PC机与单片机多机主从互通的实现

为了实现PC机与多个单片机的互相通信,特别是多个单片机都需要向PC机传输数据时,课题组采用“点名式”的总线控制方式。单片机在得到PC机发送的“点名”指令后,开始控制总线,向PC机传输数据。传输数据结束后,通知PC机并退出总线控制,PC机再逐个往后发送“点名”指令。根据这种思路,搭建了相应的电路,经过不断的实验、调试和改进,构建的系统工作稳定、可靠。“点名式”的多机互通方式非常适合于需要多单片机向PC机传送数据的场合,具有较高的实用价值。     

On Multiple Scattering of Radiation by an Infinite Grating of Dielectric Circular Cylinders at Oblique Incidence

A rigorous analytical representation for the multiple scattering coefficients of the fields radiated by an infinite grating of dielectric circular cylinders excited by an obliquely incident plane electromagnetic wave is derived in terms of the “well-known scattering coefficients of an isolated dielectric cylinder at oblique incidence” and “Schlömilch series”. In addition, a generalized sum-integral grating equation is acquired for the multiple scattered amplitude of a cylinder at oblique incidence in the grating in terms of the scattering coefficients of the insulating dielectric circular cylinder at oblique incidence.     

A Secure and Verifiable Continuous Data Collection Algorithm in Wireless Sensor Networks

Data collection is a key operation in wireless sensor networks. In view of the privacy-preserving problem of the existing data collection schemes, this paper proposes a secure and verifiable continuous data collection algorithm (SVCDC) in wireless sensor networks. Taking the temporal correlation of sensory data into consideration, SVCDC reconstructs multiple sensory data in one period, which can effectively decrease data traffic, and then by encrypting the reconstructed data, SVCDC ensures the privacy of the sensory data. In addition, in SVCDC, the “fingerprint” of sensory data is generated, aggregated and transmitted to Sink. Then, Sink extracts the “fingerprint”, which ensures the verification of the integrity and timeliness of each node’s sensory data and the detections of attack such as replaying or discarding data. Since the “fingerprint” is aggregated and much shorter than the original data, the communication cost of “fingerprint” is low. Theoretical analysis and experimental results show that SVCDC has advantages in traffic.

     

Optimal transmit antenna selection using hybrid algorithm for massive MIMO technology

Massive multiple input multiple output (M-MIMO) methods make reference to a useful method for using multipath propagation to communicate and receive multiple data signals at once over a single radio channel. To simultaneously transfer numerous data streams, it makes use of various antennas. The quantity of power used grows as the quantity of antennas rises. As a result, choosing the best transmit antennas, which is a major difficulty in M-MIMO systems, becomes important. In this research, “Hybrid Sea Lion-Whale Algorithm (HS-WA)” is introduced by choosing a best transmit antenna while taking into account several objectives. This method optimizes overall capacity and efficiency. The chosen method combines the “Whale Optimization Algorithm (WOA) and Sea Lion Optimization Algorithm (SLnO)” that determines which antenna should be chosen while also optimizing the antenna quantity. Finally, energy efficiency (EE) and capacity analysis results demonstrate that the provided approach is superior to all other models.     

基于多特征融合的层次支持向量机遥感图像云检测

云检测是遥感图像处理和应用的前提,针对遥感图像云检测的准确率容易受到薄云及似云地物影响的挑战,提出一种结合遥感影像灰度、纹理和频率特征的层次支持向量机云检测算法.该方法首先采用简单线性迭代聚类算法将遥感图像分割为像素块,再采用一种层次支持向量机分类器对遥感图像以像素块为单位进行云检测.层次支持向量机的第一层将像素块初步...     

Designing Multi‐Level Resistance States in Graphene Ferroelectric Transistors

Conventional memory elements code information in the Boolean “0” and “1” form. Devices that exceed bistability in their resistance are useful as memory for future data storage due to their enhanced memory capacity, and are also a necessity for contemporary applications such as neuromorphic computing. Here, with the aid of an experimentally validated device model, design rules are outlined and more than two stable resistance states in a graphene ferroelectric field‐effect transistor are experimentally demonstrated. The design methodology can be extrapolated for on‐demand introduction of multiple resistance states in ferroelectric transistors for applications both in data storage and neuromorphic computing.     

一种基于ERNIE的军事文本实体关系抽取模型

针对军事文本实体关系抽取过程中存在的"一句对应多个三元组","一个主语对应多个客体"等问题提出一种基于ERNIE的军事文本三元组抽取模型,在编码层引入ERNIE模型获取每个词的编码序列,参考seq-to-seq解码器的建模方法和BIO序列标注,采用先预测主体,再传入主体标注序列预测客体和二者之间关系的方法实现三元组的抽...     

Controllable Stiffness Origami “Skeletons” for Lightweight and Multifunctional Artificial Muscles

Flexible, material‐based, artificial muscles enable compliant and safe technologies for human–machine interaction devices and adaptive soft robots, yet there remain long‐term challenges in the development of artificial muscles capable of mimicking flexible, controllable, and multifunctional human activity. Inspired by human limb's activity strategy, combining muscles' adjustable stiffness and joints' origami folding, controllable stiffness origami “skeletons,” which are created by laminar jamming and origami folding of multiple layers of flexible sandpaper, are embedded into a common monofunctional vacuumed‐powered cube‐shaped (CUBE) artificial muscle, thereby enabling the monofunctional CUBE artificial muscle to achieve lightweight and multifunctionality as well as controllable force/motion output without sacrificing its volume and shape. Successful demonstrations of arms self‐assembly and cooperatively gripping different objects and a “caterpillar” robot climbing different pipes illustrate high operational redundancy and high‐force output through “building blocks” assembly of multifunctional CUBE artificial muscles. Controllable stiffness origami “skeletons” offer a facile and low‐cost strategy to fabricate lightweight and multifunctional artificial muscles for numerous potential applications such as wearable assistant devices, miniature surgical instruments, and soft robots.     

Efficient geocasting with multi-target regions in mobile multi-hop wireless networks

Geocasting, a variation on the notion of multicasting, is a mechanism to deliver messages of interest to all nodes within a certain geographical target region. Although several geocasting protocols have already been proposed for multi-hop wireless networks, most of these algorithms consider a “single” target region only. Here, when more than one target regions need to receive the same geocast messages, multiple transmissions need to be initiated separately by the message source. This causes significant performance degradation due to redundant packet transmissions, and it becomes more severe as the number of target regions increase. To solve this problem, we propose a basic scheme and its variations which utilize the geometric concept of “Fermat point” to determine the optimal junction point among multiple geocast regions from the source node. Our simulation study using ns-2 shows that the proposed schemes can effectively reduce the overhead of message delivery while maintaining a high delivery ratio in mobile multi-hop wireless networks.     

Blind velocities mitigation for MIMO GMTI radar with Doppler division multiple access waveforms

Multiple-input multiple-output (MIMO) radar with multiple transmitters and multiple receivers can achieve a larger virtual antenna array and more system degrees of freedom; thus applying it to ground moving target indication (GMTI) radar can improve the performance of GMTI. Doppler division multiple access (DDMA) waveforms are approximately orthogonal providing good minimum detectable velocity (MDV) performance. However, in such DDMA systems, a sufficient pulse repetition frequency (PRF) design freedom is required. Furthermore, these waveforms suffer from blind velocities which are serious problems, especially in radar systems with high carrier frequency or low PRF. This paper analyses the blind velocities problem and show that blind velocities are relative to variation of the PRF and/or the carrier frequency. Variable PRF techniques are widely used in conventional GMTI radar including multiple PRFs and variable pulse repetition intervals (PRI). Combined with the characteristics of the DDMA MIMO GMTI radar, this paper proposed two methods to mitigate blind velocities: “multi-PRF DDMA” which employs multiple PRFs over successive coherent processing intervals, and “PRI-dithered DDMA” which employs nonuniform sampling by dithered PRI in slow time. Simulation results demonstrate that both the methods are effective ways to mitigate blind velocities in DDMA MIMO GMTI radar systems.     

海杂波背景下基于FRFT的多运动目标检测快速算法

针对海杂波背景中多运动目标检测问题,建立了目标检测和参数估计模型,结合小波包变换（WPT）的多尺度分辨能力和分数阶Fourier变换（FRFT）对线性调频（LFM）信号良好的能量聚集性的特点,提出了一种应用小波包变换的FRFT域动目标检测算法。算法采用“最小Shannon熵”标准确定最优小波树,利用阈值删除技术,对不同频段信号进行滤波,达到抑制海杂波的目的;经分数阶Fourier变换后,取峰值的绝对值作为检测统计量,与门限进行比较后判断目标的有无。采用分级迭代运算的方法估计目标参数,大大提高了运算速度,降低了运算量;借鉴“CLEAN”思想,有效地解决了强目标对弱目标的遮蔽影响。经X波段实测海杂波数据验证,算法具有良好的检测海杂波中微弱动目标的能力。      

The Fiddle Factor: Social Binding Functions of Distractions

An attempt is made to identify a typology of “fiddles”—informal and formal devices used by individuals and groups to facilitate communication and adhesion. Fiddling is defined as minor diversionary activity which is not directly related to the primary purpose of the person or group in communication. Identified and described on the personal level is the “fidget fiddle”; in interpersonal communication, the “conversational fiddle” and the “ritual fiddle”; in larger groups, the “orchestral fiddle” and the “task fiddle.” The “strategic fiddle,” applied to both interpersonal and group communication, is discussed. Briefly mentioned are the “catalytic fiddle” and the “status fiddle.” The typology of fiddles in communication behavior is presented as suggestive and exploratory. Relationships of the fiddle factor with education, communication research and psychoanalytic research are discussed.     

Unstructured big data analytics for retrieving e-commerce logistics knowledge

The divergent evolution of e-commerce has complicated its correspondingly logistics management. However, few studies have explored e-commerce logistics business models via big data analytics. Hence, this investigation explores e-commerce logistics business models from unstructured big data. Specifically, this work develops a hybrid content analytical model to scrutinize essential knowledge of e-commerce logistics. The empirical results of the proposed model incorporate theories of resource dependence theory (RDT) and innovation diffusion theory (IDT) to generate logistical strategies. Ten critical themes of e-commerce logistics from topic mining are “Southeast Asia’s e-commerce logistics payments”, “E-commerce order management”, “E-commerce logistics cloud services”, “E-commerce logistics package management”, “Europe e-commerce trends”, “India’s e-commerce logistics”, “E-commerce distribution management”, “Tax policies”, “E-commerce logistics platforms”, and “E-commerce logistics networks”. Moreover, the fundamental rule of “cross-border e-commerce logistics” is uncovered by the association rules model. The proposed hybrid content analytics framework provides a research foundation for e-commerce logistics management. Furthermore, e-commerce logistics can be implemented by vital strategies: “Establish inter-organizational and technical collaboration to create positive operations performance” and “Comprehend law, policy, and cultural differences to customize appropriate technologies of e-commerce logistics”.     

A super-aggregation strategy for multi-homed mobile hosts with heterogeneous wireless interfaces

Most mobile devices today are equipped with multiple and heterogeneous wireless interfaces. In this paper we ask the following question: What is the best approach to leverage the multiple interfaces available at a mobile device in terms of the performance delivered to the user? In answering the question we argue that simple “bandwidth aggregation” approaches do not provide any meaningful benefits when the multiple interfaces used have highly disparate bandwidths as is true in many practical environments. We then present super-aggregation, a set of mechanisms that in tandem use the multiple interfaces intelligently and in the process is able to achieve a performance that is “better than the sum of throughputs” achievable through each of the interfaces individually. We prototype super-aggregation on both a laptop and the Google Android mobile phone and demonstrate the significant (up to 3\(\times\) throughput) performance improvements it provides in real-world experiments. We conduct both theoretical analysis and extensive experiments to show that super-aggregation is able to improve throughput beyond the sum of the parts under most of the cases.     

“数字图像处理”课程教学中“微课”的设计与实践

微课作为新型的课程形态已成为全球教育界关注的教学模式,微课内容的设计尚处于不断深入探索的阶段。文章针对微课内容设计这一关键问题,在借鉴国内外现有的微课资源和活动基础上,结合“数字图像处理”课程的教学实践提出如何构建微课内容并合理有效地实施于课堂教学中。     

Managing networks of communities of practice for organizational knowledge creation A Knowledge Management imperative in the era of globalization

This article explores some imperatives of Knowledge Management for organizational knowledge creation in the era of globalization. As the transformation of Knowledge Management practices of Japanese firms in 1990s shows, Nonaka and TakeuchVs original model of organizational knowledge creation needs to be expanded by incorporating the concept of “community of practice” as the “engine” of knowledge creation. As an attempt for such expansion, it proposes a model of knowledge-creating organization as a self-organizing network of interactive, overlapping, and self-managing communities of practice. This article also explores some organizational conditions and managerial implications to prevent “malfunction” of communities of practice in the threats of globalization and to facilitate their dynamic evolution. Knowledge-creating organizations and their managers need to give due recognition to and support for “differences” that exist not only among diverse communities of practices but also within each communities. At a micro level approach, they need to “empower” community members by encouraging “ story-telling” or “narrative” of members’ lives in the communities and by assuring “transparency” of activities and resources to the members. As a macro level approach, they need to develop a “communitarian” organizational structure that fits to organizational knowledge creation in “multiculturalization” of societies.     

进入融媒时代新闻评论呈现的新态势

近年来,融媒时代的新闻评论在媒体人的积极探索与实践下,呈现出良性发展的新态势。主要呈现出3个方面的特征,即“功能项”的提升,新闻评论“风向标”功能的高扬、“定海神针”功能的强化和“助燃器”功能的发挥;“价值链”的延展,新闻评论价值在交流中竞现、在对流中拓展、在汇流中延伸;“新形象”的展现,具有“短平快”的速率、互动化的方式和接地气的话语。     

A Nano “Immune-Guide” Recruiting Lymphocytes and Modulating the Ratio of Macrophages from Different Origins to Enhance Cancer Immunotherapy

Artificially modulating the type, density, and location of immune cells within the tumor microenvironment can suppress tumor growth and efficiently promote current immunotherapy. In this study, a magnetite nanoparticle-based “immune-guide” is developed by the functionalization of magnetite nanoparticles with hyaluronic acid (HA). HA, an extracellular matrix component, can target various CD44-overexpressing tumors and mediate the adhesion and migration of multiple types of immune cells. Thus, HA-functionalized magnetite nanoparticles (HA-PDA@Fe₃O₄) can highly efficiently accumulate in breast cancer and penetrate deep into the tumor parenchyma. Consequently, high intratumoral concentration of HA, serving as a “guidepost,” can directly recruit lymphocytes and elicit more chemokine production through cascading amplification effects, turning the immune “cold” tumor into a “hot” one. More importantly, HA-PDA@Fe₃O₄ can effectively remodel the diversity, origin, and activation of tumor-associated macrophages by recruiting and activating infiltrating macrophages, while simultaneously reducing the M2-maintained tissue-resident macrophages. Thus, HA-PDA@Fe₃O₄ synergistically improves T cell- and macrophage-based immunotherapies as well as interferes with the formation of premetastatic niches in the lung. By redistributing the localization of HA in tumors by using magnetite nanoparticles, this study provides a unique strategy to modulate the tumor immune microenvironment and potentiate tumor immunotherapies by using biocompatible nanomaterials without any therapeutic drug.     

G.657光纤熔接和熔接损耗测试

在G.657.A2光纤推广和使用过程中,熔接和熔接损耗的测试出现了比较突出的问题或认识误区,本文分别针对"黑线"和"晕环"现象、熔接参数调整、OTDR测试熔接损耗"大正大负"等方面的问题进行了解释和汇总。     

移动衰落信道中设计多级编码(MLC)方案的一种非欧度量

本文提出了在移动衰落信道中设计多级编码(MLC)方案的一种非欧度量:"信道容量规则"+"映射规则".在AWGN信道中为:"信道容量规则"+"UP(Ungerboeck Partitioning) 规则";在Rayleigh衰落信道中为:"信道容量规则"+"BP(Block Partitioning)规则".并在此理论指导下,选用不同码长的BCH码作为MLC系统中各级分量码,通过计算机模拟,比较了在AWGN和Rayleigh衰落信道中,采用8ASK调制方式、多级译码(MSD)、三种不同映射方法下的三级MLC方案的性能.