Self-adaptive PID controller of microwave drying rotary device tuning on-line by genetic algorithms

The control design, based on self-adaptive PID with genetic algorithms(GA) tuning on-line was investigated, for the temperature control of industrial microwave drying rotary device with the multi-layer(IMDRDWM) and with multivariable nonlinear interaction of microwave and materials. The conventional PID control strategy incorporated with optimization GA was put forward to maintain the optimum drying temperature in order to keep the moisture content below 1%, whose adaptation ability included the cost function of optimization GA according to the output change. Simulations on five different industrial process models and practical temperature process control system for selenium-enriched slag drying intensively by using IMDRDWM were carried out systematically, indicating the reliability and effectiveness of control design. The parameters of proposed control design are all on-line implemented without iterative predictive calculations, and the closed-loop system stability is guaranteed, which makes the developed scheme simpler in its synthesis and application, providing the practical guidelines for the control implementation and the parameter design.

Optimization of large-area YBa_(2)Cu_(3)O_(7-δ)thin films by pulsed laser deposition for planar microwave devices

This paper presents high quality YBa_(2)Cu_(3)O_(7-δ)(YBCO)thin films on LaAlO_(3)substrate for microwave devices prepared by pulsed laser deposition(PLD).The double-sided YBCO films cover a large area and have been optimized for key parameters relevant to microwave device applications,such as surface morphology and surface resistance(R_(s)).This was achieved by improving the target quality and increasing the oxygen pressure during deposition,respectively.To evaluate the suitability of the YBCO films for microwave devices,a pair of microwave filters based on microstrip fabricated on films from this work and a commercial company were compared.The results show that the YBCO films in this work could completely meet the requirements for microwave devices.

Microwave Induced Ethanol Bath Bonding for PMMA Microfluidic Device

High bonding strength,low deformation and convenient procedure are all very important aspects in the microfluidic device fabrication process. In this paper,an improved microwave induced bonding technology is proposed to fabricate microfluidic device based on methyl methacrylate( PMMA). This method employs pure ethanol as the bonding assisted solvent. The ethanol not only acts as the microwave absorbing material,but also works as the organic solvent in bath. The presented research work has shown that the bonding process can be completed in less than 45 s. Furthermore,the convenient bonding only applies microwave oven,beakers and binder clips. Then,we discuss effects of microwave power,bonding time on bonding strength and deformation of microstructures on PMMA microfluidic device. Finally,a 4 layers micro-mixer has been fabricated using the proposed bonding technique which includes 15 trapezoid micro-channels,9 T-type mix units and an X-type mix unit. Experimental results show that the proposed bonding method have some advantages compared with several traditional bonding technologies,such as hot pressing bonding,ultrasonic bonding and solvent assisted bonding methods in respect of bonding strength,deformation and bonding process. The presented work would be helpful for low coat mass production of multilayer polymer microfluidic devices in lab.

Creating Distinctive Connections between Multifunctional Microwave Circuits and Mobile-Terminal Radio-Frequency Integrated Chips Using Integrated Passive Device Technology

In this review,the advanced microwave devices based on the integrated passive device(IPD)technology are expounded and discussed in detail,involving the performance breakthroughs and circuit innovations.Then,the development trend of IPD-based multifunctional microwave circuits is predicted further by analyzing the current research hot spots.This paper discusses a distinctive research area for microwave circuits and mobile-terminal radio-frequency integrated chips.

The properties of Sn-Zn-Al-La fusible alloy for mitigation devices of solid propellant rocket motors

The Al and La elements are added to the Sn9Zn alloy to obtain the fusible alloy for the mitigation devices of solid propellant rocket motors. Differential scanning calorimetry(DSC), metallographic analysis,scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), tensile testing and fracture analysis were used to study the effect of Al and La elements on the microstructure, melting characteristics, and mechanical properties of the Sn9Zn alloy. Whether the fusible diaphragm can effectively relieve pressure was investigated by the hydrostatic pressure at high-temperature test. Experimental results show that the melting point of the Sn9Zn-0.8Al0·2La and Sn9Zn-3Al0·2La fusible alloys can meet the predetermined working temperature of ventilation. The mechanical properties of those are more than 35% higher than that of the Sn9Zn alloy at-50°C-70°C, and the mechanical strength is reduced by 80% at 175°C. It is proven by the hydrostatic pressure at high-temperature test that the fusible diaphragm can relieve pressure effectively and can be used for the design of the mitigation devices of solid propellant rocket motors.

Study of High-Temperature Superconductor Diplexers for Satellite Communications

The high-temperature superconductor （HTSC） resonator and diplexer are simulated by full-wave tools. A newly developed miniature HTSC diplexer is designed and fabricated on double sided YBa2Cu3O7 （YBCO） film （YBCO/LaAlO3/YBCO）, the thickness of which is 400 nm for YBCO and 0.5 mm for the LaAlO3. The measured results show a good agreement with the simulation. The volume and mass of the diplexers are greatly reduced by miniaturized configuration.

PHASE AND FREQUENCY LOCKING OF MICROWAVE AND MILLIMETER WAVE POWER COMBINING

The phase and frequency locking of microwave, millimeter wave power combining were analysed and summarized in an all-round way. The master/slave phase locking of cavity oscillators, the peer phase locking of mutually coupled oscillators, and the peer phase locking of ring-connected multiple oscillators were investigated. The results of numerical calculations, and the relations of phase to phase locking model and oscillator parameters were given. And the cavity and space power combining aspects for microwave and millimeter wave were presented.

Magnetoelectric Multiferroic Composites： Phenomena and Devices

Detailed mathematical modelling approaches that are used to describe the dynamic behaviour of magnetoelectric coupling in magnetostrictive-piezoelectric multiferroics at low-frequencies, in electromechanical resonance region and at microwave range are discussed. The ME （magnetoelectric） voltage coefficients were estimated from the known material parameters. The feasibility for creating new class of functional devices based on magnetoelectric interactions is addressed.

On the Path to High-Temperature Josephson Multi-Junction Devices

We report our progress in the high-temperature superconductor(HTS)Josephson junction fabrication process founded on utilizing a focused helium ion beam damaging technique and discuss the expected device performance attainable with the HTS multi-junction device technology.Both the achievable high value of characteristic voltage V_(C)=I_(C)R_(N)of Josephson junctions and the ability to design a large number of arbitrary located Josephson junctions allow narrowing the existing gap in design abilities for lowtemperature superconductor(LTS)and HTS circuits even with using a single YBa_(2)Cu_(3)O_(7-x) film layer.A one-layer topology of active electrically small antenna is suggested and its voltage response characteristics are considered.

High-temperature dielectric and microwave absorption performances of TiB2/Al2O3 ceramics prepared by spark plasma sintering

TiB_(2)/Al2O3 ceramics reinforced with Mg O are prepared by spark plasma sintering(SPS).The dielectric and microwave(MW)absorption properties are discussed.The results indicate that both the commercial TiB_(2)(C-TiB_(2))content and preparing temperature play important roles in the dielectric properties.Simultaneously,TiB_(2)/Al2O3 composite shows the best MW absorption property when the C-TiB_(2)content and preparing temperature are 9 wt%and 1400°C.To further improve the MW absorption properties,the composite containing 9 wt%synthesized TiB_(2)(S-TiB_(2))has been sintered at 1400°C.Its high-temperature complex permittivity is greater than that of TiB_(2)/Al2O3 composite with 9 wt%C-TiB_(2)sintered at 1400°C and is directly proportional to the temperature.Besides,TiB_(2)/Al2O3 composite with 9 wt%S-TiB_(2)possesses a better MW absorption at 25–500°C,its effective absorption bandwidth(RL<-5 dB)can reach 4.2 GHz at 25–500°C.And the minimum reflection loss(RLmin)value reaches-43.41 dB at the temperature of 800°C with a thickness of 1.45 mm for TiB_(2)/Al2O3 composite with 9 wt%C-TiB_(2).Consequently,the satisfying absorbing layer(d<1.75 mm),flexural strength,heat stability and considerable high-temperature MW absorption ability grant TiB_(2)/Al2O3 ceramics practical applications as high-temperature microwave absorption materials(MAMs).

Diamond Microwave Devices完成一笔130万英镑的商业投资

由EleMEnt Six TechnologiES（E6）金刚石电子团队分拆成立的公司Diamond Microwave Devices（DMD）已经从一个财团手中获得了一笔130万英镑的资本投资。该财团包括OXFord Technology Management、YFM（Partnership Investment Fund）、The ERA Foundation和两位私人投资者。

基于C#的微波器件自动校准系统的设计与实现

针对校准时,微波器件存在人工操作量大、存在读数误差等问题,本文采用C#面向对象语言,设计了一款模块化自动校准软件。该软件采用SCPI命令控制仪器;基于ACCESS数据库,实现基本信息和数据的处理存储;将图形数据转化成二进制流实现测量图形导出。同时,运用Word文档自动生成原始记录和校准证书。试验表明:该软件运行稳定、数据处理准确,满足使用要求,可实现微波器件的自动校准,提高工作效率。

超表面电磁波调控实验教学器件设计

为了解决现有电磁波实验教学设备与理论课程契合度较低、可进行的实验项目内容较浅显等问题,针对电磁场与电磁波课程的均匀平面电磁波极化、平面电磁波反射与折射等教学内容,设计了基于科教融合的超表面电磁波调控实验教学器件。结合现有的微波分光仪进行了测试,实现了对反射波与透射波的极化与波束特性的有效调控,交叉极化转换率不小于95%,波束指向与预定调控目标不大于1°。实验结果验证了该器件用于课程实验教学的可行性,为电磁波实验教学提供了一种思路。

探针结构对Ti/CuO微波点火延迟时间的影响

为了研究探针结构对微波点火性能的影响,使用4种探针对Ti/CuO点火药的微波点火延迟时间进行了测试,并通过模拟对探针结构进行优化,获得了探针参数(长度、包覆层厚度、尖端锥度和镀层厚度)对电场强度的影响规律。结果表明,探针针尖处的电场强度显著影响点火延迟时间,在2.45 GHz、50 W微波作用下,探针1、2、3、4最大电场分别为1800、190、34和53 kV/m,Ti/CuO的点火延迟时间分别为222.6、660.5、949.1和921.3 ms;在2.45 GHz、1 W微波作用下,当探针长度为26 mm、PTFE包覆层长度为8 mm、厚度为0.75 mm、针尖锥度为0.243和金镀层厚度为5μm时,能够将电场强度从原来的约10 kV/m提升到约1000 kV/m,并且电场分布集中于尖端。

高功率腔体滤波器的电磁-热-力多物理场智能代理模型及快速预测

电磁多物理场计算在模拟高功率微波器件方面至关重要。为了快速且精确地获取高功率腔体滤波器中由电磁引发的多物理场响应,本文构建了一种基于数据驱动的电磁多物理场代理模型。首先利用有限元方法建立腔体滤波器的多物理场响应数据库,随后基于该数据库构建数据驱动的人工神经网络代理模型。结果对比表明:该代理模型能够精确且快速地预测高功率腔体滤波器在不同输入功率下的S参数曲线,预测精度超过98%,预测时间少于0.2 s;相较于传统的电磁多物理场数值计算方法,计算速度提升了3个数量级以上。因此,本文代理模型的快速精确预测能力对新型高功率微波器件的稳定性分析、可靠性评估和优化设计具有重要的理论指导意义和实际工程应用价值。

慢波结构等效介电常数提取方法研究

针对天线和微波器件设计中小型化问题,论文研究了电容增强型慢波结构降低电磁波相速,达到小型化技术。通过加载周期性金属盲孔构成的慢波结构,可以大幅度提高微带贴片天线和微波腔体的等效介电常数。研究表明,对于相同结构和尺寸的慢波结构,上述两种方法所获得的等效介电常数提升是一致的。论文针对应用需求,设计了一种电容增强型慢波结构,其慢波效果十分明显,对应的等效介电常数可提高约50%,理论上对应的天线及微波器件电路尺寸可缩减30%以上。论文的仿真与实验测试结果支持了以上结论,且仿真结果和实测结果吻合度较高。

基于神经网络的超材料窗片反向设计研究

与固态器件相比,真空电子器件在高频段可以提供更大的功率、更宽的带宽。输能窗作为其中的重要部件,用以隔绝真空电子器件内外环境,保持管内的高真空度,传输高能电磁波。目前,传统输能窗的性能已经制约宽带高频真空器件性能。基于此,本文提出了一种利用神经网络算法设计超材料窗片的方案,实现了低反射和驻波比的宽带输能窗。本文利用神经网络的非线性拟合效应对窗片结构与其频谱之间建立映射关系,从而避免了求解麦克斯韦方程组的繁复过程,提高了频谱性能仿真的速度,简化了设计过程。通过设计双向神经网络并进行训练,实现反向设计窗片的目标,输入目标频谱特性参数即可生成满足指标要求的结构参数。

Recent progress of parameter-adjustable high-power photonic microwave generation based on wide-bandgap photoconductive semiconductors

Radio frequency/microwave-directed energy sources using wide bandgap SiC photoconductive semiconductors have attracted much attention due to their unique advantages of high-power output and multi-parameter adjustable ability.Over the past several years,benefitting from the sustainable innovations in laser technology and the significant progress in materials technology,megawatt-class output power electrical pulses with a flexible frequency in the P and L microwave wavebands have been achieved by photoconductive semiconductor devices.Here,we mainly summarize and review the recent progress of the high-power photonic microwave generation based on the SiC photoconductive semiconductor devices in the linear modulation mode,including the mechanism,system architecture,critical technology,and experimental demonstration of the proposed high-power photonic microwave sources.The outlooks and challenges for the future of multi-channel power synthesis development of higher power photonic microwave using wide bandgap photoconductors are also discussed.

An all-in-one FeO_(x)-rGO sponge fabricated by solid-phase microwave thermal shock for water evaporation and purification

Developing high-efficiency photothermal seawater desalination devices is of significant importance in addressing the shortage of freshwater.Despite much effort made into photothermal materials,there is an urgent need to design a rapidly synthesized photothermal evaporator for the comprehensive purification of complex seawater.Therefore,we report on all-in-one FeOx-rGO photothermal sponges synthesized via solid-phase microwave thermal shock.The narrow band gap of the semiconductor material Fe_(3)O_(4) greatly reduces the recombination of electron-hole pairs,enhancing non-radiative relaxation light absorption.The abundantπorbitals in rGO promote electron excitation and thermal vibration between the lattices.Control of the surface hydrophilicity and hydrophobicity promotes salt resistance while simultaneously achieving the purification of various complex polluted waters.The optimized GFM-3 sponge exhibitedan enhanced photothermal conversion rate of 97.3% and a water evaporation rate of 2.04 kg/(m^(2)·hr),showing promising synergistic water purification properties.These findings provide a highly efficient photothermal sponge for practical applicationsof seawater desalination and purification,as well as develop a super-rapid processing methodology for evaporation devices.