随着各种新型雷达的出现或战时预留模式的采用,真实的战场电磁环境将越加复杂,大概率会出现种类未知且参数突变的雷达调制信号,对现有的调制方式识别算法带来严峻挑战。对此,分析雷达调制方式“未知”对识别结果的影响机理,将开集差分...随着各种新型雷达的出现或战时预留模式的采用,真实的战场电磁环境将越加复杂,大概率会出现种类未知且参数突变的雷达调制信号,对现有的调制方式识别算法带来严峻挑战。对此,分析雷达调制方式“未知”对识别结果的影响机理,将开集差分分布对齐(distribution alignment with open set difference,DAOD)算法引入雷达调制方式识别领域,设计具体应用的技术方案,并针对DAOD算法所需参数依靠先验知识或者试探选取问题,利用蜣螂优化(dung beetle optimizer,DBO)算法进行参数优化。仿真结果表明:在单个雷达调制方式未知情形下,精确度Accuracy和F-measure分值的平均值分别可达91.34%和95.11%;在多个雷达调制方式未知情形下,Accuracy和F-measure的平均值分别可达91.37%、93.69%;与DAOD算法相比,上述结果分别提升了3.77%、1.83%、21.17%和12.06%。因此,DBO-DAOD算法可有效提升未知雷达调制方式的识别率。展开更多
Renewable power modules such as the thermoelectric generator and the PV panel are featured by low output voltage and low power.Aiming at maximum output power,a high energy efficiency module integrated converter(MIC),a...Renewable power modules such as the thermoelectric generator and the PV panel are featured by low output voltage and low power.Aiming at maximum output power,a high energy efficiency module integrated converter(MIC),as shown in Fig.1,and its control strategy for series connected distributed(SCD)renewable power systems,as shown in Fig.2,are proposed.The topology of the MIC is an improved one of the conventional H-bridge Buck-Boost converter.展开更多
Thermo-hydraulic calculation and analysis for sub-module of Chinese HCSB TBM were carried out using FE code ANSYS. Results indicate that temperature distribution in materials used in sub-module is reasonable and accep...Thermo-hydraulic calculation and analysis for sub-module of Chinese HCSB TBM were carried out using FE code ANSYS. Results indicate that temperature distribution in materials used in sub-module is reasonable and acceptable.展开更多
If the degree distribution is chosen carefully, the irregular low-density parity-check (LDPC) codes can outperform the regular ones. An image transmission system is proposed by combining regular and irregular LDPC cod...If the degree distribution is chosen carefully, the irregular low-density parity-check (LDPC) codes can outperform the regular ones. An image transmission system is proposed by combining regular and irregular LDPC codes with 16QAM/64QAM modulation to improve both efficiency and reliability. Simulaton results show that LDPC codes are good coding schemes over fading channel in image communication with lower system complexity. More over, irregular codes can obtain a code gain of about 0.7 dB compared with regular ones when BER is 10 -4. So the irregular LDPC codes are more suitable for image transmission than the regular codes.展开更多
Considering that real communication signals corrupted by noise are generally nonstationary, and timefrequency distributions are especially suitable for the analysis of nonstationary signals, time-frequency distributio...Considering that real communication signals corrupted by noise are generally nonstationary, and timefrequency distributions are especially suitable for the analysis of nonstationary signals, time-frequency distributions are introduced for the modulation classification of communication signals： The extracted time-frequency features have good classification information, and they are insensitive to signal to noise ratio （SNR） variation. According to good classification by the correct rate of a neural network classifier, a multilayer perceptron （MLP） classifier with better generalization, as well as, addition of time-frequency features set for classifying six different modulation types has been proposed. Computer simulations show that the MLP classifier outperforms the decision-theoretic classifier at low SNRs, and the classification experiments for real MPSK signals verify engineering significance of the MLP classifier.展开更多
A 3D temperature field distribution of biological tissue for superficial hyperthermia using a pulse modulated microwave （PMMW） was presented. A 3D sliced homogeneous phantom was radiated by the PMMW and an infrared ...A 3D temperature field distribution of biological tissue for superficial hyperthermia using a pulse modulated microwave （PMMW） was presented. A 3D sliced homogeneous phantom was radiated by the PMMW and an infrared thermal imager was applied to image temperature distribution throughout the phantom. The period of the PMMW is 3 s and the output power is 35 W. The temperature rises by at least 3 ℃ in the phantom when the duty cycle varies from 1/3, 1/2, 2/3 to 1 （denoted by scenarios 1-4）. Both the accumulative temperature-volume histogram and the relative depth-area ratio histogram show that the maximum temperature rise （MTR） is 6.6 and 8 ℃ in scenarios 2 and 3, and they are superior to scenarios 1 and 4. Furthermore, the PMMW can control temperature field distribution of biological tissue. It provides both preliminary basis for thermal volume control and new technology for temperature control and monitor in superficial hyperthermia.展开更多
文摘随着各种新型雷达的出现或战时预留模式的采用,真实的战场电磁环境将越加复杂,大概率会出现种类未知且参数突变的雷达调制信号,对现有的调制方式识别算法带来严峻挑战。对此,分析雷达调制方式“未知”对识别结果的影响机理,将开集差分分布对齐(distribution alignment with open set difference,DAOD)算法引入雷达调制方式识别领域,设计具体应用的技术方案,并针对DAOD算法所需参数依靠先验知识或者试探选取问题,利用蜣螂优化(dung beetle optimizer,DBO)算法进行参数优化。仿真结果表明:在单个雷达调制方式未知情形下,精确度Accuracy和F-measure分值的平均值分别可达91.34%和95.11%;在多个雷达调制方式未知情形下,Accuracy和F-measure的平均值分别可达91.37%、93.69%;与DAOD算法相比,上述结果分别提升了3.77%、1.83%、21.17%和12.06%。因此,DBO-DAOD算法可有效提升未知雷达调制方式的识别率。
文摘Renewable power modules such as the thermoelectric generator and the PV panel are featured by low output voltage and low power.Aiming at maximum output power,a high energy efficiency module integrated converter(MIC),as shown in Fig.1,and its control strategy for series connected distributed(SCD)renewable power systems,as shown in Fig.2,are proposed.The topology of the MIC is an improved one of the conventional H-bridge Buck-Boost converter.
文摘Thermo-hydraulic calculation and analysis for sub-module of Chinese HCSB TBM were carried out using FE code ANSYS. Results indicate that temperature distribution in materials used in sub-module is reasonable and acceptable.
文摘If the degree distribution is chosen carefully, the irregular low-density parity-check (LDPC) codes can outperform the regular ones. An image transmission system is proposed by combining regular and irregular LDPC codes with 16QAM/64QAM modulation to improve both efficiency and reliability. Simulaton results show that LDPC codes are good coding schemes over fading channel in image communication with lower system complexity. More over, irregular codes can obtain a code gain of about 0.7 dB compared with regular ones when BER is 10 -4. So the irregular LDPC codes are more suitable for image transmission than the regular codes.
文摘Considering that real communication signals corrupted by noise are generally nonstationary, and timefrequency distributions are especially suitable for the analysis of nonstationary signals, time-frequency distributions are introduced for the modulation classification of communication signals： The extracted time-frequency features have good classification information, and they are insensitive to signal to noise ratio （SNR） variation. According to good classification by the correct rate of a neural network classifier, a multilayer perceptron （MLP） classifier with better generalization, as well as, addition of time-frequency features set for classifying six different modulation types has been proposed. Computer simulations show that the MLP classifier outperforms the decision-theoretic classifier at low SNRs, and the classification experiments for real MPSK signals verify engineering significance of the MLP classifier.
基金Project(50977064) supported by the National Natural Science Foundation of China
文摘A 3D temperature field distribution of biological tissue for superficial hyperthermia using a pulse modulated microwave （PMMW） was presented. A 3D sliced homogeneous phantom was radiated by the PMMW and an infrared thermal imager was applied to image temperature distribution throughout the phantom. The period of the PMMW is 3 s and the output power is 35 W. The temperature rises by at least 3 ℃ in the phantom when the duty cycle varies from 1/3, 1/2, 2/3 to 1 （denoted by scenarios 1-4）. Both the accumulative temperature-volume histogram and the relative depth-area ratio histogram show that the maximum temperature rise （MTR） is 6.6 and 8 ℃ in scenarios 2 and 3, and they are superior to scenarios 1 and 4. Furthermore, the PMMW can control temperature field distribution of biological tissue. It provides both preliminary basis for thermal volume control and new technology for temperature control and monitor in superficial hyperthermia.
