基于自抗扰控制器的柴油机转速控制

当柴油机作为转速控制系统的被控对象时,是一个多变量强耦合非线性系统,采用经典PID控制难以得到满意的控制效果,但是自抗扰控制理论设计的控制器,能够提高调速系统的精度、准确度和柴油机的抗扰动能力。本文主要介绍了自抗扰控制技术(Active Disturbance Rejection Control Technique,ADRC),并且根据自抗扰控制技术设计了切实可行的自抗扰控制器,通过与PID控制的仿真比较,显示出自抗扰控制器对转速控制的较小超调量和较短调节时间,反应出良好的动态性能和稳态特性。     

软件无线电与移动通信

文章介绍了软件无线电的概念、特点及其在移动通信中的应用,并对软件无线电的关键技术及其发展方向作了详细分析。     

光纤光参量放大增益特性的研究

分析了光纤光参量放大过程泵浦光与信号光的非线性相互作用，得到信号光增益G_s。进一步分析G_s，获得其增益带宽特性，只有在泵浦波长大于光纤零色散波长时才有增益，带宽约为50nm。     

皮秒激光-化学复合法制备高效减反射晶硅表面微结构研究

基于皮秒激光的"冷加工"特点,进行了用皮秒激光辐照结合快速化学腐蚀(Na OH溶液:质量分数为4%,不大于3 min,80℃水浴)调控工艺制备高效减反射晶硅表面微结构的研究,在400~1000 nm波长的宽光谱范围内,获得了微-纳双结构微孔阵列和圆顶锥形周期性阵列两种减反射表面,前者的平均反射率低于5%,后者的平均反射率低于10%。制备过程中工艺可控性强,无需掩膜和真空环境。研究了激光工艺参数和化学腐蚀参数的不同调控匹配在微结构单元形成中的作用机制,分析了所制备表面微结构的减反射机理,为太阳能电池和其他半导体器件中硅基减反射表面微结构的低成本激光可控制造提供了重要的指导。     

Effect of current on the microstructure and performance of (Bi_2Te_3)_(0.2)(Sb_2Te_3)_(0.8) thermoelectric material via field activated and pressure assisted sintering

(Bi_2Te_3)_(0.2)(Sb_2Te_3)_(0.8) thermoelectric material was sintered via a field activated and pressure assisted sintering(FAPAS) process.By applying different current intensity(0,60,320 A/cm~2) in the sintering process,the effects of electric current on the microstructure and thermoelectric performance were investigated.This demonstrated that the application of electric current in the sintering process could significantly improve the uniformity and density of(Bi_2Te_3)_(0.2)(Sb_2Te_3)_(0.8) samples.Whe...     

结合图像分割的暗原色先验去雾算法

基于暗原色先验规律的图像去雾算法在进行暗原色通道计算时,用固定区域会造成介质透射率估算的不合理,从而导致最终去雾效果细节不清晰和在较远景深场景模糊的现象。采用基于图论的分割算法来确定取暗原色通道的区域,能根据景深的变化自适应地改变区域大小,避免了固定区域求取暗原色的带来的介质透射率估计不合理问题。通过实验分析和验证,证实了该算法能有效地改善雾天图像的退化现象和提高图像清晰度。     

Improved optical heterodyne methods for measuring frequency responses of photodetectors

An improved optical self-heterodyne method utilizing a distributed Bragg reflector (DBR) tunable laser and an optical fiber ring interferometer is presented in this paper. The interference efficiency can be increased by 7 dB compared with the scheme using the conventional Mach-Zehnder interferometer. The unsteady process that the beating frequency experiences in each tuning period is investigated. According to the measurement results, the wavelength and optical power of the tunable laser will be steady when the square-wave frequency is lower than 300 kHz. It has been shown that when a square-wave voltage is applied to the phase section of the tunable laser, the laser linewidths vary in a wide range, and are much larger than that under dc voltage tuning. The errors caused by the variations in the linewidth of the beat signal and optical power can be eliminated using the proposed calibration procedures, and the measurement accuracy can, therefore, be significantly improved. Experiments show that the frequency responses obtained using our method agree well with the data provided by the manufacturer, and the improved optical self-heterodyne method is as accurate as the intensity noise technique.     

Light‐Induced Surface Modification of Natural Plant Microparticles: Toward Colloidal Science and Cellular Adhesion Applications

Playing an instrumental role in the life of plants, pollen microparticles are one of the most fascinating biological materials in existence, with abundant and renewable supply, ultrahigh durability, and unique, species‐specific architectural features. Aside from their biological role, pollen microparticles also demonstrate broad utility as functional materials for drug delivery and microencapsulation, and increasingly for emulsion‐type applications. As natural pollen microparticles are predominantly hydrophobic, developing robust surface functionalization strategies to increase surface hydrophilicity would increase the range of colloidal science applications, including opening the door to interfacing microparticles with biological cells. This research investigates the extraction and light‐induced surface modification of discrete pollen microparticles from bee‐collected pollen granules toward achieving functional control over the responses elicited from discrete particles in colloidal science and cellular applications. Ultraviolet–ozone treatment is shown to increase the proportion of surface elemental oxygen and ketones, leading to increased surface hydrophilicity, enhanced particle dispersibility, tunable control over Pickering emulsion characteristics, and enhanced cellular adhesion. In summary, the findings demonstrate that light‐induced surface modification improves the functional properties of pollen microparticles, and such insights also have broad implications across materials science and environmental science applications.     

Domain Engineering in ReS2 by Coupling Strain during Electrochemical Exfoliation

Chemical exfoliation has been used for the fast and large‐scale production of 2D nanosheets from graphene and transition metal dichalcogenides; however, it is rarely used for domain engineering of exfoliated nanosheets. Herein, it is found that the use of large sized molecular intercalants during electrochemical intercalation induce atomic row dislocation and parallel mirror twin boundaries (MTBs) on an otherwise pristine rhenium disulfide (ReS₂) crystal, such that the exfoliated flakes possess a parallel, multi‐domain structure. These domains can be distinguished under a polarized microscope owing to the intrinsic in‐plane optical dichroic properties of ReS₂, thereby affording a way to track the number of domains introduced versus the size of the molecular intercalant during electrochemical exfoliation. Ferromagnetism is detected on the intercalated sample using large sized molecular intercalants. Density function theory suggests that these may be due to the coupled effects of lattice strain and S vacancies in the MTBs.     

Multifunctional Electrode Design Consisting of 3D Porous Separator Modulated with Patterned Anode for High‐Performance Dual‐Ion Batteries

Searching for low‐cost and high‐capacity electrode materials such as metal anodes is of important significance for the development of new generation rechargeable batteries. However, metal anodes always suffer from severe volume expansion/contraction during a repeated electrochemical alloying/dealloying process. In this study, a novel concept about modifying metal‐anodes‐based battery construction with a multifunctional electrode (ME) design is provided. The ME consists of a 3D porous separator that is modulated with a patterned aluminum anode, which simultaneously works as a current collector, anode material, and separator in a dual‐ion battery (DIB). The 3D porous separator not only enables the ME to possess significantly improved electrolyte uptake and retention capabilities, but also acts as a protecting layer to restrict the surface pulverization of the Al anode. The ME‐DIB displays remarkably enhanced cell performances, including excellent cycling stability with 92.4% capacity retention after 1000 cycles at a current density of 2 C, and superior rate performance with 80.7% capacity retention at 10 C.