Electrostatic monitoring technology of particle charging information can facilitate online monitoring of aero-engine,which effectively enhances engine fault diagnosis and health managements.Unlike traditional engine s...Electrostatic monitoring technology of particle charging information can facilitate online monitoring of aero-engine,which effectively enhances engine fault diagnosis and health managements.Unlike traditional engine state monitoring technologies,aircraft engine monitoring by gas path electrostatic monitoring not only covers the predicted information source itself,but also detects the information that can provide an early warnings for initial fault states through gas path charging levels.This paper establishes a non-stationary time sequence change-point model for anomaly recognition of electrostatic signals based on change-point theory combined with difference method of non-stationary time series.Finally,electrostatic induction data were utilized by the engine life test for a particular aircraft to validate the proposed algorithm.The results indicate that the activity level and the event rate were0.5—0.8(nc)and 50%,respectively,which were far greater than 4—12(pc)and 0—4% under normal working conditions of the engine.展开更多
One of the main concerns in particle pneumatic conveying process is the possibility of hazards for operation safety due to the electrostatic charge generation as a result of collisions between particles and the equipm...One of the main concerns in particle pneumatic conveying process is the possibility of hazards for operation safety due to the electrostatic charge generation as a result of collisions between particles and the equipment wall. Indeed, the electrostatic discharge can occur in the equipment leading to fire or explosion. Simulation of these kinds of processes plays an important role in understanding the various aspects of the system in order to production loss prevention. This paper deals with the simulation of particle pneumatic conveying process inside an inclined tube using a particular method. In this method, the electrification of particles inside the tube is influenced by the vertical collision velocity against the tube wall. Simulation of the particle movements inside the tube, generation of electrostatic charges over the particle surfaces as well as the possibility of fire as a result of discharging the electrostatic energy are investigated. The possibility of fire is investigated by comparing the amount of electrostatic energy with minimum ignition energy (MIE) of the particles. The effect of particle properties including the size and mechanical ones in the simulation is studied. Finally, several solutions are proposed to manage the risk of fire and explosion. As results, the electrostatic energy (E) is beyond the MIE, and the electrostatic discharge can occur leading to explosion for the diameters more than 2 mm and also for elasticity constants lower than 140 MPa. Eventually, there is no hazard of fire and explosion, since all calculated electrostatic energy for the change of Particle Poisson’s ratio varying from 0.1 to 0.9 is less than the MIE value for the air flow rate of 10 m3/h.展开更多
Based on the electrical model of body area communication, the change tendency of chan nel gain in 100 kHz 10 MHz band was experimentally analyzed and verified. Results show that chan nel gain was flat and signal a...Based on the electrical model of body area communication, the change tendency of chan nel gain in 100 kHz 10 MHz band was experimentally analyzed and verified. Results show that chan nel gain was flat and signal attenuation was approximately 43 dB in 1 MHz 10 MHz band. The char acteristics of the channel were taken into account in the design of body area spread spectrum com munication and its multiuser receiver issue. BER Eb/No curves of single user and multiuser were de rived by simulation. The characteristics of body area commutation channel were studied and the fea sibility of introducing spread spectrum theory to body area communication was verified.展开更多
The development of non-injection route for protein drugs, especially oral administration, has been the main focus of controlled release of drugs. To overcome obstacles unsolved such as enzyme degradation and penetrati...The development of non-injection route for protein drugs, especially oral administration, has been the main focus of controlled release of drugs. To overcome obstacles unsolved such as enzyme degradation and penetration barrier of intestinal epi- thelium, technologies using microspheres as carrier of protein drugs have been proven potential to realize oral administration. It has been demonstrated that microspheres can not only protect proteins, but also facilitate the penetration and absorption through Peyer’s patches when the size is smaller than 10 μm. Therefore, the objective of this paper is to prepare protein-loaded microspheres with size ≤ 10 μm. Electrostatic droplet generation technology was used with insulin and hemoglobin as drug models and so- dium alginate as microsphere material. By decreas- ing the surface tension of feed solution by adding surfactant, and improving electric field distribution by changing the shape of container and electrode for gelation solution, protein-loaded microspheres with mean size less than 10 μm were successfully pro- duced through needle with diameter of 400 μm. The microspheres showed good sphericity and narrow size distribution. The mean standard variance of size distribution was 1.61. The encapsulation efficiency of proteins was over 70%. Moreover, the significance analysis of factors influencing the size of protein loaded microspheres was carried out through or- thogonal experiments, which showed that output voltage (U), needle diameter (D) and the distance between needle tips to the surface of gelation solu- tion (δ ) influenced significantly the size of micro-spheres. Finally, the statistic analysis showed that when confidence level was α=0.05, and α=0.1, con- fidence interval of microsphere size can be (6.2545, 10.1735) and (6.6022, 9.8258) correspondingly, suggesting that there is good repeatability and reli- ability for improving electrostatic droplet generation technology to prepare protein-loaded microspheres with size ≤10 μm.展开更多
滤料作为袋式除尘器的核心,对其过滤性能具有决定性作用。为了提高过滤性能以满足日益严格的排放要求,基于熔融静电纺丝法自行设计了熔融静电纺丝装置,并进行了滤料纤维的制备。此外,运用扫描电镜(Scanning Electron Microscopy,SEM)、...滤料作为袋式除尘器的核心,对其过滤性能具有决定性作用。为了提高过滤性能以满足日益严格的排放要求,基于熔融静电纺丝法自行设计了熔融静电纺丝装置,并进行了滤料纤维的制备。此外,运用扫描电镜(Scanning Electron Microscopy,SEM)、差示扫描量热(Differential Scanning Calorimeter,DSC)、红外光谱分析(Infrared Radiation,IR)、分粒级过滤效率和阻力测试等多种方法对纤维性能进行了分析。结果表明:自行设计的试验装置可用于熔融静电纺丝;在一定范围内,随着纺丝温度、电场强度和接收距离的提高,纤维直径减小;熔融静电纺丝前后,高分子材料结晶程度和分子结构没有发生明显变化;熔融静电纺丝纤维滤料具有“高效低阻”的特点,验证了其在改善袋式除尘器滤料性能上应用的可行性。展开更多
基金supported by the Initial Scientific Research Fund (No.2015QD02S)the Foundation Research Funds for the Central Universities (No.3122016A004, 3122017027)
文摘Electrostatic monitoring technology of particle charging information can facilitate online monitoring of aero-engine,which effectively enhances engine fault diagnosis and health managements.Unlike traditional engine state monitoring technologies,aircraft engine monitoring by gas path electrostatic monitoring not only covers the predicted information source itself,but also detects the information that can provide an early warnings for initial fault states through gas path charging levels.This paper establishes a non-stationary time sequence change-point model for anomaly recognition of electrostatic signals based on change-point theory combined with difference method of non-stationary time series.Finally,electrostatic induction data were utilized by the engine life test for a particular aircraft to validate the proposed algorithm.The results indicate that the activity level and the event rate were0.5—0.8(nc)and 50%,respectively,which were far greater than 4—12(pc)and 0—4% under normal working conditions of the engine.
文摘One of the main concerns in particle pneumatic conveying process is the possibility of hazards for operation safety due to the electrostatic charge generation as a result of collisions between particles and the equipment wall. Indeed, the electrostatic discharge can occur in the equipment leading to fire or explosion. Simulation of these kinds of processes plays an important role in understanding the various aspects of the system in order to production loss prevention. This paper deals with the simulation of particle pneumatic conveying process inside an inclined tube using a particular method. In this method, the electrification of particles inside the tube is influenced by the vertical collision velocity against the tube wall. Simulation of the particle movements inside the tube, generation of electrostatic charges over the particle surfaces as well as the possibility of fire as a result of discharging the electrostatic energy are investigated. The possibility of fire is investigated by comparing the amount of electrostatic energy with minimum ignition energy (MIE) of the particles. The effect of particle properties including the size and mechanical ones in the simulation is studied. Finally, several solutions are proposed to manage the risk of fire and explosion. As results, the electrostatic energy (E) is beyond the MIE, and the electrostatic discharge can occur leading to explosion for the diameters more than 2 mm and also for elasticity constants lower than 140 MPa. Eventually, there is no hazard of fire and explosion, since all calculated electrostatic energy for the change of Particle Poisson’s ratio varying from 0.1 to 0.9 is less than the MIE value for the air flow rate of 10 m3/h.
基金Supported by the Ministerial Level Advanced Research Foundation(7130819)
文摘Based on the electrical model of body area communication, the change tendency of chan nel gain in 100 kHz 10 MHz band was experimentally analyzed and verified. Results show that chan nel gain was flat and signal attenuation was approximately 43 dB in 1 MHz 10 MHz band. The char acteristics of the channel were taken into account in the design of body area spread spectrum com munication and its multiuser receiver issue. BER Eb/No curves of single user and multiuser were de rived by simulation. The characteristics of body area commutation channel were studied and the fea sibility of introducing spread spectrum theory to body area communication was verified.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 50373046 and 20176056）.
文摘The development of non-injection route for protein drugs, especially oral administration, has been the main focus of controlled release of drugs. To overcome obstacles unsolved such as enzyme degradation and penetration barrier of intestinal epi- thelium, technologies using microspheres as carrier of protein drugs have been proven potential to realize oral administration. It has been demonstrated that microspheres can not only protect proteins, but also facilitate the penetration and absorption through Peyer’s patches when the size is smaller than 10 μm. Therefore, the objective of this paper is to prepare protein-loaded microspheres with size ≤ 10 μm. Electrostatic droplet generation technology was used with insulin and hemoglobin as drug models and so- dium alginate as microsphere material. By decreas- ing the surface tension of feed solution by adding surfactant, and improving electric field distribution by changing the shape of container and electrode for gelation solution, protein-loaded microspheres with mean size less than 10 μm were successfully pro- duced through needle with diameter of 400 μm. The microspheres showed good sphericity and narrow size distribution. The mean standard variance of size distribution was 1.61. The encapsulation efficiency of proteins was over 70%. Moreover, the significance analysis of factors influencing the size of protein loaded microspheres was carried out through or- thogonal experiments, which showed that output voltage (U), needle diameter (D) and the distance between needle tips to the surface of gelation solu- tion (δ ) influenced significantly the size of micro-spheres. Finally, the statistic analysis showed that when confidence level was α=0.05, and α=0.1, con- fidence interval of microsphere size can be (6.2545, 10.1735) and (6.6022, 9.8258) correspondingly, suggesting that there is good repeatability and reli- ability for improving electrostatic droplet generation technology to prepare protein-loaded microspheres with size ≤10 μm.
