ZigBee 无线传感器网络节点能耗模型研究

针对当前无线传感器网络能耗模型计算复杂、通用性差及理论模型与实际相差较大等问题,提出一种 ZigBee 无线传感器网络节点的能耗模型。采用无线传感器网络节点工作电压、发送状态、接收状态中各阶段的时长和工作电流以及休眠状态的工作电压和工作电流等参数,建立无线传感器网络节点处于发送状态、接收状态和休眠状态的能耗数学模型,进而建立无线传感器网络节点的总能耗数学模型。实验结果表明,该模型能够准确预测无线传感器网络节点传输能耗代价和剩余工作寿命。     

船载特装设备电能质量监测系统设计与实现

针对测量船特装设备供电系统可能受到短路、断路、漏电、谐波等因素的干扰而影响供电的电能质量问题,构建和实现了一种基于智能网络仪表的电能质量监测系统;该系统实现了对电能质量的在线监测以及采集数据的分析和处理,可准确、实时、连续地对供电系统的电能质量数据进行监测,以获取多方面的电能质量数据;同时实现了电能数据的信息共享,提高了电能数据资源的利用率,为电能质量监测数据进一步分析提供了有力支撑;电能质量监测系统投入运行后,实践结果表明,该系统具有较好的监测效果。     

新技术新业务信息安全评估的创新实践探析

通过对国内外信息安全严重事态的调研,说明国家要求新技术新业务进行信息安全评估是大势所趋。结合国内外技术平台和业务运营中遇到的若干问题和教训,阐述了云南电信完善和创新的信息安全评估手段及方式,逐步形成一套有别于其他运营商的评估流程,并成功应用推广。此举将有效规避可能的安全风险,为健全我国信息安全技术和管理体制做出应有的贡献。     

基于NG-PON2的LTE信号和有线宽带 信号混传接入技术研究

对于运营商来说,为了应对皮飞站的大规模部署和用户日益增长的有线接入速率需求,充分利用好PON和4G 的各自优势,建立PON+LTE的融合宽带网络,实现优势互补,可为用户提供体验一致的高速宽带接入服务。文章详细分析了在NG-PON2中将LTE小基站信号和高速有线宽带信号混传的技术。仿真结果显示,在NG-PON2的备选技术-正交频分复用无源光接入网(OFDM-PON)中混传无线LTE信号和高速有线宽带信号可以省去无线信号的上下变频处理,技术实现简单,可以提升接入信号的多样性和速率。     

Record‐Low‐Threshold Lasers Based on Atomically Smooth Triangular Nanoplatelet Perovskite

Single‐crystalline perovskites are ideal candidates for lasing and other optoelectronic applications. Although significant efforts have been made to grow both bulk single‐crystalline perovskites in liquid solution, their dimensions are still too large to make nanoscale whispering‐gallery‐mode (WGM) resonator based lasers that possess high quality (Q) factor and small volume. Besides, most reported perovskite resonators do not possess atomically smooth surfaces and facets, which limits the Q and thereby increases the lasing threshold. Here, atomically smooth triangular PbI₂ templates are fabricated on a mica substrate by the vapor phase deposition method and are converted to atomically smooth perovskites which have regular and unwrinkled facets with average surface roughness less than 2 nm. By using a CH₃NH₃PbI₃ nanoplatelet with a side length of 27 µm and thickness of 80 nm, room temperature WGM lasing with a Q up to 2600 is demonstrated, the highest reported for hybrid organic–inorganic perovskite nanoplatelets. In addition, the volume of the WGM mode is reduced significantly in comparison with the prior reports. The realized high‐quality triangular CH₃NH₃PbI₃ perovskite nanoplatelets with high Q factor and small volume are expected to perform as ideal cavities for long pulse durations lasers and would find potential applications in integrated optoelectronic devices.     

Analog Circuit Applications Based on All‐2D Ambipolar ReSe2 Field‐Effect Transistors

Complementary circuits based on 2D materials show great promise for next‐generation electronics. An ambipolar all‐2D ReSe₂ field‐effect transistor (FET) with a hexagonal boron nitride gate dielectric is fabricated and its electronic characteristics are comprehensively studied by temperature dependence and noise measurements. Ambipolar transfer characteristics are achieved owing to the tunable Fermi level of the graphene contact and negligible and 30 meV Schottky barrier heights for the n‐ and p‐channel regimes, respectively. An inverter is also fabricated to demonstrate ambipolar ReSe₂ FET operation in a logic circuit. Furthermore, a p/n switchable unipolar FET is designed and shows potential for building complimentary circuits from a signal device. This work demonstrates the potential of all‐2D ReSe₂ FETs and makes available new approaches for designing next‐generation devices.     

Er3+离子对Er3+/Tm3+共掺碲酸盐玻璃1.85μm波段光谱特性的影响

采用高温熔融淬火技术制备了1.0 mol% Tm3＋离子和x mol% Er3＋离子(x=0,0.5和1.5 mol%)掺杂 的系列碲酸盐玻璃,通过测量玻璃样品的差热扫描曲线(DSC)、X射线衍射(XRD)图和荧光光 谱,对不同 Er3＋浓度下的玻璃物理性能和Tm3＋离子荧光特性进行了研究。DSC结果显 示,研制的稀土掺杂碲酸盐玻璃 具有优异的热稳定性能,玻璃样品的析晶温度与转变温度之差大于130 ℃,而XRD图则证实了研制的玻璃 样品具有非晶结构特征。在808 nm泵浦激励下,随着Er3＋离 子的引入,Tm3＋离子³F₄→³H₆能级间跃迁产生 的1.85 μm波段荧光显著增强。当Er3＋离子掺杂浓度为1.0 mol%时,荧光强度提高了约76%,荧光强度的 显著增强归因于Er3＋离子和Tm3＋离子之间的能量传递。然而,随着Er 3＋离子掺杂浓度的继续增加,1.85 μm 波段荧光呈现出衰减现象,这归结于Er3＋离子浓度的淬灭效应。研究表明,具有合 适浓度Er3＋/Tm3＋共掺碲 酸盐玻璃是一种应用于1.85 μm波段固体激光器和光纤放大器的理想 基质材料。     

Joint semantic similarity assessment with raw corpus and structured ontology for semantic-oriented service discovery

Semantic-oriented service matching is one of the challenges in automatic Web service discovery. Service users may search for Web services using keywords and receive the matching services in terms of their functional profiles. A number of approaches to computing the semantic similarity between words have been developed to enhance the precision of matchmaking, which can be classified into ontology-based and corpus-based approaches. The ontology-based approaches commonly use the differentiated concept information provided by a large ontology for measuring lexical similarity with word sense disambiguation. Nevertheless, most of the ontologies are domain-special and limited to lexical coverage, which have a limited applicability. On the other hand, corpus-based approaches rely on the distributional statistics of context to represent per word as a vector and measure the distance of word vectors. However, the polysemous problem may lead to a low computational accuracy. In this paper, in order to augment the semantic information content in word vectors, we propose a multiple semantic fusion (MSF) model to generate sense-specific vector per word. In this model, various semantic properties of the general-purpose ontology WordNet are integrated to fine-tune the distributed word representations learned from corpus, in terms of vector combination strategies. The retrofitted word vectors are modeled as semantic vectors for estimating semantic similarity. The MSF model-based similarity measure is validated against other similarity measures on multiple benchmark datasets. Experimental results of word similarity evaluation indicate that our computational method can obtain higher correlation coefficient with human judgment in most cases. Moreover, the proposed similarity measure is demonstrated to improve the performance of Web service matchmaking based on a single semantic resource. Accordingly, our findings provide a new method and perspective to understand and represent lexical semantics.     

Adaptively secure ciphertext-policy attribute-based encryption with dynamic policy updating一种支持动态策略更新的自适应安全密文策略属性加密方案

Attribute-Based Encryption (ABE) is a promising new cryptographic technique which guarantees fine-grained access control of outsourced encrypted data in the cloud. With the help of ABE, the majority of security issues in accessing cloud data can be solved. However, a key limitation remains, namely policy updating. Whenever the access policy is updated, a common approach is to have the data owner retrieve the data and reencrypt it with new policy, before sending the new ciphertext back to the cloud. This straight-forward approach will lead to heavy computation and communication overhead. Although a number of other approaches have been proposed in this regard, they suffer from two limitations; namely, supporting only limited update-policy types or having weak security models. In order to address these limitations, we propose a novel solution to the attribute-based encryption access control system by introducing a dynamic policy-updating technique which we call DPU-CP-ABE. The scheme is proved to be adaptively secure under the standard model and can support any type of policy updating. In addition, our scheme can significantly reduce the computation and communication costs of updating ciphertext.     

黄河源草甸型弯曲河流的悬臂式崩岸机制

弯曲河流的滨河草甸对抑制河岸崩塌和维持河湾蜿蜒具有重要作用。2011—2014年,在黄河源区兰木错曲的弯曲河段对河岸植被根系、崩塌块几何尺寸、根土复合体物理和力学特性等开展野外调查,并通过原位拉拔试验测定河岸崩塌面植被根系抗拉强度,进而分析草甸型弯曲河道的崩岸机制。草甸型弯曲河流的滨河植被根系网络具有较强缠绕和固结土体作用,河岸根系的力学特性是抑制凹岸崩岸的关键因子。近岸水流淘刷作用集中于根系作用范围以下的砂卵石层,当砂卵石层被淘刷至上部悬空,在自重作用下达到临界状况,河岸沿纵深方向出现贯穿性裂缝,最后崩塌块垮塌贴住河岸。崩块的破坏形式以悬臂式张拉破坏为主。崩塌块的植被根系长度与崩塌块厚度呈明显对数函数关系,其体积也随根系长度增大而增加。分析草甸型弯曲河流的新崩岸模式,建立了近岸根土复合体崩岸的临界力矩平衡方程,并简化得到崩塌块的临界宽度表达式。崩塌块体的临界宽度是崩塌块根系长度和根系产生的抗拉强度增量的函数,临界宽度的计算值与实测值较为符合。