bluuebunny/crossref_metadata_2025 huggingface dataset:
Paralytic Shellfish Poisoning Toxin-Producing CyanobacteriumAphanizomenon gracilein Northeast Germany
Authors: Ballot Andreas , Fastner Jutta , Wiedner Claudia
Published: January 2010

Neurotoxic paralytic shellfish poisoning (PSP) toxins, anatoxin-a (ATX), and hepatotoxic cylindrospermopsin (CYN) have been detected in several lakes in northeast Germany during the last 2 decades. They are produced worldwide by members of the nostocalean generaAnabaena,Cylindrospermopsis, andAphanizomenon. Although no additional sources of PSP toxins and ATX have been identified in German water bodies to date, the observed CYN concentrations cannot be produced solely byAphanizomenon flos-aquae, the only known CYN producer in Germany. Therefore, we attempted to identify PSP toxin, ATX, and CYN producers by isolating and characterizing 92Anabaena, Aphanizomenon, andAnabaenopsisstrains from five lakes in northeast Germany. In a polyphasic approach, all strains were morphologically and phylogenetically classified and then tested for PSP toxins, ATX, and CYN by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA) and screened for the presence of PSP toxin- and CYN-encoding gene fragments. As demonstrated by ELISA and LC-MS, 14Aphanizomenon gracilestrains from Lakes Melang and Scharmützel produced four PSP toxin variants (gonyautoxin 5 [GTX5], decarbamoylsaxitoxin [dcSTX], saxitoxin [STX], and neosaxitoxin [NEO]). GTX5 was the most prevalent PSP toxin variant among the seven strains from Lake Scharmützel, and NEO was the most prevalent among the seven strains from Lake Melang. ThesxtAgene, which is part of the saxitoxin gene cluster, was found in the 14 PSP toxin-producingA. gracilestrains and in 11 non-PSP toxin-producingAphanizomenon issatschenkoi,A. flos-aquae,Anabaena planktonica, andAnabaenopsis elenkiniistrains. ATX and CYN were not detected in any of the isolated strains. This study is the first confirming the role ofA. gracileas a PSP toxin producer in German water bodies.
Pseudomonas aeruginosaAlginate PromotesBurkholderia cenocepaciaPersistence in Cystic Fibrosis Transmembrane Conductance Regulator Knockout Mice
Authors: Chattoraj Sangbrita S. , Murthy Rachana , Ganesan Shyamala , Goldberg Joanna B. , Zhao Ying , Hershenson Marc B. , Sajjan Umadevi S.
Published: January 2010

Pseudomonas aeruginosa, a major respiratory pathogen in cystic fibrosis (CF) patients, facilitates infection by other opportunistic pathogens.Burkholderia cenocepacia, which normally infects adolescent patients, encounters alginate elaborated by mucoidP. aeruginosa. To determine whetherP. aeruginosaalginate facilitatesB. cenocepaciainfection in mice, cystic fibrosis transmembrane conductance regulator knockout mice were infected withB. cenocepaciastrain BC7 suspended in either phosphate-buffered saline (BC7/PBS) orP. aeruginosaalginate (BC7/alginate), and the pulmonary bacterial load and inflammation were monitored. Mice infected with BC7/PBS cleared all of the bacteria within 3 days, and inflammation was resolved by day 5. In contrast, mice infected with BC7/alginate showed persistence of bacteria and increased cytokine levels for up to 7 days. Histological examination of the lungs indicated that there was moderate to severe inflammation and pneumonic consolidation in isolated areas at 5 and 7 days postinfection in the BC7/alginate group. Further, alginate decreased phagocytosis ofB. cenocepaciaby professional phagocytes bothin vivoandin vitro. P. aeruginosaalginate also reduced the proinflammatory responses of CF airway epithelial cells and alveolar macrophages toB. cenocepaciainfection. The observed effects are specific toP. aeruginosaalginate, because enzymatically degraded alginate or other polyuronic acids did not facilitate bacterial persistence. These observations suggest thatP. aeruginosaalginate may facilitateB. cenocepaciainfection by interfering with host innate defense mechanisms.
ATP-Dependent Carboxylation of Acetophenone by a Novel Type of Carboxylase
Authors: Jobst Björn , Schühle Karola , Linne Uwe , Heider Johann
Published: January 2010

Anaerobic ethylbenzene metabolism in the betaproteobacterium
Aromatoleum aromaticum
is initiated by anaerobic oxidation to acetophenone via (
S
)-1-phenylethanol. The subsequent carboxylation of acetophenone to benzoylacetate is catalyzed by an acetophenone-induced enzyme, which has been purified and studied. The same enzyme is involved in acetophenone metabolism in the absence of ethylbenzene. Acetophenone carboxylase consists of five subunits with molecular masses of 70, 15, 87, 75, and 34 kDa, whose genes (
apcABCDE
) form an apparent operon. The enzyme is synthesized at high levels in cells grown on ethylbenzene or acetophenone, but not in cells grown on benzoate. During purification, acetophenone carboxylase dissociates into inactive subcomplexes consisting of the 70-, 15-, 87-, and 75-kDa subunits (
apcABCD
gene products) and the 34-kDa subunit (
apcE
gene product), respectively. Acetophenone carboxylase activity was restored by mixing the purified subcomplexes. The enzyme contains 1 Zn
2+
ion per αβγδ core complex and is dependent on the presence of Mg
2+
or Mn
2+
. In spite of the presence of Zn in the enzyme, it is strongly inhibited by Zn
2+
ions. Carboxylation of acetophenone is dependent on ATP hydrolysis to ADP and P
i
, exhibiting a stoichiometry of 2 mol ATP per mol acetophenone carboxylated. The enzyme shows uncoupled ATPase activity with either bicarbonate or acetophenone in the absence of the second substrate. These observations indicate that both substrates may be phosphorylated, which is consistent with isotope exchange activity observed with deuterated acetophenone and inhibition by carbamoylphosphate, a structural analogue of carboxyphosphate. A potential mechanism of ATP-dependent acetophenone carboxylation is suggested.
Strengthening of reinforced concrete flexural members using externally applied steel plates and fibre composite sheets — a survey
Authors: McKenna J. K. , Erki M. A.
Published: January 2010

In Canada, as in many other parts of the world, the deterioration of reinforced and prestressed concrete bridges and parking garage structures has reached alarming proportions. Many of these structures face very expensive rehabilitation work or outright replacement. Although strengthening reinforced concrete structures using externally bonded or bolted steel plates is a technology that is not widely known in North America, a number of structures in Europe, Australia, and South America have been rehabilitated using this method. The weight of the steel plates, which makes them difficult to handle in the field, and their susceptibility to corrosion have led to research into the possibility of replacing steel plates with high strength fibre composite sheets. Fibre reinforced composite sheets are composed of carbon, glass, or aramid fibres, bound by a resin epoxy. In addition to being light in weight, these materials do not corrode. Very recently, a few bridges have been repaired in Europe using carbon fibre and glass fibre reinforced plastic sheets. This paper reviews the case studies and research pertaining to the use of steel plates and fibre composite sheets to strengthen and repair reinforced concrete flexural members. Key words: rehabilitation, strengthening, advanced composite materials, fibre reinforced composites, bonding.
Load model for bridge design code
Authors: Nowak Andrzej S.
Published: January 2010

The paper deals with the development of load model for the Ontario Highway Bridge Design Code. Three components of dead load are considered: weight of factory-made elements, weight of cast-in-place concrete, and bituminous surface (asphalt). The live load model is based on the truck survey data. The maximum live load moments and shears are calculated for one-lane and two-lane bridges. For spans up to about 40 m, one truck per lane governs; for longer spans, two trucks following behind the other provide the largest live load effect. For two lanes, two fully correlated trucks govern. The dynamic load is modeled on the basis of simulations. The results of calculations indicate that dynamic load depends not only on the span but also on road surface roughness and vehicle dynamics. Load combination including dead load, live load, dynamic load, wind, and earthquake is modeled using Turkstra's rule. The maximum effect is determined as a sum of the extreme value of one load component plus the average values of other simultaneous load components. The developed load models can be used in the calculation of load and resistance factors for the design and evaluation code. Key words: bridge, dead load, live load, dynamic load, load combinations.
Seismic load distribution in buildings with eccentric setback
Authors: Tso W. K. , Yao Shu
Published: January 2010

A study is carried out to evaluate the seismic load distribution in buildings with eccentric setback subjected to lateral loading in a direction perpendicular to the setback. Such loading causes both translational and torsional deformations. Since buildings with eccentric setback possess significant irregularities both height-wise and plan-wise, both the static and the dynamic approaches are used in this study to examine the limitations of the static approach when applied to this class of structures. It is shown that the static approach cannot simulate the higher modal contribution, nor can it simulate the inertial floor torques caused by the first mode of vibration. Consequently, the static approach leads to an underestimation of edge frame shears. However, by modifying the static approach as is done in the Canadian code (National Building Code of Canada, 1990) one can obtain load distributions in eccentric buildings that are similar to that using dynamic analysis. Based on the work of Goel and Chopra, it is further shown that implementation of the Canadian code procedure for seismic load distribution involving torsion can be simplified greatly. As a result, this procedure can be implemented efficiently in design offices to cover a wide class of buildings, including buildings with eccentric setbacks. Key words: seismic, buildings, torsion, setback, irregularity, code.
Seismic risk management for existing structures
Authors: Sexsmith Robert G.
Published: January 2010

Recent changes in seismic criteria have resulted in a perceived increase in seismic risk for many existing structures. Difficult seismic retrofit decisions may be required, involving considerations of risk, initial costs, and long-term consequences. This paper illustrates the application of an expected value decision model to seismic retrofit policies. The paper outlines the features of a logical model for choice of safety level, for alternative retrofits to a single structure, and for establishing priorities among a set of retrofit actions for one or a group of structures.Codes and standards constrain the range of possible actions; however, they are not well developed for retrofit of existing structures. It is therefore important to consider investments in safety through retrofits on the basis of present expected values, in a manner similar to insurance purchases. Consideration of the factors involved in such decisions, including seismic risk, cost of retrofit, and consequences of seismic events with and without the retrofit, will lead to improved information and better allocation of scarce retrofit funds. Key words: seismic risk, decision analysis, seismic retrofit.
Scheduling and control of linear projects
Authors: Eldin Neil N. , Senouci Ahmed B.
Published: January 2010

A two-state-variable, N-stage dynamic programming approach to scheduling and control of linear projects is presented. This approach accounts for practical considerations related to work continuity, interruptions, and lags between successive activities. In the dynamic programming formulation, stages represent project activities and state variables represent possible activity resources and interruptions at each location. The objective of the dynamic programming solution is to provide for the selection of resources, interruptions, and lags for production activities that lead to the minimum project total cost. In addition, the presented system produces a graphical presentation of the optimum project schedule and updates the original schedule based on update information input by the user. The updated schedule determines the new completion date, and forecasts the project new total cost based on the current project performance. A small linear project is provided as a numerical illustration of the system. Key words: dynamic programming, linear projects, scheduling systems, optimization of cost and scheduling durations.
Design of a coarse bubble aeration system for the bioremediation of a liquid chemical dump site
Authors: Schmidtke N. W. , Smith D. W.
Published: January 2010

The objective of designing an aeration system capable of transferring an adequate amount of oxygen to a multifaceted chemical waste mixture originating from earlier indiscriminate dumping of residuals from chemical manufacturing operations presented special problems. The dump consisted of a natural depression of irregular geometry with variable depth to 8 m. The liquid had a suspended solids concentration of up to 100 000 mg/L during in-situ treatability studies. The in-situ studies had demonstrated that the chemicals could be aerobically biodegraded to concentrations that would meet discharge criteria. The entire installation is to be operated as a temporary (5-year-life) treatment facility. The accumulated complex organic compounds, the chemical waste solids, the irregular geometry of the depression, and the requirement to provide external supplementary mixing presented a unique process design challenge. This paper describes the approach taken in the selection and design of an aeration system which will meet these constraints. The approach consisted of using a combination of pilot and field-scale data and coupling this with experiences reported in the literature and fundamental oxygen transfer considerations. The solution consisted of a flexible, modular design, coarse bubble aeration system capable of delivering up to 20 000 L/s of air at a power input of 1790 kW. Information on the aeration system sizing, layout, and costing, both capital and operating, is provided. Key words: bioremediation, aeration, gas transfer, chemical waste, KLa determination, biological waste treatment.
Seismic acceleration zones in the Vancouver area
Authors: Weichert Dieter
Published: January 2010

Since 1990, an increased number of locations for the Lower Mainland of British Columbia has been listed in the Table of Climatic Data in the Supplements to the National Building Code of Canada. While for most of the new locations the seismic acceleration and velocity zones are shown as Za = Zv = 4, Ladner is listed with Za = 5, leading to significant cost increase in the construction of certain types of buildings. Although the zonal value is formally correct, it is suggested that such discrimination is not justified by the current precision of seismic hazard estimation.The Canadian National Committee on Earthquake Engineering does not address regional variances of this nature; it is, therefore, further suggested that a regional committee should decide on an equitable solution, with due consideration of estimated probabilities of exceeding ground motion parameters, and the precision of these estimates. Some of the background and details aiding such a decision are discussed. Key words: seismic hazard, acceleration, seismic zones, earthquake design, Vancouver acceleration.
Accident prediction models for rural roads
Authors: Persaud Bhagwant N.
Published: January 2010

Following on earlier work, the development of additional models for estimating the accident potential of rural road sections is described. In the modelling procedure presented, Ontario data are used to develop regression model estimates of a section's accident potential based on its traffic and geometric characteristics, and an empirical Bayesian procedure is used for refining these estimates using the section's accident count. These refined estimates are shown in a validation exercise to be superior to estimates based on accident counts or regression models only. This method of estimating accident potential is recommended for use in the identification of accident blackspots and in the evaluation of safety treatments on rural roads. To facilitate this use, detailed example applications are presented. Key words: safety, empirical Bayesian, accident prediction, rural roads, generalized linear modelling, accident modelling.
Properties of steel fiber reinforced shotcrete
Authors: Banthia Nemkumar , Trottier Jean-Francois , Beaupre Denis , Wood David
Published: January 2010

Five commercially available steel fibers with different geometries were investigated both in dry-mix and in wet-mix shotcretes. In the dry process, bulk-bin bags with dry premixes were used. In the wet process, ingredients were wet-mixed centrally in a batching plant and then transported to the shooting site in ready-mix trucks. Mixes were shot on wooden forms and the rebound characteristics of the fibers and other ingredients were determined. Once hardened, shotcrete panels were sawed and cored to obtain beam specimens for flexural toughness tests and cylinders for compression tests. Hardened shotcrete specimens were also tested for boiled absorption and permeable voids. The boiled absorption and permeable voids data indicated that an adequately dense in-place shotcrete was obtained for both processes. The rebound of fibers in the dry process was found to be much higher than that in the wet process. Both compressive and flexural strengths were found to be improved because of the addition of fibers. Fibers also led to a significant enhancement in the toughness of shotcrete. Key words: shotcrete, wet mix, dry mix, steel fibers, rebound, toughness.
Structural performance of cavity walls constructed with units containing sawdust and shear connected to the brick veneer
Authors: Goyal Ajay , Rashwan M. Shokry , Hatzinikolas M. A. , Zervos S.
Published: January 2010

A series of experiments were conducted to investigate the behaviour of walls constructed using newly developed masonry sawdust blocks. Full-scale cavity walls consisting of the new masonry block backup and burnt clay brick veneer, connected together using metal connectors, were tested under lateral loads. The effects of block unit size, height of wall, reinforcement, grout, and cavity width on the behaviour of the wall were studied. The test results showed behaviour similar to that of walls constructed with lightweight concrete masonry units. A summary of the results is presented in this paper. Key words: masonry, cavity wall, shear connector, lateral loading, stiffness, veneer, sawdust block.
Loss of freeze–thaw durability of concrete containing accelerating admixtures
Authors: Stott D. , Rezansoff T. , Sparling B. F.
Published: January 2010

Rapid freeze–thaw durability tests on air entrained concrete mixes containing a proprietary nonchloride accelerating admixture or CaCl2 show that although early age compressive strength acceleration is achieved, the freeze-thaw durability is reduced when compared with the durability of control concretes of similar mix proportions, but without accelerating admixtures. Although the compressive strength gains were accelerated in mixes containing either the proprietary accelerating admixture or CaCl2, the tensile strengths at 28 days were similar for mixes with and without the admixtures.Petrographic analyses showed air contents and air void spacing factors in concretes with accelerating admixtures, either nonchloride or CaCl2, to be similar to the air systems in the control concrete, though more air entraining agent was required with the mixes containing accelerating admixtures. Local aggregates as well as aggregates from three alternate sources were used. Test results did not show any significant differences in durability on the basis of aggregate source.As the larger reduction measured in freeze–thaw durability for concrete mixes containing either chloride or nonchloride accelerating admixtures could not be attributed to either a deficient air void system in the cured concrete or inferior aggregate, it is believed that the cause is some characteristic or a hydration product in the cement paste microstructure produced by accelerated hydration. Key words: concrete, durability, freeze–thaw testing, strength acceleration, admixtures, air void system.
Factors affecting construction productivity: Newfoundland versus rest of Canada
Authors: Hanna A. S. , Heale Donald G.
Published: January 2010

The decline in construction productivity across North America since the mid 1970s has been reported by many researchers. The potential exists to achieve major cost savings if the factors underlying this decline can be identified and quantified and solutions are found. The issue is complex, but it is generally acknowledged as an axiom that it is a management problem and within the control of management to rectify. This paper describes the results of a survey of the attitudes of construction professionals across Canada toward factors affecting construction productivity. Special emphasis is made to the differences between Newfoundland and the rest of Canada. Findings for different regions of the country are presented and contrasted. For the purpose of this study, the factors have been classified into six groups: (i) contract environment, (ii) planning, (iii) site management, (iv) working conditions, (v) working hours, and (vi) motivation. Major factors affecting productivity are identified. The survey questionnaire addressed these factors within the groups indicated. Respondents commented freely on factors that they considered to be of great importance to construction productivity, such as quality of labor skill, project communication, timeliness, and equipping of crews. Key words: construction productivity, Canadian construction, unemployment insurance benefit.
Discussion: Hydrotechnical studies of Peter's River
Authors: Russell S. O. Denis
Published: January 2010

not available
Effect of pH on metal solubilization from sewage sludge: a neural-net-based approach
Authors: Du Y. G. , Sreekrishnan T. R. , Tyagi R. D. , Campbell Peter G. C.
Published: January 2010

Microbial leaching for heavy metals removal from municipal sewage sludge is a complex biological process. The ultimate metal solubilization achieved depends on the type of sludge involved (nondigested, aerobically digested or anaerobically digested sludge), the decrease in sludge pH as a result of the leaching operation, and the concentration of metals initially present in the sludge. In addition, the system temperature exerts an indirect but strong influence by its effect on the bacterial growth and acid production process. A neural-net-based model was developed to predict the solubilization of six heavy metals, Cd, Cr, Cu, Ni, Pb, and Zn, from sewage sludge using the bioleaching process. The only input parameters required are the type of sludge, initial metal concentrations in the sludge, and the sludge pH. The model yielded satisfactory predictions of metal solubilization when tested with a number of actual experimental data. Key words: heavy metals, microbial leaching, modelling, neural-net, sewage sludge.
Adaptive forecast of multi-month lake level elevations
Authors: Bennis Saad , Assaf Gabriel J.
Published: January 2010

The early and precise prediction of the water levels in lakes is a major concern for public authorities. Such predictions describe the evolution of the water levels and are essential for appropriate flood control measures. In this paper, a new ARMAX-type model is developed to predict, months in advance, the monthly fluctuations of the water level of Lake Erie. The predictive variables used in the model are the past monthly water levels of Lakes Erie, Superior, and Michigan–Huron along with the estimated response times between water flow entries and exits. Two scenarios are compared. The first scenario is based on the ordinary least squares (OLS) technique in order to identify the parameters of the ARMAX-type model, to filter measurement and model noises, using the ARMAX Kalman predictor (AKP), and to optimize predictions. In this scenario, the model parameters remain unchanged throughout the simulation. The second scenario is based on the mutually interactive state parameter (MISP) technique in order to readjust the parameters of the model at each time step and to filter measurement and modelling noises through the Kalman predictor. In this scenario, the parameters of the model change with time. The analysis shows that the MISP–AKP framework has a slightly higher Nash coefficient than the OLS–AKP framework for the first month. In subsequent months, however, the quality of the predictions based on the OLS–AKP technique improves significantly. This observation also applies to the persistence and extrapolation coefficients as well as to the sample autocorrelation functions for the residuals of the Lake Erie water level forecast. It was therefore decided to apply the MISP–AKP technique to obtain the first prediction of the Lake Erie level, and the OLS–AKP technique to compute subsequent predictions. Key words: adaptive, forecast, Kalman's filter, lake levels, MISP algorithm, Great Lakes.
Combined effects of end distance and spacing on the resistance of split ring connectors loaded in tension
Authors: Charron A. , Quenneville P.
Published: January 2010

An experimental study was undertaken to verify the combined effects of timber connector end distance and spacing requirements of the Canadian standard for engineering design in wood. A total of 130 test specimens using 63 mm diameter split rings were loaded to failure in tension. The split ring end distance varied between 50 and 210 mm and the spacing varied between 80 and 200 mm. Results show that a linear relation exists between the connector end distance and its resistance for a given spacing. Increase in spacing also results in an increase of the connector resistance for a given end distance. Also, connections with two connectors in a row can resist significant loads even if the end distance or spacing of one connector is below the standard minimum required value. Thus, the design philosophy of Clause 10.3.3 of the wood design standard is inadequate for these joints. Key words: split ring, tension, end distance, spacing, resistance, timber.
Seismic retrofitting techniques for bridges — a state-of-the-art report
Authors: Mitchell Denis , Sexsmith Robert , Tinawi René
Published: January 2010

This paper presents a review of the various seismic retrofitting techniques currently being carried out for bridge structures. After evaluating the performance of existing bridges in past earthquakes and their most common modes of failure, a systematic review of bridge retrofit is discussed. It includes the retrofit of foundations, concrete columns, bent cap beams and beam-column joints, as well as steel bracing. The use of restrainers is discussed as well as the possible improvements to bearing supports. Examples of bridge retrofit practice in California and British Columbia are presented. Key words: bridges, retrofitting, earthquakes.
SMPLNORM : Un modèle simple pour obtenir les probabilités conjointes de deux débits et le niveau qui en dépend
Authors: Bruneau Pierre , Ashkar Fahim , Bobée Bernard
Published: January 2010

Most bivariate models assume the same type of marginal distribution, with two parameters, for two variables (gamma, type I extreme values, and so forth). The disadvantage of these models is that it is often difficult to make adjustments for observed flows. This study shows the application flexibility of a program that calculates the joint probability of two variables, Q1, and Q2, with marginal distributions that have three parameters. The program can also provide the probability of nonexceedence of a third variable, H, mathematically related to the first two variables. Two applications are discussed, in which Q1 and Q2 are the flows of two rivers controlling the variable H, which is a level in both cases. Theoretically, this model could also be applied to other types of variables. The proposed model is based on the hypothesis that a Box–Cox type of power transformation could reduce the marginal distributions of Q1 and Q2 to a normal distribution. One of the main conclusions of the study addresses the importance of taking into account the correlation between Q1 and Q2 to obtain a valid estimate of H. Key words: hydrology, statistics, bivariate models, Box–Cox, flow, water level. [Traduit par la rédaction]
Limit states design of antenna towers
Authors: Wahba Yohanna M. F. , Madugula Murty K. S. , Monforton Gerard R.
Published: January 2010

The Canadian Standard CAN/CSA-S37-M86 “Antennas, towers and antenna supporting structures” follows a quasi-limit states approach in which the member forces determined for specified loads are multiplied by a unified factor and compared with factored resistances given in CAN3-S16.1-M84. This results in designs basically the same as those resulting from a working stress design with a factor of safety of 5/3. Such structures exhibit a non-linear structural behaviour even under service loads. Thus the effect of ice accretion and direct interaction between wind and ice does not permit the load factors specified in CAN/CSA-S16.1-M89 “Limit states design of steel structures” to be directly applied to antenna supporting structures.In this study, 41 different towers (representing various heights and designed for different ice classes and wind pressures) were analyzed under specified loads and then under a set of factored loads. From the comparison of the design forces in the towers with those calculated according to the existing standard, a set of partial load factors was derived. The new load factors to be used in the 1993 edition of S37 are presented and justified. Key words: antenna towers, guyed towers, ice and wind loads, limit states design, self-supporting towers, working stress design.
A mechanistic evaluation of modified asphalt paving mixtures
Authors: Ali N. , Zahran Shaher , Trogdon Jim , Bergan Art
Published: January 2010

The main purpose of this study was to facilitate decisions concerning the effectiveness of modifiers in mitigating pavement distress and improving long-term overall pavement performance in actual field conditions, by utilizing short-term laboratory results and a mathematical prediction model. The modifiers investigated were carbon black, neoprene latex, and polymer modified asphalt (STYRELF). The statistical general linear model (GLM) and the Fisher least significant difference (LSD) were used for the analysis of data. The results of the study indicate that the effect of the modifier on the paving mixture properties was insignificant at low temperatures (down to −17 °C), but significant at high temperatures (up to 60 °C) where the synergistic effect of the modifier on the paving mixture was pronounced. The VESYS IIIA pavement performance prediction model was utilized to assess the effects, if any, of the modifier on the pavement's overall performance. All the modifiers improve, to some degree, the overall pavement performance. Key words: modifiers, asphalt, paving mixtures, pavements, polymer asphalt.
A new method for mathematical modelling of complex stage–discharge relations
Authors: DeGagné Mark P. J. , Simonovic Slobodan P.
Published: January 2010

This paper describes a computer-based approach named multiobjective stage–discharge evaluator (MOSDE), which employs the method of regression analysis for the development of stage–discharge rating curves. The regression is done recursively as the program steps through the data set, by adding one point at each iteration. Multiobjective analysis is used to evaluate the improvement or deterioration of the model using a set of statistical criteria. The overall task is to fit a proper curve, or curves, to any given stage–discharge data set. Also, the key transition points in the stage–discharge relation are identified. This process eliminates ambiguity or subjectivity associated with the current methods used for the development of stage–discharge relationships. The MOSDE system has been tested using two different data sets. Key words: operational hydrology, stage–discharge, multiobjective analysis, mathematical modelling.
Ductility and overstrength in seismic design of reinforced concrete structures
Authors: Mitchell Denis , Paultre Patrick
Published: January 2010

The paper first reviews the different approaches taken by codes of practice in their treatment of ductility demand by the use of force modification factors. The way in which structural overstrength affects structural response and the factors influencing overstrength are discussed. Nonlinear analyses of reinforced concrete structures, designed by the Canadian codes, demonstrate the significance of structural overstrength on the ability of the structures to resist lateral load without collapse. The manner in which structural overstrength can be accounted for in the design of reinforced concrete structures is presented. Key words: seismic design, detailing, reinforced concrete, ductility, overstrength, base shear.
Application de la fonction bêta et des polynômes de Jacobi à l'analyse des valeurs extrêmes
Authors: Llamas J. , Delgado C. Diaz , Lavertu M.-L.
Published: January 2010

In this paper, an improved probabilistic method for flood analysis using the probable maximum flood, the beta function, and orthogonal Jacobi’s polynomials is proposed. The shape of the beta function depends on the sample's characteristics and the bounds of the phenomenon. On the other hand, a serial of Jacobi’s polynomials has been used improving the beta function and increasing its convergence degree toward the real flood probability density function. This mathematical model has been tested using a sample of 1000 generated beta random data. Finally, some practical applications with real data series, from important Quebec's rivers, have been performed; the model solutions for these rivers showed the accuracy of this new method in flood frequency estimation. Key words: probable maximum flood, beta function, orthogonal polynomials, distribution function, flood frequency estimation, data generation, convergency.
Seismic storey drift estimation
Authors: Zhu T. J.
Published: January 2010

The seismic storey drift estimation procedure in the 1990 edition of the National Building Code of Canada is evaluated for ductile moment-resisting frame buildings located in different seismic regions. The evaluation is based on a comparison of the storey drifts estimated from the code procedure with those obtained from the inelastic dynamic analysis of the buildings. The results indicate that the code procedure underestimates storey drift for low-rise ductile moment-resisting frame buildings. It provides good estimates of storey drift for medium- and high-rise ductile moment-resisting frame buildings. The code estimation tends to become conservative as the number of storeys increases. Key words: building, design, drift, seismic, storey.
Some characteristics of high-strength structural concrete: Part 2
Authors: Bickley J. A. , Ryell J. , Rogers C. , Hooton R. D.
Published: January 2010

The 68-storey Scotia Plaza tower in Toronto is an outstanding example of the use of concrete technology to achieve high-performance, high-strength concrete. Cementitious hydraulic slag, silica fume, and a superplasticizer were combined with CSA type-10 Portland cement and high-quality aggregates to produce very workable high-strength concrete. During the course of construction, data were published suggesting the possibility of the strength regression of test cylinders of some silica fume concretes after long exposure to low humidity. To address this concern, tests were made at ages of 1 year and 2 years on specimens drilled from columns in the structure. These data were published in Volume 18 of this journal. In this note, results of additional tests at 7 years are described and compared with the results of earlier tests. Key words: high strength, slag, silica fume, permeability, rapid chloride permeability, petrographic examination, superplasticisers.
Étude de la réouverture de la lagune du Havre aux Basques. I. Modélisation numérique des conditions d'écoulement
Authors: Ouellet Y. , Khelifa A. , Bellemare J.-F.
Published: January 2010

A numerical study based on a two-dimensional finite element model has been conducted to analyze flow conditions associated with different possible designs for the reopening of Havre aux Basques lagoon, located in Îles de la Madeleine, in the middle of the Gulf of St. Lawrence. More specifically, the study has been done to better define the depth and geometry of the future channel as well as its orientation with regard to tidal flows within the inlet and the lagoon. Results obtained from the model have been compared and analyzed to put forward some recommendations about choice of a design insuring the stability of the inlet with tidal flows. Key words: numerical model, finite element, lagoon, reopening, Havre aux Basques, Îles de la Madeleine.
Tests of full-size composite beams with perfobond rib connectors
Authors: Oguejiofor E. C. , Hosain M. U.
Published: January 2010

This paper presents the test results of six full-size composite beam specimens with perfobond rib shear connectors embedded in solid concrete slab. The objective of this investigation was to study the performance of this connector in full-size composite beams and to correlate the test results with those obtained from push-out specimens. In the first three beam specimens, the amount of transverse reinforcement was varied. Two other specimens were used to investigate the effectiveness of more perfobond rib connectors of shorter length. The effect of passing transverse reinforcing bars through the connector rib holes was investigated using the last specimen. Failure of the test specimens was initiated by longitudinal splitting of the concrete slab, eventually culminating in the crushing of concrete in the bearing zone immediately in front of the end perfobond rib connectors. The test results showed that increasing the transverse reinforcement ratio, excluding the wire mesh, from 0.11% to 0.20% led to a 10% increase in the ultimate capacity. The test specimen with six 251 mm long connectors sustained 11% higher ultimate capacity compared to that with four 376 mm long connectors. An increase of 8.4% in the ultimate strength was observed when transverse reinforcing bars were passed through the perfobond rib holes while keeping the total amount of transverse reinforcement unchanged. The experimental values of the ultimate flexural capacity of the beam specimens were, on the average, approximately 1.11 times the predicted values based on push-out test results. Key words: composite beam, perfobond rib connector, push-out test, full-size test, flexural capacity.
Cyclic behaviour of locally web-stiffened W-shape beams
Authors: Korol R. M. , Daali M. L.
Published: January 2010

A series of tests on W-shaped beam-to-column connections subjected to quasi-static cyclic loading was conducted to assess their ductility and energy dissipation capabilities. The specimens represent beams in ductile moment resisting frames undergoing alternating lateral loads. The aim of this study was to assess and compare the rotation capacity and energy absorption of locally web-stiffened beams with unstiffened beams. Of direct relevance to seismically designed moment resisting steel frames, the experimental results of this research clearly highlight the superiority of herring-bone style web-stiffened specimens over vertically web-stiffened or unstiffened specimens. Key words: earthquake, response, steel, moment resisting frames, stiffener, cyclic loading.
Effects of temperature and organic loading on the performance of upflow anaerobic sludge blanket reactors
Authors: Grant Shannon , Lin Kwan-Chow
Published: January 2010

A study investigating the effects of temperature and organic loading on the performance of upflow anaerobic sludge blanket reactors was carried out in the laboratory. Laboratory-scale reactors of 3.2 L volume were semicontinuously fed a synthetic substrate consisting of beef consommé and macro- and micro-nutrient compounds. Temperatures ranged from 10 to 42 °C; organic loadings ranged from 2.0 to 30 kg COD/(m3∙d). Steady-state process kinetics and efficiencies were evaluated for the various conditions. Based on the assumption that upflow anaerobic sludge blanket reactor kinetics in the temperature range of 10–30 °C could be approximated by Monod and modified Arrhenius equation relationships, effluent SCOD concentrations and removals were used to determine the maximum rate of substrate utilization, the half-velocity constant, and the temperature coefficient. A design and operating chart was constructed based on the kinetic coefficients determined from the experimental data. Key words: upflow anaerobic sludge blanket reactor, temperature, loading, performance, kinetics.
Shear – moment analysis of reinforced high strength concrete beams containing steel fibres
Authors: Imam Mahmoud , Vandewalle Lucie , Mortelmans Fernand
Published: January 2010

This paper concerns the incorporation of steel fibres in singly reinforced high strength concrete beams without stirrups failing under the combined effect of flexure and shear. A new equation for predicting the shear strength of reinforced high strength concrete beams is developed. This equation shows a good correlation with own test data of 16 reinforced high strength concrete beams with and without steel fibres and numerous published experimental data for beams with concrete compressive strength up to 140 MPa. The flexural capacity of reinforced high strength concrete beams is also investigated. The existing ACI method for predicting the flexural strength of steel fibre concrete composites is slightly modified to be applicable for high strength concrete. Based on the proposed equations, an analytical model is developed for predicting the relative flexural capacity, i.e., the ratio of the moment with shear interaction to the pure flexural moment. Key words: high strength concrete, steel fibre, shear strength, flexural strength, stirrups, web reinforcement.
Déversements turbulents de matériau granulaire en eau libre. I. Observations en laboratoire
Authors: Lavallée Daniel , Marche Claude
Published: January 2010

Capping of contaminated sediment with clean granular material is a commonly used mitigative measure. The capping material is often dispersed from the end of a pipeline or dumped down a chute. Such methods require special equipment that is sometimes costly. The possibility of using a hopper barge to place the material was thus explored. Laboratory tests were conducted to study bottom distribution of granular material placed in this way. Distribution is determined at the moment of impact. To identify the mechanisms at work at the moment of impact, tests were conducted with different bottom slopes. Experimental results indicate that distribution of the granular material can be described by the turbulence created by an impinging jet. This turbulence is estimated, using a digital model, the results described in a second paper. Key words: dredging, capping, seacoast.[Journal translation]
Estimation of right turn on red saturation flow rates
Authors: Stewart J. Allen , Hodgson Kirsten
Published: January 2010

It is common practice in most Canadian provinces to permit right turns on red at signalized intersections. At intersections with a high volume of pedestrian traffic, the opportunity to turn right on red may be critical to satisfy right turn demand. However, in order to properly time the traffic control signal display at a signalized intersection, the saturation flow rates for each lane or lane group of the intersection must be known. Six signalized intersections were studied in Kingston, Ontario, where saturation flow rates for right turns were measured as a function of conflicting through traffic. From these measurements, estimations of the gap size required for a right turn movement were made. A regression analysis resulted in the production of a simple equation for estimating right turn on red saturation flow rates. It was found that the gap acceptance behaviour of drivers varied both spatially and temporally. Key words: saturation flow rates, signalized intersections, capacity, gap acceptance.
A two-phase anaerobic digestion (UASB-UASB) process: design criteria and optimal system loading capacity
Authors: Fongsatitkul Prayoon , Mavinic Donald S. , Lo K. V.
Published: January 2010

This research evaluated the effectiveness and feasibility of two-phase (separation acid and methanogenic phases) anaerobic digestion of simulated sewage sludge using a UASB-UASB (upflow anaerobic sludge blanket) process. Predictive models of chemical oxygen demand (COD) (soluble) removal efficiency and CH4 gas production during loading maximization and the recovery (after failure) period were made. The optimum hydraulic retention time (HRT) for the A-UASB was about 1.0 d; for the M-UASB system, two different optimum HRTs were evident, depending on the operational mode. When the UASB-UASB system was run under the maximum loading possible, the best HRT in the M-UASB was about 2.0 d, to achieve high COD removal and concurrent optimum CH4 production; after deliberate overloading, to induce failure, and subsequent system recovery, the predicted optimum HRT in the methane unit was about 2.7 d, to achieve concurrent adequate CH4 production and COD removal. There also appeared to be a restructuring of the bacterial community inside the M-UASB, during the recovery period. For overall design purposes, optimum operating HRTs of 1 and 2 d, with an internal recycle rate of 1.6 and 2.5 times the influent flow rate, are recommended for A- and M-UASBs, respectively; a conservative organic loading rate of 19 kg COD (total)/(m3∙d) is suggested. Finally, the optimum HRTA-UASB/HRTM-UASB ratio was found to be about 0.63 and HRTA-UASB/HRTsystem was 0.38, which are within the boundaries of this research project. Key words: anaerobic sludge treatment, design criteria, optimum system loading capacity, two-phase anaerobic stabilization, upflow anaerobic sludge blanket.
Seismic design and analysis of masonry-infilled frames
Authors: Kodur V. K. R. , Erki M. A. , Quenneville J. H. P.
Published: January 2010

A simple analytical procedure, which can be used by practicing engineers, for the seismic design of masonry-infilled frames is presented. The analysis procedure, based on the experimental and analytical studies reported in the literature, accounts for the effect of infills in all three stages, namely, in computing seismic loading, in predicting response of the infilled frame, and in determining the strength of the infilled frame. Seismic loading is computed using the dynamic properties of the structure rather than arbitrary empirical relationships as recommended in design codes. Recommendations regarding the choice of infilled frame idealization, structural damping ratio, earthquake design spectrum, structural irregularity, and computational aids are made. Practical guidelines, which can be implemented during the construction phase and which have beneficial effects on the behaviour of infilled frames, are provided. Application of the proposed analytical procedure in a design situation is demonstrated through a numerical example, and it is shown that infills can be accounted for in the seismic design of frames during the normal course of design. Key words: masonry, infilled panels, frame behaviour, seismic design.