Interactive expert systems*

The author points out the advantages of using the collective intellect of a group of experts over that of a single expert – combination of disciplines, stimulation of creativity, exploiting intuition. Use of this enhanced problem-solving capacity must also take into account the negatives – conformity, domination, misunderstandings and indiscipline. The author discusses three ways of managing groups of experts: treating them as passive suppliers of precise answers to closed questions (as in conventional expert systems), as active idea-generators responding to openended questions (cf. brainstorming etc.) or, best of all, allowing them to interact constructively either passively or actively depending on the current requirements of the problem-solving process. The role of computer technologies is then to facilitate these interactive group processes, for example by holding the stock of ‘hard’ information, or helping the unhindered provision of individual inputs and permitting collective processing of those inputs towards a problem solution, or providing the technology for predicting the consequences of candidate group-defined solutions. Such assistance would be especially valuable in economic and technological forecasting.     

Commissioning of CIL's ammonia II plant

Special features of this process design contributed to fast start-up, including the role of the computer simulator for training purposes and the concept of commissioning by process test system.     

Introduction to design and analysis of production systems

In a two-party VMI channel, the vendor operates the basic stocking and delivery functions and makes inventory replenishment decisions while the retailer is responsible for customer acquisition and in-store services. This paper focuses on such retail channel and proposes an analytical model for the partners in supply channel to determine the inventory policy with the objective of optimizing system net profit. The model explicitly incorporates issues from both the vendor and the retailer in order to derive a policy for mutual benefits. To illustrate and obtain insights from the proposed solution procedure, we devise a set of numerical analyses based on various scenarios. Factors such as shelf-space-dependent demand, shelf-space capacity, demand pattern, logistics characteristics, and disparity between holding costs of the warehouse and the retail store are also investigated.     

Sensitivity of process risk to human error in an ammonia plant

Fault tree analysis evaluates the relationship between overall process risk and human failure probabilities. Based on this information, most critical areas of operator training and/or need for automatic systems are determined.     

A methodology for constructing expert systems

Construction of Expert Systems has so far been seen as a craft or an art, not a science. This paper attempts to improve this situation by deducing some aspects of a methodology for constructing Expert Systems from a model of an expert's expertise. It suggests that the traditional methods, based on extracting problem-solving rules from an expert and encoding them directly into a suitable knowledge representation have certain disadvantages, while attempting to extract a causal model from the expert overcomes many of these. The simple Plausible Inference Expert System shell, of which several are now commercially available, is often very suited to the construction of causal models, and some practical issues concerning the construction of causal models are discussed.
The suggested methodology has been found to work in several Expert System projects in I.C.I., though it is still being developed in the light of experience. In particular, the importance of the top-down design of an Expert System is stressed, though it is not yet based on theoretical considerations.     

The communicative power of expert systems

'Expert Systems' or intelligent knowledge-based computer systems can be expected to have a considerable impact in the near future on the dissemination and use of technical expertise in practical situations. The potential benefits of such an approach to decision-making in applied science domains, for example, in anti-corrosive coating selection, are considerable. This paper argues, therefore, that a premium must be placed on such a system's performance as a communicator.
The structure and behaviour of a classical 'production system' are briefly described, and the communicative ability of such a system is analysed. This critical examination of a production system's question-answering capabilities highlights the inherent restrictions which the structure of this kind of system places on its explanatory and justificatory powers. An outline design for a less inhibitive structure is presented.
It is argued that the form in which the system provides 'answers' after the completion of a problem-solving session, may not yield sufficient appropriate information to the user, and a possible alternative view of a 'solution schema' is proposed.     

Causes of ammonia plant shutdowns survey V

The onstream factor for large tonnage ammonia plants has plummeted to 80.8 percent as inventory control and feedstock curtailment cause almost fifty percent of total downtime.     

WebFleld ECS-100P DCS系统在锅炉水处理装置上的应用

简要介绍了锅炉水处理工艺流程了控制系统的总体设计方案,重点介绍了程序控制策略及DCS实现,为以后同类装置的改造提供了一定参考借鉴。     

Modernization of an ammonia plant safety shutdown system

The Agrium Redwater Nitrogen Operations Ammonia 2 plant underwent a phased project to upgrade and modernize its automatic safety shutdown system. Agrium incorporated the use of safety integrity levels in the functional design and detailed design of the safety shutdown system to ensure that all required protections were implemented in a safe and cost-effective manner. This article discusses the methodology used to determine the scope of the system, the methodology used to define the functional design, the implementation strategy chosen and the key lessons learned from the execution of this project. © 2009 American Institute of Chemical Engineers Process Saf Prog 28:282–292, 2009     

Anhydrous ammonia explosion in an ice cream plant

Causes and consequences of the explosion where firefighters and an employee barely escaped death or serious injury in December 1983.     

Experience with a simulator for training ammonia plant operators

A computer-based simulator was used for training operators prior to the start-up of a new fertilizer complex which includes a 1,350-MTPD ammonia plant, two 1,100-MTPD urea plants, and a steam and power generation plant with two 18-MW gas turbines. The simulator offered many benefits, which can be used for continued education of operators and engineering studies.     

CIL's experience with a computerized ammonia plant trip system

The computerized trip system has been in use since August, 1985, at the CIL Ammonia II plant. Superior reliability, essential avoiding unnecessary shutdowns, while protecting the plant from accident, is obtained through use of a fault-tolerant configuration.     

Metallurgical examination of existing piping in an ammonia plant

Based on their previous problems and recent experiences at other ammonia plants, Columbia Nitrogen decided to inspect all high alloy piping containing hydrogen to determine if proper metallurgy had been used in piping and welds.     

A short survey of expert systems in UK business

The paper summarises the results of a survey on behalf of the Alvey Directorate, conducted in 1983—4, of the use made of expert systems in twelve large UK firms. The survey points clearly to the conclusion that firms do not need to start with large state-of-the-art expert systems. A practical and useful entry point is provided by simpler systems, that is, those for which the knowledge base is clear cut, the expert is available and forthcoming, the knowledge is certain, the hypotheses definite and the ancillary data are valid. The author urges influential persons in an institution uncertain whether to use expert systems to make an exploratory entry and observe the results before making a final decision.
The author believes that in the longer term expert systems will have to be designed to interface with 'popular' business language databases and with other systems. He gives some guidelines to relevant developments.