bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mathematical Modeling and Computer Simulation of Fatigue Properties of Quenched and Tempered Steel
Authors: Smoljan Božo , Iljkić Dario , Traven Furio , Mrša Josipa 
Published: November 2010

Abstract
The engineering and economical aspects of the optimization of steel shaft quenching and tempering were investigated. The mathematical model and method of computer simulation for the prediction of fatigue properties of quenched and tempered steel were developed. Computer simulation of the fatigue properties of quenched and tempered steel was applied in the optimization of quenching and tempering of steel shafts. The proper heat treatment process was accepted based on economical analysis. Fatigue properties of quenched and tempered steel were predicted based on microstructure composition and yield strength. Microstructure composition and yield strength were predicted based on as-quenched hardness. The distribution of as-quenched hardness in the workpiece was predicted through computer simulation of steel quenching using a finite volume method. The as-quenched hardness was estimated based on time of cooling and on Jominy test results. It was taken into account that the mechanical properties of quenched steel directly depend on the hardness, degree of hardening, and microstructural constituents. Using a numerical simulation of microstructure and mechanical properties, it was found out that the investigated shaft has the best fatigue properties in cases when the shaft was machined or formed on proper geometry before proper quenching and tempering. Through economical analysis of the investigated shaft manufacturing, it was found out that the most suitable shaft manufacture process is to manufacture the shaft from the quenched and tempered bar. But in this case, heterogeneous microstructures of ferrite, perlite, bainite, and martensite with very low fatigue limits could appear at some critical locations.
Danish children born with glutamic acid decarboxylase-65 and islet antigen-2 autoantibodies at birth had an increased risk to develop type 1 diabetes
Authors: Eising Stefanie , Nilsson Anita , Carstensen Bendix , Hougaard David M , Nørgaard-Pedersen Bent , Nerup Jørn , Lernmark Åke , Pociot Flemming 
Published: November 2010

ObjectiveA large, population-based case–control cohort was used to test the hypothesis that glutamic acid decarboxylase-65 (GAD65) and islet antigen-2 autoantibodies (IA-2A) at birth predict type 1 diabetes.Design and methodsThe design was an individually matched case–control study of all Danish type 1 diabetes patients born between 1981 and 2002 and diagnosed before May 1 2004 (median age at diagnosis was 8.8 years). Dried blood spot samples collected 5 days after birth in the 1981–2002 birth cohorts and stored at −25 °C were identified from 2023 patients and from two matched controls (n=4042). Birth data and information on parental age and diabetes were obtained from Danish registers. GAD65A and IA-2A were determined in a radiobinding assay. HLA-DQB1 alleles were analyzed by PCR using time-resolved fluorescence.ResultsGAD65A and IA-2A were found in 70/2023 (3.5%) patients compared to 21/4042 (0.5%) controls resulting in a hazard ratio (HR) of 7.49 (P<0.0001). The HR decreased to 4.55 but remained significant (P<0.0003) after controlling for parental diabetes and HLA-DQB1 alleles. Conditional logistic regression analysis showed a HR of 2.55 (P<0.0001) for every tenfold increase in the levels of GAD65A and IA-2A. This HR decreased to 1.93 but remained significant (P<0.001) after controlling for parental diabetes and HLA-DQB1 alleles.ConclusionThese data suggest that GAD65A and IA-2A positivity at birth are associated with an increased risk of developing type 1 diabetes in Danish children diagnosed between 1981 and 2004.
VEGFR1 expression is related to lymph node metastasis and serum VEGF may be a marker of progression in the follow-up of patients with differentiated thyroid carcinoma
Authors: Karaca Z , Tanriverdi F , Unluhizarci K , Ozturk F , Gokahmetoglu S , Elbuken G , Cakir I , Bayram F , Kelestimur F 
Published: November 2010

ObjectiveVascular endothelial growth factor (VEGF) and VEGF receptor 1 (VEGFR1) are known to be related to thyroid tumorigenesis. The aim of the study was to examine the expressions and serum levels of VEGF, VEGFR1, IGF1, and IGF1 receptor (IGF1R) in patients with differentiated thyroid carcinoma (DTC) compared with patients with nodular goiter (NG).MethodsWe examined 39 patients with DTC who had a clinical history of at least 2 years and compared them with 25 patients who had a pathological diagnosis of NG after thyroidectomy. Serum VEGF, VEGFR1, and IGF1 levels were measured in both patient groups. The expressions of VEGF, VEGFR1, IGF1, and IGF1R were analyzed by the immunohistochemical method in the paraffin blocks of patients' thyroidectomy samples of the patients.ResultsThe immunostainings scores for VEGF, VEGFR1, IGF1, and IGF1R were found to be higher in patients with DTC than in those with NG. Only VEGFR1 expression was related to lymph node metastasis at the time of surgery. None of the expressions were related to the long-term prognosis of the patients. Serum VEGF was found to be higher in patients with progressive DTC than in patients in clinical remission.ConclusionThe expressions of VEGF and VEGFR1 were shown to be correlated with the expression of IGF1 and IGF1R. VEGFR1 expression may be an important index for the presence of lymph node metastasis at the time of thyroidectomy. Increased serum levels of VEGF may reflect disease recurrence in DTC.
Measurement of Carbon Dioxide Capillary Trapping in Core Analysis
Authors: Pentland C.H.. H. , Iglauer S.. , El-Maghraby R.. , Tsuchiya Y.. , Okabe H.. , Blunt M.J.. J. 
Published: November 2010

AbstractCapillary trapping has been identified as a fast and effective method to render injected carbon dioxide (CO2) immobile as disconnected pore-scale droplets surrounded by brine. We measure trapped CO2 saturations in sandstones at conditions representative of storage locations. We compare the unsteady state and porous plate methods of achieving initial CO2 saturations before waterflooding to reach residual saturation. Brine and CO2 are equilibrated prior to injection to ensure immiscible displacements occur on the pore scale. The problems faced with un-equilibrated phases are discussed.The unsteady state and porous plate methods are shown to give different results in terms of maximum initial and residual saturations for Berea sandstone samples. With the unsteady state method maximum residual CO2 saturations of 25-28% are measured for corresponding maximum initial saturations of 35-40%. With the porous plate method a maximum residual saturation of 37% is measured for a maximum initial saturation of 90%. The implications for coreflood method selection during data gathering are discussed.The porous plate results are compared with oil-brine porous plate saturations measured on the same samples. CO2-brine residual saturations are shown to be slightly lower than the corresponding oil-brine measurements. We suggest that considerable carbon dioxide capillary trapping is possible in clean sandstones and discuss the implications for carbon storage in aquifers.
CO2 Sequestration in Deepwater Subseabed Formations
Authors: Pilisi N.. , Ceyhan I.. , Vasantharajan S.. 
Published: November 2010

Abstract
Recent studies have estimated that oceans have naturally sequestrated, by dissolving and mixing with deep waters, about 40% of the anthropogenic CO2 emitted since the start of the industrial revolution. Moreover, the International Maritime Organization has recently announced that storage of CO2 under the seabed would be allowed starting in 2007. To date, almost all studies, simulations and technical papers concerning carbon sequestration have focused on storing supercritical CO2 in deep saline aquifers or depleted oil and gas reservoirs. However, a critical limiting factor for such carbon sequestration is the need for proper physical trapping and the necessity for monitoring the upward migration due to buoyancy effects and mobility of supercritical CO2. Carbon sequestration in deepwater sub-seabed formations provides an attractive alternative.
This paper presents a feasibility study of carbon sequestration in deepwater formations in the Gulf of Mexico with the existing technologies available in the offshore industry. We describe each step of the carbon capture and storage process and discuss the technical limitations when trying to capture CO2 from industrial processes, transport it offshore via tanker, drill a CO2 injector well and then, inject the CO2 from floating facilities such as drill ships or semi-submersible vessels. Due to high pressures and low temperatures reigning at water depths deeper than 9,000 feet, the liquid CO2 injected in the first few hundred feet of deposits will have a higher density than the surrounding formation pore-fluid and therefore will be buoyantly trapped. In addition, CO2 hydrates that may form and fill up pore spaces will act as an additional trapping mechanism. Finally, at these great depths, the CO2 that could leak will dissolve by reacting with ocean waters and forming mainly bicarbonate compounds.
Because oceans cover about 70% of the Earth’s surface with an average water depth of 12,500 feet, deepwater sub-seabed sequestration provides an enormous storage capacity to counteract increasing world consumption of fossil fuels. However, large time and space-scale simulations need to be performed to estimate the impact of the change in geochemistry in the deepwater seabed region. Also, the injection of liquid CO2 will force and displace formation fluid into the seabed surface zone, which will change the ocean chemistry.
CO2 Storage Engineering: Real Solution to Real Problems
Authors: Kuuskraa V. A. , Koperna G. J. , Schepers K.. 
Published: November 2010

Abstract
Deep saline aquifers offer the potential for storing large volumes of CO2. However, with conventional CO2 storage well design and operating practices, only a small fraction of this large CO2 storage potential can be productively used. Numerous alternative designs and practices, which utilize the reservoir’s internal architecture and draw on CO2 storage engineering expertise, could enable CO2 storage operators to more efficiently and fully utilize a saline formation’s storage capacity. This would help reduce the areal extent of the CO2 plume and its risk footprint. It would also help reduce the number of CO2 injection wells and patterns that would need to be developed.
This paper, entitled "CO2 Storage Engineering: Real Solution to Real Problems", discusses practical CO2 storage options that have been proposed for significantly increasing CO2 storage performance at three challenging saline reservoir settings.
Interpretation of CO2-Sequestration-Induced Surface Deformation at Krechba, Algeria
Authors: Davis E. J. , Marsic S. D. 
Published: November 2010

AbstractThe Krechba field is part of a multi-field gas development in central Algeria where CO2 is being injected rather than vented to develop carbon storage techniques within an active gas producing reservoir. Surface deformation monitoring has thus far proven to be one of the more useful of a wide array monitoring methods deployed at the site. Using differential interferometric synthetic aperture radar (InSAR), Pinnacle and MDA Geospatial services produced a high-resolution deformation time series of the Krechba field area over a 5 year period between 2004 and 2009. While the deformation measurements provide a qualitative visual assessment of the injection performance, the real goal of surface deformation monitoring is to determine the location of subsurface strain changes induced by the injected fluid. A geomechanical model is needed to determine the surface response to a given subsurface strain. An inversion routine modifies the strain source or sources to find a system that produces theoretical surface motion that best matches the measured deformation. This paper uses the example at injection well KB-501 to explore how the solution and associated uncertainty is affected by the choice of geomechanical model at this location. The best fit solution and sensitivity of that solution is derived from homogeneous and layered models of varying complexity using both linear and non-linear inversion techniques. The results place boundaries on the possible subsurface pressure distribution associated with CO2 injection and also quantify the possible benefit obtained from more complex geomechanical modelling for inversion of surface deformation data. The solutions suggest that the injected fluid at KB-501 remains near the intended depth and is spreading primarily along a northwest-southeast trajectory as anticipated.
Retardation of CO2 due to Capillary Pressure Hysteresis: a New CO2 Trapping Mechanism
Authors: Altundas Y. B. , Ramakrishnan T. S. , Chugunov Nikita , de Loubens Romain 
Published: November 2010

Abstract
Trapping of CO2 improves containment security of geologically stored CO2. To be able to asses the potential of a storage site using reservoir simulators, it is necessary to include all of the possible trapping mechanisms in the numerical algorithms. Currently, four trapping mechanisms are identified in the CO2 sequestration literature: structural, residual, dissolution, and mineralization. Although capillary pressure hysteresis has been accounted for in the historical development of simulators, it has not been recognized as a process for hindering movement of the injected CO2. Capillary pressure hysteresis reduces the buoyancy driven plume movement significantly compared to relative permeability hysteresis; but it is the latter that has been emphasized in the published literature. In this paper, we focus on a quantitative measure for the contribution of hysteresis in reducing plume transport. Rocks with large pore body to throat size ratio are the best candidates for this mechanism to be operative.
In the present work, a self-consistent relative-permeability capillary-pressure hysteresis model is incorporated within a simulator. With this model, it is possible to compare and contrast hysteresis induced retardation to other mechanisms of trapping. The self-consistent parametrization of all of the transport properties is used to quantify sensitivity compactly. The sensitivity of the CO2 plume shape and the amount of CO2 trapped, to the strength of the capillary pressure hysteresis, is also described.
Simulated results show that CO2 plume shape with and without capillary pressure hysteresis are significantly different. As expected, capillary pressure hysteresis retards the buoyant transport of the CO2 plume. Although a portion of the CO2 is connected, and therefore not residual, the plume remains immobile for all practical purposes. Also, due to decreased driving potential, gravity tonguing below the caprock is reduced in comparison to the case without capillary pressure hysteresis, thus suggesting enhanced storage efficiency. However, the total dissolution of CO2 in saline water is reduced because of the reduced diffusive transport of CO2 within the brine. Thus, one mechanism of containment is offset by the other.
Inclusion of accurate hysteresis models is important for qualifying storage sites constrained by spatial domain limits. It is anticipated that site acceptability criteria would change as a result of this study, thus impacting risk evaluation.
Optimization of Geologic CO2 Storage in Heterogeneous Aquifers Through Improved Sweep Efficiency
Authors: Shamshiri H.. , Jafarpour B.. 
Published: November 2010

Abstract
Optimization of waterflooding sweep efficiency has been widely applied in reservoir engineering to improve hydrocarbon recovery while delaying water breakthrough and minimizing the bypassed oil in reservoirs. We develop a new framework to optimize flooding sweep efficiency in geologic formations with heterogeneous properties and demonstrate its application to waterflooding and geological CO2 sequestration problems. The new method focuses on equalizing and delaying (under constant total injected volume) the breakthrough time of the injected fluid at production wells. For application to CO2 sequestration where producers may not be present, we introduce the concept of pseudo production wells that have insignificant production rates (with negligible effect on the overall flow regime) for quantification of hypothetical breakthrough curves that can be used for optimization purpose. We apply the new method to waterflooding and CO2 sequestration optimization using two heterogeneous reservoir models. We show that in water flooding experiments the proposed method improves the sweep efficiency by delaying the field breakthrough and equalizing breakthrough times in all production wells. In this case, the optimization results in increased oil recovery and decreased water production. We apply a modified version of the proposed algorithm to geologic CO2 sequestration problems to maximize the storage capacity of aquifers by enhancing the residual and dissolution trapping. The results from applying the proposed approach to optimization of geologic CO2 storage problems illustrate the effectiveness of the algorithm in improving residual and solubility trapping by increasing the contact between available fresh brine and the injected CO2 plume through a more uniform distribution of CO2 in the aquifer.
Effects of CO2 Storage in Saline Aquifers on Groundwater Supplies
Authors: Kalunka Johannes E. , LaForce Tara C. , Blunt Martin J. 
Published: November 2010

Abstract
The aim of this paper is to investigate the effects of CO2 sequestration on groundwater abstraction above the storage formation. Large-scale (10Mt/yr) CO2 injection in underlying saline aquifers is considered using a fully compositional simulator to study the pressure distribution, CO2 leakage and inter-layer brine flow. Structural, residual and solubility CO2 trapping are taken into account while the model domain is considered to have no-flow boundaries to simulate CO2 injection under the context of either pressure not being able to be dissipate quickly (due to other CO2 injection processes, for instance) or the formation being self-contained. Changes in salinity are affected by groundwater abstraction and although not caused by injection itself, can be magnified by such processes. We also conclude that the time at which CO2 leakage, pressure perturbations and upward brine flow are at their peak in overlying aquifers (layers above the injection site) may be significantly after injection has ceased (50-150 years in some cases) and could potentially cause groundwater movements, land surface uplift or rock fracturing long after the injection phase has ended.
The Social Evaluation of Intergenerational Policies and Its Application to Integrated Assessment Models of Climate Change
Authors: Kaplow Louis , Moyer Elisabeth , Weisbach David A 
Published: November 2010

AbstractAssessment of climate change policies requires aggregation of costs and benefits over time and across generations, a process ordinarily done through discounting. Choosing the correct discount rate has proved to be controversial and highly consequential. To clarify past analysis and guide future work, we decompose discounting along two dimensions. First, we distinguish discounting by individuals, an empirical matter that determines their behavior in models, and discounting by an outside evaluator, an ethical matter involving the choice of a social welfare function. Second, for each type of discounting, we distinguish it due to pure time preference from that attributable to curvature of the pertinent function: utility functions (of consumption) for individuals and the social welfare function (of utilities) for the evaluator. We apply our analysis to leading integrated assessment models used to evaluate climate policies. We find that past work often confounds different sources of discounting, and we offer suggestions for avoiding these difficulties. Finally, we relate the standard intergenerational framework that combines considerations of efficiency and distribution to more familiar modes of analysis that assess most policies in terms of efficiency, leaving distributive concerns to the tax and transfer system.
Manufacturing of Open‐Cell Metal Foams Using a Novel Leachable Pattern
Authors: Michailidis Nikolaos , Stergioudi Fani , Tsipas Dimitrios N. 
Published: November 2010

AbstractA space‐holder method using crystalline carbohydrate particles, as a novel leachable pattern for manufacturing open‐cell metal foams is described. The method involves mixing and compaction, leaching and sintering processes. Open‐cell Al foams with porosity up to 70% can be produced. The removal of the carbohydrate particles from the green compact is achieved by water leaching at room temperature. An appropriate sintering leads to a very good result as far as the microstructure achieved is concerned.
Very Large Photoconduction Enhancement Upon Self‐Assembly of a New Triindole Derivative in Solution‐Processed Films
Authors: Gallego‐Gómez Francisco , García‐Frutos Eva M. , Villalvilla José M. , Quintana José A. , Gutierrez‐Puebla Enrique , Monge Angeles , Díaz‐García María A. , Gómez‐Lor Berta 
Published: November 2010

AbstractA new carbazole‐related small molecule exhibiting self‐assembly into ordered nanostructures in solution‐processed cast films has been synthesized and its charge‐photogeneration and ‐transport properties have been investigated. Large photoconductivity was measured in the amorphous state while an enormous improvement in the photoconduction properties was observed when the molecules spontaneously organized. Photocurrents increased upon self‐assembly by up to four orders of magnitude, mostly due to the drastic enhancement of the charge photogeneration. A greatly favorable arrangement of the aromatic cores in the resulting nanostructures, which were characterized by X‐ray analysis, may explain these improvements. Photocurrents of mA cm−2, on/off ratios of 104 and quantum efficiencies of unity at low field and light intensity, which are among the best values reported to date, along with the simplicity of fabrication, give this readily‐available organic system great potential for use in plastic optoelectronic devices.