| 1. |
- Arm, Maria, et al.
(författare)
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Pulp mill fly ash for stabilization of low-volume unpaved forest roads — field performance
- 2014
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Ingår i: Canadian journal of civil engineering (Print). - : Canadian Science Publishing. - 0315-1468 .- 1208-6029. ; 41:11, s. 955-963
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Tidskriftsartikel (refereegranskat)abstract
- Increased temperatures and rainfalls will give more settlements and less bearing capacity in gravel roads, which will have implications for the forestry. Pulp mill fly ash without additives was used for stabilizing the road base of a low-volume gravel road. A two-year monitoring of the road was conducted, including measurements of achieved ash content, density, water infiltration capacity, and load bearing capacity. The results showed that the ash-stabilized sections performed better than conventionally upgraded sections and also achieved increased bearing capacity over time. Hydration of the fly ash increased the stiffness and decreased the permeability of the road base. The differences were more pronounced during spring thaw. Best performance was achieved in the section with thicker ash stabilized layer.
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| 2. |
- Aslani, Mohammad, et al.
(författare)
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Continuous residual reinforcement learning for traffic signal control optimization
- 2018
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Ingår i: Canadian journal of civil engineering (Print). - : NRC Research Press. - 0315-1468 .- 1208-6029. ; 45:8, s. 690-702
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Tidskriftsartikel (refereegranskat)abstract
- Traffic signal control can be naturally regarded as a reinforcement learning problem. Unfortunately, it is one of the most difficult classes of reinforcement learning problems owing to its large state space. A straightforward approach to address this challenge is to control traffic signals based on continuous reinforcement learning. Although they have been successful in traffic signal control, they may become unstable and fail to converge to near-optimal solutions. We develop adaptive traffic signal controllers based on continuous residual reinforcement learning (CRL-TSC) that is more stable. The effect of three feature functions is empirically investigated in a microscopic traffic simulation. Furthermore, the effects of departing streets, more actions, and the use of the spatial distribution of the vehicles on the performance of CRL-TSCs are assessed. The results show that the best setup of the CRL-TSC leads to saving average travel time by 15% in comparison to an optimized fixed-time controller.
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| 3. |
- Bäckström, Magnus, et al.
(författare)
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Draining function of porous asphalt during snowmelt and temporary freezing
- 2000
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Ingår i: Canadian journal of civil engineering (Print). - : Canadian Science Publishing. - 0315-1468 .- 1208-6029. ; 27:3, s. 594-598
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Tidskriftsartikel (refereegranskat)abstract
- Urban runoff creates problems with flooding and pollution of receiving waters. Furthermore, cold climate conditions have a degenerating effect on stormwater systems and road constructions. Porous asphalt has been used as a wearing course on highways and in porous pavement constructions all around the world. The main focus of this study was to evaluate the function of porous asphalt in cold climates. Measurements of the draining function of porous asphalt were carried out in a climate room with adjustable temperature in the range -10%C to +20%C. At freezing point, the infiltration capacity of porous asphalt was approximately 50% of the infiltration capacity at +20%C. When the porous asphalt was exposed to alternating melting and freezing during 2 days, conditions similar to the snowmelt period, the infiltration capacity was reduced by approximately 90%. Based on the results of this study and previous studies, the infiltration capacity of porous asphalt was estimated to be 1-5 mm/min for snowmelt conditions.
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| 4. |
- Hagentoft, Carl-Eric, 1958, et al.
(författare)
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Generic algorithm to assess moisture susceptibility of simplified wall assemblies
- 2019
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Ingår i: Canadian Journal of Civil Engineering. - : Canadian Science Publishing. - 0315-1468 .- 1208-6029. ; 46:11, s. 990-995
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Tidskriftsartikel (refereegranskat)abstract
- A simplified wall assembly consisting of four material elements is considered. Optional vapor retarder and thermal resistances are located between the elements. A simplified numerical model is presented to perform probability-based risk analysis using the Monte Carlo method. The risk assessment of the wall assembly considers the interior and exterior climatic load. The moisture transport mechanism accounted for in the analysis is diffusion. A prescribed rain load is assumed to be transferred directly to a chosen outer susceptible material element in the construction. A case study with a wooden wall structure is analyzed and the probability distribution of the time of wetness is presented for a case using 30 different climatic years, randomly varying indoor moisture excess, indoor temperature and rain leakages. The results show that, in the case investigated in this paper, the simulations converged after 600 years. The proposed simplified model, combined with the use of Monte Carlo simulations, offer an opportunity for a systematic assessment of risk.
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| 5. |
- Hanaeus, Jörgen
(författare)
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Swedish field experiences with chemical precipitation in stabilization ponds
- 1987
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Ingår i: Canadian journal of civil engineering (Print). - : Canadian Science Publishing. - 0315-1468 .- 1208-6029. ; 14:1, s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- Historically, sewage treatment in Sweden shows a development towards the construction and use of package plants. These package plants, however, present several problems associated with flow and temperature. Year-long studies of chemical precipitation using slaked lime in stabilization ponds have demonstrated an overall reduction of organic matter (as COD (chemical oxygen demand)) of about 75% to a level somewhat below 100 mg/L, and a reduction of total phosphorus of 90% to approximately 0.7 mg/L as P. These values were reached under ordinary operating plant condition. Two tracer studies using Rhodamine B dye have demonstrated the appearance of strong short-circuiting flows in ponds systems and the inserting of simple baffle walls in the pond has been recommended. Dewatering the sludge in the ponds by natural freezing has proven to be an excellent process, as the time for collecting sludge can be chosen almost arbitrarily during the year.
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| 6. |
- Marklund, S, et al.
(författare)
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Biological phosphorus removal at temperatures from 3-degrees-c to 10-degrees-c - a full-scale study of a sequencing batch reactor unit
- 1994
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Ingår i: Canadian journal of civil engineering (Print). - : Canadian Science Publishing. - 0315-1468 .- 1208-6029. ; 21:1, s. 81-88
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Tidskriftsartikel (refereegranskat)abstract
- Low temperature biological phosphorus removal technology was tested at a small village wastewater treatment plant near the Arctic circle. An aeration basin in a conventional activated sludge step was retrofitted to a sequencing batch reactor with a maximum volume of approximately 27 m3. The study period was November 1989 to June 1991. The wastewater temperature varied between 3 and 10-degrees-C during one full year and was below 5-degrees-C during approximately 240 days of the year. A total sequencing batch reactor cycle time of 6-12 hours produced a phosphorus reduction of 70-80%. During the same time, biochemical oxygen demand (BOD7) reductions varied between 70% and 90%. These reductions were achieved at supernatant suspended solid concentrations of 20-30 mg/L. Effluent soluble phosphorus concentrations were usually lower than 1.0 mg/L at water temperatures down to 5-degrees-C. At 4-degrees-C, a sharp increase to greater than 2.0 mg/L was evident. Supernatant soluble BOD7 was less than 8 mg/L and was found to be independent of temperature.
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| 7. |
- Marklund, Stefan, et al.
(författare)
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Biological phosphorus removal at temperatures from 3 to 10°C : a full-scale study of a sequencing batch reactor unit
- 1994
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Ingår i: Canadian journal of civil engineering (Print). - : Canadian Science Publishing. - 0315-1468 .- 1208-6029. ; 21:1, s. 81-88
-
Tidskriftsartikel (refereegranskat)abstract
- Low temperature biological phosphorus removal technology was tested at a small village wastewater treatment plant near the Arctic circle. An aeration basin in a conventional activated sludge step was retrofitted to a sequencing batch reactor with a maximum volume of approximately 27 m3. The study period was November 1989 to June 1991. The wastewater temperature varied between 3 and 10°C during one full year and was below 5°C during approximately 240 days of the year. A total sequencing batch reactor cycle time of 6-12 hours produced a phosphorus reduction of 70-80%. During the same time, biochemical oxygen demand (BOD7) reductions varied between 70% and 90%. These reductions were achieved at supernatant suspended solid concentrations of 20-30 mg/L. Effluent soluble phosphorus concentrations were usually lower than 1.0 mg/L at water temperatures down to 5°C. At 4°C, a sharp increase to greater than 2.0 mg/L was evident. Supernatant soluble BOD7 was less than 8 mg/L and was found to be independent of temperature.
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| 8. |
- Mufti, A.A., et al.
(författare)
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New Canadian highway bridge design code design provisions for fibre-reinforced structures
- 2007
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Ingår i: Canadian journal of civil engineering (Print). - 0315-1468 .- 1208-6029. ; 34:3, s. 267-283
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a synthesis of the design provisions of the second edition of the Canadian Highway Bridge Design Code (CHBDC) for fibre-reinforced structures. New design provisions for applications not covered by the first edition of the CHBDC and the rationale for those that remain unchanged from the first edition are given. Among the new design provisions are those for glass-fibre-reinforced polymer as both primary reinforcement and tendons in concrete; and for the rehabilitation of concrete and timber structures with externally bonded fibre-reinforced-polymer (FRP) systems or near-surface-mounted reinforcement. The provisions for fibre-reinforced concrete deck slabs in the first edition have been reorganized in the second edition to explicitly include deck slabs of both cast-in-place and precast construction and are now referred to as externally restrained deck slabs, whereas deck slabs containing internal FRP reinforcement are referred to as internally restrained deck slabs. Resistance factors in the second edition have been recast from those in the first edition and depend on the condition of use, with a further distinction made between factory- and field-produced FRP. In the second edition, the deformability requirements for FRP-reinforced and FRP-prestressed concrete beams and slabs of the first edition have been split into three subclauses covering the design for deformability, minimum flexural resistance, and crack-control reinforcement. The effect of sustained loads on the strength of FRPs is accounted for in the second edition by limits on stresses in FRP at the serviceability limit state.
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| 9. |
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| 10. |
- Sandberg, Maria, 1968-
(författare)
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Mill Case, Simulation and Laboratory Plant Study of Black Liquor Spill Effects on a Multiple Stage Biological Treatment Plant
- 2009
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Ingår i: Canadian journal of civil engineering (Print). - 0315-1468 .- 1208-6029. ; 36:5, s. 839-849
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the impact of black liquor shocks on multiple stage biological treatment plant was studied. The tests were carried out in a lab scale plant and using a mathematical simulation model. The results showed good relation to a parallel situation at the Gruvon Mill. The MultiBio concept is persistent to short-term black liquor spills due to the design where the black liquor is diluted between every compartment. According to the lab scale trials, short-term shocks (5 and 10 h) of black liquor addition reduce bio activity in the first part of the MultiBio plant. Oxygen uptake rate and chemical oxygen demand (COD) degradation decreased during high concentrations of black liquor and increased when the black liquor concentration declined. Protozoas disappeared from compartments exposed to high concentrations of black liquor. A long-term trial encompassing 24 h of black liquor addition inhibited the COD reduction in the whole plant for several weeks
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