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COVID-19 pandemic has transformed the conventional education landscape to online remote learning. However, this transition has brought about certain challenges such as low levels of student engagement and motivation, which raises the question of whether students are actually learning. Using Virtual Reality (VR) in teaching and learning (T&L) could increase engagement as it provides interactive experience that necessitates students' online presence. Literature shows students are aware of VR benefits, yet not many tertiary educators are using VR. Thus, this study aims to investigate Malaysian tertiary educators' awareness of VR and readiness to explore its potential in remote online T&L through a questionnaire survey adapted from previous studies that applied the Technology Acceptance Model (TAM) as their theoretical framework. Of 26 respondents, only 4 had VR experience in the classroom. While others lacked VR experience, their perceptions were positive, and they were aware of the challenges of using VR. It can be concluded these challenges are partly the reasons why VR is under-utilised. The findings implicate the need to train and familiarise tertiary educators in the use of VR for the continuous intention to use VR. It is believed that when more educators have more intimate knowledge of VR, the more students will benefit regardless if the classes are remote online or otherwise. [For the full proceedings, see ED654100.]

English proficiency is advantageous for any graduate. In Malaysia, despite English being formally introduced around age 5, proficiency in the language is still lacking in some graduates. English should be introduced to children during their formation years so they can be proficient. However, in many private preschools, English proficiency is not a priority in the hiring criteria of early childhood (EC) educators despite the introduction of the Malaysian English Language Education Roadmap 2015-2025. With EC educators being a primary provider of input in the system, it is essential to investigate their attitudes towards English, particularly on the East Coast of Malaysia, where English usage is not as extensive as on the west coast, and how these attitudes translate into their practices with the children. A questionnaire of 29 questions was distributed to 114 EC educators. Findings reveal that positive attitude leads to EC educators using English with the children. Although knowledge of the language may be limited, the positive attitude spurs them to find alternative ways to expose English to the children. The findings hence provide insight to how we can upgrade the quality of existing English language education provided in preschools, mapping it to the Roadmap 2015-2025 for the reform to succeed. [For the full proceedings, see ED654100.]

In this study we evaluated the stability of item parameters and student scores, using the pre-equated (pre-pandemic) parameters from Spring 2019 and post-equated (post-pandemic) parameters from Spring 2021 in two calibration and equating designs related to item parameter treatment: re-estimating all anchor parameters (Design 1) and holding the c-parameter fixed for all multiple-choice items (Design 2). The Spring 2021 English Language Arts and Mathematics grades 3 through 8 operational test data from a large-scale testing program were used for this study. It was found that re-estimating item parameters in both Design 1 and Design 2 had little effect on the calibration and equating results, indicating acceptable stability of item parameters re-estimated in the post-pandemic environment. There was little or no difference in the mean scale scores and percentages of students classified in the different performance levels when students were scored using the pre-equated versus post-equated item parameters in Spring 2021. These differences in performance were even smaller when scores obtained in post-equated Design 1 and post-equated Design 2 were compared. When Spring 2021 student performance was compared to the Spring 2019 student performance, a decrease in performance was observed in each grade and content area that could be attributed to the effect of the pandemic and disrupted learning in the 2020-21 school year.

The teaching quality evaluation of college teachers is an important indicator of school evaluation, performance assessment and teacher promotion. However, the existing evaluation methods are only limited to the formal evaluation of teaching behavior, and have not achieved objective, reasonable and scientific evaluation results. The purpose of this paper is to propose a [delta]S equation of the state of the teaching system from the point of view of the teaching system's operation process. On this basis, a Markov process evaluation method for teachers' teaching quality is established. The research results show that the application of the [delta]S equation of the teaching system to the evaluation of teaching behavior and teaching effect has its own characteristics, and the key lies in the reasonable selection of the [delta]S equation and the the combination of Markov analysis can effectively achieve the evaluation goal of teachers' teaching quality. [For the full proceedings, see ED638044.]

A skills gap from theoretical knowledge to practical application is always a critical issue in Taiwan's education field. The launch of 12-year Basic Education Curriculum and the emergence of the educational innovation industry arouse the awareness of project-based competency-oriented curriculum design. Introducing design thinking into the educational field has received significant attention in recent years owing to the fact that the characteristics of design thinking track with a similar vision of the "core competency" listed in the 12-year Basic Education Curriculum, including emphasizing on exploring and doing, interdisciplinary integration, and the real-world scenario. This research takes the "Campus Ambassador Program" held by Design for Change Taiwan (DFC Taiwan), an educational innovation organization, as a case study. The method of semi-constructed in-depth interview is selected to gather the information from the student teachers of the program's participants as well as the staffs of DFC Taiwan who are responsible for this program, in order to know the effectiveness of the student teachers' design thinking education program. [For the full proceedings, see ED626585.]

The current study explores the ability to predict argumentative claims in structurally-annotated student essays to gain insights into the role of argumentation structure in the quality of persuasive writing. Our annotation scheme specified six types of argumentative components based on the well-established Toulmin's model of argumentation. We developed feature sets consisting of word count, frequency data of key n-grams, positionality data, and other lexical, syntactic, semantic features based on both sentential and suprasentential levels. The suprasentential Random Forest model based on frequency and positionality features yielded the best results, reporting an accuracy of 0.87 and kappa of 0.73. This model will be included in an online writing assessment tool to generate feedback for student writers. [For the full proceedings, see ED615472.]

In this paper, we extracted content-based and structure-based features of text to predict human annotations for claims and nonclaims in argumentative essays. We compared Logistic Regression, Bernoulli Naive Bayes, Gaussian Naive Bayes, Linear Support Vector Classification, Random Forest, and Neural Networks to train classification models. Random Forest and Neural Network classifiers yielded the most balanced identifications of claims and non-claims based on the evaluation of accuracy, precision, and recall. The Random Forest model was then used to calculate the number, percentage, and positionality of claims and non-claims in a validation corpus that included human ratings of writing quality. Correlational and regression analyses indicated that the number of claims and the average position of non-claims in text were significant indicators of essay quality in the expected direction. [This paper was published in: V. Cavalli-Sforza, C. Romero, A. Rafferty, & J. R. Whitehill (Eds.), "Proceedings of the 13th International Conference on Educational Data Mining (EDM)" (pp. 691-695). Virtual Conference: International Educational Data Mining Society.]

The emphasis of this study lies in behavior change after using car apps that assist users in using their vehicles and establishing a process for examining the interrelationship between car app's persuasive characteristics and behavior change. A categorizing method was developed and 697 car apps were investigated and classified into eight categories. Meanwhile, an evaluation guideline was developed and nine persuasive design characteristics were found to be popular used. A quasi-experiment was conducted and a behavior change evaluation process was developed. 109 participants were recruited and asked to use a car app for two weeks. The results indicate that participants clearly perceived eight persuasive design principles and four types of behavior change were found. The participants in four behavior change groups showed different perception levels for eight persuasive design principles. Our pioneer work has contributed to help designers and automakers to develop more effective and more persuasive car apps. [For full proceedings, see ED571459.]

The Mobile Assisted Language Learning concept has offered infinite language learning opportunities since its inception 20 years ago. Second Language Acquisition however embraces a considerably different body of knowledge from first language learning. While technological advances have optimized the psycholinguistic environment for language learning, this study narrows the discussion into developing a conceptual framework for Mobile Assisted Second Language Learning (MASLL). It is a logical and analytical concept developed from empirical theories and principles for Second Language mobile learning environments. Second Language Acquisition Theories, Model of Working Memory and Dual Coding Theory are the underlying learning theories for second language acquisition; Cognitive Theory of Multimedia Learning and FRAME Model on the other hand guide the design principles for mobile learning environments. Interest in MASLL derived from the preliminary investigation which highlighted low performance in oral communicative skills among learners of Chinese as a foreign language due to the lack of interactive environments. As such, a mobile chat room which follows this framework is briefly discussed to better inform the concept of MASLL. [For the complete proceedings, see ED557181.]

The Ethiopian development plans have dealt with education sector as a key strategic pillar. There have been a lot of educational efforts. Especially to cope with lack of qualified teachers, lack of good teaching models, and remote rural regions separated from educational benefits, Ethiopian Ministry of Education has made efforts in utilizing educational media such as satellite TV program for improving quality of secondary education for last decades of years. However, there was lack of national investigation in the aspect of systemic evaluation, for measuring the effectiveness of satellite TV program. This study aims to investigate the actual practice and effectiveness of satellite TV program in Ethiopian secondary schools. To achieve the goal, one questionnaire was developed based on CIPP model. Two secondary schools are selected and 228 students (Grade 9-12) participated in the survey. Data collected from them were utilized for descriptives & frequencies analysis, chi-square test, and multiple regression analysis. The results indicated that Ethiopian students utilizing satellite TV program scored highly in the evaluation areas of context, input, process, and product of the program. It was also found that learning demand, learning content, and class management were factors affecting the satisfaction in satellite TV program. These findings suggested that satellite TV program could play an important role in improving the quality of in Ethiopian secondary education. As a conclusion, several educational and administrative strategies to improve the TV program were recommended. [For full proceedings, see ED557189.]

The effects of foreign exchange programs on career development and planning of the students involved should be considered. For foreign exchange students to develop the cognitive skills needed in effective transfer of vocational knowledge and skills, students need to engage in cross-cultural career exploration, make career decisions about the relevance of their foreign exchange experiences, and then integrate these experiences as they shape occupational roles in their home countries. Cross-cultural differences involve foreign students' exposure to career information that is to some degree different from their expectations and their previous experiences. Students' perceptions of these differences depend to some degree on their social interests and interpersonal skills. Students who are less outgoing may have more trouble engaging in cross-cultural experiences and integrating such experiences into their occupational plans when they return to their home countries. A model for the evaluation of foreign exchange student programs should be developed; the model should include changes in relevant career behaviors of students that occur during the time of their foreign training and education. (38 references) (KC)

The impact of world technology on the Malaysian education scene has been tremendous. The system of education, while trying to maintain its local cultural values, is greatly influenced by the world culture. This phenomena is also seen in its teacher education programs. But what has this impact done to the development and progress of teacher education in the country? This paper highlights: (1) teacher education programs in the country at the preservice and inservice level; (2) how much technology has influenced the education of teachers to be more effective in the classroom and achieve excellence in their performance; (3) the impact of world technology on the value-system of the country in direct relation to the goals of teacher education; and (4) the Malaysian classroom in perspective: realities and possibilities. In looking at the impact of world technology, especially technological aids to improve teaching and learning, we must be aware of: (1) the cost benefits of such aids; (2) the role of the "super-salesman"; and (3) the training of teachers to cope with the changing world of technology. This paper draws conclusions for studies made in the country on the above possibilities and suggests areas for further rethinking, research and planning. (Author)

Considering India's fast change in socioeconomic environment, its population change would be an important driving factor of global population trajectory. While many of well-known studies for fertility decision have focused on husband-wife relationship as a unit of decision making in micro-level study and regional sociocultural factors in macro-level, there are some difficulties to apply these ideas into India's extended and hierarchical family structure. In this paper, I discuss how family member other than a couple, such as senior-male and senior-female, has an effect on having children by analyzing India Human Development Survey. 14,168 of women, who are currently married, still living together with husbands' family, and age between 15~49, were analyzed with multivariate regression model. According to the result, there is a statistically significant effect on having additional children when senior female of the family most say about the number of children with holding other variables in constant. When senior female most say about the number of children, a couple may have 0.13 more children compare to a case when respondent (wife) most say about number of children. In Poisson model, this coefficient is equivalent to 6% more children when senior female most say about number of children, and it has statistically significant as well. This result gives a sense of importance of understanding other family member's influence on fertility decision making. [ABSTRACT FROM AUTHOR]

The high and rising divorce rate in China is not easily reconciled with traditional theories that emphasize the role of modernization in changing family life. By reformulating the state social engineering theory, this paper argues that the retreat of the state from private life has contributed to China's rising divorce rates in the past four decades. A divorce reform that simplified divorce procedures and the declining significance of the work unit are two mechanisms through which the retreating state may influence divorce rates. Results from province-level panel data set suggest that smaller share of employment in state and collective work units is associated with higher divorce rates. The diminishing function of institutional control accounts for the effect of the work unit on rising divorce rates. [ABSTRACT FROM AUTHOR]

This study investigated the effects of a pioneering pedagogical approach, Flipped Learning (FL) on undergraduate students during English reading comprehension and engagement. A framework was designed to measure the students' engagement while a pre-test and post-test was administered for comprehension. The method requires the students to visit and use the Learning Management System, LMS (Moodle) in their own time and was later questioned on what they learned and how they approached the given task. During the class time, participants were grouped whereby peer instruction (PI) was conducted. Results show that FLO group showed positive results than FLPI group in both achievement test and engagement questionnaire due to its simplicity for students which keep them active with instructors' feedback. Furthermore, there was a significant interaction effect for engagement between the flipped learning modes by gender with females reporting higher engagement. [ABSTRACT FROM AUTHOR]

Modeling road accidents using panel data approach recently has gained wide attention and application. As the nature of road crashes are non-negative count, the traditional linear computational approaches is inappropriate giving the nonlinear model of fixed effects (FE) the better choice. This paper examines the road accidents relationship with precipitation factors by estimating the FE Negative Binomial (NB) model. In the FE model two estimation methods were consider in this paper: conditional and unconditional estimation method. Thus, this paper compare the conditional and unconditional FE model for road accidents and discuss the findings obtain. Results showed that the unconditional FE Negative Binomial model gives approximately the same results with conditional models. The effect of monthly rainfall with shorter spell period presents greater risk of accident rate. On the other hand, a negative relationship is found between the monthly rainfalls with longer spell period and accident rate. [ABSTRACT FROM AUTHOR]

Current industry practice in flexible pipe tensile armor wire fatigue testing involves use of un-corroded specimens; however, if the armor wires in a flexible are prone to pitting corrosion during service, this adds a new dimension to the fatigue life consideration which is the focus of this paper. The paper presents a methodology to consistently evaluate fatigue lives of armor wires with pitting corrosion. Described herein is a methodology to create corrosion pits on armor wires and the results from a fatigue test program involving Non-Pitted and Pre-Pitted specimens. [ABSTRACT FROM AUTHOR]

TLP (tension leg platform) is often used as a supporting structure to hold offshore structures. TLP is moored vertically by axially pre-tensioned circular beam called tendon. Since tendon is installed underwater as slender structure, its behavior is affected by undersea current. Especially, VTV (vortex-induced vibration) induced by current have an influence on tendon in both in-flow and cross-flow directions. In tins work, we focus to study the response in cross-flow direction. When the occurrence frequency of VIV coincide with the natural frequency of tendon, the amplitude of VTV-induced response increases rapidly and this phenomenon is called lock-in. The effect of current velocity on VTV's amplitude Ls considered in this work to observe the lock-in. VTV-induced lift force model in previous studies is used in cross-flow direction motion, and coupled analysis for both floating structure and tendon is conducted. BEM (boundary element method) and Convolution integral method are used for floating structure model, and FEM (finite element method) is used for tendon model. In this work lock-in is investigated, and motions of floating structure and tension of tendon with VTV are estimated to verify the effect of VTV. Bending stresses in cross-flow direction are assessed for the analysis of fatigue safety. [ABSTRACT FROM AUTHOR]

Design of a steel catenary riser (SCR) requires the use of specialized connection hardware at the floater hang-off to accommodate the high bending moments produced by vessel motion. Strength and fatigue reliability of this connection hardware is imperative, especially for high pressure and high temperature applications involving corrosive production fluids. One type of SCR connector is a metallic tapered stress joint which is typically mounted on a porch basket assembly. Because of its inherent density, strength- and stiffness characteristics. steel may not be well suited for this application as it typically results in excessively long and heavy stress joints. Titanium Gr. 29 has been identified as a good material candidate for harsh stress joint applications due to its attractive mechanical characteristic including lower stiffness, high strength and fatigue performance and high resistance to corrosive fluids. Industry has successfully used this technology in approximately fifty SCR applications as described in the vendor Project Database (2016). Large titanium stress joints (TSJs) for deep-water applications may not be fabricated as a single piece due to titanium billet volume limitations, thus making an intermediate girth weld necessary to satisfy the length requirement. Fracture and fatigue performance of these welds in the presence of cathodic potentials in seawater and galvanic potentials in sour production fluids, which may produce hydrogen embrittlement effects, must be characterized to ensure long term structural integrity. Although corrosion-fatigue data have been generated for Ti alloys in seawater and sour brine environments, data are limited to small scale welded specimens or larger full thickness base metal specimens. To date, no data are available for either base metal or welded Ti Alloys under applied or galvanic currents. This paper describes a joint industry project (JTP) to qualify titanium stress joints welds for ultra-deep water applications under harsh sendee conditions. Total fatigue life results for Ti 29 1G full thickness welded specimens in air. seawater under cathodic potential and sour brine environments under galvanic potentials are summarized along with general observations and design guidance. An improved automatic gas tungsten arc welding (GTAW) process developed during the test program to better manage the maximum defect size in the girth welds and surmount current ultrasonic inspection limitations is also described. [ABSTRACT FROM AUTHOR]

A hybrid wind and wave energy converter concept, which consists of a spar floating wind turbine and a coaxial wave energy converter named the STC (Spar Torus Combination) concept, has been proposed to achieve better utilization of the ocean space and energy, synergy of the wind and wave conversion, and to reduce the energy cost. The torus moves along the spar cylinder in operational conditions. The critical component of this concept is the interface between wave energy converter and spar floater. Nonlinear local structural modelling of the interface is performed and presented in this paper. The wave energy converter is designed to be connected mechanically to the spar floater by a series of rollers through hydraulic supports. Rubber rollers are used to reduce the contact stress. Different configurations of the spar structure at the interface with the torus are investigated. Quasi-static analyses are carried out. Numerical and experimental studies of the global behavior have been performed, and the results are used as input to the local structural analysis. [ABSTRACT FROM AUTHOR]

Accurate time-consistent computation of tensile armor wire stresses remains a major challenge in flexible riser fatigue life predictions and integrity management. Accuracy requires capturing the kinematics of the flexible's helically contra-wound tensile armor layers and their interaction with the other metallic and thermo-plastic layers in a dynamic simulation. It is generally accepted thai high fidelity 3D Finite Element Models (FEMs) can capture this complex kinematics and produce accurate stresses. However, dynamic simulation of the flexible's detailed FEM for spans longer than a few meters requires prohibitively long compulation times when utilizing commercial FE solvers. This has constrained the detailed FEM to a local model for static post-processing of maximum tension and curvature from regular wave global analyses. If more accurate representations of the dynamic environments (and associated fatigue life estimates) are desired, irregular wave tension and curvature time-histories are utilized as inputs to stress transfer functions generated from simplified FEM representations. Nonlinear Dynamic Subslructuring (NDS) is designed for efficient computation of large-order nonlinear dynamic systems composed of FEMs. NDS is an extension of the framework of dynamic substructuring capturing all its computational efficiencies while operating in fully nonlinear mode. With NDS, the flexible's detailed FEM is no longer relegated to short spans and static analysis. Instead, the detailed FEM can be synthesized to longer span local models and utilized in nonlinear dynamic simulations with long duration irregular wave tension/curvature inputs. Alternatively, the detailed FEM can be synthesized to global configurations where the simulations can capture the flexible's complex kinematics at global geometries, boundary conditions, and dynamic environments. In either local or global NDS application, irregular wave armor wire stress time-histories are directly computed from the simulations and serve as an accurate basis for an enhanced fatigue assessment capturing a large array of stress ranges and associated cycles. This leads to high resolution fatigue spectra for reliable and accurate life estimates. This more accurate life estimate can play an important role in reducing over-conservatisms due to simplified models and idealized environments and allow for more accurate life extension assessments and more robust flexible riser integrity management programs. The validation of the NDS approach involved both numerical benchmarking and experimental validations. Numerical benchmarks of NDS simulations were executed against commercial FEA solvers on a pitch length 3D FEM, approximately 4 million degrees of freedom (DoFs) in size, for axial, torsion, internal pressure, external pressure, and bending cases. Experimental validation of NDS simulations involved comparisons of wire strains against an 8-pitch (4.65m) experiment involving multiple cycles of axial, torsional, and bending inputs. The 3D FEM simulated for the above experimental validation cases is approximately 32 million DoFs, making executions in commercial FEA infeasible wIil-ivus (he NDS simulations executed m minutes. It is shown that NDS results are in very good agreement for both numerical and experimental cases. [ABSTRACT FROM AUTHOR]

Since the water depth and model scale are usually limited in water tanks, truncated mooring lines are widely used in the model test for deep sea moored body. In that case, matching of physical parameters between original depth and truncated models are required. The most basic target is the static offset versus restoring force because the matched offset curve guarantees equivalent mooring stiffness of floating body. However, another parameters such as weight, mean tension and damping are also issues in truncation modeling. This paper carried out some numerical studies regarding the truncation parameters and presented some discussions about matching offset curve, weight, tension and damping at the same time. Floating body and mooring lines are analyzed by HOBEM (Higher Order Boundary Element Method) based convolution and FEM (Finite Element Method), respectively and the coupled responses are simulated The derived results may provide some guide to improve truncation model test. [ABSTRACT FROM AUTHOR]

Over the past decade, process managers have been forced increasingly to cope with the lack of a skilled workforce and increases in hazardous circumstances for human operations. Erection simulation systems have been widely proposed as alternatives to overcome these difficulties and to raise erection quality, enhance productivity, and improve safety. With the deterioration in the technical ability of process managers without enough erection simulation training and information to achieve low interference and saving time, the marine erection accidents in yard such as fatality, collision due to interference tend to increase gradually in erection process of ships and offshore platform. It may be considerably difficult to establish the methodology for a safety and accurate measures system for erection process. In this paper, to demonstrate the efficiency of an erection simulation system, introduce a point cloud based erection simulation method for planning erection process in offshore installations. This simulation method produces an optimized movement path of workforce and without interference for erection structures. As a practical example, the cost-benefit analysis for preventing erection process time and the background risk is investigated using the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, a series of numerical models has been developed lo study the effects of two different baffles on liquid sloshing under the six degree-of-freedom (6-DOF) excitation. The moving particle semi-implicit (MPS) method is a mesh-free method which can simulate flow with large deformation and nonlinear fragmentation of free surface effectively. The MLParticlc-SJTU solver based on improved MPS method is first validated against the available experimental data for 3-D liquid sloshing in a rectangular tank under horizontal excitation. Then, the study of liquid sloshing in another tank is carried out under the 6-DOF excitation. The detailed (low field and the variation of impact pressure can be observed clearly. In addition, the effects of two different baffle types on liquid sloshing, two vertical baffle and two ring baffles, arc further analyzed based on previous rectangular tank. Results show that the sloshing and pressure amplitudes arc obviously reduced due to these baffles and the ring baffles arc more effective on restraining sloshing. [ABSTRACT FROM AUTHOR]

In the present study, the process of free-falling wedge imparting on water is numerically studied by our in house solver based on Moving Particle Semi-Implicit (MPS) method. Some improved schemes are used in this solver to suppress numerically unphysical pressure oscillation in traditional MPS method. For validation purpose, computational results of wedge with different tilting angles are compared against experimental results from the Wave Induced Loads on Ships Joint Industry Project III (WILS J1P-III). Numerical pressures, free surface elevations and velocities of wedge show agreement with experimental data. [ABSTRACT FROM AUTHOR]

The improved MPS (Moving Particle Semi-implicit) method is adopted lo numerically investigate the water entry of a ship bow section and three cases with different impact speeds arc carried out in the present work. Firstly, the ship bow impacting water with speed U0=0.61m/s is simulated to validate the capability of the present method into water entry of a ship bow with complex shape. The vertical force and velocity of the bow section arc compared with the literature data. Then, two more cases arc calculated and the bow drops into water with different speeds. The comparisons of the vertical forces between the present method and literature data show that the force peak will rise up and the corresponding instant will reach earlier as increasing the initial entry speed. [ABSTRACT FROM AUTHOR]

An Unsteady Acluator Line Model (UALM) is developed in this paper and applied lo a 5MW floating offshore wind turbine (FOWT). This model is implemented into two-phase fluid CFD solver, naocFOAM-SJTU. The goal of the approach presented here is to investigate the interaction of the aerodynamic loads with the platform motion within acceptable time cost. A semi-submerged floating platform conceptualized in the Offshore Code Comparison Collaboration (OC4) is considered in this paper. Initially the UALM is verified by comparison with the results of a previous study. Next, two kind of full-system simulations with different complexity arc performed: first, the wind forces arc simplified into a constant thrust; second, the fully coupled dynamic analysis with wind and wave excitation is conducted by utilizing UALM. Based on the results, the aerodynamic loads and coupled responses for cases of different complexity arc discussed. [ABSTRACT FROM AUTHOR]

The present work is focused on the comparative study of two numerical methods, i.e. MPS method and VOF method, for the prediction of sloshing in LNG tank. Numerical simulations are carried out by an in-house meshless solver MLParticlc-SJTU based on improved Moving Particle Semi-Implicit (IMPS) method, and VOF based CFD solver naoc-FOAM-SJTU developed on the open source platform OpcnFOAM. Several sloshing conditions with different kinds of tanks are applied to validate the present two numerical methods. The time histories of impact pressure and (low patterns are presented and compared to the experimental data. For the rectangular tank, sway motion with different excitation periods are taken into account to investigate the sloshing performance and validate the two simulation methods. For the membrane-type LNG tank, pitch motion with different excitation periods are simulated. According to the numerical results, the two methods can both predict the impact pressure compared with the experiment data. The VOF method and the MPS method show different (low patterns when encountering with breaking waves. [ABSTRACT FROM AUTHOR]

The present work is focused on the numerical prediction of ship self-propulsion in different shallow water conditions: H/T=2.0 and H/T=1.2 (H is the depth of water and T is draft of ship). The KRISO Container Ship (KCS) model is used in the present simulation. Numerical computations are carried out by our own solver naoc-FOAM-SJTU, which is developed on the open source platform OpcnFOAM and mainly composed of a dynamic overset grid module and a full 6D0F motion module with a hierarchy of bodies. A proportional-integral (PI) controller is applied to adjust the rotational speed of the propeller to achieve the desired ship speed. The simulated results, i.e. the rate of revolution of propeller n, propulsion coefficients, are compared to the experimental data provided by Flanders Hydraulics Research (FHR) in SIMMAN 2014. Good agreements show that the present approach is applicable for self-propulsive prediction in shallow water. [ABSTRACT FROM AUTHOR]

Resistance prediction for a ship is one of the vital tasks at the design stage. In this paper, the in-house multifunction solver naoc-FOAM-SJTU based and developed on the open source code Open FOAM is applied to study the resistance, sinkage & trim characteristics and the local How around the stem of Japan Bulk Carrier (JBC) with and without an energy saving device sailing in calm water. A V&V (verification and validation) method is used to determine the errors and uncertainties. The numerical results of the presented paper agree very well with the measurement data of model test. [ABSTRACT FROM AUTHOR]

The objective of this study is lo predict and analyze the viscous flow and the ship-ship interaction between two different tankers KVLCC2 and Aframax advancing in shallow water with same speed and with a fixed separation distance by solving the unsteady RANS equations in combination with the k-co SST turbulence model. The computational results of the resistance, lateral force, yawing moment, as well as wave height measured by the wave gauge are validated against EFD conducted in Flanders Hydraulics Research (FHR) towing tank. Though the error for case A is not so satisfactory by up to 73%EFD, the tendency is agreed well with EFD data. Moreover, the error case B is much batter by less than 6.25% for both ships. For better understanding of the ship-ship interactions, the wave pattern of the free surface, surface pressure distribution of the ship hull, the asymmetric ship wake and vortex system arc also given. [ABSTRACT FROM AUTHOR]

The aerodynamic performance of the floating offshore wind lurbinc has an extra level of complexity than that of bottom-fixed wind turbines because of the motions of the supporting platform. In this paper, the unsteady aerodynamic performance of the NREL-5MW Baseline wind turbine with periodical surge and pitch motions of its supporting platform arc investigated. The three-dimensional Reynolds Averaged Navier-Stokes equations arc solved for the aerodynamic numerical simulation. The naoc-FOAM-os-SJTU solver, which is based on OpcnFOAM and overset grid technology and developed for ship and ocean engineering problems, is employed. From the simulation, the time series of the unsteady torque and thrust are obtained, together with the detailed information of the wake flow field, and the pressure coefficient distribution in different cross-section arc also available to clarity the detailed (low filed information. The simulation results arc compared both with those obtained from aerodynamic simulation of wind turbine without effects of platform motions, and with other approaches in previous studies. The simulation results show that the pitch motion has more significant effects on the aerodynamic forces and moments of the rotor than the surge motion docs. And the motion of the platform especially the pitch motion may bring very bad influence on the turbine forces and wake flow, even on the power generation in case of very severe pitch motion. [ABSTRACT FROM AUTHOR]

This paper presents a numerical study of flow over a circular cylinder al high Reynolds number using detached-eddy simulation (DES). The k-ω Shear Stress Transport (SST) based DES model is selected for handling massively separated flow. The computations arc performed with an O-type grid and the instantaneous and statistical characteristics of the turbulent wake flow behind the cylinder is extensively studied. The results are compared with the available experimental data, as well as the previously published numerical data obtained from Reynolds-averaged Navier-Stokes (RANS) and large-cddy simulation (LES). The incompressible flow assumption and finite volume discretization is adopted. All the works are carried out with the use of OpcnFOAM toolbox. [ABSTRACT FROM AUTHOR]

Vortex-induced motions (VIM) is a common phenomenon on varies kinds of deep-water offshore platforms such as deep draft semi-submersible and Spar. The present study investigates the VIM response of a Spar at different incident angles (current headings). The numerical investigations arc conducted under supercritical Reynolds number using naoc-FOAM-SJTU, a solver developed based on the open source framework OpcnFOAM. The self-d eve loped six degree-of-freedom (6D0F) motion module and mooring system module are applied to model motions of Spar and the constraint of mooring lines, respectively. The shear stress transport (SST) based detached-eddy simulation (DES) is chosen for turbulence closure to predict the massive flow separation at high Reynolds number. The main purpose of this paper is to study the "hot spots" phenomenon of VIM response in a numerical way. [ABSTRACT FROM AUTHOR]

A practical multi-objective optimization tool, named OPTShip-SJTU, is utilized here to optimize both of the resistance and seakeeping performance for a surface combatant DTMB Model 5415. During the optimization procedure, free-form deformation (FFD) method is used as parametric hull surface modification technique to produce a series of alternative hull forms subjected to geometric constrains. The Neumann-Michell (NM) theory and an extension of Bales seakeeping ranking method are implemented in the evaluation module of the tool, and to predict the wave-making drag and Bales seakeeping rank factor R respectively. An optimized Latin hypercube sampling (OLHS) method is employed to generate 60 samples within the design space, and an approximation model is established in terms of these samples and corresponding predictions. A multi-objective genetic algorithm, NSGA-II, is adopted to produce pareto-optimal front. The numerical optimization results arc analyzed, and the availability of the OPTShip-SJTU is confirmed by this application. [ABSTRACT FROM AUTHOR]

Vortex-induced vibration (VIV) is a key issue in deep water riser design. Design of deep water systems is a challenging engineering problem and the understanding of VIV and its suppression arc very active areas of research. This paper presents the response of a vertical tension riser model in a step current when subject to VIV. The riser is 13.12m long and 28mm in diameter, with a mass ratio of 3.0. The simulation is carried out by a multi-strip method. This method combines a series of 2D RANS simulations of the flow at individual axial strips along the riser with a fully 3D FEM structural analysis based on Euler-Bernoulli beam theory. The entire flow-structure solution procedure is carried out in the time domain via a loose coupling strategy. The numerical results show that the VIV response is mainly dominated by the 7th mode for in-line vibrations and the 4th mode for cross-How vibrations. The response included significant contributions from several modes. The riser pipe vibrates with a multimodal pattern. Moreover, the dominant modes and modal amplitudes, the mean in-line displacement, and the instantons deflected shape of the riser in the cross-flow direction, etc., agree well with the experimental results. In particular, the numerically predicted location of the maximum mean in-line displacement and the experimental result differ by only about 1%. The good agreement between the numerical and experimental results shows that the multi-strip method is practical in predicting the general features as well as specifics of the VIV of the riser. [ABSTRACT FROM AUTHOR]

With the development of CFD technology and the improvement of computing capacity, CFD is playing an increasingly important role in ship design. However, at present CFD computations of ships are typically performed in model scale due to the lack of experimental results in full-scale, and the increasingly complexity of numerical simulation at very high Reynolds numbers that RANS is hard to solve. In this paper, a RANS/DES solver for naval architecture and ocean engineering named naoe-FOAM-SJTU solver, which is developed from OpenFOAM, is applied to carry out the numerically simulation of model- and full-scale VLCC. For model scale computation results, we adopt the three-dimensional extrapolation method to get full-scale resistance, and also full-scale calculation is carried out by CFD method at the cruise speed directly. Results are compared with the experimental results' three-dimensional extrapolation results. The effect of surface roughness is considered in full-scale computations. Analysis results show reliability and validity of our IDDES method in ship resistance prediction. This paper also made a discussion on comparison of flow fields of model-and full-scale VLCC. [ABSTRACT FROM AUTHOR]

In this paper, a numerical solver for naval architecture and ocean engineering named naoc-FOAM-SJTU solver, which is developed using OpcnFOAM, is applied to conduct the simulation of a special object moving in calm water. The main part of the object goes forward under the free surface of water, whereas a slender rod of the object stretches out of the water. To better simulate the situation, this research use two different girds. One is the traditional non-overset grids, and the other is overset grids. Results of both grids are compared in regard of forces, wave patterns and velocities. The object moves at two different speeds (5kn and 6kn), while the moving direction, which is named as x-direction, is always parallel to the free surface of water. The similarities and differences of the result calculated out by the two grids are discussed. This paper also discusses the influence of moving speed on the wave pattern, resistance and velocity field. [ABSTRACT FROM AUTHOR]

In this study, fatigue lives of mooring line and tower of a floating wind turbine structure were investigated. A SPAR type wind turbine with three catenary mooring lines, a rotor-supporting tower, and three blades is considered as an example structure. Mooring line tension and tower base stress are calculated through a time-domain coupled analysis. Boundary element method (BEM) and convolution are applied to floating body formulation. The mooring lines, tower, and blades are formulated with catenary elements, elastic beam elements, and aerodynamic elastic rotating beam elements, respectively, using finite element method (FEM). By analyzing the mooring line tensions with fatigue curves according to API-RP-2SK and statistical methods such as simple summation (SS), combined spectrum (CS), and combined spectrum with dual narrow band (CSDN), fatigue life of a mooring line is obtained. Fatigue life of a tower is obtained by analyzing the tower base stress with fatigue curves according to API-RP-2A-WSD and the statistical methods SS, CS, and CSDN. From the numerical results, fatigue features of mooring line and supporting tower are investigated and compared. Through an analysis of fatigue life by changing breaking strength of mooring line, the effect of breaking strength on fatigue life variation is also discussed. [ABSTRACT FROM AUTHOR]

The article discusses research which examined the fatigue crack growth rate (FCGR) model to accurately predict fatigue cracking behavior during the process of conducting an engineering criticality assessment to determine weld flaw acceptance criteria. Topics discussed include the evaluation of parent pipe, weld center line and heat-affected zone metallurgies and steel catenary rise (SCR) and lateral buckling flowline.

The article discusses research which examined the fatigue assessment methods for fatigue design of fracture-critical flowlines. Topics discussed include the proposed reliability-based analysis to determine safety factors (SF) for various offshore applications, weld design cases with different specified design flaw sizes, challenges in the fatigue design of Julia flowline and the fracture mechanics (FM) approach.