A general method of calculating the saturable leakage reactances of squirrelcage asynchronous motors is presented.The method synthesized the variety of effectswhich affect the saturation of leakage magnetic circuit.An...A general method of calculating the saturable leakage reactances of squirrelcage asynchronous motors is presented.The method synthesized the variety of effectswhich affect the saturation of leakage magnetic circuit.And the saturable reactances canbe precisely evaluated in any running condition.The computation results of Y-series mo-tors are in good agreement with the test ones.展开更多
A new 300 MVA/1350 MJ motor generator (MG) will be built to feed all of the poloidal field power supplies (PFPS) and auxiliary heating power supplies of the HL-2M tokamak. The MG has a vertical-shaft salient pole ...A new 300 MVA/1350 MJ motor generator (MG) will be built to feed all of the poloidal field power supplies (PFPS) and auxiliary heating power supplies of the HL-2M tokamak. The MG has a vertical-shaft salient pole 6-phase synchronous generator and a coaxial 8500 kW induction motor. The Ohmic heating power supply (OHPS) consisting of 4-quadrant DC pulsed convertor is the one with the highest parameters among the PFPS. Therefore, the match between the generator and the OHPS is very important. The matching study with Matlab/Simulink is described in this paper. The simulation results show that the subtransient reactance of the generator is closely related to the inversion operation of the OHPS. By setting various subtransient reactance in the simulation generator model and considering the cost reduction, the optimized parameters are obtained as xd" = 0.405 p.u. at 100 Hz for the generator. The models built in the simulation can be used as an important tool for studying the dynamic characteristics and the control strategy of other HL-2M PFPSes.展开更多
Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the...Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the second generator by errors in the rotor rotating speed calculation are found,and the tuning method of the speed related parameters are given.The damping and reverse tuning characteristics of power system stabilizers(PSSs)in the digital automatic voltage regulator(AVR)are compared and investigated in the frequency range of 0.18-1.1 Hz.The efficiency of the proposed tuning method for ensuring power system stability is verified by RTDS.Finally,field tests show the validity of the laboratory test results.展开更多
More Electrical Aircraft(MEA)which replaces the hydraulic and pneumatic power by electrical power leads to reducing emissions and fuel consumption.The MEA concept has led to a growing use of the starter/generator(S/G)...More Electrical Aircraft(MEA)which replaces the hydraulic and pneumatic power by electrical power leads to reducing emissions and fuel consumption.The MEA concept has led to a growing use of the starter/generator(S/G)system.Permanent magnet(PM)machines have been gaining interests for aircraft S/G system application over the last few years.This is mainly due to the several advantages,including high power density,high efficiency and high speed ability.The shortcoming of the PM machines is the de-excitation problem in case of a failure,which is a main issue for the aircraft application.However,by using a PM machine with high reactance or multiphase configuration,the fault-tolerant ability can be improved.In terms of the aircraft S/G system,this paper is going to present a comprehensive analysis of PM machines.Firstly,the state-of-the-art of PM starter/generator(PMS/G)is summarized and the basic structure of PMS/G system is analyzed.Next,key technologies of the PMS/G system are summarized and analyzed.Finally,a flux weakening fault protection strategy that is used to suppress the turn-to-turn short circuit(SC)current is studied,simulated and verified.With the breakthrough of key technologies based on the development of high temperature electromagnetic material and high temperature power electronics,the PMS/G will be a potential candidate for aircraft S/G system including the embedded power generation system.展开更多
We study the interaction of a uniform, cold and collisional plasma with a test charged particle moving off-axis at a constant speed down a cylindrical tube with a resistive thick metallic wall. Upon matching the elect...We study the interaction of a uniform, cold and collisional plasma with a test charged particle moving off-axis at a constant speed down a cylindrical tube with a resistive thick metallic wall. Upon matching the electromagnetic field components at all interfaces, the induced monopole electromagnetic fields in the plasma are obtained in the frequency domain. An expression for the plasma electric resistance and reactance is derived and analyzed numerically for some representative parameters. Near the plasma resonant frequency, the plasma resistance evolves with frequency like a parallel RLC resonator with peak resistance at the plasma frequency pe, while the plasma reactance can be capacitive or inductive in nature depending on the frequency under consideration.展开更多
Racehorses in training are in situations of repeated stress that may have effects on hydration and health.It was hypothesized that daily consumption of a structured water(SW)product for 4 weeks will result in improved...Racehorses in training are in situations of repeated stress that may have effects on hydration and health.It was hypothesized that daily consumption of a structured water(SW)product for 4 weeks will result in improved hydration,improved upper airway health and increased heart rate variability.Two groups of Thoroughbred racehorses matched for physiological,training and racing attributes were studied for 4 weeks.One group(n=17)received 10 L(about 15%)of their daily water as SW(followed by ad libitum filtered deep well water)and the control group(n=15)only filtered deep well water.Blood samples and bioelectrical impedance analysis(BIA)measures were obtained at baseline,2 and 4 weeks.Hydration was assessed using BIA.The upper airway was assessed by nasopharyngeal endoscopy at baseline and weekly within 60 minutes of breezing.On weekly breeze days heart rate was recorded at rest,during exercise and recovery and data were analysed for heart rate variability.Compared to controls,horses drinking SW showed increased hydration improved upper airway health post-breezing and increased heart rate variability.It is concluded that drinking 10 L daily of SW increased hydration and may have conferred some wellness benefits.展开更多
The most important elements of “intellectual networks” (Smart Grid) are the systems of monitoring the parameters of electrical equipment. Information-measuring systems (IMS), which described in this paper, were prop...The most important elements of “intellectual networks” (Smart Grid) are the systems of monitoring the parameters of electrical equipment. Information-measuring systems (IMS), which described in this paper, were proposed to use together with rapid digital protection against short-circuit regimes in transformer windings. This paper presents an application’s experience of LVI-testing, some results of the use of Frequency Response Analysis (FRA) to check the condition of transformer windings and infra-red control results of electrical equipment. The LVI method and short-circuit inductive reactance measurements are sensitive for detecting such faults as radial, axial winding deformations, a twisting of low-voltage or regulating winding, a losing of winding’s pressing and others.展开更多
We report the accurate determinations of quantum mechanical state-to-state probabilities tor reactions Cl + H2 - HCl + H and H' + HCl - H'Cl + H by the generalized Newton variational principle, on the most acc...We report the accurate determinations of quantum mechanical state-to-state probabilities tor reactions Cl + H2 - HCl + H and H' + HCl - H'Cl + H by the generalized Newton variational principle, on the most accurate available potential energy surface. We compare the results for three versions of realistic potential energy surfaces, and to those from hyperspherical close-coupling calculations.展开更多
Introduction:Impulse oscillometry(IOS)employs high frequency sinusoidal or impulse pressure and flow waveforms to interrogate the mechanical properties of the respiratory system.It has special applications to preschoo...Introduction:Impulse oscillometry(IOS)employs high frequency sinusoidal or impulse pressure and flow waveforms to interrogate the mechanical properties of the respiratory system.It has special applications to preschool and younger children who may have difficulty performing the repetitive forced expiratory maneuvers required for spirometry.Case presentation:We present a case illustrating improvements of respiratory system mechanics measured by IOS in a 6-year-old child with cystic fibrosis(CF)who demonstrated clinical and radiological improvement after a course of therapy with hospitalization and intravenous antibiotics,and initiation of a cystic fibrosis transmembrane regulator(CFTR)protein corrector/potentiator agent.We also report a new finding:observed lower than expected reactance at low compared to high frequencies("reactance inversion").Conclusion:Reactance inversion may reflect parallel pathway inhomogeneities in resistance and elastance or intrabreath airway inertance changes in young children with CF.Further study is needed in children with airway obstruction due to asthma,cystic fibrosis,and chronic lung disease of infancy to demonstrate the prevalence of this finding and whether it is specific to a measurement device.展开更多
Labisia pumila(Kacip fatimah)is a popular medicinal plant in Malaysia.The constituents of this plant have been reported to possess anticancer,antioxidant and anti-inflammatory properties.The growth and production of L...Labisia pumila(Kacip fatimah)is a popular medicinal plant in Malaysia.The constituents of this plant have been reported to possess anticancer,antioxidant and anti-inflammatory properties.The growth and production of L.pumila is greatly influenced by the plant water status.Current techniques to measure plant water status are generally based on the plant soil moisture,which apparently did not indicate the real water content inside the plant.There are other techniques to measure directly on the plant such as based on leaf water potential(LWP)and relative water content(RWC).However,these techniques are destructive and time consuming.In this study,four levels of evapotranspiration replacement(ER)treatment which were 100%ER,75%ER,50%ER and 25%ER was applied to 30 polybags of L.pumila plants.The plant water status was measured using an impedance spectroscopy technique.A pair of electrocardiogram(ECG)electrode connected to an impedance analyzer board was used to measure the impedance value of the leaf samples noninvasively.Plant water status parameters such as LWP,RWC,volumetric moisture content(VMC),and leaf thickness were measured using standard methods.The results show that after 20 weeks of treatment,25%ER had the highest impedance value ranged from 0.10 MX to 0.15 MX at the frequency of 70–100 kHz.The resistance of 100%ER at 20 weeks of treatment increased from 0.70 kX to 1.23 kX as the reactance decreased from 0.51 kX to 0.28 kX.Comparatively,the resistance of 25%ER increased from 1 kX to 1.10 kX as the reactance decreased from 0.88 kX to 0.83 kX.The polynomial regression of impedance measurements with plant water status parameters(VMC,leaf thickness,LWP and RWC)shows that LWP and RWC had the highest R2(0.78,0.73).The results show that impedance measurement technique is auspicious to evaluate plant water status.展开更多
文摘A general method of calculating the saturable leakage reactances of squirrelcage asynchronous motors is presented.The method synthesized the variety of effectswhich affect the saturation of leakage magnetic circuit.And the saturable reactances canbe precisely evaluated in any running condition.The computation results of Y-series mo-tors are in good agreement with the test ones.
文摘A new 300 MVA/1350 MJ motor generator (MG) will be built to feed all of the poloidal field power supplies (PFPS) and auxiliary heating power supplies of the HL-2M tokamak. The MG has a vertical-shaft salient pole 6-phase synchronous generator and a coaxial 8500 kW induction motor. The Ohmic heating power supply (OHPS) consisting of 4-quadrant DC pulsed convertor is the one with the highest parameters among the PFPS. Therefore, the match between the generator and the OHPS is very important. The matching study with Matlab/Simulink is described in this paper. The simulation results show that the subtransient reactance of the generator is closely related to the inversion operation of the OHPS. By setting various subtransient reactance in the simulation generator model and considering the cost reduction, the optimized parameters are obtained as xd" = 0.405 p.u. at 100 Hz for the generator. The models built in the simulation can be used as an important tool for studying the dynamic characteristics and the control strategy of other HL-2M PFPSes.
文摘Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the second generator by errors in the rotor rotating speed calculation are found,and the tuning method of the speed related parameters are given.The damping and reverse tuning characteristics of power system stabilizers(PSSs)in the digital automatic voltage regulator(AVR)are compared and investigated in the frequency range of 0.18-1.1 Hz.The efficiency of the proposed tuning method for ensuring power system stability is verified by RTDS.Finally,field tests show the validity of the laboratory test results.
基金This work was supported in part by National Natural Science Foundation for Excellent Young Scholar of China under Award 51622704Jiangsu Provincial Science Funds for Distinguished Young Scientists under Award BK20150033.
文摘More Electrical Aircraft(MEA)which replaces the hydraulic and pneumatic power by electrical power leads to reducing emissions and fuel consumption.The MEA concept has led to a growing use of the starter/generator(S/G)system.Permanent magnet(PM)machines have been gaining interests for aircraft S/G system application over the last few years.This is mainly due to the several advantages,including high power density,high efficiency and high speed ability.The shortcoming of the PM machines is the de-excitation problem in case of a failure,which is a main issue for the aircraft application.However,by using a PM machine with high reactance or multiphase configuration,the fault-tolerant ability can be improved.In terms of the aircraft S/G system,this paper is going to present a comprehensive analysis of PM machines.Firstly,the state-of-the-art of PM starter/generator(PMS/G)is summarized and the basic structure of PMS/G system is analyzed.Next,key technologies of the PMS/G system are summarized and analyzed.Finally,a flux weakening fault protection strategy that is used to suppress the turn-to-turn short circuit(SC)current is studied,simulated and verified.With the breakthrough of key technologies based on the development of high temperature electromagnetic material and high temperature power electronics,the PMS/G will be a potential candidate for aircraft S/G system including the embedded power generation system.
基金Supported by the Yarmouk Universitythe KUSTAR–KAIST Institution Fund
文摘We study the interaction of a uniform, cold and collisional plasma with a test charged particle moving off-axis at a constant speed down a cylindrical tube with a resistive thick metallic wall. Upon matching the electromagnetic field components at all interfaces, the induced monopole electromagnetic fields in the plasma are obtained in the frequency domain. An expression for the plasma electric resistance and reactance is derived and analyzed numerically for some representative parameters. Near the plasma resonant frequency, the plasma resistance evolves with frequency like a parallel RLC resonator with peak resistance at the plasma frequency pe, while the plasma reactance can be capacitive or inductive in nature depending on the frequency under consideration.
基金This research was funded by Defiance Brands Inc,Nashville,TN,USA.
文摘Racehorses in training are in situations of repeated stress that may have effects on hydration and health.It was hypothesized that daily consumption of a structured water(SW)product for 4 weeks will result in improved hydration,improved upper airway health and increased heart rate variability.Two groups of Thoroughbred racehorses matched for physiological,training and racing attributes were studied for 4 weeks.One group(n=17)received 10 L(about 15%)of their daily water as SW(followed by ad libitum filtered deep well water)and the control group(n=15)only filtered deep well water.Blood samples and bioelectrical impedance analysis(BIA)measures were obtained at baseline,2 and 4 weeks.Hydration was assessed using BIA.The upper airway was assessed by nasopharyngeal endoscopy at baseline and weekly within 60 minutes of breezing.On weekly breeze days heart rate was recorded at rest,during exercise and recovery and data were analysed for heart rate variability.Compared to controls,horses drinking SW showed increased hydration improved upper airway health post-breezing and increased heart rate variability.It is concluded that drinking 10 L daily of SW increased hydration and may have conferred some wellness benefits.
文摘The most important elements of “intellectual networks” (Smart Grid) are the systems of monitoring the parameters of electrical equipment. Information-measuring systems (IMS), which described in this paper, were proposed to use together with rapid digital protection against short-circuit regimes in transformer windings. This paper presents an application’s experience of LVI-testing, some results of the use of Frequency Response Analysis (FRA) to check the condition of transformer windings and infra-red control results of electrical equipment. The LVI method and short-circuit inductive reactance measurements are sensitive for detecting such faults as radial, axial winding deformations, a twisting of low-voltage or regulating winding, a losing of winding’s pressing and others.
文摘We report the accurate determinations of quantum mechanical state-to-state probabilities tor reactions Cl + H2 - HCl + H and H' + HCl - H'Cl + H by the generalized Newton variational principle, on the most accurate available potential energy surface. We compare the results for three versions of realistic potential energy surfaces, and to those from hyperspherical close-coupling calculations.
文摘Introduction:Impulse oscillometry(IOS)employs high frequency sinusoidal or impulse pressure and flow waveforms to interrogate the mechanical properties of the respiratory system.It has special applications to preschool and younger children who may have difficulty performing the repetitive forced expiratory maneuvers required for spirometry.Case presentation:We present a case illustrating improvements of respiratory system mechanics measured by IOS in a 6-year-old child with cystic fibrosis(CF)who demonstrated clinical and radiological improvement after a course of therapy with hospitalization and intravenous antibiotics,and initiation of a cystic fibrosis transmembrane regulator(CFTR)protein corrector/potentiator agent.We also report a new finding:observed lower than expected reactance at low compared to high frequencies("reactance inversion").Conclusion:Reactance inversion may reflect parallel pathway inhomogeneities in resistance and elastance or intrabreath airway inertance changes in young children with CF.Further study is needed in children with airway obstruction due to asthma,cystic fibrosis,and chronic lung disease of infancy to demonstrate the prevalence of this finding and whether it is specific to a measurement device.
基金The authors gratefully acknowledge the financial support from the Ministry of Education Malaysia and Universiti Putra Malaysia with the UPM Research Grant Scheme(Project Code:GP-IPS/2013/9399814)The authors would also like to acknowledge Mrs.Nadirah Roslan who was involved in data collection process.
文摘Labisia pumila(Kacip fatimah)is a popular medicinal plant in Malaysia.The constituents of this plant have been reported to possess anticancer,antioxidant and anti-inflammatory properties.The growth and production of L.pumila is greatly influenced by the plant water status.Current techniques to measure plant water status are generally based on the plant soil moisture,which apparently did not indicate the real water content inside the plant.There are other techniques to measure directly on the plant such as based on leaf water potential(LWP)and relative water content(RWC).However,these techniques are destructive and time consuming.In this study,four levels of evapotranspiration replacement(ER)treatment which were 100%ER,75%ER,50%ER and 25%ER was applied to 30 polybags of L.pumila plants.The plant water status was measured using an impedance spectroscopy technique.A pair of electrocardiogram(ECG)electrode connected to an impedance analyzer board was used to measure the impedance value of the leaf samples noninvasively.Plant water status parameters such as LWP,RWC,volumetric moisture content(VMC),and leaf thickness were measured using standard methods.The results show that after 20 weeks of treatment,25%ER had the highest impedance value ranged from 0.10 MX to 0.15 MX at the frequency of 70–100 kHz.The resistance of 100%ER at 20 weeks of treatment increased from 0.70 kX to 1.23 kX as the reactance decreased from 0.51 kX to 0.28 kX.Comparatively,the resistance of 25%ER increased from 1 kX to 1.10 kX as the reactance decreased from 0.88 kX to 0.83 kX.The polynomial regression of impedance measurements with plant water status parameters(VMC,leaf thickness,LWP and RWC)shows that LWP and RWC had the highest R2(0.78,0.73).The results show that impedance measurement technique is auspicious to evaluate plant water status.