bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role model of model-based systems engineering application
Authors: Gräßler Iris , Wiechel Dominik , Pottebaum Jens 
Published: March 2021

Abstract
The transition to model-based systems engineering (MBSE) is essential to meet the demands of increasing system complexity, productivity, quality and shorter design cycles. Necessary perspectives, associated roles and competencies for the application of MBSE are not sufficiently defined. The paper at hand presents a role model for the practical application of MBSE based on three major steps: (1) identification, (2) categorization and (3) association of stakeholders, which implement and apply MBSE within an enterprise. The use of the role model is demonstrated and evaluated in a test case based on personas within a fictional scenario which illustrates the implementation of MBSE. The roles, which are adapted to today’s conditions, serve as a practical guide comprising all basic conditions that have to be considered when applying MBSE. Practitioners can easily tailor the illustrated results to their own use case.
Investigations on the Micro-Pitting and Wear Behavior of Nitrided Internal Gears
Authors: Geitner M , Zornek B , Hoja S , Tobie T , Stahl K 
Published: March 2021

Abstract
Nitriding processes can significantly increase the load carrying capacity of gears, compared e.g. to through hardened gears. Nitrided gears are generally characterized by a thin and hard compound layer on the surface and an adjacent diffusion layer that extends deeper into the material. Structure and properties of the compound layer significantly determine especially the tribologically dominated load carrying capacity characteristics of the tooth flank surface such as micro-pitting and wear. Previous investigations on nitrided gears were mainly focused on fatigue limits for the surface durability against pitting and tooth root bending strength. Furthermore, mostly external nitrided gears were investigated. Results of systematic investigations on the wear and micro-pitting behavior of nitrided internal gears are scarcely available. Based on the investigations in the research project FVA 482 IV, experimental test results confirm that nitrided internal gears in the material pairing “case hardened/nitrided” provide a significantly better performance regarding wear compared to through hardened or case hardened internal gears. Furthermore, it was shown that nitriding can have a positive influence on the micro-pitting behavior. A detailed analysis of the microstructure shows that the properties of the compound layer are primarily responsible for both, the micro-pitting and wear behavior.
Investigations on the rolling bearing cage dynamics with regard to different operating conditions and cage properties
Authors: Schwarz S. , Grillenberger H. , Tremmel S. , Wartzack S. 
Published: March 2021

Abstract
The dynamic behavior of a cage can have a significant influence on the performance and the noise of a rolling bearing. In case of an unstable or high-frequency cage movement, vibrations are transmitted to the adjacent machine elements and the environment, which can influence the operating behavior of the whole system. In addition, a loud noise can often be perceived, which is referred to in the literature as cage rattling or squealing. In this paper, characteristics of different cage movements are investigated using multibody simulations and experimental investigations. For this purpose, essential properties of the fundamentally observable cage movement types “stable”, “unstable” and “circling” are presented. The calculated cage dynamics and the type of cage motion are used to show dependencies between the operating conditions and the resulting cage movement such as inner ring rotational speed, bearing load or cage characteristics such as pocket clearance. Based on the simulations, interactions between the input parameters can also be determined. The results are used to identify operation-critical conditions and cage properties that lead to high cage dynamics. Finally, a comparison between the results of the multibody calculations and optical measurements is made. The optical measurements are performed using high-speed cameras. Reference markers fixed on the cage and digital image correlation allow the evaluation of the kinematics as well as the deformation of the cage. These results are compared with the simulation data to ensure a high quality of dynamics simulation.
Damage Diagnosis of Cardan Shafts in Mobile Mining Machines using Vibration Analysis
Authors: Golafshan Reza , Dascaliuc Catalin , Jacobs Georg , Roth David , Berroth Joerg , Neumann Stephan 
Published: March 2021

Abstract
The ability of prediction of machine condition may become even more crucial in mobile mining machines considering their instantly-varying conditions. The field of early damage diagnosis for mobile machinery is gaining increasing attention in modern and predictive maintenance strategies. In general, vibration-based machine condition monitoring methods offer the possibility to detect and localize the damages in mechanical systems at their early stages. In vibration monitoring, the vibration signals are captured via accelerometers, and are processed in the time and frequency domains in signal processing packages to extract diagnostic information. However, in real-world mobile applications, vibration analysis alone may not reveal the diagnostic information due to extreme transient and nonstationary operating conditions. In this regard, additional metadata available on the machine’s CAN bus system, can improve the reliability of vibration analysis for mobile applications. The current study aims to investigate the usage of metadata as additional information to the vibration analysis on cardan shaft of a test wheel loader in field conditions. Two various damage types, namely, misalignment and bearing clearance, both on cardan shaft, are investigated in some detail. The experimental results show how vibration analysis together with metadata processing can identify the state of the machine even in harsh operating conditions.
Design and manufacturing of a cylinder head by laser powder bed fusion
Authors: Willkomm J , Kuhlbach K , Merget D , Wagner M , Reich S , Ziegler S , Schleifenbaum J H 
Published: March 2021

Abstract
Nowadays the reduction of fuel consumption is the most important challenge for engine development. Laser Powder Bed Fusion (LPBF) as an additive manufacturing process with its implied design freedom makes it possible to reduce combustion emissions, increase engine efficiency and respond specifically to customer requirements. In this work, the outstanding degree of freedom of LPBF is exploited for a new design concept for a cylinder head of an engine in automotive industry in order to address further reduction of fuel consumption through improved cooling performance. Within the given installation space and under consideration of the existing mounting and connection positions, the design concept was developed, subsequently manufactured and reworked. In order to develop a design that meets the LPBF requirements, both the potential of the LPBF using the geometric degrees of freedom as effectively as possible and the limitations are considered. The opposing design drivers between exploitation of potentials and limitations in LPBF are achieved by an iterative design process supported by an own developed design tool. With the new design concept, a reduction of the metal temperature in the cylinder head of approx. 25 K is achieved, verified by simulation.
Influence of Basic Airfoil Layout on Aerodynamic Characteristics of Forward-swept Wing
Authors: Jun-yi Zhang , Xin-bing Su , Wen Jiang , Xi-wei Zhao 
Published: March 2021

Abstract
When the swept angle of the wing varies, the parameters such as the aspect ratio of the forward-swept wing aircraft and the relative speed of the cross-section airfoil relative to the incoming flow will change, which will play a great influence on the aerodynamic characteristics of the wing. Based on this purpose, this paper explores the impact of the oblique angle of the basic airfoil on the aerodynamic performances of the forward-swept wing. Firstly, the wing models of the upright and oblique basic airfoil were established, meanwhile the one-equation Spalart-Allmaras turbulence model and CFD technique were used for numerical simulation calculation. The change law of the aerodynamic characteristics of the wing with the fundamental airfoil upright and tilted are compared and analyzed when the swept angle varies.
Utilization of Low-Potential Energy Through to the Use in Aircraft Fuel System
Authors: Badykov Renat R. , Panshin Roman A. , Tremkina Olga V. , Prokofieva Anastasia A. 
Published: March 2021

Abstract
The article discusses the possibility of improving the main characteristics (efficiency, specific thrust) of a gas turbine engine by using liquefied natural gas (LNG) as fuel. This possibility is considered on the example of using as fuel instead of aviation kerosene on PS-90A and NK-93 engines. The parameters of the engine were determined at various stages in the cruise flight mode when operating on kerosene and LNG. The parameters evaluating the fuel consumption of the engine are calculated and compared for both fuels. The performance characteristics for kerosene and LNG were evaluated in the system of the Tu-330 subsonic transport aircraft. Energy losses during storage of cryogenic fuel on board the aircraft are estimated.
Analysis of Sound Insulation Mechanism and Optimization Design of an Acoustic Coating Layer with Multi-section Cylindrical Cavities
Authors: Zhou J L , Meng X J , Huang Fu H D , Zhang J H , Su K , Tao W , Chen H Y 
Published: March 2021

Abstract
Introducing the insulation layer is an effective way to reduce sound radiation from underwater structures. Impedance mismatch properties between water and layer is closely related to sound insulation performance. Finite element method with COMSOL is used to calculate sound insulation loss in this paper. In order to investigate the insulation mechanisms of coating layer embedded with multi-section cylindrical cavities, the coating layer is approximated to a homogeneous layer with equivalent material properties. The results show that acoustic coating layer with multi-section cylindrical cavities, which causes a higher impendence mismatch has a better sound insulation performance than cylindrical cavity acoustic coating layer of the same cavity volume. The coating layer with optimized multi-section cylindrical cavities structure has obvious sound insulation advantages in the range of 200Hz to 4000Hz. Finally the theoretical analysis is verified by experiments.
Dynamic Modelling and Pendulation Laws of Cable Hoisting System
Authors: Tian Z X , Lin X X , Li J P , Hu P 
Published: March 2021

Abstract
The dynamic characteristics of the cable hoisting system (CHS) are studied by combining theoretical modelling and visual simulation. The dynamic model is derived using D’Alembert’s principle. It contains the effect of horizontal motion and lifting motion, and also takes into account the quality of the cable to improve the accuracy of model. The Runge-Kutta method is used to solve model numerically, and simulation is conducted within Adams environment to verify the dynamic model. Based on the dynamic model and numerical calculation, the effect of horizontal motion, lifting motion and system parameters on swing was studied. The results show that the dynamic model and numerical calculations are accurate; during the movement, the payload oscillation is mainly affected by the initial acceleration, sudden change of acceleration and lifting speed; the length of steel cable and the mass of hoisting payload determine the frequency of CHS, which does not affect the payload oscillation; the oscillation and frequency are affected by lifting laws; and the study of acceleration laws can be used to guide the design and control of CHS.
Application of Closed Magnetic Circuit Method for Evaluating the Stress Distribution along Depth Direction
Authors: Di Jingyu , He Cunfu , Liu Xiucheng , Lee Yung-Chun 
Published: March 2021

Abstract
Electromagnetic nondestructive evaluation method is feasible in assessing stress or residual stress levels in ferromagnetic structures, for there is a strong inherent correlation between the permeability and the stress. This study is based on the closed magnetic circuit method for testing stress distribution along depth. Firstly, a theory is proposed for describing the propagation of electromagnetic energy inside ferromagnetic materials. A layered model is established considering the electromagnetic field experienced different attenuation at different depths. And each layer is assumed to have the identical physical state. Then, multi-frequency eddy current method is proposed to testing the in-depth permeability variation and consequently the stress-depth profile. For simply using the convolution integral, a novel inversion algorithm is given to resolve the convolution integral. To apply the proposed method for testing the stress-depth profile, multi-frequency eddy current experiments are conducted through a four-point bending device; with the specimen material employed is 45# steel. Finally, map the experimental data fitting curve to the theoretical calculation curve, and hence can verify the proposed theory and the inversion algorithm.
Effects of Misalignment on the Sliding Rates of Parallel Line Gear Pair
Authors: Lin Yifan , Chen Yangzhi 
Published: March 2021

Abstract
The sliding rates of parallel line gear pair (PLGP) are equal to zero and pure rolling meshing can be achieved under ideal condition. In this paper, effects of misalignment on the sliding rates of PLGP were studied. Firstly, the geometric model of PLGP was presented. Then the contact curves of PLGP with misalignment were obtained by the tooth contact analysis (TCA) method and the sliding rates were calculated. The calculation results of the example show that PLGP under ideal condition or with only axial deviation accomplishes transmission along the theoretical contact curves, the sliding rates are equal to zero, and pure rolling meshing can be achieved. For PLGP with centre distance deviation and parallelism misalignment, the sliding rates are not equal to zero and the form of relative motion between the meshing surfaces combines rolling and sliding. This investigation provides a theoretical basis for the further study of meshing efficiency and wear prediction of line gear pair under actual operating condition.
Bolt Load Calculation for Hybrid Joint Considering Friction and Nonlinear Stiffness under Combined Thermal and Mechanical Loads
Authors: He Tiren , Xu Jifeng , Zhu Kaige , Wang Haijun 
Published: March 2021

Abstract
An improved analytical method for calculating the bolt load distribution in single-lap or double-lap multi-bolt composite-metal joint structure considering material nonlinear behaviour and thermal stress is proposed in this paper. The analytical method is based on the stiffness method and the composite material mechanics. The bolt load ratios calculation results of a three-bolt joint structures by the improved method is compared with the results from finite element (FE) method and the relative error less than 7%. The great agreement verifies the accuracy of the analytical method. Besides, this improved has more considering factors and higher accuracy than traditional stiffness method and less calculating cost than FE method.
Engineering bioinks for 3D bioprinting
Authors: Decante Guy , Costa João B , Silva-Correia Joana , Collins Maurice N , Reis Rui L , Oliveira J Miguel 
Published: March 2021

Abstract
In recent years, three-dimensional (3D) bioprinting has attracted wide research interest in biomedical engineering and clinical applications. This technology allows for unparalleled architecture control, adaptability and repeatability that can overcome the limits of conventional biofabrication techniques. Along with the emergence of a variety of 3D bioprinting methods, bioinks have also come a long way. From their first developments to support bioprinting requirements, they are now engineered to specific injury sites requirements to mimic native tissue characteristics and to support biofunctionality. Current strategies involve the use of bioinks loaded with cells and biomolecules of interest, without altering their functions, to deliver in situ the elements required to enhance healing/regeneration. The current research and trends in bioink development for 3D bioprinting purposes is overviewed herein.
Ab-initio energetics of graphite and multilayer graphene: stability of Bernal versus rhombohedral stacking
Authors: Paul Nery Jean , Calandra Matteo , Mauri Francesco 
Published: March 2021

Abstract
There has been a lot of excitement around the observation of superconductivity in twisted bilayer graphene, associated to flat bands close to the Fermi level. Such correlated electronic states also occur in multilayer rhombohedral stacked graphene (RG), which has been receiving increasing attention in the last years. In both natural and artificial samples however, multilayer stacked Bernal graphene (BG) occurs more frequently, making it desirable to determine what is their relative stability and under which conditions RG might be favored. Here, we study the energetics of BG and RG in bulk and also multilayer stacked graphene using first-principles calculations. It is shown that the electronic temperature, not accounted for in previous studies, plays a crucial role in determining which phase is preferred. We also show that the low energy states at room temperature consist of BG, RG and mixed BG–RG systems with a particular type of interface. Energies of all stacking sequences (SSs) are calculated for N = 12 layers, and an Ising model is used to fit them, which can be used for larger N as well. In this way, the ordering of low energy SSs can be determined and analyzed in terms of a few parameters. Our work clarifies inconsistent results in the literature, and sets the basis to studying the effect of external factors on the stability of multilayer graphene systems in first principles calculations.
Effect of different operating conditions on the conversion efficiency of triple-junction solar cell
Authors: Kumar Durgesh , Dheer Dharmendra Kumar , Kumar Lawrence 
Published: March 2021

Abstract
In this work, a theoretical study based on the detailed balance limit has been carried out for the performance evaluation of series-connected triple-junction solar cell. The effect of different operating conditions on the conversion efficiency of the solar cell is evaluated by numerical modeling using MATLAB. The performance has been measured for three standard spectra (AM0, AM1.5D and AM1.5 G) and over a range of temperatures (273 K–523 K) under varying solar concentration. It has been observed that changes in operating conditions have a significant impact on conversion efficiency. The conversion efficiency is found to be highly sensitive to spectrum distribution. By selecting the appropriate bandgap combination as per the incident spectrum, conversion efficiency is improved significantly. The effect of temperature on the conversion efficiency is mitigated by increasing the ratio of solar concentration. The finding of the present study indicates that appropriate combination of bandgap and solar concentration can be an effective tool to improve the conversion efficiency. This study can further be extended for higher generation solar cells to evaluate their performance.
Megadepth: efficient coverage quantification for BigWigs and BAMs
Authors: Wilks Christopher , Ahmed Omar , Baker Daniel N , Zhang David , Collado-Torres Leonardo , Langmead Ben 
Published: March 2021

Abstract

Motivation
A common way to summarize sequencing datasets is to quantify data lying within genes or other genomic intervals. This can be slow and can require different tools for different input file types.

Results
Megadepth is a fast tool for quantifying alignments and coverage for BigWig and BAM/CRAM input files, using substantially less memory than the next-fastest competitor. Megadepth can summarize coverage within all disjoint intervals of the Gencode V35 gene annotation for more than 19 000 GTExV8 BigWig files in approximately 1 h using 32 threads. Megadepth is available both as a command-line tool and as an R/Bioconductor package providing much faster quantification compared to the rtracklayer package.

Availability and implementation
https://github.com/ChristopherWilks/megadepth, https://bioconductor.org/packages/megadepth.

Supplementary information
Supplementary data are available at Bioinformatics online.
Super-delta2: an enhanced differential expression analysis procedure for multi-group comparisons of RNA-seq data
Authors: Cui Zihan , Liu Yuhang , Zhang Jinfeng , Qiu Xing 
Published: March 2021

Abstract

Motivation
We developed super-delta2, a differential gene expression analysis pipeline designed for multi-group comparisons for RNA-seq data. It includes a customized one-way ANOVA F-test and a post-hoc test for pairwise group comparisons; both are designed to work with a multivariate normalization procedure to reduce technical noise. It also includes a trimming procedure with bias-correction to obtain robust and approximately unbiased summary statistics used in these tests. We demonstrated the asymptotic applicability of super-delta2 to log-transformed read counts in RNA-seq data by large sample theory based on Negative Binomial Poisson (NBP) distribution.

Results
We compared super-delta2 with three commonly used RNA-seq data analysis methods: limma/voom, edgeR and DESeq2 using both simulated and real datasets. In all three simulation settings, super-delta2 not only achieved the best overall statistical power, but also was the only method that controlled type I error at the nominal level. When applied to a breast cancer dataset to identify differential expression pattern associated with multiple pathologic stages, super-delta2 selected more enriched pathways than other methods, which are directly linked to the underlying biological condition (breast cancer).

Conclusions
In conclusion, by incorporating trimming and bias-correction in the normalization step, super-delta2 was able to achieve tight control of type I error. Because the hypothesis tests are based on asymptotic normal approximation of the NBP distribution, super-delta2 does not require computationally expensive iterative optimization procedures used by methods such as edgeR and DESeq2, which occasionally have convergence issues.

Availability and implementation
Our method is implemented in a R-package, ‘superdelta2’, freely available at: https://github.com/fhlsjs/superdelta2.

Supplementary information
Supplementary data are available at Bioinformatics online.
Omixer: multivariate and reproducible sample randomization to proactively counter batch effects in omics studies
Authors: Sinke Lucy , Cats Davy , Heijmans Bastiaan T 
Published: March 2021

Abstract

Motivation
Batch effects heavily impact results in omics studies, causing bias and false positive results, but software to control them preemptively is lacking. Sample randomization prior to measurement is vital for minimizing these effects, but current approaches are often ad hoc, poorly documented and ill-equipped to handle multiple batches and outcomes.

Results
We developed Omixer—a Bioconductor package implementing multivariate and reproducible sample randomization for omics studies. It proactively counters correlations between technical factors and biological variables of interest by optimizing sample distribution across batches.

Availabilityand implementation
Omixer is available from Bioconductor at http://bioconductor.org/packages/release/bioc/html/Omixer.html. Scripts and data used to generate figures available upon request.

Supplementary information
Supplementary data are available at Bioinformatics online.