bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rheological Properties of Water-Based Drilling Fluids in Deep Offshore Conditions
Authors: Ding Qian , Sun Baojiang , Wang Zhiyuan , Gao Yonghai , Gao Yu , Liao Yongqiang , Wang Di , Xia Andi 
Published: November 2019

Abstract
In deep-water drilling, the drilling fluid is affected by the alternating temperature field derived from the low temperature of the seawater and the high temperature of the formation. The complicated wellbore temperature and pressure environments make the prediction of rheological properties of the drilling fluid difficult.
In this study, the rheological properties of water-based drilling fluid in full temperature and pressure range of deep-water conditions were tested from 2 to 150 °C (35.6 to 302 °F) and 0.1 to 70 MPa (14.5 to 10000psi). The experiment was carried out by the OFI130-77 high temperature and high pressure rheometer. The experimental data were processed by multiple regression analysis method, and the mathematical model for predicting the apparent viscosity, plastic viscosity and yield point of water-based drilling fluid under high temperature and high pressure conditions was established.
The experimental results show that when the temperature is lower than 65 °C (149 °F), the apparent viscosity and plastic viscosity of the water-based drilling fluid decrease significantly with increasing temperature. When the temperature is higher than 65 °C (149 °F), the apparent viscosity and plastic viscosity decrease slowly. Under low temperature conditions, the effect of pressure on the apparent viscosity and plastic viscosity of water-based drilling fluids is relatively significant. The calculated values of the prediction model have a good agreement with the experimental measurements. Compared with the traditional model, this prediction model has a significant improvement in the prediction accuracy in the low temperature section, which can provide a calculation basis for on-site application of deepwater drilling fluid.
Effect of Rock on Cement Sheath Integrity: Shale vs. Sandstone
Authors: Skorpa Ragnhild , Werner Benjamin , Vrålstad Torbjørn 
Published: November 2019

Abstract
It is crucial to understand cement sheath degradation mechanisms, since the cement sheath is an important well barrier element. Repeated pressure cycling is known to cause radial cracks and microannuli in the cement sheath, and the stiffness of the surrounding rock determines how much pressure the cement withstands before failure. However, experimental data on the effect of surrounding rock (shale vs. sandstone) on cement sheath integrity are scarce.
In this paper we present experimental studies on how different surrounding rocks influence cement sheath integrity. We have used our unique downscaled experimental set-up to perform pressure cycling tests with both shale and sandstones, where cement sheath integrity is visualized in 3D by X-ray computer tomography (CT). The obtained results confirm that a cement sheath surrounded by a rock with a relative higher Young’s modulus can withstand higher casing pressure compared to a cement sheath surrounded by rock with relative lower Young modulus. All cracks were initially observed as small defects in the cement sheath prior to expanding to full radial cracks and propagation into the surrounding formation.
Stability Analysis of Free Hanging Riser Conveying Fluid for Ocean Thermal Energy Conversion (OTEC) Utilization
Authors: Adiputra Ristiyanto , Utsunomiya Tomoaki 
Published: November 2019

Abstract
This paper examines the stability of a riser conveying fluid for Ocean Thermal Energy Conversion (OTEC) application by analytical and numerical approaches. Initially, the analytical solution for free hanging riser with fixed end connection is governed by including the components of the riser dynamics. Considering the boundary conditions, the general solution can be obtained using power series expansion. The imaginary and real parts of the solutions are plotted in an Argand diagram which is then used to predict the occurrence of instability. To verify the analytical solution, the dynamic behavior observed in the analytical solution is compared with the one predicted using numerical analysis. The numerical analysis here refers to a coupled analysis between riser and the fluid. After being verified, the analytical model is used to determine the acceptance of the proposed riser designs for 100 MW-Net OTEC power plant. In this paper, there are three materials being investigated which are steel, aluminum and FRP. For the given conditions, the results show that the critical velocity for steel-made riser is only about 0.9 m/s, for aluminum-made riser is about 1.7 m/s and the critical velocity for riser made of FRP is about 2.1 m/s.
FEA Based Simplified Integrated Analysis for Mudmat Design
Authors: Srigiriraju Srikanth , Chakraborty Arindam , Ozturk Burak , Rathore Devvrat 
Published: November 2019

Abstract
The objective of this study is to explore the opportunity to improve the design and sizing of mudmat for subsea structures, such as Pipeline End Termination (PLET). This is done by comparing the traditional approach following the limit equilibrium methods in API RP 2GEO with a more rigorous simplified integrated analysis approach that involves a single finite element analysis (FEA) model that includes both the pipeline and jumpers together along with the soil-mudmat interaction modeled as non-linear springs, and to quantify any conservatism inherent in the traditional approach.
A mudmat design with aspect ratio of 1:2 was considered for detailed analysis. Initially, jumper and pipeline loads were determined by imposing artificial boundary conditions at the hubs and end terminals. Using analytical methods and considering a total dead (submerged) weight of the mudmat and superstructure, a mudmat size was determined per the American Petroleum Institute (API) approach. Factor of Safety (FOS) for bearing and sliding loads were also determined. Thereon, using this mudmat size, the FOS for bearing and sliding were determined using the simplified integrated approach with nonlinear springs representing soil-mudmat interactions.
The FOS values using the simplified approach were observed to be higher than those obtained using the traditional approach. This provides an opportunity for a “leaner” design, especially as new high pressure, high temperature (HPHT) fields are made feasible where the mudmat size, if designed with conservatism in API RP 2GEO, may be impractically large for installation.
Comparative Study on Fatigue Damage Assessment of a Structure Member in a Bulk Carrier Using Various Environmental Conditions
Authors: Prasetyo Fredhi Agung , Osawa Naoki , Kurniawan Mohammad Arif , Komariyah Siti 
Published: November 2019

Abstract
Specific design life could be identified by using fatigue damage assessment in the structure engineering field as well as in the maritime sector. Fatigue assessment is one of the assessments to be conducted during review of ship structure design. Fatigue assessment of ship structural member is mainly conducted based on specific environmental condition. In general, specific environmental condition, which is provided by Classification Society rules, is a long term sea-state data of North Atlantic Ocean. The wave scatter diagram presents the tabulation of a long term data of sea state history in the specific ocean. Therefore, a realistic encounter of wave scatter diagram is essential to simulate the variation of wave loadings applied on the ship structure in determination of fatigue design life.
Since the application of North Atlantic ocean environmental condition is commonly used by major Classification societies, this condition might give the substantial deterioration on the fatigue design life of the ship that specially operate only in specific ocean area, i.e. South East Asia area. In this work, the wave scatter diagram of various environmental conditions is chosen and the statistical characteristic is compared. The wave load sequence that is used on the fatigue damage assessment are generated by using the concept of storm model, so that the changing nature of sea state could be emulated as in real ocean. Fatigue damage of a structure member of 220 meter Bulk Carriers is calculated based on various environmental conditions.
Hydrodynamic Load Modeling for Offshore Free-Floating Macroalgal Aquaculture Under Extreme Environmental Conditions
Authors: Chen Ming , Yim Solomon C. , Cox Daniel , Wang Taiping , Huesemann Michael , Yang Zhaoqing , Mumford Thomas , Wood Geoffrey 
Published: November 2019

Abstract
This article describes a preliminary study of an on-going ARPA-E (Advanced Research Projects Agency-Energy) MARINER Phase I project. The hydrodynamic load and dynamic response of an innovative offshore macroalgae cultivation system, Nautical Offshore Macroalgal Autonomous Device (NOMAD), under extreme environmental conditions is examined. The high strength, extremely durable, recyclable carbon fiber (rCF) free-floating long-line is applied with polyculture (Nereocystis luetkeana (bull kelp) and Saccharina latissima (sugar kelp)) in the NOMAD system. This novel macroalgal farming system is designed to free float from Washington State to California along the west coast of the US to avoid anchoring costs and the failure of earlier offshore growth trials. In this study, we expect to identify possible failure modes for the preliminarily design of NOMAD free-floating long-line macroalgal farming system based on the preliminary numerical predictions. We developed a 1km system-scale NOMAD free-floating long-line numerical model and performed a dynamic response analysis on the long-line to determine the behaviors of the long-line under extreme environmental conditions. The 1km free-floating rCF long-line responses very flexible due to wave and current activities even for large bending stiffness. Therefore, the potential entanglement of free-floating long-line on a global scale may cause the system failure even when the tensions and bending moments are in the safe range. Three cases include 10m NOMAD free-floating long-line with sugar kelp, bull kelp, and polyculture numerical models are developed, and the simulation results are analyzed. The tensions at the holdfast of the kelps in these cases are found to be below the breakage limit approximately. However, the severe clumping of the kelps and potential entanglement of adjacent lines may result in damage to the farming system.
Modification to Shield Tank Overpressure Protection in a CANDU Reactor for Beyond Design Basis Event
Authors: Huang Michael , Khan Khurram , Etedali-Zadeh Ali , Tse Jefferson , Li Bing 
Published: November 2019

Abstract
The Shield Tank and End Shield Cooling System in the CANDU reactor contains a large volume of light water surrounding the Calandria and circulates water to remove heat that arises from the reactor core and Moderator. In a beyond design basis event that results in a severe event, progression in the absence of mitigating cooling actions could result in a large heat load being transferred to the water inside the shield tank from the calandria wall causing shield tank failure due to over pressurization. Following the 2011 events at Fukushima Daiichi Nuclear Power Plant, the adequacy of system pressure relief was assessed against severe events. Emergency mitigating equipment tie-ins for water make-up will likely limit the core damage state and prevent the need to protect the shield tank. However, Shield Tank Overpressure Protection (STOP) has been installed against severe event conditions pursuant to the CANDU defense-in-depth safety philosophy. A larger open vent line has been installed at some CANDU units on the top of the shield tank outside containment. This design routes the vent piping high enough to preclude any venting under any operational configuration and discharges back into the containment through an existing spare penetration. Vent piping is designed as Nuclear Class 2 in accordance with ASME BPVC Section III. Assessment of stresses in the modification piping was also completed for BDBEs including for a lower probability seismic event, steam venting and corresponding higher pressure and temperature conditions.
Simple Pd-Ag-H EAM Potentials for Hydrogen Storage Applications
Authors: Fuller Robert , Hijazi Iyad 
Published: November 2019

Abstract
The palladium–hydrogen system has attracted a vast amount of research interest. Palladium’s ability to absorb hydrogen at room temperature is reversible, and therefore suitable for many applications, including fuel cells, hydrogen storage, and nuclear radiation adsorption. Alloying palladium with silver can increase its performance in many applications as well as substantially lowering the materials cost. Palladium silver alloys can offer increased H diffusivity and a less pronounced miscibility gap with much improved mechanical properties over pure palladium. However, the relative insolubility of hydrogen in silver necessitates proper alloying of Pd-Ag to obtain the best combination of properties. Atomic simulations are useful in the evaluation of palladium-silver hydride systems as changes in composition can be more easily explored than with experiments. In this work we introduce fully analytical Embedded Atom Method (EAM) potentials for the Pd-Ag-H system, with fewer fitting parameters than previously developed EAM models. The central atom method is used, without the need for time-consuming molecular dynamics simulations during the fitting procedure.
Overview of Revisions to the ASME Boiler and Pressure Vessel Code Section VIII Division 3 for the 2019 Edition and Near Future
Authors: Maslowski Adam P. , Mital Gregory , Peters Daniel , Subramanian Kannan 
Published: November 2019

Abstract
This paper provides an overview of the significant revisions to the upcoming 2019 edition of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Section VIII Division 3, Alternative Rules for Construction of High Pressure Vessels, as well as potential changes to future editions under consideration of the Subgroup on High Pressure Vessels (SG-HPV).
Identification of Key Factors of Fire Risk of Oil Depot Based on Fuzzy Clustering Algorithm
Authors: Xie Shuyi , Dong Shaohua , Zhang Guangyu 
Published: November 2019

Abstract
With the rapid development of the national economy, the demand for oil is increasing. In order to meet the increasing energy demand, China has established a number of oil depot in recent years, whose largest capacity reaching up to tens of millions of cubic meters. Due to the flammable and explosive nature of the stored medium, the risk of fire in the oil depot area has increased dramatically as the tank capacity of the storage tank area has increased. The intensification of the oil depot and the development of large-scale oil storage tanks have brought convenience to the national oil depot, but also brought many catastrophic consequences. In recent years, there have been many fires and explosions in the oil depot, causing major casualties and property losses, which seriously endangered the ecological environment and public safety.
Based on the constructed oil depot fire risk index system, the fuzzy C-means algorithm (FCM) and fuzzy maximum support tree clustering algorithm is introduced. Through the two fuzzy clustering mathematical models, key factors in the established index system are identified. Firstly, the expert scoring method is used to evaluate the indicators in the oil depot fire risk index system, and the importance degree evaluation matrix of oil depot fire risk factors is constructed through the fuzzy analysis of expert comments. Then, the fuzzy C-means algorithm (FCM) and the fuzzy clustering tree algorithm are used to cluster the various risk indicators, and the key factors of the oil depot fire risk are identified. Through the comparative analysis and cross-validation of the results of the two fuzzy clustering methods, the accuracy of the recognition results is ensured. Finally, using an oil depot as a case study, it is found that passive fire prevention capability and emergency rescue capability are key factors that need to be paid attention to in the oil depot fire risk index.
The fuzzy clustering algorithm used in this paper can digitize the subjective comments of experts, thus reducing the influence of human subjective factors. In addition, by using two fuzzy clustering algorithms to analyze and verify the key factors of the oil depot fire risk, the reliability of the clustering results is guaranteed. The identification of key factors can enable managers to predict high-risk factors in advance in the fire risk prevention and control process of the oil depot, so as to adopt corresponding preventive measures to minimize the fire risk in the oil depot, and ensure the safety of the operation of the oil depot.
Fabrication and Mechanical Aspects of Using FeCrAl for Light Water Reactor Fuel Cladding
Authors: Rebak Raul B. , Huang Shenyan , Schuster Michael , Buresh Steve J. , Dolley Evan J. 
Published: November 2019

Abstract
General Electric (GE) is working with the US Department of Energy (DOE) to develop advanced technology fuel (ATF) for light water reactors (LWR) that will have enhanced tolerance to failure under severe accident conditions. The development of materials for the current fuel is aimed at Generation III LWR but findings may be extended to future Generation IV reactors. One of the concepts pursued by GE is to use iron-chromium-aluminum (FeCrAl) or IronClad for the cladding due to its outstanding resistance to reaction with air and steam at temperatures higher than 1000°C. Ferritic FeCrAl alloys have been used for almost nine decades in the industry, but never in nuclear applications, therefore its fabrication and mechanical aspects for nuclear use needs to be evaluated. Results show that billets of FeCrAl can be produced via traditional melting and using powder metallurgy, and these billets can later be processed to high strength full length cladding tubes having less than half a millimeter wall thickness. The tubes can be joined to the caps via several welding processes.
Experimental Study on Cryogenic Ratcheting of Pre-Strain Austenitic Stainless Steel SS304
Authors: Li Leilei , Gao Bingjun , Dong Junhua , Chen Xu 
Published: November 2019

Abstract
Austenitic stainless steel SS304 is often used as the inner container of the Liquefied Natural Gas (LNG) semitrailer tank. Due to excellent cryogenic ductility and strain-hardening effect, pre-strain of austenitic stainless steel is practicable and conducive to achieve lightweight design of this kind of transporting vehicle. In the present work, we focus on the cryogenic ratcheting of pre-strain austenitic stainless steel SS304. The SS304 specimens were cut from as received plates and butt welded plates which are all pre-strained 8% and 12%. With CARE electronic universal testing machine, ratcheting experiments are performed at both ambient temperature and 110K with different mean stresses and stress amplitudes. Ratcheting strains increase with the mean stress and stress amplitude under cryogenic temperature, but much smaller than that at ambient temperature. And it would quickly get shakedown after ratcheting in a few cycles due to the rapid γ-α′ phase transformation under cryogenic temperature. The cryogenic ratcheting strain generally reduces with the pre-strain amount for both parent material specimens and welded specimens. Compared with parent material specimens, weld specimens yield much smaller cryogenic ratcheting strain due to the hardening effect of welding induced initial ferrite with less slipping system.
Variable Loading Sequence Effect for Thermal Fatigue at a Mixing Tee
Authors: Miyoshi Koji , Kamaya Masayuki 
Published: November 2019

Abstract
Mixing flow causes fluctuations in fluid temperature near the pipe wall and may result in fatigue crack initiation. In a previous study, the authors reported the characteristics of the thermal stress to cause thermal fatigue at a mixing tee. A large stress fluctuation was caused by movement of the hot spot, at which the pipe wall was heated by hot flow from the branch pipe. According to a general procedure, fatigue damage is calculated by the linear damage accumulation rule. However, it has been reported that Miner’s rule does not always predict the fatigue life conservatively for variable stress amplitude. In this study, we investigated the change in fatigue life due to variable strain around the hot spot. The time histories of the strain around the hot spot were estimated by finite element analysis (FEA) for which the temperature condition was determined by wall temperature measured in a mock-up test. Strain-controlled fatigue tests were conducted using smooth cylindrical specimens made of stainless steel. The fatigue damage at failure of the specimen was calculated using Miner’s rule. The calculated fatigue damage around the hot spot became less than unity and the minimum value was 0.18. Therefore, Miner’s rule predicted non-conservative fatigue life. In addition, the calculated fatigue damage inside the hot spot was larger than those outside the hot spot and at the position of maximum stress fluctuation. Fatigue tests using strain with periodic overload were also conducted in order to investigate the effect of the loading history on fatigue life. It was shown that the strain with periodic overload reduced the fatigue life. The calculated fatigue damage for the strain at the maximum position of stress fluctuation range seemed to be smaller than those at other positions. This implies that the fatigue life can be estimated conservatively from the viewpoint of the loading sequence effect by calculating the fatigue damage using Miner’s rule for the strain at the maximum position of stress fluctuation range.
Direct Analysis of Post-Shakedown Quantities With the STPZ Considering Multi-Parameter Loading
Authors: Vollrath Bastian , Hübel Hartwig 
Published: November 2019

Abstract
If a structure is subjected to cyclic loading, strain, displacements etc. may accumulate cycle by cycle due to a ratcheting mechanism. Design Codes frequently require strain limits to be satisfied at the end of the specified lifetime of the structure. Usually, this is requested to be done considering all load sets pairwise. However, this leads to the fact that ratcheting cannot be detected, if it occurs only because of multi-parameter loading. Ordinary incremental step-by-step calculations can easily exceed time and hardware resources. This is particularly true for travelling loads, where many load steps are required for one load cycle. As an alternative, the Simplified Theory of Plastic Zones (STPZ) is used in the present paper. Being a direct method, effects from load history are disregarded. The elastic-plastic behavior in the state of either elastic or plastic shakedown is estimated on the basis of purely elastic analyses. Two kinds of linear elastic analyses are to be performed, fictitious elastic analyses for each set of loading, and a number of modified elastic analyses. Few of these analyses are usually sufficient to obtain reasonable estimates of the post-shakedown quantities. Trilinear material behavior is adopted along with kinematic hardening, a Mises yield surface and an associated flow law. The modified elastic analyses are performed making use of modified elastic parameters (Young’s modulus and Poisson’s ratio) in the plastic zone and applying suitably defined initial strains. The results obtained can be improved iteratively. The theory of the method is briefly explained and its application is shown using an example with multi-parameter loading.