanced 40%. The results demonstrate the validity of the novel method.