bluuebunny/crossref_metadata_2025_split huggingface dataset:
Camera traps show foxes are the major predator of flatback turtle nests at the most important mainland western Australian rookery
Authors: King J. , Whiting S. D. , Adams P. J. , Bateman P. W. , Fleming P. A. 
Published: July 2023

Context Quantifying marine turtle-nest depredation by daily observer monitoring requires substantial labour. Aims To quantify nest depredation of the Vulnerable flatback turtle (Natator depressus) at one of its largest rookeries and to compare effectiveness of different monitoring methods. Methods We used daily observer monitoring and passive infrared-camera traps separately or in combination to record nest depredation, and identified impacts on remaining eggs and hatchlings in depredated nests. Key results More than a quarter (28%) of the 69 monitored nests were confirmed as depredated, although this figure is an underestimate of total losses because camera traps detected twice as many depredation events (39%) as did direct observation (17%) (P = 0.012). Cameras also provided important behavioural data and identified predators. Although reptile and bird predators were also recorded, the introduced red fox (Vulpes vulpes) was the primary predator identified, digging into 26% of the monitored nests. More than half of the depredation events by foxes (58% or 11/19 nests) occurred late term, between turtles hatching and emerging from the nest, which therefore means that losses calculated through counts of eggshell left in the nest are underestimates because predation of hatchlings is not included by the eggshell count method. Furthermore, almost half (42%) of all depredated nests were depredated more than once, with some nests opened up to five times, potentially exacerbating clutch losses due to environmental exposure. Conclusions Egg losses for confirmed depredated nests (27 ± 37%, range 0–100%) were three times the background levels (i.e. 9.3% of eggs that failed to hatch as a result of embryo death during development). Implications The results of this study strongly warrant the implementation of ongoing fox predator monitoring and mitigation strategies to protect nests at this nationally, and internationally, conservation-significant population of flatback turtles.
Match-reinforcement learning with time frequency selection for bearing fault diagnosis
Authors: Wang Jiaxuan , Gao Dawei , Zhu Yongsheng , Ren Zhijun , Zhao Rongzhen , Lin Tantao , Yan Ke , Hong Jun 
Published: July 2023

Abstract
Rolling bearings play a vital role in ensuring the safe operation of rotating machinery. However, in many application scenarios, the collected data has a low signal-to-noise ratio and the samples with faults are rare, which affects the generalization capability of the model, making it impossible to achieve accurate diagnosis. To solve this problem, the selection of time-frequency (TF) maps was considered in this paper through reinforcement learning. The TF maps are built by four classical TF characterization methods such as short-time Fourier transform and synchro squeezing transform. And the match-reinforcement learning time frequency selection (MRLTFS) fault diagnosis model is proposed to extract the fault-related features. Experiments show that the proposed MRLTFS method is superior to existing methods in robustness, generalization and feature selection capability.
CT-CBCT deformable registration using weakly-supervised artifact-suppression transfer learning network
Authors: Tian Dingshu , Sun Guangyao , Zheng Huaqing , Yu Shengpeng , Jiang Jieqiong 
Published: July 2023

Abstract

Objective. Computed tomography-cone-beam computed tomography (CT-CBCT) deformable registration has great potential in adaptive radiotherapy. It plays an important role in tumor tracking, secondary planning, accurate irradiation, and the protection of at-risk organs. Neural networks have been improving CT-CBCT deformable registration, and almost all registration algorithms based on neural networks rely on the gray values of both CT and CBCT. The gray value is a key factor in the loss function, parameter training, and final efficacy of the registration. Unfortunately, the scattering artifacts in CBCT affect the gray values of different pixels inconsistently. Therefore, the direct registration of the original CT-CBCT introduces artifact superposition loss. Approach. In this study, a histogram analysis method for the gray values was used. Based on an analysis of the gray value distribution characteristics of different regions in CT and CBCT, the degree of superposition of the artifact in the region of disinterest was found to be much higher than that in the region of interest. Moreover, the former was the main reason for artifact superposition loss. Consequently, a new weakly supervised two-stage transfer-learning network based on artifact suppression was proposed. The first stage was a pre-training network designed to suppress artifacts contained in the region of disinterest. The second stage was a convolutional neural network that registered the suppressed CBCT and CT. Main Results. Through a comparative test of the thoracic CT-CBCT deformable registration, whose data were collected from the Elekta XVI system, the rationality and accuracy after artifact suppression were confirmed to be significantly improved compared with the other algorithms without artifact suppression. Significance. This study proposed and verified a new deformable registration method with multi-stage neural networks, which can effectively suppress artifacts and further improve registration by incorporating a pre-training technique and an attention mechanism.
Primordial black hole production in natural and hilltop inflation
Authors: Cook Jessica L. 
Published: July 2023

Abstract
We consider the possibility of primordial black hole, PBH, formation sourced by a rise in the power spectrum. The power spectrum becomes large at late times due to decay of the inflaton into vectors through a ϕFF̃ coupling. Two background inflaton models which are well supported by current Planck data are considered, natural inflation and hilltop inflation. Many of the papers considering formation of PBHs have considered a peaked power spectrum where Pζ
gets small again at late times. This avoids overproducing miniature PBHs which would evaporate and could violate BBN and CMB bounds. This paper examines the other way of avoiding these bounds, producing PBHs from perturbations formed closer to the end of inflation such that the PBHs are too small to violate these bounds. This has the advantage of allowing for simpler models in that no additional feature is needed to be added to evade constraints. Although these black holes would have evaporated, they can be close to without exceeding current BBN bounds, making it possible the signature will be revealed in the future. We calculate how the various model parameters affect the mass and number of PBHs produced. Any evidence for PBHs sourced from an inflationary power spectrum would provide evidence for inflation on a drastically different energy scale from the CMB, and thus would be highly valuable in answering what occurred during inflation.
Influence of geometric nonlinearity on static and dynamic response of flexible beam
Authors: Peng Quancheng , Ji Yujie , Li Jinquan 
Published: July 2023

Abstract
The flexible beam theory is widely applied in engineering, due to that many engineering structures can be regarded as flexible beam. For the flexible beam under large rotation, researches have shown that consideration of geometric nonlinearity is necessary: beam deflection will be erroneously larger or diverge without consideration of geometric nonlinearity. The reason lies on the dynamic stiffening effect caused by geometric nonlinearity. The dynamic stiffening effect of flexible beam under large rotation is well studied already, however, most studies only focus on flexible beam with constant cross section and rarely considers flexible beam without rotation. In view of this, a flexible beam with variable and twisted cross section is adopted to analyze the influence of geometric nonlinearity, and the response of flexible beam without rotation or static response is also analyzed. The results of dynamic beam deflection with and without consideration of geometric nonlinearity is compared, the results of static beam deflection under different load is also compared. On the basis of result comparison, the influence of geometric nonlinearity on static and dynamic response of flexible beam is then explained.
The Research on Performance Characteristics of the Sliding Relief Valve
Authors: Wang Lipeng , Hou Dingqi , Li Guanghui , Ma Xiaochen , Wei Guanju , Han Xinmiao , Zhao Jun , Qiao Jing 
Published: July 2023

Abstract
Based on the software AMESim, this paper introduced the operating principle and established the system models of relief valves. The effects on dynamic characteristics under the different parameters, including the number of overflow orifices, overflow orifice diameter and spring stiffness, were analyzed by the AMESim batch processing method. This paper compared and analyzed the curves and summarized the parameters which affect the performance characteristics of the relief valves. The result helps optimize the structure parameters and improve the performance characteristics of the relief valves.
Research and Application of Support in Triangle Area of Underground Withdrawal Working Face in Coal Mine
Authors: Xie Xuebin 
Published: July 2023

Abstract
Aiming at the rapid withdrawal of temporary support technology at the fully mechanized mining face in the Shendong mining area, a temporary support bracket group in the triangle area is designed according to the current geological mining conditions, and the working principle of the temporary support bracket in the triangle area is explained and analyzed. The key technical parameters of the triangular support are analyzed, and the stress of its key structure is analyzed. Field practice shows that the developed triangular area temporary support bracket group has a reasonable structural design, improves the withdrawal efficiency based on effective roof support, and meets the requirements for the use of temporary support for rapid withdrawal of fully mechanized mining faces.
Effect of different roughness on oil film formation in a diesel engine
Authors: Wu Beibei , Xu Zengtian , Feng Shiquan , Li Changqing , Yao Jia 
Published: July 2023

Abstract
After diesel fuel injection, when the spray droplets in the air hit the wall, an oil film may be formed on the wall, and the surface roughness is the key parameter. To analyze the influence of roughness on the formation of oil film, a combustion model of the engine cylinder is built in this paper. The main part of the model is the simulation of diesel injection, and a related fuel injection model is built. The influence of cylinder wall roughness on the oil film formation in the diesel engine cylinder is analyzed through a wall-droplet interaction model.
A new method for the single mesh stiffness calculation of helical gear considering slice coupling effect
Authors: Yan Hai , Wen Lihua , Yin Shaoping , Jiang Tonglei , Wang Bo 
Published: July 2023

Abstract
In this paper, a new method is proposed, calculating the single mesh stiffness by cobining the silce principle and contact line analysis. Firstly, this method obtains the length of the contact line of the helical gear through contact line analysis. Secondly, along the tooth face width, the teeth of helical gear is separated into a series of equivalent thin teeth of spur gear. Thirdly, in order to consider the slice coupling effect, a weighting factor is introduced to modify the stiffness of the thin tooth itself according to the contribution of the thin tooth to the overall stiffness, which is distributed in parabola. Finally, by integrating the equivalent thin teeth of the spur gear along the contact line, the single mesh stiffness is calculated. The investigation shows that the influence of the slice coupling effect on single meshing stiffness related to the relationship between the value of transverse contact ratio and overlap ratio. When transverse contact ratio is greater, the influence of the slice coupling effect on the single mesh stiffness is very small an can be ignored, and when the overlap ratio is larger, which is significant.
Study on Adaptive Sliding Mode Fault-tolerant Control of 1/4 Vehicle Electromagnetic Suspension
Authors: Kou Farong , Chen ChenRuo , Xiao Wei , Hu Kailun 
Published: July 2023

Abstract
An adaptive sliding mode fault-tolerant manage approach is proposed to remedy the trouble of actuator acquire failure of the electromagnetic hybrid energetic suspension device and the hassle of automobile manipulate balance degradation induced by using the nonlinear pressure of spring and damper. The failure thing is chosen to symbolize the actuator fault size, and the actuator fault parameter mannequin is established. Combining sliding mode manipulate with adaptive control, an adaptive sliding mode fault-tolerant controller for lively suspension primarily based on an correct mannequin is designed. Based on the Lyapunov balance theory, the steadiness of the machine is proved; and the Gravity search algorithm (GSA) and linear matrix inequality (LMIS) are used to optimize the sliding floor parameters, and the most beneficial answer is chosen in accordance to the health function. The simulation effects exhibit that in contrast with passive suspension, the root capability rectangular values of sprung mass acceleration, suspension dynamic deflection, and tire dynamic load underneath adaptive sliding mode fault-tolerant manipulate approach decrease by way of 41.7%, 38.4%, and 36.5% respectively. It suggests that the designed adaptive sliding mode fault-tolerant controller is right and can enhance car experience comfort.
Damage Rule of Marine Isolator under Secondary Shock Vibration
Authors: Ma Chuanlin , Lu Xudong , Lu Xi , Yin Fengjun 
Published: July 2023

Abstract
To study the damage of the shock vibration generated by the ship hull to the internal equipment of the ship under the secondary explosion impact, a three-dimensional simulation model of the BE rubber isolator was established. The signal of the impact vibration load was loaded by the AUTODYN software. And the relationship between the damage of the isolator under the primary vibration impact and the frequency, amplitude, and attenuation of the loading signal was found. It is revealed that the damage law curve of the isolator under the secondary shock vibration conforms to a rational function. Based on this discovery, a mathematical model of the secondary shock vibration signal that can predict the isolator damage through the primary shock vibration is established.
Research on Key Point Detection Method of Mechanical Arm
Authors: Fu Xin , Han Le , Tian Songpo , Shen Zhonghong 
Published: July 2023

Abstract
Accurate keypoint localization is an important research direction in the field of robotic arms. Deep learning is being used more and more for motion capture and pose estimation. This is due to their ability to detect user-defined key points without the use of labels. We present an approach for detecting robot 3D key points coordinate based on two perspectives. Two images of different perspectives are processed by the same deep neural network to detect 2D projections of key points (such as joints) associated with the robot. Triangularization is then applied to recover 3D coordinates. In addition, the existing dataset of robot critical points is obtained by simulation. It seriously impedes the advancement of this field. We establish an actual robot key points dataset and corresponding evaluation criterion. The experimental results demonstrate that our framework achieves cutting-edge detection performance. It is reusable for other robot models.
The Fuel-efficient Vehicle Frame for Energy Saving Competition Design and Analysis Based on ABAQUS
Authors: Mao Yuhao , Liu Chunyu , Fei Yeqi , Ma Zhuqiao 
Published: July 2023

Abstract
Non-load-bearing body, with an independent frame, is subject to gravity load provided by itself and load-bearing components, and also subject to excitation load from the road and engine, etc. Therefore, the rigidity and strength of the frame must be ensured in the frame design, so the welding strength in the frame fabrication process is extremely important. In this paper, the basic characteristics of the frame are analyzed by using finite element technology, and the welding displacement, stress, and strain of the frame are studied in detail. The main research contents are as follows:
The thesis takes the frame of energy-saving racing car as the research object. According to the design requirements of the official committee, firstly, the 3D model software is used to design the geometric model of the racing car and rationalize the spatial layout of the frame. Secondly, the finite element model of the frame of the energy-saving racing car is established by Abaqus software, and through the process of parameter sett and load application, the stress, deformation, and modal performance of the frame under each working condition are derived. Finally, the structural parameters of the frame are compared to see whether the safety factor is achieved, so as to conclude whether the frame is qualified and whether it meets the lightweight design requirements of the racing car.
Study on Fracture Mechanism of Low-Pressure Blades of Steam Turbines in Power Plants
Authors: Li Yanping , Zhang Yaoyao , Cui Xinyi 
Published: July 2023

Abstract
With the continuous improvement of steam turbine design technology and production level, steam turbine blade fracture accidents have dropped significantly, and blade fracture accidents are no longer the main reason for the forced shutdown of thermal power generation units. Due to the bad working conditions of turbine blades, blade designers still need help to accurately analyze their dynamic stress and evaluate their high cycle fatigue life. Up to now, blade fracture accidents still occur frequently. In this paper, a comprehensive analysis is made of the causes of the fracture of the low-pressure 16th stage blade of a 25 MW steam turbine in a thermal power plant. The fracture property of turbine moving blades is that small corrosion pits are formed first, and then the fatigue propagation fracture occurs. The main cause of corrosion is poor steam quality.
Diagnostic Analysis Method of Direct Air Cooling Unit Limited Output Based on Pressure Ratio
Authors: Zhang Deli , Wang Na , Pang Chunfeng 
Published: July 2023

Abstract
Given the limited output of a 600MW direct air cooling steam turbine unit, through the thermal performance test, historical operation data extraction, and comparative analysis combined with the data after the latest overhaul, it is found that the extraction pressure of the first section of the high-pressure cylinder began to appear over-pressure in recent two years. After further calculating the pressure ratio of the HP cylinder flow passage stage group, it is found that the pressure ratio of HP cylinder exhaust steam to Section I extraction steam has increased by nearly 4% in the last two years, indicating that the area of flow passage part of this stage group has become smaller and serious salt deposition has occurred, resulting in the reduction of HP cylinder flow passage capacity and the ultimate limitation of the output of the whole unit. The cylinder uncovering inspection results verify the correctness of the diagnosis. The diagnosis method is simple and suitable for the fault diagnosis of the actual flow passage.
The level measuring method of machine tool flatness and its data processing of three far point method and least square method
Authors: Zhu Weiwei , Dong Chenchen , Wei Jinling 
Published: July 2023

Abstract
The flatness error of the machine tool worktable is an important index to evaluate the worktable. The measurement process of flatness error is complex, and data processing is difficult. Aiming at the indirect method of flatness using the level, this paper introduces in detail the grid method path planning method, the original data recording method, the calculation method of local data conversion, and the calculation method of global coordinate sorting, conversion, and verification. On this basis, the three distant point method and the least square method are used to process the original data respectively, and the least square method is solved by MATLAB to obtain the flatness error. Through the example of flatness measurement of rectangular worktable of machining center, the path planning method, original data processing, three far point method, and least square method are further introduced. The research of this paper standardizes the flatness measurement method and data processing method of the level in detail, which can improve detection efficiency and data accuracy.
Design and Simulation Analysis of Large-Angle Simulation Turntable
Authors: Jing Manjun , Ma Jun , He Pin , Lu Jinjin , Fan Zhuo , Mao Hongyong 
Published: July 2023

Abstract
Three-dimensional solid modeling and structural design of the large-angle simulation turntable were carried out by three-dimensional software, and the assembly of the simulation turntable was realized. Simultaneously, the dynamics simulation of the simulation turntable was carried out to obtain the angular velocity, angular acceleration and torque curve of the simulated turntable under the given motion curve. Considering the influence of the tested equipment on the simulation turntable, the vibration simulation analysis of the simulation turntable was carried out by finite element software, and the modal analysis and harmonic response analysis obtained the vibration characteristics of the simulation turntable. The results show that the structural design of the large-angle simulation turntable meets the design requirements.
Identification of Exoskeleton Dynamics Parameters and Control Based on Series Elastic Actuator
Authors: Zhao Jiawei , Zhu Lizhong 
Published: July 2023

Abstract
The lower limb exoskeleton is used for rehabilitation, assistance and maturing. Taking an exoskeleton based on a serial elastic actuator as an object, a method of dynamic parameter identification is proposed. Firstly, the modular SEA structure is introduced, and the exoskeleton is modeled by using the Modified Denavit-Hartenberg (MDH) method. Then, the exoskeleton dynamic model is derived and linearized. Secondly, the excitation trajectory required for exoskeleton parameter identification is designed, which is optimized by using the genetic algorithm. Then, the exoskeleton is tested by using the excitation trajectory to decouple the dynamic parameters. Finally, the exoskeleton impedance control algorithm based on dynamic compensation is designed and compared with the algorithm without dynamic compensation. The results show that the parameters obtained from the identification algorithm and the control algorithm are effective.
Characterizing a Ka-Band FMCW Reflectometer
Authors: Buch J.J.U. , Pathak S.K. 
Published: July 2023

Abstract
A Ka-Band ultra-fast, ultra-wide band Frequency Modulated Continuous Wave (FMCW) reflectometer to measure the plasma density profile has been designed and developed at Institute for Plasma Research (IPR). We present here the need for ultra-fast and ultra-wide frequency of operation and estimate expected beat frequencies for the instrument. Three distinct corrections are made to the obtained frequencies. Firstly, inherent non-linearity of the frequency source is removed by shifting non-linearity to the tuning voltage of the hyper-abrupt varactor tuned oscillator and then correcting mismatch of the absolute values of frequency by introducing a delay line to account for the
difference in length between active and reference paths
for producing the beat frequencies. Using code developed based on the short time Fourier transform we extract the beat frequency to measure various known distances and verify with our beat frequency estimations and also show that range resolution obtained is very close to the theoretical one obtained.