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.     

离子束能量和衬底温度对氧化钆结构的影响

利用双离子束沉积技术，在Si(100)衬底上制备了氧化钆薄膜. 离子束能量在100～500eV范围内，衬底温度较低时薄膜为(402)择优取向的单斜结构，随着衬底温度的增加，择优取向转为(202)方向. 当衬底温度是700℃时，出现了立方结构，这是由于离子束加热的作用，导致低温下出现单斜结构. XPS研究表明薄膜中存在氧缺陷，改进工艺条件可消除部分缺陷.     

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.     

An Analog Front‐End Circuit for ISO/IEC 14443‐Compatible RFID Interrogators

An analog front‐end circuit for ISO/IEC 14443‐compatible radio frequency identification (RFID) interrogators was designed and fabricated by using a 0.25 µm double‐poly CMOS process. The fabricated chip was operated using a 3.3 Volt single‐voltage supply. The results of this work could be provided as reusable IPs in the form of hard or firm IPs for designing single‐chip ISO/IEC 14443‐compatible RFID interrogators.     

天然气提氦技术现状及建议

介绍了天然气提氦资源市场与技术现状,总结了天然气提氦工艺特点,综述公司天然气提氦技术的发展历程,并分析了该技术存在的主要问题,对下一步技术发展提出相关建议。     

潜山地层地应力方向识别方法及其对裂缝有效性的影响

在对潜山地应力方向识别原理进行了介绍的基础上,提出了三种利用成像测井新技术结合常规测井信息,判断现今最大水平主应力方向的方法。根据天然裂缝走向与现今最大水平主应力方向之间的关系,可以评价现今最大水平主应力对天然裂缝的保存和次生改造作用,从而判断裂缝的有效性。