PIN二极管的高功率微波响应

利用自行编制的半导体器件模拟程序 m PND1 D(采用时域有限差分方法 ,求解器件内部载流子所满足的非线性、耦合、刚性方程组 ) ,对 PIN二极管微波限幅器在高功率微波激励下的响应进行了计算 ,比较了不同条件下的计算结果 ,并对二极管微波响应截止频率作了探讨。计算结果表明 :随着激励源幅值的升高 ,器件截止频率增大 ;随着脉冲长度减小 ,器件截止频率降低 ;随着器件恒定温度值升高 。

微波响应型纳米材料及其抗肿瘤应用的研究进展

微波消融(MWA)是近年来兴起的一种针对实体肿瘤的微创介入治疗技术,具有创伤较小、疗效确切、可重复性等优势.但是,当肿瘤靠近重要脏器或者大血管时,MWA治疗往往不够彻底,由此而导致的残余肿瘤复发是影响MWA远期疗效的桎梏.随着纳米科学在生物医学领域的飞速发展,具有独特理化性质的微波响应型纳米材料为增强MWA疗效、降低瘤周正常组织的热损伤及减少肿瘤复发提供了新的可能性.本文回顾现有微波响应型纳米材料的种类,分析其响应微波并应用于抗肿瘤治疗的作用机制,以期对新型微波响应型纳米材料的构建及其在肿瘤微波治疗领域的进一步临床转化提供系统而全面的参考.

高温超导Josephson结的微波响应分析

在 Aslam azov和 L arkin给出的 RSJ模型下电压时变方程无扰解的基础上 ,运用二阶微扰算法计算了Josephson结在高频辐射下的直流电压响应和阻抗 .结果表明 ,辐射响应正比于辐射功率 ,并且根据 Josephson固有频率 w0 是大于、等于还是小于辐射频率 w,可将响应分为三个特性频率区 .当 w大于或者小于 w0 时 ,响应可以用V- I特性参数表示 .当 w0 w时 ,响应正比于 :(1)直流特性曲线的斜率 ;(2 )辐射频率的负二次方 ;(3)本征Josephson振荡的电压幅值 .当 w0 w时 ,响应正比于 V- I曲线的曲率 .实验表明 ,当 w0 w时 ,响应正比于辐射功率和 V- I特性曲线的曲率 .所得到的等效噪声功率为 N EP=2 .45× 10 - 1 4 W/Hz1 / 2 。

电流磁场作用下YBCO颗粒膜的非平衡微波响应

文中从二维 Josephson弱连接网络模型出发 ,讨论了二维超导体系的磁通“涡流 -反涡流”束缚对的激发问题 ,并进一步讨论了涡旋在电流、磁场作用下的激发问题 ,给出了自由涡旋的密度分布 n(I,H ,T)随温度的分布图 ,对比高温超导体的非平稳微波响应曲线图 ,发现两者具有相似的分布特征。该结果表明 ,高温超导体的非平稳微波响应与磁通“涡旋 -反涡旋”束缚对的激发有关。

磁场下高温超导YBCO颗粒膜的非平衡微波响应

应用二维约瑟夫逊弱连接网络模型 ,讨论了磁场引起的二维超导体系中磁通“涡旋反涡旋”束缚对的激发问题 ,给出了自由涡旋分布 n( T,H )的分析表达式 ,对比 YBCO颗粒膜样品的非平衡微波响应测量数据发现 :两者具有相似的分布特征。该结果表明 ,高温超导颗粒膜的非平衡微波响应机制与磁通“涡旋反涡旋”束缚对的激发态可能存在某种内在联系。

YBCO颗粒膜的非平衡微波响应与Kosterlitz-Thouless相变

报道了ＹＢａ２Ｃｕ３Ｏ７－δ（ＹＢＣＯ）颗粒膜的微波辐射（λ＝８ｍｍ）响应特征．实验结果表明：ＹＢＣＯ颗粒膜的微波响应行为不能用辐射热效应来描述，而应当属于非平衡响应行为．在超导转变温度Ｔｃｏ以下温区，非平衡微波响应信号电平随样品电阻Ｒ趋于零而消失，并且对弱的外磁场十分灵敏．在对样品的直流ＩＶ特性进行了仔细测量后发现，样品的电输运行为具有准二维结构特征，可以用ＫｏｓｔｅｒｌｉｔｚＴｈｏｕｌｅｓ（ＫＴ）相变模型加以描述．在此基础上，分析结果表明：ＹＢＣＯ颗粒膜中的非平衡微波响应机制可能与磁通“涡旋反涡旋”

Response surface optimization of process parameters for removal of F and Cl from zinc oxide fume by microwave roasting

Microwave was applied to roasting the zinc oxide fume obtained from fuming furnace for the removal of F and Cl. The effects of important parameters, such as roasting temperature, holding time and stirring speed, were investigated and the process conditions were optimized using response surface methodology (RSM). The results show that the effects of roasting temperature and holding time on the removal rate of F and Cl are the most significant, and the effect of stirring speed is the second. The defluorination rate reaches 92.6% while the dechlorination rate reaches 90.2%, under the process conditions of roasting temperature of 700 °C, holding time of 80 min and stirring speed of 120 r/min. The results indicate that the removal of F and Cl from fuming furnace production of zinc oxide fumes using microwave roasting process is feasible and reliable.

Optimization of Microwave Extraction of Flavonoids from Water Chestnut Skin Dregs with Response Surface Method

[Objective] In order to take full advantage of processing by-product of water chestnut, the microwave extraction method of flavonoids from water chestnut skin dregs was optimized. The extracted flavonoids had a relatively high yield. [Method] The Box-Behnken design-based response surface method was adopted to optimize the microwave extraction of flavonoids from water chestnut skin dregs, a by-product of water chestnut starch. The mathematical relationships between various influencing factors and flavonoids yield were established. [Result] The optimum extraction conditions of flavonoids from water chestnut skin dregs were as follows： ethanol concentration of 55.4%, solid/liquid ratio of 1：30 g/ml, microwave power of 320 W, microwave time of 3 min and microwave time of 2 times. Under the optimum extraction conditions, the theoretical flavonoids yield was 2.376%. However, the actual flavonoids yield under the optimum extraction conditions was 2.365%. The relative error between actual values and theoretically predicted values was 0.461%. [Conclusion] The results showed the optimized extraction method is reliable, and it can provide a reference for the comprehensive and highly efficient utilization of water chestnut processing wastes.

Optimization of Microwave-assisted Extraction Technology of Polyphenols from Loropetalum chinense(R. Br.) Oliv

In order to optimize the microwave-assisted extraction technology of polyphenols from Loropetalum chinense （R. Br.） Oliv., the effects of microwave power, ethanol concentration, solid to liquid ratio and extraction time on polyphenols extraction rate were investigated. On the basis of single-factor test, a four-factor and three-level orthogonal test was designed by response surface method to establish a mathematical model between the response value and various factors. The results showed that the intensity of effect of different influencing factor on polyphenols ex- traction rate ranked as microwave power＇s〉solid to liquid ratio＇s〉extraction time＇s〉 ethanol concentration＇s. The optimum microwave-assisted extraction conditions for polyphenols from L. chinense were as follows： extraction power 254 W, ethanol concentration 60%, extraction time 12.5 rain and solid to liquid ratio 1：17. Under the optimum extraction conditions, the extraction rate of polyphenols from L. chinense was 19.17%.

Optimization of processing parameters for microwave drying of selenium-rich slag using incremental improved back-propagation neural network and response surface methodology

In the non-linear microwave drying process, the incremental improved back-propagation （BP） neural network and response surface methodology （RSM） were used to build a predictive model of the combined effects of independent variables （the microwave power, the acting time and the rotational frequency） for microwave drying of selenium-rich slag. The optimum operating conditions obtained from the quadratic form of the RSM are： the microwave power of 14.97 kW, the acting time of 89.58 min, the rotational frequency of 10.94 Hz, and the temperature of 136.407 ℃. The relative dehydration rate of 97.1895% is obtained. Under the optimum operating conditions, the incremental improved BP neural network prediction model can predict the drying process results and different effects on the results of the independent variables. The verification experiments demonstrate the prediction accuracy of the network, and the mean squared error is 0.16. The optimized results indicate that RSM can optimize the experimental conditions within much more broad range by considering the combination of factors and the neural network model can predict the results effectively and provide the theoretical guidance for the follow-up production process.

The Microwave Synthesis of 2,6-Pyridine Dicarboxylic Hydrazine

Under microwave irradiation, with dimethypyridine-2,6-dicarboxylate and hydrazine hydrate as raw materials, 2,6-pyridine dicarboxylic hydrazine was produced. At the same time, the influence factors of production rate, such as microwave radiation time, reaction power, the amount of dimethypyridine-2,6-dicarboxylate and hydrazine hydrate was further explored. Through the orthogonal experiments, better technology conditions were found which make the synthetic process turn from the new type of microwave technology.

A microwave photonic filter based on multi-wavelength fiber laser and infinite impulse response

A microwave photonic filter(MPF) based on multi-wavelength fiber laser and infinite impulse response(IIR) is proposed. The filter uses a multi-wavelength fiber laser as the light source, two sections of polarization maintaining fiber(PMF) and three polarization controllers(PCs) as the laser frequency selection device. By adjusting the PC to change the effective length of the PMF, the laser can obtain three wavelength spacings, which are 0.44 nm, 0.78 nm and 1.08 nm, respectively. And the corresponding free spectral ranges(FSRs) are 8.46 GHz, 4.66 GHz and 3.44 GHz, respectively. Thus changing the wavelength spacing of the laser can make the FSR variable. An IIR filter is introduced based on a finite impulse response(FIR) filter. Then the 3-d B bandwidth of the MPF is reduced, and the main side-lobe suppression ratio(MSSR) is increased. By adjusting the gain of the radio frequency(RF) signal amplifier, the frequency response of the filter can be enhanced.