无线通信技术的发展对人们的生活和工作产生了重大影响,GSM(Global System for Mobile Communications)和蓝牙(Blue tooth)是人们日常生活中应用广泛的两种通信系统。我国GSM手机占用频段是GSM900MHz和GSM1800MHz,利用"蓝牙"...无线通信技术的发展对人们的生活和工作产生了重大影响,GSM(Global System for Mobile Communications)和蓝牙(Blue tooth)是人们日常生活中应用广泛的两种通信系统。我国GSM手机占用频段是GSM900MHz和GSM1800MHz,利用"蓝牙"技术,能够有效地简化移动通信终端设备之间的通信,而蓝牙的工作频段是2.45GHz。通过选用单同轴馈电法,同时激发TM10和TM01谐振模式,实现双频。应用仿真软件对该天线进行建模、参数的扫描和优化,设计可同时工作在GSM1.8GHz和蓝牙2.45GHz的小型化、双频段微带天线,来适应当前无线通信系统的应用需求。展开更多
A new hybrid technique is presented, which combines the Mode Matching (MM) method with the Method of Lines (MoL) to analyze a coaxial fed monopole antenna. The monopole antenna is dealt with using the MoL, while the M...A new hybrid technique is presented, which combines the Mode Matching (MM) method with the Method of Lines (MoL) to analyze a coaxial fed monopole antenna. The monopole antenna is dealt with using the MoL, while the MM method is used to analyze the coaxial feed system. Then, the two sub-problems are combined by enforcing point matching at the common regional interfaces. The input impedance is computed and compared with the measured data reported in literature, and the excellent agreement is observed.展开更多
Application of a DFIG （doubly-fed induction generator）, which is one of adjustable speed generators, to a gas engine cogeneration system has been investigated. To operate during a blackout as an emergency power supp...Application of a DFIG （doubly-fed induction generator）, which is one of adjustable speed generators, to a gas engine cogeneration system has been investigated. To operate during a blackout as an emergency power supply is one of important roles for the gas engine eogeneration system. In the case of conventional constant speed of synchronous generator, the amount of the allowed step load is limited to around 30% of the rated power. On the other hand, DFIG is expected to increase the amount of step load during the stand-alone operation. In this paper, it has been demonstrated that an increase in the gas engine speed resulted in an increase in the maximum amount of step load using experimental equipment with a real gas engine. It has been concluded that the proposed system can improve the performance of an emergency power supply at step-loading.展开更多
Objective： To investigate stretch-induced electrophysiological changes in chronically infarcted hearts and the effect of streptomycin （SM） on these changes in vivo. Methods： Sixty Wistar rats were divided randomly...Objective： To investigate stretch-induced electrophysiological changes in chronically infarcted hearts and the effect of streptomycin （SM） on these changes in vivo. Methods： Sixty Wistar rats were divided randomly into four groups： a control group （n=15）, an SM group （n=15）, a myocardial infarction （MI） group （n=15）, and an MI＋SM group （n=15）. Chronic MI was obtained by ligating the left anterior descending branch （LAD） of rat hearts for eight weeks. The in vivo blockade of stretch-activated ion channels （SACs） was achieved by intramuscular injection of SM （180 mg/（kg·d）） for seven days after operation. The hearts were stretched for 5 s by occlusion of the aortic arch. Suction electrodes were placed on the anterior wall of left ventricle to record the monophasic action potential （MAP）. The effect of stretching was examined by assessing the 90% monophasic action potential duration （MAPD90）, premature ventricular beats （PVBs）, and ventricular tachycardia （VT）. Results： The MAPD90 decreased during stretching in both the control （from （50.27±5.61） ms to （46.27±4.51） ms, P〈0.05） and MI groups （from （65.47±6.38） ms to （57.47±5.76 ms）, P〈0.01 ）. SM inhibited the decrease in MAPD90 during inflation （（46.27±4.51） ms vs. （49.53±3.52） ms, P〈0.05 in normal hearts; （57.47±5.76） ms vs. （61.87±5.33） ms, P〈0.05 in MI hearts）. The occurrence of PVBs and VT in the MI group increased compared with that in the control group （PVB： 7.93±1.66 vs. 1.80±0.86, P〈0.01; VT： 7 vs. 1, P〈0.05）. SM decreased the occurrence of PVBs in both normal and MI hearts （0.93±0.59 vs. 1.80±0.86 in normal hearts, P〈0.05; 5.40±1.18 vs. 7.93±1.66 in MI hearts, P〈0.01）. Conclusions： Stretch-induced MAPD90 changes and arrhythmias were observed in chronically infarcted myocardium. The use of SM in vivo decreased the incidence of PVBs but not of VT. This suggests that SACs may be involved in mechanoelectric feedback （MEF）, but that there might be other mechanisms involved in causing VT in chronic MI.展开更多
文摘无线通信技术的发展对人们的生活和工作产生了重大影响,GSM(Global System for Mobile Communications)和蓝牙(Blue tooth)是人们日常生活中应用广泛的两种通信系统。我国GSM手机占用频段是GSM900MHz和GSM1800MHz,利用"蓝牙"技术,能够有效地简化移动通信终端设备之间的通信,而蓝牙的工作频段是2.45GHz。通过选用单同轴馈电法,同时激发TM10和TM01谐振模式,实现双频。应用仿真软件对该天线进行建模、参数的扫描和优化,设计可同时工作在GSM1.8GHz和蓝牙2.45GHz的小型化、双频段微带天线,来适应当前无线通信系统的应用需求。
文摘A new hybrid technique is presented, which combines the Mode Matching (MM) method with the Method of Lines (MoL) to analyze a coaxial fed monopole antenna. The monopole antenna is dealt with using the MoL, while the MM method is used to analyze the coaxial feed system. Then, the two sub-problems are combined by enforcing point matching at the common regional interfaces. The input impedance is computed and compared with the measured data reported in literature, and the excellent agreement is observed.
文摘Application of a DFIG （doubly-fed induction generator）, which is one of adjustable speed generators, to a gas engine cogeneration system has been investigated. To operate during a blackout as an emergency power supply is one of important roles for the gas engine eogeneration system. In the case of conventional constant speed of synchronous generator, the amount of the allowed step load is limited to around 30% of the rated power. On the other hand, DFIG is expected to increase the amount of step load during the stand-alone operation. In this paper, it has been demonstrated that an increase in the gas engine speed resulted in an increase in the maximum amount of step load using experimental equipment with a real gas engine. It has been concluded that the proposed system can improve the performance of an emergency power supply at step-loading.
基金Project supported by the National Natural Science Foundation of China(No.81301343)
文摘Objective： To investigate stretch-induced electrophysiological changes in chronically infarcted hearts and the effect of streptomycin （SM） on these changes in vivo. Methods： Sixty Wistar rats were divided randomly into four groups： a control group （n=15）, an SM group （n=15）, a myocardial infarction （MI） group （n=15）, and an MI＋SM group （n=15）. Chronic MI was obtained by ligating the left anterior descending branch （LAD） of rat hearts for eight weeks. The in vivo blockade of stretch-activated ion channels （SACs） was achieved by intramuscular injection of SM （180 mg/（kg·d）） for seven days after operation. The hearts were stretched for 5 s by occlusion of the aortic arch. Suction electrodes were placed on the anterior wall of left ventricle to record the monophasic action potential （MAP）. The effect of stretching was examined by assessing the 90% monophasic action potential duration （MAPD90）, premature ventricular beats （PVBs）, and ventricular tachycardia （VT）. Results： The MAPD90 decreased during stretching in both the control （from （50.27±5.61） ms to （46.27±4.51） ms, P〈0.05） and MI groups （from （65.47±6.38） ms to （57.47±5.76 ms）, P〈0.01 ）. SM inhibited the decrease in MAPD90 during inflation （（46.27±4.51） ms vs. （49.53±3.52） ms, P〈0.05 in normal hearts; （57.47±5.76） ms vs. （61.87±5.33） ms, P〈0.05 in MI hearts）. The occurrence of PVBs and VT in the MI group increased compared with that in the control group （PVB： 7.93±1.66 vs. 1.80±0.86, P〈0.01; VT： 7 vs. 1, P〈0.05）. SM decreased the occurrence of PVBs in both normal and MI hearts （0.93±0.59 vs. 1.80±0.86 in normal hearts, P〈0.05; 5.40±1.18 vs. 7.93±1.66 in MI hearts, P〈0.01）. Conclusions： Stretch-induced MAPD90 changes and arrhythmias were observed in chronically infarcted myocardium. The use of SM in vivo decreased the incidence of PVBs but not of VT. This suggests that SACs may be involved in mechanoelectric feedback （MEF）, but that there might be other mechanisms involved in causing VT in chronic MI.
