bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of a comprehensive geriatric assessment on decision‐making in older patients with hematological malignancies
Authors: Garric Marie , Sourdet Sandrine , Cabarrou Bastien , Steinmeyer Zara , Gauthier Martin , Ysebaert Loïc , Beyne‐Rauzy Odile , Gerard Stephane , Lozano Stephanie , Brechemier Delphine , Filleron Thomas , Mourey Loïc , Balardy Laurent
Published: December 2020

Objective

Hematological treatment decisions in older adults with hematological malignancies are complex. Our objective is to study the impact of a comprehensive geriatric assessment on hematological treatment decision in older patients and the factors associated with change in treatment plan.

Methods

We conducted a cross‐sectional analysis of patients aged 65 years and above with hematological malignancies, hospitalized between 2008 and 2019 at the University Cancer Institute of Toulouse. They were assessed by a geriatrician/nurse team using a comprehensive geriatric assessment (CGA). A penalized logistic regression model with elastic net regularization was used to identify factors associated with change in hematological treatment plan.

Results

A total of 424 patients were included. Main hematological malignancies were lymphoma (36.1 %), acute myeloid leukemia (26.9 %) and myelodysplastic syndrome (19.8%). Change in hematological treatment plan was suggested after CGA for 92 patients (21.7%). Factors associated with change in treatment plan were functional impairment according to ADL and IADL scale, mobility impairment, the presence of comorbidity defined by the Charlson score >1 and increasing age.

Conclusion

A CGA has a significant impact on hematological treatment decision in older patients. Functional and mobility impairment, comorbidities and age are predictive factors of change in treatment plan.
Histology and ultrastructure of ink gland and melanogenesis in the cuttlefish Sepia pharaonis
Authors: Jiang Maowang , Xue Ruiping , Chen Qiang , Zhan Pingping , Han Qingxi , Peng Ruibing , Jiang Xiamin
Published: December 2020

The ink gland in cephalopods is a modified part of the digestive tract that generates melanin used in defense activities against predators. In the present study, we document the histological structure of the ink gland of the cuttlefish Sepia pharaonis following light microscopy (LM) and transmission electron microscopy (TEM) examinations. Based on the observations, we infer the series of cellular events leading to the formation and secretion of melanin. LM observations revealed that the cuttlefish ink gland was cord‐like, and could be separated into two distinct regions with different functions, based on markedly different cellular and biochemical characteristics. The region with the function of secreting ink was the epithelial cell region (i.e., mature ink gland cells) and was mainly composed of melanosomes, rough endoplasmic reticulum, Golgi apparatus, and mitochondria. Conversely, the connective tissue region was the site of formation of cells and energy supply. In addition, the most probable sequence of activities from melanogenesis to the release, based on TEM observations, is as follows: (a) formation of a matrix of opaque electronic substances (melanin precursors); (b) melanization in the precursor matrix to form melanin‐like particles; (c) further melanin granule development and enlargement, and gradual intensifying of the hue; (d) production of melanin granules (melanosomes) in the precursor matrix; (e) binding of melanosomes to the cytoskeleton and migration to the cell surface; (f) fusion of melanosomes with the cell membrane at the apical pole, and discharge of melanin granules into intercellular spaces or lumen by exocytosis or cell fragmentation. We also investigated how the process of continuous ink release influences ink gland histology and ultrastructure. Inking stimulation induced the release of large amounts of ink by epithelial cells, and was associated with cell disorganization, and severe cellular vacuolization, in addition to severe organelle damage.
NDUFA4L2 in smooth muscle promotes vascular remodeling in hypoxic pulmonary arterial hypertension
Authors: Liu Yun , Nie Xiaowei , Zhu Jinquan , Wang Tianyan , Li Yanli , Wang Qian , Sun Zengxian
Published: December 2020

Pulmonary arterial hypertension (PAH) is characterized by a progressive increase in pulmonary vascular resistance and obliterative pulmonary vascular remodelling (PVR). The imbalance between the proliferation and apoptosis of pulmonary artery smooth muscle cells (PASMCs) is an important cause of PVR leading to PAH. Mitochondria play a key role in the production of hypoxia‐induced pulmonary hypertension (HPH). However, there are still many issues worth studying in depth. In this study, we demonstrated that NADH dehydrogenase (ubiquinone) 1 alpha subcomplex 4 like 2 (NDUFA4L2) was a proliferation factor and increased in vivo and in vitro through various molecular biology experiments. HIF‐1α was an upstream target of NDUFA4L2. The plasma levels of 4‐hydroxynonene (4‐HNE) were increased both in PAH patients and hypoxic PAH model rats. Knockdown of NDUFA4L2 decreased the levels of malondialdehyde (MDA) and 4‐HNE in human PASMCs in hypoxia. Elevated MDA and 4‐HNE levels might be associated with excessive ROS generation and increased expression of 5‐lipoxygenase (5‐LO) in hypoxia, but this effect was blocked by siNDUFA4L2. Further research found that p38‐5‐LO was a downstream signalling pathway of PASMCs proliferation induced by NDUFA4L2. Up‐regulated NDUFA4L2 plays a critical role in the development of HPH, which mediates ROS production and proliferation of PASMCs, suggesting NDUFA4L2 as a potential new therapeutic target for PAH.
Vigour‐related traits and immunity in hybrids of evolutionary divergent cyprinoid species: advantages of hybrid heterosis?
Authors: Šimková Andrea , Janáč Michal , Hyršl Pavel , Krasnovyd Vadym , Vetešník Lukáš
Published: December 2020

Hybrid advantage, described as the superiority of hybrids in some traits over their parents and termed the “heterosis effect,” is widely documented in the case of reciprocal crosses of parental species (i.e., hybrids representing the F1 generation). In fish, high survival, fast growth and better health status have been widely documented in F1 hybrids. Nonetheless, the effects of interspecific hybridization on vigour, physiology and immunity‐related traits in fish are largely unknown, especially concerning native systems of coexisting parental and hybrid genomes in the same habitat. The present study examined the potential physiological and immune aspects of hybrid heterosis by comparing condition status (measured especially by indexes), haematological profile, glucose concentration and selected parameters of non‐specific and specific immunity between the evolutionarily divergent non‐congeneric cyprinoid species Abramis brama and Rutilus rutilus and their hybrids representing the F1 generation, all of them caught in nature. Clear differences were documented for vigour‐related, physiological and immune parameters between the two divergent species. Hybrids generally tended to express intermediate characters of the measured traits, likely generated by the evolutionary divergence of the hybridizing species; nonetheless, for some traits, hybrids exhibited a character that was more similar to one parental species than to the other. This was interpreted as the heterozygote advantage for F1 hybrids. It is suggested that a maternally inherited genetic background may potentially influence the expression of some branches of non‐specific immunity or other aspects related to the fish health status.
Alveolar progenitor cells and the origin of lung cancer
Authors: Sainz de Aja J. , Dost A. F. M. , Kim C. F.
Published: December 2020

Lung Cancer is the leading cause of cancer‐related deaths worldwide. This is mainly due to late diagnosis and therefore advanced stage of the disease. Understanding the cell of origin of cancer and the processes that lead to its transformation will allow for earlier diagnosis and more accurate prediction of tumour type, ultimately leading to better treatments and lower patient morbidity. In this review, we focus on alveolar type 2 (AT2) cells as the cell of origin of lung adenocarcinoma (LUAD), the most common type of lung cancer. We first elaborate on the different oncogenes that are associated with LUAD and other lung cancers. After, we lay out in detail what is known about AT2 biology, to further delve into AT2 cells as cell of origin for adenocarcinoma. Understanding the precursors of LUAD and identifying the molecular changes during its progression will allow for earlier detection and better molecular targeting of the disease in early stages.
Quantitative Analysis on Risk Influencing Factors in the Jiangsu Segment of the Yangtze River
Authors: Zhang Jinfen , He Anxin , Fan Cunlong , Yan Xinping , Soares C. Guedes
Published: December 2020

Quantitative risk influencing factors (RIFs) are proposed, using the Conjugate Bayesian update approach to analyze 945 collision accidents and incidents cases from the Jiangsu Segment of the Yangtze River over five years from 2012 to 2016. The accident probability is compared under a pairwise comparison mode in order to reflect the relative risk between accidental situations. The Bayesian update mode is constructed to quantitatively evaluate the relative importance of different RIFs. The riskiest segment of Jiangsu Waterways as well the main causations of collisions are identified based on the distributions of collision risk in the six segments of the waterways. The results can support managers to develop the most effective policies to mitigate the collision risk.
COPII genes SEC31A/B are essential for gametogenesis and interchangeable in pollen development in Arabidopsis
Authors: Liu Xiaoyu , Tong Mengjuan , Zhang Aiwei , Liu Mei , Zhao Bingchun , Liu Zhaojiao , Li Zhouyue , Zhu Xu , Guo Yi , Li Rui
Published: December 2020

In eukaryotes, coat protein complex II (COPII) vesicles mediate anterograde traffic from the endoplasmic reticulum to the Golgi apparatus. Compared to yeasts, plants have multiple COPII coat proteins; however, the functional diversity among them is less well understood. SEC31A and SEC31B are outer coat proteins found in COPII vesicles in Arabidopsis. In this study, we explored the function of SEC31A and compared it with that of SEC31B from various perspectives. SEC31A was widely expressed, but at a significantly lower level than SEC31B. SEC31A‐mCherry and SEC31B‐GFP exhibited a high co‐localization rate in pollen, but a lower rate in growing pollen tubes. The sec31a single mutant exhibited normal growth. SEC31A expression driven by the SEC31B promoter rescued the pollen abortion and infertility observed in sec31b. A sec31asec31b double mutant was unavailable due to lethality of the sec31asec31b gametophyte. Transmission electron microscopy revealed that one quarter of male gametogenesis was arrested at the uninuclear microspore stage, while confocal laser scanning microscopy showed that 1/4 female gametophyte development was suspended at the functional megaspore stage in sec31a‐1/+sec31b‐3/+ plants. Our study highlights the essential role of SEC31A/B in gametogenesis and their interchangeable functions in pollen development.
The Great Trade Collapse and the determinants of UK export margins: A cohort‐ and firm‐level matching approach
Authors: Douch Mustapha , Edwards Terence Huw , Van Hove Jan , Kren Janez
Published: December 2020

This paper uses a detailed data set of UK firms between 2005 and 16, to investigate how export participation and export values were affected by the aftermath of the 2008 crisis, and particularly the post‐crisis recovery period of 2011–16. Viewing the post‐crisis period as a treatment compared to before the crisis, we compare firm export propensity and export values using a propensity score matching approach. We conclude that the underlying relationships between size, productivity, creditworthiness and exports remained remarkably consistent throughout the period. After correcting for TFP and credit scores, we find relatively constant export propensity across the whole time period, except for younger firms in services industries, whose export propensity increased. Our results suggest that the slowdown in trade in this period has not been attributable to a change in underlying firm export behaviour.
American cutaneous leishmaniasis associated with degradation of native forest, regardless of economic, social and infrastructure vulnerability
Authors: Caldart Eloiza Teles , Sevá Anaiá da Paixão , Pinto‐Ferreira Fernanda , Pereira Pachoal Aline Ticiani , de Oliveira Juliana Silva , Cortela Isadora de Britto , Bernardes Juliana Correa , Freire Roberta Lemos , Mistsuka‐Breganó Regina , Navarro Italmar Teodorico
Published: December 2020

American cutaneous leishmaniasis (ACL) is a notifiable dermatozoonosis with relevant morbidity. The present study aimed to evaluate the epidemiological aspects of cases of ACL reported in Northern Paraná (2007–2016), as well as to georeference and analyse the influence of economic, social and environmental variables. Data from ACL notification forms were obtained and the patients' houses were georeferenced. Descriptive statistics, calculations of disease incidence and proportion of vegetation cover by municipality, spatial analysis, multiple linear regression and vulnerability analysis by census sector (CS) were performed. One thousand four hundred fifty‐one cases of ACL were reported in the 89 municipalities of four regional health (RH). The average incidence of cases per 10,000 inhabitants was as follows: 11.58, 8.79, 4.92 and 4.03 in 18thRH, 15thRH, 16thRH and 17thRH. Peaks of incident cases were observed in 2008, 2012 and 2015. There was a statistically significant difference between the HR when comparing the proportions of the variables gender, age, education level, area of residence, clinical form, diagnostic criteria, response to treatment and drug used in case of failure. It was observed that the lower the proportion of remaining Atlantic Forest, the greater the incidence of ACL in the municipality. With regard to clusters analysis, treatment abandonment clusters were observed in the 15thRH and mucous form clusters were observed in the 15thRH, 16thRH and 17thRH. The vulnerability analysis by CS allowed us to observe a statistically significant difference in all vulnerability indicators: economic and social in 15thRH and 17thRH; home infrastructure in 15thRH and 18thRH, urban infrastructure in 15thRH and 18thRH and compound vulnerability index in 15thRH and 18thRH. However, the most vulnerable areas did not always have the highest number of cases. The data presented demonstrate that preventive and health education measures must be mainly directed to areas of greater degradation of native forest; regardless of the vulnerability situation.
Using Reinforcement Learning to Estimate Human Joint Moments From Electromyography or Joint Kinematics: An Alternative Solution to Musculoskeletal-Based Biomechanics
Authors: Wu Wen , Saul Katherine R. , Huang He (Helen)
Published: December 2020

Reinforcement learning (RL) has potential to provide innovative solutions to existing challenges in estimating joint moments in motion analysis, such as kinematic or electromyography (EMG) noise and unknown model parameters. Here, we explore feasibility of RL to assist joint moment estimation for biomechanical applications. Forearm and hand kinematics and forearm EMGs from four muscles during free finger and wrist movement were collected from six healthy subjects. Using the proximal policy optimization approach, we trained two types of RL agents that estimated joint moment based on measured kinematics or measured EMGs, respectively. To quantify the performance of trained RL agents, the estimated joint moment was used to drive a forward dynamic model for estimating kinematics, which was then compared with measured kinematics using Pearson correlation coefficient. The results demonstrated that both trained RL agents are feasible to estimate joint moment for wrist and metacarpophalangeal (MCP) joint motion prediction. The correlation coefficients between predicted and measured kinematics, derived from the kinematics-driven agent and subject-specific EMG-driven agents, were 98% ± 1% and 94% ± 3% for the wrist, respectively, and were 95% ± 2% and 84% ± 6% for the metacarpophalangeal joint, respectively. In addition, a biomechanically reasonable joint moment-angle-EMG relationship (i.e., dependence of joint moment on joint angle and EMG) was predicted using only 15 s of collected data. In conclusion, this study illustrates that an RL approach can be an alternative technique to conventional inverse dynamic analysis in human biomechanics study and EMG-driven human-machine interfacing applications.
Acoustic Energy Balance During the Onset, Growth, and Saturation of Thermoacoustic Instabilities
Authors: Gaudron R. , Yang D. , Morgans A. S.
Published: December 2020

Thermoacoustic instabilities can occur in a wide range of combustors and are prejudicial since they can lead to increased mechanical fatigue or even catastrophic failure. A well-established formalism to predict the onset, growth and saturation of such instabilities is based on acoustic network models. This approach has been successfully employed to predict the frequency and amplitude of limit cycle oscillations in a variety of combustors. However, it does not provide any physical insight in terms of the acoustic energy balance of the system. On the other hand, Rayleigh's criterion may be used to quantify the losses, sources and transfers of acoustic energy within and at the boundaries of a combustor. However, this approach is cumbersome for most applications because it requires computing volume and surface integrals and averaging over an oscillation cycle. In this work, a new methodology for studying the acoustic energy balance of a combustor during the onset, growth and saturation of thermoacoustic instabilities is proposed. The two cornerstones of this new framework are the acoustic absorption coefficient Δ and the cycle-to-cycle acoustic energy ratio λ, both of which do not require computing integrals. Used along with a suitable acoustic network model, where the flame frequency response is described using the weakly nonlinear Flame Describing Function (FDF) formalism, these two dimensionless numbers are shown to characterize: 1) the variation of acoustic energy stored within the combustor between two consecutive cycles, 2) the acoustic energy transfers occurring at the combustor's boundaries, and 3) the sources and sinks of acoustic energy located within the combustor. The acoustic energy balance of the well-documented Palies burner is then analyzed during the onset, growth and saturation of thermoacoustic instabilities using this new methodology. It is demonstrated that this new approach allows a deeper understanding of the physical mechanisms at play. For instance, it is possible to determine when the flame acts as an acoustic energy source or sink, where acoustic damping is generated, and if acoustic energy is transmitted through the boundaries of the burner.
Numerical and Analytical Investigation of Heat Transfer Mechanisms and Flow Phenomena in an Intermediate Pressure Steam Turbine Blading During Startup
Authors: Bohn Dieter , Betcher Christian , Kusterer Karsten , Weidtmann Kristof
Published: December 2020

As a result of an ever-increasing share of volatile renewable energies on the worldwide power generation, conventional thermal power plants face high technical challenges in terms of operational flexibility. Consequently, the number of startups and shutdowns grows, causing high thermal stresses in the thick-walled components and thus reduces lifetime and increases product costs. To fulfill the lifetime requirements, an accurate prediction and determination of the metal temperature distribution inside these components is crucial. Therefore, boundary conditions in terms of local fluid temperatures as well as heat transfer coefficients (HTCs) with sufficient accuracy are required. As modern numerical modeling approaches, like 3D-conjugate-heat-transfer (CHT), provide these thermal conditions with a huge calculation expense for multistage turbines, simplified methods are inevitable. Analytical heat transfer correlations are thus the state-of-the-art approach to capture the heat transport phenomena and to optimize and design high efficient startup curves for flexible power market. The objective of this paper is to understand the predominant basic heat transfer mechanisms such as conduction, convection, and radiation during a startup of an intermediate pressure (IP) steam turbine stage. Convective heat transport is described by means of heat transfer coefficients as a function of the most relevant dimensionless, aero-thermal operating parameters, considering predominant flow structures. Based on steady-state and transient CHT simulations, the heat transfer coefficients are derived during startup procedure and compared to analytical correlations from the literature, which allow the calculation of the heat exchange for a whole multistage in an economic and timesaving way. The simulations point out that the local convective heat transfer coefficient generally increases with increasing axial and circumferential Reynolds' number and is mostly influenced by vortex systems such as passage and horseshoe vortices. The heat transfer coefficients at vane, blade, hub, and labyrinth-sealing surfaces can be modeled with a high accuracy using a linear relation with respect to the total Reynolds' number. The comparison illustrates that the analytical correlations underestimate the convective heat transfer by approximately 40% on average. Results show that special correlation-based approaches from the literature are a particularly suitable and efficient procedure to predict the heat transfer within steam turbines in the thermal design process. Overall, the computational effort can be significantly reduced by applying analytical correlations while maintaining a satisfactory accuracy.
Low-Order Modeling to Investigate Clusters of Intrinsic Thermoacoustic Modes in Annular Combustors
Authors: Fournier Guillaume J. J. , Haeringer Matthias , Silva Camilo F. , Polifke Wolfgang
Published: December 2020

The intrinsic thermoacoustic (ITA) feedbackloop constitutes a coupling between flow, flame and acoustics that does not involve the natural acoustic modes of the system. One recent study showed that ITA modes in annular combustors come in significant number and with the peculiar behavior of clusters, i.e. several modes with close frequencies. In the present work, an analytical model of a typical annular combustor is derived via Riemann invariants and Bloch theory. The resulting formulation describes the full annular system as a longitudinal combustor with an outlet reflection coefficient that depends on frequency and the azimuthal mode order. The model explains the underlying mechanism of the clustering phenomena and the structure of the clusters associated with ITA modes of different azimuthal orders. In addition, a phasor analysis is proposed, which encloses the conditions for which the 1D model remains valid when describing the thermoacoustic behavior of an annular combustor.
Simplified Realization of Zero Phase Error Tracking
Authors: Tomizuka Masayoshi , Sun Liting
Published: December 2020

Zero phase error tracking (ZPET) control has gained popularity as a simple yet effective feedforward control method for tracking time varying desired trajectories by the plant output of a continuous time transfer function of relative order greater than or equal to two. In this paper, we will note that the sampling zeros of the zero-order hold equivalent of chain of integrators, 1/sn, are configured for natural realization of zero phase error tracking. This property is exploited to realize a simplified realization of zero phase error tracking control for chain of integrators. The property can also be utilized for general transfer functions when the sampling period for digital control is small. The effectiveness of the proposed approach for general transfer functions is demonstrated by simulations.
On the Use of a Buoyancy Parameter for Distinguishing Deteriorated From Normal Heat Transfer in Upward Flows at Supercritical Pressures
Authors: Kline Nathan , Tavoularis Stavros
Published: December 2020

An extensive analysis of two versions of a buoyancy parameter as supercritical heat transfer deterioration (DHT) identifiers was conducted for large databases obtained in carbon dioxide flowing through three electrically heated tubes with internal diameters equal to 4.6, 8.0, and 22.0 mm and in Refrigerant R134a through an 8.0 mm tube. For the first time, buoyancy parameter profiles along each tube were considered for wide ranges of closely incremented operating conditions. The occurrence of DHT in each test section was first assessed confidently by observation of wall temperature profiles and comparison of measurements with wall temperature predictions of a correlation for normal heat transfer (NHT). The objective of this work was to determine whether a universal buoyancy parameter threshold could be used as a means for identifying DHT in a test section. It was found that correction factors were required for both parameters to account for an observed shift of the threshold for DHT occurrence, as the mass flux was changed. The resulting threshold for one of the buoyancy parameters identified correctly DHT for cases having a mass flux up to a certain value, but failed to do so for cases with a higher mass flux.
A Multifidelity Aero-Thermal Design Approach for Secondary Air Systems
Authors: Amirante Dario , Adami Paolo , Hills Nicholas J.
Published: December 2020

The paper presents a multidisciplinary approach for aero-thermal and heat transfer analysis for internal flows. The versatility and potential benefit offered by the approach are described through the application to a realistic low pressure turbine assembly. The computational method is based on a run time code-coupling architecture that allows mixed models and simulations to be integrated together for the prediction of the subsystem aero-thermal performance. In this specific application, the model is consisting of two rotor blades, the embedded vanes, the interstage cavity, and the solid parts. The geometry represents a real engine situation. The key element of the approach is the use of a fully modular coupling strategy that aims to combine (1) flexibility for design needs, (2) variable level of modeling for better accuracy, and (3) in memory code coupling for preserving computational efficiency in large system and subsystem simulations. For this particular example, Reynolds averaged Navier–Stokes (RANS) equations are solved for the fluid regions and thermal coupling is enforced with the metal (conjugate heat transfer, CHT). Fluid–fluid interfaces use mixing planes between the rotating parts while overlapping regions are exploited to link the cavity flow to the main annulus flow as well as in the cavity itself for mapping of the metal parts and leakages. Metal temperatures predicted by the simulation are compared to those retrieved from a thermal model of the engine, and the results are discussed with reference to the underlying flow physics.
Risk Perception Oriented Autonomous Ship Navigation in AIS Environment
Authors: Zhang Ruolan , Furusho Masao
Published: December 2020

Due to the quality and error of the data itself, historical automatic identification system (AIS) data was insufficient used to predict navigation risk at sea, but it adequately used to train decision-making neural networks. This paper presents a real AIS ship navigation environment with a rule-based and a neural-based decision processes with frame motion and training the decision network using a deep reinforcement learning algorithm. Rule-based decision-making has several applications in the field of adaptive systems, expert systems, and decision support systems, it also including general ship navigation which regulated by the convention on the international regulations for preventing collisions at sea (COLREGs). However, if someone intend to achieve full unmanned ship navigation without any remote control at the open sea, a rule-based decision-making system cannot be implemented alone. With the growing amount of data, complex sea environment, different collision scenarios, the agent-based decision has become an important role in transportation. For ships, combined rule-based and neural-based decision-making is the only option. It has become progressively challenging to satisfy autonomous decision-making development requirements. This study uses deep reinforcement learning to evaluate the performance of decision-making efficiency under different AIS data input shapes. The results show that the decision neural network trained with AIS data has good robustness and a high ability to achieve collision avoidance. Furthermore, using the same methodology, include instructive guidance for processing radar, camera, ENC, etc., respond to different risk perception tasks in different scenarios. It has important implications for fully unmanned navigation.
Parametric Analysis of Steel-Tube Umbilical Armor Pots
Authors: Geremias Toni Fernando , de Arruda Martins Clóvis , Provasi Rodrigo , Morini Rafael Giovane
Published: December 2020

Armor pots are mechanical devices employed in the offshore oil production to anchor armor wires/steel tubes of an umbilical cable. In epoxy-based armor pots, this anchoring is obtained through the interaction between the resin and the tensile armors/steel tubes and also through the capstan effect from geometric variations, such as radius and lay angle changes. In this context, friction plays a fundamental role in the anchoring capacity and is mainly affected, among other factors, by the intensity of resin thermal contraction, which generates positive pressure at the contact interfaces, and also by the friction coefficient. Therefore, this works presents an extensive parametric analysis of the resin thermal contraction and of the friction coefficient performed through the finite element method with the objective of understanding their qualitative and quantitative influence at the anchoring capacity of a steel-tube umbilical armor pot. In recent years, the authors published fully three-dimensional finite element models of armor pots. In order to accomplish the present work, several enhancements were performed in the aforementioned models. The main development is an innovative methodology for the resin mesh generation, ensuring mapped elements at the interfaces with steel tubes, resulting in a smoother contact representation. At the same time, this methodology is computationally advantageous by allowing larger element sizes at the remaining resin volume without loss of quality in the representation.
A 6-DOF Ship-Borne Antenna Platform With Large Orientation Workspace
Authors: He Yuhang , Li Weijia , Wu Yaozhong , Wu Jinbo , Cheng Zhiyuan
Published: December 2020

Compared with traditional antenna platform with two axes, Stewart platform can search airspace with no tracking blind district. And the advantages of high accuracy, high stiffness and high load-weight ratio also make it be a better solution for antenna platforms. This paper designed a 6-DOF ship-borne antenna platform based on the Stewart platform to overcome the difficulties that to realize a large orientation workspace (azimuth range is from 0° to 360°, pitch range is from 0° to 100°) under the compact dimensions of parallel mechanisms. A novel joint structure has been proposed which can provide a larger rotation angle than common Hooke joints to realize the large orientation workspace without the inter-mechanism interference. In addition, this paper defined the concept of working height and working radius then proposed a trajectory based on that to obtain the complete pose (translation and orientation) of antenna platform by azimuth and pitch angles. After that, the particle swarm optimization algorithm is employed to seek the optimal geometrical design parameters. A prototype of the 6-DOF ship-borne antenna platform adopted the particle swarm optimization results has been constructed. And the results show that it not noly meets the design requirements, but also provides a good performance.
Numerical Evaluation on Lateral Impact Resistance of Thermoplastic Composite Pipes in Terms of Internal Pressure Capacity
Authors: Wang J. , Shi C. , Fu G. , Liu Z. , Bao X. , Li H.
Published: December 2020

Subsea pipelines are prone to be damaged by the falling objects from ships or offshore platforms, which may result in economic losses and pollution. The dimensions of dent were commonly used to evaluate the impact resistance of pipes made from carbon steel. Thermoplastic composite pipes (TCPs), due to their superior properties including corrosion resistance, thermal insulation, fast installation, etc., are increasingly used as the subsea pipelines. The TCP is made from thermoplastic resins and reinforced by continuous fibers. Because of the brittle nature of carbon fibers and glass fibers, the dimensions of dent are not suitable for assessment of impact resistance of a TCP. In the present work, a procedure was proposed using the internal pressure capacity as an indicator to evaluate the lateral impact resistance of a TCP. First, the internal pressure capacity of an intact TCP was evaluated. Second, a quasi-static simulation was conducted by applying a lateral compression force on the intact TCP using a rigid ball, until one of the composite plies in the reinforcement layer failed. The quasi-static simulation provided an initial estimate of the minimum energy that causes the start of damage of the TCP. Third, the impact simulations were performed by using a rigid ball hitting the TCP and, then, the internal pressure capacity of the damaged TCP was evaluated. Finally, the internal pressure capacity of the damaged pipe, compared with that of the intact pipe, was used as an indicator to evaluate the lateral impact resistance of the TCP. In this study, a glass-fiber reinforced polyethylene (PE) pipe of an inner diameter of 150 mm was modeled by ABAQUS to illustrate the procedure. A theoretical method was proposed to calculate the impact energy of a dropped object in a shallow water. The example studied in the present work showed that the modeled TCP was not strong enough to survive the lateral impact caused by the dropped object and should be buried to a certain depth beneath the seabed if used as a subsea pipeline.
Software Application Based on Subsea Engineering Design Codes
Authors: Gullaksen Joannes
Published: December 2020

Development of software application for subsea engineering design and analysis is to a large extent based on codes and standards used in the offshore industry when considering subsea pipelines. In this paper a software is described which main purpose is to facilitate the design and analysis process and such that results and documentation are automatically generated to increase quality of documentation. Current scope is a standard calculation tool covering different aspects of design in compliance with relevant offshore codes. A modularization technique is used to divide the software system into multiple discrete and independent modules based on offshore codes, which are capable of carrying out task(s) independently. All modules in range operate from a project model that is accessed directly by other modules for analysis and performance prediction and allows design changes to flow through automatically to facilitate smooth communication and coordination between different design activities. All the modules have a number of common design features. The quality of an implementation of each offshore code in independent software modules is measured by defining the level of inter-dependability among modules and their interaction among them, and by defining the degree of intra-dependability within elements of a module. This modularization technique also includes other benefits, such as ease of maintenance and updates. The improvements are related to the objectives of a state-of-the-art procedure of performing engineering, design and analysis by use of offshore codes implemented in a software application. The application is developed in .NET C# language with MS Visual Studio Technology that provides a powerful graphical user interface well integrated in windows environment.
Integrity Management for Steel Catenary Risers With Design Life of 30 Years
Authors: Song Hao , Yu Chenteh Alan , Cheng Yongming , Hou Jing
Published: December 2020

The riser is a critical element in a subsea production system for transporting hydrocarbons from the seafloor to the surface. The track record of existing riser systems worldwide has shown that risers tend to be designed conservatively to accommodate dynamic loads, strength and fatigue requirements, and corrosion/erosion provision needs. Among all the riser types, the steel catenary riser (SCR) is the most installed riser configuration for deepwater oil and gas production worldwide in the last two decades. This is mainly because of their simple configuration and relatively low manufacturing and installation cost.

As riser technology advances, SCRs are designed to tackle more challenging environments and longer service lives. For the riser life extension applications, regulatory bodies prefer riser operations to be managed through an integrity management program, demonstrating that a robust framework with detailed records on the conditions of the risers is in place. This paper studies an integrity management program for SCRs with a 30-year design life in a harsh environment.

The planned riser integrity management program is based on successful industry practice and the newly published riser integrity management standard API RP 2RIM [4]. It starts with a review of the riser design basis and as-built data, continuing with key field data measurement and production fluid sampling. A digital model, continuously calibrated with the measured data, is established to assess the integrity of the riser system.

Key physical quantities are selected to monitor the structural health of the SCRs, including vessel motion measurement, measurement of SCR top hang-off angles and tensions, and full water column current measurement. The relationship between the measurement data and the riser strength and fatigue performance is established. Details of the riser integrity assessment in a digital model utilizing the measurement data are presented. The implemented proposed riser integrity management program is expected to provide a more focused and efficient method with a higher level of confidence in operating the SCRs during the design life and potentially beyond.
Fatigue Performance of Thick Section Titanium Grade 29 Girth Welds
Authors: Rombado Gabriel , Baker David A. , Haldorsen Lars M. , Macdonald Kenneth , Walker Heath , Caldwell Chris , He Binyan , Johnston Carol
Published: December 2020

Design of Steel Catenary Risers (SCRs) requires the use of specialized connection hardware to mitigate the high dynamic bending moments at the hang-off location induced by host floater motion. Reliability of this connection hardware is imperative, especially in those applications involving high tension loads, high pressure and elevated fluid temperature. One option for connection hardware is a monolithic, metallic tapered stress joint. Because of its inherent density, strength, and stiffness properties, steel is not well suited for these applications due to excessive stress joint length and weight requirements. Titanium Grade 29 has been identified as an attractive material candidate for demanding service applications due to its unique mechanical properties including increased flexibility, excellent fatigue performance and corrosion resistance to sour fluids. This technology is well established in the offshore industry and utilized in over 60 SCR installations with operating lives exceeding 20 years of continuous subsea operation.

Large titanium stress joints (TSJs) for deep-water applications are typically not fabricated as a single piece due to titanium ingot volume limitations thus making one or more intermediate girth weld(s) necessary to satisfy the overall length requirements. Fatigue testing of 38 mm (1.5-in) wall thickness girth welds, utilizing an optimized GTAW welding procedure to limit defect sizes to sub-millimeter, has previously been performed in seawater (OD exposure) under cathodic protection potentials and sour service (ID exposure) under galvanic potentials. Fatigue testing results fully verified the vendor S-N fatigue design curve, in addition, no appreciable differences in fatigue performance in environments were observed allowing project-specific testing to be limited to in-air testing.

This paper presents in-air fatigue testing results of 51 mm (2.0-in) wall thickness Grade 29 girth welds, using the same optimized welding procedure, to assess thickness size effect on the vendor S-N fatigue design curve. Verification of the vendor fatigue design curve was demonstrated by testing curved dog-bone specimens, extracted longitudinally across the girth weld, with production level surface finishes on inner and outer surfaces in-air up to a predefined S-N fatigue target curve with 95% confidence level.
Using Isotropic and Anisotropic Models to Determine Solar Module Tilt to Maximize Incident Energy and PV Electricity Output on the Alaska North Slope
Authors: Wurthmann Kurt
Published: December 2020

The Alaska North Slope is a pristine and fragile arctic environment that needs protection. The present article illustrates the application of isotropic and anisotropic models for predicting solar radiation on photovoltaic (PV) modules (and, hence, potential electricity output) for different angles of inclination (or tilt) in Utqiagvik Alaska. The anisotropic model is shown to provide higher, albeit more accurate, predictions of solar radiation since it includes all of the measures used in the isotropic model, but provides a more comprehensive representation of the diffuse component. Specifically, the anisotropic model includes not only the isotropic part of diffuse radiation, but also the circumsolar and horizon brightening parts. A PV array angle of tilt of 55 degrees is shown to provide the greatest total amount of incident solar radiation for the entire year, based on both the isotropic and anisotropic models. However, both models also indicate that angles of tilt that are steeper than 55 degrees result in slightly greater amounts of incident solar radiation during the late-winter, early-spring, and mid-fall months; while angles of tilt that are flatter than 55 degrees result in slightly greater amounts of incident solar radiation during the summer and early-fall months. It is shown that a PV system with a moderately sized array, tilted at the fixed angle of 55 degrees, could provide more than 50 percent of the total annual electricity needs for homes in Utqiagvik Alaska.
Investigation of a Novel Wave Energy Generator Using Dielectric Elastomer
Authors: Jiang Changqing , Chiba Seiki , Waki Mikio , Fujita Koji , el Moctar Ould
Published: December 2020

The type of electroactive polymer, known as dielectric elastomers, has shown considerable promise for harvesting energy from environmental sources such as ocean waves, wind, and human motions, etc. The high energy density and conversion efficiency of dielectric elastomers (DEs) can allow for very simple and robust “direct drive” generators. In such generators, a DE transducer is directly driven by the up and down motions of waves. These generators can be simple, low-cost and robust. The efficiency of a wave energy convertor using DEs was confirmed by our previous experimental work.

In this study, a wave energy convertor using DEs was numerically investigated as a moored floating body. First, the numerical model is validated against existing benchmark experiments. Then the moored floating body is numerically modelled, and the simulated results are compared to physical wave tank tests. The analyzed conditions vary from single body, two bodies with different intervals, and three bodies. The fluctuation, energy absorption efficiency, as well as the influence of multiple moored floating bodies on each other are discussed. The purpose of present work is to clarify the influence of floating body intervals and number of floating bodies on the motions, the mooring tensions, as well as the power generation efficiencies for a plurality of floating bodies arranged in a series in head seas. This kind of optimal arrangement is expected to be popularized in the future, which may contribute to the increasing demand of renewable energy solutions.
Numerical Analysis of a Floating Fish Cage With Feeding Systems
Authors: Li Lin , Bruset Mathias , Ong Muk Chen , Wu Xiaopeng
Published: December 2020

A modern marine-based fish farm normally consists of a feeding barge, several fish cages, and feeding tubes. Although many studies, both experimental and numerical, are available in the literature to investigate the global responses of the fish cages under wave and current conditions, research on the coupled system including both the fish cage and the feeding system is very limited. This paper presents a numerical study on the coupled system with a floating fish cage and the feeding system. The purpose is to study the dynamic responses of the coupled system under different environmental conditions and configurations of the fish farm. A numerical model is firstly established in the numerical program OrcaFlex, comprising of a feeding barge, a gravity-based floating fish cage with mooring systems, and a feeding tube between the barge and the cage. Time-domain simulations of this coupled system are then performed under environmental conditions corresponding to 1-year and 50-year return periods for a reference site. The deformation of the fish cage, the tensions in the anchor lines and in the feeding tube are compared under various conditions. Sensitivity studies on the solidity ratio of the fish net as well as the lengths of the feeding tube are addressed, and their influences on the responses of the coupled system are also discussed.
Model Updating of Soil-Structure Interface of Monopiled Offshore Wind Turbines
Authors: Cong Shuai , Hu Sau-Lon James , Li Hua-Jun
Published: December 2020

As the vibration analysis of an offshore wind turbine (OWT) system should consider its soil-structure interaction, a recent article proposed a simple soil-structure interface model. It includes a horizontal spring, a rotational spring and a rotational dash-pot at the interface. Developing a finite element model updating method on correcting the soil-structure interface coefficients based on the true response measurements is highly desired. This paper develops an accurate and efficient model updating method for simultaneously updating the stiffness and damping parameters of the soil-structure interface of a monopiled offshore wind turbine, when only a few measured modal frequencies and damping ratios are available. The performance of the proposed method is numerically demonstrated through a simulated National Renewable Energy Laboratory 5-MW (NREL 5-MW) reference turbine.