蒸汽吹灰器的常见故障分析

介绍了锅炉用吹灰器的结构和工作原理,以及生产过程中出现的常见故障。对故障原因进行了分析,并根据故障原因提出了相应的解决方法。根据生产实践中的经验,指出了生产运行中需要注意的一些常见事项,为维护检修设备提供一定的参考。     

Ambient intelligence platform using multi-agent system and mobile ubiquitous hardware

In this paper, a novel ambient intelligence (AmI) platform is proposed to facilitate fast integration of different control algorithms, device networks and user interfaces. This platform defines the overall hardware/software architecture and communication standards. It consists of four layers, namely the ubiquitous environment, middleware, multi-agent system and application layer. The multi-agent system is implemented using Java Agent DEvelopment (JADE) framework and allows users to incorporate multiple control algorithms as agents for managing different tasks. The Universal Plug and Play (UPnP) device discovery protocol is used as a middleware, which isolates the multi-agent system and physical ubiquitous environment while providing a standard communication channel between the two. An XML content language has been designed to provide standard communication between various user interfaces and the multi-agent system. A mobile ubiquitous setup box is designed to allow fast construction of ubiquitous environments in any physical space. The real time performance analysis shows the potential of the proposed AmI platform to be used in real-life AmI applications. A case study has also been carried out to demonstrate the possibility of integrating multiple control algorithms in the multi-agent system and achieving a significant improvement on the overall offline learning performance.     

A model for the determination of residential water demand by the use of tracers

A model that determines nodal demands by making tracer concentration measurements at specific nodes is developed. The model minimizes the difference between calculated and measured tracer concentrations to determine the unknown demands. Even-, over-, and under-determined cases are considered. For the purpose of verifying the model, tracer concentrations obtained by the model for known demands are considered as measurements. Results showed that the model made very accurate prediction of the unknown demands for both the even-, and the over-determined cases. The under-determined case made less accurate but still good estimates of the unknown demands for the scenarios considered here. The relationship between the sensitivity of the measurement location to the unknown demand and the accuracy of the determined demand is verified. Results showed that the model makes accurate estimation of the unknown demands if measurements are made at sensitive nodes while errors are introduced to the determined demand as a result of assuming measurements at nodes of low sensitivity.     

Occurrence of aflatoxin in commodities imported into Qatar, 1997-2000.

The occurrence of aflatoxin in commodities imported into Qatar was investigated from 1999 to 2000. During the 4 years, 351 samples of susceptible commodities were analysed. Aflatoxin was detected in 71 (20%) samples in the range 0.1-20 microg kg(-1) and in 50 (14%) samples above the permitted level of 20 microg kg(-1). The highest incidence and levels of aflatoxin contamination were recorded in pistachio without shell followed by pistachio with shell. Aflatoxin levels >20 microg kg(-1) in the pistachio samples varied from 8.7 to 33%. The highest level of total aflatoxin found in pistachio without shell was 289 microg kg(-1). A few samples of corn and corn products (three of 54 analysed), peanut and peanut products (nine of 42 analysed) and other nuts like almond, walnut and cashew (one of 40 analysed) were found contaminated with low levels (0.1-20 microg kg(-1)) of aflatoxins. Only one sample of custard powder and one sample of roasted peanut were found with aflatoxin >20 microg kg(-1)     

Wind energy potential in Aden-Yemen

The wind energy resource is very large and widely distributed throughout the world as well as in Yemen. Aden possesses a very good potential of wind energy. In this article a number of years data on wind speed in Aden has been studied and presented. A statistical analysis was carried out from which the annual wind speed was found to be 4.5 m/s and most of the time the wind speed is in the range of 3.5–7.5 m/s. The wind speed distributions were represented by Weibull and Rayleigh distributions. It was found that the Rayleigh distribution is suitable to represent the actual probability of wind speed data for Aden. The wind speed data showed that the maximum monthly wind speed occurs in the month of February with the maximum in the month of June. It is concluded that Aden can be explored for wind energy applications.     

Effect of Plasma Electrolytic Oxidation coating on the specific strength of open-cell aluminium foams

Plasma Electrolytic Oxidation (PEO) coating treatment is applied to open celled aluminium foams with different structures, aiming to enhance the mechanical performance of the composite material. The mechanical properties of the coated foams produced are assessed experimentally, both in tension and compression. From experimental results, yield stress is found to increase initially with increasing PEO coating thickness, though this trend is not maintained with thicker coatings. This is caused by the transformation of greater quantities of metal to ceramic with thicker coatings (leading to more flaw-sensitive behaviour), and higher defect density in the surface layer (reducing the strength of the coating material). The specific strength of the samples (the yield strength per unit weight for a fixed volume) is shown to initially increase with coating thickness, although, due to the diminishing mechanical benefit and constant weight increase, the effect of substantial coatings is less beneficial. The optimum coating thickness appears to be in the region of 13 μm for the low porosity replicated foams tested in compression, and a value between 18 and 50 μm for the high porosity investment cast foams tested in tension.