IPv6网络协议中分段机制安全问题的研究

以开源Snort 平台为基础,探讨IPv6网络的分组分段机制,对利用IPv6分组分段来攻击网络的行为进行了研究。针对其中IPv6过小分组分段、重叠分段等问题提出了相应的应对措施,设计并实现了针对分段漏洞进行检测的入侵检测机制。通过实验表明,所设计的入侵检测机制能够检测相关异常的IPv6分段分组,对Snort支持IPv6功能进行了改进和优化。     

The Interesting Influence of Nanosprings on the Viscoelasticity of Elastomeric Polymer Materials: Simulation and Experiment

Among all carbon nanostructured materials, helical nanosprings or nanocoils have attracted particular interest as a result of their special mechanical behavior. Here, carbon nanosprings are used to adjust the viscoelasticity and reduce the resulting hysteresis loss (HL) of elastomeric polymer materials. Two types of nanospring‐filled elastomer composites are constructed as follows: system I is obtained by directly blending polymer chains with nanosprings; system II is composed of the self‐assembly of a tri‐block structure such as chain‐nanospring‐chain. Coarse‐grained molecular dynamics simulations show that the incorporation of nanosprings can improve the mechanical strength of the elastomer matrix through nanoreinforcement and considerably decrease the hysteresis loss. This finding is significant for reducing fuel consumption and improving fuel efficiency in the automobile tire industry. Furthermore, it is revealed that the spring constant of nanosprings and the interfacial chemical coupling between chains and nanosprings both play crucial roles in adjusting the viscoelasticity of elastomers. It is inferred that elastomer/carbon nanostructured materials with good flexibility and reversible mechanical response (carbon nanosprings, nanocoils, nanorings, and thin graphene sheets) have both excellent mechanical and low HL properties; this may open a new avenue for fabrication of high performance automobile tires and facilitate the large‐scale industrial application of these materials.     

面向矿山物联网的“计算机网络”课程的教学重构

本文根据矿山物联网的基本网络体系结构对"计算机网络"的知识点进行重构,在保持协议栈完整性的前提下重点引了无线感知的内容。在实验环节中,配套设计了多源信息集成监测实验和传感子系统接入实验,以支持矿山物联网的泛在感知。实践表明,这种重构能够提高学生的工程思维和动手能力。     

Z-source inverter for motor drives

This paper presents a Z-source inverter system and control for general-purpose motor drives. The Z-source inverter system employs a unique LC network in the dc link and a small capacitor on the ac side of the diode front end. By controlling the shoot-through duty cycle, the Z-source can produce any desired output ac voltage, even greater than the line voltage. As a result, the new Z-source inverter system provides ride-through capability during voltage sags, reduces line harmonics, improves power factor and reliability, and extends output voltage range. Analysis, simulation, and experimental results will be presented to demonstrate these new features.     

Segment-based proxy caching for Internet streaming media delivery

The proliferation of multimedia content on the Internet poses challenges to existing content delivery networks. While proxy caching can successfully deliver traditional text-based static objects, it faces difficulty delivering streaming media objects because of the objects' sizes as well as clients' rigorous continuous delivery demands. We present two techniques supporting segment based proxy caching of streaming media. We evaluated these techniques in simulations and real systems.     

High SNR sum capacity analysis of BD MIMO BC systems with imperfect CSI

We investigate the sum capacity of Block Diagonalization precoding Multiple Input Multiple Output Broadcast Channels (BD MIMO BC) with imperfect Channel State Information (CSI) at the base station. Since it is difficult to obtain the exact expression, a lower and an upper bounds of the sum capacity under Gaussian channel estimation errors are drived instead. Analyses show that the gap between two bounds is considerably tight at all Signal to Noise Ratio (SNR) region. From the lower bound of the sum capacity, we can see that the multiplexing gain tends to be zero at high SNR region, which indicates that the BD MIMO BC system with channel estimation errors is interference-limited at high SNR.     

Inverse QR iterative method for subspace tracking

The Bi-LS method based on QR decomposition provides a convenient framework for developing efficient subspace tracking algorithms. To overcome the shortcoming of the backsubstitution step and improve the parallel architecture of the Bi-LS algorithms, a Bi-LS subspace tracking algorithm based on Inverse QR (IQR) decomposition is developed. The proposed IQR iterative algorithm for subspace tracking is well suited for the parallel implementation in the systolic array. Simulation results are presented to illustrate the effectiveness of the proposed IQR subspace tracking algorithm.     

An adaptive digital image watermark algorithm based on gray-scale morphology

An adaptive digital image watermark algorithm with strong robustness based on gray-scale morphology is proposed in this paper. The embedded strategies include: The algorithm seeks and ex-tracts adaptively the image strong texture regions. The algorithm maps the image strong texture region to the wavelet tree structures, and embeds adaptively watermark into the wavelet coefficients corre-sponding to the image’s strong texture regions. According to the visual masking features, the algorithm adjusts adaptively the watermark-embedding intensity. Experimental results show the algorithm is robust to compression, filtering, noise as well as strong shear attacks. The algorithm is blind watermark scheme. The image strong texture region extraction method based on morphology in this algorithm is simple and effective and adaptive to various images.     

A novel cooperative spectrum sensing method based on cooperative game theory

A novel cooperative sensing method is proposed in this paper. The proposed scheme adopts sensing creditability degree to characterize the impact of the distance and the channel parameters on the sensing result, and considers that each user has different average SNR and different decision threshold, by using General Nash Bargaining Solution (GNBS) strategy in Cooperative Game Theory (CGT), the detec-tion performance for two-user case are derived. For multi-user case, the sensing performance is obtained with Hungarian method. Compared with the traditional schemes such as Nash Bargaining Solution (NBS) and AND, the proposed scheme covers all the factors mentioned above, and enhances the sensing rationality and reliability. Simulation results show that the proposed scheme can further improve the sensing performance and creditability.     

In-situ cleaning and passivation of oxidized Cu surfaces by alkanethiols and its application to wire bonding

The treatment of oxidized Cu surfaces using an alkanethiol as a reducing agent has been investigated. Exposure to a dilute solution of 1-decanethiol resulted in the complete removal and/or conversion of CuO and subsequent formation of a passivating thiolate film, a so-called self-assembled monolayer (SAM), on the underlying Cu/Cu₂O surface as evidenced by x-ray photoelectron spectroscopy (XPS) analysis. Morphological changes, monitored by scanning electron microscopy (SEM) and atomic force microscopy (AFM), revealed transformation of the rough, porous CuO layer into a comparatively smooth Cu/Cu₂O surface. Experiments performed on integrated circuit back-end-of-line (BEOL) die structures, comprising Cu/SiO₂ bond pads used as substrates for Cu wire bonding, demonstrate the potential application of a thiol-based in-situ cleaning-passivation procedure in microelectronics.