集中式与分布式鲁棒状态融合估计

研究不确定多传感器系统的鲁棒估计问题是多传感器融合估计理论的一个重要研究方向.本文以鲁棒滤波理论为基础,给出了不确定多传感器系统的多胞型描述模型,并利用LMI方法给出集中式鲁棒状态融合估计问题的解,证明了将集中式鲁棒融合估计转化为相同估计性能的分布式融合估计算法的条件.最后给出了分布式不确定多传感器系统的状态融合估计的一个算例.     

Auditing large plant engineering projects

The theoretical principles and the practical aspects of auditing procedures for large plant construction projects are considered. Some aspects often neglected are focused on. A form of suitable auditing report is presented.     

近红外光谱在线分析系统及应用

介绍了在线近红外光谱分析系统的组成及技术发展,以及在食品加工业、农业、废弃物体自动分类、石油化工、制药与临床医学方面的应用。近红外光谱分析技术不需对样品进行前处理,可同时对多组分样品进行瞬间分析。与光纤的连用已使它被广泛应用于过程分析。近红外在线分析技术今后将向专用、小型化方向发展。     

Study of polymer-bound mixed valence palladium catalysts. I. Preparation and characterization of polymer-bound mixed valence palladium catalysts

Polymer-bound palladium catalysts of different valence have been prepared by reducing PdCl₂ with a proper reductant, i.e., hydrazine hydrate, under certain conditions. ESR, XPS and IR were used to characterize the catalysts. Pd ⁺ was prepared for the first time and found to be stable on the polymersupport. The authors also investigated the influences of the reducing conditions, the surface properties of polymer supports and the effectsof reducing agents on the degree of reduction of divalent palladium bound onto the polymers, and the state of the palladium after reduction. The experimental results showed that the coexistence of different valence states of palladium in the supports may be Pd ²⁺, Pd^O; Pd²⁺, Pd⁺ (or Pd^δ+); Pd^O and Pd²⁺ Pd⁺ (or Pd^δ+), Pd^O. The method of preparing catalysts of mixed valence is described.     

Novel techniques for controlling the growth of and aflatoxin production by Aspergillus parasiticus in packaged peanuts

The effects of modified atmosphere packaging involving oxygen absorbents, storage temperature and packaging film barrier characteristics on the growth of and aflatoxin production by Aspergillus parasiticus in packaged peanuts was investigated. Mold growth was barely visible in air-packaged peanuts using a high gas barrier film (ASI) while extensive mold growth was observed in peanuts packaged under similar gaseous conditions using a low barrier film (ASIII). Incorporation of an oxygen absorbent (Ageless type S) inhibited mold growth in peanuts packaged in film ASI, while mold growth occurred in peanuts packaged with an absorbent/carbon dioxide generator (Ageless type G) in film ASI and in all absorbent-packaged peanuts in film ASIII. Aflatoxin B₁ production was detected at levels greater than the regulatory limit of 20 ng g^-1 in air-packaged peanuts using film ASI at 20°C and 25°C with the maximum level of aflatoxin (52·95 ng g^-1) being detected in air-packaged peanuts using film ASIII. However, aflatoxin production in all absorbent-packaged peanut samples was less than the regulatory level of 20 ng g^-1 irrespective of the barrier characteristics of the packaging film. Discoloration was more intensive in air-packaged peanuts in film ASIII especially at 25°C and 30°C than those packaged under similar or modified gaseous conditions using film ASI. This study has shown that oxygen absorbent technology is a simple and effective means of controlling the growth of and aflatoxin production by A. parasiticus. However, the effectiveness of these absorbents is dependent on the gas barrier properties of the packaging film surrounding the product.     

The NECTAR-project research into the application of neural networks for flight control

Processes with (partly) unknown or complex dynamic behaviours need complex control schemes. Neural networks offer interesting perspectives both for identification and control of these processes, because neural networks can approximate any (non-linear) continuous function. Especially adaptive control using neural networks offers good possibilities, due to the possibility to learn online. The NECTAR-project (Neural and Expert ConTrol of AircRaft) aims at studying both neural network and expert system structures for highly demanding control environments. In this publication the general structure of the project will be sketched, after which the neural network part of the project will be discussed in more detail. The final architecture will be implemented on-board of a laboratory aircraft to demonstrate the possibilities. Some preliminary results are reported.     

QUANTITATIVE AND QUALITATIVE MODELS FOR FAULT DETECTION AND ISOLATION

This paper develops a unified view of model-based approaches for fault detection and isolation (FDI), taking as a guideline the different levels of the knowledge available about the monitored system. Two functions of the FDI process are distinguished, namely alarm generation and alarm interpretation. The numerical and the qualitative model-based approaches are discussed with respect to these two functions.     

Microwave dielectric properties and cation distributions of Zn1-3xAl2+2xO4 ceramics with defect structures

The spinel-structured Zn_1-3xAl_2+2xO₄ (x = 0–0.2) ceramics having defective structures were synthesized using the molten salt method, and their microwave dielectric properties and cation distributions were assessed. The ²⁷Al solid-state nuclear magnetic resonance spectra of these ceramics demonstrate that they have an intermediate spinel structure in which the tetrahedral site occupancy increases from 0.03 to 0.64 as x increases. Moreover, crystal structure refinements suggest that cation vacancies are located at octahedral sites for x = 0.1 and 0.2. Based on these data, the introduction of cation vacancies at octahedral sites appears to enhance the preferential occupation of tetrahedral sites by Al³⁺. The ε_r of these ceramics slightly decreased from 8.5 to 8.2 with increasing x, while the Q·f value increased significantly, from 127,532 to 202,468 GHz, upon the introduction of cation vacancies. An intermediate spinel structure with preferential occupancy of tetrahedral sites by trivalent cations exhibits an enhanced Q·f value.     

新型的三电平逆变零序注入与优化

针对传统空间矢量脉宽调制(SVPWM)方式控制三电平中点钳位(NPC)逆变器中点电位时需调节每个小扇区中冗余小矢量的作用时间,实现过程繁复。在CWPWM方式下,首先通过状态平均法推导出了每个开关周期内中点电位和零序电压之间的关系,并据此构建新颖的中点电位分段控制模型,在此基础上通过设定中点电位阈值并引入滞环,对注入的零序分量进行了优化,实现了在兼顾中点电位控制的同时有效地降低开关损耗。仿真和实验进一步验证了所提优化控制策略的有效性。