bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental and Simulation Studies of Sequestration of Supercritical Carbon Dioxide in Depleted Gas Reservoirs
Authors: Seo Jeong G. , Mamora Daulat D.
Published: March 2005

This paper presents experimental and simulation studies to evaluate the feasibility of sequestering supercritical CO2 in depleted gas reservoirs. Experimental results were simulated to obtain gas-liquid relative permeability curves used in the field simulation study. A 3D simulation model of one-eighth of a five-spot pattern was constructed to evaluate injection of supercritical CO2 under typical field conditions.
Formulations for the Thermodynamic Properties of Pure Substances
Authors: Adebiyi George A.
Published: March 2005

This article presents a procedure for formulation for the thermodynamic properties of pure substances using two primary sets of data, namely, the pvT data and the specific heat data, such as the constant-pressure specific heat cp as a function of pressure and temperature. The method makes use of a linkage, on the basis of the laws of thermodynamics, between the virial coefficients for the pvT data correlation and those for the corresponding specific heat data correlation for the substance. The resulting equations of state take on remarkably simple analytic forms that give accurate predictions over the range of input data employed.
Biomass Feed System Flow Control Using a Weigh Belt Table
Authors: Maxwell T. T. , Nevill Joe D. , Ertas A. , Craig Joe
Published: March 2005

Over the last 100 years, the ability to reliably extract energy through biomass gasification has proven to be quite elusive. Environmental issues, energy shortages, and the lack of coherent energy development policies in third world countries have kindled a renewed interest in biomass gasification technology. Recent innovations in pressurized fluidized bed gasification technology have raised expectations for the development of highly efficient biomass gasification power systems. The use of pressurized gasification systems has introduced a supposedly insurmountable problem regarding the transport of biomass across a pressure differential as it is fed to the gasifier. The biomass feed system must provide the capability to not only reliably feed the biomass to the gasifier, it must also monitor and automatically adjust the feed rate to the operating condition of the system. This paper presents the development of a biomass feed system, weight belt assembly modeling, and automated cascade loop PID control development.
On the Figure of Merit of Thermoelectric Generators
Authors: Chen Min , Lu Shan-Shan , Liao Bo
Published: March 2005

In order to improve the performance of semiconductor thermoelectric power generators, a high figure of merit Z of both material and generator system has been a target for a long time. In this technical brief, it is demonstrated that a higher value of Z does not always guarantee better generating performances because of the thermoelectric-coupled effect in the generators. Based on a coupled analytical thermal model and a set of performance formulas with considerations of heat transfer irreversibility, numerical simulation examples are provided to support the analysis, by which some important relations between design parameters and performance parameters are described.
Thermoeconomic Diagnosis: Zooming Strategy Applied to Highly Complex Energy Systems. Part 2: On the Choice of the Productive Structure*
Authors: Verda Vittorio , Serra Luis , Valero Antonio
Published: March 2005

The thermoeconomic diagnosis strategy introduced in the accompanying paper [Verda, V., Serra, L., Valero, A. 2004. Thermoeconomic Diagnosis: Zooming Strategy Applied to Highly Complex Energy Systems. Part 1: Detection and Localization of Anomalies. Part 1: The diagnosis procedure. ASME J. Energy Resour. Technol. 127(1), pp. 42–49. This issue.] is a zooming technique consisting of a successive localization of anomalies. At each step the required productive structure to be adopted becomes even more detailed, focusing the analysis on a more specific part of the system. The detail of a productive structure has two different levels: the number of components and the number of productive flows. The first one is selected according to the precision desired in locating the anomalies. A larger number of components (or subsystems) allows one to locate the anomalies in smaller control volumes, providing more precise indications for maintenance. The number of flows is partially dependent on the number of components. Once the number of components is fixed, the productive flows can be increased by separating exergy into its components or introducing fictitious flows, such as negentropy [see, for example, C. A. Frangopoulos, Energy, The International Journal 12(7), pp. 563–571 (1987)]. This decision also affects the results of the thermoeconomic analysis when it is adopted for diagnosis purposes. In this paper, the effects of the productive structure on the diagnosis results are carefully analyzed. Depending on the selected productive structure, the accuracy of the diagnosis results can be significantly improved.
Computation of Chemical Exergy Potential in an Industrial AC Electric ARC Furnace
Authors: C¸amdali U¨nal , Tunc¸ Murat
Published: March 2005

Chemical exergy is equal to the maximum amount of work obtainable when the substance is brought from the environmental state to the dead state by a process involving heat transfer and exchange of substances only with the environment. As it is well known the iron and steel industry is the largest industrial energy consumer. After the employee costs, energy costs (about 30% of the total) represent the second highest cost element in integrated steel works. In this study, the chemical exergy potential in an electric arc furnace (EAF) is calculated and these potentials are distributed depending on production materials, emphasizing the chemical exergy concept.
Image reconstruction in peripheral and central regions‐of‐interest and data redundancy
Authors: Pan Xiaochuan , Zou Yu , Xia Dan
Published: March 2005

Algorithms have been developed for image reconstruction within a region‐of‐interest (ROI) from fan‐beam data less than that required for reconstructing the entire image. However, these algorithms do not admit truncated data. In this work, we investigate exact ROI‐image reconstruction from fan‐beam data containing truncations by use of the so‐called fan‐beam backprojection‐filtration (BPF) algorithm. We also generalize the fan‐beam BPF algorithm to exploit redundant information inherent in the truncated fan‐beam data. Because the parallel‐beam scan can be interpreted as a special case of the fan‐beam scan, based upon the fan‐beam BPF algorithm, we derive a parallel‐beam BPF algorithm for exactly reconstructing ROI images from truncated parallel‐beam data. Furthermore, we investigate image reconstruction within two types of distinctive ROIs, which are referred to as the peripheral and central ROIs, respectively, from fan‐beam data containing truncations and discuss their potential clinical applications. The results can readily be generalized to reconstructing 3D ROI images from data acquired in circular and helical cone‐beam scan. They can also be extended to address ROI‐image‐reconstruction problems in parallel‐, fan‐, and cone‐beam scans with general trajectories. The work not only has significant implications for clinical and animal‐imaging applications of CT, but also may find applications in other imaging modalities.
Comparison of inhomogeneity correction algorithms in small photon fields
Authors: Jones Andrew O. , Das Indra J.
Published: March 2005

Algorithms such as convolution superposition, Batho, and equivalent pathlength which were originally developed and validated for conventional treatments under conditions of electronic equilibrium using relatively large fields greater than are routinely employed for inhomogeneity corrections. Modern day treatments using intensity modulated radiation therapy employ small beamlets characterized by the resolution of the multileaf collimator. These beamlets, in general, do not provide electronic equilibrium even in a homogeneous medium, and these effects are exaggerated in media with inhomogenieties. Monte Carlo simulations are becoming a tool of choice in understanding the dosimetry of small photon fields as they encounter low density media. In this study, depth dose data from the Monte Carlo simulations are compared to the results of the convolution superposition, Batho, and equivalent pathlength algorithms. The central axis dose within the low‐density inhomogeneity as calculated by Monte Carlo simulation and convolution superposition decreases for small field sizes whereas it increases using the Batho and equivalent pathlength algorithms. The dose perturbation factor (DPF) is defined as the ratio of dose to a point within the inhomogeneity to the same point in a homogeneous phantom. The dose correction factor is defined as the ratio of dose calculated by an algorithm at a point to the Monte Carlo derived dose at the same point, respectively. DPF is noted to be significant for small fields and low density for all algorithms. Comparisons of the algorithms with Monte Carlo simulations is reflected in the DCF, which is close to 1.0 for the convolution‐superposition algorithm. The Batho and equivalent pathlength algorithms differ significantly from Monte Carlo simulation for most field sizes and densities. Convolution superposition shows better agreement with Monte Carlo data versus the Batho or equivalent pathlength corrections. As the field size increases the DCF's for all algorithms converge toward 1.0. The largest differences in DCF are at the interface where changes in electron transport are greatest. For a 6 MV photon beam, electronic equilibrium is restored at field sizes above 3 cm diameter and all of the algorithms predict dose in and beyond the inhomogeneous region equally well. For accurate dosimetry of small fields within and near inhomogeneities, however, simple algorithms such as Batho and equivalent pathlength should be avoided.
Glass rod detectors for small field, stereotactic radiosurgery dosimetric audit
Authors: Perks J. , Gao M. , Smith V. , Skubic S. , Goetsch S
Published: March 2005

This paper demonstrates the feasibility of using glass rod detectors for quality assurance audit of radiosurgery units. Five radiosurgery units (3 Gamma Knife model C, 1 Gamma Knife model U and 1 Cyberknife) located in California participated in the study. At each center glass rod detectors were used to measure a number of dosimetric parameters including relative collimator output factor and absolute dose rate. The Gamma Knife data obtained is in excellent agreement with the commissioning data generated by the manufacturer for each unit and the Cyberknife data is in general agreement with the data published by other centers. In particular the output factor of the 4 mm Gamma Knife helmet factor, a subject of abundant debate, was measured in the range 0.863–0.872 with an accuracy of better than 1% across the four participating centers. It is hoped that this pilot study will facilitate a nationwide postal audit of stereotactic radiosurgery units.
Boron neutron capture enhancement of fast neutron radiotherapy utilizing a moderated fast neutron beam
Authors: Burmeister Jay , Yudelev Mark , Kota Chandrasekhar , Maughan Richard L.
Published: March 2005

An investigation of the therapeutic potential of boron neutron capture (BNC) enhancement of fast neutron therapy utilizing the Harper University Hospital superconducting cyclotron‐produced fast neutron therapy beam is presented. A technique for modification of the fast neutron beam to increase the BNC enhancement is presented along with an evaluation of the effects of beam moderation on the biological effectiveness of the absorbed dose. Characteristics of the photon, neutron, and boron neutron capture components of the absorbed dose are presented. Results demonstrate the possibility of therapeutic gains greater than 50% over conventional fast neutron therapy at depths required to treat brain lesions. This enhancement is estimated assuming currently achievable boron concentrations, and is more than adequate to provide a therapeutic window for the effective treatment of Glioblastoma Multiforme without prohibitive toxicity to the normal brain.
The effect of ambient pressure on well chamber response: Experimental results with empirical correction factors
Authors: Griffin S. L. , DeWerd L. A. , Micka J. A. , Bohm T. D.
Published: March 2005

For some air‐communicating well‐type chambers used for low‐energy brachytherapy source assay, deviations from expected values of measured air kerma strength were observed at low pressures associated with high altitudes. This effect is consistent with an overcompensation by the air density correction to standard atmospheric temperature and pressure . This work demonstrates that the correction does not fully compensate for the high altitude pressure effects that are seen with air‐communicating chambers at low photon energies in the range of . Deviations of up to 18% at a pressure corresponding to an approximate elevation of for photon energies of are possible. For high‐energy photons and for high‐energy beta emitters in air‐communicating chambers the factor is applicable. As expected, the ambient pressure does not significantly affect the response of pressurized well chambers (within 1%) to either low‐ or high‐energy photons. However, when used with beta emitters, pressurized chambers appear to exhibit a slight dependence on the ambient pressure. Using measured data, the response and correction factors were determined for three models of air‐communicating well chambers for low‐energy photon sources at various pressures corresponding to elevations above sea level. Monte Carlo calculations were also performed which were correlated with the experimental findings. A more complete study of the Monte Carlo calculations is presented in the accompanying paper, “The effect of ambient pressure on well chamber response: Monte Carlo calculated results for the HDR1000 Plus.”
Investigation of secondary neutron dose for dynamic MLC IMRT delivery
Authors: Howell Rebecca M. , Ferenci Michele S. , Hertel Nolan E. , Fullerton Gary D.
Published: March 2005

Secondary neutron doses from the delivery of conventional and intensity modulated radiation therapy (IMRT) treatment plans were compared. IMRT was delivered using dynamic multileaf collimation (MLC). Additional measurements were made with static MLC using a primary collimated field size of and MLC field sizes of , , and . Neutron spectra were measured and effective doses calculated. The IMRT treatment resulted in a higher neutron fluence and higher dose equivalent. These increases were approximately the ratio of the monitor units. The static MLC measurements were compared to Monte Carlo calculations. The actual component dimensions and materials for the Varian Clinac including the MLC were modeled with MCNPX to compute the neutron fluence due to neutron production in and around the treatment head. There is excellent agreement between the calculated and measured neutron fluence for the collimated field size of with the MLC field. Most of the neutrons at the detector location for this geometry are directly from the accelerator head with a small contribution from room scatter. Future studies are needed to investigate the effect of different beam energies used in IMRT incorporating the effects of scattered photon dose as well as secondary neutron dose.
MRI‐guided interstitial ultrasound thermal therapy of the prostate: A feasibility study in the canine model
Authors: Nau William H. , Diederich Chris J. , Ross Anthony B. , Butts Kim , Rieke Viola , Bouley Donna M. , Gill Harcharan , Daniel Bruce , Sommer Graham
Published: March 2005

The feasibility of MRI‐guided interstitial ultrasound thermal therapy of the prostate was evaluated in an in vivo canine prostate model. MRI compatible, multielement interstitial ultrasound applicators were developed using diameter cylindrical piezoceramic transducers (7 to ) sectored to provide of angular directional heating. Two in vivo experiments were performed in canine prostate. The first using two interstitial ultrasound applicators, the second using three ultrasound applicators in conjunction with rectal and urethral cooling. In both experiments, the applicators were inserted transperineally into the prostate with the energy directed ventrally, away from the rectum. Electrical power levels of per element ( acoustic output power) were applied for heating periods of 18 and . Phase‐sensitive gradient‐echo MR imaging was used to monitor the thermal treatment in real‐time on a interventional MRI system. Contrast‐enhanced T1‐weighted images and vital‐stained serial tissue sections were obtained to assess thermal damage and correlate to real‐time thermal contour plots and calculated thermal doses. Results from these studies indicated a large volume of ablated (nonstained) tissue within the prostate, extending 1.2 to from the applicators to the periphery of the gland, with the dorsal margin of coagulation well‐defined by the applicator placement and directionality. The shape of the lesions correlated well to the hypointense regions visible in the contrast‐enhanced T1‐weighted images, and were also in good agreement with the contours of the threshold temperature and . This study demonstrates the feasibility of using directional interstitial ultrasound in conjunction with MRI thermal imaging to monitor and possibly control thermal coagulation within a targeted tissue volume while potentially protecting surrounding tissue, such as rectum, from thermal damage.
Calculation of photon energy deposition kernels and electron dose point kernels in water
Authors: Mainegra‐Hing Ernesto , Rogers D. W. O. , Kawrakow Iwan
Published: March 2005

Effects of changes in the physics of EGSnrc compared to EGS4/PRESTA on energy deposition kernels for monoenergetic photons and on dose point kernels for beta sources in water are investigated. In the diagnostic energy range, Compton binding corrections were found to increase the primary energy fraction up to 4.5% at with a corresponding reduction of the scatter component of the kernels. Rayleigh scattered photons significantly increase the scatter component of the kernels and reduce the primary energy fraction with a maximum 12% reduction also at where the Rayleigh cross section in water has its maximum value. Sampling the photo‐electron angular distribution produces a redistribution of the energy deposited by primaries around the interaction site causing differences of up to 2.7 times in the backscattered energy fraction at . Above the pair production threshold, the dose distribution versus angle of the primary dose component is significantly different from the EGS4 results. This is related to the more accurate angular sampling of the electron‐positron pair direction in EGSnrc as opposed to using a fixed angle approximation in default EGS4. Total energy fractions for photon beams obtained with EGSnrc and EGS4 are almost the same within 0.2%. This fact suggests that the estimate of the total dose at a given point inside an infinite homogeneous water phantom irradiated by broad beams of photons will be very similar for kernels calculated with both codes. However, at interfaces or near boundaries results can be very different especially in the diagnostic energy range. EGSnrc calculated kernels for monoenergetic electrons (, , and ) and beta spectra ( and ) are in excellent agreement with reported EGS4 values except at where inclusion of spin effects in EGSnrc produces an increase of the effective range of electrons. Comparison at with an ETRAN calculation of the electron dose point kernel shows excellent agreement.
Helical tomotherapy radiation leakage and shielding considerations
Authors: Balog John , Lucas Dan , DeSouza Cleber , Crilly Rick
Published: March 2005

Leakage radiation and room shielding considerations increase significantly for intensity‐modulated radiation therapy (IMRT) treatments due to the increased beam‐on time to deliver modulated fields. Tomotherapy, with its slice by slice approach to IMRT, further exacerbates this increase. Accordingly, additional shielding is used in tomotherapy machines to reduce unwanted radiation. The competing effects of the high modulation and the enhanced shielding were studied. The overall room leakage radiation levels are presented for the continuous gantry rotations, which are always used during treatments. The measured leakage at 4 m from the isocenter is less than relative to calibration output. Primary radiation exposure levels were investigated as well. The effect of forward‐directed leakage through the beam‐collimation system was studied, as this is the leakage dose the patient would receive in the course of a treatment. A 12‐min treatment was calculated to produce only 1% patient leakage dose to the periphery region. Longer treatment times might yield less patient dose if the field width selected is correspondingly narrower. A method for estimating the worst‐case leakage dose a patient would receive is presented.
Particle selection and beam collimation system for laser‐accelerated proton beam therapy
Authors: Luo Wei , Fourkal Eugene , Li Jinsheng , Ma Chang‐Ming
Published: March 2005

In a laser‐accelerated proton therapy system, the initial protons have broad energy and angular distributions, which are not suitable for direct therapeutic applications. A compact particle selection and collimation device is needed to deliver small pencil beams of protons with desired energy spectra. In this work, we characterize a superconducting magnet system that produces a desired magnetic field configuration to spread the protons with different energies and emitting angles for particle selection. Four magnets are set side by side along the beam axis; each is made of NbTi wires which carry a current density ofat 4.2 K, and produces a magnetic field ofin the corresponding region. Collimation is applied to both the entrance and the exit of the particle selection system to generate a desired proton pencil beam. In the middle of the magnet system, where the magnetic field is close to zero, a particle selection collimator allows only the protons with desired energies to pass through for therapy. Simulations of proton transport in the presence of the magnetic field show that the selected protons have successfully refocused on the beam axis after passing through the magnetic field with the optimal magnet system. The energy spread for any given characteristic proton energy has been obtained. It is shown that the energy spread is a function of the magnetic field strength and collimator size and reaches the full width at half maximum of 25 MeV for 230 MeV protons. Dose distributions have also been calculated with theGEANT3Monte Carlo code to study the dosimetric properties of the laser‐accelerated proton beams for radiation therapy applications.
Assessment of whole body and regional evaporative heat loss coefficients in very premature infants using a thermal mannequin: Influence of air velocity
Authors: Belghazi Khalid , Elabbassi Elmountacer Billah , Tourneux Pierre , Libert Jean‐Pierre
Published: March 2005

In human adults, experimental assessment of the evaporative heat loss coefficient requires a fully wetted skin surface area implying exposure to severe heat stress. For ethical reasons, this type of experimental situation is impossible to perform on neonates. The aim of the present study was to assess values in clinical situations for the body as a whole and for the different body segments, in particular, in natural and forced convection and using an anthropomorphic, sweating, thermal mannequin to represent a very small premature neonate (body mass 900 g). Skin hydration (i.e., simulated sweating) was performed by two electronic pumping systems, providing a steady adjustable flow of water to the mannequin surface. Experiments were carried out in a closed‐incubator heated to air temperatures of 33 °C and 36 °C, with air velocities ranging from 0.01 to , and with four levels of air relative humidity (40, 50, 60, and 80%). For the body as a whole, in natural convection, whereas in forced convection was 11.7, 12.4, and for air velocities of 0.2, 0.4, and , respectively. As far as local is concerned, our results showed that the relative values of regional water loss in forced convection differ greatly from those observed under still air conditions. Thus, increasing air velocity enhances the heterogeneity in regional skin cooling, which may contribute to the neonate's thermal discomfort.
Contrast‐detail phantom scoring methodology
Authors: Thomas Jerry A. , Chakrabarti Kish , Kaczmarek Richard , Romanyukha Alexander
Published: March 2005

Published results of medical imaging studies which make use of contrast detail mammography (CDMAM) phantom images for analysis are difficult to compare since data are often not analyzed in the same way. In order to address this situation, the concept of ideal contrast detail curves is suggested. The ideal contrast detail curves are constructed based on the requirement of having the same product of the diameter and contrast (disk thickness) of the minimal correctly determined object for every row of the CDMAM phantom image. A correlation and comparison of five different quality parameters of the CDMAM phantom image determined for obtained ideal contrast detail curves is performed. The image quality parameters compared include: (1) contrast detail curve—a graph correlation between “minimal correct reading” diameter and disk thickness; (2) correct observation ratio—the ratio of the number of correctly identified objects to the actual total number of objects multiplied by 100; (3) image quality figure—the sum of the product of the diameter of the smallest scored object and its relative contrast; (4) figure‐of‐merit—the zero disk diameter value obtained from extrapolation of the contrast detail curve to the origin (e.g., zero disk diameter); and (5) ‐factor—the product of the thickness and the diameter of the smallest correctly identified disks. The analysis carried out showed the existence of a nonlinear relationship between the above parameters, which means that use of different parameters of CDMAM image quality potentially can cause different conclusions about changes in image quality. Construction of the ideal contrast detail curves for CDMAM phantom is an attempt to determine the quantitative limits of the CDMAM phantom as employed for image quality evaluation. These limits are determined by the relationship between certain parameters of a digital mammography system and the set of the gold disks sizes in the CDMAM phantom. Recommendations are made on selections of CDMAM phantom regions which should be used for scoring at different image quality and which scoring methodology may be most appropriate. Special attention is also paid to the use of the CDMAM phantom for image quality assessment of digital mammography systems particularly in the vicinity of the Nyquist frequency.
Decision support for sustainable development using a Canadian economic input–output life cycle assessment model
Authors: Bjorn Andrew , Declercq-Lopez Laura , Spatari Sabrina , MacLean Heather L
Published: March 2005

The environmental and human health impacts of engineering activities have reshaped the way engineers make decisions. Increasingly, engineering decision-making is taking into consideration the full life cycle implications of engineering activities. This paper details the development and application of a national economic input–output-based life cycle assessment model, a tool for guiding engineering decision-making, for the Canadian economy. The model consists of 61 industries and 103 commodities and incorporates economic and environmental–resource data, including marginal resource consumption, energy use, releases of National Pollutant Release Inventory compounds, and emissions of greenhouse gases. The model is useful for evaluating various development strategies and analyzing the potential direct and indirect impacts of alternative public policies on the Canadian economy and environment. The model is applied to various sectors of the Canadian economy, and the life-cycle implications of demands for different commodities are determined, including demand for electricity and construction materials for highway design.Key words: life cycle assessment–analysis, sustainable development, economic input–output.
Construction prequalification using data envelopment analysis
Authors: McCabe Brenda , Tran Viet , Ramani Joseph
Published: March 2005

Contractor prequalification is essential in most construction projects, and the process has been performed by many different methods in practice. Data envelopment analysis (DEA) had been recognized as a useful technique to prequalify contractors by assigning relative efficiency scores. Data envelopment analysis, however, usually requires a large amount of data and has not been fully developed to achieve reliable results. An enhanced contractor prequalification model using DEA was developed together with a methodology for determining a "practical frontier" of best contractors. The established practical frontier can be used as a regional performance standard for the owner in prequalification and as improvement guidelines for contractors.Key words: contractor prequalification, construction engineering, data envelopment analysis, practical frontier.
A method-based survey of life cycle costing literature pertinent to infrastructure design and renewal
Authors: Christensen Paul N , Sparks Gordon A , Kostuk Kent J
Published: March 2005

Motivated by Canada's infrastructure crisis, the Intelligent Sensing for Innovative Structures (ISIS) Canada Research Network has developed and demonstrated the efficacy of innovative materials and monitoring technologies to support infrastructure design and renewal efforts. To quantify the potential benefits of these technologies across a diverse range of infrastructure applications, a rational, pragmatic and flexible method of life cycle costing (LCC) is needed. The purpose of this paper is to review and broadly classify LCC methods evident in pertinent literature. Through this process, a state-of-the-art LCC method is identified and described. Its noted strengths and limitations suggest promising avenues for future research.Key words: life cycle cost, infrastructure, design.
Turbulent flow field in a scour hole at a semicircular abutment
Authors: Dey Subhasish , Barbhuiya Abdul Karim
Published: March 2005

The three-dimensional turbulent flow field in a scour hole at a semicircular abutment under a clear water regime was experimentally measured in a laboratory flume using an acoustic Doppler velocimeter. The distributions of time-averaged velocity components, turbulent intensity components, turbulent kinetic energy, and Reynolds stresses at different azimuthal planes are presented. Upstream, presentation of flow field through vector plots at azimuthal and horizontal planes shows the existence of a large primary vortex associated with the downflow inside the scour hole. On the other hand, downstream, the flow field is irregular. The bed shear stresses are determined from the Reynolds stresses and velocity gradients. The data presented in this paper would be useful for the development and validation of flow field models, which can be used to determine the strength of the primary vortex that is used to estimate scour depth at bridge abutments.Key words: bridge abutments, fluid flow, three-dimensional flow, turbulent flow, open channel flow, scour, sediment transport, hydraulic engineering.
Geographic information system (GIS) based decision support for neighbourhood traffic calming
Authors: Randall Todd A , Churchill Cameron J , Baetz Brian W
Published: March 2005

In suburban areas, traffic issues are generally related to elevated speeds and volumes and a perceived reduction in personal safety. In response, traffic engineers have designed and implemented a variety of traffic calming measures for local and collector streets, with significant speed reductions and other benefits. Less common are measures to address traffic issues on arterials which (if implemented) might reduce speeds, thereby encouraging more sustainable transportation modes and lessening automobile dependence. A geographic information system (GIS) based tool has been developed to provide decision support for the development of neighbourhood traffic calming plans for all street types. This tool is potentially useful because of the increased use of traffic calming measures and the growing public desire for safer streets. Decision support (provided by the tool) is dependent upon measured or perceived problems, roadway type, and user objectives, as well as the potential impacts and current installation costs of traffic calming measures. An application to suburban Hamilton demonstrates the functionality of this tool.Key words: traffic calming, suburban retrofitting, urban sustainability, decision support system.
Policy making for greening the concrete industry in Canada: a systems thinking approach
Authors: Rehan R , Nehdi M , Simonovic S P
Published: March 2005

Portland cement production in Canada increased from 1.7 million tonnes in 1946 to more than 13 million tonnes in 2002. Although the industry is a major player in meeting infrastructural needs of Canadians, it is also a major user of natural resources such as water, natural minerals, and aggregates. Moreover, for each tonne of cement clinker produced, 1 t of CO2 is released into the atmosphere. At the same time, Canada produces nearly 5 million tonnes of fly ash each year, and yet the use of fly ash as cement replacement remains dismally low at around 17%. It is believed that through product and process innovations, more fly ash can be used in concrete, thus preserving natural resources, reducing CO2 emissions, and helping Canada meet the requirements of the Kyoto Protocol. Forecasting the future impact of using fly ash in concrete has been based on qualitative and linear estimates, however, without accounting for the complexity of the problem and its dynamic feedbacks. In this paper, a novel application of system dynamics modeling, a feedback-based object-oriented modeling paradigm, is proposed to create a rational model that departs from current approaches used in modeling CO2 emissions of cement production. The model accounts for the various enablers and barriers for using fly ash in concrete, including market dynamics and technology development. It allows the user to test a wide variety of scenarios and policies, its flexible architecture permits coupling it with general economic or service life models, and its modular nature allows expanding its boundaries to include other facets of the holistic CO2 emissions problem in Canada.Key words: concrete, blended cements, CO2 emission, global warming, sustainable development, system dynamics, modeling.
A numerical model of sediment-laden turbulent flow in an open channel
Authors: Yoon Joon-Yong , Kang Seung-Kyu
Published: March 2005

A numerical analysis of sediment-laden flow is carried out. Velocity and suspended sediment concentration profiles are compared with the experiments in open channel flow. The k-ω turbulence model is selected for the fully turbulent flow field because this model has shown good results for wall-bounded flows and for flows on rough surfaces. The concentration equation that takes into account the settling velocity is adopted for the concentration field. A new eddy viscosity model is proposed in the turbulence modeled equations to couple the velocity field and the concentration field. The bed load thickness and surface roughness are considered in this study, and reasonable predictions are achieved.Key words: numerical simulation, suspended sediment transport, open channel flow, k-ω turbulence model.
Influence of vertical alignment on horizontal curve perception: effect of spirals and position of vertical curve
Authors: Hasan Moudud , Sayed Tarek , Hassan Yasser
Published: March 2005

Several studies have shown that the perception of horizontal curves can be influenced by an overlapping vertical alignment. A previous two-phase study investigated the hypothesis that a horizontal curve appears flatter when overlapping with a vertical sag curve and sharper when overlapping with a vertical crest curve. The study concluded that the hypothesis was valid. The study also developed several statistical models to estimate the perceived radius of horizontal curves in a combined alignment. This study extends the earlier work by investigating the effect of additional geometric parameters on the perception. The parameters examined include the presence of spiral curves, the length of the spirals, and the position of the vertical curve midpoint relative to the horizontal curve. It was found that (1) driver misperception of the horizontal curvature increases as the radius of the horizontal curve increases, (2) the presence of a spiral curve affects driver perception of the horizontal curvature in the case of crest combination only, (3) the length of the spiral curve has no effect on the perception whether on crest or sag combinations, and (4) while the effect of the position of the vertical curve midpoint relative to the horizontal curve is not statistically significant, it seems that the perception problem appears to diminish as the positive offsets increases.Key words: highway geometric design, visual perception, combined alignment.
A constitutive model of concrete confined by steel reinforcements and steel jackets
Authors: Li Y-F , Chen S-H , Chang K-C , Liu K-Y
Published: March 2005

In this paper, a total of 60 concrete cylinders 30 cm in diameter and 60 cm in length confined by steel jackets of different thicknesses and different types of lateral steel reinforcements are tested to obtain the stress–strain curves of the cylinders. A constitutive model is proposed to describe the behavior of concrete confined by steel reinforcement, steel jackets, and both steel reinforcement and steel jackets used to retrofit and strengthen reinforced concrete structures. The confined concrete stress–strain curve of the proposed model is divided into two regions: the curve in the first region is approximated using a second-order polynomial equation, and that in the second region using an nth-order power-law equation, where n is a function of the unconfined concrete strength and the lateral confining stress. The results of the experiments show that different types of lateral steel reinforcement contribute greatly to the compressive strength of concrete cylinders confined by the reinforcement. Comparing the stress–strain curves of the uniaxial test with that from the proposed model, we conclude that the proposed model for concrete confined by a steel jacket and lateral steel reinforcement can predict the experimental results very well.Key words: constitutive model, steel jacket, confined concrete.
Energy use in Canada: environmental impacts and opportunities in relationship to infrastructure systems
Authors: Cuddihy John , Kennedy Christopher , Byer Philip
Published: March 2005

Canada exhibits high per capita energy consumption. This paper examines energy use in Canada by region and sector, focusing on four sectors most relevant to civil engineering activities: residential, commercial–institutional, construction, and transportation. Environmental impacts associated with major energy sources including coal, petroleum products, natural gas and electricity are reviewed. The relationships between energy consumption and infrastructure design are analysed. Opportunities for reductions are identified in building design, water and waste-water systems, urban form, and transportation. Large improvements in commercial and residential energy efficiency can be achieved through the implementation of existing technologies in building upgrades, retrofits, and rebuilds. Increasing surface albedos and more extensive use of vegetative shading and consideration of the geometric properties of urban canyons and their microclimatic effects also allow for considerable energy savings. The incorporation of mixed-modal transit, walking and cycling paths, and community-scale design as elements of long-term transportation planning and the development of alternative transportation technologies have the potential to considerably reduce per capita energy use. The development and implementation of alternative energy supply technologies include energy recovery from waste-water treatment.Key words: energy, infrastructure, urban, sustainability, sustainable development.
System dynamics approach to assess the sustainability of reclamation of disturbed watersheds
Authors: Elshorbagy Amin , Jutla Antarpreet , Barbour Lee , Kells Jim
Published: March 2005

The mining of oil sands in northern Alberta leaves behind large open pits, tailings, and overburden piles in which the surface and subsurface hydrology has been completely disrupted. Extensive reclamation work is required to reconstruct the entire landscape and reestablish the various elements of the hydrologic cycle. Syncrude Canada Ltd. has established a series of small instrumented watersheds in a reclaimed overburden pile at the Mildred Lake mine in northern Alberta, Canada, to test the sustainability of different reclamation strategies. The purpose of these field sites is to assess the performance of different reclamation strategies and track the evolution of the reclaimed landscape with time. The saline–sodic shale overburden has been covered with different (in type and depth) soil layers to provide sufficient moisture storage for vegetation while minimizing runoff and salt transport into the cover from the underlying overburden shale. In this paper, a system dynamics watershed model (SDWM) is developed to simulate one of the reconstructed watersheds and assess its ability to provide common watershed functions. The model is at an early stage, but preliminary results point to the potential of the system dynamics approach in simulating watersheds and testing different scenarios. The tested reclamation strategy seems to be satisfactory within a certain range of hydrologic conditions. Further validation of the SDWM is required, however, before relying on its results for decision support with regard to reclamation strategies.Key words: sustainability, watershed simulation, system dynamics, reclamation, STELLA.
Beijing water resources and the south to north water diversion project
Authors: Wei Duan
Published: March 2005

Beijing is located in a semiarid region, and water shortage is a common problem in the city. Along with the rapid increase in water demand, due to fast socioeconomic development and an increase in population, a shortage of water resources and a deterioration of the water environment have become obstacles to sustainable socioeconomic development in Beijing. In the long run, sustainable water resources management, water conservation, and completion of the south to north water diversion project will solve the problem. This paper introduces the water resources situation in Beijing; analyzes future water demand; and discusses the actions of water saving, nontraditional water resources exploitation, wetland construction, and water environment protection. The paper also explains the importance of the south to north water diversion project and the general layout of the water supply strategy, water distribution system, and methods to efficiently use the diverted water in Beijing.Key words: water resources, water supply, water saving, water recycling, water diversion.
The application of knowledge management to support the sustainable analysis of urban transportation infrastructure
Authors: El-Diraby T E , Abdulhai B , Pramod K C
Published: March 2005

This paper presents a semantic framework for supporting the cost–benefit analysis in urban transit rehabilitation decisions. The use of semantic representations of decision parameters allows for more effective knowledge management practice and easier accumulation and access of corporate knowledge regarding balancing traditional construction investments with the costs to the environment, local business, and impacts on traffic. A sample illustrative case was considered by this study. It includes a comparison of a hypothetical scenario of building a monorail to replace an existing streetcar in one of Toronto's most congested streets: King Street. A microscopic simulation model for the King Street route has been developed and used in comparing the status quo to the proposed scenario in terms of impacts on traffic performance. A cost–benefit analysis has been conducted to assess the feasibility of both options. The study investigated direct costs such as monorail construction cost, streetcar system removal cost, and operating and maintenance costs of both systems. The sustainability-related costs included user costs and accident costs.Key words: sustainable infrastructure, knowledge management, cost–benefit analysis.
Sustainable waste management: recovery of fuels from petroleum sludge
Authors: Elektorowicz Maria , Habibi Shiva
Published: March 2005

Petroleum sludge is a complex mixture of hydrocarbons, water, metals, and suspended fine solids. The objective of this research was to develop a technique that will lead to the separation of phases ready for further reuse. A study was carried out to investigate a combination of various systems of electrokinetic cells, to which oily sludge, conditioning liquids, and different electrical potentials were applied. The developed electrokinetic phase separation is a new cost-effective technology, which in turn will permit the revitalization of petroleum sludge. This method can significantly reduce the amount of wasted sludge and can recover new fuels free of metals and water. Life cycle analysis of the recovered fuel shows that a new petroleum waste management protocol might reduce emissions of major greenhouse gases such as CO2, CH4, and N2O by 40 026 000, 1057, and 566 kg, respectively, per refinery per year.Key words: oily sludge, electrokinetics, fuel recovery, sustainable management, life cycle analysis.
EFFECT OF PHONONS IN STIMULATED BRILLOUIN SCATTERING ON OPTICAL FIBER COMMUNICATION
Authors: HSU H. , LI T. N. , YANG E. Z. , YU J. L. , LÜ J. , XU YUE , GAO YAN
Published: March 2005

Stimulated Brillouin scattering (SBS) can be used for phase conjugation mirrors in many laser systems1,5 and it also often appears in long distance optical fiber communication systems because the threshold of SBS is normally inversely proportional to the interaction length.2 In this paper, the effect of phonon loss is investigated. Our study shows that phase conjugation systems do require lower phonon loss and higher nonlinearity as expected but higher phonon loss and lower nonlinearity are actually desirable for long distance optical fiber communications.
MEASUREMENT OF THE INTENSITY-DEPENDENT REFRACTIVE INDEX USING COMPLETE SPATIO-TEMPORAL PULSE CHARACTERIZATION
Authors: PIREDDA GIOVANNI , DORRER CHRISTOPHE , WILLIAMS ELLEN M. KOSIK , WALMSLEY IAN A. , BOYD ROBERT W.
Published: March 2005

We use complete spatio-temporal characterization of an ultrashort pulse to study self-phase modulation and other propagation effects in a sample of SF59 optical glass. The goal of this work is to perform accurate experimental measurements of the optical parameters of material samples. From the measured dependence of the self-induced phase shift on the transverse coordinate, we deduce a value of the coefficient n2 of the intensity-dependent refractive index that is in good agreement with previous measurements. We also observe that the spectrum of the transmitted pulse can be explained only approximately in terms of the solution to the nonlinear Schrödinger equation.
DESIGN AND SYNTHESES OF HIGHLY EFFICIENT AND THERMALLY-STABLE IMIDAZOLE CHROMOPHORES BEARING DIAMINO GROUPS FOR NONLINEAR OPTICS
Authors: WU WEI , ZHANG ZHAOLI , ZHANG XIAOYUN
Published: March 2005

Four imidazole type chromophores bearing diamino groups were designed and synthesized with a facile method. All the chromophores possess efficient second-order nonlinearities based on MOPAC/AM1 calculation, high thermal stability and good transparency for the application in NLO materials. Chromophore 1d, an X-type dual charge transfer system, shows well-balanced nonlinearity/transparency properties.