bluuebunny/crossref_metadata_2025 huggingface dataset:
One‐Part Geopolymers Based on Thermally Treated Red Mud/NaOH Blends
Authors: Ke Xinyuan , Bernal Susan A. , Ye Nan , Provis John L. , Yang Jiakuan
Published: September 2014

In this study, one‐part “just add water” geopolymer binders are synthesized through the alkali‐thermal activation of the red mud which is relatively rich in both alumina and calcium. Calcination of the red mud with sodium hydroxide pellets at 800°C leads to decomposition of the original silicate and aluminosilicate phases present in the red mud, which promotes the formation of new compounds with hydraulic character, including a partially ordered peralkaline aluminosilicate phase and the calcium‐rich phases C3A and α‐C2S. The hydration of the “one‐part geopolymer” leads to the formation of zeolites and a disordered binder gel as the main reaction products, and the consequent development of compressive strengths of up to 10 MPa after 7 d of curing. These results demonstrate that red mud is an effective precursor to produce one‐part geopolymer binders, via thermal and alkali‐activation processes.
Evolution of Microstructure and Intergranular Glass Chemistry in Plastically Deformed Nanocrystalline Si3N4 Ceramics
Authors: Wananuruksawong Raayaa , Shinoda Yutaka , Akatsu Takashi , Wakai Fumihiro
Published: September 2014

Nanograined Si3N4 ceramics with Y2O3–Al2O3–MgO as sintering additive exhibited superplastic elongation of >300% at 1923 K with an initial strain rate of 5 × 10−4 s−1. Flow stress was less than 4 MPa up to elongation of 130%. In the later stage of deformation, the flow stress increased with strain due to the grain growth and the alignment of elongated grains. The volume fraction of glassy phase significantly reduced due to vaporization of glassy phase. The chemical analysis by TEM/EDS revealed that the chemical composition of the near Si3N4 grain surface was different from that of the interior of the glass pocket at multigrain junctions due to absorption of additive cations on the Si3N4 grain. The chemistry of intergranular glassy phase changed significantly in the later stage of deformation accompanying the microstructural evolution. It is suggested that the flow stress, which depends on the viscosity of intergranular glassy phase, varies with the change in glass chemistry during deformation.
Factors influencing migratory decisions made by songbirds on spring stopover
Authors: Covino Kristen M. , Holberton Rebecca L. , Morris Sara R.
Published: September 2014

Behavioral decisions made by migrating songbirds may depend on a variety of biotic and abiotic factors. To investigate which factors most influence songbird behavior on stopover, we related departure and directional decisions of captive birds released at the capture site to a variety of factors including, weather, date, energetic condition, age, sex, and species. We captured spring migrants during the day, released them after sunset, and visually assessed whether they departed the study site and if so, in which direction. Departure was strongly influenced by wind direction and energetic condition, especially fat stores. The proportion of birds departing increased as the season progressed. Directional decisions were also strongly influenced by energetic condition, particularly fat stores and plasma triglyceride levels. Wind direction also influenced the direction in which birds made migratory flights. While energetic condition, stage of migration, and weather seem to be important proximate determinants in departure and directional decisions, habitat availability and other factors may also need to be considered.
Effects of maternal sensitivity on low birth weight children's academic achievement: a test of differential susceptibility versus diathesis stress
Authors: Jaekel Julia , Pluess Michael , Belsky Jay , Wolke Dieter
Published: September 2014

Background

Differential Susceptibility Theory (DST) postulates that some children are more affected – for better and for worse – by developmental experiences, including parenting, than others. Low birth weight (LBW, 1,500–2,499 g) may not only be a predictor for neurodevelopmental impairment but also a marker for prenatally programmed susceptibility. The aim was to test if effects of sensitive parenting on LBW and very LBW (VLBW, <1,500 g) versus normal birth weight (NBW, ≥2,500 g) children's academic achievement are best explained by a differential susceptibility versus diathesis‐stress model of person‐X‐environment interaction.

Methods

Nine hundred and twenty‐two children ranging from 600 g to 5,140 g birth weight were studied as part of a prospective, geographically defined, longitudinal investigation of neonatal at‐risk children in South Germany (Bavarian Longitudinal Study). Sensitive parenting during a structured mother–child interaction task was observed and rated at age 6 years. Academic achievement was assessed with standardized mathematic, reading, and spelling/writing tests at age 8 years.

Results

Maternal sensitivity positively predicted the academic achievement of both LBW (n = 283) and VLBW (n = 202) children. Confirmatory‐comparative and model‐fitting analysis (testing LBW vs. NBW and VLBW vs. NBW) indicated that LBW and VLBW children were more susceptible than NBW to the adverse effects of low‐sensitive, but not beneficial effects of high‐sensitive parenting.

Conclusions

Findings proved more consistent with the diathesis stress than differential‐susceptibility model of person‐X‐environment interaction: LBW and VLBW children's exposure to positive parenting predicted catch‐up to their NBW peers, whereas exposure to negative parenting predicted much poorer functioning.
Motivational interviewing to explore culturally and linguistically diverse people's comorbidity medication self‐efficacy
Authors: Williams Allison , Manias Elizabeth , Cross Wendy , Crawford Kim
Published: September 2014

Aims and objectives

To examine the perceptions of a group of culturally and linguistically diverse participants with the comorbidities of diabetes, chronic kidney disease and cardiovascular disease to determine factors that influence their medication self‐efficacy through the use of motivational interviewing.

Background

These comorbidities are a global public health problem and their self‐management is more difficult for culturally and linguistically diverse populations living in English‐speaking communities. Few interventions have been tested in culturally and linguistically diverse people to improve their medication self‐efficacy.

Design

A series of motivational interviewing telephone calls were conducted in the intervention arm of a randomised controlled trial using interpreter services.

Methods

Patients with these comorbidities aged ≥18 years of age whose preference it was to speak Greek, Italian or Vietnamese were recruited from nephrology outpatient clinics of two Australian metropolitan hospitals in 2009.

Results

The average age of the 26 participants was 73·5 years. The fortnightly calls averaged 9·5 minutes. Thematic analysis revealed three core themes which were attitudes towards medication, having to take medication and impediments to chronic illness medication self‐efficacy. A lack of knowledge about medications impeded confidence necessary for optimal disease self‐management. Participants had limited access to resources to help them understand their medications.

Conclusion

This work has highlighted communication gaps and barriers affecting medication self‐efficacy in this group. Culturally sensitive interventions are required to ensure people of culturally and linguistically diverse backgrounds have the appropriate skills to self‐manage their complex medical conditions.

Relevance to clinical practice

Helping people to take their medications as prescribed is a key role for nurses to serve and protect the well‐being of our increasingly multicultural communities. The use of interpreters in motivational interviewing requires careful planning and adequate resources for optimal outcomes.
Participatory research, people with intellectual disabilities and ethical approval: making reasonable adjustments to enable participation
Authors: Northway Ruth , Howarth Joyce , Evans Lynne
Published: September 2014

Aims and objectives

The aim of this paper is to explore how making reasonable adjustments to the process of securing ethical approval for research can facilitate the meaningful involvement of people with intellectual disabilities as members of a research team. This is achieved through critical reflection upon the approach taken within one participatory research study whose objective was to explore how people with intellectual disabilities understand abuse.

Background

Internationally participatory research studies (in which active involvement of community members in all stages of the research process is sought) are becoming increasingly common in the context of health care and, more specifically, within research involving people with intellectual disabilities. However, whilst it is acknowledged that participatory research gives rise to specific ethical challenges, how (or if) involvement in securing ethical approval is facilitated, is not discussed in most research reports. The significance of this paper is that it seeks to address this gap by exploring how meaningful participation can be promoted by making reasonable adjustments.

Methods

Within the study, the research team worked in collaboration with the ethics committee to identify potential barriers that could prevent the participation of members of the research team who had intellectual disabilities. Reasonable adjustments (such as redesigning forms) were made to the processes involved in securing ethical approval.

Conclusions

This study demonstrated that it is possible to ensure that ethical standards are upheld and the requirements of ethics committees met whilst also facilitating the meaningful involvement of people with intellectual disabilities.

Relevance to clinical practice

The reasonable adjustments approach explored within this paper can be translated into the context of clinical practice: making changes to the way that services are delivered can promote greater involvement of people with intellectual disabilities in their own health care.
Daily Affect and Female Sexual Function
Authors: Kalmbach David A. , Pillai Vivek
Published: September 2014

Introduction

The specific affective experiences related to changes in various aspects of female sexual function have received little attention as most prior studies have focused instead on the role of clinical mood and anxiety disorders and their influence on sexual dysfunction.

Aim

We sought to understand the transaction between daily affect and female sexual function in effort to provide a more nuanced understanding of the interplay between affective and sexual experiences.

Methods

The present study used a 2-week daily diary approach to examine same-day and temporal relations between positive and negative affect states and sexual function in young women.

Main Outcome Measures

We examined the unique relations between positive (i.e., joviality, serenity, self-assurance) and negative (i.e., fear, sadness, hostility) affects and female sexual response (i.e., desire, subjective arousal, vaginal lubrication, orgasmic function, and sexual pain) while controlling for higher order sexual distress, depression, and anxiety, as well as age effects and daily menstruation.

Results

Analyses revealed different aspects of both positive and negative affects to be independently related to sexual response indices. Specifically, results indicated that joviality was related to same-day sexual desire and predicted increased desire the following day. This latter relation was partially mediated by sexual activity. Further, greater sexual desire predicted next-day calmness, which was partially mediated by sexual activity. Notably, fear was related to same-day subjective arousal, lubrication, orgasmic function, and vaginal pain, whereas poorer orgasmic function predicted greater next-day sadness.

Conclusions

These findings describe the manner in which changes in affect correspond to variations in female sexual function, thus highlighting the inextricability of mental and sexual health. Further, these findings may offer insight into the progression of normative levels of affect and sexual function as they develop into comorbid depression, anxiety, and sexual dysfunction.
A little acceptance is good for your health: Interpersonal messages and weight change over time
Authors: LOGEL CHRISTINE , STINSON DANU ANTHONY , GUNN GREGORY R. , WOOD JOANNE V. , HOLMES JOHN G. , CAMERON JESSICA J.
Published: September 2014

This research examines whether acceptance messages from close others about one's weight predict changes in stressful weight concern and body mass index (BMI) over time. Participants reported weight concern and BMI in three waves of data collection spanning approximately 9 months, and reported the messages they received from parents, friends, and romantic partners concerning their weight in the second wave of data collection. Participants normatively gained weight during the study period. But for vulnerable women, those initially high in weight concern, receiving fewer acceptance messages about weight was associated with weight gain, whereas receiving more acceptance messages was associated with decreases in stressful weight concern and weight maintenance, or even loss, over time. Alternative predictors, mechanisms, and models were also tested.
Concerning Workload Control and Order Release: The Pre‐Shop Pool Sequencing Decision
Authors: Thürer Matthias , Land Martin J. , Stevenson Mark , Fredendall Lawrence D. , Godinho Filho Moacir
Published: September 2014

Every production planning concept that incorporates controlled order release will initially withhold jobs from the shop floor and create a pre‐shop pool. Order release is a key component of the Workload Control concept that aims to maintain work‐in‐process within limits while ensuring due dates are met. Order release includes two decisions: (i) a sequencing decision that establishes the order in which jobs are considered for release; and, (ii) a selection decision that determines the criteria for choosing jobs for release. While selection has received much research attention, sequencing has been largely neglected. Using simulation, this study uncovers the potential for performance improvement in the sequencing decision and improves our understanding of how order release methods should be designed. Although most prior studies apply time‐oriented sequencing rules and load‐oriented selection rules, analysis reveals that load balancing considerations should also be incorporated in the sequencing decision. But an exclusive focus on load balancing is shown to increase mean tardiness and, paradoxically, require high workloads. A new sequencing rule is developed that only balances loads when multiple orders become urgent. It avoids high mean tardiness and allows the shop to operate at a low workload level. At the same time, the percentage tardy is reduced by up to 50% compared to a purely time‐oriented rule. The findings have implications not only for Workload Control but for any concept that features order release control, such as ConWIP and Drum‐Buffer‐Rope.
The meaning of the virtual Midas touch: An ERP study in economic decision making
Authors: Spapé Michiel M. , Hoggan Eve E. , Jacucci Giulio , Ravaja Niklas
Published: September 2014

The Midas touch refers to the altruistic effects of a brief touch. Though these effects have often been replicated, they remain poorly understood. We investigate the psychophysiology of the effect using remotely transmitted, precisely timed, tactile messages in an economic decision‐making game called Ultimatum. Participants were more likely to accept offers after receiving a remotely transmitted touch. Furthermore, we found distinct effects of touch on event‐related potentials evoked by (a) feedback regarding accepted and rejected offers, (b) decision cues related to proposals, and (c) the haptic and auditory cues themselves. In each case, a late positive effect of touch was observed and related to the P3. Given the role of the P3 in memory‐related functions, the results indicate an indirect relationship between touch and generosity that relies on memory. This hypothesis was further tested and confirmed in the positive effects of touch on later proposals.
Multimarket Linkages, Trade and the Productivity Puzzle
Authors: Matsushima Noriaki , Zhao Laixun
Published: September 2014

This paper examines the relationship between firms’ productivity improvement and the volume of exports, and shows that it can be sometimes negative, which seems to be an empirical puzzle. The key lies in that we simultaneously take into account intermediate retailers (i.e. vertically) and multimarket linkages (i.e. horizontally). With convex cost functions, when market conditions worsen, the manufacturer increases supply to the retailer who is larger or more efficient in trade cost.
Advanced classification of carbonate sediments based on physical properties
Authors: Insua Tania L. , Hamel Lutz , Moran Kathryn , Anderson Louise M. , Webster Jody M.
Published: September 2014

Physical properties such as bulk density (gamma ray attenuation), P‐wave velocity (primary or compressional wave acoustic velocity), electrical resistivity and magnetic susceptibility are related to characteristics of the marine sediments that, in turn, are indicative of the lithology. Non‐destructive physical properties are routinely measured during Mission Specific Platform expeditions conducted by the Integrated Ocean Drilling Program using a multi‐sensor core logger on whole cores. The goal of this study was to develop linear and non‐linear relations among physical properties and different types of carbonate sediment to identify relevant information that may aid in the classification of carbonates. The database and model presented here integrate sedimentology with physical properties data. Data were analysed using three techniques: Linear Discriminant Analysis, Random Forest and Support Vector Machines. The models that best describe the nature of the data are Random Forest and Support Vector Machines, reaching up to 79% and 74% total accuracy, respectively. This article presents an application of machine learning as a potentially useful tool for classifying sediment types, developed specifically for assisting with the challenging identification of the lithologies in coral cores. This technique can also be used for provisional core description prior to splitting, thereby enabling identification and preservation of potentially critical intervals for special analyses and studies. These methods of data analysis can also assist with sample selection for specific studies. Other applications include the interpretation of lithotypes from wireline geophysical logging data, particularly in boreholes where core recovery is poor or sampling is limited to drill cuttings.
Early assessment of patient perception of outcome in total knee replacement
Authors: Boniforti Filippo , Macaione Antonio , Gagliardi Stefano , Giangrasso Francesco , Di Marzo Davide , Giacco Francesco
Published: September 2014

Purpose: the aim of the present study was to measure patient perception in the early period after knee replacement surgery and to correlate health status with the surgery-related outcome.

Methods: thirty-eight consecutive patients who underwent total knee replacement were evaluated before surgery; at the time Radiographic evaluation was used to assess limb alignment and the Oxford Knee Score (OKS) to assess objective outcome. Health outcome was measured with the three-level version of the EuroQol – five dimension (EQ-5D-3L) selfadministered questionnaire, a standardized instrument used to measure patient’s perception of health status. Evaluation was performed before surgery, at discharge from hospital, and six weeks after surgery.

Results: the mean overall EQ-5D-3L scores were 10.23 before surgery, 8.34 at discharge from the hospital, and 6.52 at six weeks. The overall EQ-5D-3L score before surgery was greater than 8 points in 31 of the 38 patients, ranging from 5 to 8 points in 21 of the 38 patients at the discharge and greater than 8 points in six of the 38 patients six weeks after surgery. Patients with scores of over 8 points at six weeks also scored more than 10 points on the discharge assessment.

Conclusions: analysis of early patient reports of performance after TKR showed marked changes in the level of satisfaction during the first six weeks after surgery. An EQ-5D-3L score of 8 or more at follow-up should be considered a sign that the patient has not achieved satisfaction and, accordingly, should be studied in the context of a personalized follow-up schedule in order to identify as soon as possible the causes of impairment.

Level of Evidence: Level IV, prognostic case series.
Acromioclavicular joint instability: anatomy, biomechanics and evaluation
Authors: Saccomanno Maristella , De Ieso Carmine , Milano Giuseppe
Published: September 2014

Acromioclavicular (AC) joint instability is a common source of pain and disability. The injury is most commonly a result of a direct impact to the AC joint. The AC joint is surrounded by a capsule and has an intraarticular synovium and an articular cartilage interface. An articular disc is usually present in the joint, but this varies in size and shape. The AC joint capsule is quite thin, but has considerable ligamentous support; there are four AC ligaments: superior, inferior, anterior and posterior. The coracoclavicular (CC) ligament complex consists of the conoid and trapezoid ligaments. They insert on the posteromedial and anterolateral region of the undersurface of the distal clavicle, respectively. The coracoid origin of the trapezoid covers the posterior half of the coracoid dorsum; the conoid origin is more posterior on the base of the coracoid. Several biomechanical studies showed that horizontal stability of the AC joint is mediated by the AC ligaments while vertical stability is mediated by the CC ligaments. The radiographic classification of AC joint injuries described by Rockwood includes six types: in type I injuries the AC ligaments are sprained, but the joint is intact; in type II injuries, the AC ligaments are torn, but the CC ligaments are intact; in type III injuries both the AC and the CC ligaments are torn; type IV injuries are characterized by complete dislocation with posterior displacement of the distal clavicle into or through the fascia of the trapezius; type V injuries are characterized by a greater degree of soft tissue damage; type VI injuries are inferior AC joint dislocations into a subacromial or subcoracoid position. The diagnosis of AC joint instability can be based on historical data, physical examination and imaging studies. The cross body adduction stress test has the greatest sensitivity, followed by the AC resisted extension test and the O’Brien test. Proper radiographic evaluation of the AC joint is necessary. The Zanca view is the most accurate view for examining the AC joint. The axial view of the shoulder is important in differentiating a type III AC joint injury from a type IV injury.
Osteochondritis dissecans of the talus
Authors: Zanon Giacomo , Di Vico Giovanni , Marullo Matteo
Published: September 2014

Osteochondritis dissecans (OCD) is an acquired idiopathic lesion of subchondral bone that can produce delamination and sequestration with or without articular cartilage involvement and instability.

The cause of OCD is still debated: the most recognized etiology is the occurrence of repetitive micro-traumas associated with vascular impairment, causing progressive ankle pain and dysfunction in skeletally immature and young adult patients.

Ankle OCD is classically located in the medial part of the talus, while lateral and posterior involvement is less frequent.

Diagnosis of OCD, based on MRI findings, is quite straightforward; MRI examination can also be very useful for dating the defect and obtaining information about the associated bone bruise.

Osteochondritis dissecans, if not recognized and treated appropriately, may lead to secondary osteoarthritis with pain and functional limitation.

Surgical treatment is mandatory especially in young patients with unstable cartilage fragments. There are various surgical options: fixation, microfracture, or substitution using autologous chondrocyte implantation techniques.
Simulations of Mountings on Offshore Platforms in Arctic Regions
Authors: Michel Josefine , Garke Steffen , Kaeding Patrick
Published: September 2014

In the arctic offshore industry auxiliary systems are required for adequate living and working conditions. These systems comprise pipes and service modules on LNG ships as well as work and accommodation modules on offshore platforms. The object of this paper is an overview about the approach to simulate the different mounting systems on offshore/ship-structures in arctic regions: Which assumptions are made in the simulations? Which forces act on the systems? How are the results accomplished — by parameter studies, sub-model-technique? Where are the challenges located in the simulation? How can the runtime of the simulations be reduced?

In the case of pipe mountings, two different phases — installation and operation mode — as well as the cooling down of the insulating material between the two phases are considered. The result of this research topic is an automatic and parametric FE-Analysis of the structural limit state in these modes. The analysis of the twistlock system has been presented the last two years at OMAE. These systems are used to mount living and working modules on offshore platforms. The existing and new results will be discussed and evaluated. The accommodation modules are located in a containment — the so-called housing — attached to the deck. The required connection between this housing and the deck is analyzed. This analysis comprises welded and bolted connections. According to the stress results of the simulations the adequate connection is selected. These analyses are performed with the sub-model-technique in ANSYS.
Reliability Analysis of a Steel Catenary Riser With Environmental, Geometry, and Operational Uncertainties
Authors: Ma C. Y. , Alibrandi U. , Koh C. G.
Published: September 2014

Steel Catenary Riser (SCR) offers an attractive solution to deepwater floating structure due to its economical effectiveness, large diameters, high resistance to internal and external pressure, simple and robust installation methods. SCR forms a prolongation of a subsea flowline attached to a fixed platform or a floating unit in a catenary shape. Due to the relatively large motion under waves and currents, SCR lines are sensitive to dynamic effects and vulnerable to damage in deep water. They are commonly subjected to high top tension and large bending moment due to platform or FPSO movements which may lead to fatigue damage. There are many uncertainties that can affect the safety and cost-effectiveness of the SCR. Offshore design codes typically adopt empirical safety factors to account for these uncertainties but this approach does not permit the prediction of failure probability of the riser system.

To address the above issue, this paper presents the coupling of the stochastic analysis concept to the deterministic computational model for the dynamic analysis of SCR. The finite element solution is developed for hydrodynamic and structural analysis accounting for nonlinear and dynamic coupling effects. Methods for reduction of dimensionality of uncertainties are investigated to help to make the analysis computationally feasible. Uncertainty and numerical realization of specific uncertainty parameters are modeled through riser dynamics software and uncertainty analysis software. Distributions of effective tension, bending moment, and API RP 2RD stress are illustrated for a specified SCR model. The correlation effects between structural responses and random variables are investigated. In addition, the failure probability of SCR API RP 2RD stress is investigated through Monte Carlo simulations. This will help to evaluate the behavior and reliability of SCR realistically, incorporating the environmental, geometry and operational uncertainties in engineering practice.
Closed Flexible Fish Cages: Modelling and Control of Deformations
Authors: Strand Ida M. , Sørensen Asgeir J. , Volent Zsolt
Published: September 2014

Closed Flexible Fish Cages are proposed used in the sea, to meet with ecological challenges in the aquaculture industry. Earlier experiences with structural collapse of a similar concept have shown that it is crucial to secure the cage against rifts and escapes. To ensure this, a method to detect leakages and pump failure at an early stage must be developed. To detect leakages it is important to know how the bag deforms under static conditions for lower filling levels. In this paper a new method for modelling the deformed shape of the bag for decreasing filling level is proposed. Experimental data are analysed related to deformations on the bag for different filling levels, under static conditions.
Lift Characteristics of Controlling Fins of Resonance-Free SWATH
Authors: Oishi Go , Iwashita Hidetsugu , Kanda Masamitsu , Yoshida Motoki , Kihara Hajime , Kinoshita Takeshi
Published: September 2014

Speed reduction, additional resistance or slamming, which caused by the large ship motions, should be avoided for a high-speed oceangoing vessel, because of the delivery punctuality and high value of the cargo. A promising ship type for such the oceangoing vessel is the so-called “Resonance-Free SWATH (RFS)”. It has negative restoring moment due to the extraordinary small water plane area. As a consequence, the resonance peak is removed from the motion response. RFS is designed to cross 4,800 nautical miles of Pacific Ocean within 5 days punctually at a speed of 40 knots, with good seaworthiness such as no speed reduction or absolutely no slamming even when running in the rough sea of sea state 7 with significant wave height of 6–9 m.

The attitude of RFS with negative restoring moment is adjusted by four pairs of controlling fins attached to the fore and aft ends of lower hulls. In the previous works, the quasi-steady values of lift-curve slope are usually adopted in the motion equations of frequency domain. However, when working in waves, the controlling fins are not in a steady state. The lift coefficient is no longer a constant. In addition, there exist a phase lag between the movement of attack angle and the fin-generated lift.

The theoretical prediction and the experiment to analyze the phenomena of lift generation including the phase difference and the interaction among fins and lower hulls are carried out. The results show that the characteristics of fins depend on the encounter frequency. Then, the effect of lift characteristics of controlling fins on the RFS model is discussed. The results of theoretical estimation and experiment are discussed and it is observed that estimated results agree to some extent with experimental results.
Effect of Embedded Electric Sensor on the Structural Strength of Filament Wound Hybrid Composite
Authors: Ameri Sianaki Abolfazl , Evans Brian , Rasouli Vamegh , Roufail Reem , Stewart Gordon
Published: September 2014

Filament wound composites (FWC) consist of multiple layers of carbon/glass fibres within an epoxy matrix at different angles of orientation to achieve required mechanical properties. The type of hybrid composite and method of fabrication may be tailored to develop a smart pipe with embedded sensors for use in mineral exploration drill pipe applications. Experimental work and numerical simulations were performed in order to understand the effect of the filament angle-ply and how embedded sensors altered the overall mechanical structure strength of the angle-ply composite. Numerical analysis was performed using Hypersizer, to understand the stress distribution on each of the laminated layers, their angles, and the presence of a sensor on the strength of the composite’s structure. The experimental work was carried out to validate the numerical analysis results.

Experiments on two specimens are reported in this study, being with and without an embedded sensor. Eight plies were fabricated with the characteristic angle-ply of filament, wound in a rhomboid pattern. Due to the electrical conductivity of carbon fibre, the sensors’ performance was anticipated to deteriorate. Consequently a hybrid structure was designed. Glass fibre was wrapped around the sensors for isolation and the glass fibre, along with the sensors were then embedded in the carbon fibre filament wound structure. The fabricated hybrid specimens were then subjected to simple tensile tests in the lab. The mechanical strength of both specimens, with and without sensors, was compared to determine the effect of embedding the sensor within this hybrid composite.
Modeling Vortex Induced Motion in Sheared Currents
Authors: Holmes Samuel
Published: September 2014

In this paper we examine the vortex induced motions (VIM) of a spar platform in a sheared current. This study is motivated in part by the problem of using flume tanks for the simulation of platform VIM in sheared currents. To date, such experiments have not tried to reproduce the density gradients seen in the ocean in the presence of a stable sheared current. Instead, the flume tanks are kept short so that a velocity gradient introduced at one end is preserved long enough so that a sheared current exists at the model. In this paper we use computational fluid mechanics to simulate both problems. It is shown that buoyancy effects can be significant and need to be considered in the interpretation of flume tank experiments.
Derrick Structure Design and Finite Element Analysis of CPOE-16 Jack-Up
Authors: Ji Zeng , Gang Chen , Jian Mo , Hongtao Yuan , Ruijia Zhou , Chenfeng Li
Published: September 2014

Drilling derrick, acting as one of the most important structures in Jack-up Rig, is designed to accommodate drilling machines like top drive, utility winches and so on. According to the requirement of API Spec. 4F, the accuracy of the standard design ratings of each structure shall be tested by proof loading or a computer model such as Finite Element Analysis. Therefore, this thesis utilizes Finite Element Analysis software, ANSYS, to verify the design of derrick structure for CPOE-16 (No. 16 jack-up rig for China National Petroleum Offshore Engineering) jack-up based on API 4F [1], AISC Allowable Stress Design [2] and ABS MODU rules [3]. The permanent loads, live loads (variable functional loads), environmental loads (mainly wind loads) and dynamic loads will be included in the total derrick structure strength calculation with the purpose of verifying the security and reliability in all required conditions by rules and regulations. Furthermore, on the basis of analytical result, the authors focused on the adverse beams provide an optimization solution by improving the section of beams for reducing the distortion, and ultimately deal with the distorted problem.
Saturation Index Prediction Based on Taguchi Approach and Multiple Linear Regression in Oil Wells
Authors: Lima Vivianne Cristina Ferreira , de Almeida Marco Antonio Ribeiro , Machado Florence Leal , Branco Valter Antonio Monteiro
Published: September 2014

During the productive phase of an oil well, there may be jointly production of groundwater, called formation water, which has different dissolved salts which may, during production, form a solid phase (precipitate), causing partial or total obstruction of the well, due to scaling of precipitation. The main inorganic scales in oil industry are: calcium sulfate (CaSO4), barium sulfate (BaSO4), strontium sulfate (SrSO4) and calcium carbonate (CaCO3). The carbonate is precipitated due to changes in temperature, pressure and water flow associated with oil. These variations happen due to fluid displacement which originally are in equilibrium conditions to the flow conditions. As the removing process is extremely expensive and often irreversible, mathematical tools are used to predict the saline scale. This work will present three methods: software Multiscale, Multiple Linear Regression and Taguchi Approach. Those methods will help predict saline scales of CaCO3, by calculating saturation index. The other salts will not be used in this monograph. After realization of the experiments, comparing the values found in the calculation of the CaCO3 saturation index using the three methods, satisfactory results are obtained when the pressure ranges up to 20% of the experimental pressure, with a reduction in the number of experiments, using the method known as Taguchi Approach.
Trenching Considerations for Arctic Pipelines
Authors: Paulin Mike , Cocker Joseph , Humby Damien , Lanan Glenn
Published: September 2014

Offshore pipelines installed in the Arctic and other cold regions are often buried to reduce the risk of damage from ice gouging, upheaval buckling, and other loading challenges specific to the region. Pipeline burial is normally achieved through trench excavation and backfill.

Pipelines have been buried using a wide variety of technologies including conventional excavation equipment, hydraulic dredges, ploughs, mechanical trenchers, and jetters. In order to determine a preferred trenching method for a particular route, consideration must be given to a variety of factors. The water depth range and maximum trench depth required along a route are primary considerations when evaluating the various trenching technologies. These are “show stopper” route parameters, which have a direct impact on the ability to complete a particular trench.

If multiple trenching technologies satisfy the primary considerations, a variety of secondary considerations must be used to determine the preferred solution. These include parameters such as seabed geology, backfill method, seabed slopes, and environmental sensitivity. The preferred solution may not always be the only method of excavating the trench, but it may have an advantage compared to other technologies for the route under evaluation.

As developments are proposed for areas that experience relatively deep ice gouging (up to 5m), burial depth requirements will exceed the capabilities of current technologies. New technologies capable of working in deeper water, achieving greater burial depths, achieving reasonable trenching advance rates, operating in harsh environments, and trenching through variable and difficult seabed soils will be required.
Arctic Offshore Pipeline Design and Installation Challenges
Authors: Paulin Mike , DeGeer Duane , Cocker Joseph , Flynn Mark
Published: September 2014

With the oil industry’s continued quest for oil and gas in frontier offshore locations, several developments have taken place in regions characterized by seasonal ice cover including the US Beaufort, North Caspian, and Sakhalin Island. In these projects, pipeline systems have been used, which are a cost-effective, safe, and reliable mode of hydrocarbon transport.

For pipeline development in Arctic, several years of data need to be collected to support the pipeline design and construction planning, and may be required by regulations. Therefore, Arctic offshore pipeline projects generally require repetitive mapping surveys and geotechnical programs to verify design loads, soil properties, and thaw settlement potential.

The major design loads that are considered for Arctic projects include ice gouging, strudel scour, upheaval buckling as well as thaw settlement. These issues can have a significant influence on the pipeline engineering considerations such as strain based design, target burial depth requirements, cost, and safety.

While important to the design of the pipeline, these issues account for just a few of the many criteria that must be considered when routing a pipeline; criteria which can be categorized as either engineering, environmental, social, administrative, or infrastructural.

The pipelines which are currently operational in the Arctic are located in shallow water depths and close to shore but were influenced by the unique Arctic environmental loading conditions. The experience from these past projects provides a significant base for the design, and operating of future offshore arctic pipelines.

Pushing the limits to developments further offshore in deeper water will require that additional consideration be given to aspects related to pipeline design, in particular with respect to burial for protection against ice gouging.
An Improved Computational Fluid Dynamics (CFD) Model for Erosion Prediction in Oil and Gas Industry Applications
Authors: Pandya Deval , Dennis Brian , Russell Ronnie
Published: September 2014

In recent years, the study of flow-induced erosion phenomena has gained interest as erosion has a direct influence on the life, reliability and safety of equipment. Particularly significant erosion can occur inside the drilling tool components caused by the low particle loading (<10%) in the drilling fluid. Due to the difficulty and cost of conducting experiments, significant efforts have been invested in numerical predictive tools to understand and mitigate erosion within drilling tools. Computational fluid dynamics (CFD) is becoming a powerful tool to predict complex flow-erosion and a cost-effective method to re-design drilling equipment for mitigating erosion. Existing CFD-based erosion models predict erosion regions fairly accurately, but these models have poor reliability when it comes to quantitative predictions. In many cases, the error can be greater than an order of magnitude. The present study focuses on development of an improved CFD-erosion model for predicting the qualitative as well as the quantitative aspects of erosion.

A finite-volume based CFD-erosion model was developed using a commercially available CFD code. The CFD model involves fluid flow and turbulence modeling, particle tracking, and application of existing empirical erosion models. All parameters like surface velocity, particle concentration, particle volume fraction, etc., used in empirical erosion equations are obtained through CFD analysis. CFD modeling parameters like numerical schemes, turbulence models, near-wall treatments, grid strategy and discrete particle model parameters were investigated in detail to develop guidelines for erosion prediction. As part of this effort, the effect of computed results showed good qualitative and quantitative agreement for the benchmark case of flow through an elbow at different flow rates and particle sizes.

This paper proposes a new/modified erosion model. The combination of an improved CFD methodology and a new erosion model provides a novel computational approach that accurately predicts the location and magnitude of erosion. Reliable predictive methodology can help improve designs of downhole equipment to mitigate erosion risk as well as provide guidance on repair and maintenance intervals. This will eventually lead to improvement in the reliability and safety of downhole tool operation.
A Numerical Investigation Into the Impact Pressures of Different Base Forms Using SPH Method
Authors: Chen Zhen , Zou Li , Zong Zhi
Published: September 2014

In this paper, the impact pressures of two different base forms are comparatively studied using Smoothed Particle Hydrodynamics (SPH) method. It is summarized from previous works that the improved weakly compressible SPH model shows better performances than incompressible SPH model in numerical simulations of free surface flows accompany with large deformations and strong discontinuities. Such advantages are observed in numerical accuracy, stability and efficiency. The weakly compressible SPH model used in this paper is equipped with some new correction algorithms, among which include the density reinitialization algorithm and a new coupled dynamic Solid Boundary Treatment (SBT) on solid boundaries. The new boundary treatment combines the advantages of both the repulsive boundary treatment and the dynamic boundary treatment, intending to obtain more stable and accurate numerical results. A benchmark test of dam breaking is conducted to prove the reliability of the numerical model used in this paper. Two representative cases, among which one has one cavity and the other one has three cavities, are numerically investigated and compared to support the conclusion that the base form with cavities generally experience lower local and overall impact pressures than the base form of flat plate. It is found that with the application of cavities on the bottom, the peak values of the boundary pressure near central bottom significantly decrease, leading to smaller force load and better structural stability. The mechanisms of such phenomenon might be the pressure absorption effect conducted by the cavities.
The Effect on Hydrodynamic Performance of Multi-Point Moored FPSO in Swell Condition of West Africa
Authors: Gang Chen , Hongtao Yuan , Peilin Dou , Ji Zeng , Jian Zhu , Yuhan Wang
Published: September 2014

The paper respectively study the effect on hydrodynamic performances of FPSO under only swell and only wind-sea based on 3D potential theory and non-linear time domain coupled analysis method. The analysis results indicated that swell and wind-sea act as the same role in low frequency response. Swell is key factor in wave frequency response. Incident angle of swell evidently effects on mooring line tension. So it is necessary that we should consider swell and wind-sea at the same time in studying the hydrodynamic performances of FPSO in West Africa. The study offered an important reference on FPSO hydrodynamic performances analysis in West Africa.
FHSIM — Time Domain Simulation of Marine Systems
Authors: Reite Karl-Johan , Føre Martin , Aarsæther Karl Gunnar , Jensen Jørgen , Rundtop Per , Kyllingstad Lars T. , Endresen Per Christian , Kristiansen David , Johansen Vegar , Fredheim Arne
Published: September 2014

Numerical time domain simulations have proven applicable for analysing marine systems and operations, but available tools often target specific sub-problems or applications associated with a system or an operation. Such tools are also often limited in terms of extensions and usage. This has motivated the development of FhSim at SINTEF Fisheries and Aquaculture (SFA). FhSim is a software framework aimed at simulating especially marine systems in the time domain, using models described as ordinary differential equations (ODEs).

In this paper, we present the architecture and core functionality of the FhSim framework, including modelling, integration and 3D-visualisation. We also present a series of simulation cases which illustrate the different core properties of FhSim, including numerical simulations of aquaculture structures, model-based estimation of trawl nets and optimisation of energy systems in ships.
Logic Sequence Prevents Launching Devices Downhole Out of Sequence
Authors: de Lepeleire Ricardo , Rogozinski Nicolas , Rogers Hank , Ferrari Daniel
Published: September 2014

Within the oil and gas industry, significant costs are often incurred by the operating company during the well-construction phase of drilling operations. Specifically, the operators cost to drill a well can cost tens or hundreds of millions of USD. One specific area where significant changes in drilling operations have occurred is in the offshore environment, specifically operations from mobile offshore drilling units (MODUs). With the ever-increasing demand for oil and gas, operators globally have increased drilling budgets in an effort to meet forecasted demand. However, the increased budgets are often eroded or offset by increasing drilling costs. Therefore, operators are continually in search of new technology, processes, or procedures to help improve drilling operations and overall operational efficiencies.

One Latin America operator identified a common operation as a possible area where operational cost could be easily reduced through the implementation of systems that allow the manipulation of valve manifolds remotely. Additionally, operating such valve manifolds remotely enhanced operational safety for personnel, which was an equally important consideration.

This paper details the evaluation of existing equipment and procedures and a process used to develop a new remote-control system using a machine logic control (MLC) that has been designed, built, tested, and deployed successfully on MODUs operating in Latin America.