频谱拍卖中投标者共谋策略与多频段拍卖中共谋问题的讨论

本文通过对单频段拍卖中共谋问题的研究,从抑制共谋的角度,提出了最优的拍卖机制是第一价格封闭式拍卖,论证了频谱拍卖中投标者的最优共谋策略,给出了拍卖方基于保留价格的应对投标者共谋的对策。在单频段拍卖研究的基础上,进一步将频谱拍卖中的共谋问题引申到多频段拍卖中,讨论了当待售频段之间具有互补性和替代性时的共谋情况。     

数字电路故障的基本检测技术

本文介绍了数字电子电路的特点,数字电路故障的具体特征,检测和排除故障的基本方法,以及在检测过程中应注意的问题.     

ISAR Imaging of Maneuvering Targets Based on the Range Centroid Doppler Technique

A new inverse synthetic aperture radar (ISAR) imaging approach is presented for application in situations where the maneuverability of noncooperative target is not too severe and the Doppler variation of subechoes from scatterers can be approximated as a first-order polynomial. The proposed algorithm is referred to as the range centroid Doppler (RCD) ISAR imaging technique and is based on the stretch Keystone-Wigner transform (SKWT). The SKWT introduces a stretch weight factor containing a range of chirp rate into the autocorrelation function of each cross-range profile and uses a 1-D interpolation of the phase history which we call stretch keystone formatting. The processing simultaneously eliminates the effects of linear frequency migration for all signal components regardless of their unknown chirp rate in time-frequency plane, but not for the noise or for the cross terms. By utilizing this novel technique, clear ISAR imaging can be achieved for maneuvering targets without an exhaustive search procedure for the motion parameters. Performance comparison is carried out to evaluate the improvement of the RCD technique versus other methods such as the conventional range Doppler (RD) technique, the range instantaneous Doppler (RID) technique, and adaptive joint time-frequency (AJTF) technique. Examples provided demonstrate the effectiveness of the RCD technique with both simulated and experimental ISAR data.     

物联网的由来与发展趋势

近来,物联网成为炙手可热的名词,许多人预言物联网将彻底改变人们的生活方式,带动万亿级的产业发展,成为信息化发展的新的推动力量。但是究竟什么是物联网,它离我们还有多远,仍是众说纷纭,见仁见智。本文试图通过分析物联网和互联网的关系,从人类现代信息化发展的历史角度,用结构化模型的方式,对物联网的概念给予辨析,并提出物联网的未来演进路径。     

遥感相机的智能调焦方法

为了将基于图像处理的智能调焦方法引入到空间遥感相机中,从而提高其在轨调焦能力,提出了采用辅助CCD的遥感相机智能调焦方法。该方法解决了推扫式遥感相机由于图像动态变化导致的比较基准不确定问题,为智能调焦方法在遥感相机中的应用开创了途径。在阐述基本调焦原理的基础上,给出了实际应用中多片CCD级联时评价区域选择依据和算法,并以Variance函数为评价函数对调焦过程进行了仿真模拟,实验结果表明:该方法能够可靠、自动地搜索到最佳聚焦位置,获取清晰图像,适用于遥感相机使用。     

CDMA与线性模拟调制通信质量的比较与分析

CDMA在无线移动通信中受到了“垂青”,得到了通信专家与用户的首肯。为此,笔者将古典的线性模拟调制通信方式与现代的CDMA的性能予以量化比较,得出CDMA的优值可达10以上,优于线性模拟调制。因此选择CDMA作为首选通信方式是有理论依据的。     

Study of proton irradiation effects on AlGaN/GaN high electron mobility transistors

AlGaN/GaN high electron mobility transistors (HEMTs) were exposed to 3 MeV protons at fluences of 6 × 10¹³, 4 × 10¹⁴ and 1 × 10¹⁵ protons/cm². The drain saturation currents decreased by 20% and the maximum transconductance decreased by 5% at the highest fluence. As the fluence increased, the threshold voltage shifted more positive values. After proton irradiation, the gate leakage current increased. The Schottky barrier height changed from 0.63 eV to 0.46 eV, and the ideality factor from 2.55 to 3.98 at the highest fluence. The degradations of electrical characteristics of AlGaN/GaN HEMTs are caused by displacement damages induced by proton irradiation. The density of vacancies at different proton fluence can be calculated from SRIM. Being an acceptor-like defect, the Ga vacancy acts as a compensation center. While N vacancy acts as a donor. Adding the vacancies model into Slivaco device simulator, simulation results match well with the trends of experimental data. Hall measurement results also indicate the concentration and mobility of 2DEG decrease after proton irradiation. It is concluded that the Ga vacancies introduced maybe the primary reason for the degradation of AlGaN/GaN HEMTs performance.     

一种改进的进程调度算法在机顶盒上的设计与实现

调度算法对操作系统中的实时性起着关键的作用.就此问题,深入分析了基于最小优裕度算法的内核进程调度算法,为更好地满足Linux系统对嵌入式系统实时可靠性的要求,对现有的LSF调度策略进行分析,指出LSF算法调度算法的不足.为了改进LSF算法的颠簸现象,基于抢占阈值的思想,提出适用于LSF算法的抢占阈值分配方法,动态地给每...     

Amplifying Nanoparticle Targeting Performance to Tumor via Diels–Alder Cycloaddition

Traditional targeting approach utilizing biological ligands has to face the problems of limited receptors and tumor heterogeneity. Herein, a two‐step tumor‐targeting and therapy strategy based on inverse electron‐demand [4+2] Diels–Alder cycloaddition (iEDDA) is described. Owing to the unique acidic tumor microenvironment, an intravenous injection of tetrazine modified pH (low) insertion peptide could efficiently target and incorporate onto various cell surfaces in tumor tissue, such as cancer cells, vascular endothelial cells, and tumor‐associated fibroblasts. The “receptor‐like” tetrazine groups with a large amount and homogeneous intratumoral distribution could then serve as the baits to greatly amplify the tumor‐targeting ability of indocyanine green (ICG)‐loaded and trans‐cyclooctene (TCO)‐conjugated human serum albumin (HSA) nanoparticles (TCO‐HSA‐ICG NPs) via iEDDA after the second intravenous injection. Compared with the passive enhanced permeability and retention (EPR) effect and traditional active targeting approaches, the targeting performance and photothermal therapeutic effect based on the two‐step strategy are significantly enhanced, while no notable toxicity is observed. As acidity is a characteristic of solid tumor, the two‐step strategy can serve as a universal and promising modality for safe and high‐performance nanoparticle‐based antitumor therapy.     

基于DSP和局域网的医疗护理监控系统的设计

随着社会的不断进步,人们对护理工作的要求也越来越高,护理工作好坏直接关系着医院的发展。因此,本文研究设计了一种基于DSP和局域网的医疗护理监控系统,并对此设计作了简要分析,促进了医院医疗护理工作的发展。