bluuebunny/crossref_metadata_2025 huggingface dataset:
Explorations in Biofuels Economics, Policy, and History: Introduction to the Special Issue
Authors: Gardner Bruce , Tyner Wallace
Published: December 2007

Biofuels are prominent in current discussion both as a solution to problems and as a creator of problems. They have promise as a substitute for fossil fuels, particularly for petroleum as the raw material for transportation fuel. But biofuels also have pitfalls, especially when produced at a scale sufficient to replace a significant proportion of the world's use of petroleum. The articles in this special issue analyze key aspects of both the promise and pitfalls of biofuels. They address issues in the technology of producing raw materials for biofuels and converting these raw materials into fuel, resource constraints facing expansion of biofuel production, and the demand for fuels. Particular attention is paid to the relationship between expanded biofuel production and the cost of food. The economics of biofuels is inherently linked to policy issues as well as market analysis because biofuels in every country have received subsidies from governments. Consequently several articles address the welfare economics of governmental efforts to promote biofuels, with a focus on U.S. ethanol subsidies. These subsidies generate net social losses (deadweight costs) on a global scale, although not necessarily from the U.S. national viewpoint. Governmental promotion of biofuels can be justified on the grounds of externalities created by the use of fossil fuels, most notably in recent debates on global warming caused by the release of sequestered carbon in the form of carbon dioxide. This justification is weakened and perhaps even nullified by externalities in the production and use of biofuels. The articles in this issue consider a range of topics concerning these matters, and the welfare losses caused by biofuel subsidies absent net environmental gains from biofuels.
Development of Water Gas Shift Supported Catalysts for Fuel Processor Units
Authors: Fiorot Sabina , Galletti Camilla , Specchia Stefania , Saracco Guido , Specchia Vito
Published: December 2007

Fuel Cell (FC) technology promises to be a viable alternative for small scale electric heat and power generation (combined heat and power units, CHP). Moreover, the polymer electrolyte membrane FC (PEM-FC) is currently considered the most suitable technology for vehicles, both for traction and as auxiliary power unit APU; the latter is used on boats and yachts too. The ideal fuel for the PEM-FC is pure H2 gas. However, due to the lack of H2 distribution infrastructures, the current way of producing H2 to feed PEM-FC involves the reforming of hydrocarbon feedstocks and the removing of the catalyst poison CO with a series of catalytic steps. Water Gas Shift (WGS) is an attractive option for CO conversion although, due to its exothermic nature (?H298°C = -41.1 kJ?mol-1), the equilibrium conversion is thermodynamically limited at high temperatures. In contrast, at low temperatures, the reaction rate is constrained by kinetics such that highly performing catalysts are necessary to provide adequate activity. For these reasons two WGS stages are generally employed: a high temperature stage (HT-WGS), which takes place between 400-500°C and reduces the CO concentration to about 2-5%, followed by a second shift at a lower temperature (LT-WGS), with a cooling stage in between, which is carried out over a temperature range of 200-400°C and reduces the CO concentration to about 0.5-1%. In this work, catalysts based on Pt and mixed Pt+Re on different supports were prepared and their catalytic activity was tested; moreover, a comparison with commercial catalysts was also carried out. Very promising results were obtained in the HT-WGS range as the catalytic performances of the prepared catalysts were superior to those reached by the commercial catalyst; therefore they can be considered as possible candidates for FC technology.
Psychometric Properties of the Chinese Leadership Practices Inventory
Authors: Chen Hsiu-Chin , Baron Mark
Published: December 2007

There is little evidence of psychometric properties of the Leadership Practices Inventory (LPI) when used with Taiwan's nursing faculty. The purpose of this study was to examine psychometric properties of the Chinese LPI and provide a culturally appropriate instrument for use in Taiwan's nursing. Thirteen bachelor and nine associate degree nursing programs were eligible for participation. The Chinese LPI was used to gather nursing faculty's perceptions of leadership behaviors of nursing deans and directors. A total of 369 questionnaires were returned. Psychometric examinations used content validity, internal consistency reliability, item analysis, and construct and concurrent validities. Cronbach's alpha of the Chinese LPI total scale was .96. Three factors were extracted that explained 59.5 % of the variance. Concurrent validity was supported by the Chinese Multifactor Leadership Questionnaire (MLQ-5X). Findings for the psychometric properties and cultural appropriateness of the Chinese LPI supported its potential as an instrument for measuring nursing leadership in Taiwan.
Outcomes of ADN-BSN Partnerships to Increase Baccalaureate Prepared Nurses
Authors: Sizemore Mary H , Robbins Leslie K. , Hoke Mary M , Billings Diane M
Published: December 2007

The limited supply of BSN nurses hinders efforts to increase patient care quality and address health disparities. In largely rural and economically disadvantaged areas, associate degree prepared nurses provide the majority of nursing services. To address a statewide need, a BSN Program and 3 ADN Programs formed a partnership to take BSN education to rural and medically underserved areas. This article describes the program planning, implementation, and evaluation using an adapted assessment framework with partnership principles as its foundation. Interactive television, internet education components, local clinical experiences, and distant nursing faculty liaisons were used. The nursing course sequence was completed by 101 of 102 students. Hall's Professionalism Scale, the California Critical Thinking Disposition Inventory, and the California Critical Thinking Skills Test measured the increases found in professional socialization and critical thinking. Use of the adapted theoretical framework represented a strategic approach to developing a distance delivered nursing education program.
Effectiveness of an Evidence-Based Curriculum Module in Nursing Schools Targeting Safe Patient Handling and Movement
Authors: Nelson Audrey L. , Waters Thomas R , Menzel Nancy N. , Hughes Nancy , Hagan Pamela C , Powell-Cope Gail , Sedlak Carol , Thompson Vivian
Published: December 2007

Nursing schools in the United States have not been teaching evidence-based practices for safe patient handling, putting their graduates at risk for musculoskeletal disorders (MSDs). The specific aim of this study was to translate research related to safe patient handling into the curricula of nursing schools and evaluate the impact on nurse educators and students' intentions to use safe patient handling techniques. Nurse educators at 26 nursing schools received curricular materials and training; nursing students received the evidence-based curriculum module. There were three control sites. Questionnaires were used to collect data on knowledge, attitudes, and beliefs about safe patient handling for both nurse educators and students, pre- and post-training. In this study, we found that nurse educator and student knowledge improved significantly at intervention schools, as did intention to use mechanical lifting devices in the near future. We concluded that the curriculum module is ready for wide dissemination across nursing schools to reduce the risk of MSDs among nurses.
Measures of Homophobia among Nursing Students and Faculty: A Midwestern Perspective
Authors: Dinkel Shirley , Patzel Brenda , McGuire Michael J , Rolfs Elaine , Purcell Kelly
Published: December 2007

It is well documented that homophobia exists among healthcare providers including nurses. However, little research is available on the level of homophobia among nursing students and nursing faculty. Using the Index of Attitudes Toward Homosexuals (IAH) and the Homophobic Behavior of Students Scale (HBSS) 241 nursing students and 32 faculty in a Midwest university were invited to participate. One hundred twenty six students completed the survey resulting in a 51% return rate. Fifteen faculty completed the survey. Results reveal that there is a low level of homophobia among students and faculty at this university. Religion and LGBT acquaintances or family members accounted for most of the variance within the homophobia scores. While scores reflect low levels of homophobia, it is the belief of these researchers that they actually may reflect ambivalent or heterosexist attitudes toward LGBT people which may impact healthcare delivered by these future nurses.
Willingness to Pay for Antiretroviral Therapy for HIV Positive Individuals in India
Authors: Gupta Indrani
Published: December 2007

With falling prices of antiretroviral drugs in countries like India, there has been an increasing awareness that antiretroviral therapy can be made available and accessible to a large number of HIV-positive individuals. Prices, however, still remain high enough to keep ART out of reach of a majority of affected individuals in India. This study analyses the demand for antiretroviral therapy (ART) using a contingent valuation approach, by estimating the willingness to pay for ART among a sample of HIV positive individuals in India. The study finds a very high willingness to be on ART, but substantially lower willingness to pay for it. To cover 70 percent of patients would require the price to be around Rs. 500 per month. Economic status generally and of females in particular have a positive relationship with the willingness to pay for drugs, whereas being a female exerts a downward pressure on the demand for ART.
A Model to Predict Radial Solids Holdup and Liquid Velocity Distributions in Liquid-Solid Circulating Fluidized Bed
Authors: Palani Natarajan , R. Velraj , R.V. Seeniraj
Published: December 2007

A general expression which is useful for predicting the radial distributions or for analyzing and interpreting experimental data is derived for a liquid-solid circulating fluidized bed. The effect of both the radial liquid velocity and solids holdup distributions are taken into account in the analysis. Both effects are analyzed and are related to the operating variables of superficial liquid velocity, jl, superficial solids velocity, js, and cross-sectional average solids holdup. The results predicted by the analysis are compared with the experimental data obtained for various two-phase flow regimes, when different solids and bed dimensions are applied. The model predictions show good agreements with the experimental data and reasonable trends when different solids and bed dimensions are applied. Stronger non-uniformities in flow structures are found in larger size particles systems, with larger solids density and/or larger diameter columns. Radial solids holdup distribution is related with the cross-sectional average solids holdup. Good agreement with data and reasonable trends are observed.
Consumer Food Safety Risk Perceptions and Attitudes: Impacts on Beef Consumption across Countries
Authors: Schroeder Ted C. , Tonsor Glynn T. , Pennings Joost M.E. , Mintert James
Published: December 2007

Beef food safety events have contributed to considerable market volatility, produced varied consumer reactions, created policy debates, sparked heated trade disputes, and generally contributed to beef industry frustrations. Utilizing data from a total of 4,005 consumers in the United States, Canada, Mexico and Japan in a Double-Hurdle modeling framework, we examine whether consumers altered their beef consumption behavior because of their risk aversion and risk perceptions stemming from information about beef food safety in recent years. Results reveal stark differences in risk perceptions and risk aversion regarding beef food safety across consumers in the four countries and that these differences are revealed through different beef consumption behavior. An improved understanding of food safety perceptions and attitudes will enable policy makers and agricultural industries to better anticipate consumers changing consumption behavior, if a food safety event occurs. Food safety management strategies vary across countries because of identified differences in food safety risk attitudes and risk perceptions.
Contests with Ties
Authors: Cohen Chen , Sela Aner
Published: December 2007

We study two-player all-pay contests in which there is a positive probability of a tied outcome. We show that the players' efforts in equilibrium do not depend on the expected prize in the case of a tie given that this prize is smaller than the prize for winning. The implications of this result are twofold. First, in symmetric one-stage contests, the designer who wishes to maximize the expected total effort should not award a prize in the case of a tie which is larger than one-third of the prize for winning. Second, in multi-stage contests, the designer should not limit the number of stages (tie-breaks) but should allow the contest to continue until a winner is decided.
Information-Invariant Equilibria of Extensive Games
Authors: Börgers Tilman M , McQuade Timothy
Published: December 2007

The paper studies the concept of ``ex post equilibrium" that has recently become popular in literature on auctions, mechanism design and implementation. We ask how one should define ex post equilibrium if one wants to consider extensive games, such as dynamic auctions, and if one wants to include sequential rationality in the equilibrium definition. As it turns out, this raises some conceptual questions that are not present in the static setting. We are lead to introduce three different definitions - all variations of what we call ``information-invariant equilibrium." One of these three definitions is equivalent to ``ex post equilibrium." In static games the three definitions coincide. In extensive games they do not - if we impose sequential rationality. Our main purpose is to make a methodological contribution to game theory, but we illustrate the relevance of this contribution by applying our concepts to several auction games.
The Compensation Principle and the National Income Test
Authors: Montesano Aldo
Published: December 2007

According to a common opinion in economic literature, the National Income Test provides a necessary condition for potential Pareto dominance. This paper demonstrates that this statement is true in pure-exchange economies, but, in general, false in production economies.
Mucosal Remodeling in Chronic Rhinosinusitis
Authors: Rehl Ryan M. , Balla André A. , Cabay Robert J. , Hearp Matthew L. , Pytynia Kristin B. , Joe Stephanie A.
Published: January 2008

Background

Despite pathophysiologic similarities, mucosal remodeling is well described in asthma but not chronic rhinosinusitis (CRS).

Objective

This study attempts to identify mucosal remodeling in CRS and correlate it with clinical information.

Methods

Charts and histopathology from 53 CRS patients who underwent functional endoscopic sinus surgery were reviewed. Clinical data and basement membrane (BM) thickness were recorded. BM thickness was graded as 0 (no thickening), 1 (mild thickening), 2 (moderate thickening), or 3 (marked thickening). Control mucosae from ten patients without CRS were analyzed for comparison.

Results

Duration of CRS symptoms positively correlated with BM thickness (p = 0.007). Also, patients with a markedly thickened BM (score of 3) had a significantly greater duration of CRS symptoms (120 months) compared to patients with a thinner BM (score ≤2) (33 months) (p = 0.010). Markedly thickened BM was associated with increased coincidence of asthma (p = 0.019) and aspirin sensitivity (p = 0.003). No correlation was found between BM thickness and preoperative Lund-MacKay score. There was no statistically significant difference between markedly thickened BM and thinner BM with respect to coincidence of polyps, course of preoperative systemic steroids, estimated blood loss at surgery, and number of prior surgeries.

Conclusion

Increased BM thickness is correlated with prolonged duration of symptoms and the coincidence of asthma. This may indicate paranasal sinus remodeling akin to that which occurs in the bronchioles of persistent asthmatic sufferers.
Effects of Topical Antifibrinolytics in Endoscopic Sinus Surgery: A Pilot Randomized Controlled Trial
Authors: Athanasiadis Theodore , Beule Achim G. , Wormald Peter J.
Published: January 2008

Background

Bleeding in endoscopic sinus surgery (ESS) may increase the risk of intraoperative complications and is associated with poorer outcomes Antifibrinolytic agents have been shown to reduce bleeding if administered systemically. The aim of this study was to determine the effect of topical epsilon-aminocaproic acid (EACA) and tranexamic acid (TA) on bleeding in the surgical field during ESS.

Methods

A prospective blind randomized controlled trial was performed. Thirty patients undergoing ESS were randomized to receive either 2.5 g of EACA, 100 mg of TA, or 1 g of TA while the contralateral side received saline. The solution was applied as a spray at the conclusion of operating on each side. Bleeding was documented using standardized videoendoscopy and grading scales.

Results

EACA did not show a significant effect on intraoperative bleeding. TA at 100 mg showed a clinically significant improvement in the surgical field at 2, 4, and 6 minutes after application. The mean for 2 minutes was TA, 1.6 ± 1.08, and control, 2.2 ± 1.3; at 4 minutes was TA, 1.25 ± 1.2, and control, 1.7 ± 1.2,; and at 6 minutes was TA, 0.75 ± 1.2, and control, 1.3 ± 1.4 (p < 0.05). TA at 1 g also approached significance at all time points. Combined results from the two TA groups showed a significant improvement in the surgical field at 2, 4, 6, and 8 minutes after application. TA was regarded by the blinded surgeon as more effective than saline in 80% of cases. No adverse effects were encountered after topical application of either drug.

Conclusion

Topical application of TA is effective in achieving hemostasis and improving the surgical field. In contrast to EACA, TA is a valuable tool in ESS that merits additional evaluation.
The Frontal Wishbone: Anatomic and Clinical Implications
Authors: Goldsztein Hernan , Pletcher Steven D. , Reh Douglas D. , Metson Ralph
Published: January 2008

Background

The interfrontal septal cell, which often takes the shape of a wishbone on axial CT scan, was first described by Van Alyea more than 50 years ago; however, its potential role in disease of the frontal sinus was only recently recognized. The purpose of this study was to correlate the incidence and dimensions of this “frontal wishbone” (FWB) with the presence of frontal sinus disease.

Methods

The dimensions, drainage pathways, and disease state of the FWB were measured in 150 consecutive sinus CT scans performed at a tertiary care referral center. Statistical analysis was performed to correlate the FWB configuration to the presence of frontal sinus disease.

Results

A FWB was present in 77.3% of patients. The wishbone drained through a discrete ostium into either the left (54.8%), the right (45.2%), or the bilateral (0.8%) frontal sinuses. In those scans with mucosal thickening or opacification of the frontal sinus (36%), concurrent FWB disease was found in 82%. Patients with a large (>1 cm) FWB in the anterior–posterior dimension were more likely to have a diseased frontal sinus (p = 0.02).

Conclusion

The term FWB is used to describe an air cell within the interfrontal septum, which may play a role in the pathogenesis of frontal sinus disease.
Proteomics of Nasal Mucus in Chronic Rhinosinusitis
Authors: Tewfik Marc A. , Latterich Martin , DiFalco Marcos R. , Samaha Mark
Published: January 2008

Background

Chronic rhinosinusitis (CRS) is among the three most common chronic diseases in North America. The area of proteomics research is providing tremendous insight into the mechanisms of a variety of physiological processes and disease states. The purpose of this study was to evaluate qualitative and quantitative differences in protein content of nasal mucus in patients with chronic hypertrophic sinusitis with nasal polyposis when compared with control subjects.

Methods

A case-control study was performed in a tertiary academic center. Nasal mucus was collected from four patients with CRS and nasal polyposis as well as four control subjects. The protein content was digested using proteolytic enzymes, labeled with iTRAQ reagents, and subjected to mass spectrometry (MS) analysis.

Results

A total of 35 proteins were identified, many of which were related to innate and acquired immunity. Lysozyme C precursor was found to be down-regulated by a ratio (R) of 0.65 (p = 0.016) in CRS patients, as was Clara cell phospholipid-binding protein (R = 0.23; p = 0.0018), and antileukoproteinase 1 (R = 0.47; p < 0.0001). A detailed analysis and characterization of the protein isolates is outlined.

Conclusion

The field of proteomics has great potential in leading to a better understanding of the mechanism of the disease process in CRS. Differences in the expression of proteins related to regulation of immune cells and mediators merit additional investigation.
Moisture Susceptibility of Asphalt Mixtures with Known Field Performance
Authors: Arambula Edith , Masad Eyad , Martin Amy Epps
Published: January 2008

Moisture damage in asphalt mixtures refers to loss in strength and durability due to the presence of water. The level and the extent of moisture damage, also called moisture susceptibility, depend on environmental, construction, and pavement design factors; internal structure distribution; and the quality and type of materials used in the asphalt mixture. This study evaluates the moisture susceptibility of asphalt mixtures with known field performance using dynamic analysis and a crack growth model to characterize the asphalt mixtures and corresponding asphalt mastics. The model parameters were obtained from surface energy measurements, uniaxial dynamic testing for the asphalt mixtures, and dynamic shear testing for the asphalt mastics. Results showed good differentiation between the moisture-conditioned (wet) and unconditioned (dry) specimen behavior and provided a good correlation with the reported field performance of the asphalt mixtures.
Hot-Mix Asphalt Mixtures for Nevada's Intersections
Authors: Hajj Elie Y. , Siddharthan Raj V. , Sebaaly Peter E. , Weitzel Dean
Published: January 2008

The overall objective of this research was to identify a hot-mix asphalt (HMA) mixture with good resistance to rutting and shoving at intersections to be used in the southern part of the state of Nevada. For that purpose, two laboratory evaluations were conducted: (a) evaluation of mixtures from in-service intersections and (b) laboratory evaluation of mixtures with different aggregate gradations. In the first part, field cores from 13 different projects cut from rutted and nonrutted intersections in southern Nevada were investigated in the laboratory to evaluate and compare the volumetric and gradation properties of the mixtures. In the second part, five aggregate gradations were selected for laboratory evaluation on the basis of past performance and results from the first part of this study. On the basis of the analysis of the data generated in this study, the aggregate gradation from the intersections that experienced no rutting showed the best performance in all the permanent deformation tests conducted in this experiment. In addition, the specifications used by the Nevada Department of Transportation for various permanent deformation tests were reviewed, and adjustments have been suggested for the HMA mixtures that are to be used at intersections. Interpretations from dynamic mechanistic analyses of pavements under heavy loads at intersections (with and without interface shear stresses) and laboratory behavior of HMA mixtures were used to arrive at these recommendations.
Estimating Nonmotorized Travel Demand
Authors: An Meiwu , Chen Mei
Published: January 2008

The modeling of nonmotorized travel demand has mostly been conducted at the large spatial level (e.g., city, county, or census tract level) by using data from the Bureau of the Census and the National Household Travel Survey. This paper introduces a modeling approach for estimating the mode share of nonmotorized trips by using data from multiple sources at a finer spatial scale. The correlations between a number of socioeconomic, environmental, and infrastructural factors and the nonmotorized share of the daily commute are analyzed at the level of the census block group. A neighborhood analysis concept is developed to take the length of non-motorized trips into consideration. Multiple regression analysis shows that employment density, the percentage of the student population, median household income, and average sidewalk length together provide the strongest power for prediction of the nonmotorized mode share. The potential applications of the methodology and the implications for data collection are also discussed.
Modeling Fault in Fatal Pedestrian Crashes by Using Various Data Sources
Authors: Spainhour Lisa K. , Wootton Isaac A.
Published: January 2008

Binary logistic regression was used to model fault in 318 fatal pedestrian cases that occurred in Florida in the year 2000. The results were used to classify fault and identify factors that influenced fault. An expert fault assessment served as a control for predicting fault in each crash. The expert assessment team conducted a case review of each traffic crash by using additional data sources, such as traffic homicide reports, diagrams, photographs, accident reconstructions, and site visit notes. The logistic models correctly classified fault in anywhere from 84% to 97% of the cases. The existing Florida Department of Transportation algorithm correctly classified fault in only 56% to 58% of the same cases. Improvements in classification accuracy were shown to stem from two sources: the abundance of the data and the improved accuracy of the data. The mental state of the pedestrian and the driver were shown to be important in determining fault. Exhibiting a mental aberration, such as inattention, distraction, perception or decision error, or intoxication, increased the propensity for fault. Issues such as the number of lanes attempted in a crossing, the age of an individual, being a former vehicle occupant, having limited conspicuity, receiving a citation, and wet roads were also shown to be factors significant in determining fault.
In-Roadway “Yield to Pedestrians” Signs
Authors: Ellis Ralph , Van Houten Ron , Kim Jin-Lee
Published: January 2008

Motorists often fail to yield to pedestrians in marked crosswalks at uncontrolled locations. Several studies, including a recent NCHRP and TCRP study, have demonstrated that the use of in-roadway signs can significantly increase the percentage of motorists yielding to pedestrians at uncontrolled marked crosswalks. The 2003 edition of the Manual of Uniform Traffic Control Devices includes two in-roadway signs that may be installed at uncontrolled locations but does not give precise directions on where to place the sign in relation to the crosswalk. The purpose of the present FHWA study was to compare the effect of placing these signs at the crosswalk, 20 ft in advance of the crosswalk, 40 ft in advance of the crosswalk, and at all three locations on driver yielding behavior. A counterbalanced multielement design was used in this experiment. This design involves the installation of the sign at several different locations in advance of the crosswalk to determine if there is an optimum location for sign placement. After the collection of baseline data at all three crosswalks on Collins Avenue in Miami Beach, Florida, the research team placed the sign at each of the three distances in advance of the crosswalk at each crosswalk location as well as at all three locations together in randomized blocks of trials to control for order effects. The data showed that the sign produced a marked increase in yielding behavior at all three crosswalks and that installation of the sign at the crosswalk line was as effective as or more effective than installation of the sign 20 or 40 ft in advance of the crosswalk. The data also indicated that placement of the sign at all three locations at once was no more effective than placement of the sign at the crosswalk line. These data suggest that the in-road-way sign is likely effective because the in-roadway placement is particularly salient to drivers. Because drivers frequently struck the signs on Collins Avenue, it is recommended that these signs be placed on median islands whenever possible to extend their useful lives.
Instrumenting Pencel Pressuremeter Control Unit to Simplify Data Collection, Reduction, and Analysis
Authors: Cosentino Paul J. , Kalajian Edward , Sundaram Sunil , Misilo Thaddeus J. , Horhota David J.
Published: January 2008

The Pencel pressuremeter control unit was instrumented to simplify digital recording, data reduction, and analysis of soil parameters. Digital signals from the instrumentation were collected through a commercially available data acquisition package, known as an automated pressuremeter (APMT), which produced reduced stress-strain data and allowed operators to determine the critical parameters. The instrumented system saved significant time. Data from numerous tests were evaluated for accuracy. Both clays and sands were included in the comparison. A digital pressure transducer was plumbed into the control unit, and a linear potentiometer was connected directly to the piston to produce digital volumes. The digital equipment improved the accuracy of the pressures more than ten-fold and eliminated gear backlash associated with the existing volume counter. The backlash affects the moduli more than the limit pressures, especially those associated with unload-reload loops of stiffer soils. Pressure-versus-time data for each injected volume increment were evaluated to determine when the pressures stabilized. APMT indicated that the pressure stabilized between 10 and 80 s for the sands and clays evaluated. The volume increment stabilization period was defined as the time required for the pressures to stabilize.
Wireless Shape-Acceleration Array System for Local Identification of Soil and Soil Structure Systems
Authors: Bennett Victoria , Zeghal Mourad , Abdoun Tarek , Danisch Lee
Published: January 2008

Soil and soil structure systems are massive multiphase particulate systems characterized by the development of localized response mechanisms under extreme loading conditions. Identification and analysis of such systems on the basis of inverse boundary value problem formulations and sparse measurements are generally indeterminate. An alternative local inverse problem technique using measurements from the newly developed wireless shape-acceleration array (WSAA) system is presented. Local identification analyses of the constitutive behavior of water-saturated soil and soil structure systems are performed with acceleration and pore pressure records provided by a cluster of closely spaced sensors. The developed novel technique does not require the availability of boundary condition measurements or the solution of an associated boundary value problem. The constitutive behavior at a specific location of a soil or soil structure system is analyzed independently of adjacent response mechanisms or material properties. Numerical simulations and centrifuge tests of a soil-retaining wall system were used to demonstrate the capabilities of this local system identification technique. The combination of the developed WSAA and local identification technique constitute a major step toward autonomous monitoring technology and analysis tools capable of providing a realistic picture of large deformation and acceleration response or failure of soil and soil structure systems.
Effect of Reinforcement on Resilient and Permanent Deformations of Base Course Material
Authors: Abu-Farsakh Murad Y. , Nazzal Munir D. , Mohammad Louay N.
Published: January 2008

Deformational response of base course material under traffic loading is characterized by resilient (recoverable) and permanent (irrecoverable) deformation. A series of repeated load triaxial tests was conducted on unreinforced and geogrid-reinforced crushed limestone samples to evaluate the effects of the geogrid stiffness, location, number of layers, and crushed limestone moisture content and state of stress on the resilient and permanent deformations of these samples at different number of load cycles. Three types of geogrids were used. For each geogrid type, three reinforcement arrangements were investigated. The effect of the moisture content of the crushed limestone was investigated by conducting repeated load triaxial tests on samples prepared at three different moisture contents: optimum moisture content and ±2.5% of the optimum moisture content. Statistical analyses were conducted on the collected data. Results indicated that the geogrid inclusion within crushed limestone samples significantly reduced permanent deformations but did not show appreciable effect on resilient deformations. Improvement was significantly affected by the geogrid stiffness and arrangement. However, the effect of the geogrid stiffness was found to be smaller than the effect of the geogrid arrangement. For stress levels less than the plastic shakedown stress limit, the geogrid had a minimum contribution to the permanent deformation resistance during primary postcompaction stage; however, it significantly increased the permanent deformation resistance during the secondary stage. In addition, the geogrid reinforcement was found to have a small effect on the permanent deformation resistance mechanisms when the imposed stress level was greater than the plastic shakedown stress limit. Results illustrate that change in the moisture content of the crushed limestone material alters the material state of stress and this significantly affects the geogrid improvement.
Performance Evaluation of Bonded Concrete Pavement Overlays after 11 Years
Authors: Mokarem David W. , Galal Khaled A. , Sprinkel Michael M.
Published: January 2008

Concrete overlays were placed on continuously reinforced concrete (CRC) pavement sections of I-295 near Richmond, Virginia, and I-85 near Petersburg, Virginia. A 2-in. bonded portland cement concrete overlay on I-295 was placed to prevent spalling attributable to improper steel depth of the existing CRC pavement, and a 4-in. bonded portland cement concrete overlay on I-85 was placed to increase the structural capacity of the pavement. The CRC pavements were in reasonably good condition when the overlays were placed. Evaluations of the bonded overlays were conducted immediately after their placement in 1995, in 1999, and in 2006 after 11 years in service. The evaluations included bond strength testing between the overlay and the CRC pavement, chain drag testing to detect delamination between the overlays and the pavement, falling weight deflectometer testing to assess the in situ structural capacity of the bonded overlay pavement sections, permeability testing to determine the permeability conditions of the overlays, and skid resistance testing to check the surface texture conditions. The bonded concrete overlays performed well after 4 and 11 years. The results indicate that bonded overlays extended the life of the existing CRC pavements and are expected to last 20 years or more. The experience gained during 11 years is documented and the use of bonded concrete overlays is recommended where the design life can be realized.
Forecasting Transit Speed and Delay for Planning Applications in Florida
Authors: Ryus Paul , Bartee Tara
Published: January 2008

The Florida Department of Transportation sponsors automobile speed and delay studies for the purpose of calibrating regional transportation planning models, so that modeled link speeds more closely reflect existing conditions. In contrast, the models’ bus speeds are typically not calibrated. As a result, it is difficult to assess accurately the impact of future traffic conditions and project alternatives on future bus speeds; this in turn makes it difficult to plan for a more multimodal transportation system in the long term. To address this issue, the department sponsored simultaneous speed and delay studies in 2005 in the Jacksonville region for the automobile and bus modes. Four sets of models were developed from the collected data, which estimate bus speeds as functions of both auto speeds and planning-level attributes (e.g., daily traffic volumes, roadway functional class, and area type), for roadway segments and entire bus trips. The study found a linear relationship between bus and auto travel times (and speeds) across the range of sampled travel times, unlike the current regional model structure, which uses three different linear functions for various ranges of auto speeds. Bus travel times were a consistent proportion of auto travel times during peak and off-peak periods, although absolute travel times were longer during peak periods. Finally, the current model structure was found to underestimate the maximum observed bus speeds in the field. These results are consistent with those of a study conducted in the Tampa Bay area in 2003.
Success and Challenges in Modernizing Streetcar Systems
Authors: Currie Graham , Shalaby Amer
Published: January 2008

On-street running in mixed traffic has been identified as the least desirable right-of-way for light rail and tram systems. While most cities in the developed world have withdrawn streetcar systems, substantial networks have been retained in Melbourne, Australia, and Toronto, Canada. Although some commentators have seen the retention of these systems as visionary, there are substantial challenges to be faced in addressing conflicts between streetcars and rising road traffic. Poor running speeds, unreliability, safety, and difficulties in providing universal access are significant issues for modern streetcar systems. Experiences are described in regard to planning and operating the Melbourne and Toronto streetcar systems. The types of challenges being faced in providing services are contrasted. Programs to address the challenge of creating modern high-quality transit systems out of streetcars are compared. Finally, success strategies in modernizing streetcar systems are identified.
San Diego, California, Trolley's New Green Line
Authors: Bates Toni Botte , Jablonski Paul
Published: January 2008

In July 2005, San Diego, California, Trolley officials and riders celebrated completion of the light rail system's eighth extension. The 6-mi (9.7-km) Mission Valley East project closed the gap in the 53-mi (85.3-km) system and provided service to San Diego State University (SDSU). The project allowed for the introduction of the 19-mi (30.6-km) Green Line, which operates between Old Town and Santee on existing, new, and shared tracks. The Green Line is distinctive in a number of ways. It is a nonradial corridor that does not serve downtown San Diego. It directly serves the 35,000-student SDSU campus and surrounding community through the system's first tunnel and underground station. In addition, the line links a variety of regional activity centers along Mission Valley's intense residential and employment corridor. In fall 2005, the Metropolitan Transit System and the San Diego Association of Governments conducted two surveys and a passenger count to help understand more about who rides the Green Line, why they ride it, and where they are going. Survey results indicate that the Green Line has changed the composition and riding habits of transit users, resulting in high proportions of school trips, increased frequency of transit use, high numbers of choice riders, and high percentages of prepaid fare use. The Green Line has increased transit trips at SDSU by over 350%. The surveys also prompted plans for improvements, including operating later night service, pursuing station modifications that would allow the Green Line to extend into downtown, and considering partnerships with SDSU to expand the college semester pass program.
Personal Rapid Transit Safety and Security on University Campus
Authors: Muller Peter J. , Young Stanley E. , Vogt Michael N.
Published: January 2008

Personal rapid transit (PRT) uses small driverless vehicles operating on dedicated guideways to transport passengers efficiently to their destinations. A study was focused on the safety and security of PRT in a university setting. Safety issues result from accidental causes, and security issues result from deliberate causes, but the effects are similar; both were analyzed according to threats (or hazards) and vulnerabilities. Threats and vulnerabilities were rated according to ASCE's automated people mover standards. Safety data were gathered for the 30-year old Morgantown PRT system at West Virginia University and for surface transportation on the Kansas State University (KSU) campus. KSU has no plans to build a PRT system. Where applicable, these data were used to calibrate the hypothetical PRT system ratings and also used to help determine which of those aspects rated undesirable or, worse, warranted additional mitigating measures. The study concluded that no aspect of PRT posed any significant security or safety issues that had not been successfully mitigated in other forms of public transit. Furthermore, the nature of PRT, in which passengers are aggregated in small groups rather than large groups, provides significant threat deterrence when compared with traditional transit. In addition, using a PRT concept as a shuttle between peripheral parking and central facilities in combination with restricted vehicle access to central facilities significantly decreases the threat exposure for vehicle-born explosive devices.
Advanced Modeling Capabilities for Airport Performance Assessment and Capacity Management
Authors: Zografos Konstantinos G. , Madas Michael A.
Published: January 2008

Airport decision makers face frequently complex decisions related to airport planning, design, and operations. These decisions are highly complicated since they involve a variety of entities processed through the system, a number of different airport elements, and a large variety of airport performance measures such as capacity, delays, safety, security, noise, and cost-effectiveness. Existing airport modeling capabilities suffer from (a) fragmentation between the various airport elements, entities, and their operations; (b) the isolated manner in which the airport performance measures are assessed and modeled; and (c) the lack of user-friendly modeling capabilities and decision support systems adopting a problem-oriented approach for airport decision making and planning. Advanced airport modeling capabilities should be deployed to integrate domain knowledge with tool expertise in assisting airport decision makers to answer frequently arising airport planning questions in an integrated, user-friendly, and problem-oriented environment. The operational concept for an integrated, problem-oriented modeling approach for total airport performance analysis is introduced, the development of a decision support system for airport performance assessment and capacity management is described, and the modeling and decision support capabilities of the system are demonstrated.
Steeper Approach Procedure for Increasing Ultimate Capacity of Closely Spaced Parallel Runways
Authors: Janic Milan
Published: January 2008

The steeper approach procedure (SAP) is investigated as an innovative option for increasing the ultimate arrival capacity of closely spaced parallel runways under the instrument metrological conditions and instrumental flight rules. SAP is based on the two pairs of instrumental landing systems, each enabling the certified aircraft to approach a given parallel runway at either the standard (3°) or steeper (5° to 7°) glide slope (GS) angle. The difference in the GS angles allows application of the air traffic control (ATC) vertical separation rules between the arriving aircraft; this can mitigate the impact of wake vortices on the aircraft in trail separation while on the same or different approach trajectories. A combination of these with the ATC longitudinal and horizontal–diagonal separation rules has the potential to increase the ultimate arrival capacity of closely spaced parallel runways. An analytical model was developed for calculating the arrival ultimate capacity of closely spaced parallel runways. The model inputs are the geometry of given parallel runways, the ATC minimum separation rules, and the aircraft fleets mix characterized by the aircraft wake vortex types and categories, capability of using different GS angles, final approach speeds, and the arrival runway occupancy time. The model output consists of the ultimate capacity of closely spaced parallel runways and its variations in dependence on the mixture of arrivals and departures for a large U.S. airport.
Methodology for Estimating Freight Volume Shift in an International Intermodal Corridor
Authors: Tsamboulas Dimitrios , Moraitis Panayota
Published: January 2008

Facilitating the movement of freight in developing countries is likely to have a significant impact on these countries’ economic development. For these countries, freight modeling is crucial, especially when alternative modes and routes exist, investments in infrastructure are limited, and the objective is to promote environmentally friendly intermodal transportation. However, limited research related to model freight demand is performed in developing countries, compared with the amount of research done in more developed countries. In general, freight transportation demand is a highly variable process over space and time, which precludes the prediction of future scenarios with certainty. This paper presents a methodological framework for the analysis that is required before development of an intermodal (i.e., involving both rail and ship) international transportation corridor. It outlines a simplified methodology for estimating freight volumes on the specific corridor, either in absolute numbers or percentages, when compared with alternative routes. This methodology overcomes issues such as limited availability of data and complexity of trends and relationships of the freight transportation demand characteristics. The resulting estimations can be used to assess whether a new international intermodal transportation corridor is viable and under what conditions. An application is demonstrated for a specific transportation corridor from ports on the Black Sea by maritime and rail connections to Greek ports in the Mediterranean.
Single Allocation Hub Network Design Model with Consolidated Traffic Flows
Authors: Kim Dong Kyu , Park Chang Ho , Kim Tschangho John
Published: January 2008

Economies of scale achieved by consolidating traffic flows are fundamental characteristics of hub networks. In the hub network design problem, then, it is particularly important to quantify cost savings stemming from economies of scale, the operating costs of hub facilities, and the opportunity costs of delays in hub facilities. Because of the NP (nondeterministic polynomial time)-complete nature of the hub network design problem, most previous researchers have focused on the development of heuristic algorithms for approximate solutions. The purpose of this paper is to develop a hub network design model considering economies of scale stemming from consolidation of traffic flows. The model is designed to determine endogenously the cost-decreasing effect resulting from economies of scale and to include several cost components and capacity constraints relative to the particularity of hub networks. The model in this paper is compared with recently published studies using real data. The results of the analysis show that the proposed model can provide a more reliable and realistic representation of real hub networks. This study can not only form the theoretical basis of an effective and rational hub network design but also contribute to the assessment of existing and planned logistics systems.