Chemical etching of a GaSb crystal incorporated with Mn grown by the Bridgman method under microgravity conditions

uring crystal growth can be reflected by the observations of etch pit distribution and other structural defects. Suggestions for improving the space experiment to improve the quality of the crystal are given.     

多功能清洗平台

化学清洗是工业清洗中的重要手段，成套清洗装置是必要的装备。本文详细介绍了多功能清洗平台这种清洗装置，它可以方便地完成多种设备的清洗工作。     

Comparison between Single-mode Treatment and Multi-mode Treatment of a Coaxial Bragg Resonator for a Terahertz Cyclotron Autoresonance Maser Oscillator

As a coaxial Bragg structure has more complex geometry configuration than a cylindrical or a planar Bragg structure, for simplicity of calculation a single-mode treatment is often adopted. However, heterogeneity of a coaxial Bragg structure always gives rise to the multi-mode conversion, which can change the performance of the resonator. Based on the scattering matrix method, detailed comparison between the single-mode treatment and the multi-mode treatment is presented to a coaxial Bragg resonator for a cyclotron autoresonance maser (CARM) oscillator operating in the higher-order mode TE₆₁ at frequency of 0.35 THz. Results indicate that there is a little difference between the results obtained by these two treatments to the upstream reflector due to its shallow ripple amplitude, whereas to the downstream reflector, due to its relatively deep ripple amplitude, an apparent difference occurs at the operating frequency and consequently it gives notable difference to the frequency response and Q-factor of the whole resonator. Optimization shows possible application of a coaxial Bragg resonator with a single higher-order mode operation in constructing a terahertz CARM oscillator.     

小区覆盖预测中一种有效的射线跟踪技术

射线跟踪法是近年来常用于城市微小区和室内环境无线电波传播信道特性预测的方法,但其在具体实现方面仍有许多问题需要进一步的研究。本文将计算机图形学中的八叉树方法用于射线跟踪法,得到了一种提高射线跟踪效率的方法。     

低能离子束方法制备Mn-Si薄膜

采用低能离子束技术,获得了Mn组分渐变的Mn-Si薄膜.利用俄歇电子能谱法分析了样品的组分特性,X射线衍射法和原子力显微镜法分析了样品的结构和形貌特性.测试结果表明,300℃下制备的样品Mn离子的注入深度要比室温下制备的样品深.室温下制备的Mn-Si薄膜结构呈非晶态.300℃下制备的Mn-Si薄膜发生晶化现象,没有新相形成,成功制备了Mn-Si固溶体薄膜.     

A new chaotic secure communication system

The paper proposes a digital chaotic secure communication by introducing a magnifying glass concept, which is used to enlarge and observe minor parameter mismatch so as to increase the sensitivity of the system. The encryption method is based on a one-time pad encryption scheme, where the random key sequence is replaced by a chaotic sequence generated via a Chua's circuit. We make use of an impulsive control strategy to synchronize two identical chaotic systems embedded in the encryptor and the decryptor, respectively. The lengths of impulsive intervals are piecewise constant and, as a result, the security of the system is further improved. Moreover, with the given parameters of the chaotic system and the impulsive control law, an estimate of the synchronization time is derived. The proposed cryptosystem is shown to be very sensitive to parameter mismatch and hence the security of the chaotic secure communication system is greatly enhanced.     

Emancipating Target‐Functionalized Carbon Dots from Autophagy Vesicles for a Novel Visualized Tumor Therapy

Killing the tumor cells by a visualized targeting system is a promising strategy with which to achieve high efficiency, low side effects, and a high survival rate for tumor therapy. Here, an autophagy regulation strategy is reported by emancipating target‐functionalized carbon dots from autophagy vesicles for the efficient visualized tumor therapy. The folic acid modified N‐doped carbon dots (FN‐CDs) are selectively endocytosed (specific cellular uptake rate >93.40%) and stably existed in autophagic vacuoles in tumor cells. Next, the autophagic vacuoles are “opened” by the autophagy inhibitors. Released FN‐CDs activate both the intrinsic and extrinsic apoptotic signaling pathway and kill tumor cells efficiently. This method achieves therapeutic effects with high performance in 26 types of tumor cell lines. Animal experiments show that the 30 d survival rate of this therapeutic strategy is much higher than that with traditional drug treatment. Real‐time imaging/monitoring and its effects on the intelligent tumor therapy are also demonstrated based on the stable, strong, green emission from FN‐CDs.     

一种强干扰条件下微弱信号DOA估计的新方法

给出了一种基于均匀线性阵列的既能抑制强烈干扰,又能同时进行微弱信号DOA估计的算法。在已知强干扰源个数和入射方向的前提下,先使用改进的波束形成方法,在子阵上进行波束形成以抗干扰,再对加权后的子阵进行微弱信号的DOA估计。该方法的优点是当干扰和希望信号处在同一个波束内时,不需要提高信号的信噪比就可以正确地估计出信号的入射方向。理论分析和计算机仿真都表明该算法是有效的。     

大剂量Mn离子注入GaAs的性质

在室温条件下在半绝缘性GaAs衬底上进行了大剂量Mn离子的低能注入，并进行了不同条件的退火. 借助于X射线衍射(XRD)和高分辨X射线衍射(HR-XRD)进行了结构分析，经过退火后生成的新相衍射峰增多，根据衬底(004)峰摇摆曲线分析结果退火后更多的Mn离子进入晶格. 运用原子力显微镜分析了样品的表面，发现退火后突起的起伏度增加. 磁性分析表明，退火样品的磁化强度增大.     

A Unified Framework for Transmitter Power Control in Cellular Radio Systems

In earlier works on transmitter power control in cellular radio systems, the problem of whether a signal‐to‐interference ratio (SIR) threshold is achievable is determined by apparently different rules for homogeneous and heterogeneous SIR systems. In this paper, we present a unified and more universal framework for both cases. We also highlight the conditions under which a given SIR threshold vector for the heterogeneous SIR system is achievable, although so far there is no general solution to this problem.