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Cryptococcus albidus , isolated from the sediments of Century Pulp and Paper Mill, Lalkuan, Nainital, Uttarakhand, India, produced a copper containing oxidase, laccase, that was capable of degrading environmental pollutants. Bagasse was the most efficient inducer for laccase production. The Taguchi approach was used to optimize the growth media for five factors, i.e., pH, copper sulphate, carbon, nitrogen, and the inducer at four levels using an M-16 orthogonal array. The optimum conditions for laccase production were pH (6), CuSO4(2 mmol/L), meat peptone (0.5%), glucose (0.1%), and bagasse (1.0%). After optimization, laccase production increased seven times from 32 to 219 IU/mg. The inducer (bagasse) had maximum effect on laccase production leading to 52% increase, while pH had minimum effect with 7% increase. Growth media with laccase activity (2 U/mL) was applied for the bioremediation of dyes, effluent, and chemical compounds. These experiments showed that the growth media with laccase activity (2 U/mL) produced by Cryptococcus albidus had good potential for bioremediation of toxic and recalcitrant compounds. Further, the laccase enzyme extracted from the growth media was fractionated by DEAE-cellulose ion-exchange chromatography, and the molecular weight of the enzyme determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE) was found to be 64 kDa. The activity of laccase was confirmed by native PAGE, in which ABTS was used for staining gel.

Construction projects are usually labour intensive, and human resource (HR) issues contribute significantly to a project’s final costs. From this perspective, a tool that can help construction managers reduce their HR costs can potentially generate improvement in the project cost. In this paper we propose a simulation-based approach that sheds light on the dynamics of workforce skill evolution as the project progresses, thereby assisting construction managers in adjusting their HR policies. The proposed approach uses a system dynamics (SD) simulation model that dynamically tracks the effects of alternative HR policies. After the development and validation of the SD model, the SD model is extended to capture operational details and their interaction with workforce skill evolution, adopting a hybrid SD and discrete event simulation (DES). The hybrid model has been applied to an experimental case of structural steel fabrication projects, in which we demonstrate that there is a considerable room for cost-saving in HR. The hybrid modeling approach introduced in this paper can be employed by construction managers for possible improvements in HR management, as well as researchers for an in-depth understanding of the dynamics in workforce skill evolution.

Contractor default is one of the major risks that threaten a project’s success in the construction industry. Previous studies have focused mainly on evaluation of the contractor’s financial aspects to predict contractor default. There remains a need for a comprehensive model that has the ability to incorporate the evaluation of all the project aspects, project team, contractual risks, and project management evaluation criteria to predict the possibility of a contractor’s default on a specific construction project. This paper presents a contractor default prediction model (CDPM) from the surety bonding perspective that incorporates these criteria and uses a fuzzy inference system for reasoning. The CDPM provides a more objective, structured, and comprehensive approach for contractor default prediction for surety practitioners, project owners, and for self-assessment by contractors to reduce the risk of contractor default. The multi-attribute utility function was used to develop a group consensus system (GCS) to aggregate the participating experts’ opinions to build the CDPM. The accuracy of the GCS was found to be 91.1%. A novel approach for fuzzy rule base development is applied to develop the rule base for the CDPM. The CDPM was validated using 30 contractor default prediction cases, and the accuracy was found to be 86.5%.

To improve construction productivity and performance, it must be measured. The Construction Sector Council (CSC) has started a Labour Productivity and Project Performance Benchmarking Program for the infrastructure sector of the construction industry in Canada. Metrics were developed for project cost, time, safety, and quality performance; labour productivity; rework; project conditions; and management practices related to health and safety. Data from 19 projects located in different regions of Canada were collected and analyzed. Based on the results and on industry feedback, additional metrics for practices related to project planning, materials management, and construction supervisory skills development were developed. This paper describes the development of the program. Lessons learned during the development and implementation of the benchmarking and metrics program are summarized and steps to establish a sustainable program are identified. It is concluded that a successful program is feasible and has the potential to have broad impact.

This paper presents a framework for optimizing condition assessment policies by balancing the revealed value of information with the cost of obtaining such information. The computational platform is based on augmenting the asset condition state with an expected level of accuracy. Inaccuracies due to condition assessment reliability are evaluated using the partially observable Markov decision process. The single objective genetic algorithm is used to select the most cost-effective assets to assess considering information inaccuracy under a fixed budget. The model is extended using multiobjective genetic algorithms and fuzzy set theory to include minimizing the risk exposure based on asset consequence of failure. This methodology takes into consideration direct and indirect costs of sudden infrastructure failure and reduced level of service costs. A case study is presented using the City of Hamilton, Canada, water network to demonstrate the capabilities of the model.

The factory-based modular construction process has proven to increase the speed of construction, and improve quality and safety, while providing value to the customer and a rapid return on investment to the builder and owner. However, onsite module assembly creates new schedule demands, as activities are scheduled on a minute-by-minute basis; therefore simulation of the process becomes essential at early stages of a project. Although simulation proves to be an effective tool for project engineers to assess complex construction operations, it remains a symbolic base model with no visual link to the actual physical shape and look of the project’s activities. This paper presents the application of integrated simulation and post simulation visualization as a tool to assist the modular construction industry in scheduling onsite installation of prefabricated modules. The proposed methodology uses simulation model output as an ASCII file in a binary format and imports this ASCII file to 3D Studio Max to perform the animation. The output from the high level simulation model is transformed into frames/second in 3D Studio Max. The proposed methodology was tested on the planned construction of a 34-storey building in Brooklyn, New York, USA. Simulation visualization of the process proved to be effective in communicating the value and simplicity of a minute-by-minute schedule. Based on the output information, the most efficient solutions were generated. The use of post simulation visualization was effective in analyzing the construction methods of the case study which consisted of 950 structural steel modules. Issues related to construction activities’ productivity were synchronized to achieve onsite installation of the project in only 56 working days.

This paper presents an automated method for estimating productivity of earthmoving operations in near-real-time. The developed method utilizes Global Positioning System (GPS) and Google Earth to extract the data needed to perform the estimation process. A GPS device is mounted on a hauling unit to capture the spatial data along designated hauling roads for the project. The variations in the captured cycle times were used to model the uncertainty associated with the operation involved. This was carried out by automated classification, data fitting, and computer simulation. The automated classification is applied through a spreadsheet application that classifies GPS data and identifies, accordingly, durations of different activities in each cycle using spatial coordinates and directions captured by GPS and recorded on its receiver. The data fitting was carried out using commercially available software to generate the probability distribution functions used in the simulation software “Extend V.6”. The simulation was utilized to balance the production of an excavator with that of the hauling units. A spreadsheet application was developed to perform the calculations. An example of an actual project was analyzed to demonstrate the use of the developed method and illustrates its essential features. The analyzed case study demonstrates how the proposed method can assist project managers in taking corrective actions based on the near-real-time actual data captured and processed to estimate productivity of the operations involved.

The critical path method (CPM) has been useful for project planning, yet its float calculation errors in cases of complex schedules hinders its ability to provide decision supports during project control, namely corrective actions and forensic analysis of schedules. To improve project control, this paper enhances the critical path segments (CPS) scheduling technique and incorporates a rich visualization of all as-built events made by all parties, including work stops, accelerations, and rework. Its improved critical path calculation incorporates the decision variables used at the project control stage such as revised construction methods. It also uses a modified float calculation with forward-pass only to avoid float errors. A case study is used to demonstrate the proposed technique and its benefits for project control. This research has the potential to revolutionize scheduling computations to resolve CPM drawbacks and provide decision support capabilities to help improve project planning and control.

Information exchange processes (referred to as transactions) in the AEC/FM (architecture, engineering, construction and facility management) industry are mostly manual and performed on an ad hoc basis. There is a growing trend towards computer-based exchange of information. This allows for more extensive, rapid, and error-free exchange of information, but it requires more formal specifications and agreements to govern these data exchanges. This research focuses on the development of an ontology-supported protocol for formalizing these data exchanges. As part of the development effort, this paper describes a taxonomy of transactions and messages. The knowledge represented in the ontology is evaluated and potential areas of application of the ontology are identified using an industry IT survey.

Although the current economic downturn has eased the stress of broad skilled labour shortages, it is reasonable to believe that the shortage will return when the U.S. economy rebounds. The shortage could become more substantial because the U.S. construction industry is poised to make a significant demographic shift with Baby Boomer workers approaching retirement and Generation Y workers joining the workforce. This paper investigates how different generations of craft workers perceive the factors affecting labour productivity. The data was collected through a survey of 1996 craft workers on 28 U.S. construction sites in 2004 and 2005. The analysis results reveal that: (1) Generation Y, Generation X, and Baby Boomers actually have consensus on the relative impact of productivity factors; and (2) significant differences were also observed on individual productivity factors and the primary differences among the generations were associated with tools and consumables, labour, engineering drawing management, and project policy.

Pipe-works are among the most complicated items to be tracked in the course of monitoring construction project progress. Traditionally, the tracking of pipe-works progress is conducted either manually or using laser scanning technology. While laser scanning is a 3D imaging technique, and commercial software exists to construct 3D CAD models of piping based on such images, it suffers from portability, purchase cost, and other disadvantages. This paper describes digital photogrammetry technology as an alternative for pipe-works reconstruction and as a cost effective tracking tool. For validation, data was collected using a handheld digital camera to acquire images inside a new building under construction. Progress of the pipe-work networks of different types and sizes in the new building was monitored during the construction phases. In addition to the known accuracy and robustness of photogrammetry, it was found that the use of digital photogrammetry provided a practical and low-cost approach.

During the past decade, significant research has been carried out on the strengthening of reinforced concrete (RC) slabs, beams, and columns using externally bonded carbon fibre reinforced polymer (CFRP) sheets. Steel reinforced polymer (SRP) sheets have recently been proposed as an alternative to CFRP to strengthen reinforced concrete beams. This paper reports experimental and numerical results of RC beams and beam-columns transversely wrapped with SRP and tested under blast load. A total of 10 scaled RC members were tested at a variety of blast wave intensities. Detailed observations are reported and validated against numerical models created in AUTODYN for the unstrengthened RC members. The SRP wraps were resilient in the near-field blast range and enhanced the ductility of the concrete likely through enhanced confinement. Member capacity could be increased by the wraps in failure modes dominated by concrete crushing. AUTODYN appears able to reasonably predict the behaviour of the RC members when loaded by blast.

There are many computational techniques to model the consequences to built infrastructure when subject to explosive blast loads; however, the majority of these do not account for the uncertainties associated with system response or blast loading. This paper describes a new computational model, called “Blast-RF” (Blast Risks for Facades), that incorporates existing (deterministic) blast-response models within an environment that considers threat and (or) vulnerability uncertainties and variability using probability and structural reliability theory. The structural reliability analysis uses stress limit states and the UK Glazing Hazard Guide's rating criteria to calculate probabilities of glazing damage and occupant safety hazards conditional on a given blast scenario. This allows the prediction of likelihood and extent of damage and (or) casualties, useful information for risk mitigation considerations, emergency service's contingency and response planning, collateral damage estimation, weaponeering, and post-blast forensic analysis.

The state-of-the-art tracking technologies, such as the global positioning system (GPS) and the radio frequency identification (RFID), lend themselves well to applications in relatively open areas, while falling short of accuracy and reliability in indoor or partially covered application settings due to signal blockage, distortion or deterioration. This research aims to address this challenge in construction engineering by exploring a cost-effective positioning methodology to realize automated and continuous tracking of construction resources. The emerging ZigBee-based wireless sensor networks (WSN) technology is introduced. A framework of WSN application is proposed for indoor construction resources tracking, which consists of a group of stationary and mobile sensor nodes that can communicate with one another. Real-time locations of the mobile nodes can be determined by applying the localization method based on received signal strength indicator (RSSI) and geometric trilateration.

Efforts to break down decision-making silos in the architecture, engineering, and construction (AEC) industry have resulted in the evolution of integrated project delivery (IPD). IPD brings together participants to make decisions early in the project cycle. But, anecdotal evidence indicates that IPD is not being implemented as effectively as envisioned. One potential barrier to implementation is the multi-party risk and reward agreement that is a hallmark of IPD. Many owners may be statutorily prohibited from entering into such a risk-sharing contractual arrangement, and countless other organizations “remain skeptical of its practicality.” However, recent case study research established an important link between reimbursable contracting strategies and greater collaboration and information-sharing among parties. The researchers found that more traditional contracting approaches, when combined with a cost reimbursable compensation structure, achieved positive outcomes by properly allocating risk, fostering teamwork, and bringing together diverse experts to address challenging design problems, thus providing a viable alternative to shared risk and reward approaches.

In this paper, we discuss issues in verification, validation, and uncertainty prediction in computational fluid dynamics (CFD). Mesh adaptation is used to perform the systematic grid refinement studies required for code and simulation verification. We demonstrate the method of manufactured solutions (MMS) for code verification. Examples of successful and failed validation show that reliable prediction can only occur with an appropriate mathematical model of physics along with accurate numerical solution of the differential equations. The paper emphasizes good CFD practices to achieve systematic verification and put validation studies on solid grounds. Finally, the sensitivity equation method (SEM) is used to cascade input data uncertainty through the CFD code for estimating the uncertainty of the flow response.

The size of the largest horizontal coherent structures (HCSs) of turbulence in open-channel flows is investigated experimentally on the basis of three series of flow velocity measurements. These are further used to explore the dynamics and morphological consequences of HCSs. The flow velocity measurements were carried out in a 21 m long and 1 m wide channel, with a bed formed by sand with average grain size of 2 mm. The bed surface was flat. The turbulent and subcritical flow under investigation was uniform, with a flow depth of 4 cm. The bed slope of 0.0015 was such that, for the present flow depth, the bed shear stress acting on the bed was substantially below the threshold for initiation of motion, thus ensuring that the bed remained flat throughout the measurements. To the knowledge of the writers, this work is a first attempt to systematically investigate HCSs in open-channel flows. It should be viewed as an extension to the case of horizontal structures of work previously carried out by a number of authors on large-scale organized turbulence motion in open-channel flows, so far focusing exclusively on vertical coherent structures (VCSs). The horizontal burst length was found to be between five and seven times the flow width. A slight internal meandering of the flow caused by the superimposition of burst sequences on the mean flow was detectable. Both of these findings lend support to the longstanding belief expressed by many prominent researchers that the formation of large-scale river forms is directly related to the large-scale turbulence. In particular, the present measurements for the first time provide some direct evidence in support of hypotheses previously raised by Yalin and da Silva regarding the formation of alternate bars and meanders through the action of HCSs on the mean flow and the mobile bed and banks.

Masonry component products are increasingly made industrially with reduced variation in mechanical properties. The joint is the only part of the masonry that is affected by manual action and so the load bearing capacity is not only determined by the quality of the bricks and mortar used but moreover by the way the masonry has been built and cured. As a result, it may be expected that the largest material variations are at the brick–mortar interfaces. This has been observed as irregular interface bonding with a bonded central area surrounded by fissures. As a consequence of the final shape of the joint, forces concentrate in the central part of the joint and strain variations occur near fissure tips which result in spalling of bricks in experiments. This paper demonstrates the need for detailed deformational measurements in the brick–mortar interface region. To overcome the limitations with traditional measuring instruments, a refined methodology based on the laser speckle technique is introduced in a companion paper [Canadian Journal of Civil Engineering, 34(11), 1467 (2007)] by the authors of this paper.

The brick–mortar interaction is important in the mechanical behaviour of masonry. It affects the load transfer considerably, as shown by detailed deformation measurements taken using electronic speckle pattern interferometry (ESPI), a laser speckle interference technique. A companion paper [Canadian Journal of Civil Engineering, 34(11), 1475 (2007)] by the authors of this paper argues that the joint is the only part of contemporary masonry significantly affected by manual action, which is why large material variations appear at the brick–mortar interface. To evaluate this phenomenon, ESPI measurements were performed and compared with accompanying linear variable differential transformer (LVDT) results. The behaviour of specimens loaded with various eccentricities was relatively soft in the brick–mortar interface area when compared with the behaviour shown in the surrounding stiff brick and mortar. The brick–mortar interface was characterized by a central part surrounded by fissures. Most of the load was transmitted in the central part. Because of this, the axial strain curve over the width of the specimens was U-shaped for concentrically loaded specimens (i.e., those with zero eccentricity). Over the height of the two-brick one-joint specimen, a smooth, B-shaped lateral strain curve was observed, in which the largest strains were found in the bricks.

Finished compost should be both stable (resistant to decomposition) and mature (ready for a particular end-use) so that it can safely be packaged and transported, and not cause adverse effects during its end use. A variety of methods for evaluating stability and maturity are available; this paper contains a review of the effectiveness of a number of the most commonly used tests, to determine the most reliable approach(es). In the literature reviewed, it was generally agreed that a single, stand-alone test for both compost stability and maturity does not yet exist; therefore, it is best to use a combination of tests. However, there is disagreement in the literature as to what the best combination for evaluation should be, and guidelines and regulations around the world employ a variety of approaches.

This paper gives an overview of the most important bioreactor configurations used in waste gas treatment, i.e., conventional and trickling biofilters, the bioscrubber, suspended-growth bioreactors, as well as two-liquid phase systems (stirred tank bioreactor and biotrickling filter). The historical evolution, main characteristics, and recent developments are described in each case.

In Canada, the piggery industry is an essential part of the agricultural sector, but the main waste product of this industry, swine slurry, is particularly harmful to the environment. The anaerobic storage conditions and the excessive use of slurry for agricultural fertilization contribute, respectively, to the emission of greenhouse gases and to aquatic pollution. This paper provides a review of these environmental concerns and of the existing mitigation technologies. Water pollution from swine slurry is associated with the nutrients it contains, such as nitrogen and phosphorous, while the main greenhouse gases produced by the piggery industry are methane and nitrous oxide. Available technologies can valorize the slurry through agricultural fertilization, reduce greenhouse gas emissions, by limiting nutrient availability for example, or treat the effluents using solid–liquid separation, flaring or biological processes. Specific attention is paid to biofiltration due to its potential to simultaneously treat these two types of pollution.

As a young, new, and rapidly growing science, the applications of ultrasound in environmental technology hold a promising future. Compared with conventional methods, ultrasonication can bring several benefits such as environmentally friendly (no toxic chemicals are used or produced), low cost, and compact (allowing on-site treatment). Beside an overview on ultrasonic background, this paper summarizes main findings and innovations of recent studies that used ultrasound in environmental analysis, water and sludge treatment, soil and sediment remediation, and air purification.

Because of changes in functional or security requirements, many new or existing buildings are now required to resist blast loads. New buildings can be designed and constructed to resist defined blast loads. Existing buildings, on the other hand, would have to rely on a risk assessment to determine both its vulnerability to blast effects and the necessary measures to mitigate the unacceptable blast effects. A rapid screening methodology has been developed for conducting a preliminary assessment of buildings against external blast effects. The methodology accounts for the threat, the vulnerability of the building, the consequence of an event and the risk, which is the product of the threat and the consequence. The rapid screening methodology has been applied to several buildings and the results are reasonable. This paper presents the rapid screening methodology and its application to two federal buildings in Canada.

This study critically discusses the fundamental concepts used for evaluating the flexural and axial resistance of structures under blast. Simplified methods based on single degree of freedom are emphasized. The paper begins with how to estimate the blast parameters for a given charge size and standoff distance. These parameters include side-on and reflected pressures, positive phase duration, and side-on and reflected impulses. Subsequently, blast damage criteria are defined in accordance with prevailing guidelines and some of their short comings are discussed. To assess the impact of blast on the flexural safety and performance of structures, some simple methods are presented. The methods are either empirical or are based on the principles of energy and momentum conservation. The analytical results are in closed-form or in the form of pressure–impulse (P–I) diagrams. The effect of strain rate on both blast-induced flexural deflection and strength of structures, with particular emphasis on reinforced concrete structures, is discussed.

Designers charged to develop blast-resistant structural designs must be able to address the technical aspects of the explosion process and provide structural components with sufficient strength and ductility to resist the applied pressures. The blast environment is different from those of other loads with which designers deal, and uncertainties about the actual response of structures often are higher. For these reasons, designers often have less confidence in their abilities to explain to their clients their expectations about the actual response of the building to a blast event. This paper identifies some elements of the conventional design process that do not translate directly to blast-resistant design, reasons why uncertainties in performance expectations differ from those encountered with other load sources, and the need to understand and acknowledge residual risks for the facade, the structure, and the safety of the occupants of blast resistant buildings.

Membrane processes have become a competitive option to conventional treatment technologies because of the high quality of the product water. In particular, nanofiltration and reverse osmosis have been found to remove materials like natural organic matter, disinfection by-products, and endocrine-disrupting compounds. However, an issue identified as one of the major drawbacks for the adoption of pressure-driven membrane processes is the need for additional treatment of the concentrate stream. Few studies dealing with membrane concentrate treatment have been published. The majority of the published studies address the disposal of concentrate into receiving waters bodies and sewer systems. In this review paper, the characteristics of membrane concentrate in terms of water quality and their impact on receiving water bodies are discussed. In addition, several approaches to the removal of pollutants and disposal options for membrane concentrates are examined.

If natural windbreaks create air turbulence and can help disperse odours from livestock operations, their dispersion effect has not been extensively researched. This paper introduces a model simulating odour dispersion downwind from natural windbreaks. The standard k-ε model of the FLUENT software was used to incorporate the effect of climatic conditions and windbreak structure. The model was calibrated for wind velocity recovery, odour concentration (OC) from field observations and inertial resistance. Once calibrated, the model accurately reproduced the odour plume developing downwind from the windbreak. The correlation between OC for 11 field trials and that simulated were statistically significant (P < 0.01), indicating that the model was accurate. The model demonstrated that a windbreak did alter the magnitude and direction of the wind velocity, thus creating a pressure jump across its width. This pressure jump produces a strong downwind turbulence forming a mixing layer capable of enhancing odour dispersion.

A commercially available 3-D computational fluid dynamics (CFD) model (STAR-CD) was used to investigate capacity upgrading options for a combined sewer overflow (CSO) facility of inadequate capacity. The numerical model was verified against the data collected in two physical models. The need for verifying the CFD model was given by the complexity of the CSO facility, which comprises several interconnected tanks. The verified numerical model was then applied to analyze hydraulic conditions in the whole facility for major structural modifications with the aim of reducing or eliminating untreated overflows from the facility. Many scenarios were proposed and tested in the study and the two most promising structural modifications, scenarios 1 and 2, are presented in the paper. Both appeared to meet the design condition of increasing the facility capacity to 60 m3/s, but better performing scenario 1 would be significantly more costly to implement than scenario 2. Even though the study focused on a particular CSO facility, hydraulic conditions in the studied facility represent general flow conditions in typical CSO or stormwater settling facilities and, therefore, the numerical modeling methods used are applicable to solving a wide range of hydraulic problems encountered at similar facilities.

A simple alternative equation for the calculation of the strength of laterally unbraced structural steel beams is presented herein. This equation uses a format similar to the present steel column design curve in the Canadian structural steel design standard, CAN/CSA-S16-09, and is proposed as a replacement for the existing three part curve for beam strength by a one part equation with a continuous derivative. A reliability analysis of the new equation indicates that the equation provides safety levels very close to those of the current formula for classes 1 and 2 rolled sections. It also provides the desired level of safety for welded beams, whereas the current equations tend to over-estimate their strength. The alternative equation also provides adequate safety for class 3 beams. The concept of maximum unbraced length for braced beam design (Lu) is revisited herein and a simple calculation for this length is also proposed.

Post-tensioned concrete masonry walls provide improved seismic performance, but have had limited application in seismic regions because of a lack of research pertaining to their in-plane response. Following focused research over recent years, a consortium of product suppliers has collaborated with the University of Auckland to construct New Zealand’s first post-tensioned concrete masonry house. A feature of this innovative design was that all incorporated products were commercially available, with no proprietary products being specifically developed for the prestressed masonry system used. Consequently, it is hoped that this house will be a showcase, and provide exposure for the technology in New Zealand and elsewhere. This paper provides a brief review of previous post-tensioned concrete masonry research applications, then discusses post-tensioning details and their application to house design and construction.

The issue regarding the corrosion of steel ties connecting brick veneer to its structural backing is well known and well documented. However, none of the research to date has developed field-calibrated corrosion rate and service life models specific to wall ties in brick veneer steel stud (BVSS) wall systems. In this paper, corrosion rate and service life estimates produced by two models generated by the International Organization for Standardization (ISO) were compared with the empirically determined corrosion rates (CRs) and service lives of nine zinc galvanized tie specimens inspected at five buildings in four different Canadian cities. The best estimate, obtained using actual environmental data, was found to be the ISOCORRAG formula. However, the maximum difference between predicted and actual service life was still significant, indicating that a better understanding of the mechanics governing the corrosion of a tie embedded in mortar is still needed.

The mechanics of masonry structures have been underdeveloped for a long time in comparison with other fields of knowledge. Presently, nonlinear analysis is a popular field in masonry research and homogenization techniques play a major role despite the mathematical and conceptual difficulties inherent to this approach. This paper addresses different homogenization techniques available in published literature, aiming at defining a first catalogue and at discussing the advantages and disadvantages of the different approaches. Finally, special attention is given to a micromechanical based model and a model based on a polynomial expansion of the microstress field. These seem promising and accurate strategies for advanced structural analysis.

A horizontal subsurface flow constructed wetland (HSSFCW) was employed to remove tannins from the effluent of a tannins extracting company. Two HSSFCW cells with hydraulic retention time (HRT) of 9 d and packed with limestone were used. One cell without macrophytes was used as a control, while the second cell was planted with Phragmites mauritianus . Results indicated that HSSFCW was capable of treating tannin wastewater that has been seeded with primary facultative pond sludge. Tannins and chemical oxygen demand (COD) removal efficiency of 95.9% and 90.6% with outlet concentration of 27 mg/L and 86 mg/L, respectively, were obtained in the planted cell; while the tannins and COD removal efficiency of 91.1% and 89.5% with outlet concentration of 57 mg/L and 96 mg/L, respectively, were obtained in the control cell.

Air quality in workplaces is a main concern for industrial hygienists and occupational health specialists. Aerosolization of microorganisms or their by-products from contaminated material can significantly decrease the air quality and expose the workers’ health to potentially harmful effects. To identify the risks and elaborate safe exposure thresholds, the microbiology of air samples from industrial workplaces must be characterized, which means the airborne microorganisms must be identified and quantified. This review summarizes, for nonbiologist specialists, the principal sampling and analysis techniques for air sample characterization regarding microbiological contamination. A survey of the literature regarding levels of airborne bacteria, fungi, and viruses in agricultural industries, waste management plants, peat and wood processing facilities, and other industries is also provided. This review shows that very complex bioaerosol sources are present in industrial settings, and variable and hardly predictable biodiversity is expected in such environments.

A two-dimensional model was developed in this study. The model predicts the performance of a full-scale aerated grit chamber for grit removal from wastewater. The model numerically integrates Poisson’s equation, which describes the motion of the liquid induced by the rising air bubbles. The model makes use of finite element algorithms available in Mathcad to solve Poisson’s equation. The model was developed for predicting the velocity field in the chamber. The model was used to perform a sensitivity analysis of the design variables that affect the performance of an existing grit chamber at the Moose Jaw Wastewater Treatment Plant. The results of the sensitivity analysis indicate that predictions of velocity field are highly sensitive to energy transfer efficiency, air flowrate, and particle settling velocity but less sensitive to variations of wastewater flowrate, diffuser depth, and grid spacing.

Accurate analysis of reinforced concrete (RC) structures under blast loading is very complicated due to the nonlinear behaviour of concrete and reinforcement and the various failure modes to be considered. Although blast loads can excite a large number of modes due to their high frequency content, practical computational tools are usually limited to single-degree-of-freedom (SDOF) models. In addition to oversimplification, SDOF models are known to give inaccurate prediction for shear forces and support reactions. This is because accurate shear force prediction typically requires accounting for modes higher than the fundamental mode. In this study, a multi-degree-of-freedom (MDOF) model is developed that takes into account the nonlinear behaviour of RC structures and the material strength and deformation dependency on the strain rate. Using this model, a series of dynamic analyses were carried out for two typical structural members, with different combination of blast pressure and impulse. The effect of varying the number of degrees of freedom (DOF) was investigated through increasing the number of nodes used to descretize each structural member. The results of the developed MDOF model were compared to the results of available SDOF models which demonstrated the deficiencies of the latter. The developed MDOF model, with few DOF, was found to be capable of accurately predicting the dynamic shear of the modeled structural members. The model was also compared to available experimental results and showed good agreement. Changing the number of DOF also affected the pressure–impulse (P–I) diagrams for the structural member significantly, especially in the impulsive regime.

The blast response and ultimate resistance of reinforced concrete slabs externally strengthened with carbon fibre reinforced polymer (CFRP) laminates were investigated. Five square slab specimens, 1 m on a side, were retrofitted with 500 mm wide CFRP laminates bonded to their top and bottom surfaces. Another four nominally identical unretrofitted slabs were used as control specimens. Four of the retrofitted and the four control slabs were first subjected to the detonation of either 22.4 or 33.4 kg of explosive at a stand-off distance of 3.0 m. For reference, the fifth retrofitted slab was only statically tested to failure. Blast pressures and impulses and slab deformations were measured. After exposure to the blast, the slabs that were not completely damaged were statically tested to failure. Overall the retrofitted slabs performed better than the control slabs, but one retrofitted slab completely failed under the blast load while none of the control slabs experienced complete failure under similar load.

Recent bomb attacks on buildings have raised awareness about the vulnerability of structures to blast effects. The resiliency of structures against blast-induced impulsive loads is affected by structural characteristics that are also important for seismic resistance. Deformability and continuity of structural elements, strength, stiffness, and stability of the structural framing system and resistance to progressive collapse are factors that play important roles on the survivability of buildings under both blast and seismic loads. The significance of these structural parameters on blast resistance of reinforced concrete buildings is assessed through structural analysis. Both local element performance and global structural response are considered while also assessing the progressive collapse potential. The buildings under investigation include 10-storey moment resisting frames with or without shear walls. The blast loads selected consist of different charge-weight and standoff distance combinations. The results are presented in terms of ductility and drift demands. They indicate improved performance of seismic-resistant buildings when subjected to blast loads, in terms of local column performance, overall structural response, and progressive collapse potential.

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 Gruvön 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.

Inspired by an analogy to AM radio signals, amplitude modulation (AM) is proposed here as a useful view of nonstationary environmental periodicities, and applied to hydrologic and air quality datasets. Both example time series considered exhibit seasonally evolving diel cycles, with large (small) daily cycle amplitudes in summer (winter). The carrier wave is taken to be a sinusoidal daily cycle; this is multiplied by an information signal consisting of a sinusoidal annual cycle, forming an envelope to the diel variations. Our results suggest that amplitude modulation may offer a novel, compact, and accessible perspective, both qualitatively and quantitatively, on the net phenomenological behaviour arising from highly complex, nonlinear, and diverse environmental process dynamics. Physical interpretations, synergies with common environmental time series processing or analysis methods (Kolmogorov-Zurbenko filtering, classical spectral analysis, and singular systems analysis), and potential future research directions are also explored.

A fuzzy logic model was developed to simulate the effect of leachate recirculation and sludge addition on the biogas generation in anaerobic bioreactor landfills. The model was designed using a fuzzy logic system (FLS) which incorporated 3 input variables (time, leachate recirculation, and sludge addition) and a single manipulated output (biogas generation rate). The biogas production rate was measured during the experiment and was increasing proportionally with the rate of both leachate recirculation and sludge addition. The experimental work involved the operation of six simulated laboratory-scale bioreactors for over a year under different operating schemes. The experimental results were employed in formulating the fuzzy rule base, calibrating the model, and verifying its predictions. Then, the model was validated against other measured data that was compiled from published studies. The FLS model simulations demonstrated high correlation with the experimental observations.

Humic substances (HS) can be isolated in preparative quantities from low rank coal, peat, and soil. Traditionally, treatment with solutions of NaOH, KOH, or metal salts (K4P2O7) has been used for their isolation. The aim of this article is to study the effectiveness of different technologies in extracting HS from peat as well as the impact of the different extractive technologies on the properties of the isolated HS. Yields of HS depend very much on the extraction process (extractant, temperature, pretreatment procedures, solvent, mixing intensity); however, the properties of the substances obtained (molecular mass, number of functional groups, spectral characteristics) differ significantly. Yields of HS can be associated with the degree of destruction of the peat fibres and intensive destruction technologies provide opportunities to obtain HS from peat in higher yields than traditional extraction methods. However, during the extraction process, significant degradation of the humic molecules takes place.

In the present study, masonry creep was experimentally investigated. Creep tests were performed on masonry prisms, which were produced using standard fired clay brick and standard Type S mortar. A total of 11 sets of loaded and unloaded masonry specimens were tested under sustained load with three main parameters: stress level, masonry age at loading, and relative humidity. The unloaded prisms compensated for the effects of shrinkage. In this article, the ability of a number of rheological models reported in the literature are examined for their ability to predict masonry creep. Moreover, a new rheological model, one that considers the effect of stress level and masonry age at loading, is proposed. The system parameters of the proposed model were identified using the experimental data. The proposed model was then validated using masonry creep data that was reported by other researchers, but not used in model development. It is shown that the creep behaviour of masonry can be modelled with good accuracy using the proposed rheological model.

The optimization of the production of fired clay brick is essential for the sustainability of the clay brick industry. While there exist areas for improvement of these bricks’ properties when they are used in severe climates, concerns — including nonrenewable resource depletion, increasing energy costs, and waste management — have become increasingly important in Canadian and global industries. One strategy to address these concerns is to use waste additives as fluxing agents in bricks. Use of these additives can decrease the dependency of the industry on nonrenewable resources and can improve brick strength and durability. The effect nonrecycled waste glass additives have on fired brick durability and mechanical and transport properties was investigated in this study. The variables studied were waste glass particle size and percentage added by mass. Microstructure was investigated using mercury intrusion porosimetry to determine the effect on pore structure. The results yielded an optimal percentage addition of waste glass.

Performance of dry-cast concrete masonry products (DCCMPs), which are becoming the product of choice for many applications, has yet to be assessed in a comprehensive manner. This study was undertaken to investigate the effects of mix design and manufacturing parameters on the mechanical and transport properties, as well as the freeze–thaw (F/T) durabilities, of DCCMPs. The variables studied were water to cement ratio, mixing time, vibration time, and curing regime. Freeze–thaw durability was assessed in accordance with the American Society for Testing and Materials (ASTM) standard C1262 by exposing specimens to four conditions: water, 3% NaCl, 4% CaCl2, and 4% MgCl2 solutions. Results revealed that 3% NaCl exposure yielded the most mass loss due to scaling, whereas 4% MgCl2 exposure exhibited the least. Increase in either water content, vibration time, mixing time, or use of moist curing led to improvement in the mechanical properties, refinement of large pores in the range of 40 to 400 μm, reduction of total porosity, and enhancement of F/T durability of capstones. Ionic sorptivity yielded a strong statistical correlation with mass loss due to F/T action in the presence of 3% NaCl and 4% CaCl2.

Twelve reinforced masonry wall specimens with nominal dimensions of 2400 mm × 800 mm × 150 mm were tested under eccentric compressive loading with varying eccentricity to thickness ratios, e/t, and end eccentricity ratios, e1/e2. Pinned-pinned support conditions resulted in a slenderness ratio of 17.1 for all specimens. Test results showed that the variation of ultimate load, Pu, and effective modulus of rigidity values, EIeff, at failure depended on the type of failure mode, which was influenced by e/t and e1/e2ratios and their interaction. Comparing ultimate loads obtained by test against those calculated using the EIeffvalues from the Canadian standard CSA S304.1-04 and against the ones calculated using the EIeffvalues proposed herein indicates that, while the moment magnifier method used in the current Canadian design standard to account for secondary effects is effective, the standard underestimates EIeffvalues, especially in regions where compression-controlled failure tends to predominate and, thus, leads to a conservative design. However, the use of proposed EIeffvalues in combination with the moment magnifier method provides estimations of ultimate loads in reasonably good agreement with test results.

The results of lateral resistance tests of masonry walls and shaking table tests of a number of models of masonry buildings of various structural configurations, built with various materials in different construction systems, have been analyzed to find a correlation between the occurrence of different grades of damage to structural elements, characteristic limit states, and lateral displacement capacity. On the basis of correlation between acceptable level of damage and displacement capacity, it has been shown that the range of elastic force reduction factor values used to determine the design seismic loads for different masonry construction systems proposed by the recently adopted European standard Eurocode 8 EN-1998-1 for earthquake resistant design are adequate. By using the recommended design values, satisfactory performance of the masonry buildings that have been analyzed may be expected when subjected to design intensity earthquakes with respect to both the no-collapse and damage-limitation requirements.

Strengthening masonry columns by spraying them with glass fibre reinforced polymer (GFRP) was investigated experimentally. The study was aimed at assessing the strength and strain increases imparted by the technique under both concentric and eccentric axial loading. Plain and steel-reinforced columns were tested. Twenty-four columns were constructed from Type S mortar and straight and bullnose clay masonry units. The columns were 1 m high and either 290 mm × 290 mm or 390 mm × 390 mm in cross section. Two thicknesses of sprayed GFRP (SGFRP) were attempted, but it was found to be difficult to maintain uniform thickness. Nevertheless, with only minor increases in strength, large increases in strain capacity were achieved with both the plain and reinforced columns under concentric axial compression. Eccentric loading reduced the effect of the SGFRP laminate on the strength of masonry columns. Failure of SGFRP included both mode I and mode III fractures.

Given sufficient anchorage to the diaphragms, out-of-plane walls in unreinforced masonry (URM) buildings have been shown to crack above midheight and then rock as two rigid bodies. This study investigates the sensitivity of the rocking response to the type of ground motion and the quality of the wall construction. Shake table tests were conducted on four full-scale multi-wythe walls, all with a height to thickness (h/t) ratio of 12 but of varying construction quality and subjected to three different ground motions. All walls experienced cracking at less than one half of the 2005 National Building Code of Canada (NBCC) level for Vancouver, but exhibited a stable rocking behaviour without collapse beyond a ground motion 1.5 times the 2005 NBCC level.