bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of rain on absorption after transdermal application of flunixin in calves
Authors: Altenbrunner‐Martinek Birgit , Witek Martin , Koppatz Karl , Freissmuth Michael , Kraft Alinta , Sutter Charlene , Torres Siddartha , Gelfert Christian , Wittek Thomas
Published: December 2019

Flunixin is a nonsteroidal anti‐inflammatory drug (NSAID) that has anti‐inflammatory, anti‐pyretic, and analgesic effects. Recently, a novel transdermal formulation was developed (Finadyne® Transdermal, MSD Animal Health) and is now the first NSAID registered to be administered as a pour‐on product in cattle. According to the manufacturer's instructions, the pour‐on product should be applied only to dry skin and exposure to rain should be avoided for at least 6 hr after application. The objective of the study was to evaluate the effect of simulated exposure to light or heavy rain on flunixin absorption and bioavailability within the first 4 hr after administration. Therefore, an isocratic HPLC method was developed to quantify flunixin concentrations in bovine serum by UV detection. Light rain decreased flunixin absorption only when rain started immediately after flunixin administration, while light rain starting more than 30 min after administration of flunixin had no effect on absorption. Absorption and bioavailability of flunixin was impacted under simulated heavy rain conditions, when exposure to rain occurred within one hour after the application of the pour‐on formulation, but not later.
Maternal MUAC and fetal outcome in an Indian tertiary care hospital: A prospective observational study
Authors: Vasundhara Donugama , Hemalatha Rajkumar , Sharma Saurabh , Ramalaxmi Baru Anantha , Bhaskar Varanasi , Babu JagJeevan , Kankipati Vijaya Radha Krishna , Mamidi RajaSriswan
Published: December 2019

Studies to date demonstrated the relatedness of mid‐upper arm circumference (MUAC) measurement of pregnant women to their anthropometry/weight. Hence, the objective was to determine whether maternal MUAC at different gestational age predicted birthweight, and if so, to identify which cut‐offs provided the best prediction of low birthweight (LBW) in pregnant women cohort. A total of 928 pregnant women, free of any obstetrical and medical complications known to affect fetal growth, were followed from 20 to 24 weeks' gestation till delivery. Weight, height, and MUAC were determined for the pregnant women, and gestational age along with newborns anthropometry was collected. The mean birthweight was 2.6 ± 0.460 kg. Maternal age, height, weight, MUAC (three time points), gestational age at delivery, and post‐natal weight showed positive correlation with birthweight, crown heel length, and head circumference of the neonates. The cut‐off limit with the best sensitivity–specificity (54.0 and 59.8, respectively) for MUAC was 23 cm, whereas maternal weight of 55 kg had sensitivity and specificity of 62.5 and 59.9 for predicting LBW. Maternal weight of 55 kg and MUAC value of 23 cm had almost similar sensitivity and specificity for predicting LBW. MUAC (≤23 cm) can be considered as a potential indicator of LBW where weighing of pregnant women is not feasible or when presentation for antenatal care is late, especially where pre‐pregnancy weights are not available.
A qualitative exploration of escalation of care in the acute ward setting
Authors: Ede Jody , Jeffs Emma , Vollam Sarah , Watkinson Peter
Published: December 2019

Background

“Failure to Rescue” includes failing to prevent avoidable patient deterioration and death. Despite its use, delays in care escalation still affect patient outcomes.

Aims and Objective

The aim of this qualitative service evaluation was to map the barriers and facilitators to the escalation of care in the acute ward setting and identify those that are modifiable.

Design

A total of 55 hours of qualitative observations were completed to capture care escalation events. These were conducted at two hospital sites in one National Health Service trust.

Methods

Observations were iterative, with research team meetings being used to discuss the data and future methods. Field notes were analysed thematically by two researchers, extracting data on barriers and facilitators to escalation of care.

Results

Clinical nursing staff challenged the sensitivity and specificity of Early Warning Scores, describing tool failings in certain clinical scenarios. Staff did not escalate based on the alerting Early Warning Scores alone but used other clinical factors, such as bleeding, which are not necessarily captured in the scoring systems. Staff frequently did not re‐escalate low‐level scores. Patient and non‐patient factors identified as posing barriers to escalation were complex care needs, patient outlier status, and involvement of multiple care teams. Factors negatively affecting the chain of communication during escalation were team tension, staffing levels, and inadequate handover.

Conclusion

This service evaluation identified barriers and facilitators to the escalation of care in the acute ward setting. Unlike other studies, we found that re‐escalation or tracking of deterioration was problematic. Patients identified as being at a higher risk of escalation failure included complex patients, outliers, and patients with multiple care teams.

Relevance to clinical practice

This service evaluation demonstrates continuing health care communication barriers. Patient groups (complex patients and outliers) risk process failures during escalation. This can be applied in clinical practice by staff anticipating problems in these patients, documenting clear escalation pathways.
Nasal high‐flow oxygen in pediatric anesthesia and airway management
Authors: Humphreys Susan , Schibler Andreas
Published: December 2019

Nasal High‐Flow (NHF) is weight‐dependent in children, aimed to match peak inspiratory flow and thereby deliver an accurate FiO2 with a splinting pressure of 4‐6 cm H2O. During apnea in children, NHF oxygen can double the expected time to desaturation below 90% in well children but there is no ventilatory exchange; therefore, children do not “THRIVE”. Total intravenous anesthesia competency to maintain spontaneous breathing is an important adjunct for successful NHF oxygenation technique during anesthesia. Jaw thrust to maintain a patent upper airway is paramount until surgical instrumentation occurs. There is no evidence to support safe use of NHF oxygen with LASER use due to increased risk of airway fire.
Emergency intubation of children outside of the operating room
Authors: Long Elliot , Barrett Michael J. , Peters Cheryl , Sabato Stefan , Lockie Francis
Published: December 2019

Intubation of children outside of the operating room is performed infrequently and is often associated with life‐threatening adverse events. This review aims to clarify the contributors to adverse events encountered during intubations outside of the operating room and provide preventative strategies. The primary contributors to adverse events during non‐operating room intubations are physiologically and situationally difficult airways; anatomically difficult airways are rare. Systems‐based changes, including a shared mental model, standardization in equipment and its location, checklist use, physiological resuscitation prior to resuscitation, dose titration of induction agent, multi‐disciplinary team training in the technical and nontechnical aspects of non‐operating room intubation, debrief post–real and simulated events, and regular audit of performance all reduce life‐threatening intubation‐related adverse events in children. Intubation of children outside of the operating room may be performed safely through engagement of all critical care specialties, shared learning, and focus on patient‐centered care delivery.
Young people’s trauma‐related cognitions before and after cognitive processing therapy for post‐traumatic stress disorder
Authors: König Julia , Kopp Brigitte , Ziegelmeier Angela , Rimane Eline , Steil Regina , Renneberg Babette , Rosner Rita
Published: December 2019

Objectives

Cognitive processing therapy (CPT) is a psychotherapy for post‐traumatic stress disorder (PTSD) with a broad evidence base. Change in trauma‐related cognitions is considered its primary working mechanism. When trying to integrate a traumatic event into existing cognitive schemas, the adaptive mechanism is changing the schema (accommodation). However, PTSD patients frequently either change their schemas too much (over‐accommodation), or cognitively distort the event (assimilation). We aimed to test the hypothesized connections between the three types of cognition and symptom load.

Design

This study adds to the literature using ‘impact statements’, essays on their trauma‐related thoughts written by patients at the beginning and end of CPT, to investigate cognitive change and its relationship to symptomatic outcome.

Methods

We analysed statements written by 31 adolescents and young adults who received developmentally adapted CPT (a longer treatment where CPT is the core component) in a randomized controlled trial.

Results

As expected, post‐CPT statements contained more accommodated and fewer over‐accommodated and assimilated clauses than pre‐CPT statements. Correlations between cognition frequencies and concurrent symptom load were as expected for assimilation, and, in part, over‐accommodation and accommodation. Decreased PTSD and depressive symptoms were correlated with increased accommodated thoughts. For over‐accommodation and assimilation, however, expected correlations could not be shown.

Conclusions

Our results support the notion that cognitive change is an important mechanism of change in CPT in a sample of younger, non‐English‐speaking clients.
Calling Solomon’s Bluff: Ethics, Aspect‐Perception and the Unity of the Tractatus
Authors: Campbell Michael
Published: December 2019

In this paper, I consider how we ought to read the aspect‐perception passages in the Tractatus Logico‐Philosophicus (TLP) in the light of its ethics. I engage with a recent proposal, of Genia Schönbaumsfeld's, that we should replace the TLP account of aspect‐perception with that which Wittgenstein puts forward in the Philosophical Investigations (PI). I show that, far from helping us to grasp the ethical vision contained in the TLP, this proposal obscures it. I go on to draw some conclusions from this as to how to read the TLP in its relation to Wittgenstein's other work.
Diffuse large B cell lymphoma‐derived extracellular vesicles educate macrophages to promote tumours progression by increasing PGC‐1β
Authors: Liu Wenjian , Zhu Mengyuan , Wang Hua , Wang Weida , Lu Yue
Published: December 2019

Tumour‐associated macrophages (TAMs) comprise an important part of the tumour microenvironment and play a key role in malignant tumours progression. Tumour‐derived extracellular vesicles (EVs) modulated TAMs polarization and reprogrammed TAMs to influence the progression of various tumours. Here, we hypothesized that diffuse large B cell lymphoma (DLBCL)‐derived EVs can regulate macrophages polarization and thus contribute to tumour progression. Our results demonstrated that EVs, released from DLBCL, augment the M2 polarization effects of macrophages. Moreover, conditional medium derived from macrophages by DLBCL‐derived EVs stimulation revealed the superior effects of promoting tumour proliferation, migration and invasion. Further analysis demonstrated that DLBCL‐derived EVs regulated the metabolism of macrophages by increasing the expression of PGC‐1β protein, thereby reprogramming the macrophage phenotype of promoting tumour progression. In conclusion, our findings signify that the DLBCL‐derived EVs mediated the increasing of functional PGC‐1β protein in macrophages to promote the tumour progression.
Swedish norms for the Strengths and Difficulties Questionnaire for children 3–5 years rated by parents and preschool teachers
Authors: Dahlberg Anton , Fält Elisabet , Ghaderi Ata , Sarkadi Anna , Salari Raziye
Published: December 2019

The Strengths and Difficulties Questionnaire (SDQ) is a widespread tool for assessing behavior problems in children and adolescents. Despite being investigated thoroughly concerning both validity and reliability, peer reviewed studies that provide norms, especially for preschool children, are lacking. This paper provides Swedish norms using data from a large community sample of children aged 3–5, based on mothers’, fathers’, and preschool teacher’s ratings. Preschool teachers’ ratings were generally lower than parents’ ratings, which contradicts some previous studies. Differences between girls and boys were found, suggesting that boys display higher levels of behavior problems. Lower parental education and country of origin outside of Sweden were also associated with more difficulties. Cut‐offs are presented for each age group, gender and rater category. Population‐specific norms and percentile cut‐offs provided in this study facilitate identifying children in need of interventions in paediatric care and enable cross‐country comparisons of children’s mental health problems.
The impact of product subsidies on plant‐level total factor productivity in Britain, 1997–2014
Authors: Harris Richard , Moffat John
Published: December 2019

The United Kingdom’s imminent departure from the European Union provides the opportunity for a more selective industrial strategy. This paper therefore analyses the effect of product subsidies on productivity in British manufacturing plants between 1997 and 2014 in order to provide evidence on the desirability of extending their use. The results suggest that low rates of subsidization had either a positive or no effect but higher rates had a negative effect on total factor productivity in some sectors. This implies that increasing the generosity of subsidies does not offer a means of improving the UK’s productivity performance.
The Normative Force of Logical and Probabilistic Reasoning in Improving Beliefs
Authors: Strössner Corina
Published: December 2019

There is a deep tension between logical and probabilistic norms of belief. This article illustrates the normative force that is associated with these frameworks by showing how rather unrestricted belief bases can be improved by undergoing logical and probabilistic reflection. It is argued that probabilistic reasoning accounts for the reliability of the conclusions one can draw from the beliefs. Most importantly, reliability commands us to care for the increasing uncertainty of conjunctions of beliefs. Deductive logic captures the agent's commitment towards all conclusions of her beliefs. In other words, it seems that commitment forces the agent to believe conclusions, which reliability tells her to view with scepticism. This conflict is resolved by arguing that commitment merely forces the agent to find the logical conclusions of her beliefs acceptable, not necessarily to believe them. This demands consistency but no deductive closure. Furthermore, it is shown that by restoring consistency, a straightforward connection between high subjective probability and full belief is undermined. Finally, the article delineates how this approach deals with the lottery paradox and the preface paradox.
Reassessing the foreign ownership wage premium in Germany
Authors: Egger Hartmut , Jahn Elke , Kornitzky Stefan
Published: December 2019

This paper evaluates the effect of foreign takeover on wages of workers in German establishments, using rich linked employer–employee data from 2003 to 2014. To identify a causal effect of foreign takeover, we combine propensity‐score matching with a difference‐in‐difference estimator. We find that a takeover by a foreign investor leads to a wage premium of 4.0 log points in the year after ownership change, which further increases to 6.3 log points 3 years after acquisition. The wage premium is largest for high‐skilled workers, which is consistent with three theoretical arguments, namely rent appropriation by managers, technology protection and training on new technology. We also show that the wage premium does not pick up an exporter effect due to a platform investment of the foreign owner, that it takes about 4 years before it fully develops, that it does not vanish after foreign divestment and that the wage increase is specific to foreign acquisition instead of ownership change per se.
Jehovah's Witnesses and transfusion: where do we stand in Europe?
Authors: Loix Sébastien , Henin Pierre , Descamps Olivier , Reusens Isabelle
Published: December 2019

Transfusion refusal expressed by Jehovah's Witnesses has always been questioning for medical community. However, abundant literature exists treating about how to manage difficult medical bleeding situations in Jehovah's witnesses, there is a few information available on the legal and ethical aspects of transfusion refusal. Since 1994, Europe has putted a spotlight on patient's right. The question of patient's autonomy and consent have taken a predominant place in care. In order to summarize the actual situation in Europe, this work intends to draw a global view on legal, ethical and medical aspects of transfusion refusal expressed by Jehovah witnesses.
Observer-Based Nonlinear Decoupling Control for Two-Joint Manipulator Systems Driven by Pneumatic Artificial Muscles
Authors: Zhao Ling , Liu Xin , Wang Tao
Published: December 2019

Pneumatic artificial muscles (PAMs) are an important type of bionic actuators for high power-to-weight ratio and good flexibility. However, nonlinearities always exist in systems driven by PAMs, which should be dealt with to obtain good performances during position control. In this paper, a nonlinear state error feedback controller (NSEFC) is presented to obtain good position accuracy for a two-joint manipulator system driven by PAMs. The two-joint manipulator system has nonlinearities, which come from friction, hysteresis, uncertainties of model, loss of piping pressure, coupling between two joints, and so on. A nonlinear extended state observer (ESO) is designed to estimate the nonlinearities in the two-joint manipulator system. Both the effectiveness of the nonlinear ESO and stability of the two-joint manipulator system are given by Lyapunov approaches. Experimental results are obtained to show that the position accuracy of the two-joint manipulator system is improved based on the proposed method in this paper.
Using Cluster Analysis and Dynamic Programming for Demand Response Applied to Electricity Load in Residential Homes
Authors: Chanpiwat Pattanun , Gabriel Steven A. , Moglen Rachel L. , Siemann Michael J.
Published: December 2019

This paper develops means to analyze and cluster residential households into homogeneous groups based on the electricity load. Classifying customers by electricity load profiles is a top priority for retail electric providers (REPs), so they can plan and conduct demand response (DR) effectively. We present a practical method to identify the most DR-profitable customer groups as opposed to tailoring DR programs for each separate household, which may be computationally prohibitive. Electricity load data of 10,000 residential households from 2017 located in Texas was used. The study proposed the clustered load-profile method (CLPM) to classify residential customers based on their electricity load profiles in combination with a dynamic program for DR scheduling to optimize DR profits. The main conclusions are that the proposed approach has an average 2.3% profitability improvement over a business-as-usual heuristic. In addition, the proposed method on average is approximately 70 times faster than running the DR dynamic programming separately for each household. Thus, our method not only is an important application to provide computational business insights for REPs and other power market participants but also enhances resilience for power grid with an advanced DR scheduling tool.
Representative Volume Element for Mechanical Properties of Carbon Nanotube Nanocomposites Using Stochastic Finite Element Analysis
Authors: Sanei Seyed Hamid Reza , Doles Randall
Published: December 2019

The aim of this study is to present a representative volume element (RVE) for nanocomposites with different microstructural features using a stochastic finite element approach. To that end, computer-simulated microstructures of nanocomposites were generated to include a variety of uncertainty present in geometry, orientation, and distribution of carbon nanotubes. Microstructures were converted into finite element models based on an image-based approach for the determination of elastic properties. For each microstructure type, 50 realizations of synthetic microstructures were generated to capture the variability as well as the average values. Computer-simulated microstructures were generated at different length scales to determine the change in mechanical properties as a function of length scale. A representative volume element is defined at a length scale beyond which no change in variability is observed. The results show that there is no universal RVE applicable to all properties and microstructures; however, the RVE size is highly dependent on microstructural features. Microstructures with agglomeration tend to require larger RVE. Similarly, random microstructures require larger RVE when compared with aligned microstructures.
Density Variation in the Expanded Polystyrene Foam of Bicycle Helmets and Its Influence on Impact Performance
Authors: Kroeker Shannon G. , Özkul Muammer Ç. , DeMarco Alyssa L. , Bonin Stephanie J. , Siegmund Gunter P.
Published: December 2019

Bicycle helmets attenuate head impacts using expanded polystyrene (EPS) foam liners. The EPS density plays a key role in determining the helmet and head response during an impact. Prior pilot work in our lab showed that EPS density varied by up to 18 kg/m3 within a single helmet, and thus the purpose of this study was to quantify the regional density variations within and between helmets and to establish how these variations influence helmet impact performance. We evaluated 10–12 samples of two traditional and two bicycle motocross (BMX) bicycle helmets with EPS liners. The bulk liner density and density of 16–19 cores extracted from specific locations on each sample were measured. Additional samples of two of these helmet models were then impacted at 3.0, 6.3, and 7.8 m/s to determine the relationship between local EPS density and helmet impact performance. We found that density varied significantly within each sample in all helmet models and also varied significantly between samples in three helmet models. The density variations were not symmetric across the midline in two of the four helmet models. The observed density variations influenced the helmets' impact performance. Our data suggest that variations in peak headform acceleration during impacts to the same location on different samples of the same helmet model can be partially explained by density differences between helmet samples. These density variations and resulting impact performance differences may play a role in a helmet's ability to mitigate head injury.
Validation of Hot Corrosion and Fatigue Models in HOTPITS
Authors: Chan K. S. , Burns J. T. , Enright M. P. , Moody J. , Goodrum W.
Published: December 2019

HOTPITS is a set of physics-based modeling tools for treating Type II hot corrosion in Ni-based superalloys. The methodology includes modeling the nucleation, growth, and coalescence of pits and microcracks as a random process, as well as the transition of pits to micrcracks and the propagation of the resulting large crack to failure. In this investigation, critical experiments were performed on coupon and low-cycle fatigue (LCF) specimens in order to validate the hot corrosion and the fatigue models in HOTPITS. The pit nucleation, growth, and coalescence models in HOTPITS including the assumption of a random process are validated by the hot corrosion critical experiments performed at two salt contents. The LCF critical experiments, performed using a marker band protocol, validated the stress concentration factor-based models used to predict the pit-to-crack transition in the HOTPITS tool.
Development and Validation of a General and Robust Methodology for the Detection and Classification of Gas Turbine Sensor Faults
Authors: Manservigi Lucrezia , Venturini Mauro , Ceschini Giuseppe Fabio , Bechini Giovanni , Losi Enzo
Published: December 2019

Sensor fault detection and classification is a key challenge for machine monitoring and diagnostics, since raw data cleaning represents a key process in the gas turbine industry. To this end, this paper presents a comprehensive approach for detection, classification, and integrated diagnostics of gas turbine sensors (named DCIDS), which was previously developed by the authors and has been substantially improved and validated by means of field data. For a single sensor or redundant/correlated sensors, the improved diagnostic tool, called improved-DCIDS (I-DCIDS), can identify seven classes of faults, i.e., out of range, stuck signal, dithering, standard deviation, trend coherence, spike, and bias. First, this paper details the I-DCIDS methodology for sensor fault detection and classification. The methodology uses basic mathematical laws that require some user-defined configuration parameters, i.e., acceptability thresholds and windows of observation. Second, a sensitivity analysis is carried out on I-DCIDS parameters to derive some rules of thumb about their optimal setting. The sensitivity analysis is performed on four heterogeneous and challenging datasets with redundant sensors acquired from Siemens gas turbines (GTs). The results demonstrate the diagnostic capability of the I-DCIDS approach in a real-world scenario. Moreover, the methodology proves to be suitable for all types of datasets and physical quantities and, thanks to its optimal tuning, can also identify the exact time point of fault onset.
Investigation of Wind Flow Conditions on the Flight Endurance of UAVs in Hovering Flight: A Preliminary Study
Authors: Scicluna Leo , Sant Tonio , Farrugia Robert N.
Published: December 2019

Over the past decade the use of Unmanned Aerial Vehicles (UAVs) for the inspection of turbine blades has been registering steady progress and is fast becoming a well-established inspection methodology especially at offshore wind farms. A UAV operating in the open field is subject to varying ambient conditions which have an effect on the power required to maintain stable flight. This may have an impact on the flight endurance of the UAV, especially when operating in windy conditions. Simulations are a very useful tool for estimating the impact of such ambient conditions on the performance and flight endurance of a UAV. However, it is extremely difficult to accurately model all the dynamics at play in the open field where flow conditions are highly stochastic. Few open field studies necessary to validate such simulation models have been carried out to date in this regard. In this study, the impact of open field wind conditions on the flight endurance of a hovering UAV is investigated. The test vehicle used in this study is a quadrotor UAV, which was fitted with an array of sensors to monitor power consumption parameters of the propulsion motors whilst the vehicle is hovering at a fixed altitude above the ground. The quadrotor was also fitted with an ultrasonic wind sensor in order to measure the relevant wind parameters that the quadrotor was being subjected to during the hovering study. The test UAV was flown in different ambient conditions to establish the impact on the UAV flight endurance when subjected to different wind speeds. Results from a series of UAV test flights in the open field indicated that the power required by the UAV to maintain hovering flight decreases as the wind speed increases.
Modelling the Aerodynamics of a Floating Wind Turbine Model Using a CFD-Based Actuator Disc Method
Authors: Bezzina Ryan , Sant Tonio , Micallef Daniel
Published: December 2019

Significant research in the field of Floating Offshore Wind Turbine (FOWT) rotor aerodynamics has been documented in literature, including validated aerodynamic models based on Blade Element Momentum (BEM) and vortex methods, amongst others. However, the effects of platform induced motions on the turbine wake development downstream of the rotor plane or any research related to such areas is rather limited. The aims of this paper are two-fold. Initially, results from a CFD-based Actuator Disc (AD) code for a fixed (non-surging) rotor are compared with those obtained from a Blade Element Momentum (BEM) theory, as well as previously conducted experimental work. Furthermore, the paper also emphasises the effect of tip speed ratio (TSR) on the rotor efficiency. This is followed by the analysis of floating wind turbines specifically in relation to surge displacement, through an AD technique implemented in CFD software, ANSYS Fluent®. The approach couples the Blade Element Theory (BET) for estimating rotating blade loads with a Navier Stokes solver to simulate the turbine wake.

With regards to the floating wind turbine cases, the code was slightly altered such that BET was done in a transient manner i.e. following sinusoidal behaviour of waves. The AD simulations were performed for several conditions of TSRs and surge frequencies, at a constant amplitude. Similar to the fixed rotor analysis, significant parameters including thrust and power coefficients, amongst others, were studied against time and surge position. The floating platform data extracted from the AD approach was compared to the non-surging turbine data obtained, to display platform motion effects clearly. Data from hot wire near wake measurements and other simulation methods were also consulted.
Integrating Compressed Air Energy Storage (CAES) in Floating Offshore Wind Turbines
Authors: Vella Peter P. , Sant Tonio , Farrugia Robert N.
Published: December 2019

The design of an offshore energy storage system carries unknowns which need to be studied at an early stage of the project to avoid unnecessary costs of failures. These risks have led to an increasing dependence on more sophisticated mathematical models.

This paper refers specifically to energy storage in the offshore wind farming industry and has the objective of proposing an adiabatic compressed air energy (A-CAES) system which would be integrated on a semi-submersible offshore wind turbine (OWT) platform. Calculations in respect to the sizing of the main sub-components of the system are included and estimates for the overall round trip efficiency are presented.

Preliminary calculations to size the various parts of the energy storage system (ESS) have been carried out based on the energy availability of an offshore 8 MW wind turbine with real wind data from the North Sea. The load data to determine the lowest 12-hour demand period was taken from the Nordpool database. The calculations of the proposed conceptual design are based on an operational scenario in which the 24-hour period of a particular day is split in a 12-hour charging and 12-hour discharging cycle. For charging, a 5-bank, 2-stage compressor train is used to pressurize a number of steel cylindrical vessels with compressed air. This is followed by a process in which the compressed air is discharged across 12 hours using a 2-bank, 2-stage expander turbine. The multiple compression banks enable a modular power delivery to the air storage vessels, with the number of compressors utilized varying subject to wind availability. The two stages allowed for the air to be cooled in between the stages using heat exchangers, transferring the heat of compression to a pressurized sea water circuit. The hot water would be stored in thermally insulated vessels at 350°C to heat the inlet expanding air in the discharge period. A 70 and 100 Bar charging scenarios, both with a cushion pressure (CP) in the air storage vessel (ASV) of 10 Bar at the end of the discharge cycle have been considered.

Standard performance criteria are calculated such as compression and expansion ratios, inlet and outlet temperatures for the respective expansion and compression air streams and flow rates within the heat exchangers to come up with an indicative sizing proposal for the respective turbo machinery and storage vessels making up the system. Round trip efficiencies are also calculated.

The study determined that a CAES system consisting of 9 compressed air storage vessels operating with a peak pressure of 100 Bar should meet the storage requirements. It is also estimated that the entire CAES system would require around 1082 m2 of deck area on the platform to accommodate the pressure vessels, the compressor and expander trains, the heat exchanger and the hot water storage vessel.
Numerical Analysis of VIV on Drillstring During CPT in Shallow High-Current Sea
Authors: Yamamoto Marcio , Masanobu Sotaro , Yamamoto Joji , Ban Katsuo , Ikenobu Masayuki , Izumida Tamotsu , Sakamoto Takashi
Published: December 2019

To design the foundation of a fixed-type wind turbine, the geotechnical data of the region in different depths below the seafloor must be surveyed using a cone penetration test (CPT). A common methodology to carry out the CPT in shallow water is to use a drillstring to drill a well. Then the drillstring must be anchored and a cone probe is conveyed within the drillstring to survey the undisturbed soil a few meters below the bit. However, during the period the drillstring is anchored in a relative high-current environment, it will be exposed to the vortex-induced vibration (VIV). In this article, we will present the VIV numerical analysis to assess the stress and accumulate fatigue on the drillstring. The simulation was calculated in the frequency domain using commercial software for marine riser analysis used by the Petroleum Industry. We compared two different drillstrings, one composed by Bottom Hole Assembly (BHA) and drill pipe and the other using BHA and heavyweight drill pipe. The VIV results show slightly better performance of the string composed by heavy weight drill pipes.
Performance Evaluation of Dynamic HV Cables With Al Conductors for Floating Offshore Wind Turbines
Authors: Thies Philipp R. , Harrold Magnus , Johanning Lars , Grivas Konstantinos , Georgallis Georgios
Published: December 2019

Floating Offshore Wind turbine installations will require HV dynamic power cables to be connected to the of longer length static export power cables. Experience from offshore wind installations has highlighted the criticality of power cables, underlining the need for high integrity, yet cost effective cable solutions. This paper will assess the mechanical performance and load parameters for an Aluminum power conductor cable. Whilst copper is the conventional choice due to its lower resistive losses, Aluminum cores are increasingly used for static power cables, due to their benefits regarding overall cable weight and material cost. The work presented adopts a coupled aero-elastic and hydrodynamic modelling approach to simulate the behavior of the well-documented OC4 semi-sub platform, together with the 5MW NREL wind turbine. The model allows a direct comparison between the two cable types, maintaining the overall system and environmental conditions.

The results inform the design envelope regarding the ultimate load conditions a for the two principle cable designs, providing global load estimates, such as effective tension and bending stresses, to inform the local stress analysis. Furthermore, the results will form the basis for future physical demonstration and validation tests.

This paper will be of interest to technology developers and practitioners concerned with submarine dynamic power cables, offer a methodology to directly compare and evaluate different cable design options, and providing some design guidance for and aluminum conductor cables.
Demonstration of the Intelligent Mooring System for Floating Offshore Wind Turbines
Authors: Harrold Magnus J. , Thies Philipp R. , Halswell Peter , Johanning Lars , Newsam David , Bittencourt Ferreira Claudio
Published: December 2019

Existing mooring systems for floating offshore wind turbines are largely based on designs from the oil and gas industry. Even though these can ensure the safe station keeping of the floating wind platform, the design of the mooring system is currently largely conservative, leading to additional expense in an industry striving to achieve cost reduction. Recent interest in the usage of mooring materials with non-linear stiffness has shown that they have the potential to reduce peak line loads, ultimately reducing cost. This paper reports on the combined physical testing and numerical modeling of a hydraulic-based mooring component with these characteristics. The results suggest that the inclusion of the component as part of the OC4 semi-submersible platform can reduce the peak line loads by 10%. The paper also discusses a number of challenges associated with modeling and testing dynamic mooring materials.
Loading and Structural Analysis of the Self-Aligning HyStOH Floating Wind Turbine Concept
Authors: Manjock Andreas , Starr Markus S.
Published: December 2019

This paper summarizes the results of the implementation and verification of a hydro-aero-servo-elastic load simulation model for a self-aligning floating offshore wind turbine (FOWT) combined with a structural analysis methodology of this FOWT structure. The main focus is a comparison of a rigid and a flexible support structure representation in the load simulation. This investigation is part of the multiparty project for the ‘Hydrodynamic and Structural Optimization of a Semi-submersible Offshore Wind Turbine’ (HyStOH), joining partners from science and industry and financially supported by the German Ministry of Economics Affairs and Energy, BMWi (Bundesministerium für Wirtschaft und Energie).
WindCrete Fatigue Verification
Authors: Trubat Pau , Bairan Jesús , Yagüe Adrián , Molins Climent
Published: December 2019

WindCrete is an offshore concrete spar type platform for Wind Turbines developed at Universitat Politècnica de Catalunya – BarcelonaTech. The main characteristics of the platform are its monolithic configuration and the use of concrete as main material. The monolithic nature allows avoiding joints between the substructure and the tower increasing the service life of the structure. The use of concrete increases the resistance when exposed to an offshore environment but requires ensuring a full compression state along the structure to avoid cracking. Thus, the platform is post-tensioned by longitudinal tendons along its length.

Adequate fatigue design is a key factor to ensure the reliability of offshore structures. Floating Offshore Wind Turbines are subjected to cyclic phenomena coming from waves, wind, rotor-induced vibrations and structural vibrations. These loads have to be considered in order to assess the fatigue life of offshore structures. Furthermore, pre-stressed concrete adds an internal load such that it avoids the presence of tension stresses at any given section, which has a positive influence on the fatigue response of the structure by increasing its fatigue resistance. An excess of compression can, however, also induce an adverse effect on the fatigue resistance of the concrete.

In order to study the fatigue behaviour of WindCrete when fitted with a 5MW Wind Turbine, a Fatigue Limit State verification is performed according to the DNVGL-ST-0437 for load cases definition and FIB Model Code (2010) for fatigue structural verification. The location chosen to install WindCrete is the Gulf de Lion, at the west of the Mediteranian Sea off the coast of Catalunya with a mean wind speed above 9 m/s. The metocean conditions for design purpose are presented, which are obtained from available environmental data.

A total of 458 simulation cases are performed using the NREL FAST software assuming wind and wave co-directionally, and quasi-static mooring response for Parked and Power-Production operational modes. Assuming an elastic response of the tower, the internal stresses at the tower base are obtained for all the simulations. Then, a fatigue analysis is performed at the tower base through a cumulative damage approach based on the Palmgren-Miner rule. The analysis accounted for the multiaxial stresses produced by the combination of axial, bending and tangential forces. The S-N material curves were defined according to the Model Code 2010 method, which accounts for the effect of the stress range as well as the average stress.
Bichromatic Wave Selection for Validation of the Difference-Frequency Transfer Function for the OC6 Validation Campaign
Authors: Tom Nathan , Robertson Amy , Jonkman Jason , Wendt Fabian , Böhm Manuela
Published: December 2019

The focus of the Offshore Code Comparison Collaboration, Continuation, with Correlation and unCertainity (OC6) project, which operates under the International Energy Agency Wind Task 30, is to refine the accuracy of engineering tools used to design offshore wind turbines. In support of this work, a new validation campaign is being developed that seeks to better understand the nonlinear wave loading that excites floating wind systems at their low-frequency, rigid-body modes in surge and pitch. The validation data will be employed in a three-way validation between simplified engineering tools and higher-fidelity tools, such as computational fluid dynamics (CFD). Irregular wave spectrums, which are traditionally used to examine the nonlinear wave interaction with offshore structures, are too computationally expensive to be simulated in CFD tools, and so we will employ bichromatic wave cases instead. This paper reviews the process used to choose the bichromatic wave pairs to be applied in the campaign to validate the second-order difference-frequency quadratic and potential loads at the surge and pitch natural frequencies of a floating semisubmersible.
Hybrid Model Tests for Floating Offshore Wind Turbines
Authors: Thys Maxime , Fontanella Alessandro , Taruffi Federico , Belloli Marco , Berthelsen Petter Andreas
Published: December 2019

Model testing of offshore structures has been standard practice over the years and is often recommended in guidelines and required in certification rules. The standard objectives for model testing are final concept verification, where it is recommended to model the system as closely as possible, and numerical code calibration.

Model testing of floating offshore wind turbines is complex due to the response depending on the aero-hydro-servo-elastic system, but also due to difficulties to perform model tests in a hydrodynamic facility with correctly scaled hydrodynamic, aerodynamic and inertial loads. The main limitations are due to the Froude-Reynolds scaling incompatibility, and the wind generation. An approach to solve these issues is by use of hybrid testing where the system is divided in a numerical and a physical substructure, interacting in real-time with each other. Depending on the objectives of the model tests, parts of a physical model of a FOWT can then be placed in a wind tunnel or an ocean basin, where the rest of the system is simulated.

In the EU H2020 LIFES50+ project, hybrid model tests were performed in the wind tunnel at Politecnico di Milano, as well as in the ocean basin at SINTEF Ocean. The model tests in the wind tunnel were performed with a physical wind turbine positioned on top of a 6DOF position-controlled actuator, while the hydrodynamic loads and the motions of the support structure were simulated in real-time. For the tests in the ocean basin, a physical floater with tower subject to waves and current was used, while the simulated rotor loads were applied on the model by use of a force actuation system. The tests in both facilities are compared and recommendations on how to combine testing methodologies in an optimal way are discussed.
Assessing the Impact of Integrating Energy Storage on the Dynamic Response of a Spar-Type Floating Wind Turbine
Authors: Cutajar Charise , Sant Tonio , Farrugia Robert N. , Buhagiar Daniel
Published: December 2019

Offshore wind technology is at the forefront of exploiting renewable energy at sea. The latest innovations in the field comprise floating wind turbines deployed in deep waters that are capable of intercepting the stronger, less turbulent winds farther away from the landmass. Despite being able to augment the power harnessed, wind resources remain intermittent in nature, and so unable to satisfy the energy demand at all times. Energy storage systems (ESS) are therefore being considered a key component to smoothen out the supply-demand mismatch when wind penetration into electricity grids increases. Yet, multiple issues pertaining to the integration of ESSs on large-scale projects arise, including economic, environmental and safety considerations.

This paper presents a novel concept for integrating a hydro-pneumatic energy storage (HPES) system within a spar-type floating offshore wind turbine (FOWT) platform. It aims to assess the technical feasibility of integrating the storage unit within the floater. A preliminary investigation on the influence of integrated storage on the static stability and hydrostatic response of a conventional ballast-stabilised FOWT is conducted, followed by numerical simulations for the dynamic response using ANSYS® AQWA™. Based on the results presented, several conclusions are drawn on the implications of integrating energy storage with floating wind turbine structures. Finally, a preliminary assessment of the thermal efficiency of the storage system based on this specific embodiment is also presented and discussed.
A Systematic Study on Fatigue Loads of Offshore Wind Turbines on Monopiles Foundation
Authors: Peng Lihua , Wang Chao , Niu Shengkai
Published: December 2019

Fatigue failure is one of the most common damage types of monopiles, which are widely used in offshore wind turbines (OWT). In this paper, a systematic study is performed to investigate the influence of stiffness matrix, sea states and wave directions on fatigue loads of monopiles. The stiffness matrix of the monopile determines natural frequency of the whole system and has great effect on fatigue loads. The influence of the pile diameter and length on the stiffness matrix are analyzed, which are calculated based on p-y curve of foundation. Then, three methods for selected sea states are compared. The dynamic response of the monopile using the different selection method under same wind condition are calculated and their contribution to the fatigue load is discussed. Finally, bending moment on the top of monopiles in vary wave direction are analyzed which shows significant on the fatigue. Several suggestions for design of monopile are given to avoid fatigue failure based on this study.
Dynamic Load Response Analysis on Yaw Bearing of Wind Turbine to Turbulent Wind
Authors: Xu Jianwen
Published: December 2019

Wind turbines are subjected to dynamic loads during their service life. The yaw bearing is an important part which also bears these loads. In this study, a series of 5-megawatt (MW) wind turbines are analyzed for their dynamic response under normal operating conditions while exposed to turbulent wind. These models are Onshore, Monopile, ITI Barge, Spar, Tension-Leg Platform (TLP), Semi-Submerisible. TurbSim is used to prescribe turbulent-wind inflow and a time domain FAST code is applied in order to conduct the Aero-Hydro-Servo-Elastic coupled analysis on the yaw loads of the wind turbines. Three different average wind velocities are examined to compare the load response of the wind turbine to turbulent wind on the yaw bearing. A Gumbel distribution coupled maximum likelihood method is used to predict ultimate loads. And the rain flow counting algorithm, the linear cumulative damage law and S-N curve theory are used to predict the damage equivalent load. The results should aid the fatigue design of yaw bearing and the yaw control system according to different wind turbine design.