bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Detection for Free Flight
Authors: Tallman Jake , Yu David , Pantoja Maria 
Published: March 2021

Abstract
Thermals are regions of rising hot air formed on the ground through the warming of the surface by the sun. Thermals are commonly used by birds and glider pilots to extend flight duration, increase cross-country distance, or simply to conserve energy. This kind of powerless flight using natural sources of lift is called soaring. Once a thermal is encountered, the pilot flies in circles to keep within the thermal, so gaining altitude before flying off to the next thermal and towards the destination. A single thermal can net a pilot thousands of meters of elevation gain. Estimating thermal locations is not an easy task, pilots look for different indicators like color variation on the ground because the difference in the amount of heat absorbed by the ground varies based on the color/composition, birds circling in an area, and certain types of cloud formations (cumulus clouds). The above methods are not always reliable enough and pilots study the conditions for thermals by estimating solar heating of ground (cloud cover and time year/date) and also the lapse rate and dew point of air. In this paper, we present a Machine Learning based solution to forecast thermals. Since pilots in general record many of their flights locally and sometimes upload them to databases, we use the flight data uploaded to determine where the pilot encountered thermals and together with other information (weather and satellite images corresponding to the location and time of the flight) train an algorithm to automatically predict the location of thermals given as input the current weather conditions and terrain information (obtained from Google Earth Engine). Results show that our model is able to converge on the training and validation set with a loss bellow 1%.
Educational Gaps in Latin American childhood: Regional Inequality in Learning Deprivation with Local Modulations
Authors: Sánchez-Restrepo Harvey , Louçã Jorge 
Published: March 2021

AbstractThis research is a secondary analysis of a multivariate dataset coming from a large-scale assessment, coordinated by UNESCO in 15 Latin American countries (LAC), which was carried out for estimating the level of learning achievements of students at the end of primary education. The objective is to estimate the lack of quality in education across the region, based on the sociological concepts of absolute and relative deprivation, through a new learning deprivation index, as well as to offer robust evidence on the deep inequalities in learning outcomes among groups of population. Main results show strong evidences on how big gaps in learning outcomes are associated with socioeconomic status of students, pointing out that the profound lack of equity in LAC has become structural inequality beyond borders. This study establishes three milestones in educational research using the best available data. First, provides a direct method for estimating learning deprivation. Second, intra-and inter-country inequality is estimated from comparable socioeconomic deciles at regional level. Third, it was found that the intensity of learning deprivation, as a function of the SES, has an interplay with the wealth of the country and it is not possible to apply same strategies in all countries for developing inclusive and equitable educational for all.
Two Degree-of-freedom μ Synthesis Control for Turbofan Engine with Slow Actuator Dynamics and Uncertainties
Authors: Zhu Meiyin , Wang Xi , Miao Keqiang , Pei Xitong , Liu Jiashuai 
Published: March 2021

Abstract
To address the robust control problem of turbofan engine with slow actuator dynamics and uncertainties, we present a two degree-of-freedom (TDOF) μ synthesis control scheme. The actuators with slow dynamics and parameter uncertainties are considered in the control design. To handle the problem of rapid change of reference command, feed forward control (one freedom) is adopted, and feedback control (another freedom) is introduced to ensure good servo tracking and disturbance attenuation. The performance and the control output weighting functions are properly devised to guarantee servo tracking and disturbance attenuation performance of the devised controller. The D-K iterative algorithm is adopted to calculate the TDOF μ synthesis controller. A turbofan engine with slow actuator dynamics and parameter uncertainties is adopted for simulation. The effectiveness and superiority of the devised TDOF μ synthesis controller are verified by a series of simulation analyses. The simulation analyses show that the TDOF μ synthesis control scheme developed in this paper can handle the robust control problem of turbofan engines, despite the negative influence of the slow actuator dynamics and uncertainties. The comparison shows that the TDOF μ synthesis controller provides better performance than the PI controller and the LMI optimization gain scheduled controller do.
Two-Timescale Missile Autopilot Design Based on Suboptimal Control
Authors: Li Zongxing , Zhang Rui 
Published: March 2021

Abstract
Aiming at the missile longitudinal motion model with obvious aerodynamic nonlinearity, this paper proposes a two-timescale design method of missile autopilot based on suboptimal control. By dividing the system states into fast and slow states based on different timescales, the corresponding fast and slow control inputs are designed. This paper introduces suboptimal control and robust control to enable the system to have good dynamic response characteristics, and the system’s ability to suppress various uncertainties is guaranteed. By applying the Lyapunov method, the stability conditions of the system are given. Finally, the simulation results show that the system has good dynamic characteristics and robustness.
Research and Engineering Implementation of Laser Point Cloud 3D Target Recognition Algorithm in Complex Scene
Authors: Shi Shixi , Zhou Yifu , Sun Yang , Ding Ziquan , Hou Xiaoxiang , Li Tao , Cao Jihong , Tan Yijun , Deng Bu , Li Hongyi , Zhang Jun , Gu Yaping 
Published: March 2021

Abstract
Here are many challenges for target detection in the complex scenes. In the real scene, such as the diversity of the type, quantity and shape of the parts on the workpiece plates, the model construction and rapid detection need to deal with the complex and changeable scene, and the large-scale massive point cloud data challenges the operational efficiency and accuracy of visibility analysis technology. In this paper, the 3D modeling method based on computer graphics is proposed by using the displacement laser sensor as the digital representation of 3D complex scene on the scanning point cloud, which realizes the fast extraction of semantic target feature parameters under complex conditions. The multi-dimensional parameter-based saliency feature and fusion multiple filtering algorithm is built to obtain a fast and high-precision intelligent template recognition detection method. Based on SOC embedded engineering technology, the detection algorithm is realized by software programming. The two-dimensional mechanical motion platform is developed to test the workpiece plate applied to wheel hub of high-speed rail train, and the recognition accuracy is more than 99%.
Iterative PSO Algorithms for RAP Problems with k-out-of-n:G Subsystems and Mixing of Components and Changing k Values
Authors: Li Dongkui , Wulantuya  , Zhu Yanlong , Li Xuebao , Yang Liiping , Xia Yuqin 
Published: March 2021

AbstractThe subsystem is k-out-of-n: G configuration, and the subsystem has component mixing (that is, subsystem components can be selected from different kinds of components), and the minimum number of normal working elements (k value) that can be selected as well as can change RAP problem. On the basis of giving a solution construction method and generating a new solution by symmetric bit transformation technology, an iterative DPSO (discrete particle swarm optimization) algorithm with fixed-compression coefficient and dynamic inertia weight is designed to solve the model. The calculate results indicate that the algorithm can effectively give the optimal solution for each test case (which is consistent with the existing optimal results in the literature). PSO algorithm can effectively solve the RAP problem of subsystems with mixed components and varyingkvalues. When the size of subsystems (k-out-of-n: G) is large, and the solution of the model is limited by microcomputers.
Prediction and Optimization of Full-Vehicle Road Noise Based on Random Response Analysis
Authors: Cao Cheng , Meng Dejian , Zhao Ye , Shu Yuan , Zhang Menghao , Zhang Lijun 
Published: March 2021

Abstract
Based on the theory of random response analysis, a road noise prediction method is proposed. A finite element model of acoustic-structure coupling for the full-vehicle was established, and the road surface texture measured in the actual vehicle test was converted into a power spectrum, which is the excitation of FE model. Under the conditions of coast down from 80km/h to 20km/h on Belgian pavement, the prediction of road noise in the 20- 200Hz frequency band was achieved. The driver’s ear sound pressure obtained from the simulation is in good agreement with the test results, which verifies the effectiveness of the simulation model and prediction method. The sensitivity of the driver’s ear-side sound pressure level to the stiffness of the suspension mounts was further analysed. The stiffness of the bushings that had a large impact was determined. The Response Surface Methodology was used to optimize road noise. The results show that the average sound pressure level near the driver’s ear is reduced by 1.81 dBA. The simulation analysis and optimization methods introduced in this paper can provide a reference for the virtual development process of vehicle road noise.
Variable Parameter and Real-time Co-simulation Method and Its Application in the Analysis of Train Dynamic Air Consumption Law
Authors: Zuo Jianyong , Huang Shuling 
Published: March 2021

Abstract
System simulation technology is currently the mainstream technology for system design optimization. Parametric design can greatly improve the speed of model generation and modification by establishing various constraint relations. In this paper, the parameter design method is improved and combined with the system simulation technology, and the variable parameter and real-time co-simulation method is proposed. In order to verify the feasibility of the method in system dynamic performance analysis, this paper builds a real-time co-simulation platform based on AMESim, and applies it to the analysis process of train dynamic air consumption law. The results prove that the method is beneficial to reduce the workload of designers, and can be applied to the design optimization, analysis and tracking of complex systems.
Gamification for climate change engagement: review of corpus and future agenda
Authors: Fernández Galeote Daniel , Rajanen Mikko , Rajanen Dorina , Legaki Nikoletta-Zampeta , Langley David J , Hamari Juho 
Published: March 2021

AbstractBoth bottom-up and top-down initiatives are essential for addressing climate change effectively. These include initiatives aiming to achieve widespread behavioral change towards reduction of greenhouse gas emissions as well as pursuing education regarding adaptation measures. While awareness of the issue of climate change is now pervasive, and actions are being taken at all levels of society, there is still much to do if international goals are to be met. Games and gamification offer one approach to foster both behavioral change and education. In this paper, we investigate the state-of-the-art of game-based climate change engagement through a systematic literature review of 64 research outputs comprising 56 different gamified approaches. Our analysis of the literature reveals a trend of promising findings in this nascent and growing area of research, suggesting the potential to impact multiple engagement dimensions simultaneously, as well as create an engaging gameful experience. Overall, the corpus appears to offer a fruitful balance in foci between climate science, mitigation, and adaptation, as well as a variety of formats in game-based approaches (i.e. digital, analog, and hybrid). However, shortcomings were also observed, such as geographic and demographic imbalances and the short duration of interventions. The reviewed studies yield a large number of results indicating climate change engagement through gamification, especially in the form of cognitive engagement, affect towards climate change-related topics, and in-game behavioral engagement with others. Nevertheless, heterogeneity in terms of contexts, designs, outcomes, and methods, as well as limited rigor in research designs and reporting, hinders drawing overall conclusions. Based on our review, we provide guidelines regarding contexts, interventions, results, and research quality and internal validity for advancing the space of game-based interventions for climate change engagement.
Near lightcone thermal conformal correlators and holography
Authors: Parnachev Andrei 
Published: March 2021

Abstract
Heavy–heavy–light–light (HHLL) correlators of pairwise identical scalars in CFTs with a large central charge in any number of dimensions admit a double scaling limit where the ratio of the heavy conformal dimension to the central charge becomes large as the separation between the light operators becomes null. In this limit the stress tensor sector of a generic HHLL correlator receives contributions from the multi stress tensor operators with any number of stress tensors, as long as their twist is not increased by index contractions. We show how one can compute this leading twist stress tensor sector when the conformal dimension of the light operators is large and the stress tensor sector approximates the thermal CFT correlator. In this regime the value of the correlator is related to the length of the spacelike geodesic which approaches the boundary of the dual asymptotically AdS spacetime at the points of light operator insertions. We provide a detailed description of the infinite volume limit. In two spacetime dimensions the HHLL Virasoro vacuum block is reproduced, while in four spacetime dimensions the result is written in terms of elliptic integrals.
Study on Rule of Heavy Metal Cu2+ in Small and Medium-Sized Tailings Ponds under Rainfall-Evaporation-Transpiration Coupling
Authors: Chen Hongdan , Hao Zhe , Zhang Ying , Teng Da , Wang Xiaoming , Zhang Qian 
Published: March 2021

Abstract
In order to research the heavy metal migration rule of small and medium-sized tailings ponds under the action of climate, vegetation and groundwater, this paper consider the rainfall-evaporation-transpiration and coupling effect of groundwater, establish the model of different dam height, slope ratio, permeability coefficient and migration time impact on the migration of heavy metals of tailings dam, applied to Geostudio software, based on the orthogonal design method of factors significant difference analysis and design method of the comprehensive factors analysis, make up the simulation of the tailings heavy metal pollutants concentration of Cu2+ migration law. The results show that the height of tailing dam is inversely proportional to the average migration velocity of pollutant Cu2+. The effect of slope ratio on migration concentration of Cu2+ pollutant in tailings pond is not significant. The permeability coefficient has a highly significant influence on the migration of heavy metal Cu2+. At the same depth of tailings pond, when Cu2+ migrated for 365 days, the permeability coefficient increased with the increase of pollutant Cu2+ concentration. The concentration of heavy metal increased with the increase of migration time.
Study on the Effect of Chemical Conditioning on the Consolidation Characteristics of Municipal Sludge in Landfill Depot
Authors: Zhan Xinjie , Li Wenwei , Xu Xiaolong , Zhu Qunfeng 
Published: March 2021

Abstract
Vacuum preloading is one of the effective methods for in-situ dewatering and reduction treatment of municipal sludge landfill, but because the consolidation coefficient of municipal sludge is 1 or 2 orders of magnitude smaller than that of sludge, the drainage consolidation technology will face the problem of vacuum for too long. In order to improve the consolidation characteristics of sludge, combined with the chemical conditioning technology in the field of water treatment, firstly, the chemical conditioner suitable for landfill sludge was selected. The effects of different conditioning combinations on sludge dewatering characteristics were studied by microscopic testing techniques (zeta potential analysis and environmental scanning electron microscope analysis) and vacuum filtration test and consolidation test. The results show that the combination of ferric chloride and calcium oxide can significantly improve the dewatering characteristics of sludge. After conditioning with 10% ferric chloride and 10% calcium oxide (relative to sludge dry base), the specific resistance of sludge is reduced from 2 × 1013m/kg to 3 × 1012m / kg, and the consolidation coefficient is 3.5-10 times higher than that of original sludge, which lays a foundation for improving the efficiency of vacuum preloading treatment. In addition, from the results of vacuum filtration test and consolidation test of sludge, it can be found that there is a good negative linear relationship between specific resistance and consolidation coefficient of sludge. Compared with the consolidation test, the vacuum filtration test is simple and easy, so it can be used as an effective means to select sludge conditioner or test the conditioning effect.
Assessment of Heavy Metals in Sediments of Different Functional Areas along the Yangzong Lake Coast, Yunnan Province
Authors: Li Yanli , Fan Fu , Li Jin , Ying Xi 
Published: March 2021

Abstract
Contents of Cu, Zn, Ni, Cr, Fe, Mn, V, Mo, Co, Sr, Li, Be, Cd, As, Pb, Al, Ba and Ti in 40 coast sediment samples collected from the industrial, tourism and agriculture area adjacent to Yangzong Lake Coast were analyzed. Enrichment coefficient method and potential ecological risk index method have been adopted to evaluate heavy metal pollution and ecological risk. The results showed that pollution degree of Cu, Zn, Ni, Cr, Mn, Co, V from high to low was as follows: agriculture area > tourism area > industrial area. The enrichment performance of Be, As, Cd, Al, Ti, Li, Fe from high to low was as follows: agriculture area>industrial area>tourism area. The pollution degree of Mo, Pb, Sr from high to low was as follows: industrial area > tourism area > agriculture area. The pollution degree of Ba from high to low was as follows: tourism area > industrial area > agriculture area. According to the potential ecological risk coefficients, Cd, As, Cu, Co were the most hazardous elements in industrial area, tourism area and agriculture area. The request potential ecological risk index indicated that industrial area and tourism area were low-moderate potentical ecological risk, agriculture area was moderate-considerable potentical ecological risk.
Temporal and Spatial Distribution Characteristics of Precipitation over Guangzhou, China
Authors: Chen Guangxin , Chen Kui , Yang Kai , Guo Qinghao 
Published: March 2021

Abstract
The current study probed the spatial distribution and temporal variation of precipitation extremes over the Pearl River Delta region (PRD) depended on meteorological observation data for 1960-2019. The daily precipitation for the major 7 synoptic stations in the Guangdong province of China was analyzed. It is found that the spatiotemporal heterogeneity were the distribution characteristics of PRD precipitation. In terms of spatial distribution, more precipitation value in the eastern coastal areas of Guangdong province. In general, the average annual precipitation presented an increasing trend form 1960 to 2019. At the same time, the probability and intensity of extreme precipitation with increasing tendency were analyzed in this time period. It was indicated the continuing situation of climate fluctuation that adjusted the precipitation regime of Guangzhou. Summer became the season with the largest number of statistically significant trends of extreme precipitation, mostly increasing ones.
Study on the Construction of Water Environment Promotion Joint Control and Joint Regulation System in Plain River Network Area
Authors: Xie Chen , Pan Xiaobao , Ding Rui , Liu Guoqing , Liu Yang 
Published: March 2021

Abstract
There are many river networks in Southeast plain cities of China, such as dense river network, many water projects, poor connectivity, strong pollution load into the river, and difficulty in regulation and control. The water environment problem of river network has become the bottleneck restricting the sustainable economic and social development of plain river network area. In order to improve the river water environment, it is very important to carry out reasonable intelligent regulation of regional river system. In view of the current situation that the water environment regulation is mainly based on manual operation and has not formed intelligent dispatching decision-making, this paper integrates the technology of water power and water quality joint control of urban river network, researches and develops the joint control and joint dispatching system of water environment improvement in plain river network area, and establishes a full coverage, full element three-dimensional monitoring and warning, dispatching and intelligent decision-making system, driven by monitoring data, with model as the core and remote control as the core with the goal of hydrodynamic, water level and water quality as the target, relying on the model cloud, the intelligent one click precise scheduling is realized.
Effect of Vegetation on the Flow of a Partially-Vegetated Channel
Authors: Tang Xiaonan , Guan Yutong , Zhang Yujia , Zhang Wenxuan , Jiang Yanzhen , Liu Tong , Yi Xintong 
Published: March 2021

Abstract
A vegetated channel commonly exists in the natural environment. Over recent decades, many researchers have taken an interest in this field. The hydraulic characteristics of flow over vegetated channels are complex. Vegetation significantly affects the flow resistance and turbulence, resulting in sediments, nutrients, and contaminants transportation. Thus, understanding the impact of vegetation on flow structures is important for river and environment management. However, most attention on vegetated channel flow focuses on single-layered vegetated channels. There are few studies on the impact of double-layered, partially placed vegetation on open channel flow. To fill this research gap, this paper aims to investigate the impact of vegetation on the flow velocity of a double-layered, partially placed vegetated channel.
Experimental Study of Smooth Asymmetric Compound Channels Flow: An Investigation of the Interaction of Flow Using Scaling Argument for Prediction of Overall Discharge
Authors: Singh P , Tang X , Guan Y 
Published: March 2021

Abstract
A simple model for the apparent shear stress on the vertical interface between the floodplain and main channel in asymmetric smooth compound channels is proposed using experimental data obtained in this study. The turbulent structure, including Reynolds shear stress in asymmetric compound channel flows, is investigated for three different flow depths. The lateral distribution of the apparent shear stress obtained shows that the total apparent shear stress has a negative peak near the junction edge in the main channel. Furthermore, the intensity of the advection terms and the Reynold shear stress near the interface are investigated as the function of the bankfull height and floodplain width. The momentum transport due to Reynolds stress and secondary current between main channel and floodplain is finally modeled as depth ratio using scaling argument. The validation of the current model on three datasets shows an accurate prediction of overall discharge for the asymmetric smooth compound channels.