湿式氧化处理乙烯裂解废碱液

文章研究了WAO处理乙烯裂解废碱液的方法。在2L高压釜中进行了乙烯废碱液的湿式氧化实验研究，重点考察了反应温度、停留时间对乙烯废碱液中COD、S^2-,酚的含量的影响。结果表明，湿式氧化处理乙烯裂解废碱液是可行的，处理后污水中COD、S^2-,酚的去除率分别达到40％、98％和30％，达到了排放标准。     

非临氢降凝催化剂的研制与评价

以ZSM-5为主体，加入一定量的自制BCM沸石，采用水热合成法合成新型非临氢降凝催化剂。以催化裂化柴油和减一线馏分油为原料对其反应性能进行评价。结果表明, 该催化剂具有明显的降凝效果。当反应温度为340 ℃、空速为1 h^-1时，凝点降幅为45 ℃左右，液体产品收率均在95%以上。所生产的柴油十六烷值高，硫、氮含量低，凝点低，基本满足了产品调合出厂的质量要求。     

Finite horizon optimal control of non-linear discrete-time switched systems using adaptive dynamic programming with ε-error bound

In this paper, we aim to solve the finite-horizon optimal control problem for a class of non-linear discrete-time switched systems using adaptive dynamic programming(ADP) algorithm. A new ε-optimal control scheme based on the iterative ADP algorithm is presented which makes the value function converge iteratively to the greatest lower bound of all value function indices within an error according to ε within finite time. Two neural networks are used as parametric structures to implement the iterative ADP algorithm with ε-error bound, which aim at approximating the value function and the control policy, respectively. And then, the optimal control policy is obtained. Finally, a simulation example is included to illustrate the applicability of the proposed method.     

Robust consensus algorithm for multi-agent systems with exogenous disturbances under convergence conditions

In this paper, a robust consensus algorithm is developed and sufficient conditions for convergence to consensus are proposed for a multi-agent system (MAS) with exogenous disturbances subject to partial information. By utilizing H_∞ robust control, differential game theory and a design-based approach, the consensus problem of the MAS with exogenous bounded interference is resolved and the disturbances are restrained, simultaneously. Attention is focused on designing an H_∞ robust controller (the robust consensus algorithm) based on minimisation of our proposed rational and individual cost functions according to goals of the MAS. Furthermore, sufficient conditions for convergence of the robust consensus algorithm are given. An example is employed to demonstrate that our results are effective and more capable to restrain exogenous disturbances than the existing literature.     

Sliding mode control for Markov jump linear uncertain systems with partly unknown transition rates

In this paper, based on sliding mode control approach, the robust stabilisation problem for a class of continuous-time Markovian jump linear uncertain systems with partly unknown transition rates is investigated. The transition rate matrix under consideration covers completely known, boundary known and completely unknown elements. By making use of linear matrix inequalities technique, sufficient conditions are presented to derive the linear switching surface and guarantee the stochastic stability of sliding mode dynamics. Then a sliding mode control law is designed to drive the state trajectory of the closed-loop system to the specified linear switching surface in finite time in spite of the existing uncertainties and unknown transition rates. Finally, an example is given to verify the validity of the theoretical results.     

Subcarrier allocation in multi-hop orthogonal frequency division multiple access wireless networks

Orthogonal frequency division multiplexing (OFDM) has been widely considered as a key technique for next generation mobile communication systems. Meanwhile, relaying technologies can improve users’ quality of service, increase network capacity and enlarge cellular coverage at a low cost. In this paper, we focus on subcarrier allocation and utilization in multi-hop OFDM access (OFDMA) wireless networks, and propose two efficient subcarrier allocation schemes aiming to increase network throughput and subcarrier utilization. The first scheme selects suitable links for data transmission from base stations to terminals at the beginning. Then, interference-free links are included into the same group for network resource reuse. For the purpose of global optimization, we propose a Tabu-based searching algorithm as the second subcarrier allocation scheme. Simulation results demonstrate that our proposed algorithms outperform other schemes in both network throughput and subcarrier utilization.     

Improving cache locality for GPU-based volume rendering

We present a cache-aware method for accelerating texture-based volume rendering on a graphics processing unit (GPU). Because a GPU has hierarchical architecture in terms of processing and memory units, cache optimization is important to maximize performance for memory-intensive applications. Our method localizes texture memory reference according to the location of the viewpoint and dynamically selects the width and height of thread blocks (TBs) so that each warp, which is a series of 32 threads processed simultaneously, can minimize memory access strides. We also incorporate transposed indexing of threads to perform TB-level cache optimization for specific viewpoints. Furthermore, we maximize TB size to exploit spatial locality with fewer resident TBs. For viewpoints with relatively large strides, we synchronize threads of the same TB at regular intervals to realize synchronous ray propagation. Experimental results indicate that our cache-aware method doubles the worst rendering performance compared to those provided by the CUDA and OpenCL software development kits.     

Microstructures and electrical properties of lead zinc niobate–lead titanate–lead zirconate ceramics using microwave sintering

Electrical properties and microstructural characteristics of (1 − x)(0.94PbZn_1/3Nb_2/3O₃ + 0.06BaTiO₃) + xPbZr_yTi_1−yO₃ (PZN–PZ–PT) ceramics, sintered by microwave heating, were investigated using electron microscopy, energy-dispersive spectroscopy (EDS) and electrical property measurement. Experimental results imply that the microwave-sintered (MW) samples with x = 0.5 and y = 0.52 (1150 °C, 10 min) possess higher dielectric constant than the conventionally sintered (CS) specimens (1150 °C, 2 h). Microstructural investigations show that ZnO precipitated on the surfaces of specimens during a thermal process, implying that ZnO diffusion may have influenced the distribution of phases in a specimen due to an eutectic reaction of PbO and ZnO. TEM–EDS investigations show that the CS specimens exhibit pronounced elemental segregation of PbO and ZnO at the grain boundaries, but it is much less significant for MW samples. The results imply that microwave sintering not only enhances material densification markedly, but also reduces the PbO/ZnO segregation and amorphous intergranular layers effectively, and thus improve the electrical properties of PZN–PZ–PT ceramics.     

烧结工艺对硼泥玻璃陶瓷显微结构和性能的影响

以硼泥为主要原料对制备玻璃陶瓷工艺进行研究,实验中发现烧结温度和烧结时间对析晶相的成分影响较小,但玻璃陶瓷的表面形貌影响较大;当烧结温度高于析晶温度时,对晶体尺寸影响更大;根据不同烧结温度和烧结时间对玻璃陶瓷结构影响,找出适合的最佳烧结温度和烧结时间,其值为781℃,时间为4h。     

Decentralized control: Status and outlook

This paper reviews state of the art in the area of decentralized networked control systems with an emphasis on event-triggered approach. The models or agents with the dynamics of linear continuous-time time-invariant state-space systems are considered. They serve for the framework for network phenomena within two basic structures. The I/O-oriented systems as well as the interaction-oriented systems with disjoint subsystems are distinguished. The focus is laid on the presentation of recent decentralized control design and co-design methods which offer effective tools to overcome specific difficulties caused mainly by network imperfections. Such side-effects include communication constraints, variable sampling, time-varying transmission delays, packet dropouts, and quantizations. Decentralized time-triggered methods are briefly discussed. The review is deals mainly with decentralized event-triggered methods. Particularly, the stabilizing controller–observer event-based controller design as well as the decentralized state controller co-design are presented within the I/O-oriented structures of large scale complex systems. The sampling instants depend in this case only on a local information offered by the local feedback loops. Minimum sampling time conditions are discussed. Special attention is focused on interaction-oriented system architecture. Model-based approach combined with event-based state feedback controller design is presented, where the event thresholds are fully decentralized. Finally, several selected open decentralized control problems are briefly offered as recent research challenges.