bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Live Crude Oil Composition On Optimal Salinity of A Surfactant Formulation
Authors: Marliere Claire , Creton Benoit , Oukhemanou Fanny , Wartenberg Nicolas , Courtaud Tiphaine , Féjean Christophe , Betoulle Stéphane , Defiolle Denis , Mougin Pascal
Published: March 2016

The objective of surfactant formulation design is to achieve ultra-low interfacial tension (IFT) with the oil in place in reservoir conditions. Several parameters have to be investigated, the presence of dissolved gas in crude oil can greatly impact the surfactant/brine/crude oil microemulsion phase behavior and omitting it may degrade the formulation efficiency. We propose an experimental investigation of optimal salinity evolution as a function of live oil compositions and conditions varying the pressure independently to the gas to oil ratio (GOR), i.e. the amount of gas dissolved in crude oil.

A specific High Pressure - High Temperature (HPHT) sapphire cell with a mobile piston is used to separately study the impact on the formulation optimal salinity of: (i) the GOR by adding different amounts of C1 to C5 n-alkanes at the corresponding saturation pressure; and (ii) the pressure cell – up to 500 bar – by varying the cell volume (without changing the live crude oil composition). Experiments were performed at 40°C and at the saturation pressure or above.

Using the HPHT sapphire cell we show that GOR variations up to 135 Sm3/m3 induce important modifications of the {surfactant/brine/oil} microemulsion phase behavior. In the case of the studied fluid, experimental data indicate that the optimal salinity of the {brine/surfactant/oil system} decreases when increasing the amount of gas dissolved in the live crude oil. As a consequence, the equivalent alkane carbon number (EACN) of the live crude oil strongly depends on the gas to oil ratio. We demonstrate hereafter that the cell pressure– for a fixed composition (i.e. fixed GOR) –impacts neither the formation nor the stability of the microemulsion. Furthermore, preliminary results suggest that the composition of the dissolved gas has a slight effect on the microemulsion phase behavior.

In this work, using a specific HPHT sapphire cell, we are able to dissociate the impact of the amount of added gas from the impact of the cell pressure and to consider pressures up to 500 bar. Whereas the pressure alone has a negligible influence on the surfactant/brine/oil microemulsion phase behavior, the dissolution of gases in crude oil leads to a decrease of the optimal salinity and a variation of live crude oil EACN.
The Application of Cyclic Steam Stimulation in Heavy Oil Reservoir with a High Water Cut
Authors: Abdullah Al Shibli , Suleiman Al Hinai , Abdesslam Belghache , Sumaiya Al Habsi
Published: March 2016

"A" West field is a heavy oil field (17–25 deg API), discovered in 1972 in the South of Oman, with a 200 m thick oil column in Haradh formation. The field development started in 1984 by cold production with vertical and horizontal wells. In 2007, the steam drive concept through 10 acre inverted 7-spot patterns was selected for the full field development. Being part of the concept, two Cyclic Steam Stimulation "CSS" campaigns were executed between 2011 and 2014 to stimulate both the wells and the reservoir using a mobile steaming unit. Throughout the two campaigns, a number of optimizations have been implemented including: the deployment of Vacuum Insulated Tubing "VIT", the extension of the perforated intervals, the adjustment of the injection and production cycle durations and resources management.

The deployment of the 1000 m VIT during the steam injection phase confirmed the predicted oil gain, resulting from a reduction in wellbore heat losses. Along with CSS, a re-perforation campaign has been conducted on wells with low productivity index "PI" to maximize their gross offtake. After steam stimulating the re-perforated wells, it has been observed that higher oil to steam ratio "OSR" is obtained for thicker oil column exposed to steam. In addition, for highly depleted zones in the reservoir, it has been found that producing at the maximum possible rate and right after the end of the soaking period, leads to a better OSR. CSS proved also to have improved the steam conformance within the targeted pattern.

Based on the promising results from the CSS jobs a decision was made to build a permanent CSS capability in all future wells in "A" West. This will also enable a proper management of the lateral steam conformance.
Results & Interpretation of a High Viscous Polymer Injection Test in a South Oman Heavy Oil Field
Authors: Rubalcava D. , Al-Azri N.
Published: March 2016

This paper discusses the design and results of a polymer test in a field containing heavy oil. The field is located in the south of Oman and contains significant in place volumes of viscous oil (700cp) in sub Darcy reservoir. Due to unfavorable oil-water mobility ratio, the ongoing water injection will still leave significant volumes of stranded oil post water injection.

A "Paradigm Shift" from energy intensive thermal processes, high viscous polymer flood is currently being evaluated to target and recover stranded high viscosity oil. If successful not only would the oil recovery from the field be significantly increased but a reproducible process would be available to target other high viscosity oil reservoirs in Oman.

A single well injection test was conducted in 2014 representing the first foray into high viscous polymer flooding for the field. The driver for conducting the test was to de-risk polymer injection as a pre-courser to a full field expansion. To that end the following KPI's were identified. Matrix injection – can economical rates at design pressures be achievedLow salinity – clay swelling and subsequent loss of injectivityAlternate higher molecular weight polymer's – can injectivity be maintained or is polymer pluggingConformance – Applicability to full field / is conformance control requiredFracture pressure – Defining injection envelope for full filed expansion

The test comprised of a converted horizontal producer that was retrofitted with Disturbed Temperature and Acoustics (DTS & DAS) fiber optics. Modular polymer facilities capable of injecting high viscous polymer slugs at high rates were utilized; additionally a modular low salinity process was also used to drop the injected water and polymer salinity to 500ppm TDS.

The following have been identified as key learning's from the test: A lack of conformance was identified through DTS and DAS evaluation during initial water injection, prior to the injection of any polymerA loss of injectivity was also observed over a period of the test. This affected subsequent polymer and water injection periods.The behavior of in-situ polymer highlighted possible unexpected phenomena, particularly the effect on water injection post polymer injection.Low salinity, 500ppm TDS, water was injected with and without polymer with no adverse affect on injectivity.Additionally, the higher molecular weight polymer also was successfully injected.
Nanoparticles as Foam Stabilizer for Steam-Foam Process
Authors: Khajehpour Maryam , Etminan S. Reza , Goldman Jon , Wassmuth Fred
Published: March 2016

Steam foams have been considered as effective additives for unconventional oil recovery processes. Conventionally for steam-foam applications, chemical additives are injected with steam. However, this operation has serious drawbacks owing to poor thermal stability of additives and high volume of additives loss, due to adsorption to rocks surface. To overcome these limitations, nanoparticles can be used as novel additives to improve generation and stabilization of the foams for steam-foam applications.

In this study, silica nanoparticles in synergy with surfactants have been used as steam additives. Dynamic light scattering (DLS), foam height test using N2 at reservoir conditions, and thermal stability analysis were designed to measure nanoparticles size distribution in brine, foam-ability and thermal stability of the additive solutions, respectively. Subsequently, core-flooding tests were performed to evaluate the synergistic effect of nanoparticles and surfactants on the foam quality and oil recovery. We observe an optimum ratio of nanoparticle and surfactant that yields the best foam generation performance (maximum foam height). Herein, surface treated silica nanoparticles have been tested with two of our candidate surfactants. The nanoparticles alone generate small amount of foam, while each surfactant generates a small to moderate amount of foam. Synergy is demonstrated by the system which contains 0.1 wt% nanoparticles (the optmum concentration) and 0.5 wt% of surfactant solution at neutral pH (~7), as it leads to about 67% and 50% greater foam height respectively for Surfactants A and B than observed in tests with surfactants only. Core-floods with co-injected steam and water containing nanoparticles and surfactant confirm the synergy, exhibiting significant improvement in mobility factor reduction (MRF) and steam control, compared to co-injection of steam and water containing only surfactant.
Design of CO2 Injection Pilot in Offshore Middle East Carbonate Reservoir
Authors: Kumar Jitendra , Draoui Elyes , Takahashi Satoru
Published: March 2016

Carbon dioxide (CO2) injection is considered to be a viable option for enhanced oil recovery (EOR) and has already been implemented commercially for more than 40 years. However, the applications are limited to onshore and offshore application for EOR activities have not yet been implemented. This paper presents the subsurface evaluation using laboratory experiments (PVT and corefloods) and compositional modeling, the design and surveillance program of a CO2 pilot project planned in a carbonate reservoir located offshore Abu Dhabi.

PVT and coreflood experiments demonstrate the local displacement efficiency of CO2 in tertiary mode due to gas-oil miscibility, swelling of oil and reduction in oil viscosity. The screening study performed using a tuned equation of state (EOS) predicts significant additional recovery in a previously waterflooded area. A pilot is planned in one of the reservoirs of the field, which has 40 years of peripheral seawater injection history. The pilot design is influenced by existing peripheral pressure gradient, and is located down-dip in the field that covers approximately 80 acres. The pilot location is selected based on geology, reservoir quality, maturity to waterflood and surface facility constraints. A comprehensive reservoir surveillance plan, including one to two observers well, is developed to monitor pilot performance. The planned pilot will reduce uncertainties and risk associated with CO2 injection and address bottleneck uncertainties in an offshore environment before large-scale application.

The first offshore CO2 injection pilot is designed for implementation in a tertiary mode in a giant carbonate field, which is still under secondary recovery production, to minimize interaction with current production and impact on surface facility. The paper also presents the possible mitigation for various challenges identified like asphaltene, scaling, corrosion, impact on existing carbon steel well completion, etc. associated with CO2 injection.

The methodology and technical analysis used to evaluate and design the CO2 pilot are applicable to other potential fields in the region.
Effect of Steam Injection Interruption on SAGD Performance
Authors: Ali S. M.
Published: March 2016

Steam-Assisted Gravity Drainage (SAGD) is a complex process governed strongly by geology and steam injection conditions, among other parameters under normal circumstances. At times it may become necessary to shut down a project temporarily for a variety of reasons, e.g. low bitumen price, high fuel cost, etc. Later, when steam injection is re-started, the performance may be considerably inferior to that for continuous operation. It is the intent of this work to examine the effect of steam stoppage for a certain period on SAGD performance, for a selected set of conditions. Also presented is an analytical approach.

Two different geological models were employed in SAGD simulations - one was that of an actual reservoir, the other one consisted of a homogeneous reservoir. Steam injection conditions were similar for the two cases. The principal variables were steam injection time, the point of shut-off and the time of shut-off, and the steam injection rate. The simulator utilized a thermal compositional approach, treating the fluids as a three-component system.

It was found that for a given steam injection time, the stoppage time (after which steam injection is restarted) lowered SAGD performance, as measured by oil recovery and steam-oil ratio, for the same volume of steam injected. The performance was lowered to a greater degree in the case if a real reservoir than for the homogeneous case. Steam injection rate reduction further adversely impacted performance. Another variable is the point of steam injection stoppage. An analytical model was developed to examine steam condensation during the shut-off period.

The results of this work provide insight into the complex behaviour of SAGD when the process is interrupted. It provides guidelines on the interruption point and the length of interruption for minimizing the adverse effects on performance.
Experimental and Theoretical Study on Corrosion Inhibition of Mild steel in 20 % Formic Acid Solution Using Schiff Base-Based Cationic Gemini Surfactant
Authors: Mobin Mohammad , Masroor Sheerin
Published: March 2016

The paper investigates the adsorption and corrosion inhibition behavior of Schiff base-based cationic gemini surfactant bis-[p-(N,N,N-dodecyldimethylammonium bromide) benzylidene]thiourea, designated as (12-S-12) on mild steel in 20 % formic acid solution in the temperature range of 30 – 60 °C. The synthesized inhibitor was characterized using nuclear magnetic resonance spectroscopy (NMR). The adsorption and corrosion inhibition mechanism of the inhibitor was elaborated using weight loss measurements, solvent analysis of iron ions, potentiodynamic polarization measurements, electrochemical impedance measurements, measurement of thermodynamic/kinetic parameters and quantum chemical calculations. The surface morphology of the corroded mild steel specimen was evaluated using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). The inhibition efficiency of the compound was found to vary with the inhibitor concentration and temperature. The inhibitor was found to be a mixed type inhibitor. Adsorption process on mild steel surface followed Langmuir's model adsorption isotherm.
Dipeptide Glycyl-Glycine (Gly-Gly)–Ninhydrin Reaction: Effect of Alkanediyl-α,ω-bis(dimethylcetylammonium bromide) (16-s-16, s = 4, 5, 6) Gemini Surfactants on the Reaction Rate
Authors: Kumar Dileep , Neo Kian-Eang , Rub Malik Abdul
Published: March 2016

The present work concerns with the effect of alkanediyl-α,ω-bis(dimethylcetylammonium bromide) gemini surfactants on the reaction rate of ninhydrin with glycyl-glycine. The spectra showed peaks at 400 nm and 570 nm in aqueous and aqueous–micellar media indicating the formation of the same product. Under pseudo-first-order conditions of excess ninhydrin, the reaction followed an irreversible first- and fractional-order kinetics with respect to [Gly-Gly] and [ninhydrin]. Also, the rate constants (kψ) increases and leveling-off regions are found with [geminis] (akin to conventional cetyltrimethylammonium bromide, CTAB), a third-region of increasing kψ is observed at higher [geminis]. The kinetic data in gemini micellar medium have been examined with the pseudo-phase model.
Steady state and transient analyses of MNSR reactor using RELAP5 code
Authors: Zarifi E. , Tashakor S. , Khorsandi J.
Published: March 2016

Developing a reliable thermal-hydraulic model of a nuclear reactor is an essential process in the steady state and transient analyses. This paper provides the results of best estimate calculation carried out with reference to Iranian Miniature Neutron Source Reactor (MNSR) using the RELAP5 code. Applying the qualified nodalization and the cross-flow effects are some of the advantages in the present model. Here, various transients including step and ramp reactivity insertions were inspected for safety analysis. The obtained results from the code showed a reasonable agreement with the MNSR Safety Analysis Report (SAR) and existing experimental and reference data.
Calculation of PDS-XADS core closed-loop transfer function by using feedback with the lumped-model
Authors: Moghassem A. , Pazirandeh A. , Abbaspour A.
Published: March 2016

In this paper, the PDS-XADS LBE-cooled core open-loop transfer function was calculated by considering the source importance in point-kinetic equations. For this purpose, the overall-feedback transfer function was calculated considering the lumped-model for 14-steps of subcritical levels. Following effects were considered in three steps: 1. Doppler broadening, fuel expansion, coolant density and structure expansion, 2. Delayed-reactivity and void-worth inserted to prior step, 3. Severe-accident condition, inserted to prior steps. The linear stability analysis was modeled by using the Bode diagrams, Nyquist stability criterion and Nichols chart in MATLAB for each subcritical level and six groups of delayed neutrons. For optimized subcritical level determination, a conservative severe accident was considered. According to calculation results and analysis, the PDS-XADS core is stable and in optimized subcritical level, has the higher safety margin. The results are in good agreement with SIMMER-III code and main neutronic results. The optimized subcritical level by using the lumped-model is 0.97687.
Validation of RELAP5 model of experimental test rig simulating the natural convection in MTR research reactors
Authors: Khedr A. , Abdel-Latif S. H. , Abdel-Hadi E. A. , D’Auria F.
Published: March 2016

In an attempt to understand the built-up of natural circulation in MTR pool type upward flow research reactors after loss of power, an experimental test rig was built to simulate the loop of natural circulation in MTR reactors. The test rig consisting of two vertically oriented branches, in one of them the core is simulated by two rectangular, electrically heated, parallel channels. The other branch simulates the part of the return pipe that participates in the development of core natural circulation. In the first phase of the work, many experimental runs at different conditions of channel's power and branch's initial temperatures are performed. The channel's coolant and surface temperatures were measured. The measurements and their interpretation were published by the first three authors. In the present work the thermal hydraulic behavior of the test rig is complemented by theoretical analysis using RELAP5 Mod 3.3 system code. The analysis consisting of two parts; in the first part RELAP5 model is validated against the measured values and in the second part some of the other not measured hydraulic parameters are predicted and analyzed. The test rig is typically nodalized and an input dick is prepared. In spite of the low pressure of the test rig, the results show that RELAP5 qualitatively predicts the thermal hydraulic behaviour and the accompanied phenomenon of flow inversion of such facilities. Quantitatively, there is a difference between the predicted and measured values especially the channel's surface temperature. This difference may be return to the uncertainties in initial conditions of experimental runs, the position of the thermocouples which buried inside the heat structure, and the heat transfer package in RELAP5.
Assessment of pin-by-pin fission rate distribution within MOX/UO2 fuel assembly using MCNPX code
Authors: Louis H. K. , Amin E.
Published: March 2016

The aim of the present paper is to assess the calculations of pin-by-pin group integrated fission rates within MOX/UO2 Fuel assemblies using the Monte Carlo code MCNPX2.7c with two sets of the available latest nuclear data libraries used for calculating MOX-fueled systems. The data that are used in this paper are based on the benchmark by the NEA Nuclear Science Committee (NSC). The k
∞
and absorption/fission reaction rates per isotope, keff and pin-by-pin group integrated fission rates on 1/8 fraction of the geometry are determined. To assess the overall pin-by-pin fission rate distribution, the collective per cent error measures were investigated. The results of AVG, MRE and RMS error measures were less than 1 % error. The present results are compared with other participants using other Monte Carlo codes and with CEA results that were taken in the benchmark as reference. The results with ENDF/B-VI.6 are close to the results received by MVP (JENDL3.2) and SCALE 4.2 (JEF2.2). The results with ENDF/BVII.1 give higher values of k∞ reflecting the changes in the newer evaluations. In almost all results presented here, the MCNP calculated results with ENDF/B VII.1 should be considered more than those obtained by using other Monte Carlo codes and nuclear data libraries. The present calculations may be consider a reference for evaluating the numerical schemes in production code systems, as well as the global performance including cross-section data reduction methods as the calculations used continuous energy and no geometrical approximations.
Calculation of nuclear reactivity using the generalised Adams-Bashforth-Moulton predictor corrector method
Authors: Suescún-Díaz D. , Narváez-Paredes M. , Lozano-Parada J. H.
Published: March 2016

In this paper, the generalisation of the 4th-order Adams-Bashforth-Moulton predictor-corrector method is proposed to numerically solve the point kinetic equations of the nuclear reactivity calculations without using the nuclear power history. Due to the nature of the point kinetic equations, different predictor modifiers are used in order improve the precision of the approximations obtained. The results obtained with the prediction formulas and generalised corrections improve the precision when compared with previous methods and are valid for various forms of nuclear power and different time steps.
A methodology for in-situ micro-compression testing of fiber composites
Authors: Lu Y. Charles , Tandon Gyaneshwar P. , Wheeler Robert
Published: March 2016

A methodology for in-situ micro-compression testing of fiber composites has been developed. The tests were performed on carbon fiber reinforced bismaleimide matrix unidirectional composite, IM7/BMI 5250-4. Micro-size specimens were prepared from the bulk composite plaque through a two-step micro-fabrication process and then tested by using a micro-mechanical testing device placed inside the scanning electron microscope chamber. Results show that the fundamental properties (modulus and strength) of the fiber composites obtained from micro-size specimens are consistent with the theoretical estimations and significantly higher than those from macro-size specimens, which may have revealed the presence of size-scale effects in composite materials. The in-situ testing shows that the overall failure mode of the present composite is caused by “micro-buckling” of fibers in shear-mode. High shear strains are seen to occur at the fiber–matrix interfaces, which lead to the micro-cracking and ultimate failure of the composite.
Relaxation and diffusion barriers at step edges of Cu, Ag and Au homo- and heterogeneous systems: Case of (100) facet
Authors: Benlattar Mourad , Elkoraychy Elyakout , Sbiaai Khalid , Mazroui M'hammed , Boughaleb Yahia , Gounaya Hicham
Published: March 2016

Using molecular dynamics simulations based on the embedded atom method, we present the calculations of adsorption and activation energies for the diffusion of adatoms (Cu, Ag or Au) on Cu (100), Ag (100) or Au (100) surfaces with steps. We have also examined the relaxation trends and bond lengths of the adatoms for both fourfold and bridge sites. We note that the vertical distance of the adatom relaxation to the first nearest neighbors is the largest (1.56 %) for Ag on Cu (100) and the shortest (–14.58 %) for Cu on Au (100) as compared to other systems. On the other hand, for Cu on the Au (100) system, we find the adatom barrier for hopping along the step edges to be 0.44 eV, which is the highest for this process among the systems studied here, but the lowest barrier is found for Ag on Cu (100) compared to other systems and costs only 0.20 eV. Attention has also been focused on the evaluations of the adsorption and activation energies for the nine systems in the presence of step edges. The diffusion barriers over and along step edges are interpreted in terms of the cohesive energies of the adatoms and substrates. Moreover, these results can offer some basic rules for forecasting precise atomic surface morphologies in homo- and hetero-epitaxial growth.
Dry wear behavior of cooling-slope-cast hypoeutectic aluminum alloy
Authors: Van Thuong Nguyen , Zuhailawati Hussain , Anasyida Abu Seman , Huy Tran Duc , Dhindaw Brij Kumar
Published: March 2016

This study investigated the effect of use of a cooling slope on the microstructure, hardness and wear behavior of Al-7Si-Mg alloy. The Al-7Si-Mg alloy was cast with and without a cooling slope at a pouring temperature of 640 °C. Examination with optical and electron microscopes showed that the microstructure of cast samples using the cooling slope comprised fine and globular primary α-Al phase with homogeneous distribution of eutectic phase, while conventionally cast samples featured coarse and dendritic primary α-Al phase. The wear resistance of the cast sample was significantly better with cooling slope casting. The wear mechanism was found to be a combination of adhesion, delamination, oxidation and abrasive wear for both cooling slope- and conventionally cast samples. The wear mechanisms of cast samples both with and without cooling slope are similar and follow Archard's law. The cooling slope-cast samples with fine and globular α-Al phase, high hardness and low specific wear rate (K′) showed the highest wear resistance of 10.08 × 10−5 mm3 N−1 m−1.
Group and Single Pedestrian Behavior in Crowd Dynamics
Authors: Do Truong , Haghani Milad , Sarvi Majid
Published: March 2016

An analytical study was proposed in this paper to explore various behavioral aspects of group and single pedestrians. The results were obtained from reviewing the literature and studying primary data. Data collected from field surveys, direct observations, and video recordings were analyzed to produce the following findings. For crowds with densities between 0.4 and 0.8 persons per square meter, individuals walked faster than groups, on average. There was also significant evidence to suggest that individuals were likely to have more trajectory changes than groups. As the crowd density got higher, the likelihood of pedestrians splitting from groups of two decreased. With higher crowd densities, the rate at which split members came back to the group decreased. More individual pedestrians chose spacious stairs; groups of two were more likely to go for escalators.
Civil Integrated Management for Highway Infrastructure: Case Studies and Lessons Learned
Authors: Sankaran Bharathwaj , O’Brien William J. , Goodrum Paul M. , Khwaja Nabeel , Leite Fernanda L. , Johnson Joshua
Published: March 2016

The use of information modeling and digital data for highway projects has seen a considerable surge over the past decade. These tools have enhanced the predictability and performance of several tasks in the project delivery process. This study explores the implementation of civil integrated management (CIM) practices in four case studies and documents the lessons learned to enhance CIM inclusion in project delivery processes. CIM encompasses the system of interdependent technologies and practices that facilitate collection, management, and utilization of digital information for project delivery and asset management processes. CIM is an emerging practice, and studies concerning integration of CIM technologies with project life cycle are limited. Through case studies of four highway projects, this study emphasizes the standards and processes that played a vital role in utilizing CIM technologies for contract documentation, design coordination, construction automation, and project management. The two small-scale projects investigated as part of this study demonstrate that pilot initiatives could be successfully carried out to harvest best practices in overcoming contract and legal challenges while embracing new technologies in agencies’ workflow. The two large-scale projects indicate that with the owner’s participation and expertise, the role of CIM technologies can be further enhanced toward performing project management functions. The lessons learned from the case studies are organized to provide a synthesis of process and organizational considerations that would enhance the agencywide adoption of CIM technologies.
Comparing Construction Manager–General Contractor and Federal Early Contractor Involvement Project Delivery Methods
Authors: Gransberg Douglas D.
Published: March 2016

Past studies of the construction manager–general contractor (CMGC) project delivery method have focused on its use by state and municipal departments of transportation. The literature also includes the approach to the CMGC delivery method based on Federal Acquisition Regulation (FAR) termed early contractor involvement (ECI), which the literature classifies as merely a different term for CMGC. The desire to use CMGC project delivery by the Federal Lands Highway Divisions stimulated a deeper study of the restrictions placed on federal agencies by the FAR and found that although CMGC and ECI project delivery are indeed similar, they are not identical. The findings of that study are reported. A comparative analysis of the two project delivery models is presented, and it is found that ECI delivery is substantially different from CMGC delivery because of FAR-based limitations on preconstruction services and pricing methodology. It is concluded that the use of an incentive–disincentive scheme and the bidding of a proposed profit margin enhance competition during the ECI contractor selection process. The results of this study can be used outside the federal sector by state and local transportation agencies to furnish an alternative to the CMGC delivery method in those areas in which industry opposition is the primary barrier to implementing the CMGC delivery method.
Large-Scale Deployment of Performance-Related Specifications for Jointed Plain Concrete Pavement
Authors: Gillen Steven , Vavrik William , Wilson Thomas P.
Published: March 2016

For the 2015 construction season, the Illinois Tollway management awarded nine contracts that include performance-related specifications for jointed plain concrete pavement (JPCP) to be placed along the I-90 corridor between Chicago and Elgin, Illinois. Overall, the nine contracts have a total value of over $550 million, with more than $50 million of the JPCP subject to performance-related specification incentives and disincentives. Deployment of this volume of performance-related paving has required the development of specifications and special provisions as well as a more focused approach to monitoring the testing of the concrete materials as paving is proceeding. Enhanced communication and documentation processes have also been created to ensure that the flow of materials test data and the impacts that the data are having on the calculation of incentives and disincentives can be transmitted to the contractors as quickly as possible. The communication processes include contractor responses and feedback to the materials test data and the financial impact resulting from the test data, with electronic documentation of communication between the testing labs, the tollway and its quality contractors, and the paving contractors. This study documents the development of the current performance-related JPCP specifications, including the challenges encountered in trying to establish performance-related specifications for such a large number of concurrent projects, the solutions employed to overcome those challenges, and the impact on both the tollway and the contractors as a result of the deployment of performance-related JPCP.
Evaluation of Additional Laboratory Tests for Design of Full-Depth Reclamation Mixtures Using Foamed Bitumen
Authors: González Álvaro , Paniagua Fernando , Thenoux Guillermo , López Carlos
Published: March 2016

The mix proportion design methods for full-depth reclamation mixtures using foamed bitumen normally fix a constant active filler content, and an indirect tensile strength (ITS) test is used to determine the optimum bitumen content. However, it has been reported in the literature that for some materials the ITS test is not sufficiently sensitive to bitumen content. This lack of sensitivity is a problem for the practitioner engineer who has to validate the bitumen content adopted in the mixture design. The main objective of this work is to examine the sensitivity to bitumen content of additional laboratory tests that could complement current design methods based on ITS. The mixtures used in the study were prepared by using three recycled blends of reclaimed asphalt pavement and aggregate that were mixed with bitumen foam contents of 1.25%, 2.5%, and 3.75%. Test results confirmed the low sensitivity of the ITS test, and it was found that the indirect tensile fatigue (ITF) test was the most sensitive among all tests. To explain the higher sensitivity of the ITF test compared with the ITS test, a stress–strain diagram and a simple unidirectional mechanical model were developed. In addition, an S-N fatigue diagram was used to illustrate that at a larger number of load cycles, the effect of the foamed bitumen content is clear, as shown in the experimental work. Overall, the laboratory program and material behavior analysis indicate that when the ITS test does not provide conclusive results, the laboratory program should be complemented with ITF tests to determine the optimum foamed bitumen content with more reliability.
Comparing Life-Cycle Cost Analysis of Full-Depth Reclamation Versus Traditional Pavement Maintenance and Rehabilitation Strategies:
Authors: Braham Andrew
Published: March 2016

Arkansas has highways in the central and southern portions of the state that have experienced unanticipated high traffic levels because of logging and drilling for natural gas. These highways are being exposed to traffic much higher than their design values. In these situations, traditional maintenance and rehabilitation strategies can often be either ineffective or too expensive. Therefore, full-depth reclamation is being explored as a possible alternative for asphalt concrete pavements in Arkansas. This research compared chip seals, overlays, mill and fill, and complete reconstruction with three full-depth reclamation technologies from the economic and structural perspectives: asphalt emulsion, asphalt foam, and portland cement. With life-cycle cost analysis techniques, it was found that the user costs ranged from one-fourth to five times the agency costs. Although full-depth reclamation is economically competitive with traditional strategies, it was not as competitive on roadways with higher ratios of bounded versus unbounded material. Finally, traffic capacity increased significantly at reclaiming depths greater than 10 in. Overall, this research supports full-depth reclamation as a viable economic alternative to chip seals, overlays, mill and fill, and complete reconstruction given the proper conditions of traffic and bound pavement depth.
Verification of Time–Temperature Superposition Principle for Shear Bond Failure of Interlayers in Asphalt Pavements
Authors: Cho Seong-Hwan , Kim Y. Richard
Published: March 2016

Asphalt pavement structures are composed of different asphalt concrete layers with surface layers that are bonded together with a tack coat. Thus, interlayer bonding between pavement layers is a key factor that affects the performance of any pavement structure. However, relatively little attention has been given to the characterization and modeling of interlayer bonding or to associated test methods that can be used in the laboratory to evaluate the bond strength between asphalt concrete layers. This paper presents a test method for evaluating interface bonding between asphalt concrete layers in shear mode. Moreover, the time–temperature superposition (t-TS) principle with growing damage in shear failure mode is examined to characterize the shear bond strength of asphalt concrete pavements for a wide range of temperatures. The subsequent validation of the t-TS principle allows the shear bond strength between asphalt layers at various temperatures and loading rates to be determined with only three or four shear tests. Comparison of the shear stress values calculated from a mechanistic pavement analysis program for a critical condition with the shear strength values at the condition determined from the prediction model developed in this study can provide the foundation for a mechanistic design to prevent shear bond failure between asphalt layers.
Enhancing Rutting Prediction of the Mechanistic–Empirical Pavement Design Guide by Using Data from a Field Test Section in Oklahoma
Authors: Hossain Nur , Singh Dharamveer , Zaman Musharraf
Published: March 2016

An instrumented test section was constructed on Interstate 35 near Purcell, Oklahoma. Mechanistic–Empirical Pavement Design Guide (MEPDG) input parameters for traffic, climate, and materials were developed from the data for this test section. The site included a weigh-in-motion station and lateral positioning sensors to obtain input parameters for traffic. In addition, laboratory tests—dynamic modulus, resilient modulus, dynamic shear rheometer, and other pertinent tests—were conducted with materials from the test section. Rut measurements were taken at the site on a quarterly basis for 5 years. Differences in traffic input parameters between Level 3 and Level 1 were identified and are discussed in this paper. At first, significant differences were observed between measured and predicted ruts. For example, the average error between the MEPDG-predicted rut and the measured rut was approximately 18% when default input parameters were used. Although the average error was reduced to approximately 10% when the Level 1 inputs were used, differences between the predicted and measured ruts still existed, which necessitated the development of local calibration factors. After the calibration process, the average error was reduced to less than 5%. The optimized calibration coefficients were found to be β r1 = 2, β r2 = 1, and β r3 = 0.9 for asphalt layers; βGB = 1 for an aggregate base layer; and βSG = 0.5 for a natural subgrade layer. There is a need for the development of a database and local calibration of models for successful implementation of the MEPDG in Oklahoma.
Whatever Singularity, Negative Community, and Literature (Perhaps)
Authors: Tremblay Thierry
Published: March 2016

Evoking the eighteenth-century sources of the idea of ‘negative community’, this article refers to Georges Bataille's attempt to create a new community, or secret society: Acéphale. For his part, and writing after Maurice Blanchot's The Unavowable Community and Jean-Luc Nancy's The Inoperative Community, Giorgio Agamben articulates the idea of a ‘coming community’, which he calls the ‘whatever singularity’. Doing so in the context of these influences, this article considers, particularly in its conclusion, the question of literature in the specific temporality brought by the potentiality of the negative.
The Time of Indifference: Mandelstam's Age, Badiou's Event, and Agamben's Contemporary
Authors: Watkin William
Published: March 2016

There has been little direct discussion between perhaps the two leading philosophers of our age: Alain Badiou and Giorgio Agamben. Yet both men have written about the same poem by Osip Mandelstam, ‘The Age’, around the topic of time. Significantly, Agamben's response, written after Badiou's, is a subtle and damning critique of Badiou's conceptualisation of time, in particular extended across the categories of the modern, the contemporary, and the now or the event – although it never actually mentions Badiou by name. In this paper the lens of the central role of indifference in the work of both is used to present alternating and competing views as to the nature of modern, contemporary, and ‘now’ time. Specifically, a contrast is drawn between Badiou's use of indifference as both quality-neutral and absolutely non-relational, and Agamben's application of the indifferent suspension of the temporal signature as such. The paper concludes that while Badiou uses temporal indifference to question and problematise the idea of modern time as ‘now’, through a theory of the event, Agamben appears to go further. Rather than analyse the nature of modern time, the contemporary and the now through his reading of Mandelstam, Agamben uses Mandelstam's poem to suspend the Western conception of time as a line composed of points in its entirety.
A Pretreatment Method for the Velocity of DVL Based on the Motion Constraint for the Integrated SINS/DVL
Authors: Zhao Li-Ye , Liu Xian-Jun , Wang Lei , Zhu Yan-Hua , Liu Xi-Xiang
Published: March 2016

It is difficult for autonomous underwater vehicles (AUVs) to obtain accurate aided position information in many locations because of underwater conditions. The velocity accuracy from the Doppler velocity log (DVL) is a key element in deciding the AUV position accuracy when the integration system of Strapdown Inertial Navigation System/DVL/Magnetic Compass/Press Sensor (SINS/DVL/MCP/PS) is adopted. However, random noise and sudden noise in DVL caused by sound scattering, fishing populations, and seafloor gullies introduce level attitude errors and accumulate as position error. To restrain random noise, a velocity tracing method is designed based on the constant velocity model and the assumption of slow motion of AUV. To address sudden noise, a fault diagnosis method based on the χ 2 rule is introduced to judge sudden changes from innovation. When a sudden change occurs, the time update of the velocity from the tracing model is used for data fusion instead of the velocity from DVL. Simulation test results indicate that with this velocity tracing algorithm, random noise in the DVL can be effectively restrained. The level attitude accuracy and the level position accuracy are also improved with the time update of the velocity when the sudden change occurs.
Impacts of Soil Moisture on Typical Frontal Rainstorm in Yangtze River Basin
Authors: Min Jinzhong , Guo Yakai , Wang Guojie
Published: March 2016

By using a coupled land surface-atmosphere model with initial conditions of varying resolution and ensembles of systematically changed soil moisture, convective-scale simulations of a typical frontal rainstorm in the Yangtze River Basin are collected to investigate: (1) effects of different datasets on the simulated frontal mesoscale convective systems (MCSs); (2) possible linkages between soil moisture, planetary boundary layer (PBL), MCSs and precipitation in this modeled rainstorm. Firstly, initial soil moisture differences can affect the PBL, MCSs and precipitation of this frontal rainstorm. Specially, for a 90 mm precipitation forecast, the Threat score (TS) can increase 6.61% by using the Global Land Data Assimilation System (GLDAS) soil moisture. Secondly, sensitivity experiment results show that the near-surface thermodynamic conditions are more sensitive to dry soil than wet due to the initial moist surface; atmosphere conditions have suppressed the relations between soil and atmosphere; and decreased precipitation can be found over both wet and dry surfaces. Generally, a positive feedback between soil moisture and the near-surface thermodynamic conditions is identified, while the relations between soil moisture and precipitation are quite complicated. This relationship shows a daytime mixing of warm surface soil over dry surfaces and a daytime evaporation of adequate moisture over wet surfaces. The large-scale forcing can affect these relations and finally cause decreased precipitation over both wet and dry surfaces.
Reconstructing Fire Records from Ground-Based Routine Aerosol Monitoring
Authors: Zhao Hongmei , Tong Daniel , Lee Pius , Kim Hyuncheol , Lei Hang
Published: March 2016

Long-term fire records are important to understanding the trend of biomass burning and its interactions with air quality and climate at regional and global scales. Traditionally, such data have been compiled from ground surveys or satellite remote sensing. To obtain aerosol information during a fire event to use in analyzing air quality, we propose a new method of developing a long-term fire record for the contiguous United States using an unconventional data source: ground-based aerosol monitoring. Assisted by satellite fire detection, the mass concentration, size distribution, and chemical composition data of surface aerosols collected from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network are examined to identify distinct aerosol characteristics during satellite-detected fire and non-fire periods. During a fire episode, elevated aerosol concentrations and heavy smoke are usually recorded by ground monitors and satellite sensors. Based on the unique physical and chemical characteristics of fire-dominated aerosols reported in the literature, we analyzed the surface aerosol observations from the IMPROVE network during satellite-detected fire events to establish a set of indicators to identify fire events from routine aerosol monitoring data. Five fire identification criteria were chosen: (1) high concentrations of PM2.5 and PM10 (particles smaller than 2.5 and 10 in diameters, respectively); (2) a high PM2.5/PM10 ratio; (3) high organic carbon (OC/PM2.5) and elemental carbon (EC/PM2.5) ratios; (4) a high potassium (K/PM2.5) ratio; and (5) a low soil/PM2.5 ratio. Using these criteria, we are able to identify a number of fire episodes close to 15 IMPROVE monitors from 2001 to 2011. Most of these monitors are located in the Western and Central United States. In any given year within the study period fire events often occurred between April and September, especially in the two months of April and September. This ground-based fire climatology is also consistent with that derived from satellite retrievals. This study demonstrates that it is feasible to reconstruct historic records of fire events based on continuous ground aerosol monitoring. This dataset can provide not only fire activity information but also fire-induced aerosol surface concentrations and chemical composition that can be used to verify satellite-based products and evaluate air quality and climate modeling results. However, caution needs to be exercised because these indicators are based on a limited number of fire events, and the proposed methodology should be further tested and confirmed in future research.
Low-Temperature Catalytic Performance of Ni-Cu/Al2O3 Catalysts for Gasoline Reforming to Produce Hydrogen Applied in Spark Ignition Engines
Authors: Tuan Le , Luong Nguyen , Ishihara Keiichi
Published: March 2016

The performance of Ni-Cu/Al2O3 catalysts for steam reforming (SR) of gasoline to produce a hydrogen-rich gas mixture applied in a spark ignition (SI) engine was investigated at relatively low temperature. The structural and morphological features and catalysis activity were observed by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and temperature programmed reduction (TPR). The results showed that the addition of copper improved the dispersion of nickel and therefore facilitated the reduction of Ni at low temperature. The highest hydrogen selectivity of 70.6% is observed over the Ni-Cu/Al2O3 catalysts at a steam/carbon ratio of 0.9. With Cu promotion, a gasoline conversion of 42.6% can be achieved at 550 °C, while with both Mo and Ce promotion, the gasoline conversions were 31.7% and 28.3%, respectively, higher than with the conventional Ni catalyst. On the other hand, initial durability testing showed that the conversion of gasoline over Ni-Cu/Al2O3 catalysts slightly decreased after 30 h reaction time.