bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Evaluation of the Lake Sturgeon Reintroduction Program in the Mississippi and Missouri Rivers
Authors: Drauch Andrea M. , Rhodes Olin E.
Published: April 2007

Over the past 20 years, there has been a growing awareness of the impact of genetic factors on the success of reintroduction programs for fish and other species. One primary genetic criterion to be considered in the design and implementation of reintroduction programs is the maximization of genetic diversity within reintroduced populations. Reintroduction has become an important management tool for the imperiled lake sturgeon Acipenser fulvescens. However, little published work has evaluated current lake sturgeon reintroduction programs in terms of their ability to transfer genetic diversity from source populations to reintroduced populations. We evaluated the success of an ongoing lake sturgeon reintroduction program based upon its ability to adequately transmit the genetic diversity of the Lake Winnebago source population into reintroduced populations in the Mississippi and Missouri rivers. Additionally, a nonreintroduced single year-class from a hatchery population established from the Lake Winnebago stock was included in this study to determine how much of a source population's genetic diversity could be captured in a single stocking event. Reintroduced populations exhibited levels of genetic diversity similar to that of their source population, and estimates of genetic differentiation revealed very little divergence between source and reintroduced population pairs. Significant levels of genetic differentiation between the Lake Winnebago and nonreintroduced hatchery fish, as well as evidence of a bottleneck within the hatchery fish, indicated that the small number of parents used in a single-year stocking event may not adequately exploit a source's available genetic diversity. Therefore, a multiple-year stocking strategy may be most appropriate for lake sturgeon reintroduction programs.
Warwickshire–Arup partnership: the first five years
Authors: Harwood K. , Follett B.
Published: April 2007

Warwickshire is a rural county in the UK Midlands with a population of around 535 000 and an area of about 2000 km2. Warwickshire County Council, through its Design Services Group, has been working in partnership with engineering consultancy Arup since August 2001. A successful relationship developed over the first five-year contract, with both organisations perceiving value beyond that envisaged at the start. Major benefits have been gained in achieving project targets of the local transport plan and in staff development and training. The scope of the relationship expanded to include additional technical disciplines and more client groups, bringing challenges in communication and management. The objective of the second partnering contract, running from 2006–2011, is to build on the success, learn from the difficulties experienced and develop the relationship to add value to both organisations.
Supplemental Irrigation and Fall Dormancy Effects on Alfalfa Productivity in a Semiarid, Subtropical Climate with a Bimodal Precipitation Pattern
Authors: Malinowski D. P. , Pinchak W. E. , Kramp B. A. , Zuo H. , Butler T. J.
Published: April 2007

Alfalfa (Medicago sativa L.) is an important hay crop produced under rain‐fed conditions or various levels of irrigation in the southern Great Plains of the USA. The objective of this study was to determine the role of fall dormancy (FD) on productivity and forage nutritive value of alfalfa in rain‐fed and supplemental irrigation systems in a semiarid, subtropical climate with a bimodal pattern of precipitation. Cultivars with FD ratings of 1 to 3 (dormant), 4 to 6 (moderately dormant), and 7 to 8 (nondormant) were planted in November 2001 on a Miles fine sandy loam (fine‐loamy, mixed, Thermic Udic Paleustalfs) near Vernon, Texas in two adjacent, randomized, complete‐block experiments representing rain‐fed and supplemental irrigation systems. In the supplemental irrigation system, water was supplied during April to October to meet the long‐term average monthly precipitation. During 2002–2005, plants were defoliated to 5 cm height at 5 to 15% bloom in all cultivars. In the rain‐fed system, FD had no effect on productivity (5.6–6.0 Mg ha−1). Nondormant cultivars produced higher dry matter yield (20.2 Mg ha−1) than dormant cultivars (15.9 Mg ha−1) under supplemental irrigation. Moderately dormant cultivars were intermediate (18.6 Mg ha−1). Forage nutritive value was greater in the spring (rain‐fed) or spring and autumn (supplemental irrigation) than in the summer. Weather patterns and harvest time interacted with FD in determining forage nutritive value under supplemental irrigation. Cultivars with FD ratings of 5 to 8 may be used in similar environments of the southern Great Plains to maximize productivity of alfalfa.
Using Leaf Gas Exchange to Quantify Drought in Cotton Irrigated Based on Canopy Temperature Measurements
Authors: Baker J. T. , Gitz D. C. , Payton P. , Wanjura D. F. , Upchurch D. R.
Published: April 2007

Plant gas exchange provides a highly sensitive measure of the degree of drought stress to which a crop is exposed. However, equipment costs and time requirements for gas exchange measurements are major obstacles to the use of gas exchange measurements in real‐time irrigation scheduling systems. Canopy temperature (Tc) provides a much easier to acquire indication of crop water deficit that has been used in irrigation scheduling systems, but interpretation of this measurement has proven difficult. Our goal was to test the ability of Tc to quantify the degree of crop water deficit by comparing Tc with simultaneous measurements of leaf‐level gas exchange parameters, which were viewed as alternative indicators of water deficit. To provide a wide range of plant water deficit conditions for the comparison of Tc with leaf‐level gas exchange parameters, cotton (Gossypium hirsutum L.) was subsurface drip irrigated using Tc according to the stress‐time index method of irrigation scheduling during two growing seasons. Comparisons between Tc and leaf‐level gas exchange were accomplished by measuring Tc diurnally with hand‐held infrared thermometers and controlling cuvette leaf temperature (TL) equal to Tc and then measuring leaf level net assimilation (A) and stomatal conductance (g) at a photosynthetically active radiation (PAR) level of 1500 μmol (photons) m−2 s−1. In general, as plant water deficit became more severe, leaf level gas exchange tended to decline with rising TL. However, we found that A and g could vary by more than twofold at a given TL, indicating that Tc was not a particularly robust indicator of the degree of drought stress. Furthermore, we found the leaf minus air temperature differential (TL − Ta) and vapor pressure deficit calculated based on leaf temperature (VPDL) were better predictors of the degree of drought stress, as indicated by gas exchange parameters, than TL alone. Regression of A and g against (TL − Ta) and VPDL indicated that the combination of these two variables accounted for >79% of the variability in A and g. We conclude that the term (Tc − Ta) either alone or in combination with VPD should provide a better predictor of the degree of drought stress in cotton than Tc alone.
Nitrogen and Phosphorus Fertilizer and Residual Response in Cotton–Sorghum and Cotton–Cotton Sequences
Authors: Booker J. D. , Bronson K. F. , Trostle C. L. , Keeling J. W. , Malapati A.
Published: April 2007

Nitrogen and P fertilizer response for cotton (Gossypium hirsutum L.) and sorghum [Sorghum bicolor (L.) Moench] in a reduced tillage rotation system in the Southern High Plains has not been well studied. During 2000 to 2003, an irrigated study of cotton–sorghum rotation vs. continuous cotton evaluated the crop rotation effects on cotton lint yield and assessed N and P fertilizer and residual fertilizer response for the two systems. Preplant soil samples were collected each spring to determine fertilizer rates. Cotton lint yields and cottonseed N were not affected by rotation with sorghum compared with continuous cotton. Nitrogen fertilizer response was observed in lint yields from 2001 to 2003 in cotton following sorghum, but not in continuous cotton. No P fertilizer or soil residual P response in cotton lint yields was found, regardless of rotation. Grain sorghum yields responded to N fertilizer in 2 yr. No grain sorghum response was observed to P fertilizer, but in 1 yr a yield response to residual P fertilizer relative to zero‐P plots was noted. Seed N uptake was greater in sorghum than in cotton. Nitrogen fertility level increased seed N in sorghum and in cotton following sorghum. Infrequent crop response to P fertilizer was not unexpected, especially when Mehlich‐3 soil P in zero‐P subplots was near the 95% sufficiency level of 20 mg P kg−1. The main finding of this study is that N fertilizer response was more consistent for cotton following sorghum than in a continuous cotton system. In refining N fertilizer recommendations, N debits may be needed for N immobilization in sorghum residue. Nitrogen credit may be appropriate from leaf litter for crops following cotton and for NO3–N in irrigation water.
Development of Vegetation Indices for Identifying Insect Infestations in Soybean
Authors: Board James E. , Maka Vijay , Price Randy , Knight Dina , Baur Matthew E.
Published: April 2007

Because of greater efficiency relative to conventional methods, interest has developed for using vegetation indices in soybean [Glycine max (L.) Merr.] for identifying areas in a field experiencing injury by defoliating insects. Vegetation indices can indicate leaf area index (LAI) and light interception levels, canopy parameters affected by defoliating insects. Our objectives were to determine the relative accuracy of three vegetation indices for predicting LAI and light interception, and to outline a method for using vegetation indices for identifying areas in a field experiencing insect injury. Several commercial soybean cultivars were planted on a Commerce silt loam soil (fine‐silty, mixed, nonacid, thermic Aeric Fluvaquent) near Baton Rouge, LA (USA) (30° N lat) in May 2004 and June 2005. In 2004, differences in LAI and light interception were created by manual defoliation, whereas in 2005, LAI/light interception differences occurred because of cultivars and planting dates. Results indicated that across canopies ranging from very low LAI to canopy closure (95% light interception), the normalized difference vegetation index (NDVI) most accurately predicted LAI and light interception (r2 = 0.93–0.97). Light interception and LAI were linked to NDVI by strong linear regression models, and did not show the quadratic response reported by others. A proposed method for adopting NDVI to identify insect‐infested areas is presented.
An Algorithm for Corn Nitrogen Recommendations Using a Chlorophyll Meter Based Sufficiency Index
Authors: Varvel G. E. , Wilhelm W. W. , Shanahan J. F. , Schepers J. S.
Published: April 2007

Nitrogen fertilizer continues to be the major input influencing corn (Zea maysL.) yield in the Midwest. Improved N recommendations should result in greater N use efficiency and producer profit while reducing surface and groundwater contamination. This study was conducted to develop a plant‐based technique to detect and correct N deficiencies during the season. Chlorophyll meter readings and grain yield were collected from corn in irrigated monoculture corn and soybean [Glycine max(L.) Merr.]–corn cropping systems with four hybrids and five N fertilizer application rates in the Platte Valley near Shelton, NE. Normalized chlorophyll meter readings (sufficiency index, SI) were calculated from data collected at three vegetative stages, defined by thermal time accumulation after planting, during each of the 10 yr of study (1995–2004). Highly significant linear correlations between SI and relative yield (normalized yield) indicated both responded similarly to N fertilizer application. Relationships between N rate and SI (at each of the three vegetative stages and combined over stages) were described by quadratic models. The combined model [(SI = 0.8073 + 0.002(N rate) − 0.0000056(N rate)2,R2= 0.70)] can be used to compute N needed to achieve maximum yield. Our procedure gives producers the tools to determine if N is needed, and if so, the amount of N required for maximum yield. In addition if SI is computed for specific areas of the field, N applications can be tailored to those areas, thereby reducing the potential of introducing more N into the system than needed to achieve maximum yield, with spatial and temporal constraints.
Beachell and Borlaug, Two Giants of the American Society of Agronomy's First Century
Authors: Milford Murray H. , Runge E. C. A.
Published: April 2007

On the occasion of the 100th anniversary of the American Society of Agronomy, it is appropriate that recognition be given to two men: Henry M. Beachell, internationally recognized and most long‐lived 73‐yr member, until his death in December 2006; and to Norman E. Borlaug, who without doubt, is the most widely acclaimed of the Society's members. Both men had scientific accomplishments that were crucial to the Green Revolutions associated with the production of rice (Oryza sativa L.) (Beachell) and wheat (Triticum aestivum L.) (Borlaug). Their professional careers have much in common and their interactions with each other had significant impact on the careers of both. The purposes of this paper are to gain insight into their thinking and to highlight the accomplishments that make them the most well‐known agronomists of the Society's first 100 yr.
On the convergence of the secant method under the gamma condition
Authors: Argyros Ioannis
Published: April 2007

We provide sufficient convergence conditions for the Secant method of approximating a locally unique solution of an operator equation in a Banach space. The main hypothesis is the gamma condition first introduced in [10] for the study of Newton’s method. Our sufficient convergence condition reduces to the one obtained in [10] for Newton’s method. A numerical example is also provided.
Hilbert algebras as implicative partial semilattices
Authors: Cīrulis Jānis
Published: April 2007

The infimum of elements a and b of a Hilbert algebra are said to be the compatible meet of a and b, if the elements a and b are compatible in a certain strict sense. The subject of the paper will be Hilbert algebras equipped with the compatible meet operation, which normally is partial. A partial lower semilattice is shown to be a reduct of such an expanded Hilbert algebra i ?both algebras have the same ?lters.An expanded Hilbert algebra is actually an implicative partial semilattice (i.e., a relative subalgebra of an implicative semilattice),and conversely.The implication in an implicative partial semilattice is characterised in terms of ?lters of the underlying partial semilattice.
Limit points of eigenvalues of truncated unbounded tridiagonal operators
Authors: Ifantis E.K. , Kokologiannaki C.G. , Petropoulou E.
Published: April 2007

Let T be a self-adjoint tridiagonal operator in a Hilbert space H with the orthonormal basis {e
n}n=1∞, σ(T) be the spectrum of T and Λ(T) be the set of all the limit points of eigenvalues of the truncated operator T
N. We give sufficient conditions such that the spectrum of T is discrete and σ(T) = Λ(T) and we connect this problem with an old problem in analysis.
The construction of the eukaryotic expression plasmid pcDNA3.1/azurin and the increased apoptosis of U2OS cells transfected with it
Authors: Ye Zhaoming , Peng Huiqin , Fang Yongming , Feng Jie , Yang Di-Sheng
Published: April 2007

In our previous study, we demonstrated that azurin could selectively trigger apoptosis in human osteosarcoma cell line U2OS cells. However, the rate of apoptosis (35.8 ± 3.2%) is not very high, and azurin is too expensive to obtain readily. To solve these problems, we constructed a eukaryotic expression plasmid containing the azurin gene with an influenza virus haemagglutinin 9 peptide HA epitope tag, and transfected the recombinant plasmid pcDNA3.1(+)/azurin into U2OS cells. RT-PCR and Western blot analysis validated the successful transfection and the expression of the azurin-HA protein. Conspicuous apoptosis of the transfected cells was detected by flow cytometry (FCM) and the DNA ladder test. The apoptosis rate reached 64.3 ± 13.1%. The transcriptional levels of the Bax and p53 genes increased significantly in U2OS cells transfected with pcDNA3.1(+)/azurin, but the Bcl-2 mRNA level decreased. There was no difference in the levels of Bcl-xl mRNA and Survivin mRNA. We propose that the transfection of the recombinant plasmid pcDNA3.1(+)/azurin can significantly induce apoptosis in U2OS cells. This is closely associated with the up-regulation of the transcriptional level of the Bax and p53 genes, and the down-regulation of that of the Bcl-2 gene.
Behaviour of inorganic constituents of municipal sewage sludge during fluidized-bed combustion
Authors: Hartman M. , Pohořelý M. , Trnka O.
Published: April 2007

The fate of main heavy metals in municipal sewage sludge (As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, and Zn) was investigated using a fluidized-bed reactor. The behaviour of metals in the incinerator was explored by comparing metal contents in the two main ash streams: bottom (in-bed) ash and ash separated by a cyclone (cyclone-catch ash). All metals showed enrichment in the cyclone ash. The ash originating from sewage sludge is thermally quite stable consisting of quartz, hematite, spar(s), mica(s), apatite, and anhydrite. It does not soften nor becomes sticky and does not tend to agglomerate at temperatures up to 950°C.
Notes on notation of sodium oxofluoroaluminate anions
Authors: Boča M. , Kucharík M.
Published: April 2007

The chemical notation of the reaction products in the system NaF—AlF3—Al2O3 was reevaluated and its modifications were suggested. Based on these modifications, the equilibrium constants of selected reactions were calculated. Some of the equilibrium constants differed by one or two orders of magnitude from the values of the corresponding original equilibrium constants.
Niche Networks for New Entrants
Authors: Hogendorn Christiaan
Published: April 2007

How new entrant carriers may use returns to airline networks in competition is discussed. In addition to overall returns to scope and density, there are more localized returns that are based on network shape. A network shape index, which is a measure of airline network concentration based on the Herfindahl-Hirschman index, is described. Airlines have chosen many different shapes as measured by the network shape index, and new entrants tend to be shaped differently from major airlines. A model of new entrant profitability relative to the major airlines is developed. New entrants whose network shape indices are substantially different from the major airlines have niche networks, and the model indicates that niche networks are associated with higher profitability.
Developing a Probabilistic Metric of Midair Collision Risk
Authors: Knecht William R.
Published: April 2007

The evaluation of single-aircraft-pair midair collision risk in the national airspace system is addressed. A nonlinear mathematical function is proposed to model the most significant feature of this risk. The function estimates probability of collision as a function of time to contact. Previous attempts to model collision risk have met with difficulty when faced with the challenge of integrating multiple, uncertain probability density functions for the individual components of risk. This approach sidesteps this problem by finding a psychometric function for collision-avoidance performance. This function is evaluated logically and by curve fitting to flight simulator data from commercial airline pilots in simulated conflict scenarios. Analysis of these data gives preliminary support for the appropriateness of the approach. Properly parameterized, such a function or family of functions could be projected to estimate the probability of collision associated with a planned aircraft maneuver. This is similar to the idea of the “conflict probe” currently being explored by the aviation community in its effort to institute free flight.
Air Carrier Deicing: Human Factors Approach for Building Redundancy and Commonality in Standard Operating Procedures
Authors: von Thaden Terry L.
Published: April 2007

Winter operations have long posed unique problems for the aviation community. According to Federal Aviation Regulations, no pilot may take off in an aircraft that has ice, snow, or frost adhering to the surface. This “clean aircraft concept” is difficult, if not impossible, for the pilots to assess from inside the aircraft. Equipment is in development to furnish the flight deck with icing information; however, these devices are not widely available and in many cases require costly retrofits. Pilots, unable to assess their aircraft’s external condition, often choose to return for additional deicing, necessitating the use of more glycol, thus jeopardizing the environment with additional glycol runoff entering the storm water system. A procedure has been developed to give the flight deck the necessary critical information concerning the state of the aircraft just before departure, providing a support system for pilot go/no-go decisions, increasing safety, and decreasing environmental hazards with reduced glycol usage. This Final Ice Detection Operation (FIDO) may be put into effect immediately with resources currently available at the nation’s airports and at minimal cost. A query of the National Aeronautics and Space Administration’s Aviation Safety Reporting System was conducted for ground icing incidents. A case study was also performed on a randomly selected group of air carrier pilots to understand their current issues with ground deicing operations. The findings support FIDO. A cost-benefit analysis would determine the viability of this procedure.
Fracture Mechanics in Pavement Engineering: The Specimen-Size Effect
Authors: Ioannides Anastasios M.
Published: April 2007

Application of fracture mechanics concepts developed in various branches of engineering to the pavement problem can address current limitations, thereby advancing considerably existing pavement design procedures. The state of the art in fracture mechanics applications to pavement engineering is summarized, and an in-depth discussion of one of the major concerns in such applications, the specimen-size effect, is provided. It is concluded that the fictitious crack model proposed by Hillerborg appears most promising for computerized application to pavements. The similitude concepts developed by Bache will be very useful in such efforts. Both the desirability and the scarcity of suitable candidates to replace Miner’s cumulative linear fatigue hypothesis in conventional pavement design are confirmed. Fracture mechanics is shown to be a very promising engineering discipline from which innovations could be transplanted to pavement activities. Nonetheless, it is pointed out that rather slow progress characterizes fracture mechanics developments in general. Pavement engineers clearly need to remain abreast of and involved in fracture mechanics activities.
Simplified Procedure for Prediction of Asphalt Pavement Subsurface Temperatures Based on Heat Transfer Theories
Authors: Shao Lisheng , Park Sun Woo , Kim Y. Richard
Published: April 2007

Surface deflection measurements and backcalculation of layer moduli in flexible pavements are significantly affected by the temperature of the asphalt concrete (AC) layer. Correction of deflections or backcalculated moduli to a reference temperature requires determination of an effective temperature of the AC layer. For routine deflection testing and analysis in state highway agencies, it is preferable, from a practical point of view, to use a nondestructive prediction method for determining the effective AC layer temperature instead of measuring the temperature directly from a small hole drilled into the AC layer. A simplified procedure to predict asphalt pavement subsurface temperatures is presented. The procedure is based on fundamental principles of heat transfer and uses the surface temperature history since yesterday morning to predict the AC layer mid-depth temperature at the time of falling weight deflectometer (FWD) testing today. The surface temperature history is determined using yesterday’s maximum air temperature and cloud condition, the minimum air temperature of today’s morning, and surface temperatures measured during FWD tests. FWD tests and temperature measurements have been conducted on seven pavement sections with varying structural designs located in three different climatic regions of North Carolina. The field temperature records from these pavements have provided values of pavement thermal parameters and coefficients in temperature functions that are needed in the prediction procedure. A set of verification results are presented using examples with different climatic regions, changing AC layer thicknesses, and varying weather patterns in different seasons.
Techniques for Selecting Pavement Rehabilitation Strategies: Pennsylvania Case Studies
Authors: Morian Dennis A. , Cumberledge Gaylord C.
Published: April 2007

The design and construction of pavement rehabilitation projects is one of the greatest challenges afforded today’s pavement engineers. All project information pertinent to the performance of a pavement section is needed to select, design, and successfully construct a rehabilitation strategy. Case studies of three rehabilitation projects constructed by the Pennsylvania Department of Transportation are provided. Each case study uses a different rehabilitation strategy. The process for selecting the appropriate requirements for each one is discussed. The pavement performance for each rehabilitated section is reviewed. The pavement performance information is tied back to the original criteria for project strategy selection and design to evaluate the success of the rehabilitation in addressing the issues that necessitated the rehabilitation and providing quality pavement performance.
Detecting Stripping in Asphalt Concrete Layers Using Ground Penetrating Radar
Authors: Rmeili Elias , Scullion Tom
Published: April 2007

A study undertaken by the Texas Department of Transportation to nondestructively detect stripping in the asphalt surfacing on I-45 in the Bryan district is described. The highway was constructed in the 1960s and 1970s with an initial portland cement concrete thickness of 200 mm. Since then, several asphalt overlays have been applied. Maintenance of this highway is a recurring problem, and it is known that in several locations moderate to severe areas of subsurface stripping are present. To plan the future rehabilitation of this important highway, the Bryan district investigated the ability of ground penetrating radar (GPR) to provide subsurface condition information. A GPR survey was conducted at close to highway speeds, and the data were interpreted before taking validation cores. The GPR was used to provide information concerning the section breaks along the highway on the basis of asphalt layer thickness and condition, the average thickness of the asphalt layer within each section, and the extent and severity of any defect in the asphalt layer. More than 60 cores were taken to correlate the GPR interpretation. GPR results and ground truth cores are compared. In general, the comparisons were good. The GPR equipment and interpretation schemes used were found to provide information of sufficient quality and accuracy to permit the district to make programming decisions. GPR is now being used on several additional projects in the Bryan district. The best use appears to be for both defect detection and thickness estimation before deflection testing and coring. GPR will not eliminate coring or deflection testing, but by using all three in a coordinated approach pavement designers will have more confidence in their design decisions.
Linear Tracking Performance Tests on Full-Depth Asphalt Pavement
Authors: Groenendijk J. , Vogelzang C. H. , Miradi A. , Molenaar A. A. A. , Dohmen L. J. M.
Published: April 2007

A 0.15-m-thick gravel asphalt concrete (AC) pavement on a sand subgrade was loaded with 4 million repetitions of a 75-kN super-single wheel load using the linear tracking device (LINTRACK) heavy-traffic simulator. Frequent measurements were carried out, including asphalt strain, temperature, rutting, cracking, and falling weight deflectometer measurements, to investigate the performance of full-depth asphalt pavements. The subsequent data analysis indicated that the life of the tested asphalt pavement, according to the Dutch fatigue-design criterion (halving the asphalt stiffness), was 2 to 4 times longer than predictions based on the pavement-design method of the Road and Hydraulic Engineering Division (RHED) of the Dutch Ministry of Transport, Public Works and Water Management. Thus, this method does not give an unsafe design. The analysis also indicated that halving of the asphalt stiffness, implying structural distress, occurred before any cracking was visible at the pavement surface. Almost all visible cracking occurring later in this test pavement consisted of surface cracking instead of structural cracking. Therefore, the structural distress did not grow upward to form the visible cracks at the surface, but the latter formed independently. The same was observed on Dutch highways, which are much thicker. These conclusions are based on only one test section, although supplemented with extensive materials testing, and verification with other tests is necessary.
Analysis of LTPP Profile Data for Jointed Concrete Pavement Sections
Authors: Moody Eric D.
Published: April 2007

Incremental changes to a pavement-surface profile have long been considered a primary measure of pavement performance. As a result, the Long-Term Pavement Performance (LTPP) program of the Strategic Highway Research Program has allocated considerable resources for collecting accurate profile data on all general pavement studies (GPS) sites annually. As of June 1995, the profiles of the rigid pavement sites had been measured an average of four times, with many sites having been measured seven times. The data are collected and processed in the field, generating several statistical measures of pavement profile for each wheelpath, including the international roughness index (IRI), present serviceability index (PSI), slope variance, and root-mean-square vertical acceleration (RMSVA) at selected wavelengths. The focus of this analysis is on the primary profile statistic, the IRI. The profile data were downloaded from the National Inventory Management System (NIMS) and extensively analyzed using selected statistical techniques. The objective of this effort was to conduct a thorough analysis of the response variable, the IRI. The analysis included univariate, bivariate, and multivariate analytical techniques to determine which prediction variables are useful for predicting the IRI. Although many of the primary independent variables had significant correlations with the IRI, others did not. Various measures of traffic had particularly poor correlations with the IRI. Several regression models are also presented along with advantages and limitations of the prediction and response variables. The results of a detailed analysis of the within-year and year-to-year variability in IRI measurements are also included. The coefficient of variation in year-to-year measurements averaged 4.2 percent for the jointed plain concrete pavement (JPCP) sections (GPS-3) and 3.8 percent for the jointed reinforced concrete pavement (JRCP) sections (GPS-4). This degree of variability in year-to-year profile measurements tended to overshadow any absolute increase in IRI that may have been occurring in these sections. An analysis was then performed on every section to determine exactly which sections had statistically significant increases in IRI over time. Approximately 44 percent of the jointed concrete pavement sections exhibited statistically significant increases in IRI over time.
Investigation of Backcalculated Moduli Using Deflections Obtained at Various Locations in a Pavement Structure
Authors: Zhou Haiping , Rada Gonzalo R. , Elkins Gary E.
Published: April 2007

The interpretation and use of deflection measurements on the prepared surfaces of the various pavement layers during construction are examined. Measurements were obtained from four asphalt concrete pavement test sections, two with unbound aggregate base and two with bituminous-treated base over an untreated aggregate base. Deflection basin measurements using a falling weight deflectometer were performed on the prepared surfaces of the subgrade, base layers, and asphalt concrete layers. The elastic moduli of each layer were computed using the EVERCALC backcalculation program. The primary finding from this investigation is that deflection measurements on the subgrade and base layers during construction can be used to control construction uniformity and provide checks on mechanistic-based pavement design assumptions. Also, subgrade uniformity has a profound impact on the entire pavement structure and subgrade variations affect total deflections and computed layer moduli of all successive layers. The backcalculated modulus is directly related to the stress state in the layer. For unbound aggregate bases, the backcalculated elastic modulus decreases with a decrease in the bulk stress, and for fine-grained subgrade soil, the backcalculated elastic modulus increased with a decrease in the deviator stress. As expected, a higher and more variable root-mean-square basin fit error value was obtained for measurements on unbound material as compared with measurements on bound material surfaces.
Temperature Correction of Backcalculated Moduli and Deflections Using Linear Viscoelasticity and Time-Temperature Superposition
Authors: Park Sun Woo , Kim Y. Richard
Published: April 2007

New analytical procedures for temperature correction of backcalculated asphalt concrete moduli and surface deflections were developed based on the theory of linear viscoelasticity and the time-temperature superposition principle and verified using falling weight deflectometer data and field temperature measurements. The new correction procedures explicitly utilize the thermorheological properties of the asphalt mixture. The resulting temperature-modulus correction factors depend only on the relaxation modulus and time-temperature shift factor of the mixture. The temperature-deflection correction factor depends on both the material properties and the layer thicknesses of the pavement section. Emphasis has been placed on the analytical description of the mixture’s thermoviscoelasticity responsible for temperature effects on mixture modulus and pavement deflection. A mechanistic framework for dealing with temperature correction problems for asphalt pavement has been introduced.
DIPLOBACK: Neural-Network-Based Backcalculation Program for Composite Pavements
Authors: Khazanovich Lev , Roesler Jeffery
Published: April 2007

A neural-network-based backcalculation procedure is developed for multilayer composite pavement systems. The constructed layers are modeled as compressible elastic layers, whereas the subgrade is modeled as a Winkler foundation. The neural networks are trained to find moduli of elasticity of the constructed layers and a coefficient of subgrade reaction to accurately match a measured deflection profile. The method was verified by theoretically generated deflection profiles and falling weight deflectometer data measurements conducted at Edmonton Municipal Airport, Canada. For the theoretical deflection basins, the results of backcalculation were compared with actual elastic parameters, and excellent agreement was observed. The results of backcalculation using field test data were compared with the results obtained using WESDEF. Similar trends were observed for elastic parameters of all the pavement layers. The backcalculation procedure is implemented in a computer program called DIPLOBACK.
Montana’s Automated Deflection Analysis Procedure
Authors: Rada Gonzalo R. , Shepherd Kent L. , Zeigler Terry D. , Smith Tim E.
Published: April 2007

Economic conditions in the state of Montana during the past few years have dictated that the time and cost required to collect and analyze deflection data be significantly reduced. Consequently, the Montana Department of Transportation (MDT) undertook the development of an automated deflection analysis procedure (ADAP). This effort resulted in a PC-based Microsoft Windows application that provides a single program to assist the user in each step of the backcalculation analyses, from raw data to generated reports. The ADAP system consists of three components: preprocessor, main processor, and postprocessor. The preprocessor is used to import, validate, and extract deflection data and other pertinent pavement information from the Road Rater and MDT Oracle data base files and to generate the input for the MODULUS backcalculation program. The MODULUS program, which is the main system processor, is used to backcalculate in situ pavement layer moduli. The postprocessor provides the ability to generate reports and retrieve the analysis results, calculate the structural capacity and remaining life of the pavements in question, and upload the results to the MDT Oracle data base. In addition to providing for a more consistent, productive, and straightforward backcalculation process, the time and resources to perform the analysis of deflection data have been significantly reduced. Initial estimates indicate that instead of the 3 to 4 hr of work that were required for every hour of data collection, only 1 hr is now required, and this time will likely decrease as the MDT staff becomes more familiar with the program.
Dynamic Performance of Composite Pavements Under Impact
Authors: Shoukry Samir N. , Martinelli D. R. , Selezneva Olga I.
Published: April 2007

The importance of developing a deep understanding of the behavior of pavement layers under the action of dynamic loads, and the availability of cutting-edge computational and visualization technologies, led to the study presented in this paper. Explicit finite-element analysis was used to investigate the propagation of dynamic displacements induced in pavement layers under the action of an impact load similar to the one applied in a falling weight deflectometer test. The time-dependent dynamic response of a rigid pavement with straight asphalt concrete overlay was studied for two cases of unbonded and fully bonded interfaces between different layers. Significant differences in behavior were observed. Three-dimensional computer graphics and animation of the deformed model were used to display the propagation of vertical dynamic displacements through pavement layers. It was found that in the absence of a perfect bond between all pavement layers, the displacements measured on the top surface correlated little with the deformation measured in subsequent layers. In this case, a complicated pattern of behavior took place between the asphalt overlay and the concrete. The time histories of vertical displacements at selected surface locations and on the top and bottom of every layer were plotted. The plots revealed the existence of time shifts between the maximum displacements experienced by each layer, irrespective of the type of bond assumed between the interfaces.
Using Geographic Information System Technology To Synthesize Census Areawide and Linear Highway Data for Location of Weigh-in-Motion Sites
Authors: Erlbaum Nathan S. , Vaughan Thomas M.
Published: April 2007

A process is described that was developed by the New York State Department of Transportation to identify potential areas around the state for location of new weigh-in-motion sites. The procedure uses geographic information system (GIS) technology to synthesize census areawide travel and business data with linear highway system traffic and vehicle classification data from the Department’s computer inventories. The conclusion is that GIS is a powerful tool for synthesizing and displaying diverse data sets for use in solving engineering problems.
Development of Prototype Video-Based Sensor for Vehicle Detection from Stand-Still Images
Authors: Tzes Anthony , McShane William R.
Published: April 2007

The design, development, and testing of a prototype wide-area traffic detection system are described. The video-based sensor computes the approximate number of vehicles present within an a priori defined observation area from stand-still images. This sensor is mostly oriented toward the traffic detection in congested intersections, in which sensors using existing radar, acoustic, and video-based technology are faced with critical obstacles caused by the automobile stoppage. The prototype system has been tested and found to perform satisfactorily in field studies.
PART 1: Bus: Bus Performance Indicators: On-Time Performance and Service Regularity
Authors: Nakanishi Yuko J.
Published: April 2007

New York City Transit has established a customer-oriented bus performance indicator program. The program contains two schedule adherence indicators—en route on-time performance and service regularity—that measure different aspects of service performance experienced by the customer. The indicators and analysis methodologies are described in detail. What do these indicators really measure? And what types of further analysis can be performed using the underlying data? These are some of the issues addressed. Recommendations are made for adding a third indicator to the performance indicator program.
Trip Assignment Model for Timed-Transfer Transit Systems
Authors: Shih Mao-Chang , Mahmassani Hani S. , Baaj M. Hadi
Published: April 2007

A trip assignment model for timed-transfer transit systems is presented. Previously proposed trip assignment models focused on uncoordinated transit systems only. In timed-transfer transit systems, routes are coordinated and scheduled to arrive at transfer stations within preset time windows. Thus, passengers at coordinated operations terminals may face a choice among simultaneously departing buses serving alternative routes (unlike the case for uncoordinated operations terminals, where passengers generally board the first vehicle to arrive). A general trip assignment model is proposed that applies different assignment rules for three types of transfer terminals: uncoordinated operations terminals, coordinated operations terminals with a common headway for all routes, and coordinated operations terminals with integer-ratio headways for all routes. In addition, the care of missed connections at transfer terminals (due to vehicles arriving behind schedule) is accounted for. The model has been implemented in the LISP computer language, whose “list” data structure is specially suited to handle path search and enumeration. Results from an application to an example network with different combinations of terminal operations and headways indicate the following: ( a) demand tends to be assigned to higher-frequency paths in the uncoordinated transit network; ( b) demand is more concentrated, and tends to be assigned to paths with higher frequency and lower travel costs in the coordinated transit network; and ( c) missed connections have no significant effects on trip assignment.
PART 4: Rail Transit: New Vehicle Options for Lower-Cost Rail Mobility: Using Diesel or Dual-Powered Light Rail Cars as a Transfer of Technology
Authors: Geissenheimer Harold H.
Published: April 2007

An exciting opportunity exists to transfer innovative transit technology and operating scenarios from Europe to North America. There is a need to demonstrate a range of mobility options using efficient and cost-effective new technologies to maximize the use of available rail rights of way. The use of a new generation of self-propelled diesel power cars (DMU) or dual-powered electric light rail vehicles (LRVs) combined with changes in operations and organization can provide a low-cost way to operate efficient rail service on marginal lines. Two types of DMUs and two applications of dual-powered LRVs are described, both of which have been demonstrated in North America. These demonstrations represent commitment by the manufacturer and the operator to seek new solutions from overseas. Whereas each type of DMU fits a specific niche, they both offer a clear indication of the potential for this type of vehicle. Also suitable for technology transfer are dual-powered electric light rail cars now used in Karlsruhe and Amsterdam. The Karlsruhe system extends a city tramway system out into the region on standard rail lines. The Amsterdam operation brings a suburban light rail line into the city center by sharing the existing subway. Cleveland’s Shaker Heights Light Rail Line also reaches the city center by sharing tracks with a rapid transit line. Each combines the use of existing infrastructure into a cost-effective package. Planning in New York and Philadelphia includes a potential application of light rail dual-powered technology and track sharing. Although outside the scope of this study, both Japan and Korea have demonstrated the feasibility of similar track sharing for heavy rail services. Strategies for operating these new vehicle concepts are identified: ( a) track sharing with freight railroads or metros, ( b) providing separate time windows for non-FRA-compliant vehicles, ( c) FRA compliance, ( d) Americans with Disabilities Act compliance, ( e) fare collection, and ( f) other institutional and labor issues.
PART 5: Commuter Rail: Loadgen: NJ Transit’s Ridership Allocation Model
Authors: Disarro John A. , Galloway Andrew J.
Published: April 2007

Effective equipment manipulation can lead to cost savings in vehicle purchases, maintenance, and parts inventory. “Loadgen,” developed in-house by NJ Transit, is a computerized ridership allocation model that helps size train consists. It projects the number of riders boarding or departing at each station stop for each train in a proposed schedule. The total boardings projected for each train dictate the minimum number of coaches needed. The model has been validated and put to use for many short-and long-term projects at NJ Transit.
Rediscovering the Urban Railroad
Authors: Allen John G.
Published: April 2007

The urban railroad represents a long-established but little-understood range of rail transit in several older North American industrial cities. In most instances urban railroads are officially classified as commuter rail, but the genre also includes a couple of lines in the rapid transit category. Several urban railroads incorporate elements of both modes. The urban railroad uses conventional railroad technology and rights of way to provide high-quality service within the central city. Examples of the urban railroad include Metra Electric in Chicago, Cleveland’s Red Line, and the urban portions of Philadelphia’s Regional Rail and New York’s Long Island Rail Road. Neglected and overlooked for decades, the urban railroad has untapped potential to attract amenity-conscious customers and relieve ridership pressure on nearby bus routes.