摘要:

Knowledge-based systems were brought to the attention of hydrologists almost a decade ago. The application of knowledge-based systems technology is natural and appropriate for the field of hydrology because it contains numerous procedures developed from theory, actual practice, and experience. The emphasis of the present paper is on demystifying knowledge-based systems of artificial intelligence. After a detailed review of the most important applications to the field of hydrology, the original concept for applying knowledge-based technology is presented. The discussion ends with the list of possible benefits from the application of knowledge-based technology. An expert system for the selection of a suitable method for flow measurement in open channels is used as a case study to illustrate the discussion in the paper. The system has been designed for potential use in Environment Canada.Key words: expert system, water resources, hydrology, flow measurements.

ISSN:0315-1468    

DOI:10.1139/l91-001

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

Aboveground concrete cylindrical storage tanks must be designed for temperature differences between inside and outside faces of the wall. The stresses in the cylinder wall are a linear function of the temperature difference. A number of transient heat transfer finite element analyses were carried out to determine reasonable design values for this temperature difference. Extreme summer and winter conditions for southern Ontario were assumed in the analyses. It was found that for water stand-pipes supplied by groundwater the temperature difference can be as high as 25 °C, based on a summer water temperature of 10 °C. The maximum winter temperature difference was also 25 °C, based on a winter water temperature of 5 °C. For farm tower silos, a design temperature difference of 15 °C is probably more appropriate. Storage structures for other liquids can be judged if the temperature of the contained liquid is known.Key words: standpipes, structural design, temperature load, water reservoir, finite element prediction.

ISSN:0315-1468    

DOI:10.1139/l91-002

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

In many transportation studies, the time span of data collection, model development, and analysis is often too long to be responsive to the needs of policy analysts and decision makers. This problem is often exacerbated in situations with severely constrained analysis resources. Therefore, it is often useful totransfera model from one area to another. Model transfer is defined as the application of a model developed in one area to describe the corresponding behavior in another area. This paper examines the transferability of a class of models used in intercity travel demand analysis. Specifically, disaggregate mode choice models of the multinomial logit type are developed for two regions in Canada, and some established measures of transferability are applied to assess the potential of calibrating these models in one region and applying them in the other. Comparison of mode choice models estimated on data sets from the two regions yielded inconclusive results regarding model transferability. In general, transferred models were found to be 18–23% less accurate than local models in predicting modal shares. Adjusting models' parameters to reflect observed modal shares in the application context improved the predictive ability of the models by about 10%.Key words: transferability, mode choice, disaggregate, travel behavior, multinomial logit, intercity.

ISSN:0315-1468    

DOI:10.1139/l91-003

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

There are no standards for the setting of a hydraulic turbine with respect to the tailwater level. Manufacturers rely on hydraulic model data to determine the required protection against cavitation, and never publish these data. Utilities and consultants must then rely on the interpretation of published statistical data relating submergence to various turbine parameters. In this paper, an alternative approach is proposed wherein a general equation is developed relating the submergence of a stainless steel or cast steel runner to the number of runner blades, the plant capacity factor, the turbine throat velocity, the tailwater level above sea level, the water temperature, and the acceptable amount of cavitation. The equations have been tested on 39 different power plants having either horizontal or vertical axis Kaplan, propeller, or Francis turbines, both large and small. The equations are particularly useful for establishing the turbine diameter and setting during feasibility assessment, and for comparing manufacturer's suggested turbine parameters in the final design stage. The equations can also be used to determine the capacity of a new runner in an existing casing.Key words: hydroelectric, turbines, cavitation, design.

ISSN:0315-1468    

DOI:10.1139/l91-004

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

Reliability, resiliency, and vulnerability criteria are formulated as risk-based performance measures for the evaluation of a real-time reservoir operation model. The reservoir operation model includes a multi-objective compromise programming algorithm to select, in real time, an optimal operating horizon for the reservoir operation. The utility of the risk-based performance criteria for comparing operational strategies resulting from the selection of different parameters for the compromise programming algorithm is demonstrated. Although trade-offs exist between the performance evaluators, it is shown that appropriate compromises can be reached between the conflicting modeling goals.Key words: reservoir operation, real time, risk, optimization.

ISSN:0315-1468    

DOI:10.1139/l91-005

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

A general method of analysing flows in gated circular and rectangular conduits was developed, and empirical contraction coefficients were determined for typical gates in circular conduits. A momentum analysis of the flow immediately downstream of a submerged gate was also conducted.Key words: gated conduits, contraction coefficient, hydraulic jump, jet, development length.

ISSN:0315-1468    

DOI:10.1139/l91-006

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

This paper describes the effect of the cationic chelating agent penta sodium dithylene triamine penta acetate (DTPA) on anaerobic granular biomass. Batch and continuous tests indicated that acidogenic and methanogenic activity were relatively unaffected by short-term exposure to DTPA. However, long-term exposure to high concentrations (> 1800 mg/L) and low concentrations (180 mg/L) in the absence of a sacrificial trivalent cation eventually led to inhibition of hydrogen consuming and acetoclastic methanogens. An anaerobic sludge bed reactor exposed to DTPA which had been complexed to sacrificial Fe3+was not inhibited.Key words: anaerobic, wastewater, pulp, paper, DTPA, penta sodium diethylene triamine penta acetate, cationic chelator.

ISSN:0315-1468    

DOI:10.1139/l91-007

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

This paper outlines the current status of the hydrometric network of the Prairie provinces and the Northwest Territories, the data and information available, general hydrologic characteristics of the region, and efforts being made to ensure that the network continues to meet the needs of Canadians in the future.Key words: hydrology, hydrometric network, streamflow, water level, sediment.

ISSN:0315-1468    

DOI:10.1139/l91-008

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The position of railcars carrying dangerous goods in a train can affect their involvement in a derailment. A model is presented, which minimizes the number of cars carrying dangerous goods derailing for different marshalling strategies and rail corridor conditions. An application of the model to the Sarnia–Toronto rail corridor is presented. The results of this analysis suggest that marshalling strategies for cars carrying dangerous goods need to be sensitive to corridor conditions that affect the causes of train derailments. Current Canadian Transport Commission directives governing the placement of cars carrying dangerous goods along a train were found to be ineffective in reducing their derailment probability when compared to a low-cost unregulated option. Effective marshalling strategies can substitute for speed controls on the shipment of dangerous goods, resulting in a similar or improved derailment profiles and lower operating costs.Key words: dangerous goods, derailment, rail, marshalling, railcars.

ISSN:0315-1468    

DOI:10.1139/l91-009

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

This paper presents the results of an experimental study on the hydraulics of culvert fishways with spoiler baffles. Four designs were studied with the heights of the baffles equal to 0.09Dand 0.15Dand longitudinal spacings of 0.53Dand 1.06D, whereDis the diameter of the culvert. Design equations have been developed relating the flow depth to the flow rate, the diameter and the slope of the culvert for each baffle design. Expressions have also been found for the barrier velocity.Key words: culverts, fishways, hydraulics, turbulent flow, open-channel flow.

ISSN:0315-1468    

DOI:10.1139/l91-010

出版商:NRC Research Press    

年代:1991

数据来源: NRC