bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of the fidelity level of numerical simulations on the wake meandering phenomenon
Authors: Coudou N. , Moens M. , van Beeck J. , Bricteux L. , Chatelain P. 
Published: July 2019

Abstract
The aim of this paper is to verify that a modeling approach affordable at wind farm scale, in this case a fourth-order finite differences code combined with a rotating actuator disk, provides equivalent results in terms of wake meandering compared to a method with a higher fidelity level, i.e. a Vortex Particle-Mesh Method combined with immersed lifting lines. The analysis is performed on the wake centerlines obtained from Large Eddy Simulations of an isolated NREL 5-MW wind turbine subject to several synthetic turbulent inflows: 6%, 10%, and 15% turbulence intensity. A direct comparison of the wake centerlines reveals a good match between the two approaches up to five rotor diameters. Concerning the amplitude and wavelength of the wake meandering, the lower fidelity code leads to larger amplitudes and shorter wavelengths. Assuming that Taylor’s frozen turbulence hypothesis is applicable, the Strouhal number St is computed as the ratio between the rotor diameter and the wavelength. Obtained values are such that 0.22 ⩽ St ⩽ 0.4.
Comparative study on the wake description using actuator disc model with increasing level of complexity
Authors: Navarro Diaz Gonzalo P. , Saulo A. Celeste , Otero Alejandro D. 
Published: July 2019

Abstract
The present work evaluates the benefits obtained when different levels of geometric and aerodynamic information of wind turbine blades are included in the actuator disc (AD) model, progressively increasing its descriptive capabilities. A novel AD model is presented, equivalent in precision to the AD coupled with the blade element momentum method, but avoiding the need to modify the CFD code by the use of a pre-calculated table. It is compared against three classical AD models, particularly aiming at the simulation of the wind farm wake interaction. The NREL-5MW reference wind turbine is adopted as test case, and configurations with single and two shifted wind turbines are analyzed.
Coupling the actuator line method to the high order meteorological LES model Meso-NH to study wind farm wakes impacts on local meteorology
Authors: Joulin PA , Mayol ML , Blondel F , Masson V , Rodier Q , Lac C 
Published: July 2019

Abstract
Offshore wind energy is now reaching the technological maturity, its capacity is increasing all over the world and this trend is projected to continue for several more years. Given this expectation, a better understanding of the relationship between the presence of wind farms and the atmospheric boundary layer is needed. Turbulent wakes produced by wind turbines can significantly impact the flow dynamics within wind farms and downstream of them. Operating offshore parks have already shown losses on energy production and effects on the local climate. In order to analyse the interactions occurring during these impacts, a new tool has been developed. This numerical tool is a coupling between the Actuator Line Method (ALM) and the open-source, non-hydrostatic mesoscale atmospheric model Meso-NH, based on the Large Eddy Simulation (LES) framework. The coupled Meso-NH + ALM system is first validated by using the experimental data obtained during the New MEXICO experiments. In particular, simulated and experimental loadings along the blades are compared. Then, a simulation of an idealized Horns Rev wind farm is performed using met mast measurements and reanalysis data for the “Horns Rev 1 photo case” as initial conditions. This new coupled system allows the exploration of the impact of wind farms on the lower levels of the atmosphere.
Global Blockage Effects in Wind Farms
Authors: Segalini A , Dahlberg J-Å 
Published: July 2019

Abstract
An experimental and numerical study of wind-farm blockage has been performed to quantify the velocity reduction that the first row of a wind farm experiences due to other turbines downstream. In the present study, an attempt is made to demonstrate the existence of a two-way coupling between individual turbines and wind farm. Several staggered layouts were tested in the wind-tunnel experiments by changing the spacing between rows, spacing between the turbines in the same row and the amount of wind turbines involved. Three turbines located in the first row were monitored to assess their sensitivity to the turbines downstream. One of the experiments was replicated by means of numerical simulations performed in ORFEUS, a linearised code developed at KTH, in order to complement the experimental results. Simulations were performed at the same thrust coefficient and with a more distant ceiling to assess the eventual interference of the ceiling on the experimental results. Additionally, simulations performed at different thrust coefficients were done to assess its effect on the blockage phenomenon.
Benchmarks for Model Validation based on LiDAR Wake Measurements
Authors: Doubrawa P , Debnath M , Moriarty P J , Branlard E , Herges T G , Maniaci D C , Naughton B 
Published: July 2019

Abstract
Technology development and design decisions in wind energy are often based on results from simulations performed for individual wind turbines or entire wind plants. It is therefore critical to ensure that the models being used for research and industry applications in wind energy be thoroughly validated against measurements. A full-system validation of wind plant simulations must consider the atmospheric inflow, the response of the wind turbines, and their wakes. This task is complicated by the lack of freely available, quality-controlled, high-quality measurements. Here, such measurements are used to offer a validation exercise that can be used to assess the accuracy of models of any fidelity level. When it comes to real-world measurements, the dataset considered herein is simple in terms of terrain but exhibits pronounced diurnal cycles. Instead of a full-scale wind plant, we consider an individual research-scale, utility wind turbine instrumented for power and loads measurements. Three benchmarks are defined, with increasing levels of complexity: near neutral, slightly unstable, and very stable atmospheric stratification. Through comparisons between observations and simulations, the benchmarks provide complementary information about the model performance and its ability to reproduce mean and dynamic wake characteristics. This article describes the measurements and methodology used to define these benchmarks and provides the information required to perform simulations and conduct the model-measurement comparison. The objective is to provide a robust wake model validation exercise open to anyone, which will serve to minimize uncertainty in model validation practices related to varying methodologies across simulation tools and users.
Wind Farm Wakes Simulated Using WRF
Authors: Pryor S C , Shepherd T J , Barthelmie R J , Hahmann A N , Volker P 
Published: July 2019

AbstractOptimization of wind turbine (WT) arrays to maximize system-wide power production (i.e. minimize ‘wind-theft’) requires high-fidelity simulations of array-array interactions at the regional scale. This study systematically compares two parameterizations (Fitch and EWP) developed to describe wind farm impacts on atmospheric flow in the Weather Research and Forecasting (WRF) model. We present new year-long simulations for a nested domain centred on Iowa (the state with highest WT density) in the US Midwest that employ real WT characteristics and locations. Simulations with Fitch and EWP indicate similar seasonality in system-wide gross capacity factors (CF) for WT operating in Iowa, but the gross CF are systematically higher in simulations using EWP. The mean gross CF from the Fitch scheme is 44.1%, while that from EWP is 46.4%. These differences in CF are due to marked differences in the intensity and vertical profile of wakes simulated by the two approaches. Output from EWP also indicates much smaller near-surface climate impacts from WT. For example, when summertime hourly near-surface temperature (T2m) from the 299 WT grid cells are compared (i.e. EWP or Fitch minus noWT) the results show warming of nocturnal temperatures (lowest decile of T2m) but the maximum warming is considerably larger in simulations with the Fitch scheme.
Why curved wind turbine rows are better than straight ones
Authors: Krabben I G W , van der Laan M P , Koivisto M. , Larsen T J , Pedersen M M , Hansen K S 
Published: July 2019

Abstract
Wind turbine wake effects in wind farms not only reduce the wind farm power production but also influence the wind farm power dependency on wind direction. In this paper, the wake effects in wind farm layouts consisting of curved and straight wind turbine rows are studied using engineering wake models and a Reynolds-averaged Navier-Stokes model. These models predict a similar annual energy production for both wind farm layouts, but show stronger wake losses in the aligned wind directions for a rectangular wind farm layout, while the wake losses for a curved wind farm layout are more spread out over a larger wind direction sector. An energy system level simulation predicts that the enhanced spreading of wake losses over wind directions results in less hourly variability in energy generation on a Danish energy system level. Thus, our results show that a curved wind farm layout is more favorable compared to a wind farm layout with straight rows.
Investigation of oxygen vacancy migration energy in yttrium doped cerium
Authors: Lam Le Thu , Hung Vu Van 
Published: July 2019

Abstract
Using the statistical moment method, the analytic expression of vacancy migration energy in yttria doped cerium (YDC) is derived within the fourth order moment approximation. This expression depends strongly on the interaction potentials between the diffusing oxygen ion and the surrounding cations. Our results show the predominant direction of oxygen vacancy migration and the influence of cation barriers on oxygen vacancy diffusion. The dependences of the migration energy on temperature and dopant concentration are evaluated in detail. Calculated results are compared with other theoretical results.
Zero bias anomaly in the two-site Anderson-Hubbard model with Gaussian distribution for disorder
Authors: Nguyen Oanh K. T. , Tran Nam Van , Bach Giang Huong 
Published: July 2019

Abstract
The Anderson-Hubbard model considers the correlation between disorder and other interactions in a strongly correlated electron system. Both disorder and correlations drive the metal-insulator transition but the densities of states behave in different ways. The zero bias anomaly (ZBA) referring to the V-dip shape of the density of states at the Fermi energy occurs in the strong disorder and strong interaction regime instead of a hard Coulomb gap in an insulator phase of strongly correlated interacting systems. In this paper, we use a Gaussian distribution for disorder to examine a two-site Anderson-Hubbard model. We also explain comprehensively the relationship between the phase diagram of ground states with various numbers of electrons and the behavior of the density of states. Furthermore, we want to investigate the effect of disorder distribution on the formation of the ZBA which originates from a hopping mechanism in two specific configurations.
Theoretical predictions of two-dimensional covalent organic frameworks (COF) with hexagonal topologies
Authors: Duong Le Nam , Tuoc Vu Ngoc , Thao Nguyen Thi 
Published: July 2019

Abstract
Recently, covalent organic frameworks (COFs) - a new class of highly ordered organic crystalline porous polymers, have attracted huge research interest because of their unique structures and potential applications in gas separation/storage, catalysis, energy strorage and optoelectronic materials development. We have studied several structure’s series of hexagonal shapes to explore the applicability of the formation of two-dimensional (2D) COFs from various pre-defined individual building blocks using Density Functional based tight-binding (DFTB) method. Different high-symmetry stackings, e.g. AA and AB stacking sequence are also designed and investigated. The designed series’s band gaps are found to be ranging from 1.7 to 4.0 eV. Further, the COF series, revealing a variety of promising mechanical and electronic properties, which can potentially find future realistic applications.
Cluster-root bearing Proteaceae species show a competitive advantage over non-cluster root species
Authors: Fajardo Alex , Piper Frida I 
Published: July 2019

Abstract

Background and aims
Cluster roots (CRs) constitute a special root adaptation that enables plants to take up nutrients, especially phosphorus (P), from soils with low nutrient availability, including recent volcanic deposits. It is unclear, however, how CR species interact with non-cluster root (NCR) species, and how substrates’ fertility modulates potential interactions.

Methods
We experimentally assessed the net interaction between CR and NCR species using two substrates of contrasting fertility: nutrient-rich nursery mix and tephra (low P availability). We planted seedlings of two southern South America (SSA) Proteaceae species and two NCR Nothofagus species in pairs (conspecifics and heterospecifics) and as singles. We analysed the effect of seedling neighbours on survival, growth performance (e.g. total biomass and leaf area), and leaf and substrate nutrient concentrations (including manganese [Mn], a proxy for P-acquisition efficiency through CR activity) using the relative interaction index (RII).

Key Results
After three growing seasons, we found that 1) Proteaceae species had fewer CRs, lower CR biomass, and grew less in the tephra than in the nursery substrate; 2) Nothofagus species did not improve their survival and growth in the presence of Proteaceae species in any substrate; 3) contrary to Nothofagus, Proteaceae species improved their growth more when planted with any neighbour (including conspecifics) than when planted alone, which was accompanied by a significant accretion of leaf P; and 4) the presence of a neighbour increased the final N and P concentrations in the nursery substrate, regardless of species identity.

Conclusions
CRs provide Proteaceae a competitive advantage over NCR species at the seedling stage, which may have important consequences for species coexistence and community structuring. The investigated SSA Proteaceae, which have not evolved in nutrient-impoverished soils as their relatives in southwestern Australia and South Africa, improve their growth when cultivated in pairs, especially in nutrient-rich substrates.
Lame Ducks and Local Fiscal Policy: Quasi-Experimental Evidence from Portugal
Authors: da Fonseca Mariana Lopes 
Published: July 2019

Abstract
I use the introduction of mayoral term limits in Portugal to identify how an exogenous variation in eligibility for office affects policy decisions. Relying on a quasi-experimental difference-in-differences approach, I find that term-limited incumbents pursue more conservative fiscal policies than those who are eligible for re-election. Heterogeneous effects show that the treatment effects primarily reflect the behaviour of right-leaning, term-limited incumbents. Results are in line with a model in which right-leaning officeholders try to maintain a good reputation by pleasing an electorate prone to redistribution while they are eligible, but adopt policies closer to their true preferences when term-limited.
Inflammatory bowel disease- and Barrett’s esophagus-associated neoplasia: the old, the new, and the persistent struggles
Authors: Karamchandani Dipti M , Zhang Qin , Liao Xiao-Yan , Xu Jing-Hong , Liu Xiu-Li 
Published: July 2019

AbstractEarly diagnosis of and adequate therapy for premalignant lesions in patients with inflammatory bowel disease (IBD) and Barrett's esophagus (BE) has been shown to decrease mortality. Endoscopic examination with histologic evaluation of random and targeted biopsies remains the gold standard for early detection and adequate treatment of neoplasia in both these diseases. Although eventual patient management (including surveillance and treatment) depends upon a precise histologic assessment of the initial biopsy, accurately diagnosing and grading IBD- and BE-associated dysplasia is still considered challenging by many general as well as subspecialized pathologists. Additionally, there are continuing updates in the literature regarding the diagnosis, surveillance, and treatment of these disease entities. This comprehensive review discusses the cancer risk, detailed histopathological features, diagnostic challenges, and updates as well as the latest surveillance and treatment recommendations in IBD- and BE-associated dysplasia.
An Introduction to Pathology in Biomedical Research: A Mission-Critical Specialty for Reproducibility and Rigor in Translational Research
Authors: Brayton Cory F , Boyd Kelli L , Everitt Jeffrey L , Meyerholz David K , Treuting Piper M , Bolon Brad 
Published: July 2019

Abstract
This issue of ILAR Journal focusses on pathology and pathologists in biomedical research, more specifically in preclinical translational research involving (nonhuman) animals, emphasizing academic settings. Considerations in study design and planning to maximize benefit from pathologists and pathology resources are reviewed. Adjunctive technologies including molecular techniques, digital pathology, and imaging are highlighted. Additional considerations regarding safety and regulatory concerns, and veterinary clinical trials are reviewed as well. Pathology has been fundamental to understanding clinical disease, remains fundamental to diagnosing disease, and is required in drug and device development. Broader integration of pathology expertise and well-designed pathology investigations have much to offer research rigor and reproducibility, and successful translation from biomedical research.
What Is the Evidence to Support a Correlate of Protection for Measles? A Systematic Review
Authors: Bolotin Shelly , Hughes Stephanie L , Gul Nazish , Khan Sumaiya , Rota Paul A , Severini Alberto , Hahné Susan , Tricco Andrea , Moss William J , Orenstein Walter , Turner Nikki , Durrheim David , Heffernan Jane M , Crowcroft Natasha 
Published: July 2019

Abstract

Background
Many studies assume that the serologic correlate of protection from measles disease is 120 mIU/mL. We systematically reviewed the literature to examine the evidence supporting this correlate of protection.

Methods
We searched peer-reviewed and gray literature for articles reporting a measles correlate of protection. We excluded studies focusing on special populations, infants aged &lt;9 months, and those using animal models or nonstandard vaccines or administration routes. We extracted and synthesized data from full-text articles that met inclusion criteria.

Results
We screened 14 778 articles and included 5 studies in our review. The studies reported either preexposure antibody concentrations of individuals along with a description of symptoms postexposure, or the proportion of measles cases that had preexposure antibody concentrations above a threshold of immunity specified by the authors. Some studies also described secondary antibody responses upon exposure. The variation in laboratory methods between studies made comparisons difficult. Some of the studies that assumed 120 mIU/mL as a correlate of protection identified symptomatic individuals with preexposure titers exceeding this threshold.

Conclusions
Our findings underscore the scant data upon which the commonly used 120 mIU/mL measles threshold of protection is based, suggesting that further work is required to characterize the measles immunity threshold.
Intrahousehold Bargaining, Female Autonomy, and Labor Supply: Theory and Evidence from India
Authors: Heath Rachel , Tan Xu 
Published: July 2019

AbstractStandard models of labor supply predict that unearned income decreases labor supply. We propose an alternative noncooperative household model in which a woman’s unearned income improves her autonomy within the household, which raises her gains from working and can increase her labor supply. We find empirical support for this model, using women’s exposure to the Hindu Succession Act in India as a source of exogenous variation in their unearned income. Exposure to the Hindu Succession Act increases a woman’s labor supply by between 3.8 and 6.1 percentage points, particularly into high-paying jobs. Autonomy increased by 0.17 standard deviations, suggesting that control of income is a potential channel for these effects. Thus, policies that empower women can have an additional impact on the labor market, which can further reinforce autonomy increases.
Sleep in Huntington’s disease: a systematic review and meta-analysis of polysomongraphic findings
Authors: Zhang Ye , Ren Rong , Yang Linghui , Zhou Junying , Li Yun , Shi Jie , Lu Lin , Sanford Larry D , Tang Xiangdong 
Published: July 2019

AbstractStudy ObjectivesDisturbed overnight sleep is a prominent feature of advanced stage Huntington’s disease (HD). Several polysomnography (PSG) studies have reported significant changes of sleep in HD patients, but the findings are not unequivocal. To date, no meta-analysis has investigated the PSG changes in HD patients. The present study meta-analyzed results from studies examining the PSG changes in HD patients compared with controls.MethodsA literature search performed in MEDLINE, EMBASE, All EBM databases, PsycINFO, and CINAHL databases identified seven studies involving 152 HD patients and 144 controls which were included in our meta-analysis.ResultsPooled results indicated decreased sleep efficiency, percentage of slow wave sleep and rapid eye movement sleep, and increased percentage of N1 sleep, wake time after sleep onset, and rapid eye movement sleep latency in HD patients compared with controls. We found high heterogeneity in the effect sizes and no indication of systematic publication biases across studies. Meta-regression analyses showed that some of the heterogeneity was explained by age, body mass index (BMI), CAG repeat length, and disease severity of HD patients.ConclusionsOur study showed that polysomnographic abnormalities are present in HD. Our findings also underscore the need for a comprehensive PSG assessment of sleep changes in patients with HD. Furthermore, the effects of age, BMI and CAG repeat length on sleep changes should be carefully considered and closely monitored in the management of HD.