bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative proteomics of Helicobacter pylori strains reveals geographical features rather than genomic variations
Authors: Sugiyama Naoyuki , Miyake Satomi , Lin Miao‐Hsia , Wakabayashi Masaki , Marusawa Hiroyuki , Nishiumi Shin , Yoshida Masaru , Ishihama Yasushi
Published: December 2018

Helicobacter pylori, a pathogen of various gastric diseases, has many genome sequence variants. Thus, the pathogenesis and infection mechanisms of the H. pylori‐driven gastric diseases have not been elucidated. Here, we carried out a large‐scale proteome analysis to profile the heterogeneity of the proteome expression of 7 H. pylori strains by using an LC/MS/MS‐based proteomics approach combined with a customized database consisting of nonredundant tryptic peptide sequences derived from full genome sequences of 52 H. pylori strains. The nonredundant peptide database enabled us to identify more peptides in the database search of MS/MS data compared with a simply merged protein database. Using this approach, we carried out proteome analysis of genome‐unknown strains of H. pylori at as large a scale as genome‐known ones. Clustering of the H. pylori strains using proteome profiling slightly differed from the genome profiling and more clearly divided the strains into two groups based on the isolated area. Furthermore, we identified phosphorylated proteins and sites of the H. pylori strains and obtained the phosphorylation motifs located in the N‐terminus that are commonly observed in bacteria.
Kidney embolization induces prompt organ response in a 86‐year‐old patient with MGRS‐related AL‐amyloidosis
Authors: Küchlin Sebastian , Duffner Johannes , Scheubeck Sophia , Schoeller Katja , Maruschke Lars , Seidl Maximilian , Engelhardt Monika , Walz Gerd , Prager Eric Peter , Waldschmidt Johannes Moritz
Published: December 2018

Despite substantial improvements following the introduction of novel agents and antibodies, amyloid light‐chain (AL)‐amyloidosis still carries a grim prognosis. Here, we report on the case of a severely frail 86‐year‐old patient suffering from monoclonal gammopathy of renal significance (MGRS)‐associated AL‐amyloidosis with a diuretic‐refractory nephrotic syndrome. In this patient, treatment with bortezomib–dexamethasone effectively induced a serological response, but was unfortunately poorly tolerated and failed to promote renal recovery fast enough to prevent secondary complications. Facing ongoing nephrotic syndrome, we performed unilateral kidney embolization and observed a substantial improvement of hypoalbuminemia accompanied by a significant gain in overall quality of life despite the necessity for thrice weekly dialysis. It can be concluded that systemic drugs in MGRS typically do not lead to instantaneous organ recovery but may initially rather be associated with substantial treatment‐related morbidity. In this setting, unilateral renal artery embolization is effective to treat nephrotic syndrome and its secondary complications. The risk of potentially adverse effects, including post‐embolization syndrome, can be minimized by unilateral embolization, still noting that also one‐sided renal ablation has to be balanced against the requirement for life‐long renal replacement therapy. Prospective controlled trials in a more comprehensive cohort will be needed to estimate the overall benefit of kidney embolization relative to novel agent therapies in frail patients with MGRS‐related AL‐amyloidosis.
Sectoral composition of government spending, distortionary income taxation, and macroeconomic (in)stability
Authors: Chang Juin‐Jen , Guo Jang‐Ting , Shieh Jhy‐Yuan , Wang Wei‐Neng
Published: December 2018

This paper examines the interrelations between the sectoral composition of government spending and macroeconomic (in)stability in a two‐sector real business cycle model with positive productive externalities in investment and a balanced‐budget fiscal policy rule, whereby endogenous public expenditures are financed by the distortionary constant tax rate. Under the benchmark parameterization, our model always exhibits indeterminacy and sunspots provided the tax rate does not exceed a critical value. When the tax rate is raised to a higher level, a sufficiently high public‐consumption share can destabilize the macroeconomy by generating belief‐driven cyclical fluctuations. We also find that saddle‐path stability and equilibrium uniqueness will prevail when the household's labor supply elasticity is not higher than a threshold level. In addition, analytical proofs for each of the aforementioned quantitative results are provided.
Cox Point Processes: Why One Realisation Is Not Enough
Authors: Micheas Athanasios C.
Published: December 2018

We review a rich class of point process models, Cox point processes, and illustrate the necessity of more than one observation (point patterns) in performing parameter estimation. Furthermore, we introduce a new Cox point process model by treating the intensity function of the underlying Poisson point process as a random mixture of normal components. The behaviour and performance of the new model are compared with those of popular Cox point process models. The new model is exemplified with an application that involves a single point pattern corresponding to earthquake events in California, USA.
A novel, effective, and feasible method for deacidifying kiwifruit wine by weakly basic ion exchange resins
Authors: Zhong Wu , Li Xinyue , Yang Hong , Li Erhu
Published: December 2018

In this study, an effective deacidification process for kiwifruit wine using ion exchange resins was investigated. Static adsorption experiments were conducted to screen an appropriate resin and optimize the volume ratio of resin to wine. Dynamic adsorption experiments were conducted to optimize the flow rate. Sensory and chemical analysis of the deacidified kiwifruit wine were also performed. The results demonstrated that 330 resin with a maximum adsorption capacity decreased total acid and citric acid to 4.32 and 1.39 g/L in kiwifruit wine. The acid adsorption process fitted Ho's sorption kinetic model well. The volume ratio of the 330 resin to wine and the feed flow rate were further optimized to be 1:30 and 4 mL/min. Kiwifruit wine with total acid and citric acid contents of 7.98 and 4.74 g/L was obtained, under optimum conditions, while preserving alcohol, vitamin C (Vc), flavonoids and phenol content, and improving the flavor.

Practical applications

The high acidity in kiwifruit wine depress the sensory quality and attraction to consumers. Resins are applied for liquid treatment because of high efficiency, insolubility and low cost. This work showed that 330 resin treatment is a promising method to deacidify kiwifruit wine and provided an economical and effective processing method for kiwifruit processing enterprises. Monitoring acidity change and kiwifruit wine quality help enterprises better control the process. Furthermore, the easy removal of resins will greatly reduce energy consumption, resulting in lower processing cost.
Storage stability of bioactive compounds of pomegranate leather (pestil) produced by refractance window drying
Authors: Tontul Ismail , Topuz Ayhan
Published: December 2018

Fruit leathers are commonly produced with several fruits for consuming out of harvesting seasons. It is rich in nutritional and bioactive compounds. However, the bioactive compounds are sensitive to processing and storage conditions. Therefore, the chemical properties of the pomegranate leather produced by refractance window drying during storage at three different storage temperatures were investigated in the present study. The bioactive compounds of pomegranate leathers gradually decreased during storage, especially in high storage temperatures. The degradation of anthocyanins fit the second‐order reaction kinetics. HMF content and volatile nonenzymatic browning reaction products were increased during storage especially at 35 °C. Moreover, storing at 35 °C for short period of time caused a volatile composition similar to the storing for a long period at 22 °C. Overall, leather must be stored at low temperatures to increase the stability of bioactive compounds.

Practical applications

Refractance window drying has gained more and more attention from the food industry due to its scalability, cost‐effectiveness, and continuous production opportunity. Many papers have shown the effectiveness of refractance window drying over different drying techniques. However, the fate of refractance window dried materials during storage is absent in the literature. Therefore, the storage stability of pomegranate leather was determined in the present study.
Willingness to Change Medications Linked to Increased Fall Risk: A Comparison between Age Groups
Authors: Haddad Yara K. , Karani Mamta V. , Bergen Gwen , Marcum Zachary A.
Published: December 2018

Objective

To describe and compare two age groups’ knowledge of medications linked to falls and willingness to change these medications to reduce their fall risk.

Method

We analyzed data from community‐dwelling adults age 55 and older (n = 1812): 855 adults aged 55 to 64 years and 957 older adults (65 and older) who participated in the 2016 summer wave of the ConsumerStyles survey, an annual Web‐based survey. The data are weighted to match the US Current Population Survey proportions on nine US Census Bureau demographic characteristics.

Measurements

Survey respondents were asked about medication use, knowledge of side effects, their willingness to change their medications to reduce fall risk, communication in the previous year about fall risk with their healthcare provider, and their comfort in discussing fall risk with their healthcare provider. All data were weighted to match the 2016 population estimates. Descriptive statistics and χ2 (p ≤ .05) were used to identify differences between the two age groups.

Results

About one‐fifth of all respondents reported using at least one class of medication that increases fall risk. Older adults were less likely to report using medications for mood or sadness, less likely to report knowing the side effects of pain medications, and more willing to change their sleep medications compared with their younger counterparts. Among all respondents using these medication classes, less than one‐third knew the potential fall‐related side effects. However, most of them expressed willingness to change their medication if advised by their healthcare provider.

Conclusion

Most older adults were unaware of potential fall risks associated with medications prescribed to address pain, difficulty sleeping, mood or sadness, and anxiety‐ or nervousness‐related health issues. However, most were willing to change their medication if recommended by a healthcare provider. J Am Geriatr Soc 67:527–533, 2019.
High‐speed railway to success? The effects of high‐speed rail connection on regional economic development in China
Authors: Yu Feng , Lin Faqin , Tang Yihong , Zhong Changbiao
Published: December 2018

We find that high‐speed railway connection in China has led to a reduction in GDP per capita for connected peripheral prefectures. We use the least‐cost path‐spanning tree network to address the nonrandom route placement issue. We find that the reduction of GDP per capita is driven by significant contractions in capital input, industrial output, and skilled labor outflow. We present evidence to support a trade‐based channel in light of falling transportation costs between peripheral and metropolitan regions. Our finding highlights the importance of the cost of human transport.
Rural business programs and business performance: The impact of the USDA's Business and Industry (B&I) Guaranteed Loan Program
Authors: Rupasingha Anil , Crown Daniel , Pender John
Published: December 2018

The USDA's Rural Development (RD) has implemented several loan and grant programs to support businesses located in rural areas and the Business and Industry (B&I) Guaranteed Loan Program is the largest among them. The focus of the present study is to estimate the impact of B&I program participation and the amount of loans received on the probability of survival and employment growth of recipient businesses over the period of 1990–2013. Using administrative data on B&I loans from RD and business‐level data from the National Establishment Time‐Series (NETS), we utilize a matched difference‐in‐difference estimation strategy to assess the impact of the B&I program on establishment‐level outcomes. We find that the receipt of a B&I loan helps recipient businesses to reduce the risk of failure and grow slightly faster, compared with a similar control group of businesses. We also test if the impacts vary with the loan size and find that while increasing the size of loans has an increasing effect to reduce the risk of failure, it shows no statistically significant effect on employment growth.
Implantable cardioverter defibrillator replacement guided by T wave safety margin in a short QT syndrome patient
Authors: Shen Yishi , Pan Weizhong , Jiang Chenyang , Fu Guosheng , Sun Yaxun , Hu Dan
Published: December 2018

We report implantable cardioverter defibrillator (ICD) generator replacement guided by T wave safety margin (TWSM) in a short QT syndrome patient with T wave oversensing (TWOS). During the procedure of generator replacement, the feature of ventricular sensing in four different ICDs was compared in the patient. The four ICDs showed different R and T wave amplitudes. Though R/T ratio is not the highest, Vitality ICD showed the highest TWSM and was implanted as replacing generator. During 20‐month follow‐up, the patient has been symptom‐free with no T‐wave oversensing episode. This case illustrates a method to evaluate the risk of TWOS before ICD implantation in patients with high risk of TWOS.
Molecular signatures associated with increased freezing tolerance due to low temperature memory in Arabidopsis
Authors: Zuther Ellen , Schaarschmidt Stephanie , Fischer Axel , Erban Alexander , Pagter Majken , Mubeen Umarah , Giavalisco Patrick , Kopka Joachim , Sprenger Heike , Hincha Dirk K.
Published: December 2018

Alternating temperatures require fast and coordinated adaptation responses of plants. Cold acclimation has been extensively investigated and results in increased freezing tolerance in Arabidopsis thaliana. Here, we show that the two Arabidopsis accessions, Col‐0 and N14, which differ in their freezing tolerance, showed memory of cold acclimation, that is, cold priming. Freezing tolerance was higher in plants exposed to cold priming at 4°C, a lag phase at 20°C, and a second triggering cold stress (4°C) than in plants that were only cold primed. To our knowledge, this is the first report on cold memory improving plant freezing tolerance. The triggering response was distinguishable from the priming response at the levels of gene expression (RNA‐Seq), lipid (ultraperformance liquid chromatography–mass spectrometry), and metabolite composition (gas chromatography–mass spectrometry). Transcriptomic responses pointed to induced lipid, secondary metabolism, and stress in Col‐0 and growth‐related functions in N14. Specific accumulation of lipids included arabidopsides with possible functions as signalling molecules or precursors of jasmonic acid. Whereas cold‐induced metabolites such as raffinose and its precursors were maintained in N14 during the lag phase, they were strongly accumulated in Col‐0 after the cold trigger. This indicates genetic differences in the transcriptomic and metabolic patterns during cold memory.
Suspicious minds: Police Attitudes to Mental Ill Health
Authors: Bell Sean , Palmer-Conn Sue
Published: December 2018

Policing and mental ill health are inextricably entwined. The police have a role to respond to distressed persons and depending on the circumstances act as mental health practitioners or law enforcement officers.  Policing can have an impact on the mental health of those delivering the service. Those working within policing will either experience, work alongside and/or manage colleagues with mental ill health. Therefore it is important that the attitudes of police officers and police staff to mental ill health are established. The research employs the Time to Change Survey to bench mark police attitudes against the general public. Results indicate that police officers/staff hold similar attitudes to the public. However police officers are less supportive of community based interventions. Police data portrays an organisation where mental health related stigma persists, where discussing or seeking help is avoided and having a mental health issue seen as career destroying.
Can Trademark Infringement Be a Victimless Crime? The Stone Creek v. Omnia Case
Authors: Bania Doug
Published: December 2018

This article examines a case in which the defendants had made unauthorized use of the plaintiff’s trademark but were nonetheless able to successfully defend themselves against the awarding of monetary damages. As it shows, to claim damages, trademark holders must demonstrate actual harm to their reputation or loss of potential profits. It describes the methods used by the author to determine the actual effect of the infringement, which included analyzing information regarding the defendants’ intentions and the parties’ industry and the findings of a consumer survey and of Internet search and social media analytic tools. The article argues for the importance of understanding the particularities of a given case and marketplace and the utility of readily available and inexpensive Internet analytic tools.
Sensory coding is impaired in rat absence epilepsy
Authors: Studer Florian , Laghouati Emel , Jarre Guillaume , David Olivier , Pouyatos Benoît , Depaulis Antoine
Published: December 2018

Key points

Absence epilepsy is characterized by the occurrence of spike‐and‐wave discharges concomitant with an alteration of consciousness and is associated with cognitive comorbidities.

In a genetic model of absence epilepsy in the rat, the genetic absence epilepsy rat from Strasbourg (GAERS), spike‐and‐wave discharges are shown to be initiated in the barrel field primary somatosensory cortex that codes whisker‐related information, therefore playing an essential role in the interactions of rodents with their environment.

Sensory‐information processing is impaired in the epileptic barrel field primary somatosensory cortex of GAERS, with a delayed sensory‐evoked potential and a duplicated neuronal response to whisker stimulation in in vivo extracellular recordings. Yet, GAERS present no defaults of performance in a texture discrimination task, suggesting the existence of a compensatory mechanism within the epileptic neuronal network.

The results of the present study indicate that physiological primary functions are processed differently in an epileptic cortical network.

Several neurodevelopmental pathologies are associated with disorganized cortical circuits that may alter primary functions such as sensory processes. In the present study, we investigated whether the function of a cortical area is altered in the seizure onset zone of absence epilepsy, a prototypical form of childhood genetic epilepsy associated with cognitive impairments. We first combined in vivo multichannel electrophysiological recordings and histology to precisely localize the seizure onset zone in the genetic absence epilepsy rat from Strasbourg (GAERS). We then investigated the functionality of this epileptic zone using extracellular silicon probe recordings of sensory‐evoked local field potentials and multi‐unit activity, as well as a behavioural test of texture discrimination. We show that seizures in this model are initiated in the barrel field part of the primary somatosensory cortex and are associated with high‐frequency oscillations. In this cortex, we found an increased density of parvalbumin‐expressing interneurons in layer 5 in GAERS compared to non‐epileptic Wistar rats. Its functional investigation revealed that sensory abilities of GAERS are not affected in a texture‐discrimination task, whereas the intracortical processing of sensory‐evoked information is delayed and duplicated. Altogether, these results suggest that absence seizures are associated with an increase of parvalbumin‐inhibitory neurons, which may promote the functional relationship between epileptic oscillations and high‐frequency activities. Our findings suggest that cortical circuits operate differently in the epileptic onset zone and may adapt to maintain their ability to process highly specialized information.
La radio comercial en Colombia. El nuevo panorama digital de la comunicación y del periodismo.
Authors: Zambrano William Ricardo
Published: December 2018

Las emisoras tradicionales hallaron en Internet un canal donde coexisten nuevos formatos, contenidos, narrativas y lenguajes para llegar a diferentes públicos, al tiempo que abren otras alternativas de procesamiento, elaboración y difusión de la información. Estos medios dominantes están en un afán por migrar sus contenidos a la red, ya sea para ofrecer un servicio complementario o para crear una simbiosis de convergencia mediática, en la cual se generen nuevos modelos de comunicación y de actuación del comunicador y del periodista. Para comprender estos nuevos paradigmas mediáticos, se analizó la transformación de la radio comercial análoga a digital a partir de las categorías: empresarial, tecnológica, informativa, diseño web, audiencias y tendencias profesionales y laborales. Para esto, se realizó una investigación teórica y aplicada de carácter documental, descriptivo y correlacional de cinco emisoras comerciales de seis cadenas radiales que existen en Colombia, con mayor audiencia y cobertura informativa a nivel nacional.
Características de los Sistemas Centrales de Conocimiento en niños de 3 a 6 años de edad
Authors: Rueda-Posada María Fernanda , Quiroz-Padilla María Fernanda , Giraldo Juan Jose
Published: December 2018

Los Sistemas Centrales de Conocimiento son la base de las habilidades cognitivas de la especie humana. Teniendo en cuenta el valor evolutivo de los mismos, se buscó reconocer las relaciones o diferencias entre estos y otras variables de crecimiento (sexo y edad) y variables ambientales (nivel socioeconómico). Para ello, se evaluó cada sistema central de conocimiento y el desarrollo sociocognitivo de 164 niños y 164 niñas, entre los 37 y 71 meses de edad (M  = 54 meses; DE = 0.55). Al aplicar una prueba Kruskal-Wallis se encontró que la edad tuvo un efecto significativo sobre el índice general de desarrollo sociocognitivo (p < 0.001) y sobre el reconocimiento funcional del objeto (χ2 = 54.221, p < 0.001), del número (χ2 = 85.735, p < 0.001) y la ubicación espacial (χ2 = 8.258, p < 0.016). En contraste, no se hallaron efectos del sexo ni del nivel socioeconómico para las diferencias en los sistemas centrales de conocimiento ni en el índice de desarrollo sociocognitivo.
Percepción de habilidad, reto y relevancia como predictores de compromiso cognitivo y afectivo en estudiantes de secundaria
Authors: Ochoa-Angrino Solanlly , Montes-González Jairo A. , Rojas-Ospina Tatiana
Published: December 2018

Este estudio evalúa la relación entre percepción de habilidad, reto, relevancia de la tarea y compromiso cognitivo y afectivo en 88 estudiantes colombianos de secundaria durante clases de Ciencias. Igualmente, indaga si las relaciones entre percepción de habilidad, reto, relevancia y compromiso están moderadas por tipo de asignatura y género, y si existe relación entre compromiso y desempeño académico. El diseño del estudio es descriptivo correlacional y predictivo. Se usó el método de muestreo de experiencias (ESM) para tomar medidas repetidas del compromiso y de las percepciones de habilidad, reto y relevancia. Dada la característica anidada de los datos, se realizaron análisis lineales jerárquicos. Las percepciones de habilidad, reto y relevancia predicen el compromiso cognitivo y afectivo. Género y tipo de curso emergen como moderadores de las relaciones entre estas percepciones y compromiso. A su vez, el compromiso cognitivo y afectivo predice el desempeño académico en Ciencias. Se discuten las implicaciones educativas del estudio.
Micro Combined Heat and Power System Transient Operation in a Residential User Microgrid
Authors: Ippolito Francesco , Venturini Mauro
Published: December 2018

This paper presents an analysis of the transient operation of a micro combined heat and power (CHP) system, equipped with both thermal and electric storage units and connected with both electric and district heating grids. Analysis is carried out by means of a simulation model developed by the authors for reproducing the transient behavior of micro-CHP systems operating within a microgrid. The prime mover considered in this paper is an internal combustion reciprocating engine. A residential user, characterized by electric and thermal energy demand during one representative summer day, is analyzed by using literature data. The transient response of each component is evaluated separately to quantify the relative deviation (RD) between the user-demand and micro-CHP system transient response. Therefore, this paper provides a measure of the RD over 1 day in terms of the energy required by the user versus the energy provided to the user itself.
A Semi-Analytical Method for Modeling Two-Phase Flow Behavior in Fractured Carbonate Oil Reservoirs
Authors: Wang Suran , Cheng Linsong , Huang Shijun , Xue Yongchao , Bai Minghong , Wu Yonghui , Jia Pin , Sun Zheng , Wang Junfeng
Published: December 2018

It is quite common for oil/gas two-phase flow in developing fractured carbonate oil reservoirs. Many analytical models proposed for black oil wells in fractured carbonate reservoirs are limited to single-phase flow cases and conventional methods have been the use of numerical simulations for this problem. In this approach, a novel semi-analytical method is proposed to integrate the complexities of phase change, pressure-dependent pressure-volume-temperature (PVT) properties, two-phase flow behavior, and stress-dependent fracture permeability characteristics. A dual-porosity, black oil model considering the phase change and two-phase flow is applied to model the fractured carbonate reservoirs. To linearize the model, only flow equations of oil phase are used to develop the mathematical model. Nonlinear parameters and producing gas–oil ratio (GOR) are updated with coupled flowing material balance equations, followed by a novel proposed procedure for history matching of field production data and making forecasts. The semi-analytical method is validated with a commercial simulator Eclipse. The results show that both of the production rate curves of oil and gas phase using the proposed model coincide with the numerical simulator. The results also show that the effects of pressure-dependent fracture permeability, fracture porosity, and exterior boundary on production rate are significant. Stress sensitivity influences production rate during the whole process, reducing the cumulative production. Fracture porosity influences production rate during the intermediate flow periods. The exterior boundary affects production rate mainly in the early and intermediate production periods. Finally, a field example from the eastern Pre-Caspian basin is used to demonstrate the practicability of the method. Acceptable history match is achieved and the interpreted parameters are all reasonable.
Performance Assessment of a Heat Recovery System for Monolithic Receiver-Reactors
Authors: Brendelberger Stefan , Holzemer-Zerhusen Philipp , von Storch Henrik , Sattler Christian
Published: December 2018

The most advanced solar thermochemical cycles in terms of demonstrated reactor efficiencies are based on temperature swing operated receiver-reactors with open porous ceria foams as a redox material. The demonstrated efficiencies are encouraging but especially for cycles based on ceria as the redox material, studies have pointed out the importance of high solid heat recovery rates to reach competitive process efficiencies. Different concepts for solid heat recovery have been proposed mainly for other types of reactors, and demonstration campaigns have shown first advances. Still, solid heat recovery remains an unsolved challenge. In this study, chances and limitations for solid heat recovery using a thermal storage unit with gas as heat transfer fluid are assessed. A numerical model for the reactor is presented and used to analyze the performance of a storage unit coupled to the reactor. The results show that such a concept could decrease the solar energy demand by up to 40% and should be further investigated.
Effects of Cooling Passages and Nanofluid Coolant on Thermal Performance of Polymer Electrolyte Membrane Fuel Cells
Authors: Kordi Mostafa , Moghadam Ali Jabari , Afshari Ebrahim
Published: December 2018

In this research, cooling of polymer membrane fuel cells by nanofluids is numerically studied. Single-phase homogeneous technique is used to evaluate thermophysical properties of the water/Al2O3 nanofluid as a function of temperature and nanoparticle concentration. Four cooling plates together with four various fluids (with different nanoparticle concentrations) are considered for cooling fuel cells. The impact of geometry, Reynolds number, and concentration is investigated on some imperative parameters such as surface temperature uniformity and pressure drop. The results reveal that, among different cooling plates, the multipass serpentine flow field has the best performance. It is also proved that the use of nanofluid, in general, enhances the cooling process and significantly improves those parameters directly affecting the fuel cell performance and efficiency. By increasing the nanoparticle concentration by 0.006, the temperature uniformity index will decrease about 13%, the minimum and maximum temperature difference at the cooling plate surface will decrease about 13%, and the pressure drop will increase about 35%. Nanofluids can improve thermal characteristics of cooling systems and consequently enhance the efficiency and durability of fuel cells.
Further Discussion on the White-Noise Approach for Predicting Slow-Drifts in FAST
Authors: do Carmo Lucas H. S. , Camargo Ewerton C. , Simos Alexandre N.
Published: December 2018

Making use of theoretical approximations for the computation of the wave-induced slow-drift forces is a common procedure in the early stages of design of a new floating unit. They can help reducing the computational burden in two different fronts: for generating the QTFs in a frequency domain analysis, and during the subsequent execution of time-domain simulations. In a previous paper, we have discussed a simple procedure for making use of the white-noise approximation in FAST, without the need for any modification of the software. The proposal only requires restricting the computation of the QTFs to pairs of frequencies that are indeed essential to the slow-drift dynamics. For this, however, an additional assumption is made, considering that each motion is decoupled from those in the other dofs. In the present paper, a more detailed analysis of the subject is made, in order to clarify the theoretical aspects of the procedure and supplement the previous analysis. Once again, the results are based on the data available for the OC4 FOWT. The accuracy obtained with the procedure is discussed not only in terms of the resulting motions, but also comparing its effects on the second-order force spectra. A more detailed evaluation of the dynamic couplings is presented, and comparisons with the results obtained with Newman’s approximation are made in simulations involving waves only.
Integrity Management Challenges for Commercial-Scale Floating Wind Farms
Authors: Carra Christopher , Kilner Andrew , Potts Andrew , Rowley David , Ryan Victoria
Published: December 2018

Large-scale deployment of multiple structures within a Floating Offshore Wind Farm (FOWF) will place many challenges on both the approach to effective integrity management and the demand to reduce through-life operating costs. Additionally, wind farm designers and operators will need to consider the issues related to design robustness in the design of their systems, whereby rational robustness criteria are applied to address possible accidental conditions that are not explicitly addressed in code-specified design basis conditions.

This paper will review the significant advances in the approach to integrity management that have been recently made in the mature offshore oil industry and relate them to the nascent offshore wind industry. In particular, the requirement for consideration across the full lifecycle of the potential for threat introduction and the application of controls to prevent or mitigate the evolution of those threats will be described. This includes threats that may be inadvertently introduced during the design, manufacturing and installation phases, in addition to the more traditional rate-based degradation mechanisms such as fatigue, corrosion and wear that occur once the facility is in operation.

The challenges that commercial-scale wind farm developments will face relate particularly to integrity issues arising in the design, manufacturing and installation phases, where the focus needs to ensure that degradation threats are not being introduced into the deployment of multiple repeat-copy units. The issues of common cause/common mode degradation threats will have much higher significance for a commercial-scale wind farm, where rectification of a common issue across a large number of floating units could have significant impacts in terms of reliability, operating costs, insurance premiums and power purchase agreements.

FOWF mooring system designs are also likely to be more optimized than that for a typical one-off offshore oil facility. This will require the wind farm designer to have a deep understanding of the fundamental dynamic behavior of the overall system and the local dynamic behaviors of the components within the mooring system in order to be able to fully identify the types of threats that may be present. This may also involve robustness considerations where there may be step changes in the dynamic behavior of the system, often termed as cliff-edge effects.

The paper will outline issues that wind farm designers will need to consider in building integrity considerations into the design and execution phases of a development, as well as the opportunities that risk-based integrity management processes offer in terms of through-life condition verification and inspection optimization.
An Analysis of Alternatives for the Development of Jones Act Compliant Windfarm Construction Vessel Fleets
Authors: Maloney Kenneth J. , Bourg David M. , Humphreys Kenneth F. , Townsend Christopher M.
Published: December 2018

The typical offshore wind turbine generator (WTG) currently being installed worldwide produces 6 to 8 megawatts of electrical power and stands more than 100 meters above the ocean surface. The next generation turbines will produce 12 megawatts or more. In the summer of 2016 five of these turbines were installed in the coastal waters of Rhode Island. They are representative of the latest in a constantly evolving series of WTGs. As manufacturers continue to develop more powerful turbines, larger and larger specialized vessels will be needed to lift the components at assembly sites offshore. The process these vessels use to build America’s offshore windfarms will need to be different from the approach normally used at sites outside the U.S. This is due in part to regulatory restrictions imposed by the Merchant Marine Act of 1920, which is more commonly known as the Jones Act. As it pertains to offshore windfarm construction, the Jones Act prohibits foreign-flagged vessels, (vessels built outside the United States) from moving cargo between two U.S. ports. Under the law, an offshore windfarm within territorial waters is considered a U.S. port. Therefore, employing a foreign built windfarm construction vessel to transport components from a nearby port to the construction site, as it typically does, violates the Jones Act. Although the Jones Act might appear to be a deterrent to the development of offshore wind in the U.S., it is not. The developers of the Rhode Island’s Block Island Wind Farm (BIWF) used a combination of U.S. and foreign-flagged vessels to construct BIWF, while remaining in compliance with the law. This paper reviews the approach used at Block Island and discusses how it can be applied to future projects. An analysis of alternatives for various vessel fleet combinations that can be used for this purpose is provided. The analysis is based on results produced by a throughput and scheduling model developed by the authors. The model leverages the experience gained during the construction of BIWF, and was validated with data collected during the project. The alternatives include scenarios utilizing existing vessels modified for windfarm construction service, foreign-flagged windfarm construction vessels, and new vessels specifically built for the U.S. market. The paper concludes with a review of the relative efficiencies of various fleet configurations while undertaking the construction of a notional windfarm located off the East Coast of the U.S.
DNV GL Standard for Floating Wind Turbines
Authors: Hopstad Anne Lene Haukanes , Argyriadis Kimon , Manjock Andreas , Goldsmith Jarett , Ronold Knut O.
Published: December 2018

The first issue of the DNV Offshore Standard, DNV-OS-J103 Design of Floating Wind Turbine Structures, was published in June 2013. The standard was based on a joint industry effort with representatives from manufacturers, developers, utility companies and certifying bodies from Europe, Asia and the US. The standard represented a condensation of all relevant requirements for floaters in existing DNV standards for the offshore oil and gas industry which were considered relevant also for offshore floating structures for support of wind turbines, supplemented by necessary adaptation to the wind turbine application. The development of the standard capitalized much on experience from development projects going on at the time, in particular the Hywind spar off the coast of western Norway, the WindFloat off the coast of Portugal and the Pelastar TLP concept. In July 2018, DNV GL published a revision of DNV-OS-J103 as a part of the harmonization of the DNV GL codes for the wind turbine industry after the merger between Det Norske Veritas (DNV) and Germanischer Lloyd (GL) in the fall of 2013. The standard was re-issued as DNVGL-ST-0119 Floating wind turbine structures. This new revision reflects the experience gained after the first issue in 2013 as well as the current trends within the industry. Since 2013, numerous guidelines addressing the design of floating structures for offshore wind turbines have been published by various certifying bodies, and an IEC technical specification on the subject is under way. In addition, several prototypes have been installed and the first small array of floating wind turbines, Hywind Scotland pilot park, are currently in operation. The most important updates in the revision of the standard include formulation of floater-specific load cases, requirements to be fulfilled to support the exemption for design of unmanned floaters with damage stability, and replacement of current consequence-class based requirements for design fatigue factors with low-consequence based factors dependent on the accessibility for inspection and repair, the aim being a safety level against fatigue similar to that which is currently targeted for bottom-fixed structures. Other topics which have been considered in the revision are the floater motion control system and its possible integration with the control and protection system for the wind turbine, the issue of how to deal with slack in tendons in the station keeping system, corrosion, anchor design and power cable design.

In parallel to the revision of the standard, a new service specification for certification of floating wind turbines has been developed by DNV GL, identified as DNVGL-SE-0422 Certification of floating wind turbines. For technical requirements, the service specification refers to the revised standard, DNVGL-ST-0119.

The technical paper summarizes the updates and changes in the revised standard, in addition to the content of the new service specification.
A New Assessment of Offshore Wind Profile Relationships
Authors: Jeans Gus , Quantrell Dave , Watson Andrew , Grignon Laure , Lizcano Gil
Published: December 2018

Engineering design codes specify a variety of different relationships to quantify vertical variations in wind speed, gust factor and turbulence intensity. These are required to support applications including assessment of wind resource, operability and engineering design. Differences between the available relationships lead to undesirable uncertainty in all stages of an offshore wind project.

Reducing these uncertainties will become increasingly important as wind energy is harnessed in deeper waters and at lower costs. Installation of a traditional met mast is not an option in deep water. Reliable measurement of the local wind, gust and turbulence profiles from floating LiDAR can be challenging. Fortunately, alternative data sources can provide improved characterisation of winds at offshore locations.

Numerical modelling of wind in the lower few hundred metres of the atmosphere is generally much simpler at remote deepwater locations than over complex onshore terrain. The sophistication, resolution and reliability of such models is advancing rapidly. Mesoscale models can now allow nesting of large scale conditions to horizontal scales less than one kilometre.

Models can also provide many decades of wind data, a major advantage over the site specific measurements gathered to support a wind energy development. Model data are also immediately available at the start of a project at relatively low cost.

At offshore locations these models can be validated and calibrated, just above the sea surface, using well established satellite wind products. Reliable long term statistics of near surface wind can be used to quantify winds at the higher elevations applicable to wind turbines using the wide range of existing standard profile relationships.

Reduced uncertainty in these profile relationships will be of considerable benefit to the wider use of satellite and model data sources in the wind energy industry. This paper describes a new assessment of various industry standard wind profile relationships, using a range of available met mast datasets and numerical models.
Compressible Navier-Stokes Analysis of Floating Wind Turbine Rotor Aerodynamics
Authors: Campobasso M. Sergio , Sanvito Andrea G. , Drofelnik Jernej , Jackson Adrian , Zhou Yang , Xiao Qing , Croce Alessandro
Published: December 2018

The unsteady aerodynamics of floating offshore wind turbine rotors is more complex than that of fixed-bottom turbine rotors, due to additional rigid-body motion components enabled by the lack of rigid foundations; it is still unclear if low-fidelity aerodynamic models, such as the blade element momentum theory, provide sufficiently reliable input for floating turbine design requiring load data for a wide range of operating conditions. High-fidelity Navies-Stokes CFD has the potential to improve the understanding of FOWT rotor aerodynamics, and support the improvement of lower-fidelity aerodynamic analysis models. To accomplish these aims, this study uses an in-house compressible Navier-Stokes code and the NREL FAST engineering code to analyze the unsteady flow regime of the NREL 5 MW rotor pitching with amplitude of 4° and frequency of 0.2 Hz, and compares all results to those obtained with a commercial incompressible code and FAST in a previous independent study. The level of agreement of CFD and engineering analyses in each of these two studies is found to be quantitatively similar, but the peak rotor power of the compressible flow analysis is about 20 % higher than that of the incompressible analysis. This is possibly due to compressibility effects, as the instantaneous local Mach number is found to be higher than 0.4. Validation of the compressible flow analysis set-up, using an absolute frame formulation and low-speed preconditioning, is based on the analysis of the steady and yawed flow past the NREL Phase VI rotor.
Fatigue Life Analysis of Offshore Wind Turbine Support Structures in an Offshore Wind Farm
Authors: Nelson Bryan , Quéméner Yann
Published: December 2018

This study evaluated, by time-domain simulations, the fatigue lives of several jacket support structures for 4 MW wind turbines distributed throughout an offshore wind farm off Taiwan’s west coast. An in-house RANS-based wind farm analysis tool, WiFa3D, has been developed to determine the effects of the wind turbine wake behaviour on the flow fields through wind farm clusters. To reduce computational cost, WiFa3D employs actuator disk models to simulate the body forces imposed on the flow field by the target wind turbines, where the actuator disk is defined by the swept region of the rotor in space, and a body force distribution representing the aerodynamic characteristics of the rotor is assigned within this virtual disk. Simulations were performed for a range of environmental conditions, which were then combined with preliminary site survey metocean data to produce a long-term statistical environment. The short-term environmental loads on the wind turbine rotors were calculated by an unsteady blade element momentum (BEM) model of the target 4 MW wind turbines. The fatigue assessment of the jacket support structure was then conducted by applying the Rainflow Counting scheme on the hot spot stresses variations, as read-out from Finite Element results, and by employing appropriate SN curves. The fatigue lives of several wind turbine support structures taken at various locations in the wind farm showed significant variations with the preliminary design condition that assumed a single wind turbine without wake disturbance from other units.
Load Sensitivity Analysis for a Floating Wind Turbine on a Steel Semi-Submersible Substructure
Authors: Müller Kolja , Guzman Ricardo Faerron , Cheng Po Wen , Galván Josean , Sánchez Miren J. , Rodríguez Raúl , Manjock Andreas
Published: December 2018

The site-specific load verification for floating offshore wind turbines requires the consideration of the complex interaction of the different system components and their environment. Sensitivity analyses help reducing the simulation amount for both fatigue and ultimate load analysis significantly by highlighting relevant load parameters and increase the understanding for the system behavior in its real environment. Aligned with work in the H2020 project LIFES50+, this study investigates different approaches for global sensitivity analysis using quasi-random sampling for the independent variables.

Two different load case groups are analyzed: (1) fatigue loads during power production, (2) ultimate loads during power production and severe sea state. The considered system is the public DTU 10MW turbine’s rotor-nacelle assembly, installed on the public NAUTILUS-10 floating structure. Load simulations are performed by using FAST v8. Simulations are set up based on the LIFES50+ Site B (medium severity). A comparison is made to a similar study with a different platform (Olav Olsen semi-submersible) in order to observe if similar conclusions can be reached for the different floater types.