bluuebunny/crossref_metadata_2025 huggingface dataset:
Earthworms as indicators for different forest management types and human disturbance in Ilam oak forest, Iran
Authors: Heydari Mehdi , Poorbabaei Hassan , Bazgir Masoud , Salehi Ali , Eshaghirad Javad
Published: February 2015

There has been observed widespread destruction of natural ecosystems around the world due to population growth, land use change and clear cutting which have affected soil properties. Different management strategies have been so far implemented to reduce this crisis in various regions of the world, such as e.g. short-term and long-term conservation management in the Zagros region. However, any management approach should be evaluated with appropriate measures to determine how managed areas respond. The main objective of the present study was to evaluate the potential of earthworms as an indicator for different forest management strategies and human disturbances in Zagros oak (Quercus persica Jaub. and Spach) forest. The sites selected included undisturbed one as the control (Un), the sites under five-year conservation management (FCM) and twenty-year conservation management (TCM) as well as the disturbed site (D). The results of principal component analysis (PCA) showed that different regions separated into the components: PC1 and PC2. Un and TCM sites gathered together and represented higher values of the factors such as pH, Kavailable, OC, clay content, Pavailable, CEC, overstory tree canopy, Ntot, biomass and abundance of earthworms. The positive direction of the first axis reflected a gradient of EC, BD and Ptot. According to the logistic model, NH4-N and EC played the most important role in earthworm presence and absence in Zagros forest ecosystem. Earthworm abundance and biomass could be a good indicator to evaluate different forest management strategies in the study area.
Intelligibility Assessment of Ideal Binary-Masked Noisy Speech with Acceptance of Room Acoustic
Authors: Vladimír Sedlak , Daniela Durackova , Roman Zalusky , Tomas Kovacik
Published: February 2015

In this paper the intelligibility of ideal binary-masked noisy signal is evaluated for different signal to noise ratio (SNR), mask error, masker types, distance between source and receiver, reverberation time and local criteria for forming the binary mask. The ideal binary mask is computed from time-frequency decompositions of target and masker signals by thresholding the local SNR within time-frequency units. The intelligibility of separated signal is measured using different objective measures computed in frequency and perceptual domain. The present study replicates and extends the findings which were already presented but mainly shows impact of room acoustic on the intelligibility performance of IBM technique.
Nonlinear Predictive Control of Wind Energy Conversion System Using Dfig with Aerodynamic Torque Observer
Authors: Kamel Ouari , Mohand Ouhrouche , Toufik Rekioua , Taib Nabil
Published: February 2015

In order to improvement of the performances for wind energy conversions systems (WECS), an advanced control techniques must be used. In this paper, as an alternative to conventional PI-type control methods, a nonlinear predictive control (NPC) approach is developed for DFIG-based wind turbine. To enhance the robustness of the controller, a disturbance observer is designed to estimate the aerodynamic torque which is considered as an unknown perturbation. An explicitly analytical form of the optimal predictive controller is given consequently on-line optimization is not necessary The DFIG is fed through the rotor windings by a back-to-back converter controlled by Pulse Width Modulation (PWM), where the stator winding is directly connected to the grid. The presented simulation results show a good performance in trajectory tracking of the proposed strategy and rejection of disturbances is successfully achieved.
McEliece PKC Calculator
Authors: Marek Repka
Published: February 2015

The original McEliece PKC proposal is interesting thanks to its resistance against all known attacks, even using quantum cryptanalysis, in an IND-CCA2 secure conversion. Here we present a generic implementation of the original McEliece PKC proposal, which provides test vectors (for all important intermediate results), and also in which a measurement tool for side-channel analysis is employed. To our best knowledge, this is the first such an implementation. This Calculator is valuable in implementation optimization, in further McEliece/Niederreiter like PKCs properties investigations, and also in teaching. Thanks to that, one can, for example, examine side-channel vulnerability of a certain implementation, or one can find out and test particular parameters of the cryptosystem in order to make them appropriate for an efficient hardware implementation. This implementation is available [1] in executable binary format, and as a static C++ library, as well as in form of source codes, for Linux and Windows operating systems.
Achieving an Equilibrium Position of Pendubot Via Swing-Up and Stabilizing Model Predictive Control
Authors: Martin Gulan , Michal Salaj , Boris Rohal'-Ilkiv
Published: February 2015

In this paper, a complex control strategy to swing-up and balance the under-actuated pendubot system in one of its unstable equilibrium positions is presented. The initial swing-up maneuver is performed using an energy-based approach. For the purposes of stabilizing the system in its mid unstable equilibrium position a model predictive controller based on optimal control law with integral action is proposed. Satisfaction of constraints is ensured by introducing perturbations in the LQ control law acting as corrections when input amplitude/rate bounds are to be exceeded. The stability issue is addressed via additional constraints imposed on the terminal set. The emphasis of the paper is on the experimental realization of the pendubot swing-up followed by its balancing, which reveals the accuracy of the proposed control scheme.
An Impact of Thermodynamic Processes in Human Bodies on Performance Reliability of Individuals
Authors: Smalko Zbigniew
Published: February 2015

The article presents the problem of the influence of thermodynamic factors on human fallibility in different zones of thermal discomfort. Describes the processes of energy in the human body. Been given a formal description of the energy balance of the human body thermoregulation. Pointed to human reactions to temperature changes of internal and external environment, including reactions associated with exercise. The methodology to estimate and determine the reliability of indicators of human basal acting in different zones of thermal discomfort. The significant effect of thermodynamic factors on the reliability and security ofperson.
A Multi-Valued Diagnostic Model Synthesis Based on Descrete Wavelet Transform
Authors: Borowczyk Henryk
Published: February 2015

The method of a multi-valued diagnostic model synthesis using discrete wavelet transform is presented. The method's algorithm consists of three stages: (1) - signal decomposition into low- and high frequency parts - approximations and details, (2) - approximations and details parameterization, (3) - multi-valued encoding parameters obtained in stage 2. The method is illustrated with vibroacoustic signal in real life experiment. The multi-valued diagnostic model is the final result.
Semi-Analytical Solution of Functionally Graded Circular Short Hollow Cylinder Subject to Transient Thermal Loading
Authors: Eskandari Jam Jafar , Nezhad Y. Rahmati
Published: February 2015

In this paper, by using a semi-analytical solution based on multi-layered approach, the authors present the solutions of temperature, displacements, and transient thermal stresses in functionally graded circular hollow cylinders subjected to transient thermal boundary conditions. The cylinder has finite length and is subjected to axisymmetric thermal loads. It is assumed that the functionally graded circular hollow cylinder is composed of N fictitious layers and the properties of each layer are assumed to be homogeneous and isotropic. Time variations of the temperature, displacements, and stresses are obtained by employing series solving method for ordinary differential equation, Laplace transform techniques and a numerical Laplace inversion.
Rehabilitation Robot Prototypes Developed by the ITAM Zabrze
Authors: Michnik Andrzej , Brandt Jacek , Szczurek Zbyszek , Bachorz MichaŁ , Paszenda Zbigniew , Michnik Robert , Jurkojć Jacek , Rycerski Wiesław , Janota Jan
Published: February 2015

Limb physical movements disability is the result of illnesses or serious injuries, impaired execution of daily activities and limitations or even inability to perform working activity. Restoration of fitness in such cases is possible through rehabilitation that requires arduous repetition of appropriate exercises with participation of an experienced physiotherapist. Exercises using the robot to repeat movements would speed up the process of rehabilitation. The paper presents the concept of rehabilitation robot control system realizing a specified purpose.
Effect of Tool Geometry and Welding Speed on Mechanical Properties and Microstructure of Friction Stir Welded Joints of Aluminium Alloys AA6082-T6
Authors: Patil Hiralal Subhash , Soman Sanjay N.
Published: February 2015

Friction stir welding is a solid state innovative joining technique, widely being used for joining aluminium alloys in aerospace, marine automotive and many other applications of commercial importance. The welding parameters and tool pin profile play a major role in deciding the weld quality. In this paper, an attempt has been made to understand the influences of welding speed and pin profile of the tool on friction stir welded joints of AA6082-T6 alloy. Three different tool pin profiles (tapered cylindrical four flutes, triangular and hexagonal) have been used to fabricate the joints at different welding speeds in the range of 30 to 74 mm/min. Microhardness (HV) and tensile tests performed at room temperature were used to evaluate the mechanical properties of the joints. In order to analyse the microstructural evolution of the material, the weld’s cross-sections were observed optically and SEM observations were made of the fracture surfaces. From this investigation it is found that the hexagonal tool pin profile produces mechanically sound and metallurgically defect free welds compared to other tool pin profiles.
A Two-Dimensional Discrete Model for Dynamic Analysis of Belt Transmission with Dry Friction
Authors: Kubas Krzysztof
Published: February 2015

The paper presents a model for dynamic analysis of belt transmission. A twodimensional discrete model was assumed of a belt consisting of rigid bodies joined by translational and torsion spring-damping elements. In the model, both a contact model and a dry friction model including creep were taken into consideration for belt-pulley interaction. A model with stiffness and damping between the contacting surfaces was used to describe the contact phenomenon, whereas a simplified model of friction was assumed. Motion of the transmission is triggered under the influence of torque loads applied on the pulleys. Equations of motion of separate elements of the belt and pulleys were solved numerically by using adaptive stepsize integration methods. Calculation results are presented of the reaction forces acting on the belt as well as contact and friction forces between the belt body and pulley in the sample of the belt transmission. These were obtained under the influence of the assumed drive and resistance torques.
Investigation of the Stress-Strain State of Seamless Pipe in the Initial State
Authors: Malachowski Jerzy , Hutsaylyuk Volodymyr , Yukhumets Petr , Dmitryenko Roman , Beliaiev Grigorii , Prudkii Ihor
Published: February 2015

Mechanical properties of the pipeline samples that had been cut in annular and axial directions were investigated. The methodology of modeling and calculation of the real stress-strain state was described. The stable state during in the deformation process was defined. The results of the experimental researches were used as a test variant during examination of pipe strength.
Structural Health Monitoring (SHM) Methods in Machine Design and Operation
Authors: Barski Marek , Kedziora Piotr , Muc Aleksander , Romanowicz Paweł
Published: February 2015

The present paper is devoted to the discussion and review of the non-destructive testing methods mainly based on vibration and wave propagation. In the first part, the experimental methods of actuating and analyzing the signal (vibration) are discussed. The piezoelectric elements, fiber optic sensors and Laser Scanning Doppler Vibrometer (SLDV) method are described. Effective detecting of the flaws needs very accurate theoretical models. Thus, the numerical methods, e.g. finite element, spectral element method and numerical models of the flaws in isotropic and composite materials are presented. Moreover, the detection of the damage in structures, which are subjected to cyclic or static loads, is based on the analyzing of the change in natural frequency of the whole structure, the change of internal impedance of the material and the change in guided waves propagating through the investigated structure. All these cases are characterized in detail. At the end of this paper, several applications of the structural health monitoring systems in machine design and operation are presented.
Towards a general theory of landscape systems: the integration of the geoecological and bioecological approaches
Authors: Tandarić Neven
Published: February 2015

Ever since its beginnings, landscape ecology has been developing in two different directions: the bioecological and the geoecological. While the bioecological approach is focused on the relationship between organisms and their abiotic environment, the geoecological approach is based on the relationship between human society and its, primarily abiotic, environment. Therefore, the geoecological approach can be applied in planning human use of the environment in a long term sustainable manner, while the bioecological approach could represent the basis for the planning of conservational and environmental usage. The merging of these two approaches will result in a comprehensive and more holistic landscape ecology, which will thus gain the potential for coordinating interdisciplinary landscape research and a more prominent role in contributing to spatial planning. The merge will also enhance attempts to create a general theory of landscape systems.
The public and economic aspects of the functioning of protected areas within a commune
Authors: Jaros Henryk
Published: February 2015

Between 2009 and 2013, research was conducted in the commune offices for the Podlaskie voivodeship which have large areas of protected Natura 2000 sites. The research is repeated every few years and widened to include new communes. The aim of the research was to determine the influence of the protected areas on the economic conditions of the communes. It is widely assumed that protected areas generate income for communes, however the communes claim that they incur large additional costs. The surveyed communes were critical of obligatory legal requirements in relation to the protected areas. It was argued that there are problems with obtaining natural resources and with the establishment of new summer resorts, residential and farm buildings and infrastructure; as well as the use and management of the site. The communes’ benefits incidental to the ownership of the protected area are not clear. As part of the benefits, the protected areas offer an opportunity for tourism development. According to the communes, protected areas generate losses in which the estimated losses are several times higher than the potential income. Studies indicate that the conservation cost factor should be considered in terms of financing the communes from the state budget.
Cide-A Gene Expression in Patients with Obesity Qualified for Endovascular Treatment of Abdominal Aorta Aneurysm
Authors: Feldo Marcin , Kocki Janusz , Feldo Jan , Łukasik Sylwia , Bogucki Jacek , Skwarzyński Adam , Wroński Jacek , Kęsik Jan , Zubilewicz Tomasz
Published: February 2015

gene and the genes of LRP group play a key role in the regulation of the body weight and lipid metabolism in mammals.

was to define the role of

. The study group consisted of 38 subjects, including 27 men and 11 women qualified for endovascular aneurysm repair (EVAR). The subjects with abdominal aortic aneurysm were enrolled in the study group, depending on the body mass index (BMI); in obese patients (BMI > 30). The control group (n = 16) included subjects without lipid disorders. One-step isolation of RNA from lymphocytes and adipose tissue cells was performed using the modified TRI method by Chomc-zynski and Sacchi, and then the gene expression was tested by real-time PCR.

. The highest mean relative of the gene expression for

. Due to the important role of the
First Observation of the Yellow-Browed Warbler Phylloscopus Inornatus in Romania
Authors: Bolboacă Lucian-Eugen , Baltag Emanuel Ştefan , Fasolă-Mătăsaru Lucian , Ion Constantin
Published: February 2015

The Yellow-browed Warbler is a species of the Sylviidae family that breeds in Asia and winters in South East Asia and western Europe. In northern and north-western Europe it is considered one of the most numerous nocturnal migratory species from Siberia. In the southern and eastern part of the continent there are fewer observations of the presence of the species in passage or in winter. On 29 September 2013, during a ringing session in the southern part of the Danube Delta (Romania), we captured a juvenile individual of the Yellow-browed Warbler. This is the first record of the species in Romania.
Fracture Through an Enthesophyte on the Olecranon Process
Authors: Hoppes Carrie W. , Jonson Scott R.
Published: February 2015

The patient was a 54-year-old man who was currently serving in the military. He was evaluated by a physical therapist in a direct-access capacity for a chief complaint of left elbow pain that began 3 weeks prior. The physical therapist ordered radiographs, which revealed a linear lucency through a large enthesophyte at the insertion of the triceps tendon on the olecranon process that was consistent with a fracture.

J Orthop Sports Phys Ther 2015;45(2):143. doi:10.2519/jospt.2015.0402
Report of the NIH Task Force on Research Standards for Chronic Low Back Pain
Authors: Deyo Richard A. , Dworkin Samuel F. , Amtmann Dagmar , Andersson Gunnar , Borenstein David , Carragee Eugene , Carrino John , Chou Roger , Cook Karon , Delitto Anthony , Goertz Christine , Khalsa Partap , Loeser John , Mackey Sean , Panagis James , Rainville James , Tosteson Tor , Turk Dennis , Von Korff Michael , Weiner Debra K.
Published: February 2015

Note fr'5ym PTJ's Editor in Chief: Both investigators and readers get frustrated reading research on low back pain because of different definitions of “chronic” and different outcome measures. Lack of consensus on study methods makes it difficult to determine if contradictory findings are based on different methods or different interventions; lack of consensus also prevents synthesis across studies. Dr. Partap Khalsa, Deputy Director, National Center for Complementary and Integrative Health, announced the release of Research Standards for Chronic Low Pain, and the hope is that future investigations will adopt them and reduce variability in research reporting. The task force on research standards was an international, multidisciplinary team including Anthony Delitto, PT, PhD, FAPTA. Its findings have been published in leading pain journals. PTJ is among the first professional journals to share the report with its readers.

Despite rapidly increasing intervention, functional disability due to chronic low back pain (cLBP) has increased in recent decades. We often cannot identify mechanisms to explain the major negative impact cLBP has on patients' lives. Such cLBP is often termed non-specific and may be due to multiple biologic and behavioral etiologies. Researchers use varied inclusion criteria, definitions, baseline assessments, and outcome measures, which impede comparisons and consensus. Therefore, NIH Pain Consortium charged a Research Task Force (RTF) to draft standards for research on cLBP. The resulting multidisciplinary panel recommended using 2 questions to define cLBP; classifying cLBP by its impact (defined by pain intensity, pain interference, and physical function); use of a minimum dataset to describe research participants (drawing heavily on the PROMIS methodology); reporting “responder analyses” in addition to mean outcome scores; and suggestions for future research and dissemination. The Pain Consortium has approved the recommendations, which investigators should incorporate into NIH grant proposals. The RTF believes that these recommendations will advance the field, help to resolve controversies, and facilitate future research addressing the genomic, neurologic, and other mechanistic substrates of chronic low back pain. We expect that the RTF recommendations will become a dynamic document and undergo continual improvement. Perspective: A task force was convened by the NIH Pain Consortium with the goal of developing research standards for chronic low back pain. The results included recommendations for definitions, a minimum dataset, reporting outcomes, and future research. Greater consistency in reporting should facilitate comparisons among studies and the development of phenotypes.
Verbal autopsy of neonatal deaths in Khatauli Block of District Muzaffarnagar, Uttar Pradesh, India
Authors: Muzammil K , Singh JV , Shankar R
Published: February 2015

BackgroundVerbal autopsy is a method of inquiry to ascertain the likely cause of death in populations where vital registration of deaths is incomplete and unreliable. Over 75% of deaths in India occur at homes; more than half of these do not have a certified cause. Further, most of the deaths in the rural areas of India occur at home and that is why a medical certification by a qualified practitioner is not possible. Keeping these facts in mind, this study was designed having objectives as to find out the causes of neonatal deaths through verbal autopsy and its feasibility to be used by health workers.Material & Methods:This cross-sectional epidemiological study was conducted in randomly selected rural areas of Khatauli Block of District Muzaffarnagar, Uttar Pradesh, India. Verbal autopsy data was collected by a team of health workers adequately trained for the same well in advance. Data related to reported neonatal deaths in the study area in the specified period of time was collected on structured & pre-tested questionnaire used as study tool by interviewing the parents, relatives or neighbours of the deceased. Data thus collected was verified twice by the coordinator and principal investigator respectively and analyzed by using Epi info statistical package.Results:A total of 24 perinatal deaths were reported, out of which 7 (29.2%) were stillbirth and 17 (70.8%) were neonatal deaths. ANC was received by 14 mothers (58.3%). Half of the deliveries were conducted by untrained Dai. About 20 deliveries (83.3%) were at home and 10 (58.8%) of the deceased were early neonates. The cause of deaths found by means of verbal autopsies were mainly: pneumonia - 4 (23.5%), diarrhoea - 2 (11.8%) neonatal jaundice - 03 (17.6%) etc.Conclusion:Pneumonia, diarrhoea & neonatal jaundice alone constitute about 53% of the total neonatal deaths. The use of the verbal autopsy tool by health workers to find out the cause of neonatal deaths is very much feasible.DOI: http://dx.doi.org/10.3126/nje.v4i5.12019 Nepal Journal of Epidemiology 2014; 4(5):423-27
Urban Freight Consolidation Centers
Authors: Triantafyllou Maria K. , Cherrett Tom J. , Browne Michael
Published: February 2015

In recent years, traditional urban distribution systems have undergone major structural changes as a result of the increasing power of customers demanding greater variety of quality products at low cost. These customer demands have increased the competition between businesses, and at the same time more complicated and longer supply chains have emerged as a result of the globalization of many businesses in their search for low-cost production locations and access to new skills. In response, hub-and-spoke systems are increasingly used to deal with product flows from many origins and to many destinations. As a result, a growing number of studies have examined the establishment of various forms of intermodal transshipment centers to minimize the use of roads in city centers and support the frequent and rapid replenishment of goods at retail and catering outlets. This study examined the establishment of a consolidation center servicing nearly 100 businesses that operated in an urban shopping mall in Southampton, United Kingdom. Through the review of numerous existing UK and international consolidation schemes and the examination of their operational characteristics, the study aimed to identify potential strengths, weaknesses, and risks that would impact the operation of the consolidation center. Various operational scenarios considering business take-up combinations, vehicle delivery mixes, fill rates, and back-load practices were examined to elucidate the potential transport and environmental effects of the consolidation scheme. To quantify and to verify these effects accurately, a multistage analysis framework, including data collection, map routing, emissions assessment, and scenario-building activities, was developed.
Freight-Trip Generation Model
Authors: Alho André Romano , Silva João de Abreu e
Published: February 2015

Freight demand models are important analytical tools for estimating demand per retail establishment, which is assumed as the total vehicle arrivals for loading and unloading purposes. Urban freight parking demand prediction is particularly useful in the context of transportation planning to determine, for example, infrastructure options and investment scale (e.g., freight parking). Achieving a balance between the predictive capabilities of the model and the feasibility of application is a challenge, as data regarding the population of retail establishments are frequently minimal. An establishment-based freight survey was used to collect data for 604 retail establishments in the city of Lisbon, Portugal. The relationship of candidate independent variables (e.g., store sales area and supply chain characteristics) versus the total number of weekly deliveries was investigated. Variables were chosen on the basis of suggested choices from the literature but also considering an exploratory perspective. Various sets of variables were modeled under ordinary least squares (OLS) linear regression and generalized linear model frameworks. Several tests were performed to assess model output quality. The analysis of the variables showed that those more commonly used in practical applications were not necessarily the best predictors of demand. The number of employees was consistently a better predictor than the area of the establishment or warehouse. Establishment category was the dominant variable. Supply-chain-related variables slightly improved the predictive capabilities of the models. OLS models showed better predictive capabilities but suffered from heteroskedasticity problems. Overall, the predictive capabilities of any of the models with the chosen methodology were lower than what is considered acceptable for a practical application.
Estimation of Pavement and Bridge Damage Costs Caused by Overweight Trucks
Authors: Dey Kakan C. , Chowdhury Mashrur , Pang Weichiang , Putman Bradley J. , Chen Linbo
Published: February 2015

This study adopted a damage quantification framework to estimate bridge and pavement damage caused by overweight trucks. The framework was applied to estimate unit overweight truck damage costs for the highway system maintained by the South Carolina Department of Transportation. The analysis revealed that pavement and bridge damage increased significantly when trucks were above legal weight limits. Tradeoffs between the most common overweight truck fee types were estimated to examine their relative efficacy. The study found the axle-based damage cost recovery fee for the additional per trip damage cost above the legal weight limit for an overweight truck loaded up to the maximum overweight limit. The fee varied between $14 and $165 per trip, depending on the type of overweight truck. The flat damage cost recovery fee was $55 per trip for all overweight trucks (about two times the current flat damage fee in South Carolina). The study revealed that ignoring the axle distribution in the flat damage cost recovery fee caused some truck types to pay more and others to pay less than the actual damage they imparted. In a weight-based damage cost recovery fee system, the per trip damage cost recovery fee varied between $2.77 and $36.57 per ton; in a weight-distance-based damage cost recovery fee system, the damage fee varied between 2 and 14 cents per ton-mile. A comparative analysis between damage cost recovery fee types, such as the one presented in this paper, will provide insight to decision makers for setting policies regarding overweight trucking fees.
Risk Assessment Framework for the Rail Transport of Hazardous Materials
Authors: Rahbar Mohadeseh , Bagheri Morteza
Published: February 2015

This research presented a unique opportunity to investigate an innovative train assembly process to mitigate the risks associated with the rail transport of hazardous materials (hazmat). This paper presented the formulation and solution of a risk assessment framework for moving hazmat by rail transport. The databases of FRA have been used to develop a risk minimization model for application that incorporates in-transit risk as well as rail yard train assembly cost and time constraints. The research problem was formulated as a mixed integer programming problem to be solved with the CPLEX software. The merits of the proposed model were illustrated through a case study highlighting the inadequacies of previous studies.
Assessing the Use of Navigation Systems in the Trucking Industry
Authors: Park Lisa , Fender Katie
Published: February 2015

There is currently a dearth of information and understanding on the role and the scope of the use of navigation systems in large trucks. Furthermore, the relationship between navigation system use in large trucks and safety benefits and consequences is unclear. Anecdotal evidence suggests that the use of navigation systems that are not specifically designed for the operation of large trucks has a detrimental impact on safety. Given the limited crash data that directly tied large truck crashes to navigation system usage, the American Transportation Research Institute (ATRI) explored alternative methodologies for investigating this important safety issue. The study developed two new approaches that (a) assessed navigation system usage in the industry and (b) attempted to identify the technical basis for navigation system failures and inadequacies from a truck operations perspective. ATRI collected and analyzed a large survey data sample on navigation system usage, including perceived utility and the associated benefits and risks for truck drivers who used navigation systems. Furthermore, the study identified the key priorities that navigation system providers should address to meet the needs of the trucking industry.
Evolution of Thermoviscoelastic Properties of Asphalt Mixtures with Oxidative Aging
Authors: Morian Nathan E. , Alavi Mohammad Zia , Hajj Elie Y. , Sebaaly Peter E.
Published: February 2015

The uniaxial thermal stress and strain test (UTSST) provides a fundamental approach to characterize the thermoviscoelastic properties of asphalt mixtures and permits the pragmatic evaluation of changes in the stiffness and overall behavior of mixtures as a function of oxidative aging. The UTSST modulus was computed in the temperature domain with a linear viscoelastic constitutive equation from the measured thermally induced stress and strain. Five distinct stages, here named thermoviscoelastic properties, are identified from the modulus as a function of temperature: viscous softening, viscous-glassy transition, glassy hardening, crack initiation, and fracture stages. Through consideration of the thermoviscoelastic properties, marked differences in the aging process were noted in the evaluation of two binders and two aggregate sources over a range of air void levels. Typically, decreases in the viscous response of the mixtures as well as corresponding increases in both the stiffness and brittle behavior are presented as a function of aging. The evaluated behavior of the mixtures also provides a clearer understanding of the significant influence the air void level, or mixture density, has on the binder oxidation and overall mixture performance. The evaluation method provides definitive measures to monitor the progression of multiple aspects of the response of asphalt mixtures to thermally induced loading.
Mode-Dependent Fracture Behavior of Asphalt Mixtures with Semicircular Bend Test
Authors: Im Soohyok , Ban Hoki , Kim Yong-Rak
Published: February 2015

Cracking in asphalt concrete pavements causes primary failure in the pavement structure. This cracking is considered one of the key issues to be addressed when paving materials are selected and sustainable pavement structures are designed. Given the diverse nature of traffic loads and pavement geometry, the asphalt mixture in the pavement is subjected to complex cracking behavior, such as mixed-mode fracture (i.e., the combination of an opening mode and a shearing mode of fracture). To date, most studies considered Mode 1 (opening) fractures only, because of technical challenges in testing and analysis. For a better understanding of asphalt fracture and more accurate design of pavement structure, mode-dependent fracture behavior needs to be characterized. This paper presents experimental efforts to characterize the mode-dependent fracture behavior of an asphalt mixture. Toward this end, semicircular bending (SCB) fracture tests were incorporated into the results of digital image correlation analysis for a fine aggregate matrix mixture subjected to a 10 mm/min loading rate and an intermediate temperature condition of 218C. To achieve different fracture modes (i.e., opening, sliding, and mixed), the geometric loading configurations of the SCB test were varied through the use of different initial notch inclination angles and different supporting spans. Test results were further analyzed to calculate fracture resistance. Observations from this study, though limited, imply that mixed-mode fracture characteristics exist and need to be considered in the structural design of asphalt pavements with which multiaxial cracking usually is associated.
Analytical Approach to Estimate the Rheological Properties of Asphalt Binders
Authors: Kabir Pooyan , Sakhaeifar Maryam S. , Newcomb David
Published: February 2015

The importance of rheological properties of bituminous materials has grown in the United States since the early 1990s, in line with the SHRP. These rheological properties are now commonly used in materials specifications and as input into the Mechanistic–Empirical Pavement Design Guide. Thus an approach that used predictive models to estimate accurately the rheological properties of bituminous materials would be useful for pavement design. In the study reported here, a modeling approach was proposed with a basis in fundamental viscoelastic principles. To establish the models, a large data set, which was obtained from multiple efforts from numerous locations across the United States, was used. The database consisted of measured modulus values from mixtures with modified and unmodified binders and mixtures that had various amounts of reclaimed asphalt pavement (RAP). As a result, two predictive models were developed to estimate the binder shear modulus and phase angle, given the desired physical and mechanical properties of asphalt mixtures. These models could be used for the wide range of temperatures (from 2108 to 54.48C) recommended in the AASHTO TP62-03 test protocol. The predictive capabilities of the newly developed models were evaluated with the use of different data sets with various types of mixtures. The findings of this study should lead to enhanced knowledge of the rheological properties of binders in RAP mixtures at intermediate and high temperatures without the need to extract the binders from the mixtures.
Balanced Asphalt Mixture Design through Specification Modification
Authors: Cooper Samuel B. , Mohammad Louay N. , Kabir Sharear , King William (Bill)
Published: February 2015

Traditional asphalt mixture design practices recognize the need for laboratory parameters, which relate to field performance throughout the life of the pavement. However, many design methodologies consider volumetric proportions and strength characteristics of the mixtures, which may not provide adequate insight into mixture performance. Laboratory testing that can ascertain an asphalt mixture's capability to resist common distresses is needed to complement current design methodologies. Distresses commonly associated with flexible pavement failure are fatigue cracking and permanent deformation (rutting). The Louisiana Department of Transportation and Development proposed specification modifications for 2013 to address the need for balanced mixtures (i.e., mechanistic laboratory evaluation to complement volumetric criteria). This paper presents Louisiana's experience with specification modifications to develop a balanced mixture as evaluated through the use of the Hamburg loaded wheel tester (HLWT) and semicircular bend (SCB) tests. Laboratory performance of 11 mixtures produced with the 2013 proposed specification modifications was compared with that of 40 mixtures produced under the 2006 specifications. Laboratory tests included HLWT and SCB to evaluate rutting and intermediate temperature cracking, respectively. The research showed that specification modifications did not adversely affect rutting or fatigue cracking resistance of the mixtures.
Effect of Long-Term Ambient Storage of Compacted Asphalt Mixtures on Laboratory-Measured Dynamic Modulus and Flow Number
Authors: Zeinali Alireza , Blankenship Phillip B. , Mahboub Kamyar C.
Published: February 2015

The asphalt mixture performance tester (AMPT) requires an exhaustive examination of the factors that influence the dynamic modulus and flow number test results. Interlaboratory research conducted in NCHRP Project 9–29, Phase 4, showed that dynamic modulus test results were highly dependent on the testing laboratory and the preparation of the AMPT specimens. Factors could include the oxidative aging and the steric hardening of asphalt in the mixture specimens during storage in a laboratory. The Asphalt Institute, Lexington, Kentucky, performed an experiment in cooperation with FHWA to evaluate the effect of ambient laboratory sample storage on the mechanical properties of asphalt mixture specimens. A half-factorial test matrix with triplicate specimens was developed to evaluate the effect of the following factors on the dynamic modulus and flow number of a laboratory standard mixture: storage duration (1 to 84 days), binder type (PG 64–22 and modified PG 76–22), storage of the specimen in a bag, and the cutting and coring of the specimen after compaction or immediately before it was tested. The results showed that storage duration could affect significantly the properties of the mixture with neat binder. The bagging of specimens did not seem to prevent their stiffening. However, storage of specimens uncut and uncored seemed to delay the stiffening phenomenon.
Development of a Failure Criterion for Asphalt Mixtures under Different Modes of Fatigue Loading
Authors: Sabouri Mohammadreza , Kim Y. Richard
Published: February 2015

In the study reported in this paper, the previously developed failure criterion for the viscoelastic continuum damage (VECD) model (referred to here as GOR, where O indicates old and GR is the rate of release of the pseudostrain energy) was applied to different modes of fatigue loading. The research team found that this criterion was mode-of-loading dependent and therefore considered insufficient. To mitigate this limitation, the GOR criterion was refined to become a new failure criterion, the GR method, which resolved the mode-of-load dependency issue. A characteristic relationship, which was found to exist in recycled asphalt pavement (RAP) and non-RAP mixtures between the rate of change of the averaged released pseudostrain energy during fatigue testing and the final fatigue life was derived in this study. This relationship is independent of mode of loading, strain amplitude, and temperature. The proposed failure criterion combines the advantages of the VECD model and this characteristic relationship, which originate from fundamental mixture properties. This proposed method can predict the fatigue life of asphalt concrete mixtures across different modes of loading, temperatures, and strain amplitudes within typical sample-to-sample variability that is observed in fatigue testing.
Multiscale Model for Asphalt Mixtures Subjected to Cracking and Viscoelastic Deformation
Authors: Teixeira Jamilla Emi Sudo Lutif , Kim Yong-Rak , Souza Flavio V. , Allen David H. , Little Dallas N.
Published: February 2015

The study reported in this paper presented a multiscale computational model, along with its validation and calibration, to predict the damage-dependent behavior of asphalt mixtures subjected to viscoelastic deformation and cracking. Asphalt mixture is a classic example of a multiphase composite that represents different lengths of scales. The understanding of the mechanical behavior of asphaltic materials has been a challenge to the pavement mechanics community because of the multiple complexities involved: heterogeneity, anisotropy, nonlinear inelasticity, and damage growth in multiple forms. To account for this issue in an accurate and efficient way, the study reported here presented a two-way linked multiscale computational modeling approach. The two-way linked multiscale model had its basis in continuum thermomechanics and was implemented with a finite element formulation. With the unique multiscale linking between scales and the use of the finite element technique, this model could take into account the effects of material heterogeneity, viscoelasticity, and anisotropic damage growth in small-scale mixtures on the overall performance of larger-scale structures. Along with the brief theoretical model formulation, the multiscale model was validated and calibrated through the comparison of the numerical, analytical, and experimental results of three-point bending beam tests of asphalt mixture samples that involved viscoelasticity, mixture heterogeneity, and cohesive zone fracture.
Florida's Return on Investment from Pavement Research and Development
Authors: Cunagin Wiley , Musselman James , Taylor Rhonda , Dietrich Bruce
Published: February 2015

The Florida Department of Transportation (DOT) recently implemented an innovative pavement management forecasting methodology, Florida's Analysis System for Targets (FAST). FAST uses bottom-up, section-level forecasts to develop regional and systemwide network pavement condition forecasts and evaluates the effects of alternative resurfacing funding scenarios. FAST is calibrated and validated annually with the latest section-level pavement condition data. This calibration provides the ability to assess the latest impacts of changes in pavement materials, processes, and construction methods and management. FAST allows the Florida DOT to leverage its pavement management database to address funding limitations by ensuring that transportation dollars are efficiently allocated. FAST enables engineers and managers to predict more accurately the condition of the highway system in a manner that allows managers to establish the level of funding necessary for projected resurfacing needs. For two decades, the Florida DOT has worked on an initiative to improve the durability of its pavement sections. Florida's experience with FAST has shown an excellent return on investment for research and development into pavement materials, processes, construction methods and management, and pavement management technology. As a result of the adoption of Superpave®, changes to open graded friction courses, changes to the Florida DOT construction quality control program, and a consistent resurfacing program, Florida's pavements are lasting longer, and Florida DOT management is able to reallocate resources. This tool has enabled the Florida DOT to reduce its resurfacing program and reallocate approximately $3 billion in nonessential resurfacing funds over the next 10 years to projects to increase capacity.
Considering Safety Impacts of Skid Resistance in Decision-Making Processes for Pavement Management
Authors: Wu Hui , Zhang Zhanmin , Long Kan , Murphy Michael R.
Published: February 2015

With the increase in material and labor costs and the decrease in purchasing power, the Texas Department of Transportation (DOT) is striving to maintain its roadways at the current level of conditions within a severely constrained budget. In particular, maintaining adequate pavement skid resistance has become a challenge for decision makers at various levels. The goal of this study was to develop a methodological procedure that could be used to establish the appropriate threshold values for skid resistance so that safety would not be compromised on Texas highways when there is a budget shortfall. The two primary issues were to be addressed: ( a) identification of the quantitative relationship between pavement skid resistance and crash rates and ( b) determination of threshold values for skid resistance and corresponding recommendations for maintenance decisions. A detailed methodological framework was proposed. Highway segments were categorized into homogenous groups of safety-related characteristics, except skid resistance. The quantitative relationship between crash risks and skid resistance was then established with the concept of the crash rate ratio. Three threshold values were determined to establish four decision categories of skid resistance values, with crash and skid resistance data collected from 2008 to 2011 on the highway system maintained by the Texas DOT. Corresponding recommendations on maintenance decisions were provided. The results show that the proposed methodological procedure can effectively capture the safety impacts of skid resistance at the network level and provide a useful tool for the Texas DOT to take safety into its maintenance decision-making processes.
Probabilistic Life-Cycle Assessment as Network-Level Evaluation Tool for Use and Maintenance Phases of Pavements
Authors: Bryce James , Katicha Samer , Flintsch Gerardo , Sivaneswaran Nadarajah , Santos João
Published: February 2015

Agencies that manage pavement networks have a role in mitigating the factors affecting global climate change by managing their networks in such a way that these factors are minimized. Although much research is still required to quantify the climate change impact of many variables relating to pavements, the impact of pavement condition on vehicle fuel consumption has been clearly demonstrated in several research projects. In the light of extensive research that shows pavement characteristics as having a significant impact on vehicle fuel consumption, it can be shown that maintaining a network of pavements to minimize roughness can limit the energy consumption of vehicles traveling along the pavement network. The objective of this study was to demonstrate a method by which transportation agencies could measure the impact of their management decisions on reducing the energy consumption of their networks. The use of a life-cycle assessment (LCA) to quantify energy consumption probabilistically for a given set of expected maintenance actions defined at the network level is demonstrated. This study shows how the results of the LCA can be used to evaluate the energy consumption attributed to the pavement network over a defined time frame.