bluuebunny/crossref_metadata_2025_split huggingface dataset:
COPII genes SEC31A/B are essential for gametogenesis and interchangeable in pollen development in Arabidopsis
Authors: Liu Xiaoyu , Tong Mengjuan , Zhang Aiwei , Liu Mei , Zhao Bingchun , Liu Zhaojiao , Li Zhouyue , Zhu Xu , Guo Yi , Li Rui 
Published: December 2020

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

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

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

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

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

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

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

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

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

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

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

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

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