bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Analysis of Rotor/Wing Flap for Canard Rotor/Wing Aircraft
Authors: Deng Yangping , Mi Baigang 
Published: May 2019

Abstract
In the present study, a kind of blunt trailing edge airfoil with its flap is designed for the purpose of reducing drags of blunt leading and trailing edge airfoils which are used for rotor/wing of CRW. The aerodynamic characteristics of designed flaps and elliptic airfoil which has the same thickness are numerically investigated based on the Reynolds-averaged Navier–Stokes equations and the SST k-ω two-equation turbulence model. The comparisons of aerodynamic force and moment coefficients show that, the lift characteristic is improved for designed flaps, but the drag will not be reduced if the flap has great bending trailing edge, and small bending trailing edge design is suitable for this kind of flap, and it will reduce the drag and improve the longitudinal stability characteristics.
Observer-Based Backstepping Fault-tolerant Control for Spacecraft with Reaction-wheel Failures
Authors: Zhang Z Z , Ye D , Sun Z W 
Published: May 2019

Abstract
In this paper, nonlinear satellite system with actuator faults is considered. To solve the problem of attitude stabilization of satellite under external disturbances and actuator faults, an observer is designed firstly. And the output of the observer is proved to be uniformly ultimately bounded. By using the estimated information of the observer, a backstepping fault-tolerant controller is derived. The proposed controller could achieve attitude stabilization in the presence of actuator faults. Finally, a simulation of attitude stabilization is carried out to illustrate effective of the fault-tolerant controller
Modeling and Simulation of Satellite Attitude Dynamics and Control System using Modelica
Authors: Liu Y H , Shangguan D S , Yao J , Chen L P , Ding J W 
Published: May 2019

Abstract
The control of attitude of a satellite is difficult to verify since several subsystems of different disciplines, e.g., flexible multibody dynamics, machines, electronics and control, are involved and strongly coupled. A traditional method is to model each single discipline subsystem with a domain specific software, and combine them through interfaces. However, the problems are that lots of interfaces between software have to be developed, and manual decoupling of systems should be considered during modelling process. In this Paper, models of the dynamics and the control system are established in a unified modelling software, MWorks, which is an Integrated Development Environment of Modelica. The model can be used to verify the satellite control strategy, and also provide an effective means for satellite attitude control system design. Moreover, on this basis, the whole satellite was modelled to access state parameters changes under the coupling of the dynamic subsystem, the attitude control subsystem, the power supply subsystem, the propulsion subsystem and the integrated electronic subsystem can be synthetically considered.
Optimal Formation Control for Quadrotors with Collision Avoidance Based on Dynamic Constraints
Authors: Jin P F , Yu J Q , Jia Z Y , Yang D 
Published: May 2019

Abstract
This paper studied the optimal formation control of quadrotor UAV based on the dynamic model, and the collision avoidance between quadrotors is considered. By constructing the problem into a standard convex quadratic programming problem, we hope to improve the solving efficiency of the formation control problem. Firstly, the nonlinear dynamic model of quadrotor is linearized and the prediction model is established. Then, the safety zone constraints are transformed from a circular zone to a half-plane zone, making the optimization problem be a standard convex quadratic programming problem. Finally, the quadratic programming problem is solved using distributed receding horizon optimization. Numerical simulations in three-dimensional space show that this method can obtain the optimal formation trajectory with collision avoidance, and can improve the solving efficiency.
Image Processing Techniques for Shock Wave Detection and Tracking in High Speed Schlieren and Shadowgraph Systems
Authors: Li Guoshuai , Burak Agir Muhammed , Kontis Konstantinos , Ukai Takahiro , Rengarajan Sriram 
Published: May 2019

Abstract
Schlieren and shadowgraph photography has been widely used to offer insight into the flow field in aerospace engineering due to their ease of application. The high-speed schlieren and shadowgraph techniques are typically applied to investigation of unsteady shock wave structure including shock reflection patterns and shock wave/boundary layer interactions, etc. Generally, qualitative analysis is performed based on the schlieren and shadowgraph image sequences. To process and analyze the large data set of the high-speed schlieren and shadowgraph images quantitatively, especially for the shock wave detection and tracking, a software was developed based on MATLAB GUI and its image processing toolbox. In this study, the image processing techniques exploited in the software, such as background subtraction, filter, threshold, edge detection, and shock tracking are presented. A case study on the phenomena of shock wave reflection from a solid surface was conducted. The results show that the proper filter method and the background image subtraction can effectively eliminate the image noises in frequency domain, which makes it easier to analyze the flow structure. Moreover, the instantaneous locations of shock waves are detected accurately, and the shock wave propagation speed calculated using the developed software are consistent with those of previous studies.
Neural Partial Differentiation Based Nonlinear Parameter Estimation from Noisy Flight Data
Authors: Mohamed Majeed , Madhavan G , Manikantan R , Priya PS Lal 
Published: May 2019

AbstractThis paper focuses on the application of neural partial differentiation (NPD) approach to estimate the longitudinal parameters of an aircraft HFB 320 from noisy flight data. By exciting both short period and phugoid modes of an aircraft with thrust variation, the aircraft system dynamics becomes highly nonlinear and aerodynamic parameters appears nonlinear to the state trajectories of velocity, AOA, pitch rate and pitch angle. This paper highlights the application of NPD for such a class of nonlinear dynamics; previously it was used only for the estimation of parameter appearing linear to the states. The extracted the nonlinear longitudinal parameters of HFB 320 aircraft are compared with the parameters estimated by using adaptive Unscented Kalman Filter (UKF) approach. Finally, the estimation results are validated by comparing with flight data and the responses obtained from the estimates by adaptive UKF.
Research on Binding Memory of Icon Features Based on Event-related Potential
Authors: Niu Y F , Shi B Z , Qiu L C , Li B , Shen Q Y , Xue C Q 
Published: May 2019

Abstract
The visual characteristics are important factors influencing the cognition and memory of the icon. In order to study the process of memory coding of feature binding in working memory of icon, the experiment requires 20 subjects to remember whether the icon features or feature binding are consistent and response quickly by pressing buttons, and the behaviour data and ERP data of the subjects are recorded. The experiment results show that compared with single feature memory of an icon, the accuracy under the icon-color feature binding memory condition is lower and the reaction time is longer while the P300 brain electric component with larger amplitude can be triggered. Studies have shown that the binding of visual features in icon memory requires additional cognitive resources. Compared with the other three memory conditions, the latency of the P300 under icon semantic-color feature binding is more significant, indicating that the task of semantic coding of icon is more difficult to complete and the cognitive load is greater.
Assurance and Evaluation Method for Reliability Requirements Completion of Aviation Product Based on CMM
Authors: Li Yuan , Wang Wei , Feng Weijia , Zhang Qi , Liu Huichao 
Published: May 2019

Abstract
Modern aviation product needs to meet the reliability requirements during the development process. In this paper, a comprehensive assurance system of reliability requirements completion is established and a method to evaluate the assurance system capabilities of reliability requirements completion based on CMM (Capability Maturity Model) is proposed. The evaluate index system in each level is described and AHP method is applied to determine the weight of each index factor in maturity. The evaluation results can comprehensively and effectively direct the aviation product reliability work during the development process and ultimately ensure the reliability of aviation product meets the requirements.
A Cognitive Study of Multicolour Coding for the Head-up Display (HUD) of Fighter Aircraft in Multiple Flight Environments
Authors: Ling Bai , Bo Li , Bingzheng Shi , Lingcun Qiu , Chengqi Xue , Yafeng Niu 
Published: May 2019

Abstract
By analyzing flight environments and HUD key information of fighter combat mission, based on the theory of color psychology and the regulation of the avionics system, this study simplified 10 kinds of typical flight environments and combined with 7 types of key information colors into 70 color schemes. Taking reaction accuracy and reaction time as performance indicators and testing participants’ subjective feelings, to evaluate pilots’ recognition ability of key information and general information with different color schemes in different flight environments, so as to provide the scientific basis for information coding design of flight HUD. The experimental results showed that the cognitive performance of the bicolor coding is significantly better than that of the monochrome coding by comparing the mean reaction time in various environments, and the cognitive performance of color schemes with the hue of 320 or 340 was better than that of other color schemes in most environments.
Two Problems for a Strip with a Transverse Crack: Exact Solutions
Authors: Guangming Yu , Kovalenko M D , Menshova I V , Kerzhaev A P 
Published: May 2019

Abstract
In this paper for the first time we have constructed the exact solutions of two boundary value problems of the theory of elasticity for an infinite strip with a central transverse crack on which a constant normal stress is given (even-symmetric deformation). In the first problem the sides of the strip are free, while in the second they are rigidly clamped. The solution is represented in the form of series in Papkovich–Fadle eigenfunctions. The expansion coefficients (Lagrange coefficients) have the form of simple Fourier integrals. The final formulas are simple and can easily be used in engineering.
Increased probability of compound long-duration dry and hot events in Europe during summer (1950–2013)
Authors: Manning Colin , Widmann Martin , Bevacqua Emanuele , Van Loon Anne F , Maraun Douglas , Vrac Mathieu 
Published: May 2019

Abstract
The propagation of drought from meteorological drought to soil moisture drought can be accelerated by high temperatures during dry periods. The occurrence of extremely long-duration dry periods in combination with extremely high temperatures may drive larger soil moisture deficits than either extreme occurring alone, and lead to severe impacts. In this study, we propose a framework to both characterise long-duration meteorological droughts that co-occur with extremely high temperatures and quantify their probability. We term these events as long-duration, dry and hot (DH) events and characterise them by their duration (D) and magnitude (M). D is defined as the consecutive number of days with precipitation below 1 mm, while M is the maximum daily maximum temperature during an event. A copula-based approach is then employed to estimate the probability of DH events. The framework is applied to Europe during the summer months of June, July and August. We also assess the change in probability that has occurred over the historical period 1950–2013 and find an increased probability of DH events throughout Europe where rising temperatures are found to be the main driver of this change. Dry periods are becoming hotter, leading to an increase in the occurrence of long-duration dry periods with extremely high temperatures. Some parts of Europe also show an increased probability of long-duration events although the relative change is not as strong as that seen with temperature. The results point to a predominant thermodynamic response of DH events to global warming and reaffirm previous research that soil moisture drought events are setting in faster and becoming more severe due to a change in the contributing meteorological hazards. It is hoped that the framework applied here will provide a starting point for further analysis of DH events in other locations and for the assessment of climate models.
Ultrametric properties for valuation spaces of normal surface singularities
Authors: García Barroso Evelia , Pérez Pedro , Popescu-Pampu Patrick , Ruggiero Matteo 
Published: May 2019

Let

L
L

be a fixed branch – that is, an irreducible germ of curve – on a normal surface singularity

X
X

. If

A
,
B

A,B

are two other branches, define

u

L

(
A
,
B
)
:=

(
L
⋅
A
)

(
L
⋅
B
)

A
⋅
B

u_{L}(A,B) := \dfrac {(L \cdot A) \> (L \cdot B)}{A \cdot B}

, where

A
⋅
B

A \cdot B

denotes the intersection number of

A
A

and

B
B

. Call

X
X

arborescent if all the dual graphs of its good resolutions are trees. In a previous paper, the first three authors extended a 1985 theorem of Płoski by proving that whenever

X
X

is arborescent, the function

u

L

u_{L}

is an ultrametric on the set of branches on

X
X

different from

L
L

. In the present paper we prove that, conversely, if

u

L

u_{L}

is an ultrametric, then

X
X

is arborescent. We also show that for any normal surface singularity, one may find arbitrarily large sets of branches on

X
X

, characterized uniquely in terms of the topology of the resolutions of their sum, in restriction to which

u
L

u_L

is still an ultrametric. Moreover, we describe the associated tree in terms of the dual graphs of such resolutions. Then we extend our setting by allowing

L
L

to be an arbitrary semivaluation on

X
X

and by defining

u

L

u_{L}

on a suitable space of semivaluations. We prove that any such function is again an ultrametric if and only if

X
X

is arborescent, and without any restriction on

X
X

we exhibit special subspaces of the space of semivaluations in restriction to which

u

L

u_{L}

is still an ultrametric.
Thyroid-Like Low-Grade Nasopharyngeal Papillary Adenocarcinoma
Authors: Huang Fengbo , Xiang Xueping , Hong Bo , Min Jie , Li Jinfan 
Published: May 2019

Abstract

Objectives
Thyroid-like low-grade nasopharyngeal papillary adenocarcinoma (TLLGNPPA) is a relatively rare nasopharyngeal tumor. We performed morphological characterization, immunohistochemical profiling, and investigated gene mutations. We also provide clinical follow-up data and brief review of the literature.

Methods
Immunohistochemistry was used to evaluate the expression of TTF-1, CK19, CK7, EMA, TG, Pax-8, CK5/6, S100, and Ki-67. Additionally, in situ hybridization was utilized to identify the presence of EBV. We investigated mutations in hot-spot exons of KRAS/NRAS/BRAF to rule out common mutations seen in thyroid tumors.

Results
Histopathologic examination of four cases identified tumors that were mainly occupied by papillary architectures. One case had a predominantly glandular structure. The tumors expressed TTF-1 and CK19, while TG and Pax-8 were negative. S100 was moderately expressed focally in three cases.

Conclusions
While TLLGNPPA displays a morphological resemblance to papillary thyroid carcinoma (PTC), it is vital to differentiate nasopharyngeal metastasis from PTC for appropriate treatment.
Association Between Serum β-Alanine and Risk of Dementia
Authors: Hata Jun , Ohara Tomoyuki , Katakura Yoshinori , Shimizu Kuniyoshi , Yamashita Shuntaro , Yoshida Daigo , Honda Takanori , Hirakawa Yoichiro , Shibata Mao , Sakata Satoko , Kitazono Takanari , Kuhara Satoru , Ninomiya Toshiharu 
Published: May 2019

Abstract
We examined the association between serum concentrations of β-alanine, a metabolite of carnosine and anserine, and the risk of dementia in a general population of elderly Japanese persons. In 2007, 1,475 residents of Hisayama, Japan, aged 60–79 years and without dementia were divided into 4 groups according to quartiles of serum β-alanine concentrations (quartile 1, lowest; quartile 4, highest) and followed for a median of 5.3 years. During follow-up, 117 subjects developed all-cause dementia (Alzheimer in 77 cases and vascular dementia in 31). The risk of all-cause dementia decreased with increasing serum β-alanine levels after adjustment for potential confounding factors (quartile 2, hazard ratio (HR) = 0.73 (95% confidence interval (CI): 0.45, 1.18); quartile 3, HR = 0.50 (95% CI: 0.28, 0.89); quartile 4, HR = 0.50 (95% CI: 0.27, 0.92); P = 0.01 for trend). A similar inverse association was observed for Alzheimer disease (quartile 2, HR = 0.78 (95% CI: 0.44, 1.38); quartile 3, HR = 0.53 (95% CI: 0.26, 1.06); quartile 4, HR = 0.53 (95% CI: 0.25, 1.10); P = 0.04 for trend) but not for vascular dementia. We found that higher serum β-alanine levels were significantly associated with lower risks of all-cause dementia and Alzheimer disease. Because serum β-alanine levels reflect intakes of carnosine/anserine, higher intakes of carnosine/anserine might be beneficial for the prevention of dementia.
Evaluation of Intussusception After Oral Monovalent Rotavirus Vaccination in South Africa
Authors: Groome Michelle J , Tate Jacqueline E , Arnold Marion , Chitnis Milind , Cox Sharon , de Vos Corné , Kirsten Mari , le Grange Susanna M , Loveland Jerome , Machaea Sello , Maharaj Ashwini , Andrews Nick , Madhi Shabir A , Parashar Umesh D 
Published: May 2019

Abstract

Background
Postlicensure studies have shown an association between rotavirus vaccination and intussusception. We assessed the risk of intussusception associated with Rotarix (RV1) administration, at 6 and 14 weeks of age, in an upper-middle-income country, South Africa.

Methods
Active prospective surveillance for intussusception was conducted in 8 hospitals from September 2013 through December 2017. Retrospective case enrollment was done at 1 hospital from July 2012 through August 2013. Demographic characteristics, symptom onset, and rotavirus vaccine status were ascertained. Using the self-controlled case-series method, we estimated age-adjusted incidence rate ratios within 1–7, 8–21, and 1–21 days of rotavirus vaccination in children aged 28–275 days at onset of symptoms. In addition, age-matched controls were enrolled for a subset of cases (n = 169), and a secondary analysis was performed.

Results
Three hundred forty-six cases were included in the case-series analysis. Post–dose 1, there were zero intussusception cases within 1–7 days, and 5 cases within 8–21 days of vaccination. Post–dose 2, 15 cases occurred within 1–7 days, and 18 cases within 8–21 days of vaccination. There was no increased risk of intussusception 1–7 days after dose 1 (no cases observed) or dose 2 (relative incidence [RI], 1.71 [95% confidence interval {CI} .83–3.01]). Similarly, there was no increased risk 8–21 days after the first (RI, 4.01 [95% CI, .87–10.56]) or second dose (RI, .96 [95% CI, .52–1.60]). Results were similar for the case-control analysis.

Conclusions
The risk of intussusception in the 21 days after the first or second dose of RV1 was not higher than the background risk among South Africa infants.

Clinical Trials Registration
South African National Clinical Trial Register (DOH-27-0913-4183).
Genetic variation at the coronary artery disease risk locus GUCY1A3 modifies cardiovascular disease prevention effects of aspirin
Authors: Hall Kathryn T , Kessler Thorsten , Buring Julie E , Passow Dani , Sesso Howard D , Zee Robert Y L , Ridker Paul M , Chasman Daniel I , Schunkert Heribert 
Published: May 2019

Abstract

Aims
Efficacy of aspirin in primary prevention of cardiovascular disease (CVD) may be influenced by a common allele in guanylate cyclase GUCY1A3, which has been shown to modify platelet function and increase CVD risk.

Methods and results
We investigated whether homozygotes of the GUCY1A3 rs7692387 risk (G) allele benefited from aspirin in two long-term, randomized placebo-controlled trials of aspirin in primary CVD prevention: the Women’s Genome Health Study (WGHS, N = 23 294) and a myocardial infarction (MI, N = 550) and stroke (N = 382) case–control set from the Physician’s Health Study (PHS, N = 22 071). Bleeding risk was evaluated in the WGHS. In the placebo group of the WGHS, the GUCY1A3 risk (G) allele was confirmed to increase CVD risk [hazard ratio 1.38; 95% confidence interval (CI) 1.08–1.78; P = 0.01]. Random-effects meta-analysis of the WGHS and PHS revealed that aspirin reduced CVD events among risk allele homozygotes [G/G: odds ratio (OR) 0.79; 95% CI 0.65–0.97; P = 0.03] but increased CVD events among non-risk allele carriers (e.g. G/A: OR 1.39; 95% CI 1.03–1.87; P = 0.03) thus implying an interaction between genotype stratum and aspirin intake (P interaction = 0.01). Bleeding associated with aspirin increased in all genotype groups, with higher risks in heterozygotes.

Conclusion
In two randomized placebo-controlled trials in the setting of primary prevention, aspirin reduced the incidence of CVD events in individuals homozygous for the GUCY1A3 risk (G) allele, whereas heterozygote individuals had more events when taking aspirin.
Weight and weight change and risk of atrial fibrillation: the HUNT study
Authors: Feng Tingting , Vegard Malmo , Strand Linn B , Laugsand Lars E , Mørkedal Bjørn , Aune Dagfinn , Vatten Lars , Ellekjær Hanne , Loennechen Jan P , Mukamal Kenneth , Janszky Imre 
Published: May 2019

Abstract

Aims
Although obesity has been associated with risk of atrial fibrillation (AF), the associations of long-term obesity, recent obesity, and weight change with AF risk throughout adulthood are uncertain.

Methods and results
An ambispective cohort study was conducted which included 15 214 individuals. The cohort was created from 2006 to 2008 (the baseline) and was followed for incident AF until 2015. Weight and height were directly measured at baseline. Data on previous weight and height were retrieved retrospectively from measurements conducted 10, 20, and 40 years prior to baseline. Average body mass index (BMI) over time and weight change was calculated. During follow-up, 1149 participants developed AF. The multivariable-adjusted hazard ratios were 1.2 (95% confidence interval 1.0–1.4) for average BMI 25.0–29.9 kg/m2 and 1.6 (1.2–2.0) for average BMI ≥30 kg/m2 when compared with normal weight. The association of average BMI with AF risk was only slightly attenuated after adjustment for most recent BMI. In contrast, current BMI was not strongly associated with the risk of AF after adjustment for average BMI earlier in life. Compared with stable BMI, both loss and gain in BMI were associated with increased AF risk. After adjustment for most recent BMI, the association of BMI gain with AF risk was largely unchanged, while the association of BMI loss with AF risk was weakened.

Conclusion
Long-term obesity and BMI change are associated with AF risk. Obesity earlier in life and weight gain over time exert cumulative effects on AF development even after accounting for most recent BMI.