bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel method for Thermodynamic Study on the Binding of Milk Carrier protein of BLG-A with Cr+3
Authors: Behbehania G. , Divsalar A. , Saboury A.
Published: January 2010

A Novel method for Thermodynamic Study on the Binding of Milk Carrier protein of BLG-A with Cr+3

Thermodynamics of the interaction between Cr3+ with β-lactoglobulin type A (BLG-A) was investigated at pH 7.0 and 37°C by isothermal titration calorimetry. A new method to follow the effect of Cr3+ on the stability of BLG-A was introduced. The new solvation model was used to reproduce the enthalpies of BLG-A+ Cr3+ interactions over the whole range of Cr3+ concentrations. The solvation parameters recovered from the new equation are attributed to the structural change of BLG-A and its biological activity. The results obtained indicate that there is a set of two identical binding sites for Cr3+ ions with positive cooperativity. The association equilibrium constants are 14.39 and 0.49 mM-1 for the first and second binding site, respectively. The enthalpy of binding for one mole of Cr+3 ion to one mole of the binding site on BLG-A (ΔH=104.60 kJ mol-1) is obtained.
Catalytic oxidation of organic pollutants
Authors: Parus Wiesław , Paterkowski Wojciech
Published: January 2010

Catalytic oxidation of organic pollutants

The paper presents the results of the measurements of the catalytic activity of V2O5/TiO2 and MoO3/TiO2 catalysts (8,10,12 and 15 wt % of V2O5 or MoO3 on TiO2 - anatase, respectively), prepared in our laboratory, in the complete oxidation (combustion) process of chosen volatile organic pollutants of the air such as methanol and n-butyl acetate. The activity of these catalysts was compared with the activity of industrial catalysts: supported platinum - Pt-p (0.15 wt % of Pt on γ-Al2O3) and MCA (15 wt % of CuO and 6 wt % of ZnO on γ-Al2O3). The investigations were carried out in the kinetic region (powder of the catalysts with the diameter in the range of 1.02-1.2·10-4 m) and for the chosen catalysts also in the diffusion region (the grains of the catalysts having the diameter of 2.5·10-3 m). On the basis of the obtained results the analysis of the process was performed.

It has been stated that reaction rate is well-described by the first order equation in relation to the methanol or n-butyl acetate concentration. On the basis of the obtained results in the kinetic region for all the applied catalysts the parameters of Arrhenius equation were determinated.

The comparison of the results for the kinetic region with the results for the diffusion region for the chosen catalysts allowed the calculation of the effective coefficients of diffusion. The parameters of Arrhenius equations as well as the effective coefficients of diffusion show a good correlation with the values obtained for the catalytic combustion of other organic pollutants of the air.

The measurements were carried out using a flow tubular reactor. The flow rate of the reaction mixture was kept constant 20 dm3/h (5.56·10-6 m3/s) in each test, using the space velocity of 20 s-1. It has been stated that the use of the applied catalysts led to the almost total oxidative destruction of both pollutants. Only H2O and CO2 were found as the final products of the reaction. The complete oxidation of the methanol process runs at the lower temperature than that of the complete oxidation process of n-butyl acetate. The most active at the combustion of methanol was the Pt-p catalyst. It demonstrates a comparable activity to molybdenum - titanium catalysts and the slightly lower activity than vanadium - titanium catalysts in the combustion of the n- butyl acetate process. The MCA catalyst was less active than the others in the oxidation of both compounds. The structures of the catalysts were tested using the X -ray analysis (XRD), infrared spectroscopy and scanning microscopy (SEM).

The results of the investigations show that V2O5/TiO2 and MoO3/TiO2 catalysts, especially the most active of them the 8% V2O5/TiO2 catalyst can be used in industrial systems for the purification of the air and industrial waste gases with VOCs, replacing the more expensive noble metals supported catalysts.
Topical and prospective processes of acetoxylation
Authors: Lewandowski Grzegorz , Bartkowiak Marcin , Milchert Eugeniusz
Published: January 2010

Topical and prospective processes of acetoxylation

The latest acetoxylation processes have been described in this work: oxidative acetoxylation of propene to allyl acetate, acetoxylation of propene to propene glycol and its acetates, acetoxylation of methyl tert-butyl ether and oxidative acetoxylation of cyclohexene by hydrogen peroxide. Acetoxylation of 1,3-butadiene, isobutene and toluene were presented together with a short description of the acetoxylation catalysts.
Mixing system for highly concentrated fine-grained suspensions
Authors: Moravec Jiří , Jirout Tomáš , Rieger František , Krátký Lukáš
Published: January 2010

Mixing system for highly concentrated fine-grained suspensions

The mixing equipment for highly concentrated fine-grained suspensions must be designed differently from the equipment in which a suspension with a low concentration of the solid phase or bigger particles is mixed. It is due to the different rheological properties of the suspensions. In this work we are trying to find a suitable mixing system for a highly concentrated fine-grained suspension. The aim was to determine an effect of particular geometrical parameters of the tested mixing systems on a suspension process, especially from the energetic viewpoint. The energetic costs of all the used mixing systems were compared on the basis of the power consumption which was necessary for reaching the state of sufficient suspension movement in the whole mixed bulk. As a result, it was confirmed that multistage impellers can be used even in standard vessels (with a liquid level height equal to a vessel diameter) with a profit. During experiments, the state of sufficient movement was determined by a visual observation of the suspension at the vessel bottom, at the wall and also at the suspension level.
Effect of Nitrogen Fertilization on the Yield and Quality of Field-grown Leaf Lettuce for Spring Harvest
Authors: Chohura Piotr , Kołota Eugeniusz
Published: January 2010

Effect of Nitrogen Fertilization on the Yield and Quality of Field-grown Leaf Lettuce for Spring Harvest

Two field experiments with leaf lettuce were carried out in 2006-2008. Each of them was set up in a random sub-block design in 3 replications and a two-factorial system. The first factor represented different nitrogen doses that were used to obtain the required N level in the soil prior to planting the seedlings, the levels being: 50, 100 and 150 mg N·dm-3. The second factor incorporated 4 nitrogenous fertilizers which were different in terms of chemical composition, and, more importantly, contained different nitrogen forms for introduction to the soil: ammonium nitrate 34% N-[NH4NO3], calcium nitrate 15.5% N-[Ca(NO3)2xH2O+NH4NO3], ammonium sulphate 20.0% N-[(NH4)2SO4], and ENTEC 26% N-[NH4NO3+(NH4)2SO4+0.8% DMPP]. Two varieties of leaf lettuce were used: Casabella (of the type Lollo Bionda) with green leaves, and Klausia (of the type Lollo Rosa) with red leaves. The best sources of nitrogen for the lettuce plants were the fertilizers ENTEC 26 and ammonium nitrate, which in contrast to calcium nitrate and ammonium sulphate made it possible to obtain significantly higher yields of lettuce. Irrespective of the kind of the nitrogenous fertilizer used, increasing the concentration of nitrogen in the soil from 50 mg N·dm-3 to 100 mg N·dm-3 resulted in a significant increase in the marketable yield of lettuce. At 150 mg N·dm-3 this yield remained at a level similar to that at 100 mg N·dm-3. The lettuce fertilized with ammonium sulphate was marked by the lowest mean nitrate content in the leaves before harvest. The use of gradually higher doses of nitrogen resulted in a reduced dry weight content and lower levels of total and reducing sugars in lettuce leaves. With respect to yield size and quality, the recommended concentration of nitrogen in the soil for leaf lettuce should not exceed 100 mg N·dm-3.
Some Quality Characteristics Including Isothiocyanates Content of Horseradish Cream as Affected by Storage Period
Authors: Kosson Ryszard , Horbowicz Marcin
Published: January 2010

Some Quality Characteristics Including Isothiocyanates Content of Horseradish Cream as Affected by Storage Period

During two-year experiments the effects of long-term storage at three temperature levels (2°C, 8°C and 18°C) on content of some nutritive components, including pungent compounds - isothiocyanates (ITC), in processed horseradish (cream) were studied. The significant changes of content of reducing sugars, total isothiocyanates and color indexes in horseradish cream after its storage were noted. The higher temperature of storage the higher content of reducing sugar in horseradish cream was observed. Content of allyl isothiocyanate (AITC) and especially phenylethyl isothiocyanate (PEITC) in fresh horseradish cream was lower in comparison to non-processed horseradish roots. Contents of both isothiocyanates decreased significantly during storage period. The highest decline of isothiocyanates level was observed during first four months of storage. The highest temperature of storage studied (18°C) caused faster decline of both isothiocyanates concentration in horseradish cream. To maintain the human health-promoting compounds in processed horseradish, as well as to keep sensory attributes (color), it is suggested to store horseradish cream in cold condition.
The Influence of Postharvest Treatment and Type of Packaging on Quality and Storage Ability of Cauliflower (Brassica oleracea L. var. botrytis)
Authors: Grzegorzewska Maria , Kosson Ryszard
Published: January 2010

The Influence of Postharvest Treatment and Type of Packaging on Quality and Storage Ability of Cauliflower (Brassica oleracea L. var. botrytis)

The influence of postharvest hot and cold water treatments on the quality and storage ability of cauliflowers were studied. Also the usefulness of different type of unit packaging for cauliflower storage was compared. The cauliflower heads of Fremont F1 cultivar, after different treatments, were stored at 0°C for six weeks. Postharvest hot water treatment with temperature 38-54°C has not influenced on the storage ability of cauliflower. The heads treated with water of temperatures 50°C and 54°C have shown after six weeks of storage higher rooting, greater compactness loss and colour changes than not treated heads. Postharvest cooling of heads with ice water has not affected quality after storage. It was found that the type of packaging influenced on cauliflower quality after storage. The best quality of cauliflowers after 28 and 42 days of storage was maintained in P-Plus film bags and PE film bags with perforation (8 holes ϕ0.04 cm). The satisfactory quality was maintained also in case of heads wrapped in stretch film and stored for 42 days. The unsatisfactory quality due to heads darkening was found for cauliflowers kept in tightly sealed PE film bags.
Taxes, Transfers, and Canadian Income Inequality
Authors: Frenette Marc , Green David A. , Milligan Kevin
Published: January 2010

In this paper, we investigate the relationship between the substantial changes in tax and transfer programs and the movements in after-tax income inequality over the 1980s and 1990s. We show that in the 1980s, tax and transfer programs became more redistributive, offsetting substantial increases in market income inequality. In the 1990s, the tax and transfer system stopped undoing the increases in market income inequality, leading after-tax income inequality to rise. Even so, tax and transfer programs were more redistributive in 2000 than in the 1980s. Much of the changes occurred at the provincial level, with social assistance payments first increasing (in the late 1980s) then decreasing (in the late 1990s) and with surtaxes on high-income earners being first imposed and subsequently removed.
Policy and Practice Regarding Adoption by Sexual and Gender Minority People in Ontario
Authors: Ross Lori E. , Epstein Rachel , Goldfinger Corrie , Yager Christina
Published: January 2010

In 2000, changes to the Ontario Child and Family Services Act made it possible for lesbian and gay couples to jointly adopt a child. This research investigated the extent to which Ontario adoption agencies and licensees are supportive of adoption by sexual and gender minority people. Results indicate that while overall, there is support for sexual and gender minority adopters in Ontario, disparities exist on the basis of agency type (public vs. private vs. international; religious/cultural affiliation) and location (urban centres vs. smaller communities), as well as the applicants' identity (lesbian/gay vs. other minority identities). Policy and practice implications of these findings are be discussed.
Review of the Report of the Expert Panel on Older Workers
Authors: Beach Charles M.
Published: January 2010

This paper offers a general evaluative review of the report of the Expert Panel on Older Workers of July 2008. It is a balanced, clearly written report that emphasizes the importance of individual choice, flexible work arrangements, reduced barriers to employment of older workers, and regional mobility. But the report does not highlight the important gender dimension operating in retirement decisions and in older worker job displacements. The perspective of the report is that of labour economics, but it could have benefited from a more public economics perspective for guiding principles on job displacement issues.
Population Aging, Older Workers, and Canada's Labour Force
Authors: Denton Frank T. , Spencer Byron G.
Published: January 2010

The Expert Panel on Older Workers made recommendations designed to increase the labour force participation of older workers. We explore the implications that higher rates of older-worker participation would have for the overall size and age composition of the labour force, for the productive capacity of the economy, and for the incomes of Canadians. Our purpose is to assess the potential impact that increased participation of older workers might have in offsetting any anticipated adverse effects of population aging on standards of living.
The Report of the Expert Panel on Older Workers: How Should Public Pensions Be Improved?
Authors: Baker Michael , Milligan Kevin
Published: January 2010

The recent report of the Expert Panel on Older Workers provided an important focus on retirement income policy. We comment here on the Panel's recommendations that aim to support continued work by older Canadians. We find that the focus on removing barriers to continued work is well-motivated, practical, and sensible. Particular attention must be paid to the full actuarial cost of reforms, however. Overall, the recommendations provide a sterling benchmark for future efforts to reform Canada's retirement income system.
Comparison of Stress States and Paths
Authors: Rinehart Robert V. , Berger John R. , Mooney Michael A.
Published: January 2010

Vibratory roller-based measurement of soil stiffness during intelligent compaction and continuous compaction control can be used for performance-based quality assurance of unbound materials. To realize this potential, the relationship between the roller-measured soil stiffness and the soil modulus, particularly resilient modulus, must be understood. The in situ stress states and paths experienced by soil beneath a vibratory roller were compared with stress states and paths during laboratory resilient modulus testing. Observed stress fields within the 1-m depth of influence varied considerably for both vertically homogeneous embankment soil and layered base over subgrade conditions. During low excitation force vibration, roller-induced levels of deviator stress were notably greater than those used during laboratory resilient modulus testing, whereas levels of mean stress were less. Predicted modulus variation with depth was strongly influenced by modulus function parameters. With typical granular soil parameters, modulus was found to be constant with depth for the embankment conditions. With modulus parameters of more fine-grained behavior, modulus increased considerably with depth.
Horizontal Drains in a Clay–Landslide Stabilization Test Program
Authors: Black Brent A. , Machan George , Poelma Michael
Published: January 2010

During highway construction, a large ancient landslide was discovered within the Cattaraugus Creek Valley in western New York State. An active landslide was contained within this ancient landslide complex. The depth of the slide is approximately 30 m (100 ft). The purpose of the horizontal drain installation test program was to determine the feasibility of reducing pore-water pressures within a clay stratum by using dewatering techniques. The test demonstrated that horizontal drains could be installed with moderate difficulty. More than 90% of the installed horizontal drains produced discharge water. Flow rates were low but consistent with horizontal drain experience in clayey soils. Most of the original working drains were still discharging water 6 months after installation. Several of the piezometers appeared to have responded to the horizontal drains. One piezometer showed a gradual drawdown of 3.8 m (12 ft) during the first 6 months. A reduction in the rate of slide movement was also observed.
High-Capacity Piles at the Stony Creek Bridge Project
Authors: Liebich Brian A.
Published: January 2010

High-capacity piles (HCPs) offer a highly attractive foundation option to geotechnical designers, but regular acceptance and wider implementation remain elusive. Until recently, large-diameter high-capacity piling was mainly used in the offshore oil industry; there the unique environment and design requirements led to piling where capacity did not need to be verified. When larger-diameter piling began to emerge as a cost–benefit option onshore, little was known about the unique behavior. Although there were no scalability problems in dynamic stress measurement and energy calculations, engineers found dynamically estimated pile capacity to be unreliable. To provide the required capacity information for HCPs, the California Department of Transportation developed static axial pile load tests for piles up to 8,000 kips (35 MN). Through a case study of the Stony Creek Bridge Project, the California Department of Transportation presents its experience with the advantages and limitations of HCPs. The 8-ft (2.44-m) diameter and 170-ft (51.8-m) long steel piles at the Stony Creek Bridge are reputed to be the largest piles ever driven on land.
Using Dynamic Modulus Test to Evaluate Moisture Susceptibility of Asphalt Mixtures
Authors: Nadkarni Atish A. , Kaloush Kamil E. , Zeiada Waleed A. , Biligiri Krishna Prapoorna
Published: January 2010

The stripping in of hot-mix asphalt (HMA) is assessed by AASHTO T283 by means of the indirect tensile strength test. The tensile strength ratio (TSR) is used as the criterion for strength retention after sample conditioning. In recent years, the dynamic modulus ( E*) test, conducted according to AASHTO TP62-03, has gained wider use in the pavement community for two reasons: it is a major input into the Guide for Mechanistic–Empirical Design of New and Rehabilitated Pavement Structures and is being used as a simple performance test indicator. The objective of this study was to assess whether the E* laboratory test can be used as a replacement test property for indirect tensile strength in AASHTO T283. Because the E* test is nondestructive, unlike the indirect tensile strength test, the advantage would be that the same specimens could be used before and after moisture conditioning. The scope of work in this research included conducting a laboratory testing program on several types of asphalt mixtures by means of both test procedures. All mixtures were obtained from construction projects in the field. A unique aspect of this study was that some of the mixtures failed in the field after stripping. The E* tests were used to determine the percent of retained stiffness, a term referred to as E* stiffness ratio (ESR). Results of both TSR and ESR conducted on the same mixtures were compared and statistically analyzed. The analysis indicated that there was no statistically significant difference between the measured TSR and ESR values for the same mixture. The correlation obtained between the two ratios had good measures of accuracy. It was concluded that the ESR can potentially replace TSR testing to assess field moisture damage for asphalt mixtures. The recommendation was to continue the testing program and expand the database for future analysis.
Forensic Investigation and Validation of Energy Ratio Concept
Authors: Timm David H. , Sholar Gregory A. , Kim Jaeseung , Willis J. Richard
Published: January 2010

The energy ratio (ER) concept was recently introduced as an accurate predictor of top-down cracking performance in Florida. Initial evaluation of ER with field projects in Florida confirmed its ability to distinguish between cracked and uncracked sections. To evaluate and validate the ER concept further, the Florida Department of Transportation designed and constructed two test sections at the National Center for Asphalt Technology test track. The primary difference between the two sections was the binder used in the upper two lifts. The first section used PG 67-22 and the second section used PG 76-22, which resulted in an ER of about twice the size. The section with the lower ER value cracked first and more extensively, though both sections experienced top-down cracking. This study was intended not only to look at ER as the primary factor to differences in performance but also to evaluate forensically the sections by using in situ strain measurements, coring, and interface bond strength testing. The strain regimes and bond strengths were found to be approximately equal between the sections, a finding that further validated the ER as a good predictor of top-down cracking performance.
Evaluation of Embedded Discontinuity Method for Finite Element Analysis of Cracking of Hot-Mix Asphalt Concrete
Authors: Wu Rongzong , Denneman Erik , Harvey John
Published: January 2010

Cracking is a major source of distress in hot-mix asphalt (HMA) pavements. Various approaches have been proposed to describe crack initiation and propagation in HMA. This paper evaluates a finite element analysis technique that uses the embedded discontinuity method (EDM) for model cracking. The purpose of this study is to identify the strengths and potential weaknesses of the approach and investigate its applicability in general crack simulation for HMA pavements. An alternative formulation of EDM is adopted to make the approach easier to understand. The cohesive-crack model is used to describe development of HMA cracking. Numerical examples are presented to demonstrate the ability of EDM to simulate uniaxial-tension, three-point bending, and semicircular beam bending tests. It is shown that EDM is a promising finite element analysis technique, but additional research is needed to make it more robust.
Precision of AASHTO TP62-07 for Use in Mechanistic–Empirical Pavement Design Guide for Flexible Pavements
Authors: Bennert Thomas , Williams Stacy Goad
Published: January 2010

In the Mechanistic–Empirical Pavement Design Guide (MEPDG), one of the most important material inputs for designing flexible pavements is the dynamic modulus ( E*). Currently, AASHTO has provided a provisional test specification for measuring the E* of hot-mix asphalt mixtures, AASHTO TP62-07 [Standard Method of Test for Determining Dynamic Modulus of Hot-Mix Asphalt (HMA)]. Under AASHTO TP62-07, recommendations are provided for sample preparation–compaction, measurement system, testing conditions–procedures, and calculations. Unfortunately, information regarding the general precision of the test method does not exist. With many different test machines capable of conducting AASHTO TP62-07 and the importance of E* in flexible pavement design, an understanding of the general precision of the test method and its influence on the MEPDG is needed. This paper describes the results of a round-robin study conducted to address the need for a precision-type statement for AASHTO TP62-07. Seven laboratories, all having equipment compliant with the specifications in AASHTO TP62-07, were asked to laboratory age, compact, prepare, and test six HMA test specimens according to the provisions in AASHTO TP62-07. A statistical analysis was conducted on the test data in a precision statement environment. On the basis of the test results, an initial precision statement for AASHTO TP62-07 was generated and presented. The test results for the seven different laboratories were also used as inputs in the MEPDG to evaluate the relative differences in predicted pavement distresses. Results from the precision evaluation were used to recommend modifications to AASHTO TP62-07 to promote greater precision in different testing laboratories and the results were reevaluated in the MEPDG.
Evaluation and Application of Long-Lasting Asphalt Mixture
Authors: Ma Xiang , Ni Fujian , Chen Rongsheng , Dong Qiao
Published: January 2010

The application of a “long-lasting” asphalt mixture was studied in this paper. The performance of asphalt mixtures made of three types of binders (unmodified, modified styrene–butadiene–styrene, and modified long-lasting) was evaluated through a series of laboratory tests and test road investigations. Both conventional asphalt test methods and Super-pave® PG test methods were employed to evaluate the performance of the three binders. Three types of gradations were employed to make the mixtures. The splitting, dynamic modulus, wheel-tracking, and repeated-load permanent-deformation tests were conducted to evaluate the mechanical properties of the mixtures. The low-temperature performance was also evaluated to verify the applicability of the long-lasting mixture. The mechanical performance of the mixture was evaluated in relation to the amount of improvement the long-lasting asphalt mixture offered compared with the other types of mixtures. On the basis of the laboratory study, test roads with different pavement structures were constructed and investigated after 1 year of service. Laboratory test results showed that the mixture made of the modified PG 82-22 long-lasting binder, which demonstrated good properties for tensile strength and high-temperature stability, exhibited 25% higher splitting strength and better rutting resistance. Investigation of test roads showed that the pavement rutting resistance was improved significantly by using the long-lasting asphalt mixture in the pavement structures, especially in the intermediate layer. The long-lasting asphalt mixture was recommended for use in heavy traffic, in high-temperature areas, and on steel bridge decks because of its excellent rutting resistance and good mechanical properties.
Field and Laboratory Evaluation of Fracture Resistance of Illinois Hot-Mix Asphalt Overlay Mixtures
Authors: Kim Minkyum , Buttlar William G. , Baek Jongeun , Al-Qadi Imad L.
Published: January 2010

A major study of reflective cracking of asphalt overlays that are used in conjunction with interlayer systems for reflective-crack control was recently completed. In this cooperative study at the Illinois Center for Transportation, three field projects in central Illinois were selected and extensive coring was performed. Six fundamentally different types of hot-mix asphalt overlay mixtures, which were expected to demonstrate significantly different levels of fracture resistance, were obtained from coring. To evaluate the fracture resistance of these mixtures in the field and the laboratory, visual field crack surveys and a series of advanced laboratory tests were conducted. This paper presents field performance evaluation results for the performance–benefit ratio and laboratory performance evaluation results for creep stiffness ( St), complex modulus ( E*), and disk-shaped compact tension fracture energy ( Gf). Field performance of pavement sections with premium overlay mixtures was found to be superior to those sections containing conventional overlay materials. The polymer-modified overlay section in one of three projects was found to have performance inferior to that of the unmodified control overlay section of the same project. This tendency was detected by the Gf test but not by the St or the E* tests. The St and Gf values obtained for the interlayer mixtures were consistent with results typically obtained on short-term aged specimens, validating the appropriateness of the coring and testing approach used here as a forensic investigation tool and indicating that little aging had occurred in the bottom of the overlay system.
Effective Temperature for Analysis of Permanent Deformation and Fatigue Distress on Asphalt Mixtures
Authors: El-Basyouny Mohamed , Jeong Myung Goo
Published: January 2010

The determination of a single test temperature for asphalt mixtures to simulate major distresses on flexible pavement is quite significant in characterizing asphalt mixtures. It is apparent that the practical use of a single temperature would reduce testing needs as well as relevant analysis efforts. Effective temperature ( Teff) can be defined as a single test temperature at which an amount of distress would be equivalent to that which occurs from the seasonal temperature fluctuation throughout the annual temperature cycle. The primary goal of this study was to develop the Teff for permanent deformation and fatigue cracking of asphalt mixtures. The predicted distress for both permanent deformation and fatigue cracking that is used to optimize the Teff models and to find optimal coefficients was obtained by running the latest version of the Mechanistic–Empirical Pavement Design Guide (MEPDG). A feature of the developed Teff models is that they incorporate comprehensive climatic characteristics as well as loading frequency. By incorporating those parameters, it was observed that the model is well correlated with the MEPDG distress results. Therefore, the use of the Teff models is recommended as a means to suggest a testing temperature in the simple performance test (SPT) for the distresses. This research work addresses the integration of the MEPDG methodology (NCHRP 1-37A and NCHRP 1-40D) with the SPT (NCHRP 9-19) to develop the Teff models for the two distresses. Furthermore, the Teff methodology will be incorporated into the performance-related specification being developed (NCHRP 9-22).
Assessment of Traffic Signal Maintenance and Operations Needs at Virginia Department of Transportation
Authors: Chen Wenling , Henley Larrie , Price Jeff
Published: January 2010

Budgeting for the maintenance and operations (M&O) of traffic signal assets can be done in many ways. Systematic, data-driven approaches are applied to various extents in transportation agencies. However, little has been documented regarding signal resource allocation practices. A traffic signal needs assessment framework recently developed by the Virginia Department of Transportation to support signal M&O funding allocation is presented. The framework offers the potential for incorporating several performance measures into the needs assessment process, including mean time between failures, mean time to repair, average signal component service life, average remaining service life, and share of preventive maintenance costs with respect to overall maintenance costs. Through adjustment of related parameters, the needs assessment framework allows users to set performance targets against key signal system performance measures and compare needs for meeting various performance scenarios.
Three-Dimensional Mapping of Inductive Loop Detector Sensitivity with Field Measurement
Authors: Day Christopher M. , Brennan Thomas M. , Harding Matthew L. , Premachandra Hiromal , Jacobs Allen , Bullock Darcy M. , Krogmeier James V. , Sturdevant James R.
Published: January 2010

Inductance loops continue to be the most widely used sensing device for vehicle detection. Several different loop geometries are commonly used, but scant technical design literature quantifies their field of detection and sensitivity. Three-dimensional maps of loop response sensitivity based on field measurement with loops installed in asphalt are presented. Loop response was characterized for different metal objects at various heights from the pavement surface. Sensitivity maps were generated for 6-ft circular, 6-ft octagonal, 20-ft octagonal, and 20-ft quadrupole loops. From the field observations, it is concluded that the claims of increased vehicle sensitivity for quadrupole loops first published in the 1970s are inaccurate for most vehicles and quadrupole loops are in fact less sensitive than comparatively sized rectangular loops.
Active and Passive Bus Priority Strategies in Mixed Traffic Arterials Controlled by SCOOT Adaptive Signal System
Authors: Oliveira-Neto Francisco Moraes , Loureiro Carlos Felipe G. , Han Lee D.
Published: January 2010

In recent years, bus priority techniques for signals controlled by traffic management centers have become a viable alternative to reduce passenger delays at signalized intersections, especially in mixed traffic corridors. However, before any bus signal priority strategy is deployed in such corridors, the impacts on the different users of the system should be evaluated. The main objective of this work was to assess the operational performance of passive and active bus priority techniques in fixed and real-time signal systems of one of the main arterial corridors in Fortaleza, Brazil. As a secondary objective, it also evaluated the operational benefits of a SCOOT adaptive signal control system, comparing it with well-adjusted fixed-time plans optimized by TRANSYT, for periods of medium and high traffic volumes. In the evaluation of alternative scenarios, the following performance measures were considered: vehicle delay and number of stops simulated by SCOOT, as well as bus and automobile travel times observed in the field during the operation of each scenario. The results did not favor the adoption of passive and active priority schemes in the studied corridor; this led to the conclusion that SCOOT's real-time control, programmed for a good signal progression of the general traffic (buses and automobiles), is the best signal control strategy for an arterial corridor similar to the one under analysis.
Recommended Tolerances for Magnetometer Orientation and Field Calibration Procedure
Authors: Ernst Joseph M. , Ault Aaron , Krogmeier James V. , Bullock Darcy M.
Published: January 2010

Magnetometers are increasingly being deployed for traffic detection in both fixed wired and wireless installations around the United States. Magnetometers respond to local magnetic field disturbances from the ambient magnetic field of the earth, and this response may be expected to depend on the relative orientation of the magnetometer axis and the direction of the earth's magnetic field lines at the point of deployment. As documented by U.S. Geological Survey (USGS) maps, the declination and inclination of the earth's magnetic field vary significantly over the continental United States, yet there is no traffic engineering design literature characterizing the effect of geographic magnetic field variation on magnetometer detection performance. This study briefly reviews the scientific theory, identifies the magnetometer installation parameters of most importance, and characterizes their impact on performance. In addition, recommendations are based on USGS data, which can be used to develop specifications for installation, testing, and acceptance of magnetometer-based detection technology. Finally, a simple procedure for field calibration of sensor orientation in a conduit to near-optimal rotation angle is presented.
Optimizing Signal Timings from the Field
Authors: Stevanovic Aleksandar , Stevanovic Jelka , Martin Peter T.
Published: January 2010

Traditionally, when traffic signals are retimed, a significant difference is seen between signal timings recommended by optimization software and those implemented in field controllers. Those two sets of signal timings rarely match each other, and often a manual process is involved in transferring the data to and from the field controllers. A method is presented: signal timings are downloaded from field controllers, optimized by a software package, and then uploaded to field controllers. The method is VISGAOST, a stochastic optimization program, working with VISSIM–ASC/3 software-in-the-loop simulation to optimize the signal timings obtained from the field. The method was applied to optimize signal timings for a five-intersection urban arterial segment in West Valley City, Utah. Traffic operations simulated by a high-fidelity VISSIM represented field observations reliably. After thousands of potential signal timings were evaluated, VISGAOST found a better set of signal timings than those used in the field. The final signal timings were tested for robustness under fluctuating traffic in microsimulation. The test results show that these optimized signal timings are more robust than those used in the field. Further applications of the method are needed to test the field performance of the signal timings optimized by VISGAOST.
Distributed Ethernet Network of Advanced Pedestrian Signals
Authors: DeVoe Dustin , Giri Sanjeev , Wall Richard W.
Published: January 2010

For more than 60 years, traffic signals have used direct wire connections between the traffic controller cabinet and the signals and detectors dispersed throughout the intersection. A network-based approach is reported for distributed control and sensing of traffic signal devices. The motivation of this research has been to improve safety and performance while reducing the cost of a signalized intersection installation. An Ethernet-based network architecture is presented that uses the National Transportation Communications for Intelligent Transportation Systems Protocol (NTCIP) for real-time signal control combined with the IEEE 1588 precision time protocol for robust operation of safety-critical applications synthesized into the term “smart signals.” The investigation focuses on improving accessibility and safety for pedestrians through the use of smart signals. The smart signal paradigm is the basis of an enabling technology that permits complex functioning signals and detectors with self-test capability. The bidirectional communication provides the ability to monitor the operational status of signals and detectors that are currently unobservable by automated traffic controls. The elements of network messaging that enable NTCIP to be used for real-time intersection signal control are presented. The concerns of signal outputs being generated outside the scope of observation for malfunction management units are addressed by implementing a deterministic network. The time performance of the system is evaluated for Simple Network Management Protocol and Simple Transportation Management Protocol network messages. The results of testing on the global network time synchronization are presented and show that inexpensive microprocessors can achieve stable long-term time division multiplexed operation with 100-μs accuracy.
Comparison of Before–After versus Off–On Adaptive Traffic Control Evaluations
Authors: Kergaye Cameron , Stevanovic Aleksandar , Martin Peter T.
Published: January 2010

An adaptive traffic control system, the Sydney Coordinated Adaptive Traffic System (SCATS), was installed in Park City, Utah, to improve traffic performance at its network of signalized intersections. A field evaluation of the previous time-of-day actuated–coordinated signal timings was conducted before SCATS installation to compare the two systems. However, the post-SCATS field evaluation could not occur until two additional signals were installed and several other changes were made to the network. Two years after the original pre-SCATS field evaluation, the network was reevaluated with an off–on technique analogous to a before–after study. The signal timings and parameters in the off condition forced SCATS to use time-of-day actuated–coordinated control, similar to the before study but with timings readjusted for the additional signals and changed traffic conditions. The performance gains with SCATS on were measurably greater than those with SCATS off for travel time and number of stops and greater overall for stopped delay. These data provided the transportation agency with results anticipated by its traffic engineers. However, the original field evaluation data from 2 years earlier provided a less distinct conclusion. A methodology is presented to determine the relevance of an off–on study in place of a before–after study. The results show that “before” and “off ” data sets behave consistently 62.5% of the time. This value provides a basis of support for using off data, which better represent before signal timings on an after network. It also quantifies sensitivity to changes in the network, which are substantial in this case.
Safety Evaluation for Intergreen Intervals at Signalized Intersections Based on Probabilistic Method
Authors: Tang Keshuang , Nakamura Hideki
Published: January 2010

This study presents a probabilistic safety estimation approach based on traffic conflict technique. The study aims to investigate the impacts of the German signal control policy and intergreen design method on safety during intergreen intervals at signalized intersections in Japan. To facilitate application of the policy, the uncertainty of input variables and of safety itself, indicated by the postencroachment time, was analyzed first by means of field data collected at 12 typical intersections in Japan and Germany. A few case studies were then examined with Monte Carlo simulation. The results indicated that safety during the intergreen interval and its reliability might significantly drop if inter-green times were simply changed from the values based on the Japanese method to the values based on the German method without supplementary countermeasures. However, safety as well as reliability can be maintained if the Japanese control policy is completely replaced with the German one.
Adapting Travel Models and Urban Models to Forecast Greenhouse Gases in California
Authors: Johnston Robert A. , Roth Nathaniel , Bjorkman Jackie
Published: January 2010

This paper reviews the California Global Warming Solutions Act, which motivates both urban modeling by countywide agencies and the modeling of energy use in buildings and travel and the resultant greenhouse gases (GHGs). The authors identify principles for urban models and travel models, as applied to countywide land use plans and transportation plans. Two urban models, UPlan (a simple one) and PECAS (a complex one) were developed by the authors and are outlined here. The energy use and GHG impacts calculator, which will take as an input floor space data from UPlan or PECAS, is described. The methods used in this calculator and how it will be applied within the two urban models are described. The UPlan implementation is described in detail and an example given. Finally, the limits of UPlan are identified and an explanation for how PECAS may be able to perform all of the economic evaluations called for in the California Climate Act is provided.
Intrametropolitan Location of Business Establishments
Authors: Maoh Hanna , Kanaroglou Pavlos
Published: January 2010

A model for location choice of business establishments is presented for the city of Hamilton, Canada. The model is developed with data from the Business Register of Statistics Canada, the Canadian census, and other ancillary geographic information system information that is produced by a private organization called DMTI Spatial. Using the bid–choice theory, the authors estimate multinomial logit models to study and explain the location choice behavior of individual business establishments with fewer than 200 employees for the period 1996 to 1997. Similar analysis is performed for the period 2001 to 2002. Estimation results suggest that commercial business district, highway, and mall proximities; population density; new residential development; and agglomeration economies influence the location decision of business establishments. The results also point to the existence of land use specialization and firm clustering. Using interaction terms in the specification of the location choice utilities is very effective in teasing out the impacts of firm heterogeneity on the location choice decision of individual firms. Finally, the findings from the two periods examined suggest an overall consistency in location choice behavior over time.
Understanding Residential Mobility
Authors: Eluru Naveen , Sener Ipek N. , Bhat Chandra R. , Pendyala Ram M. , Axhausen Kay W.
Published: January 2010

Residential relocation or mobility is a critical component of land use dynamics. Models of land use dynamics need to consider residential relocation or mobility behavior of households to be able to predict population demographics land use patterns that are critical to activity and travel demand forecasting. Unfortunately, little is known about residential relocation behavior at the disaggregate level, in terms of both the reasons for relocation and the duration of stay at a given residential location. This paper aims to fill this gap in knowledge by formulating and estimating a joint model of the reason for residential relocation and the duration of stay at a location. The model is estimated on a data set derived from a survey conducted in Zurich, Switzerland, that captures information about residential moves over a 20-year period spanning 1985 to 2004. The paper provides elasticity estimates demonstrating how the model can be applied to evaluate impacts of changes in exogenous factors on residential mobility events.
Dynamic Origin–Destination Estimation Using Dynamic Traffic Simulation Model in an Urban Arterial Corridor
Authors: Choi Keechoo , Jayakrishnan R. , Kim Hyunmyung , Yang Inchul , Lee Jungwoo
Published: January 2010

As dynamic traffic simulation (DTS) becomes ever more popular, how to provide the input data, that is, a dynamic origin–destination (O-D) table, for simulation becomes an important question. During recent years, many researchers have proposed estimation methods for a dynamic O-D table from an academic point of view, but transportation engineers appear to use the dynamic approach in practical applications rarely. In recent simulation projects, ad hoc schemes have been used by practitioners for developing dynamic O-D tables for subareas from larger, static planning O-D tables without much theoretical soundness. The authors developed a dynamic O-D estimation model based on a path-flow approach and iterative simulations, along with a scheme to find a justifiable seed O-D table, and applied it to a real-world context. A major arterial corridor in Suwon, South Korea, was selected, and the link turning counts were collected at intersections. A microscopic DTS model, PARAMICS, was used with the dynamic O-D table to simulate link turning counts. The test results show that the developed O-D estimation technique is efficient, with simulated link traffic counts and section travel times very close to the reality.