bluuebunny/crossref_metadata_2025 huggingface dataset:
Output Power Leveling of a Wind Generation System Using Inertia of a Wind Turbine
Authors: Howlader Abdul Motin , Urasaki Naomitsu , Yona Atsushi , Senjyu Tomonobu , Kim Chul-Hwan , Y. Saber Ahmed
Published: September 2009

Wind energy conversion systems have become important in the research of renewable energy sources. This is in no small part due to the rapid advances in the size of wind generators as well as the development of power electronics and their applicability in wind energy extraction. However, wind energy has a drawback of having only 1/800 (gm per cubic cm) density as compared to that of water energy. Wind energy does not remain constant and wind turbine output is proportional to the cube of wind speed, which causes the generated power of the wind turbine generator (WTG) to fluctuate. In this paper, a technique is proposed for output power leveling of a wind generation system. Wind turbine blades have a large inertia compared to the inertia of a generator. The inertia of the rotor behaves like an inductor in an electrical circuit. It helps smooth the wind turbine output power, stores energy during acceleration, and restores energy during deceleration. The effectiveness of output power leveling control is verified by simulations for the wind power generation system.
Comparative Study of LEO and GEO SSPS for Some Identified Sites in India
Authors: Chaudhary Kalpana , Vishvakarma Babau R.
Published: September 2009

The analysis of satellite solar power station (SSPS) is carried out for some specified locations in India and consequently the performance of the system is evaluated for geostationary earth orbit (GEO)-based SSPS and low earth orbit (LEO)-based SSPS for sites located at different latitudes. The analysis of power, the received energy over a year, and the received energy during a day for the same beam intensity show better results for LEO-based SSPS system as compared to GEO-based system. However GEO-based system is advantageous in the sense that it will deliver constant energy to the load throughout a year. Thus it is concluded that GEO-based system is suitable for base load power plant. The weight of the rectenna and hence the space required for ground station for same power output for GEO-based system is greater than that for LEO-based system which will in turn increase the overall cost of the GEO-based system. These findings may help for judicious selection of orbit for placing the satellite for SSPS.
The Contemporary American Vice Presidency: A School for the Presidency?
Authors: Prémont Karine
Published: September 2009

The vice presidency is probably the most unappreciated and underestimated institution of American democracy. Often the target of gibes, it has nevertheless undergone a radical transformation over time. Vice presidents are now almost always considered for the presidency. Moreover, since World War II, most of them have had presidential ambitions. What factors account for the fact that the vice-presidency has become a potential breeding ground for future presidents? To answer this question, I initially examine the external changes that have affected the vice-presidential functions. Secondly, I compare four contemporary vice presidents (Nixon, Ford, Mondale and Bush) to determine whether their management style is linked to their presidential prospects. Finally, I discuss other considerations that could explain why the vice presidency is a significant asset for those who seek the presidency.
Host-parasite relationships between Porichthys porosissimus (Pisces) and cestode larvae of the Scolex group
Authors: Guagliardo S. , Tanzola D. , Schwerdt C. , Galeano N.
Published: September 2009

Larvae of tetraphyllidean cestodes have been recorded in several species of marine teleosts. However, little is known on parasite-host interactions. In view of this, the present study aims at i) determining the localization sites of a larval type, belonging to the Scolex group, in the digestive tract mucose; ii) describing the anatomo-pathological features of the larval lesions produced; and iii) evaluating the potential effect of parasite intensity on the body condition of the host. Our findings reveal that parasitic charges were more intense in the second portion of the digestive tract. In the area of contact between the parasite and the epithelium a compressive atrophy of the cells was observed with a marked lowering and disappearance of the epithelial layer. The condition factor of the samples analyzed was significantly affected by infection intensity, thus revealing an adverse effect on the growth and physical condition of the host.
Communities of metazoan parasites of two fishes of the Proterorhinus genus (Actinopterygii: Gobiidae)
Authors: Kvach Yuriy , Oğuz Mehmet
Published: September 2009

Metazoan parasite communities of two gobiids, Proterorhinus marmoratus and P. semilunaris, which are common small-sized fishes native for the Black Sea basin, were studied. The parasite component community of P. marmoratus is represented by 11 species (one monogenean, one cestode, five digeneans, two nematodes, and two acanthocephalans). P. semilunaris had 5 species (one monogenean, one cestode, one digenean, one nematode, and one acanthocephalan). Acanthocephaloides propinquus has a great tendency to join the infracommunity. The differences between the parasite component communities of two Proterorhinus gobies are explained by different quality of habitats and available intermediate hosts. The component community of parasites of P. marmoratus is formed by brackish-water and marine parasite species, and that of P. semilunaris consists of limnetic parasite species. The euryhaline G. proterorhini is the only parasite species found in both P. marmoratus and P. semilunaris. In both species of gobiids, the main abundant parasite species (A. propinquus in P. marmoratus and Nicolla skrjabini in P. semilunaris) infest the host by feeding on crustaceans.
The helminth community of the agile frog, Rana dalmatina Bonaparte, 1839 (Anura: Ranidae) collected from Northwest of Turkey
Authors: Düşen S. , Uğurtaş İ. , Aydoğdu A. , Oğuz M.
Published: September 2009

A total of 33 agile frogs (Rana dalmatina) were collected from 7 localities in Edirne, Bursa and Adapazarı Provinces (Northwest of Turkey), between 1987–2007 and examined for the first time for helminths. R. dalmatina harbored one species of Monogenea (Polystoma sp.), 3 species of Digenea (Diplodiscus subclavatus, Pleurogenoides medians, and Pleurogenes claviger), 4 species of Nematoda (Rhabdias bufonis, Oswaldocruzia filiformis, Cosmocerca ornata, and Oxysomatium brevicaudatum) and one species of Acanthocephala (Acanthocephalus ranae). All helminths represent new host records for Rana dalmatina in Turkey.
Functional Outcome after Operatively Treated Ankle Fractures in the Elderly
Authors: Davidovitch Roy I. , Walsh Michael , Spitzer Allison , Egol Kenneth A.
Published: September 2009

Background:

The goal of this review was to compare the functional outcomes of patients less than 60 and greater than or equal to 60 years old following operative stabilization of unstable ankle fractures. The review was conducted as a retrospective analysis of prospectively collected data at two level one trauma centers and a tertiary referral academic center.

Materials and Methods:

All patients operatively treated for an unstable ankle fracture were entered into a database and prospectively followed. The postoperative protocol was standardized for all patients. Baseline characteristics, complications, additional surgery, functional status and the American Orthopaedic Foot and Ankle Society score (AOFAS) were assessed. The intervention chosen was open reduction and internal fixation of unstable ankle fractures. AOFAS hindfoot score and Short Musculoskeletal Functional Assessment (SMFA) questionnaire were used as the main outcome measures in the study. A p < 0.05 was considered significant.

Results:

Three hundred sixty-nine (369) patients were entered into the database, 313 (84.8%) were less than 60 years old. At 3 months, 57% (32/56) of patients greater than or equal to 60 years old reported limitation of activities versus 33% (103/313) of patients less than 60 years old ( p = 0.005). At 6 and 12 months, these percentages improved to 41% versus 10% ( p = 0.001), and 29% versus 7.4% ( p = 0.001) for older and younger individuals respectively. However, when compared to their baseline scores, both groups achieved a return to pre-injury status. Total AOFAS scores were not significantly different at 3, 6, or 12 months ( p = 0.431).

Conclusion:

Operative fixation of unstable ankle fractures in patients greater than or equal to 60 years old can provide a reasonable functional result at the 1-year followup with a return to preoperative baseline even though they report more limitation of activities than younger patients.
Postoperative Cast Necessity after a Lapidus Arthrodesis
Authors: Kazzaz Sarmad , Singh Dishan
Published: September 2009

Background:

The incidence of non union following a first tarsometatarsal arthrodesis (Lapidus procedure) has decreased significantly with modern techniques of minimal bone resection, meticulous bone surface preparation and rigid internal fixation. We evaluated whether a postoperative wedge shoe would increase our non-union rate.

Materials and Methods:

Nineteen adult female patients (27 feet; eight bilateral, five simultaneous) undergoing a first tarsometatarsal arthrodesis for hallux valgus associated with a hypermobile first ray or for recurrent hallux valgus were managed postoperatively by allowing them to bear weight in a wedge shoe instead of a cast. Radiographs were evaluated for signs of fusion.

Results:

All 27 feet went on to successful union after 6 to 24 weeks. There was one superficial wound infection and one case of recurrence of the hallux valgus.

Conclusion:

Based on our results, we allow adult patients undergoing a Lapidus type procedure to be managed in a postoperative wedge shoe.
Toward an Intelligent Brokerage Platform
Authors: Muckell Jonathan , Cao Qing , Mackenzie Patricia , Messier Daniel , Salvo Joseph
Published: September 2009

In commercial transportation operations, one of the largest wasteful expenditures is the movement of tractor trailers with little or no cargo. Analysis of interfleet data shows many lost opportunities for identifying backhauling loads—cargo that could have been moved by an otherwise empty trailer on its return from a delivery point to its home base. Brokerage systems that facilitate matching of load-sharing and backhaul opportunities currently do not incorporate monitoring of real-time, geo-based information, analysis of historical geo-based information, and user-calibrated preferences from all brokerage participants. Future intelligent brokerage systems will need to provide a full range of services including supply chain visibility and automated identification of potential collaborations based on historical trends. In this paper an algorithm is described for identifying load-sharing and backhaul opportunities based on the detection of patterns in large-scale, event-based telematics network data.
Addressing the Last Mile Problem
Authors: Song Liying , Cherrett Tom , McLeod Fraser , Guan Wei
Published: September 2009

The impacts of failed first-time home deliveries on additional carrier journeys (repeat deliveries) and customer trips (to retrieve goods from carrier depots) are of increasing concern to e-retailers and are assessed in this paper. The attended collection and delivery point (CDP) concept is one solution to first-time delivery failures, using a variety of outlets (e.g., convenience stores, petrol stations, post offices) as alternative addresses to receive deliveries. By using a database of households from across West Sussex in the United Kingdom, this paper confirms that certain benefits might accrue from using networks of Local Collect post offices, supermarkets, and railway stations as CDPs, compared with the traditional delivery method in which the carrier may make several rede-livery attempts to the home with the customer making a personal trip to the carrier's depot in the event that these attempts also fail. A network of CDPs across West Sussex would function most effectively (in reducing the overall traveling costs associated with handling failed first-time deliveries) when the proportion of first-time home delivery failures is greater than 20%, the proportion of customers traveling to the depot is more than 30%, Local Collect post offices are used as CDPs, and significant numbers of people would walk to their local CDP. Customers benefit the most from CDPs, with reductions in their current traveling costs of up to 90% being modeled here. The reduction in carrier traveling costs is much less, but the processing costs associated with home delivery failures are reduced significantly by diverting the failed packages to CDPs.
Structuring a Definition of Resilience for the Freight Transportation System
Authors: Ta Chilan , Goodchild Anne V. , Pitera Kelly
Published: September 2009

This paper summarizes a broad literature review on system resilience. After these interpretations of resilience are considered, a definition of resilience in the context of freight transportation systems is provided. The definition of resilience offered here captures the interactions between managing organizations—namely, state departments of transportation, the infrastructure, and users—which is critical considering that the freight transportation system exists to support economic activity and production. A list of properties of freight transportation system resilience is outlined. These properties of resilience can contribute to the overall ability of the freight transportation system to recover from disruptions, whether exhibited at the infrastructure, managing organization, or user dimension. This contribution provides a framework that can serve as a starting point for future research, offering a shared language that promotes a more structured conversation about freight transportation resilience.
Estimating Time-Dependent Demand for Truck Parking Facilities along a Federal Highway
Authors: Heinitz Florian M. , Hesse Norman
Published: September 2009

This study documents a new demand modeling approach for scarce truck parking facilities. In recent years the parking sites and service areas on Germany's federal highway system have been frequently overcrowded by heavy goods vehicles. Especially at night, the shortage of parking space is evident; the shortage counteracts the goals of the Europe-wide hours-of-service (HOS) rules for truck drivers. The simulation-based examination aims to close the gap between empirical data and the decision support needs for target-oriented improvements. First a generic approach was developed reconstructing demand for truck parking space at an arbitrary segment of highway. The unique features are the time resolution and the explicit functional dependency on the HOS regulation. A prototype of this model having been applied to one study area in Germany, possible adaption to the United States is discussed. In summary the methodological contribution seeks to establish the basis of a test of various transport policy measures and subsequent performance reviews.
Options for Exposure-Based Charging for Long Multiple Trailer Truck Permits
Authors: Regehr Jonathan D. , Montufar Jeannette , Clayton Alan
Published: September 2009

This paper analyzes options for exposure-based charging for long multiple trailer truck permits. Long trucks—Rocky Mountain doubles, turnpike doubles, and triple trailer combinations—are granted permits because they provide increased technical productivity for hauling low-density freight. Experiences in the Canadian Prairie Region indicate that standardization of rationales used to establish permit charges is increasingly important as the network permitting long trucks expands and enables regional operation. Contributing to the differences in charging perspectives is the cube-out condition under which most long trucks operate, which challenges the justification for assessing incremental fees for their operation. An analysis of truck size and weight regulations governing the cubic trucking domain demonstrates that trucks in this domain are ideally suited for freight densities up to about 240 kg/m3 (15 lb/ft3). Four exposure-based options for establishing permit charges are presented: revenue-based charging, cost recovery, incentive provision, and privatization. Carrier costs and public revenues for three cases in the revenue-based charging option—benefit-sharing, revenue neutrality, and full benefit taxation—are analyzed and compared with the current base case conditions in Manitoba. The analysis reveals increases in turnpike double operating costs ranging from 2% for revenue neutrality to 50% for full benefit taxation. Corresponding public revenue increases for these three cases range from 30% for revenue neutrality to a 12-fold increase for full benefit taxation. The sensitivity of the results to freight density and utilization demonstrates the need for charges to reflect differences between cube-out and weigh-out conditions, and the distance traveled by long trucks.
Behavioral Microsimulation Formulation for Analysis and Design of Off-Hour Delivery Policies in Urban Areas
Authors: Silas Michael A. , Holguín-Veras José
Published: September 2009

This paper is aimed at gaining a better understanding of how to increase participation in off-hour deliveries by using behavioral microsimulation (BMS) of carrier–receiver interactions. BMS is used to study the effectiveness of policies such as time-of-day pricing and financial incentives to receivers in exchange for their acceptance of off-hour deliveries. The main components of this BMS are the simulations of receiver and carrier behaviors. The simulation of receiver behavior uses a discrete choice model to estimate receivers’ decisions to accept or reject off-hour deliveries. The simulation of carriers’ behaviors uses receivers’ decisions as an input for deciding whether to make off-hour deliveries along with a computation of the associated delivery costs. The analyses done revealed several key results: ( a) tax deductions given to receivers in exchange for accepting off-hour deliveries and financial rewards to carriers making off-hour deliveries would increase participation in off-hour deliveries, ( b) time-of-day toll surcharges have no major impact on increasing off-hour deliveries, ( c) carriers located close to their urban customers are more likely to participate in off-hour deliveries because they can easily start to accrue the benefits from off-hour delivery operations, and ( d) increased enforcement of parking fines for double-parking during regular hours could increase the number of carriers participating in off-hour deliveries.
Freight Generation Models
Authors: Bastida Carlos , Holguín-Veras José
Published: September 2009

This paper conducts a comparative analysis of two alternative approaches to freight generation modeling: ordinary least square (OLS) and cross classification. OLS models were estimated to identify a functional relationship between the number of freight deliveries per day and a set of company attributes used as independent variables. Cross-classification techniques aim at identifying a classification structure that provides a good representation of the freight generation process. To that effect, multiple classification analysis was used to identify groups of independent variables explaining freight generation, which provided the basis for constructing cross-classification tables. In both cases freight generation is explained as a function of company attributes. The model estimation process used data obtained from commercial establishments located in Manhattan and Brooklyn, New York. More than 190 different variables were tested as predictors for the number of deliveries received or carried per day. Six linear regression models found to be statistically significant and conceptually valid are discussed. Establishment attributes such as industry segment, commodity type, facility type, total sales, and number of employees were found to be statistically significant. The OLS models indicated that industry segment and commodity type are strong predictors of freight generation. It was also noticed that many of these variables played a significant role when interacting with economic variables such as total sales or employment. Twelve different groups of independent variables predicting freight generation were found to be significant as part of the cross-classification models. Results indicate that as in the case of regression models, commodity type, industry segment, and employment are strong predictors for freight generation.
Simultaneous Load Scheduling of Quay Crane and Yard Crane in Port Container Terminals
Authors: Lee Der-Horng , Cao Zhi , Chen Jiang Hang , Cao Jin Xin
Published: September 2009

Load scheduling problems of the quay crane (QC) and yard crane (YC) are important issues in port container terminal operations. Because the two scheduling problems are closely related, this paper proposes a mathematical model to formulate the load scheduling problem of the QC and YC simultaneously. A genetic algorithm (GA) and a heuristic method [QC and YC scheduling heuristic (QYSH)] are designed for the problem solution. Results obtained through numerical experiments showed that the problem-oriented QYSH method significantly outperformed the GA and could be applied in real operations to conduct simultaneous quay crane and yard crane scheduling.
Load Scheduling of Multiple Yard Crane Systems in Container Terminal with Buffer Areas
Authors: Lee Der-Horng , Cao Zhi , Chen Jiang Hang , Cao Jin Xin
Published: September 2009

This paper addresses the load scheduling problem of multiple yard crane systems in container terminals with buffer areas. In the problem several yard cranes are used to pick up a sequence of containers for a quay crane. The containers picked up ahead of schedule can be stored in buffer areas until they can be handled by the quay crane. An integer programming model is developed for the problem formulation. In the model the work schedules of different yard cranes are decided simultaneously to minimize the loading time. The yard crane scheduling problem is NP-complete by nature. Therefore a scheduling heuristic is designed to solve the proposed problem. Numerical experiments are conducted to compare the performance of the multiple yard crane systems in container terminals with and without buffer areas.
Impact of Land Bridge on Port Market Area
Authors: Wang Xinchang , Meng Qiang , Miao Lixin , Fwa T. F.
Published: September 2009

A land bridge as an intermodal freight transport mode seamlessly integrates long-haul rail and short-haul truck services to provide transcontinental delivery of containers that can be alternatively transported by maritime transport mode. To evaluate the impact of the Myanmar–China international land bridge on the Shanghai, China, port, this paper first proposes a novel concept of the probability-based port market area to measure the service area of a port by assuming that costs and times of the intermodal freight transport routs are the normal distributed random variables. The analytical expression of the probit-based market area of the Shanghai port is then derived for two competing transport routes to the Dubai port: one involves the Myanmar–China land bridge and the other uses the direct port-to-port maritime link. The probability-based market area curves in relation to transport cost and time of the Shanghai port are established for two operational scenarios of the Myanmar–China land bridge: ( a) current state of operation and ( b) a possible future state of operation with efficiency similar to that of the U.S. continental land bridge operation. Each of these curves possesses one branch of a hyperbola curve representing a contour of the impact level of the land bridge on the Shanghai port. Differences of the impact contours of the two scenarios provide an indication of the market area of the Shanghai port that will be affected by changes in the efficiency of the land bridge operation.
Free Trade Agreement Effects in the Mediterranean Region
Authors: Kepaptsoglou Konstantinos , Tsamboulas Dimitrios , Karlaftis Matthew G. , Marzano Vittorio
Published: September 2009

Free trade agreements (FTAs) are tools that have been widely implemented for enhancing trade between countries. As a result, various models have been developed in an effort to explain the effects of these agreements on trade. The objective of this study is to develop a model suitable for exploring FTA effects on trade flows in the Mediterranean region. For that purpose a model is developed for analyzing trade flows based on the family of gravity models; the model parameters are estimated by using the seemingly unrelated regression estimation approach, in an effort to account for cross-sectional heterogeneity, serial correlation, and heteroscedasticity in the data set used. Results of the derived models are discussed and indicate that FTA effects on trade flows do exist but remain relatively low compared with other factors such as transportation costs.
Evaluation of Impacts of Intermodal Terminals on the Highway System
Authors: Bhamidipati Chiranjivi Sarma , Demetsky Michael J.
Published: September 2009

Rail–truck intermodal terminals can play a key role in making rail–truck intermodal transportation an effective transportation alternative to long-haul trucking. To measure this effectiveness, public and private stakeholders require some qualitative and quantitative methodologies. This paper is based on a study describing a general methodological framework for evaluation of the impacts of intermodal terminals on the transportation system and applying it to the highway system of Virginia. Apart from incorporating the needs of several agencies into the framework, preliminary models for site-specific evaluation of impacts on mobility, accessibility, safety, and economic activities were also developed, and were calibrated with commodity flow, socioeconomic, and other data for the Commonwealth of Virginia. Results of the application of the evaluation framework on a case study terminal are presented in this paper. The study identified the key steps involved in the assessment of highway system impacts and regional planning of intermodal terminals in Virginia. It is recommended that further research be carried out on a detailed evaluation to provide decision support on the feasibility of public–private shared financing of intermodal terminals.
Resources to Minimize Disruption Caused by Increased Security Inspection of Containers at an Intermodal Terminal
Authors: Harris Gregory A. , Schroer Bernard J. , Anderson Michael D. , Moëller D. P. F.
Published: September 2009

This paper presents the application of simulation to determine the inspection resources needed to minimize disruption resulting from increased security inspection of containers at an intermodal terminal. The initial simulation run intentionally started with a large number of resources. Additional simulation runs were made with a continual reduction of inspection resources until entity throughput at the terminal dropped below allowable limits. Simulation Run 9, with six tailgate inspection stations, three intensive inspection stations, and one general purpose inspector, provided the minimum resources that did not disrupt container throughput. This paper includes the description of the conceptual model framework, the simulation model, the experimental design, and simulation results.
Improving the Safety of Transportation of Dangerous Goods
Authors: Elshafey M. M. , Contestabile E. , Abd El Halim A. O. , Isgor O. B.
Published: September 2009

The transportation of dangerous goods (DG) represents an important portion of the overall freight transport worldwide. Ground transport (excluding pipelines) moves approximately 21% to 31% of the total tonnage of DG in Canada. Accidents involving DG might occur at any time at any location along transport routes or within storage areas, and not only do they have an effect on people and the environment, but also they can have a great effect on the national economy. This paper presents the details of an experimental investigation studying the blast attenuation capability of suppressive shield panels (SSPs). Suppressive shield technology can be used for the storage, processing, and transport of explosive materials and can also be applied to protecting attractive targets and infrastructure deemed vulnerable to explosive attacks. Various configurations of commercially available steel angles were assembled as SSPs and evaluated for their ability to attenuate blast pressure from detonating Pentolite charges. Results obtained from the tests with 0.5-kg charges indicated that the SSPs attenuate the blast pressure to values in the range of 43% to 60%. The results of this research can be extended to include the design and construction of SSPs for transportation of DG by sea as well. Effectively, this can include the strengthening of current standard containers.
Communication and Interpretation of Results of Route Risk Analyses of Hazardous Materials Transportation by Railroad
Authors: Kawprasert Athaphon , Barkan Christopher P. L.
Published: September 2009

Route risk analysis of hazardous materials transportation by railroad is receiving considerable new attention from industry and government. Such analyses are necessary for effective public policy and development of rational risk management strategies. However, route risk analysis is complex and generates results that can be difficult to properly interpret. Risk analyses are intended to provide risk managers with objective information about how to effectively manage risk and the most effective options to reduce it. This paper uses results from a quantitative risk analysis of hazardous materials shipped by rail to develop and illustrate several new techniques to present, interpret, and communicate risk results more effectively. The analysis accounted for the major factors affecting risk: infrastructure quality, traffic volume, and population exposure along shipment routes, as well as tank car design and product characteristics. Approaches for system-level and route-specific analyses are presented. Both absolute and normalized estimates of risk provide useful information. The question of interest and the user affects which type of information is most useful for effective decision making. Various graphical techniques enable risk metrics to be compared and contrasted, either in a geographic context or independent of it, depending on which is most useful. Identifying the locations that account for the highest concentration of risk and understanding the contributing factors will also clarify the mutual roles of carriers, shippers, and municipalities along a route in regard to risk management, reduction, and mitigation options. In addition, the techniques presented in this paper may also be useful for regulators and researchers who might be interested in a broader view of risk analysis at the network level.
Radio Frequency Identification Tracking Technology Applied to Testing of Transportation Construction Materials
Authors: Ross Weslie A. , Burns Susan E. , Wu Peter Y. , Jared David M.
Published: September 2009

This study tested the applicability of radio frequency identification (RFID) technology to tracking the progress of construction materials being tested by the Georgia Department of Transportation (GDOT) Office of Materials and Research (OMR). OMR receives and tests thousands of construction samples each year and currently tracks them with a paper-based system. The work in this investigation focused on RFID tracking technology, specifically read-only, passive, ultra-high-frequency tags. Because of their balance between low-cost and tracking capabilities, both handheld and fixed (portal) readers were used for tracking and identification of the applied tags. This study demonstrated that RFID tags were durable enough to be used under the harsh testing conditions in the laboratory, specifically extremes of moisture, pH, temperature, and pressure. In addition, the study demonstrated that the technology can be used for sample tracking in the laboratory and for location of misplaced samples. Finally, when integrated with an information technology database, such as GDOT's Materials Information Management System, the use of RFID technology will facilitate productivity within the testing scheme by time stamping a sample's progress through the laboratory and identifying delays and bottlenecks in the system.
Priority-Ranking Workload Reduction Strategies to Address Challenges of Transportation Construction Inspection
Authors: Jagars-Cohen Chelsea A. , Menches Cindy L. , Jangid Yetendra K. , Caldas Carlos H.
Published: September 2009

Throughout the past decade, the Texas Department of Transportation (TxDOT) has experienced an average increase in funding for projects of more than 44%. Similarly, other state departments of transportation (DOTs) have also seen significant funding increases. As a result, DOTs have been able to complete projects that would not have been feasible without the additional funding. However, the additional funding has also brought about an increase in the construction inspection and testing workload for these projects, but DOTs have not seen a sufficient increase in personnel to manage the additional work. As a result, TxDOT was motivated to identify efficient strategies for reducing the construction testing and inspection workload without decreasing the quality of the end product. TxDOT turned to other states facing a similar situation that were innovatively and efficiently addressing their challenges. Other states have implemented programs that include increasing contractor testing and inspection responsibilities, outsourcing testing and inspection to third parties, creating extensive training and certification programs, and modifying their specifications to minimize time-intensive testing and measurement. This study investigated current practices in other state DOTS and summarized workload reduction strategies that can reduce inspection workload. A list has been developed of the best workload reduction strategies that show the greatest potential for efficiently reducing the testing and inspection workload for TxDOT. The workload reduction strategies have also been priority-ranked for future implementation at TxDOT.
Development of Decision Model for Selection of Appropriate Timely Delivery Techniques for Highway Projects
Authors: Sillars David N.
Published: September 2009

On-time project performance is an important goal at the Oregon Department of Transportation (ODOT); pressure from two key constituents—the state legislature and trucking interests—creates an even stronger focus on this goal. Currently, statistics indicate that less than 50% of ODOT projects are completed within their originally contracted time of performance. Further, project delay causes uncertainty about exactly when traffic delays may occur on a given stretch of highway and makes it difficult to alert the public of these delays far in advance. The primary umbrella method used to ensure on-time performance in standard ODOT contracting is liquidated damages. Often this amount is difficult to determine, so the assessment value is usually a matter of some judgment. In practice, liquidated damages is not seen as an effective incentive and is thus rarely assessed. Other contracting and management methods that focus on encouraging on-time performance have been identified but are used sporadically. Implementation of a system that creates better awareness of alternative schedule delivery methods and that provides a consistent method for choosing among these methods would improve ODOT's schedule performance. Results are discussed of a research project (ODOT SPR-646) designed to enable development of a tool to assist in selection among various available alternative methods for ensuring timely project delivery, given a specific project profile, by using a selection model that is stable and scalable.
Testing and Performance Evaluation of Fixed Terrestrial Three-Dimensional Laser Scanning Systems for Highway Applications
Authors: Hiremagalur Jagannath , Yen Kin S. , Lasky Ty A. , Ravani Bahram
Published: September 2009

In many three-dimensional (3-D) laser scanner applications, high relative precision (relative dimensions within the registered point cloud) is sufficient; in contrast, highway infrastructure (HI) applications require good relative precision and high absolute accuracy. Thus, precise and robust georeferencing is critical, and robust work flows are needed to reduce the likelihood and impact of human errors. HI applications have a fairly unique combination of challenges, including longer-range requirements, long linear geometry for complete jobs, tall structures, and dark pavement scanned at a high incidence angle. These factors motivate standardized protocols and metrics to characterize and evaluate scanner performance and to develop confidence limits for the scanner data in such applications. The primary contribution in this study is a set of standard test protocols for the characterization and evaluation of 3-D laser scanner performance that users can conduct in easily accessible facilities. These evaluations focus on issues significant in HI survey applications, work flows, and data flows. An example performance evaluation is provided for several commercially available 3-D laser scanners. This study provides the needed scientific basis for data-driven deployment of this valuable measurement tool in HI applications. It also provides recommendations and guidelines that will promote consistent and correct use of 3-D laser scanners. The guidelines clarify the common limitations of 3-D laser scanners and recommend mitigation methods; this information will help engineers and surveyors to select the right scanner and determine optimum scanning settings for highway applications.
Application of Uncertainty Analytic Hierarchy Process Method for Asphalt Pavement Construction Quality Control in China
Authors: Guo Dajin , Zhou Wenhuan , Sha Aimin , Bai Ruyue
Published: September 2009

A comprehensive asphalt pavement construction quality control evaluation system and a computer program for this system were developed to improve asphalt pavement construction quality in China. The system was developed on the basis of the uncertainty analytic hierarchy process and used a large amount of data collected from actual asphalt paving construction projects and laboratory test results from various provinces and regions in China. The 33 indices incorporated into the system were selected by a panel of Chinese asphalt pavement experts. The indices included parameters related to materials, equipment, personnel, and the construction process that were deemed important in improving quality and performance of asphalt pavements. Weight factors for each of the 33 indices and the higher-level parameters in the three-level hierarchy system were generated by utilizing the uncertainty concept, which allowed the experts to assign relative importance between any related pairs of indices. The program was able to generate rating scores for asphalt pavement construction quality. Through evaluation of the rating scores among the parameters and indices generated by the system, potential problems in an asphalt pavement construction project could be detected in a timely manner and corrective actions applied to remediate the deficiencies detected by the system. The system, the first of this kind developed for assessing the quality control of asphalt pavement construction in China, has been used to monitor several major asphalt pavement construction projects in the country.
Quality Control–Quality Assurance Sampling Strategies for Hot-Mix Asphalt Construction
Authors: Tsai Bor-Wen , Monismith Carl L.
Published: September 2009

The effects of sampling strategies and size on statistically based decision making in hot-mix asphalt (HMA) construction are presented. For sample sizes agreed on by the agency and the contractor, an acceptable level for an HMA mix parameter is determined with risk balanced between the two organizations. With increased emphasis on specific performance requirements, the use of performance tests on HMA specimens prepared from in situ samples is developing. Examples include direct measures of mix stiffness and permanent deformation characteristics. A measure of rutting resistance, the stabilometer S-value, is used by the California Department of Transportation (Caltrans) for quality control–quality assurance (QC/QA) projects. Although the S-value was used for this simulation because extensive tests were available, this approach is applicable to any performance measures already in use, such as HMA thickness or compacted air void content. A sampling scheme and sampling size through statistical simulation of a fixed length of a one-lane-width placement of HMA are discussed. Sample size is based on the combination of the sample size of the contractor and that of the agency to balance the risk to both organizations and results in a mix that will meet the minimum performance requirement. An example is given for the placement of 15,000 tons of HMA according to Caltrans QC/QA requirements. For this total tonnage, the contractor and agency are respectively assumed to perform a specific number of stabilometer tests for QC and QA. Results of the simulation yield the average stabilometer value that the contractor must obtain to ensure that the quality requirement, that is, the minimum S-value, is met.
Analyzing Hot-Mix Asphalt and Portland Cement Concrete Highway Construction Using Probabilistic Optimization for Profit
Authors: Rao Shreenath , Vidalis Sofia M. , Smith Kelly , Kopac Peter A.
Published: September 2009

Contractors constantly have to make decisions about maximizing profits while considering risks associated with choosing construction target levels for various acceptance quality characteristics (AQCs). With more and more states adopting incentive–disincentive pay adjustment provisions for quality as measured by various AQCs, a contractor likely has to evaluate several options before selecting an optimum target quality that will maximize profit at an acceptable level of risk. The greater the number of AQCs, the more complex the assessment that the contractor is required to perform and the less intuition and experience can be relied on. The updated Probabilistic Optimization for Profit (Prob. O. Prof. 2.0) is a computer program used as a probabilistic-based tool designed to assist portland cement concrete and hot-mix asphalt paving contractors in evaluating statistical quality assurance specifications. In addition, it assists the highway agencies in evaluating the appropriateness of their specifications and ensuring that they have no undesirable consequences. This procedure allows the agency to adjust pay factors accordingly while developing specifications. The Prob. O. Prof. 2.0 program is discussed, and examples of its use are provided.
Design and Construction of Sustainable Pavements
Authors: Tompkins Derek , Khazanovich Lev , Darter Michael I. , Fleischer Walter
Published: September 2009

Several recent efforts in U.S. pavement research deal with creating sustainable technologies and designs that use composite pavements, that is, pavements with heterogeneous asphalt, concrete layers, or both, resulting from new construction. Although there are several asphalt-over-concrete composites in the United States, in the case of two-layer portland cement concrete (PCC) pavements there has been little research or expertise in the United States despite the wide acceptance of two-layer PCC as a solution for pavements in parts of the European Union (EU). The EU experience is described in this paper in terms of German and Austrian case studies. After the case studies, the major benefits of two-layer PCC and potential challenges in importing, adapting, and implementing German and Austrian techniques are discussed.
Evaluation of Dowel Alignment Constructability in Portland Cement Concrete Pavements
Authors: Rao Shreenath , Hoegh Kyle , Yu Thomas , Khazanovich Lev
Published: September 2009

Although dowel bars are an essential design feature of jointed concrete pavements to prevent pumping and faulting, few studies dealing with the constructability of dowel alignment have been conducted. With the emergence of the Magnetic Imaging Tools (MIT) Scan-2 as a nondestructive, robust method of locating dowels, it is now possible to efficiently evaluate the construction quality of dowel bar placement without damaging the newly constructed pavement. A brief review is presented of the results of recent field studies aimed at examining the constructability of doweled joints in concrete pavements. The dowel bar alignment data collected in this study encompass a wide range of design and environmental conditions and show that alignment within reasonable levels—considering equipment, mix design, as well as workmanship and consistency—is achievable in the field. Distress and performance analyses show that within these levels of misalignment, the pavement performance is not significantly affected. However, misalignment at a greater level may not be detrimental to pavement performance, and therefore performance-based guidelines may be less strict than the constructability levels collected in this study. Nevertheless, the results shed light on the level of alignment that can be reasonably achieved in the field.
Temperature Behavior of Pervious Concrete Systems
Authors: Kevern John T. , Schaefer Vernon R. , Wang Kejin
Published: September 2009

To achieve the permitted stormwater effluent limits required by the Clean Water Act, many best management practices (BMPs) are being utilized to reduce the overall stormwater volume and provide initial pretreatment and pollutant removal. One such BMP is use of portland cement pervious concrete (PCPC), which allows stormwater to pass through the pavement into an aggregate base below to infiltrate. Until now, the temperature response of the entire system (concrete, aggregate base, and natural soil) was not known. Since PCPC is an infiltration-based BMP, once a frost line forms under the base the infiltrating capacity is reduced or eliminated. PCPC also is recommended for use in warmer climates as a cooler pavement alternative to conventional concrete or asphalt. To quantify the temperature behavior of a pervious concrete system, a fully monitored parking lot—composed of half traditional concrete and half PCPC—was constructed at Iowa State University as part of the Iowa Pervious Concrete Stormwater Project. Sensors were installed through the profile of both pavements and into the underlying soil. The results show that insulation from the aggregate base underneath the pervious concrete substantially delays the formation of a frost layer and permeability is restored when meltwater is present. It was also observed that in direct sunlight, the pervious pavement became hotter than traditional concrete, whereas the daily low temperature of the two was similar, indicating less heat storage capacity in the pervious concrete.
Asphalt Mix Design Optimization for Efficient Plant Management
Authors: Awuah-Offei Kwame , Askari-Nasab Hooman
Published: September 2009

The role of aggregate gradation in hot-mix asphalt performance is well documented in the literature. Yet the Bailey method is the only tool available for guidance on aggregate gradation selection for optimal performance. Also, there is a lack of tools for design engineers and plant managers of quarry sites to manage stockpile inventory levels and control cost of aggregate used in asphalt mixes. This work presents a linear programming model of the asphalt mix design problem and a numerical algorithm to solve the model. The algorithm is implemented in MATLAB as an asphalt mix design optimization (AMIDO) program. The program is successfully verified with an example. The results show that using the Bailey method alone results in suboptimal results and that cheaper mixes with similar aggregate ratios can be designed with the same aggregate stockpiles. For the specific stockpiles used in the verification, the AMIDO mix design resulted in a 53-cent/ton reduction in aggregate cost. This work improves the state of the art in asphalt mix design for dense-graded mixes and could be modified for other mixes.