Journal articles on the topic '12th International Fluid Power Conference'

This is the text of the presentation “Charles V and the Fury at the Prado Museum: The Power of the King’s Body as Image” at the International Conference “El poder del la imagen en el Museo del Prado” (Madrid, December 12th-13th, 2017). By analysing the bronze sculpture Charles V and the Fury (Leone and Pompeo Leoni, 1549-1564. Prado Museum, Madrid), this paper aims to underline the necessity to study royal images in their context (with particular attention to their visibility) to understand better their social use and function. This type of methodological approach can be without any doubt very useful for the historiography in the overall analysis of the leader’s portrait and can stimulate new researches for the future and reformulate some of the traditional conceptions on this topic.

Despite widespread awareness of the health benefits for both mothers and babies we are far from achieving universal breastfeeding. Breastfeeding rates globally are lower than recommended levels and there are concerns that some global breastfeeding efforts have stalled (1, 2). In addition, we see persistent disparities in breastfeeding rates by race, ethnicity, class and status (3). A growing literature documents how a range of injustices, including gender inequality (7), racism (8), poverty (9), and violence (10, 11) shape whether, how exclusive, and for how long mothers and others will be able to breastfeed or feed their infants human milk. These social injustices and inequities work to privilege breastfeeding even as the health message becomes more mainstreamed and human milk more desirable. A social justice approach could help us address the gender, race, and sexuality-based inequities and injustices in opportunities, resources, status, and power that are influencing the patterns of breastfeeding we see today. The 12th Breastfeeding and Feminism International Conference held in 2017 took as its theme Breastfeeding as Social Justice: From Crucial Conversation to Inspired Action. The planning team for that conference identified seven core domains that could help us conceptualize a framework for placing social justice at the core of our work. This paper presents this framework and suggestions for policy and practice that follow.

Mechatronics is one of the most powerful technologies to overcome various industrial and social problems arising in the 21st century, for example, realization of the recycle manufacturing system, global consideration on the environment, development of human-oriented technology. The 3rd International Conference on Advanced Mechatronics (ICAM’98)-Innovative Mechatronics for the 21st Century hass been held in Okayama August 3-6, 1998, following the 1st and 2nd held in Tokyo in 1988 and 1993, sponsored by the Japan Society of Mechanical Engineers. The purpose of the conference is to promote the creation of new technologies and industries such as advanced robotics and human-oriented technology for the coming 21st century. Two plenary talks and 35 technical sessions including 11 specially organized sessions were opened. In technical sessions, a total of 149 papers was presented, of which 61 papers were in organized sessions and 88 papers in general sessions. Some 47 papers came from 17 countries abroad and 102 papers from Japan. A number of registered participants excluding invited guests was 40 from other countries and 163 from Japan. After the technical program, the Advanced Robotics and Mechatronics symposium was held for tutorial reviews of future robotics and mechatronics, mainly focusing on ""human collaboration"" technology. More than 100 persons attended the symposium. Organized sessions included Analysis and Control of Robot Manipulators, Modeling and Control of Nonholonomic Underactuated Systems, Human Perspective Characteristics and Virtual Reality, Robotic Hand Design Grasping and Dexterous Manipulation, Healthcare Robotics, Advanced Fluid Power Control Technology, Advanced Robot Kinematics, Human Directed Robotics, Computer Support for Mechatronics System Design, Robotic Control, and Motion Control of Special Motors. Robotics was a main subject, but fluid power technology, fundamental motion control technology, and so on were also discussed. “Human collaboration” technology dealing with interaction between humans and robots attracted great attention from many participants. General sessions included Manufacturing, Vision, Micro Machine, Electric Actuator, Human-Robot Interface, Processing Technology, Fluid Actuator, Legged Locomotion, Control Strategy, Soft-Computing, Vehicle, Automation for Agriculture, Robot Force Control, Vibration, and Robot Application. Many studies have been presented over comprehensive subjects. This special issue has been organized by editing the papers presented at ICAM’98 for widely distributing the significant results of the conference. I would like to thank the authors in this special issue who have contributed their updated papers. Also, I would like to thank to Prof. Makoto Kaneko (Hiroshima University), whose work has been indispensable in organizing this special issue.

The results of the International Wet Steam Modelling Project presented at the Wet Steam Conference in Prague in 2016 again gave rise to a discussion about the suitability of the flow solver ANSYS CFX for the prediction of spontaneous condensation. In this article, the main reason for the discrepancy between results obtained with CFX and measurement data is identified. It could be found that in CFX the temperature of already existing droplets is used for evaluating the fluid properties involved in the nucleation process. This is not in agreement with the isothermal classical nucleation theory, which is based on the assumption that clusters of critical radius are formed at vapour temperature. The most dominant parameter affected by this is the surface tension, the evaluation of which can be altered easily by the user. The influence of the correction is illustrated by means of standard Laval nozzle test cases, and a significant improvement of the results compared to measurement data can be observed.

The objective of this paper is to perform trim optimization on a 4250-TEU container ship based on the influence of trim on the resistance by using computational fluid dynamics (CFD) in conjunction with towing tank tests. First, the International Towing Tank Conference (ITTC) procedures were applied to uncertainty analysis of CFD and the CFD procedure was further verified and validated through three representative resistance curves obtained by the tests. Next, a series of resistance curves in different conditions with varied drafts and trims were obtained by the CFD computations for the model to provide data source to analyze the influence of the trim on the resistance. Results indicate that the variation of wave-making resistance due to trim dominates that of the total resistance. Finally, the resistance data for the model were converted to the engine power of the real ship. At each speed, the response surface of engine power with respect to drafts and trims was constructed and thus a trim optimization program was developed. The real ship operated under the instruction of the trim optimization program can save energy and reduce emissions significantly.

The 18th IUPAC International Conference on Chemical Thermodynamics (ICCT-2004), concurrent with the 12th National Conference on Chemical Thermodynamics and Thermal Analysis, was held 17-21 August 2004 at the Fragrant Hill Hotel, Beijing, China. Professor Haike Yan was Conference Chair, Prof. Zhiwu Yu was Conference Co-chair, and Prof. Xibai Qiu was Secretary. The 395 participants came from 40 countries.During the official opening ceremony, there was a presentation of the first Doctorate Awards to be given by the International Association of Chemical Thermodynamics, with sponsorship from Elsevier. The three recipients were Dr. Lin Chen, Tsinghua University, Beijing; Mr. Dirk Wandschneider, University of Rostock, Germany; and Mr. Weiguo Xu, Liaoning University, China. They each received a certificate plus a cash prize of USD 500.The conference began with the Rossini lecture, presented by Prof. Jean-Pierre E. Grolier on "Advanced experimental techniques in polymer thermodynamics". The conference program consisted of eight symposia and three workshops. In Symposium 1, Electrolyte and Nonelectrolyte Solution Thermodynamics, Prof. Emmerich Wilhelm gave the plenary lecture "The fascinating world of pure and mixed nonelectrolytes". There were invited lectures by Profs. Eckhard Vogel, Fumio Hirata, and Takayoshi Kimura. In Symposium 2, New Materials, Prof. C. Richard Catlow presented the plenary lecture "Computational approaches to the catalytic activation of carbon-hydrogen bonds", and invited lectures were given by Profs. Mary Anne White and Vladimir Durov. The plenary lecture in Symposium 3, Phase Equilibrium, Supercritical Fluids, and Separation Technologies, was given by Prof. Pablo Debenedetti on "Thermodynamics of supercooled and glassy water", with invited lectures from Profs. Cornelis Peters and Ding-Yu Peng. Symposium 4, Biological, Medical, Pharmaceutical, Agricultural, and Food Thermodynamics, had as its plenary lecturer Prof. Stephan Grzesiek, who spoke on "Biomolecular interactions in solutions". Professors Lee Hansen and Ichiro Hatta were the invited lecturers.Symposium 5 was on Colloid and Interface Science. Professor Bernard Cabane presented the plenary lecture "Solid-liquid separation", and there were invited lectures from Dr. Gerd Olofsson and Profs. Watson Loh and Xueqin An. The title of Symposium 6 was Non-equilibrium Thermodynamics, Statistical Thermodynamics, and Molecular Simulation. The plenary lecture "Non-equilibrium pattern formation" was presented by Prof. Qi Ouyang, with an invited lecture by Prof. Zhen-Gang Wang. Symposium 7 considered Thermochemistry and Molecular Energetics, with Prof. Michio Sorai, the plenary lecturer, speaking on "Entropy diagnosis for phase transitions occurring in functional materials". Professor Juliana Boerio-Goates gave the invited lecture. Symposium 8 was on Industrial Thermodynamics and Data Bases. Dr. Michael Fenkel gave the plenary lecture on "Global communications and expert systems in thermodynamics: Connecting property measurement and chemical process design". Invited lectures were given by Profs. Pertti Koukkari and Zhoulan Yin.There were three workshops. Prof. Kazuya Saito was invited lecturer for the Workshop on Thermodynamic Frontiers and Education. Professors Joan Brennecke and Andreas Heintz were invited lecturers for the Ionic Liquids Workshop. Professors Joon Won Park and Junko Morikawa gave invited lectures at the Workshop on New Experimental Techniques, including Nanotechnology.In addition, there were over 180 oral presentations, spread over the symposia and workshops, and about 280 poster presentations.The Rossini lecture and plenary lectures, with the exception of the paper by Prof. P. Debenetti where the field was recently reviewed [1,2], are published in this issue, together with the invited paper by Prof. Lee Hansen entitled "A thermodynamic law of adaptation of plants to environmental temperatures". Selected papers from individual symposia will be published in the Journal of Molecular Liquids (Symposium 1), Fluid Phase Equilibria (Symposia 3 and 6), the Journal of Chemical Thermodynamics (Symposia 1, 2, and 7), Thermochimica Acta (Symposium 4), or in the Journal of Chemical and Engineering Data (Workshop on Ionic Liquids).After the previous weeks when it had been very hot and humid, the temperature dropped and the weather was most pleasant for the conference. This change in weather, together with the attractive setting of the hotel, the excellent hospitality, which included a welcome reception, an evening of acrobatics entertainment, a conference banquet in the Summer Palace, and the high standard of the presentations, made this conference memorable. In addition, there was a full program of tours for accompanying persons. Our thanks are extended to the Conference Chair and Co-chair, and to all members of the local Organizing Committee, the International Advisory Committee, and the International Scientific Committee. We are most grateful to IUPAC, the International Association of Chemical Thermodynamics, the China Association for Science and Technology, the National Natural Science Foundation of China, and the Chinese Academy of Sciences for sponsoring the conference.Thermodynamics will continue to be an important area of research for many years to come, with a wide range of applications from chemical engineering to the biosciences. We look forward to the presentation and discussion of the results of further advances in chemical thermodynamics at the next ICCT, which will take place in Boulder, Colorado in 2006.1. P. G. Debenedetti. J. Phys.: Condens. Mater. 45, R1669-1726 (2003).2. P. G. Debenedetti and H. E. Stanley. Phys. Today 56, 40-46 (2003).J. H. DymondConference Editor

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 199243, “First Use of a Newly Developed High-Density Brine in an Oil-Based Screen Running Fluid in a Multilateral Extended-Reach Well: Fluid Qualification, Formation Damage Testing, and Field Application, Offshore Norway,” by Bjarne Salmelid, Morten Strand, and Duncan Clinch, Halliburton, et al., prepared for the 2020 SPE International Conference and Exhibition on Formation Damage Control, Lafayette, Louisiana, 19–21 February. The paper has not been peer reviewed. When used for running sand-control screens, low-solids, oil-based completion fluids (LSOBCF) maintain reservoir wellbore stability and integrity while minimizing the potential risks of losses, screen plugging, completion damage, and productivity impairment. Until now, using LSOBCF as a screen running fluid has been limited by fluid density. The complete paper discusses the design, qualification, and first deployment of an LSOBCF that incorporates a newly developed, high-density brine as the internal phase to extend the density limit. Field History This new field’s well forms part of the greater Alvheim area located in the central part of the North Sea, close to the UK sector. The formations discussed present excellent reservoir characteristics but also significant drilling challenges. The intruded country rock tends to have a high shear failure gradient (SFG) combined with a relatively low fracture gradient. Furthermore, because these reservoirs are exploited using long horizontal and multilateral wells, the drilling window is relatively narrow. For the presented case, the SFG was anticipated to be 1.39 specific gravity (SG) equivalent mud weight with an equivalent circulating density limit of 1.49 SG and stretch limit of 1.53 SG. The fluid density chosen to drill the well was 1.40 SG, and the density for the screen running fluid was planned to be 1.45 SG. Fluids Qualification Laboratory Testing Matrix. An extensive laboratory test matrix was initiated for the qualification of reservoir fluids. The reservoir fluid and drill-in fluid (RDIF) qualification is not detailed in the paper, only the LSOBCF and the novel brine used to prepare this fluid. The test matrix included tests such as rheology performance, long-term stability, production screen on 275 µm screen coupons, standard fluid-loss and filter-cake repair capabilities, reservoir fluid and RDIF compatibility tests, true crystallization temperature (TCT), and corrosion rate. The ultimate test was to check for formation and completion damage performance.

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 199268, “Upscaling Laboratory Formation Damage Laboratory Test Data,” by Michael Byrne, SPE, Lesmana Djayapertapa, and Ken Watson, SPE, Lloyd’s Register, et al., prepared for the 2020 SPE International Conference and Exhibition on Formation Damage Control, Lafayette, Louisiana, 19-21 February. The paper has not been peer reviewed. Through several case histories, the complete paper demonstrates applications of computational fluid dynamics (CFD) modeling to upscaling of laboratory-measured formation damage and reveals implications for well and completion design. The value of laboratory testing is quantified and interesting challenges to conventional wisdom are highlighted. Introduction Laboratory formation damage testing is often used to help select optimal drilling and completion fluids. Test procedures such as sand retention and return permeability represent an attempt to simulate near-wellbore conditions during well construction and production. To determine what degree of permeability impairment is allowable, further interpretation that cannot be provided using classical nodal analysis or reservoir simulation methods is required. The complete paper describes the evolution of, and potential for, more-comprehensive upscaling and outlines the importance of consideration of full well geometry when designing and interpreting coreflood tests for formation damage. CFD simulations provide a means to upscale suitable laboratory test data to predict effect on well performance. Methods CFD simulations use a relatively simple, steady-state, static damage model that takes endpoint data from laboratory core tests and translates the data into parameters that are used for input into well geometry. Although this method has its merits and is a considerable advance on previous, more-simplistic upscaling attempts, it does not necessarily present the full picture of damage evolution in the near-wellbore. A transient model of damage with data again derived from laboratory coreflood data could reveal more about well cleanup and progressive damage removal. Steady-State Modeling. No API recommended practice for return permeability testing exists. Laboratories have their own procedures that comply broadly with recommended procedures developed some time ago. Operators and consultants, too, have their own procedures, which they often ask laboratories to follow. Although no recommended practice exists, evaluation of drilling and completion fluids usually involves measurement of a base permeability and remeasurement of a return permeability—or several—after application of the test fluid or fluids. In many cases, the laboratory removes the external mud cake or trims a slice of the end of the plug to measure return permeability without mud cake (Fig. 1).

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 197560, “Enhanced Well Remedial Decisions From Exact Location of Fluid Movement Behind Casing Identification,” by Marcel Croon, SPE, Perry Huber, SPE, and Jacob Wright, SPE, Weatherford, SPE, prepared for the 2019 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 11-14 November. The paper has not been peer reviewed. Historically, acoustic wellbore monitoring is among the primary methods of detecting fluid movement behind the casing. However, analysis of the complex acoustic environment in the wellbore can be challenging. A standard hydrophone noise tool is unable to measure flow directions (vertical and horizontal) and cannot detect low flow, low-pressure sporadic events, or multiple sources. The complete paper discusses a geophone array, including four, three-component geophones deployed by wireline, that provides a solution for this problem by creating a 3D map of the acoustic environment. Introduction Well-integrity issues such as a poor cement bond can lead to undesirable fluid movements behind the casing, which could have negative effects with regard to health, safety, and the environment. A detailed understanding of annular fluid movement is critical in identifying potential source locations for wells with surface-casing vent-flow (SCVF) issues. Applicable scenarios include the following: Planned well-intervention activities for wells with multiple-source vent/flow situations Confirming the presence of flow (gas/oil/water) behind the casing Identifying areas with suspected crossflow between zones Integrity confirmation for gas storage caverns or zones Identifying unwanted flow for well-abandonment activities Well abandonment is bound by stringent regulations in some countries where the testing and repair of SCVF and gas-migration (GM) issues before final abandonment are required. An ex-ample is western Canada, where surface casing vents must be tested through a bubble test at minimum. This involves connecting a small container with 2.54 cm of water using fittings to the surface casing vent and monitoring for gas bubbles for 10 minutes. Often the flow rates are very low (less than 35 cu ft/d) with minimal pressure buildup. If bubbles are detected during the monitoring period, the well is deemed to have a positive vent flow. Consequently, the source of the vent flow must be identified by a survey as approved by the energy regulator, which could be conducted by means of acoustic logs, temperature logs, or gas- isotope analysis. Additionally, GM measurements must be conducted before final abandonment in specific areas within western Canada but are recommended for all wells. The complete paper details this process.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 20136, “Research and Application of Fracture Failure Control Technology for 13Cr Tubing in HP/HT Gas Wells,” by Lei Ma, Hongtao Liu, and Hailong Geng, PetroChina, et al., prepared for the 2020 International Petroleum Technology Conference, Dhahran, Saudi Arabia, 13-15 January. The paper has not been peer reviewed. Copyright 2020 International Petroleum Technology Conference. Reproduced by permission. Super 13Cr-110 tubing used in high-pressure, high-temperature (HP/HT) gas wells in the Tarim oil field has experienced numerous failures. After a series of investigations for root-cause analysis, the conclusion was that fracture of the tubing mechanistically is categorized as stress corrosion cracking (SCC) and is closely related to the application of phosphate-based completion fluid. Further tests indicated that Super 13Cr (S13Cr) tubing specimens experienced SCC with phosphate-based completion fluids contaminated with mud and oxygen, whereas formate-based completion fluid is compatible with S13Cr tubing. At present, 55 HP/HT gas wells in the field have used formate-based completion fluid with no tubing string fracture. Introduction Compared with the Gulf of Mexico, the North Sea, the South China Sea, the Qiongqiong Basin, and various Chinese oil and gas fields, the oil pipelines in the Tarim field are among the most difficult with regard to service conditions, which are characterized by extreme operating conditions such as high pump pressure and large displacement reform. Construction and high-yield alternating loads on tubing string and joint and a harsh, corrosive environment [chloride content greater than 80 000 mg/L, carbon dioxide (CO2) partial pressure greater than 1 MPa, and the presence of fresh and residual acid] pose significant challenges to the safe service of the tubing string. In the early stages of production, S13Cr oil pipe was selected as the completion string of the HP/HT gas well in the Kuqa mountain front, but in recent years, the S13Cr-110 pipe of the HP/HT gas well in the Tarim field has been continuously fractured. Failure accidents have caused serious economic losses. In the complete paper, through lateral comparison analysis of the failed tubing and indoor simulation experiments, the cause of the tubing fracture is discovered, solution measures are initiated, and good application results are achieved. Comparative Analysis of Oil-Pipe Failures Comparative Analysis of Fracture Macroscopic Morphology. When comparing the macroscopic topographic maps of oil-pipe failures seen in six studied wells, fracture locations of three wells are located in the coupling, while fracture locations of the other three wells are located on the body. In five wells (Wells A through E), the tubing fracture is neat, indicating brittle fracture with no plastic deformation. Well F, however, has a visible longitudinal crack on the surface of the tubing, and many burrs are visible at the fracture. Comparison and Analysis of Working Conditions of Failed Tubing. Through comparative analysis, it was determined that five of the six wells have under-gone acidification. The service shaft temperature, pressure, CO2 content, and formation water salinity of the failed wells differ, but, in five of the six wells, the tubing was exposed to a phosphate-based completion fluid.

The operation of hydrokinetic turbine depends on river flow and pressure head (∆H) which are of high potential in many parts of Nigeria. This study attempts the analysis of the potential of the area upstream of Ikere Gorge dam for hydrokinetic potential. Soil and Water Assessment Tool (SWAT) was used to determine the hydrological parameters of the sub-basins. Pearson Moment Correlation and linear regression methods were used to find the relationships between morphometric properties and the discharge parameters. Hydrological modeling and statistical computations were done to estimate the theoretical potential of the catchment. The result shows that River Oshe has 9.542 MW, which is the highest potential while River Konsun with 1.161 MW has the lowest potential Pearson Moment Correlation shows that there is strong positive relation of 0.7 between slope and pressure head (∆H) at 0.05 significant levels. The result of the multiple regression show that hydro-geomorphic factors explained 59.1% of the variance in the explanation of hydrokinetic power potential upstream of Ikere gorge dam. References Alaska Center for Energy and Power (ACEP) (2011). Hydrokinetic energy (In-River, Tidal and Ocean Current), Retrieved from http://energy-alaska.wikidot.com/ on April 20th, 2014 Aschenbrenner, F. (2008). Innovation on traditional waterwheels for renewable energy // Power electronics and motion Control conference, Portoroz, Slovenia, pp.1625 Bahleda, M., and Hosko, M. A. (2007). Assessment of water power potential and development Needs: Electric power research institute, California Bhattacharya, A.K., and Bolaji, G.A. (2012). Fluid Flow Interactions in Ogun River, International Journal of Research and Reviews in Applied Sciences, 2 (2): 22-23. Electric Power Research Institute, EPRI (2012). Fish passage through turbine: Application of convectional hydropower data to hydrokinetic technology Palo Alto, USA Energy Information Administration (2014). Retrieved on Dec. 20th, 2014 from www.eia.gov/electricity Epler, J. (2010). Tidal Resources characteristics from acoustics Doppler current profiler, An Unpublished M.Sc.Thesis, Department of Mechanical Engineering, University of Washington, USA Evan, M. (2012). Hydrokinetic Power: An Analysis of Its Performance and Potential in the Roza and Kittas Canals. An Unpublished M. Sc. Thesis, the Evergreen State College, USA Ifabiyi, I.P. and Wahab, S. (2017). Theoretical potential of hydrokinetic energy in the Upper Ogun and Upper Kaduna River basins, Nigeria. Journal of Sustainable Development in Africa, 19 (1): 242-256. Clarion University of Pennsylvania, Clarion, USA. ISSN: 1520-5509. Jsd-africa@clarion.edu Kosnik, L. (2008). The Potential of Water Power in the Fight against Global Warming in the USA, Energy policy, doi: 10.1016/ J. enpol. (05), 009. Kusakana, K., and Vermaak, H. J. (2013). Hydrokinetic Power Generation for Rural Electricity Supply: Case of South Africa. Renewable Energy, 1 (55): 467-73. Ladokun, L.L., Ajao, K.R., and Sule, B.F. (2013). Hydrokinetic Energy Conversion System: Pros -pects and Challenges in Nigerian Hydrological setting, Nigerian Journal of Technology, 3 (32): 538-549. Miller, V.B, Ramde, E.W., Grandoville, R.T., and Schaefer, L.A. (2010). Hydrokinetic Power for Energy Access in Rural Ghana, Renewable Energy International Journal, 1(36): 671-675. Mohibullah, M., Radzi, A. M., and Hakim, M.I.A. (2004). Basics Design Aspects of Micro Hydropower Plant and Its Potential Development in Malaysia // Power and Energy Conference, Kualar Lumpur, pp. 220-223. Neitsch, S.L, Arnold, J.G., Kiniry, J.R and Williams, J.R. (2009). Soil and Water Assessment Tool Theoretical Documentation Version 2009 Grassland, Soil and Water Research Laboratory-Agriculture Research Service, Blackland Research Center- Texas Agrilife Research., USA. Ofuani, A.I. (2013). Combating climate change through renewable energy legislation in Nigeria: Prospects and Challenges. Paper Presented at university of Ilorin/ UCC (Ghana) International Conference held at university of Ilorin. May 1st-4th 2011. Stephen, V.A, Paul, T.A., and Daniel, J.G. (2012). Survival and Behaviour of Fish interacting With Hydrokinetic Turbines, 9th ISE, Vienna, USA Vermaak, H.J., Kusakana, K., and Koko, S.P. (2013). Status of Micro-hydrokinetic River Technology in Rural Applications: A Review of literature: Renewable and sustainable energy reviews, 29(14): 625-633. Wahab, S., Ifabiyi, I.P. and Adeogun, A.G. (20017). SWAT analysis of Ikere Gorge Basin for Hydrokinetic power estimation in selected rural settlement of Oke Ogun, Nigeria. Ruhuna Journal of Science. 8(2):24-43 Ruhuna, Faculty of Science, University of Ruhuna, Sri Lanka. eISSN: 2536-8400. DOI: http//:doi.org/10.4038/rjs.v8il. Copyright (c) 2018 Geosfera Indonesia Journal and Department of Geography Education, University of Jember This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 19854, “Modeling and Prediction of Resistivity, Capillary Pressure, and Relative Permeability Using Artificial Neural Network,” by Mustafa Ba alawi, SPE, King Fahd University of Petroleum and Minerals; Salem Gharbi, SPE, Saudi Aramco; and Mohamed Mahmoud, King Fahd University of Petroleum and Minerals, prepared for the 2020 International Petroleum Technology Conference, Dhahran, Saudi Arabia, 13–15 January. The paper has not been peer reviewed. Copyright 2020 International Petroleum Technology Conference. Reproduced by permission. Capillary pressure and relative permeability are essential measurements that affect multiphase fluid flow in porous media directly. The processes of measuring these parameters, however, are both time-consuming and expensive. Artificial-intelligence methods have achieved promising results in modeling extremely complicated phenomena in the industry. In the complete paper, the authors generate a model by using an artificial-neural-network (ANN) technique to predict both capillary pressure and relative permeability from resistivity. Capillary Pressure and Resistivity Capillary pressure and resistivity are two of the most significant parameters governing fluid flow in oil and gas reservoirs. Capillary pressure, the pressure difference over the interface of two different immiscible fluids, traditionally is measured in the laboratory. The difficulty of its calculation is related to the challenges of maintaining reservoir conditions and the complexity of dealing with low-permeability and strong heterogeneous samples. Moreover, unless the core materials are both available and representative, a restricted number of core plugs will lead to inadequate reservoir description. On the other hand, resistivity can be obtained by either lab-oratory analysis or through typical and routine well-logging tools in real time. Both parameters have similar attributes, given their dependence on wetting-phase saturation. Despite many studies in the literature that are reviewed in the complete paper, improvement of capillary pressure and resistivity modeling remains an open research area. Artificial Intelligence in Petroleum Engineering In addition to labor and expense concerns, conventional methods to measure resistivity, capillary pressure, and relative permeability depend primarily, with the exception of resistivity from well logs, on the availability of core samples of the desired reservoir. The literature provides several attempts to model these parameters in order to avoid many of the requirements of measurement. However, the performance of many of these models is restricted by assumptions and constraints that require further processing. For example, the accuracy of prediction of capillary pressure from resistivity is highly dependent on the tested core permeability, which requires measuring it as well to achieve the full potentiality of the model.

The 12th International Symposium on Advanced Intelligent Systems (ISIS 2011) held at La Vie DfOr Resort, Suwon, Korea, on September 28 to October 1, 2011, featured presentations by researchers, engineers and practitioners on the latest accomplishments, innovations and applications in artificial intelligence, intelligent systems, and information technology. The 152 papers consisted of 110 regular papers, 39 organized session papers and 3 invited papers were contributed to the conference. The Program Committee requested ISIS 2011 reviewers to select papers for a special issue of the Journal of Advanced Computational Intelligence & Intelligent Informatics (JACIII), of which about 10 were accepted for publication in a twopart ISIS 2011 special issue, Vol.16, No.7, containing 5 papers. Part II will feature about 5 papers. A brief review of Part I covers 5 papers: First paper proposes a quantitative model for assessing the collision risk in maritime waterway traffic. The method proposes recent maritime traffic characteristics in time-variant CPA waterway environments and models a dynamic causation factor as a risk indicator. Second paper proposes multiagent query refinement realizing personalized query refinement by three strategies ? knowledge-based query expansion, user-device-based query and weighted query expansion strategy. These approaches determine the domain that the initial query belongs to and expand the query by comprehensively considering user interests. Third paper presents variable-step-size incremental conductance direct maximum power point tracking using fuzzy membership for a standalone photovoltaic system under rapidly changing irradiation. Fourth paper applies a natural actor-critic (NAC) and natural evolution strategies (NES) from natural-gradient-based machine learning to path-tracking control problems for autonomous vehicles. Fifth paper presents features for authenticating painting style, specifically that of Piet Mondrain. It demonstrates meaningful features using two supervised learning algorithms ? decision tree induction algorithm C4.5 and the feature generating machine (FGM) ? selecting important features in the course of learning. We thank the reviewers for their time and effort in making this special issue available so quickly. We are also grateful to the JACIII editorial office for invaluable assistance and advice in putting the issue together.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 203147, “Investigating Hole-Cleaning Fibers’ Mechanism To Improve Cutting Carrying Capacity and Comparing Their Effectiveness With Common Polymeric Pills,” by Mohammad Saeed Karimi Rad, Mojtaba Kalhor Mohammadi, SPE, and Kourosh Tahmasbi Nowtarki, International Drilling Fluids, prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed. Hole cleaning in deviated wells is more challenging than in vertical wells because of the boycott effect or the eccentricity of the drillpipe. Poor hole cleaning can result in problems such as borehole packoff or excessive equivalent circulating density. The complete paper investigates a specialized fibrous material (Fiber 1) for hole-cleaning characteristics. The primary goal is to identify significant mechanisms of hole-cleaning fibers and their merits compared with polymeric high-viscosity pills. Hole-Cleaning Indices Based on a review of the literature, most effective parameters regarding hole cleaning in different well types were investigated. These parameters can be classified into the following five categories: - Well design (e.g., hole angle, drillpipe eccentricity, well trajectory) - Drilling-fluid properties (e.g., gel strength, mud weight) - Formation properties (e.g., lithology, cutting specific gravity, cuttings size and shape) - Hydraulic optimizations (e.g., flow regime, nozzle size, number of nozzles) - Drilling practices (e.g., drillpipe rotation speed, wellbore tortuosity, bit type, rate of penetration, pump rate) In this research, rheological parameters and parameters of the Herschel-Bulkley rheological model are considered to be optimization inputs to increase hole-cleaning efficiency of commonly used pills in drilling operations. The complete paper offers a detailed discussion of both the importance of flow regime and the role of the Herschel-Bulkley rheological model in reaching a better prognosis of drilling-fluid behavior at low shear rates. The properties of the fibrous hole-cleaning agent used in the complete paper are provided in Table 1. Test Method Two series of tests were performed. The medium of the first series is drilling water, with the goal of evaluating the efficiency of Fiber 1 in fresh pills. The second series of tests was per-formed with a simple polymeric mud as a medium common in drilling operations. Formulations and rheological properties of both test series are provided in Tables 4 and 5 of the complete paper, respectively.

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 199260, “Filter Cake Breaker Evaluation for Water Injectors: Scale Up From Laboratory to Field Deployment,” by Pavithiran Chandran, SPE, Arunesh Kumar, SPE, and Iain Cameron, BP, et al., prepared for the 2020 SPE International Conference and Exhibition on Formation Damage Control, Lafayette, Louisiana, 19–21 February. The paper has not been peer reviewed. The complete paper describes the test procedures adopted for evaluating various filter cake breaker formulations and the work conducted to develop the systems to be ready for use in two North Sea fields (Field A and Field B). Water injection wells were planned to provide pressure support to oil producers in the two fields, and water-based drilling fluids were selected to drill the reservoir sections for both. The average permeability is 1000 md for Field A and 50–100 md for Field B. A laboratory study was commissioned to evaluate and optimize filter cake breaker systems for use in water injectors to efficiently remove external and internal filter cake to attain matrix injection without the need for backflow to clean the sandface. Introduction Field A was commissioned to drill 18 producers and seven water injectors from a semisubmersible drilling rig. Most of the injector wells are high-inclination, long openhole sections. Fluid density of 1.24–1.48 specific gravity (SG) (10.3–12.3 ppg) was required for wellbore stability. The Field B development plan included drilling 26 producers and 10 water injectors with an average injection rate target of 40,000 B/D of treated, produced water per well. Most wells are high-inclination to reduce the risk of direct fracture communication between wells. Injectivity indexes of 10–30 BWPD/psi were anticipated. The ability to include backflow/gas-lift capacity in the injector wells to assist cleanup was not included in the operational plan; therefore, direct injection was the preferred design standard. The injection interval in Field A features high-permeability (approximately 1000-md) zones; the Field B injection interval is considered a low-to-mid-permeability (approximately 100-md) zone. Injection of warm produced water into naturally occurring fractures in Field B injector wells yields poorer performance than when cooler fluids such as seawater are used. Higher downhole temperature and longer fluid residence time in the wellbore on Field B could increase the temperature of the injection fluid and thermally contract the natural fractures. Poor initial injectivity with produced water was identified as a potential risk on these wells, because this could lead to subsequent complications with seawater injection into these zones. Reservoir Drilling Fluid (RDF) Design and Selection Water-based RDF was chosen to drill the reservoir section of the water injectors on the basis of its ability to reduce operational complexity in terms of fluids preparation, displacement design, and screen running issues. RDF fluids typically contain a brine phase to achieve required density, xanthan polymer for viscosity, starch for filtration control, sized calcium carbonates for a bridging package, and specialized chemicals to address specific well challenges such as shale inhibitors and lubricants. Water-based RDF is more amenable than invert emulsion fluids to stimulation treatments for cleanup of filter cake and remediation of near-wellbore damage. However, water-based fluids can pose other operational issues such as increased torque and drag and potential for differential sticking, especially while drilling long horizontal wells, as was planned for both fields. A lubricant was included in the fluid used on Field B to manage torque-and-drag issues.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 19775, “Quantifying Separator-Oil Shrinkage,” by Mathias Lia Carlsen, SPE, and Curtis Hays Whitson, SPE, Whitson, prepared for the 2020 International Petroleum Technology Conference, Dhahran, Saudi Arabia, 13-15 January. The paper has not been peer reviewed. Copyright 2020 International Petroleum Technology Conference. Reproduced by permission. In tight unconventionals, oil and gas rates often are measured daily at separator conditions. Consequently, converting these rates reliably to volumes at standard conditions is necessary in cases where direct stock-tank measurements are not available. Because of changes in producing-wellstream compositions and separator conditions, the separator-oil shrinkage factor (SF) can change significantly over time. The complete paper presents a rigorous and consistent method to convert daily separator rates into stock-tank volumes. Recommendations for developing field-specific shrinkage correlations using field test data also are proposed. SF and Flash Factor (FF) Separator-Oil SF. Separator-oil SF is the fraction of metered separator oil rate that remains (or transforms into) stock-tank oil after further processing to standard conditions of 1 atm and 60°F. Put simply, the SF quantifies the decrease in oil volume from separator conditions to stock tank. The magnitude can range from less than 0.65 to 0.99. Separator-Oil FF. Separator-oil FF is the ratio of liberated gas from metered separator oil after further processing to standard conditions of 1 atm and 60°F. The FF accounts for the increase in gas volume from separator conditions to stock tank and explains why oil is shrinking (i.e., gas is coming out of the solution). The magnitude of the FF can range from 5 to 1,000 scf/STB. Total producing gas/oil ratio (GOR) can be calculated easily when SF and FF are known. An SF always is associated with an FF and is literally the solution GOR of the separator oil. Both SF and FF are a function of the top-side surface process and an associated wellstream composition. Surface Process. The surface process represents the number of topside separation stages and the associated separator pressure and temperature of each stage. In shale basins, two- and three-stage separation trains are common. The number of separation stages typically is fixed throughout the lifetime of a well. However, the separator temperature and pressure may vary significantly. Wellstream Composition. The well-stream composition quantifies the relative amounts of different components flowing out of a well at a given day. This measurement is typically expressed in mol%. Tight unconventional basins contain many kinds of in-situ reservoir fluid compositions from dry gas to black oils. The produced-wellstream compositions from these systems tend to change considerably with time because of producing flowing bottomhole pressures below the saturation pressure, as seen in the field example presented in Fig. 1. In the figure, the shut-in period after approximately 330 days results in a transient period with large compositional changes.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202996, “An Efficient Treatment Technique for Remediation of Phase-Trapping Damage in Tight Carbonate Gas Reservoirs,” by Rasoul Nazari Moghaddam, SPE, Marcel Van Doorn, and Auribel Dos Santos, SPE, Nouryon, prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed. Aqueous- and hydrocarbon-phase trapping are among the few formation-damage mechanisms capable of significant reduction in effective permeability (sometimes near 100%). In this study, a new chemical treatment is proposed for efficient remediation of water- or hydrocarbon-phase-trapping damage in low-permeability porous media. The method proposed here is cost-effective and experimentally proved to be efficient and long-lasting. Such a chemical treatment is recommended to alleviate gas flow in tight gas with aqueous-trapping-damaged zones or in gas condensate reservoirs with condensate-banking challenges. Introduction Remediation techniques for existing aqueous- or hydrocarbon-phase-trapping damage can be categorized into two approaches: bypassing the damaged region by direct penetration techniques and trapping-phase removal. In the former category, the damaged zone is bypassed by creation of high-conductance flow paths through hydraulic fracturing or acidizing. However, for tight and ultratight formations, conventional acidizing may not be feasible (mostly because of injectivity difficulties). In the second category, direct removal and indirect removal have been used, but usually are seen as short-term solutions. The fluid used in the proposed treatment is comprised of a nonacidic chelating agent. The treatment fluid can be injected safely into the damaged region, while a slow reaction rate allows it to penetrate deep into the formation. In the proposed treatment, the mechanism is the permanent enlargement of pore throats where the nonwetting phase has the most restriction (to overcome the capillary forces) to pass through. In fact, phase trapping or capillary trapping occurs inside the pore structure when viscous forces are not strong enough to overcome the capillary pressure. The experimental setup and method are detailed in the complete paper. Results and Discussion Treatment of Outcrop Samples: Lueder Carbonate. The performance of the proposed treatment fluid initially was investigated on two outcrop core samples from the Lueder carbonate formation. The first treatment was conducted on the Le1 core sample with an absolute permeability of 1.46 md. To establish trapped water in the core, 10 pore volumes (PV) of 5 wt% potassium chloride brine were injected followed by nitrogen (N2) gas displacement. Then, to achieve irreducible water saturation, N2 was injected at a rate of 2 cm3/min for at least 100 PVs until no further water was produced. Next, the effective gas permeability was measured while N2 was injected at approximately 0.2 cm3/min. The effective gas permeability was obtained as 0.042 md. The trapped water saturation was also calculated (from the core weight) as 77.7%. After all pretreatment measurements, the core was loaded into the core holder for the treatment. The treatment injections with preflush and post-flush were performed at 130°C. In this test, 0.5 PV of treatment fluid was injected.

Abstract— The solar energy is the most important type of energy. The parabolic dish solar collector (PDSC) is the best type among other solar collectors because it is always tracking the sun movement. The exergy and the energy performances of a PDS were analyzed experimentally and numerically. The effect of different coil geometries and different mass flow rates of heat transfer fluid (HTF) were investigated. The PDS has parabolic dish and receiver with diameter (1.5) m and (0.2) m respectively. Concentration ratio is 56.25. The parabolic polar dish was supported by a tracking system with two axes. The types of the copper absorber were used which are: (spiral –helical) coil (SHC) and spiral-conical coil (SCC). The results showed that the useful energy and thermal efficiency are varying with solar radiation variation. The useful energy varying between (480-765) W for (SHC), the thermal efficiency varying between (35.2-39.8) % for (SHC). Exergy efficiency varying between (6.9 –8.6) %. It was shown that the higher values of useful energy for (spiral – helical) absorber was 0.1L/min flow rate. REFERENCES 1. T. Taumoefolau , K. Lovegrove ," An Experimental Study of Natural Convection Heat Loss from a Solar Concentrator Cavity Receiver at Varying Orientation. ", Australian National University,, Canberra ACT 0200 AUSTRALIA.2002 2. S. PAITOONSURIKARN and K. LOVEGROVE," On the Study of Convection Loss from Open Cavity Receivers in Solar Paraboloidal Dish Applications ", Australian National University Canberra ACT 0200, AUSTRALIA, pp 154,155,2003 3. Soteris A. Kalogirou*,"Solar thermal collectors and applications", Higher Technical Institute, Progress in Energy and Combustion Science 30 (2004) 231–295, pp237, 240, 241, 2004 4. M. Prakash, S.B. Kedare, J.K. Nayak," Investigations on heat losses from a solar cavity receiver", Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India,2008. 5. Shiva Gorjian1, Barat Ghobadian1, Teymour Tavakkoli Hashjin1, and Ahmad Banak ,"Thermal performance of a Point-focus Solar Steam Generating System ", 21st Annual International Conference on Mechanical Engineering-ISME201 7-9 May, 2013, School of Mechanical Eng., K.N.Toosi University, Tehran, Iran ,1ISME2013-1195,2013 6. Kailash Karunakaran1 Hyacinth J Kennady2 ,"Thermal Analysis of Parabolic Dish Snow Melting Device " ,International Journal for Research in Technological Studies| Vol. 1, Issue 3, February 2014 | ISSN (online): 2348-1439,2014 7. Charles-Alexis Asselineau, Ehsan Abbasi, John Pye "Open cavity receiver geometry influence on radiative losses" Australian National University (ANU), Canberra, ACT 0200 Australia. Solar2014: The 52nd Annual Conference of the Australian Solar Council 2014 8. Vahid Madadi, Touraj Tavakoli and Amir Rahimi First and second thermodynamic law analyses applied to a solar dish collector" DOI 10.1515/jnet-2014-0023 | J. Non-Equilib. Thermodyn. 2014; 39 (4):183–197 9. Yaseen. H. Mahmood , Mayadah K h. Ghaffar " Design of Solar dish concentration by using MATLAB program and Calculation of geometrical concentration parameters and heat transfer" , University of Tikrit , Tikrit , Iraq, Tikrit Journal of Pure Science 20 (4) ISSN: 1813 – 1662, 2015. 10. Vanita Thakkar, Ankush Doshi, Akshaykumar Rana "Performance Analysis Methodology for Parabolic Dish Solar Concentrators for Process Heating Using Thermic Fluid IOSR", Journal of Mechanical and Civil Engineering (IOSR-JMCE) eISSN: 2278-1684,p-ISSN: 2320-334X, Volume 12, Issue 1 Ver. II (Jan- Feb. 2015), PP 101-114 11. Saša R. pavlovi, Evangelos A. bellos, Velimir P. Stefanovi, Christos Tzivanidis and Zoran M. Stamenkovi "Design, Simulation ,and Optimiztion Of A Solar Dish Collector with spiral coil absorber ", , Nis, Serbia, thermal SCIENCE, Vol. 20, No. 4, pp. 1387-1397 1387,2016 12. Flávia V. Barbosa, João L. Afonso, Filipe B. Rodrigues, and José C. F. Teixeir," Development of a solar concentrator with tracking system", University of Minho,Guimarães, 4800-058, Portugal2016 13. O. López, A. Arenas, and A. Baños"Convective Heat Loss Analysis of a Cavity Receiver for a Solar Concentrator" International Conference on Renewable Energies and Power Quality (ICREPQ’17)Malaga (Spain), 4th to 6th April, 2017 ,ISSN 2172-038 X, No.15 April 2017 RE&PQJ, Vol.1, No.15, April 2017 14. D.R.Rajendran,E.GanapathySundaram,P.Jawahar "Experimental Studies on the Thermal Performance of a Parabolic Dish Solar Receiver with the Heat Transfer Fluids Sic water Nano Fluid and Water", Journal of Thermal Science Vol.26, 15. Muhammad Shoaib, Muhammad , Jameel Kabbir Ali ,Muhammad Usman1, Abdul Hannan " Analysis of thermal performance of parabolic dish collectors having different reflective" ,NFC institute of engineering &fertilizer research ,2018 . 16. Sasa PAVLOVIC, Evangelos BELLOS, Velimir STEFANOVIC ,Christos TZIVANIDIS " EXPERIMENTAL AND NUMERICAL INVESTIGATION OF A SOLAR DISH COLLECTOR WITH SPIRAL ABSORBER" A CTA TECHNICA CORVINIENSIS – Bulletin of Engineering Tome XI [2018] .

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202683, “Marrying the Static and Dynamic Worlds: Enhancing Saturation and Permeability Interpretation Using a Combination of Multifrequency Dielectric, Nuclear Magnetic Resonance, and Wireline Formation Testers,” by Hassan Mostafa, Ghassan Al-Jefri, SPE, and Tania Felix Menchaca, SPE, ADNOC, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed. Accurate water saturation evaluation and permeability profiling are crucial factors in determining volumetrics and productivity of multiple, stacked carbonate reservoirs offshore Abu Dhabi and derisking reservoir management. The case study presented in the complete paper illustrates how the integration of static measurements, such as dielectric dispersion and nuclear magnetic resonance (NMR) with dynamic measurements improves understanding of reservoir properties and supports more-accurate reservoir evaluation. Sampling and downhole fluid analysis (DFA) performed by wireline formation tester (WFT) identifies the fluid and rock properties in various flow units. Field Background and Challenges Optimal field development requires accurate estimations of water saturation and permeability. In this greenfield, the hydrocarbon is generally oil (medium to light) with very low asphaltene content. Overall, the reservoir quality is controlled by a combination of depositional environment, sequence stratigraphy, and diagenesis. Some reservoirs have good porosity, but reconciliation of log-based water saturation results with well-test results has been an issue. The objective in this case study was to drill a pilot hole for data gathering in a poorly characterized field location. Phase I included drilling a hole with a 55° deviation to cover all reservoirs for data gathering only, with the openhole reservoir section then being plugged and abandoned. Phase II of the plan was to sidetrack and complete the well as dual water-injector boreholes. In the reservoir section of the pilot borehole, a variety of logs was acquired for evaluation, including both logging-while-drilling and wireline measurements. While drilling, triple- combination data were acquired, consisting of gamma ray, resistivity, and nuclear logs (density neutron) along with resistivity images. The wireline-logging program was carried out in two stages to avoid differential sticking. In the first stage, the WFT was used to acquire 10 pressure points, seven points in the first reservoir and three points in the second. Two DFA stations were also recorded in Zone 1 to confirm whether the oil/water contact was deeper than expected. Logging was conducted using a high-tension wireline cable, which facilitates quicker accessibility to the openhole sections. In the second stage, multiple wireline runs were performed for the formation evaluation of the complete section, followed by the WFT pressure and fluid-sampling run on the drillpipe conveyance. Another critical challenge was to obtain accurate water saturations in the heterogeneous, minor, thin reservoirs, which are bounded by dense layers above and below and cause shoulder-bed effects. The third challenge in this well was to obtain an accurate, continuous, and representative permeability profile for the multiple reservoirs. WFT mini-drillstem test (DST) stations along with NMR logs were used to address this important requirement.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 199561, “Validation of Transient Annular Pressure Buildup (APB) Model Predictions With Field Measurements in an Offshore Well and Characterization of Uncertainty Bounds,” by Rahul Pai, Anamika Gupta, and Udaya B. Sathuvalli, Blade Energy Partners, et al., prepared for the 2020 IADC/SPE International Drilling Conference and Exhibition, Galveston, Texas, 3-5 March. The paper has not been peer reviewed. The average geothermal gradient in the subject deepwater field in Nigeria is 4.37°C/100 m, nearly twice the gradient in most fields. As a result, the magnitude of the expected annular pressure buildup (APB) during steady-state production is large enough to threaten well integrity. Therefore, an insulating packer fluid (IPF) was used in Annulus A to reduce heat transfer to the outer annuli and to regulate the APB within acceptable values. The complete paper reports the results of a study that compares the temperature and pressure measurements from these wells with model predictions. Introduction Though APB has been studied by well designers for decades, the use of downhole measurements to study APB has been somewhat limited. Previous uses of downhole instrumentation to study APB phenomena principally have centered on monitoring the magnitude of the APB and managing the risk. None, as far as the authors are aware, use the results gathered from downhole measurements to verify the results of the models that routinely are used in the design of the wellbore tubulars and APB-mitigation technologies. Notwithstanding the wealth of literature on the subject of APB, several crucial and fundamental questions remain unanswered. Chief among these are: What is the accuracy of thermal-model temperature predictions during various well operations? How do temperature uncertainties influence APB predictions? When APB magnitudes are large enough to require installation of APB mitigation devices? How do the mitigation devices perform over the life of the well? The complete paper seeks to address these questions through an examination of downhole pressure and temperature measurements and a parallel analysis of model predictions. Furthermore, field data and model predictions are juxtaposed, sources of uncertainties in the measurement data and model inputs are considered, and overall uncertainties in the APB predictions (i.e., model estimates) are characterized.

Wind speed is the principal climatic element that drives the Marmaton season in West African sub region. It drives the season by conveying huge amount of dust across the Northeastern Nigeria. The presence of dust in the atmosphere brought by the Northeast trade winds during the Harmattan season plays a vital role in absorbing and scattering solar radiation. The study examines the spatial and temporal variations of wind speed in Northeastern Nigeria during the Harmattan season with the sole aim of ascertaining its variability, patterns and trends from1984 to 2014. Descriptive and statistics such as mean, standard deviation, coefficient of variation, and time series analysis with ArcGIS 10.3 was used in examine the temporal and spatial variations of wind speed from 1984–2014 in six synoptic stations of Northeastern Nigeria. The findings show that wind speed varied both temporally and spatially in the last three decades. The pattern of variations in the six synoptic stations shows rising trends within the study years. It was also found that latitude playing a crucial role in determining the speed of the wind in the study area and as the speed of the wind increases with increasing latitude. Keywords: Wind speed, Harmattan, Season, Northeast, Variation and ITD. References Adaramola,M.S.andOyewola,O. M. (2011). Wind Speed Distribution and Characteristics in Nigeria. Asian Research Publishing Network (ARPN). Journal of Engineering and Applied Sciences.ISSN 1819-6608.www.arpnjournals.com Amadi, S. O., Udo, S. O. and Ewona, I. O. (2014). Trends in Monthly Mean Minimum and Maximum Temperature Data over Nigeria for the Period 1950-2012. International Research Journal of Pure and Applied Physics, 2(4), 1-27. Ayoade, J.O. (2004). Introduction to Climatology for the Tropics.2nd ed. Spectrum Books Limitted, Spectrum House Ring Road Ibadan, Nigeria. Balarabe, M., Abdallah, K., and Nawawi, M. (2015). Long- Term Trend and Seasonal Variability of Horizontal Visibility in Nigerian Troposphere.Journal of Atmosphere 6:1462-1486; doi:10.3390/atmos6101462. Dahuwa, D., Promise, K. U., Umar, W., Bello, I. and Mohammed, R. (2018). Analysis of Wind Speed And Frequency InAzare North eastern Part of Nigeria. IOSR Journal of Applied Physics (IOSR-JAP) e-ISSN: 2278-4861.Volume 10, Issue 1 Ver. I. PP 09-17 www.iosrjournals.org DOI: 10.9790/4861-1001010917 www.iosrjournals.org Danlami, D., Gwari, M., Suleiman, S., and Bara, A. (2018). Temporal and Spatial variations of Groung Surface visibility during Harmattan Season in North-Eastern Nigeria.Ceylon Journal Science, 47(4), 337 – 346. DOI: http://doi.org/10.4038/cjs.v47i4.7551. Danlami, D. (2017). Spatio-Temporal Variations of Harmattan Season in Northeastern Nigeria.M.Sc. Dissertation (Not published) Submitted to the Department of Geography, Bayero University, Kano, Nigeria. De Longueville, F., Hountondji, Y. C., Henry, S. and Ozer, P. (2010). What do we Know about the Effects of Desert Dust on Air Quality and Human Health in West Africa compared to other regions? Journal: Science of Total Environment Fagbenle, R.L., Fasade, A.O., Amuludun A.K. andLala,P.O.( 1980). Wind power potentials of Nigeria. 12th Biennial conference of the West African Science Association, University of Ife, Nigeria. Getis, A., Getis, J., Bjelland, M. and Fellmann, J.D. (2011).Introduction to Geography. 13thed. The McGraw-Hill Companies, Inc., 1221 Avenue of the Americas, NY10020. Karabulut, M., Demirci, A. and Kora, F. (2012). Analysis of spatially distributed annual, seasonal and monthly temperatures in Istanbul from 1975 to 2006.World Applied Sciences Journal, 12(10), 1662-1675 Ojosu, J.O. and Salawu, R.I. (1990).An evaluation of wind energy potential as a power generation source in Nigeria.Solar & Wind Technology.ELSEVIER.Volume 7, Issue 6, 1990, Pages 663-673 Schwanghart, W. and Schutt, B. (2007). Meteorological causes of Harmattan dust in West Africa. Journal of Science Direct Geomorphology. Shuman, M. (2007) Evaluation of five GIS basedInterpolation techniques for estimating the Radonconcentration for unmeasured zip codes in thestate of Ohio, Master of Science Degree in Civil Engineering, University of Toledo, 28-29 Pp. Waewsak, J., Chancham, C., Landry, M. and Gagnon, Y (2011).An Analysis of Wind Speed Distribution at Thasala, Nakhon Si Thammarat, Thailand.Journal of Sustainable Energy & Environment 2 pp 51-55 Willmott, C., Robeson, S. and Philpot, W. (1985). Small- scale climate maps: A sensitivity analysisof some common assumptions associated withgrid-point interpolation and contouring. American Cartographer 12(1):5-16. Copyright (c) 2019 Geosfera Indonesia Journal and Department of Geography Education, University of Jember This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 199654, “Simplifying Well Abandonments Using Shale as a Barrier,” by Eric van Oort, SPE, and Maria Juenger, The University of Texas at Austin, and Munir Aldin, SPE, Metarock Laboratories, et al., prepared for the 2020 IADC/SPE International Drilling Conference and Exhibition, Galveston, Texas, 3-5 March. The paper has not been peer reviewed. The complete paper presents the results of an investigation into the creep behavior of North Sea shales and their ability to form effective annular barriers. The large-scale laboratory results show that Lark-Horda shales will form competent low-permeability annular barriers when left uncemented, as confirmed using pressure-pulse-decay measurements. Experimental conditions were found to influence the rate of barrier formation. Higher effective stress, higher temperature, and beneficial manipulation of annular fluid chemistry all have a significant effect. Introduction An alternative to traditional plug-and-abandonment techniques presented it-self more than a decade ago, with observations that formations such as mobile salts and shales could creep into uncemented annular spaces and form competent annular barriers that could be identified on sonic and ultrasonic bond logs and verified using pressure testing. Shale particularly has the necessary characteristics that several guidelines require of a good barrier, being largely impermeable, nonshrinking, ductile, and resistant to chemicals and substances, all of which help provide long-term integrity. Shales that appeared to be particularly well-suited to beneficial annular creep behavior were characterized by low strength and high ductility, high clay content with relatively high smectite content, low levels of quartz and carbonate cementation, relatively high porosity and low compressional wave velocity, and a tendency to yield wellbore instability problems while being drilled. Mechanisms other than creep were considered for the annular blockage behavior observed, but the mounting body of evidence indicates that the predominant mechanism is indeed creep (i.e., the viscoplastic behavior of argillaceous rocks). In the laboratory and field work published to date, stimulation of shale barriers through accelerated creep by pressure and temperature manipulation has received the most attention. The authors investigate barrier activation not only by temperature and pressure activation but also by chemical activation, because it offers practical advantages and reduces risks associated with temperature and pressure activation. Temperature has a significant effect on the viscoplastic behavior of shale, but heating a long shale section (with a minimum barrier length of 50 m) through casing with an effective downhole heater presents considerable practical challenges. Pressure reduction in the annulus through reduction of the hydrostatic head in the wellbore brings with it well-control concerns, particularly when no functional annular barrier is in place. By contrast, circulating a chemical solution in place in an annular space through casing perforations with a workstring and packer arrangement is relatively straightforward and is routine when practicing the perforate, wash, and cement technique in the field.

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 203086, “First Successful Fishbone Stimulation Completion in Onshore Oil Field in the United Arab Emirates,” by Fernando Quintero, Noor Talib, and Alvaro Jimenez, SPE, ADNOC, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually from 9-12 November. The paper has not been peer reviewed. The complete paper describes the operator’s first implementation of fishbone stimulation technology. A multidisciplinary team analyzed the operational procedures, conducted risk assessments and logistical studies, and established contingency plans, technical requirements, and technical limitations. The deployment of the equipment and the production results were a success, overcoming hazard risks and uncertainties and closing gaps from previous, partially effective applications. According to the authors, fishbone stimulation technology will help increase productivity in a well too risky to be hydraulically fractured and beyond the reach of coiled tubing. Background As the industry seeks dynamic changes and novel ideas to increase the productivity of tight, thin reservoirs, fisbone stimulation represents a lower-risk and -cost solution to ensure deep connectivity with the reservoir in situations in which traditional conventional stimulation practices have reached their potential boundaries without achieving crude recovery objectives. The project described in the complete paper is part of a series of field-development projects in United Arab Emirates onshore fields to exceed expectations of the committed production targets. This trial has taken the form of a pilot test for implementing fishbone stimulation for a short duration in other onshore fields. The new approach has already enhanced production up to three times and has provided wellhead pressure support. While this marks a successful beginning, more field trials will be needed to implement wider use of this technology. Fishbone completion stimulation technology is based on the use of subs that are installed in uncemented liner in which each sub features four small-diameter, high-strength tubes called needles (Fig. 1) that can be extended up to 40 ft in length by bullheading acid (Fig. 2). The objective of the technology is to increase well productivity and injectivity by the needles by connecting natural fractures and vertical layers and increasing reservoir contact and effective well-bore radius. To address the deployment challenge, a risk assessment was under taken with the active participation of a multidisciplinary team, including members from the operator (drilling and asset team) and the service company, to ensure that all required precaution inputs were considered. The risk assessment was conducted by identifying the situations that could threaten the deployment and full extension of the needle, a critical aspect of the job. The complete paper describes primary factors such as the following: - Sub-assembly preparation - Running liner to total depth and setting liner hanger - Mixing and handling hydrochloric acid (HCl) - Pumping the acid job - Fluid losses after the acid job - Cleanup runs with fishbasket cutting assembly

Abstract. 1. The conference The third conference on "Nonlinear VAriability in Geophysics: scaling and multifractal processes" (NVAG 3) was held in Cargese, Corsica, Sept. 10-17, 1993. NVAG3 was joint American Geophysical Union Chapman and European Geophysical Society Richardson Memorial conference, the first specialist conference jointly sponsored by the two organizations. It followed NVAG1 (Montreal, Aug. 1986), NVAG2 (Paris, June 1988; Schertzer and Lovejoy, 1991), five consecutive annual sessions at EGS general assemblies and two consecutive spring AGU meeting sessions. As with the other conferences and workshops mentioned above, the aim was to develop confrontation between theories and experiments on scaling/multifractal behaviour of geophysical fields. Subjects covered included climate, clouds, earthquakes, atmospheric and ocean dynamics, tectonics, precipitation, hydrology, the solar cycle and volcanoes. Areas of focus included new methods of data analysis (especially those used for the reliable estimation of multifractal and scaling exponents), as well as their application to rapidly growing data bases from in situ networks and remote sensing. The corresponding modelling, prediction and estimation techniques were also emphasized as were the current debates about stochastic and deterministic dynamics, fractal geometry and multifractals, self-organized criticality and multifractal fields, each of which was the subject of a specific general discussion. The conference started with a one day short course of multifractals featuring four lectures on a) Fundamentals of multifractals: dimension, codimensions, codimension formalism, b) Multifractal estimation techniques: (PDMS, DTM), c) Numerical simulations, Generalized Scale Invariance analysis, d) Advanced multifractals, singular statistics, phase transitions, self-organized criticality and Lie cascades (given by D. Schertzer and S. Lovejoy, detailed course notes were sent to participants shortly after the conference). This was followed by five days with 8 oral sessions and one poster session. Overall, there were 65 papers involving 74 authors. In general, the main topics covered are reflected in this special issue: geophysical turbulence, clouds and climate, hydrology and solid earth geophysics. In addition to AGU and EGS, the conference was supported by the International Science Foundation, the Centre Nationale de Recherche Scientifique, Meteo-France, the Department of Energy (US), the Commission of European Communities (DG XII), the Comite National Francais pour le Programme Hydrologique International, the Ministere de l'Enseignement Superieur et de la Recherche (France). We thank P. Hubert, Y. Kagan, Ph. Ladoy, A. Lazarev, S.S. Moiseev, R. Pierrehumbert, F. Schmitt and Y. Tessier, for help with the organization of the conference. However special thanks goes to A. Richter and the EGS office, B. Weaver and the AGU without whom this would have been impossible. We also thank the Institut d' Etudes Scientifiques de Cargese whose beautiful site was much appreciated, as well as the Bar des Amis whose ambiance stimulated so many discussions. 2. Tribute to L.F. Richardson With NVAG3, the European geophysical community paid tribute to Lewis Fry Richardson (1881-1953) on the 40th anniversary of his death. Richardson was one of the founding fathers of the idea of scaling and fractality, and his life reflects the European geophysical community and its history in many ways. Although many of Richardson's numerous, outstanding scientific contributions to geophysics have been recognized, perhaps his main contribution concerning the importance of scaling and cascades has still not received the attention it deserves. Richardson was the first not only to suggest numerical integration of the equations of motion of the atmosphere, but also to attempt to do so by hand, during the First World War. This work, as well as a presentation of a broad vision of future developments in the field, appeared in his famous, pioneering book "Weather prediction by numerical processes" (1922). As a consequence of his atmospheric studies, the nondimensional number associated with fluid convective stability has been called the "Richardson number". In addition, his book presents a study of the limitations of numerical integration of these equations, it was in this book that - through a celebrated poem - that the suggestion that turbulent cascades were the fundamental driving mechanism of the atmosphere was first made. In these cascades, large eddies break up into smaller eddies in a manner which involves no characteristic scales, all the way from the planetary scale down to the viscous scale. This led to the Richardson law of turbulent diffusion (1926) and tot he suggestion that particles trajectories might not be describable by smooth curves, but that such trajectories might instead require highly convoluted curves such as the Peano or Weierstrass (fractal) curves for their description. As a founder of the cascade and scaling theories of atmospheric dynamics, he more or less anticipated the Kolmogorov law (1941). He also used scaling ideas to invent the "Richardson dividers method" of successively increasing the resolution of fractal curves and tested out the method on geographical boundaries (as part of his wartime studies). In the latter work he anticipated recent efforts to study scale invariance in rivers and topography. His complex life typifies some of the hardships that the European scientific community has had to face. His educational career is unusual: he received a B.A. degree in physics, mathematics, chemistry, biology and zoology at Cambridge University, and he finally obtained his Ph.D. in mathematical psychology at the age of 47 from the University of London. As a conscientious objector he was compelled to quit the United Kingdom Meteorological Office in 1920 when the latter was militarized by integration into the Air Ministry. He subsequently became the head of a physics department and the principal of a college. In 1940, he retired to do research on war, which was published posthumously in book form (Richardson, 1963). This latter work is testimony to the trauma caused by the two World Wars and which led some scientists including Richardson to use their skills in rational attempts to eradicate the source of conflict. Unfortunately, this remains an open field of research. 3. The contributions in this special issue Perhaps the area of geophysics where scaling ideas have the longest history, and where they have made the largest impact in the last few years, is turbulence. The paper by Tsinober is an example where geometric fractal ideas are used to deduce corrections to standard dimensional analysis results for turbulence. Based on local spontaneous breaking of isotropy of turbulent flows, the fractal notion is used in order to deduce diffusion laws (anomalous with respect to the Richardson law). It is argued that his law is ubiquitous from the atmospheric boundary layer to the stratosphere. The asymptotic intermittency exponent i hypothesized to be not only finite but to be determined by the angular momentum flux. Schmitt et al., Chigirinskaya et al. and Lazarev et al. apply statistical multifractal notions to atmospheric turbulence. In the former, the formal analogy between multifractals and thermodynamics is exploited, in particular to confirm theoretical predictions that sample-size dependent multifractal phase transitions occur. While this quantitatively explains the behavior of the most extreme turbulent events, it suggests that - contrary to the type of multifractals most commonly discussed in the literature which are bounded - more violent (unbounded) multifractals are indeed present in the atmospheric wind field. Chigirinskaya et al. use a tropical rather than mid-latitude set to study the extreme fluctuations form yet another angle: That of coherent structures, which, in the multifractal framework, are identified with singularities of various orders. The existence of a critical order of singularity which distinguishes violent "self-organized critical structures" was theoretically predicted ten years ago; here it is directly estimated. The second of this two part series (Lazarev et al.) investigates yet another aspect of tropical atmospheric dynamics: the strong multiscaling anisotropy. Beyond the determination of universal multifractal indices and critical singularities in the vertical, this enables a comparison to be made with Chigirinskaya et al.'s horizontal results, requiring an extension of the unified scaling model of atmospheric dynamics. Other approaches to the problem of geophysical turbulence are followed in the papers by Pavlos et al., Vassiliadis et al., Voros et al. All of them share a common assumption that a very small number of degrees of freedom (deterministic chaos) might be sufficient for characterizing/modelling the systems under consideration. Pavlos et al. consider the magnetospheric response to solar wind, showing that scaling occurs both in real space (using spectra), and also in phase space; the latter being characterized by a correlation dimension. The paper by Vassiliadis et al. follows on directly by investigating the phase space properties of power-law filtered and rectified gaussian noise; the results further quantify how low phase space correlation dimensions can occur even with very large number of degrees of freedom (stochastic) processes. Voros et al. analyze time series of geomagnetic storms and magnetosphere pulsations, also estimating their correlation dimensions and Lyapounov exponents taking special care of the stability of the estimates. They discriminate low dimensional events from others, which are for instance attributed to incoherent waves. While clouds and climate were the subject of several talks at the conference (including several contributions on multifractal clouds), Cahalan's contribution is the only one in this special issue. Addressing the fundamental problem of the relationship of horizontal cloud heterogeneity and the related radiation fields, he first summarizes some recent numerical results showing that even for comparatively thin clouds that fractal heterogeneity will significantly reduce the albedo. The model used for the distribution of cloud liquid water is the monofractal "bounded cascade" model, whose properties are also outlined. The paper by Falkovich addresses another problem concerning the general circulation: the nonlinear interaction of waves. By assuming the existence of a peak (i.e. scale break) at the inertial oscillation frequency, it is argued that due to remarkable cancellations, the interactions between long inertio-gravity waves and Rossby waves are anomalously weak, producing a "wave condensate" of large amplitude so that wave breaking with front creation can occur. Kagan et al., Eneva and Hooge et al. consider fractal and multifractal behaviour in seismic events. Eneva estimates multifractal exponents of the density of micro-earthquakes induced by mining activity. The effects of sample limitations are discussed, especially in order to distinguish between genuine from spurious multifractal behaviour. With the help of an analysis of the CALNET catalogue, Hooge et al. points out, that the origin of the celebrated Gutenberg-Richter law could be related to a non-classical Self-Organized Criticality generated by a first order phase transition in a multifractal earthquake process. They also analyze multifractal seismic fields which are obtained by raising earthquake amplitudes to various powers and summing them on a grid. In contrast, Kagan, analyzing several earthquake catalogues discussed the various laws associated with earthquakes. Giving theoretical and empirical arguments, he proposes an additive (monofractal) model of earthquake stress, emphasizing the relevance of (asymmetric) stable Cauchy probability distributions to describe earthquake stress distributions. This would yield a linear model for self-organized critical earthquakes. References: Kolmogorov, A.N.: Local structure of turbulence in an incompressible liquid for very large Reynolds number, Proc. Acad. Sci. URSS Geochem. Sect., 30, 299-303, 1941. Perrin, J.: Les Atomes, NRF-Gallimard, Paris, 1913. Richardson, L.F.: Weather prediction by numerical process. Cambridge Univ. Press 1922 (republished by Dover, 1965). Richardson, L.F.: Atmospheric diffusion on a distance neighbour graph. Proc. Roy. of London A110, 709-737, 1923. Richardson, L.F.: The problem of contiguity: an appendix of deadly quarrels. General Systems Yearbook, 6, 139-187, 1963. Schertzer, D., Lovejoy, S.: Nonlinear Variability in Geophysics, Kluwer, 252 pp, 1991.

AbstractMarine fouling on the hull of surface vessels is a topic of increasing importance in the maritime field for its environmental and financial impacts. Recent research developments have introduced mathematical models dealing with the frictional resistance associated with fouling. Herein, an implementation of these models in a numerical code to predict the added resistance of ships due to biofouling and associated costs is presented. The code is designed to account for the singularity of each context based on at least one observation of the fouling condition. Through a hypothetical yet realistic scenario, it is shown that it enables proactive management by indicating when fouling is no longer tolerable from a financial standpoint. <def-list>Nomenclature<def-item><term>B</term><def>log-law intercept (=5.0)</def></def-item><def-item><term>CA</term><def>correlation allowance</def></def-item><def-item><term>CC</term><def>cleaning cost</def></def-item><def-item><term>CF</term><def>frictional resistance coefficient</def></def-item><def-item><term>Cf</term><def>local skin friction coefficient</def></def-item><def-item><term>Cfuel</term><def>cumulative added fuel cost</def></def-item><def-item><term>Cfuel</term><def>fuel price</def></def-item><def-item><term>CR</term><def>residuary resistance coefficient</def></def-item><def-item><term>CT</term><def>total resistance coefficient</def></def-item><def-item><term>CV</term><def>viscous resistance coefficient</def></def-item><def-item><term>FC</term><def>cumulative extra fuel consumption</def></def-item><def-item><term>Fn</term><def>Froude number</def></def-item><def-item><term>g</term><def>acceleration due to gravity</def></def-item><def-item><term>KF</term><def>cumulative added power</def></def-item><def-item><term>K</term><def>roughness height</def></def-item><def-item><term>Ks</term><def>sand roughness height</def></def-item><def-item><term>1 + K1</term><def>form factor</def></def-item><def-item><term>L</term><def>length of ship</def></def-item><def-item><term>PB</term><def>brake power or engine power</def></def-item><def-item><term>PE</term><def>effective power</def></def-item><def-item><term>Ra</term><def>centerline averaged roughness height</def></def-item><def-item><term>Rn</term><def>Reynolds number</def></def-item><def-item><term>RT</term><def>total resistance</def></def-item><def-item><term>Rt</term><def>maximum peak to trough roughness height</def></def-item><def-item><term>Rt50</term><def>maximum peak to trough roughness height over a length of 50 mm</def></def-item><def-item><term>S</term><def>wetted surface area</def></def-item><def-item><term>U</term><def>velocity</def></def-item><def-item><term>Ue</term><def>freestream velocity</def></def-item><def-item><term>U τ</term><def>friction velocity = <inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mimetype="image" xlink:href="MTS51201e16.gif"/></def></def-item><def-item><term>T</term><def>threshold time</def></def-item><def-item><term>Tsea</term><def>time spent at sea</def></def-item><def-item><term>ΔU+</term><def>roughness function</def></def-item><def-item><term>δ</term><def>boundary layer thickness</def></def-item><def-item><term>ρ</term><def>density of fluid</def></def-item><def-item><term>κ</term><def>Von Karman constant (=0.41)</def></def-item><def-item><term>η</term><def>efficiency of the propulsion system</def></def-item><def-item><term>μ</term><def>dynamic viscosity</def></def-item><def-item><term>υ</term><def>kinematic viscosity</def></def-item><def-item><term>τ</term><def>shear stress</def></def-item></def-list><def-list>Subscripts<def-item><term>clean</term><def>clean, newly coated</def></def-item><def-item><term>r</term><def>rough</def></def-item><def-item><term>sm</term><def>smooth</def></def-item></def-list><def-list>Superscript<def-item><term>+</term><def>normalized variable</def></def-item></def-list><def-list>Abbreviations<def-item><term>ATTC</term><def>American Towing Tank Conference</def></def-item><def-item><term>BMT</term><def>British Maritime Technology</def></def-item><def-item><term>IFO</term><def>intermediate fuel oil</def></def-item><def-item><term>IMO</term><def>International Maritime Organization</def></def-item><def-item><term>IPPIC</term><def>International Paint and Printing Ink Council</def></def-item><def-item><term>ITTC</term><def>International Towing Tank Conference</def></def-item><def-item><term>MEPC</term><def>Marine Environment Protection Committee</def></def-item><def-item><term>NSTM</term><def>Naval Ships' Technical Manual</def></def-item><def-item><term>SFOC</term><def>specific fuel oil consumption of engine</def></def-item></def-list>

Abstract Near-wall modeling is one of the most challenging aspects of computational fluid dynamic computations. In fact, integration-to-the-wall with low-Reynolds approach strongly affects accuracy of results, but strongly increases the computational resources required by the simulation. A compromise between accuracy and speed to solution is usually obtained through the use of wall functions (WFs), especially in Reynolds averaged Navier–Stokes computations, which normally require that the first cell of the grid to fall inside the log-layer (50 &lt; y+ &lt; 200) (Wilcox, D. C., 1998, Turbulence Modeling for CFD, Vol. 2, DCW Industries, La Cañada, CA). This approach can be generally considered as robust, however the derivation of wall functions from attached flow boundary layers can mislead to nonphysical results in presence of specific flow topologies, e.g., recirculation, or whenever a detailed boundary layer representation is required (e.g., aeroacoustics studies) (Craft, T., Gant, S., Gerasimov, A., Lacovides, H., and Launder, B., 2002, “Wall – Function Strategies for Use in Turbulent Flow CFD,” Proceedings to 12th International Heat Transfer Conference, Grenoble, France, Aug. 18–23). In this work, a preliminary attempt to create an alternative data-driven wall function is performed, exploiting artificial neural networks (ANNs). Whenever enough training examples are provided, ANNs have proven to be extremely powerful in solving complex nonlinear problems (Goodfellow, I., Bengio, Y., Courville, A., and Bengio, Y., 2016, Deep Learning, Vol. 1, MIT Press, Cambridge, MA). The learner that is derived from the multilayer perceptron ANN, is here used to obtain two-dimensional, turbulent production and dissipation values near the walls. Training examples of the dataset have been initially collected either from large eddy simulation (LES) simulations of significant 2D test cases or have been found in open databases. Assessments on the morphology and the ANN training can be found in the paper. The ANN has been implemented in a Python environment, using scikit-learn and tensorflow libraries (Scikit-Learn Developers, 2019, “Scikit-learn v0.20.0 User Guide,” Software, Scikit-Learn Developers; Abadi, M., Barham, P., Chen, J., Chen, Z., Davis, A., Dean, J., Devin, M., Ghemawat, S., Irving, G., Isard, M., Kudlur, M., Levenberg, J., Monga, R., Moore, S., Murray, D. G., Steiner, B., Tucker, P., Vasudevan, V., Warden, P., Wicke, M., Yu, Y., and Zheng, X., 2016, “TensorFlow: A System for Large-Scale Machine Learning,” 12th Symposium on Operating Systems Design and Implementation, Savannah, GA, Nov. 2–4, pp. 265–283). The derived wall function is implemented in openfoam v-17.12 (CFD Direct, 2020, “OpenFoam User Guide v5,” CFD Direct, Caversham, UK), embedding the forwarding algorithm in run-time computations exploiting Python3.6m C_Api library. The data-driven wall function is here applied to k-epsilon simulations of a 2D periodic hill with different computational grids and to a modified compressor cascade NACA aerofoil with sinusoidal leading edge. A comparison between ANN enhanced simulations, available data and standard modelization is here performed and reported.

The prediction of power required to propel a high-speed catamaran involves the hydrodynamic interactions between the hull surface and the surrounding fluid that may be difficult to compute numerically. In this study model-scale experiments are used as a basis for comparison to full-scale sea trials data measured on a 112m Incat wave-piercing catamaran to predict the full-scale powering requirements from model-scale testing. By completing water jet shaft power measurements on an Incat vessel during sea trials, comparison of these results was made to model-scale test results to provide good correlation. The work demonstrates that the International Towing Tank Conference (ITTC) extrapolation techniques used provide a good basis for extrapolating the data from model-scale to full-scale to predict the power requirements for the full-scale catamaran vessel operating at high Froude Number with water jet propulsion. This provides a useful tool for future designers and researchers for determining the power requirements of a catamaran vessel through model tests.

In recent years, linear Fresnel (LF) collector systems have been developed as a technical alternative to parabolic trough (PT) collector systems. While in the past, LF systems focused on low- and medium-temperature applications, today, LF systems are equipped with vacuum receivers and, therefore, can be operated with similar operating parameters as PT systems. Papers about the technical and economical comparison of specific PT and LF systems have already been published (Dersch et al., 2009, "Comparison of Linear Fresnel and Parabolic Trough Collecor Systems—System Analysis to Determine Break-Even Costs of Linear Fresnel Collectors," Proceedings of the 15th International SolarPACES Symposium, Berlin; Giostri et al. 2011, "Comparison of Two Linear Collectors in Solar Thermal Plants: Parabolic Trough vs. Fresnel," ASME 2011 5th International Conference on Energy Sustainability, Washington, DC; and Morin et al., 2012, "Comparison of Linear Fresnel and Parabolic Trough Collector Power Plants," Sol. Energy, 86(1), pp. 1–12). However, the present paper focuses on the systematic differences in optical and thermodynamic performance and the impact on the economic figures. In a first step the optical performance of typical PT and LF solar fields (SFs) has been examined, showing the differences during the course of the day and annually. Furthermore, the thermodynamic performance, depending on the operating temperature, has been compared. In a second step, the annual electricity yield of typical PT and LF plants has been examined. Solar Salt has been chosen as the heat transfer fluid. Both systems utilize the same power block (PB) and storage type. Solar field size, storage capacity, and PB electrical power are variable, while all examined configurations achieve the same annual electricity yield. As expected for molten salt systems, both systems are the most cost-effective with large storage capacities. The lower thermodynamic performance of the LF system requires a larger SF and lower specific SF costs in order to be competitive. Assuming specific PT field costs of 300 €/m2 aperture, the break-even costs of the LF system with Solar Salt range between 202 and 235 €/m2, depending on the site and storage capacity. In order to confirm the major statements, within a sensitivity analysis, it is shown that a variation of SF and storage costs does not have a significant impact on the relative break-even costs of the LF system.