摘要:

The main flow characteristics of side weirs are presented. In particular, the discussion accounts for the dynamic effects on the lateral outflow intensity, the additional head losses due to the lateral and the frictional effects on the free surface profile. The pseudouniform flow condition is considered in detail. Using typical nondimensional parameters, the general solution for the free surface profiles and the local discharge distribution is presented graphically. The computational procedure is illustrated by examples.Key words: hydraulics, side weir, open channel flow, water distribution, bifurcation.

ISSN:0315-1468    

DOI:10.1139/l86-076

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

A pilot-scale stirred tank reactor was used to evaluate the efficiency of ozone for disinfecting primary effluent. Total and fecal coliform numbers before and after disinfection were evaluated concomitant with several common wastewater characteristics. A disinfection model was built using the method of linear least squares. The model enables the designer to choose the transferred ozone dose to achieve a given number of indicator bacteria in the effluent when the BOD5is known. The model was found to be useful for the primary effluent studied but should not be used in other applications without pilot plant investigations. Examination of similar models reported in the literature suggests that weak wastewaters (COD < 25 mg/L) may be described by a regression model using COD and transferred ozone as variables but extrapolation to moderate and strong wastewaters, as was done in this study, introduced gross errors. Further research into the fundamental kinetics of ozone disinfection of wastewater is necessary before a reliable design model is available.Key words: ozone, disinfection, primary eflluent, model, coliforms.

ISSN:0315-1468    

DOI:10.1139/l86-077

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

An experimental investigation was conducted to evaluate a new concept of upflow clarification. A novel sludge removal mechanism that used the entire floor area for the removal of solids was incorporated in an upflow clarifier. The operating characteristics and design features of the continuous flux upflow clarifier (CFLUC) are described in detail. The laboratory study was conducted to determine the effectiveness of the CFLUC clarifier in separating sludges with different settling characteristics. The different sludge types were produced by an activated sludge system treating a synthetic dairy waste at four different food to microorganism (F:M) ratios. At low organic loadings (0.10–0.24 (g COD)(g MLVSS)−1(d)−1), the CFLUC clarifier removed 70% of the pinpoint floe that remained during quiescent batch settling conditions. At high organic loadings (0.41–0.83 (g COD)(g MLVSS)−1(d)−1), the CFLUC clarifier was capable of separating filamentous bulking sludges with poor settling characteristics. Based on the results of the experimental study the upflow clarifier effectively separated all sludge types over the range of organic loadings investigated.Key words: CFLUC clarifier, secondary clarification, upflow clarification, sludge blanket, bioflocculation, bulking sludge, gravity sedimentation.

ISSN:0315-1468    

DOI:10.1139/l86-078

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Flow in rough steep open channels is mostly found in mountain streams and in flow overtopping protected weirs. In both cases, the energy of the flowing stream may be dissipated by artificial means so that the flowing water does not result in serious damage due to scour or erosion downstream of the main slope. The best way of achieving this purpose is to lead the flow over a series of steps. In this investigation, the author tried to determine the form drag of stepped steep open channels, considering the steps as two-dimensional triangular roughness elements.Key words: open channel flow, flow resistance, channel roughness, form drag, steep channels.

ISSN:0315-1468    

DOI:10.1139/l86-079

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

This paper looks at some of the requirements of a database for building structure data and the role of the building structure database in an integrated design system. A method of representing the necessary building structure data in a relational database is discussed. The basic data manipulation commands for relational databases are briefly explained. A demonstration database for a steel structure implemented on a microcomputer using a commercial relational database is presented.Key words: computer-aided design (CAD), database, database management system (DBMS), relational database, engineering database, building description.

ISSN:0315-1468    

DOI:10.1139/l86-080

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Severe damage during the September 19, 1985 Mexican earthquake prompted a site visit by three engineers and two seismologists representing the Canadian National Committee on Earthquake Engineering. This paper includes background information on earthquake history of the region, details of the 1985 earthquake and its strong ground motion, subsoil conditions, and building code provisions. The team's observations of moderate damage in the epicentral area are consistent with the relatively low near-field accelerations (15% g). In the damaged parts of Mexico City, soft soil conditions amplified the ground motion and resulted in almost pure harmonic motion with a period of about 2 s. These characteristics, together with the long duration and high accelerations (20% g) caused severe damage to many structures, as is illustrated in the paper. Lessons learned from the earthquake together with the Mexican emergency code changes are discussed.Key words: seismic, earthquake, Mexico, soils, structures, codes.

ISSN:0315-1468    

DOI:10.1139/l86-081

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

The Opinaca spillway is one of the concrete structures of the EOL (Eastmain – Opinaca – La Grande) project within the "La Grande" hydroelectric complex at James Bay, Quebec. Three rivers were diverted to the La Grande River to increase the hydroelectric potential of the LG 2 power plant. Opinaca spillway is a reinforced concrete structure 28.7 m wide and 46.6 m long with intake and restitution channels excavated in the rock. This paper describes the different construction phases of the spillway with emphasis on rock excavation and support, grouting, concreting, and quality control.Key words: blasting, bolting, concreting, dowel, excavation, grouting, presplitting, rock, shotcrete, spillway.

ISSN:0315-1468    

DOI:10.1139/l86-082

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

The philosophy of sludge management in the sewage treatment industry must respond to changes in processing costs and environmental requirements. As overall costs increase, the efficiency of sludge management must be increased either by ugrading the existing scheme or introducing new technology. Both of these approaches are discussed briefly in the paper and it is pointed out that low-temperature conversion of sludge to fuel appears to have considerable potential as a viable new technology.Experimental work carried out at Environment Canada's Wastewater Technology Centre used batch and continuous reactors to evaluate this technology at bench scale. Tests on a number of mixed raw sludges (primary + waste activated) resulted in the following yields: oil, 22–25%, char, 50–60%, noncondensable gas, 10–12%, and reaction water, 5–12%.The impact of a number of sludge treatment alternatives, including the conversion of sludge to oil, are discussed with respect to energy efficiency, flexibility, and public acceptance. The future plans of Environment Canada for the development and demonstration of sludge-to-oil technology are also discussed.Key words: sewage sludge, thermal conversion, energy recovery, sludge management, oil, fuel, char.

ISSN:0315-1468    

DOI:10.1139/l86-083

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

The effective width of the concrete slab of a composite beam is used in the determination of its moment resistance and service load moment for the purposes of structural design of the composite beam. It is usually assumed that the same effective width of the concrete slab may be used for both ultimate strength and elastic stage calculations.This paper presents the results of an analytical investigation of the variation of the effective width of composite beams and ribbed slabs formed by ribbed metal deck in both the elastic and inelastic stages and at ultimate load. A layered finite element method is used to model the composite beam. The influence of four variables on the effective width of the composite beams was studied, namely, type of loading, beam span to actual concrete slab width, ultimate compressive strength of the concrete, and steel beam size.It was found that the effect of the compressive strength of the concrete and the size of the steel beam have negligible influence on the effective width of the concrete slab. The effective width of the slab at ultimate load is of the order of 4% larger than that in the elastic range.The effective width used for the design of composite beams under a uniformly distributed load, which is the practical loading in most cases, is significantly different from that which should be used for any other type of loading.

ISSN:0315-1468    

DOI:10.1139/l86-084

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

This note describes how the displacements and shear stresses of an axisymmetric elastic component, when loaded in torsion, can be computed by modelling the component with torsional axisymmetric finite elements. The model developed represents only minor modifications of the well-known plane stress or plane strain finite element technique.In the analysis, the model is split into a mesh of triangular annuli. Each node of each element has only one degree of freedom, the tangential displacement. The state of strain in each element is represented by a three-term displacement function, one representing a rigid body rotation, the second representing the state of torsion, and the third representing the state of strain in a hollow thin disc.The model has been applied satisfactorily to three torsional problems with known theoretical solutions. The first problem involves the computation of torsional shear stresses of a uniform shaft subjected to pure torsion. In the second problem, the solution is obtained for a conical shaft. In the third problem, known as the Reissner–Sagoci problem, an elastic semi-infinite medium is subjected to a torsional displacement on a small area of the surface.A typical application of the model to the problem of a shrink-fitted assembly subjected to torsion is discussed.Key words: torsion, finite element, elasticity, axisymmetry.

ISSN:0315-1468    

DOI:10.1139/l86-085

出版商:NRC Research Press    

年代:1986

数据来源: NRC