基于LVDS技术的高速数据传输系统设计

串行传输技术具有更高的传输速率和更低的设计成本,被广泛应用于高速通信领域;研究了一种基于FPGA的LVDS高速数据传输系统方案,该方案以Altera FPGA芯片为核心,通过其LVDS I/O口稳定可靠地完成数据传输,系统采用Verilog语言完成8B/10B编解码、时钟数据恢复、CRC校验、字节边界调整、误码率测试模块等;通过实验表明,该方案既满足了长距离和高速数据传输的要求,又降低了系统成本。     

Semi‐Global Output Feedback Stabilization for a Class of Uncertain Nonlinear Systems

This paper addresses the problem of semi‐global stabilization by output feedback for a class of nonlinear systems whose output gains are unknown. For each subsystem, we first design a state compensator and use the compensator states to construct a control law to stabilize the nominal linear system without the perturbing nonlinearities. Then, combining the output feedback domination approach with block‐backstepping scheme, a series of homogeneous output feedback controllers are constructed recursively for each subsystem and the closed‐loop system is rendered semi‐globally asymptotically stable.     

Stability of a class of switched stochastic nonlinear systems under asynchronous switching

The stability of a class of switched stochastic nonlinear retarded systems with asynchronous switching controller is investigated. By constructing a virtual switching signal and using the average dwell time approach incorporated with Razumikhin-type theorem, the sufficient criteria for pth moment exponential stability and global asymptotic stability in probability are given. It is shown that the stability of the asynchronous stochastic systems can be guaranteed provided that the average dwell time is sufficiently large and the mismatched time between the controller and the systems is sufficiently small. This result is then applied to a class of switched stochastic nonlinear delay systems where the controller is designed with both state and switching delays. A numerical example illustrates the effectiveness of the obtained results.     

含砷氰化尾矿回填利用污染控制技术试验研究

针对某黄金生产企业含砷氰化尾矿污染特征,开展了搅拌洗涤法、臭氧氧化法、酸化溶砷法、铁盐固砷法等多种无害化方法联合处理试验研究,旨在将该含砷氰化尾矿处理至满足氰渣规范回填利用污染控制要求。结果表明：该含砷氰化尾矿回填利用污染控制技术工艺为压滤调浆搅拌洗涤+臭氧氧化+酸化溶砷+铁盐固砷,最佳参数为原矿浆压滤后加水调浆,矿浆浓度40%,臭氧投加量0.66 g/L,酸化溶砷pH值3、曝气量0.1 m³/h、反应时间2 h,铁盐固砷七水合硫酸亚铁投加量20.0 g/L、反应时间1 h。研究结果为该黄金生产企业含砷氰化尾矿回填利用提供了技术支撑。     

D301树脂分离衣康酸的工艺研究

采用弱碱性阴离子交换树脂Ｄ３０１对发酵法生产的衣康酸进行了分离研究。通过静态交换实验，研究了Ｄ３０１树脂对衣康酸的静态交换动力学，确定了传质机制和影响因素；通过动态交换实验，研究了以硫酸为洗脱剂，以氨水为再生剂的工艺过程，确定了主要工艺参数。     

Stabilizing bit-rates in networked control systems with decentralized event-triggered communication

In a decentralized event-triggered networked control system (NCS), an agent samples and transmits its local state information to the controller when some local event occurs. Such event-triggered NCSs were expected to be more efficient than traditional periodically sampled system in terms of communication channel usage. This paper studies the stability of decentralized event-triggered NCS in the presence of quantization and delays. We point out some potential issues in decentralized event-triggered design and propose an alternative decentralized event with a linear-affine threshold, which avoids infinitely fast data transmission. Conditions on quantizer and communication channel are derived, which, when satisfied, can guarantee stability of the resulting NCS. Based on these conditions, finite stabilizing bit-rates are provided.     

Typhoon eye extraction with an automatic SAR image segmentation method

Spaceborne microwave synthetic aperture radar (SAR), with its high spatial resolution (10–100 m), large area coverage, and day/night imaging capability, has been used as an important tool for typhoon monitoring. Since the microwave signal can penetrate through clouds, SAR images reveal typhoon morphology at the sea surface. Within the region of a typhoon eye, wind speed and the associated sea surface roughness are usually low. Therefore, the typhoon eye can be well distinguished as dark areas in SAR images. However, automatic typhoon eye extraction from SAR images is hampered by SAR image speckle noise and other false-alarm dark features contained in an image. In this study, we propose an image processing approach to extract typhoon eyes from SAR images. The three-step image processing includes: (1) applying an extended non-local means image denoizing algorithm to reduce image speckle noise; (2) applying a top-hat transform to denoized imagery to enhance the contrast; and (3) using a labelled watershed to segment the typhoon eye. Experimental results from analysing three Environmental Satellite SAR typhoon images show that our approach provides fast and efficient SAR image segmentation for typhoon eye extraction. Typhoon eyes are segmented correctly, and their edges are well detected. Our experimental results are comparable to manually extracted typhoon eye information. Fine-tuning of this approach will provide an automatic tool for typhoon eye information extraction from SAR images.     

Association-Based Active Access Control models with balanced scalability and flexibility

In existing Active Access Control (AAC) models, the scalability and flexibility of security policy specification should be well balanced, especially: (1) authorizations to plenty of tasks should be simplified; (2) team workflows should be enabled; (3) fine-grained constraints should be enforced. To address this issue, a family of Association-Based Active Access Control (ABAAC) models is proposed. In the minimal model ABAAC₀, users are assigned to roles while permissions are assigned to task-role associations. In a workflow case, to execute such an association some users assigned to its component role will be allocated. The association's assigned permissions can be performed by them during the task is running in the case. In ABAAC₁, a generalized association is employed to extract common authorizations from multiple associations. In ABAAC₂, a fine-grained separation of duty (SoD) is enforced among associations. In the maximal model ABAAC₃, all these features are integrated, and similar constraints can be specified more concisely. Using a software workflow, case validation is performed. Comparison with a representative association based AAC model and the most scalable AAC model so far indicates that: (1) enough scalability is achieved; (2) without decomposition of a task, different permissions can be authorized to multiple roles in it; (3) separation of more fine-grained duties than roles and tasks can be enforced.     

管材超声波分层缺陷检测中盲区的构成探析

管材超声波分层检测作为控制产品质量的关键步骤,必须引起相关从业人员的重视,特别是要重点分析分层缺陷检测中盲区的构成原因和分布特征。只有这样,才能切实保证检测结果的准确性,更好地控制管材质量。通过对超声波分层缺陷检测的重要性进行阐释,分析了其中盲区的构成和分布等问题。     

一种基于CloudStack的企业级云资源平台网络优化研究

在对云资源平台的现状进行分析后,提出了一种基于Cloud Stack的企业级云资源平台网络优化方案,通过与现有3种解决方案进行对比,展示了该方案的可靠性和有效性。同时,针对可能存在的风险和不足进行了充分的考虑和论证,并给出了应对措施。